Abstract: A bias field generator can provide a magnetic bias field for a magnetic sensor. The bias field generator includes a body with magnetic or magnetizable material. A recess is formed in the body. The recess is adapted to a package of the magnetic sensor.

Abstract: An apparatus for detecting a rotation angle using a magnet rotor comprising a magnet having 2N poles, wherein N is a natural number, and a sensor device for detecting the direction of a magnetic flux from the magnet rotor, at least one of two output voltages obtained in radial and rotational directions by the sensor device being multiplied by a correction coefficient, and the rotation angle being calculated from the two corrected output voltages to increase the detection accuracy of the rotation angle.

Abstract: A stroke amount detection device includes a yoke, a magnetic flux generation section, and a magnetism detection section. The yoke has a protruding section that protrudes to outside the yoke. The magnetic flux generation section is located in the yoke. The magnetism detection section is disposed between the magnetic flux generation section and the protruding section. The magnetism detection section is disposed at a fixed position with respect to the magnetic flux generation section. The magnetism detection section outputs a signal in accordance with a magnetic flux density generated due to a relative movement of the yoke with respect to the magnetism detection section.

Abstract: An indoor navigational system determines a location of a moveable object in an indoor area and displays this location to a user. The system includes an absolute position sensor coupled to a case attached to a moveable object including a motion sensor coupled to a case including a first magnetic field sensor configured to detect a polarity of a magnet as the magnet passes in proximity to the first magnetic field sensor, a code wheel having two or more magnets alternately oriented with north and south polarities facing toward the first magnetic sensor, the code wheel positioned to rotate in unison with a wheel of the moveable object, and encoder circuitry configured to determine an amount of rotation of the wheel of the moveable object based on an output of the first magnetic field sensor.

Abstract: There is provided a coercivity performance determination device for a coercivity distribution magnet that is capable of determining, in a short period of time, with precision, and at as low a testing cost as possible, whether or not each part of one coercivity distribution magnet has a coercivity that is equal to or greater than the required coercivity. A coercivity determining device of the present invention comprises: a substantially C-shaped magnetic body; excitation means that generates a magnetic flow in the magnetic body; and a flux meter that measures the residual magnetic flux of the coercivity distribution magnet. Protrusions are provided at corresponding positions on two opposing end faces of the magnetic body, and the coercivity distribution magnet is held between the two protrusions to form an annular magnetic circuit. An external magnetic field generation means is formed by magnetic regions caused by the protrusions and non-magnetic regions comprising the air in the periphery thereof.

Abstract: A motion sensor has an output protocol processor configured to provide a validated output signal after a determined time period, wherein the determined time period is extended if a vibration is detected.

Abstract: A magnetic field sensor includes a compensation loop coupled in series with normal circuit couplings in order to reduce a transient signal that would otherwise be generated when the magnetic field sensor experiences a high rate of change of magnetic field. In some embodiments, the magnetic field sensor is a current sensor responsive to a magnetic field generated by a current-carrying conductor.

Abstract: A method for tracking a position of an object includes using a field sensor associated with the object to measure field strengths of magnetic fields generated by two or more field generators, wherein a measurement of at least one of the field strengths is subject to a distortion. Rotation-invariant location coordinates of the object are calculated responsively to the measured field strengths. Corrected location coordinates of the object are determined by applying to the rotation-invariant location coordinates a coordinate correcting function so as to adjust a relative contribution of each of the measured field strengths to the corrected location coordinates responsively to the distortion in the measured field strengths.

Abstract: A control system for use in safety critical human/machine control interfaces is described, more particularly a joystick type control system and particularly a joystick type control system utilizing magnetic positional sensing. The control system provides a control input device having a movable magnet, a pole-piece frame arrangement positioned about the magnet, at least three magnetic flux sensors being positioned in said pole-piece frame arrangement and a monitoring arrangement for monitoring the output signal of each of said at least three sensors.

Abstract: The invention relates to a proximity sensor and a method for determining the proximity to an electrically conductive body. By means of a transmitting arrangement, to this end an alternating magnetic field is transmitted at a selected frequency an alternating magnetic field registered by a receiving arrangement. Moreover, frequencies of the registered alternating magnetic field, which are outside a predefined frequency band comprising the selected frequency and have an amplitude value above a predefined threshold value, are detected by means of a detection means. In a control logic, by means of a blocking circuit, frequencies of a predefined frequency band comprising the detected frequency or a plurality of predefined frequency bands comprising in each case one of the detected frequencies, are defined as blocked frequencies.

Abstract: An angular position sensor includes a moving element consisting of at least one essentially cylindrical permanent magnet turning about it axis, at least two magnetosensitive elements and at least one processing circuit furnishing a signal dependent on the absolute position of the moving element The magnetosensitive elements are located essentially at the same point and in that they measure the tangential component of the magnetic field and the radial and/or axial component of the magnetic field for furnishing 2 sinusoidal signals that are essentially 90° out of phase.

Abstract: A packaging material comprising a plurality of magnetizable portions thereon comprising at least one spot per package to be formed from the packaging material is disclosed. At least one of the magnetizable portions provides a magnetic mark carrying a magnetic field pattern. The magnetic field pattern comprises a first magnetic field peak having a first polarity and a second magnetic field peak having a second opposite polarity.

Abstract: A locator for detecting an article includes a push-pull measurement bridge configured to actuate a first and a second electromagnetic device in a variable ratio. Depending on the actuation the first electromagnetic device generates an alternating electromagnetic field in the region of the article. The locator further includes a comparator for detecting the article, should the variable ratio differ by more than a predetermined amount from a predetermined ratio.

Abstract: Apparatus for moving an automotive vehicle seat along a track includes a motor, a first sensor sensing rotation of the motor, and a second sensor detecting presence of the seat at a reference position along the track. A controller determines a seat position based upon signals from the first sensor and calibrates the determined seat position based upon a signal from the second sensor indicating that the seat is at the reference position. This allows any error that as accumulated in the seat position as determined by the first sensor to be eliminated each time the seat reaches the known reference position.

Abstract: A sensor used to sense the position of an attached movable object. The sensor can be mounted to a pneumatic actuator. The sensor includes a housing that has a pair of cavities or pockets separated by a wall. A magnet carrier is positioned within one of the cavities and a magnet is coupled to the magnet carrier. The magnet carrier is coupled to the moveable object. A magnetic sensor is positioned in the other of the cavities. The magnetic sensor generates an electrical signal that is indicative of a position of the movable object.

Abstract: A method for determining the position and/or change of position of a measured object relative to a sensor, where the sensor preferably has a sensor coil to which an alternating current is applied, is characterized in that a magnet associated with the measured object, in a soft magnetic foil, whose permeability changes under the influence of a magnetic field on the basis of the magnetic field's field strength and which is arranged in the area of influence of the sensor, brings about a change in the permeability of the foil and in that the change in the permeability of the foil is determined from the latter's reaction to the sensor, and this is used to determine the position and/or change of position of the measured object relative to the sensor. A sensor arrangement is designed accordingly.

Abstract: A three-wire transformer position sensor is provided that includes an excitation coil and an output coil. The excitation coil is adapted to be electrically excited with an excitation signal, and has a first end and a second end. The output coil includes a first coil and a second coil and is inductively coupled to the excitation coil upon electrical excitation thereof the excitation coil. The first end of the first coil is electrically connected to the second end of the second coil and to the second end of the excitation coil, and the second end of the first coil is electrically connected to the first end of the second coil. The output coil is configured, when it is balanced and the excitation coil is being electrically excited, to supply a null output signal.

Abstract: A magnetic linear position sensor includes an array of N number of magnets. The array of magnets is distributed along a line to form a magnetic field relay along the line. The sizes and positions of the magnets in the array of magnets are symmetric along the line, and the size of the magnets decreases from the sides of the array of magnets towards the center of the array of magnets. The magnetic linear position sensor further includes a magnetic field sensor spaced apart and positioned above the array of magnets. The magnetic field sensor moves back and forth over the array of magnets to sense the magnetic field of the array of magnets.

Abstract: A sensor assembly for determining a spatial position of a first part relative to a second part has at least one magnet disposed on the first part. The magnet generates a magnetic field that extends to the second part. The sensor assembly further has a pair of magnetic field sensors arranged at a spatial distance from each other on the second part. The magnet is positioned in an interval defined by the spatial distance between the magnetic field sensors. The magnetic field sensors each produce an output signal depending on the magnetic field. The output signals of the two magnetic field sensors are combined to form a common sensor signal related to the spatial position of the first part relative to the second part. The output signals of the two magnetic field sensors essentially represent a direction of the magnetic field at the location of the respective magnetic field sensors.

Abstract: A method for detecting magnetic fields, particularly for detecting the position of objects with a preferably oblong, soft-magnetic element, which is connected to electronics, with via the electronics the impedance of the soft-magnetic material is measured, characterized in that a magnetic field is used in which by the position of an object which is located in an arrangement with the soft-magnetic material the magnetic field develops at the location of the soft-magnetic material, with the magnetic permeability ? of the soft-magnetic material adjusting, depending on the magnetic field and thus the position of the object. A respective device serves for applying the method according to the invention.

Abstract: A magnetic field sensor includes a compensation loop coupled in series with normal circuit couplings in order to reduce a transient signal that would otherwise be generated when the magnetic field sensor experiences a high rate of change of magnetic field. In some embodiments, the magnetic field sensor is a current sensor responsive to a magnetic field generated by a current-carrying conductor.

Abstract: Provided is a position detecting device including a first magnetic-field generating unit including at least one magnetic-field generating coil and that generates a first magnetic field in a detection space where a detected object provided with a circuit including at least one built-in coil is disposed; a magnetic-field detecting unit having a plurality of detecting coils arrayed to detect an induced magnetic field generated from the built-in coil by the generated first magnetic field; and a second magnetic-field generating unit including at least one magnetic-field generating coil, that generates a second magnetic field, and including a magnetic-field component having a phase substantially opposite to the first magnetic field and entering the detecting coils, wherein the first magnetic-field generating unit and the detecting coils are disposed so that a generating direction of the first magnetic field and a detecting direction of the induced magnetic field intersect each other.

Abstract: A vibration and condition monitoring system, with true digital signal processing based design, with very limited analog based general signal conditioning and integrated specific sensor conditioning in each module. In addition to the support for common eddy current probe systems, employing an external driver, the module also supports direct connection of an eddy current probe system to the module, due to a built-in driver and linearization functionality. Specific sensor signal conditioning is not dependent on hardware, but only on embedded software, firmware. There is full sensor input support in an I. S. environment. Not only the common sensor input types from accelerometer, velocity sensor, but also direct input for eddy current probe systems for both vibration and/or speed measurements. The module also comprises means to assess the type and correct functionality of an attached eddy current probe system (302, 303) by means of a frequency measurement and possibly an amplitude measurement.

Abstract: Anti-lock and intelligent braking systems have become ubiquitous in modern vehicles, which employ wheel speed sensors or WSSs. These WSSs generally uses current-domain signals (transmitted through power wires) to reduce the size of the vehicle's wiring harness, but because a vehicle is an inherently noisy environment, mixed signal circuit or MSC (used to decode these signals for a microcontroller) should be able to filter out or compensate for noise. However, traditional MSCs have been plagued with problems, partly due to errors in time base measurement due to noise (as well as other factors). Here, an MSC is provided that accurately calculates a wheel speed pulse width (which is used for time base measurements) by observing the wheel speed pulse as it passes through several thresholds.

Abstract: A non-contact position sensor includes a magnet, magnetoresistive elements arranged on a line extending in a predetermined direction on a pole surface of the magnet with predetermined intervals, and an object made of magnetic material displaceable in the predetermined direction. The magnetoresistive elements are connected serially between a power supply and a ground. A first magnetoresistive element is connected to the second magnetoresistive element at a first node. A second magnetoresistive element is connected to a third magnetoresistive element at a second node. The object includes a projection and a shaft connected to the projection. The projection can face the first to third magnetoresistive elements. The shaft is located away from the pole surface by a distance longer than a distance between the projection and the pole surface of the magnet.

Abstract: In a sensor of a sensor unit in which working voltage or calibration voltage is supplied through a single input end, working voltage can be stably supplied to the sensor after initial calibration. The sensor unit includes a voltage stabilizing circuit for stabilizing a voltage value of a supply power source to said working voltage, and a wiring for supplying said calibration voltage to the sensor, which are provided parallel to each other between the input end of the sensor and a power source connecting end for the sensor on the circuit board, and a switching portion which can disconnect the wiring, wherein an access hole is formed in the housing through which the switching portion is accessible to disconnect the wiring.

Abstract: A differential amplifier generates an offset correction signal based on a rotation detection signal from a rotation detector apparatus and an offset signal. A comparator compares the offset correction signal with a threshold voltage, and outputs a binarized signal representing the comparison result. An average value signal generator circuit generates an average value signal representing the average value of the offset correction signal. The offset signal generator circuit generates the offset signal so that the signal voltage of the average value signal has a voltage value between a threshold voltage and a threshold voltage.

Abstract: A magnetic signal noise reduction and detection system has inputs configured to receive data from a first total field scalar magnetometer, data from a vector magnetometer, and data from a position, velocity and heading sensor, a signal processor configured with a pre-processor system, an adaptive noise cancellation system and a detection system, the pre-processor system configured to carry out initial processing of data received. The pre-processor is configured to convert data to the frequency domain and pass the converted data to the adaptive noise cancellation system. The adaptive noise cancellation system is configured to carry out multivariate regression on the converted data to reduce detected noise. The detection system is configured to detect magnetic anomalies and output information in real time about the magnetic anomalies to a user interface.

Abstract: This invention relates to an apparatus and method for deriving speed and position information for an electric motor. Apparatus for and a method of controlling a motor 100 are also disclosed. The apparatus for providing information relating to the operation of an electrical motor 100 comprises a sampler 50, 51 for sampling the instantaneous motor current is and a processor 160 for determining the instantaneous rate of change of the motor current and providing information about the motion or position of said motor based on said instantaneous rate of change of the motor current. In this way speed and position information can be provided, at low speeds, and without using a speed sensor.

Abstract: An electric motor (10) has: a stator (12) and a rotor (14) having a shaft (87). The rotor (14) has a sensor magnet (82) having a number SP of sensor poles (71, 72, 73, 74) for generating a predetermined distribution of the magnetic flux density, such that SP=2, 4, 6, 8, etc. The motor also has at least two rotor position sensors (450, 455, 460, 465) for generating rotor position signals (B_S1, B_S2) characterizing the magnetic flux density, the rotor position sensors (450, 455, 460, 465) being arranged in the region (30) of the circumference of the sensor magnet (82). The motor also has an evaluation apparatus (32) that ascertains, from the rotor position signals (B_S1, B_S2), an absolute value (phi_el, phi_mech) for the rotational position of the rotor (14). A method of generating an absolute value for the rotational position of an electric motor is likewise described.

Abstract: An embodiment of a method for a determination, section after section, of a parameter-dependent correction value approximation course includes determining a first measurement signal value with a first parameter value associated with a sensor arrangement when the first parameter value fullfils a predetermined condition or a trigger condition is fulfilled, changing the first parameter value to obtain a second parameter value, determining a second signal value with the second parameter value and determining a second partial section of the correction value approximation course for a second parameter range based on a functional connection describing the second partial section, the first parameter value, the second parameter value, the first measurement signal value, the second measurement signal value and an initial correction value.

Abstract: A circuit to detect a movement of an object has a calibration time period that ends when peak detectors in the circuit stop updating for a predetermined amount of time. A method associated with the circuit is also described.

Abstract: Disclosed is a relative angle detection device for detecting a relative angle between a first rotary shaft and a second rotary shaft, the relative angle detection device being provided with a first magnetic field sensing unit which outputs a value according to a magnetic field of a magnet, a second magnetic field sensing unit which outputs a value according to the magnetic field of the magnet and outputs a value different from the output value of the first magnetic field sensing unit even if being placed in the same magnetic field as that of the first magnetic field sensing unit, a correction unit which corrects one output value out of the output value of the first magnetic field sensing unit and the output value of the second magnetic field sensing unit in accordance with an amplitude ratio between magnetic field components orthogonal to each other in the magnetic field of the magnet, and a computing unit which computes the relative angle between the first rotary shaft and the second rotary shaft on the basi

Abstract: A magnetic array sensor circuit to process an output from a magnetic sensor array including a plurality of magnetic sensor elements arranged in an array. The circuit includes a regulating circuit to reduce an offset variation of the output from the magnetic sensor elements arranged in the array. The regulating circuit includes a control circuit to operate the magnetic sensor element in a linear region. The control circuit includes a reference sensor element in the form of the magnetic sensor element short-circuited between two output terminals, a storage element to store a reference offset value read out from the reference sensor element, and a subtraction circuit to subtract the stored reference offset value from an output of the other magnetic sensor elements.

Abstract: A method for tracking a position of an object includes using a field sensor associated with the object to measure field strengths of magnetic fields generated by two or more field generators, wherein a measurement of at least one of the field strengths is subject to a distortion. Rotation-invariant location coordinates of the object are calculated responsively to the measured field strengths. Corrected location coordinates of the object are determined by applying to the rotation-invariant location coordinates a coordinate correcting function so as to adjust a relative contribution of each of the measured field strengths to the corrected location coordinates responsively to the distortion in the measured field strengths.

Abstract: An electronic pedal assembly including a treadle, a pedal arm connected to the treadle, and a rotor assembly about which the pedal arm rotates. The assembly also includes one or more Hall sensors positioned within a cavity in the rotor assembly and one or more magnets that fixedly attached to the rotor assembly. The Hall sensors detect the position of the treadle by monitoring the positions of the magnets. Also, a method of monitoring an electronic pedal assembly using one or more magnets and one or more Hall sensors.

Abstract: A magnetic sensor includes a first detection unit and a second detection unit. The first detection unit calculates a first detection angle which is a detected value of a first angle that a direction of an external magnetic field in a first position forms with respect to a first direction. The second detection unit calculates a second detection angle which is a detected value of a second angle that the direction of the external magnetic field in a second position forms with respect to a second direction. The first detection angle includes a first angular error. The second detection angle includes a second angular error. The first angular error and the second angular error differ in phase by an odd number of times ½ of the error period.

Abstract: The invention relates to a proximity detection system. The invention provides a proximity detection system comprising a generator that generates a magnetic field that establishes a boundary, where the generator is capable of receiving radio frequency signals. Also provided is a radio frequency device that sends radio frequency signals, the radio frequency device being capable of sensing the magnetic field and generating a radio frequency response. In the proximity detection system, the generator generates the magnetic field for a first predefined time period, and thereafter senses for a radio frequency response signal from the radio frequency device within a second predefined time period. The invention also provides for shaping proximity detection zones by overlaying magnetic field boundaries to produce a different boundary. The invention also provides for varying the strength of magnetic fields by adjusting a width of a timed pulse.

Abstract: A compact sensing device capable of sensing a rotational angle and a rotational velocity, or a rectilinear moving distance and a moving velocity. A displacement sensing device that senses a rotational angle of a moving member rotation and a distance of a linear movement of the moving member, or senses an angular velocity of the moving member rotation and a velocity of a linear movement of the moving member, includes: a first movable member, moved together with the moving member by a linear movement of the moving member; a second movable member holding the first movable member in a rotatable manner, and rotated together with the moving member by rotation of the moving member; a first sensor outputting a signal in accordance with a linear movement of the first movable member; and a second sensor outputting a signal in accordance with a rotation of the second movable member.

Abstract: A position detecting system including: a detected object disposed in a space; and an external device disposed outside the space, wherein the detected object includes a resonant circuit, and the external device includes at least two drive coils; at least two drive-signal input units; at least one sense coil; a signal adjustment unit that adjusts a phase or amplitude of a drive signal using an evaluation function for evaluating the phase or the amplitude, based on an intensity of the magnetic field; and a position deriving unit that derives a position of the detected object based on a magnetic field detected by the sense coil, wherein the evaluation function derives a solution by adding or multiplying a weight set according to a positional relation between each drive coil and each sense coil to or by an intensity of a magnetic field detected by the sense coils.

Abstract: The invention relates to a motion monitoring system (1) for monitoring motion within a region of interest (2). The motion monitoring system (1) comprises a magnetic induction tomography detection data acquisition unit (3) for acquiring MIT detection data of the region of interest (2), and a motion determining unit (4) for determining motion within the region of interest (2) based on the acquired MIT detection data. The invention relates further to an imaging system for imaging a region of interest comprising the motion monitoring system (1). The determined motion can be used for reducing motion artifacts in reconstructed images.

Abstract: The invention relates to a sensor arrangement for detecting at least one of the movement and the position of two components of an assembly, which are located close to each other or are disposed one inside the other and can be moved relative to each other, said sensor arrangement comprising at least one first sensor for detecting at least one of the movement and the position of the one component and a second sensor for detecting at least one of the movement and the position of the other component, the sensors functioning according to different measuring principles without affecting each other mutually.

Abstract: 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.

Abstract: Metal face inductive proximity sensors and methods are presented for sensing the presence or absence of a target object in a target sensing area in which a coil system is operated to generate a magnetic field extending outward from the sensing face at a frequency in a range that maximizes a relative target effect for the sensing face area, material, and thickness, and a target material from which the target object is made to allow the protective advantages of metal sensing face materials while enhancing sensing distance by optimizing the ratio of the target energy loss to the energy loss in the metal face.

Abstract: A position detection apparatus and a medical-device-position detection system that have improved position detection accuracy are provided by setting high amplification for the position detection apparatus. The position detection apparatus includes a circuit that has at least one embedded coil (10a) and that is provided inside an object (10) to be detected; a first magnetic-field generating unit (11) for generating a first magnetic field in the region where the embedded coil (10a) is disposed; a magnetic-field detecting unit (5, 12) for detecting an induced magnetic field generated at the embedded coil (10a) by the first magnetic field; and a second magnetic-field generating unit (23) for generating a second magnetic field having a phase substantially opposite to the phase of the first magnetic field.

Abstract: An inductive position encoder is described having first and second members which are relatively moveable over a measurement path, a magnetic device mounted on the first member; a plurality of first windings mounted on the second member; and a second winding. The magnetic device is operable to interact with the windings such that upon the energization of either the second winding or the first windings, there is generated a plurality of sensor signals each being associated with a respective one of said first windings and varying with the relative position between said magnetic device and the associated first winding and hence with the relative position between said first and second members. Additionally, the plurality of first windings are arranged along said measurement path so that the sensor signals vary substantially in accordance with a predetermined Gray code.

Abstract: Certain embodiments of the present invention provide a system and method for improved distortion measurement and compensation. Certain embodiments include selecting a set of sources on a surface of a volume, determining mutual inductances from the set of sources on the surface, and calculating distortion from the volume using the mutual inductances from the set of sources on the surface. In an embodiment, distortion is calculated using an integral method and/or a finite element analysis. The volume may be modeled as a simplified construct, such as a ring model, a coil array with straight line segments model, a polygon model, and/or dipole array model. The model may be adjusted based on the distortion calculated from the volume. Magnetic fields may also be used to calculate distortion. In an embodiment, an object may be tracked using a distortion mapping.

Abstract: A rolling bearing unit having a sensor comprising: a first raceway member, on the outer circumferential surface of which a raceway surface is provided; a second raceway member, on the inner circumferential surface of which a raceway surface is provided; a plurality of rolling elements arranged between the raceway surface of the first raceway member and the raceway surface of the second raceway member; a base plate, the shape of which is formed into an annular and flat shape, having a through-hole that the first raceway member penetrates; a first coil, the shape of which is formed into a plane shape, arranged so that the first coil surrounds an overall circumference of the first raceway member; and a plurality of second coils, the shape of which is formed into a plane shape, arranged around the first coil.

Abstract: An apparatus is provided for compensating for the effect of a stray ferromagnetic object moving past but not through a sensing region of a ferromagnetic object detector. The ferromagnetic object detector is of a type to produce a plurality of sensor signals, each sensor signal being influenced by the presence of a genuine ferromagnetic object moving through the sensing region but also liable to be influenced by the presence of the stray object. The apparatus comprises: an input for receiving the plurality of sensor signals and first means for analysing the received signals to determine whether there is a substantially same time-varying component present in each of the signals. The apparatus also comprises second means for determining whether the plurality of signals without the contribution of that time-varying component are each or collectively below a predetermined level of significance.

Abstract: A rotation-angle-detecting apparatus comprising a magnet rotor, a magnetic sensor detecting the direction of magnetic flux from the magnet rotor, a correction circuit, and an angle-calculating circuit, the magnetic sensor having bridge circuits X and Y each comprising four connected magnetoresistive devices, each magnetoresistive device comprising a spin-valve, giant-magnetoresistive film, the correction circuit calculating difference (Vx?Vy) and sum (Vx+Vy) from the output voltage Vx of the bridge circuit X and the output voltage Vy of the bridge circuit Y, and making their amplitudes equal to each other, and the angle-calculating circuit determining the rotation angle of the rotor by arctangent calculation from a signal (Vx?Vy)? and a signal (Vx+Vy)? supplied with the same amplitude from the correction circuit.