| 摘要 |
PURPOSE:To appropriately control the rotation of a spindle motor in spite of the position in the radial direction of a magnetic head by changing the gain of a rotary control loop in accordance with the position in the radial direction of the magnetic head. CONSTITUTION:A disk 1 is set and a magnetic head 12 is moved to a free track. After photographing, a motor 1 is driven, the interruption input of an FG pulse and a PG pulse to an arithmetic unit 2 is permitted and a PWM output from the arithmetic unit 2 to the spindle motor 1 is permitted. When the motor 1 is normally rotated and its rotation is locked, a disk image is recorded and the motor 1 is stopped. On the other hand, when the FG pulse is inputted, a free running counter value is substituted for a variable NF1 and when the counter is overflowed, the maximum value of the counter is added to the NF1. The previous value NF2 is subtracted from the current value NF1, the cycle of the FG pulse is calculated, it is subtracted from the reference cycle of the FG pulse, a speed error EVOUT is calculated by multiplying a coefficient KV, it is substituted for the NF2 as a next value and the PWM output processing is executed. |
