Micropolis Corporation

Bipin V Gami

Russell H Jacobs

Ashok K Desai

William J Gervais

Ericson M Dunstan

Ericson Dunstan

A hard disk drive digital storage system provides increased power efficiency and reduced power losses by using a switching regulator type DC to DC power converter, to control spindle motor speed, in which a variable duty cycle, low 'ON' resistance n-channel power MOSFET transistor is located near the ground side of the motor drive circuit. A voltage booster circuit provides higher gate control switching voltages to the motor power phase commutation switching transistors. A sense resistor is connected between the converter and ground, and the voltage developed across this sense resistor provides a signal which is coupled to the motor control circuit to vary the duty cycle of the converter to regulate the peak current applied to the motor.

Drive motor controller for low power disk drive

A hard disk drive digital storage system provides increased efficiency and reduced losses by using a switching regulator type power supply in which a variable duty cycle, low resistance n-channel field effect transistor is located near the ground side of the motor drive circuit. A voltage booster circuit provides higher switching voltages to the motor power phase control switching transistors.

Low power disk drive spindle motor controller

The power amplifier for the head positioning coil of a Winchester or hard disk drive digital storage system includes circuitry for generating complementary variable width pulses at a frequency above 100 kilohertz. The filter coupling the positive and negative power pulses to the head positioner coil includes two oppositely poled coils mounted on a single enclosing coil to avoid D.C. saturation and to maintain high inductance for high frequency noise filtering. Circuitry is also provided for improving the common mode noise rejection capability of the feedback circuit, and the head retract circuitry.

Efficient head positioner power amplifier

An improved switching regulator power supply with a variable duty cycle is disclosed which forms part of a compact Winchester disk drive system having a storage capacity in excess of 380M bytes of information. The switching regulator is designed for frequencies in excess of 80 kilocycles per second and may therefore be construced using smaller capacitive and inductive elements. Also, very low heat dissipation and high regulator efficiency may be achieved by the improved power supply to drive a brushless D. C. motor encased within a hard disk assembly where no separate fan or cooling system is used to aid in heat removal. Circuitry is provided to control the motor speed while simultaneously limiting the motor current to a predetermined level. This is a achieved by controlling the voltage applied to the motor by suitably adjusting the duty cycle of the switching regulator. A filter is provided to ensure that the switching regulator current fluctuations are not reflected in the current drawn from the power supply. At the start when the D. C. motor E.M.F. is zero, the switching regulator causes significantly higher current to flow through the motor than is drawn from the power supply through a current multiplying effect. These unique features provides significant advantages in a Winchester disk drive using thin film media whose overcoming high level of initial stiction-friction forces is important and desirable.

Winchester disk drive motor circuitry

A printed circuit motor is constructed with the printed circuit windings stationary, and therefore constituting the stator of the motor. The stator is mounted at the end of a heavy hollow supporting frame member. The rotor is mounted on the end of a shaft which is journaled within the hollow frame member, and the rotor extends outwardly in close proximity to the stator and around the outer periphery of the stator and back toward the hollow supporting member, with a permanent magnet assembly on one side of the printed circuit stator and the magnetic return path on the other side of it. The permanent magnet assembly and the magnetic return path are rigidly coupled so that no relative motion occurs between them. Electrical connections to the winding turns of the stator are brought out from the periphery of the stator close to its surface through an additional printed circuit board, and along the outer surface of the hollow frame member to pass the inner edge of the permanent magnet rotor. Timing for the energization of the coils of the printed circuit stator is controlled by three photosensors which are interrupted by the outer edge of the rotating return path of the rotor, which is provided with a peripheral interruptions to selectively block the light path to the photosensors. Six coils of the printed circuit stator are arranged in a Y-configuration and are selectively energized in accordance with the output from the photosensors.

Growing community of inventors

Northridge, CA, United States of America

Bipin V Gami