Computer Memories, Incorporated

James E Quackenbush

A head positioning system for a magnetic disk memory to position the head over a reference track so that track seeking operations can proceed from a known reference location. A plurality of control tracks are recorded adjacent the reference track with the first control track having a first type of control signal recorded thereon and the remainder having a second type of control signal. Means are provided to move the head a sub-multiple of the track spacing is to establish the head as close as possible to the centerline of the track, and to thereafter move the head integral multiples of the track spacing toward the reference track. The head is moved sequentially over the control tracks until the first type of control signal is detected. One more step then positions the head over the reference track. The sub-multiple movement capability is achieved through the use of a position encoder having a polyphase output, movement between zero crossings of the polyphase outputs being said submultiple. Selection of the optimal phase positions the head as close as possible to tracks centerline, and once chosen, the optimal phase is used in track seeking operations until a disturbing event or shut down and start up.

Encoder output phase selection system for magnetic disk memory

The track access time in a disk drive system is minimized by determining an optimum velocity profile each time the system is operated. The optimum velocity profile is determined by performing repeated seek operations with successively higher velocity profiles until a seek failure occurs. A velocity profile slightly lower than the profile which caused failure is then used to control seek operations. During seek operations, the time between track crossings is monitored and the velocity profile reduced if the transducer of the disk drive system is not adequately following the preset velocity profile.

Disk drive head positioner with optimized seek operation

An amplifier for bidirectionally driving a motor includes circuitry for enabling the amplifier to operate with a bipolar input signal while employing a single power supply. The amplifier includes an input section which receives the bipolar input signal and provides a unipolar output voltage. The operational amplifier drives a bridge drive network to provide a drive current to output bridge transistor in one of two directions. The bridge network includes control circuitry for causing all of the transistors of the drive bridge to be operated in their active regions, thereby improving the power dissipation characteristics of the network. The output bridge transistors are also controlled to operate in their active regions. In addition, circuitry is included for providing negative feedback for the amplifier despite the fact that the output current is always a positive current.

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Canoga Park, CA, United States of America

James E Quackenbush