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DLP / DMD Technology & Texas Instrument. Jessica Lau. Background - DMD. Digital Mircomirror Device (DMD) Invented by Larry Hornbeck of Texas Instrument Semi-conductor light switch Rectangular array of up to 1.3 million of hinge-mounted movable microscopic mirrors
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DLP / DMD Technology& Texas Instrument Jessica Lau
Background - DMD • Digital Mircomirror Device (DMD) • Invented by Larry Hornbeck of Texas Instrument • Semi-conductor light switch • Rectangular array of up to 1.3 million of hinge-mounted movable microscopic mirrors • Size of a fifth of human hair • Each mirror correspond to one pixel of image • Mounted over a CMOS SRAM
DMD • Not operating – parked at 0 degree • On – Tilt +10 degrees • Off – Tilt –10 degrees • On/Off Switching – 1000 times/sec • 848 x 600 DMD • Consists of 508,800 tiny, tiltable mirrors • A glass window seals and protects the mirrors.
Background - DLP • DLP – Digital Light Processing • Proprietary Display Technology developed by Texas Instrument • Imaging system employ the use of one or two or three DMDs • Consisted of a light source, color filter system, cooling system, illumination and projection optics, memory and signal processing support.
How DLP works ? • DMD chip • DLP I – Gray Scale Image • DLP II – Digital Color Creation • Applications and Configurations
Step 1 – Signal Conversion • Accepts both analog or digital signal • All signals must be converted into digital • Each pixel mapped directly to its own mirror at 1:1 ratio • By electrically addressing the memory cell below each mirror with the digital signal, enables mirrors to tilt towards “On” or away from “Off” light source.
Step 2 – Gray Scale Image • “On” – light Pixel vs. “Off” – Dark Pixel • Mirror switched on more frequently than off – Reflects Light Gray Pixel • Mirror switched off more than on – Reflects Dark Gray Pixel • Rapid Switching allows up to 1024 shades of gray reflections • Digitalized video signal entering DMD get converted into highly detailed grayscale image
Step 3 – Color Creation • Color is added as white light from the lamp passes through a color wheel filter • Color Wheel – RED, GREEN & BLUE • As wheel spin, mirrors on DMD are tilted on for the exact amount of time required for each basic color • Only 1 color is shined onto DMD at a time • When spinning fast enough, human eyes blend alternating flashes to view “more” colors in the projected image.
Step 4 – Applications 1-chip DLP Projection System • 16.7 millions of colors • TV, projector, home theater system 3-chip DLP Projection System • 35 trillion of colors • 3 DMD configuration • Each DMD dedicated to 1 color only • White light passes through a prism to divide red, green and blue and later recombine to form image
Advantages • Smaller package size • Light in weight • Higher Contrast Ratio ( by increasing the tilt of mirror to12 degrees, and featuring a black substrate under mirrors) • Reduced Pixelation (less visible pixel grid compared to LCD)
Disadvantages THE RAINBOW EFFECT • “ ” (Use of spinning color wheel to modulate image causes color to separate out in distinct red, green and blue in any given instant of time) • Varies for different people • Break out and rapid sequencing of color blamed for headaches and eyestrain • 1st generation – 60Hz, 3600RPM, 1x • 2nd generation – 120Hz, 7200RPM, 2x • Today – 120Hz, 7200RPM, 4x (6 segments of color wheel, double refresh rate)
