MULTIPLEX ADDRESSING OF FERROELECTRIC LIQUID CRYSTAL DISPLAYS

A FERROELECTRIC LIQUID CRYSTAL DISPLAY COMPRISES LAYER OF FERROELECTRIC LIQUID CRYSTAL MATERIAL CONTAINED BETWEEN TWO CELL WALLS (2,3), SURFACE TREATED TO ALIGN THE MATERIAL IN A TILTED LAYER. THE WALLS CARRY EG ROW AND COLUMN ELECTRODES (5,6) FORMING AN X, Y MATRIX OF ADDRESSABLE ELEMENTS OR PIXELS. MULTIPLEX ADDRESSING VOLTAGES ARE PROVIDED BY DRIVER CIRCUITS (10,11). AN IMPROVED ADDRESSING IS OBTAINED BY VARYING THE ADDRESSING VOLTAGE APPLIED DURING SWITCHING OF A PIXEL TO MAXIMISE TORQUE APPLIED ON LIQUID CRYSTAL MOLECULES (21). ADDRESSING VOLTAGES ARE FROM TWO DATA WAVEFORMS AND ONE STROBE WAVEFORM (14); THE DATA WAVEFORMS HAVE THREE OR MORE TIME SLOTS PER PERIOD FORMING A LINE ADDRESS TIME, TWO OR MORE VOLTAGES LEVELS, DC BALANCE, AND EQUIVALENT RMS VALUES; THE STROBE WAVEFORM HAS TWO OR MORE VOLTAGE LEVELS (WHICH MAY INCLUDE A ZERO LEVEL). THE STROBE AND DATA WAVEFORMS COMBINE TO PROVIDE SWITCHING AND NON-SWITCHING RESULTANT WAVEFORMS THAT FORM AN ADDRESSING VOLTAGE AT EACH PIXEL. THE SWITCHING RESULTANT WAVEFORM HAS GRADUALLY INCREASING VOLTAGE LEVELS THROUGHOUT A LINE ADDRESSING TIME. THE NON-SWITCHING RESULTANT WAVEFORM HAS A FIRST VOLTAGE OF OPPOSITE POLARITY TO THAT OF THE LATER VOLTAGE LEVELS WHICH MAY INCLUDE ONE OR MORE LEVELS OF SUFFICIENTLY LARGE AMPLITUDE TO INHIBIT SWITCHING.FIGURE 1