Basics of LCD

Digital Light Processor

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 up to 1.3 million hinge-mounted microscopic mirrors; each of these micromirrors measures less than one-fifth the width of a human hair, and corresponds 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.

Grayscale
A DMD panel'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 DMD into a highly detailed grayscale image.

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 DMD panel. 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-DMD 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.

Scrolling color has been a major goal for the projection industry because it enables the most efficient use of light in a single panel display. True to this promise, Sequential Color Recapture (SCR) is an innovation in scrolling color that produces a 40 percent boost in lumen output compared to traditional field sequential color systems.

While current implementations of scrolling color require splitting a light source into primary colors and manipulating that light on a modulator, SCR achieves the same result with no moving components other than a color wheel-achieving the efficiency of three-modulator systems with only one modulator

Single-Chip
Televisions, home theater systems and business projectors using DLP technology rely on a single DMD 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 DMD. 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.

Samsung Electronics

Three-Chip
DLP technology-enabled projectors for very high image quality or high brightness applications such as cinema and large venue displays rely on a 3-DMD-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 DMD chip is dedicated to one of these three colors; the colored light that each micromirror reflects is then combined and passed through the projection lens to form a single pixel in the image.

NEC Visual Systems