A device for measuring a measurement variable, wherein a first inductance is replenished with a capacitance to form a parallel resonant circuit and the first inductance is coupled to a measurement inductance.

Inductance values are measured though the use of a charge transfer based measurement system. During a first phase, a target inductor is connected to an energy source to allow current through an inductor to increase. In a second phase, the inductor is disconnected from the energy source, to allow the current to decrease, and to facilitate transfer of charge to a capacitor. The phases may be repeated, and a count is kept of the number of repetitions.

Systems and methods for vehicle detection and assessments of loop deterioration rely on changes in inductance of a loop sensor. The conductive element of the loop sensor is modeled using one or more inductances and one or more resistances. Sets of stimuli at different frequencies are provided to the loop sensor, and the resulting responses form the basis for vehicle detection and for an assessment whether the loop sensor has deteriorated.

The described techniques are directed to inductive torque sensors that implement independent target coil and pickup coil systems. By utilizing the various principles of inductive angle sensors, and as a result of the specific physical arrangement of target coils, the inductive torque sensor may independently obtain a rotational position (i.e., mechanical angle) of the rotatable input shaft via one pickup coil system, and a rotational position (i.e., mechanical angle) of the rotatable output shaft via another pickup coil system. Combiner circuitry is also provided to calculate the torsion angle using the signals induced in each of two separate pickup coil systems. By using different k-fold symmetry periodicities in the target coils with respect to the coil configurations, the inductive torque sensor advantageously reduces or eliminates mutual coupling between the different target coil systems and provide robustness to stray or external electromagnetic fields.

A two-wire displacement sensor device includes an LC oscillation circuit including a coil whose inductance changes in accordance with a displacement amount of an object and an oscillation unit provided with capacitors and amplifying elements; and an interface unit serving as a signal output unit and a power supply input unit. The interface unit includes a constant current circuit that outputs at least two current values.

An instrument playing apparatus has: a movable member configured to be displaced responsive to a playing operation of a user; a detection part formed from a magnetic or conductive body and disposed on the movable member; and a filter that includes a coil. The filter has a frequency response that changes depending on a distance between the detection part and the coil, and generates a detection signal from a reference signal.

This disclosure provides systems, methods and apparatus for detecting foreign objects. In one aspect an apparatus for detecting a presence of an object is provided. The apparatus includes a resonant circuit having a resonant frequency. The resonant circuit includes a sense circuit including an electrically conductive structure. The apparatus further includes a coupling circuit coupled to the sense circuit. The apparatus further includes a detection circuit coupled to the sense circuit via the coupling circuit. The detection circuit is configured to detect the presence of the object in response to detecting a difference between a measured characteristic that depends on a frequency at which the resonant circuit is resonating and a corresponding characteristic that depends on the resonant frequency of the resonant circuit. The coupling circuit is configured to reduce a variation of the resonant frequency by the detection circuit in the absence of the object.

A method of manufacturing a proximity sensor and a manufacturing system for the proximity sensor capable of improving detection precision or expanding a detectable range are provided. A method of manufacturing a proximity sensor outputting presence or absence of a detection object or a position of the detection object as a detection result is provided. The manufacturing method includes: disposing the proximity sensor in a temperature-changeable environment; setting an environment of the proximity sensor to a plurality of different temperatures respectively and storing temperature detected by the temperature detection part of the proximity sensor in association with the detection result output by the control calculation part at each temperature; determining a characteristic parameter unique to a target proximity sensor based on the stored temperature and detection result; and setting the determined characteristic parameter for the target proximity sensor.

In accordance with one embodiment of the present disclosure, an inductive sensor assembly includes a shaft and a multilayered printed circuit board (PCB). The shaft includes a first end. The first end has a bottom surface. A target including a flat forming a straight edge is integrally formed into the first end of the shaft. The PCB includes a transmitter coil and a two part receiving coil. The two part receiving coil has a first receiving coil and a second receiving coil. The first receiving coil is on a different layer of the PCB than the second receiving coil in an axial direction. The target is rotated about a central axis of the two part receiving coil. The straight edge of the target and the bottom surface is detected by the two part receiving coil.

A detector circuit for detecting a variation in inductance of the magnetic circuit of an inductive displacement sensor, the detector circuit including: a first flip flop arranged to supply a first signal including a voltage pulse of necessary and sufficient duration to charge a coil to a threshold current, wherein the first signal is applied to a first terminal of the coil; a pulse generator configured to supply a reference signal comprising a reference pulse; a clock signal generator arranged to trigger the voltage pulse and the reference pulse periodically and simultaneously; and a second flip flop arranged to generate an output signal taking a status of the first signal on a trailing edge of the reference pulse.