US 6,259,249 B1 · Induction-type position measuring apparatus

Abstract

An inductive linear encoder (10) has a position sensor (1) and scale (2) which are movably disposed relative to each other. The sensor (1) is with a drive wire (3) to which an alternating current is supplied, and one set of detection wires (4a-4d) at right angles to the drive wire (3) in the same plane. The scale (2) is configured including an elongate substrate (7) having its surface on which a series combination of conductive closed loop patterns (8) are periodically arranged at equal intervals. These conductive closed loop (8) are linearly laid out on the substrate (7) in the relative movement direction. Each loop (8) consists essentially of a reception conductor segment (8a) and signal transmit conductor segments (8b, 8c) integral with the former (8a). The receive conductor segment (8a) is responsible for generation of an induced current due to a first variable magnetic field creatable from the drive coil (3). The transmit conductor segments (8b, 8c) are to create second variable magnetic fields that are opposite in polarity to each other and are perpendicular to the first magnetic field. Creation of such second magnetic fields results in flow of an induced current in the detector wire (4) of sensor (1), which in turn acts as a position detection output current.

Claims13

Dependent claims

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;
and
a 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.

3 more elements

Dependencies are inferred from the claim text.

Induction-type position measuring apparatus

Life of this patent

Induction-type position measuring apparatus

Life of this patent

Abstract

Claims13