| 摘要 |
PURPOSE:To supply electric power supplied from a television camera in accordance with the operation of a servo circuit to a heater as much as possible and to prevent a lens from being fogged by providing the titled heater system with a detecting part for detecting a power supply current for the TV lens and a control part for controlling the current supplied to the heater by the detecting signal. CONSTITUTION:When a servo mechanism is driven, current is allowed to flow into the servo circuit 2, but current flowing into a resistor 4 is held at a constant current I1 by controlling a current flowing into the heater by a bridge consisting of resistors R1-R4 and a feedback mechanism constituted of an amplifier 5, a transistor 6 and the heater 3. When it is defined that current flowing into the resistor 4 is I1, current flowing into the heater 3 is I2 and current flowing into the servo circuit 2 is I3, I1=I2+I3 is formed and the current flowing into the heater 3 is I2=I1-I3. Namely, the current I2 allowed to flow into the heater 3 is all current except the current required for the servo circuit 2 out of the maximum current I1 to be supplied to the lens, so that the heater 3 is heated as high as possible even at the use of the servo mechanism to prevent the lens from being fogged.
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