International Standard Electric Corporation

Northern Telecom Limited

Stc, Inc

Itt Industries, Inc.

The Secretary of State for Defence in Her Britannic Majesty's Government of the United Kingdom of Great Britain and Northern Ireland

Standard Telephones and Cables Public Limited Company

Standard Telephones & Cables Limited

The Secretary of State for Defence in Her Majesty's Government of the

Screen Technology Limited

William A Crossland

Anthony Bernard Davey

Peter J Ayliffe

Neil Collings

Joseph H Morrissy

David Coates

Peter W Ross

Martin J Birch

Matthew F Bone

Jack R Peters

Vincent Glenn Geake

Ian David Springle

Adrian Paul Sparks

John R Brocklehurst

Paul Andrew Bayley

Barbara Needham

Derek H Mash

Harry J Smith

Arthur Atkinson

Christopher J Walker

David Vass

Frank Astorino

Robert W Scarr

Timothy M Coker

A liquid crystal display of the UV-phosphor type comprises a light source,for producing activation light at a predetermined narrow range of UV wavelengths, a collimator,for directing the activation light in parallel in a predetermined direction, a LC cell,formed from an array of pixels, a photoluminescent screen (,) 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. With the phosphor-emitter configuration, on the other hand, it is ideal, and as a result without loss of contrast a much lower range of drive voltages, and hence a much greater multiplexing capability for passive-matrix displays, can be used while preserving full viewing-angle properties of the display.

Liquid crystal display

A display device includes a shutter layer of liquid-crystal material arranged in cells to shutter input light selectively, a cover layer,on the shutter layer, and a set of phosphors,on the cover layer, corresponding to the cells, to be activated by the input light and provide the display image. To prevent crosstalk the active cell areas,defined by the electrode overlaps are smaller than the corresponding phosphors. This prevents crosstalk between cells even when input light that is not fully collimated is used and also allows space for thicker and/or broader electrodes,leading to the cells, reducing resistance, and for other components such as TFTs.

Liquid crystal cell

Light modulator including a collimator comprising an interference filter

In an active back-plane coordinate addressed liquid crystal cell whose pixels are set into one state by the application of a unidirectional potential across the thickness of the liquid crystal layer, and into the opposite state if the direction of the applied potential is reversed, refreshing is carried out in two sequential stages in order to avoid cumulative charge imbalance effects. In one stage the pixels are set to their required states, whereas in the other stage they are set to the inverse of those states.

Co-ordinate addressing of liquid crystal cells

Telecommunications switch architecture

A smart pixel is comprised by a chiral smectic liquid crystal light modulator (45) (ferro-electric or electroclinic) disposed on a semiconductor substrate and having associated therewith electronic circuitry (41-44) formed in the semiconductor substrate in particular a single crystal silicon VLSI substrate, which circuitry is such as to provide localised intelligence (electrical signal processing and conditioning, pointwise operations, logic functions) at the modulator. The circuitry may comprise photodetector/threshold circuitry (FIG. 7) or digital-to-analogue conversion (FIGS. 3 or 4), for example.

Spatial light modulators

An optical logic device consists of a bistable liquid crystal layer (BOD 1) of the thermally-induced birefringent (TIB) type settable by one or more write beams and rfead by a beam of a different wavelength or different light polarization. Thus the read and write beams are optically decoupled. Two such devices (BOD 1 and BOD 2) in tandem form a 3-input AND gate. Here beams A and B are write beams for the first device, (BOD 1), and beam C is the read beam for the first device. For the second device (BOD 2) the write beams are the output of the first device (BOD 1) and beam D, the read beam being beam E. The two read beams have different wavelengths from the write beam. In a second version, the liquid crystal layer is on the base of a prism via which the beams reads it. Write beams go right through the layer, while a read beam is 'reflected' from the layer but is modulated by the state thereof. This is an OR gate. Logic assemblies can use combinations of such AND or OR gates.

Optical logic device

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.

Ferroelectric liquid crystal cells having a helical liquid crystal

Optical four wave mixing is provided by interfering two waves on a liquid crystal layer (1) temperature stabilized just beneath its nematic/isotropic phase change transition temperature. The liquid crystal incorporates a guest dye to absorb the light producing a holographic thermal image which is accompanied by a holographic phase image. Once this phase image starts to build up it is illuminated with a `third wave` of light that is not absorbed so as to produce the required holographically diffracted `fourth wave`.

Dynamic hologram recording

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.

Two-dimensional optical information processing apparatus

The data processing terminal comprises a smectic liquid crystal flat panel display module (2) which is supported by a support module (1). The terminal also includes a keyboard (4). The display module (2) may be removed from the support module (1) and has its own central processor, memory, control means and power source to enable it to operate independently of the support module, which contains its own central processor, memory, control means, and interface means and is mains operated. The display module may incorporate a touch sensitive overlay to permit the manipulation of the contents of the display. The support unit may incorporate a telephone interface unit.

Data processing terminal having support module and portable display

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.

Laser addressed smectic displays

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.

Ferro-electric liquid crystal display with steady state voltage on front

Growing community of inventors

Harlow, United Kingdom

William A Crossland