How CRT and LCD monitors work

Future technology in LCDs

What does the future hold for display technology?

Arguably, there is not much of a future at all for CRT technology. As LCDs get better and better, with faster response times, better contrast and higher resolutions, the uses for the analogue output it provides will become fewer, given the convenience of the form factor of LCD displays.

Philips and other companies have come up with technology to create flatter CRTs, which occupy less than half the space of a traditional CRT of any given specification, but even these look bulky compared to today's svelte LCD designs.

Connections: The first area that LCDs will evolve in is through different connector types. VGA and DVI are, effectively, connections that are becoming obsolete. The new standards coming in are HDMI and UDI, which we have written about previously. These standards should allow for better quality connections with more featureset, such as the ability to carry audio and video along a single cable.

LED backlighting: We've seen that LCDs are currently backlit by a number of cold cathodes above and below the screen. New technology replaces these heat-producing, power-intensive cathodes with cooler, more efficient LEDs. Laptops using LED backlighting are now starting to come into the mainstream, with the Sony TX2 sporting a 7 hour battery life thanks to the efficiency of its backlight. LCD monitors are now also beginning to approach reference CRT quality thanks to the technology - check out this review of the NEC Spectraview for more details.

Better panel types: Currently, the vast majority of monitors on the market are sold with Twisted Nematic (TN) LCD panels. This type of LCD panel usually has a great response time, but the colour range and viewing angle can often be limited.

Multi-domain Vertical Alignment (MVA) panels have fast response time, wider viewing angles and a much better contrast, resulting in a better picture overall. However, it is a more expensive technology. As costs fall, however, MVA panels could deliver better image quality to TFT monitors.

Leaping ahead

If we were to leap into the future, we would see some fairly hefty transitions in display technology.

SEDs: Surface-conduction Electron-emitter displays are being touted as a replacement for LCD panels. SEDs use a phosphor coating, like CRTs, that is charged with electrodes - only rather than from behind through a vacuum, like a CRT, the electrodes are within the matrix of pixels, like with a LCD. They are said to produce better images than LCD with a cost that will eventually be lower. Prototypes have already been shown off by companies like Toshiba and displays are expected to be available on the market in 2007. However, some remain sceptical about the technology and manufacturing problems and costs that are yet to be overcome.

Curved displays: At the Consumer Electronics Show in Las Vegas this year, Bill Gates showed off a number of concept displays that he believed would be on the market within the next 10 years. Perhaps the most awesome of these was a field-of-view curved display. Around the size of two 24" panels 'sewn' together, the curved display sat on the desktop and allowed for things on the monitor to be seen in the peripheral vision outside of our 90 degree standard view. Imagine gaming on one of those! Since the display is curved, we have to image it was an OLED display, which can be produced in that way.


Table displays: Bill also showed off a concept display built into a coffee table, where the surface of the table becomes the screen when a device, like a PDA, is placed on top of it. This could bring a 'big-screen' interface to PDAs and Gates suggested that they'd be used at airports and other places where keyboard-mouse-monitor access was limited.

OLED: Short for Organic Light Emitting Diode, OLED could well replace LED as the display of choice over coming years. OLED has similarities to SED technology, in that the lighting material is an organic substrate. When current is applied, it glows. However, rather than the material being on the panel, it is within the LED itself, meaning that LEDs can be coloured as required to emit the correct light - with no RGB sub-pixels needed. Because the electricity can operate directly on the substrate, you don't need to have a backlight - this saves on power and space.

OLED is already starting to make its way into the market, such as with this BenQ phone.