Devices, systems, and method for detecting, determining and compensating for offset error arising in inductive position and torque sensors are described. In accordance with at least one embodiment, an offset coil can be configured for use within an inductive sensor and include a first trace and at least one second trace. The first trace and the at least one second trace may be drawn within a stator of an inductive sensor. The first trace and the at least one second trace may be drawn within the stator proximate to a pair of excitation coil connecting leads, drawn on a first plane within the stator, and on at least one plane substantially parallel to the first plane such that wherein an excitation coil flowing through the pair of excitation coil connecting leads induces an offset coil signal in the first trace and at least second trace.

An electromagnetic induction type encoder includes a detection head and a scale. The detection head has a first transceiver coil to generate magnetic flux with respect to a first track and a second transceiver coil to generate magnetic flux with respect to a second track. The scale has a first plurality of periodical elements with respect to the first track and a second plurality of periodical elements with respect to the second track. The detection head has a receiver coil that continuously extends from the first track to the second track, is electromagnetically coupled with the magnetic flux generated by the first plurality of periodical elements and the magnetic flux generated by the second plurality of periodical elements, and detects a phase of the magnetic flux generated by the first plurality of periodical elements and a phase of the magnetic flux generated by the second plurality of periodical elements.

A measurement method for measuring the position of a movable body that is movable relative to a fixed body, the measurement method making use of a measurement device comprising a fixed portion for securing to the fixed body and a movable portion for securing to the movable body, the fixed portion including a first printed circuit (7; 20) having formed thereon first tracks (9) defining at least one emission pattern (10; 24) and also a plurality of measurement patterns (11; 25), the movable portion including a second printed circuit (8; 21) having formed thereon second tracks (14) defining at least one reception pattern (15; 27) and also at least one target pattern (16; 28), the first and second printed circuits being coupled together electromagnetically in such a manner that, when the emission pattern is excited by an excitation signal, an induced signal is received by the reception pattern and is then re-emitted by the target pattern, the measurement patterns then picking up measurement signals that are representative of the position of the target pattern, and thus also of the second printed circuit, of the movable portion, and of the movable body.

A sensing circuit in a device having a moving body in which a unit to be detected including first and second pattern units spaced apart from each other is formed includes an oscillation circuit unit including first and second oscillation circuits fixedly mounted on a substrate spaced apart from the unit to be detected, including, respectively, first and second sensing coils having first and second inductance values depending on areas of overlap between the first and second sensing coils and the first and second pattern units and outputting, respectively, first and second sensed oscillation signals based on the first and second inductance values; and a sensing circuit outputting an output signal having movement information of the moving body based on each period count value for each of the first and second sensed oscillation signals using a reference oscillation signal.

An electromagnetic induction type encoder includes a detection head and a scale. The detection head has a transmitter coil configured to generate magnetic flux. The scale has connection coils that are arrayed in a measurement axis direction, are configured to be electromagnetically coupled with magnetic flux generated by the transmitter coil and generate magnetic flux that fluctuates in a predetermined spatial period in the measurement axis direction. The detection head has a receiver coil having a plurality of coils that are arrayed in the measurement axis direction on a predetermined face of the detection head, are configured to be electromagnetically coupled with the magnetic flux generated by the connection coils and detect a phase of the magnetic flux. A current direction of one of the plurality of coils is opposite to a current direction of another coil of the plurality of coils next to each other.

A scale capable of maintaining measurement accuracy even if the pattern of the scale pattern is scratched is provided. The scale 2 comprises a scale pattern 4 having a plurality of unit patterns provided at a predetermined pitch along the measurement direction on a surface thereof. At least one of the plurality of unit patterns comprises a plurality of loop portions 8 formed with conductors in a loop shape. The plurality of loop portions 8 included in the unit pattern are arranged so as to be spaced from each other such that the centers of gravity of the loop portions 8 are at the same position in the measurement direction on the surface of the scale 2. Thereby, the plurality of loop portions 8 included in the unit pattern can prevent deviation of the center of gravity of the magnetic flux distribution in the measurement direction, even if any of the plurality of the loop portions 8 is scratched. Therefore, the scale 2 can maintain the measurement accuracy.

A circuit includes a bandpass filter and a self-tracking circuit. The bandpass filter has a first input node configured to receive an input square wave signal and an output node configured to provide an output sine wave signal. The bandpass filter includes a first binary-weighted programmable resistor array. The self-tracking circuit includes a second input node coupled to the output node. The self-tracking circuit includes a counter, and the counter includes an output node coupled to the first binary weighted programmable resistor array.

A measurement method for measuring the position of a movable body that is movable relative to a fixed body, the measurement method making use of a measurement device comprising a fixed portion for securing to the fixed body and a movable portion for securing to the movable body, the fixed portion including a first printed circuit (7; 20) having formed thereon first tracks (9) defining at least one emission pattern (10; 24) and also a plurality of measurement patterns (11; 25), the movable portion including a second printed circuit (8; 21) having formed thereon second tracks (14) defining at least one reception pattern (15; 27) and also at least one target pattern (16; 28), the first and second printed circuits being coupled together electromagnetically in such a manner that, when the emission pattern is excited by an excitation signal, an induced signal is received by the reception pattern and is then re-emitted by the target pattern, the measurement patterns then picking up measurement signals that are representative of the position of the target pattern, and thus also of the second printed circuit, of the movable portion, and of the movable body.

An offset correction device includes: an amplitude adjuster that adjusts an amplitude of a detection signal output from an encoder by adjusting a gain of the detection signal so that the amplitude is within a predetermined range; an offset corrector that corrects an offset of an amplitude center of the detection signal; and a storage that stores a relationship between the gain and an offset amount in advance, wherein the offset corrector refers to the relationship stored in the storage when the amplitude adjuster changes the gain, obtains the offset amount corresponding to the changed gain, and corrects the offset based on the obtained offset amount.

An electromagnetic induction type encoder, wherein at least one of widths of a first transceiver coil, a first plurality of conductors and a first receiver coil of a first track in a direction vertical to facing direction between a detection head and a scale and a measurement direction is different from corresponding width of a second transceiver coil, a second plurality of conductors and a second receiver coil in the direction vertical to the facing direction and the measurement direction.