| 摘要 |
PURPOSE: To obtain a circuit with which a user can expand his contrast controllable range by nonlinearly constituting a contrast control voltage generating circuit, which responds to the operation of the user. CONSTITUTION: A high-level pulse width TH in an arbitrary step Ni between steps 1 and 63 can be expressed by Ni/63 TP, where the period TP has a pulse width equal to TH+TL, and the TH and TL respectively represent the length of the high and low periods of the pulse. Changing the length of one period (for example, the period TH) of the pulse with respect to that of the other period TP is one means for changing the duty cycle (namely, TH/TP×100%) of a pulse train, supplied to a combined amplifier/filter circuit. The DC level of a contrast control voltage is changed by changing the duty cycle of the pulse train.
|
