PLZT ceramic display devices for slow-scan graphic projection displays

A projection display device for slow-scan graphics has been developed using the scattering properties of PLZT ferroelectric ceramics. The device consists of a ferroelectric-photoconductor sandwich in which a Cd1-xZnxS mixture is used as a photoconductive film. The composition of the film is controlled to provide peak photosensitive response at 441.6 nm, corresponding to the blue line from a He-Cd laser. Any image can be written into the device with a combination of steered laser beam (less than 1 mW) and electrically applied pulses, held for an indefinite time without sustaining power and erased electrically. Because of the properties of the photoconductive film, selective erase and simultaneous reading and writing are possible. The all-solid-state structure of the device combined with the scattering properties of the ceramic permit the device to be used as a slide in a conventional 35-mm projector.