| 摘要 |
A contrast control circuit for a display apparatus includes third and fourth resistors, a first transistor, a second transistor, serially connected resistors and a Darling circuit. The third and fourth resistors each has one end connected to the terminals of a positive supply voltage. The first transistor has its emitter connected to the other end of the third resistor and its base to which the first voltage is input. The second transistor has its emitter connected to the other end of the third resistor, its base connected to the other end of the fourth resistor, and its collector connected to a terminal of a negative supply voltage. The serially connected resistors have one end connected to the base of the second transistor and the other end connected to the output terminal of the second voltage. The Darlington circuit, constituents of which are connected between each of the output terminal of the second voltage, the collector of the first transistor and the terminal of the negative supply voltage, operates such that the absolute value of the second voltage is inversely proportional to the absolute value of the first voltage.
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