Proceedings PaperNext generation photoactivated light valve projection systems
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A great deal of effort has been directed to the production of large area, high pixel density, high brightness displays systems. Hughes Aircraft (Carlsbad), who continues the work under the Hughes/JVC joint venture, has been and continues to be a leader in this field. This class of display uses projection of images from a reflective mode liquid crystal under the control of a photoactivated panel. Alternate means for reaching the same goal are being explored in a number of laboratories. Many designs use a matrix of transistors or scanned row and column electrodes coupled to a liquid crystal modulator. They are used either in a transmissive, or under development, reflective mode. The leader in this field is Sharp Corporation. LighTouch Systems is taking the approach of using the photoactivated reflective mode approach, similar to Hughes. However, the internal structure developed by LighTouch Systems recognizes the need for a more efficient structure in coupling the source image to the liquid crystal modulator. In particular, an internal structure that is in essence a phototransistor, rather than a photodiode, will support sensitivities, resolutions, and speeds that are a marked improvement over existing designs. These advances are critical for low cost, simple and effective large screen projection systems.