Memorex Corporation

Unisys Corporation

Burroughs, Inc.

Eugenio Berti

Ashraf I El-Sadi

Shown is a disk drive arrangement with servo-mechanism for controlling (thin-film) head position, etc.; the servo having a disk face dedicated to servo tracks, rendered in 'Quad' code, with special timing indicia to separate position indicia, with position signals being deployed to follow, and to be terminated by, like, distinct timing sequences.

Method for determining servo position data in a disk drive

Seek drive forces coupled between head actuators in a magnetic disk storage system employing separately controllable head actuators are prevented from affecting reliable head actuator operation. For this purpose a compensating signal is derived proportional to the driving current employed in performing an actuator seek operation. This compensating signal is fed forward into the drive circuit of the other actuator so as to cause this other actuator to begin moving its heads in a direction opposite to that which would be caused by the later arriving coupled drive forces, thereby making it possible to prevent driving forces coupled between actuators from deleteriously interferring with reliable actuator operation.

Disk drive storage system having means for compensating for seek driving

Damaging head crashes are prevented in a disk drive system by providing a specially chosen RC network between the head position control servo and the head actuator. The values of the RC network are chosen in conjunction with the servo output voltage so that, without detracting from head access time, the maximum head velocity will be limited to a value which will prevent damaging head crashes even when a fault occurs in the system.

Disk drive positioning system providing fault-free protection against

A system for rotating a data storage disc in a disc drive and for rapidly bringing the disc to a halt comprises a brushless motor fed with direct current in its windings by a motor drive circuit which current is also fed to a solenoid to hold a spring loaded solenoid arm from pressing a brake against a shaft to brake the disc, the motor control circuit using the current caused by back emf in the windings of the motor to provide motor braking while passing the current through the solenoid which applies the brake when the motor speed falls below a predetermined limit, the solenoid also being employed as a current smoothing choke.

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San Jose, CA, United States of America

Eugenio Berti