GB1489435A - Matrix display device - Google Patents

Abstract

1489435 Matrix displays and circuits therefor INTERNATIONAL BUSINESS MACHINES CORP 10 Dec 1974 [28 Dec 1973] 53274/74 Heading G5C A driving circuit for a display panel with crossed conductor arrays comprising means for providing two unipolar pulse trains, means to invert selected pulses of the two trains to provide two bipolar pulse trains, which when applied to electrodes of the two arrays respectively produce an A.C. waveform of zero D.C. content across display sites at the intersections of the arrays. A generator 3 provides line scanning pulses A sequentially to the exclusive OR gate 33 of each row electrode where they are combined with pulses B from a square wave generator 25 to produce pulse signal C. This is added to the output, also B, of generator 17 to give output D. Generator 5 provides pulses E to selected column gates 35 where they are combined with the outputs of generators 19, 27 to give output H. The outputs of generators 17, 25 are the complements of generators 19, 27. Thus the combined pulses across a cell, D-H are sufficient to energize it when it is selected, the sign of the voltage reversing each scan period. In other embodiments the signal B has a much higher frequency, e.g. with a pulse duration half that of A; the outputs of the X OR gates may be adjusted to increase the amplitude of signal C to 2V TH and that across selected cells to Œ3V TH . Additional h.f. bias may be added to one or both electrode arrays by generator 29, 31. The h.f. signal may be applied only to unselected electrodes to reduce half select effects. Alternatively a l.f. bias may be applied to all electrodes and scanning be done with h.f. signals. The cells may be of liquid crystal or electroluminescent material or gas discharge devices.