Siemens Aktiengesellschaft

Martin Bechteler

Hans Krueger

Wolfgang Welsch

Werner Veith

Wolfgang Gross

Rolf Stock

Conventional turnoff power semiconductor devices each comprise a p-n junction blocking in case of turnoff, one zone of which, lying at the p-n junction, has a high doping gradient. But this produces a low dynamic voltage stability characteristic for the power semiconductor device. To increase the dynamic voltage stability characteristic of the power semiconductor device, it is proposed to provide one zone in the form of a region having at least a width of twenty microns viewed from the p-n junction, wherein a maximum doping gradient dN.sub.2 /dx=5.times.10.sup.16 cm.sup.-4 and a predetermined basic dopant concentration is present.

Turn-off power semiconductor component

An electro-optical display device particularly a liquid crystal display device having a pair of carrier plates spaced apart to form a cavity with each of the carrier plates on a surface facing the cavity being provided with an electrically conductive layer covered by a dielectric layer with the device having the medium, which may be the liquid crystal layer and is switchable between two optically different states, disposed in the cavity, characterized by the conductive layer having a thickness d.sub.1 and an index of refraction n.sub.1 and each of the dielectric layers having a thickness d.sub.2 and a refractive index n.sub.2 with the thickness having a range of 0.5 d.sub.1 .ltoreq.d.sub.1 .ltoreq.1.5 d.sub.1 and 0.5 d.sub.2 .ltoreq.d.sub.2 .ltoreq.1.5 d.sub.2, wherein ##EQU1## with .lambda. being the mean free wavelength of the operating light, ##EQU2## with n.sub.o being the index of refraction of the carrier plate and n.sub.3 being the index of refraction of the liquid crystal layer in the idle state.

Electro-optical liquid crystal display device

A device for displaying variable and fixed indicia is provided by liquid crystal cells which give variable as well as fixed information. The variable and fixed information is in the form of alpha and/or numerical characters and/or punctuation characters, such as colons in a digital clock. The fixed characters are formed by members such as spacers which simultaneously space two carrier plates relative to one another as part of a liquid crystal cell. In a preferred embodiment, the display is a so-called twisted nematic display with spacers consisting of a glass solder enriched with a spacer element. The invention may be used in all types of displays having a relatively low tolerance of plate spacing and which contain fixed characters. It is particularly suited for liquid crystal displays in measuring equipment such, for example, as tachometers or watches.

Display device for illustrating variable and fixed information

A gas-discharge display device for multi-colored data display in three basic colors, comprising a gas-filled, gas-tight enclosure, a board-like matrix control structure, dividing the enclosure into two chambers, which is in the form of an insulating plate having a plurality of apertures therethrough, arranged in an array of coordinate lines corresponding in number to a desired number of image points. A plasma electrode is disposed in one chamber and a luminescent screen electrode disposed in the other chamber. The control structure includes a plurality of anode conductors disposed on the side of said plate facing said plasma electrode, and a plurality of control conductors disposed on the side of said plate facing said luminescent screen electrode, with each of the conductors extending around the edges of the associated apertures. The plasma electrode is so disposed that, upon application of appropriate potentials, a gas discharge can burn in the discharge chamber, while the luminescent screen electrode is disposed sufficiently close to the adjacent conductors on the matrix member that even a few kV applied to such screen electrode cannot trigger any undesired gas discharge. The anode conductors each contain a corresponding line of apertures with each three successive apertures being allotted to the three basic colors, and each third aperture being allotted to the same basic color. Each control conductor interconnects each successive aperture along the line in which such conductor extends, and each of the latter may include apertures allotted to two of the three basic colors.

Matrix-addressed gas-discharge display device for multi-colored data

An electron-optical system with a magnetic focusing and an electromagnetic deflection system of unit design in which a screening means in the form of a coil of magnetic wire or other conventional structure is arranged between the magnetic and electromagnetic units is employed in tubes, in particular high-resolution television camera tubes such as vidicons or the like, having a target for scanning by an electron beam and a fine-mesh field net arranged in front of the target. The focusing coil has an increasing winding density in the direction from the aperture diaphragm toward the target, and the deflection coils are of such short length and arranged either inside or outside of the focusing coil so that, in association with the increasing focusing field strength toward the target due to the use of a deflection field of less than about half the usual extent in the axial direction, the electron beam experiences a rotation of less than 90.degree. in the deflection field while achieving magnification less than unity with low beam landing errors. The focusing coil has an internal and/or external diameter which increases in steps toward the target.

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Kirchheim, Germany

Martin Bechteler