Motor speed sensing system for magnetic disk apparatus or the li

Details Motor speed sensing system for magnetic disk apparatus or the li Motor speed sensing system for magnetic disk apparatus or the li

1991-03-13

1994-10-04

Callahan, Timothy P.

Dynamic magnetic information storage or retrieval

Automatic control of a recorder mechanism

Controlling the head

360 7811, 360 7804, G11B 555

Patent

active

053531744

ABSTRACT:
A motor speed control system is disclosed as adapted for the traveling speed control of a transducer on a pivotal support beam driven by a voice coil motor in a rotating disk data storage apparatus. The speed control system includes a speed sensor having a speed sensing coil for electromagnetically generating a motor speed signal representative of the actual traveling speed of the transducer. Since the speed sensing coil is of necessity disposed adjacent the drive coil of the voice coil motor, the motor speed signal contains a noise component due to the mutual induction between the two coils. For the elimination of the noise component from the motor speed signal, which is to be utilized for the feedback speed control of the voice coil motor, a differentiator circuit is provided for deriving a noise suppression signal, which is equivalent to the noise component, from a motor speed control signal representative of the desired traveling speed of the transducer. Both the motor speed signal and the noise suppression signal are directed to a differential amplifier whereby a is noise-free motor speed signal is obtained. A second differential amplifier inputs both this noise-free Motor speed signal and the motor speed control signal for providing an output proportional to the difference therebetween. This output is supplied to a motor driver circuit for driving the voice coil motor accordingly.

REFERENCES:
patent: 4642541 (1987-02-01), El-Sadi
patent: 4807072 (1989-02-01), Ono et al.
patent: 4875116 (1989-10-01), Yasuda et al.
patent: 4907109 (1990-03-01), Senio 360 77.04

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