US3909643A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Direct-driven type phonograph turntable
Assignee: Victor Company of Japan Ltd
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Filing: 1974-03-25
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Granted: 1975-09-30
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Expires: 1994-03-25
Abstract
Abstract A direct-driven type phonograph turntable has a frame, a main shaft, a rotor having a plurality of equally circularly spaced magnets on the periphery thereof and an arc-shaped stator having a plurality of inwardly extending, equally spaced teeth in opposed relation to the magnets. Static unbalances and preferably, also dynamic unbalances of the rotor are compensated for by an arcuate-shaped member of a magnetically soft material. The arcuate-shaped member is located at a substantially symmetrical position to the arc-shaped stator with respect to the main shaft. More exactly, and preferably, this member has end portions mutually angularly spaced by an amount equal to a plurality of the center-to-center spacings of the magnets plus one half of the center-to-center spacing of said magnets.
Inventors
- 👤 Yukihiro Kishima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 15:41
CPC Classifications
H; H02; H02K; H02K29/00; H02K29/06; H02K29/08; G; G11; G11B; G11B19/00; G11B19/20; G11B19/2009; H02K41/00; H02K41/02
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
148 words
A phonograph turntable driving assembly, comprising; a frame; rotor means having a plurality of equally angularly spaced magnets on a periphery thereof and rotatably supported on said frame for rotating a turntable; arc-shaped stator means embracing only a portion of said periphery of said rotor means, having a plurality of inwardly extending, equally angularly spaced stator teeth in opposed relation to said magnets, and having electromagnetic coil and circuit means for magnetizing said stator teeth to cyclically attract and repel said magnets and thereby to rotate said rotor means; and means located in a substantially symmetrical position with respect to said stator means for compensating for static and dynamic unbalances of said rotor means resulting from the cyclic attracting and repelling of said magnets by the magnetized stator teeth, comprising a generally arc-shaped member of magnetically soft material, supported on said frame in opposed relation to said magnets.
Claim 2
Dependent Claim
148 words
A phonograph turntable driving assembly, comprising; a frame; rotor means having a plurality of equally angularly spaced magnets on a periphery thereof and rotatably supported on said frame for rotating a turntable; arc-shaped stator means embracing only a portion of said periphery of said rotor means, having a plurality of inwardly extending, equally angularly spaced stator teeth in opposed relation to said magnets, and having electromagnetic coil and circuit means for magnetizing said stator teeth to cyclically attract and repel said magnets and thereby to rotate said rotor means; and means located in a substantially symmetrical position with respect to said stator means for compensating for static and dynamic unbalances of said rotor means resulting from the cyclic attracting and repelling of said magnets by the magnetized stator teeth, comprising a generally arc-shaped member of magnetically soft material, supported on said frame in opposed relation to said magnets.
Claim 3
Dependent Claim
38 words
A phonograph turntable driving assembly as claimed in claim 1, wherein said generally arc-shaped member has ends located at positions displaced from one another by an amount equal to one half of the center-to-center spacing of said magnets.
Claim 4
Dependent Claim
32 words
A phonograph turntable driving assembly as claimed in claim 1, wherein said generally arc-shaped member has a plurality of equally angularly spaced apertures in positions angularly symmetrical to spaces between said teeth.
Claim 5
Dependent Claim
69 words
A phonograph turntable driving assembly as claimed in claim 1, further including second arc-shaped means of a magnetically soft material supported on said frame and having a plurality of second teeth equally spaced as said teeth of said stator means in opposed relation to said magnets, said second teeth being located at angular positions displaced by one-fourth of the angular spacing of said magnets relative to said stator teeth.
Claim 6
Dependent Claim
52 words
A phonograph turntable driving assembly as claimed in claim 1, wherein said means for compensating is a second generally arc-shaped stator having stator teeth and coil means similar to those of said stator means; said stator means and second stator jointly embracing only a portion of the periphery of said rotor means.
Claim 7
Dependent Claim
108 words
A phonograph turntable driving assembly, comprising, a frame, a main shaft, a rotor having a plurality of equally circularly spaced magnets on the periphery thereof and rotatably supported on said frame, by said shaft, a first arc-shaped stator embracing only a portion of the periphery of said rotor and having a plurality of inwardly extending, equally arcuately spaced teeth in opposed relation to said magnets, and second arc-shaped stator means constructed substantially the same as said first arc-shaped stator and located in a substantially symmetrical position to said first arc-shaped stator with respect to said main shaft for compensating for static and dynamic magnetic unbalances of said rotor.
Claim 8
Dependent Claim
108 words
A phonograph turntable driving assembly, comprising, a frame, a main shaft, a rotor having a plurality of equally circularly spaced magnets on the periphery thereof and rotatably supported on said frame, by said shaft, a first arc-shaped stator embracing only a portion of the periphery of said rotor and having a plurality of inwardly extending, equally arcuately spaced teeth in opposed relation to said magnets, and second arc-shaped stator means constructed substantially the same as said first arc-shaped stator and located in a substantially symmetrical position to said first arc-shaped stator with respect to said main shaft for compensating for static and dynamic magnetic unbalances of said rotor.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-29 | 1979-03-31 | 1979-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-29 | 1983-03-31 | 1983-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-29 | 1987-03-31 | 1987-09-30 | $7700.00 | Window Closed / Lapsed |