| 摘要 |
PROBLEM TO BE SOLVED: To reduce the cost by containing a capacitor and also to obtain a ramp signal that is resistant to disturbance noise by making a charging interval a part of an interval of a horizontal blanking interval, increasing prescribed voltage at capacitor terminals to generate stepped wave and outputting it as a vertical ramp signal. SOLUTION: A charging interval is made a part of an interval of a horizontal blanking interval, and stepped wave is generated by increasing prescribed voltage at capacitor terminals and is outputted as a vertical ramp signal. In this case, charge pulse generating part 3 inputs a reference signal of a prescribed interval, makes and output Hi in a part of the interval, and a discharging pulse generating part 4 inputs a reference signal of a prescribed interval and makes an output Hi in a part of the interval. A charging and discharging control circuit 9 charges current to the capacitor 13 from the source 10 when an output of the part 3 is Hi and a switch 1 between a constant current source 10 and a capacitor 13 is conducting, and discharges charge of the capacitor 13 when an output of the part 4 is Hi and a switch 12 connected to the capacitor 13 terminals is conducting. |
