| 摘要 |
PURPOSE:To simultaneously remove an unnecessary part and to set a correct black reference level when an expanding reading is executed by providing a means to partially make the simultaneous scanning possible and a selecting/ prohibiting means to partially prohibit the simultaneous scanning. CONSTITUTION:At the time of an expanding reading, a transistor QZC to constitute a prohibiting means is turned off. In this condition, a shift register 105 is driven at a frequency fS by pulses phi1 and phi2 during the horizontal blanking period and a shading part ob1 is read. Then, 10 picture elements are not removed from the head of an unnecessary part (c) to an output line 103 because the transistor QZC is off. The shading part ob1 only is inputted to a processing circuit 104 and a black reference level is set by a clamping pulse CP. Continuously, at the next period, unnecessary parts (a) and (b) are removed at a frequency 2fS at a high speed. When a horizontal blanking period is completed and an effective period arrives, an expanding part (b) is transferred at a frequency fS/2 at a low speed.
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