CES 2008: The Power of Reflection

A brighter yet power-sipping display draws inspiration from butterfly wings

Unlike today’s LCD screens, with their battery-sucking backlights, new displays from Qualcomm illuminate themselves simply by reflecting ambient light. As your surroundings get brighter, so do the screens, making them easier to read, even in the strong sunlight that renders typical LCDs worthless. The power savings come from a new technology called IMOD (interferometric modulation display) that mimics the light-reflecting properties of butterfly wings. Like the insect, the screen relies on layered membranes that absorb white light and reflect back color to create crisp, bright images.

IMOD debuted last November in a two-tone screen on the Acoustic Research ARWH1 Bluetooth headset and will appear in cellphones within the year. Full-color displays should fly along in the next few years.


How it Works

As light rays strike the IMOD screen, they bounce off thousands of tiny double-layered squares. Some of the light reflects off the top layer [A] , while the rest penetrates deeper [B] , reflects off the bottom layer, and passes through the top layer. The distance between the two layers determines whether the square appears red, green or blue. If the length of the gap matches, say, the wavelength of blue light, blue waves reflect off the bottom layer and sync with blue waves reflected off the top ** [C]** . The result: The square appears blue. Waves of other colors, such as red, combine out of sync and cancel each other out [D] .

To turn a pixel off [E], an electrical charge pulls the two layers together, tightening the gap so that it matches the wavelength of invisible ultraviolet light.

By turning individual red, green and blue squares on or off, the screen creates full-color images.

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