Magnetoresistive speed and direction sensing method and apparatus
AssigneeHoneywell International Inc.
InventorsMichael J. Haji-Sheikh, Mark Plagens, Robert Kryzanowski
Life of this patent
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Abstract
The ring magnet speed and direction sensing scheme according to the present invention addresses many of the shortcomings of the prior art. In accordance with various aspects of the present invention, a pair of bridges placed on the same semiconductor chip are provided for sensing the passing of north/south transition points on a ring magnet. In accordance with an exemplary embodiment, the bridge contains a first group of runners that are perpendicular to a second group of runners. The bridges are placed to cause the signal from one bridge to slightly follow the signal from the other bridge. Placement of the bridges on the same chip enables highly accurate readings.
Claims34
A method for implementing a ring-type magnetoresistive sensor, the method comprising the steps of:
- generating a variable magnetic field by a ring magnet;
- and
- introducing a first bridge and a second ridge, each adjacent to the ring magnet, the first bridge and second bridge each comprising a first set of runners and a second set of runners, wherein the first set of runners is approximately perpendicular to the second set of runners, the first set of runners and the second set of runners being electrically influenced by the magnetic field and each bridge generating at least a direct facing relationship signal and a direct transitional relationship signal as the ring magnet moves;
- the second bridge being located a distance from the first bridge such that a phase difference exists between the signals of th two bridges;
- wherein the first and second bridges are oriented with respect to the ring magnet such that the first set of runners is substantially in parallel to a radial line from the center of the ring magnet and the second set of runners is substantially perpendicular to the radial line from the center of the ring magnet.
A method of forming a magnetic speed and direction detection device, the method comprising the steps of:
- introducing a first set of runners and a second set of runners wherein the first set of runners is approximately perpendicular to the second set of runners, configuring the first set of runners with the second set of runners as a first Wheatstone bridge, the first Wheatstone bridge configured to generate at least a first output signal in the presence of a variable magnetic field;
- and
- introducing a second Wheatstone bridge, the second Wheatstone bridge configured to generate at least a second output signal in the presence of the variable magnetic field;
- the second Wheatstone bridge located a distance from the first Wheatstone bridge;
- the distance being selected to create a phase shift between the first output signal and the second output signal;
- wherein the first and second Wheatstone bridges are oriented with respect to a ring magnet such that the first set of runners is substantially in parallel to a radial line from the center of the ring magnet and the second set of runners is substantially perpendicular to the radial line from the center of the ring magnet.
An apparatus to sense the speed and direction of a ring magnet, the apparatus comprising:
- at least a first set of runners and at least a second set of runners adjacent to the moving member, wherein the first set of runners is approximately perpendicular to the second set of runners;
- the first set of runners and the second set of runners configured as a first Wheatstone bridge, the first Wheatstone bridge configured to generate at least a first output signal as the ring magnet moves and as a magnetic field associated with the ring magnet electrically influences at least one of the first and second set of runners;
- and
- the apparatus further comprising a second Wheatstone bridge located a distance from the first Wheatstone bridge, the second Wheatstone bridge configured to generate at least a second output signal as the ring magnet moves and in the presence of the magnetic field associated with the ring magnet;
- and the distance between the first and second Wheatstone bridge selected to create a phase shift between the first and second output signals;
- wherein the first Wheatstone bridge is oriented with respect to the ring magnet such that the first set of runners is substantially in parallel to a radial line from the center of the ring magnet and the second set of runners is substantially perpendicular to the radial line from the center of the ring magnet.
An apparatus to sense the speed of a ring magnet, the apparatus comprising:
- at least a first set of runners and at least a second set of runners adjacent to the ring magnet, wherein the first set of runners is approximately perpendicular to the second set of runners;
- the first set of runners and the second set of runners configured as a Wheatstone bridge, the Wheatstone bridge configured to generate at least an output signal as the ring magnet moves and as a magnetic field associated with the ring magnet electrically influences at least one of the first and second set of runners;
- wherein the Wheatstone bridge is oriented with respect to the ring magnet such that the first set of runners is substantially in parallel to a radial line from the center of the ring magnet and the second set of runners is substantially perpendicular to the radial line from the center of the ring magnet.
Dependencies are inferred from the claim text.