Panasonic Corporation

Panasonic Intellectual Property Management Co., Ltd.

Kunitaka Okada

Masahisa Niwa

Sukoya Tawaratsumida

Jiri Kutej

Fumihiro Kasano

Timothy J Warneck

Yukiko Nishida

Kazuma Haraguchi

Itsushi Tadamasa

Rudolf Hajek

A processor of a position detection device intermittently performs an acquisition process during a measurement period to acquire a detection signal induced in a detection coil depending on the position of an object by driving an excitation coil. The processor configured to monitor whether or not the processor is executing the acquisition process without driving the excitation coil during a monitoring period set before the measurement period of the processor, and the processor is configured to execute a predetermined process when the processor is executing the acquisition process.

Position detection device

A position sensor includes a detector, an oscillation circuit, a signal processing circuit, and a resonance circuit having a detection coil and a capacitor. The oscillation circuit forms a negative feedback loop from: an amplitude detection circuit that detects an amplitude of an oscillation signal outputted from the resonance circuit; an integrating circuit that outputs a signal corresponding to a difference between a predetermined reference voltage and the amplitude of the oscillation signal; a negative conductance control circuit that, based on the output of the integrating circuit, controls the negative conductance of the oscillation circuit such that the amplitude of the oscillation signal is equals to the predetermined reference voltage; and an operational amplifier that adjusts such that the oscillation voltage of the resonance circuit is equal to the applied voltage of the negative conductance control circuit.

Position sensor

A mode detector in a sensor interface is configured to detect a mode specified by a mode signal when an input signal received from a side of a first terminal is the mode signal. A communication portion in the interface transmits an electric signal, obtained from a sensor circuit, to a side of a second terminal when a mode detected with the detector is a sensor output mode. The communication portion receives an input signal from the side of the first terminal while transmitting an output signal to the side of the second terminal, when a mode detected with the detector is a communication mode.

Sensor device and sensor interface

A proximity sensor has an oscillation circuit, an amplitude measurement circuit, a control circuit and a signal processing circuit. The oscillation circuit has an LC resonant circuit and an oscillation control circuit that is configured to supply an electric current to the LC resonant circuit to generate oscillating voltage across the LC resonant circuit. The amplitude measurement circuit is configured to produce an amplitude signal corresponding to the amplitude of the oscillating voltage. The control circuit is configured to set the negative conductance of the oscillation control circuit to a critical value by which the LC resonant circuit can oscillate based on the amplitude signal. The signal processing circuit is configured to produce a distance signal corresponding to the distance between an object and the sensing coil based on a parameter associated with the negative conductance.

Proximity sensor

The position sensor includes a moving member configured to be displaced in response to displacement of a measurement target, a resonant unit, an oscillation unit, a signal processing unit, an output unit, a signal absence detection unit, and a low-pass filter. The resonant unit includes a detection coil. The oscillation unit is configured to output an oscillation signal. The signal absence detection unit is configured to judge whether or not the oscillation signal is output from the oscillation unit. The low-pass filter is configured to have a cut-off frequency which passes the oscillation signal corresponding to the resonant frequency of the resonant unit in a normal condition, but blocks the oscillation signal output from the oscillation unit when the resonant unit sees an oscillation at an abnormal frequency.

The physical quantity measurement device involves a terminal unit, a sensor, a storage unit, an output unit, a communication unit, a control unit, and a discriminating unit. The terminal unit has a power terminal, an output terminal, and a ground terminal. The communication unit uses the power terminal in order to receive a serial signal from an external device. The control unit has an adjusting mode and a normal mode. The discriminating unit decides that the external device requests either the adjusting mode or the normal mode based on whether or not an electrical potential of each of the power terminal and the output terminal satisfies a predetermined condition. The control unit selects the normal mode when the discriminating unit decides that the external device requests the normal mode, and selects the adjusting mode when the discriminating unit decides that the external device request the adjusting mode.

Physical quantity measurement device

An oscillator circuit outputs an oscillator signal with a frequency corresponding to an inductance of a displacement detector coil. An oscillation cycle measurement circuit measures a cycle of the oscillator signal output from the oscillator circuit, and outputs a signal corresponding to the measured cycle. A squaring circuit calculates and outputs a square of the signal output from the oscillation cycle measurement circuit. By the calculation and output of the square of the oscillator signal cycle, a square root component of the product of inductance and capacitance components is eliminated, so that the output signal changes linearly relative to the displacement of a displacement body. As a result, the linearity of the output signal relative to the displacement of the displacement body can be improved.

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Osaka, Japan

Kunitaka Okada