Abstract: A display (50) with enhanced image contrast contains an image-producing component (60) and a set of shutter strips (80). The image-producing component, typically a flat-panel device, has multiple imaging lines that provide light to produce an image. Each shutter strip is situated in front of one or more associated imaging lines. By appropriately switching the shutter strips between light-absorptive and light-transmissive states, the image contrast is enhanced. The shutter strips are typically implemented with a liquid-crystal display structure. The switching of the shutter strips is typically performed with a control component (52/76) which utilizes light to control the shutter switching and which is synchronized to signals (90 or/and 100) that control the imaging lines.

Abstract: A liquid crystal display of the UV-phosphor type comprises a light source 1 for producing activation light at a predetermined narrow range of UV wavelengths, a collimator 3 for directing the activation light in parallel in a predetermined direction, a LC cell 5 formed from an array of pixels, a photoluminescent screen (7) on the cell arranged to emit a visible output when struck by the narrow-band excitation light passing through the cell, and a drive circuit for addressing the LC cell in a multiplexed manner. The direction of the light and the thickness of the cell are chosen to give the best contrast ratio for the liquid crystal. Such an effect is only possible when monochromatic, collimated light is used, which for a normal display is not practical.

Abstract: A display makes use of circularly polarised activation light; to this end it comprises a liquid crystal cell (7) acting as a half-wave plate so as to reverse the handedness of incident light in one setting and not to affect the handedness in another, and a filter (9) such as a cholesteric mirror for passing only that part of the light from the liquid crystal that has a predetermined handedness. When the light is passed by the filter (9), it strikes a photoluminescent screen (12), causing it to emit visible light for the display. The nematic cell is easy to produce and to switch, and the display does not need polarisers.

Abstract: A collimator is formed of a stack of layers (11) of different thicknesses in a way analogous to a low-pass interference filter. When illuminated by narrow-band light of a predetermined wavelength just within the pass band of the filter, the collimator preferentially transmits light incident within a predetermined angular range, usually near-normal. The collimator is especially useful with photoluminescent liquid-crystal display, having phosphor emitters (17), because the collimator layers can simply be deposited on one face of the liquid-crystal modulator (1).

Abstract: Relaxation effects of a uniform mode ferroelectric liquid crystal cell with obliquely evaporated alignment layers, characterized by the reduction in apparent tilt angle consequent upon removal of a switching stimulus, are eliminated by a poling treatment that typically comprises the application of a relatively low frequency (c. 500 Hz) relatively large amplitude (c. 60 volts peak-to-peak) electric potential difference across the thickness of the liquid crystal layer.

Abstract: Bistable switching between clear and scattering states is provided by a liquid crystal cell whose liquid crystal layer is constituted by a random orientation planar aligned ferroelectric smectic exhibiting a pitch length comparable with the wavelength of visible light.

Abstract: Liquid crystal compositions comprising as a first part between 40 and 99% by weight in aggregate of one or more materials selected from one or more of the six compound classes (1) to (3'), wherein R is in every instance an alkyl chain containing between 2 and 18 carbon atoms and R' is in every instance an alkyl chain containing between 1 and 17 carbon atoms, wherein one or more non-adjacent CH.sub.2 -groups are replaced by oxygen atoms, and as a second part between 1 and 60% by weight of one or more materials of high birefringence and high positive dielectric anisotropy which raise the S.sub.A -N transition temperature, exhibit a smectic A phase of relatively low melting point and wide smectic range. Such compositions may be used in liquid crystal cells, not only in display or optical information processing applications, but also for instance in temperature sensing applications. The operation of such cells may involve laser addressing, thermal or electrical addressing.

Abstract: Bistable operation of ferroelectric liquid crystal smectic I* or smectic F* display cells is disclosed which uses a greater liquid crystal layer thickness than is achievable with smectic C* material while yet retaining bistability of operation.

Abstract: A method of addressing a matrix addressed ferroelectric liquid crystal cell is described that uses parallel entry of balanced bipolar data pulses on one set of electrodes to co-operate with serial entry of unipolar strobe pulses on the other set of electrodes. Data entry is preceded with blanking (erasing) pulses applied to the strobe lines. The polarity of the strobing and blanking pulses is periodically reversed to maintain charge balance in the long term.

Abstract: Bistable operation of ferroelectric liquid crystal smectic I* or smectic F* cells is disclosed which uses a greater liquid crystal layer thickness than is achievable with smectic C* material while yet retaining bistability of operation. One or more such cells are employed in two-dimensional information processing apparatus.

Abstract: A method of addressing a matrix addressed ferroelectric liquid crystal cell is described that uses parallel entry of balanced bipolar data pulses on one set of electrodes to co-operate with serial entry of unipolar strobe pulses on the other set of electrodes. Data entry is preceded with blanking (erasing) pulses applied to the strobe lines. The polarity of the strobing and blanking pulses is periodically reversed to maintain charge balance in the long term.

Abstract: A laser beam addressed smectic display in which the laser beam is used to write clear tracks in an optically scattering field employs an anisotropic conductivity dopant in the liquid crystal filling so that the cell can be electrically set into the scattering state by means of dynamic scattering effects. This requires the use of a laser light absorbing dye that is not only photochemically stable, but also stable against the effects of the relatively high fields and currents present when the cell is being set into the scattering state.