US4649342A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus using inclined sensor for detecting relative displacement
Assignee: Nidec Precision Corp
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Filing: 1984-06-11
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Granted: 1987-03-10
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Expires: 2004-06-11
Abstract
Abstract An apparatus for detecting a relative displacement of a magnetic record medium and a magnetic sensor a method for manufacturing the above apparatus are disclosed. A magnetization pattern is recorded on the magnetic record medium and the relative displacement is detected by means of at least two magnetic detectors arranged on a common substrate with a given pitch. The common substrate is relatively inclined with respect to an arranging direction of the magnetization pattern to derive a desired phase difference between output signals generated from respective two magnetic detectors. The two magnetic detectors are connected into a bridge circuit to derive a detection output signal representing only the relative displacement without being affected by a noise magnetic field.
Inventors
- 👤 Shigekazu Nakamura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 04:24
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/12; G01D5/14; G01D5/142; G01D5/145; G01P; G01P3/00; G01P3/64; G01P3/66
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
256 words
An apparatus for detecting a relative displacement of a magnetic record medium on which a magnetization pattern is recorded along a displacing direction, said pattern being in the form of a plurality of successive magnetized areas, each area extending in a first direction, said apparatus comprising a common substrate having a flat surface which is arranged such that it is inclined by an angle with respect to said first direction of said areas of said magnetization pattern; at least two magnetic detectors arranged on said flat surface at positions which are shifted in said first direction, each of said magnetic detectors comprising at least two magnetoresistive elements and at least one insulating layer arranged between the magnetoresistive elements; means for magnetically biasing said at least two magnetoresistive elements of each magnetic detector in opposite directions; means for connecting said at least two magnetoresistive elements of each of said detectors into at least one bridge circuit having first and second input terminals and first and second output terminals, said first and second input terminals being connectable to an electric power source; and at least one differential amplifier having first and second input terminals connected to said first and second output terminals of said at least one bridge circuit; the angle by which said flat surface is inclined with respect to said first direction being set such that output signals appearing at said first and second output terminals of the bridge circuit have a phase difference of about 180° with respect to a pitch of the magnetization pattern.
Claim 2
Independent Claim
256 words
An apparatus for detecting a relative displacement of a magnetic record medium on which a magnetization pattern is recorded along a displacing direction, said pattern being in the form of a plurality of successive magnetized areas, each area extending in a first direction, said apparatus comprising a common substrate having a flat surface which is arranged such that it is inclined by an angle with respect to said first direction of said areas of said magnetization pattern; at least two magnetic detectors arranged on said flat surface at positions which are shifted in said first direction, each of said magnetic detectors comprising at least two magnetoresistive elements and at least one insulating layer arranged between the magnetoresistive elements; means for magnetically biasing said at least two magnetoresistive elements of each magnetic detector in opposite directions; means for connecting said at least two magnetoresistive elements of each of said detectors into at least one bridge circuit having first and second input terminals and first and second output terminals, said first and second input terminals being connectable to an electric power source; and at least one differential amplifier having first and second input terminals connected to said first and second output terminals of said at least one bridge circuit; the angle by which said flat surface is inclined with respect to said first direction being set such that output signals appearing at said first and second output terminals of the bridge circuit have a phase difference of about 180° with respect to a pitch of the magnetization pattern.
Claim 3
Dependent Claim
53 words
An apparatus according to claim 1, wherein said substrate on which at least two magnetic detectors are provided is arranged in a second direction perpendicular to the displacing direction and the first direction of said areas of said magnetization pattern is inclined with respect to the second direction perpendicular to the displacing direction.
Claim 4
Dependent Claim
53 words
An apparatus according to claim 1, wherein said common substrate on which at least two magnetic detectors are provided is inclined with respect to a second direction perpendicular to the displacing direction and the first direction of said areas of said magnetization pattern is arranged in said direction perpendicular to the displacing direction.
Claim 5
Dependent Claim
52 words
An apparatus according to claim 1, wherein there are provided first and second magnetic detectors respectively having first and second and third and fourth magnetoresistive elements which are so arranged on said common substrate that a phase difference betwen output signals generated from said first and second magnetic detectors is substantially 180°.
Claim 6
Dependent Claim
73 words
An apparatus according to claim 4, wherein said first and third and second and fourth magnetoresistive elements are respectively connected in series with each other between positive and negative terminals of a voltage source, and a junction point between said first and third magnetoresistive elements and a junction point between said second and fourth magnetoresistive elements are respectivelly connected to positive and negative inputs of a differential amplifier to generate the output signal.
Claim 7
Dependent Claim
73 words
An apparatus according to claim 4, wherein said first and second and third and fourth magnetoresistive elements are respectively connected in series with each other between positive and negative terminals of a voltage source, and a junction point between said first and second magnetoresistive elements and a junction point between said third and fourth magnetoresistive elements are respectively connected to positive and negative inputs of a differential amplifier to generate the output signal.
Claim 8
Dependent Claim
75 words
An apparatus according to claim 1, wherein there are provided first, second, third and fourth magnetic detectors respectively having first and second; third and fourth; fifth and sixth; and seventh and eighth magnetoresistive elements which are so arranged on said common substrate that a phase difference between output signals generated from said first and third magnetic detectors and a phase difference between output signals generated from said second and fourth magnetic detectors are substantially 180°.
Claim 9
Dependent Claim
137 words
An apparatus according to claim 7, wherein said first and second; third and fourth; fifth and sixth; and seventh and eighth magnetoresistive elements are respectively connected in series with each other between positive and negative terminals of a voltage source, a junction point between said first and second magnetoresistive elements and a junction point between said fifth and sixth magnetoresistive elements are respectively connected to positive and negative inputs of a first differential amplifier to generate a first detection output signal, and a junction point between said third and fourth magnetoresistive elements and a junction point between said seventh and eighth magnetoresistive elements are respectively connected to positive and negative inputs of a second differential amplifier to generate a second detection output signal, a phase difference between these first and second detection output signals being substantially 90°.
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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) | 1990-03-09 | 1990-09-08 | 1991-03-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-03-09 | 1994-09-08 | 1995-03-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-03-09 | 1998-09-08 | 1999-03-10 | $7700.00 | Window Closed / Lapsed |