We Know: All About the Types of Computer Screens
What are the different types of computer screens?
The two major types of computer screens on the market today are the cathode ray tube (CRT)
and the liquid crystal display (LCD).
What is a CRT screen?
CRTs are what we commonly know as the traditional computer screen. CRTs use the same technologies
as old television sets. Electron beams of phosphor dots are fired in a glass tube to form images on
the screen. Although they are large, CRTs offer decent performance at inexpensive prices. In recent years,
compact flatscreen CRT displays have replaced the older and clunkier curved screen CRT displays.
What is a LCD screen?
Newer models of computer screens use LCD technology. The images on the LCD screens are created
when liquid crystal molecules bend in response to electric signals activated by light.
LCD screens are commonly found on notebook computers and personal digital assistants (PDAs).
They are also known as flat panel display monitors.
There are two types of LCD screens:
- Active matrix displays, or thin film transistor (TFT) displays have
higher resolutions and refresh more frequently. There are
three types of active matrix displays:
- Vertical alignment (VA)
- Twisted nematic (TN)
- In-plane switching (IPS)
- Passive matrix displays are small monochromatic screens that are found in older
notebook computers. Passive matrix displays have slower refresh rates and poorer
contrasts than active matrix displays. There are two distinct types:
- Supertwist nematic (STN)
- Double-layer STN
Which display type is better?
The advantages of CRT displays include:
- CRT displays are inexpensive.
- CRT displays have bright images and clear motion video.
- Images are sharp and there is minimal glare.
The disadvantages of using a CRT display are:
- CRT displays are large and space-intensive.
- CRT displays consume more electricity.
- CRT displays emit more electromagnetic radiation.
The advantages of using a LCD display include:
- LCDs are lightweight and use less space.
- LCDs use less electricity and emit less electromagnetic radiation.
- LCDs have wider screens for higher resolutions and higher definition.
- Some LCDs are flexible, meaning the screen can be rotated to portrait or landscape orientations.
The disadvantages of using a LCD display are:
- Expensive.
- At smaller resolutions, pictures can appear jagged.
- LCD displays are hard to view with sunlight and are difficult to view from side to side.
LCDs appeal to those who desire high definition graphics (such as computer gamers) and who like
lots of desk space. CRTs still maintain a loyal fan following because of its ease of use and
quality for relatively cheap prices.
What are some features to look for when shopping for a new computer display?
Computer screens come in different sizes, shapes, and prices. Shoppers should look for computer
displays that have:
- Viewing area: viewing areas are measured diagonally and are two inches
less than the advertised screen size. Make sure you select one with a 17 inch viewing surface.
- Dot pitch: the closer the dots are to one another, the sharper the picture quality. Look
for dot pitch sizes of at least .26 millimeters.
- Brightness is measured in candelas (cd) per millimeter squared (m2). For LCDs, look
for brightness qualities of at least 250 cd/m2.
- Refresh rates on CRTs of at least 72 MHz are recommended.
- Contrast rations on LCDs: the higher the contrast, the better the picture. The ideal contrast
ratio is 400:1.
- Energy conservation: monitors that are environmentally friendly are branded with the Energy
Star symbol. These monitors use less electricity and emit less radiation.
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