Liquid crystal display apparatus

Claim 2

A display system including a. a liquid crystal display cell comprising a layer of liquid crystal substance and two transparent support substrates for containing said layer of liquid crystal substance, said liquid crystal substance being arranged to exhibit differing lightscattering properties in response to thermal excitation, b. projection means including a source of projection light for projecting an image stored in said liquid crystal substance onto a viewing surface, and c. means for controllably heating selected areas of said liquid crystal substance above the transition temperature of said liquid crystal substance, said means for heating comprising means for selectively applying laser light to said liquid crystal substance, wherein said liquid crystal display cell further includes a first layer of electrically conducting material between one of said transparent support substrates and said liquid crystal substance and a second layer of electrically conducting material transparent to viewing light between the other of said transparent support substrates and said liquid crystal substance, and means for controllably applying high-frequency electrical signals to said layers of conducting material, and wherein at least one of said layers of conducting material is an absorbing electrode for absorbing a portion of said laser light to produce a heated region in response thereto which is sufficiently high in temperature to raise the temperature of said liquid crystal substance above the transition temperature of said liquid crystal substance, and wherein each of said absorbing electrodes comprises indium tin oxide including excess carriers sufficient to establish free carrier absorption of light having a wavelength in the range 0.8 Mu m to 1.6 Mu m and said means for applying laser light comprises apparatus for emitting light having a wavelength in the range 0.8 Mu m to 1.6 Mu m.

Claim 3

Apparatus as in claim 1 wherein said layer of liquid crystal substance comprises a cholesteric liquid crystal substance having negative dielectric anisotropy and in which the molecules in the ordered state are arranged to have the long axes thereof aligned in a direction parallel to the surface of the conducting electrodes.

Claim 4

Apparatus as in claim 2 wherein said cholesteric liquid crystal substance is a solution of MBBA including 10 percent by weight solution of CN and 2 percent by weight of Butyl Aniline.

Claim 5

Apparatus as in claim 3 wherein said means for applying coherent light comprises a GaAs laser source for emitting coherent light having a wavelength 0.9 Mu m.

Claim 6

Apparatus as in claim 3 wherein said means for applying coherent light comprises a YAG laser source for emitting coherent light having a wavelength 1.06 Mu m.

Claim 7

Apparatus as in claim 3 wherein said means for applying coherent light comprises a HeNe laser source for emitting coherent light having a wavelength 1.15 Mu m.

Claim 8

Apparatus as in claim 3 wherein said means for applying coherent light comprises a gallium aluminum arsenide source for emitting light having a wavelength in the range 0.8 Mu m to 0.9 Mu m.

Claim 9

A display system including a. a liquid crystal display cell comprising a layer of liquid crystal substance and two transparent support substrates for containing said layer of liquid crystal substance, said liquid crystal substance being arranged to exhibit differing light-scattering properties in response to thermal excitation, b. projection means including a source of projection light for projecting an image stored in said liquid crystal substance onto a viewing surface, and c. means for controllably heating selected areas of said liquid crystal substance above the transition temperature of said liquid crystal substance, said means for heating comprising means for selectively applying laser light to said liquid crystal substance, wherein said display cell futher comprises i. a layer of heat-producing material adjacent a first one of said transparent electrodes for transforming light from said source of addressing light into heated regions in said heat-producing material, ii. a first erasing electrode layer intermediate said layer of heat-producing material and said liquid crystal substance, said first erasing electrode layer being arranged to reflect projection light and to conduct heat to said liquid crystal substance, and iii. a second erasing electrode layer intermediate the second one of said support substrates and said liquid crystal substance said second erasing electrode being transparent to light from said source of viewing light.

Claim 10

A display system including a. a liquid crystal display cell comprising a layer of liquid crystal substance and two transparent support substrates for containing said layer of liquid crystal substance, said liquid crystal substance being arranged to exhibit differing light-scattering properties in response to thermal excitation, b. projection means including a source of projection light for projecting an image stored in said liquid crystal substance onto a viewing surface, and c. means for controllably heating selected areas of said liquid crystal substance above the transition temperature of said liquid crystal substance, said means for heating comprising means for selectively applying laser light to said liquid crystal substance, wherein said display cell futher comprises i. a layer of heat-producing material adjacent a first one of said transparent electrodes for transforming light from said source of addressing light into heated regions in said heat-producing material, ii. a first erasing electrode layer intermediate said layer of heat-producing material and said liquid crystal substance, said first erasing electrode layer being arranged to reflect projection light and to conduct heat to said liquid crystal substance, and iii. a second erasing electrode layer intermediate the second one of said support substrates and said liquid crystal substance said second erasing electrode being transparent to light from said source of viewing light.

Claim 11

Apparatus as in claim 8 further including a source of high frequency electrical signals and means for controllably applying said signals to said erasing electrode layers.

Claim 12

A cell as in claim 9 wherein said isolating material comprises an electrical insulating substance, and wherein each of said first and second plurality of light-reflecting elements further comprises means for establishing thermal and electrical conduction paths among selected ones of their respective reflecting elements.

Claim 13

A display system including a. a liquid crystal display cell comprising a layer of liquid crystal substance and two transparent support substrates for containing said layer of liquid crystal substance, said liquid crystal substance being arranged to exhibit differing light-scattering properties in response to thermal excitation, b. projection means including a source of projection light for projecting an image stored in said liquid crystal substance onto a viewing surface, and c. means for controllably heating selected areas of said liquid crystal substance above the transition temperature of said liquid crystal substance, said means for heating comprising means for selectively applying laser light to said liquid crystal substance, and wherein said display cell further includes i. a first current-carrying layer contiguous to and coextensive with one of said transparent substrates, said first current-carrying layer being transparent to light from said source of addressing light, ii. a heat-producing layer adjacent and coextensive with said first current-carrying layer for transforming coherent light incident on said heat-producing layer into thermal energy. iii. a plurality of spatially separated reflectors adjacent sAid heat-producing layers for reflecting said projection light, iv. a second current-carrying layer contiguous to and coextensive with the other one of said transparent support substrates, said second current-carrying layer being transparent to light from said source of projection light and v. a source of high-frequency alternating voltage controllably connected to said first and second current-carrying electrode layers.

Claim 14

A display system including a. a liquid crystal display cell comprising a layer of liquid crystal substance and two transparent support substrates for containing said layer of liquid crystal substance, said liquid crystal substance being arranged to exhibit differing light-scattering properties in response to thermal excitation, b. projection means including a source of projection light for projecting an image stored in said liquid crystal substance onto a viewing surface, and c. means for controllably heating selected areas of said liquid crystal substance above the transition temperature of said liquid crystal substance, said means for heating comprising means for selectively applying laser light to said liquid crystal substance, and wherein said display cell further includes i. a first current-carrying layer contiguous to and coextensive with one of said transparent substrates, said first current-carrying layer being transparent to light from said source of addressing light, ii. a heat-producing layer adjacent and coextensive with said first current-carrying layer for transforming coherent light incident on said heat-producing layer into thermal energy. iii. a plurality of spatially separated reflectors adjacent sAid heat-producing layers for reflecting said projection light, iv. a second current-carrying layer contiguous to and coextensive with the other one of said transparent support substrates, said second current-carrying layer being transparent to light from said source of projection light and v. a source of high-frequency alternating voltage controllably connected to said first and second current-carrying electrode layers.

Claim 15

A display system including a. a liquid crystal display cell comprising a layer of liquid crystal substance and two transparent support substrates for containing said layer of liquid crystal substance, said liquid crystal substance being arranged to exhibit differing light-scattering properties in response to thermal excitation, b. projection means including a source of projection light for projecting an image stored in said liquid crystal substance onto a viewing surface, and c. means for controllably heating selected areas of said liquid crystal substance above the transition temperature of said liquid crystal substance, said means for heating comprising means for selectively applying laser light to said liquid crystal substance, and wherein said display cell further includes i. a first layer of current-carrying material contiguous to and coextensive with one of said transparent support substrates, said first layer of current-carrying material being transparent to light from said means for applying coherent light, ii. a layer of photosensitive material contiguous to and coextensive with said first layer of current-carrying material, said layer of photosensitive material being arranged to transform said coherent light within a range of power levels sufficient to raise the temperature of said liquid crystal substance beyond its transition temperature and to conduct increased current in response to said coherent light within a second range of power levels, iii. means intermediate said photosensitive layer and said liquid crystal substance for reflecting said projection light, iv. a second layer of current-carrying material contiguous to and coextensive with said second support substrate and said liquid crystal substance, said second current-carrying material being transparent to light from said projection means, and v. means for applying an electric potential between said first and second current-carrying layers sufficient to affect light-scattering centers within said liquid crystal substance only when addressing light within said second range of power levels irradiates said photosensitive material.

Claim 16

A display system including a. a liquid crystal display cell comprising a layer of liquid crystal substance and two transparent support substrates for containing said layer of liquid crystal substance, said liquid crystal substance being arranged to exhibit differing light-scattering properties in response to thermal excitation, b. projection means including a source of projection light for projecting an image stored in said liquid crystal substance onto a viewing surface, and c. means for controllably heating selected areas of said liquid crystal substance above the transition temperature of said liquid crystal substance, said means for heating comprising means for selectively applying laser light to said liquid crystal substance, and wherein said display cell further includes i. a first layer of current-carrying material contiguous to and coextensive with one of said transparent support substrates, said first layer of current-carrying material being transparent to light from said means for applying coherent light, ii. a layer of photosensitive material contiguous to and coextensive with said first layer of current-carrying material, said layer of photosensitive material being arranged to transform said coherent light within a range of power levels sufficient to raise the temperature of said liquid crystal substance beyond its transition temperature and to conduct increased current in response to said coherent light within a second range of power levels, iii. means intermediate said photosensitive layer and said liquid crystal substance for reflecting said projection light, iv. a second layer of current-carrying material contiguous to and coextensive with said second support substrate and said liquid crystal substance, said second current-carrying material being transparent to light from said projection means, and v. means for applying an electric potential between said first and second current-carrying layers sufficient to affect light-scattering centers within said liquid crystal substance only when addressing light within said second range of power levels irradiates said photosensitive material.

Claim 17

A display system including a liquid crystal display cell comprising a. a layer of liquid crystal substance arranged to scatter light within a specified range of wavelengths in response to thermal excitation, b. first and second support substrates for containing said layer of liquid crystal substance, c. a first plurality of current-carrying elements adjacent one of said transparent support substrates and a second plurality of current-carrying elements adjacent said second support substrate and intermediate said second support substrate and said liquid crystal substance, d. a layer of heat generating substance adjacent said first support substrate and contiguous said first plurality of current-carrying elements, for producing heat from electrical energy, e. a third plurality of current-carrying elements adjacent said heat generating layer and intermediate said heat generating layer and said liquid crystal substance, f. means for applying electrical energy to selected ones of said first and third current-carrying elements, said electrical energy being arranged to induce said heat generating substance to produce heat sufficiently high to cause scattering centers of light in said liquid crystal substance, and g. means for applying electrical signals to selected ones of said second and third pluralities of current-carrying elements to remove scattering centers of lIght from said liquid crystal substance, and projection means for generating a representation of differences in the scattering of light by said liquid crystal substance.

Claim 18

A display system including a liquid crystal display cell comprising a. a layer of liquid crystal substance arranged to scatter light within a specified range of wavelengths in response to thermal excitation, b. first and second support substrates for containing said layer of liquid crystal substance, c. a first plurality of current-carrying elements adjacent one of said transparent support substrates and a second plurality of current-carrying elements adjacent said second support substrate and intermediate said second support substrate and said liquid crystal substance, d. a layer of heat generating substance adjacent said first support substrate and contiguous said first plurality of current-carrying elements, for producing heat from electrical energy, e. a third plurality of current-carrying elements adjacent said heat generating layer and intermediate said heat generating layer and said liquid crystal substance, f. means for applying electrical energy to selected ones of said first and third current-carrying elements, said electrical energy being arranged to induce said heat generating substance to produce heat sufficiently high to cause scattering centers of light in said liquid crystal substance, and g. means for applying electrical signals to selected ones of said second and third pluralities of current-carrying elements to remove scattering centers of lIght from said liquid crystal substance, and projection means for generating a representation of differences in the scattering of light by said liquid crystal substance.

Claim 19

In a reflection mode liquid crystal display cell comprising a layer of liquid crystal substance, at least two support substrates for containing said liquid crystal substance, light-reflecting means positioned between said liquid crystal layer and one of said substrates, the improvement comprising a. a first plurality of spatially separated light-reflecting elements contiguous to one of said substrates for reflecting applied viewing light, b. a layer of transparent isolating material adjacent said first plurality of reflecting elements for imbedding said first plurality of elements, and c. a second plurality of light-reflecting elements adjacent said layer of isolating material and separated from said first plurality of elements by said isolating material said first plurality of elements being positioned relative to said second plurality of reflecting elements such that said light-reflecting means reflects light from substantially all points incident on the face thereof.

Claim 20

In a reflection mode liquid crystal display cell comprising a layer of liquid crystal substance, at least two support substrates for containing said liquid crystal substance, light-reflecting means positioned between said liquid crystal layer and one of said substrates, the improvement comprising a. a first plurality of spatially separated light-reflecting elements contiguous to one of said substrates for reflecting applied viewing light, b. a layer of transparent isolating material adjacent said first plurality of reflecting elements for imbedding said first plurality of elements, and c. a second plurality of light-reflecting elements adjacent said layer of isolating material and separated from said first plurality of elements by said isolating material said first plurality of elements being positioned relative to said second plurality of reflecting elements such that said light-reflecting means reflects light from substantially all points incident on the face thereof.

Claim 21

A cell as in claim 14 wherein said layer of transparent isolating material comprises a heat-resistant substance.

Claim 22

A display system including a. a liquid crystal display cell comprising a layer of liquid crystal substance and two transparent support substrates for containing said layer of liquid crystal substance, said liquid crystal substance being arranged to exhibit differing light-scattering properties in response to thermal excitation, b. projection means including a source of projection light for projecting an image stored in said liquid crystal substance onto a viewing surface, and c. means for controllably heating selected areas of said liquid crystal substance above the transition temperature of said liquid crystal substance, said means for heating comprising means for selectively applying laser light to said liquid crystal substance, wherein said liquid crystal display cell further includes a first layer of electrically conducting material between one of said transparent support substrates and said liquid crystal substance and a second layer of electrically conducting material transparent to viewing light between the other of said transparent support substrates and said liquid crystal substance, and means for controllably applying high-frequency electrical signals to said layers of conducting material, and wherein at least one of said layers of conducting material is an absorbing electrode for absorbing a portion of said laser light to produce a heated region in response thereto which is sufficiently high in temperature to raise the temperature of said liquid crystal substance above the transition temperature of said liquid crystal substance and wherein each of said absorbing electrodes comprises material for absorbing laser light in the ultraviolet range.

Claim 23

A display system including a. a liquid crystal display cell comprising a layer of liquid crystal substance and two transparent support substrates for containing said layer of liquid crystal substance, said liquid crystal substance being arranged to exhibit differing light-scattering properties in response to thermal excitation, b. projection means including a source of projection light for projecting an image stored in said liquid crystal substance onto a viewing surface, and c. means for controllably heating selected areas of said liquid crystal substance above the transition temperature of said liquid crystal substance, said means for heating comprising means for selectively applying laser light to said liquid crystal substance, wherein said liquid crystal display cell further includes a first layer of electrically conducting material between one of said transparent support substrates and said liquid crystal substance and a second layer of electrically conducting material transparent to viewing light between the other of said transparent support substrates and said liquid crystal substance, and means for controllably applying high-frequency electrical signals to said layers of conducting material, and wherein at least one of said layers of conducting material is an absorbing electrode for absorbing a portion of said laser light to produce a heated region in response thereto which is sufficiently high in temperature to raise the temperature of said liquid crystal substance above the transition temperature of said liquid crystal substance and wherein each of said absorbing electrodes comprises material for absorbing laser light in the ultraviolet range.

Claim 24

Apparatus as in claim 16 wherein said material comprises indium tin oxide for absorbing light from a helium cadmium laser source emitting light having a wavelength of 0.325 Mu m.

Claim 25

Apparatus as in claim 16 wherein said material comprises indium tin oxide for absorbing light from a krypton laser source emitting light having a wavelength of 0.35 Mu m.