| 摘要 |
PURPOSE:To prevent the lowering in picture quality due to excessive incident quantity of light, by changing a fixed bias point and a beam control signal in accordance with the incident quantity of light to an image pickup tube and setting a fixed beam quantity being a reference less. CONSTITUTION:An automatic variable bias point 6 changing an off-time (t) of a beam blanking pulse 1 in accordance with incident quantity of light is set to a standard signal level when the normal incident quantity of light is less, and the fixed beam quantity is increased as the quantity of light increases. Thus, since the beam follows automatically, the picture quality can remarkably be increased. |
