Magnetic field sensor for sensing a movement of a target object
First Claim
Patent Images
1. A magnetic field sensor for sensing a movement of a ferromagnetic target object having ferromagnetic target object features with a target feature width, comprising:
- a substrate;
a first magnetoresistance element disposed upon the substrate for generating a first signal responsive to movement of the ferromagnetic target object features;
a second magnetoresistance element disposed upon the substrate for generating a second signal responsive to movement of the ferromagnetic target object features;
a first combining circuit disposed upon the substrate and configured to combine the first signal and the second signal to generate a feature signal having a largest value when a ferromagnetic target object feature is centered with the first and second magnetoresistance elements;
a second combining circuit disposed upon the substrate and configured to combine the first signal and the second signal to generate an edge signal having a largest value when the first magnetoresistance elements is on one side of an edge of a target feature and the second magnetoresistance element is on the other side of the same edge, wherein the feature signal and the edge signal are analog signals; and
an electronic circuit disposed upon the substrate, coupled to receive the feature signal and the edge signal, wherein the electronic circuit is operable to compare the edge signal with one or more threshold values to generate a first two-state signal and operable to compare the feature signal with another one or more threshold values to generate a second two-state signal, wherein an output signal generated by the magnetic field sensor comprises a signal encoding that identifies an alignment of state transitions of a selected one of the first or the second two-state signal.
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Abstract
A magnetic field sensor operates as a motion detector for sensing a movement of a ferromagnetic target object having features. The magnetic field sensor has a plurality of magnetoresistance elements to generate, in a first channel, a feature signal indicative of a proximity of a feature of a ferromagnetic target object and, in a second channel, an edge signal indicative of a proximity of an edge of a feature of a ferromagnetic target object.
353 Citations
33 Claims
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1. A magnetic field sensor for sensing a movement of a ferromagnetic target object having ferromagnetic target object features with a target feature width, comprising:
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a substrate; a first magnetoresistance element disposed upon the substrate for generating a first signal responsive to movement of the ferromagnetic target object features; a second magnetoresistance element disposed upon the substrate for generating a second signal responsive to movement of the ferromagnetic target object features; a first combining circuit disposed upon the substrate and configured to combine the first signal and the second signal to generate a feature signal having a largest value when a ferromagnetic target object feature is centered with the first and second magnetoresistance elements; a second combining circuit disposed upon the substrate and configured to combine the first signal and the second signal to generate an edge signal having a largest value when the first magnetoresistance elements is on one side of an edge of a target feature and the second magnetoresistance element is on the other side of the same edge, wherein the feature signal and the edge signal are analog signals; and an electronic circuit disposed upon the substrate, coupled to receive the feature signal and the edge signal, wherein the electronic circuit is operable to compare the edge signal with one or more threshold values to generate a first two-state signal and operable to compare the feature signal with another one or more threshold values to generate a second two-state signal, wherein an output signal generated by the magnetic field sensor comprises a signal encoding that identifies an alignment of state transitions of a selected one of the first or the second two-state signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A magnetic field sensor for sensing a movement of a ferromagnetic target object having ferromagnetic target object features with a target feature width, comprising:
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a substrate; a first magnetoresistance element disposed upon the substrate for generating a first signal responsive to movement of the ferromagnetic target object features; a second magnetoresistance element disposed upon the substrate for generating a second signal responsive to movement of the ferromagnetic target object features; a first combining circuit disposed upon the substrate and configured to combine the first signal and the second signal to generate a feature signal having a largest value when a ferromagnetic target object feature is centered with the first and second magnetoresistance elements; and a second combining circuit disposed upon the substrate and configured to combine the first signal and the second signal to generate an edge signal having a largest value when the first magnetoresistance elements is on one side of an edge of a target feature and the second magnetoresistance element is on the other side of the same edge, wherein the feature signal and the edge signal are analog signals, wherein the first and second magnetoresistance elements are disposed in a line parallel to a tangent to a direction of movement of the ferromagnetic target object, wherein the first and second magnetoresistance elements are disposed with a spacing between about one half and about two times the target feature width, the magnetic field sensor further comprising; an electronic circuit disposed upon the substrate, coupled to receive the feature signal and the edge signal, wherein the electronic circuit is operable to compare the edge signal with one or more threshold values to generate a first two-state signal and operable to compare the feature signal with another one or more threshold values to generate a second two-state signal, wherein an output signal generated by the magnetic field sensor comprises a signal encoding that identifies an alignment with state transitions of a selected one of the first or the second two-state signal. - View Dependent Claims (32, 33)
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Specification