Screen Technology puts the focus on seamless tiling

20 Nov 2002

UK display developer Screen Technology is to put all its efforts into seamless tiling for standard flat panels. Phillip Hill looks at the company's chances of success.

From Displays Europe magazine

Screen Technology Ltd (STL) of Cambridge, UK, had been working quietly since the mid-1990s on an unusual photoluminescent LCD (PLLCD) technology with an ultraviolet backlight. Now, that is all on hold while the company concentrates on "ITrans" - a seamless tiling technology to produce large-screen displays, initially using LCDs.

Seamless tiling

Seamless tiling had always been envisioned as part of the PLLCD concept, so that devices could be scaled up to target the 40-60 inch and above screen-size markets.

Said Tony Kellett, STL's CEO: "Tony Lowe [STL's CTO] came up with ITrans while we were developing PLLCD. We realized that ITrans works perfectly well with visible light and costs are much lower. PLLCD would have been too expensive for volume markets, although there are niche markets for it, and we would have been stretched to do both."

High-profile investment

ITrans has just received some high-profile recognition with the news in July that the LCD pioneer and holder of major LCD patents, QinetiQ, had taken a 6% equity stake in STL.

Graham Brown, QinetiQ's director of new ventures, said: "With QinetiQ's expertise in LCDs and current work on advanced flat panels, STL represents a good partner. The FPD market is currently worth $30 bn (EURO 30 bn), and STL's new ITrans technology has great potential."

STL was funded by private investment from Thomas Swan & Co until October 2000, when additional venture capital funding was obtained from MTI Partners and TTP Ventures. According to Kellet, Thomas Swan still holds 47%, with MTI holding 24% and TPP holding 12%. STL is looking for a further £4 m (EURO 6.4 m) this autumn to take the next step: volume production.

In October, executives had just completed a round tour of the Far East talking to volume manufacturers - "all the household names", according to Kellett.

ITrans uses standard LCD panels, but the technology can also work with a variety of current and emerging displays including organic LEDs, the company claims. The display consists of a white backlight, standard display panels and the ITrans modules that use non-imaging optics to expand the image of an unlimited number of small displays to produce seamless tiling. In this way it differs from a technology just announced by Seamless Display (a spin-off of Oxford University, UK), which is also hoping to target the large video-wall market. Here, a thin lens at the edge of the display spreads light over the inactive borders surrounding the individual screens, leaving just a shadow.

Seamless tiling had been all but abandoned as too difficult, but interest was regenerated when Rainbow Displays of New York, US, showed a 37.5 inch tiled LCD at a show in Korea in 2000. Said Kellett: "Rainbow Displays effectively only go up to two in height by n across. Ours is n by n unlimited. We have now developed a 52 inch 4 x 3 tiled demonstrator. This scale-up equates to a 16:9 aspect ratio HDTV. Also, they do not use off-the-shelf panels as we do."

On the Seamless Display technology, Kellett commented: "I understand that it operates by compressing and spreading the image between the joins. There will be distortion issues and luminance will drop off at the edges. It is not suitable for TV."

STL has already produced a 1 x 2 demonstrator. This gives 1000 cd/m², using approximately 100 LEDs as the backlight and 12.1 inch LCD modules. The ITrans module magnifies the image onto a 14 inch output face to give a seamless overlap between the individual screens. Kellett says the luminous efficiency will be increased to 3 lm/W. "For the demo, we focused on developing the optics to demonstrate the viability," he said.

Kellett believes that ITrans will rival PDPs because STL's volume costs are much lower, and he does not think that PDP costs can be reduced and power efficiency increased to the levels required by the consumer market. If he is right, ITrans could be the UK's biggest success in the LCD field since its invention more than 20 years ago.