Abstract: Integrated control, active matrix display means comprising two groups of row electrodes and two groups of column electrodes per image point and the control process for the same. This means comprises a display material inserted between two walls on the inner faces of which are arranged n parallel row conductors and two groups, each formed from m parallel columns, one of the two groups being raised to reference potential and each row conductor being connected to m switches, themselves connected to two conductor blocks of first and second groups facing column conductors of first and second groups. An image point is defined by the overlap zone of two column conductors and two conductor blocks respectively of a first and second groups.

Abstract: A process for the control of a matrix display such as a liquid crystal display displaying grey levels comprising a display material inserted between m electrode rows and p electrode columns which cross the rows, a material zone M.sub.i N.sub.j being excited by the application to row M.sub.i of a first series of pulse signals and to column N.sub.j of a second series of continuous signals, with i,j being integers such that 1.ltoreq.i.ltoreq.m and 1.ltoreq.j.ltoreq.p, said signals being cyclical of cycle T with polarity reversal at each half-cycle T/2, T/2 being subdivided into n time fractions equal to 2.sup.(k-1) m.tau., in which k is an integer such that 1.ltoreq.k.ltoreq.n and .tau. a time interval useful for exciting the material, the signal of the second series having a maximum of 2 n polarity reversals over a cylcle T and for each time fraction being either in phase, or in phase opposition with the signal of the first series.

Abstract: Each image point X.sub.ij of the matrix screen is defined by the intersection between a control row i having at least one electrode and a control column j having an even number of electrodes. In order to eliminate the coupling between the rows and columns, the voltage signals applied to the electrodes of the same control column cancel one another out in groups of two.

Abstract: Liquid crystal cell having a homeotropic structure, with compensated birefringence for said structure.The cell comprises a liquid crystal layer which can have a hometropic structure and electrodes located on either side of the layer and whereof at least one is transparent. It also comprises means for compensating the birefringence of the liquid crystal layer in its homeotropic structure, so that the cell has a high contrast for said structure, in the case of an oblique observation made in a given observation plane.Application to the construction of data display means.

Abstract: Active matrix display screen without intersections of the addressing row and column conductors.The display screen comprises a material with modifiable optical characteristics placed between a first wall and a second transparent wall. On the first wall is formed a matrix of elements, each comprising a switching element constituted by a thin film transistor and an electrode and on which there is also a group of row conductors. The other wall carries a group of column electrodes and a group of column conductors.Application to liquid crystal display screen.

Abstract: The display comprises a cholesteric liquid crystal film in which are embedded dye molecules between the two walls separated by a shim. One wall is at least partly covered by a reflecting coating reversing the polarization of a circularly polarized electromagnetic wave. The optical anisotropy .DELTA.n and the helix pitch p are such that the least absorbed wave on passing through the cell has an ellipticity equal to or greater than .pi./8.