HKUST A High-Resolution Projection Display Based on Silicon Light Valves P W Cheng, H C Huang and H S Kwok Centre for Display Research Department of Electrical and Electronic Engineering The Hong Kong University of Science & Technology HKUST Outline Silicon Light Valve XGA Display Features Optical Engine Conclusion HKUST Characteristics and Topography Fine pixels on the top as reflective mirrors All the electronics are beneath the mirrors Light shield and surface planarization HKUST Silicon Advantages Full driver Integration and fine pixels High fill factor Mature silicon VLSI technology HKUST SEM Pictures of Fine Pixels 9.6 m pixels 86% fill factor Virtual Reality 13.8 m pixels 91% fill factor Projection HKUST Effect of Pixel Size on Optical Performance ( Comparison between theory and experiment ) HKUST Fabrication Flow Front-end for electrical functions Full integration of display drivers Pixels of high breakdown voltage Standard 0.5 m CMOS process Back-end for optical performance Surface planarization and light shield Pixels of high fill factor Modified 0.35 m process HKUST HKUST-XGA Panel Specifications Resolution: 1024 x 768,13.8 mpixels Fill factor:91% Reflectivity:90% (dielectric mirror) Process: 0.5 m FE/0.35 m BE Data driver:6-bit, 2 channels LC Mode: MTB NW or NB Others:Built-in gamma corrections HKUST Functional Block Diagram ODD-COLUMN DATA DRIVERS D/A CONVERTERS SCAN DRIVERS 1024 x 768 PIXEL ARRAY QA1 BIT1 SHR SCLK FLM SCAN_DN CLK1 DISP1 ODD_DATA (0:5) V1, V2, V3, V4 VG1, VG2, VG3,VG4 VB1, VB2 FRAME D/A CONVERTERS EVEN-COLUMN DATA DRIVERS REFERENCE VOLTAGE GENERATOR CLK2 DISP2 EVEN_DATA (0:5) VCC, VDD, VDD2 GND SHIELD BIT2 SOUT Almost identical to TFT panel with full driver integration HKUST Fine and Resolvable Pixels Advantage of digital driving scheme HKUST Reflectance-vs-Voltage Curves Contrast Ratios: Red 169:1 Green 101:1 Blue 68:1 White 108:1 Wide-band MTB NW mode for three primary colors HKUST Gamma Correction VG1 VG2 VG3 VG4 Fine tune of linear gray scale for three primary colors HKUST Optical Engine Trichroic prism assembly (TPA) 16 o incident angle (patent pending) MH Lamp B D A C B-LCD G-LCD R-LCD PBS H. S. Kwok etal, to be published on Applied Optics, 1999 HKUST Good Color Fidelity for TPA - Experimental Results Negligible S-P Polarization Split HKUST Measured color coordinates Includes the effects of the halogen light source and the TPA HKUST Good Color Saturation by the Optical Engine HKUST Linear Gray Scale by correction HKUST Projected Image on the Screen HKUST Projector Prototype Specifications HKUST Conclusions Highly Integrated Silicon Light Valve Front-end for electrical functions Back-end for optical optimization XGA Projection Display Features Fine and resolvable pixels Linear gray scale Good color saturation HKUST Acknowledgements Dr. Steve Yeung and Mr. George Lee of Varitronix (HK) for making LC cells Sponsored by Industry Department of Hong Kong Government HKUST END (of IDRC99) Screen