Abstract: The present invention is directed to a cholesteric liquid crystal display that includes a homogeneous alignment surface effective to provide increased brightness, low focal conic reflectance and/or reflected light treat is to a significant degree circularly polarized. The homogeneous alignment surface substantially homogeneously aligns the liquid crystal director adjacent thereto. The homogeneous alignment surface may be disposed on one or both sides of a cell of the display. In the case of a cell in which the homogeneous alignment surface is disposed on only one side, the substrate with the inhomogeneous alignment surface may be upstream or downstream of the substrate with the homogeneous alignment surface relative to a direction of incident light. Also included especially in the case of a cell that has the homogeneous alignment surface on both sides is the use of a polarizer to provide very good brightness and low focal conic reflectance.

Abstract: The present invention is directed to a cholesteric liquid crystal display that includes a homogeneous alignment surface effective to provide increased brightness, low focal conic reflectance and/or reflected light that is to a significant degree circularly polarized. The homogeneous alignment surface substantially homogeneously aligns the liquid crystal director adjacent thereto. The homogeneous alignment surface may be disposed on one or both sides of a cell of the display. In the case of a cell in which the homogeneous alignment surface is disposed on only one side, the substrate with the inhomogeneous alignment surface may be upstream or downstream of the substrate with the homogeneous alignment surface relative to a direction of incident light. Also included especially in the case of a cell that has the homogeneous alignment surface on both sides is the use of a polarizer to provide very good brightness and low focal conic reflectance.

Abstract: A method of addressing a bistable liquid crystal material having incremental reflectance properties disposed between opposed substrates is disclosed. One substrate has a first plurality of electrodes deposited thereon facing a second substrate which has a second plurality of electrodes disposed thereon. The intersection of the first and second plurality of electrodes forms a plurality of pixels. The addressing method includes applying a predetermined number of pulses to the first plurality of electrodes, and applying a like number of the predetermined number of pulses to the second plurality of electrodes. Each of the predetermined number of pulses has a different frequency, wherein the predetermined number of pulses are applied in a set time period.

Abstract: The present invention is directed to a cholesteric liquid crystal display that includes a homogeneous alignment surface effective to provide increased brightness, low focal conic reflectance and/or reflected light that is to a significant degree circularly polarized. The homogeneous alignment surface substantially homogeneously aligns the liquid crystal director adjacent thereto. The homogeneous alignment surface may be disposed on one or both sides of a cell of the display. In the case of a cell in which the homogeneous alignment surface is disposed on only one side, the substrate with the inhomogeneous alignment surface may be upstream or downstream of the substrate with the homogeneous alignment surface relative to a direction of incident light. Also included especially in the case of a cell that has the homogeneous alignment surface on both sides is the use of a polarizer to provide very good brightness and low focal conic reflectance.

Abstract: A liquid crystal display device includes cell wall structure and a chiral nematic liquid crystal material. The cell wall structure and the liquid crystal cooperate to form focal conic and twisted planar textures that are stable in the absence of a field. A device applies an electric field to the liquid crystal for transforming at least a portion of the material to at least one of the focal conic and twisted planar textures. The liquid crystal material has a pitch length effective to reflect radiation having a wavelength in both the visible and the infrared ranges of the electromagnetic spectrum at intensity that is sufficient for viewing by an observer. One liquid crystal material may be disposed in a single region or two or more liquid crystal materials may be used, each in separate regions even without the infrared reflecting layer. One aspect of the invention is directed to a photolithography method for patterning a substrate of the display.

Abstract: A liquid crystal material for a display device includes a liquid crystal material comprising first chiral nematic liquid crystal component and a second component that exhibits no liquid crystalline phase. The second component is present in an amount not greater than 5% by weight based upon the total weight of the liquid crystal display material and is effective to avoid image sticking of the display device when in use. The liquid crystal material has positive dielectric anisotropy. The second component may have a molecular weight not exceeding 205 grams/mole.

Abstract: An operating method for a color display system including an active matrix bistable liquid crystal display (LCD) having a plurality of pixels arranged in a matrix based on color data and status bits corresponding to each of the pixels stored in a memory includes steps for generating voltage data corresponding to the pixels based on the color data and the status bits stored for each of the pixels, converting the voltage data to drive signals suitable for driving the active matrix bistable LCD, and applying the drive signals to the active matrix bistable LCD. In an exemplary embodiment, the active matrix bistable LCD is a Cholesteric LCD. Advantageously, the generating, converting, and applying steps are repeated for a corresponding pixel N times, where N is an integer established by the status bits.

Abstract: A low power color display system includes a memory which, stores color data and status bits corresponding to a plurality of pixels, status logic, which generates the status bits responsive to receipt of color data for a respective one of the pixels, a data generator, which generates voltage data corresponding to the pixels based on the color data and the status bits for each of the pixels, driver circuitry, which generates voltage signals responsive to receipt of the voltage data for each of the pixels, and a bistable liquid crystal display (LCD) having multiple cells arranged in a matrix, each cell corresponding to a pixel, the LCD being responsive to the voltage signals. Preferably, the system also includes a power supply which provides power to the driver circuitry, and a power manager, the latter turning the power supply ON when the data generator is in the first operating mode and turning the power supply OFF when the data generator is in the second operating mode.

Abstract: A graphics controller for a color display system having a bistable liquid crystal display (LCD) for displaying a plurality of pixels arranged in a matrix includes a memory device for storing color data and status bits corresponding to each of the pixels, and a generating device for generating voltage data corresponding to the pixels based on the color data and the status bits for each of the pixels. In an exemplary case, the bistable LCD is a Cholesteric LCD. Preferably, the generating device has a first mode of operation in which the data corresponding to the pixels is generated for each corresponding pixel and a second mode of operation in which no data is generated; the generating device switches from the first operating mode to the second operating mode when all of the status bits for all of the pixels are zeros.

Abstract: A series of drive schemes are used to apply a single phase of at least one voltage pulse to drive a display with a bistable cholesteric liquid crystal material to a gray scale reflectance. Each drive scheme takes into consideration the initial texture of the cholesteric material and the range of voltages that may be applied between maximum and minimum reflectance of the material. Application of the single phase can be implemented by either time modulation or amplitude modulation.

Abstract: A flat-panel liquid crystal display having unipolar drive circuitry. The display includes a flat sheet of bistable chiral nematic liquid crystal material activated by a drive circuit that individually controls the display state of multiple picture elements at a refresh rate 1000 scan lines per second. The driver circuitry activates the liquid crystal domains into homeotropic states over a relatively long activation period and then, during a short (˜1 msec.) selection period, either keeps the domains in a homeotropic state or initiate a transition to the transient twisted planar state. The drivers then activate the domains in an evolution phase to provide either focal conic or twisted planar end states across the two-dimensional array of picture elements. The drive circuitry includes a plurality of unipolar display drivers which generate substantially square wave, unipolar waveforms which are applied to row and column electro segments.

Abstract: A flat-panel liquid crystal display. The display includes a flat sheet of bistable chiral nematic liquid crystal material activated by a drive circuit that individually controls the display state of multiple picture elements. The driver circuitry activates the liquid crystal domains with various drive schemes which have any number of different phases to attain various addressing sequence times. At the end of each drive scheme, the texture of the liquid crystal material is allowed to provide either focal conic or twisted planar end states across the two-dimensional array of picture elements. Each drive scheme employs at least a preparation phase and a selection phase to predispose the liquid crystal material to one of the end states.

Abstract: A liquid crystal display including driver circuitry which applies a series of voltage pulses at a frequency of approximately 60 Hz. to cumulatively change a reflectance state of a pixel in an array of pixels at a near video updating rate. The display includes a near video rate updating portion, while the remainder of the display has a slower updating frequency or rate. The display is comprised of a bistable cholesteric liquid crystal material sandwiched between an electrode array having a plurality of row and column electrodes. In one operating embodiment, the driver circuitry generates a unipolar row and column waveforms, the row waveforms being applied to the row electrodes and the column waveforms being applied to the column electrodes of the near video rate updating portion. Approximately every 16 milliseconds, a pixel in the near video rate updating portion receives a control voltage pulse corresponding to the difference between the row and column waveforms.

Abstract: A liquid crystal display device includes cell wall structure and a chiral nematic liquid crystal material. The cell wall structure and the liquid crystal cooperate to form focal conic and twisted planar textures that are stable in the absence of a field. A device applies an electric field to the liquid crystal for transforming at least a portion of the material to at least one of the focal conic and twisted planar textures. The liquid crystal material has a pitch length effective to reflect radiation having a wavelength in both the visible and the infrared ranges of the electromagnetic spectrum at intensity that is sufficient for viewing by an observer. One liquid crystal material may be disposed in a single region or two liquid crystal materials may be used, each in separate regions. One aspect of the invention is directed to a photolithography method for patterning a substrate of the display. The display may also have multicolor capabilities by including at least two materials that reflect visible light.

Abstract: A flat-panel liquid crystal display. The display includes a flat sheet of bistable chiral nematic liquid crystal material activated by a drive circuit that individually controls the display state of multiple picture elements at a refresh rate 1000 scan lines per second. The driver circuitry activates the liquid crystal domains into homeotropic states over a relatively long activation period and then, during a short (.about.1 msec.) selection period, either keeps the domains in a homeotropic state or initiate a transition to the transient twisted planar state. The drivers then activate the domains in an evolution phase to provide either focal conic or twisted planar end states across the two-dimensional array of picture elements.