Flat screens exploit electron emission technology

Canon and Toshiba have formed a joint venture to make SED -- a display technology based on electron emission -- a commercial success

Canon and Toshiba have formed a joint venture to develop, produce and sell surface-conduction electron-emitter display (SED) flat screens

SED is a technology that holds the promise of very high picture quality while using less power than alternative displays such as plasma screens.

Like a cathode-ray tube (CRT) TV or monitor, SED creates an image by colliding electrons with a fluorescent-coated glass plate. But rather than using one gun that fires electrons in a single stream, SED uses a second glass plate mounted with electron emitters -- several for each pixel.

The two plates are positioned just a few nanometres apart, with a vacuum between them. When a small voltage is applied across this gap, electrons are released from the emitters. They drift across the vacuum and collide with the fluorescent-coated glass plate, causing light to be given off.

Canon and Toshiba are already the front-runners in SED development, and have been working together on SED since 1999. They claim that SED will deliver "exceptional overal image quality", including high contrast, brightness, definition and gradation levels.

Their joint venture will be called SED Inc. and will employ around 300 staff. It will aim to get SED into mass-production in 2005. Its first application will probably be for large-screen flat-panel television.

SED could also be used for computer monitors. It's likely that it will appear in presentation monitors -- such as those used to display information at airports -- before it reaches the desktop market, because early commercial SED screens probably won't provide a high-enough resolution for PC use.