Abstract: A method of making a multilayer printed circuit upon a single crystal substrate for the mounting thereon of a semiconductor laser and an optical fibre pigtail located in a crystallographically etched groove in the substrate wherein all the photolithographic processing required to create the multilayer printed circuit is performed prior to the etching of the groove.

Abstract: A drive circuit for a liquid crystal display uses a sampling technique to derive drive signals from a pair of input waveforms. The waveforms comprise positive going and negative going trapezoidal pulses. By sampling the waveforms at appropriate points, single cycle AC signals and zero voltage signals can be provided. The technique subjects the drive circuit to a voltage stress that is lower than that provided by conventional techniques.

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 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: In operating a display device incorporating a matrix addressed smectic cell, a strobing pulse is applied to each row electrode in turn while data pulses are applied in parallel to the column electrodes. The data pulse voltage excursion is less than the minimum voltage V.sub.T required to switch the cell. For the entry of complete rows the strobing voltage excursion is made larger than twice V.sub.T for fast data entry. For entry of rows in successive segments (e.g. for single character entry) the strobing voltage is less than twice V.sub.T so that successive strobing pulses applied to a single line may be of longer duration but cannot give rise to spurious switching of unselected pixels.

Abstract: A ferro-electric liquid crystal display in which the individual pixels are addressed via an address matrix that includes one field effect transistor for each pixel, and a plurality of row and column conductors whereby data is written into each pixel to change or to maintain its display condition.

Abstract: A matrix array type liquid crystal device whose liquid crystal layer is ferro-electric is addressed using strobing pulses applied serially to the members of a set of electrodes on one side of the layer while balanced bipolar data pulses are applied in parallel to the members of a set of electrodes on the other side. The data pulses are twice the length of the strobing pulses. This provides a way of minimizing the exposure of the pixels to `wrong` voltages between consecutive addressing that would tend to drive them to their opposite states.

Abstract: A relatively shallow arrangement for providing illumination for a light scattering type display cell employs a transparent sheet in optical contact with the front surface of the cell and a matte black sheet out of contact with the rear surface. The assembly acts as a light guide for light launched into at least one of the transparent sheet from at least one strip lamp. The only light escaping from the display, etc. in the direction of the observer is a proportion of that scattered into non-guided directions by regions of liquid crystal layer selectively set into a scattering state.

Abstract: A coherent light image generator for signal processing such as image correlation directs laser light onto a specularly reflecting matrix addressed dyed nematic liquid crystal display device having a liquid crystal layer sandwiched between a transparent electroded front plate and an active single crystal silicon wafer incorporating NMOS circuitry.

Abstract: A co-ordinate matrix addressing system is used to address a liquid crystal display cell containing a positive dielectric anisotropy smectic material. For this purpose one or more direct voltage pulses are applied across selected elemental volumes of the display to convert them from a focal-conic scattering state to a homeotropically aligned state. Prior to this all elements are electrically driven into the turbulent scattering state which relaxes into the focal-conic scattering state upon removal of the driving field. The driving field may also take the form of direct voltage pulses. Unselected elemental volumes may be refreshed to substantially their original level of focal-conic scattering by means of a suitable blanking potential applied to both selected and unselected elemental volumes which nevertheless leaves previously restored elemental volumes in the homeotropically aligned state.

Abstract: A curtailed drive scheme for a matrix array liquid crystal display cell in which the field developed across each picture element is maintained for only a fraction of the time interval between consecutive addressings. This reduces the effects of differences in time constants across the display for addressing schemes in which the average time constant is short compared with this time interval between consecutive addressings.

Abstract: A co-ordinate matrix addressing system is used to address a liquid crystal display cell containing a positive dielectric anisotropy smectic material. For this purpose one or more direct voltage pulses are applied across selected elemental volumes of the display to convert them from a focal-conic scattering state to a homeotropically aligned state. Prior to this all elements are electrically driven into the turbulent scattering state which relaxes into the focal-conic scattering state upon removal of the driving field. The driving field may also take the form of direct voltage pulses.