Electronic linear scale using a self-contained, low-power inductive

Abstract

An electronic linear scale, which uses an induced current position transducer, includes a slider assembly mounted adjacent to an elongated beam. The slider assembly is mounted on one mounting member of a device such as a machine tool. The elongated beam is mounted on a second mounting member of the device. The first and second mounting members move relative to each other. The position of the slider assembly on the beam is indicative to of the position between the first and second mounting members. Relative movement is determined by an inductive read head mounted on the slider assembly that couples to flux modulators on the beam. The read head includes a transmitter winding and a pair of receiver windings, preferably fabricated in a planar form, carried by a common printed circuit board. The flux modulators, which can include flux disrupters and/or flux enhancers, are carried by the beam and modulate the magnetic fields produced by the transmitter. Thus, the receiver windings produce output voltages corresponding to the overlap between the modulators and the receiver windings. Signal processing electronics are connected to the read head and determine the relative positions of the first and second mounting members by monitoring the output of the receiver windings. A digital display displays the determined position. The relatively insensitive nature of the induced current position transducer to contaminants allows the linear scale to function with improved reliability when operating in industrial environments. Low power operation of the linear scale is possible.