Abstract: An electro-optic device comprising, in turn, a first electrode, a photoconductive layer, a liquid crystalline layer, and a second electrode, and imaged with background at a voltage v.sub.o, is imaged without background by relatively slowly applying v.sub.o. Optionally, v.sub.o is relatively slowly reduced to zero to prevent background creation during removal of v.sub.o.

Abstract: High quantum yields are provided by sandwiching an insulating layer in contact with a photoconductor between two electrodes. The sandwiched structure in conjunction with an applied electrical potential and excitation light provides an electrical switching device. Optionally, an imaging layer can be included between the photoconductive layer and one of the electrodes, and can be imaged with increased sensitivity.

Abstract: An imaging system wherein an imaging member comprises a layer of a homeotropically aligned nematic liquid crystalline material which is optically uniaxial residing on a photoconductive insulating layer. When the liquid crystal layer is subjected to an electrostatic charge and the photoconductive insulating layer is exposed to an imagewise pattern of activating electromagnetic radiation, the liquid crystalline material is subjected in selective areas to an electrical field which has components both in the plane of the layer and normal to the plane of the layer thereby inducing optical biaxiality in those areas of the imaging material. In a preferred embodiment of the invention a layer of a suitable overcoating material is arranged over the liquid crystal layer.

Abstract: The electrical resistivity of pure trans-stilbene nematic liquid crystalline materials is altered by exposure to ultraviolet radiation. These stilbenes can therefore be made to dynamically scatter uniformly or in imagewise configuration and can be added to liquid crystalline compositions to alter the compositions' resistivities.

Abstract: A nematic liquid crystalline composition having positive dielectric anisotropy is provided in the homeotropic texture by contact with a layer of an electrically insulating polysiloxane elastomer. An electrical field is then applied parallel to the molecular axes of the nematic resulting in reorientation of the nematic molecules.

Abstract: A system which transforms a liquid crystal composition having a mixture of cholesteric liquid crystal or other optically active materials and nematic liquid crystal materials from an electrically induced dynamic scattering state into an aligned nematic state by changing variables of an applied electrical field, and an imaging system wherein such a liquid crystal member is imaged in a desired image configuration by such an electrical field-induced transition system. Such systems exhibit high optical contrast and may be viewed without the aid of light polarizing devices.

Abstract: Increased sensitization of liquid crystalline devices utilizing current flow to provide a change in optical characteristics is provided by sandwiching a photoconductive layer between an insulating layer and a liquid crystalline layer wherein all three layers are placed between two electrodes. The sandwich device is utilized in an imaging method wherein an electrical potential is applied across said device, a bias or sensitizing light is utilized to bring the device up to the threshold for gain photocurrent and then removed, and wherein a subsequent light is utilized to gate or initiate gain photocurrent. Alternatively, the biasing light may be in imagewise configuration which forms a latent image in which case the subsequent light can be a uniform exposure which gates the gain photocurrent, thereby developing the latent image.

Abstract: The optical transitions of extrinsically optically active insoluble materials become optically active and circularly dichroic when in contact with optically negative liquid crystalline materials thereby providing unusual and highly advantageous properties. The circularly dichroic optical properties induced in the extrinsically optically active insoluble materials can be utilized for information transfer applications.

Abstract: The optical transitions of extrinsically optically active insoluble materials become optically active and circularly dichroic when in contact with optically negative liquid crystalline materials thereby providing unusual and highly advantageous properties. The circularly dichroic optical properties induced in the extrinsically optically active insoluble materials can be utilized for optical filter applications.

Abstract: The optical transitions of extrinsically optically active insoluble materials become optically active and circularly dichroic when in contact with optically negative liquid crystalline materials thereby providing unusual and highly advantageous properties. The circularly dichroic optical properties induced in the extrinsically optically active insoluble materials can be utilized for optical display applications.

Abstract: The optical transitions of extrinsically optically active insoluble materials become optically active and circularly dichroic when in contact with optically negative liquid crystalline materials thereby providing unusual and highly advantageous properties. The circularly dichroic optical properties induced in the extrinsically optically active insoluble materials can be utilized for optical filter applications.

Abstract: The optical transitions of extrinsicially optically active insoluble materials become optically active and circularly dichroic when in contact with optically negative liquid crystalline materials thereby producing unusual and highly advantageous properties. The circularly dichroic optical properties induced in the extrinsically optically active insoluble materials can be utilized for converting infrared images to visible images.

Abstract: Liquid crystalline compositions comprising dielectrically negative nematic liquid crystalline materials from about 0.4 percent by weight to about 3 percent by weight optically active materials, in contact with an aligning agent, and characterized by a helical pitch to layer thickness ratio of from about 1 to about 10 are transformed from an initially homeotropic or homogeneous texture into a novel stable spherulitic texture upon removal of an applied D.C. or low frequency A.C. electrical field. Erasure and imaging of the novel spherulitic texture are disclosed.

Abstract: High quantum yields of gain photocurrent provided by sandwiching an insulating layer in contact with a photoconductor between two electrodes, applying an electrical potential thereacross, and directing excitation light upon the photoconductor are increased by simultaneously impinging the photoconductor with infrared radiation during exposure to the excitation light where the photoconductor comprises selenium or a selenium alloy. In cyclical operation of gain photocurrent devices having a photoconductive layer comprising selenium or a selenium alloy, fatigue effects are overcome by irradiation with infrared radiation.

Abstract: Coding of a group of characters for recognition by a machine and by a human viewer is provided by coloring each character with a predetermined plurality of colors arranged in predetermined locations within a character configuration. Each character configuration in a set of characters is segregated into a plurality of sectors and each sector is coded by a predetermined one of a plurality of colors which differs from the color coding of an adjacent sector. Apparatus for forming the color-coded characters by printing and by a photoelectrophoretic process is disclosed. Apparatus for automatically recognizing characters colored according to the predetermined code comprise color detecting elements positioned in an array at a reading station for generating output electrical signals representative of the color-sector coding and circuit means coupled to the detection means for translating the color-sector signals into an electrical signal representative of a character in a set.

Abstract: Method and apparatus for maintaining the conductance of liquid crystalline compositions comprising pure transstilbene liquid crystalline materials at a level sufficient to allow dynamic scattering of the composition.

Abstract: A dielectric anisotropic material provided in its optical uniaxial state is caused to alter its optical properties along electrode edges by shorting electrodes, changing potential or otherwise modifying the application of an applied electrical field parallel to the optical axis of the dielectric anisotropic material. Electro-optic cells and imaging systems are disclosed using the edge effect accompanying the modification of the applied electrical field.