Computer Moniter, LCD moniter,CRT monitor

A computer monitor, technically termed as a visual display unit, can be plainly described as an electronic device that transmits information from the computer onto a screen, thereby acting as an interface and connecting the viewer with the computer. At present, computer monitors are available in a variety of shapes, designs and colors. However, based on the technology used in the making of computer monitors, they can be broadly categorized into two types. These include CRT (cathode ray tube) and LCD (Liquid Crystal Technology).

CRT (Cathode Ray Tube) Monitors:

These monitors employ the CRT technology used most commonly in the manufacturing of television screens. In this, a stream of intense high energy electrons is used to form images on a fluorescent screen. A cathode ray tube is a basically a vacuum tube containing an electron gun at one end and a fluorescent screen at another end. From this electron gun, a strong beam of electrons is generated by a process called thermionic emission. These electrons are made to travel through a narrow path within the tube with high speed using various electro-magnetic devices and finally strike the phosphor points present on the fluorescent screen, thus creating an image. There are several advantages of using CRT monitors.
These monitors are highly reliable, efficient and are capable of generating a resolution up to 2048 x 1536 pixels, thereby providing a clear picture quality. Also, CRT monitors that are now available are capable of producing thousands of different colors.
Secondly, CRT monitors are affordable and cost effective.
Unlike conventional CRT monitors, modern technological advancements have resulted in the development of flat screen CRT monitors that reduce the glare and are good for your eyes.
However, the only concern with buying CRT monitors is that they are heavy and can occupy a great deal of work space. Also, these devices get heated up very easily.

LCD (Liquid Crystal Display) Monitors:

Liquid crystal display, also known as liquid crystal diode, is one of the most advanced technologies available at present. Typically, an LCD monitor consists of a layer of color or monochrome pixels arranged schematically between a couple of transparent electrodes and two polarizing filters. Optical effect is achieved by polarizing the light in varied amounts and making it pass through the liquid crystal layer. At present, there are two different types of LCD technology available. These include the active matrix or TFT, and a passive matrix technology. Among these, TFT technology is much secure, reliable and generates better picture quality. On the other hand, passive matrix has a slow response time and is slowly becoming outdated.
In the recent times, LCD monitors are becoming increasing popular with consumers. Some major advantages of using a LCD monitor include:
These monitors are compact, light in weight and do not consume much desk space.
Secondly, these monitors do not consume much electricity and can even be operated by using batteries.




Also, the images transmitted by these monitors do not get geometrically distorted and have little flicker.
However, LCD monitors do have certain disadvantages. Most importantly, these monitors are very much expensive. Secondly, image quality is not constant when viewed from different angles. Also, the resolution of an LCD monitor is always constant. Any alterations can result in a reduced performance.


Computer Monitors

The computer monitor is an output device that is part of your computer's display system. A cable connects the monitor to a video adapter (video card) that is installed in an expansion slot on your computer’s motherboard. This system converts signals into text and pictures and displays them on a TV-like screen (the monitor).
The computer sends a signal to the video adapter, telling it what character, image or graphic to display. The video adapter converts that signal to a set of instructions that tell the display device (monitor) how to draw the image on the screen.
Cathode Ray Tube (CRT)
The CRT, or Cathode Ray Tube, is the "picture tube" of your monitor. Although it is a large vacuum tube, it's shaped more like a bottle. The tube tapers near the back where there's a negatively charged cathode, or "electron gun". The electron gun shoots electrons at the back of the positvely charged screen, which is coated with a phosphorous chemical. This excites the phosphors causing them to glow as individual dots called pixels (picture elements). The image you see on the monitor's screen is made up of thousands of tiny dots (pixels). If you've ever seen a child's LiteBrite toy, then you have a good idea of the concept. The distance between the pixels has a lot to do with the quality of the image. If the distance between pixels on a monitor screen is too great, the picture will appear "fuzzy", or grainy. The closer together the pixels are, the sharper the image on screen. The distance between pixels on a computer monitor screen is called its dot pitch and is measured in millimeters. (see sidebar). You should try to get a monitor with a dot pitch of .28 mm or less.


Note: From an environmental point of view, the monitor is the most difficult computer peripheral to dispose of because of the lead it contains.

There are a couple of electromagnets (yokes) around the collar of the tube that actually bend the beam of electrons. The beam scans (is bent) across the monitor from left to right and top to bottom to create, or draw the image, line by line. The number of times in one second that the electron gun redraws the entire image is called the refresh rate and is measured in Hertz (Hz).

If the scanning beam hits each and every line of pixels, in succession, on each pass, then the monitor is known as a non-interlaced monitor. A non-interlaced monitor is preferred over an interlaced monitor. The electron beam on an interlaced monitor scans the odd numbered lines on one pass, then scans the even lines on the second pass. This results in an almost imperceivable flicker that can cause eye-strain.


This type of eye-strain can result in blurred vision, sore eyes, headaches and even nausea. Don't buy an interlaced monitor, they can be a real pain in the ... ask your optometrist.
Interlaced computer monitors are getting harder to find (good!), but they are still out there, so keep that in mind when purchasing a monitor and watch out for that "steal of a deal".