US5420736A
Expired / Lapsed
US
⏱️ 0.0 years remaining
MR read transducer with thermal noise cancellation
Assignee: International Business Machines Corp
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Filing: 1994-04-15
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Granted: 1995-05-30
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Expires: 2014-04-15
Abstract
Abstract Three leads L1, L2, and L3 connected to an MR stripe of an MR read transducer are arranged in a circuit for eliminating: (1) thermal asperity noise, (2) damage from shorting from the transducer to a magnetic medium, and (3) signal reduction from shorting between the conductive layers of the transducer at the ABS. The first and second leads L1 and L2 are connected to the MR stripe adjacent its top edge and the third lead L3 is connected to the MR stripe adjacent its bottom edge, the bottom edge being at the ABS of the transducer. A current of equal magnitude is applied to each of the first and second leads to flow at an angle from each of these leads to the third lead L3, this angle being preferably 45° to the longitudinal axis or ABS of the MR stripe. A differential preamplifier is connected across the first and second leads L1 and L2. With this arrangement, thermal asperity noise is cancelled by common mode rejection at the differential preamplifier. The third lead L3 and the support device for a magnetic medium are grounded to prevent sensor damage from shorting between these components. The third lead also electrically interconnects the MR stripe to one of the shield layers S1 or S2 and both shield layers are grounded to prevent signal loss from shorting between these conductive layers at the ABS.
Inventors
- 👤 David E. Heim
- 👤 Po-Kang Wang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 23:38
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/31; G11B5/33; G11B5/39; G11B5/3903; G11B5/398; G11B19/00; G11B19/02; G11B19/04; G11B5/02; G11B5/40; G11B5/48; G11B5/488; G11B5/4886
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
152 words
An MR read transducer comprising: an elongated MR stripe having a longitudinal axis which is located between top and bottom edges; first and second leads connected to the MR stripe along one of its edges in a spaced apart relationship and a third lead connected to the MR stripe along its other edge; each of the first and second leads having an edge and the third lead having first and second edges, all of the edges being spaced from one another; the edge of the first lead and the first edge of the third lead being in a spaced apart relationship facing one another along an angle α to the longitudinal axis of the MR stripe; and the edge of the second lead and the second edge of the third lead being in a spaced apart relationship facing one another along an angle β to the longitudinal axis of the MR stripe.
Claim 2
Dependent Claim
152 words
An MR read transducer comprising: an elongated MR stripe having a longitudinal axis which is located between top and bottom edges; first and second leads connected to the MR stripe along one of its edges in a spaced apart relationship and a third lead connected to the MR stripe along its other edge; each of the first and second leads having an edge and the third lead having first and second edges, all of the edges being spaced from one another; the edge of the first lead and the first edge of the third lead being in a spaced apart relationship facing one another along an angle α to the longitudinal axis of the MR stripe; and the edge of the second lead and the second edge of the third lead being in a spaced apart relationship facing one another along an angle β to the longitudinal axis of the MR stripe.
Claim 3
Dependent Claim
29 words
A disk drive including the MR read transducer as claimed in claim 1, the disk drive including: a spindle for rotating a magnetic disk; and the spindle being grounded.
Claim 4
Dependent Claim
60 words
An MR read transducer as claimed in claim 1 including: first and second shield layers constructed of NiFe; the MR stripe being located between the first and second shield layers; any of the leads connected to the MR stripe along the bottom edge being connected to one of the shield layers; and the first and second shield layers being grounded.
Claim 5
Dependent Claim
18 words
An MR read transducer as claimed in claim 1 including: the angles α and β being substantially equal.
Claim 6
Dependent Claim
57 words
An MR read transducer as claimed in claim 4 including: each of the angles α and β being substantially 45 degrees; the edges of the first and second leads extending substantially 90 degrees with respect to one another; and the first and second edges of the third lead extending substantially 90 degrees with respect to one another.
Claim 7
Dependent Claim
59 words
An MR read transducer as claimed in claim 1 including: the MR stripe having first and second film surfaces which are bounded in part by the top and bottom edges; and the leads being flat strips which are mounted to the first film surface and the edges of the leads being within a boundary of the first film surface.
Claim 8
Dependent Claim
65 words
An MR read transducer as claimed in claim 1 including: sensing circuit means connected to the first, second and third leads for applying a sense current between the first and third leads and for applying a sense current between the second and third leads; and the current in the first and third leads and the current in the second and third leads being substantially equal.
Claim 9
Dependent Claim
27 words
An MR read transducer as claimed in claim 7 including: the sensing circuit means including a differential preamplifier which is connected across the first and second leads.
Claim 10
Dependent Claim
26 words
An MR read transducer as claimed in claim 8 including: servo circuit means including a summing preamplifier which is connected across the first and second leads.
Claim 11
Dependent Claim
41 words
A disk drive including the MR read transducer as claimed in claim 9, the disk drive including: a disk supported below the bottom edge of the MR stripe; and the disk having a circular track which carries information and servo data.
Claim 12
Dependent Claim
41 words
A disk drive as claimed in claim 10 including: the track having first and second spaced apart edges; and the servo data comprising a pulse which extends from the first edge of the track to the second edge of the track.
Claim 13
Dependent Claim
64 words
An MR read transducer as claimed in claim 1 including: the first and second leads being connected to the MR stripe along the top edge of the MR stripe; the third lead being connected to the MR stripe along the bottom edge of the MR stripe; and the bottom edge of the MR stripe extending along an air bearing surface of the MR transducer.
Claim 14
Dependent Claim
64 words
An MR read transducer as claimed in claim 1 including: the first and second leads being connected to the MR stripe along the bottom edge of the MR stripe; the third lead being connected to the MR stripe along the top edge of the MR stripe; and the bottom edge of the MR stripe extending along an air bearing surface of the MR transducer.
Claim 15
Dependent Claim
19 words
An MR read transducer as claimed in claim 1 including: the MR stripe being biased along its longitudinal axis.
Claim 16
Dependent Claim
21 words
An MR read transducer as claimed in claim 14 including: means for hard biasing the MR stripe along its longitudinal axis.
Claim 17
Dependent Claim
23 words
An MR read transducer as claimed in claim 1 including: any leads connected to the MR stripe along the bottom edge being grounded.
Claim 18
Dependent Claim
60 words
An MR read transducer as claimed in claim 16 including: first and second shield layers constructed of NiFe; the MR stripe being located between the first and second shield layers; any of the leads connected to the MR stripe along the bottom edge being connected to one of the shield layers; and the first and second shield layers being grounded.
Claim 19
Dependent Claim
18 words
An MR read transducer as claimed in claim 17 including: the angles α and β being substantially equal.
Claim 20
Dependent Claim
57 words
An MR read transducer as claimed in claim 18 including: each of the angles α and β being substantially 45 degrees; the edges of the first and second leads extending substantially 90 degrees with respect to one another; and the first and second edges of the third lead extending substantially 90 degrees with respect to one another.
Claim 21
Dependent Claim
65 words
An MR read transducer as claimed in claim 19 including: sensing circuit means connected to the first, second and third leads for transmitting a sense current between the first and third leads and for transmitting a sense current between the second and third leads; and the current in the first and third leads and the current in the second and third leads being substantially equal.
Claim 22
Dependent Claim
57 words
An MR read transducer as claimed in claim 20 including: the MR stripe having first and second film surfaces which are bounded by the top and bottom edges; and the leads being flat strips which are mounted to the first film surface and the edges of the leads being within a boundary of the first film surface.
Claim 23
Dependent Claim
27 words
An MR read transducer as claimed in claim 21 including: the sensing circuit means including a differential preamplifier which is connected across the first and second leads.
Claim 24
Dependent Claim
26 words
An MR read transducer as claimed in claim 22 including: servo circuit means including a summing preamplifier which is connected across the first and second leads.
Claim 25
Dependent Claim
34 words
An MR read transducer as claimed in claim 23 including: a disk supported below the bottom edge of the MR stripe; and the disk having a circular track which carries information and servo data.
Claim 26
Dependent Claim
42 words
An MR read transducer as claimed in claim 24 including: the track having first and second spaced apart edges; and the servo data comprising a pulse which extends from the first edge of the track to the second edge of the track.
Claim 27
Dependent Claim
64 words
An MR read transducer as claimed in claim 25 including: the first and second leads being connected to the MR stripe along the top edge of the MR stripe; the third lead being connected to the MR stripe along the bottom edge of the MR stripe; and the bottom edge of the MR stripe extending along an air bearing surface of the MR transducer.
Claim 28
Dependent Claim
233 words
An MR read transducer comprising: an elongated MR stripe which has a longitudinal axis; the MR stripe having first and second film surfaces which are bounded in part by top and bottom edges; first and second conductive strips connected to the first film surface in a spaced apart relationship and extending from one of the edges of the MR stripe toward said longitudinal axis; a third conductive strip connected to the first film surface and extending from the other edge of the MR stripe toward said longitudinal axis; any conductive strip connected to the MR stripe along said bottom edge being grounded; each of the first and second conductive strips having a substantially straight edge and the third conductive strip having first and second straight edges; the straight edge of the first conductive strip and the first straight edge of third conductive strip being spaced from one another in a substantially parallel relationship and facing one another along a line which is at an angle α to the longitudinal axis of the MR strip; the straight edge of the second conductive strip and the second edge of the third conductive strip being spaced from another in a substantially parallel relationship and facing one another along a line which is at an angle β to the longitudinal axis of the MR strip; and means for hard biasing the MR stripe along its longitudinal axis.
Claim 29
Dependent Claim
233 words
An MR read transducer comprising: an elongated MR stripe which has a longitudinal axis; the MR stripe having first and second film surfaces which are bounded in part by top and bottom edges; first and second conductive strips connected to the first film surface in a spaced apart relationship and extending from one of the edges of the MR stripe toward said longitudinal axis; a third conductive strip connected to the first film surface and extending from the other edge of the MR stripe toward said longitudinal axis; any conductive strip connected to the MR stripe along said bottom edge being grounded; each of the first and second conductive strips having a substantially straight edge and the third conductive strip having first and second straight edges; the straight edge of the first conductive strip and the first straight edge of third conductive strip being spaced from one another in a substantially parallel relationship and facing one another along a line which is at an angle α to the longitudinal axis of the MR strip; the straight edge of the second conductive strip and the second edge of the third conductive strip being spaced from another in a substantially parallel relationship and facing one another along a line which is at an angle β to the longitudinal axis of the MR strip; and means for hard biasing the MR stripe along its longitudinal axis.
Claim 30
Dependent Claim
29 words
A disk drive including the MR read transducer as claimed in claim 27, the disk drive including: a spindle for rotating a magnetic disk; and the spindle being grounded.
Claim 31
Dependent Claim
60 words
An MR read transducer as claimed in claim 27 including: first and second shield layers constructed of NiFe; the MR stripe being located between the first and second shield layers: any of the leads connected to the MR stripe along the bottom edge being connected to one of the shield layers; and the first and second shield layers being grounded.
Claim 32
Dependent Claim
73 words
An MR read transducer as claimed in claim 29 including: the angles α and β being substantially equal; sensing circuit means connected to the first, second and third leads for transmitting a sense current between the first and third leads and for transmitting a sense current between the second and third leads; and the current in the first and third leads and the current in the second and third leads being substantially equal.
Claim 33
Dependent Claim
106 words
A disk drive including the MR read transducer as claimed in claim 30, the disk drive including: the sensing circuit means including a differential preamplifier which is connected across the first and second leads; servo circuit means including a summing preamplifier which is connected across the first and second leads; a disk supported below the bottom edge of the MR stripe; the disk having a circular information track; the track also containing servo data; the track having first and second spaced apart edges; and the servo data comprising a pulse which extends from the first edge of the track to the second edge of the track.
Claim 34
Dependent Claim
58 words
A disk drive as claimed in claim 31 including: each of the angles α and β being substantially 45 degrees; the edges of the first and second conductive strips extending substantially 90 degrees with respect to one another; and the first and second edges of the third conductive strip extending substantially 90 degrees with respect to one another.
Claim 35
Dependent Claim
65 words
A disk drive as claimed in claim 32 including: the first and second conductive strips being connected to the MR stripe along the top edge of the MR stripe; the third conductive strip being connected to the MR stripe along the bottom edge of the MR stripe; and the bottom edge of the MR stripe extending along an air bearing surface of the MR transducer.
Claim 36
Dependent Claim
63 words
A disk drive as claimed in claim 32 including: the first and second leads being connected to the MR stripe along the bottom edge of the MR stripe; the third lead being connected to the MR stripe along the top edge of the MR stripe; and the bottom edge of the MR stripe extending along an air bearing surface of the MR transducer.
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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) | 1998-05-29 | 1998-11-28 | 1999-05-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-05-29 | 2002-11-28 | 2003-05-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-05-29 | 2006-11-28 | 2007-05-30 | $7700.00 | Window Closed / Lapsed |