Patent US5473484A successfully refreshed from Google Patents.
US5473484A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for electrically grounding a rotor hub in a disc drive motor
Assignee: Seagate Technology LLC
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Filing: 1994-06-03
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Granted: 1995-12-05
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Expires: 2014-06-03
Abstract
Abstract A disc drive includes a disc drive motor for rotating a storage disc. The motor includes a motor base having a fixed member. A rotor is rotatably coupled to the fixed member and carries the storage disc. First and second bearings are positioned between the rotor and the fixed member allowing rotation of the rotor about the fixed member. A permanent magnet is positioned between the first and second bearings. A conductive fluid between the rotor and the fixed member is maintained in operable contact with the rotor and the fixed member by the permanent magnet. The ferrofluid provides a low resistance electrical path between the rotor and the fixed member thereby electrically grounding the rotor to the motor base.
Inventors
- 👤 John C. Dunfield
- 👤 Robert M. Pelstring
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 03:22
CPC Classifications
G; G11; G11B; G11B25/00; G11B25/04; G11B25/043; G11B19/00; G11B19/20; G11B19/2009; G11B23/00; G11B23/50; G11B23/505; G11B33/00; G11B33/14; G11B33/1493
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
164 words
A disc drive motor for use in a disc drive for storing information, the disc drive motor comprising: a motor base; a fixed member coupled to the motor base; a rotor rotatable about the fixed member for rotatably carrying a storage disc; a first bearing between the rotor and the fixed member rotatably coupling the rotor to the fixed member; a second bearing between the rotor and the fixed member and axially spaced apart from the first bearing rotatably coupling the rotor to the fixed member; the first and second bearings allowing rotation of the rotor relative to the fixed member; a permanent magnet positioned between the first and second bearings and electrically coupled to the fixed member, the permanent magnet extending over an elongated axial area; and a conductive ferrofluid between the rotor and the permanent magnet and maintained in operable contact with the rotor by the permanent magnet thereby providing a low resistance electrical path between the rotor and the fixed member.
Claim 2
Dependent Claim
164 words
A disc drive motor for use in a disc drive for storing information, the disc drive motor comprising: a motor base; a fixed member coupled to the motor base; a rotor rotatable about the fixed member for rotatably carrying a storage disc; a first bearing between the rotor and the fixed member rotatably coupling the rotor to the fixed member; a second bearing between the rotor and the fixed member and axially spaced apart from the first bearing rotatably coupling the rotor to the fixed member; the first and second bearings allowing rotation of the rotor relative to the fixed member; a permanent magnet positioned between the first and second bearings and electrically coupled to the fixed member, the permanent magnet extending over an elongated axial area; and a conductive ferrofluid between the rotor and the permanent magnet and maintained in operable contact with the rotor by the permanent magnet thereby providing a low resistance electrical path between the rotor and the fixed member.
Claim 3
Dependent Claim
18 words
The disc drive motor of claim 1 wherein the fixed member is a sleeve which receives the rotor.
Claim 4
Dependent Claim
18 words
The disc drive motor of claim 1 wherein the rotor is a sleeve which receives the fixed member.
Claim 5
Dependent Claim
17 words
The disc drive motor of claim 1 wherein the permanent magnet is coated with a conductive material.
Claim 6
Dependent Claim
13 words
The disc drive motor of claim 4 wherein the conductive material is nickel.
Claim 7
Dependent Claim
166 words
A disc drive motor for use in a disc drive for storing information, the disc drive motor comprising: a motor base; a fixed member coupled to the motor base; a rotor rotatable about the fixed member for rotatably carrying a storage disc; a first bearing between the rotor and the fixed member rotatably coupling the rotor to the fixed member; a second bearing between the rotor and the fixed member and axially spaced apart from the first bearing rotatably coupling the rotor to the fixed member; the first and second bearings allowing rotation of the rotor relative to the fixed member; a permanent magnet positioned between the first and second bearings and electrically coupled to the fixed member, the permanent magnet extending over an elongated axial area; and a conductive ferrofluid between the fixed member and the permanent magnet and maintained in operable contact with the fixed member by the permanent magnet thereby providing a low resistance electrical path between the rotor and the fixed member.
Claim 8
Dependent Claim
166 words
A disc drive motor for use in a disc drive for storing information, the disc drive motor comprising: a motor base; a fixed member coupled to the motor base; a rotor rotatable about the fixed member for rotatably carrying a storage disc; a first bearing between the rotor and the fixed member rotatably coupling the rotor to the fixed member; a second bearing between the rotor and the fixed member and axially spaced apart from the first bearing rotatably coupling the rotor to the fixed member; the first and second bearings allowing rotation of the rotor relative to the fixed member; a permanent magnet positioned between the first and second bearings and electrically coupled to the fixed member, the permanent magnet extending over an elongated axial area; and a conductive ferrofluid between the fixed member and the permanent magnet and maintained in operable contact with the fixed member by the permanent magnet thereby providing a low resistance electrical path between the rotor and the fixed member.
Claim 9
Dependent Claim
18 words
The disc drive motor of claim 6 wherein the fixed member is a sleeve which receives the rotor.
Claim 10
Dependent Claim
18 words
The disc drive motor of claim 6 wherein the rotor is a sleeve which receives the fixed member.
Claim 11
Dependent Claim
17 words
The disc drive motor of claim 6 wherein the permanent magnet is coated with a conductive material.
Claim 12
Dependent Claim
13 words
The disc drive motor of claim 9 wherein the conductive material is nickel.
Claim 13
Dependent Claim
30 words
The disc drive motor of claim 6 wherein electrical resistance between the rotor and the fixed member during operation of the disc drive motor is less than about 2.5 mΩ.
Claim 14
Dependent Claim
15 words
The disc drive motor of claim 6 wherein the permanent magnet is a multipolar magnet.
Claim 15
Dependent Claim
13 words
The disc drive motor of claim 6 wherein the permanent magnet is uni-polar.
References Cited (Backward Citations)
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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) | 1998-12-04 | 1999-06-05 | 1999-12-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-12-04 | 2003-06-05 | 2003-12-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-12-04 | 2007-06-05 | 2007-12-05 | $7700.00 | Window Closed / Lapsed |