Magnetoresistive position sensor including an encoder wherein the magnetization extends greater than 0.5 times the pole pitch below the surface
First Claim
1. A magnetoresistive (MR) position sensor, comprising:
- (a) a rotatable cylindrical encoder wheel having plurality of alternating N and S magnetic poles spaced a constant pole pitch around the circumferential surface of said encoder wheel, adjacent ones of said N and S poles having interfacing edges parallel to the axis of rotation of said encoder wheel, and material in which said N and S magnetic poles are formed extending a distance greater than about 0.5 times said pole pitch below said circumferential surface;
(b) a first MR sensing array disposed on an insulative substrate in proximity to said circumferential surface of said encoder wheel, at a distance less than about 0.4 times said pole pitch from said circumferential surface, such as to sense rotating magnetic fields produced by said N and S poles as they pass said first MR sensing array as said encoder wheel rotates, said first MR sensing array including at least a first section comprising at least two legs extending parallel to said interfacing edges, said at least two legs being joined in series so as to form a serpentine shape, and wherein all said legs of said first section are together periodically under the influence of a single one of said N and S magnetic poles as said encoder wheel rotates; and
(c) means to apply a constant DC voltage across terminal ends of said serpentine shape.
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Accused Products
Abstract
In a preferred embodiment, a magnetoresistive (MR) position sensor, including: a rotatable cylindrical encoder wheel having a plurality of alternating N and S magnetic poles spaced a constant pole pitch around the circumferential surface of the encoder wheel, adjacent ones of the N and S poles having interfacing edges parallel to the axis of rotation of the encoder wheel; a first MR sensing array disposed on an insulative substrate in proximity to the circumferential surface of the encoder wheel, such as to sense rotating magnetic fields produced by the N and S poles as they pass the first MR sensing array as the encoder wheel rotates, the first MR sensing array including at least a first section comprising at least two legs extending parallel to the interfacing edges, the at least two legs being joined in series so as to form a serpentine shape; apparatus to apply a constant DC voltage across terminal ends of the serpentine shape.
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Citations
5 Claims
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1. A magnetoresistive (MR) position sensor, comprising:
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(a) a rotatable cylindrical encoder wheel having plurality of alternating N and S magnetic poles spaced a constant pole pitch around the circumferential surface of said encoder wheel, adjacent ones of said N and S poles having interfacing edges parallel to the axis of rotation of said encoder wheel, and material in which said N and S magnetic poles are formed extending a distance greater than about 0.5 times said pole pitch below said circumferential surface; (b) a first MR sensing array disposed on an insulative substrate in proximity to said circumferential surface of said encoder wheel, at a distance less than about 0.4 times said pole pitch from said circumferential surface, such as to sense rotating magnetic fields produced by said N and S poles as they pass said first MR sensing array as said encoder wheel rotates, said first MR sensing array including at least a first section comprising at least two legs extending parallel to said interfacing edges, said at least two legs being joined in series so as to form a serpentine shape, and wherein all said legs of said first section are together periodically under the influence of a single one of said N and S magnetic poles as said encoder wheel rotates; and (c) means to apply a constant DC voltage across terminal ends of said serpentine shape. - View Dependent Claims (2, 3, 4, 5)
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Specification