| 摘要 |
PURPOSE:To eliminate the steady load applied to a head and to increase the stiffness by applying a prescribed current to a voice coil motor in the form of an offset current. CONSTITUTION:A deciding circuit 16 delivers a control signal 23 to an offset current setting circuit 15. When a current (I0+DELTA) flows to a voice coil motor 5, a head starts its shift to the 2nd cylinder from the 1st cylinder and a counter 17 starts a count-up action. Then the circuit 16 turns off a count permitting signal 22 when the head passes through the 2nd cylinder and sets the current of the motor 5 at (I0-DELTA). Thus the head starts to move to the 1st cylinder and the counter 17 starts a count-down action. Then the circuit 16 turns off the signal 22 when the head passes through the 1st cylinder. Thus the current I0 is defined as a genuine offset current when the counter value 21 is set within a prescribed range. |
