Systems, methods, and apparatus for detecting ferromagnetic foreign objects in a predetermined space
First Claim
1. A method for detecting an object, comprising:
- applying, by a signal generator, a voltage signal to a sense coil;
determining, by a processor, an amount of change in a reactance of the sense coil from a previous reactance value for the sense coil;
determining, by the processor, an amount of change in a resistance of the sense coil from a previous resistance value for the sense coil; and
determining, by the processor, a presence and a type of the object based on;
performing an inverse tangent operation on a quotient of the amount of change in the reactance of the sense coil divided by the amount of change in the resistance of the sense coil, anddetermining the type of the object based on a result of the inverse tangent operation coinciding with a predetermined range of values corresponding to the type of the object.
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Accused Products
Abstract
An apparatus for detecting a presence of an object includes an inductive sensing coil that is configurable to generate a first magnetic field. The inductive sensing coil is configured to have an electrical characteristic that is detectable when generating the first magnetic field. The electrical characteristic is configured to vary as a function of a second time-varying magnetic field simultaneously applied to the object. The apparatus comprises a controller configured to detect a change in the electrical characteristic and determine a presence of the object based on the detected change in the electrical characteristic. The electrical characteristic comprises one or more of an equivalent resistance, an equivalent inductance, an equivalent impedance, and an impulse response of the inductive sensing coil. The object comprises one or more of a ferromagnetic object, a metallic film and a metallic foil.
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Citations
14 Claims
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1. A method for detecting an object, comprising:
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applying, by a signal generator, a voltage signal to a sense coil; determining, by a processor, an amount of change in a reactance of the sense coil from a previous reactance value for the sense coil; determining, by the processor, an amount of change in a resistance of the sense coil from a previous resistance value for the sense coil; and determining, by the processor, a presence and a type of the object based on; performing an inverse tangent operation on a quotient of the amount of change in the reactance of the sense coil divided by the amount of change in the resistance of the sense coil, and determining the type of the object based on a result of the inverse tangent operation coinciding with a predetermined range of values corresponding to the type of the object. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A non-transitory, computer-readable medium comprising code that, when executed, causes an apparatus for detecting an object to:
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applying, by a signal generator, a voltage signal to a sense coil; determine, by a processor, an amount of change in a reactance of the sense coil from a previous reactance value for the sense coil; determine, by the processor, an amount of change in a resistance of the sense coil from a previous resistance value for the sense coil; and determine, by the processor, a presence and a type of the object based on; performing an inverse tangent operation on a quotient of the amount of change in the reactance of the sense coil divided by the amount of change in the resistance of the sense coil, and determining the type of the object based on a result of the inverse tangent operation coinciding with a predetermined range of values corresponding to the type of the object. - View Dependent Claims (10, 11, 12, 13, 14)
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Specification