| 摘要 |
PURPOSE:To apply adequate damping on an actuator and to position the same correctly by connecting and disconnecting an impedance circuit to and from an auxiliary coil provided in parallel with a main coil of a voice coil motor. CONSTITUTION:A position signal is amplified 9 and is supplied to a main coil 11 and is also supplied to a current integrating circuit 10. The output thereof is added 20 to the position signal and is amplified 12. During the time of a speed mode, the speed is controlled digitally, but when the same approaches to the cylinder address stored in an address register 15, the mode is changed over to a position mode, then an impedance control circuit opens a switch 18, and a switch 13 is closed by a position mode signal, whereby an impedance 19 is connected to an auxiliary coil 17 and damping force is applied upon the main coil 11. Thus, the overrun of the actuator is prevented, and the actuator is positioned correctly by applying an adequate damping force. |
