The big screen
Summary Description We all interact with our computers using some kind of monitor. Newswire's 5 Minute Guides examines the technologies behind the different types of displays.
Author

Publication

Roullas Top10 Simon Vandore

Newswire
No


Editorial InformationArticle Location http://www.newswire.com.au/0005/5mg04.htm
Article Topic 5 Minute Guides
Story Order
Story Group 000507
Post Date 04/05/2000 08:47 AM Status Posted Entered by Simon Vandore on 02/05/2000 05:32 PM


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CRT, RGB, TV? What's the difference?
An everyday computer monitor uses a cathode ray tube (CRT) to produce images, similar to the 'picture tube' in a standard television set. CRTs use an electron 'gun' to light up phosphors against a glass tube. They can be used to produce multiple resolutions (levels of detail) and cope with various refresh rates (how many times the screen is updated per second).
Today's CRTs have three electron guns, producing red, green and blue (known as RGB) overlapping images, resulting in the colour picture we see.
CRT monitors are priced according to size, measured in inches diagonally across the screen. Often you will see a second measurement, boasting 'viewable area', which is a more accurate representation of the screen size. A 15in display will set you back just a few hundred dollars, a 17in costs a little more, a 19in will come in at about $1,000, and a 21in can cost as much as a PC.
What about those nice, flat LCD monitors?
Liquid crystal display (LCD) screens, like those used on notebook PCs or in flat-panel monitors, produce an image with many rod-shaped molecules which can bend light. They take up much less space and their output is clearer to the eye. The image is produced by blocking light rather than emitting it. LCDs are designed to operate at a single resolution -- lower resolutions simply take up less of the screen or are stretched across it. Modern active matrix LCD displays are also called TFTs, after the thin film transistor technology they use to improve image updating.
LCDs are far more expensive and are best suited to a single resolution, but smaller LCD screens are better at displaying higher resolutions. A 15in TFT will usually operate at 1,024 by 768, whereas a 15in CRT is better suited to 800 by 600. A 15in TFT will set you back as much as, or even more than, a 21in CRT.
What's this I hear about hemispheres?
Most CRT monitors are built for a particular hemisphere of the world. Differences in the Earth's magnetic field can distort the image produced by a CRT monitor if it is used in the wrong hemisphere. Monitors imported into Australia from Europe, for example, must often be adjusted to suit the Southern Hemisphere. Sometimes this can add a little to CRT monitor prices in our hemisphere.
I read something about a 'plasma' screen. What's that?
A plasma display uses gas in a tiny, flat space between glass, which reacts with phosphors to produce red, green and blue light that is manipulated into a picture. Such screens can be very large (42in is the most common size on the market), and will usually set you back between $10,000 and $20,000. Plasma screens can be used anywhere, as they are unaffected by magnetic distortion and are not much thicker than a picture frame, and for that reason they are often hung on a wall or even placed flat in the floor. Plasma screens have an incredible viewing angle -- the picture can be clearly seen through 160 degrees -- but questions remain about their life span.
How about those touchscreen gizmos?
A touchscreen monitor is simply a screen with an input device overlay. The overlay might use sensors to detect electrical disruption where contact is made, or perhaps infra-red light which is interrupted by the user's finger.
Touchscreen monitors are not suited to everyday use as they require the user to suspend their hand in mid-air for long periods, which quickly leads to fatigue. You'll find them more often on automatic teller machines and electronic information kiosks than attached to PCs.
What else is on the way?
The holy grail for display designers may be a paper-thin, very high resolution screen that can be rolled up and carried around. There are already prototypes of screens that are as easy on the eyes as paper and ink, but it may be many years before they enter commercial production.


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Bulletin Summary5 Minute Guides: The big screen
We all interact with our computers via some kind of monitor. Newswire's 5 Minute Guides examines the technologies behind the different display types.

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5 Minute Guides: The big screen

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