A magnetic field sensor includes at least one magnetic field sensing element configured to generate a measured magnetic field signal responsive to an external magnetic field and to generate a reference magnetic field signal responsive to a reference magnetic field and a calibration circuit configured to divide the measured magnetic field signal by the reference magnetic field signal to generate a calibrated magnetic field signal. The calibrated signal has reduced susceptibility to stress influences.

There is provided a method of compensating a command value for rotation angle capable of precisely compensating a command value for rotation angle even when conditions at detection differ to thereby make error patterns different in the case where a tooth-to-tooth period error pattern in an arbitrary tooth period is used for all the tooth periods to correct a command value for rotation angle. A forward direction tooth-to-tooth period error pattern being an error pattern of detected rotation angles at forward rotation and the actual rotation angles and a backward direction tooth-to-tooth period error pattern being an error pattern at backward rotation are found, and the command value for rotation angle is corrected based on the error pattern at the time of forward rotation, and the command value for rotation angle is corrected based on the error pattern at the time of backward rotation.

The rotation detection device includes: an encoder having to-be-detected patterns cyclically arranged in the circumferential direction; and a sensor configured to detect the to-be-detected patterns to generate pulses. The device further includes a reference pattern storage unit, a phase difference detection unit, and an error correction unit. The reference pattern storage unit measures pitch errors in the to-be-detected patterns prior to operation and stores the pitch errors as a reference pattern Pref. The phase difference detection unit determines a pitch error pattern Pm corresponding to one rotation of the to-be-detected patterns from rotation signals representing a plurality of rotations detected during operation, and performs comparison with a reference pattern Pref to determine a relative phase difference φ. Based on the phase difference φ obtained by the phase difference detection unit, the error correction unit corrects errors included in the rotation signals detected by the sensor.

An angle sensor temperature correcting device includes: a zero correcting factor storing portion that stores, as a reference temperature bridge midpoint potential difference offset and a bridge total resistance indicating value, a difference from an actual correct value, for a relative angle between a bridge circuit and a magnetic field, for the bridge midpoint potential difference, and a value indicating the total resistance of the bridge circuit, at a reference temperature, and stores, as a zero correcting factor, a ratio of the bridge midpoint potential difference offset and the bridge total resistance indicating value at the reference temperature; and a temperature correcting portion that performs temperature correction on angle information obtained from the bridge midpoint potential difference of the bridge circuit at a given time, based on a zero correcting factor stored in the zero correcting factor storing portion.

Methods and apparatus for processing a signal comprise at least one circuit configured to generate a measured signal during a measured time period and a reference signal during a reference time period. Also included is at least one dual- or multi-path analog-to-digital converter comprising at least a first processing circuit configured to process the measured signal, at least a second processing circuit configured to process the reference signal, and a third processing circuit configured to process both the measured signal and the reference signal.

The present disclosure provides an input device and control method thereof. The input device includes a roller module, a relative encoder, an absolute encoder, and a processor. The control method includes: obtaining current angle data outputted by the absolute encoder according to a target phase of at least one signal outputted by the relative encoder; obtaining a current position number corresponding to the current angle data according to the current angle data; calculating a number difference according to the current position number and a previous position number; and outputting the number difference.

An encoder system includes a signal processing circuit including: (1) a first position data detection circuit that detects first position data representing positional displacement in rotation of an input shaft through first predetermined signal processing based on a first detection signal input from a first absolute position encoder; (2) a second position data detection circuit that detects second position data representing positional displacement in rotation of an output shaft through second predetermined signal processing based on a second detection signal input from a second absolute position encoder; (3) a position data combination circuit that combines the first and second position data to generate combined position data representing the number of rotations of the input shaft and the positional displacement within one rotation of the input shaft; and (4) a position data comparing and collating circuit that compares and collates the first and second position data.

An interpolated position of an incremental encoder is provided. A first signal and a second signal having a quadrature relationship are received from the incremental encoder. A coarse position of the incremental encoder at a first time is produced using the quadrature relationship between the first signal and the second signal. An arcsine or arccosine value based on the first signal at the first time is determined using a lookup table and a fine position of the incremental encoder is calculated using the determined value. The interpolated position of the incremental encoder, based on both the coarse position and the fine position, is then provided.

The various embodiment of the present disclosure provides a system to define and identify an absolute mechanical reference position for a rotating element, The system comprises a radial ring magnet comprising plurality of pole pairs mounted to the rotating element, a first magnetic sensor in proximity of the radial ring magnet to detect angular position of said rotating element, at least one second magnetic sensor in proximity of the radial ring magnet to detect the passage of each of the pole pair and a control module adapted to define said absolute mechanical position by computing a unique first set of feature values for each of said plurality of pole pairs based on responses of said first magnetic sensor and said second magnetic sensor. The first set of feature values is stored in a memory unit.

A system may include a plurality of sensors configured to sense a physical quantity and a calibration subsystem configured to perform a calibration comprising: comparing a measured characteristic from each of at least two sensors of the plurality of sensors to determine a sensitivity drift of at least one sensor of the plurality of sensors; based on the measured characteristics of the at least two sensors and stored reference characteristics for the at least two sensors, calculating a normalization factor; and applying the normalization factor to the measured characteristic of the at least one sensor to ensure sensitivity of the plurality of sensors relative to each other remains approximately constant.