Liquid crystal memory, system utilizing the memory and methods of constructing and operating such a memory

Claim 2

In a memory element, a liquid crystal layer contained between transparent surfaces, said crystal being selected to have first and second stable molecular axis orientations having complementary tilt angles of about 45* with respect to said surfaces, the molecular axis orientation of the liquid crystal molecules being shiftable from one tilt angle to the other in response to polarized light directed onto the liquid crystal molecules, with the electric field vector of the light being perpendicular to the long axes of the liquid crystal molecules, said surfaces being treated to cause the uniform orientation of the long axes of the molecules in said layer to insure that said axes will align along either a first or a second stable molecular orientation, and also being treated to insure that the molecular layers within said crystals are substantially parallel to said transparent surfaces.

Claim 3

The memory defined in claim 1 wherein the angle between said stable molecular directions is substantially 90*.

Claim 4

A method for setting selected molecular groups in the memory of claim 1 comprising: directing a high intensity light beam to selected molecular groups representing memory elements, said light beam having an electric field vector in the plane normal to said beam with an angle with respect to said first bistable direction sufficiently large to cause rotation of the selected molecules to align with said second stable direction.

Claim 5

A method for resetting selected molecules in the memory of claim 1 comprising: directing a high intensity light beam to the selected molecules with the electric field vector in a plane normal to said beam and having an angle with respect to the second of said stable directions of sufficient energy to cause rotation of the selected molecules from said second stable direction to said first stable direction.

Claim 6

A method for resetting molecular groups representing memory elements in the memory of claim 1 comprising: directing a magnetic field substantially along a vector parallel to said first stable direction to cause rotation of memory elements in said second stable direction to assume said first stable direction.

Claim 7

A memory comprising a liquid crystal layer contained between transparent surfaces, the surfaces being treated such that the long axes of the liquid crystal molecules assume one of two compLementary stable orientations with respect to the transparent surfaces, means for directing a beam of polarized light against the entirety of said layer along the axes of the liquid crystal molecules in one of said two stable orientations, with the electric field vector of the polarized light being perpendicular to the long axes of said molecules, the intensity of the light beam being such as to cause the long axes of all molecules to assume a position parallel to said electric vector, means for directing a beam of polarized light against selected areas of said layer along the axes of the liquid crystal molecules in the other of said two stable orientations, with the electric field vector of the polarized light being perpendicular to the long axes of the molecules in said other orientation, said latter-mentioned beam of light being of such intensity to cause the long axes of the molecules in only those selected areas to rotate back to said one stable orientation, and means for directing a beam of polarized light through said liquid crystal layer in a direction parallel to the molecular axes in one of said two stable orientations whereby the polarized light will differentially pass through said selected areas and the remainder of the layer.

Claim 8

A memory comprising a liquid crystal layer contained between transparent surfaces, the surfaces being treated such that the long axes of the liquid crystal molecules assume one of two compLementary stable orientations with respect to the transparent surfaces, means for directing a beam of polarized light against the entirety of said layer along the axes of the liquid crystal molecules in one of said two stable orientations, with the electric field vector of the polarized light being perpendicular to the long axes of said molecules, the intensity of the light beam being such as to cause the long axes of all molecules to assume a position parallel to said electric vector, means for directing a beam of polarized light against selected areas of said layer along the axes of the liquid crystal molecules in the other of said two stable orientations, with the electric field vector of the polarized light being perpendicular to the long axes of the molecules in said other orientation, said latter-mentioned beam of light being of such intensity to cause the long axes of the molecules in only those selected areas to rotate back to said one stable orientation, and means for directing a beam of polarized light through said liquid crystal layer in a direction parallel to the molecular axes in one of said two stable orientations whereby the polarized light will differentially pass through said selected areas and the remainder of the layer.

Claim 9

The memory of claim 6 wherein said liquid crystal is of the smectic C-phase type.

Claim 10

The memory of claim 6 wherein said last-mentioned beam of polarized light is of insufficient intensity to cause rotation of the axes of said molecules from one stable orientation to the other.

Claim 11

The combination of claim 6 wherein said liquid crystal layer is bounded by prisms.

Claim 12

The combination of claim 6 wherein the last-mentioned polarized light beam passes through said liquid crystal layer along the axes of said molecules in said other of the two stable orientations.