JP6656958B2 - Rotary encoder and method for correcting angle of rotary encoder - Google Patents

Description

  The present invention relates to a rotary encoder suitable for correcting an angular error due to a harmonic component superimposed on a fundamental wave of a detection signal from a sensor constituting a part of the rotary encoder, and a method of correcting the angle of the rotary encoder.

  The rotary encoder detects, for example, the rotational position of a motor shaft of a servomotor and feeds it back to the control system as detection data. Then, the control system compares the detection data from the rotary encoder with the control command value, and outputs a voltage command for controlling the detection data to approach the control value.

  As such a rotary encoder, for example, in Patent Document 1, a first magnet having a magnetized surface in which an N pole and an S pole are magnetized one by one in the circumferential direction, and a first magnet arranged outside the first magnet and arranged in the circumferential direction. And a second magnet having an annular magnetized surface in which a plurality of N poles and S poles are alternately magnetized, and the rotational position on the first magnet side is detected by the first magnetoresistive element and the Hall element. There has been proposed a rotary encoder that detects the rotation position on the magnet side by a second magnetoresistive element.

Japanese Patent No. 5666886

  In the above-described rotary encoder, detection data of the rotation position on the first magnet side detected by the first magnetoresistive element and the Hall element, and detection data of the rotation position on the second magnet side detected by the second magnetoresistive element, It is possible to detect a rotational position with high resolution.

  By the way, in such a rotary encoder, a sine wave signal having a fixed repetition period is output from the second magnetoresistive element on the second magnet side having a large number of magnetic poles. As is well known, the sine wave signal is a signal in which a harmonic component is superimposed on a fundamental wave component (one cycle output from one pole of the magnet) and the fundamental wave component. Also, harmonics occur in prime orders such as third, fifth, seventh, eleventh, thirteenth,..., And the smaller the order, the greater the amplitude. That is, if the amplitude of the harmonic is large, the fundamental wave is distorted. In addition, the harmonic appears as an angular error of (order + 1) cycle.

  As described above, for example, when the rotational position of the motor shaft of the servo motor is detected based on the sine wave signal on which the harmonics are superimposed, the detected rotational position has an angular error, so that the accuracy is high. There is a problem that detection data of the rotational position cannot be obtained.

  The present invention has been made in view of such a situation, and cancels a harmonic superimposed on a fundamental wave of a detection signal from a sensor constituting a part of a rotary encoder, thereby achieving a highly accurate rotation position. It is an object of the present invention to provide a rotary encoder capable of obtaining detection data and a method for correcting an angle of the rotary encoder.

The rotary encoder according to the present invention includes a first rotating magnet in which the N and S poles are magnetized one by one in the circumferential direction, and a second rotating magnet in which a plurality of N and S poles are alternately magnetized in the circumferential direction. A rotary encoder having a rotating magnet portion including a rotating magnet, a first magnetoresistive element for detecting an angular position of the first rotating magnet, and a second magnetoresistive element disposed in proximity to the first magnetoresistive element. A first Hall element, a second Hall element disposed at a position shifted by 90 ° in mechanical direction from the first Hall element in the circumferential direction, and a second Hall element for detecting an angular position of the second rotating magnet. Based on detection data of the first magnetoresistive element, the first Hall element, the second Hall element, and the second magnetoresistive element, and an angle of the rotary magnet unit by data processing. A data processing unit for finding the position The second magnetoresistive element is provided with a harmonic cancellation pattern for canceling a harmonic of a predetermined order or less, and the data processing unit uses the correction data for canceling the harmonic of a predetermined order or less to correct the second harmonic. The detection data of the magnetoresistive element is corrected.
In this configuration, the first magnetoresistive element detects the angular position of the first rotating magnet, and the second magnetoresistive element cancels harmonics of a predetermined order or less by the harmonic canceling pattern, and performs the second rotation. When the angular position of the magnet is detected, the data processing unit corrects the detection data of the second magneto-resistive element with the correction data for canceling out harmonics exceeding a predetermined order. As a result, harmonics of a predetermined order or less are canceled by the second magnetoresistive element, and harmonics exceeding the predetermined order are canceled by the data processing unit, so that a detection signal from a sensor constituting a part of the rotary encoder is eliminated. Harmonics superimposed on the fundamental wave can be canceled.

Further, the correction data is electrical angle correction data for canceling a periodic angular error that is commonly possessed by each pole of the second rotating magnet, and the data processing unit is configured to execute the electrical angle correction data , An electrical angle correction unit that corrects an angle error of detection data of the second magnetoresistive element using the electrical angle correction data, the first magnetoresistance element, and the first hole. And an angular position determining unit that determines the angular position of the rotating magnet unit based on the detection data of the element and the second Hall element and the detection data corrected by the electrical angle correction unit. And
In this configuration, the electrical angle correction unit uses the electrical angle correction data stored in the memory to cancel the periodic angle error that each pole of the second rotating magnet has in common, and the angular position determination unit Since the angular position of the rotating magnet unit is determined based on the detection data of the first magnetoresistive element, the first Hall element, the second Hall element, and the detection data corrected by the electrical angle correction unit, the second It is possible to cancel the periodic angular error which each pole of the rotating magnet has in common.

Further, the electrical angle correction data includes data for canceling a harmonic of a predetermined order or less that remains without being canceled by the harmonic canceling pattern.
With this configuration, the electrical angle correction unit can cancel the harmonics of a predetermined order or less remaining without being canceled by the harmonic cancellation pattern by the electrical angle correction data.

Further, the memory stores mechanical angle correction data for canceling an angular error periodically generated with the rotation of the first rotating magnet and the second rotating magnet, and the data processing unit includes: It is characterized by having a mechanical angle correction unit that corrects the angular position data determined by the angle position determination unit using the mechanical angle correction data.
In this configuration, the mechanical angle correction unit uses the mechanical angle correction data stored in the memory to correct the angular position data determined by the angular position determination unit, so that the first magnetoresistive element, the first rotating magnet, , And an angle error generated by a mechanical factor such as a center deviation between the second magnetoresistive element and the second rotating magnet can be canceled.

Further, the electrical angle correction data has a value obtained by averaging errors caused by all harmonics exceeding the predetermined order.
In this configuration, since the electrical angle correction data has a value obtained by averaging the errors caused by all harmonics exceeding the predetermined order, the storage capacity of the memory can be reduced, and the electrical angle correction unit uses a predetermined value. The procedure of the correction processing for canceling the harmonics exceeding the order can be shortened.

Further, the electrical angle correction data includes a value obtained by averaging errors remaining due to all the harmonics of the predetermined order or less remaining without being canceled by the harmonic canceling pattern.
In this configuration, since the electrical angle correction data includes a value obtained by averaging errors due to all harmonics of a predetermined order or less, which remain without being canceled by the harmonic cancellation pattern, As a result, harmonics of a predetermined order or less remaining without being canceled can be canceled.

Further, the electric angle correction data has a value averaged for each specific order of harmonics exceeding the predetermined order.
In this configuration, since the electrical angle correction data has a value averaged for each specific order of harmonics exceeding the predetermined order, the electrical angle correction unit outputs the harmonics exceeding the predetermined order for each specific order. It is possible to cancel, and the periodic angle error which each pole of the second rotating magnet has in common can be further reduced.

Further, the electrical angle correction data includes a value averaged for each specific order of harmonics having a predetermined order or less and remaining without being canceled by the harmonic canceling pattern.
In this configuration, since the electrical angle correction data includes a value that is averaged for each specific order of harmonics of a predetermined order or less and remains without being canceled by the harmonic cancellation pattern, the electrical angle correction unit performs the harmonic correction. The harmonics of a predetermined order or less remaining without being canceled by the wave canceling pattern can be canceled for each specific order, and the periodic angle that each pole of the second rotating magnet has in common The error can be further reduced.

Further, the predetermined order is a seventh order.
In this configuration, the second magnetoresistive element can cancel the seventh or lower harmonics by the harmonic cancel pattern.

The angle correction method for a rotary encoder according to the present invention includes a first rotating magnet in which the N pole and the S pole are magnetized one by one in the circumferential direction, and a plurality of N poles and the S pole alternately magnetized in the circumferential direction. A method for correcting an angle of a rotary encoder having a rotating magnet unit including a second rotating magnet, wherein the step of detecting an angular position of the first rotating magnet by a first magnetoresistive element; A first Hall element disposed adjacent to the first magnetoresistive element, a second Hall element disposed at a position shifted by 90 ° in mechanical angle with respect to the first Hall element in a circumferential direction, A step of detecting the angular position of the second rotating magnet by a magnetoresistive element; and a step of detecting the first magnetoresistive element, the first hall element, the second hall element, and the second hall by a data processing unit. Data based on the detection data Determining the angular position of the rotating magnet unit by a data processing, wherein the second magnetic resistance element is provided with a harmonic cancellation pattern for canceling a harmonic of a predetermined order or less, The unit corrects the detection data of the second magnetoresistive element with correction data for canceling a harmonic exceeding a predetermined order.
In this configuration, the first magnetoresistive element detects the angular position of the first rotating magnet, and the second magnetoresistive element cancels harmonics of a predetermined order or less by the harmonic canceling pattern, and performs the second rotation. When the angular position of the magnet is detected, the data processing unit corrects the detection data of the second magneto-resistive element with the correction data for canceling out harmonics exceeding a predetermined order. As a result, harmonics of a predetermined order or less are canceled by the second magnetoresistive element, and harmonics exceeding the predetermined order are canceled by the data processing unit, so that a detection signal from a sensor constituting a part of the rotary encoder is eliminated. Harmonics superimposed on the fundamental wave can be canceled.

Further, the correction data is electrical angle correction data for canceling a periodic angle error that is common to the respective poles of the second rotating magnet, and is stored in a memory by an electrical angle correction unit. Correcting the angle error of the detection data of the second magnetoresistive element using the electrical angle correction data; and determining the first magnetoresistive element, the first Hall element, and the second 2) determining an angular position of the rotating magnet unit based on the detection data of the Hall element and the detection data corrected by the electrical angle correction unit.
In this configuration, the electrical angle correction unit uses the electrical angle correction data stored in the memory to cancel the periodic angle error that each pole of the second rotating magnet has in common, and the angular position determination unit Since the angular position of the rotating magnet unit is determined based on the detection data of the first magnetoresistive element, the first Hall element, the second Hall element, and the detection data corrected by the electrical angle correction unit, the second It is possible to cancel the periodic angular error which each pole of the rotating magnet has in common.

Further, the electrical angle correction data includes data for canceling a harmonic of a predetermined order or less that remains without being canceled by the harmonic canceling pattern.
With this configuration, the electrical angle correction unit can cancel the harmonics of a predetermined order or less remaining without being canceled by the harmonic cancellation pattern by the electrical angle correction data.

Further, the memory stores mechanical angle correction data for canceling an angular error periodically generated with the rotation of the first rotating magnet and the second rotating magnet, and the mechanical angle correcting unit A step of correcting the angular position data determined by the angle position determining unit using mechanical angle correction data.
In this configuration, the mechanical angle correction unit uses the mechanical angle correction data stored in the memory to correct the angular position data determined by the angular position determination unit, so that the first magnetoresistive element, the first rotating magnet, , And an angle error generated by a mechanical factor such as a center deviation between the second magnetoresistive element and the second rotating magnet can be canceled.

Further, the electrical angle correction data has a value obtained by averaging errors caused by all harmonics exceeding the predetermined order.
In this configuration, since the electrical angle correction data has a value obtained by averaging the errors caused by all harmonics exceeding the predetermined order, the storage capacity of the memory can be reduced, and the electrical angle correction unit uses a predetermined value. The procedure of the correction processing for canceling the harmonics exceeding the order can be shortened.

Further, the electrical angle correction data includes a value obtained by averaging errors remaining due to all the harmonics of the predetermined order or less remaining without being canceled by the harmonic canceling pattern.
In this configuration, since the electrical angle correction data includes a value obtained by averaging errors due to all harmonics of a predetermined order or less, which remain without being canceled by the harmonic cancellation pattern, As a result, harmonics of a predetermined order or less remaining without being canceled can be canceled.

Further, the electric angle correction data has a value averaged for each specific order of harmonics exceeding the predetermined order.
In this configuration, since the electrical angle correction data has a value averaged for each specific order of harmonics exceeding the predetermined order, the electrical angle correction unit outputs the harmonics exceeding the predetermined order for each specific order. It is possible to cancel, and the periodic angle error which each pole of the second rotating magnet has in common can be further reduced.

Further, the electrical angle correction data includes a value averaged for each specific order of harmonics having a predetermined order or less and remaining without being canceled by the harmonic canceling pattern.
In this configuration, since the electrical angle correction data includes a value that is averaged for each specific order of harmonics of a predetermined order or less and remains without being canceled by the harmonic cancellation pattern, the electrical angle correction unit performs the harmonic correction. The harmonics of a predetermined order or less remaining without being canceled by the wave canceling pattern can be canceled for each specific order, and the periodic angle that each pole of the second rotating magnet has in common The error can be further reduced.

Further, the predetermined order is a seventh order.
In this configuration, the second magnetoresistive element can cancel the seventh or lower harmonics by the harmonic cancel pattern.

  According to the rotary encoder and the angle correction method of the rotary encoder of the present invention, the second magnetoresistive element cancels harmonics of a predetermined order or less, and the data processing unit cancels harmonics exceeding the predetermined order by the correction data. Therefore, it is possible to cancel a harmonic superimposed on a fundamental wave of a detection signal from a sensor constituting a part of the rotary encoder, and to obtain highly accurate rotation position detection data.

FIG. 2 is a diagram illustrating an embodiment of a rotary encoder according to the present invention. FIG. 2A illustrates the basic principle of detecting the angular position of the rotating magnet unit in FIG. 1 when harmonics are not included, and FIG. 2A illustrates waveforms of detection signals of a magnetoresistive element and a Hall element. FIG. 2B is a diagram illustrating the angular position (electrical angle) of the rotating magnet unit. FIG. 3A shows a method of determining the angular position of the rotating magnet unit shown in FIG. 1. FIG. 3A shows that the angular position θ obtained from the detection signal (sin, cos) of the magnetoresistive element on the rotating magnet is 1 FIG. 3B shows the angular position θ obtained from the detection signal (sin, cos) of the magnetoresistive element on the rotating magnet for one cycle, and FIG. 3C shows the angular position θ for one cycle. FIG. 4 is a diagram showing a case where the absolute angle data shown in FIG. 3) and the incremental angle data shown in FIG. FIG. 4A shows a periodic angle error and the like which each pole of the rotating magnet having a plurality of magnetized surfaces of FIG. 1 has in common. FIG. 4A shows the N pole of the rotating magnet of FIG. The angle error before correction for 128 poles, which is the number of pairs with the S pole, is superimposed and shown in FIG. 4B. FIG. It is a figure which shows the angle error after correction | amendment superimposedly. FIG. 5 is a diagram illustrating angle errors after correction for four poles out of 128 poles in FIG. 2 is a flowchart for describing a method of correcting an angle of a rotating magnet unit in FIG. 1.

  Hereinafter, an embodiment of a rotary encoder according to the present invention will be described with reference to FIGS.

  First, a configuration example of a rotary encoder will be described with reference to FIG. The rotary encoder 100 includes a data processing unit 10, a rotating magnet unit 20, a magnetic resistance element 50, Hall elements 51 and 52, a magnetic resistance element 60, amplifiers 70 to 72, and A / D conversion units 73 to 75. The rotary encoder 100 according to the present embodiment is characterized in that it corrects an angular error due to a harmonic component superimposed on a fundamental wave of a detection signal from the magnetoresistive element 60, for example, but details will be described later. . The details of the configuration of each unit will also be described step by step. Further, a magnetoresistive element 50 and Hall elements 51 and 52 on the rotating magnet 30, which will be described later, and a magnetoresistive element 60 on the rotating magnet 40 are mounted on a substrate on a fixed plate (not shown). A magnetoresistive element 50, Hall elements 51 and 52, and a magnetoresistive element 60, which will be described later, are sensors that output a detection signal in accordance with the rotation of the rotating magnet unit 20 described below.

  The data processing unit 10 includes angle calculation units 11 and 12, a memory 13, an electrical angle correction unit 14, an angle position determination unit 15, and a mechanical angle correction unit 16.

  The angle calculation unit 11 performs calculation processing on the detection data after A / D conversion from the magnetoresistive element 50 and the Hall elements 51 and 52 to obtain an angle position. Further, the angle calculation unit 11 outputs the obtained angle position as angle position data. The angle calculation unit 12 performs a calculation process on the detection data after the A / D conversion from the magnetoresistive element 60 to obtain an angle position. Further, the angle calculation unit 12 outputs the obtained angle position as angle position data. The method of obtaining the angle position by the angle calculation units 11 and 12 will be described later.

  The memory 13 stores electrical angle correction data and mechanical angle correction data. Here, the electrical angle correction data is data for correcting a periodic angle error which is common to each pole of the rotating magnet 40 having a large number of magnetic poles of the rotating magnet unit 20 described later. This periodic angle error is caused by a harmonic superimposed on a detection signal (sin, cos) of the magnetoresistive element 60 described later. The harmonic is a wave having a frequency that is an integral multiple of the fundamental wave (one cycle of output with one pole of the magnet), such as 3rd, 5th, 7th, 11th, 13th,. Occurs in prime order.

  In the present embodiment, as described later, the magnetoresistive element 60 is provided with a harmonic canceling pattern 61 for canceling, for example, a seventh or lower harmonic. Therefore, the electrical angle correction data is error correction data for canceling out harmonics exceeding the seventh order. Further, the electrical angle correction data is error correction data for canceling a periodic angle error that is common to each pole of the rotating magnet 40. Here, the electrical angle correction data may have a value obtained by averaging the errors caused by all the harmonics exceeding the seventh order in order to cancel the angle error, or specifying the harmonics exceeding the seventh order. May be a value averaged for each order of. In addition, the electrical angle correction data may include error correction data that can be canceled without remaining by the harmonic canceling pattern 61, for example, the seventh and lower harmonics. In this case, it is possible to cancel out, for example, the seventh or lower harmonic that remains without being canceled by the harmonic canceling pattern 61.

  When the electrical angle correction data has a value obtained by averaging errors caused by all harmonics exceeding the seventh order in order to cancel the angle error, the storage capacity of the memory 13 can be reduced, and the electrical angle correction unit can be used. 14 can shorten the procedure of the correction process. On the other hand, when the electrical angle correction data has a value averaged for each specific order of harmonics exceeding the 7th order to cancel the angle error, the storage capacity of the memory 13 increases, and the electrical angle correction unit 14 Although the number of steps of the correction process increases, the correction process can be performed for each specific order by the electrical angle correction unit 14, so that the periodic angle error that each pole of the rotating magnet 40 has in common can be further reduced. .

  The mechanical angle correction data is error correction data for canceling an angle error due to a mechanical factor. Incidentally, such an angular error due to a mechanical factor is caused by a variation in the magnetization, a displacement of an assembling position, or the like. The positional deviation of the assembling is typically a central deviation between the magnetoresistive element 50 and the rotating magnet 30, a central deviation between the magnetoresistive element 60 and the rotating magnet 40, and the like. In addition, such an angular error occurs periodically as the rotating magnet 40 rotates. That is, such an angular error occurs at a fixed angular position.

  The above-described electrical angle correction data and mechanical angle correction data are error correction data obtained based on a master encoder (not shown). Further, these error correction data are obtained in advance by measurement using a measuring device (not shown) with reference to the master encoder. Then, in the memory 13, the average value of the periodic angle error that is common to the respective poles of the rotating magnet 40 is used as the electrical angle correction data, and is used to cancel the angle error due to mechanical factors. The value of the error correction is stored as mechanical angle correction data.

  When obtaining electrical angle correction data and mechanical angle correction data by a measuring device, a method of performing an Fourier transform on an error of one rotation of the rotating magnet unit 20 with respect to the master encoder and calculating a unique error component can be used. . As described above, since the electrical angle correction data and the mechanical angle correction data are obtained for each of the rotating magnet units 20, it is possible to determine appropriate error correction data for each of the rotating magnet units 20. Further, the measuring device measures, for example, the 7th-order or lower harmonics remaining without being canceled by the harmonic canceling pattern 61 with reference to the master encoder, and uses the measurement result as error correction data. May be included.

  The electrical angle correction unit 14 uses the electrical angle correction data stored in the memory 13 for the angular position data obtained by the angle calculation unit 12 to generate a periodic Cancel angle errors. The angle position determination unit 15 determines the angle position of the rotating magnet unit 20 from the angle position data from the angle calculation unit 11 and the corrected angle position data from the electrical angle correction unit 14. The mechanical angle correction unit 16 uses the mechanical angle correction data stored in the memory 13 to correct the angle position data determined by the angle position determination unit 15. Accordingly, it is possible to cancel an angular error generated by a mechanical factor such as a center shift between the magnetoresistive element 50 and the rotating magnet 30 and a center shift between the magnetoresistive element 60 and the rotating magnet 40.

  The rotating magnet section 20 has rotating magnets 30 and 40. These rotating magnets 30 and 40 are attached to a rotating body (not shown) connected to, for example, a motor shaft of a servo motor, and rotate around a rotation axis L in synchronization with the rotation of the motor shaft.

  The rotating magnet 30 has magnetized surfaces 31, 32 in which the N pole and the S pole are magnetized one by one in the circumferential direction. These magnetized surfaces 31 and 32 are directed to a magnetoresistive element 50 and Hall elements 51 and 52 arranged on the rotating magnet 30.

  On the other hand, the rotating magnet 40 has an annular magnetized surface 41 in which a plurality of N poles and S poles are alternately magnetized in the circumferential direction. A plurality of annular magnetized surfaces 41 are arranged in parallel in the radial direction. In the present embodiment, two rows are formed in the radial direction, and the positions of the N pole and the S pole are shifted in the circumferential direction between the two rows. That is, the N and S poles are shifted by one pole in the circumferential direction between the two rows. Further, the number of pairs of the N pole and the S pole is arbitrary, but is set to, for example, 128 in the present embodiment. The ring-shaped magnetized surface 41 faces the magnetoresistive element 60 arranged on the rotating magnet 40.

  The magnetoresistive element 50 on the rotating magnet 30 has an A phase (SIN) pattern and a B phase (COS) pattern having a phase difference of 90 ° with respect to the phase of the rotating magnet 30. The A-phase (SIN) pattern has a + a-phase (SIN +) magnetoresistive pattern 50c and a -a-phase (SIN-) magnetoresistive pattern 50a for detecting the movement of the rotating magnet 30 with a phase difference of 180 °. . The B-phase (COS) pattern has a + b-phase (COS +) magnetoresistive pattern 50d and a -b-phase (COS-) magnetoresistive pattern 50b that detect the movement of the rotating magnet 30 with a phase difference of 180 °. . Here, the magnetic resistance patterns 50a to 50c constitute a bridge circuit. The Hall elements 51 and 52 are arranged shifted by 90 ° (mechanical angle) in the rotation direction about the rotation axis L.

  The magnetoresistive element 60 on the rotating magnet 40 has an A phase (SIN) pattern and a B phase (COS) pattern having a phase difference of 90 ° with respect to the phase of the rotating magnet 40. The A-phase (SIN) pattern has a + a-phase (SIN +) magnetoresistive pattern 60d and a -a-phase (SIN-) magnetoresistive pattern 60b that detect the movement of the rotating magnet 40 with a phase difference of 180 °. . The B-phase (COS) pattern has a + b-phase (COS +) magnetoresistive pattern 60c and a -b-phase (COS-) magnetoresistive pattern 60a that detect the movement of the rotating magnet 40 with a phase difference of 180 °. . Here, the magnetoresistive patterns 60a to 60d constitute a bridge circuit.

  The magnetoresistive element 60 has a harmonic canceling pattern 61 for canceling harmonics. Here, a sine wave signal having a constant repetition cycle is output from the magnetoresistive element 60 on the rotating magnet 40 having a large number of magnetic poles. As described above, this sine wave signal is a signal in which a harmonic component is superimposed on a fundamental wave component (one cycle output from one pole of the magnet) and the fundamental wave component. The harmonics are generated in the order of prime numbers such as the third, fifth, seventh, eleventh, thirteenth,..., And the smaller the order, the larger the amplitude. In addition, the harmonic appears as an angular error of (order + 1) cycle.

  Therefore, it is theoretically possible to eliminate the angle error by providing the magnetoresistive element 60 with a harmonic canceling pattern 61 capable of canceling harmonics of all orders. However, the harmonic cancellation pattern 61 capable of canceling harmonics of all orders has a large number of pattern repetitions and a large size. Further, the size of the magnetoresistive element 60 is limited due to factors such as the pitch between the magnetic poles of the rotating magnet 40. For this reason, in the present embodiment, the magnetoresistive element 60 is provided with the harmonic cancellation pattern 61 that can cancel, for example, the seventh or lower harmonics. The harmonic cancellation pattern 61 is not limited to the seventh or lower order. For example, the order may be 11 or less, or may be 6 or less.

  The amplifier 70 is provided on the output side of the Hall elements 51 and 52 on the rotating magnet 30 and amplifies the detection signals of the Hall elements 51 and 52. The amplifier 71 is provided on the output side of the magnetoresistive element 50 on the rotating magnet 30, and amplifies the detection signal of the magnetoresistive element 50. The amplifier 72 is provided on the output side of the magnetoresistive element 60 on the rotating magnet 40, and amplifies the detection signal of the magnetoresistive element 60.

  The AC / DC converter 73 is provided on the output side of the amplifier 70 and converts the detection signal amplified by the amplifier 70 into detection data. The AC / DC converter 74 is provided on the output side of the amplifier 71, and converts the detection signal amplified by the amplifier 71 into detection data. The AC / DC converter 75 is provided on the output side of the amplifier 72 and converts the detection signal amplified by the amplifier 72 into detection data.

  Next, with reference to FIG. 2 and FIG. 3, a basic principle of detecting the angular position of the rotating magnet unit 20 when no harmonic is included will be described. 2A shows a waveform of a detection signal of the magnetoresistive element 50 and the Hall elements 51 and 52 on the rotating magnet 30, and FIG. 2B shows an angular position (electrical angle) of the rotating magnet unit 20. Is shown. FIG. 3 shows a method for determining the angular position of the rotating magnet unit 20. FIG. 3A shows the angular position θ obtained from the detection signal (sin, cos) of the magnetoresistive element 50 on the rotating magnet 30 for one cycle. FIG. 3B shows the angular position θ obtained from the detection signal (sin, cos) of the magnetoresistive element 60 on the rotating magnet 40 for one cycle. FIG. 3C shows a case where the absolute angle data shown in FIG. 3A and the incremental angle data shown in FIG. 3B are combined.

  First, when the rotating magnets 30 and 40 rotate, the detection signals of the magnetoresistive element 50 and the Hall elements 51 and 52 on the rotating magnet 30 are amplified by the amplifiers 70 and 71, and are converted into detection data by the A / D converters 73 and 74. The data is converted and provided to the data processing unit 10. The detection signal of the magnetoresistive element 60 on the rotating magnet 40 is amplified by the amplifier 72, converted into detection data by the A / D converter 75, and provided to the data processor 10. The data processing unit 10 obtains the absolute angular position of the rotating magnet unit 20 based on the detection data of the magnetoresistance element 50 and the Hall elements 51 and 52 and the detection data of the magnetoresistance element 60. Note that the absolute angular position of the rotating magnet unit 20 is relative to an arbitrary reference position. Further, the arbitrary reference position may be, for example, a position with respect to a fixed plate (not shown) to which the magnetoresistive element 50, the Hall element 51, and the Hall element 52 on the rotating magnet 30 and the magnetoresistive element 60 on the rotating magnet 40 are attached.

Here, when the rotating magnet 30 makes one rotation, the magnetic flux on the magnetized surfaces 31 and 32 of the rotating magnet 30 changes as shown in FIG. When the rotating magnet 30 makes one rotation, the A-phase (SIN) pattern and the B-phase (COS) pattern having a phase difference of 90 ° from each other of the magnetoresistive element 50 as shown in FIG. , Sinusoidal signals sin and cos are output for two periods. Then, as shown in FIG. 2B, the data processing unit 10 obtains θ = tan ⁻¹ (sin / cos) from the sine wave signals sin and cos, so that the angular position θ of the rotating magnet unit 20 can be obtained. . This calculation process is performed by the angle calculation unit 11.

  Further, the Hall elements 51 and 52 on the rotating magnet 30 are arranged at positions shifted by 90 ° from the center of the rotating magnet 30. Therefore, when the rotating magnet 30 makes one rotation, the outputs of the Hall elements 51 and 52 change in the order of (H, L) → (H, H) → (L, H) → (L, L). That is, by confirming that the output of the Hall elements 51 and 52 is any one of the four, it is possible to know in which section from 0 ° to 360 °. By monitoring the output state of each of the Hall elements 51 and 52, the angular position can be determined even if the combination of the sine output and the cos output of the magnetoresistive element 50 is two as shown in FIG. Therefore, the rotational position and the angular position θ of the rotating magnet 30 can be determined from the output of the magnetoresistive element 50 and the outputs of the Hall elements 51 and 52.

Further, sine wave signals sin and cos corresponding to the number of pairs of the N pole and the S pole of the annular magnetized surface 41 are output from the magnetoresistive element 60 on the rotating magnet 40. In this case, as shown in FIG. 2B, if the sine wave signals sin and cos output from the magnetoresistive element 60 are determined as θ = tan ⁻¹ (sin / cos), the angular position of the rotating magnet 40 can be determined. θ is known. This calculation process is performed by the angle calculation unit 12.

  Here, as shown in FIG. 3A, the absolute angle data of one cycle per rotation based on the detection data after the A / D conversion of the magnetoresistive element 50 and the Hall elements 51 and 52 on the rotating magnet 30 are as shown in FIG. Change. Further, the incremental angle data of one rotation N cycle based on the detection data after the A / D conversion from the magnetoresistive element 60 on the rotating magnet 40 changes as shown in FIG. 3B. Therefore, by combining the absolute angle data shown in FIG. 3A and the incremental angle data shown in FIG. 3B, the absolute angle data shown in FIG. 3C can be obtained. That is, FIG. 3C shows absolute angle data obtained by complementing the absolute angle data shown in FIG. 3A with angle data for 128 poles of the rotating magnet 40.

  Next, with reference to FIG. 4 and FIG. 5, a description will be given of the periodic angle error that each pole of the rotating magnet 40 has in common and the angle error after correction by the electrical angle correction unit 14.

  First, FIG. 4A shows 128 poles, which is the number of pairs of the N pole and the S pole of the rotating magnet 40, in an overlapping manner. FIG. 4A shows an angle error before correction due to a harmonic of a specific order (for example, 11th order). The horizontal axis indicates the angle of one rotation, and the vertical axis indicates the level of the angle error when the resolution is, for example, 20 bits.

  As can be seen from FIG. 4A, when a harmonic of a specific order (for example, the 11th order) is superimposed on the fundamental wave (one cycle of output with one pole of the magnet), the maximum level becomes 20 and -22. Angle error has occurred.

  FIG. 4B shows, as in FIG. 4A, 128 poles, which is the number of pairs of the N pole and the S pole of the rotating magnet 40, superimposed. FIG. 4B shows the corrected angle when the harmonic of a specific order (for example, 11th) is canceled based on the electrical angle correction data obtained by averaging the harmonics of a specific order (for example, 11th). The error is shown. As can be seen from FIG. 4B, an angle error occurs in which the maximum level is 20, -15. However, as can be seen from FIG. 4B, it can be seen that the repetitive angle error in which the maximum level is 20, -22 is canceled.

  FIG. 5 shows the corrected angle error of four poles among the 128 poles in FIG. 4B. As can be seen from FIG. 5, since the eleventh harmonic has been corrected, it can be seen that the angle error component of 12 periods is reduced for one rotation.

  Next, a method of correcting the angle of the rotating magnet unit 20 will be described with reference to FIG. In the following, a description will be given assuming that the detection signal from the magnetoresistive element 60 on the rotating magnet 40 has the seventh or lower harmonic canceled by the harmonic cancellation pattern 61.

(Step S101)
First, when the rotating magnet unit 20 rotates, the amplifiers 70 to 72 amplify the detection signal. That is, the amplifiers 70 and 71 amplify the detection signals of the magnetoresistive element 50 and the Hall elements 51 and 52 on the rotating magnet 30. The amplifier 72 amplifies a detection signal of the magnetoresistive element 60 on the rotating magnet 40.

(Step S102)
A / D-convert the detection signal. That is, the A / D converter 73 A / D converts the detection signals of the Hall elements 51 and 52 on the rotating magnet 30. Further, the A / D converter 74 performs A / D conversion on the detection signal of the magnetoresistive element 50 on the rotating magnet 30. Further, the A / D converter 75 A / D converts the detection signal of the magnetoresistive element 60 on the rotating magnet 40.

(Step S103)
Find the angular position. That is, the angle calculation unit 11 performs a calculation process of θ = tan ⁻¹ (sin / cos) on the detection data after the A / D conversion from the A / D conversion units 73 and 74 to obtain an angle position. In addition, the angle calculation unit 12 performs a calculation process of θ = tan ⁻¹ (sin / cos) on the detection data after the A / D conversion from the A / D conversion unit 75 to obtain an angle position. In addition, in the detection data after A / D conversion from the A / D conversion unit 75, since the harmonic of the seventh order or less is canceled by the harmonic cancellation pattern 61, the data of the harmonic exceeding the seventh order is included. include.

(Step S104)
Correct the electrical angle. That is, the electrical angle correction unit 14 cancels harmonics included in the angle position data obtained by the angle calculation unit 12 based on the electrical angle correction data stored in the memory 13. Here, the electrical angle correction data is, for example, a value obtained by averaging errors caused by all harmonics exceeding the seventh order, as described above. Further, the electrical angle correction data is a value that cancels out the periodic angle error that is commonly possessed by the poles of the rotating magnet 40. Therefore, the electrical angle correction unit 14 corrects the angular position data obtained by the angle calculation unit 12 based on the electrical angle correction data, so that the periodic angle error that each pole of the rotating magnet 40 has in common is reduced. Will be corrected. When the electrical angle correction unit 14 includes error correction data that can be canceled without remaining by the harmonic cancellation pattern 61, for example, the seventh or lower harmonic, At the same time as the harmonics exceeding the seventh order, the remaining harmonics that are not canceled by the harmonic cancellation pattern 61, for example, the harmonics of the seventh order or less are canceled.

(Step S105)
Determine the angular position. That is, the angular position determining unit 15 determines the angular position of the rotating magnet unit 20 from the angular position data from the angle calculating unit 11 and the corrected angular position data from the electrical angle correcting unit 14.

(Step S106)
Correct the mechanical angle. That is, the mechanical angle correction unit 16 cancels the mechanical angle component based on the mechanical angle correction data stored in the memory 13 with respect to the angle position data determined by the angle position determination unit 15. Here, the mechanical angle correction data is a value for canceling an angle error generated by a mechanical factor such as a center shift between the magnetoresistive element 50 and the rotating magnet 30 and a center shift between the magnetoresistive element 60 and the rotating magnet 40. . Note that an angular error individually included in any of the poles of the rotating magnet 40 occurs periodically with the rotation of the rotating magnet 40. Such an angular error occurs at a fixed angular position. Accordingly, the mechanical angle correction unit 16 corrects the angular position data determined by the angular position determination unit 15, thereby correcting an angular error that periodically occurs with the rotation of the rotating magnet 40.

  As described above, in the present embodiment, the magnetoresistive element 50 (first magnetoresistive element) detects the angular position of the rotating magnet 30 (first rotating magnet), and the magnetoresistive element 60 (second magnetoresistive element) ) Cancels harmonics of a predetermined order (for example, 7th order) or less by the harmonic canceling pattern 61 and detects the angular position of the rotating magnet 40 (second rotating magnet), the data processing unit 10 determines the predetermined order ( The detection data of the magnetoresistive element 60 (second magnetoresistive element) is corrected by correction data (for example, electrical angle correction data) that cancels out harmonics exceeding 7th order. As a result, harmonics having a predetermined order (for example, 7th order) or less are canceled by the magnetoresistive element 60 (second magnetic resistance element), and harmonics exceeding a predetermined order (for example, 7th order) are generated by the data processing unit 10. Since the cancellation is canceled, it is possible to cancel the harmonics superimposed on the fundamental wave of the detection signal from the sensor (the magnetoresistive element 60) constituting a part of the rotary encoder 100, and obtain highly accurate rotation position detection data. Can be.

  Further, the electrical angle correction unit 14 uses the electrical angle correction data stored in the memory 13 to cancel a periodic angle error that is common to each pole of the rotating magnet 40 (second rotating magnet), The angular position determining unit 15 detects the detection data of the magnetoresistive element 50 (first magnetoresistive element), the Hall element 51 (first Hall element), the Hall element 52 (second Hall element), and the electrical angle correction unit 14. Determines the angular position of the rotating magnet section 20 based on the corrected detection data, so that it is possible to cancel the periodic angular error that each pole of the rotating magnet 40 (second rotating magnet) has in common. it can.

  If the electrical angle correction data includes data that cancels out harmonics of a predetermined order or less that remain without being canceled by the harmonic cancellation pattern 61, the electrical angle correction unit 14 cancels the data using the harmonic cancellation pattern 61. It is possible to cancel the remaining harmonics of a predetermined order or less.

  Further, since the mechanical angle correction unit 16 uses the mechanical angle correction data stored in the memory 13 to correct the angular position data determined by the angular position determination unit 15, the magnetoresistive element 50 (first magnetoresistive element) And the rotating magnet 30 (first rotating magnet) and the center displacement between the magnetoresistive element 60 (second magnetoresistive element) and the rotating magnet 40 (second rotating magnet). The generated angle error can be canceled.

  In addition, since the electrical angle correction data has a value obtained by averaging errors caused by all harmonics exceeding a predetermined order, the storage capacity of the memory 13 can be reduced, and the predetermined The procedure of the correction processing for canceling the harmonics exceeding the order can be shortened.

  If the electrical angle correction data includes a value obtained by averaging errors due to all harmonics of a predetermined order or less that remain without being canceled by the harmonic canceling pattern 61, As a result, harmonics of a predetermined order or less remaining without being canceled can be canceled.

  When the electrical angle correction data has a value averaged for each specific order of harmonics exceeding the predetermined order, the electrical angle correction unit 14 cancels the harmonics exceeding the predetermined order for each specific order. This can further reduce the periodic angular error that each pole of the rotating magnet 40 (second rotating magnet) has in common.

  If the electrical angle correction data includes a value that is averaged for each specific order of harmonics of a predetermined order or less and remains without being canceled by the harmonic canceling pattern, the electrical angle correction unit 14 Harmonics of a predetermined order or less remaining without being canceled by the cancel pattern 61 can be canceled for each specific order, and each pole of the rotating magnet 40 (second rotating magnet) has in common. Periodic angle error can be further reduced.

  By setting the order of the harmonic canceling pattern 61 of the magnetoresistive element 60 (second magnetoresistive element) to 7 or less, the magnetoresistive element 60 (second magnetoresistive element) is controlled by the harmonic canceling pattern 61. 7th and lower harmonics can be canceled.

DESCRIPTION OF SYMBOLS 10 Data processing part 11, 12 Angle calculation part 13 Memory 14 Electric angle correction part 15 Angular position determination part 16 Mechanical angle correction part 20 Rotating magnet part 30, 40 Rotating magnet 31, 32, 41 Magnetized surface 50, 60 Magnetoresistive element 50a to 50d, 60a to 60d Magnetoresistive pattern 51, 52 Hall element 61 Harmonic cancellation pattern 70-72 Amplifier 73-75 A / D converter 100 Rotary encoder

Claims (18)

Rotation including a first rotating magnet in which N poles and S poles are magnetized one by one in the circumferential direction, and a second rotating magnet in which a plurality of N poles and S poles are alternately magnetized in the circumferential direction. A rotary encoder having a magnet unit,
A first magnetoresistive element for detecting an angular position of the first rotating magnet;
A first Hall element disposed in proximity to the first magnetoresistive element;
A second Hall element arranged at a position shifted by 90 ° in mechanical angle in the circumferential direction with respect to the first Hall element;
A second magnetoresistive element for detecting an angular position of the second rotating magnet;
A data processing unit for determining an angular position of the rotating magnet unit by data processing based on detection data of the first magnetoresistive element, the first hall element, the second hall element, and the second magnetoresistive element With
The second magnetoresistive element is provided with a harmonic cancellation pattern for canceling a harmonic of a predetermined order or less,
The rotary encoder according to claim 1, wherein the data processing unit corrects the detection data of the second magnetoresistive element with correction data for canceling a harmonic that exceeds a predetermined order. The correction data is electrical angle correction data for canceling a periodic angle error that each pole of the second rotating magnet has in common,
The data processing unit includes:
A memory in which the electrical angle correction data is stored;
An electrical angle correction unit that corrects an angle error of detection data of the second magnetoresistive element using the electrical angle correction data;
Determining an angular position of the rotating magnet unit based on detection data of the first magnetoresistive element, the first Hall element, the second Hall element, and detection data corrected by the electrical angle correction unit; The rotary encoder according to claim 1, further comprising an angular position determining unit.   3. The rotary encoder according to claim 2, wherein the electrical angle correction data includes data that cancels a harmonic of a predetermined order or less that remains without being canceled by the harmonic cancel pattern. 4. . The memory stores mechanical angle correction data for canceling an angular error that periodically occurs with the rotation of the first rotating magnet and the second rotating magnet,
4. The rotary encoder according to claim 2, wherein the data processing unit includes a mechanical angle correction unit configured to correct the angular position data determined by the angular position determination unit using the mechanical angle correction data. 5.   The rotary encoder according to claim 2, wherein the electrical angle correction data has a value obtained by averaging errors caused by all harmonics exceeding the predetermined order.   6. The electric angle correction data includes a value obtained by averaging errors remaining due to all harmonics of the predetermined order or less that remain without being canceled by the harmonic canceling pattern. The rotary encoder according to 1.   The rotary encoder according to claim 2, wherein the electrical angle correction data has a value averaged for each specific order of harmonics exceeding the predetermined order.   8. The electric angle correction data according to claim 7, wherein the electric angle correction data includes a value averaged for each specific order of harmonics of the predetermined order or less, which remain without being canceled by the harmonic canceling pattern. Rotary encoder.   The rotary encoder according to any one of claims 1 to 8, wherein the predetermined order is a seventh order. Rotation including a first rotating magnet in which N poles and S poles are magnetized one by one in the circumferential direction, and a second rotating magnet in which a plurality of N poles and S poles are alternately magnetized in the circumferential direction. An angle correction method for a rotary encoder having a magnet unit,
Detecting an angular position of the first rotating magnet with a first magnetoresistive element;
A first Hall element disposed in proximity to the first magnetoresistive element;
A second Hall element arranged at a position shifted by 90 ° in mechanical angle in the circumferential direction with respect to the first Hall element;
Detecting an angular position of the second rotating magnet by a second magnetoresistive element;
A data processor configured to perform data processing based on detection data of the first magnetoresistive element, the first hall element, the second hall element, and the second magnetoresistive element, and perform data processing on the angular position of the rotating magnet unit And a step of determining
The second magnetoresistive element is provided with a harmonic cancellation pattern for canceling a harmonic of a predetermined order or less,
The method according to claim 1, wherein the data processing unit corrects the detection data of the second magnetoresistive element using correction data for canceling a harmonic that exceeds a predetermined order. The correction data is electrical angle correction data for canceling a periodic angle error that each pole of the second rotating magnet has in common,
A step of correcting an angle error of detection data of the second magnetoresistive element using the electric angle correction data stored in a memory by an electric angle correction unit;
An angular position determining unit configured to detect the rotation of the rotating magnet unit based on detection data of the first magnetoresistive element, the first Hall element, and the second Hall element, and detection data corrected by the electrical angle correction unit; Determining the angular position of the rotary encoder. The method of correcting an angle of a rotary encoder according to claim 10, further comprising:   The rotary encoder according to claim 11, wherein the electrical angle correction data includes data that cancels a harmonic of a predetermined order or less that remains without being canceled by the harmonic cancel pattern. Angle correction method. The memory stores mechanical angle correction data for canceling an angular error that periodically occurs with the rotation of the first rotating magnet and the second rotating magnet,
The method of correcting an angle of a rotary encoder according to claim 11, further comprising: using a mechanical angle correction unit to correct the angular position data determined by the angular position determination unit using a mechanical angle correction unit. .   The method according to claim 11, wherein the electrical angle correction data has a value obtained by averaging errors caused by all harmonics exceeding the predetermined order.   The electrical angle correction data includes a value obtained by averaging errors remaining due to all harmonics of the predetermined order or less that remain without being canceled by the harmonic canceling pattern. 3. The angle correction method for a rotary encoder according to 1.   The method according to claim 11, wherein the electrical angle correction data has a value averaged for each specific order of harmonics exceeding the predetermined order.   17. The electric angle correction data according to claim 16, wherein the electric angle correction data includes a value averaged for each specific order of harmonics having a predetermined order or less and remaining without being canceled by the harmonic canceling pattern. Angle correction method for rotary encoders.   18. The method according to claim 10, wherein the predetermined order is a seventh order.

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