Disk drive with internal brake and static discharge

Details Disk drive with internal brake and static discharge Disk drive with internal brake and static discharge

1985-12-02

1987-10-20

Salce, Patrick R.

Electrical generator or motor structure

Dynamoelectric

Rotary

310 71, 310 78, H02K 7102, H02K 1100

Patent

active

047016531

ABSTRACT:
A drive unit for direct drive of an information-storage disk comprises a collectorless D.C. external-rotor motor having a permanent-magnet rotor magnet arrangement of considerably reduced axial length. Electrostatic charge is removed from the rotor shaft by a metallic spring element which engages the shaft periphery from within the interior of the rotor housing. An electromagnetic braking arrangement is located interiorly of the housing. The packet of stator plates for the stator has an axial length shorter than that of the rotor magnet arrangement, but is provided at its axial end faces with skirted-rim flux-conducting elements whose peripheral skirt portions form useful-air-gap extensions in cooperation with the rotor magnet arrangement. The stator plate packet and associated skirted-rim flux-conducting elements may have cut-outs defining salient-pole structure; the skirt portions of the flux-conducting elements are provided with cut-outs at their leading ends serving to produce a reluctance torque component which, during rotor rotation, is shifted in time relative to the electromagnetic torque component attributable to the salient-pole configuration. The portion of the rotor structure which supports an information-storage disk has an annular recess accommodating a disk-holding magnet whose upper surface is slightly recessed relative to an annular magnetically conductive disk-supporting ridge of the rotor, the cross-sectional shape of the ridge being such as to establish a magnetic disk-holding force of exactly predetermined character despite tolerance-range variation of the coercive force of the holding magnet employed.

REFERENCES:
patent: 3619676 (1971-11-01), Kawakami
patent: 4497002 (1985-01-01), von der Heide et al.
patent: 4535373 (1985-08-01), Schuh

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