toshiyoshi - projection based displays

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Hiroshi Toshiyoshi [email protected]

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Optical MEMS

III. MEMS Projection Displays

Micro Mirror Projection

- Texas Instruments DMD

- Daewoo Elec. AMA

Grating Light Valve

- Silicon Light Machines

Image Projection

Color Synthesis

Pixel Addressing

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History of Micromechanical Projection Display (1)

Westinghouse Mirror-Matrix Device

Surface micromachined

Built on SOS (Sapphire)

Addressed by electron beam

Deflect up to 4

Contrast ratio: 10 to 1

Difficul ty in HNA release etch

Limited resolution in electron

beam

R. N. Thomas, "The mirror matrix tube: A novel light valve for projection display,"IEEE T-ED, 22, 765 (1975)

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IBM Cantilever Light Modulator Array

K. E. Petersen, "Micromechanical Light Modulator Array Fabricated on Silicon,"

Appl. Phys. Lett. vol. 31, 521 (1977).

~ +/- 1 deg.

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Texas Instruments, Deformable Mirror Device (DMD)

L. J. Hornbeck, "128 x 128 Deformable Mirror Device," IEEE Trans.

ED (1983).

128 x 128 Deformable Mirrors

Mirror Size 51 m x 51 m

DRAM like operation (hold & refresh)

response 25 s

hold 200 ms

Addressed by embedded MOS

Transistors

Air gap 620 nmMirror fill factor 32 %

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L. J. Hornbeck,"Deformable Mirror Spatial Light Modulator, " Proc. SPIE vol. 1150(1989)

Prototypes of TI DMD

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MEMS Projection Display (1)

Digital Micromirror Device

Texas Instruments

[1] Graphic Images -->http://www.ti.com/dlp/resources/library/[2] Up-to-date --> P. F. Van Kessel, L.J. Hornbeck, R. E. Meier,M. R. Douglass, "AMEMS-based projection display," Proc. IEEE, vol.86, 1687-704 (1998)http://ielimg.ihs.com/iel4/5/15216/00704274.pdf[3] Up-to-date --> L. J. Hornbeck, "Digital Light Processing for High Brightness, High

Resolution Applications," Proc. SPIE vol. 3013 (Electronic Imaging EI'97, Feb. 10-12,1997, San Jose, CA).[4] MEMS & DMD ---> Gregory A. Magel, "Micromachining in Optics," http://www.ti.com/dlp/resources/whitepapers/pdf/micro.pdf[5] History overview ---> L. J. Hornbeck,"From cathode rays to digital micromirrors: Ahistory of electronic projection display technology ,"http://www.ti.com/dlp/resources/whitepapers/pdf/titj03.pdf

References

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Good Example of "Quantity Changes Quality"

Texas InstrumentsDigital Mirror Device (DMD) for Digital Light Processing (DLP)

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Principle of Image Projection

Electrostatic On-Off Control of Mirror Array

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Advantage of MEMS Projection Display

LCD Image DLP Image

Compared with Liquid Crystal Display

+ High Contrast and High Brightness due to Fill Factor ~ 1

+ Controlled both in digital mode (PWM) and analog mode (SLM)

+ Small size

+ New market for Portable Projector and Large Screen TV Monitors

PWM: Pulse Width Modulation

SLM: Spatial Light Modulation

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Structure of DMD

Aluminum Mirror on Addressing CMOS SRAM

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Fabrication Process of DMD

Al mirror ---- CMOS Process compatible

Photoresist sacrificial layer --- removed by plasma etching

DMD on CMOS SRAM by 6 mask process

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Electrostatic Operation

GND

Driving Electrodes

Landing Electrode

Angle Angle Angle

Angle Angle

Electrostatic Torque

Mechanical Restoring Torque

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Resonant Frequency ~ 50 kHz

Step Response ~ 12 s

Temporal Response to Step Voltage

Mechanical Characteristics of DMD

CMOS 5 V Drive

450 Billion Contacts

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SVGA XGA SXGA

848 x 600 1024 x 768 1280 x 1024

Typical Notebook PC LCD

508,800 786,432 1,310,720

Number of Pixels

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Addressing Architecture

CMOS SRAM for Electrostatic Operation

CMOS 5 V Drive

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Brightness Control

Pulse Width Modulation for Gray Scale Image

Similar to the principle of LCD display

ON

OFF

Bright

Dark

Time

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Color Synthesis by One DMD Chip

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Color Synthesis by Two DMD Chips

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Color Synthesis by Three DMD Chips

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Schematic of Three-DMD Projector

Can you figure out how it works ? ...

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