| 摘要 |
PURPOSE:To eliminate the change in a luminance signal by using a horizontal and vertical blanking pulse to a blanking circuit and using a horizontal blanking pulse only to a pedestal clamp circuit. CONSTITUTION:The pedestal clamp circuit consists of a switch circuit by a pedestal clamp pulse from transistors (TRs) 38, 39 and a switch circuit by a horizontal blanking pulse of TRs 40, 41. The horizontal and vertical blanking pulses are applied at the same time to a terminal D, connected directly to a blanking circuit 33 so as to apply the blanking of the blanking period. Although the pulse inputted from the terminal D is divided by resistors 60, 61, a potential of nearly 1.4V is required to turn on a TR58. When a blanking pulse having a large level for the horizontal pulse and having a small level for the vertical pulse is inputted as the pulse, only the horizontal pulse is applied to the pedestal clamp circuit and the luminance change by the vertical pulse is prevented. |
