Bbc Brown, Boveri & Company, Limited

Allan R Kmetz

Meinolph Kaufmann

Klaus Muller

Terry J Scheffer

Peter J Wild

Ernst Gloor

A liquid crystal display including a cell which consists of two cell plates and a liquid crystal with positive dielectric anisotropy layered between the plates, where the molecules of the liquid crystal next to the plates exhibit preferred directions rotated by 90.degree.. The display includes only one polarizer that is placed on the front cell plate. A reflector formed of a layer of insulated metal particles is located inside the cell on the rear plate and exhibits a structure determining the preferred direction of the liquid crystal molecules. The electrode segments are holohedral and the operating voltage applied thereto lies between 1.3 and 2.5 times the Freedricksz threshold voltage.

Liquid crystal display and method of making

An electro-optical display composed of two plates which enclose a display medium and a reflector located on the rear plate. The reflector consists of a thermoplastic material and consists of reflecting surface strips, inclined to the display plane, which reflect incident light beams into the eye of an observer. The surface strips which can be semi-transparent and/or diffusely reflecting are inclined with respect to the display plane at an angle .alpha. and extend rectilinearly in at most two different directions over the surface of the reflector. The angle of inclination .alpha. is either the same for all surface strips and has a value of between 20.degree. and 40.degree., or decreases progressively from an outermost surface strip to the subsequent surface strip. The reflector strips are produced by milling, embossing or injection molding of a suitable thermoplastic material.

Electro-optical display having an improved reflector and method of making

An electro-optical display for the display of dark symbols against a bright background, wherein except for fine separation lines the front and rear cell plates are almost entirely covered with isolated electrode elements. The regions of overlap between these various front and rear electrode elements define the areas of the selectable display segments. The display employs an electro-optic media requiring no polarizers, for example, cholesteric liquid crystals to which has been added pleochroic dyes, or electrophoretic suspensions. The display device is addressed through the application of appropriate signals to the electrodes so that a vanishingly small potential difference lies across the liquid crystal layer in the region of the selected display segments which remain dark. In all the other regions of the display, however, there exists a potential difference which is larger than the transition voltage of the electro-optical medium, and these regions therefore appear as a bright background. The addressing is preferably carried out using unipolar pulsed signals which are applied to the electrode elements of the front and rear cell plates, with those electrodes corresponding to optically selected display segments receiving signals having the same phase and amplitude.

Electro-optical device for the display of dark symbols composed of

A display device including a plurality of adjoining display elements which comprise front and rear electrodes. The display elements are disposed geometrically in at least one row and are electrically grouped together to form at least one matrix. The display device further includes a drive circuit which drives the display elements in such a manner that along each row there is at most one transition from a first optical condition to a second optical condition different from the first.

Display device having adjoining display elements, and a method of

A procedure for the display of measured quantities as a bargraph with the help of a row of addressable display elements, whereby the display elements are interconnected on one side into contiguous groups and on the other side according to like position within each group. Either the on-groups, in which all display elements are to be excited, or the mixed group, in which only a part of the display elements are to be excited, are addressed in a rapid alteration imperceptible to the eye of the beholder. The amplitude of the driving voltage across display elements in the mixed group is zero during the strobe interval for the on-groups.

Procedure of bargraph display for measured quantities

A procedure for the addressing of visual display devices comprising stylized alphanumeric characters which consist of similarly shaped front and rear display elements, whereby in the case of simultaneous selection of a front and the corresponding rear display elements, an optical activation of these elements results such that by coincident selection of the front and rear display elements of several pairs of elements having a specific geometrical configuration a corresponding alphanumeric character becomes visible, whereby further the number of address leads and drivers is reduced by interconnecting the display elements as a matrix and by time-sharing the address leads through multiplexed operation in such a way that the address leads in one matrix dimension are used to select the front elements of the display and the address lines in the second matrix dimension are used to select the rear elements of the display and the address leads in one of these matrix dimensions extend over more than one character.

Procedure for addressing of visual display devices

An electro-optical display device and a method of manufacturing it are disclosed. The display device includes a liquid crystal cell arranged between two polarizers. A light source is positioned adjacent one polarizer on the side thereof remote from the liquid crystal cell, and an electronic control device is coupled to the liquid crystal cell. A diaphragm is arranged on one side of the liquid crystal cell in the form of an aperture for limiting the display field of the liquid crystal. The device limits viewing parallax and improves contrast for both day and night viewing.

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Nussbaumen, Switzerland

Allan R Kmetz