| 摘要 |
A method of parking the head by first moving the head toward the inner diameter of the disc an then back across the disc and parking the head on a flat part of a ramp. In one embodiment, a moderate voltage on the motor drives the head toward the inner diameter of the disc until the head hits the inner crash stop and then a moderate current drives the head back across the disc to give the head enough momentum to get to the flat part of he ramp. In another embodiment, more stages, each having a different voltage, are used to get better control of the velocity of the head as it is being driven across the disc. A higher voltage is also used to turn the head to move toward the inner diameter of the disc when it is moving fast toward the outer diameter. A retract circuit controls the movement of the head during retract. To be able to drive the head in the tow directions, the retract circuit needs to be bipolar, containing both a current source and a current sink. Counters are used to time the driving of the head. Driving the head toward the outer diameter of the disc across substantially the entire disc permits the head to gather momentum as the head approaches the ramp, and use a lower current to ensure that the head gets to the flat art of the ramp where it is then parked. Parking the head on the flat part of the ramp prevents the head from landing on the disc, preventing damage to the head and the disc, and eliminating the possibility of loss or corruption of data due to the head landing on the disc.
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