Kayaba Kogyo Kabushiki Kaisha

Yoichi Shimoura

Masakazu Nakazato

Yoshitsugu Tsuchiya

Hideki Yamagata

Kazuhisa Ikenoya

Richard J Hellinga

A magnetic scale formed by arranging a non-magnetic material at a predetermined pitch in the direction of motion of a piston rod, and a pair of magnetic sensors which output two sine waves with a phase difference of 90.degree. corresponding to the pitch of said magnetic scale, are provided. The peak voltages of the sensor output at each pitch of the magnetic scale are updated and stored. Center voltages are computed from the peak voltages at each pitch, and a coarse displacement is computed based on the result of comparing the center voltages and sensor outputs. Correction coefficients of the sensor outputs are computed from the peak voltages and center voltages, and the sensor outputs are compensated based on these correction coefficients. A fine displacement is then computed by an inverse trigonometric function from the two corrected signals, and a displacement signal is output by adding the coarse displacement to the fine displacement.

Displacement detecting apparatus

System for processing position signals that are reponsive to

System for processing fine position signals pulse-width modulates signals from two magnetic sensors for producing sinusoidal wave signals different from each other in phase by a quarter cycle in correspondence with the scale pitches, then switches the phase so as to bring the pair of pulse-modulated signals in phase with each other, then calculates the weight constants for the pair of pulse-width modulated signals in phase in order that of said pair of pulse-width modulated signals in phase, any one having a higher linearity will be treated at a handsome rate, and then subjects said pulse-width modulated signals to weighted mean by the use of the resultant weight constants, with the result that the pair of pulse-width modulated signals will become free from disorder at the switching point, thereby producing signals of a high accuracy representing fine positions corresponding to the scale pitch divided at regular intervals.

System for processing position signals to improve resolution of the

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Sagamihara, Japan

Yoichi Shimoura