Importance

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Abstract

A disk drive that generates a smooth spiral during the recording of data so that the recording operation is continuous. A magnetic read/write head (2) is mounted on an arm (4) so that it can move generally along a radius of a disk (8). A rotary motor (12) is used to spin the disk and to drive a gear train. The output of the gear train is used to move the arm-mounted head across the disk. The pitch of the spiral generated is controlled by the relative gear ratio between the disk and the head mechanism. Rapid retrace of the head mechanism to its starting position is accomplished by placing a return spring (56) on the head mechanism and a clutch (42) in the gear train. The location of the clutch in the gear train is chosen so that the head mechanism, while being returned to the starting position under spring power, spins a neutral pitch fan (102). The energy dissipated by churning the air by the fan limits the peak velocity of the head mechanism. The clutch mechanism itself is designed to give essentially no sliding friction during the retrace operation so that the final position achieved is repeatable. The connection from the gear train to the head mechanism is made variable, under the control of a second motor (68, 74), so that the head can be made to follow the previously-recorded track for playback. The track following is done by dithering the head and using the demodulated head output as a steering signal.

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First Claim