Patent ID: 6909279
Filing Date: 2005-06-21
Classification: G01D

Abstract:
1. A position sensor comprising: a constant current circuit for outputting a constant current which is obtained by superposing an alternate current having a given frequency and a given amplitude over a direct current having a given amplitude; a detecting section including at least a detection coil to which said constant current is supplied; a core made of a magnetic material, said core being displaced relative to said detection coil in an axial direction of said detection coil; and a signal processing circuit for outputting a displacement signal indicative of position data of said core relative to said detection coil based on a peak value of an output voltage from said detecting section upon supply of said constant current, wherein at least one of a ratio of the direct current to the alternate current of said constant current, a ratio of an alternate current component to a direct current component of an impedance in said detecting section, a temperature characteristic of the ratio of the direct current to the alternate current of said constant current, and a temperature characteristic of the ratio of the alternate current component to the direct current component of the impedance in said detecting section is set in such a manner that a margin of fluctuation of a temperature coefficient of the peak value of the output voltage from said detecting section in a whole displacement zone of said core relative to said detection coil is smaller than a margin of fluctuation of a temperature coefficient of the alternate current component of the impedance in said detecting section at said given frequency in the whole displacement zone of said core relative to said detection coil.