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US 2021/0262831 A1Published application
Orientation independent magnetic field sensor
AssigneeAllegro MicroSystems, LLC
InventorsAndrea Foletto, Yannick Vuillermet, Florian Kulla
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Abstract
Methods and apparatus for an orientation insensitive speed sensor. Magnetic field sensing elements can be located on a circle, for example, to generate first and second channel signals which can be combined to generate an output signal. The location of the magnetic field sensing elements reduces the effects of stray fields. Embodiments can include true power own state processing to determine target position during start up.
Claims37
A sensor, comprising:
- at least a first pair of sensing elements comprising first and second magnetic field sensing elements and a second pair of sensing elements comprising third and fourth magnetic field sensing elements for measuring field change in response to movement of a target, wherein each of the magnetic field sensing elements in the first and second pairs of sensing elements is located in a planar circle, wherein each of the magnetic field sensing elements has its most sensitive direction to a magnetic field radial to the planar circle, wherein the first magnetic field sensing element is positioned to be diametrically opposite the second magnetic field sensing element, and wherein the third magnetic field sensing element is positioned to be diametrically opposite the fourth magnetic field sensing element, wherein the first and second magnetic field sensing elements are configured to measure positive field in the same direction and the third and fourth magnetic field sensing elements are configured to measure positive field in the same direction, wherein a plane of the planar circle is configured for positioning to be parallel to a tangent of the target which has teeth and valleys, wherein the sensor is configured to subtract a voltage generated by the second magnetic field sensing element from a voltage generated by the first magnetic field sensing element to provide a first voltage, and wherein the sensor is configured to subtract a voltage generated by the third magnetic field sensing element from a voltage generated by the fourth magnetic field sensing element to generate a second voltage, and wherein the sensor is configured to combine the first and second voltages to generate a third voltage.
A method, comprising:
- employing at least a first pair of sensing elements comprising first and second magnetic field sensing elements and a second pair of sensing elements comprising third and fourth magnetic field sensing elements for measuring field change in response to movement of a target, wherein each of the magnetic field sensing elements in the first and second pairs of sensing elements is located in a planar circle, wherein each of the magnetic field sensing elements has its most sensitive direction to a magnetic field radial to the planar circle, wherein the first magnetic field sensing element is positioned to be diametrically opposite the second magnetic field sensing element, and wherein the third magnetic field sensing element is positioned to be diametrically opposite the fourth magnetic field sensing element, wherein the first and second magnetic field sensing elements are configured to measure positive field in the same direction and the third and fourth magnetic field sensing elements are configured to measure positive field in the same direction, wherein a plane of the planar circle is configured for positioning to be parallel to a tangent of the target which has teeth and valleys;
- subtracting a voltage generated by the second magnetic field sensing element from a voltage generated by the first magnetic field sensing element to provide a first voltage;
- subtracting a voltage generated by the third magnetic field sensing element from a voltage generated by the fourth magnetic field sensing element to generate a second voltage;
- and
- combining the first and second voltages to generate a third voltage.
2 more elements
A sensor, comprising:
- a means for sensing comprising a plurality of magnetic field sensing elements for measuring field change in response to movement of a target, wherein each of the magnetic field sensing elements is located in a planar circle positioned to be diametrically opposite another of the magnetic field sensing elements, wherein a plane of the planar circle is configured for positioning to be parallel to a tangent of the target which has teeth and valleys;
- and
- a means for processing a voltage generated by a second one of the magnetic field sensing element from a voltage generated by a first one of the magnetic field sensing elements to provide a first voltage, subtracting a voltage generated by a third one of the magnetic field sensing elements from a voltage generated by a fourth one of the magnetic field sensing elements to generate a second voltage, and combining the first and second voltages to generate a third voltage.
Dependencies are inferred from the claim text.