Matsushita Electric Works, Ltd.

Katsuhiro Teramae

Yuji Takada

Motoo Ikari

Hideki Fukuzono

Shintaro Yamamoto

Makio Asai

A sensor is configured to comprise a detection coil into which a metallic shaft to be detected, a reference coil having the same specifications as those for the detection coil , drive oscillator circuits for generating high-frequency magnetic fields in the detection coil and the reference coil , and a comparator for outputting a detection signal, which indicates that the shaft to be detected is detected, according to the difference between an oscillation signal, which is outputted from the detection coil according to an inserted state of the shaft to be detected, and an oscillation signal outputted from the reference coil

Magnetic sensor for detecting the angular displacement of a rotating shaft

A rotary speed measurement device includes an oscillator including a resonant circuit with a coil which conducts a resonant current to develop a magnetic field therearound. A wheel is connected to rotate together with a rotating member and is provided along circumference with alternately arranged first and second marks which causes different magnetic effect on the magnetic field. The coil is disposed adjacent the wheel so as to sense the magnetic effect and provide a corresponding voltage Vs. An analyzer is provided to give a parameter Vsub based upon voltage Vs and to compare the parameter with a predetermined threshold V.sub.TH to give a pulse when the parameter exceeds the threshold as indicative of that the wheel rotates by an increment corresponding to an angular distance between the first mark and the adjacent second mark. The pulse is counted by a counter within a unit time to obtain a rotary speed of the wheel. The device is characterized to include a reference circuit connected in circuit with the resonant circuit to provide a reference voltage Vr which is in phase with voltage Vs and varies at a different rate from voltage Vs in response to the inductance change in the coil, and to include a differential low-pass filter which is connected to receive voltage Vs and reference voltage Vr for providing a difference therebetween as the parameter Vsub to be compared at the analyzer with the threshold V.sub.TH. Thus, voltage difference between Vs and Vr can represent the parameter of which amplitude is kept within a limited range irrespective of the distance between the coil and the wheel, whereby realizing successful rotary speed measurement without necessitating to care the relative position of the rotor to the wheel, and extending the measurable distance between the coil and the wheel.

Device for measuring rotating speed having a resonent circuit and a

An optical displacement measuring system utilizing a triangulation is so arranged that light receiving means receives light reflected back from an object to be measured and generates a pair of output signals having mutually opposite values and responsive to a position of a light spot on the light receiving means. An operational means performs addition and subtraction over the pair of positional output signals and to obtain a ratio between the both added and subtracted output signals for generating a measured distance signal, and a linearity correcting means provides a mathematical correction number to one of the pair of positional output signals to correct any nonlinearity of the measured distance signal, for providing the linearity to the measured distance signal with a simple arrangement.

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Osaka, Japan

Katsuhiro Teramae