723–0018 /02 F7024
4.2 The DMD Device
DMD Device
Image 4-3
At the heart of every DLP™ projection system is an optical semiconductor known as the Digital Micromirror
Device, or DMD chip, which was invented by Dr. Larry Hornbeck of Texas Instruments in 1987.
The DMD chip is probably the world's most sophisticated light switch. It contains a rectangular array of hinge-
mounted microscopic mirrors, each measuring less than one-fifth the width of a human hair, and
corresponding to one pixel in a projected image.
When a DMD chip is coordinated with a digital video or graphic signal, a light source, and a projection lens, its
mirrors can reflect an all-digital image onto a screen or other surface. The DMD and the sophisticated
electronics that surround it are what we call Digital Light Processing™ technology.
The F70 / 90 DMD chip is part of the Texas Instrument DLP9000 family and features over 4 million
micromirrors on each chip, offering a dazzling high resolution 2560 x 1600 (WQXGA) array.
4.3 The Grayscale image
Grayscale
Image 4-4 Image 4-5
A DMD panel's micro-mirrors are mounted on tiny hinges that enable them to tilt either toward the light source
in a DLP™ projection system (ON) or away from it (OFF)-creating a light or dark pixel on the projection
surface.
The bit-streamed image code entering the semiconductor directs each mirror to switch on and off up to several
thousand times per second. When a mirror is switched on more frequently than off, it reflects a light grey pixel;
a mirror that's switched off more frequently reflects a darker grey pixel.
In this way, the mirrors in a DLP™ projection system can reflect pixels in up to 1,024 shades of grey to convert
the video or graphic signal entering the DMD into a highly detailed grayscale image.
DLP System General Description
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