| 摘要 |
PROBLEM TO BE SOLVED: To provide a gamma correcting circuit capable of securing the amplitude of a picture signal and capable of improving an intermediate intensity. SOLUTION: A fundamental constituent signal proportional to Vin and an enhancement constituent signal which is changed by a gain larger than the Vin are produced based on an input picture signal Vin. A differential amplifier circuit 4 produces current Idf in accordance with a difference between the Vin and a reference voltage Vp, as the enhancement constituent signal. When the terminal voltage Ven of a resistor Rr in accordance with the current Idf has exceeded a Vh, a limiter circuit 6 is operated to suppress the increase of the Idf and mitigate the change of the Ven. An addition circuit 8 effects the summing composite of the fundamental constituent signal and the Ven to produce an output picture signal Vout. According to this operation, the Vout can be increased within the range of intermediate level of the Vin while securing the amplitude of Vout with respect to the maximum input level. COPYRIGHT: (C)2009,JPO&INPIT
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