A magnetically responsive member is disposed on a rotating member along the circumference of the rotating member in such a manner that the magnetically responsive member rotates together with the rotating member, and the magnetically responsive member is formed in a line-shaped pattern varying cyclically in a rotational axis direction. A stator is disposed around the rotating member in a contactless manner, and the stator includes a primary coil wound around the rotating member, and a secondary coil forming a loop pattern of a plurality of cycles along the circumference of the rotating member. As the primary coil is AC-energized, an induced AC output signal corresponding to relative positions between the line-shaped pattern of the rotating member and the loop pattern of the secondary coil, which depend on a rotational position of the rotating member, is output from the secondary coil.

An actuator of a camera module includes a detected portion disposed on a lens barrel, and a position detector including a first sensing coil and a second sensing coil, disposed to face the detected portion, and a reference coil disposed outside of a region facing the detected portion, wherein the position detector detects a position of the detected portion in accordance with calculation results of inductances of the first sensing coil and the second sensing coil, and removes noise components by applying inductance of the reference coil to the calculation results of inductances of the first sensing coil and the second sensing coil.

An actuator includes an oscillating unit including two or more oscillation circuits each configured to output an oscillation signal including a frequency, which is changed in response to movement of a detection target, a frequency down-converting unit configured to down-convert frequencies of two or more oscillation signals respectively output from the two or more oscillation circuits, and a determining unit configured to calculate a position of the detection target in response to two or more down-converted oscillation signals output from the frequency down-converting unit.

Maintaining a fixed frequency in a resonant circuit of an inductive sensor circuit is described. In one embodiment, an apparatus includes an inductance-to-digital converter (LDC). The LDC includes a digital filter to measure an inductance change of a sensor and convert the inductance change to a digital value. The LDC further includes a digital control loop to maintain a fixed frequency in the sensor. The sensor forms an oscillator in the digital control loop. An output of the digital control loop is representative of the inductance change of the sensor.

The present invention relates to an inductive position sensor configured to determine a position of a target device, comprising at least one receiving coil arranged to receive a magnetic field and an inner transmitting coil winding and an outer transmitting coil winding arranged to generate said magnetic field, whereby said at least one receiving coil is positioned between said inner transmitting coil winding and said outer transmitting coil winding and whereby said inner transmitting coil winding and said outer transmitting coil winding are so arranged that current flows in the same sense.

A speed detection device includes a comparator module, a sensor lead with a node connected to the comparator module, and a limit set module. The limit set module is connected to the sensor lead node and to the comparator by an upper limit lead and a lower limit lead to provide upper and lower limits to the comparator that vary according to amplitude variation in voltage applied to the sensor lead.

There is provided a driving apparatus including: a rotation unit configured to be rotated about a center shaft by driving of a motor; a rotation angle acquisition unit configured to acquire information of a rotation angle of the rotation unit, as information proportional to the rotation angle; and a control unit configured to control the driving of the motor on the basis of the information of the rotation angle acquired by the rotation angle acquisition unit.

To reduce the construction effort and also to make it smaller, the detector coil (6) is formed in the detector head (7) of a magnetostrictive position sensor (100) in a semiconductor chip (2), in which at the same time also the evaluation circuit (16) is formed andif biased electrically and by means of direct currentalso the then necessary separate bias coil (18).

A position sensor device includes a sensor head with a sensor coil, and an analog-to-digital (A/D) converter for digitizing output from the sensor coil, and sending the digital input to electronics of the device for further processing. The A/D converter is located closer to the coil than it is to the electronics, which may be in an electronics box mounted remotely from the sensor head. The A/D converter may be a part of the sensor head, may be adjacent to the sensor head, and/or may be connected to the sensor coil by an analog output cable. The analog output cable between the sensor coil and the A/D converter may be of negligible length (and of negligible capacitance), and in any event may be shorter than a digital output cable between the A/D converter and the electronics.

A device rotates at least one static magnetic field about an axis, producing a rotating magnetic dipole field, and is movable in relation to the surface of the ground. The field is periodically sensed using a receiver to produce a receiver output responsive to the field. A positional relationship between the receiver and the device is monitored using the output. In one aspect, changing the positional relationship, by moving the device nearer to a boring tool which supports the receiver, causes an increase in accuracy of depth determination. In another aspect, determination of an actual overhead position of the boring tool, and its application, are described. Use of a plurality of measurements over at least one-half revolution of each magnet is disclosed. Establishing a surface radial direction toward a boring tool and resolution of multi-valued parameters is described. Calibration techniques, as well as a three transmitter configuration are also described.