Head positioning system for disc files

Abstract

Abstract A positioner for precisely and quickly locating a magnetic head structure relative to a selected track on a disc file utilizes an electromagnetic device such as a brushless DC motor for pivoting a directly coupled arm and head mount through a small arc about a pivot axis. The motor, which may advantageously be mounted outside an hermetic enclosure for the discs and the arm and head structure of the positioner, comprises a multi-pole magnetic rotor whose mass is concentrated at the pivot axis, and whose periphery is closely encompassed by a stator. Energizing coils on the stator are wound in close magnetic coupling to the rotor to provide substantially uniform field distribution throughout the limited arc of movement of the rotor. While the masses of the rotor and an arm-coupling shaft are a substantial majority of the total mass of the positioner, the inertial components of the motor, shaft, and the positioner arm are well below the inertial components contributed by the head mount and heads at the terminus of the arm. Minute angular control at the motor pivot axis is feasibly translated into precise high speed accessing and tracking of selected locations on the discs. In addition, heat generated during high duty cycle energization of the motor is readily dissipated, and the motor is readily accessible for service and replacement without opening the dust-free hermetic enclosure.

Inventors

• 👤 Norman P. Gruczelak

Bibliographic Details