Monitor (screen) computer - a device designed to display text and graphical disk imaging. It can fearlessly call the most important part of personal computer. On the monitor screen, we are in touch during operation. On its size and the quality depends on how it will be comfortably our disgusted. The monitor should be very deleterious to health in terms of various types of radiation. Finally, it must ensure the possibility of comfortable work, giving to the user a high-quality image. Before the 50's computers Prints information only for printers. While computers are often equipped with scopes, but these are not used for output, and test electrical circuits of the computer. For the first time in 1950 at the University of Cambridge (UK) cathode ray tube oscilloscope was used to display graphics on a computer disk imaging EDASC (Electronic Delay Storage Automatic Computer). Eighteen months later, the British scientist Christopher wrote a stretch for the company "Mark 1" the files of, the game of checkers, and displays the information on the screen. The real breakthrough in the representation of graphic information on the screen happened in America in the army based project company "Whirlwind". This computer was used for recording information about the invasion of aircraft in the airspace of USA. The first demonstration of "Whirlwind" was held April 20, 1951 - Radar sends information about the location of the aircraft a computer, and he passed on the screen of the target state of the aircraft, which was depicted in the form of points and the letter T (target). It was the first major project in which the cathode ray tube used to display the graphical disk imaging.
CRTs
Available now displays different device, diagonal screen size, refresh rate, security standards, and more. First cathode-ray screens were vector. In this type of monitors electrical beam produces a line on the screen, moving directly from one of the first set of coordinates to another. Because of this, there is no need to divide the screen into pixels. Later emerged screens raster scan. They electric beam scans the screen from left to right and from top to bottom, each time running through the whole plane of the screen. The next step in the development of cathode ray display has color image, for which it was necessary to use not one, but three electric beam. Any of them highlight specific points in the plane of the monitor.
It is these screens have the greatest distribution.
For cathode-ray (CRT) displays have their own characteristics that improve performance or with a computer, or exacerbate it. One of the main features of the monitor itself is the screen refresh rate. For cathode-ray displays the required refresh rate is 85Hz. This value indicates how much time will be updated in the second picture on the screen. If the low speed, the eyes begin to see the screen flicker and because of that tire quickly. The very best refresh rate is 100Hz, if greater, the human eye can not perceive the difference between 100Hz and 200Hz. More to work with a computer very principled resolution. As if the resolution is very small, the icons on the screen is very large and can not fit on the screen, and if very large resolution, the icons and signs are very small. Because of this, my eyes get tired quickly.
As there is one more parameter monitor - a "step masks" or "grain." The fact that the color monitors and TV screens inside covered with small particles of phosphor 3 colors - red, green and blue glow. Three nearby particles form a triad. If we consider a magnifying glass screen, glowing white light, we'll see if he really shone particles 3 colors that blend into white. All other colors are obtained by the triad and the intensity of their glow, for example, if the light only red and green element of the triad, we visibly yellow. To control the emission of the individual elements of the triad used three electric ray, runs around all the triad with a frequency sweep. What would each beam points exactly to your element of the triad, the phosphor coating on the screen is placed a special mesh, getting on which the beam is deflected exactly to your element of the triad.
As a result, we see that the screen color monitor, as opposed to monochrome, where the phosphor coating continuous and homogeneous, has a granular structure. The size of these "seeds" is responsible for how accurate the picture becomes - the less "grain", the clearer the image and vice versa. First color screens have a size of the "grain" - 0, 42 mm. With the release of the super high resolution graphics modes use these screens become impossible: small parts, for example, thin vertical stripes, steel ripple and all colors of the rainbow. Later emerged tubes with "grain" 0.31 mm and then 0.28 mm. Currently, the most common meaning - 0.27 mm, but in the more expensive models use a tube with an even smaller grain size - 0,2-0,24 mm.
A very important parameter is the security monitor. If it had not been used special safety measures, the monitor would have rewarded us for being different malicious radiation. Cathode ray tube monitor generates, for example, X-rays. However, the monitor is slightly advanced, as securely screened. But not so long ago, it was very much the implementation of protective screens that display old not a luxury but a means of protection. As with any electrical device, the monitor creates even electromagnetic radiation. In addition, it creates an even electrostatic field, which contributes to the dust settling on the face, neck and hands. It can cause allergic reactions in humans. Fortunately, at this time protection from these malicious actions have improved since, a number of standards. If the monitor has an inscription or label TCO 95, TCO 99, TCO 03, then it is allowed to work without fear for their health (within reason). Currently, the standard is considered harmless denbolee TCO 03 (2003god).
First degree of electromagnetic radiation was limited outside, not dangerous to humans, the standard MPR II. The following standards were tightened. Starting from the standard 95 to monitor TCO imposed environmental and ergonomic requirements. Starting with the standard TCO 99, also imposed stringent quality image settings for brightness, contrast, flicker and properties of anti-reflective screen coating. The monitor must be able to control the image. In addition, the monitor has yet to meet the European standards of fire and electrical safety. 1 more feature CRT - is unflattened beams. This term means a deviation of electric rays of red and blue from green centering. Such rejection prevents obtaining pure colors and sharp images. Recognize static and dynamic unreconciled. Static unreconciled is unreconciled 3 colors across the plane of the screen, which traditionally comes from the assembly faults cathode-ray tube. Dynamic unreconciled is unreconciled 3 colors on the edges and sharp image in the center. Just as important in the monitor screen cover and the screen shape (spherical or flat, which is less distorted image). Screens CRT displays may have different coverage, makes the best image property and consumer features of the monitor. Cathode-ray screens now - just perfect and cheap devices. They have good contrast and brightness, low cost, and, consequently, and availability. However, there they and cons. This is quite a lot of weight and size, considerable energy consumption and harmful radiation.
Liquid-crystal displays
Another type of display - liquid-crystal (LCD). First LCD materials were discovered over 100 years ago, the Austrian scientist F. Renittserom. Over time, it was found a large number of materials that can be used as an LCD modulators, but the practical implementation of the technology is comparable started recently.
Development of LCD-monitors were based on the unique properties of liquid crystals, which simultaneously possess certain qualities as a liquid (for example, flow), and solid crystals (in particular anisotropy (from the Greek. Anisos - uneven and tropos - direction - dependent properties of the medium on the direction . anisotropy characteristic, for example., mechanical, optical, magnetic, electrical and other parameters of the crystals.). LCD-panels in use that way called nematic crystals, whose molecules are in the form of elongated plates connected by a twisted spiral. LCD-element except crystals include transparent electrodes and polarizers. When voltage is applied to the electrodes of a spiral straightened. using the input and output polarizers are allowed to use a spiral effect, as an electrically controlled valve that is missing, it does not transmit light. Screen LCD-monitor consists of the LCD-matrix elements. To get the image, you must submit separate LCD-elements. recognizes two main ways of addressing and respectively two types of matrices: passive and active. in passive matrix image point is activated by applying a voltage to the electrode wires row and column . The electric field appears not only at the point of intersection of address
Active matrix LCD
conductors, but also on all current pathway that prevents the achievement of high contrast. In an active matrix of each image point charge your electric switch, which ensures the highest level of contrast. Usually active matrix realized by using thin-film field-effect transistors (Thin Film Transistor, TFT). TFT-screen, otherwise referred to as active-matrix screens, have among the highest resolution flat-panel devices, are widely used in laptops, car navigation devices, and various digital consoles.
LCD-screen does not radiate, and works as an optical shutter. Because to recreate the image would need a light source, which is located behind the LCD-panel. The lifetime of the internal light source TFT LCD-monitor depends on its type. Typically, light sources for 15-inch displays are losing about 50% of the initial luminance of 20,000 hours.
Discharge or plasma display panels (PDP).
The principle of operation is based on the plasma screen glow special phosphors (phosphorescent material) when exposed to UV radiation. In its own turn, this radiation occurs when an electric discharge in the environment of a highly rarefied gas. In this case, a number of the electrodes to a control voltage appears having "cord", consisting of ionized molecules of gas (plasma) (same principle works implemented in fluorescent - gas in the flask (glass tube) lights up when the voltage passing through it). That is why the discharge panel, working on this principle, and are called "discharge" or "plasma" panels. Feeding control signals to the vertical and horizontal
Plasma panel
conductors deposited on the inner planes of glass panels, control panel provides methods respectively "lower case" and "personnel" raster scan television image. For a given brightness of each image is determined by the time the substance emission respective "cells" plasma panel: the most striking components of "burn" continuously, and in darker locations, they are not "set on fire". Light areas of the image on the PDP (Plasma Display Panel) rovnenko light shine, so the image is not flash, than favorably with the "picture" on the screen of conventional tubes.
Plasma panel
Plasma panels are formed by filling the space between the 2 glass surfaces with an inert gas. All the space is divided into a plurality of pixels (picture elements), each of which is composed of 3 sub-pixels, so 1 out of 3 colors (red, green, and blue) (see fig.) Combining these three colors can be reproduced any other color . In each sub-pixel has tiny transparent electrodes to which a high-frequency voltage. Under the action of this pressure there is an electrical discharge. With the assistance of a gas discharge plasma with particles of phosphorus in each sub-pixel appears radiation corresponding color (red, green or blue). The work of each sub-pixel is controlled entirely by electronics, which allows each pixel to re-create 16 million different colors.
Currently, for a flat-panel displays (Flat Panel Display, FPD) uses different technologies and solutions, although the market still dominated by the time the LCD screens. As you know, the technology used in the development of advanced displays, can be conditionally divided into two categories. 1 refer to the device based on the emission of light, such as traditional products from the cathode ray tube (CRT), plasma monitors and PDP (Plasma Display Panel). The second category come translational device type, including LCD screens. Unit two groups have very specific advantages and disadvantages. If we talk about the future, promising solutions in the area of advanced displays really often combine features of the two technologies.
So, today, a lot of attention paid to the creation of monitors based on field emission (Field Emisson Display, FED). Unlike LCD screens, which work with reflected light, FED-panels themselves generate light, which makes them with screens, CRT and plasma monitors. But if the CRT only 3 electric guns, the FED-devices for each pixel is its electrode, so the panel thickness does not exceed a few millimeters. In this case, each pixel is controlled directly, as in LCDs with active matrix. The genealogy of FED-unit developments are of the mid-1990's, when engineers tried to create a truly fine picture tube.
Monitor (screen) computer - a device designed to display text and graphical disk imaging. It can fearlessly call the most important part of personal computer. On the monitor screen, we are in touch during operation. On its size and the quality depends on how it will be comfortably our disgusted. The monitor should be very deleterious to health in terms of various types of radiation. Finally, it must ensure the possibility of comfortable work, giving to the user a high-quality image. Before the 50's computers Prints information only for printers. While computers are often equipped with scopes, but these are not used for output, and test electrical circuits of the computer. For the first time in 1950 at the University of Cambridge (UK) cathode ray tube oscilloscope was used to display graphics on a computer disk imaging EDASC (Electronic Delay Storage Automatic Computer). Eighteen months later, the British scientist Christopher wrote a stretch for the company "Mark 1" the files of, the game of checkers, and displays the information on the screen. The real breakthrough in the representation of graphic information on the screen happened in America in the army based project company "Whirlwind". This computer was used for recording information about the invasion of aircraft in the airspace of USA. The first demonstration of "Whirlwind" was held April 20, 1951 - Radar sends information about the location of the aircraft a computer, and he passed on the screen of the target state of the aircraft, which was depicted in the form of points and the letter T (target). It was the first major project in which the cathode ray tube used to display the graphical disk imaging.
