The main technologies in the manufacture of LCD displays. Secrets of modern lcd monitors

Andrey Borzenko

Experts predict that in just a few years display devices based on cathode ray tubes (CRTs) will take their place of honor in the museum of the history of technology. They will be replaced by the so-called flat panel displays (FPDs). Various technologies are used to create flat panel displays, but more than half of the FPD market is occupied by liquid crystal displays with an active matrix (Active-Matrix Liquid Crystal Display, AM-LCD). The principle of their work is well known. Under the influence of an electric field, the molecules of liquid crystals change the plane of polarization of the light passing through them. In other words, the LCD cell reflects or does not reflect light.

Such devices also steadily dominate in the computer market. This trend is likely to continue over the next few years.

Liquid crystal monitors

According to the estimates of Display Research, in the III quarter of 1998 about 50 thousand LCD-monitors were sold (recall that the market for CRT devices is estimated at 80-85 million units). 15 "monitors are considered the most popular with 39% of the market, followed by 14" monitors at 26%, and high quality 16 "monitors occupy only 10%. Until now, the most significant disadvantage of AM-LCD devices is their high price. But the situation is changing literally before our eyes. For example, this is how the price of the 15-inch VPA150 by ViewSonic Corporation (www.viewsonic.com) decreased: at the beginning of last year - $ 2200, in the spring - $ 1500, in the beginning of autumn - $ 1200. Some 15 "monitors are now under $ 1000. For example, the recommended retail price of a 15-inch PanaFlat LCD50s multimedia monitor from Panasonic Computer Peripheral (www.panasonic.com) is $ 999. It has a USB port and built-in one-watt stereo speakers. The screen provides a brightness of at least 250 nits with a contrast ratio of 200: 1. The viewing angle is 140 degrees.

Flat panel display is the future

The pricing situation is set to change drastically in early 2000, when several new LCD factories will be fully operational in Taiwan.

At the COMDEX'98 exhibition, almost all the leading manufacturers of screens and monitors presented new products based on AM-LCD. Of particular interest were 18-inch devices, for example, from Acer (www.acer.com), Eizo (www.eizo.com), NEC (www.nec.com), Nokia (www.nokia.com) and others. that the screen of an 18 "LCD monitor matches the viewable area of \u200b\u200ba 21" CRT device. For example, the 18.1-inch 800Xi model from Nokia Corporation (www.nokia.com) achieves a brightness of at least 250 nits with a contrast ratio of 200: 1. Its viewing angle is 170 degrees. At the same time, prices vary widely: from $ 2,500 at Acer to $ 3,600 at NEC.

Samsung Electronics (www.samsungelectronics.com) has unveiled improved versions of its 15- and 17-inch SyncMaster multimedia monitors at COMDEX'98. At just 2.5 inches thin and 150: 1 contrast, they deliver 200 nits of brightness and 120-degree viewing angle. These devices allow you to scale the image on the screen by factors of 2, 4 and 8. Monitors with a screen size of 18 inches and more are expected in the spring.

Compaq Corporation (www.compaq.com) has demonstrated a 15-inch LCD model with a digital interface that meets the VESA specification. These products will be offered on Presario home computers.

Further development of LCD is associated with an increase in the clarity and brightness of the image, an increase in the viewing angle and a decrease in screen thickness. Thus, at the stand of Toshiba Corporation (www.toshiba.com) one could see a new LCD-monitor, in the manufacture of which polycrystalline silicon was used. This technology allows the control chips to be placed directly on the glass substrate of the display, resulting in very thin devices. In addition, high resolution is provided on a relatively small screen. Thus, a 10.4-inch AM-LCD achieves a resolution of 1024x768 pixels.

LCD Panasonic LC90S

By the way, maximum dimensions LCD screens that can be industrially produced do not exceed 20 inches (although Sharp Corporation, www.sharp.co.jp, at one time showed a 40-inch LCD monitor with a screen obtained by joining two 29-inch panels). The fact is that just a year ago, the yield of suitable 10.4-inch screens was only 60-70%, and companies set a goal to reach 80-85%. Note that with an increase in screen size, the percentage of defects also increases.

Plasma Displays

Traditionally, the market for large screens (20 inches and above) has been dominated by the so-called Plasma Display Panel (PDP). Research and development in this area began in the early 60s. It is worth recalling that monochrome PDP screens have even been used in some laptop computers. Color PDP displays are produced today by companies such as Panasonic, Mitsubishi, Pioneer, NEC. Fujitsu Corporation (www.fujitsu.com) is deservedly considered the leader in this market sector. To improve the quality of the image and reduce the price, in particular, it has developed a special Alternate Lighting of Surfaces (ALiS) technology. This increased the brightness of PDP screens to 500 nits, contrast to 400: 1, and viewing angle to 160 degrees. Fujitsu's finished PDPs are used by Grundig and Philips for home theater applications.

PDP devices are a lot like a two-electrode vacuum tube. An inert gas (argon or neon) ionizes between two transparent electrodes. An electrically charged gas (plasma) produces ultraviolet radiation, which excites phosphorus droplets. The latter also emit visible light.

PDP Display Panasonic PT-42P

Color PDPs are well suited for digital HDTVs, but the price tag is still quite high: a 42-inch display costs $ 8,000-15,000.

A rather interesting symbiosis of liquid crystal and plasma technologies was implemented by Tektronix (www.tek.com). She suggested using plasma to control the rows and columns of an LCD screen. Subsequently, the license for this technology was acquired by Sony Corporation (www.sony.com), which in collaboration with Sharp was to begin production of such devices. According to Sony experts, the new approach enables displays with fast response time, good brightness and high resolution.

DLP devices

Displays based on Digital Light Processing (DLP) technology developed by Texas Instruments (www.ti.com) are especially widely used in military affairs: screens for helmets, aircraft cabins, command centers, etc. At the heart of DLP- technology is a DMD-cell (Digital Micromirror Device). In fact, it is a structure consisting of a static memory cell and a microscopic aluminum mirror that can be rotated in two directions at an angle of 10 degrees. Depending on its position, the mirror reflects or does not reflect light from external source, the result is projected onto big screen.

FED devices

Some companies have now begun to pay much attention to the creation of displays based on field emisson display (FED). Unlike LCD and DMD screens, which work with reflected light, FED panels generate light themselves, which makes them similar to CRT and plasma displays. However, unlike CRTs, which have only three electron guns, in FED devices, each pixel has its own electrode, so that the thickness of the panel does not exceed a few millimeters. Pixels are directly controlled like AM-LCD.

Several are currently working on the creation of FED monitors large companies: PixTech (www.pixtech.com), Candescent Technologies (www.candescent.com), Motorola (www.motorola.com), Raytheon (www.raytheon.com).

PixTech is already shipping 8.5- and 15-inch FED color panels with VGA resolution and 160-degree viewing angles.

The Candescent Technologies corporation is accelerating the preparation of production, and calls its technology FED-devices ThinCRT ("thin" CRT). The corporation's investors are companies such as Hewlett-Packard, Sony and Compaq. One of the problems faced by FED panel manufacturers is that a vacuum must be created between two glass plates separated by a narrow gap (i.e., evacuated). But in this case, the plates begin to attract each other, and this must be avoided. New Candescent Technologies technology is protected by at least three dozen patents. The production capacity of the company will allow by 2001 to produce about one million 14.1-inch FED-screens.

Motorola is implementing a project that is practically not advertised in the press, according to which it has completely re-equipped its plant in Arizona (USA), focusing it on the production of FED devices. The first products should appear early next year.

Electroluminescent Displays

The production of flat panel displays based on electroluminescent (ElectroLuminescent, EL) technology is developing less intensively. The fact that some substances (for example, zinc sulfide), when current passes through them, acquire the ability to emit visible light has been known since 1937.However, this effect was practically used in the manufacture of flat displays almost 50 years later, when thin-film EL materials appeared. ... According to some experts, EL displays have a number of advantages over LCD and even FED devices. This applies to both resolution and contrast, viewing angle and even power consumption. Nevertheless, Planar Systems (www.planar.com), a leading manufacturer of EL-panels, still supplies its products mainly for various medical equipment.

LEP Displays

Recently it was reported that the British company Cambridge Display Technology (CDT), which closely cooperates with the Japanese corporation Seiko-Epson, has demonstrated a monochrome display with a resolution of 800x236 pixels based on a Light-Emitting Polymer (LEP) film. Each pixel in a LEP display, as in an AM-LCD, is controlled by a thin film transistor. Epson inkjet printing was used to apply a polymer layer to the transistor matrix. CDT promises to release a color LEP display early next year.

The table shows the technical characteristics of LCD monitors offered on russian market.

LCD monitors in the Russian market

Manufacturing firm

Web site address

Screen diagonal size, inches

Point size, mm

Brightness, cd / m ^ 2 (nit)

Contrast

Horizontal viewing angle, degrees

Vertical viewing angle, degrees

Maximum resolution, points

Number of reproducible colors

Signal bandwidth, MHz

Horizontal frequency, kHz

Vertical frequency, Hz

Plug and play support

Built-in speakers

Video signal type

Energy consumption, W

Dimensions, mm

Samsung Electronics

SyncMaster 500 TFT

Analog

There is no data

Samsung Electronics

SyncMaster 520 TFT

Analog

There is no data

Samsung Electronics

SyncMaster 700 TFT

Analog

There is no data

Analogs

3.5 (without stand)

Analog

390х85х345 (plus stand)

Analog

446х83х432 (plus stand)

www.maginnovision.com

There is no data

There is no data

Analog

www.maginnovision.com

There is no data

There is no data

There is no data

There is no data

Analog

MultiSync LCD400V

There is no data

There is no data

Analog

There is no data

MultiSync LCD1510

There is no data

Analog

There is no data

MultiSync LCD2000

Analog

There is no data

Analog

There is no data

There is no data

There is no data

Analog

www.panasonic.ru

There is no data

Analog

www.panasonic.ru

Analog

There is no data

There is no data

There is no data

There is no data

Analog

www.mitsubishi-display.com

Analog

www.mitsubishi-display.com

Analog

www.viewsonic.com

There is no data

There is no data

Analog

There is no data

www.viewsonic.com

There is no data

There is no data

Digital

www.viewsonic.com

There is no data

Digital

Studioworks 500LC

There is no data

Analog

Studioworks 800LC

There is no data

Analog

There is no data

There is no data

Brilliance 151AX

www.monitors.philips.com

There is no data

Analog

There is no data

There is no data

There is no data

There is no data

There is no data

Analog

Not too long ago on user desktops great place occupied monitors with a cathode-ray tube. , and even more so smartphones, have just begun to appear on store shelves. Not much time passed, and bulky CRT monitors began to replace the first liquid crystal displays, and pockets were filled with all sorts of gadgets in which a screen was a necessary attribute.

Over time, screens began not only to add diagonals, but the display technology also changed, and in the characteristics of devices we increasingly began to notice such incomprehensible abbreviations as TN, TN-Film, IPS, Amoled, etc.

This article was written for ordinary consumers who want to choose a monitor, smartphone or tablet. Therefore, there will not be a lot of terms and deep implementation in this or that technology, but the operation of the screens will be described in an accessible language that is understandable to an ordinary user. I hope this article will shed light on new technologies in the field of information display, and also help people in the future choice of a device that will be pleasant to use.

LCD (Liquid crystal display), aka LCD (liquid crystal display), is built on the basis of liquid crystals, which change their position when voltage is applied to them. If you look closely at the monitor, you will notice that it consists of small dots - pixels. These are liquid crystals. In turn, each pixel consists of red, blue and green subpixels. When voltage is applied, the subpixels line up in a specific order and let light through them, thus forming a pixel of a specific color.

From a large number of such pixels, an image is formed on the screen of a monitor or other device.

TN and TN + Film matrices

The first mainstream monitors were equipped with TN matrices. This is the simplest, but at the same time, not the highest quality type of matrix. This technology is based on the fact that in the absence of voltage, the subpixels pass light through themselves, forming on the screen white point... When voltage is applied to subpixels, they line up in a specific order, forming a pixel of a given color.

Due to the fact that the standard pixel color, in the absence of voltage, is white, this type of matrix does not have the best color reproduction. Colors appear dull and faded, while blacks appear more dark gray.

Another major disadvantage of the TN matrix is \u200b\u200bthe small viewing angles. In part, they tried to cope with this problem by improving the TN technology to TN + Film, using an additional layer applied to the screen. The viewing angles became larger, but still remained far from ideal. At the moment TN + Film matrices have completely replaced TN.

But apart from the disadvantages, such matrices have their own advantages. These include fast response times and relatively inexpensive production costs.

Considering all the advantages and disadvantages, we can say that if you need an inexpensive monitor for occasional use in working with documents or for surfing the Internet, then monitors with TN + Film matrices are perfect for these needs.

IPS matrices

The main difference from IPS technology from TN is the arrangement of subpixels in the absence of voltage. They are positioned perpendicular to each other, forming a black dot. Thus, the screen remains black when calm. This gives an advantage in color rendering over screens with TN matrices. The colors on the screen look bright, rich, and the black remains really black. When voltage is applied, the pixels change their color. Taking this feature into account, owners of smartphones and tablets with IPS screens can be advised to use dark color schemes and wallpapers on the desktop, then the smartphone will last a little longer on battery power.

Also a nice feature of IPS matrices are the large viewing angles. On most screens, they are 178 °. For monitors, and especially for smartphones and tablets, this feature is important when a user chooses a device.

But, of course, there are also disadvantages. The main disadvantage is the longer screen response time. This affects the display in dynamic pictures such as games and movies. In modern IPS panels, the response time has been improved, so now this drawback is not so critical.

Another feature of IPS-screens is their high cost compared to TN. But recently, the price of IPS panels has dropped and became available to most users.

Thus, it is better to choose phones and tablets with IPS matrices, and then the user will receive great aesthetic pleasure from using the device. The matrix for the monitor is not so critical, but if possible, it is recommended to pay attention to modern IPS monitors.

AMOLED screens

In the last few years smartphones have started to be equipped with AMOLED displays and at the same time advertise such phones very much to buyers. So let's figure out what the PR managers of companies are trying to convey to us, and what is in their words a common advertising trick.

The technology for creating AMOLED matrices is based on active LEDs, which start to glow and display color when voltage is applied to them. What does it give us? And this gives us quite contradictory features.
Let's start with color rendering. The saturation and contrast of such screens are off scale. Colors are displayed so vividly that some users may experience eye strain after prolonged use of their smartphone. But black color is displayed even more black than even in IPS-matrices.

These vibrant colors have a huge impact on the power consumption of the display. As with IPS, displaying black requires less power than displaying a specific color, and even more so white. But the difference in power consumption between displaying black and white in AMOLED screens is much larger. Displaying white requires several times more energy than displaying black.

Another negative feature is "picture memory". With prolonged display of a static image, traces may remain on the screen, and this, in turn, affects the quality of information display.

Also, due to their rather high cost, AMOLED screens are still used only in smartphones. Monitors based on this technology are unreasonably expensive.

Conclusion

At the end of the article, I would like to say that the perception of the image is quite subjective for each user. For some, a TN matrix will be quite enough, and someone will change dozens of monitors until they find their ideal. Thus, despite all the technologies for creating displays, the choice always remains with the user and depends on his individual perception of the picture on the screen. You can read how the screens work in touch mode.

Monitors

When someone asks us for advice on which computer to buy, we always emphasize that in no case should you save on a monitor. The monitor cannot be upgraded. It is purchased once for long term use. It is through the monitor that we perceive all the visual information from the computer. It doesn't matter if you work with an accounting program, write letters, play games, manage a server - you always use a monitor. Your health directly depends on the quality and safety of the monitor - first of all, your eyesight. So how do you choose a monitor? So that it is convenient and safe to work, so that the head does not hurt, and the eyes do not get tired, so that it is comfortable to play and work? We will try to answer all these questions in this article.

It is clear that there are a lot of criteria that determine the correct choice of a monitor. Moreover, different monitors are chosen for different purposes. The cost of monitors can be very different, their capabilities and technical parameters are also different. We will try to tell you about the types of monitors and give recommendations on how to choose a monitor exactly for your needs.

If you are going to buy a new computer or decide to upgrade, then before choosing the most modern video card, or the fastest hDD, or ... whatever, think about the monitor first. It is in front of the monitor that you will spend a lot of time, having fun or working. Better to buy a simpler video accelerator to upgrade later, but you cannot upgrade your monitor. You can only throw it out and buy a new one. Or sell for ridiculous money. That is why you cannot save on the monitor, because you are saving on your health.

Of course, when choosing a monitor, we, willy-nilly, focus on advertising. But, for obvious reasons, in advertising, manufacturers focus on those characteristics of the monitor that are beneficial to the manufacturers. We will try to give you recommendations on what to pay special attention to and what characteristics you should know exactly. We will also look at the advantages and disadvantages different types monitors ranging from traditional CRT monitors to ultramodern LCD monitors. We will pay special attention to parameters such as supported resolutions and refresh rates, compliance with security standards, and support for power saving modes. And much more.

So, enough of the prefaces, let's start.

Today, the most common type of monitor is CRT (Cathode Ray Tube) monitors. As the name implies, all such monitors are based on a cathode ray tube, but this is a literal translation, it is technically correct to say "cathode ray tube" (CRT). The technology used in this type of monitor was created many years ago and was originally created as a special instrument for measuring alternating current, in other words, for an oscilloscope. The development of this technology, applied to the creation of monitors, in recent years has resulted in the production of larger and larger screens with high quality and low cost. Today it is very difficult to find a 14 "monitor in a store, and after all three or four years ago it was the standard. Today, 15" monitors are standard, and there is a clear trend towards 17 "screens. Soon 17" monitors will become a standard device, especially in light of the significant lower prices for them, and on the horizon there are already 19 "monitors and more.

Let's consider the principles of CRT monitors. A CRT or CRT monitor has a glass tube inside of which there is a vacuum, i.e. all air is removed. On the front side, the inner part of the glass of the tube is coated with a phosphor (Luminofor). Rather complex compositions based on rare-earth metals - yttrium, erbium, etc. are used as phosphors for non-ferrous CRTs. A phosphor is a substance that emits light when bombarded with charged particles. Note that sometimes the phosphor is called phosphorus, but this is not true, since the phosphor used in the CRT coating has nothing to do with phosphorus. Moreover, phosphorus "glows" as a result of interaction with atmospheric oxygen during oxidation to P 2 O 5 and is short in time (by the way, white phosphorus is a strong poison). To create an image in a CRT monitor, an electron gun is used, which emits a stream of electrons through a metal mask or grating onto the inner surface of the glass screen of the monitor, which is covered with multi-colored phosphor dots. The flow of electrons on the way to the front of the tube passes through the intensity modulator and the accelerating system, operating on the principle of potential difference. As a result, electrons acquire a large energy, part of which is spent on the glow of the phosphor. Electrons fall on the phosphor layer, after which the energy of the electrons is converted into light, i.e. the flow of electrons causes the dots of the phosphor to glow. These glowing dots of the phosphor form the image you see on your monitor. As a rule, three electron guns are used in a color CRT monitor, in contrast to one gun used in monochrome monitors, which are now practically not produced and are of little interest to anyone.

We all know or have heard that our eyes react to the primary colors: red (Red), green (Green) and blue (Blue) and their combinations, which create an infinite number of colors.

The phosphor layer covering the front of the CRT is made up of very small elements (so small that human eye cannot always distinguish between them). These phosphor elements reproduce the primary colors, in fact, there are three types of multi-colored particles, whose colors correspond to the basic RGB colors (hence the name of the group of phosphor elements - triad).

The phosphor begins to glow, as mentioned above, under the influence of accelerated electrons, which are created by three electron guns. Each of the three guns corresponds to one of the primary colors and sends a beam of electrons to different phosphor particles, whose luminescence by the primary colors with different intensities is combined, and, as a result, an image with the required color is formed. For example, if you activate red, green and blue phosphor particles, then their combination will form a white color.

To control the cathode-ray tube, control electronics are also needed, the quality of which largely determines the quality of the monitor. By the way, it is the difference in the quality of control electronics created by different manufacturers that is one of the criteria that determine the difference between monitors with the same cathode-ray tube. So, to repeat: each gun emits an electron beam (or stream, or beam), which affects phosphor elements of different colors (green, red, or blue). It is understood that the electron beam destined for red phosphor elements should not affect the green or blue phosphor. To achieve such an action, a special mask is used, whose structure depends on the type of kinescopes from different manufacturers, which ensures the discreteness (rasterization) of the image. CRTs can be divided into two classes - three-beam with a delta-shaped arrangement of electron guns and with a planar arrangement of electron guns. These tubes use slot and shadow masks, although it would be more accurate to say that they are all shadows. At the same time, tubes with a planar arrangement of electron guns are also called self-aligning kinescopes, since the effect of the Earth's magnetic field on three planar beams is practically the same, and when the position of the tube relative to the Earth's field changes, additional adjustments are not required.

So, the most common types of masks are shadow, and they are of two types: "Shadow Mask" and "Slot Mask".

SHADOW MASK

The shadow mask is the most common type of mask for CRT monitors. The shadow mask consists of a metal mesh in front of a part of the glass tube with a phosphor layer. Typically, most modern shade masks are made from Invar (an alloy of iron and nickel). The holes in the metal mesh work like a sight (albeit not precise) to ensure that the electron beam hits only the required phosphor elements, and only in certain areas. The shadow mask creates a lattice with homogeneous points (also called triads), where each such point consists of three luminous elements of the primary colors - green, red and blue - which glow with different intensities under the influence of beams from electron guns. By varying the current of each of the three electron beams, an arbitrary color of an image element formed by a triad of dots can be achieved.

The minimum distance between phosphor elements of the same color is called dot pitch and is an index of image quality. Dot pitch is usually measured in millimeters (mm). The smaller the dot step value, the higher the quality of the image displayed on the monitor.

The shadow mask is used in most modern monitors - Hitachi, Panasonic, Samsung, Daewoo, LG, Nokia, Viewsonic.

SLOT MASK

The slot mask is a technology widely used by NEC under the name "CromaClear". In practice, this solution is a combination of the two technologies described above. In this case, the phosphor elements are arranged in vertical elliptical cells, and the mask is made of vertical lines. In fact, the vertical stripes are divided into elliptical cells that contain groups of three phosphor elements in three primary colors. The minimum distance between two cells is called a slot pitch. The lower the slot pitch value, the better the image quality on the monitor.

The slit mask is used, in addition to monitors from NEC (where the cells are elliptical), in Panasonic monitors with a PureFlat tube (formerly called PanaFlat). By the way, the very first flat-tube monitor was a Panasonic with a PanaFlat tube. In general, the topic of monitors with flat tubes deserves a separate article. In this article, we will only touch on this topic a little:

LG uses a 0.24 pitch Flatron slit tube in its monitors. This technology has nothing to do with Trinitron.

Note that Samsung's Infinite Flat Tube (DynaFlat series) does not use a slit mask, but a regular shadow mask.

Sony has developed its own flat tube technology, the FD Trinitron. Of course, using an aperture grille, but not a conventional one, but with a constant step.

Mitsubishi has developed the DiamondTron NF technology. Apparently, there is no connection with Sony's FD Trinitron. At the same time, a variable-pitch aperture grating is used in DiamondTron NF tubes.

There is another type of tube that uses the "Aperture Grill" (aperture, or shadow grill). These tubes became known as Trinitron and were first introduced to the market by Sony back in 1982. The aperture grating tubes use the original technology, where there are three beam guns, three cathodes and three modulators, but there is one common focusing. Sometimes the technical literature says that there is only one gun. However, the question of the number of electron guns is not so fundamental. We will be of the opinion that there are three electron guns, since it is possible to control the current of all three beams independently. On the other hand, we can say that the electron gun is one, but three-beam. Sony itself uses the term "unitized gun", but this is due only to the cathode structure.

Note that there is a misconception that a single electron beam gun is used in aperture grating tubes, and the color is created by time multiplexing. In fact, this is not so, and we gave the explanation above.

Another misconception, sometimes encountered, is that a single-beam chromatron is used in aperture grating tubes. That is, there is one gun with a variable beam energy and a two-layer phosphor. While the beam energy is low, one phosphor (for example, red) glows. As the energy rises, another layer (for example, green) starts to glow, which gives a yellow color. If the energy becomes even higher, then the electrons fly past the first layer without exciting it and a green color is obtained. Such pipes were used 20-30 years ago and are now practically extinct.

APERTURE GRILLE

An aperture grill is a type of mask used by different manufacturers in their technologies to produce CRTs that have different names but have the same essence, such as Sony's Trinitron technology or Mitsubishi's Diamondtron technology. This solution does not include a metal grid with holes, as in the case of the shadow mask, but has a grid of vertical lines. Instead of dots with phosphor elements of three primary colors, the aperture grille contains a series of filaments consisting of phosphor elements arranged in vertical stripes of three primary colors. Such a system provides high contrast images and good color saturation, which together provide high quality monitors with tubes based on this technology. The mask used in Sony tubes (Mitsubishi, ViewSonic) is a thin foil on which thin vertical lines are scratched. It rests on a horizontal (one in 15 ", two in 17", three or more in 21 ") wire, the shadow of which you can see on the screen. This wire is used to damp vibrations and is called damper wire. , especially with a light background of the image on the monitor.Some users do not like these lines in principle, while others, on the contrary, are happy and use them as a horizontal ruler.

The minimum distance between phosphor stripes of the same color is called strip pitch and is measured in millimeters (mm). The lower the strip pitch value, the better the image quality on the monitor.

The aperture grille is used in monitors from Viewsonic, Radius, Nokia, LG, CTX, Mitsubishi, in all monitors from SONY.

Note that one cannot directly compare the pitch size for different types of tubes: the pitch of the points (or triads) of a tube with a shadow mask is measured diagonally, while the pitch of the aperture grating, otherwise called the horizontal pitch of the points, is measured horizontally. Therefore, with the same dot pitch, a tube with a shadow mask has a higher point density than a tube with an aperture grating. For example: 0.25 mm strip pitch is approximately equivalent to 0.27 mm dot pitch.

Both types of pipes have their own advantages and supporters. Tubes with a shadow mask give a more accurate and detailed image because the light passes through the holes in the mask with sharp edges. Therefore, it is good to use monitors with such CRTs for intensive and long-term work with texts and small graphic elements, for example, in CAD / CAM applications. Tubes with an aperture grille have a more delicate mask, it obscures the screen less, and allows you to get a brighter, more contrasting image in saturated colors. Monitors with these tubes are well suited for desktop publishing and other color-oriented applications. In CAD systems, monitors with a tube that uses an aperture grille are disliked not because they reproduce fine details worse than tubes with a shadow mask, but because the Trinitron-type monitor screen is flat vertically and convex horizontally, i.e. ... has a dedicated direction.

As we already mentioned, in addition to the cathode-ray tube inside the monitor, there is also control electronics that processes the signal coming directly from your PC's video card. These electronics must optimize the amplification of the signal and control the operation of the electron guns, which initiate the glow of the phosphor, which creates the image on the screen. The image displayed on the monitor screen looks stable, although, in fact, it is not. The image on the screen is reproduced as a result of a process during which the glow of the phosphor elements is initiated by an electron beam passing sequentially line by line in the following order: from left to right and from top to bottom on the monitor screen. This process happens very quickly, so it seems to us that the screen is constantly lit. In the retina of our eyes, the image is stored for about 1/20 of a second. This means that if the electron beam moves slowly across the screen, we can see this movement as a separate moving bright point, but when the beam begins to move, quickly tracing a line on the screen at least 20 times per second, our eyes will not see the moving point, but will see only a uniform line on the screen. If we now make the beam run sequentially along many horizontal lines from top to bottom in less than 1/25 of a second, we will see an evenly lit screen with a little flicker. The beam itself will move so fast that our eye will not be able to notice it. The faster the electron beam travels across the entire screen, the less flickering the picture will be. It is believed that such flicker becomes almost imperceptible at a frame repetition rate (beam passes through all the image element) of about 75 per second. However, this value is somewhat dependent on the size of the monitor. The fact is that the peripheral regions of the retina contain light-sensitive elements with less inertia. Therefore, flickering on monitors with large viewing angles becomes noticeable at high frame rates. The ability of the control electronics to form small image elements on the screen depends on the bandwidth. The bandwidth of a monitor is proportional to the number of pixels from which your computer's graphics card forms an image. We will come back to the bandwidth of the monitor later.

Now let's move on to another type of monitors - LCD.

LCD Monitors

LCD (Liquid Crystal Display) are made from a substance that is in a liquid state, but has some of the properties inherent in crystalline bodies. In fact, these are liquids with anisotropy of properties (in particular, optical) related to the ordering in the orientation of molecules. Liquid crystals were discovered a long time ago, but they were originally used for other purposes. Molecules of liquid crystals under the influence of electricity can change their orientation and, as a result, change the properties of the light beam passing through them. Based on this discovery and as a result of further research, it became possible to find a relationship between an increase in electrical voltage and a change in the orientation of the crystal molecules to ensure imaging. Liquid crystals were first used in displays for calculators and in quartz watches, and then they began to be used in monitors for laptop computers. Today, as a result of progress in this area, LCD monitors for desktop computers are becoming more common. Further we will focus only on traditional LCD monitors, the so-called Nematic LCD.

An LCD monitor screen is an array of small segments (called pixels) that can be manipulated to display information. An LCD monitor has multiple layers, where the key role is played by two panels made of sodium-free and very pure glass material called a substrate or substrate, which actually contain a thin layer of liquid crystals between them. The panels have grooves that guide the crystals to give them a special orientation. The grooves are located in such a way that they are parallel in each panel, but perpendicular between the two panels. Longitudinal grooves are obtained by placing thin films of transparent plastic on the glass surface, which are then processed in a special way. Contacting the grooves, molecules in liquid crystals are oriented in the same way in all cells. Molecules of one of the types of liquid crystals (nematics) in the absence of voltage rotate the vector of the electric (and magnetic) field in such a light wave by a certain angle in the plane perpendicular to the beam propagation axis. The application of grooves on the glass surface makes it possible to ensure the same rotations of the plane of polarization for all cells. The two panels are very close to each other. The liquid crystal panel is illuminated by a light source (depending on where it is located, liquid crystal panels work to reflect or transmit light). The plane of polarization of the light beam is rotated 90 ° when passing one panel.

When an electric field appears, the liquid crystal molecules are partially aligned along the field, and the angle of rotation of the plane of polarization of light becomes different from 90 degrees.

The rotation of the plane of polarization of the light beam is imperceptible to the eye, so it became necessary to add two more layers to the glass panels, which are polarizing filters. These filters transmit only that component of the light beam, for which the polarization axis corresponds to the given one. Therefore, when passing through the polarizer, the light beam will be attenuated depending on the angle between its plane of polarization and the axis of the polarizer. In the absence of voltage, the cell is transparent for the following reason: the first polarizer transmits only light with the corresponding polarization vector. Thanks to liquid crystals, the polarization vector of light is rotated, and by the time the beam passes to the second polarizer, it is already rotated so that it passes through the second polarizer without problems. In the presence of an electric field, the rotation of the polarization vector occurs at a smaller angle, thereby the second polarizer becomes only partially transparent for radiation. If the potential difference is such that there is no rotation of the plane of polarization in liquid crystals at all, then the light beam will be completely absorbed by the second polarizer, and the screen will appear black when illuminated from the front from the front (the backlight rays are completely absorbed in the screen). If you place a large number of electrodes that create different electric fields in separate places of the screen (cell), then it will be possible, with proper control of the potentials of these electrodes, to display letters and other image elements on the screen. The electrodes are placed in transparent plastic and can be of any shape. Technological innovations have made it possible to limit their size to the size of a small dot, respectively, on the same screen area, more electrodes can be placed, which increases the resolution of the LCD monitor and allows us to display even complex images in color. To display a color image, a monitor backlight is required from the back so that light is generated at the back of the LCD. This is necessary so that a good quality image can be observed even if the environment is not light. The color is obtained by using three filters that separate three main components from the emission of a white light source. The combination of three primary colors for each point or pixel of the screen makes it possible to reproduce any color.

In fact, in the case of color, there are several possibilities: you can make several filters one after another (which leads to a small fraction of transmitted radiation), you can use the property of a liquid crystal cell - when the electric field strength changes, the angle of rotation of the radiation polarization plane changes differently for light components with different wavelengths. This feature can be used to reflect (or absorb) radiation of a given wavelength (the problem is the need to accurately and quickly change the voltage). Which mechanism is used depends on the specific manufacturer. The first method is simpler, the second is more effective.

The first LCD displays were very small, about 8 ", while today they have reached 15" sizes for use in laptops, and 19 "and larger LCD monitors are produced for desktop computers. The increase in size is followed by an increase in resolution, which results in the appearance of new problems that have been solved with the help of emerging special technologies, we will describe all this below. One of the first challenges was the need for a standard to define display quality at high resolutions. The first step towards the goal was to increase the angle of rotation of the plane of polarization of light in crystals from 90 ° to 270 ° using STN technology.

STN technology

STN is an acronym for Super Twisted Nematic. STN technology allows to increase the torsion angle (twist angle) of the crystal orientation inside LCD display from 90 ° to 270 °, which provides better image contrast when increasing the size of the monitor. STN cells are often used in pairs. This is called DSTN (Double Super Twisted Nematic) and is very popular among laptop monitors using passive matrix displays where DSTN provides contrast enhancement when displaying images in color. Two STN cells are positioned together so that they move in different directions as they rotate. STN cells are also used in TSTN (Triple Super Twisted Nematic) mode, when two thin layers of plastic film (polymer film) are added to improve the color rendering of color displays or to ensure good quality monochrome monitors. We mentioned the term "passive matrix", let's make an explanation. The term "passive matrix" is a result of dividing the monitor into points, each of which, thanks to the electrodes, can set the orientation of the plane of polarization of the beam independently of the others, so that as a result, each such element can be individually illuminated to create an image. The matrix is \u200b\u200bcalled passive, because the technology for creating LCD displays that we just described cannot provide a quick change of information on the screen. The image is formed line by line by sequentially applying a control voltage to individual cells, making them transparent. Due to the rather large electrical capacity of the cells, the voltage across them cannot change quickly enough, so the picture is updated slowly. The display just described has many disadvantages in terms of quality, because the image is not displayed smoothly and shakes on the screen. The low speed of change in the transparency of the crystals does not allow for the correct display of moving images. We must also take into account the fact that there is some mutual influence between adjacent electrodes, which can appear in the form of rings on the screen.

Dual Scan Screens

To solve some of the above problems, special tricks are used, for example, splitting the screen into two parts and applying double scanning at the same time of both parts, as a result, the screen is twice regenerated, and the image does not shake and is displayed smoothly.

Also, the best results in terms of stability, quality, resolution, smoothness and brightness of the image can be achieved using screens with an active matrix, which, however, are more expensive. The active matrix uses separate amplifying elements for each screen cell, which compensate for the effect of cell capacitance and significantly reduce the time of changing their transparency. The active matrix has many advantages over the passive matrix. For example, the best brightness and the ability to look at the screen even with a deviation of up to 45 ° or more (i.e., with a viewing angle of 120 ° -140 °) without compromising image quality, which is impossible in the case of a passive matrix, which allows you to see a high-quality image only from the front position in relation to the screen. Note that expensive models of LCD-monitors with an active matrix provide a viewing angle of 160 °, and there is every reason to assume that the technology will continue to improve. In the case of an active matrix, you can display moving images without visible jitter, since the response time of a display with an active matrix is \u200b\u200babout 50 ms versus 300 ms for a passive matrix, and the contrast quality is better than that of CRT monitors. It should be noted that the brightness individual element the screen remains unchanged throughout the entire time interval between image updates, and does not represent a short pulse of light emitted by the phosphor element of the CRT-monitor immediately after the passage of the electron beam along this element. That is why a refresh rate of 60 Hz is sufficient for LCD monitors. Thanks to better quality For imaging, this technology is also used in desktop monitors to create compact monitors that are less hazardous to our health.

In the future, we should expect an increase in the invasion of LCD monitors in the market due to the fact that with the development of technology, the final price of devices is decreasing, which allows more users to buy new products. The functionality of an active matrix LCD is almost the same as a passive matrix display. The difference lies in the electrode array that drives the display's liquid crystal cells. In the case of a passive matrix, different electrodes receive electric charge by a cyclic method during the line-by-line regeneration of the display, and as a result of the discharge of the capacities of the elements, the image disappears, since the crystals return to their original configuration. In the case of an active matrix, a storage transistor is added to each electrode that can store digital information (binary values \u200b\u200b0 or 1), and as a result the image is stored until another signal arrives. The problem of delaying image fading in passive matrices is partially solved by using a larger number of liquid crystal layers to increase passivity and reduce displacements, but now, when using active matrices, it became possible to reduce the number of liquid crystal layers. Storage transistors must be made of transparent materials, which will allow the light beam to pass through them, which means that the transistors can be located on the back of the display, on a glass panel that contains liquid crystals. For these purposes, plastic films are used, called "Thin Film Transistor" (or simply TFT).

Thin Film Transistor (TFT), i.e. a thin film transistor, really very thin, its thickness is in the range from 1/10 to 1/100 micron. The technology for creating TFTs is very complex, and there are difficulties in achieving an acceptable percentage of products due to the fact that the number of used transistors is very large. Note that a monitor that can display an image with a resolution of 800x600 pixels in SVGA mode and with only three colors has 1,440,000 individual transistors. Manufacturers set standards for the maximum number of transistors that can be inoperative in an LCD display. True, each manufacturer has its own opinion about how many transistors may not work.

Let's briefly describe the resolution of LCD monitors. This resolution is one, and it is also called native, it corresponds to the maximum physical resolution of CRT monitors. It is in native resolution that the LCD monitor reproduces the image best. This resolution is determined by the pixel size, which is fixed on the LCD monitor. For example, if the LCD monitor has a native resolution of 1024x768, then this means that each of the 768 lines has 1024 electrodes, read: pixels. At the same time, it is possible to use a resolution lower than native. There are two ways to do this. The first is called "Centering"; the essence of the method is that only the number of pixels is used to display the image, which is necessary to form an image with a lower resolution. As a result, the image is not full screen, but only in the middle. All unused pixels remain black, i.e. a wide black border appears around the image. The second method is called "Expansion". Its essence is that when reproducing an image with a lower than native resolution, all pixels are used, i.e. the image fills the entire screen. However, because the image is stretched to fill the entire screen, slight distortion occurs and sharpness is impaired. Therefore, when choosing an LCD monitor, it is important to clearly know which resolution you need.

Separately, it is worth mentioning the brightness of LCD monitors, since there are no standards yet for determining whether an LCD monitor has sufficient brightness. At the same time, in the center, the brightness of an LCD monitor can be 25% higher than at the edges of the screen. The only way to determine if the brightness of a particular LCD monitor is right for you is to compare its brightness with other LCD monitors.

And the last parameter to be mentioned is contrast. The contrast of an LCD monitor is defined as the ratio of brightness between the brightest white and the darkest black. A good contrast ratio is considered to be 120: 1, which ensures the reproduction of vibrant saturated colors. A contrast ratio of 300: 1 and above is used when accurate black-and-white halftones are required. But, as with brightness, there are no standards yet, so your eyes are the main determining factor.

It is worth noting such a feature of some LCD monitors as the ability to rotate the screen itself by 90 °, with simultaneous automatic image rotation. As a result, for example, if you are doing typesetting, now an A4 sheet can be completely fitted on the screen without the need to use vertical scrolling to see all the text on the page. True, among CRT monitors there are also models with this capability, but they are extremely rare. In the case of LCD monitors, this function becomes almost standard.

The advantages of LCD-monitors include the fact that they are really flat in the literal sense of the word, and the image created on their screens is clear and rich in colors. Lack of distortion on the screen and a lot of other problems inherent in traditional CRT monitors. We add that the power consumption and dissipation of LCD monitors is significantly lower than that of CRT monitors. Below is a summary table comparing Active Matrix LCDs to CRT monitors:

Options	Active Matrix LCD monitor	CRT monitor
Resolution	One resolution with fixed pixel size. It can be used optimally only at this resolution; higher or lower resolution may be used depending on the supported expansion or compression functions, but these are not optimal.	Various resolutions are supported. You can use your monitor for optimal use at all supported resolutions. The limitation is imposed only by the acceptability of the regeneration frequency.
Refresh rate	The optimal frequency is 60 Hz, which is enough to avoid flickering.	Only at frequencies above 75 Hz is there no clearly noticeable flicker.
Color display accuracy	True Color is supported and the desired color temperature is simulated.	True Color is supported and at the same time there are a lot of color calibration devices on the market, which is a definite plus.
Image formation	The image is formed by pixels, the number of which depends only on the specific resolution of the LCD panel. The pixel pitch depends only on the size of the pixels themselves, but not on the distance between them. Each pixel is individually shaped for superior focus, clarity and clarity. The image is more consistent and smoother.	Pixels are formed by a group of points (triads) or stripes. The step of a point or line depends on the distance between points or lines of the same color. As a result, the clarity and clarity of the image is highly dependent on the size of the dot or line pitch and on the quality of the CRT.
Viewing angle	Currently, the standard viewing angle is 120 o and above; with the further development of technology, an increase in the viewing angle should be expected.	Excellent visibility from any angle.
Power consumption and radiation	There is practically no dangerous electromagnetic radiation. Power consumption is about 70% lower than standard CRT monitors.	Electromagnetic radiation is always present, but the level depends on whether the CRT d complies with a safety standard. Operating energy consumption at 80 W.
Monitor interface	Digital interface, however most LCD monitors have a built-in analog interface for connecting to the most common analog outputs of video adapters.	Analog interface.
Scope of application	Standard display for mobile systems... Recently, it has begun to conquer its place as a monitor for desktop computers. Ideal as a display for computers, i.e. for working on the Internet, with word processors, etc.	Standard desktop monitor. They are extremely rarely used in mobile form. Ideal for displaying videos and animations.

The main challenge in the development of LCD technology for the desktop sector seems to be the size of the monitor, which affects its cost. As displays grow in size, production capacity decreases. Currently, the maximum diagonal of LCD-monitor suitable for mass production reaches 20 ", and recently some developers have introduced 43" models and even 64 "models of TFT-LCD-monitors ready for commercial production.

But it looks like the battle for market space between CRTs and LCD monitors is already a foregone conclusion. And not in favor of CRT monitors. The future, apparently, is still for LCD-monitors with an active matrix. The outcome of the battle became clear after IBM announced the release of a monitor with a matrix having 200 pixels per inch, that is, with a density twice that of CRT monitors. According to experts, the image quality differs in the same way as when printing on dot matrix and laser printers. Therefore, the question of the transition to the widespread use of LCD-monitors is only in their price.

However, there are other technologies that are created and developed by different manufacturers, and some of these technologies are called PDP (Plasma Display Panels), or simply "plasma", and FED (Field Emission Display). Let's talk a little about these technologies.

Plasma

Major manufacturers such as Fujitsu, Matsushita, Mitsubishi, NEC, Pioneer and others have already begun producing plasma monitors with a diagonal of 40 "or more, and some models are already ready for mass production. Plasma monitors work very similar to neon lamps that are made in the form of a tube filled with an inert gas of low pressure. Inside the tube is placed a pair of electrodes between which an electric discharge is ignited and a glow is generated. Plasma screens are created by filling the space between two glass surfaces with an inert gas, such as argon or neon. Then small transparent ones are placed on the glass surface. Electrodes, to which a high-frequency voltage is applied. Under the action of this voltage, an electrical discharge occurs in the gas region adjacent to the electrode. The gas discharge plasma emits light in the ultraviolet range, which causes the phosphor particles to glow in the range visible to humans. every pixel on the screen works like a regular fluorescent lamp (in other words, a fluorescent lamp). High brightness and contrast along with no jitter are great advantages of these monitors. In addition, the angle with respect to the normal at which a normal image can be seen on plasma monitors is substantially greater than 45 ° in the case of LCD monitors. The main disadvantages of this type of monitors are rather high power consumption, which increases with increasing monitor diagonal, and low resolution due to the large pixel size. In addition, the properties of the phosphor elements quickly deteriorate and the screen becomes less bright, so the lifespan of plasma monitors is limited to 10,000 hours (this is about 5 years for office use). Due to these limitations, such monitors are used so far only for conferences, presentations, information boards, i.e. where large screen sizes are required to display information. However, there is every reason to believe that the existing technological limitations will soon be overcome, and with a decrease in cost, this type of device can be successfully used as television screens or monitors for computers. Such TVs already exist, they have a large diagonal, very thin (compared to standard TVs) and cost a lot of money - $ 10,000 and more.

A number of leading LCD and Plasma screen developers are jointly developing PALC (Plasma Addressed Liquid Crystal) technology, which should combine the advantages of plasma and active matrix LCD screens.

FED

The technologies used to create monitors can be divided into two groups: 1) monitors based on light emission, for example, traditional CRT monitors and plasma monitors, i.e. these are devices whose screen elements emit light into external world and 2) broadcast-type monitors such as LCD monitors. One of the best technological trends in the field of creating monitors, which combines the features of both technologies described above, is the FED (Field Emission Display) technology. FED monitors are based on a process that is slightly similar to that used in CRT monitors, as both methods use a phosphor that is emitted by an electron beam. The main difference between CRT and FED monitors is that CRT monitors have three guns that emit three electron beams sequentially scanning a panel covered with a phosphor layer, and a FED monitor uses many small electron sources located behind each element of the screen. and they are all located in a shallower space than the CRT requires. Each source of electrons is controlled by a separate electronic element, just like in LCD monitors, and each pixel then emits light due to the action of electrons on phosphor elements, just like in traditional CRT monitors. That being said, FED monitors are very thin.

There is another new and, in our opinion, promising technology, this LEP (Light Emission Plastics), or luminous plastic. You can read about it in a special article: LEP Monitors

Sizes-Resolutions-Refresh Rate

Now it's logical to move on to sizes, resolutions and refresh rates. In the case of monitors, size is one of the key parameters. The monitor requires space for its installation, and the user wants to work comfortably with the required resolution. In addition, it is essential that the monitor maintains an acceptable refresh rate or refresh rate. At the same time, all three parameters - size, resolution and refresh rate - should always be considered together if you want to make sure of the quality of the monitor that you decide to buy, because all these parameters are rigidly interconnected, and their values \u200b\u200bmust match.

Monitor resolution (or resolution) is related to the size of the displayed image and is expressed in the number of dots in the width (horizontal) and height (vertical) of the displayed image. For example, if a monitor is said to have a resolution of 640x480, this means that the image consists of 640x480 \u003d 307200 dots in a rectangle whose sides are 640 dots wide and 480 dots high. This explains why a higher resolution corresponds to displaying a more substantial (detailed) image on the screen. It is clear that the resolution must match the size of the monitor, otherwise the image will be too small to see it. The ability to use a particular resolution will depend on various factors, including the capabilities of the monitor itself, the capabilities of the graphics card, and the amount of available video memory, which limits the number of colors displayed.

The choice of monitor size is strictly related to the way you use your computer: the choice depends on what applications you usually use, such as playing games, using a word processor, doing animation, using CAD, etc. It is clear that, depending on which application you are using, you need a display with more or less detail. In the traditional CRT monitors market, size is usually understood as the diagonal size of the monitor, while the size of the user's viewable area of \u200b\u200bthe screen is usually slightly smaller, on average, by 1 "than the tube size. Manufacturers may indicate two diagonal sizes in the accompanying documentation, while the apparent size usually indicated in parentheses or marked "Viewable size", but sometimes only one size is indicated, the size of the diagonal of the tube.

Typically, monitors with a large tube diagonal are presented as the best solution, even with some concerns such as cost and required desktop space. As we already said, the choice of the size, and therefore the best resolution, depends on how you use the monitor: for example, if you rarely use your computer, just to write a letter, then the best solution for you may be 14 "monitor with a resolution of 640x480; on the other hand, if you need more screen real estate when using a word processor, then there is much better fit 15 "monitor with 800x600 resolution, which also has the advantage over the 14" monitor as a less curved screen surface.

If you use spreadsheets that occupy a large area, and you need to use several documents at the same time, then you should opt for a 17 "monitor with a resolution of 1024x768, or better with a resolution of 1280x1024. If you are a professional DTP, Desk Top Publishing or design and CAD modeling, you will need a 17 "to 24" monitor to work in resolutions from 1280x1024 to 1600x1200. A large, high-resolution monitor will allow you to work more comfortably as you do not need to enlarge the picture. or moving parts of it, or using a virtual desktop when multiple monitors are connected to one or more video cards. Having a large monitor is like looking through a window at the world: the larger the window, the more you see without having to look out.

Maximum resolution in numbers

Maximum resolution is one of the main characteristics of the monitor, which is indicated by each manufacturer. However, you can determine the actual maximum resolution of the monitor yourself. To do this, you need to have three numbers: the step of the point (the step of the triads for tubes with a shadow mask or the horizontal step of the strips for tubes with an aperture grating) and dimensions used screen area in millimeters. The latter can be found from the description of the device or measured independently. If you go the second way, then maximize the boundaries of the image and take measurements through the center of the screen. Substitute these numbers into the appropriate formulas to determine the actual maximum resolution.

Let's accept abbreviations:

• maximum horizontal resolution \u003d MRH
• maximum vertical resolution \u003d MRV

For monitors with shadow mask:

• MRH \u003d horizontal dimension / (0.866 x triad pitch);
• MRV \u003d vertical dimension / (0.866 x triad pitch).

So, for a 17-inch monitor with a dot pitch of 0.25 mm and a usable screen area of \u200b\u200b320x240 mm, we get the maximum real resolution of 1478x1109 dots: 320 / (0.866x0.25) \u003d 1478 MRH; 240 / (0.866x0.25) \u003d 1109 MRV.

For monitors with a tube using an aperture grille:

• MRH \u003d horizontal dimension / horizontal stripe pitch;
• MRV \u003d vertical dimension / vertical stripe pitch.

So, for a 17-inch monitor with a tube using an aperture grille and a stripe pitch of 0.25 mm horizontally and a size of the used screen area of \u200b\u200b320x240 mm, we obtain the maximum real resolution of 1280x600 pixels: 320 / 0.25 \u003d 1280 MRH; The aperture grating has no vertical pitch, and the vertical resolution of such a tube is limited only by focusing the beam

The maximum resolution supported by the monitor is directly affected by the horizontal scanning frequency of the electron beam, measured in kHz (Kilohertz, kHz). The horizontal value of the monitor shows how many horizontal lines on the monitor screen can be drawn by an electron beam in one second. Accordingly, the higher this value (which is usually indicated on the box for the monitor), the higher the resolution the monitor can support at an acceptable frame rate. Line rate limiting is a critical parameter when designing a CRT monitor. These monitors use magnetic systems for deflecting the electron beam, which are windings with a fairly large inductance. The amplitude of overvoltage pulses on the line coils increases with the line frequency, so this node turns out to be one of the most stressed places in the structure and one of the main sources of interference in a wide frequency range. The power consumed by line scan units is also one of the major factors in the design of monitors.

The refresh or refresh rate (frame rate for CRT monitors) of the screen is a parameter that determines how often the image on the screen is redrawn. The refresh rate is measured in Hz (Hertz, Hz), where one Hz corresponds to one cycle per second. For example, a monitor refresh rate of 100 Hz means that the image is refreshed 100 times per second. As we said above, in the case of traditional CRT monitors, the glow time of the phosphor elements is very short, so the electron beam must pass through each element of the phosphor layer often enough so that no image flicker is noticeable. If the frequency of such a bypass of the screen becomes less than 70 Hz, then the inertia of visual perception will not be enough for the image to not flicker. The higher the refresh rate, the more stable the image appears on the screen. Flickering images (flicker) leads to eye fatigue, headaches and even blurred vision. Note that the larger the monitor screen, the more noticeable the flickering, especially with peripheral (side) vision, since the viewing angle of the image increases. The refresh rate value depends on the used resolution, on the electrical parameters of the monitor and on the capabilities of the video adapter. The minimum safe frame rate is considered to be 75 Hz, while there are standards that determine the value of the minimum allowable refresh rate. It is believed that the higher the refresh rate, the better, but studies have shown that at a vertical frequency above 110 Hz, the human eye can no longer notice any flicker. Below we provide a table with the minimum allowable refresh rates for monitors according to the new TCO'99 standard for different resolutions:

If the visible screen size is used instead of the CRT size, then the data in the table above also applies. Note that the minimum admissible parameters are given, and recommended regeneration frequency\u003e \u003d 100 Hz.

Next, we bring to your attention a reference table, which shows the physical and visible dimensions of CRT monitors, the maximum supported resolution, the recommended resolution, as well as the required video memory for display with 256, 65K and 16M colors. Note that we are not talking about the presentation of 3D graphics, since in this case additional memory is required for Z-buffering and for storing textures.

Physical size monitor diagonal	Visible diagonal of the monitor	Maximum resolution	Recommended Resolution	Local memory for 256 colors	Local memory for 65K colors	Local memory for 16M colors
14"	12,5" — 13"	1024x768	640x480	0,5	1	2
15"	13,5" — 14"	1280x1024	800x600	1	2	2
17"	15,5" — 16"	1600x1200	1024x768	1	2	4
19"	17,5" — 18"	1600x1200	1280x1024	2	4	4
21"	19,5" — 20"	1600x1200	1280x1024	2	4	4
24"	21,5" — 22"	1900x1200	1600x1200	2	4	8

It is clear that the data in the table is purely for reference, and no one forbids you to work on a 15 "monitor with a resolution of 1024x768. It all depends on the capabilities of your monitor, your preferences and your vision. Remember, as in the parody of" Star Wars ":" ... and if you have read this line, then you do not need glasses ". :-)

Now it is logical to move on to the issue of safety standards. Moreover, on all modern monitors, you can find stickers with the abbreviation TCO or MPRII. On very old models, there are also the inscriptions "Low Radiation", which in fact do not say anything. It's just that once, solely for marketing purposes, manufacturers from Southeast Asia attracted attention to their products. Such an inscription does not guarantee any protection.

TCO and MPRII certified

We have all heard at least once that monitors are hazardous to health. In order to reduce health risks, various organizations have developed recommendations on monitor parameters, following which monitor manufacturers are fighting for our health. All safety standards for monitors regulate the maximum allowable values \u200b\u200bof the electric and magnetic fields generated by the monitor during operation. Almost every developed country has its own standards, but the standards developed in Sweden and known under the names TCO and MPRII have gained particular popularity all over the world (as it happened historically). Let's tell you more about them.

TCO

The TCO (The Swedish Confederation of Professional Employees), of which 1.3 million Swedish professionals are members, is organized into 19 associations that work together to improve the working conditions of their members. These 1.3 million members represent a wide range of workers and employees from the public and private sectors of the economy.

TCO has nothing to do with politics or religion, which is one of the defining reasons that allows different collective members to unite under the roof of one organization.

Teachers, engineers, economists, secretaries and nannies are just a few of the groups that collectively form the TCO. This means that TCO reflects a large cross-section of society, which gives it broad support.

This was a quote from an official TCO document. The fact is that more than 80% of employees and workers in Sweden deal with computers, so the main task of TCO is to develop security standards when working with computers, i.e. provide its members and everyone else with a safe and comfortable workplace. In addition to developing security standards, TCO is involved in the creation of special tools for testing monitors and computers.

TCO standards are designed to ensure that computer users can operate safely. Every monitor sold in Sweden and Europe must meet these standards. TCO guidelines are used by monitor manufacturers to create better products that are less hazardous to users' health. TCO guidelines are not just about defining acceptable values different types radiation, but also in determining the minimum acceptable parameters of monitors, for example, supported resolutions, luminescence intensity of the phosphor, brightness margin, power consumption, noise, etc. Moreover, in addition to the requirements, the TCO documents provide detailed methodologies for testing monitors. Some documents and more information can be found on the official TCO website: tco-info.com

TCO guidelines are applied in Sweden and all European countries to determine the standard parameters that all monitors must comply with. The recommendations developed by TCO today include three standards: TCO'92, TCO'95 and TCO'99; it is easy to guess that the numbers mean the year of their adoption.

Most of the measurements during TCO compliance testing are taken 30cm in front of the screen and 50cm around the monitor. For comparison, when testing monitors against another MPRII standard, all measurements are taken at a distance of 50 cm in front of the screen and around the monitor. This explains why TCO standards are more stringent than MPRII.

TCO "92

The TCO'92 standard was developed exclusively for monitors and defines the maximum allowable electromagnetic radiation during the operation of the monitor, and also sets the standard for the energy saving features of monitors. In addition, a TCO'92 certified monitor must comply with the NUTEK energy standard and comply with European fire and electrical safety standards.

TCO "95

The TCO'92 standard is designed only for monitors and their performance in relation to electric and magnetic fields, energy saving modes, and fire and electrical safety. The TCO'95 standard applies to all personal Computer, i.e. on the monitor, system unit and keyboard, and concerns ergonomic properties, radiation (electric and magnetic fields, noise and heat), energy saving and ecology modes (with the requirement for mandatory adaptation of the product and the production process at the factory). Note that in this case, the term "personal computer" includes workstations, servers, desktops, desktops, and Macintosh computers.

The TCO'95 standard exists alongside the TCO'92 and does not override the latter.

TCO'95 requirements for electromagnetic emissions of monitors are not more stringent than TCO'92.

By the way, with regard to ergonomics, TCO'95 in this regard imposes more stringent requirements than the international standard ISO 9241

Note that LCD and plasma monitors can also be certified according to TCO'92 and TCO'95 standards, as well as laptop computers.

By the way, mice are not subject to TCO'95 certification.

Four organizations were jointly involved in the development of the TCO'95 standard: TCO, Naturskyddforeinegen, NUTEK and SEMKO AB.

Naturskyddforeinegen (The Swedish Society for Nature Conservation) - The Swedish Society for Nature Conservation. This is their sign in the form of a flying falcon placed on the TCO'95 emblem. It would be interesting to know the transcription of the name of this respected organization.

NUTEK (The National Board for Industrial and Technical Development in Sweden) is a Swedish government organization dedicated to research on energy conservation and effective use energy.

SEMKO AB is engaged in the testing and certification of electrical products. It is an independent division of the British Inchcape Group. SEMKO AB has developed tests for TCO'95 certification and verification of certified devices.

TCO "99

TCO'99 is more demanding than TCO'95 in the following areas: ergonomics (physical, visual and usability), energy, radiation (electric and magnetic fields), environment and ecology, and fire and electrical safety. TCO'99 standard applies to traditional CRT monitors, flat panel displays (Flat Panel Displays), portable computers (Laptop and Notebook), system blocks and keyboard. The TCO'99 specifications contain requirements taken from the TCO'95, ISO, IEC and EN standards as well as from EC Directive 90/270 / EEC and the Swedish national standard MPR 1990: 8 (MPRII) and from earlier TCO recommendations. TCO'99 was developed by TCO, Naturskyddsforeningen and and Statens Energimyndighet (The Swedish National Energy Administration, Swedish National Energy Agency).

Environmental requirements include restrictions on the presence of heavy metals, brominates and chlorinates, freons (CFCs) and chlorinated substances within materials.

Any product must be prepared for recycling, and the manufacturer must have a developed disposal policy, which must be followed in each country in which the company operates.

Power saving requirements include the need for the computer and / or monitor to reduce power consumption by one or more steps after a certain period of inactivity. In this case, the period of time for recovery to the operating mode of energy consumption should suit the user.

MPR II

This is another standard developed in Sweden, where the government and nongovernmental organizations are very concerned about the health of the country's population. The MPRII was developed by SWEDAC (The Swedish Board for Technical Accreditation) and defines the maximum allowable radiation for magnetic and electric fields and how they are measured. MPRII is based on the concept that people live and work in places where there are already magnetic and electric fields, so the devices we use, such as a computer monitor, should not create electrical and magnetic fieldslarger than those that already exist. Note that TCO standards require devices to reduce emissions of electric and magnetic fields as much as technically possible, regardless of the electric and magnetic fields already existing around us. However, we have already noted that TCO standards are tougher than MPRII.

Standards are good, but the user can help maintain their health and increase comfort when working with a computer. There are several recommendations for this:

• Since a monitor is an electrical device, it is always a good idea to plug it into a grounded outlet.
• After switching on for several minutes, the monitor becomes very hot, as a result of which various chemical gases begin to spread in the form of gases, which are hazardous to health. Therefore, the better the room with the computer is ventilated and the more space around the monitor, the better and safer.
• It is very important that your monitor and video adapter match each other. This ensures you can use the optimal resolution at a high refresh rate of the monitor screen, which means less eye fatigue and less risk of visual impairment.
• Monitors, like humans, age. After a few years, image quality may deteriorate, just as contrast and brightness may deteriorate. If you have any suspicions that the properties of the monitor have deteriorated, then before buying a new one, contact the service center.
• If your budget allows you to make expensive purchases from time to time, then it's a good idea to buy a new monitor every 4-5 years. Or more often if higher quality models have appeared on the market.

Now let's talk a little about what DDC, VESA, Plug & Play and Power Management are.

Let's start with the DDC standard, well known in the world of monitors and video adapters. DDC stands for Display Data Channel. DDC is a standard created by the VESA (Video Electronics Standard Association) consortium. With the help of DDC, the user has the ability to control the settings of a graphical terminal, for example, a monitor, through software... The DDC standard enables the monitor to communicate directly with the video adapter. The video adapter receives from the monitor all the necessary information about the functionality of the latter, which, as a result, provides the ability to automatically configure and select the optimal values \u200b\u200bof the screen refresh rate, depending on the selected resolution. DDC is the foundation of Plug & Play functionality for monitors. DDC finds physical communication channels between the monitor and the video adapter, which allow the monitor to communicate with the video adapter, and the CPU sends all the necessary information about the functionality of the monitor. The DDC standard is based on a special architecture developed by Philips and DEC, known as I2C. I2C is used to drive a data bus that consists of two wires that carry bidirectional signals and one wire that is used for ground. You can connect every component to this bus, from the CPU to the monitor, video adapter, and whatever, and each of these components controls the bus during the start of data transfer. At this point, the bus controlling component becomes the Master Bus. At the same time, other devices connected to the I2C bus become Slave Bus. The advantage of this architecture is low cost and reliability in data transmission. There are three different levels DDC:

• DDC1: Used by the monitor to transfer configuration information (EDID) to the computer.
• DDC2B: Uses the I2C bus to read configuration data from the monitor.
• DDC2AB: bi-directional communication between the monitor and the computer is used and is controlled by commands transmitted via the ACCESS.BUS protocol.

We mentioned VESA, which is a non-profit company run by a group of directors representing over 280 companies from all over the world. VESA appeared at a time when graphics devices that were incompatible with each other began to appear on the market, which resulted in the appearance of a lot of problems. VESA develops standards with the aim of achieving the highest level of compatibility between devices that conform to the standard. All standards are developed by the best experts in the field of hardware and software from best companiesrelated to graphics in the computer world.

We often hear the phrase Plug & Play and the name of the operating room. windows systems 95/98, which supports Plug & Play devices and manages their configuration. Operating systems like Windows 98 can detect the presence of an installed video adapter in your computer, receive important information from the graphics card, such as the maximum supported resolution and maximum color depth. In addition, the operating system obtains information about the monitor, such as supported vertical and horizontal refresh rates, as well as support for power management if the monitor is Plug & Play (read: DDC). After obtaining all the necessary information about the video subsystem, Windows98 analyzes it and presents in the display properties the ability to choose among the modes available for use. Those. the user gets the opportunity to choose the resolution, color depth and refresh rate value (sometimes only the optimal and default values \u200b\u200bare available). For this to work, both the monitor and video adapter must be DDC12B compliant, which we mentioned above.

The monitor's power management system is based on EPA's Energy Star specification, which can reduce system idle power consumption by 60-80% compared to the power consumption of the monitor at high resolution and deep color depth. EPA (Environmental Protection Agency) is the US government's environmental protection agency. It is this agency that develops recommendations for the optimal use and conservation of energy. The Energy Star logo is familiar to all computer owners, it only says that the manufacturer followed EPA recommendations when developing a product or component (for example, a monitor).

Energy management occurs automatically after turning on the energy saving mode. You can reduce the power consumption by up to 5W in full off mode, while the monitor uses an average of 80-90W during operation. In Standby mode, i.e. temporarily switching to standby mode, the monitor consumes less than 30 watts. In addition to saving energy, using power saving modes can reduce thermal radiation from an operating monitor.

* The cumulative default on time for both power saving modes should not exceed 70 minutes.

In the "Standby" mode, the screen is blanked out, in the "Suspend" mode - the heating temperature of the CRT cathodes decreases. Some monitors interpret Standby mode the same as Suspend mode. Note that the sync signals going out of range are perceived by most monitors as their absence, which leads to a transition to a complete shutdown mode.

DPMS (Display Power Management Signaling) is a VESA consortium standard. DPMS defines the power management modes that you can use when the monitor is idle, and you can choose from three modes shown in the table above: "Standby", "Suspend" and "Off" ("Shut down"). The monitor must comply with the EPA Energy Star standard, but you can use these modes only if your computer (or rather the BIOS), video adapter and operating system support the DPMS specification recommended by VESA.

Setup and problems

There are many problems with the monitor even if it is just purchased. What are these problems? Here are the most common ones:

• image focus
• non-mixing
• jitter
• problems with the geometry of the image visible on the screen
• problems with uniform display of the image on the screen

These problems arise due to the complex structure of the monitor, and it happens that even if all the electronic components are working correctly, the problem cannot be corrected by changing the monitor adjustments. In practice, most problems are still due to component malfunction, calibration problems associated with a mismatch between the monitor and video adapter, etc. Setting up a monitor is time consuming and the end result is often unsatisfactory. If possible, it is always better to contact the specialists from the service center.

As we already know from the theoretical part of this article, one of the most important components of the monitor are electron guns, a mask and a surface with a phosphor. Let's start with a beam of electrons that are emitted by three guns.

Guns that emit electrons, one for each of the primary colors (red, green, and blue), send a beam onto the screen. This beam of electrons, falling into the middle of the screen, forms a circle, while when moving to the rest of the screen, the beam forms an ellipse, as a result of which the image is distorted, this process is called astigmatism. Moreover, the problem becomes more and more with increasing the size of the monitor. Of course, there is nothing good for our health in this.

Another problem, also unsafe for health, is image flickering. Image flickering is caused by insufficient screen refresh rate. Flickering was common on older, low frame rate, interlaced interlaced monitors. In them, each image frame is formed from two fields containing either even or odd lines, which were replaced by monitors with progressive scan (non-interlaced, in which each image frame is formed by all lines).

Another problem is incorrect convergence of the beams of electronic monitors' projectors, which leads to blurring of the image and color fringing of picture elements. The three beams of electrons emitted by the respective guns must accurately hit the corresponding colored phosphor elements.

Another problem is the lack of clarity at the edges of the screen. This problem arises due to the fact that cannon spotlights must always focus beams on the screen surface. Since the lengths of the electron beam paths to the center of the screen and its edges are different, monitors use dynamic focusing circuits that change the focal length of the projector depending on the angle of deflection of the beam. Since such circuits inevitably have some error in operation, the dynamic focus circuits are adjusted to provide maximum sharpness in the center of the screen. Therefore, motion blur may appear at the edges of the screen. The degree of this blur depends on the diligence of the monitor manufacturer.

The electron beams of the searchlights are deflected in the magnetic field of special horizontal and vertical coils. Such deflection systems easily provide a linear change in the angle of deflection of the beam in time with a linear current in the coils. On a flat screen monitor, the beam speed will increase with an increase in the deflection angle according to the law 1 / cos (a). Therefore, geometric distortions in the form of elongated corners (pincushion) raster borders will be noticeable on the screen. To compensate for them in monitors and televisions, distortion correction circuits are used, which form currents of a complex shape in the coils of the deflecting system. If these devices are not properly calibrated, image distortions such as "barrel distortion" or "pincushion" may appear on the screen. Distortions such as "trapezium distortion" or "trapezoid" are also possible, when the lateral borders are inclined and tend to converge to one point, i.e. the image is trapezoidal. Sometimes such distortions can also arise as a result of changes in the geometry or position of the coils and correcting elements of the monitor deflection system over time, as a result of which the image rotates slightly.

A fairly common problem is color or dark spots that suddenly appear on the monitor screen. And even yesterday everything was fine, but today there is a rainbow on the screen. In this case, most likely, magnetization of the shadow mask (or aperture grille, or slit mask) of the monitor tube has occurred. Magnetization occurs under the influence of magnetic fields: natural (say, a magnetic anomaly) or man-made (another monitor, acoustic speakers, transformer). Moreover, magnetization can also occur as a result of even a short operation of the monitor in a non-standard position (screen down, or up, or on its side). The fact is that the monitors have a built-in system for compensating for the influence of the Earth's magnetic fields, which, when the monitor is in a non-standard position, only enhance this influence. Due to magnetization, the convergence of the monitor beams can be disturbed and geometric distortions appear.

To demagnetize the cathode-ray tube mask, almost all modern monitors have a special circuit through which current is passed at the moment the power is turned on. The monitor has, as a rule, an additional button (or OSD menu item) of forced demagnetization (Degauss). If after switching on you find spots on the screen, then double-click the demagnetization button. If the spots are not completely gone, then make sure that the monitor is in the standard position :-) and after 25-30 minutes repeat the demagnetization process.

If your monitor does not provide such a function, then just turn the monitor on and off several times, pausing for several minutes.

An important detail should be added here. Built-in demagnetization is enabled only when power is applied, i.e. after the monitor has been completely de-energized. Which leads to an interesting fact - ATX units do not have a monitor power connector. And when the monitor is constantly on (if it is not de-energized, and this is what everyone does), demagnetization does not work. So, it's worth remembering about such a nuance. Note that many do not have this problem. modern models monitors, as they are demagnetized when switching from "Stanby" to normal mode, i.e. a complete power cut is not required.

If, nevertheless, it was not possible to demagnetize the monitor screen, then you should contact the service center, since the use of artisanal methods can lead to disastrous results.

In addition, it should be noted that many problems that arise when using a monitor are due to the computer's video adapter or because of the interface cable between the monitor and the video card. Sometimes, no matter how ridiculous it may seem, but some problems with the monitor can be solved as a result of a simple reversal of the interface cable, or as a result of installing new drivers for the video adapter, or after setting a different resolution or a different refresh rate.

So, in view of the fact that the monitor is a device that may have problems that negatively affect the comfort of your work at the computer, then when choosing a new monitor, you should give preference to the highest quality monitor that best meets your needs. Depending on the type and brand of monitor, the set of functional settings that can solve some or most of the problems can vary significantly, so when choosing a monitor, make sure that it has a sufficient set changeable settings, which will allow you to solve some of the problems yourself, without the need to contact the service center. Moreover, even if there were no flaws in the purchase of the monitor, they may appear later.

How to choose a monitor?

It is clear that it is impossible to give an unambiguous answer to this question. Too many factors determine the final choice. Everyone has their own preferences and needs. In addition, two monitors of the same type and brand can vary greatly in quality. But you can give general recommendations on what to look for when choosing a monitor. This is what we will try to do below.

Before heading to the store for a new monitor, you need to clearly define for yourself two things: how much you are willing to spend on the monitor and for what purposes you will use the monitor. With money, in principle, everything is clear: either it is there, or it is not. However, if you are going to buy a monitor as part of a computer system, then weigh again the amount set aside for the monitor. Perhaps saving money on a processor or video adapter can help you buy a better monitor. As for what tasks you need a monitor for, there are several considerations. It is clear that if you are not constrained in funds and there is more than enough space on your desktop, then it is obvious that a monitor with a large diagonal and high resolutions will be an excellent choice. Again, if there is money, but there is no space, then modern TFT-LCD monitors will satisfy your needs. If there is not enough money and there is no free space, then you should choose from 15 "and 17", while among 17 "monitors, you should pay close attention to models with a shortened tube, since in depth they correspond to the dimensions of 15" monitors, and there is not enough as a rule, it is space in the depth of the table. By the way, the tendency to reduce the length of the tubes has become widespread, now 19 "monitors are being produced, which in terms of dimensions in the depth of the table take up space as 17" models. We do not recommend buying a 14 "monitor at all, except when it is exactly what you need.

There is a certain type of task for which a monitor with a large diagonal is simply necessary. For example, if you are going to do layout or design, then a monitor with a size of less than 17 "will simply not work for you. So, in this case, if you do not have enough funds, it makes sense to wait until better times.

Since we are talking about monitors with a large diagonal, it is worth mentioning the connection of such monitors to video cards using special BNC cords. The fact is that quite often monitors with a diagonal of 17 "and larger have two types of connectors for connecting VGA cables: 15 pin D-SUB (standard) and a set of several coaxial BNC sockets (3, 4 or 5 BNC connectors). To connect the monitor via BNC connectors, a special cord is used, on one side of which there is a standard 15 pin D-SUB connector, and on the other - several coaxial cables with BNC connectors (three, four or five).

These are the signals that are carried through cables in cords with BNC connectors:

• Three BNC cables: Red, Green + Sync, Blue (sync signal is transmitted together with green)
• Four BNC cables: Red, Green, Blue, CS (Composite sync, mixed sync). Synchronization possible with green signal
• Five BNC cables: Red, Green, Blue, HS (Horizontal Sync), VS (Vertical Sync). That is, Separate syncs are applied. It is also possible to apply mixed sync or sync on green.

By the way, note that there is another 13W3 connector (used, for example, in monitors from Sun), which consists of 3 coaxial (BNC) and 10 conventional signal contacts (pin), combined into one housing.

Using a BNC cable allows you to get a smoother front signal transmitted to the monitor. A branded (high-quality) BNC cord costs about $ 20-40 (and even $ 100). Note that a poor-quality BNC cable often only spoils the signal, which can degrade the image. What is a BNC cable for? It is believed that its application will significantly improve the image quality at high resolutions, starting from 1024x768. However, judging by practice, these impressions are rather subjective. In this case, you need to take into account the quality of the signal issued by the video card. When using a cheap video card with bad filters (or in the absence of them at all), with a weak or low-quality DAC, no BNC cable will help you. Conversely, when using a high-quality video card, switching to a BNC connection may not provide any visual improvements (there is nothing to improve). We emphasize that for monitors with a diagonal of less than 17 "and at resolutions below 1024x768, the use of a BNC cable will not give any advantage. But at high resolutions and at high frequencies, a gain in the form of a better image can be obtained.

There is another area of \u200b\u200bapplication for BNC cords. If you need to place the monitor quite far from the computer, for example, in a hospital, when the monitor is in the patient's room, and the computer itself, which takes readings from the sensors, is located behind the wall. In this case, you cannot do without BNC cords. Since their use will allow you to remove the monitor 15 meters from the computer.

Now let's continue our discussion of monitor types. Some monitors have built-in speakers. Is this good or bad? In our opinion, not all built-in speakers sound decent, moreover, there are times when the image on the monitor deteriorates because of them. It's up to you, of course, to decide, we think it's better to buy the speakers separately, again, based on your tastes. In addition, if you already have speakers, you are unlikely to use those that are built into the monitor, but why buy something that you will not use? The only argument in favor of the speakers built into the monitor, in our opinion, is the saving of space on the table. However, no one bothers to buy external acoustics, which are mounted on the monitor. Moreover, modern sound cards are designed to connect more than four speakers, so sooner or later you will still buy external acoustics. But back to the monitors, since we are talking about them.

In general, we are talking about the size of the diagonal, but it should be remembered that the maximum resolution that you can use depends on the size of the monitor. We talked about this earlier. In addition, an important factor is the point pitch or the parameter corresponding to a specific type of monitor tube (i.e., it can be both a slot pitch and a strip pitch). The dot pitch determines how accurately the image details are reproduced when displayed on the monitor screen. The smaller the dot step value, the higher the image quality we get on the screen, while the higher the resolution, the more clearly it will be. In the case of LCD monitors, the parameter that determines the image quality is the number of electrodes: the more, the better.

Note that some manufacturers sometimes use unconventional designations for parameters such as dot pitch. As a result, the user does not buy exactly what he wanted. Therefore, always look at the manual, but rather ask the seller what exactly the monitor manufacturer means by this or that parameter. The same applies to the maximum resolution. Some monitors, when using the maximum resolution, maintain a very low refresh rate, or even work in interlace mode at all, which is unacceptable. Therefore, the more you learn about a monitor before buying, the less likely you are to be disappointed later.

Also, inquire in advance about service support and monitor warranty. Best of all, if you contact a specific seller, a friend recommended you, who has already dealt with this company and was satisfied with the quality of the service. It also doesn't hurt to ask the opinion of friends about specific brands of monitors. But remember, you don't care to choose.

Now, regarding the frequencies supported by the monitor. Very often only the bandwidth is indicated on the monitor box. Sometimes there is also a horizontal frequency sweep range. However, as a rule, you can find additional information in the manual for the monitor. Basically, if a monitor complies with the TCO standard, then one can already draw conclusions about its characteristics from this. But, even knowing only the bandwidth of the monitor, we can determine quite accurately whether we will be able to work at the required resolution at the required refresh rate. The bandwidth is measured in MHz (Megahertz, MHz) and characterizes what can be the minimum pulse duration corresponding to the display of a single dot on a line of the image, and, therefore, its size at the limiting line scan rates. Note that the values \u200b\u200bof the monitor's bandwidth and the maximum pulse rate of individual pixels by the video adapter (dot clock, i.e., the data on the display of how many pixels the video adapter can transmit to the monitor per second; also measured in MHz), in combination determine the sharpness of the image by horizontals at extreme resolutions and scan rates. At approximately equal values \u200b\u200bof this frequency, the overall limiting frequency of the "video card-monitor" system will be approximately 40% lower. For other ratios, one can use the Pythagorean theorem for a right-angled triangle with legs of reciprocal frequencies for estimates. The length of the hypotenuse will roughly correspond to the reciprocal of the system bandwidth. Obviously, with a large difference between two such frequencies, the final bandwidth value will be determined by the worst element. Therefore, when replacing a monitor, you should carefully study the characteristics of the video card and evaluate its effect on the sharpness of the image in the monitor mode you are using. Otherwise, the loss of sharpness when increasing the resolution or frame rate may be due to insufficiently good characteristics of the video card. In any case, the larger the dot clock headroom, the better.

It should be noted that the bandwidth depends on the number of vertical and horizontal pixels and the refresh rate of the screen. Suppose Y is the number of vertical pixels, X is the horizontal number of pixels, and R is the screen refresh rate. To account for the additional vertical sync time, multiply Y by a factor of 1.05. The time required for horizontal sync corresponds to about 30% of the scan time, so we use a factor of 1.3. Note that 30% is a very conservative figure for most modern monitors. As a result, we get the formula for calculating the bandwidth of the monitor:

Bandwidth \u003d 1.05 * Y * 1.3 * X * R

Now, if you have chosen a monitor for yourself and are going to work in a resolution, for example, 1280x1024 at a refresh rate of 90 Hz, then the required bandwidth of the monitor will be: 1.05 * 1024 * 1280 * 1.3 * 90 \u003d 161 MHz.

We emphasize that the obtained value is approximate, and it can be used only as a guide. It is clear that the best way check if the monitor holds a certain resolution at a certain refresh rate, this is to set this resolution and refresh rate. If the result suits you, then everything is in order. However, do not forget that the video adapter in the store may be completely different from the one in your computer.

In addition to checking the frequency response of the monitor and the supported resolutions, you should also look at how the monitor displays the image. Those. look at brightness, contrast, chromaticity (including color saturation), flattening, geometry. It is recommended to allow the monitor to warm up for at least 20 minutes before checking the quality of the displayed image. A monitor is an expensive purchase, so you shouldn't rush to make a choice.

Almost all modern monitors have digital adjustment of parameters or combined analog-digital. In addition to knobs or control buttons, the monitor usually has a so-called OSD (On Screen Display), i.e. settings menu that appears when it is called on the monitor screen over all currently displayed video information. As a rule, you can get information about the current video mode via OSD, i.e. resolution and refresh rate, select the language of the menu messages, demagnetize the monitor, select the color temperature, etc. After you make changes in the menu settings, all settings for this mode will be automatically remembered (unless, of course, you have a purely analog monitor, which you are unlikely to find on sale today). Of course, you need to set up the monitor during testing in the mode in which you will most often work (if there are several such modes, then it is best to test them all).

To test the quality of the image displayed on the monitor screen, you can use special utilities, the most famous of which is Nokia Monitor Test from renowned manufacturer monitors. But if such a utility is not at hand, then you can do with your own eyes.

So, if you don't have any special utilities at hand, and you don't have a friend nearby who is ready to take responsibility for choosing a monitor for you, you will have to do everything yourself, as they say, by eye. First of all, let the monitor warm up, as we said, at least 20 minutes.

If there is an opportunity and free time, then it is best to let the monitor work for 1.5-2 hours, since it is during this time that you can notice such a type of marriage as the appearance on the screen of mild violations of the purity of tone, clearly visible on a white background and from a long distance. These disturbances are similar to mask magnetization. All attempts to demagnetize, even with special external devices, may fail. On some monitors, this effect can be very pronounced. For example, the entire screen may take on a bluish tint and spots on the screen may appear yellowish. It is clear that for people working with graphics, such a monitor is completely unsuitable, but even when working with texts, there are problems with out of focus on the screen field. Moreover, in the area of \u200b\u200byellow spots, the rays are poorly converged and defocused. At the same time, as practice has shown, the service center recognizes "incorrectness", but in many cases refuses to change the monitor, referring to the fact that violations are within tolerance. In fact, such problems are associated precisely with the thermal deformation of the mask, and specifically with the sagging of its strings in areas with spots. The slightest tapping on the monitor with your finger leads to a play of colors in the problem area with the frequency of vibration of the strings. In the rest of the screen, there are no such overflows (with a light tap on the body with one finger!). This defect was observed in some ViewSonic PT775 monitors. We emphasize that the image looks great when the monitor is cold. Obviously, the manufacturer made a mistake in the implementation of monitor cooling. Although this may be the result of attempts to reduce the level of electromagnetic radiation in the event of some urgent revision of the monitor in accordance with the changed requirements. In general, it should be borne in mind that some defects may manifest themselves only after a fairly long period of operation of the monitor.

So, the monitor has warmed up. Then set the desired resolution and refresh rate. If you have such an opportunity, then it is better to connect several monitors at the same time so that you can compare and choose the best one.

Next, adjust the brightness of the screen so that the color of the luminous part of the screen (working) matches the non-luminous part of the screen, i.e. with a frame around the edges of the screen. Adjust the contrast to an acceptable level. Make sure you have a margin of both brightness and contrast. If there is no stock, replace the monitor. Note that almost all the actions suggested below are performed by a utility from Nokia.

Focus check:

It is very important that the electron guns are correctly focused, both in the center of the screen and at the corners. It is the places in the corners of the screen that are problematic. Look at the dark text displayed on a light background in the center and corners of the screen. Letters must be clear and legible, and pixels at the edges of the screen must not smudge or double. All the flaws are very well visible on the lowercase letters "e" and "m", ideally, they should be readable anywhere on the screen.

Check information:

Take a close look at the white lines displayed against the black background. If the lines remain white along the edges of the screen, then everything is fine, the convergence is good. However, if streaks of a different color appear on the line, then reproduction of small objects such as characters or lines on this monitor may be mediocre. However, even if color bars are present, the monitor may still meet the manufacturer's specifications. If color stripes appear differently and in different places each time, then the monitor is most likely not meeting specifications, however, generally speaking, most monitors exhibit color stripes at the edges of the screen.

Pillow (barrel) check:

Take something with a straight edge, such as a piece of paper, and place it against the edge of the picture screen. Now look at the screen from the distance you would normally look at a monitor from. If the edges of the image deviate from the straight edge of the paper, the monitor has pillow or barrel distortion. Barrel distortion is the result of improper (over) use of pincushion correction, i.e. the edges of the image are convex outward. If your monitor has pincushion correction, you can try to correct the position. If this is not possible, or if the adjustment did not help, then geometric distortions will be present on the monitor screen, sometimes very significant. It is worth noting that changing the resolution or refresh rate can affect the presence of pincushion distortion: they can either disappear altogether or worsen.

Geometric distortion:

Move a constant-sized object (any small application window will do) across the screen and measure its dimensions with a ruler in different parts of the screen. If the size of the window changes in different parts of the screen, it means that there is geometric distortion, which may not be corrected, especially if the monitor does not provide enough variable geometry settings.

Color rendering:

Display pure red, green and blue colors on the screen in sequence and look at how these colors are displayed on the screen, if the color is displayed incorrectly, then the monitor has an incorrect color rendition.

Illumination uniformity:

Display a completely white image. The brightness should be uniform over the entire area, and no obvious color or dark spots should be visible.

Color smear:

Display the subject with a lighter foreground color (light red, light green, and light blue). On the right side, the light color should clearly end at the border of the object, and not blur or smudge, fading away.

Moire:

Moire, or combinational distortion, appears in the background or around objects in the form of outlines of lines, waves, ripples, etc. Moire is a natural interference phenomenon that occurs on all CRT monitors. Moire depends on the used resolution and monitor size and is best seen at high resolutions on monitors with perfectly focused beams. If you see moiré, then the monitor is well focused, but unpleasant. If there is never any moire at all, then the monitor has poor focus. Some monitors have a moiré adjustment to make it invisible. There are many other ways to get rid of the moire visible to the eye, for example, changing the background in Windows, changing the resolution, resizing the displayed objects, etc.

Anti-glare coating:

As a rule, few people pay attention to this, but since you have decided to choose the most comfortable monitor, then this issue is worth considering.

All anti-reflective coatings work differently. In lower quality coatings, too coarse large particles are used, which scatter light like frosted glass. Turn off your monitor and turn the screen towards a bright light. The presence of blurry reflected images may indicate an increased level of scattering, which degrades the image quality on the monitor. Next, turn the screen towards the fluorescent lamp located on the ceiling (if, of course, one is available). A quality anti-reflective coating has a dark bluish-violet reflection, while less expensive coatings will produce white reflections.

However, the most important determining factor is your eyes and your senses. Since it is you who spend a lot of time at the monitor, it is up to you to decide whether a particular instance is right for you. And no tests and recommendations will ever replace your eyes.

After you have chosen a monitor and brought it home or office for use, check if there is a driver for it in the box for your operating system (we are talking about Windows). If the driver diskette is not included, visit the manufacturer's website.

Wipe the monitor screen and the monitor cabinet periodically. It makes sense to vacuum or blow dust out of the monitor case. It is advisable to wipe the CRT monitor screen with special compounds. The thing is, dust on the screen forces you to increase the brightness of the monitor, which is not good. Plus, a clean monitor contributes to a comfortable work experience.

Try to take breaks when working in front of the monitor. To rest your eyes and your monitor. It is recommended that the monitor screen is located at a distance of at least 50-70 cm from the user and at such a level that there is no need to tilt or lift your head while looking at it.

We hope that our material will help you make the right choice and use all the capabilities of your monitor with minimal risk to health.

It is, of course, impossible to tell about everything connected with monitors in one article, therefore questions and additions are welcome.

Assistance in preparing the material was provided by Luca ruiu, Victor Kartunov,
Grigory Baytsur and Ilya Tumanov

There are currently a large number of types or types of monitorsthat have differences in screen manufacturing technology, and, as a consequence, image reproduction quality and application in various fields of activity. Let's list the main types of monitors and give brief description:

Cathode ray monitors. Historically the very first. They consist of a vacuum electron tube, in which electron beams are formed and controlled by means of a magnetic deflection system. These beams of electrons bombard the phosphor layer on which the image is projected, a glow arises and, as a result, an image appears. Since these monitors are practically superseded everywhere, we will not consider them in more detail.

The main disadvantages of these monitors:

Large dimensions associated with the fundamental structure of the cathode-ray tube.

Large mass associated with the first characteristic.

Distortions of the image on the periphery of the monitor associated with the physical structure of the cathode-ray tube and the fundamental impossibility of producing flat-panel monitors using this technology.

The constructive need to use high voltage, up to 50 kV, which affects not the best way on energy-saving characteristics, as well as safety.

Liquid crystal monitors or LCD in English. The effect of changing the position of a liquid crystal molecule under the influence of voltage has been known for a long time. The practical effect was obtained back in the early 60s of the last century. It was then that miniature displays first appeared in wrist watch, calculators, various indicators. Over time, the technology has improved, with the advent of laptops and other portable computers served as a good impetus.

The use of this technology in the production of monitors allowed us to completely solve the problems that their predecessors, cathode ray monitors, had. The dimensions have been significantly reduced, tenfold. Now there is no need to specially allocate a large space for the monitor. In this regard, the weight of the monitor itself has been significantly reduced. Now it is comparable in weight to a laptop. Naturally, this applies to not very large monitors. The distortion common to cathode ray monitors has disappeared because the LCD screen is really flat.

However, LCD monitors have their own drawbacks, which manufacturers are trying to overcome by introducing new technologies. These disadvantages include lower contrast and color saturation of the image. Matrix response time (appeared new characteristic for LCD) was large at first, this led to the fact that dynamic scenes were shown with image artifacts. This is due to the inertia of switching the state of liquid crystals. Small viewing angles, when one and the same picture, when viewed from the side, from above or below, begins to distort or invert colors.

To overcome these shortcomings, manufacturing firms began to improve the technology of liquid crystal matrices, which led to the creation of the following types of monitors, differing in the matrix manufacturing technology:

Historically, the first liquid crystal arrays in which crystals are lined up one after another, but located relative to the plane of the display or view in a spiral. When voltage is applied, this spiral "twists" by an amount that depends on the voltage. The pixel is colored in one color or another.

Developed by Hitachi, the crystals are not twisted into a spiral, but are lined up one after another in parallel. This allows for higher quality colors, but the response time increases, as it takes more time to rotate the entire array of crystals.

Fujitsu has developed another technology that eliminates the color imperfections of TN technology and improves response time compared to S-IPS technology. For this, it was necessary to significantly complicate the structure of both the matrix and the polarizer filters. Samsung has developed its own PVA technology to avoid paying licensing fees. These technologies are similar, but the difference is in the greater contrast of the image.

The technology developed by Samsung is positioned in the ability to provide a higher contrast image compared to S-IPS technology, and is 10% cheaper than it. The manufacturing technology and device of the matrix is \u200b\u200bunknown. Until recently, this type of matrix was used in mobile devices.

in English. The effect of glowing inert gases under high voltage is used. This technology eliminates the disadvantages inherent in liquid crystal matrices. The brightness and contrast of the picture are at a height, and since the matrix elements are large enough, which affects the resolution not in the best way, this is practically invisible. Dynamic scenes are also transmitted without distortion. The viewing angles are large, the picture can be seen without loss of color from any direction. The screen thickness has become even smaller compared to LCD monitors.

or monitors with an OLED array. They are receivers of liquid crystal monitors. The benefits include extremely low power consumption as these LEDs light up by themselves. No need for a backlight. Extremely high contrast, fast response times, and response times are measured in microseconds, as opposed to milliseconds in LCD monitors. An OLED monitor is even thinner than a plasma monitor. And the viewing angles are 180 degrees, since we are looking at the LEDs themselves, and not at the filters, like with liquid crystal monitors.

Despite such outstanding characteristics, there are also disadvantages. This fragility of the OLED matrix with the high cost of such monitors is a decisive factor in the low demand for them. And this affects the speed of implementation of developments, because firms incur losses. Why spend large resources on an unprofitable business?

But despite this, the developers do not abandon their attempts to solve these problems, since OLED technology allows you to do fantastic things: fold the screen into a tube, create transparent displays, use in a wide range of temperatures, etc. For lovers of such things, OLED monitors are sold, costing about $ 8000, with a screen diagonal of about 60 cm.

Today these are the most common types of monitors, with the exception of the very first and last on our list. The times of the former have already passed, while the latter still has everything ahead. Let's consider in more detail the technologies for manufacturing monitor matrices.

Matrix manufacturing technologies.

The TN + film liquid crystal matrix consists of the following elements:

A pixel in a liquid crystal matrix is \u200b\u200bformed from 3 cells or dots of blue, red and green colors. Turning on and off these points, combining these states, get one color or another. The matrix is \u200b\u200bcontrolled by pixel. Here lies a big drawback of these passive matrices: until the signal reaches the last pixels, the brightness of the first will decrease due to the loss of charge. And building matrices with a large diagonal using this technology is also impractical. You will need to increase the voltage, which will lead to an increase in interference.

To overcome these obstacles, TFT (Thin Film Transistor) technology or thin film transistor has been developed. Since the transistor is an active element, accordingly, the matrices have become active. The use of such transistors made it possible to control each pixel separately, which made it possible to significantly increase the response time and produce large-size liquid crystal matrices.

In each cell of one color or another, which is part of the pixel, there are liquid crystal molecules. In TN + film technology, they are lined up one after the other, but rotated relative to each other in a spiral in such a way that the extreme molecules are rotated relative to each other by 90 degrees. These molecules are located in special grooves, which create such an arrangement on the glass substrate.

Electrodes are connected to the ends of this spiral, to which a voltage is applied to control the pixel. In response to this, depending on the voltage, the spiral begins to contract. Thus, in the absence of voltage, the light passes through the first polarizer filter, then the liquid crystal molecules rotate the light 90 degrees so that it is in the same plane with the 2nd filter and passes through it. Thus, we get a white pixel.

If the maximum voltage is applied, the molecules of the crystal will take a position in which the light will be completely absorbed by the second filter-polarizer. Accordingly, the pixel will be colored black. With variations in the applied voltage, the light will be partially absorbed by the polarizer due to the arrangement of the crystals. The pixel will be grayed out, which means the light will partly pass and partly be absorbed.

Since the matrix made using this technology has small viewing angles, we used a special film applied from above and broadening the view. The result is TN + film technology, in which when changing the viewing angle, the color intensity does not change so sharply. This technology is still used today because it is the cheapest. But it is not suitable for working with graphics.

high speed of the matrix;

low cost;

Disadvantages of technology:

small viewing angles;

low contrast;

color quality;

S-IPS technology is based on the same principles, the difference is that the molecules line up one after the other in parallel, rather than twisting into a spiral, as in TN + film technology. The electrodes are located on the bottom substrate. In the absence of voltage, the light does not pass through 2 polarizing filter, the polarization plane of which is located at an angle of 90 degrees. This produces a rich black color. The viewing angles of the matrices made using this technology are up to 170 degrees horizontally and vertically, which distinguishes these monitors very favorably from previous ones.

large viewing angles horizontally and vertically;

high contrast;

Disadvantages of technology;

long response time, since it is necessary to turn the molecules at a greater angle;

more powerful lamps for panel illumination;

more powerful voltages are needed to turn the molecules, since the electrodes are in the same plane;

high price;

Based on the characteristics of matrices made using this technology, it is best to use them in design tasks, where high-speed dynamic scenes are not required, but high-quality color reproduction is required.

The compromise between the high color rendering of S-PS technology and the speed of TN + film is MVA technology. The essence of this technology is that the molecules are located parallel to each other, and in relation to 2 filters at an angle of 90 degrees. The second filter has a complex structure, it consists of triangles, to the lateral sides of which the crystal molecules are deployed in this way. Falling on the second filter through the molecules, the light is polarized 90 degrees (the work of the crystal molecules) and is absorbed by the second filter, which does not transmit such light. The result is black light.

Applying voltage, the molecules begin to turn and thereby directing the light onto the filter 2 already at an angle other than 90 degrees. As a result, light begins to pass through the 2nd filter with an intensity proportional to the applied voltage. This technology, voluntarily or involuntarily, divides the screen into 2 parts, according to the direction of the molecules to the 2 filter, it turns out that being in relation to the screen from the side, the crystal molecules of the other side do not work for us. We see only the area that is closer to us and that does not distort the color. The use of this technology significantly complicates the structure of the filters-polarizers and the matrices themselves, since each point of the screen is duplicated from 2 zones.

Samsung was unwilling to pay for the license and developed its PVA technology, very similar to MVA, and with even greater contrast. Therefore, MVA / PVA is often indicated in the characteristics of monitors.

large viewing angles;

good color rendering and contrast;

Disadvantages of technology:

the complexity of making a matrix;

response time is longer than matrices of TN + film technology

This concludes the review of liquid crystal matrix technologies. As for the PLS (Plane-to-Line Switching) technology, which was recently announced by Samsung, it is most likely a development of S-IPS technology. In this case, outside experts examined the PLS and S-IPS matrices under a microscope and found no differences. Moreover, Samsung filed a lawsuit against LG, in which it argued that the AH-IPS technology used by LG is a modification of PLS, which indirectly confirms the above.

Plasma monitors are now widespread due to the fact that production technology has become cheaper. Monitors with a large diagonal are produced, since it is technologically difficult to produce with a small diagonal. Therefore, the prices for them may be higher than for widescreen ones.

The matrix of a plasma monitor consists of cells, the walls of which are coated with phosphorus, and the cells themselves are filled with an inert gas: neon or xenon. When voltage is applied to the cell, a discharge occurs, the inert gas begins to emit photons, which in turn bombard the phosphorus coating of the cell. Phosphorus, in turn, begins to emit photons of light. Everyone knows how phosphorus luminesces even in daylight.

Plasma cells have 3 colors: red, green, blue, and in this composition form a pixel. Accordingly, applying voltages of different intensities and combining colors, at the moment the color that is needed is obtained. The principle is the same as for liquid crystal matrices, just instead of crystals, cells with an inert gas are used. Moreover, each pixel cell is controlled separately, which in the best way affects the color rendition and contrast.

In general, the plasma matrix screen consists of 2 glasses, external and internal, between which there are 2 dielectric layers with electrodes. One dielectric layer is adjacent to the outer glass. This dielectric has built-in supply or shield electrodes. After the dielectric layer there is a thin layer of magnesium oxide or protective layer... And then the layer itself with cells of inert gas.

On the side of the inner glass, there is also a dielectric layer in which electrodes are embedded, which are called address or control electrodes. Thus, when voltage is applied between the supply and address electrodes, a gas-discharge current arises, which leads to the emission of photons in a separate cell and the entire plasma panel as a whole, according to the required plot.

As you can see from this description, the technology of the matrix of plasma monitors is somewhat simpler than that of liquid crystal ones. Let's now consider the pros and cons of this technology.

large viewing angles;

unmatched quality of color reproduction and contrast, saturation of the transmitted color;

absolutely flat screen and its small thickness;

short image regeneration time;

Every technology has a limit, so its

increased power consumption, since the gas-discharge effect is used;

large pixel size, which affects the resolution of a picture with fine details;

the resource of plasma panels is lower than that of liquid crystal ones;

panels with a small diagonal are more expensive than similar liquid crystal ones;

OLED-matrix consists of organic light-emitting diodes. An LED consists of a cathode and an anode with organic matter in between. When an electric current is passed, the cathode emits electrons, and the anode emits positive ions. The electric field directs these particles towards each other and recombining with each other they emit light. An anode made of indium isoxide with tin additives transmits light in the visible range.

To create color OLED displays, substances were selected that can emit light of different wavelengths, and accordingly, colors. Blue, red and green LEDs form the matrix cell. This cell controlled by applying voltage to it. The matrix controller at high speed sequentially supplies a control voltage, as in a line scan of a cathode-ray tube. Due to this, the human eye does not have time to feel the color difference when the cell received an impulse, and when it stopped acting on the cell. This OLED matrix is \u200b\u200bpassive.

There are also active OLED-matrices, where each cell is controlled by its own transistor, and all the diodes light up almost simultaneously. Such a matrix is \u200b\u200bmore expensive than a passive one, due to the complexity of production.

The possibilities of OLED technology are amazing. So, for example, not only the anode, but also the cathode can be made transparent. In this case, the display will be completely transparent, and it will not affect the perception of the picture due to the brightness of the LEDs. Alternatively, instead of a glass backing, use a flexible material. In this case, the screen can be rolled up into a tube.

Mass production of OLED monitors has not yet been observed due to the high price. And it is more difficult to produce displays with large diagonals. However, firms do not stop at their research. Samsung recently announced a 55-inch monitor, so the challenges posed by OLED technology are being overcome.

the largest viewing angles compared to other technologies;

the highest contrast among existing technologies;

response time is measured in microseconds, and for liquid crystal matrices in milliseconds;

lack of a backlight lamp, which means energy consumption is lower;

the screen thickness is even less;

can be used in a wide range of temperatures;

oLED lifetime;

the need for thorough sealing of the matrix from moisture;

high cost;

Prospects for the development of various display technologies.

On this stage An interesting picture is observed: there are several technologies for manufacturing display matrices and all of them are actively developing, getting rid of their shortcomings. With all this, there is no hard confrontation between products made using different technologies.

If you need a large screen, then choose a plasma matrix, if it is smaller, then a liquid crystal one. Need to solve design problems? Choose an S-IPS LCD display. Need a picture with more or less high definition and fast response time? Choosing MVA / PVA technology. Don't want to pay big money? Then choose TN + film. Do you want something like that? OLED monitors are on the way and are already being produced, albeit for a lot of money.

Since each technology has essentially found its own niche, accordingly there is a demand for it and it will develop further, getting rid of its shortcomings. But as soon as one of them turns out to be similar or surpass the other in terms of technological and consumer characteristics, it will accordingly oust a competitor.

Latest technology OLED is very promising, it can replace plasma displays and squeeze out liquid crystal displays, but not before the issue of an increase in the lifetime of organic LEDs and a reduction in the cost of technology is resolved.

Liquid crystal monitors are now the cheapest and they also get rid of their shortcomings, but by definition they cannot surpass plasma monitors in terms of color quality, viewing angles, screen thickness, response time and diagonal size.

Accordingly, plasma monitors cannot replace others in the class of medium and small monitors, and, accordingly, in the degree of image detail. Small details, and even on a small monitor, will look poor.

Therefore, work on improving the characteristics of matrices manufactured using different technologies is being carried out continuously, but there is no need to talk about the decisive superiority of any technology. Exceeding in some characteristics, each of them is inferior to rivals in others. Therefore, there is only one conclusion: all these technologies will develop, and therefore they are all promising.

We examined what exist types of monitors at the present time and the device of their matrices. In the next articles we will continue to review the technical characteristics of monitors.