Murata Machinery, Ltd.

Ryohei Kido

Tetsuya Shimizu

Kentaro Otomo

A displacement detection device includes a detection signal processor including a first differential amplifier a to output a first AC signal acquired by synthesizing a cosine function and a minus cosine function, a second differential amplifier to output a second AC signal acquired by synthesizing a sine function and a minus sine function, and a processor to determine, at least at a start of use of the displacement detection device, a value that substantially indicates a phase displacement amount between an excitation signal and the first AC signal and the second AC signal. When detecting displacement, the processor is configured or programmed to perform an arctangent computation using values of the first and second AC signals acquired at a timing based on the value that is determined, and output relative displacement information of a scale with respect to a magnetic detection head.

Displacement detection device

A processing device of a displacement detection device includes an AD conversion device, a switching circuit, and an arithmetic processing unit. The AD conversion device has first and second AD conversion units. The switching circuit periodically switches between a first connection mode in which a first differential signal is AD-converted by the first AD conversion unit and a second differential signal is AD-converted by the second AD conversion unit, and a second connection mode in which the first differential signal is AD-converted by the second AD conversion unit and the second differential signal is AD-converted by the first AD conversion unit. The arithmetic processing unit outputs displacement information of a scale based on an addition average value of the first differential signals output from the first and second AD conversion units and an addition average value of the second differential signals output from the first and second AD conversion units.

A magnetic response section provided by a scale of a magnetic linear sensor is configured so that changes in magnetic influence on a magnetic detection head appear alternately and repeatedly every first pitch in a displacement detection direction. The magnetic detection head is provided on one side of the scale in the first direction, which is a direction perpendicular to the displacement detection direction, and provided with a base substrate section and a plurality of signal output sections. The signal output sections are arranged on an insulating plate and in the displacement detection direction at a second pitch based on a first pitch. The first conductive pattern and the second conductive pattern included by each of the signal output sections are formed to arrange coil elements side by side in an elongated area in a second direction orthogonal to both the displacement detection direction and the first direction.

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Kyoto, Japan

Ryohei Kido