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Introduction 3

Cathode-ray monitors 4

Two. Liquid-crystal displays 7

Three. Gas-discharge or plasma display panels (PDP). 8

References: 10

Introduction

Monitor (LCD) computer - a device designed to display textual and graphical information. It can be safely called the most important part of the personal computer. On the computer screen, we are in touch during operation. From its size and quality depends on how comfortable will our eyes. The monitor should be as safe for health in terms of various radiations. It should also be capable of a comfortable, providing the user with a quality image. Before the fifties, computer displays information only for printers. While computers are often equipped with scopes, but these were not used to display information, and to test the electronic circuitry of the computer. For the first time in 1950 at Cambridge University (England), cathode ray tube oscilloscope was used to display graphics on your computer EDASC (Electronic Delay Storage Automatic Computer). Eighteen months later, the English scientist Christopher Stretch written for a computer "Mark 1" program to play checkers and displays information on the screen. The real breakthrough in the representation of graphical information on the screen occurred in America in the War of the project based on the computer "Whirlwind." This computer was used for capturing information about the invasion of aircraft in U.S. airspace. The first demonstration of "Vortex" was held on April 20, 1951 - Radar sent information about the position of the aircraft computer, and he passed on to the screen position of the plane of the target, which is depicted as a dot and the letter T (target). It was the first major project in which the cathode ray tube is used to display graphical information.

Cathode-ray monitors

Existing monitors are distinguished by the device, diagonal screen size, refresh rate, security standards, and many others. The first cathode-ray monitors were vector. As monitors of this type of electron beam creates a line on the screen, moving directly from one set of coordinates to another. Because of this, there is no need to split the screen in pixels. Later, there were displays of raster scan. They electron beam scans the screen from left to right and top to bottom, running every time the entire surface of the screen.The next step in the development of CRT monitors has a color image, for which it was necessary to use not one but three electron beam. Each of them shed light on certain points on the surface of the display.   It is these monitors were most common. For electron-beam (CRT) monitors have their own characteristics, which are either improve your computing experience, or worsen it. One of the main characteristics of this monitor is the screen refresh rate. For cathode-ray monitors sufficient refresh rate is 85Hz. This value shows how many times per second will update the picture on the screen. If this rate is small, the eyes begin to capture the screen flicker and because of this tire quickly. The best refresh rate is 100Hz, if greater, the human eye can not perceive the difference between 100Hz and 200Hz. More about working with computers is very important resolution. After all, if the resolution is too low, then the icons on the screen is very big and not fit on the screen, and if too much resolution, icons and symbols that are too small. Because of this, my eyes get tired quickly. Below is a table of recommended and maximum resolutions.

There is also another parameter of the monitor - it is a "step mask" or "grain." The fact that the color monitors and TV screens inside the phosphor coated with tiny particles of three colors - red, green and blue glow. Three adjacent particles form a triad. If we look at the screen through a magnifying glass, glowing white light, we see that in fact the particles are illuminated in three colors, which merge into white. All other colors are due to the triad and the intensity of their glow, for example if the light is red and green only element of the triad, we see yellow. To control the emission of individual elements of the triad are three electron beams, rounds all of the triad with a frequency sweep. What would each beam got exactly the item on its triad of phosphor-coated screen is placed a special grid, which falls on the beam is deflected exactly to their element of the triad. As a result, we see that the screen color monitor, as opposed to monochrome, where the phosphor coating a continuous and homogeneous, has a granular structure. The size of these "grains" is responsible for how the image will be clear - the less "grain", the sharper the image and vice versa. The first color monitors were the size of the "grain" - 0, 42mm. With the advent of high-resolution graphics modes use these monitors was impossible: small parts, such as thin vertical bars, steel ripple and sparkle like a rainbow. Later, there were tubes with a "grain" 0.31 mm, and then 0.28 mm. Today the most common value - 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 you have not used special security measures, the monitor is awarded to us by various unhealthy emissions. CRT monitor creates, such as X-rays. But in today's monitors, it is insignificant, as is securely screened. But recently the market has been a lot of shielding that old monitor is not a luxury but a means of protection. As with any electrical device, the monitor also creates electromagnetic radiation. In addition, it also creates an electrostatic field, which promotes settling of dust on the face, neck and hands. It can cause allergic reactions in humans. Fortunately, protection against these harmful effects became more perfect, as was adopted by a number of standards. If there is an inscription on a monitor or a sticker TCO 95, TCO 99, TCO 03, then you can work without fear for their health (within reason). To date, 1995 99godov standards are outdated, and the safest standard is TCO 03 (2003god). For the first time the level of electromagnetic radiation was limited to outside, safe for humans, the standard MPR II. The following standards were tightened. Starting with the TCO 95 standard imposed to monitor the environmental and ergonomic requirements.Starting with the TCO 99 standard, also imposed stringent requirements on image quality parameters of brightness, contrast, flicker and properties of anti-glare coating screen. The monitor should be able to adjust your image. In addition, the monitor must also comply with European standards of fire and electrical safety. Another characteristic of a CRT monitor - is unreconciled rays. This term refers to the deviation of electron beams of red and blue colors from centering the green. This deviation prevents a clean colors and crisp images. There are static and dynamic unreconciled. Static is unreconciled unreconciled three colors across the surface of the screen, which usually occurs due to an error when building a cathode-ray tube. Dynamic unreconciled is unreconciled three colors on the edges and sharp image in the center. It is also important in the monitor screen cover and screen shape (spherical or flat, which is less distorted image). Screens CRT monitors may have different coverage, improving image quality and consumer properties of the monitor. Cathode-ray monitors today - very sophisticated and inexpensive device. They have excellent brightness and contrast ratio, low price, and, therefore, and availability. But there are also disadvantages. This is a fairly large weight and size, significant power consumption and harmful radiation.