Method for reducing the number of column voltage levels in multi-line selection multiplex activation of dot matrix liquid crystal display devices

摘要

In a liquid crystal display device with a matrix structure, a plurality of lines are simultaneously selected during the periodic scanning of the line electrodes. The number of voltage levels of the column voltage signals to be provided is selected in the 2 n1 n1 + 1 range, where n1 represents the number of lines which are to be simultaneously selected. The resulting 'ON'/'OFF' selection ratio, with an appropriate selection of the amplitudes of the line selection voltages and the column voltages, differs only slightly from the optimum Alt & Pleshko selection ratio which is derived in the case where n1 + 1 column voltage levels are used. To obtain a higher 'address duty', the line selection voltage signals can be split up into a number of distinct voltage signals which are distributed over the scanning period and added to the lines concerned; the associated column voltage signals are split up in a corresponding manner.