PLANAR THREE-AXIS MAGNETOMETER
First Claim
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1. A multi-axis magnetic field sensor comprising:
- a substrate;
a first plurality of magnetoresistive sensing units disposed on the substrate and adapted to sense a magnetic field in an x-direction;
a second plurality of magnetoresistive sensing units disposed on the substrate and adapted to sense a magnetic field in a y-direction that is orthogonal to the x-direction;
a magnetic concentrator having an inner portion and an outer portion, the concentrator disposed on the substrate so that at least one sensing unit from each of the first and the second pluralities are disposed adjacent to the inner portion and at least one sensing unit from each of the first and the second pluralities are disposed adjacent to the outer portion;
wherein the magnetic concentrator is operative to convert a magnetic field in a z-direction that is orthogonal to both the x-direction and the y-direction into a magnetic field in an xy-plane.
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Abstract
A multi-axis GMR or TGMR based magnetic field sensor system is disclosed. Preferably a three axis sensor system is provided for sensing magnetic flux along three mutually orthogonal axes, which can be used for magnetic compass or other magnetic field sensing applications. The sensing units are operative to sense X and Y axis magnetic flux signals in the device (XY) plane, while Z axis sensitivity is achieved by use of a continuous ring shaped or octagonal magnetic concentrator that is adapted to convert the Z axis magnetic flux signal into magnetic flux signals in the XY plane.
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Citations
16 Claims
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1. A multi-axis magnetic field sensor comprising:
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a substrate; a first plurality of magnetoresistive sensing units disposed on the substrate and adapted to sense a magnetic field in an x-direction; a second plurality of magnetoresistive sensing units disposed on the substrate and adapted to sense a magnetic field in a y-direction that is orthogonal to the x-direction; a magnetic concentrator having an inner portion and an outer portion, the concentrator disposed on the substrate so that at least one sensing unit from each of the first and the second pluralities are disposed adjacent to the inner portion and at least one sensing unit from each of the first and the second pluralities are disposed adjacent to the outer portion; wherein the magnetic concentrator is operative to convert a magnetic field in a z-direction that is orthogonal to both the x-direction and the y-direction into a magnetic field in an xy-plane. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A magnetic field sensor comprising:
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a planar substrate, wherein virtual orthogonal co-planar X and Y axes are defined as being in an XY plane that is co-planar with the planar substrate and a virtual Z axis is defined as being orthogonal to the XY plane; a substantially planar magnetic concentrator disposed on the planar substrate, the magnetic concentrator configured to convert a magnetic field in the Z axis into a magnetic field in the XY plane and the concentrator configured to define an inner region and an outer region of the planar substrate; a first plurality of magnetoresistive sensing units disposed on the substrate adjacent the concentrator, each unit having a long axis aligned with the Y axis, and each unit configured to sense a magnetic field in the X axis; and a second plurality of magnetoresistive sensing units disposed on the substrate adjacent the concentrator, each unit having a long axis aligned with the X axis, and each unit configured to sense a magnetic field in the Y axis, wherein at least one sensing unit from each of the first and the second pluralities is disposed in the inner region and at least one sensing unit from each of the first and the second pluralities is disposed in the outer region. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A method of measuring a magnetic field in three axes, the method comprising:
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establishing a virtual XY plane having virtual orthogonal co-planar X and Y axes defined therein and a virtual Z axis that is defined as being orthogonal to the XY plane; converting an applied magnetic flux oriented in the Z axis to be substantially parallel to the XY plane; measuring the magnetic flux along the X axis at a first location to obtain a first x-flux value; measuring the magnetic flux along the X axis at a second location, different from the first location, to obtain a second x-flux value; and obtaining a value representing the magnetic flux in the Z axis by determining a difference between the first and second x-flux values. - View Dependent Claims (15, 16)
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Specification