Siemens Aktiengesellschaft

Werner Cirkler

Hans Krueger

Hans Kruger

A liquid crystal cell having a pair of carrier plates spaced apart to form a chamber for receiving a layer of liquid crystal material, each of the carrier plates having an electrical conductive coating or layer forming the electrodes on the surface facing the chamber with the surface of the electrodes being flush with the surface of an insulating material. The insulating material may be an additional layer of material disposed with the electrical conductive coating on the carrier plate or may be the carrier plate with the conductive coating being placed in recesses which have a depth equal to the thickness of the conductive coating. To form the recesses, a mask is applied to the surface of the carrier plate which is then etched, a conductive coating is applied on the remaining portions of the mask and in the recesses and then the mask is stripped with the coating thereon. When the coating and an insulating coating are applied on the carrier plate, a coating of electrical conductive material is applied on the surface of the carrier plate, a mask is applied, those portions of the coating which are not necessary to form the electrode structure are removed, a second coating of insulating material is applied in the areas where the electrical conductive coating was removed and then the mask is removed with the portion of the coating disposed thereon.

Process for making a liquid crystal cell

A liquid crystal display device characterized by a liquid crystal cell having a layer of liquid crystal material, which is switchable on a zonal basis between various optical states, interposed between a front and rear carrier plates; a fluorescent plate which is disposed behind the rear carrier plate of a liquid crystal cell in the path of observation and has light emergent or exit windows disposed behind the switchable liquid crystal zones; and at least one supplemental light source in optical contact with the fluorescent plate to provide light for exciting fluorescent centers in the fluorescent plate. The fluorescent plate has silvered edge surfaces and consists of a material which has an index of refraction greater than 1 and contains the fluorescent centers which are excited by ambient light to emit a fluorescent light isotropically. Preferably, the liquid crystal layer is interposed between front and rear electrodes which control the optical properties of the layer. In one embodiment, the cell includes polarizers which coact with the liquid crystal layer to control the emission of light through the exit windows of the fluorescent plate. In another embodiment, the liquid crystal layer contains a pleochroic dye which will absorb the fluorescent light to a high degree while the layer is in an un-energized state and only absorbed the fluorescent light to a limited degree while the layer is in an excited state. The light exit windows may be provided with dielectric layers, which will reflect on a color selected basis so that the multi-colored displays are obtainable and the dielectric mirrors and the plane of the fluorescent plate may be arranged to enclose an angle of the polarization so that the light emerging from the exit windows is polarized.

Liquid crystal display device with supplementary lighting

An optical display device having a high contrast in the light intensity of the image being displayed relative to the background light characterized by a liquid crystal cell having a layer of liquid crystal material interposed between spaced front and rear transparent carrier plates which have transparent electrodes on their inner surfaces facing the layer and a fluorescent plate of material, which has an index of refraction greater than 1, and fluorescent centers creating fluorescent light from an ambient light, being disposed behind the liquid crystal cell in the direction of viewing with the surface of the fluorescent plate being in direct contact with an outer surface of the rear carrier plate. In this device, a selective application of voltage to the selected electrodes of the cell will cause a change in the optical properties of the liquid crystal layer to decouple light from the display with an intensity substantially greater than the intensity of the background of the display. Preferably, the liquid crystal cell is received within a recess in the plate so that the outer surface of the front plate is flush with the remaining surface of the fluorescent plate. If desired, an additional illuminating device may be encapsulated within the plate to provide an additional source of light.

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Ismaning, Germany

Werner Cirkler