Electro-magnetic drive unit comprising a pivotable armature
AssigneeU.S. Philips Corporation
InventorsHenricus M. van Hout, Johannes T. A. van de Veerdonk
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Abstract
An electromagnetic drive unit comprises a stator (2) and an armature (4) which is pivotable about a pivotal axis (5) and which cooperates with the stator via an air gap. In order to minimize the volume and to obtain a maximum efficiency, the armature is arranged coaxially around the stator, the stator comprising at least two polepieces (6A) which are interconnected by a stator member (6B) carrying a coil (8). The armature comprises a plurality of radially magnetized poles (28A, 28B) which correspond in number to at least the number of polepieces, which poles are tangentially juxtaposed with alternately opposite polarities.
Claims15
An electromagentic drive unit comprising a stator and an armature which is pivotable about a pivotal axis and which cooperates with a stator via an air gap, characterized in that
- the stator comprises at least one pair of polepieces having respective centers which are interconnected by a magnetizable stator member carrying at least one coil, and
- the armature comprises a cylindrical armature member which is arranged coaxially around the stator, which armature has a plurality of axially and tangentially extending radially magnetized poles which correspond in the number at least to the number of stator polepieces and which are juxtaposed and alternately have opposite polarities viewed in the circumferential direction of said armature member, said poles cooperating with said polepieces via said air gap, each pole of said armature having tangentially opposed bounding surfaces, at least one of said bounding surfaces of each pole being juxtaposed with a respective bounding surface of the juxtaposed pole, said juxtaposed bounding surfaces being tangentially spaced at least substantially the same as the centers of the respective stator poles.
A pivotal-arm device for recording and/or reading record tracks in an optical disc by means of a radiation beam while said disc rotates about an axis, said device comprising
- a stationary frame,
- an optical scanning unit comprising a line system which is movable along an optical axis,
- a pivotal arm which is supported in the frame to carry the optical scanning unit, said pivotal arm pivoting about a pivotal axis which extends parallel to the axis of rotation of the optical disc,
- an electromagnetic drive unit comprising a stator which is fixed to said frame and an armature which is fixed to said pivotal arm, said stator comprising a magnetizable stator member and at least one pair of polepieces having respective centers which are interconnected by said stator member, said stator member carrying at least one coil, said armature comprising a cylindrical armature member which is arranged coaxially around the stator, and a plurality of axially and tangentially extending radially magnetized poles which correspond in number at least to the number of stator polepieces, said poles being juxtaposed and alternately having opposite polarities viewed in the circumferential direction of the armature member, said poles cooperating with said polepieces via an air gap each pole of said armature having tangentially opposed bounding surfaces, at least one of said bounding surfaces of each pole being juxtaposed with a respective bounding surface of the juxtaposed pole, said juxtaposed bounding surfaces being tangentially spaced at least substantially the same as the centers of the respective stator poles.
Dependencies are inferred from the claim text.