A new type of pixel technology invented by researchers at Microsoft Corporation (Redmond, WA) and the University of Washington (Seattle, WA) for transmissive flat-panel displays increases the backlight transmission efficiency by a factor of 3 to 10 over ordinary liquid-crystal-display (LCD) pixels.1 The new pixels experimentally transmit 36% of the backlight, with 56% possible after further optimization; ordinary LCD pixels transmit a mere 5% to 10%. The Microsoft pixels' rise and fall times are fast enough to allow a color display to operate with sequential red-green-blue LEDs for illumination, thus requiring no filters of any sort.
The pixels each contain a tiny telescope. In operation, backlight enters each pixel through a rear glass plate with a central mirrored spot (the glass plate is shared by all the pixels), then bounces off a deformable annular membrane primary mirror (the deformable mirror is mounted to a front glass plate, also shared by all the pixels). When the primary is flat, light bounces toward the backlight ("off" state); when the primary is electrically deformed, light bounces from it and off the mirrored spot toward the viewer ("on" state).
I have to admit that when I first saw the design (a telescope for each pixel?), I was imagining it would be overly complex. But when I looked at it in more detail, I saw that it was actually simple in construction, and appears to be a mass-producible design with no exotic materials required.
Along with the high backlight transmission, the pixel design has two other advantages. First, the rise and fall times are quite fast--about 0.63 ms each in the first prototype. Second, the electronics for each pixel can be entirely hidden behind the primary mirrors; this is in contrast to ordinary transmissive-pixel designs, in which the electronics inevitably block some light.
In the next couple of years, or more precisely when organic LED (OLED) technology becomes well-enough developed and low enough in cost to have an effect on the commercial market, displays for computers, TVs, and mobile devices will simply look better and brighter than their existing LCD counterparts. While OLED displays could be stiff competition if Microsoft decided to commercially pursue its new pixel technology, a new entry in the race for the best and brightest (and fastest, least expensive, and most efficient) can only help matters.
REFERENCE
1. Anna L. Pyayt, et al., Nature Photonics, advance online publication, doi: 10.1038/nphoton.2008.133.
John Wallace | Senior Technical Editor (1998-2022)
John Wallace was with Laser Focus World for nearly 25 years, retiring in late June 2022. He obtained a bachelor's degree in mechanical engineering and physics at Rutgers University and a master's in optical engineering at the University of Rochester. Before becoming an editor, John worked as an engineer at RCA, Exxon, Eastman Kodak, and GCA Corporation.