Abstract: The invention relates to a method of patterning a layer formed from a fixable material such as photopolymer on a surface in a desired pattern. The method involves coating selected areas of the substrate with an adhesion promoter and subsequently coating the fixable material. The fixable material is then fixed, for instance by curing by exposure to UV radiation. The adhesion promoter is adapted to have a surface energy which is designed to adhere to the substrate or selected areas thereof and also to the fixed material such that fixed material may be easily removed from areas of the substrate not coated with adhesion promoter but retained in areas where the adhesion promoter has bonded to the substrate.

Abstract: A display system 10 for displaying information at a point of product display in a retail outlet comprising a communicator 12 for transmitting display information to a remote display module 18, the display module 18 being adapted in a first, low power mode to display information and in a second, higher power mode periodically, in a predetermined manner, to communicate with the communicator 12, the system 10 preferably being configured to enable determination of the accuracy and automated correction of the synchronization of a periodic communication between the communicator 12 and the display module 18 while the display module 18 continues to switch between first and second modes of operation enabling a low overall consumption of power by the display module 18 and more preferably wherein the display module 18 is adapted to switch between first and second power modes between receipt of a synchronization signal and a display information signal from the communicator 12.

Abstract: A liquid crystal device comprises a layer (2) of a nematic liquid crystal material contained between two cell walls (3, 4) each carrying electrode structures (6, 7) and an alignment surface (20, 21). The alignment layer (20, 21) on one or both cell wall (4), is formed of a plurality of small (<15 ?m) surface features each separably capable of providing a bistable pretilts and an alignment direction and collectively causing larger variations of molecular orientation across the layer (2). The device may be switched between a light transmissive state and a light non-transmissive state. The small surface features may be areas of grating (21), protrusions (25), or blind holes (26), separated by mono stable flat surfaces (Fm) coated with a homeotropic alignment layer. Preferably, the grating etc provides bistable switching operation between a low surface tilt and high surface tilt, and the low tilt alignment direction varies between adjacent grating areas.

Abstract: This invention relates to a liquid crystal device wherein the surface profile of a surface alignment grating stabilises at least one stable state. The invention involves the introduction or breaks (34, 36, 38) or discontinuities into the grating (10) to divide the grating into a plurality of groove segments. The breaks are discontinuities in the grating in the groove direction, the grating having substantially the same groove direction on each side of the break. The introduction of breaks prevent free movement of defects along the groove of the grating and therefore help to stabilise the desired liquid crystal configuration, either a Defect state or a Continuous state. Suitable breaks involve gaps (34) in the groove ridges (30), necks (36) between the groove ridges (30) and slips or relative displacement (38) of the grating.

Abstract: A device is described that comprises a layer of material (254) disposed between first and second cell walls (250,252) and is capable of adopting, and being electrically latched between, at least two stable configurations. The layer of material (254) comprises one or more separate electrically addressable regions (270, 272, 274, 276) and addressing means are provided to write to each of said electrically addressable regions using voltage pulses to selectively latch said layer of material as required. The addressing means is arranged to write to each of said one or more separate electrically addressable region using at least first and second latching scans.

Abstract: A liquid crystal device is described that comprises a layer of liquid crystal material contained between a first cell wall and a second cell wall. The layer of liquid crystal material being switchable between at least a first state and a second state, said first state and said second state having sufficiently low splay to enable rapid electrical switching therebetween. The internal surface of said first cell wall is arranged to provide two or more surface alignment configurations of different pretilt to said layer of liquid crystal material. Said states may persist in the absence of an applied electric field. In particular, the invention relates to pi-cell devices that allow for rapid switching from the initial splay state to the bend states, and also to bistable or multistable pi-cell devices.

Abstract: This invention relates to a liquid crystal device wherein the surface profile of a surface alignment grating stabilises at least one stable state. The invention involves the introduction or breaks (34, 36, 38) or discontinuities into the grating (10) to divide the grating into a plurality of groove segments. The breaks are discontinuities in the grating in the groove direction, the grating having substantially the same groove direction on each side of the break. The introduction of breaks prevent free movement of defects along the groove of the grating and therefore help to stabilise the desired liquid crystal configuration, either a Defect state or a Continuous state. Suitable breaks involve gaps (34) in the groove ridges (30), necks (36) between the groove ridges (30) and slips or relative displacement (38) of the grating.

Abstract: This invention relates to a liquid crystal device wherein the surface profile of a surface alignment grating stabilizes at least one stable state. The invention involves the introduction or breaks (34, 36, 38) or discontinuities into the grating (10) to divide the grating into a plurality of groove segments. The breaks are discontinuities in the grating in the groove direction, the grating having substantially the same groove direction on each side of the break. The introduction of breaks prevent free movement of defects along the groove of the grating and therefore help to stabilize the desired liquid crystal configuration, either a Defect state or a Continuous state. Suitable breaks involve gaps (34) in the groove ridges (30), necks (36) between the groove ridges (30) and slips or relative displacement (38) of the grating.

Abstract: A method and apparatus for forming a patterned layer having a surface profile that provides relief structures within an electronic device. The method comprises the steps of taking a carrier film (50) having an inverse of the required surface profile formed on one side thereof, taking a layer of fixable material (54) located on a substrate (52), laminating the carrier film (50) and substrate (52) such the carrier film causes the required surface profile to be formed in the layer of fixable material with a predetermined offset, and then fixing the fixable material. Lamination may be performed using rollers (56,58) or a vacuum process. The process is designed to ensure that the offset can be kept as low as possible, preferably to within 150 nm.

Abstract: This invention relates to a liquid crystal device with grey scale. The invention uses dither, either spatial or temporal. For spatial dither the invention arranges so that at least one bit of dither is not a multiple of the size of a smaller bit of dither—in other words there is a fractional weighting. The two bits of dither have the same number of addressable transmission levels and the weighting sacrifices some linearity in exchange for reduction of manufacturing tolerances for the smaller bit. For temporal dither the invention relates to fractional weighting of the duration of the sub-frames.

Abstract: A repeated pattern layer having areas for imparting different electro-optic characteristics to a light modulating device is disclosed. The repeated pattern is arranged so that any pixel area formed in the assembled device (above a certain minimum size) will contain an area of each electo-optic characteristic in the right proportions. The pattern is arranged as a two dimensional grid of areas of different characteristic with at least one area of each characteristic provided in each row and column of the grid. The patterned layer may usefully be an alignment layer for a liquid crystal device, especially a bistable device, and the different areas may be arranged to give grey scale in the device.

Abstract: A liquid crystal device is described that comprises a layer of liquid crystal material contained between a first cell wall and a second cell wall. The layer of liquid crystal material being switchable between at least a first state and a second state, said first state and said second state having sufficiently low splay to enable rapid electrical switching therebetween. The internal surface of said first cell wall is arranged to provide two or more surface alignment configurations of different pretilt to said layer of liquid crystal material. Said states may persist in the absence of an applied electric field. In particular, the invention relates to pi-cell devices that allow for rapid switching from the initial splay state to the bend states, and also to bistable or multistable pi-cell devices.

Abstract: A bistable nematic liquid crystal device cell is provided with a surface alignment grating on at least one cell wall and a surface treatment on the other wall. Such treatment may be a homeotropic alignment or a planar alignment with or without an alignment direction, and zero or a non zero pretilt. The surface profile on the monograting is asymmetric with its groove height to width selected to give approximately equal energy within the nematic material in its two allowed alignment arrangements. The monograting may be formed by a photolithographic process or by embossing of a plastics material. The cell is switched by dc pulses coupling to a flexoelectric coefficient in the material, or by use of a two frequency addressing scheme and a suitable two frequency material. Polarisers either side of the cell distinguish between the two switched states. The cell walls may be rigid or flexible, and are coated with electrode structures, e.g.

Abstract: A method of addressing bistable nematic liquid crystal devices is provided. The method is suitable for implementation using commercially available STN drivers. The method involves applying one of at least two data waveforms simultaneously to each column electrode whilst an active row waveform is applied to an active row and a non active row waveform is applied to all other rows. The resultant waveform at the pixels on the active row comprises a blanking portion sufficient to cause the liquid crystal material to blank, irrespective of which data waveform is applied, immediately followed by a discriminating portion which allows for selective latching depending on the data waveform applied.

Abstract: A device is described that comprises a layer of material (254) disposed between first and second cell walls (250,252) and is capable of adopting, and being electrically latched between, at least two stable configurations. The layer of material (254) comprises one or more separate electrically addressable regions (270, 272, 274, 276) and addressing means are provided to write to each of said electrically addressable regions using voltage pulses to selectively latch said layer of material as required. The addressing means is arranged to write to each of said one or more separate electrically addressable region using at least first and second latching scans.

Abstract: A method of addressing multistable nematic liquid crystal devices, in particular bistable nematic liquid crystal devices is provided. The method is a line at a time addressing scheme where one of at least two data waveforms is applied simultaneously to each of the column electrodes whilst a strobe waveform is applied to a row. The strobe waveform comprises a blanking portion sufficient to cause the liquid crystal material to blank, irrespective of which data waveform is applied, immediately followed by a discriminating portion which is such that in combination with an appropriate data waveform allows for selective latching. At least part of both the blanking portion and the discriminating portion are applied during the line address time for the particular row of interest.

Abstract: Liquid crystal devices are described that exhibit bistable, tri-stable or other multistable operation. The stable liquid crystal configurations are attained using a surface alignment grating (144) on the internal surface of at least one cell wall (142). The surface profile of the surface alignment grating comprises three or more defect sites per grating period and permit the liquid crystal molecules to adopt any one of two or more stable pretilt angles in the same azimuthal plane. Application of a suitable voltage causes the liquid crystal material to switch between the stable configurations.

Abstract: A method of addressing bistable nematic liquid crystal devices is provided. The method is suitable for implementation using commercially available STN drivers. The method involves applying one of at least two data waveforms simultaneously to each column electrode whilst an active row waveform is applied to an active row and a non active row waveform is applied to all other rows. The resultant waveform at the pixels on the active row comprises a blanking portion sufficient to cause the liquid crystal material to blank, irrespective of which data waveform is applied, immediately followed by a discriminating portion which allows for selective latching depending on the data waveform applied.

Abstract: A device is described that comprises a layer of material (254) disposed between first and second cell walls (250, 252) and is capable of adopting, and being electronically latched between, at least two stable configurations. The layer of material (254) comprises one or more separate electrically addressable regions (270, 272, 274, 276) and addressing means are provided to write to each of said electrically addressable regions using voltage pulses to selectively latch said layer of material as required. The addressing means is arranged to write to each of said one or more separate electrically addressable region using at least first and second latching scans.

Abstract: A bistable nematic liquid crystal device is addressed by application of a row waveform to successive row electrodes of an x, y matrix of pixels whilst one of two data waveforms are applied to each column electrode. The row waveform has a period of two or more time slots (ts), with two dc pulses of opposite amplitude for causing a switching to a dark state, and two dc pulses of opposite amplitude for causing a switching to a light state. The data waveforms have the same period as the strobe with dc pulses of opposite amplitude and combine with the strobe pulses to switch the device. The device can be addressed in two field periods, one field switching to a dark state, the other field switching to a light state. Alternatively, the device can be blanked to the dark state then selectively switched to the light state. When blanking is used, the row waveform has blanking de pulses placed a short time before selective switching to reduce overall addressing time.