DRIVING CIRCUIT FOR LIQUID CRYSTAL DISPLAY DEVICE

摘要

PURPOSE:To prevent the occurrence of display variance for polarity insertion of a driving waveform by moving the switching point of polarity inversion successively on a display screen when the driving waveform applied to a liquid crystal layer has the polarity inverted at intervals of a time corresponding to two frames and is made into an AC. CONSTITUTION:A counter circuit 10 which counts a latch signal CL1 to output a new AC converted signal M' and an AND gate 11 which adjusts the count number optionally are provided between a liquid crystal module 1 and a control ler circuit 2. Exclusive OR between the output signal M' of the counter 10 which counts the signal CL1 and an output signal M'' of a counter 20 which counts the AC converted signal M' essential to driving in the B system is operat ed to obtain an output signal M'''. The count number is so set that the fre quency of the signal M' is not an integer-fold frequency of an AC converted signal M (signal having a half frequency of a frame frequency 1/L'F and synchro nized with the signal M' in case of driving in the B system), thereby preventing the start point of polarity inversion of the driving waveform from being fixed to specific scanning lines in blocks 3a and 3b of a liquid crystal panel.