Patent US5373407A successfully refreshed from Google Patents.
US5373407A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Disk drive spindle motor
Assignee: Mitsumi Electric Co Ltd
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Filing: 1992-11-12
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Granted: 1994-12-13
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Expires: 2012-11-12
Abstract
Abstract A small form factor disk drive having an extremely thin, high-energy product annular magnet within the spindle motor. The magnet includes twelve alternating poles disposed about the periphery and canted from the top edge to the bottom at a slight skew angle. The high-energy product magnet generates a high starting torque which obviates the use of low viscosity lithium bearing greases. A stator disposed concentrically within the magnet has three continuous coils, each coil wound around three spokes of the stator at 120 degree intervals, for a total of nine stator slots. The rotating spindle, bearings and stationary base are constructed of materials having similar coefficients of thermal expansion to reduce stresses on the bearings during periods of temperature elevation. An annular aluminum disk support sole bonds to a ledge on the spindle hub to facilitate machining and provide material compatibility. The disk drive includes various features for reducing the amount of contamination on the disk surface. A double groove bonding configuration eliminates adhesive runout and ensures a consistent bond strength.
Inventors
- 👤 Joseph J. Stupak, Jr.
- 👤 Gregory H. Chao
- 👤 Erik Moe
- 👤 Keith W. Mayberry
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 15:04
CPC Classifications
G; G11; G11B; G11B25/00; G11B25/04; G11B25/043; G11B33/00; G11B33/14; G11B33/1446
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
156 words
A small form factor disk drive having a base and a cover attached thereto providing an inner space in which a spindle motor is disposed, said motor comprising: an inverted cup-shaped rotor sized to receive central bores of one or more data disks; a rotor shaft integral with said rotor extending downward from the rotor to rotate within an upstanding flange from said base; an annular stator frame bonded to the outside of said flange and comprising outwardly extending spokes for supporting electrical coil windings; and an annular magnet bonded to the inner wall of said rotor and arranged to rotate concentrically around said stator, said magnet having a thickness of greater than 0 and less than 1 mm, said magnet having alternating poles around the circumference arranged at a slight vertical skew angle such that interfaces between alternating poles on the top edge are offset slightly from those on a bottom edge of said magnet.
Claim 2
Dependent Claim
156 words
A small form factor disk drive having a base and a cover attached thereto providing an inner space in which a spindle motor is disposed, said motor comprising: an inverted cup-shaped rotor sized to receive central bores of one or more data disks; a rotor shaft integral with said rotor extending downward from the rotor to rotate within an upstanding flange from said base; an annular stator frame bonded to the outside of said flange and comprising outwardly extending spokes for supporting electrical coil windings; and an annular magnet bonded to the inner wall of said rotor and arranged to rotate concentrically around said stator, said magnet having a thickness of greater than 0 and less than 1 mm, said magnet having alternating poles around the circumference arranged at a slight vertical skew angle such that interfaces between alternating poles on the top edge are offset slightly from those on a bottom edge of said magnet.
Claim 3
Dependent Claim
16 words
The small form factor disk drive of claim 1, wherein said skew angle is 11 degrees.
Claim 4
Dependent Claim
52 words
The small form factor disk drive of claim 1, wherein three continuous windings are distributed around the nine spokes of said stator such that each winding goes around three spokes arranged 120° apart, said three windings being alternatively energized to react with the surrounding magnetic poles resulting in a smoothed torque profile.
Claim 5
Dependent Claim
43 words
The small form factor disk drive of claim 1, further comprising: one or more annular bearings bonded to both the downwardly extending rotor shaft and base flange to provide rotational coupling therebetween, whereby a bearing grease used within said bearings contains no lithium.
Claim 6
Dependent Claim
24 words
The small form factor disk drive of claim 4, wherein said bearing grease has a viscosity of at least 160 centistokes at 40° F.
Claim 7
Dependent Claim
27 words
The small form factor disk drive of claim 4, wherein said bearing grease has a viscosity of at least 40 centistokes at a temperature of 140° F.
Claim 8
Dependent Claim
17 words
The small form factor disk drive of claim 1, wherein said annular magnet comprises twelve alternating poles.
Claim 9
Dependent Claim
22 words
The small form factor disk drive of claim 1, wherein said annular magnet has an energy product greater than 20 Mega-Gauss Oersteds.
Claim 10
Dependent Claim
169 words
A disk drive having a stationary base with a tubular flange upstanding therefrom, comprising: an annular stator mounted to the exterior surface of said tubular flange and having electrical leads depending therefrom; one or more annular bearings bonded to the inner surface of said tubular flange; a spindle having a downwardly extending central shaft bonded to the inner bore of said bearing(s), an upper circular top portion and an outer rim extending down around said tubular flange, said rim comprising an outwardly projecting ledge providing support for one or more data disks having central apertures sized to fit over said outer rim; and an annular magnet bonded to the inner wall of said rim so that a small radial gap exists between a central bore of said magnet and said stator; wherein said base, said bearing(s) and said spindle are all constructed of steel and have similar thermal expansion rates so that the bearings will experience minimal compressive stresses during an increase in the temperature generated by rotational friction.
Claim 11
Dependent Claim
169 words
A disk drive having a stationary base with a tubular flange upstanding therefrom, comprising: an annular stator mounted to the exterior surface of said tubular flange and having electrical leads depending therefrom; one or more annular bearings bonded to the inner surface of said tubular flange; a spindle having a downwardly extending central shaft bonded to the inner bore of said bearing(s), an upper circular top portion and an outer rim extending down around said tubular flange, said rim comprising an outwardly projecting ledge providing support for one or more data disks having central apertures sized to fit over said outer rim; and an annular magnet bonded to the inner wall of said rim so that a small radial gap exists between a central bore of said magnet and said stator; wherein said base, said bearing(s) and said spindle are all constructed of steel and have similar thermal expansion rates so that the bearings will experience minimal compressive stresses during an increase in the temperature generated by rotational friction.
Claim 12
Dependent Claim
25 words
The disk drive of claim 9, further comprising a ring-shaped aluminum sole to the upper edge of said ledge to form a disk contacting surface.
Claim 13
Dependent Claim
24 words
The disk drive of claim 9, wherein said magnet is constructed of neodymium and has an energy product in excess of 20 Mega-Gauss Oersteds.
Claim 14
Dependent Claim
27 words
The disk drive of claim 9, whereby the inner surface of said tubular flange comprises a pair of circular grooves for each bearing to be bonded therewith.
Claim 15
Dependent Claim
26 words
The disk drive of claim 9, whereby the central shaft of said spindle comprises a pair of circular grooves for each bearing to be bonded therewith.
Claim 16
Dependent Claim
47 words
The disk drive of claims 12 or 13, wherein one of said pair comprises a bonding groove while the other comprises a reservoir groove, the bonds between said tubular flange and said bearings and between said spindle and said bearings being primarily formed in said bonding grooves.
Claim 17
Dependent Claim
25 words
The disk drive of claim 9, wherein in an assembled state, said bearings are subject to a diagonal preload of between one and two pounds.
Claim 18
Dependent Claim
25 words
The disk drive of claim 9, wherein in an assembled state, said bearings are subject to a diagonal preload of approximately lone and one-half pounds.
Claim 19
Dependent Claim
45 words
The disk drive of claim 14, wherein one of said pair comprises a bonding groove while the other comprises a reservoir groove, the bonds between said tubular flange and said bearings and between said spindle and said bearings being primarily formed in said bonding grooves.
Claim 20
Dependent Claim
187 words
A disk drive having a base and cover for said base, comprising: an annular stator mounted to the exterior surface of a tubular flange integral with said base having electrical leads depending therefrom; one or more annular bearings bonded to the inner surface of said tubular flange; a spindle having a downwardly extending central shaft bonded to the inner bore of said bearing(s) and an inverted cup-shaped disk-support hub depending down around said tubular flange, said hub comprising an outwardly projecting ledge upon which a ring-shaped aluminum sole forms a surface providing support for a data disk having a central aperture sized to over said hub, said surface precisely machined to ensure said disk rotates at a specific predetermined height above said base; and an annular magnet bonded to the inner wall of said hub so that a small radial gap exists between a central bore of said magnet and said stator; wherein said base and said spindle are constructed of Nickel-plated Martensitic steel and said bearing(s) material has a thermal expansion rate within ten (10%) percent of that of Martensitic steel of the base and spindle.
Claim 21
Dependent Claim
187 words
A disk drive having a base and cover for said base, comprising: an annular stator mounted to the exterior surface of a tubular flange integral with said base having electrical leads depending therefrom; one or more annular bearings bonded to the inner surface of said tubular flange; a spindle having a downwardly extending central shaft bonded to the inner bore of said bearing(s) and an inverted cup-shaped disk-support hub depending down around said tubular flange, said hub comprising an outwardly projecting ledge upon which a ring-shaped aluminum sole forms a surface providing support for a data disk having a central aperture sized to over said hub, said surface precisely machined to ensure said disk rotates at a specific predetermined height above said base; and an annular magnet bonded to the inner wall of said hub so that a small radial gap exists between a central bore of said magnet and said stator; wherein said base and said spindle are constructed of Nickel-plated Martensitic steel and said bearing(s) material has a thermal expansion rate within ten (10%) percent of that of Martensitic steel of the base and spindle.
Claim 22
Dependent Claim
27 words
The disk drive of claim 18, whereby the inner surface of said tubular flange comprises a pair of circular grooves for each bearing to be bonded therewith.
Claim 23
Dependent Claim
26 words
The disk drive of claim 18, whereby the central shaft of said spindle comprises a pair of circular grooves for each bearing to be bonded therewith.
Claim 24
Dependent Claim
47 words
The disk drive of claims 19 or 20, wherein one of said pair comprises a bonding groove while the other comprises a reservoir groove the bonds between said tubular flange and said bearings and between said spindle and said bearings being primarily formed in said bonding grooves.
Claim 25
Dependent Claim
17 words
The disk drive of claim 18, wherein the base and spindle are constructed of Nickel-plated Martensitic steel.
Claim 26
Dependent Claim
189 words
A small form factor disk drive having a base and a cover attached thereto providing an inner space in which a spindle motor is disposed, said motor comprising: an inverted cup-shaped rotor comprising an upper circular top portion and an outer rim, said rim comprising an outwardly projecting ledge providing support for one or more data disks having central apertures sized to fit over said outer rim; an annular rotor shaft integral with said rotor extending downward form the rotor to rotate about an upstanding shaft from said base; an annular stator frame bonded to the inside of an upstanding tubular flange on said base and comprising outwardly extending spokes for supporting electrical coil windings; and an annular magnet bonded to the outer wall of said annular rotor shaft and arranged to rotate concentrically within said annular stator, said magnet having a thickness of greater than zero and less then 1 mm, said magnet having alternating poles around the circumference arranged at a slight vertical skew angle such that interfaces between alternating poles on a top edge are offset slightly from those on a bottom edge of said magnet.
Claim 27
Dependent Claim
189 words
A small form factor disk drive having a base and a cover attached thereto providing an inner space in which a spindle motor is disposed, said motor comprising: an inverted cup-shaped rotor comprising an upper circular top portion and an outer rim, said rim comprising an outwardly projecting ledge providing support for one or more data disks having central apertures sized to fit over said outer rim; an annular rotor shaft integral with said rotor extending downward form the rotor to rotate about an upstanding shaft from said base; an annular stator frame bonded to the inside of an upstanding tubular flange on said base and comprising outwardly extending spokes for supporting electrical coil windings; and an annular magnet bonded to the outer wall of said annular rotor shaft and arranged to rotate concentrically within said annular stator, said magnet having a thickness of greater than zero and less then 1 mm, said magnet having alternating poles around the circumference arranged at a slight vertical skew angle such that interfaces between alternating poles on a top edge are offset slightly from those on a bottom edge of said magnet.
Claim 28
Dependent Claim
13 words
The disk drive of claim 23, wherein said skew angle is 11 degrees.
Claim 29
Dependent Claim
72 words
The disk drive of claim 23, wherein the annular stator frame comprises nine outwardly extending spokes and said annular magnet has 12 alternating poles around its circumference and wherein three continuous windings are distributed around the nine spokes of said stator such that each winding goes around three spokes arranged 120° apart, said three windings being alternatively energized to react with the surrounding 12 magnetic poles resulting in a smooth torque profile.
Claim 30
Dependent Claim
25 words
The disk drive of claim 23, further comprising a ring-shaped aluminum sole to the upper edge of said ledge to form a disk contacting surface.
Claim 31
Dependent Claim
43 words
The disk drive of claim 23, further comprising: one or more annular bearings bonded to both the downwardly extending annular rotor shaft and upstanding base shaft to provide rotational coupling therebetween; and a bearing grease used within said bearings which contains no lithium.
Claim 32
Dependent Claim
21 words
The disk drive of claim 27, wherein said bearing grease has a viscosity of at least 160 centistokes at 40° F.
Claim 33
Dependent Claim
24 words
The disk drive of claim 27, wherein said bearing grease has a viscosity of at least 40 centistokes at a temperature of 140° F.
Claim 34
Dependent Claim
28 words
The disk drive of claim 27, whereby the inner surface of said annular rotor shaft comprises a pair of circular grooves for each bearing to be bonded therewith.
Claim 35
Dependent Claim
26 words
The disk drive of claim 27, whereby the upstanding shaft of said base comprises a pair of circular grooves for each bearing to be bonded therewith.
Claim 36
Dependent Claim
45 words
The disk drive of claim 31, wherein one of said pair comprises a bonding groove while the other comprises a reservoir groove, the bonds between said tubular flange and said bearings and between said spindle and said bearings being primarily formed in said bonding grooves.
Claim 37
Dependent Claim
19 words
The disk drive of claim 23, wherein the annular magnet has an energy product greater than 20 Mega-Gauss Oersteds.
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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) | 1997-12-12 | 1998-06-13 | 1998-12-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-12-12 | 2002-06-13 | 2002-12-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-12-12 | 2006-06-13 | 2006-12-13 | $7700.00 | Window Closed / Lapsed |