The computer monitoris an output device that is part of your computer's display system. A cableconnects the monitor to a video adapter (video card) that is installedin an expansion slot on your computer’s motherboard. This system convertssignals into text and pictures and displays them on a TV-like screen (themonitor).
The computer sends asignal to the video adapter, telling it what character, image or graphic todisplay. The video adapter converts that signal to a set of instructions thattell the display device (monitor) how to draw the image on the screen.
CathodeRay 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 tubetapers near the back where there's a negatively charged cathode, or"electron gun". The electron gun shoots electrons at the back of thepositvely charged screen, which is coated with a phosphorous chemical. Thisexcites the phosphors causing them to glow as individual dots called pixels (pictureelements). The image you see on the monitor's screen is made up of thousands oftiny dots (pixels). If you've ever seen a child's LiteBrite toy, then you havea good idea of the concept. The distance between the pixels has a lot to dowith the quality of the image. If the distance between pixels on a monitorscreen is too great, the picture will appear "fuzzy", or grainy. Thecloser together the pixels are, the sharper the image on screen. The distance betweenpixels on a computer monitor screen is called its dot pitch and ismeasured in millimeters. (see sidebar). You should try to get a monitor with adot pitch of .28 mm or less.
Note:From an environmental point of view, the monitor is the most difficult computerperipheral to dispose of because of the lead it contains.
Thereare a couple of electromagnets (yokes) around the collar of the tube thatactually bend the beam of electrons. The beam scans (is bent) across themonitor from left to right and top to bottom to create, or draw the image, lineby line. The number of times in one second that the electron gun redraws theentire 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 eachpass, then the monitor is known as a non-interlaced monitor. Anon-interlaced monitor is preferred over an interlaced monitor. The electronbeam 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 almostimperceivable flicker that can cause eye-strain.
This type ofeye-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 youroptometrist.
Interlaced computermonitors are getting harder to find (good!), but they are still out there, sokeep that in mind when purchasing a monitor and watch out for that "stealof a deal".