Motor control for data disc rotating systems
AssigneeBurroughs Corporation
InventorEugenio Berti
Life of this patent
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Abstract
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.
Claims12
An apparatus for rotating an informational data storage disc in a disc data store wherein a motor has a plurality of stator windings, each having a first end coupled to a common point, in turn coupled to a power supply point via a choke and each having a second end selectably couplable to a power supply return through a corresponding plurality of selectably operable stator switches, said apparatus comprising:
- energy absorbing circuit means, coupled intermediately between said second ends of said windings and said power supply point, for absorbing inductive recoil energy from said windings;
- and
- ganged double switch means, including a first section operable when said double switch means is in a first position for coupling said power supply point to a power supply rail for the operation of said motor and a second section operable when said double switch means is in a second position for shunting said energy absorbing circuit means to thereby pass dynamo currents, generated in said windings in consequence of the rotation of said motor, through said choke to act as a brake upon the rotation of said motor.
Dependencies are inferred from the claim text.