One of the fundamental parts of a personal computer is the bit you look at, the screen. Scientists and technologists continue to chase the dream of the virtual screen through a variety of possibilities such as eye-glasses, but for the vast bulk of us the “visual display unit” or VDU continues to be the standard hardware for seeing a computer's visual output. Even here, though, developments continue.
Computer screens started out by simply copying the technology of the television. The Cathode Ray Tube or CRT is a well-known technology, consisting of a big glass enclosure with a special coating on the display side and a “gun” on the other side that fires off electrical particles to make the screen briefly flare up in tiny areas (the pixels). With small enough pixels, the basic 3 colours, and a fast enough gun, you can end up making a high-quality picture with smooth movement. But you need lots of space for the vacuum tube between the gun and the screen, it's heavey, and produces lots of heat.
Along came the Liquid Crystal Display, or LCD. Many will be familiar with LCDs from a long time back through their use in watches and phones and similar small-scale technology. Again, scientific and engineering development refined the use of LCDs to bring in colours, larger scale, and faster image management. Modern LCDs can produce great pictures without any noticeable lag or blurring when depicting movement, and of course are desirable because they are only a few centimetres thick. They are also energy efficient. LCDs cope well up to medium-sized screens such as for computers, but get expensive and unreliable above this size.
Plasma screens filled the void of very big displays that are flat – they react very quickly so are great for moving images, can be manufactured to truly enormous size. But they are expensive to manufacture and like CRTs, they use up lots of energy.
One of the most promising technologies for the future is said to bring together the benefits of each of the three technologies above – SED, or Surface-conduction Electron-emitter Display (yes, a particularly easy-to-remember acronym!) is basically miniaturisation of a TV down to a size that allows thousands of them to be stacked next to each other to make up one collective display. So you get the high-quality and very good movement capabilities of CRT along with low energy use plus the flat-screen of LCD and the watch-sized up to arena-sized scales of plasma. SED is only now appearing in demonstration units, and is not expected to be generally available for another couple of years, yet is already causing a stir thanks to its fantastic picture quality. Search online for “SED display” for more information and reviews.
All this of course simply reinforces the normal rule in technology – whatever you buy today will be superseded tomorrow by something far better and far cheaper. But if you avoid buying today, you will always be waiting for tomorrow!
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