US4686472A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic sensor having closely spaced and electrically parallel magnetoresistive layers of different widths
Assignee: US Philips Corp
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Filing: 1986-02-10
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Granted: 1987-08-11
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Expires: 2006-02-10
Abstract
Abstract A magnetic sensor for sensing magnetic fields including two flat layers of electrically conductive ferromagnetic material (11, 16) each having an in-plane easy axis of magnetization (EA 1 , EA 2 ) and each producing a resistance variation under the influence of a magnetic field Ha which originates from a source at an edge of the layer, which layers are situated a small distance apart parallel with respect to each other. In order to increase the sensor's sensitivity to small magnetic fields, in operation the layers (11, 16) convey currents flowing in the same direction and are connected in parallel to the input terminals of a detection circuit (2, 9).
Inventors
- 👤 Johannes A. C. Van Ooijen
- 👤 Jacobus J. M. Ruigrok
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 11:30
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/02; G01R33/06; G01R33/09; G01R33/093; B; B82; B82Y; B82Y25/00; G11; G11B; G11B5/00; G11B5/127; G11B5/33; G11B5/39; G11B5/3903; G11B5/3906; G11B5/3916; G11B5/3919; G11B5/3922; G11B5/3925; G11B5/3945; G11B5/3948; G11B5/3951; G11B5/3954
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
181 words
In a magnetic sensor assembly for detecting signals recorded on an associated magnetic medium, the sensor comprising: two magnetostatically coupled magnetoresistive elements, each element having a respective planar surface, the respective planar surfaces being mutually parallel and being mutually separated by a distance, each element also having an easy axis of magnetization oriented substantially parallel with the respective planar surface; the recorded signals provided a magnetic signal field applied to the magnetoresistive elements in a signal direction; and means for providing, in operation of the sensor, measuring currents which simultaneously flow in a current direction through the elements so that each measuring current flowing through an element serves to provide the sole magnetic bias for the other of the elements, the magnetizations of the elements being biased in opposite directions; wherein, in operation of the sensor, the magnetizations of the elements are oriented perpendicularly to the current direction and parallel with the signal direction, each of the magnetoresistive elements having a respective thickness measured in a direction perpendicular to the respective planar surface, the thicknesses of the magnetoresistive elements being different.
Claim 2
Dependent Claim
181 words
In a magnetic sensor assembly for detecting signals recorded on an associated magnetic medium, the sensor comprising: two magnetostatically coupled magnetoresistive elements, each element having a respective planar surface, the respective planar surfaces being mutually parallel and being mutually separated by a distance, each element also having an easy axis of magnetization oriented substantially parallel with the respective planar surface; the recorded signals provided a magnetic signal field applied to the magnetoresistive elements in a signal direction; and means for providing, in operation of the sensor, measuring currents which simultaneously flow in a current direction through the elements so that each measuring current flowing through an element serves to provide the sole magnetic bias for the other of the elements, the magnetizations of the elements being biased in opposite directions; wherein, in operation of the sensor, the magnetizations of the elements are oriented perpendicularly to the current direction and parallel with the signal direction, each of the magnetoresistive elements having a respective thickness measured in a direction perpendicular to the respective planar surface, the thicknesses of the magnetoresistive elements being different.
Claim 3
Dependent Claim
22 words
An assembly as claimed in claim 1, characterized in that the easy access of each element is parallel to the current direction.
Claim 4
Dependent Claim
21 words
An assembly as claimed in claim 1, characterized in that the distance separating the planar surfaces is less than 30 nanometers.
Claim 5
Dependent Claim
30 words
An assembly as claimed in claim 1, characterized in that the assembly further comprises means, connected to the elements, for sensing a voltage across a parallel resistance of the elements.
Claim 6
Dependent Claim
15 words
A sensor assembly as in claim 1 wherein the elements are connected electrically in parallel.
Claim 7
Dependent Claim
49 words
An assembly as claimed in claim 1, characterized in that the assembly further comprises an intermediate layer arranged between the planar surfaces of the elements so that the elements are separated by and in contact with the intermediate layer, the intermediate layer being as of a non-magnetic, electrically-conductive material.
Claim 8
Dependent Claim
21 words
An assembly as claimed in claim 6, characterized in that the intermediate layer has a thickness of less than 10 nanometers.
Claim 9
Dependent Claim
17 words
An assembly as claimed in claim 6, characterized in that the intermediate layer consists essentially of molybdenum.
Claim 10
Dependent Claim
17 words
An assembly as claimed in claim 6, characterized in that the intermediate layer consists essentially of titanium.
Claim 11
Dependent Claim
178 words
In a magnetic sensor assembly for detecting signals recorded on an associated magnetic medium, the sensor comprising: two magnetostatically coupled magnetoresistive elements, each element having a respective planar surface, the respective planar surfaces being mutually parallel and being mutually separated by a distance, each element also having an easy axis of magnetization oriented substantially parallel with the respective planar surface; the recorded signals providing a magnetic signal field applied to the magnetoresistive elements in a signal direction; and means for providing, in operation of the sensor, measuring currents which simultaneously flow in a current direction through the elements so that each measuring current flowing through an element serves to provide a sole magnetic bias for the other of the elements, the magnetizations of the elements being biased in opposite directions; wherein, in operation of the sensor, the magnetizations of the elements are oriented perpendicularly to both the current and signal directions, each of the magnetoresistive elements having a respective thickness measured in a direction perpendicular to the respective planar surface, the thickness of the magnetoresistive elements being different.
Claim 12
Dependent Claim
178 words
In a magnetic sensor assembly for detecting signals recorded on an associated magnetic medium, the sensor comprising: two magnetostatically coupled magnetoresistive elements, each element having a respective planar surface, the respective planar surfaces being mutually parallel and being mutually separated by a distance, each element also having an easy axis of magnetization oriented substantially parallel with the respective planar surface; the recorded signals providing a magnetic signal field applied to the magnetoresistive elements in a signal direction; and means for providing, in operation of the sensor, measuring currents which simultaneously flow in a current direction through the elements so that each measuring current flowing through an element serves to provide a sole magnetic bias for the other of the elements, the magnetizations of the elements being biased in opposite directions; wherein, in operation of the sensor, the magnetizations of the elements are oriented perpendicularly to both the current and signal directions, each of the magnetoresistive elements having a respective thickness measured in a direction perpendicular to the respective planar surface, the thickness of the magnetoresistive elements being different.
Claim 13
Dependent Claim
22 words
An assembly as claimed in claim 10, characterized in that the easy access of each element is parallel to the current direction.
Claim 14
Dependent Claim
21 words
An assembly as claimed in claim 10, characterized in that the distance separating the planar surfaces is less than 30 nanometers.
Claim 15
Dependent Claim
30 words
An assembly as claimed in claim 10, characterized in that the assembly further comprises means, connected to the elements, for sensing a voltage across a parallel resistance of the elements.
Claim 16
Dependent Claim
15 words
A sensor assembly as in claim 10 wherein the elements are connected electrically in parallel.
Claim 17
Dependent Claim
49 words
An assembly as claimed in claim 10, characterized in that the assembly further comprises an intermediate layer arranged between the planar surfaces of the elements so that the elements are separated by and in contact with the intermediate layer, the intermediate layer being of of a non-magnetic, electrically-conductive material.
Claim 18
Dependent Claim
21 words
An assembly as claimed in claim 15, characterized in that the intermediate layer has a thickness of less than 10 nanometers.
Claim 19
Dependent Claim
17 words
An assembly as claimed in claim 15, characterized in that the intermediate layer consists essentially of molybdenum.
Claim 20
Dependent Claim
17 words
An assembly as claimed in claim 15, characterized in that the intermediate layer consists essentially of titanium.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-08-10 | 1991-02-09 | 1991-08-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-08-10 | 1995-02-09 | 1995-08-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-08-10 | 1999-02-09 | 1999-08-11 | $7700.00 | Window Closed / Lapsed |