| 摘要 |
PURPOSE:To prevent a dc motor from rotating by decreasing the gain of a motor drive amplifier to an undriveable value when mechanical connection between the motor and a mover is cut with an automatic/manual changeover means to cut and make said mechanical connection. CONSTITUTION:Position control and position detection signals are entered to a differential amplification circuit 1 through resistors 2 and 3 and transmitted to inversion amplification circuits 6 and 9 through a switch 11. Feedback resistors 7 and 10 are installed in the two inversion amplification circuits 6 and 9 and connected to a resistor 8 to form an amplification circuit end a dc motor 14 is driven by the output signal of a transistor drive circuit 13. When the operation of a lens is changed from automatic operation to manual operation, the dc motor 14 is separated form a drive 12, the switch 11 is turned off, and the output of the differential amplification circuit 1 is shut off. Thereby rotation of the dc motor can be prevented. |
