The Science Behind DLP Television (via CobWeb/3.1 kupl1.ittc.ku.edu)
Written by Mitchell Medford
DLP televisions are based on a technology invented by Texas Instruments back in 1987 called Digital Light Processing. The technology is based on an optical semiconductor called DMD (Digital Micromirror Device) chip. It is a highly reliable, all-digital display chip that delivers the best picture across a broad range of products, including large screen digital TVs, and projectors for business, home, professional venue and digital cinema.
The chip consists of over one million mirrors to process light. They come in either single chip or 3 chip configurations. One-chip DLP systems use a projection lamp to pass white light through a color wheel that sends red-green-blue colors to the DMD chip in a sequential order to create an image on-screen. Only one DMD chip is used to process the primary RGB colors. Three-chip DLP systems use a projection lamp to send white light through a prism, which creates separate red, green, and blue light beams. Each beam is sent to their respective red, green, and blue DMD chip to process the image for display on-screen. One-chip models are said to produce a display of over 16-million colors. Three-chip models can produce a display of over 35-trillion colors. The result is maximum fidelity: a picture whose clarity, brilliance and color must be seen to be believed.
When a DLP 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 DLP chip and the sophisticated electronics that surround it are what we call Digital Light Processing technology.
Benefits of Single chip DLP:
1. Fantastic color accuracy.
2. The best contrast ratios and shadow detail.
3. Generally very quiet.
4. Very little space between each pixel creates a very smooth image, even when using lower resolution projectors.
5. Light engine failures are very rare so repairs are less costly than other technologies.
6. Technology doesn't degrade over time. With proper routine maintenance, DLP™ projectors consistently provide just-out-of-the-box performance. (DLP™ is the only technology that makes this claim).
Benefits of Three chip DLP:
1. Good contrast; much greater than film theaters.
2. Good shadow detail.
3. Can provide high brightness compared to the limited brightness of single chip versions.
4. Overall image quality deemed as the best of any type of micro display technology.
5. Same technology as projectors installed in digital theaters.
6. Pure digital technology.
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 gray pixel; a mirror that's switched off more frequently reflects a darker gray pixel. In this way, the mirrors in a DLP projection system can reflect pixels in up to 1,024 shades of gray to convert the video or graphic signal entering the DLP chip into a highly detailed grayscale image.
The white light generated by the lamp in a DLP projection system passes through a color wheel as it travels to the surface of the DLP chip. The color wheel filters the light into red, green, and blue, from which a single-chip DLP projection system can create at least 16.7 million colors. And the 3-chip system found in DLP Cinema™ projection systems is capable of producing no fewer than 35 trillion colors. The on and off states of each micromirror are coordinated with these three basic building blocks of color. For example, a mirror responsible for projecting a purple pixel will only reflect red and blue light to the projection surface; our eyes then blend these rapidly alternating flashes to see the intended hue in a projected image.
Mitchell Medford is an author and product consultant for several consumer electronics manufacturers. Visit his website for more information on home theater, LCD TVs, and plasma televisions.
