Solid-state light valves with viscoelastic control layers for projection displays. I. Operating principle and theoretical analysis

High resolution and high brightness of displayed images can be achieved at the same time if light-valve projection is employed. With a light valve, the resolution is determined by the control layer (often called spatial light modulator), while the brightness is essentially established by a completely separate light source. Because of these features, light valves are very well suited to the use in large-image projectors for high-definition television (HDTV). Here, a solid-state light valve, whose operation is based on diffraction from optical phase gratings, will be described. The phase gratings are generated by electric fields being applied to the metallized surfaces of very thin viscoelastic layers. Electrical addressing is accomplished preferably by an active matrix so that compact and fully integrated 'light-valve chips' can be used as spatial light modulators.