INDUCTIVE SENSING INCLUDING INDUCTANCE MULTIPLICATION WITH SERIES CONNECTED COILS
First Claim
1. A position detecting system comprising:
- a first sensor having a first coil, and a second sensor having a second coil;
the first and second coils disposed on a longitudinal axis, on opposite sides of a first target plane that is substantially orthogonal to the longitudinal axis;
the first and second coils connected in series; and
the first and second coils characterized by a series-combined inductance that is a multiple of a sum of the respective coil inductances;
the first and second coils generating respective first and second time varying magnetic fields, with respective pluralities of first and second magnetic field vectors that intersect a first sensing domain area of the first target plane, each vector having a normal component that lies orthogonal to the plane and a tangent component that lies parallel to the plane, a magnitude of the normal component being substantially greater than a magnitude of the tangent component, an orientation of the normal component matching an orientation of the first and second time varying magnetic fields at an intersection of the longitudinal axis and the plane;
a first conductive target movable within the first target plane, some portion of the target lying within the first sensing domain area, such that the series-combined inductance of the first and second coils changes as the target moves within the first sensing domain area of the first target plane; and
a support structure connected to the first sensor, the second sensor, and the target.
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Accused Products
Abstract
Inductive position sensing uses inductance multiplication with series connected sensor coils. In one embodiment, a first sensing domain area is established in a first target plane using first and second sensor coils disposed on a longitudinal axis, on opposite sides of the first target plane and connected in series, so that a series-combined inductance is a multiple of a sum of the respective first and second coil inductances. Target position within the first sensing domain area of the first target plane is detected based on the series-combined inductance of the first and second coils, which changes as the target moves within the first sensing domain area of the first target plane. Further sensitivity can be achieved by additional coils, series connected on the same longitudinal axis, each coil pair defining a sensing area on a respective target plane intermediate the coils.
26 Citations
12 Claims
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1. A position detecting system comprising:
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a first sensor having a first coil, and a second sensor having a second coil; the first and second coils disposed on a longitudinal axis, on opposite sides of a first target plane that is substantially orthogonal to the longitudinal axis; the first and second coils connected in series; and the first and second coils characterized by a series-combined inductance that is a multiple of a sum of the respective coil inductances; the first and second coils generating respective first and second time varying magnetic fields, with respective pluralities of first and second magnetic field vectors that intersect a first sensing domain area of the first target plane, each vector having a normal component that lies orthogonal to the plane and a tangent component that lies parallel to the plane, a magnitude of the normal component being substantially greater than a magnitude of the tangent component, an orientation of the normal component matching an orientation of the first and second time varying magnetic fields at an intersection of the longitudinal axis and the plane; a first conductive target movable within the first target plane, some portion of the target lying within the first sensing domain area, such that the series-combined inductance of the first and second coils changes as the target moves within the first sensing domain area of the first target plane; and a support structure connected to the first sensor, the second sensor, and the target. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method suitable for detecting position of a conductive target within a target plane, comprising:
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establishing a first sensing domain area of a first target plane using first and second sensor coils, the coils; disposed on a longitudinal axis, on opposite sides of the first target plane, which is substantially orthogonal to the longitudinal axis; and connected in series, and characterized by a series-combined inductance that is a multiple of a sum of the respective first and second coil inductances; establishing the first sensing domain area by generating first and second time varying magnetic fields, with respective pluralities of first and second magnetic field vectors that intersect the first sensing domain area, each vector having a normal component that lies orthogonal to the plane and a tangent component that lies parallel to the plane, a magnitude of the normal component being substantially greater than a magnitude of the tangent component, an orientation of the normal component matching an orientation of the first and second time varying magnetic fields at an intersection of the longitudinal axis and the plane; detecting movement of a first conductive target within the first sensing domain area of the first target plane, some portion of the target lying within the first sensing domain area, such that the series-combined inductance of the first and second coils changes as the target moves within the first sensing domain area of the first target plane. - View Dependent Claims (9, 10, 11, 12)
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Specification