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August 22- August 29,2004 |
The pros and cons of ultra-thin sets
The visual appeal of new Plasma and LCD televisions may not be worth the high cost
By Alessandro Cancian
Originally Published: 2004-08-08
If you're like me, during your most recent visit to Future Shop or Best Buy, you've stopped for at least a few seconds in front of one of those ultra-thin television sets. Only a few inches thick and wall-mountable, experts agree these products have enormous splurge appeal. One thing is for sure: Plasma and LCD models, which each have different advantages and disadvantages, cost a pretty penny. Plasma screens are brighter, have greater contrast, and in most cases allow greater visual angles than LCD.
Despite being competing technologies, Plasma and LCD target two different markets. While Plasma monitors can reach 63", generally LCD monitors stay under 30". From the standpoint of image quality, Plasma is superior to LCD. Better performance is due to the presence of light-generating pixels directly on the screen surface.
A plasma TV is sometimes called an "emissive" display - the panel is actually self-lighting. The display consists of two transparent glass panels with a thin layer of pixels sandwiched in between. Each pixel is composed of three gas-filled cells or sub-pixels (one each for red, green and blue - the primary colours). A grid of tiny electrodes applies an electric current to the individual cells, causing the gas (a mix of neon and xenon) in the cells to ionize. This ionized gas (plasma) emits high-frequency UV rays, which stimulate the cells' phosphors, causing them to glow the desired colour. A kind of evolved neon light bulb. Plasma TVs are sold as either enhanced definition or HD. Enhanced definition (EDTV) panels are cheaper, and although they can display HDTV programming, they do so at scaled-down resolution.
LCD screens, on the other hand, generate images by filtering white light emitted by a lamp. Imagine having a variable-shape blue filter, allowing light to get through where blue is required in the image and blocking light where no blue is required. Imagine having as many of these filters as the colours in the image, stack all these filters, et voila. There are three filters: red, green and blue. By composing these three colours, all others can be obtained.
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