Disc drive with small air gap between back iron and spindle hub

Claim 2

A disc drive comprising: a disc drive frame; a shaft extending along an axis; a bearing system located around said shaft; a spindle hub having an end wall portion and a disc receiving portion, said end wall portion being attached to a rotatable surface and extending radially outward from said rotatable surface, said disc receiving portion extending down from said radially extending end wall portion and having an inner and an outer circumferential surface, said inner and outer circumferential surfaces extending along said axis, whereby said spindle hub rotates about said axis and said shaft extends internal to said spindle hub along said axis; at least one storage disc mounted on said downwardly extending disc receiving portion of said spindle hub; a back iron having a top and a bottom surface and an inner and an outer circumferential surface, said inner and outer circumferential surfaces extending along said axis, said top surface of said back iron being attached to said radially extending end wall portion of said spindle hub, whereby said outer circumferential surface of said back iron and said inner circumferential surface of said downwardly extending disc receiving portion having overlapping sections; a small air gap extending along said axis between substantially all of said overlapping sections of said outer circumferential surface of said back iron and said inner circumferential surface of said downwardly extending disc receiving portion, whereby said small air gap is maintained so that thermal expansion and contraction of said back iron does not distort said downwardly extending disc receiving portion and cause misalignment or slippage of said at least one storage disc; a rotor comprising a plurality of permanent magnets attached to said inner circumferential surface of said back iron; a stator comprising a laminate core and a plurality of phase windings, said stator being fixed to said disc drive frame, whereby said rotor rotates around said fixed stator; and means for attaching said top surface of said back iron to said radially extending end wall portion of said spindle hub.

Claim 3

A disc drive as claimed in claim 1 wherein said inner and outer circumferential surfaces of said downwardly extending disc receiving portion are substantially cylindrical and have diameters.

Claim 4

A disc drive as claimed in claim 1 wherein said inner and outer circumferential surfaces of said back iron are substantially cylindrical and have diameters.

Claim 5

A disc drive as claimed in claim 2 wherein said inner and outer circumferential surfaces of said back iron are substantially cylindrical and have diameters, said diameter of said substantially cylindrical outer circumferential surface of said back iron being slightly smaller than said diameter of said substantially cylindrical inner circumferential surface of said downwardly extending disc receiving portion for substantially all of said overlapping sections of said substantially cylindrical outer circumferential surface of said back iron and said substantially cylindrical inner circumferential surface of said downwardly extending disc receiving portion.

Claim 6

A disc drive comprising: a disc drive frame; a shaft extending along an axis; a bearing system located around said shaft; a spindle hub having an end wall portion and a disc receiving portion, said end wall portion being attached to a rotatable surface and extending radially outward from said rotatable surface, said disc receiving portion extending down from said radially extending end wall portion and having substantially cylindrical inner and outer circumferential surfaces, said substantially cylindrical inner and outer surfaces of said downwardly extending disc receiving portion having diameters and extending along said axis, whereby said spindle hub rotates about said axis and said shaft extends internal to said spindle hub along said axis; at least one storage disc mounted on said downwardly extending disc receiving portion of said spindle hub; a back iron having a top and a bottom surface and substantially cylindrical inner and outer circumferential surfaces, said substantially cylindrical inner and outer surfaces extending along said axis and having diameters, said back iron being attached to said radially extending end wall portion of said spindle hub, whereby said outer circumferential surface of said back iron and said inner circumferential surface of said downwardly extending disc receiving portion having overlapping sections; a small air gap extending along said axis between substantially all of said overlapping sections of said substantially cylindrical outer circumferential surface of said back iron and said substantially cylindrical inner circumferential surface of said downwardly extending disc receiving portion, whereby said diameter of said substantially cylindrical outer circumferential surface of said back iron is slightly smaller than said diameter of said substantially cylindrical inner circumferential surface of said downwardly extending disc receiving portion for substantially all of said overlapping sections of said substantially cylindrical outer surface of said back iron and said substantially cylindrical inner surface of said downwardly extending disc receiving portion, whereby said small air gap is maintained so that thermal expansion and contraction of said back iron does not distort said downwardly extending disc receiving portion of said spindle hub and cause misalignment or slippage of said at least one storage disc; a rotor comprising a plurality of permanent magnets attached to said inner circumferential surface of said back iron; a stator comprising a laminate core and a plurality of phase windings, said stator being fixed to said disc drive frame, whereby said rotor rotates around said fixed stator; and means for attaching said top surface of said back iron to said radially extending end wall portion of said spindle hub.

Claim 7

A disc drive comprising: a disc drive frame; a shaft extending along an axis; a bearing system located around said shaft; a spindle hub having an end wall portion and a disc receiving portion, said end wall portion being attached to a rotatable surface and extending radially outward from said rotatable surface, said disc receiving portion extending down from said radially extending end wall portion and having substantially cylindrical inner and outer circumferential surfaces, said substantially cylindrical inner and outer surfaces of said downwardly extending disc receiving portion having diameters and extending along said axis, whereby said spindle hub rotates about said axis and said shaft extends internal to said spindle hub along said axis; at least one storage disc mounted on said downwardly extending disc receiving portion of said spindle hub; a back iron having a top and a bottom surface and substantially cylindrical inner and outer circumferential surfaces, said substantially cylindrical inner and outer surfaces extending along said axis and having diameters, said back iron being attached to said radially extending end wall portion of said spindle hub, whereby said outer circumferential surface of said back iron and said inner circumferential surface of said downwardly extending disc receiving portion having overlapping sections; a small air gap extending along said axis between substantially all of said overlapping sections of said substantially cylindrical outer circumferential surface of said back iron and said substantially cylindrical inner circumferential surface of said downwardly extending disc receiving portion, whereby said diameter of said substantially cylindrical outer circumferential surface of said back iron is slightly smaller than said diameter of said substantially cylindrical inner circumferential surface of said downwardly extending disc receiving portion for substantially all of said overlapping sections of said substantially cylindrical outer surface of said back iron and said substantially cylindrical inner surface of said downwardly extending disc receiving portion, whereby said small air gap is maintained so that thermal expansion and contraction of said back iron does not distort said downwardly extending disc receiving portion of said spindle hub and cause misalignment or slippage of said at least one storage disc; a rotor comprising a plurality of permanent magnets attached to said inner circumferential surface of said back iron; a stator comprising a laminate core and a plurality of phase windings, said stator being fixed to said disc drive frame, whereby said rotor rotates around said fixed stator; and means for attaching said top surface of said back iron to said radially extending end wall portion of said spindle hub.

Claim 8

A disc drive as claimed in claim 5 wherein said spindle hub is cup shaped.

Claim 9

A disc drive as claimed in claim 5 wherein said shaft is rotatable and has an upper and a lower circumferential surface, and wherein said end wall portion is attached to said upper circumferential surface of said rotatable shaft.

Claim 10

A disc drive as claimed in claim 5 wherein said shaft is fixed and said bearing system has an upper and a lower assembly, said upper and lower assemblies having rotatable outer circumferential surfaces, and wherein said radially extending end wall portion is attached to said rotatable outer circumferential surface of said upper assembly.

Claim 11

A disc drive as claimed in claim 5 wherein said top and bottom surfaces of said back iron are annular shaped.

Claim 12

A disc drive as claimed in claim 5 wherein said back iron is made of steel and said spindle hub is made of aluminum.

Claim 13

A disc drive comprising: a disc drive frame; a rotatable shaft extending along an axis and having an upper and a lower circumferential surface; a bearing system located around said shaft; an aluminum cup shaped spindle hub having an end wall portion and a disc receiving portion, said end wall portion being attached to said upper circumferential surface of said rotatable shaft and extending radially outward from said rotatable shaft, said disc receiving portion extending down from said radially extending end wall portion and having substantially cylindrical inner and outer circumferential surfaces, said substantially cylindrical inner and outer surfaces having diameters and extending along said axis, whereby said aluminum cup shaped spindle hub rotates about said axis and said shaft extends internal to said aluminum cup shaped spindle hub along said axis; at least one storage disc mounted on said downwardly extending disc receiving portion of said spindle hub; a steel back iron having annular shaped top and bottom surfaces and substantially cylindrical inner and outer circumferential surfaces, said substantially cylindrical inner and outer surfaces extending along said axis and having diameters, said annular shaped top surface of said back iron being attached to said radially extending end wall portion of said spindle hub, whereby said outer circumferential surface of said back iron and said inner circumferential surface of said downwardly extending disc receiving portion having overlapping sections; a small air gap extending along said axis between substantially all of said overlapping sections of said substantially cylindrical outer circumferential surface of said back iron and said overlapping portion of said substantially cylindrical inner circumferential surface of said downwardly extending disc receiving portion, wherein said diameter of said substantially cylindrical outer circumferential surface of said back iron is slightly smaller than said diameter of said substantially cylindrical inner circumferential surface of said downwardly extending disc receiving portion for substantially all of said overlapping sections of said substantially cylindrical outer surface of said back iron and said substantially cylindrical inner surface of said downwardly extending disc receiving portion, wherein said small air gap is maintained so that thermal expansion and contraction of said back iron does not distort said downwardly extending disc receiving portion of said spindle hub and cause misalignment or slippage of said at least one storage disc; a rotor comprising a plurality of permanent magnets attached to said inner circumferential surface of said steel back iron; a stator comprising a laminate core and a plurality of phase windings, said stator being fixed to said disc drive frame, whereby said rotor rotates around said fixed stator; and means for attaching said annular shaped top surface of said steel back iron to said radially extending end wall portion of said aluminum cup shaped spindle hub.

Claim 14

A disc drive comprising: a disc drive frame; a rotatable shaft extending along an axis and having an upper and a lower circumferential surface; a bearing system located around said shaft; an aluminum cup shaped spindle hub having an end wall portion and a disc receiving portion, said end wall portion being attached to said upper circumferential surface of said rotatable shaft and extending radially outward from said rotatable shaft, said disc receiving portion extending down from said radially extending end wall portion and having substantially cylindrical inner and outer circumferential surfaces, said substantially cylindrical inner and outer surfaces having diameters and extending along said axis, whereby said aluminum cup shaped spindle hub rotates about said axis and said shaft extends internal to said aluminum cup shaped spindle hub along said axis; at least one storage disc mounted on said downwardly extending disc receiving portion of said spindle hub; a steel back iron having annular shaped top and bottom surfaces and substantially cylindrical inner and outer circumferential surfaces, said substantially cylindrical inner and outer surfaces extending along said axis and having diameters, said annular shaped top surface of said back iron being attached to said radially extending end wall portion of said spindle hub, whereby said outer circumferential surface of said back iron and said inner circumferential surface of said downwardly extending disc receiving portion having overlapping sections; a small air gap extending along said axis between substantially all of said overlapping sections of said substantially cylindrical outer circumferential surface of said back iron and said overlapping portion of said substantially cylindrical inner circumferential surface of said downwardly extending disc receiving portion, wherein said diameter of said substantially cylindrical outer circumferential surface of said back iron is slightly smaller than said diameter of said substantially cylindrical inner circumferential surface of said downwardly extending disc receiving portion for substantially all of said overlapping sections of said substantially cylindrical outer surface of said back iron and said substantially cylindrical inner surface of said downwardly extending disc receiving portion, wherein said small air gap is maintained so that thermal expansion and contraction of said back iron does not distort said downwardly extending disc receiving portion of said spindle hub and cause misalignment or slippage of said at least one storage disc; a rotor comprising a plurality of permanent magnets attached to said inner circumferential surface of said steel back iron; a stator comprising a laminate core and a plurality of phase windings, said stator being fixed to said disc drive frame, whereby said rotor rotates around said fixed stator; and means for attaching said annular shaped top surface of said steel back iron to said radially extending end wall portion of said aluminum cup shaped spindle hub.

Claim 15

A disc drive as claimed in claim 11 wherein said means for attaching said annular shaped top surface of said steel back iron to said radially extending end wall portion of said aluminum cup shaped spindle hub comprises epoxy applied between said radially extending end wall portion and said annular shaped top surface of said steel back iron and between a small upper portion of said substantially cylindrical outer circumferential surface of said steel back iron and a small upper portion of said inner circumferential surface of said downwardly extending disc receiving portion.

Claim 16

A disc drive as claimed in claim 11 wherein said means for attaching said annular shaped top surface of said back iron to said radially extending end wall portion of said aluminum cup shaped spindle hub comprises at least one screw extending through said radially extending end wall portion and into a threaded part in said annular shaped top surface of said back iron.

Claim 17

A disc drive as claimed in claim 11 wherein said means for attaching said annular shaped top surface of said back iron to said radially extending end wall portion of said aluminum cup shaped spindle hub comprises three screws separated by 120 degrees, said screws extending through said radially extending end wall portion and into a threaded part in said annular shaped top surface of said back iron.

Claim 18

A disc drive as claimed in claim 11 wherein said means for attaching said annular shaped top surface of said back iron to said radially extending end wall portion of said aluminum cup shaped spindle hub comprises epoxy applied between said radially extending end wall portion and said annular shaped top surface of said back iron.

Claim 19

A disc drive comprising: a disc drive frame; a shaft fixed to said disc drive frame and extending along an axis; a bearing system located around said shaft and having an upper end and a lower assembly, said upper and lower assemblies having a rotatable outer circumferential surface; an aluminum cupped shaped spindle hub having an end wall portion and a disc receiving portion, said end wall portion being attached to said rotatable upper circumferential surface of said upper assembly of said bearing system and extending radially outward from said upper assembly, said disc receiving portion extending down from said radially extending end wall portion and having substantially cylindrical inner and outer circumferential surfaces, said substantially cylindrical inner and outer surfaces having diameters and extending along said axis, whereby said aluminum cup shaped spindle hub rotates about said axis and said shaft extends internal to said aluminum cup shaped spindle hub along said axis; at least one storage disc mounted on said downwardly extending disc receiving portion of said spindle hub; a steel back iron having annular shaped top and bottom surfaces and substantially cylindrical inner and outer circumferential surfaces, said substantially cylindrical inner and outer surfaces extending along said axis and having diameters, said annular shaped top surface of said back iron being attached to said radially extending end wall portion of said spindle hub, whereby said outer circumferential surface of said back iron and said inner circumferential surface of said downwardly extending disc receiving portion having overlapping sections; a small air gap extending along said axis between substantially all of said overlapping sections of said substantially cylindrical outer circumferential surface of said back iron and said substantially cylindrical inner circumferential surface of said downwardly extending disc receiving portion, wherein said diameter of said substantially cylindrical outer circumferential surface of said back iron is slightly smaller than said diameter of said substantially cylindrical inner circumferential surface of said downwardly extending disc receiving portion for substantially all of said overlapping sections of said substantially cylindrical outer surface of said back iron and said substantially cylindrical inner surface of said downwardly extending disc receiving portion, whereby said small air gap is maintained so that thermal expansion and contraction of said back iron does not distort said downwardly extending disc receiving portion of said spindle hub and cause misalignment or slippage of said at least one storage disc; a rotor comprising a plurality of permanent magnets attached to said inner circumferential surface of said steel back iron; a stator comprising a laminate core and a plurality of phase windings, said stator being fixed to said disc drive frame, whereby said rotor rotates around said fixed stator; and means for attaching said annular shaped top surface of said steel back iron to said radially extending end wall portion of said aluminum cup shaped spindle hub.

Claim 20

A disc drive comprising: a disc drive frame; a shaft fixed to said disc drive frame and extending along an axis; a bearing system located around said shaft and having an upper end and a lower assembly, said upper and lower assemblies having a rotatable outer circumferential surface; an aluminum cupped shaped spindle hub having an end wall portion and a disc receiving portion, said end wall portion being attached to said rotatable upper circumferential surface of said upper assembly of said bearing system and extending radially outward from said upper assembly, said disc receiving portion extending down from said radially extending end wall portion and having substantially cylindrical inner and outer circumferential surfaces, said substantially cylindrical inner and outer surfaces having diameters and extending along said axis, whereby said aluminum cup shaped spindle hub rotates about said axis and said shaft extends internal to said aluminum cup shaped spindle hub along said axis; at least one storage disc mounted on said downwardly extending disc receiving portion of said spindle hub; a steel back iron having annular shaped top and bottom surfaces and substantially cylindrical inner and outer circumferential surfaces, said substantially cylindrical inner and outer surfaces extending along said axis and having diameters, said annular shaped top surface of said back iron being attached to said radially extending end wall portion of said spindle hub, whereby said outer circumferential surface of said back iron and said inner circumferential surface of said downwardly extending disc receiving portion having overlapping sections; a small air gap extending along said axis between substantially all of said overlapping sections of said substantially cylindrical outer circumferential surface of said back iron and said substantially cylindrical inner circumferential surface of said downwardly extending disc receiving portion, wherein said diameter of said substantially cylindrical outer circumferential surface of said back iron is slightly smaller than said diameter of said substantially cylindrical inner circumferential surface of said downwardly extending disc receiving portion for substantially all of said overlapping sections of said substantially cylindrical outer surface of said back iron and said substantially cylindrical inner surface of said downwardly extending disc receiving portion, whereby said small air gap is maintained so that thermal expansion and contraction of said back iron does not distort said downwardly extending disc receiving portion of said spindle hub and cause misalignment or slippage of said at least one storage disc; a rotor comprising a plurality of permanent magnets attached to said inner circumferential surface of said steel back iron; a stator comprising a laminate core and a plurality of phase windings, said stator being fixed to said disc drive frame, whereby said rotor rotates around said fixed stator; and means for attaching said annular shaped top surface of said steel back iron to said radially extending end wall portion of said aluminum cup shaped spindle hub.

Claim 21

A disc drive as claimed in claim 16 wherein said means for attaching said annular shaped top surface of said steel back iron to said radially extending end wall portion of said aluminum cup shaped spindle hub comprises epoxy applied between said radially extending end wall portion and said annular shaped top surface of said steel back iron and between a substantially small upper portion of said substantially cylindrical outer circumferential surface of said steel back iron and a substantially small upper portion of said inner circumferential surface of said downwardly extending disc receiving portion.

Claim 22

A disc drive as claimed in claim 16 wherein said means for attaching said annular shaped top surface of said back iron to said radially extending end wall portion of said aluminum cup shaped spindle hub comprises at least one screw extending through said radially extending end wall portion and into a threaded part in said annular shaped top surface of said back iron.

Claim 23

A disc drive as claimed in claim 16 wherein said means for attaching said annular shaped top surface of said back iron to said radially extending end wall portion of said aluminum cup shaped spindle hub comprises three screws separated by 120 degrees, said screws extending through said radially extending end wall portion and into a threaded part in said annular top surface of said back iron.

Claim 24

A disc drive as claimed in claim 16 wherein said means for attaching said annular shaped top surface of said back iron to said radially extending end wall portion of said aluminum cup shaped spindle hub comprises epoxy applied between said radially extending end wall portion and said annular shaped top surface of said back iron.