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 apparatus for sensing a rotating body includes a plurality of units to be detected provided on the rotating body; at least two sensing coils disposed to face the units to be detected; an oscillator including at least two capacitors respectively connected to the at least two sensing coils to form at least two oscillation circuits; and a rotation information calculator configured to count frequencies of at least two oscillation signals respectively output from the at least two oscillation circuits to generate a first count value and a second count value, and calculate a rotation direction of the rotating body based on a change in the first count value and a change in the second count value.

Disclosed is a compact 3-axis coil design for a magnetic tracking system. In an embodiment, compactness is achieved by using a 3-axis coil in the transmitter that includes a scaffold design with a side surface having a curved groove for guiding one or more windings of a z-axis coil, such that the physical geometry is not increased.

Circuits for controlling magnetic-based tracking systems are described. These systems may be used in virtual reality applications, for example to track in real-time the location of one or more body parts. The systems use a beacon emitting mutually orthogonal magnetic fields. On the receiver side, one or more sensors disposed on different parts of a body receive the magnetic fields. The beacon includes switching amplifiers for driving the magnetic field emitters. Being binary, these amplifiers may be controlled by binary signals. The circuits may exhibit a resonant frequency response, and may be operated off-resonance, thus providing for a better control of the magnetic fields amplitude. As a result, however, fluctuations in the envelop of the magnetic fields due to the presence of a beating tone may arise. These fluctuations may be shortened by gradually activating the drivers for the magnetic field emitters.

An apparatus for sensing movement of a rotor includes: a rotor configured to rotate along a rotation axis; a first electrode and a second electrode disposed to be spaced apart from each other and arranged to surround the rotation axis; and a conductive contact member disposed on the rotor and configured to contact the first and second electrodes as the rotor receives force in a direction different from a direction of the rotation axis.

Methods and apparatuses are provided, in which a magnetic field is measured using a coil in a first operating mode and a magnetic field is generated using the coil in a second operating mode in order to test a further magnetic field sensor.

A measurement method using an inductive proximity sensor connected to a cable, the measurement method including the following steps: applying to the cable an excitation voltage at a known reference frequency; acquiring a measurement voltage representative of the excitation current that flows in the cable and in the sensor under the effect of the excitation voltage; multiplying the measurement voltage both by a first reference signal in order to obtain a first measurement signal and also by a second reference signal in order to obtain a second measurement signal; using the first measurement signal and the second measurement signal to evaluate a measurement impedance representative of the impedance of the sensor and of the cable; using the measurement impedance to estimate the inductance of the sensor or the impedance of the sensor; and comparing the inductance of the sensor or the impedance of the sensor with a predefined detection threshold in order to obtain proximity information.

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 magnetic angular position sensor system is described herein, which includes a shaft rotatable around a rotation axis, the shaft having a soft magnetic shaft end portion. The system further includes a sensor chip spaced apart from the shaft end portion in an axial direction and defining a sensor plane, which is substantially perpendicular to the rotation axis. At least four magnetic field sensor elements are integrated in the sensor chip, with two of the magnetic field sensor elements being spaced apart from each other and are sensitive to magnetic field components in a first direction and wherein two of the magnetic field sensor elements are spaced apart from each other and are only sensitive to magnetic field components in a second direction, whereby the first and the second direction are mutually non-parallel and the first and the second direction being perpendicular to the rotation axis.

An inductive sensor device for detecting a reciprocating movement of an object includes an oscillator circuit and a processing unit. The oscillator circuit has a sensing coil configured for inducing eddy currents in the object. The processing unit is configured to count a plurality of oscillations of the oscillator circuit detected in a plurality of sampling periods, compare the oscillations with a predetermined mean value of oscillations, and determine both a speed and a position of the object based on a comparison of the oscillations with the predetermined mean value of oscillations.