Abstract: This keypad for the input of control commands comprises a membrane keypad, a carrier, a keypad base and a key module. The switching operation, initiated by keys, takes place in a closed unit in the form of a carrier which encloses the keypad base and the membrane keypad. The switching contacts are located within the membrane keypad which is sealed against moisture, whereby the actual performance of the switching command take place within the sealed membrane keypad, switching plungers of the keypad base having only an actuating function. The sealed unit in the form of the carrier considerably eases installation in that the keypad base and the membrane keypad can be pre-installed in the carrier at the factory the key module can be placed over them at the installation site.

Abstract: A fibre-optic sensor for measuring a particular directional component of an electric field comprises a piezoelectric body (4) and a glass fiber (5a) which is rigidly connected to the piezoelectric body (4) in a given length section. A crystal class and a crystallographic orientation of the piezoelectric body (4) is selected in such a manner that only the directional component which is parallel to a given body axis (h) of the piezoelectric body (4) causes a change in a length of the glass fiber (a) by means of an inverse piezoelectric effect. The change in length is measured interferometrically. In a preferred embodiment, the piezoelectric body has the shape of a disk, of a plate or of a hollow cylinder.

Abstract: A pyrometric temperature measuring instrument including at least one optical wave guide (1a) with a core (5) and a cladding (6), a light detector (3) and at least one pyrometric sensor (2a). The at least one optical wave guide (1a) has a large numerical aperture. The pyrometric sensor (2a) is located at one end of the at least one optical wave guide (1a) and covers at least a cross-section of the core (5) of an optical wave guide (1a). In a preferred embodiment, the light detector (3) is an InGaAs photodiode. The optical wave guide (1a) has a numerical aperture of 0.3 or more, a diameter of the core (5) of approximately 100 .mu.m or more, and is surrounded by a light-tight cover (7).

Abstract: In a process for the sampling of an electric signal changing over time, an electron beam (12) is deflected laterally and linearly over time and at the same time modulated in its intensity according to the instantaneous amplitude of the electric signal. The electron beam (12) generates on a fluorescent screen (14) a brightness-modulated bar of light, which is preferably sampled with a sensor (15) arranged ahead of the fluorescent screen (14) in the form of a CCD line camera having a linear array of sensor elements (15a, b, c).The read-out analog sampled values of the sensor (15) are subsequently digitized and further processed.The advantage of the process is its high broad-bandedness and resolution and the capability of being able to carry out an averaging without additional expenditure of time.

Abstract: An optoelectronic displacement sensor for the absolute measurement of displacement in the sub-micrometer range is described, which is constructed, according to an exemplary embodiment, with a light-emitting diode (L) as light source and two photodiodes (D1, D2), which are arranged in a difference circuit and which are opposite to one another, as radiation sensors. The sensing of displacement takes place by means of a diaphragm (2), which is displaceable between light source and radiation sensors and which influences the illumination received by of the photodiodes (D1, D2). For the homogenization of the illumination, special means are provided, which, according to an exemplary embodiment, consist of a correction filter (6) disposed in the beam path.

Abstract: A process and apparatus for the production of an orientation layer on a plane surface of a plate, and a liquid crystal substrate plate produced thereby. By the process of evaporation from a source, orientation layers are deposited on the plane surfaces of a plurality of liquid crystal substrate plates used for application in liquid crystal displays. To obtain a uniform orientation of the optic axis of the liquid crystal with regard to the azimuthal alignment by means of the preferred direction caused by the orientation layer on the surface, the plates are moved in a direction crosswise to the evaporation direction during the evaporation process. The field of the particle stream emanating from the source is limited by an aperture in an aperture screen which is introduced between the source and the plates. The plates pass completely through the particle stream during the course of the evaporation operation. The finished plates include an approximately 5 nm thick orientation layer.

Abstract: A liquid crystal display based on the bistability effect, wherein the distance between the support plates is smaller than 10 .mu.m and the total twist of the liquid crystal is between 180.degree. and 360.degree., preferably about 270.degree.. Over the entire viewing area of the display, randomly distributed spacers are provided. Because of these measures, the range of the bistable action is so narrowed that the display can be driven with operating voltages outside this range, using conventional multiplexing techniques. A high degree of multiplexing with short switching times and excellent contrast is obtained. The range of viewing angles is very large and independent of the direction of illumination.

Abstract: A liquid crystal display cell including a liquid crystal layer contained between two plane-parallel support plates provided with electrode layers on their mutually inward facing surfaces as well as a border. The support plates are held apart within a predetermined separation range by means of spacers. Those spacers distributed in the border are electrically conductive and serve as contact bridges between through-contact points on the support plates. Rubber-like elastic particles, e.g. from a silicone elastomer, are used as spacers to prevent low pressure bubbles in the liquid crystal layer at temperatures of -30.degree. C. as well as to prevent loss of contact between the through-contact points. The rubber-like elastic particles, between the through-contact points are electrically conductive.

Abstract: An addressing method for a multiplexable, bistable liquid crystal display wherein a first driving voltage which is larger than a first limiting voltage is applied to the selected display elements and a second driving voltage which is smaller than a second limiting voltage is applied to the non-selected display elements. For the first driving voltage only a first optical state is stable, and for the second driving voltage only a second optical state is stable. All the display elements are simultaneously switched on the display by means of a single writing voltage pulse. By this means a high-contrast, constant and immediate display is achieved over the entire active area. Row-at-a-time writing is also possible. Moreover, a liquid crystal display is introduced which is based upon the bistability effect and which employs a guest-host liquid crystal containing a chiral additive. The layer thickness of the liquid crystal is less than 10 .mu.

Abstract: Nematic liquid crystal display is provided with front side polarizer (13) and homeotropic orientation in the non-field state. The nematic liquid crystal (6) has a negative dielectric anisotropy.The display cell has an internal reflector (11) consisting of an insulating oxide layer with built-in aluminum flakes and a front side polarizer (8, 13). This display provides a reflection display with no back lighting.

Abstract: A fluid crystal display cell (1) which has 2 cell plates coated with electrodes (14, 15) which include a fluid crystal mass (5). The first cell plate (1) is transparent and the second cell plate (2) is equipped with an adhesive cell interior reflector layer (9), at least in some regions, which contain the flake-like aluminum particles (6) as reflector particles and a bonding phase for this. The bonding phase is a practically homogeneous, transparent layered mineral matrix (7), consisting almost primarily of SiO.sub.2, in which the aluminum particles (6) are imbedded.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A sealing cement which is useful for bonding together mutually aligned glass plates of a liquid crystal display cell, the improvement which comprises incorporating into said cement a particulate filler of variably sized particles, wherein the shortest distance between parallel tangential planes of each particle is substantially the same for a substantial majority of said particles and the shortest distance between parallel tangential planes for the remainder of said particles is less than said shortest distance between parallel tangential planes of said substantial majority of particles, whereby the spacing between said glass plates being bonded is determined by said shortest distance of said substantial majority of particles.

Abstract: A process for the manufacture of an electrooptical display device including a circuit board and a liquid crystal display cell mounted on the circuit board, including forming a circuit board having at least one light conducting region; disposing the liquid crystal display cell adjacent the light conducting region of the circuit board; locating at least one light emitting element in the circuit board for illuminating the light conducting region; and attaching a semi-transparent reflector to the liquid crystal cell; wherein at least part of the circuit board is manufactured by combining a reflecting layer, which is produced by the deposition of a reflective material on a substrate or on one side of a mesh, with a light diffusing substance, by embedding these two materials together in a transparent polyester or epoxy resin.

Abstract: A liquid crystal display, and process of manufacture therefor, emloying an integrated reflector internal to the liquid crystal cell, and consisting of a guest-host liquid crystal layer sandwiched between two cell plates and located between front and rear electrodes. At least the front electrode is composed of segments and parts of the reflector and/or rear electrode that lie opposite the conduction paths leading to these segments are at an electrical potential whose difference from the potential of the conduction paths is smaller than the threshold voltage of the liquid crystal layer used.

Abstract: A liquid crystal display for reflection operation with a guest-host liquid crystal layer disposed between two cell plates and respective front and rear electrodes, and with a diffusely divergent reflector integrated in the interior of the cell, at least the front side of the cell plate and the front electrode being transparent. The rear electrode and its supply comprise thick layers, and the reflector consists of metal parts insulated against one another and applied to the rear electrode and to the inner surface of the rear cell plate.

Abstract: An instrument having a liquid crystal display disposed behind a glass cover and separated from the cover by a hollow space. The hollow space is filled with an immersion medium to which is added a substance imparting thixotropic properties to the immersion medium. The added substance has a refractive index comparable to that of the immersion medium.

Abstract: An electrooptic display device which can be operated either in the transmission or reflection mode. The display device consists of a liquid crystal display cell and a semitransparent reflector located in or on a circuit board having a light emitting element disposed therein and characterized by at least one light conducting region.