Photochromic display device utilizing light valve activation

Claim 2

A display system for display of an image of an object from video signals comprising a first light source of a first wavelength, the light from said first source transmitted along a first optical path for projection of an image, a photochromic member positioned in said first optical path, a drive system for directing a scanning radiation beam over said photochromic screen to modify the opaqueness of said photochromic screen, said drive means comprising a second light source of a second wavelength, means for directing the light along a second optical path from said second source onto said photochromic screen, light valve control means positioned between said second light source and said light valve control means in said second optical path comprising an optically active screen member responsive to an electric field applied thereacross and means to scan a raster over said optically active material to modify the optical activity thereof in accordance with a video signal applied to said scanning means.

Claim 3

The display system set forth in claim 1 in which light valve means comprises a cathode ray tube and said scanning means is an electron beam, said optically active screen exhibiting the pockel effect, means for projecting the collimated light beam from said first source polarized in a predetermined acceptance plane toward and through said optically active screen, said optically active screen comprised of a plate of transparent non-conductive material having a layer of transparent electrically conductive material thereto and being connected to a potential source, said electron beam means scanning the surface of said non-conductive material to create an electric field between said surface and said electrical conductive layer to vary the optical properties thereof in response to the value of an electrical field thereacross and thereby modify the polarized condition of said polarized light passing therethrough and a polarizing means having an acceptance plane normal to the polarized condition of said light beam after passing said optically active screen when unexcited for intercepting the light beam from said second source after passing through said optically active screen and passing only the portion of said light beam having a modified polarization by said optically active screen.

Claim 4

The display system set forth in claim 1 in which said second light source emits light in the ultraviolet region.

Claim 5

The display system of claim 1 in which said photochromic screen is responsive to said second wavelength by a change in its opaqueness to said first wavelength and is substantially non-responsive to said first wavelength.