JP6842943B2 - Rotary encoder - Google Patents

Description

The present invention relates to a rotary encoder, and more particularly to a magnetic rotary encoder.

As a device for detecting the rotational position of a rotating body with respect to a fixed body, a magnetic rotary encoder using a magnetoresistive element such as a magnetoresistive effect (MR) element or a Hall element is known. In such a rotary encoder, an induced voltage is generated in wiring, a circuit, etc. due to a change in the magnetic field accompanying the rotation of a rotating body (magnet), and the signal component is superimposed on the output signal from the magnetizing element, so that the detection accuracy is high. Is known to have the problem of worsening.

Patent Document 1 describes a method of correcting an error due to an induced voltage by utilizing the fact that the induced voltage is superimposed on an output signal in proportion to the rotation speed of a rotating body. In this method, a correction amount for canceling the induced voltage at a specific rotation speed is stored in advance, and from this correction amount, rotation during use is based on the ratio of the specific rotation speed and the rotation speed during use. The correction value for canceling the induced voltage at the speed is converted. As a result, the correction value that increases in proportion to the rotation speed can be calculated by converting it from the rotation speed at the time of use, and the rotation position of the rotating body can be detected with high accuracy.

Japanese Unexamined Patent Publication No. 2016-99164

However, the correction method described in Patent Document 1 alone cannot remove the error component superimposed on the output signal as the rotating body rotates, and is not sufficient to maintain high detection accuracy.

Therefore, an object of the present invention is to provide a rotary encoder that detects the rotational position of a rotating body with high accuracy.

In order to achieve the above-mentioned object, the rotary encoder of the present invention is a rotary encoder that detects the rotational position of the rotating body with respect to the fixed body, and includes a magnet provided on one of the fixed body and the rotating body, and the fixed body and the rotating body. A magnetic sensor unit provided on the other side of the rotating body to detect a change in the magnetic field from the magnet, which is arranged to face the magnetizing surface of the magnet and outputs a sinusoidal A-phase signal as the rotating body rotates. A second magnetizing element is arranged so as to face the magnetizing surface of the magnet, and outputs a sinusoidal B-phase signal having a phase difference of 90 ° from the A-phase signal as the rotating body rotates. The magnetic sensor unit has a magnetic sensor unit, and a control unit that calculates the rotation position of the rotating body based on the A-phase signal and the B-phase signal, and the control unit has the A-phase signal and the B-phase signal. Of the signal components contained in each of the above, a signal component that decreases non-linearly as the rotation speed of the rotating body increases, and has a plurality of parameters related to the signal component at the reference rotation speed, and the rotation speed of the rotating body with respect to the reference rotation speed. The control unit has a storage unit that stores data indicating the relationship between the ratio of the above and the rate of change of a plurality of parameters, and a rotation speed calculation unit that calculates the current rotation speed of the rotating body. Based on the ratio of the current rotation speed calculated by the calculation unit to the reference rotation speed and the rate of change of the plurality of parameters, at least one of the plurality of parameters stored in the storage unit is set to the current rotation speed. By converting to the value in (1) and compensating for the signal component that decreases based on the converted value, a correction process for correcting the A-phase signal and the B-phase signal is executed, and the corrected A-phase signal and the B-phase signal are obtained. It is used to calculate the rotation position of the rotating body.

According to such a rotary encoder, by correcting the output signal by using the converted value of the parameter related to the signal component that decreases according to the rotation speed, it is possible to obtain an almost constant output signal regardless of the rotation speed. High detection accuracy can be maintained.

In one aspect of the present invention, the reduced signal component is a harmonic component of each of the A-phase signal and the B-phase signal, the plurality of parameters include the amplitude and phase of the harmonic component, and the control unit , Only the amplitude of the above-mentioned plurality of parameters is converted into the current rotation speed, and the decreasing signal component is compensated based on the converted amplitude and the phase stored in the storage unit, or a plurality of signals components are compensated. It is preferred to convert both the amplitude and phase of the parameters to the values at the current rotational speed and compensate for the decreasing signal component based on the converted amplitude and phase.

In this case, when the amplitude and phase are calculated by rotating the rotating body at a constant rotation speed as a reference rotation speed and superimposing predetermined signal components on the A-phase signal and the B-phase signal, respectively. In addition, it is preferable that the amplitude and phase of a predetermined signal component when the ripple of the calculated rotation speed is minimized. By such a method, the signal component to be reduced can be easily obtained without performing analysis processing such as frequency analysis. Further, the reference rotation speed is preferably the instantaneous maximum rotation speed of the motor connected to the rotating body, whereby, as parameters, the amplitude and phase when the change of the decreasing signal component to be compensated is maximized. Can be set, and the output signal can be corrected with high resolution. Further, the calculation of the amplitude and the phase can be simplified by performing the calculation by the rotary encoder calibrated when the rotating body is rotated at a speed lower than the reference rotation speed. Further, the harmonic components are 11th and 13th harmonic components, and in that case, each magnetizing element has an A-phase signal in which the 3rd, 5th, and 7th harmonic components are cancelled. It is preferably configured to output a B-phase signal. As a result, the above-mentioned correction processing is applied only to the 11th and 13th harmonic components, and does not need to be applied to the 3rd, 5th, and 7th harmonic components, so that the arithmetic processing can be simplified. can do.

Further, in one aspect of the present invention, a low-pass filter is provided between the magnetic sensor unit and the control unit. Thereby, the rate of change of the above-mentioned parameters can be easily obtained.

Further, it is preferable that the control unit calculates the rotation position of the rotating body when the request signal from the outside is received. In this case, the rotation speed calculation unit measures the reception interval of the request signal from the outside, and calculates the current rotation speed of the rotating body from the amount of rotational displacement of the rotating body in the measured reception interval. Good. As a result, since the control unit measures the cycle in which the rotation position is actually calculated, the accurate rotation speed can be calculated, and the correction accuracy of the output signal can be improved. Alternatively, the rotation speed calculation unit may calculate the current rotation speed of the rotating body from the amount of rotational displacement of the rotating body at the reception interval of the request signal preset with the outside. This makes it possible to simplify the arithmetic processing related to the calculation of the rotation speed.

Further, the rotary encoder of the present invention may have a plurality of magnets and a plurality of magnetic sensor units, and the plurality of magnets have one north pole and one south pole arranged in the circumferential direction of the rotating body. The first magnet may be included, and a second magnet in which a plurality of N poles and S poles are alternately arranged in the circumferential direction of the rotating body may be included, and a plurality of magnetic sensor units may be attached to the first magnet. It may include at least one corresponding magnetic sensor unit and a magnetic sensor unit corresponding to the second magnet. In this case, the control unit calculates the rotation position of the rotating body based on the plurality of A-phase signals and the plurality of B-phase signals from the plurality of magnetic sensor units, and at that time, the magnetic sensor unit corresponding to the second magnet. It is preferable to execute the above correction process. According to such a configuration, it is possible to improve the detection accuracy of the rotation position of the rotating body regardless of the rotation speed.

Further, it is preferable that each magnetic sensing element has a magnetoresistive effect element. Thereby, the A-phase signal and the B-phase signal can be easily obtained from one element.

According to the present invention, it is possible to provide a rotary encoder that detects the rotational position of a rotating body with high accuracy.

It is the schematic which shows the structure of the rotary encoder which concerns on one Embodiment of this invention. It is a figure for demonstrating the detection principle of the absolute angle position of the rotating body in the rotary encoder of this embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The rotary encoder of the present invention detects the rotational position of a rotating body with respect to a fixed body. In the present specification, the present invention will be described by taking as an example a rotary encoder in which a magnet is provided in a rotating body and a magnetic sensor unit (magnetic sensor) is provided in a fixed body. It is not limited to, and may be vice versa. That is, the present invention can also be applied to a rotary encoder in which a magnetizing element is provided in a rotating body and a magnet is provided in a fixed body.
FIG. 1 is a schematic view showing a configuration of a rotary encoder according to an embodiment of the present invention. FIG. 1A is a schematic perspective view of the rotary encoder of the present embodiment, and FIG. 1B is a block diagram of the rotary encoder of the present embodiment.

As shown in FIGS. 1 (a) and 1 (b), the rotary encoder 10 of the present embodiment includes a first magnet 20, a second magnet 30, a first magnetic sensor unit 40, and a second magnet. It has a magnetic sensor unit 50, a third magnetic sensor unit 60, and a control unit 70. The first magnet 20 and the second magnet 30 are provided on a rotating body (not shown) that rotates about the rotation axis L, and can rotate together with the rotating body. The first magnetic sensor unit 40, the second magnetic sensor unit 50, and the third magnetic sensor unit 60 are provided on a fixed body (not shown). For example, the rotating body is connected to the output shaft of the motor, and the fixed body is fixed to the frame of the motor. The first to third magnetic sensor units 40, 50, and 60 are connected to the control unit 70 via an amplifier circuit (not shown) and low-pass filters (LPF) 80a, 80b, and 80c, respectively.

The first magnet 20 is arranged on the rotation axis L of the rotating body, and is composed of a disk-shaped permanent magnet (for example, a bond magnet) whose center coincides with the rotation axis L, and has north and south poles in the circumferential direction. It has a magnetized surface 21 arranged one pole at a time. On the other hand, the second magnet 30 is arranged so as to surround the outer side in the radial direction of the first magnet 20, and is composed of a cylindrical permanent magnet (for example, a bond magnet) whose center coincides with the rotation axis L in the circumferential direction. It has an annular magnetized surface 31 in which a plurality of N poles and S poles are alternately arranged. A plurality of tracks 32a and 32b (two in the illustrated embodiment) arranged in parallel in the radial direction of the rotating body are formed on the magnetized surface 31 of the second magnet 30. A total of n (n is an integer of 2 or more, for example, N = 64) magnetic pole pairs composed of N poles and S poles are formed on the tracks 32a and 32b along the circumferential direction. The two tracks 32a and 32b adjacent to each other in the radial direction are arranged so as to be offset in the circumferential direction, and in the present embodiment, they are arranged so as to be offset by one pole in the circumferential direction.

The first magnetic sensor unit 40 and the second magnetic sensor unit 50 detect changes in the magnetic field from the first magnet 20, and are arranged so as to face the magnetizing surface 21 of the first magnet 20, respectively. Has been done. The third magnetic sensor unit 60 detects a change in the magnetic field from the second magnet 30, and is arranged so as to face the magnetizing surface 31 of the second magnet 30.

The first magnetic sensor unit 40 includes two sensors (magnetosensitive elements) composed of four magnetoresistive patterns 41 to 44, each of which is composed of two magnetoresistive effect (MR) elements. Specifically, the first magnetic sensor unit 40 includes an A-phase sensor that outputs a sinusoidal A-phase signal (sin) as the rotating body rotates, and an A-phase signal and 90 as the rotating body rotates. It is equipped with a B-phase sensor that outputs a sinusoidal B-phase signal (cos) having a phase difference of °. The A-phase sensor has a reluctance pattern 43 that outputs a sinusoidal + a-phase signal (sin +) and a magnetoresistance that outputs a sinusoidal −a-phase signal (sin−) having a phase difference of 180 ° from the + a-phase signal. It has a pattern 41. Each reluctance pattern 43, 41 is composed of two MR elements connected in series, and these two reluctance patterns 43, 41 are connected in parallel to form a bridge circuit. The B-phase sensor has a reluctance pattern 44 that outputs a sinusoidal + b-phase signal (cos +) and a magnetoresistance that outputs a sinusoidal −b-phase signal (cos−) having a phase difference of 180 ° from the + b-phase signal. It has a pattern 42 and. Each reluctance pattern 44, 42 is composed of two MR elements connected in series, and like the A-phase sensor, these two reluctance patterns 44, 42 are connected in parallel to form a bridge circuit. ..

The second magnetic sensor unit 50 includes a first Hall element 51 and a second Hall element 52 arranged at a position 90 ° away from the first Hall element 51 about the rotation axis L. doing.

The third magnetic sensor unit 60 includes two sensors (magnetosensitive elements) composed of four magnetoresistive patterns 61 to 64, each of which is composed of two MR elements. Specifically, the third magnetic sensor unit 60 includes an A-phase sensor that outputs a sinusoidal A-phase signal (sin) as the rotating body rotates, and an A-phase signal and 90 as the rotating body rotates. It is equipped with a B-phase sensor that outputs a sinusoidal B-phase signal (cos) having a phase difference of °. The A-phase sensor has a reluctance pattern 64 that outputs a sinusoidal + a-phase signal (sin +) and a magnetoresistance that outputs a sinusoidal −a-phase signal (sin−) having a phase difference of 180 ° from the + a-phase signal. It has a pattern 62 and. Each reluctance pattern 64, 62 is composed of two MR elements connected in series, and these two reluctance patterns 64, 62 are connected in parallel to form a bridge circuit. The B-phase sensor has a reluctance pattern 63 that outputs a sinusoidal + b-phase signal (cos +) and a magnetoresistance that outputs a sinusoidal −b-phase signal (cos−) having a phase difference of 180 ° from the + b-phase signal. It has a pattern 61. Each reluctance pattern 63, 61 is composed of two MR elements connected in series, and these two reluctance patterns 63, 61 are connected in parallel to form a bridge circuit.

The control unit 70 is composed of a microcomputer including a central processing unit (CPU), a random access memory (RAM), a read-only memory (ROM), and the like, and the first to third magnetic sensor units 40, 50, 60. The rotation position (absolute angle position) of the rotating body is calculated based on the output signal output from.

Here, with reference to FIG. 2, the principle of detecting the absolute angular position of the rotating body in the present embodiment will be described. FIG. 2A shows the magnetic poles and strengths of the first magnet, the output signal from the first magnetic sensor unit, and the first Hall element with respect to the change in the mechanical angle of the rotating body from a specific reference position. The output signal of the above and the output signal from the second Hall element are shown. FIG. 2B shows the relationship between the output signal and the electric angle θ. Here, the mechanical angle refers to an angle determined geometrically or mechanically, and the electric angle refers to an angle determined from the phase of the output signal from the magnetic sensing element. In FIG. 2A, the output signals from the first and second Hall elements are represented by H or L binary signals obtained via the comparator.

When the rotating body makes one rotation, the first magnet 20 also makes one rotation (rotates by 360 ° in the mechanical angle). Therefore, from the first magnetic sensor unit 40, as shown in FIG. 2A, the A-phase signal (sin) for two cycles, that is, the electric angle (angle determined by the phase of the output signal) of 720 °. And the B phase signal (cos) is output. From these A-phase signals and B-phase signals, the electric angle θ is calculated using the relational expression ^{θ = tan -1 (sin / cos) as shown in FIG. 2 (b).} However, since the rotating body rotates 360 ° at the mechanical angle and 720 ° at the electric angle, the absolute angle position of the rotating body cannot be obtained only by calculating the electric angle θ. Therefore, two Hall elements 51 and 52 arranged at positions 90 ° apart from each other with respect to the rotation axis L are used. That is, the polarity of the magnetic field generated by the first magnet 20 is determined from the output signals output from the two Hall elements 51 and 52, and from there, the mechanical angle is determined as shown by the alternate long and short dash line in FIG. 2A. It is determined in which quadrant of the plane coordinate system the rotation position is located. In this way, the absolute angular position of the rotating body can be calculated.

On the other hand, from the third magnetic sensor unit 60, each time the rotating body rotates by a pair of magnetic poles in the circumferential direction of the second magnet 30, the same as that shown in FIG. 2A, respectively. A-phase signal (sin) and B-phase signal (cos) for two cycles (that is, 720 ° in electrical angle) are output. Therefore, the A-phase signal and the B-phase signal output from the third magnetic sensor unit 60 also correspond to a pair of magnetic poles of the second magnet 30 by the same principle as the first magnetic sensor unit 40 described above. The absolute angular position of the rotating body within the angle to be magnetized is calculated. Since the detection resolution of the absolute angular position by the third magnetic sensor unit 60 is higher than that by the first magnetic sensor unit 40, the absolute angular position of the rotating body can be calculated with high resolution by combining these. ..

In the rotary encoder 10 of the present embodiment, as shown in FIG. 1B, analog low-pass filters (LPF) 80a, 80b, 80c are provided between the magnetic sensor units 40, 50, 60 and the ADC 71 of the control unit 70. Is provided. The output signals from the magnetic sensor units 40, 50, and 60 contain harmonic components. Due to the LPF8a, 80b, 80c, in particular, the A-phase signal and the B-phase signal from the third magnetic sensor unit 60, respectively. It has been confirmed by the present inventors that the harmonic component of the above decreases according to the rotation speed of the rotating body. Specifically, the 11th and 13th harmonic components of the A phase signal of the third magnetic sensor unit 60 and the 11th and 13th harmonic components of the B phase signal correspond to the gain frequency characteristics of the LPF80c. As such, it has been confirmed that the amplitude decreases non-linearly as the rotation speed increases. The Lissajous waveform calculated from the A-phase signal and the B-phase signal obtained at this time (see the broken line in FIG. 2B) is an ideal circle from a dodecagon when the 11th and 13th harmonic components are included. It is also considered that those harmonic components are preferably attenuated in order to approach. However, in the present embodiment, the rotary encoder 10 for removing design errors, assembly errors, and the like is calibrated by rotating the rotating body at a very low speed (for example, 60 rpm) immediately after manufacturing. Therefore, the A-phase signal and the B-phase signal used for calibration contain most of the 11th and 13th harmonic components, respectively. Therefore, if the 11th and 13th harmonic components are attenuated as the rotation speed of the rotating body increases, the output waveform obtained at that time is deformed from that at the time of calibration, and as a result, the detection error increases. It will be.

Therefore, in the present embodiment, in order to maintain stable detection accuracy regardless of the rotation speed of the rotating body, the control unit 70 compensates for the signal component that decreases non-linearly with the increase in the rotation speed. It has a function of correcting the output signal from the magnetic sensor unit 60 of the above. Specifically, the control unit 70 has parameters related to the harmonic components of the A-phase signal and the B-phase signal from the third magnetic sensor unit 60 at the reference rotation speed, and the rate of change of the rotation speed (reference rotation speed). And the data showing the relationship between the rotation speed of the rotating body) and the rate of change of the parameters are stored. Then, based on the ratio of the current rotation speed to the reference rotation speed and the above data, the stored parameters are converted into the values at the current rotation speed, and the A-phase signal and the B-phase are converted based on the converted values. Correct the signal. In this way, by compensating for the harmonic component that decreases non-linearly with the increase in the rotation speed, a substantially constant output signal regardless of the rotation speed can be obtained, and high detection accuracy can be maintained.

Hereinafter, the functional configuration of the control unit 70 will be described with reference to FIG. 1B again, focusing mainly on the function related to this correction process.

The control unit 70 includes an A / D conversion unit (ADC) 71, an angle calculation unit 72, and a correction processing unit 73, and the correction processing unit 73 rotates with a storage unit 74, a communication cycle measurement unit 75, and so on. It has a speed calculation unit 76.

The ADC 71 converts the analog signals output from the first to third magnetic sensor units 40, 50, 60 into digital signals and outputs them to the angle calculation unit 72 and the correction processing unit 73. The angle calculation unit 72 calculates the rotation position of the rotating body described above based on the output signals from the first to third magnetic sensor units 40, 50, 60 digitally converted by the ADC 71. At this time, the angle calculation unit 72 acquires correction information from the correction processing unit 73 for compensating for the signal components that decrease in each of the A-phase signal and the B-phase signal of the third magnetic sensor unit 60. Then, the angle calculation unit 72 corrects the output signal based on the acquired correction information, and calculates the rotation position of the rotating body using the corrected output signal by the above calculation method.

From the storage unit 74, the correction processing unit 73 determines the parameters related to the harmonic components of the A-phase signal and the B-phase signal at the reference rotation speed, and the rate of change of the rotation speed (reference rotation speed and rotation speed of the rotating body). Data showing the relationship between the ratio) and the rate of change of the above parameters is acquired. Then, the correction processing unit 73 converts the above parameter into a value at the current rotation speed based on the data and the ratio of the current rotation speed calculated by the rotation speed calculation unit 76 to the reference rotation speed.

The storage unit 74 contains parameters related to the above-mentioned harmonic components, specifically, the amplitudes and phases of the 11th and 13th harmonic components of the A-phase signal at the reference rotation speed, and 11 of the B-phase signal. The amplitude and phase of the next and thirteenth harmonic components are stored. Here, as described above, the amplitude of the harmonic component changes non-linearly with the rotation speed, but the phase also changes non-linearly with the rotation speed, for example, corresponding to the phase frequency characteristics of LPF80a to 80c. .. Therefore, the storage unit 74 describes the relationship between the rotation speed of the rotating body and the respective amplitudes, specifically, the rate of change in the rotation speed (the ratio between the reference rotation speed and the rotation speed of the rotating body) and the change in each amplitude. Store data (table, etc.) that shows the relationship with the rate. The storage unit 74 also stores data (table or the like) showing the relationship between the rate of change in the rotation speed of the rotating body (ratio of the reference rotation speed and the rotation speed of the rotating body) and the rate of change in each phase. Therefore, when the correction processing is performed, the amplitude and phase at the reference rotation speed stored in the storage unit 74 are similarly stored in the storage unit 74 based on the data of the respective rate of change, and the correction processing unit 73. After being converted into the amplitude and phase at the current rotation speed, it is sent to the angle calculation unit 72. Then, the angle calculation unit 72 generates a correction signal for compensating for the attenuated signal component from the amplitude and phase converted by the correction processing unit 73, and adds the correction signals to correct the output signal. Data on the amplitude and phase change rate of the harmonic components can be obtained, for example, based on the gain frequency characteristics and the phase frequency characteristics of the LPFs 80a to 80c, respectively. In order to simplify the arithmetic processing, the phase of the harmonic component may be corrected on the assumption that it is constant regardless of the rotation speed (that is, the rate of change is zero).

The communication cycle measuring unit 75 measures the communication cycle between the upper control device (not shown) outside the rotary encoder 10 and the control unit 70. For example, the control unit 70 calculates the rotation speed of the rotating body when it receives a request signal from a higher-level control device, but the communication cycle measurement unit 75 receives the request signal from the control unit 70. The time is measured, and the reception interval of the request signal is measured from that time.

The rotation speed calculation unit 76 is based on the reception interval measured by the communication cycle measurement unit 75 and the information on the rotation position of the rotation body acquired from the angle calculation unit 72, and the rotation displacement amount of the rotation body at a predetermined time interval. Is calculated, and the current rotation speed of the rotating body is calculated from it. Therefore, since the rotation speed calculation unit 76 measures the cycle in which the control unit 70 actually calculates the rotation position, it is possible to calculate an accurate rotation speed even when the actual communication cycle fluctuates. As a result, the correction accuracy by the correction processing unit 73 can be improved. Since the cycle (reception interval) for the control unit 70 to receive the request signal from the upper control device is set in advance, it is fixed as described in Patent Document 1 in order to simplify the arithmetic processing. The rotation speed may be calculated using the set value.

The parameters stored in the storage unit 76 are set as follows using the rotary encoder 10 calibrated at a low speed (for example, 60 rpm) before the rotary encoder 10 is shipped from the factory. First, the motor connected to the rotating body is rotated at a constant rotation speed to output an A-phase signal and a B-phase signal. Here, since the rotation speed is constant, if the output signal is not ideal and contains an error, ripple appears in the rotation speed of the rotating body calculated from it, but it is ideal without error. If it is an output signal, ripple will not appear. Therefore, a predetermined signal component is superimposed on each of the A-phase signal and the B-phase signal including the signal component that decreases with the rotation speed, and the rotation speed of the rotating body is calculated from them. Then, the amplitude and phase of the superimposed signal components are adjusted to the optimum values so as to compensate for the reduced signal components, and the ripple of the calculated rotation speed is minimized. The respective amplitudes and phases at this time are set as parameters. By such a method, the signal component to be reduced can be easily obtained without performing analysis processing such as frequency analysis. The rotation speed of the motor when setting the parameters is preferably the instantaneous maximum rotation speed (for example, 6000 rpm). As a result, the amplitude and phase when the decreasing signal component to be compensated is maximized can be set as the correction parameters, and the output signal can be corrected with high resolution.

Since the magnetic sensitive element has a temperature characteristic, when the output signal changes in temperature, the amplitude of the harmonic component also changes in temperature. Therefore, the temperature change of the third magnetic sensor unit 60 may be monitored by using the temperature detecting means, and the harmonic component may be corrected based on the monitoring result. Alternatively, the temperature of the third magnetic sensor unit 60 may be adjusted to be constant by using the temperature detecting means and the heating means.

In the present embodiment, it is known that the wiring pattern is adjusted for odd-order harmonic components other than the above-mentioned 11th-order and 13th-order harmonic components, for example, the third-order, fifth-order, and seventh-order harmonic components. It is designed to be canceled by the method. That is, the A-phase sensor and the B-phase sensor of the third magnetic sensor unit 60 are configured to output the A-phase signal and the B-phase signal in which the third-order, fifth-order, and seventh-order harmonic components are canceled, respectively. Has been done. As a result, the above-mentioned correction processing is applied only to the 11th and 13th harmonic components, and does not need to be applied to the 3rd, 5th, and 7th harmonic components, so that the arithmetic processing can be simplified. can do.

10 Rotary encoder 20 First magnet 21 Magnetized surface 30 Second magnet 31 Magnetized surface 32a, 32b Track 40 First magnetic sensor section 41-44 Magnetic resistance pattern 50 Second magnetic sensor section 51 First hole Element 52 Second Hall element 60 Third magnetic sensor unit 61-64 Magnetic resistance pattern 70 Control unit 71 A / D conversion unit (ADC)
72 Angle calculation unit 73 Correction processing unit 74 Storage unit 75 Communication cycle measurement unit 76 Rotation speed calculation unit 80a to 80c Low-pass filter (LPF)

Claims (14)

A rotary encoder that detects the rotational position of a rotating body with respect to a fixed body.
A magnet provided on one of the fixed body and the rotating body,
A magnetic sensor unit provided on the other side of the fixed body and the rotating body to detect a change in the magnetic field from the magnet, which is arranged so as to face the magnetizing surface of the magnet and accompanies the rotation of the rotating body. The first magnetizing element that outputs a sinusoidal A-phase signal is arranged so as to face the magnetizing surface of the magnet, and has a phase difference of 90 ° from the A-phase signal as the rotating body rotates. A magnetic sensor unit having a second magnetic sensing element that outputs a sinusoidal B-phase signal, and
It has a control unit that calculates the rotation position of the rotating body based on the A-phase signal and the B-phase signal.
The control unit
Among the signal components contained in each of the A-phase signal and the B-phase signal, a signal component that decreases non-linearly with an increase in the rotation speed of the rotating body, and a plurality of parameters relating to the signal component at the reference rotation speed. A storage unit that stores data indicating the relationship between the ratio of the rotation speed of the rotating body to the reference rotation speed and the rate of change of the plurality of parameters.
It has a rotation speed calculation unit for calculating the current rotation speed of the rotating body, and has a rotation speed calculation unit.
The control unit is stored in the storage unit based on the ratio of the current rotation speed calculated by the rotation angle calculation unit to the reference rotation speed and the rate of change of the plurality of parameters. The A-phase signal and the B-phase signal are corrected by converting at least one of the parameters of the above to a value at the current rotation speed and compensating for the decreasing signal component based on the converted value. A rotary encoder that executes a correction process to calculate the rotation position of the rotating body using the corrected A-phase signal and the B-phase signal. The rotary encoder according to claim 1, wherein the decreasing signal component is a harmonic component of each of the A-phase signal and the B-phase signal, and the plurality of parameters include the amplitude and phase of the harmonic component. .. The control unit converts only the amplitude of the plurality of parameters into the current rotation speed, and the decreasing signal is based on the converted amplitude and the phase stored in the storage unit. The rotary encoder according to claim 2, wherein the component is compensated. The control unit converts both the amplitude and the phase of the plurality of parameters into values at the current rotation speed, and compensates for the decreasing signal component based on the converted amplitude and phase. Item 2. The rotary encoder according to Item 2. For the amplitude and phase, the rotation speed of the rotating body was calculated by rotating the rotating body at a constant rotation speed as the reference rotation speed and superimposing predetermined signal components on the A-phase signal and the B-phase signal, respectively. The rotary encoder according to any one of claims 2 to 4, which is the amplitude and phase of the predetermined signal component when the ripple of the calculated rotation speed is minimized. The rotary encoder according to claim 5, wherein the reference rotation speed is the instantaneous maximum rotation speed of the motor connected to the rotating body. The rotary encoder according to claim 5 or 6, wherein the calculation of the amplitude and the phase is performed by the rotary encoder calibrated when the rotating body is rotated at a speed lower than the reference rotation speed. The rotary encoder according to any one of claims 2 to 7, wherein the harmonic component is an 11th-order and 13th-order harmonic component. The rotary according to claim 8, wherein each of the magnetic sensing elements is configured to output the A-phase signal and the B-phase signal in which the third-order, fifth-order, and seventh-order harmonic components are canceled. Encoder. The rotary encoder according to any one of claims 1 to 9, wherein a low-pass filter is provided between the magnetic sensor unit and the control unit. When the control unit receives a request signal from the outside, the rotation position of the rotating body is calculated, and the rotation position is calculated.
The claim that the rotation speed calculation unit measures the reception interval of the request signal from the outside, and calculates the current rotation speed of the rotating body from the rotational displacement amount of the rotating body in the measured reception interval. The rotary encoder according to any one of 1 to 10. When the control unit receives a request signal from the outside, the rotation position of the rotating body is calculated, and the rotation position is calculated.
Claims 1 to 11, wherein the rotation speed calculation unit calculates the current rotation speed of the rotating body from the amount of rotational displacement of the rotating body at a reception interval of the request signal preset with the outside. The rotary encoder according to any one item. It has a plurality of the magnets and a plurality of the magnetic sensor units.
The plurality of magnets are a first magnet in which one north pole and one south pole are arranged in the circumferential direction of the rotating body, and a plurality of north poles and south poles are alternately arranged in the circumferential direction of the rotating body. Including the second magnet
The plurality of magnetic sensor units include at least one magnetic sensor unit corresponding to the first magnet and a magnetic sensor unit corresponding to the second magnet.
The control unit calculates the rotation position of the rotating body based on the plurality of A-phase signals and the plurality of B-phase signals from the plurality of magnetic sensor units, and at that time, corresponds to the second magnet. The rotary encoder according to any one of claims 1 to 12, which executes the correction process on the magnetic sensor unit. The rotary encoder according to any one of claims 1 to 13, wherein each magnetizing element has a magnetoresistive effect element.

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