| 摘要 |
PURPOSE:To ensure an easy remote control for the iris diaphragm, by actuating the meter with the output voltage of the magnetic sensor and the differential output of the middle point voltage of the variable resistor which is operated manually. CONSTITUTION:Magnetic sensor 20 the resistance volue of which varies according to the change of the magnetic flux piercing through is stuck to housing 13 of magnet meter 10 with winding which drives the open/close of iris diaphragm 51. Then variable resistor 30 is located at a proper position more behind the camera main body than iris mechanism 50 so that the middle point voltage can be set by a simple manual operation. Differential amplifier 40 inputs the voltae obtained from the middle point voltage via the semifixed resistor plus the output voltage of sensor 20, amplifies the different of these two voltage and then applies the output signal to meter 10 to drive rotor 12. When the output voltage varying in accordance with rotation of rotor 12 becomes equal to the middle point voltage of resistor 30, no output is generated from amplifier 40 to stop rotor 12. In this instant, iris 51 of mechanism 50 is controlled to the ideal degree of opening. |
