Patent ID: 6580264
Filing Date: 2003-06-17
Classification: G01D

Abstract:
A position transducer comprising:a detection coil excited with a high frequency; a magnetic core inserted in the detection coil such that the magnetic core may be moved with respect to the detection coil along a center axis of the detection coil; an auxiliary coil lap-wound on an end of the detection coil and driven in phase with the detection coil; and means for detecting a relative position of the magnetic core with respect to the detection coil based upon an impedance change of the detection coil, wherein when the magnetic core is at a reference position inside the detection coil, the impedance of the auxiliary coil is equal to the impedance of the detection coil and the means for detecting a relative position determines a difference in output between the detection coil and the auxiliary coil to detect a position of the core relative to the detection coil.