US5051853A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic disc device
Assignee: NSK Ltd
•
Filing: 1989-04-26
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Granted: 1991-09-24
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Expires: 2009-04-26
Abstract
Abstract A magnetic disc device. A seal member consisting of ring magnet and ring-shaped pole pieces is built in a shaft or housing to which disc is fixed. The inner end of the seal member is fixed to the shaft side, and the outer end forms, between the housing, a gap in which electroconductive magnetic fluid is kept. The contact areas of the electroconductive magnetic fluid with the pole pieces and the housing are made remarkedly large, so that not only grounding of the static electricity generated on the disc but also sealing of dust becomes effectual.
Inventors
- 👤 Masachi Hosoya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 06:34
CPC Classifications
F; F16; F16J; F16J15/00; F16J15/16; F16J15/40; F16J15/43; F16C; F16C33/00; F16C33/72; F16C33/76; F16C33/762; F16C33/763; F16C33/765; G; G11; G11B; G11B19/00; G11B19/20; G11B19/2009; G11B25/00; G11B25/04; G11B25/043; G11B33/00; G11B33/14; G11B33/1493; F16C2370/00; F16C2370/12; G11B33/1446
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
104 words
A magnetic disc device comprising: a seal member consisting of two ring-shaped pole pieces fixed to the end surfaces of an axially polarized ring magnet; a housing incorporating a shaft having bearings with rolling members therein to allow for a relative rotation of the shaft; a disc fixed to said shaft or said housing; and electroconductive magnetic fluid; wherein inner peripheral ends of the ring-shaped pole pieces of said seal member is fixed to the shaft side, and said electroconductive magnetic fluid is magnetically kept in a gap between outer peripheral ends of the ring-shaped pole pieces of said seal member and said housing.
Claim 2
Dependent Claim
104 words
A magnetic disc device comprising: a seal member consisting of two ring-shaped pole pieces fixed to the end surfaces of an axially polarized ring magnet; a housing incorporating a shaft having bearings with rolling members therein to allow for a relative rotation of the shaft; a disc fixed to said shaft or said housing; and electroconductive magnetic fluid; wherein inner peripheral ends of the ring-shaped pole pieces of said seal member is fixed to the shaft side, and said electroconductive magnetic fluid is magnetically kept in a gap between outer peripheral ends of the ring-shaped pole pieces of said seal member and said housing.
Claim 3
Dependent Claim
79 words
A magnetic disc device as claimed in claim 1, wherein said seal member consisting of two ring-shaped pole pieces fixed to the end surfaces of an axially polarized ring magnet is fixed to the inner race on the shaft side of the bearing, and electroconductive magnetic fluid is magnetically kept in a gap between the outer race on the housing side of the bearing and the outer peripheral ends of the two ring-shaped pole pieces of said seal member.
Claim 4
Dependent Claim
59 words
A magnetic device as claimed in claim 2 wherein bent extensions are formed on outer peripheral ends of the pole pieces in the seal member to form the gap, and the length of said bent extensions is made larger than the distance of the gap to have a larger contact area of the pole pieces with electroconductive magnetic fluid.
Claim 5
Dependent Claim
65 words
A magnetic disc device as claimed in claim 1, wherein said seal member consisting of two ring-shaped pole pieces fixed to the end surfaces of an axially polarized ring magnet is fixed directly to the shaft, and electroconductive magnetic fluid is magnetically kept in a gap between the housing itself and the outer peripheral ends of the two ring pole pieces in said seal member.
Claim 6
Dependent Claim
59 words
A magnetic device as claimed in claim 4 wherein bent extensions are formed on outer peripheral ends of the pole pieces in the seal member to form the gap, and the length of said bent extensions is made larger than the distance of the gap to have a larger contact area of the pole pieces with electroconductive magnetic fluid.
Claim 7
Dependent Claim
44 words
A magnetic disc device as claimed in claim 3, wherein said seal member consisting of two ring-shaped pole pieces fixed to the end surfaces of an axially polarized ring magnet is disposed in the bearing which has no inner race but an outer race.
Claim 8
Dependent Claim
59 words
A magnetic device as claimed in claim 6 wherein bent extensions are formed on outer peripheral ends of the pole pieces in the seal member to form the gap, and the length of said bent extensions is made larger than the distance of the gap to have a larger contact area of the pole pieces with electroconductive magnetic fluid.
Claim 9
Dependent Claim
87 words
A magnetic disc device as claimed in claim 3, wherein the inner race of the bearing is used as pole pieces, the ring magnets are disposed at both ends of said pole pieces, and the ring magnets are disposed at both ends of said pole pieces, and electroconductive magnetic fluid is magnetically kept in a gap between the outer race of the bearing and the outer peripheral ends of the two ring-shaped pole pieces fixed to the magnetic poles at the end face portions of said magnets.
Claim 10
Dependent Claim
59 words
A magnetic device as claimed in claim 8 wherein bent extensions are formed on outer peripheral ends of the pole pieces in the seal member to form the gap, and the length of said bent extensions is made larger than the distance of the gap to have a larger contact area of the pole pieces with electroconductive magnetic fluid.
Claim 11
Dependent Claim
60 words
A magnetic disc device as claimed in claim 1, wherein bent extensions are formed on outer peripheral ends of the pole pieces in the seal member to form the gap, and the length of said bent extensions is made larger than the distance of the gap to have a larger contact area of the pole pieces with electroconductive magnetic fluid.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-09-23 | 1995-03-25 | 1995-09-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-09-23 | 1999-03-25 | 1999-09-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-09-23 | 2003-03-25 | 2003-09-24 | $7700.00 | Window Closed / Lapsed |