Patent ID: 6833697
Filing Date: 2004-12-21
Classification: G01D,G01R

Abstract:
A method for sensing relative linear position within a predetermined range utilizing a magnetoresistive sensing bridge circuit, said method comprising the steps of:locating a wheatstone magnetoresistive sensing bridge circuit within a magnet substantially toward and proximate to an end of said magnet, wherein said wheatstone magnetoresistive sensing bridge circuit comprises a plurality of anisotropic magnetoresistors including at least four anisotropic magnetoresistors thereof arranged in an orthogonal layout pattern; positioning said magnet and said wheatstone magnetoresistive sensing bridge circuit in proximity to a ferrous rib target associated with a slider that moves along a shaft when a torque is applied to said shaft, such that said wheatstone magnetoresistive sensing bridge circuit is biased by a magnetic bias field of said magnet, wherein said magnetic bias field saturates said wheatstone magnetoresistive sensing bridge circuit and a response of said plurality of anisotropic magnetoresistors thereof; detecting an output signal from said wheatstone magnetoresistive sensing bridge circuit during a saturation mode of said wheatstone magnetoresistive sensing bridge circuit, wherein said output signal is produced by a change in an angle of said magnetic bias field with respect to said plurality of anisotropic magnetoresistors, and wherein said output signal determines a target position with respect to a torque applied to said shaft; and determining a relative target position of said ferrous rib target with a desired movement range utilizing a linearly varying output signal generated by said wheatstone magnetoresistive sensing bridge circuit, wherein said linearly varying output signal is produced by a change in an angle of said magnetic bias field with respect to said plurality of anisotropic magnetoresistors as said ferrous rib target slides by and proximate to said end of said magnet wherein said wheatstone magnetoresistive sensing bridge is located.