Patent ID: 7486288

Claim:
A display drive unit for driving a display having matrix type display elements, said display drive unit comprising: a resistive voltage-dividing circuit for dividing a display reference voltage using resistors to generate multiple bias voltages; multiple buffer circuits for respectively converting said multiple bias voltages into output voltages through impedance conversion of said bias voltages; a scanning drive circuit adapted to select a voltage to be applied to the scanning electrodes of said matrix type display elements from said output voltages of said multiple buffer circuits and apply the selected voltage to said scanning electrodes; and a signaling drive circuit adapted to select a voltage to be applied to the signaling electrodes of said matrix type display elements from said output voltages of said multiple buffer circuits and apply the selected voltage to said signaling electrodes, wherein at least one of said buffer circuits includes: a first output circuit receiving the bias voltage supplied to said buffer circuit and the output voltage of said buffer circuit, and having enhanced drive capability of providing output current to bring up said output voltage; a first output switch for allowing said first output circuit to output its voltage; a second output circuit receiving the bias voltage supplied to said buffer circuit and the output voltage of said buffer circuit, and having enhanced drive capability of providing output current for bringing down said output voltage; a second output switch for allowing said second output circuit to output its voltage; and a voltage comparator for comparing the bias voltage supplied to said buffer circuit with the detection voltage detected at a node connected to the output end of said buffer circuit, said voltage comparator adapted to switch between said first and second output switches in accord with the comparison.