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DLP chip
A digital micromirror device, or DMD, is an optical semiconductor that is the core of DLP projection technology,[1] and was invented by Dr. Larry Hornbeck and Dr. William E. "Ed" Nelson of Texas Instruments (TI) in 1987.
The DMD project began as the Deformable Mirror Device in 1977, using
micromechanical, analog light modulators. The first analog DMD product
was the TI DMD2000 airline ticket printer that used a DMD instead of a
laser scanner.
A DMD chip has on its surface several hundred thousand microscopic mirrors arranged in a rectangular array which correspond to the pixels
in the image to be displayed. The mirrors can be individually rotated
±10-12°, to an on or off state. In the on state, light from the
projector bulb is reflected into the lens making the pixel appear bright
on the screen. In the off state, the light is directed elsewhere
(usually onto a heatsink), making the pixel appear dark.
To produce greyscales, the mirror is toggled on and off very quickly, and the ratio of on time to off time determines the shade produced (binary pulse-width modulation). Contemporary DMD chips can produce up to 1024 shades of gray (10 bits). See Digital Light Processing for discussion of how color images are produced in DMD-based systems.


Diagram of a Digital micromirror showing the mirror mounted on the
suspended yoke with the torsion spring running bottom left to top right
(light grey), with the electrostatic pads of the memory cells below
(top left and bottom right)
The mirrors themselves are made out of aluminum
and are around 16 micrometres across. Each one is mounted on a yoke
which in turn is connected to two support posts by compliant torsion hinges. In this type of hinge, the axle is fixed at both ends and literally twists in the middle. Because of the small scale, hinge fatigue is not a problem [2] and tests have shown that even 1 trillion (1012)
operations do not cause noticeable damage. Tests have also shown that
the hinges cannot be damaged by normal shock and vibration, since it is
absorbed by the DMD superstructure.
Two pairs of electrodes control the position of the mirror by electrostatic
attraction. Each pair has one electrode on each side of the hinge,
with one of the pairs positioned to act on the yoke and the other
acting directly on the mirror. The majority of the time, equal bias
charges are applied to both sides simultaneously. Instead of flipping
to a central position as one might expect, this actually holds the
mirror in its current position. This is because attraction force on the
side the mirror is already tilted towards is greater, since that side
is closer to the electrodes.
To move the mirrors, the required state is first loaded into an SRAM
cell located beneath each pixel, which is also connected to the
electrodes. Once all the SRAM cells have been loaded, the bias voltage
is removed, allowing the charges from the SRAM cell to prevail, moving
the mirror. When the bias is restored, the mirror is once again held in
position, and the next required movement can be loaded into the memory
cell.
The bias system is used because it reduces the voltage levels required
to address the pixels such that they can be driven directly from the
SRAM cell, and also because the bias voltage can be removed at the same
time for the whole chip, so every mirror moves at the same instant.
The advantages of the latter are more accurate timing and a more cinematic moving image.


Cara memperbaiki infocus bintik - bintik putih atau bercak | service lcd projector | Tempat service lcd Infocus proyektor dan jual lampu infocus

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