DLP - Digital Light Processing (Tech Article)

How DLP Technology works:

1. The Semiconductor

At the heart of every DLP™ projection system is an optical semiconductor known as the Digital Micromirror Device, or DLP™ chip, which was invented by Dr. Larry Hornbeck of Texas Instruments in 1987.

The DLP™ chip is probably the world's most sophisticated light switch. It contains a rectangular array of up to 2 million hinge-mounted microscopic mirrors; each of these micromirrors measures less than one-fifth the width of a human hair.

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.

2. Digital Light Processing 1: The Grayscale Image

A DLP chip's micromirrors 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 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.

3. Digital Light Processing 2: Adding Color

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.

4. Applications and Configurations

1-Chip DLP Projection System

Televisions, home theater systems and business projectors using DLP technology rely on a single chip configuration like the one described above.

White light passes through a color wheel filter, causing red, green and blue light to be shone in sequence on the surface of the DLP chip. The switching of the mirrors, and the proportion of time they are 'on' or 'off' is coordinated according to the color shining on them. The human visual system integrates the sequential color and sees a full-color image.

3-Chip DLP Projection System

DLP technology-enabled projectors for very high image quality or very high brightness applications such as cinema and large venue displays rely on a 3-chip configuration to produce stunning images, whether moving or still.

In a 3-chip system, the white light generated by the lamp passes through a prism that divides it into red, green and blue. Each DLP™ chip is dedicated to one of these three colors; the colored light that the micromirrors reflect is then combined and passed through the projection lens to form an image.