U.S. Philips Corporation

Antonius G Verhulst

Jacob Bruinink

Johannes A Van Haaren

Wilbert J Hartmann

Willem Frederik Druyvesteyn

Frederik Ate De Jonge

Hendrik Veenvliet

Antonius H Raaymakers

Emanuel J Lenders

Jan Haisma

Leonard J Esser

Ulrich E Enz

Evert H Dekker

Robert A Hartman

Franciscus Antonius Kuijpers

Franciscus Johannes Stommels

Willem Frederik Druijvesteijn

Ann M Luyckx-Smolders

Franciscus J Blommaert

In Deformed Helix Ferro-electric liquid crystal display devices (DHFLCDs) the memory effect in video applications is interrupted by adapting the data voltages of matrix displays based on MIMs or TFTs, dependent on the data in a previous frame, so that the polarization within a cell always switches to a fixed value (zero). In other types of displays (based on diodes) or for less rapid applications, the polarization can also be readily set at this value.

Liquid crystal display device including drive circuit for predetermining

In liquid crystal display devices based on smectic LC material having a high polarization (Deformed Helix FLC, twisted FLC, monostable FLC, electroclinic smectic A LC and antiferroelectric LC), the memory effect in, for example, monitor or video applications is eliminated by presenting compensation voltages in matrix displays based on MIMs, TFTs or diodes, dependent on the data in a previous frame, so that the polarization within a cell always switches to the correct value.

Liquid crystal display device with control circuit

Color display device for projection of the type comprising a light-switching device, for example a device illuminated by successive light strips of different colors (sequential color single panel projector) in which a display device with a matrix of pixels driven by active switching elements is advantageously used for the light-switching device (based on, for example ferro-electric liquid crystal material), the drive being chosen to be such that there is no memory action to a subsequent sub-frame. Due to the voltage-independent capacitance, notably of ferro-electric pixels, a simple drive mode can be used in which a simple correction for possible capacitive effects is sufficient. Notably in a two-pole drive mode, use can be made of the relatively longer time available for (optical) reset. A combination of the two types of drive mode is possible. Compensation of DC effects within a small part of the frame period is also possible without affecting the contrast.

Display device

In a ferro-electric liquid crystal display, in which the pixels in one row first receive a reset or 'blanking' signal, this reset signal is presented by providing the counter electrode, prior to selection, with a reset voltage while simultaneously selecting the row of pixels to be reset. When a single counter electrode is used, it switches to a reset voltage during each selection period. If the counter electrode is divided into sub-strips, these strips switch to a reset voltage once per picture period.

The time it takes for a liquid crystal display device picture to become homogeneous can be reduced to an acceptable extent by a suitable choice of the resistance and the capacitance of the orienting layers with respect to those of the liquid crystal layer. Possible DC voltages, which may occur in the case of a reset drive mode, can thus be rapidly eliminated.

An electro-optic display device with grey scale set by areas of crossing electrodes. In one embodiment, there are 3 strip-shaped sub electrodes with a width relationship of 4:2:1, and two strip shaped column electrodes with a relationship of 8:1. In a second embodiment, there are 4 strip-shaped sub electrodes with a width relationship of 8:4:2:1, and two strip shaped column electrodes with a relationship of 16:1.

Display device with crossing electrodes with specific ratio for gray

In a bistable switching display device the occurrence of artefacts due to considerable changes of periodicity between successive grey scale stages is reduced by a suitable subdivision of the electrodes (112). To this end a drive unit (116) allocates fewer than 2.sup.n grey scale stages to each pixel (113) which is subdivided into n sub-pixels (113.sup.a, 113.sup.b, 113.sup.c). The change of periodicity will decrease when a suitable division of the surface ratios and drive sequence are chosen.

Electro-optical display device with sub-electrodes

An LCD device in which the pixels are divided into sub-pixels composed of one analog adjustable sub-pixel and a plurality of digitally controlled other sub-pixels. By combining a discrete adjustment of the (sub)-transmission levels of the other sub-pixels with an analog adjustment of transmission levels of the one sub-pixel, the total number of light transmission levels is increased considerably. The analog adjustment thus is less critical because the greater part of the ultimate level is defined by the accurate discrete adjustment.

Electro-optic display device with increased number of transmission levels

A liquid crystal device incorporating ferroelectric liquid crystal medium having smectic layers between two supporting plates provided with electrodes, the smectic layers exhibiting a spread of angles with respect to at least one of the supporting plates, whereby a gradual transmission/voltage characteristic is achieved. The spread of angles can be obtained by any of several techniques, such as subjecting the device to a low frequency electric field, or a local thermal, mechanical, chemical or magnetic treatment.

Ferroelectric liquid crystal display having a spread of angles for

For stereoscopic display arbitrarily formed sub-pictures (for example divided into columns) are mixed. This is possible by covering a light-sensitive pick-up unit (CCD) (23) on which the sub-pictures are projected with an LCD (21) in such a way that a 1:1 relation is created between pixels and storage elements. A polarizer (22) arranged between the pick-up unit (23) and the liquid crystal (21) passes sub-pictures determined by electrodes (26, 27), which sub-pictures are read by the pick-up unit. On the display side the sub-pictures are read via an LCD (36) and combined in an analogous manner to a (stereoscopic) overall picture.

Display and pick-up device for stereoscopic picture display

An electroscopic fluid display comprises substrates (1, 2) having fixed electrodes (12, 22), and movable electrodes (3) between the substrates, the electrodes (12, 22, 3) being provided on the free main surfaces with an insulating layer (13, 23, 31, 32) respectively, and asymmetry of the alternating voltage drive for the electrodes being adapted to the difference in surface properties as regards charge delivery and charge adsorption of facing insulating layers (13, 31; 32, 23), or the alternating voltage drive is symmetrical, and facing insulating layers (13, 31; 32, 23) have substantially the same surface properties as regards charge delivery and charge adsorption. The insulating layer (31, 32) consists preferably, on at least one main surface of the movalbe electrode (3) of anodized electrode material and continuing along (33) the outer peripheral and inner peripheral portions of the perforated movable electrode. The insulating layer on the substrate (1, 2) opposite the insulating layer of anodized metal material (31, 32) on the main surface of the movable electrode (3) consists of an oxide of the same metal material.

Method of manufacturing an improved electroscopic fluid display

Light losses occurring in an electroscopic display device in which UV radiation (9, 10) is converted into visible light (14, 15, 17) are partly annihilated by making the movable electrodes (7) and the fixed electrodes (4) reflective. The electroscopic display device comprises first and second radiation-transparent supporting plates (2, 3), wherein a plurality of display elements are disposed between the supporting plates (2, 3). A luminescent material (12) is disposed on one of the first and second supporting plates (2, 3) at a viewing side, wherein the luminescent material (12) is disposed between the first and second supporting plates (2, 3) adjacent to and facing the electrodes (4, 7) such that the electrodes (4, 7) reflect radiation emitted by the luminescent material (12) to increase the passage of radiation through the viewing side of the display. An extra advantage is that a diffuse light source can then be used.

Electroscopic display device

A method of manufacturing a passive display device (FIG. 1) is set forth having two substrates (1, 4) which are provided with fixed electrodes and a movable electrode (10) which is located between the substrates, which electrode lies against the upper substrate (4) in the quiescent state, and is connected to the lower substrate (1) by means of supports (9) of polymeric material. The method of manufacturing such a display device includes steps of forming the movable electrode and enclosed space between the substrates.

Method of manufacturing a display device

An electroscopic fluid display comprises substrates (1, 2) having fixed electrodes (12, 22), and movable electrodes (3) between the substrates, the electrodes (12, 22, 3) being provided on the free main surfaces with an insulating layer (13, 23, 31, 32) respectively, and the asymmetry of the alternating voltage drive for the electrodes being adapted to the difference in surface properties as regards charge delivery and charge adsorption of facing insulating layers (13, 31; 32, 23), or the alternating voltage drive is symmetrical, and facing insulating layers (13, 31; 32, 23) have substantially the same surface properties as regards charge delivery and charge adsorption. The insulating layer (31, 32) consists, preferably, on at least one main surface of the movable electrode (3) of anodized electrode material and continuing along (33) the outer peripheral and inner peripheral portions of the perforated movable electrode 3. The insulating layer on the substrate (1, 2) opposite the insulating layer of anodized metal material (31, 32) on the main surface of the movable electrode (3) consist of an oxide of the same metal material.

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Eindhoven, Netherlands

Antonius G Verhulst