Digital Light Processing (DLP) Television & Projection

Technology Overview & Description
DLP™ technology is based on an optical semiconductor called a Digital Micromirror Device, or DMD chip which was invented in 1987 by Texas Instruments. The DMD is basically an extremely precise light switch that enables light to be modulated digitally via millions of microscopic mirrors arranged in a rectangular array. Each mirror is spaced less than 1 micron apart.

These mirrors are literally capable of switching on and off thousands of times per second and are used to direct light towards, and away from, a dedicated pixel space. The duration of the on/off timing determines the level of gray seen in the pixel. Current DMD chips can produce up to 1024 shades of gray.

By integrating this grayscale capability with a 6 panel color wheel (2x RGB), the DLP system is able to produce more than 16 million colors. A DMD system can be made up of a single chip or 3 chips, resulting in even greater color reproduction. For example, DLP Cinema systems can reproduce over 35 trillion colors.

What’s Next
Advances are being made in the single DMD design. For example, Texas Instruments’ new HD2+ design incorporates an additional color (dark green) into the color wheel, allowing for contrast ratios greater than 3000:1 for much improved color reproduction and contrast. Apparently xHD3 technology is due out in late 2004 which will take the single chip technology to even greater heights by adding a new rear coating to the mirrors and eliminating more of the latent brightness when in the “off” position. Another upcoming technology is called Sequential Color Recapture (SCR) whereby DLP systems will replace the traditional color wheel with essentially, a “Spiral of Archimedes” RGB color pattern. This new technology has been mathematically projected to rival the current quality of 3-modulator DLP Cinema systems.

Adding more pixels to DMD-based systems may prove to be challenging as this requires larger and more costly microdisplays. Currently, shrinking the size of each mirror/pixel makes the DMDs impossible to mass-produce at reasonable cost. Right now, DLP is the front-runner in the technology war and, except for he price-front, is pretty much cleaning the clock of the likes of CRT and LCD rear projection.

DLP Advantages	DLP Disadvantages
Incredible color reproduction Excellent contrast ratios (using HD2+) Lightweight Excellent lamp life Fully digital displays supporting DVI/HDMI without analogue conversion	Requires a minimum of 12-14” depth for lamp-based technology Older models (pre-HD2) may not perform as well as upper scale CRT projection systems Potential for "Rainbow Effect" in older and single chip systems.
What is the Rainbow Effect? The DLP 'rainbow effect' is an artifact unique to single-chip DLP projectors. The artifact appears as a rainbow or multi-color shimmer briefly noticeable when changing focus from one part of the projector screen to another. It appears as a secondary image that appears at the viewer's peripheral vision and is generally noticeable when shifting focus from a high contrast area or 3-chip DLP projectors, higher wheel speeds, 7-segment color wheels, and archimedes color wheel designs (pending) are minimizing or may altogether elminate the effect.

Which Display is Best?