Patent ID: 8432347

Claim:
A method for correcting gradation voltage characteristics of a liquid crystal display device having a reference voltage generating circuit which includes a fixed voltage divider circuit for outputting a predetermined drive voltage from an input power supply for generating a reference voltage, and a gradation voltage generating circuit for generating gradation voltages based on the reference voltage output by the reference voltage generating circuit, said method comprising the step of: maintaining a substantially constant input power supply to the reference voltage generating circuit; correcting the predetermined drive voltage output from the fixed voltage divider circuit with a control circuit which varies the resistance in the fixed voltage divider circuit, the control circuit including a pulse width modulation circuit for generating signals with different pulse widths under a predetermined condition, a transistor controlled by the pulse width modulation circuit, and at least a pair of resistors connected in series with the transistor and in parallel with at least one resistor in the fixed voltage divider circuit; and applying the changed predetermined drive voltage to the gradation voltage generating circuit; wherein the reference voltage is an applied voltage for black display and/or white display.