High Contrast SXGA Silicon Light Valves for High Definition Video Projectors

摘要

We have developed a highly integrated liquid-crystal-on-silicon light valve for three-panel color projector. The silicon panel was designed and fabricated by a 0.35 mu m, 3-metal and dual-voltage CMOS process with a spatial resolution of 1280 x 1024 pixels. The pixel pitch was 12 mu m, the fill factor was 90percent and the display area was 0.77" in diagonal. Eight-bit digital data drivers and gamma-correction circuitry were integrated into the silicon panel for true gray scale and full color representation. The display panel was assembled with a mixed twisted nematic and birefringence liquid crystal cell for high contract at CMOS compatible voltage. Contrast ratio was typically 200:1 at 5.5Vrms. In addition, silicon surface layers, liquid crystasl materials, pixel structures and driving schemes were carefully optimized for the minimization of visual flicker. Flicker ratio of less than 3percent was achieved at 60Hz frame rate. The optical sub-system utilized a trichroic prism assembly for both color separation and recombination. With this trichroic prism assembly incorporating three silicon light valves, a compact and high-contrast SXGA video projector was demonstrated.