Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the record
Patent
1992-07-24
1993-10-05
Wolff, John H.
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the record
360 71, 360 741, 360 75, G11B 1546, G11B 1928
Patent
active
RE0343994
ABSTRACT:
An improved switching regulator DC-DC power converter or 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 converter or 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 between the read/write heads and the recording media is important and desirable.
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Dunstan Ericson
Gami Bipin V.
Micropolis Corporation
Wolff John H.
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