US 6,486,656 B1Granted

Magnetoresistive die and position sensor

AssigneeDelphi Technologies, Inc.

InventorThaddeus Schroeder

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Abstract

A galvanomagnetic position sensor (36, 18) wherein a single die MR sensor (22, 22′) senses the rotation of an end face (14) of a motor shaft (12) which is made of a ferromagnetic material and generates three sinusoidal voltage signals with 120 degree phase shifts. In a first implementation, an MR die incorporating a plurality of matched pie-shaped MR elements (MR1, MR2, MR3, MR4, MR5, MR6) collectively form a circular area. When the motor shaft rotates, a tooth (18) of the end face sweeps past the MR elements resulting in resistance modulation of each MR element between a maximum resistance and a minimum resistance whereby three sinusoidal voltage signals spaced 120 degrees apart are provided, via OpAmps (AMP1, AMP2, AMP3) or voltage dividers and OpAmps (AMP1′, AMP2′). From these voltage signals the shaft rotative position is known. In a second implementation of the present invention, the single MR sensor consists of an MR die (22″) wherein each of a plurality of MR elements (23″) consists of three interdigitated electrically isolated MR segments collectively forming a circular area, wherein OpAmps are obviated and the sensor circuit is totally passive.

Claims10

Dependent claims

A position sensor comprising:

a shaft having a magnetic irregularity located at an end face thereof, said end face defining a plane perpendicular to a center line of the shaft;
and
a galvanomagnetic sensor covering a predetermined area wherein the center thereof is aligned with the center line of the shaft adjacent the end face at an orientation parallel to said plane, said galvanomagnetic sensor comprising a plurality of substantially pie shaped galvanomagnetic sensor elements, and circuit means for providing a voltage signal therefrom which is responsive to rotative position of the magnetic irregularity;
wherein as the shaft rotates relative to the galvanomagnetic sensor, the galvanomagnetic sensor provides a plurality of periodically variable voltage signals having predetermined phase spacing therebetween, wherein the voltage signals are indicative of rotative position of the shaft;
wherein said plurality of galvanomagnetic sensor elements comprises:
a substantially pie shaped first magnetoresistor;
a substantially pie shaped second magnetoresistor;
a substantially pie shaped third magnetoresistor;
a substantially pie shaped fourth magnetoresistor;
a substantially pie shaped fifth magnetoresistor;
and
a substantially pie shaped sixth magnetoresistor;
wherein a difference between two sums, with a first sum comprising an addition of any three consecutive magnetoresistors of the first, second, third, fourth, fifth and sixth magnetoresistors, and a second sum comprising an addition of a remaining three consecutive magnetoresistors, is a periodic function of rotative position of said magnetic irregularity;
wherein said difference comprises any one of three groups, wherein a first group comprises the first magnetoresistor plus the second magnetoresistor plus the third magnetoresistor minus the fourth magnetoresistor minus the fifth magnetoresistor minus the sixth magnetoresistor;
a second group comprises the third magnetoresistor plus the fourth magnetoresistor plus the fifth magnetoresistor minus the sixth magnetoresistor minus the first magnetoresistor minus the second magnetoresistor;
and a third group comprises the fifth magnetoresistor plus the sixth magnetoresistor plus the first magnetoresistor minus the second magnetoresistor minus the third magnetoresistor minus the fourth magnetoresistor;
wherein said circuit means provides a matched current source independently for each of said first, second, third, fourth, fifth and sixth magnetoresistors.

14 more elements

A position sensor comprising:

a shaft having a magnetic irregularity located at an end face thereof, said end face defining a plane perpendicular to a center line of the shaft;
and
a galvanomagnetic sensor covering a predetermined area wherein the center thereof is aligned with the center line of the shaft adjacent the end face at an orientation parallel to said plane, said galvanomagnetic sensor comprising a plurality of substantially pie shaped galvanomagnetic sensor elements, and circuit means for providing a voltage signal therefrom which is responsive to rotative position of the magnetic irregularity;
wherein as the shaft rotates relative to the galvanomagnetic sensor, the galvanomagnetic sensor provides a plurality of periodically variable voltage signals having predetermined phase spacing therebetween, wherein the voltage signals are indicative of rotative position of the shaft;
wherein said plurality of galvanomagnetic sensor elements comprises a plurality of substantially pie shaped magnetoresistor elements, each magnetoresistor element thereof comprising a plurality of mutually interdigitated magnetoresistor segments;
wherein said circuit means serially connects a selected magnetoresistor segment of each magnetoresistor element, respectively, to thereby form a plurality of groups of the interdigitated magnetoresistor segments, wherein each group provides a respective periodically varying voltage signal of the plurality of periodically varying voltage signals.

3 more elements

Dependencies are inferred from the claim text.