Driving device and method for matrix-type display panel using guest-host type phase transition liquid crystal

摘要

An apparatus and a method for driving a guest-host type phase transition liquid crystal in matrix is disclosed in which X and Y electrodes in matrix comprising a guest-host liquid crystal made by adding a pleochroic dye to the cholesteric-nematic phase transition liquid crystal or chiralnematic phase transition liquid crystal are impressed with an X electrode selecting voltage, an X electrode non- selecting voltage, a Y electrode selecting voltage and a Y electrode non- selecting voltage selectively thereby to apply a holding voltage for holding the display condition of the liquid crystal cells of the liquid crystal display elements and a write-in voltage for new write-in. The region where the display condition is to be erased is designated in the liquid crystal display panel. The X and Y electrodes in that region are impressed with the X electrode non-selecting voltage, the other Y electrodes are impressed with the Y electrode selecting voltage, the other X electrodes are impressed with an erasure holding voltage having a continuously repetitive pulse waveform including one cycle of the Y electrode non-selecting voltage and three cycles of Y electrode selecting voltage, so that the liquid crystal cells in the designated region are supplied with the erasure voltage and the other liquid crystal cells are supplied with the holding voltage, thus erasing the designated region alone.