| 摘要 |
PURPOSE:To attain excellent image pickup for both bright object and object with a bright background by changing the rate of change in a target voltage in response to the incident light by means of a diode and a resistance. CONSTITUTION:Resistance 4 and 5 are connected in series between a power supply 2 and ground, the anode of a diode 6 is connected to a connecting point A of the resistance and the cathode of the diode 6 is connected to a connecting point K between a resistance 3 and an image pickup tube 1. The diode 6 is nonconductive in a range where the light is less and a target voltage is higher than the potential of the anode and the sensitivity characteristic having a large degree of dropping is provided as shown in a straight line segment (l). When the target voltage is lower than the anode potential because of much of the light, however, the diode 6 is conducted. In this case, the characteristic is as shown in a straight line segment (m). |
