| 摘要 |
PURPOSE:To permit discrimination of characters or graphics on a television scope without increasing their levels even if level of a luminance signal changes by switching potential which is clipped in a clipping circuit with an output signal of a potential comparison circuit. CONSTITUTION:When the luminance signal A and a control signal B are inputted to input terminals 1 and 2 respectively, the luminance signal, the current potential of which at leading edge of a synchronizing signal is clamped to certain potential by a clamp circuit 3, is clipped by switching a switch S1 with the control signal. For the potential clipped in the clipping circuit 8, a switch S2 is turned to voltage source V1 side by the output signal from the potential comparison circuit 6 if the output signal from the clamp circuit 3 is smaller than reference potential V3 from a reference potential generating circuit 7. On the contrary, if the output signal from the clamp circuit 3 is higher than the reference potential V3, the switch S2 is turned to the voltage source V2 side by the output signal from the potential comparison circuit 6 to be clipped with the V2 potential, providing a video signal showi in Fig. C.
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