| 摘要 |
PURPOSE:To perform positioning of a flexible disk driver with a simple device by detecting the amplitude variation of a reproduction signal of a magnetic head to calculate digitally a tracking error and varying the duty ratio of a coil current of a step motor. CONSTITUTION:A counter 6 always keeps its counting action with the output of an oscillating circuit 5 and then starts again counting from ''0'' after an overflow. A comparator 7 compares the values of the counter 6 and a latch 8 and delivers the result of comparison to a step motor driving circuit 3 in the form of a coil current switching signal. The duty of the switching signal varies in response to the value of the latch 8. Therefore the amplitude variation of the reproduction signal is detected with vibrations of a head in order to detect a tracking error. When the tracking error is detected, the duty ratio of the coil current is varied so that the head is positioned at the center of a track. At the same time, the frequency is increased for current switching to stop the vibration of the head. |
