Hello, readers of my blog who are interested in a CRT monitor. I will try to make this article interesting to everyone, both those who have not caught them and those who have this device pleasantly associated with the first experience of mastering a personal computer.

Today, PC displays are flat and thin screens. But in some low-budget organizations you can also find massive CRT monitors. An entire era in the development of multimedia technologies is associated with them.

CRT monitors got their official name from the Russian abbreviation of the term “cathode ray tube.” The English equivalent is the phrase Cathode Ray Tube with the corresponding abbreviation CRT.

Before PCs appeared in homes, this electrical device was represented in our everyday life by CRT televisions. At one time they were even used as displays (go figure). But more on that later, but now let’s understand a little about the principle of CRT operation, which will allow us to talk about such monitors on a more serious level.

Progress of CRT monitors

The history of the development of the cathode ray tube and its transformation into CRT monitors with decent screen resolution is full of interesting discoveries and inventions. At first these were devices such as oscilloscopes and radar radar screens. Then the development of television gave us devices that were more convenient for viewing.

Speaking specifically about displays personal computers, accessible to a wide range of users, then the title of the first Monica should probably be given to the IBM 2250 vector display station. It was created in 1964 for commercial use along with the System/360 series computer.

IBM has developed many developments for equipping PCs with monitors, including the design of the first video adapters, which became the prototype of modern powerful standards for images transmitted to the display.

So, in 1987, a VGA (Video Graphics Array) adapter was released, working with a resolution of 640x480 and an aspect ratio of 4:3. These parameters remained basic for most manufactured monitors and televisions until the advent of widescreen standards. During the evolution of CRT monitors, many changes occurred in their production technology. But I want to highlight these points separately:

What determines the shape of a pixel?

Knowing how a kinescope works, we can understand the features of CRT monitors. The beam emitted by the electron gun is deflected by an induction magnet to precisely hit special holes in the mask located in front of the screen.

They form a pixel, and their shape determines the configuration of the colored dots and the quality parameters of the resulting image:

• Classic round holes, the centers of which are located at the vertices of a conventional equilateral triangle, form a shadow mask. A matrix with evenly distributed pixels ensures maximum quality when reproducing lines. And ideal for office design applications.
• To increase the brightness and contrast of the screen, Sony used an aperture mask. There, instead of dots, nearby rectangular blocks glowed. This made it possible to make maximum use of the screen area (Sony Trinitron, Mitsubishi Diamondtron monitors).
• It was possible to combine the advantages of these two technologies in a slotted grid, where the openings looked like elongated rectangles rounded at the top and bottom. And the blocks of pixels shifted relative to each other vertically. This mask was used in NEC ChromaClear, LG Flatron, Panasonic PureFlat displays;

But it was not only the shape of the pixel that determined the merits of the monitor. Over time, its size began to play a decisive role. It varied from 0.28 to 0.20 mm, and a mask with smaller, denser holes allowed for high-resolution images.

An important and, alas, noticeable characteristic for the consumer remained the screen refresh rate, expressed in image flickering. The developers tried their best, and gradually, instead of the sensitive 60 Hz, the dynamics of changing the displayed picture reached 75, 85 and even 100 Hz. The latter indicator already allowed me to work with maximum comfort and my eyes hardly got tired.

Work to improve quality continued. The developers did not forget about such an unpleasant phenomenon as low-frequency electromagnetic radiation. In such screens, this radiation is directed by an electron gun directly at the user. To overcome this shortcoming, all kinds of technologies have been used and various protective screens and protective coatings for screens have been used.

The safety requirements for monitors have also become more stringent, which are reflected in constantly updated standards: MPR I, MPR II, TCO"92, TCO"95 and TCO"99.

The monitor professionals trust

Work on the constant improvement of multimedia video equipment and technologies over time led to the emergence of high-definition digital video. A little later, thin backlit screens appeared from economical LED lamps. These displays are a dream come true because they:

• lighter and more compact;
• characterized by low energy consumption;
• much safer;
• had no flicker even for more low frequencies(there is a flicker of a different kind);
• had several supported connectors;

And it was clear to non-specialists that the era of CRT monitors was over. And it seemed that there would be no return to these devices. But some professionals, who know all the features of new and old screens, were in no hurry to get rid of high-quality CRT displays. Indeed, according to some technical characteristics, they clearly outperformed their LCD competitors:

• excellent viewing angle, allowing you to read information from the side of the screen;
• CRT technology made it possible to display images at any resolution without distortion, even when using scaling;
• there is no concept of dead pixels here;
• The inertia time of the afterimage is negligible:
• an almost unlimited range of displayed shades and stunning photorealistic color rendering;

It was the last two qualities that gave CRT displays a chance to prove themselves once again. And they are still in demand among gamers and, especially, among specialists working in the field graphic design and photo processing.

Here's a long and interesting story about a good old friend called a CRT monitor. And if you still have one of these at home or at your business, you can try it out again and re-evaluate its qualities.

With this I say goodbye to you, my dear readers.

What is a CRT monitor?

CRT (CRT) monitor- a device that is designed to display various information (graphics, video, text, photos). The CRT (Cathode Ray Tube) monitor image is formed thanks to a special electro-ray tube, which is the main component of this device. Typically, such monitors are used to display images from computers, acting as a display.

A brief history of the appearance of CRT monitors

The progenitor of CRT monitors can be considered Ferdinand Braun, who in 1897 developed the fundamental principle of image formation using a cathode ray tube. This German scientist devoted a lot of time to research related to cathode rays.

From the very beginning, the Brown tube (CRT) was used as an oscilloscope to experiment with electrical vibrations. It was a glass tube with an electromagnet located on the outside. Although Brown did not patent his unique invention, it became a powerful impetus for the creation of CRT monitors. First serial TVs with electro-ray tubes appeared in the 1930s. Moreover, CRT monitors began to be used already in the 1940s. Subsequently, the technology was constantly improved, and the black and white picture was replaced with a high-quality color image.

CRT monitor design

If we consider the characteristics of CRT monitors, then their main link is the electro-ray tube. This is the most important element, which is also called a kinescope. There are deflection and focusing coils that direct the electron beams. It is worth noting the shadow mask and the internal magnetic screen through which the rays pass to display the picture.

Each CRT monitor is equipped with a mounting bracket for reliable protection of the internal structure. There is also a phosphor coating, which creates the necessary colors. Glass could not be avoided either, because it is what the user constantly sees in front of him.

Operating principle of a CRT monitor

The sealed electro-ray tube is made of glass. There is absolutely no air inside it. The neck of the tube is not only long, but also quite narrow. Its other part is called the screen, and also has a wide shape. The front of the glass tube is coated with phosphor (a mixture of rare metals). An image is created using an electron gun. It is from here that electrons begin their rapid path to the display surface, bypassing the shadow mask. Since the beam must hit the entire screen surface, it begins to deviate in terms of the plane.

Therefore, the movement of the electron beam can be vertical or horizontal. When electrons hit the phosphor layer, their energy is transformed into light. Thanks to this, we see different color shades.

This is how images are formed in CRT monitors. Moreover, the human eye is able to clearly recognize red, green and blue colors. Everything else is a combination of these colors with each other. For this reason, CRT monitors latest generation are equipped with three electron guns, each of which emits a specific light.

CRT monitor settings

When users purchase a new display, they often wonder how to configure a CRT monitor as correctly as possible? Of course, you can use professional calibrators. But for this you need to be a real specialist for this equipment to bring the desired effect. Or you can use the services of appropriate specialists who will come to you with a calibrator for high-quality monitor settings.

There is a much cheaper and simpler option in the form of manual image adjustment. Almost every monitor has a corresponding settings menu that can be changed.

1. You should set the screen resolution from the very beginning. The higher it is, the more detailed the picture will be. Here, a lot also depends on the diagonal of the display. If the monitor is 17-inch, then the optimal resolution will be 1024 by 768 pixels. If it is 19-inch, then 1280 by 960 pixels.
2. You don't need to try to increase the resolution too much to prevent the image from becoming extremely small.
3. Screen refresh rate is another important parameter of a CRT monitor. Numerous safety standards set a minimum threshold of 75 Hz. When frequency personnel scan below given value, then noticeable flicker will create a strong strain on your eyes. Recommended refresh rates range from 85-100 Hz.
4. With flexible adjustment of contrast and brightness, you can get an almost perfect picture. It is advisable to do this, because factory setting may not seem the most successful to the user. Moreover, we all have our own ideas about a quality image. Some people will want to make the picture as juicy as possible, while others will prefer calmer shades. In terms of setting the appropriate values, you need to be guided solely by your feelings and perceptions. That is why there are no ideal contrast and brightness parameters. At the same time, I want to make the image brighter on sunny days. But in the dark, it’s better to lower the contrast level so that your eyes don’t get tired of the abundance of colors.
5. If desired, you can also adjust the image geometry. To do this, you need to use the built-in tools, or download a third-party program (for example, Nokia Monitor Test). An excellent result is achieved if the test picture fits completely into the screen. It is also possible to adjust the vertical and horizontal lines so that they are as straight as possible.

Advantages and disadvantages of CRT monitors

The main advantages of a CRT monitor:

• Natural colors are transmitted as accurately as possible and without distortion.
• High-quality picture from any angle.
• There is no problem with dead pixels.
• High response speed, which will especially appeal to fans of games and movies.
• Really deep black color.
• Increased contrast and image brightness.
• Possibility of using commutation 3D glasses.

The main disadvantages of a CRT monitor:

• Significant physical dimensions.
• Problem with displaying geometric shapes and their proportions.
• Large invisible area in terms of diagonal selection.
• Quite harmful radiation.
• Increased electricity consumption.

What is dangerous about CRT monitors is their harmful electro-ray radiation. It creates a powerful electromagnetic field that negatively affects health. It is highly not recommended to be behind such a screen, because the harmful field extends back to a distance of one and a half meters. It is also necessary to properly dispose of such monitors so that lead oxide and other harmful substances do not spoil the environment.

Where are CRT monitors used?

CRT monitors are almost always used in conjunction with system unit. Their main task is to display text and graphic information, which comes from the computer device. They are often used at home, and can also be found in offices and offices. Such displays are used in a variety of areas of life. On this moment they are actively being replaced by LCD monitors.

Comparison of CRT and LCD monitors

Unfortunately, the era of CRT monitors is gradually coming to an end. They are being replaced by more advanced and advanced liquid crystal displays, which take up much less space on our desks.

Here's the difference between CRT and LCD monitors:

Energy consumption. LCD screens consume less power than CRT monitors.

If LCD monitors have a stable and safe screen refresh rate, then monitors with electro-ray tubes allow you to select a lower or higher frame rate.

Safety. LCD models win here, as they emit much less harmful radiation.

Image quality. CRT monitors reproduce natural colors more accurately and also boast deep shades of black.

Viewing Angles. CRT screens have better viewing angles. At the same time, some expensive LCD matrices are trying to level out the lag.

One of the most well-known problems with LCD monitors is slow response time. Here the advantage is on the side of CRT displays.

Dimensions. LCD monitors are compact physical dimensions, which cannot be said about similar devices with CRT technology. The difference is especially noticeable in terms of thickness.

Now liquid crystal displays come in a variety of diagonals, reaching up to 37 inches or more. In this regard, CRT options offer more limited solutions up to 21 inches.

Although CRT monitors can be called outdated, they can still please the user with high-quality pictures, fast response and other important advantages.

Before the advent of LCD technology, personal computers were equipped with CRT monitors. They are distinguished by their large dimensions and large mass.

IMPORTANT. Using CRT monitors is not energy efficient. In particular, the electricity consumption of such displays is comparable to high-power incandescent lamps.

The quality of the resulting image is characterized by high clarity. Therefore, this type of monitor is in demand for the graphic design of raster images.

A CRT monitor is equipped with a glass vacuum tube. The inner part of this element facing the user is coated with a special composition - Luminofor. This special coating emits light when bombarded with electrons. The composition of this layer in color CRT devices includes complex elements based on rare earth metals. The brightness and period of glow created by the phosphor depends on the percentage and properties of the components used.

Principle of operation

The formation of a picture on such a display occurs using an electron beam gun. It emits a stream of electrons that pass through a specialized metal mask and are directed to the inside of the glass surface of the display.

The flow of charged electric particles on the way to the front surface of the screen is converted in an intensity modulator, which accelerates the system. The operation is based on the principle of potential difference. Due to the passage through the modulator, charged particles receive a lot of energy, which is spent on illuminating the pixels. Electrons enter the luminofor, then the energy of the electrons contributes to the glow of certain areas of the screen. Activation of pixels ensures the formation of a picture.

REFERENCE. Conventional CRT color monitors use the RGB color palette.

The housing contains three electronic emitters. They generate one of 3 basic shades and transmit a beam of electric particles to certain areas of the phosphor layer. The intensity of the glow of each tone from the palette is different. This parameter is varied in such a way that by increasing the power of each of the three beams to the maximum, white light will be formed. By combining all three basic tones at a minimum level, a gray or black pixel will be obtained. A mask is a design element that ensures precise illumination of the required area of ​​the screen with an electron beam. Design features masks are determined by the type of kinescope and the brand. The quality of this element affects the clarity of the picture (rasterization).

Today, the most common type of monitor is CRT (Cathode Ray Tube) monitors. As the name implies, the basis of all such monitors is a cathode ray tube, but this is a literal translation, technically it is correct to say a cathode ray tube (CRT). Sometimes CRT also stands for Cathode Ray Terminal, which no longer corresponds to the tube itself, but to the device based on it.
The technology used in this type of monitor was developed by the German scientist Ferdinand Braun in 1897. and was originally created as a special tool for measuring alternating current, that is, for an oscilloscope.

Let's look at the design of CRT monitors:

The most important element of the monitor is the kinescope, also called a cathode ray tube (the main structural components of the kinescope are shown in Fig. 1.1). The kinescope consists of a sealed glass tube, inside of which there is a vacuum, that is, all air has been removed. One of the ends of the tube is narrow and long - this is the neck, and the other is wide and quite flat - this is the screen. On the front side, the inner part of the glass of the tube is coated with luminophor. Quite complex compositions based on rare earth metals - yttrium, erbium, etc. - are used as phosphors for color 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, because The phosphor used in the coating of CRTs 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 the “glow” occurs for a short amount of time (by the way, white phosphorus is a strong poison).

To create an image, a CRT monitor uses an electron gun, from which a stream of electrons is emitted under the influence of a strong electrostatic field. Through a metal mask or grille they fall onto the inner surface of the glass monitor screen, which is covered with multi-colored phosphor dots.
The flow of electrons (beam) can be deflected in the vertical and horizontal planes, which ensures that it consistently reaches the entire field of the screen. The beam is deflected by means of a deflection system [see Figure 1.2]. Deflection systems are divided into saddle-toroidal and saddle-shaped. The latter are preferable because they create a reduced level of radiation.

The deflection system consists of several inductance coils located at the neck of the kinescope. Using an alternating magnetic field, two coils create a deflection of the electron beam in the horizontal plane, and the other two in the vertical plane.
A change in the magnetic field occurs under the influence of an alternating current flowing through the coils and changing according to a certain law (this is, as a rule, a sawtooth change in voltage over time), while the coils give the beam the desired direction. The path of the electron beam on the screen is shown schematically in Fig. 1.3. Solid lines are the active beam stroke, the dotted line is the reverse one.

Transition frequency new line called the horizontal (or horizontal) scan frequency. The frequency of transition from the lower right corner to the upper left is called the vertical (or vertical) frequency. The amplitude of the overvoltage pulses on the horizontal scanning coils increases with the frequency of the lines, so this node turns out to be one of the most stressed parts of the structure and one of the main sources of interference in a wide frequency range. The power consumed by horizontal scanning units is also one of the serious factors taken into account when designing monitors.
After the deflection system, the flow of electrons on the way to the front part of the tube passes through an intensity modulator and an accelerating system, operating on the principle of potential difference. As a result, electrons acquire greater energy [see formula 1.1], part of which is spent on the glow of the phosphor.

where E is energy, m is mass, v is velocity.

The electrons hit the phosphor layer, after which the energy of the electrons is converted into light, i.e. The flow of electrons causes the phosphor dots to glow. These glowing phosphor dots form the image you see on your monitor. Typically, a color CRT monitor uses three electron guns, as opposed to the single gun used in monochrome monitors, which are rarely produced today.
It is known that human eyes react to the primary colors: red (Red), green (Green) and blue (Blue) and to their combinations that create an infinite number of colors. The phosphor layer covering the front of the cathode ray tube consists of very small elements (so small that the human eye cannot always distinguish them). These phosphor elements reproduce primary colors; in fact, there are three types of multi-colored particles, whose colors correspond to the primary RGB colors (hence the name of the group of phosphor elements - triads).
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 glow of primary colors with different intensities is combined to form an image with the desired color. For example, if you activate red, green and blue phosphor particles, their combination will form white.
To control a cathode ray tube, control electronics are also required, 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 determines the difference between monitors with the same cathode ray tube.
So, each gun emits an electron beam (or stream, or beam) that affects phosphor elements of different colors (green, red or blue). It is clear that the electron beam intended for the red phosphor elements should not affect the green or blue phosphor. To achieve this action, a special mask is used, whose structure depends on the type of picture tubes from different manufacturers, providing 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 slit and shadow masks, although it would be more accurate to say that they are all shadow masks. In this case, tubes with a planar arrangement of electron guns are also called picture tubes with self-converging beams, since the effect of the Earth’s magnetic field on three planarly located beams is almost identical and when the position of the tube relative to the Earth’s field changes, no additional adjustments are required.

Shadow mask

Shadow mask is the most common type of mask; it has been used since the invention of the first color picture tubes. The surface of picture tubes with a shadow mask is usually spherical in shape (convex). This is done so that the electron beam in the center of the screen and at the edges has the same thickness.

The shadow mask consists of a metal plate with round holes that occupy approximately 25% of the area [see rice. 1.5, 1.6]. The mask is placed in front of a glass tube with a phosphor layer. As a rule, most modern shadow masks are made from invar. Invar (InVar) is a magnetic alloy of iron and nickel. width="185" height="175" border="2" hspace="10">This material has an extremely low coefficient of thermal expansion, so although the electron beams heat the mask, it does not negatively affect color purity Images. The holes in the metal mesh act as a sight (albeit not an accurate one), which ensures that the electron beam hits only the required phosphor elements and only in certain areas. The shadow mask creates a grid of uniform dots (also called triads), where each dot consists of three phosphor elements of the primary colors - green, red and blue - which glow with different intensities when exposed to beams from electron guns. By changing the current of each of the three electron beams, you can achieve an arbitrary color of the image element formed by a triad of dots.
One of the "weak" points of monitors with a shadow mask is its thermal deformation [see. rice. 1.7]. Some of the rays from the electron beam gun hit the shadow mask, resulting in heating and subsequent deformation of the shadow mask. The resulting displacement of the shadow mask holes leads to the effect of screen variegation (RGB color shift). The material of the shadow mask has a significant impact on the quality of the monitor. The preferred mask material is Invar.

The disadvantages of a shadow mask are well known: firstly, it is a small ratio of electrons transmitted and retained by the mask (only about 20-30% passes through the mask), width="250" height="211" border="2" hspace="10" >which requires the use of phosphors with high luminous efficiency, and this in turn worsens the monochrome of the glow, reducing the range of color rendering, and secondly, it is quite difficult to ensure an exact coincidence of three rays that do not lie in the same plane when they are deflected at large angles.
Shadow mask is used in most modern monitors - Hitachi, Panasonic, Samsung, Daewoo, LG, Nokia, ViewSonic.
The minimum distance between phosphor elements of the same color in adjacent rows is called dot pitch and is an index of image quality [see rice. 1.8]. Dot pitch is usually measured in millimeters (mm). The smaller the dot pitch value, the higher the quality of the image reproduced on the monitor. The horizontal distance between two adjacent points is equal to the pitch of the wheelbarrows multiplied by 0.866.

Aperture grille

There is another type of tube that uses an "Aperture Grille". These tubes became known as Trinitron and were first introduced to the market by Sony in 1982. Aperture array tubes use an original technology where there are three beam guns, three cathodes and three modulators, but there is one common focusing [see. rice. 1.9].

An aperture grille is a type of mask used by different manufacturers in their technologies to produce picture tubes that go by different names but are essentially the same, such as Sony's Trinitron technology, Mitsubishi's DiamondTron and ViewSonic's SonicTron. This solution does not include a metal grid with holes, as is the case with the shadow mask, but has a grid of vertical lines [see rice. 1.10]. Instead of dots with phosphor elements of three primary colors, the aperture grille contains a series of threads consisting of phosphor elements arranged in vertical stripes of three primary colors. This system provides high image contrast and good color saturation, which together provides high quality monitors with tubes based on this technology. The mask used in Sony (Mitsubishi, ViewSonic) handsets is a thin foil on which thin vertical lines are scratched. It is held on a horizontal wire (one in 15", two in 17", three or more in 21"), the shadow of which is visible on the screen. This wire is used to dampen vibrations and is called a damper wire. It is clearly visible, especially with a light background images on the monitor. Some users fundamentally do not like these lines, while others, on the contrary, are happy and use them as a horizontal ruler.
The minimum distance between phosphor strips of the same color is called strip pitch and is measured in millimeters (mm) [see rice. 1.10]. The smaller the stripe pitch value, the higher the image quality on the monitor. With an aperture array, only the horizontal size of the dot makes sense. Since the vertical is determined by the focusing of the electron beam and the deflection system.
The aperture grille is used in monitors from ViewSonic, Radius, Nokia, LG, CTX, Mitsubishi, and in all monitors from SONY.

Crevice mask

Slot mask is a technology widely used by NEC under the name "CromaClear". This solution in practice is a combination of a shadow mask and an aperture grille. In this case, the phosphor elements are located in vertical elliptical cells, and the mask is made of vertical lines [see. rice. 1.11]. In fact, the vertical stripes are divided into elliptical cells that contain groups of three phosphor elements of three primary colors.
The slot mask is used, in addition to monitors from NEC (where the cells are elliptical), in Panasonic monitors with a PureFlat tube (formerly called PanaFlat). Note that you cannot directly compare step sizes for tubes different types: The pitch of the dots (or triads) of a shadow mask tube is measured diagonally, while the pitch of the aperture array, otherwise known as the horizontal dot pitch, is measured horizontally. Therefore, with the same pitch of points, a tube with a shadow mask has a higher density of points than a tube with an aperture grid. For example, a stripe pitch of 0.25 mm is approximately equivalent to a dot pitch of 0.27 mm.

Also in 1997 Hitachi, the largest designer and manufacturer of CRTs, developed EDP - latest technology shadow mask. In a typical shadow mask, the triads are placed more or less equilaterally, creating triangular groups that are distributed evenly across the inner surface of the tube [see Fig. rice. 1.12]. Hitachi has reduced the horizontal distance between the elements of the triad, thereby creating triads that are closer in shape to an isosceles triangle. To avoid gaps between the triads, the dots themselves have been elongated, appearing more like ovals than circles.

Both types of masks - the shadow mask and the aperture grille - have their advantages and their supporters. For office applications, text editors and electronic tables, picture tubes with a shadow mask are more suitable, providing very high image clarity and sufficient contrast. To work with raster and vector graphics Tubes with an aperture grille are traditionally recommended for their excellent image brightness and contrast. In addition, the working surface of these picture tubes is a cylinder segment with a large horizontal radius of curvature (unlike CRTs with a shadow mask, which have a spherical screen surface), which significantly (up to 50%) reduces the intensity of glare on the screen.
Cathode ray tubes are manufactured primarily in Japan. For some series of monitors from Acer, Daewoo, LG Electronics, Philips, Samsung and ViewSonic, tubes are manufactured by Hitachi. ADI and Daewoo products use Toshiba tubes. Apple, Compaq, IBM, MAG and Nokia use Sony Trinitron CRTs. Finally, Mitsubishi supplies CRTs to CTX, Iiyama and Wyse, and Panasonic tubes (Matsushita) can be found in CTX, Philips and ViewSonic monitors. Often, handset manufacturers are overwhelmed with orders, so different suppliers contribute to the production of monitors of the same series.

Modern CRTs

FD Trinitron (Sony)

Currently, all CRT monitors produced by Sony have a flat outer screen surface (even models with a diagonal of 15"). The technology that Sony uses in its monitors has been developed by the company for more than thirty years, and it is not an exaggeration to say that it has gained worldwide fame It all started with the invention of Trinitron technology in 1968. In 1982, Sony released the first computer display using Trinitron CRT technology.In 1998, the company introduced the first flat screen monitor using FD Trinitron technology.

Trinitron CRTs, which are well known to everyone from household TVs, differed from conventional ones in that they had a cylindrical rather than spherical screen surface. Let us dwell on the interesting points that distinguish FD Trinitron technology.

First of all, it is high resolution. To achieve high resolution, it is necessary to have three components - a very thin screen mask, a minimum diameter of the electron beam and error-free positioning of this beam over the entire surface of the screen. This task is fraught with many difficulties. For example, reducing the diameter of the electron beam causes a decrease in image brightness. To compensate for the loss in brightness, it is necessary to increase the power of the electron beam, but this leads to a reduction in the service life of the phosphor coating and the code of the electron gun itself, which serves as a source of electrons.

The FD Trinitron uses an electron gun design called SAGIC (Small Aperture G1 with Impregnated Cathode). It uses the usual barium cathode, but enriched with tungsten, which allows you to extend the life of the CRT. In addition, the diameter of the filter hole in the first element of the G1 electron gun array is reduced to 0.3 mm compared to the usual 0.4 mm, resulting in a thinner electron beam output.

As a screen mask, Sony uses an aperture grille with a pitch of 0.22-0.28 mm (This indicator varies not only depending on the monitor model. In the monitor itself, the mask pitch can be different in the center and in the peripheral areas). Using an aperture grille instead of a shadow mask allows more electrons to reach the surface of the phosphor coating, resulting in a cleaner, better focused and brighter image. In addition, the electron gun uses special focusing systems: DQL (Dynamic Quadropole Lens), MALS (Multi Astigmatism Lens System) and EFEAL (Extended Field Elliptical Aperture Lens). They allow you to obtain a thin and perfectly focused electron beam spot anywhere on the screen.

All FD Trinitron CRT monitors have a special multi-layer coating (4 to 6 layers), which performs several functions. Firstly, it allows you to obtain true colors on the surface of the screen by reducing reflected light. In addition, thanks to an additional special black anti-reflective coating layer (Hi-Con™), contrast is increased and the reproduction of gray shades is significantly improved. In addition, this black coating, unique to FD Trinitron, absorbs both direct and reflected light, increasing image contrast.

Flatron (LG Electronics)

The main difference between a Flatron CRT and picture tubes from other manufacturers is that it uses an absolutely flat screen surface, both outside and inside, to form an image. This made it possible to increase the viewing angle and, as a result, the visible image area. LG Flatron monitors use a slit mask, which allows you to reproduce images with high resolution (the mask pitch on the 17" LG Flatron 775FT and 795FT Plus monitors is 0.24 mm). In addition, in the LG Flatron CRT, the thickness of the mask is reduced, which improves the quality of the generated image electron spot screen.

The LG Flatron uses a specially designed electron gun - the Hi-Lb-MQ Gun. In conventional guns, the electron spot at the edges of the screen has an oval shape. This leads to the appearance of moire and a decrease in horizontal resolution. The focusing system used in the Hi-Lb-MQ Gun allows you to achieve an almost ideal shape of the electron spot over the entire surface of the screen. Changes have also been made to the design of the electron gun lattice - an additional G3 filter element has been added.

Another notable feature of Flatron is the anti-reflective and antistatic W-ARAS coating, which significantly reduces the amount of reflected light and at the same time allows for the lowest light transmittance of the screen (38% versus 40-52% for competitors).

ErgoFlat (Hitachi)

The ErgoFlat CRT uses a shadow mask with a very small pitch (for example, the Hitachi CM771 model has a mask pitch of 0.22 mm horizontally and 0.14 mm vertically).

CRT monitor device

The image is created by a beam of electrons incident on the inner surface of a cathode ray tube (CRT or CRT - Cathode Ray Tube), coated with a layer of phosphor (a compound based on zinc and cadmium sulfides). The electron beam is emitted by the electron gun and is controlled by the electromagnetic field created by the monitor's deflection system.
To create a color image, three electron guns are used and three types of phosphor are applied to the surface of the CRT to create red, green and blue (RGB), which are then mixed. Mixed with equal intensity, these colors give us the color white.
A special device is placed in front of the phosphor<маска> (<решетка>), narrowing the beam and focusing it on one of the three sections of the phosphor. The monitor screen is a matrix consisting of triad sockets of a certain structure and shape, depending on the specific manufacturing technology:

• three-point shadow mask (Dot-trio shadow-mask CRT)
• slotted aperture grille (Aperture-grille CRT)
• nest mask (Slot-mask CRT)

CRT with shadow mask
For this type of CRT, the mask is a metal (usually Invar) grid with round holes opposite each triad of phosphor elements. The criterion for image quality (sharpness) is the so-called grain pitch or dot pitch, which characterizes the distance in millimeters between two phosphor elements (dots) of the same color. The shorter this distance, the higher quality image the monitor can reproduce. A CRT screen with a shadow mask is usually part of a sphere with a fairly large diameter, which can be noticeable by the convexity of the screen of monitors with this type of CRT (or may not be noticeable if the radius of the sphere is very large). The disadvantages of a CRT with a shadow mask include the fact that a large number of electrons (about 70%) are retained by the mask and do not reach the phosphor elements. This can cause the mask to heat up and become thermally distorted (which can cause colors on the screen to distort). In addition, in CRTs of this type it is necessary to use a phosphor with higher light output, which leads to some deterioration in color rendition. If we talk about the advantages of CRTs with a shadow mask, then we should note the good clarity of the resulting image and their relative cheapness.

CRT with aperture grille
In such a CRT there are no pinholes in the mask (usually made of foil). Instead, thin vertical holes are made in it from the top edge of the mask to the bottom. Thus, it is a lattice of vertical lines. Due to the fact that the mask is made in this way, it is very sensitive to any kind of vibration (which, for example, can occur when lightly tapping on the monitor screen. It is additionally held in place by thin horizontal wires. In monitors with a size of 15 inches, such a wire is one in 17 and 19 two , and in large ones three or more. On all such models, shadows from these wires are noticeable, especially on a bright screen. At first they can be somewhat annoying, but over time you will get used to it. Probably this can be attributed to the main disadvantages of CRTs with an aperture grille. The screen of such CRTs is is part of a large diameter cylinder. As a result, it is completely flat vertically and slightly convex horizontally. An analogue of the dot pitch (as for a CRT with a shadow mask) here is the strip pitch - the minimum distance between two phosphor strips of the same color (measured in millimeters).The advantage of such CRTs compared to the previous one is more rich colors and a more contrasting image, as well as a flatter screen, which quite significantly reduces the amount of glare on it. The disadvantages include slightly less clarity of the text on the screen.

CRT with slit mask
The slit mask CRT is a compromise between the two technologies already described. Here, the holes in the mask corresponding to one phosphor triad are made in the form of elongated vertical slits of short length. Adjacent vertical rows of such slits are slightly offset relative to each other. It is believed that CRTs with this type of mask have a combination of all the advantages inherent in it. In practice, the difference between the image on a CRT with a slit or aperture grating is little noticeable. CRTs with a slit mask are usually called Flatron, DynaFlat, etc.

Technical specifications
Specifications monitors in price lists and on packaging are usually expressed in one line like “Samsung 550B / 15” / 0.28 / 800x600 / 85Hz”, which stands for:

• 15" is the screen diagonal size in inches (38.1 cm). In general, the larger the monitor, the more convenient it is to use. For example, with the same resolution, a 17-inch monitor reproduces the image in the same way as a 15-inch one, but the picture itself turns out to be physically larger and the details stand out more clearly. However, in reality, part of the CRT screen at the edges is hidden by the housing or lacks phosphor. Therefore, take an interest in such a parameter as the visible diagonal. For 17-inch monitors from different manufacturers, this parameter can be from 15.9" and higher.
• 0.28 - dot size. This is one of the main indicators of monitor quality. In fact, this parameter characterizes the size of each pixel in the image: the smaller this size, the closer the pixels are to each other and the more detailed the image appears. More expensive monitors have a dot size of 0.25 or 0.22. Keep in mind that dot sizes larger than 0.28 lose a significant amount of detail and create grain on the screen.
• 800 x 600 - recommended or maximum possible resolution (in the example - recommended). This means that the screen has 800 pixels per line horizontally and 600 lines vertically. With a higher resolution (1024x768) on the screen, you can display more different images, data at once, or a Web page without scrolling. This parameter also depends on the properties of the video card: some video cards do not support high resolutions.
• 85 Hz - maximum screen refresh rate (regeneration frequency, vertical frequency, FV). This means that each pixel on the screen changes 85 times per second. The more times the screen is crossed out every second, the more contrast and stability the image becomes. If you intend to carry out long hours in front of the monitor, your eyes will be less tired if the monitor has a higher refresh rate - at least 75 Hz. At higher resolutions, the screen refresh rate may decrease, so you need to keep these settings balanced. The refresh rate also depends on the properties of the video card: some video cards support high resolutions only at a low refresh rate. A monitor screen with a matte (anti-glare) finish can be very useful in a brightly lit office. The same problem can be solved by a special matte panel attached to the monitor.
• TCO 99 is a safety standard. The standards are set by the Swedish Technical Accreditation Authority (MPR) or European standard TSO. The essence of TCO recommendations is to determine the minimum acceptable parameters of monitors, for example, supported resolutions, phosphor glow intensity, brightness reserve, power consumption, noise, etc. Compliance of the monitor with the TCO standard is confirmed by a sticker.

Main advantages

• Low price. CRT monitor 1.5-4 times cheaper LCD display similar class.
• Longer service life. MTBF CRT monitor several times higher than that of LCD display. Actual service life LCD monitor does not exceed four years, while CRT devices have to be replaced due to moral rather than physical obsolescence. The problem is further aggravated by the fact that the backlights of a number of models LCD displays cannot be replaced, and they are the ones that most often fail. Moreover, the image quality LCD displays Over time it degrades, in particular, a foreign tint appears. CRT screens do not have the problem of “dead pixels”, a small number of which is not considered defective. In addition, LCD matrices are very sensitive to static electricity, shocks and shocks. Plus, light weight and small dimensions LCD displays cause such additional risks, like the probability of falling from the table and theft.
• Fast response time, while LCD displays There is a significant inertia of the image. So if the task is to create animations for the Web or presentations, then LCD display would not be the best choice.
• High contrast. On LCD displays Only in the latest models have things started to improve, and in mass-produced models one can only dream of pure black.
• No restrictions on viewing angle, while LCD displays they exist, and they are very significant.
• Lack of image discreteness. The peculiarities of image formation on a CRT are such that the elements are blurred and therefore practically invisible to the naked eye. And on LCD displays the image has a distinct discreteness, especially at non-standard resolutions.
• No problems associated with image scaling. On CRT monitor you can change the screen resolution within a fairly wide range, while LCD display Comfortable work is possible only with one resolution.
• Good color rendition. On mass LCD displays With TN+Film and MVA/PVA matrices this is far from all right, and they are still not recommended for use with color printing and video.

Flaws

• Radiation. Electromagnetic and soft x-ray radiation. Although monitors are considered one of the most secure office devices, in fact the radiation from them is through the roof. Let the monitor screen be protected. And what's behind? And the fact is that the main radiation from the monitor comes from its back. So if there are several computers in the office, it is better not to sit around all day back cover neighbor's CRT monitor, but rearrange the furniture so that it at least rests against the wall. But the screen, although protected, still emits a fair amount of radiation. I myself have sat behind so many models of monitors - from monochrome ones that came with machines produced in 1982 (on Intel 8086) - to modern ones CRT monitors highest price category. For all of them, the sensations were approximately the same - after some time (the better the monitor, the longer the time, naturally) a certain discomfort was felt. Even just being near a working monitor cannot avoid this. I also need to say about<пользе>protective screens. Yes, they seem to protect the user, but they usually just<отодвигают>electromagnetic field. It turns out that just before the screen it is reduced, and about a meter and a half later, it is seriously increased.
• Flicker. Theoretically, it is believed that after 75 hertz the human eye does not see flicker. But this, believe me, is not entirely true. Even at a higher screen refresh rate, the eye gets tired of this, albeit imperceptible, flickering. Again, sometimes you go into an office and there is a computer there. It seems to be new, the monitor is normal, but when you look at it, it immediately looks bad - the refresh rate is 65 hertz. And those who have been working on it for several months do not notice anything.
• A non-obvious factor is dust. The point here is this. Dust settles on the monitor screen, like everything else. The screen, even if well protected, becomes electrified and electrifies the dust that has settled on it. From the physics course we know that like charges repel. And a stream of dust begins to slowly fly towards the unsuspecting user. As a result, the eyes become irritated. Sometimes very much. Especially if a person suffers from myopia and tries to take off his glasses to take a closer look at the image.
• Phosphor burnout
• High power consumption