Bell Telephone Laboratories

At&t Bell Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

Gary D Boyd

Julian Cheng

Peter Dinh-Tuan Ngo

Robert N Thurston

Larry Allen Coldren

Sigurd Wagner

Benjamin Tell

Ross A Lemons

Robert B Meyer

Joseph P Remeika

Edward G Spencer

Fred Wudl

James C Phillips

Sarat K Mohapatra

Frederick G Storz

Threshold electric fields required to achieve high speed matrix addressing of selected cells in a bistable nematic liquid crystal storage display are reduced by employing a short duration, priming pulse signal in accordance with the principles of the invention. The short priming pulse signal applied to a selected cell modifies the binding energy for disclinations attached to sites of orientational discontinuity, thereby changing the threshold field required for electrical switching between bistable states. Threshold reduction also depends on the AC frequency and duration of a writing pulse signal applied to the selected cell subsequent to the priming pulse signal.

Bistable liquid crystal display utilizing priming voltages

A bistable nematic liquid crystal display cell is switched between topologically equivalent, asymmetric horizontal states. Switching is initiated by application of a directional, symmetry breaking field such as a transverse magnetic field. An electric potential is then applied across the cell to complete the switching cycle and maintain the state. The cell includes upper and lower parallel substrates, upper and lower topographically textured tilt alignment surfaces on the corresponding substrates, and nematic liquid crystal material between the substrates. In an active region of the cell, the tilt alignment surfaces form an equal reverse tilt boundary condition. In an isolation region surrounding the active region of the cell, the tilt alignment surfaces form a parallel tilt boundary condition.

Nematic liquid crystal storage display device

A row and column matrix of strip electrodes is utilized for switching bistable liquid crystal display cells from the vertical state to the horizontal state via resistive heating by applying an electric current of sufficient magnitude and duration to selected electrodes. Resistive heating causes the liquid crystal to undergo a phase transition from the nematic mesophase to an isotropic phase. Extinction of the current permits the liquid crystal to cool preferentially into the horizontal state of the nematic mesophase. Horizontal-to-vertical state switching is performed by conventional electric field effect techniques.

Electrothermal matrix addressable liquid crystal display

An AC plasma panel display (100) is described with selective row and column shifting capability. The column conductors (C.sub.2, C.sub.4 . . . , C.sub.512) are common between a staging area (11) and an exhibiting area (12) while the other column conductors (C.sub.1, C.sub.3 . . . , C.sub.511) are terminated at the boundary between the two areas. The row shifting is accomplished in the staging area to enter display data on the panel. Column shifting is used between the two areas to transport display data onto the exhibiting area from the staging area. The modified display panel requires a minimum number of drivers and intrinsically isolates column and row shifting during operation.

Selective shifting AC plasma panel

A liquid crystal cell having memory is provided by disposing a liquid crystal material having nematic directors between two substrates which are fabricated to contain an array of singular points. The cell may further include means for detaching singularities such as appropriate electrode arrangements. These substrate configurations provide multistable configurations of the director alignments because disclinations must be moved, either through the bulk of the liquid crystal material or on the substrate surfaces to switch between the stable configurations. The switching of the device between stable configurations may be accomplished by the application of electrical fields to the liquid crystal material. The stable configurations may be optically differentiated by the incorporation of pleochroic dyes into the liquid crystal material or by crossed polarizers.

Mechanically multistable liquid crystal cell

An rf sputter etch or reactive sputter etch apparatus which can be used for etching substrates at oblique angles utilizes a cathode formed from a metal grid and an equipotential enclosure. The substrate is supported in the enclosure either parallel to or at an oblique angle to the surface of the grid.

Reactive sputter etching apparatus

Solid state electrochromic devices are fabricated using, as the electrochromic material, ionic conductors such as heteropoly acids. The properties of the ionic conductors permit construction of a device having only two electrodes and the electrochromic material. In operation, low voltages impressed between the electrodes induce a color change. For example, when phosphotungstic acid is employed, the color change is from white to dark blue. Cycle times as low as 100 msec are achievable and the devices exhibit memory properties.

Solid electrochromic devices

Disclosed is an electro-optical device in which color changes are electrically induced in an electrochromic material which is a single or polycrystalline niobium tungstate represented approximately by the formula W.sub.9 Nb.sub.8 O.sub.47. The device comprises an ion source and a source of an electrical field which may be reversible so as to produce coloring and bleaching of the electrochromic material. Due to high corrosion resistance of such material, the ion source may conveniently be a hydrous electrolyte.

Tungsten niobate electrochromic device

Elastic waves are propagated in a waveguide comprising an elongate central core region and an outer cladding region, the cladding region having a larger bulk shear elastic wave velocity than the core region. Transducers at respective ends of the waveguide couple between electrical signals and 'shear' mode elastic waves in which the principal particle displacement is substantially perpendicular to a plane passing through the central longitudinal axis of the core region. The cladding region is sufficiently thick to ensure that the particle displacement profile is substantially zero at its outer surface. The waveguide is mounted in a medium suitable to mechanically support it and to protect it against external mechanical shock.

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Rumson, NJ, United States of America

Gary D Boyd