Invention signals TV that hangs flat on wall: British-developed display screen attracts world's electronics giants

THE world-wide replacement of familiar and bulky television sets with slim wall- mounted screens has come a step closer with the invention of a Hampshire scientist.

William Johnson has attracted the attention of the world's electronics giants with a display screen whose unusual optical qualities produce a crystal-clear image to rival any the industry has developed. He believes his system could make feasible mass-produced, high- quality projection systems that would replace television sets with a large wall-mounted screen and a small, unobtrusive projection unit.

Two weeks ago he signed a deal with Nashua, the American photographic company which owns TruPrint in the UK, to manufacture and market the screens. Durand, a small Guernsey-based company, is to continue research on the techniques involved, in collaboration with Nashua.

Large, high-quality display screens are much sought-after electronics applications - not only to carry large, crystal- clear television and video images, but also for vast public information displays at airports or train terminals.

Recently, Mr Johnson has demonstrated the system to a 'major US car manufacturer' interested in using it to create head-up displays that project driver information onto the windscreen. He has also teamed up with a Japanese company, Innovation Partners International, which trawls Europe and America for innovative ideas. It has set up tests at more than 30 Japanese companies, 25 of which Mr Johnson claims are now negotiating licensing contracts.

The Microsharp screen is the result of more than nine years' research in conjunction with Loughborough University. It is based on an optical technique Mr Johnson developed for a head-up display called the Gogglevox. This miniature display, worn like a pair of goggles, is made up of tiny patches of coloured light, or 'pixels', as in an ordinary television screen.

Traditionally, the electronics industry has tried to create tiny, sharp pictures by using more and more pixels of decreasing size to make up an image. This approach is limited because, eventually, the connecting 'wires' that control the patches take up a significant proportion of the screen and produce dark patches, or 'visual noise', on the image.

Mr Johnson uses optics to solve this, placing a polymer layer in front of the pixels. This 'blurs' the edges between the coloured and dark patches so that the brain no longer distinguishes them. The polymer is unusual in that its surface behaves like a mesh of tiny lenses, whose refractive index - or ability to bend light - changes with exposure to light. Mr Johnson's product alters this Graded Refractive Index, or 'Grin', so that it varies randomly across the polymer layer, blurring the pixel edges by just the right amount.

In his projection system the image created in this way is shone onto a display screen made from the same polymer. Again, he varies the refractive index across the screen's surface, but in a more controlled, fixed way. 'Around Christmas we had a breakthrough and came up with this extraordinary reflection screen, which also performs well in a back- projection system,' he said.

He ascribes his success to British inventiveness. 'I think we are still the most inventive country in the world, and that we look at things in a different way. When I first began this work nine years ago, people thought I was completely off my rocker. This had always been seen as an electronics problem . . . nobody said 'What about optics?' '

Nicholas Phillips, head of the team at Loughborough University that has developed the screen, said Mr Johnson had tried to involve British companies. 'They showed an interest, but when you get to board level this is a deadly country in which to get the initial money you need for tooling up,' he said. In this case the cost of clean rooms (a completely dust-free environment necessary to prevent damage to electronic components) could push the figure up to pounds 5m.

Mr Johnson's tale echoes many from British inventors who find it almost impossible to nurture bright ideas into marketable products in the UK. The cost of patents, which can run to hundreds of thousands of pounds, is one hurdle. Raising finance for development costs is another.