Patent ID: 6259249
Filing Date: 2001-07-10
Classification: G01B,G01D

Abstract:
An induction-type position measuring apparatus comprising:a first member;a second member having a measurement axis and being movably arranged along the measurement axis with a predefined gap between the first and second members;a drive wire disposed on the first member the drive wire producing a first variable magnetic field in response to an alternating current from a drive signal source;an array of electromagnetic coupling devices laid out on the second member along the measurement axis at constant intervals, each of the electromagnetic coupling devices generating an induced current due to coupling with the first variable magnetic field generated by the drive wire, and generating a second variable magnetic field substantially perpendicular to the first variable magnetic field in response to the induced current at a position physically spaced apart from a coupling portion with the first variable magnetic field; anda variable magnetic field detecting portion having at least one detection wire, wherein each detection wire does not form closed loops parallel to the surface of the first member and is disposed on the first member substantially perpendicular to the drive wire, the variable magnetic field detecting portion providing at least one output signal due to coupling with the second variable magnetic field from the electromagnetic coupling devices, each at least one output signal with relative displacement of the first and second members.