Trio of LEDs illuminates Microvision microdisplay

Cree, Inc.rodisplay using three light-emitting diodes (LEDs) can generated a full-color video image that may one day find use in headsets for the wireless Internet. Developed by Microvision, the prototype uses edge-emitting LEDs fabricated by <%=company%> (Durham, NC) as part of the multiyear agreement between the two companies (see Cree Invests $12.5 Million in Microvision Stock; Microvision Puts $10 Million into Cree for Laser and LED Development). The tiny, low-power diode lamps are affixed to three sides of a miniature optical cube, modulated at very high speeds, and scanned by miniature vibrating mirrors through a compact lens, to "write" the image on the viewer's retina. The viewer has the impression of seeing a full-size computer or television screen at arm's length from the very compact package.

"The imagery of our display exhibits none of the field-sequential 'color break-up' or defective pixel effects that haunt miniature display panels made from liquid crystal and liquid crystal on silicon," said Steve Willey, Microvision executive vice president. "The pixels in a retinal scanning display are non-rectangular, which contributes to a noticeable improvement in images containing curved or angular lines. We're also seeing a complete lack of motion blur, and a unique sort of 'freshness' or three-dimensional quality, that is not evident on other displays. We believe that this is the result of the instantaneous exposure of the retina to color pixels that have absolutely none of the persistent afterglow, or 'tail' artifacts, that cause pixels on CRTs or flat panel displays to smear moving images."

According to company president and CEO Rick Rutkowski, the forgiving alignment tolerances of the LEDs should simplify volume manufacturing. "We are also making excellent progress on combining the LED module with our proprietary microminiature (MEMs) scanners made from silicon," he added

By 2004, more end-users will access the Internet via handheld mobile terminals than wireline connections, according to the market analysis firm ARC Group (Cranlee, UK). Of the projected 1 billion Internet subscribers, 750 million will use mobile terminals. Retinal scanning displays offer a solution to the limited size of conventional wireless handset displays. The mobile terminals envisioned by Microvision can be configured as handheld devices that will scan the beam through a small lens to be positioned around 3 to 4 in. from the eye, or as a lightweight display that could be worn like eyeglasses and connected to a wireless device.

Edited by Kristin Lewotsky