Micropolis Corporation

Dennis Hogg

John E Scura

Ericson M Dunstan

Ming-Goei Sheu

A shock resistant hard disk drive system employs a plurality of magnetic disks for recording data, a plurality of magnetic heads for performing input/output operation on the magnetic disks, with at least one of the magnetic heads being used as a servo head, a head-positioning mechanism for controlling the movement of the magnetic heads, a servo control mechanism or servo loop for opposing shifts in the location of the servo head, detecting device for detecting and measuring certain accelerations applied to the system, and filtering device for filtering the output of said detecting device and for providing the signal to the head-positioning mechanism. The detecting device detects and measures the magnitude of internal or external accelerations or shocks applied to the system, and provides the necessary signals to counter such accelerations. The pre-existing phase locked loop includes a voltage controlled oscillator, with the voltage control signal applied to the oscillator indicating instantaneous rotational velocity resulting from accelerations applied to the system; and this control signal is modified and applied to servo loop for the head positioner, to hold the head positioner against shifting off track.

Shock resistant winchester disk drive

A current amplifier is provided with three active transistors of the same polarity type, which function to amplify the input signal at a wide range of frequencies, with low power consumption and low or no output crossover distortion. One transistor, in cooperation with the second transistor, significantly amplifies the current during one swing of the input singal while the third transistor is switched off, and switches on the third transistor just prior to a reversal of the input signal swing. By the proper and immediate biasing of the third transistor according to the circuit needs, low power consumption as well as low or zero output crossover distortion is achieved.

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Simi Valley, CA, United States of America

Dennis Hogg