| 摘要 |
PROBLEM TO BE SOLVED: To provide an iris driving device the structure of which is made to be simpler while holding the controllability to the comparable to the conventional device. SOLUTION: In this iris driving device, a rotor magnet 5 is driven by a driving coil 4 and an iris is driven by the rotor magnet 5. A rotational angleθof the rotor magnet 5 is detected by a magnetic sensitive element 6, its output is amplified by an operational amplifier 3 and supplied to one input of operational amplifiers 1 and 2 as voltage VO3. Control voltage VC corresponding to a set angle of the rotor magnet 5 is impressed on the other input of the operational amplifiers 1, 2, differential voltage between the control voltage VC and the voltage VO3 is amplified and impressed on the driving coil 4. When the control voltage VC is varied, the rotor magnet 5 is rotated and stopped at a state that voltage VO1, VO2, VO3 of each part become all equivalent to the control voltage VC.
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