Thomson-csf

Robert Hehlen

Michel Hareng

Serge Le Berre

Pierre Leclerc

Philippe Marcenac

Jean-Noel Perbet

Bruno Mourey

Serge LeBerre

The invention relates to controlling a matrix access display device comprising a layer of material reacting to a combined thermal and electric effect. According to the invention, the DC video control voltage is transformed into an AC voltage by switching the potentials of the electrodes applying the electric control field.

Process for controlling a matrix access display device

A system for making a device temperature dependent whose operation is dependent on the local heating applied to a thermo-active material layer. The invention uses the heating electrodes of the device as temperature sensors, the information detected by these sensors being stored in a memory and used as bases for establishing the temperature dependence.

System for making a thermo-active device temperature dependent

The invention relates to display devices with a mixed thermal and electrical effect. The invention relates to a special addressing mode making it possible to display a writing line, while limiting the control voltages to be applied from the outside to the display screen.

Thermoelectric effect display device

An image contained in an incident signal is displayed on a screen forming part of a matrix-access display device. The device is primarily applicable to high-definition or small-area screens designed for operation in the transmission mode, and is controlled by an optical system. Optical addressing of a line array and a column array of electrodes is performed by means of light beams which serve to illuminate photodetectors.

Electrooptical switching device

The invention relates to planar display screens and more particularly to smectic liquid crystal screens. One of the problems of high definition display screens (approximately 100 to 1000 lines and columns) is caused by the devices for controlling the heating current on the lines. The complexity of the installation and costs limit the increase in the definition. The invention arranges the N lines of a screen into .sqroot.N groups of lines supplied at each of their ends by .sqroot.N control devices functioning sequentially, i.e. 2.sqroot.N devices in all. Moreover, each line has a diode placed between the heating resistor and the common point of the circuit. Application to the display of images transmitted in the form of a video signal for television and display peripheral equipment in teletransmission.

Control device for a display screen and display screen controlled by

This invention provides a nematic liquid crystal display device for displaying a first information in the absence of any control voltage and substituting for that another information, or successively several other informations, by application of a control voltage. Several embodiments are described, in which either rotatory polarization effect in twisted structures or dynamic scattering effect are used.

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Paris, France

Robert Hehlen