CRT Monitors
- Up until recently, CRTs (Cathode RayTubes) were the only type of displays for use with desktop PCs. They are relatively big (14" to 16" deep) and heavy (over 15 lbs).
- They are available in screen sizes from 14" to 21". A 17" display means that it is 17" measured diagonally from one corner of the tube to the other. The actual viewing area is smaller than 17" (about 16") since the electron gun can't sweep completely to the tube edge.
- CRTs send a stream of electrons at the screen, which is charged to about 25,000 volts. As they strike it they cause phosphor on the backside of the screen to glow creating light which you see. The electron stream is sweep back and forth and up and down at about 60 sweeps per second and turned off and on at the right time to make text and graphics images appear.
- They are powered by standard 120Vac wall power.
- Data is transferred to the display on a cable with a 15-pin D-shell connector that plugs into a connector on the video card which in turn plugs into one of the PC's expansion slots.
- A 17" monitor with 1280 x 1024 resolution and .27mm dot pitch sells for around $150.
LCD Monitors
- Liquid Crystal Display (LCD) technology has been used in laptops for some time. It has recently been made commercially available as monitors for desktop PCs.
- LCDs have no electron gun and are therefore not very deep like CRTs. The text and images you see are created by a back light behind the panel, that shines through pixels (picture elements). Each pixel is made up of three chambers red, green and blue. The chambers in each pixel must be opened enough and in the proper proportion to produce the correct brightness and color.
- For an LCD to provide a screen resolution 1024 x 768 pixels (SVGA), it must have 786,432 (1024 x 768) pixels. In TFT (Thin Film Transistor) type LCDs, each pixel is controlled by a tiny transistor that opens and closes the chambers in each pixel.
- Desk top LCD displays are powered by standard 120Vac wall power.
- Data is transferred to the display on a cable with a 15-pin connector that plugs into a mating connector on the video card seated in an expansion slot in the PC.
- A 17" LCD monitor with 1280 x 1024 resolution and .27mm dot pitch sells for around $500.