Flixel, Ltd. (Tel Aviv, Israel) (www.flixel.com) is a start-up company with a new MEMS-based display approach. Instead of mirrors that swivel from side to side (the DLP approach), Flixel builds pixels that flip 90 or 180 degrees to block or pass light through an aperture. As a result, the display can be used in one- or three-panel transmissive projection systems. And, unpolarized light can be used.

The "flipping pixel" concept has applications beyond projection microdisplays, however. The technology can also be applied to headsets, optical sensors, lab-on-chip/DNA analysis, spatial light modulation and more. For example, one application is the reduction of blooming in night vision systems. However, the development stage company will focus first on the projection industry and is looking for partners to help commercialize the technology.

The Flixel Shutter Array (FSA) contains a matrix of flipping pixels that can be individually addressed. Grey levels are achieved by a pulse width modulation technique whereby each pixel shutter is opened a pre-defined part of the frame time. The free-moving pixels flip 180° or 90° on their own dedicated free-moving hinges without exertion of any mechanical stress (torsion) on the hinges. The company says it has driven the pixels to over one billion flips without degradation.

A key part of the IP is the fact that the FSA is not based upon a torsion hinge, as a torsion structure would ultimately fail in a 90- or 180-degree movement. Instead, CEO Jephtah Lorch says each pixel is basically mounted on a rolling pin along one edge. When commanded to flip, the shutter flips and rolls so no there is no torsion, therefore, no wear mechanism. Other advantages of the approach include fast response time (< 1ms), wide filed of view, low energy consumption, high fill factor (up to 90%), bistable operation, wide temperature range, high contrast and high collection efficiency.

So far, the company has shown a proof of concept demonstrator that was initially aimed at direct-view applications. It features a 400 x 250 pixel array with 85-micron pixel pitch (flipper size is 40 x 85), but this can be reduced to 20 microns, says the company, to support its new focus on projection applications. This display features 180-degree flips, but in order to get high aperture ratios, the flipping pixels will need to stop at 90 degrees. "Stopping at the 90-degree point can be mostly controlled through electric fields applied to the electrodes. A mechanical stop is added as an additional precaution," says Lorch. "Or, we can use a micro lens array to significant increase the light capture." The company has demonstrated the 90-degree flip in single elements, but not yet in a full array.

Flixel was founded in 1998 by Ami Heines and Mair Laiser. It now has four employees and has been doing device R&D in an older-generation (1-micron design rule) silicon foundry that is geared for mass production. There are six patents in various stages of processing, but Flixel believes it is the only company working in the non-torsion actuator filed at this time.

Currently, devices are fabricated using an 8-12 mask process that deposits the control and MEMS layers on transparent quartz substrates. Operation is based upon a 15V supply, but flipping speed can be increased with higher voltages. A capacitor must be energized to change positions, so the only energy used is during transition.
The company closed a round of funding in April 2003 and is seeking additional partners in the areas of package and test, as well as more funds. Next up will be development of a display with a 20 x 20 micron pitch. An XGA resolution device can be realized in a 1-inch form factor.

Much remains to be done to commercialize the technology, but the concept is intriguing and worth a further look.

Flixel, Jephtah Lorch, [972] 3-562-9505, jephtah@flixel.com

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Insight Media, Annmarie Gabisch, 203-831-8464, Annmarie@insightmedia.info