Process and composition for selectively bleaching a polarizer, and particularly a polarizer used in a liquid crystal display, to achieve sharply-defined polarizing areas in accurate registration with the transparent conductive areas of the display. This is achieved by silk-screening a gel, containing a bleaching agent, onto selected areas of a polarizer in place of the display, the gel having a viscosity to permit silk-screening.

A method for fabricating a liquid crystal display device includes the steps of providing a pair of insulated electrode-carrying plates, depositing on the surface of one of the plates, overlying the electrodes a layer of photopolymeric material approximately 0.0005 inches in thickness, masking and light exposing the photopolymeric layer and thereafter developing a way with a suitable solvent a predetermined area of material to provide a cavity in the photopolymeric layer through which the electrodes on the plate are accessible. On the surface of the second one of the plates whereat the second set of electrodes are located, a layer of photopolymeric material of approximately 0.0005 inches in thickness is deposited by masking and light exposing the second photopolymeric material and thereafter developing away with a suitable solvent, a predetermined area of material which is slightly smaller than the area provided by the first area of material is produced to provide a cavity in the photopolymeric layer through which the electrodes on the second plate are accessible. The first and second electrode-carrying plates are bonded together to seal the edges of the cavity. The cavity is filled with a liquid crystal composition through an aperture provided in the photopolymeric layer on one of the plates and thereafter the hole is sealed to retain the liquid crystal composition in the cavity.

A liquid crystal display of the twisted-nematic type in which light numerals or other indicia appear on a darker background. This is achieved with the use of three polarizers, one of which covers only the transparent conductive electrode regions in the display forming a desired image.

Information in binary form is stored in a planar array or mosaic of light-polarizing cells, wherein each cell may have two distinct orientations of the axis of polarization. For example, binary "1" may be denoted by setting the axis of polarization in any cell to the vertical, and binary "0" by setting the axis to horizontal. Binary data so stored are invisible to the naked eye, but will become visible as a pattern of light and dark spots when viewed through a second polarizer. A unique property of light-polarizing mosaics is that when two such mosaics are laid one atop the other in precise registration, the resulting visible pattern of light and dark spots portrays the modulo-two sum (also known as the "exclusive or" product) of the two sets of binary information stored therein. If the binary data stored in one such mosaic were data created by modulo-two addition of a set of intelligible data with a set of random data, and if this same set of random data were stored in a second such mosaic, the original data will become immediately visible in its intelligible form merely by overlaying the two mosaics.

Disclosed is a reflector for use in electro-optical displays utilizing electro-optical materials. The reflector is made from a composition comprising a blend of at least one alkali earth metal salt with a binder such as sodium carboxy methyl cellulose or thermoplastic phenoxy and an amount of solvent sufficient to provide suitable viscosity to permit the reflector to be deposited as a reflector on the display. The reflector composition comprises from about 30% to about 99.9% by weight of the alkali earth metal salt to the weight of binder casted to be adjacent to and directly adhered to the side of the back plate facing away from the electro-optical material and is able to provide a wide reflecting angle in conjunction with maintaining a high contrast ratio between the electrically energized state and the electrically un-energized state of the electro-optical material contained within the display.