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DLP or Digital Light
Processing is a technology used in projectors. DLP was developed by
Texas Instruments which is also currently the only producer of this
technology, Texas Instruments onsell their DLP designs to other
projector manufacturers. DLP is based on microscopically small mirrors,
laid out in an array of pixels. The number of mirrors varies depending
on desired resolution. DLP allows prjectors to be much smaller cheaper
and more efficent. Previous projector designs were either very heavy
like the large 3 tube design projectors and rear projection sets, or
they had poor quality like some of the early LCD designs that often had
a honeycomb look to the picture.
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.
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
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.
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.
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.
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 the
micromirrors reflect is then combined and passed through the projection
lens to form an image.
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