Liquid crystal light valve showing an improved display contrast

A liquid crystal light valve comprising first and second transparent plates, a liquid crystal layer formed between said first and second transparent plates, a transparent electrode formed between said first transparent plate and said liquid crystal layer, plural light reflective electrode layers formed between said second transparent plate and said liquid crystal layer, and optical switching elements formed between each of said light reflective electrode layers and said second transparent plate, said light switching elements respectively including a photo-detector circuit and a thin-film-transistor drive circuit constituting a source follower circuit, each of said photo-detector circuits comprising a photodiode member and a passive element layer serially connected to each other between a pair of wiring electrodes having a potential difference therebetween, said drive circuit receiving the voltage produced by said photo-detector circuit as an input, and the output from said drive circuit being connected to said respective light reflective electrode layer so that the output from said photo-detector circuit is controlled by the amount of the incident light on said photodiode member to thereby control the voltage applied on said respective light reflective electrode.

A liquid crystal light valve comprising a first transparent insulating substrate provided with a plurality of light switching elements respectively connected to pixel electrodes, a second transparent insulating substrate provided with transparent electrodes, and a liquid crystal sandwiched between the first substrate and the second substrate, each of said light switching elements including a photo-detector circuit and a transistor drive circuit respectively connected between a high voltage terminal and a low voltage terminal, said transistor drive circuit constituting a source follower circuit, said photo-detector circuit comprising a photo-diode and a capacitor element serially connected to each other, a cathode of said photo-diode being connected to said high voltage terminal, an input terminal of said transistor drive circuit being connected to a node connecting said photodiode and said capacitor element, an output terminal of said transistor drive circuit being connected to said pixel electrodes.