JP2015114209A - Encoder and electric machinery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a position with high accuracy using an encoder.SOLUTION: The encoder comprises an M1-pole first magnet body (M1 is an even number of 4 or more), an M2-pole first magnet body (M2 is an even number of 2 or more), a first biaxial magnetic sensor circuit, a second biaxial magnetic sensor circuit, and a position signal generation unit. Each of the biaxial magnetic sensor circuits includes a plurality of X-axis Hall effect elements and a plurality of Y-axis Hall effect elements, generates a position signal in accordance with the output signals of these Hall effect elements, and outputs the generated signal. The position signal generation unit generates a position signal indicating the position of a second member with respect to a first member in accordance with a first magnetic angle output of the first biaxial magnetic sensor circuit and a second magnetic angle output of the second biaxial magnetic sensor circuit.

Description

  The present invention relates to an encoder using a magnetic sensor and an electromechanical device using the encoder.

  As an encoder using a magnetic sensor, a rotary encoder described in Patent Document 1 is known. The rotary body of the rotary encoder is provided with a first magnet at the center and a plurality of annular second magnets on the outer peripheral side. Further, the fixed body facing the rotating body is provided with a first magnetosensitive element for detecting the magnetic field of the first magnet and a second magnetosensitive element for detecting the magnetic field of the second magnet. Each of the first magnetosensitive element and the second magnetosensitive element is composed of two magnetoresistive patterns provided in directions orthogonal to each other. In order to appropriately detect the magnetic field with the magnetoresistive pattern, the first magnet and the second magnet are magnetized along the direction toward the magnetosensitive element (that is, the direction parallel to the rotation axis), and the magnetized surface thereof. (A surface orthogonal to the magnetization direction) is arranged to face the magnetosensitive element. However, an absolute rotation angle cannot be detected with these first and second magnetosensitive elements. Therefore, in order to detect an absolute rotation angle, two Hall elements arranged at an angle of 90 degrees are provided on the fixed body.

JP 2012-112707 A

  However, in the conventional encoder described above, since the magnetic field is detected using the magnetoresistive pattern, the detection accuracy of the rotation angle is limited by the accuracy of the resistance of the magnetoresistive pattern. In general, it is difficult to increase the accuracy of the resistance of the magnetoresistive pattern. Therefore, a technique capable of detecting the rotation angle with higher accuracy has been desired. Further, not only the rotation angle but generally an encoder capable of detecting a position with high accuracy has been desired. Furthermore, regarding an electromechanical device, a technique that enables highly accurate position detection using an encoder has been desired.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms.

(1) According to one form of this invention, the encoder which measures the position of the 2nd member which moves along a predetermined | prescribed movement direction with respect to a 1st member is provided. The encoder is provided in the second member, and is provided in the second member; a first magnet body having an M1 pole (M1 is an even number of 4 or more) magnetized in a direction crossing the moving direction; A second magnet body having M2 poles (M2 is an even number of 2 or more) magnetized in a direction crossing the moving direction; and having a certain gap from the surface of the first magnet body, on the first member A first biaxial magnetic sensor circuit disposed; a second biaxial magnetic sensor circuit disposed on the first member with a certain gap from a surface of the second magnet body; A two-axis magnetic sensor circuit and a position signal generation unit that processes an output signal of the second two-axis magnetic sensor circuit. The position signal generator is configured to output the first member with respect to the first member according to a first magnetic angle output of the first two-axis magnetic sensor circuit and a second magnetic angle output of the second two-axis magnetic sensor circuit. A position signal indicating the position of the second member is generated.
According to this encoder, since a biaxial magnetic sensor circuit is used, position detection can be performed with high accuracy. The position signal generation unit generates a position signal according to the first magnetic angle output of the first two-axis magnetic sensor circuit and the second magnetic angle output of the second two-axis magnetic sensor circuit. Position detection can be performed with higher accuracy than in the case of using a biaxial magnetic sensor circuit.

(2) In the encoder, each of the first two-axis magnetic sensor circuit and the second two-axis magnetic sensor circuit measures a magnetic field along the X axis of the X axis and the Y axis orthogonal to each other. A plurality of X-axis sensor elements for measuring, and a plurality of Y-axis sensor elements for measuring a magnetic field along the Y-axis.
According to this configuration, it is possible to obtain a sine wave-like output with less magnetostriction as the output of a plurality of Hall elements of the two-axis magnetic sensor circuit, and accurately detect the position based on these sine wave-like outputs with little magnetostriction. Can be done.

(3) In the encoder, the integers M1 and M2 are integers in which M1 / 2 and M2 / 2 are prime, and the position signal generation unit is configured to output a first magnetic angle of the first biaxial magnetic sensor. The position signal may be generated from an output and a second magnetic angle output of the second two-axis magnetic sensor.
According to this configuration, the position of the second member relative to the first member can be detected with high accuracy from the first magnetic angle output of the first two-axis magnetic sensor and the second magnetic angle output of the second two-axis magnetic sensor. It is.

(4) In the encoder, the integer M1 is equal to 2 ^{Q + 1} (Q is an integer of 1 or more), the integer M2 is equal to 2, and the first magnetic angle of the first two-axis magnetic sensor circuit The output is a digital signal of N1 bits (N1 is an integer of 2 or more) indicating the relative position of the second member with respect to the first member, and the second magnetic angle output of the second biaxial magnetic sensor circuit is: The digital signal of N2 bits (N2 is an integer of 2 or more) indicating the relative position of the second member with respect to the first member, and the position signal generation unit outputs the most significant Q bit of the second magnetic angle output It is also possible to generate a (N1 + Q) -bit signal as the position signal in which the N1 bit of the first magnetic angle output is arranged below the most significant Q bit of the second magnetic angle output. .
According to this configuration, since the number of bits of the position signal can be increased by combining the most significant Q bit of the second magnetic angle output and the N1 bit of the first magnetic angle output, position detection with high accuracy (high resolution) Is possible.

(5) In the encoder, the position signal generation unit includes the first magnetic angle output of the first two-axis magnetic sensor circuit and the second two-axis magnetic sensor circuit according to the movement of the second member. When the first magnetic angle output of the second magnetic angle output increases, the timing at which the first magnetic angle output returns from the maximum value of the first magnetic angle output to the minimum value, and the highest Q of the second magnetic angle output. The most significant Q bit of the second magnetic angle output is corrected in accordance with the first magnetic angle output so that the timing at which the bit is incremented, and the highest magnetic bit output of the second magnetic angle output after the correction is corrected. The position signal of the (N1 + Q) bits may be generated using the upper Q bits.
According to this configuration, even when there is a non-negligible error in the second magnetic angle output, the combination of the most significant Q bit of the second magnetic angle output and the N1 bit of the first magnetic angle output is correct. A position signal can be obtained.

(6) In the encoder, the second member is a rotating body, and each small magnet constituting the magnet body has a magnetization direction perpendicular to a facing direction of the first member and the second member. The magnets may be magnetized in parallel along a magnetization direction parallel to a direction connecting the centers of the individual small magnets and the rotation axis of the rotating body.
According to this configuration, it is possible to obtain a sinusoidal output with little magnetostriction by detecting the magnetic field of the magnets magnetized in parallel with the Hall element of the two-axis magnetic sensor circuit.

(7) In the encoder, the second member has an annular yoke member provided on at least one of an inner periphery and an outer periphery of the magnet body, and the biaxial magnetic sensor circuit has a diameter of the second member. It is preferable that the magnetic flux density measured along the direction is arranged at a position where the magnetic flux central portion that becomes 0 is removed.
According to this configuration, the position detection error of the biaxial magnetic sensor circuit can be further reduced.

(8) In the encoder, the first magnet body is configured by arranging a plurality of divided magnet bodies in an annular shape, and each divided magnet body includes a small magnet having a rectangular parallelepiped shape, and a periphery of the small magnet It is good also as what has a covering member which makes the whole shape of the said division | segmentation magnet body an isosceles trapezoid pillar shape by coat | covering at least one part.
According to this configuration, it is possible to easily create an encoder with high positional accuracy using an extremely multipolar magnet body.

(9) According to another aspect of the invention, an electromechanical device is provided. The electromechanical device includes a drive or regenerative magnet body, a drive or regenerative electromagnetic coil, the encoder, and a control unit that controls the operation of the electromechanical device. A magnet body is shared as the first magnet body of the encoder.
According to this electromechanical device, since the magnet body for driving or regenerating the electromechanical device and the magnet body of the encoder are shared, the overall structure of the electromechanical device and the encoder is simplified and the electromechanical device is highly accurate. It is possible to detect the position of the magnet body.

(10) The electromechanical device is a DC motor having a two-phase electromagnetic coil, and the control unit is configured to output the sine wave signal and the cosine wave output from the first two-axis magnetic sensor circuit of the encoder. A drive signal generation unit that generates a drive signal for the two-phase electromagnetic coil from the signal may be provided.
According to this configuration, since the two-phase drive signal is generated from the sine wave signal and the cosine wave signal output from one two-axis magnetic sensor circuit, the phase shift of the drive signal due to the position shift of the magnetic sensor or the like. Can be prevented.

(11) According to still another aspect of the present invention, an electromechanical device is provided. The electromechanical device is an electromechanical device operable as a two-phase DC motor, and includes a magnet body, a two-phase electromagnetic coil, the encoder, and a control unit that controls the operation of the electromechanical device; And the control unit generates a drive signal for the two-phase electromagnetic coil from the sine wave signal and the cosine wave signal output from the first two-axis magnetic sensor circuit of the encoder Part.
According to this electromechanical device, since the two-phase drive signal is generated from the sine wave signal and the cosine wave signal output from one two-axis magnetic sensor circuit, the drive signal caused by the positional deviation of the magnetic sensor is generated. It is possible to prevent a phase shift.

  The present invention can be realized in various forms other than the apparatus. For example, an encoder, a rotary encoder, a position detection method, a rotational position detection method, an electromechanical device equipped with an encoder, a robot, a railway vehicle, a computer program for realizing the function of the method or device, and the computer program recorded It can be realized in the form of a non-transitory storage medium.

Explanatory drawing which shows the structure and operation | movement of the rotary encoder of 1st Embodiment. Explanatory drawing which shows the magnetic sensing direction of several Hall element in a biaxial magnetic sensor circuit. Explanatory drawing which shows the circuit structure and operation | movement of a biaxial magnetic sensor circuit. Explanatory drawing which shows the structure and operation | movement of the rotary encoder of 2nd Embodiment. Explanatory drawing which shows the modification of the rotary encoder of 2nd Embodiment. Explanatory drawing which shows the other structural example of a magnet body. Explanatory drawing which shows the magnetic angle output output from two 2-axis magnetic sensor circuits. Explanatory drawing which shows the position signal production | generation part which determines the absolute position (absolute angle) of a rotary body using the output of two biaxial magnetic sensor circuits. Explanatory drawing which shows the correction | amendment object range of the short period interval value Px. The flowchart which shows the algorithm of correction | amendment of the short period interval value Px. Explanatory drawing which shows the structure and operation | movement of the rotary encoder of 3rd Embodiment. Explanatory drawing which shows the magnetic angle output output from two 2-axis magnetic sensor circuits. Explanatory drawing which shows the structure of the rotary encoder as 4th Embodiment. Explanatory drawing which shows the structure of the linear encoder as 5th Embodiment. Explanatory drawing which shows the electromechanical apparatus provided with the encoder of embodiment. The block diagram which shows the electric constitution of an electric machine apparatus. The block diagram which shows the internal structure of a main control circuit. Explanatory drawing which shows the internal structure and operation | movement of a rotation speed calculation part. Explanatory drawing which shows the robot using the electromechanical device of embodiment. Explanatory drawing which shows the rail vehicle using the electric machine apparatus of embodiment.

A. First embodiment (rotary encoder using one magnet body)
FIG. 1 is an explanatory diagram showing the configuration and operation of a rotary encoder 100A as the first embodiment. The rotary encoder 100 </ b> A includes an annular magnet body 110 and a biaxial magnetic sensor circuit 130 provided to face the surface of the magnet body 110. The biaxial magnetic sensor circuit 130 is fixed on the substrate 140 (FIG. 1B). The substrate 140 constitutes a stationary body (also referred to as “stator” or “first member”) that does not rotate, and the magnet body 110 constitutes a rotating body (also referred to as “rotor” or “second member”). The rotating body rotates around a virtual rotation axis C. Therefore, the moving direction of the rotating body is the circumferential direction of the magnet body 110.

  The magnet body 110 is composed of eight small magnets 110s, and the adjacent small magnets 110s are magnetized in opposite directions. That is, the entire magnet body 110 is an 8-pole magnet body. The magnetization direction of each small magnet 110 s is a direction that intersects the rotation direction (movement direction) of the magnet body 110. The magnetizing direction is parallel to a direction perpendicular to the facing direction of the magnet body 110 and the substrate 140 (that is, the direction parallel to the rotation axis C), and the center of each small magnet 110s and the magnet body 110 are parallel to each other. It is parallel to the direction connecting the rotation axis C. As a magnetization method of the small magnet 110s, parallel magnetization (the magnetization direction is the whole of the small magnet) is more preferable than radial magnetization (magnetization method in which the magnetization direction is a radial direction around the rotation axis C). It is preferable that the magnetizing method be parallel to each other. This is because the parallel magnetization shows a smoother sinusoidal change in the magnetic field detected by the biaxial magnetic sensor circuit 130, and the resolution of the rotation angle is improved. In FIGS. 1A and 1B, only the magnetization direction of one small magnet 110s is indicated by an arrow for convenience of illustration.

  An annular yoke member 120 is disposed on the inner periphery of the magnet body 110. The yoke member 120 also covers the back surface (surface opposite to the substrate 140) of the magnet body 110. The yoke member 120 is formed of a soft magnetic material, and is for reducing leakage of unnecessary magnetic flux by forming a magnetic circuit (magnetic path) on the inner peripheral side of the magnet body 110. The yoke member 120 is preferably provided on at least one of the inner periphery and the outer periphery of the magnet body 110. However, the yoke member 120 may be omitted.

  FIG. 1C is a graph showing various detection signals sin θm, cos θm, D1 obtained by the biaxial magnetic sensor circuit 130. The horizontal axis of this graph is the rotation angle θr of the magnet body 110 (that is, the rotating body). The rotation angle θr is an angle measured clockwise from the 12 o'clock direction to the reference position PP on the magnet body 110 as shown in FIG. This rotation angle θr is also called “mechanical angle”. Further, the magnetic field along the circumferential direction of the magnet body 110 shows a sinusoidal change with one pair of adjacent small magnets 110s as one cycle. The position of each period of the magnetic field is represented by a magnetic angle θm. Signals sinθm and cosθm shown at the top of FIG. 1C are sinusoidal signals corresponding to the magnetic angle θm. A signal D1 shown at the bottom of FIG. 1C is a signal that linearly changes from 0 to the maximum value in each cycle of the magnetic angle θm, and is output from the biaxial magnetic sensor circuit 130 to an external circuit. Magnetic angle output D1. The magnetic angle output D1 can be generated, for example, by decoding two sinusoidal signals sinθm and cosθm.

  As shown in FIG. 1B, the biaxial magnetic sensor circuit 130 is disposed at a position facing the surface of the magnet body 110 via a certain gap. In other words, the biaxial magnetic sensor circuit 130 is disposed via a certain gap from the surface of the magnet body 110 parallel to both the moving direction of the magnet body 110 and the magnetization direction of the magnet body 110. The biaxial magnetic sensor circuit 130 has a position (that is, a magnet) where a magnetic flux center portion (position indicated by a broken line in FIG. 1B) where the magnetic flux density is zero is removed from positions along the radial direction of the magnet body 110. (Position facing the magnetic flux center of the body 110). In particular, the installation position of the biaxial magnetic sensor circuit 130 is arranged at the approximate center of the width W (the width W obtained by combining the magnet body 110 and the yoke member 120) measured along the radial direction of the magnet body 110. Is preferred. In other words, the two-axis magnetic sensor circuit 130 combines the magnet body 110 and the yoke member 120 rather than the center (magnetic flux center portion) of the width of the magnet body 110 alone measured along the radial direction of the magnet body 110. It is preferable to arrange at a position close to the center of the width W. The reason for this is that, according to the experiment results of the inventors, the latter arrangement has a smaller error in the magnetic angle output D1 by the biaxial magnetic sensor circuit 130 and is more preferable from the viewpoint of reducing the error.

  FIG. 2 is an explanatory diagram showing an example of the arrangement of a plurality of Hall elements included in the biaxial magnetic sensor circuit 130 and their magnetic sensitive directions. Here, as directions parallel to the surface of the biaxial magnetic sensor circuit 130, an X-axis direction and a Y-axis direction perpendicular to each other are drawn. The Z-axis direction is orthogonal to the X-axis direction and the Y-axis direction, and is a direction parallel to the rotation axis C in FIGS. 1 (A) and 1 (B). In addition, the direction from the south pole to the north pole is indicated by an arrow as the magnetic sensing direction of the hall element (direction of detecting the lines of magnetic force). A white circle including a black circle inside indicates that the direction from the back side to the front side of the paper surface is the magnetosensitive direction. A white circle including “X” in the inside indicates that the direction from the front side to the back side of the paper surface is the magnetosensitive direction.

  The two-axis magnetic sensor circuit 130 shown in FIG. 2A includes two X-axis Hall elements X1 and X2 whose X-axis direction is a magnetic sensitive direction, and two Y-axis Hall elements Y1 whose Y-axis direction is a magnetic sensitive direction. , Y2. The number of X-axis Hall elements is preferably a plurality, and is not limited to two and may be three or more. The same applies to the Y-axis Hall element. As will be described later, a first magnetic angle signal sin θm is generated from the plurality of X-axis Hall elements X1 and X2, and a second magnetic angle signal cos θm is generated from the plurality of Y-axis Hall elements Y1 and Y2. This point will be further described later.

  The biaxial magnetic sensor circuit 130 shown in FIG. 2B includes a first set of hall elements YX1 and YX2 and a second set of hall elements XY1 and XY2. In these two sets of Hall elements, a direction that is inclined by 45 degrees with respect to the X-axis direction and the Y-axis direction is defined as a magnetosensitive direction. The two-axis magnetic sensor circuit 130 shown in FIG. 2C has two Y-axis Hall elements Y1 and Y2 and two X-axis Hall elements X1 and X2. The circuit of FIG. 2C is different from the circuit of FIG. 2A in that the magnetosensitive directions of the two Y-axis Hall elements Y1 and Y2 and the two X-axis Hall elements X1 and X2 face each other. Yes. 2D includes four Y-axis Hall elements Y1a, Y1b, Y2a, and Y2b and four Z-axis Hall elements Z1a, Z1b, Z2a, and Z2b. When the two-axis magnetic sensor circuit 130 of FIG. 2D is used, the outputs of the upper two Y-axis Hall elements Y1a and Y1b are added, and the lower two Y-axis Hall elements Y2a and Y2b are added. It is possible to obtain an output equivalent to the outputs of the two Y-axis Hall elements Y1 and Y2 in FIG. The same applies to the Z-axis Hall elements Z1a, Z1b, Z2a, Z2b. Regardless of which of the two-axis magnetic sensor circuits 130 shown in FIGS. 2B to 2D, the magnetic angle signals sinθm and cosθm can be generated by combining the outputs of the plurality of Hall elements. is there. As can be understood from these examples, the biaxial magnetic sensor circuit 130 is a circuit capable of detecting a magnetic field along two orthogonal directions. Further, in the two-axis magnetic sensor circuit 130, a plurality of X-axis sensor elements are arranged at locations separated from each other along the X-axis by a first set of X-axis Hall elements and a second set of X-axis Hall elements. Similarly, the plurality of Y-axis sensor elements include a first set of Y-axis Hall elements and a second set of Y-axis Hall elements arranged at locations separated from each other along the Y-axis. It is possible to configure.

  FIG. 3 is an explanatory diagram showing the circuit configuration and operation of the biaxial magnetic sensor circuit 130. Here, the configuration of the Hall element shown in FIG. 2A is used. The biaxial magnetic sensor circuit 130 includes amplification circuits 131 and 132, AD conversion circuits 133 and 134, and a signal processing circuit 135 in addition to the X axis Hall elements X1 and X2 and the Y axis Hall elements Y1 and Y2. ing. The outputs of the two X-axis Hall elements X1 and X2 are input to the first amplifier circuit 131, and the outputs of the two Y-axis Hall elements Y1 and Y2 are input to the second amplifier circuit 132. As shown in FIG. 3B, the outputs of the two X-axis Hall elements X1 and X2 are each a first sinusoidal signal. The outputs of the two Y-axis Hall elements Y1 and Y2 are second sine wave (cosine wave) signals that are 90 degrees out of phase with the first sine wave. The first amplifier circuit 131 is configured as a differential amplifier that takes a difference (X1-X2) between outputs of the two X-axis Hall elements X1 and X2. This is because the circuits and wirings of the Hall elements X1 and X2 are configured so that the signs of the outputs of the two X-axis Hall elements X1 and X2 input to the first amplifier circuit 131 are reversed. Because. In the example of FIG. 3B, the outputs of the two X-axis Hall elements X1 and X2 are drawn as signals having opposite signs and equal absolute values. However, depending on the installation position of the two-axis magnetic sensor circuit 130 and the magnetic pole position due to the magnetic flux distortion of the magnet, the absolute values of the outputs of these two X-axis Hall elements X1 and X2 may be different from each other. However, also in this case, the difference between the outputs of the two X-axis Hall elements X1 and X2 (X1-X2) is obtained by the first amplifier circuit 131, so that the installation position of the two-axis magnetic sensor circuit 130 and the magnetic flux of the magnet are obtained. Regardless of the displacement of the magnetic pole position due to distortion, it is possible to obtain a correct sine wave output corresponding to the magnetic angle θm. The same applies to the Y-axis Hall elements Y1 and Y2 and the second amplifier circuit 132. Thus, a sine wave signal (X1-X2) is generated by taking the difference between the output signals of the plurality of X-axis Hall elements, and a sine wave signal ( A cosine wave signal (Y1-Y2) that is 90 degrees out of phase with X1-X2) can be generated. Further, based on the sine wave signal (X1-X2) and the cosine wave signal (Y1-Y2), the magnetic angle output D1 indicating the position (rotation position) of the rotating body can be generated.

  Note that the outputs of the two X-axis Hall elements X1 and X2 input to the first amplifier circuit 131 may be signals having the same sign. In this case, the first amplifier circuit 131 is configured as a summing amplifier. However, if the first amplifier circuit 131 is configured as a differential amplifier, even when the two output signals X1 and X2 include common noise (for example, high-frequency noise accompanying PWM control of the electromagnetic coil) It is preferable in that noise can be reduced by taking the difference (X−X2). These points are also the same for the second amplifier circuit 132.

  The outputs (X1-X2) and (Y1-Y2) of the amplifier circuits 131 and 132 are converted into digital signals by the AD conversion circuits 133 and 134, respectively, and become magnetic angle signals sin θm and cos θm. The signal processing circuit 135 generates a magnetic angle output D1 shown in FIG. 1C by performing a decoding operation based on these magnetic angle signals sin θm and cos θm. The signal processing circuit 135 further generates the two-phase pulse signals Pa and Pb and the periodic signal Z shown in FIG. 3C by using the magnetic angle output D1.

The two-phase pulse signals Pa and Pb and the periodic signal Z are generated as follows, for example. The magnetic angle output D1 is a signal representing the magnetic angle θm by a plurality of bits. For example, when the magnetic angle output D1 is configured as a 12-bit signal, the value of the magnetic angle output D1 is 0 to 4095 (= 2 ¹² −1) while the magnetic angle θm changes from 0 to 2π. It changes linearly. The two-phase pulse signals Pa and Pb are signals whose phases are shifted from each other by 90 degrees, and are signals corresponding to an A-phase output and a B-phase output of an optical incremental encoder. The periodic signal Z is a signal that generates one pulse every time the magnetic angle θm changes by 2π, and is a signal that corresponds to the Z-phase signal of the optical incremental encoder. For example, the A-phase pulse signal Pa is generated as a signal indicating a change in the second least significant bit of the magnetic angle output D1. The B-phase pulse signal Pb is generated as a signal obtained by taking an exclusive OR (XOR) of the least significant 2 bits of the angle signal D1. The periodic signal Z is generated as a signal obtained by taking a negative logical sum (NOR) of all bits of the angle signal D1. When the angle signal D1 is a 12-bit signal, 1024 pulses of the two-phase pulse signals Pa and Pb are generated while the magnetic angle θm changes by 2π.

  The signal processing circuit 135 can output the angle signal D1, the sine wave signal sin θm, the cosine wave signal cos θm, the two-phase pulse signals Pa and Pb, and the periodic signal Z to the outside. A device using the rotary encoder 100A can perform position control and speed control using some of these signals.

  As described above, the rotary encoder 100A of the first embodiment is magnetized in a direction intersecting the moving direction (circumferential direction) of the magnet body 110, and the biaxial magnetic sensor circuit 130 is moved by the magnet body 110. Are arranged via a certain gap from the surface of the magnet body parallel to both the direction of the magnet body 110 and the magnetizing direction of the magnet body 110, so that the output of the plurality of Hall elements of the biaxial magnetic sensor circuit 130 A small sinusoidal output can be obtained. Therefore, it is possible to obtain a magnetic angle output with high resolution from the sine wave output with little magnetic distortion. The biaxial magnetic sensor circuit 130 has a plurality of X-axis Hall elements X1 and X2 and a plurality of Y-axis Hall elements Y1 and Y2, and a magnetic angle output D1 according to the output signals of those Hall elements. Therefore, even when the installation position of the biaxial magnetic sensor circuit 130 is slightly deviated with respect to the magnet body 110, it is possible to obtain an accurate magnetic angle output D1.

  In addition, although the pole number M of the magnet body 110 is 8 in the first embodiment, the pole number M is preferably an even number of 4 or more. This is because when the number of poles M is an odd number, the range of 2π of the mechanical angle θr does not become an integral multiple of 2π of the magnetic angle θm, so that the angle detection is inconvenient. Also, if the number of poles M is 2, the resolution of the magnetic angle output D1 may not be sufficiently increased.

B. Second Embodiment (Rotary Encoder Using Two Magnets, Part 1)
FIG. 4 is an explanatory diagram showing the configuration and operation of the rotary encoder 100B as the second embodiment. The rotary encoder 100B of the second embodiment is different from the rotary encoder 100A of the first embodiment shown in FIG. 1 in that a second magnet body 210, a second yoke member 220, and a second two-axis magnetic sensor circuit 230 are used. Are added. The configuration and operation of the second biaxial magnetic sensor circuit 230 are the same as the configuration and operation of the biaxial magnetic sensor circuit 130 described in the first embodiment.

  The second magnet body 210 is disposed inside the first magnet body 110 and is a two-pole annular magnet concentric with the first magnet body 110. As a method of magnetizing the second magnet body 210, parallel magnetization is preferable to radial magnetization. This reason is the same as the reason explained in the first embodiment (the reason why parallel magnetization is preferable as the magnetization method of the individual small magnets 110s of the first magnet body 110). The direction of parallel magnetization of the second magnet body 210 is preferably parallel to the direction passing through the rotation axis C of the rotating body (that is, the radial direction of the magnet body 210).

  An annular second yoke member 220 is disposed on the inner periphery of the second magnet body 210. However, the yoke member 120 may be omitted. Note that it is preferable to provide some kind of magnetic yoke member between the first magnet body 110 and the second magnet body 210. The reason for this is to prevent the two magnet bodies 110 and 210 from causing magnetic field interference in the two-axis magnetic sensor circuits 130 and 230, respectively.

  The second biaxial magnetic sensor 230 is disposed at a position facing the surface of the second magnet body 210 via a certain gap. In other words, the second biaxial magnetic sensor circuit 230 has a second parallel to both the moving direction (that is, the circumferential direction) of the second magnet body 210 and the magnetization direction of the second magnet body 210. It arrange | positions through the fixed gap from the surface of the magnet body 210. FIG. Further, the installation position of the second two-axis magnetic sensor circuit 230 is closer to the second magnet body 210 than the center of the width of the second magnet body 210 measured along the radial direction of the second magnet body 210. The second yoke member 220 is preferably disposed at a position close to the center of the combined width. This point is the same as the preferable installation position of the first two-axis magnetic sensor circuit 130 described in the first embodiment.

  FIG. 4C shows an example of a segment of a short cycle section used in the rotary encoder 100B of the second embodiment. Here, four small sections divided every 90 degrees with reference to the direction in which the reference position PP of the rotary body (the first magnet body 110 and the second magnet body 210) of the rotary encoder 100B is in the 12 o'clock direction. Periodic intervals are shown. One small cycle section corresponds to a section where the magnetic angle θm of the first magnet body 110 changes by 360 degrees (2π) (that is, a section of two small magnets). The short cycle interval value Px is a value for distinguishing these four short cycle intervals, and takes four values from 0 to 3. As will be described later, the short period interval value Px is generated from the magnetic angle output of the second biaxial magnetic sensor circuit 230.

  FIG. 7 shows an example of the first magnetic angle output D1 output from the first two-axis magnetic sensor circuit 130 and the second magnetic angle output D2 output from the second two-axis magnetic sensor circuit 230. It is explanatory drawing. In FIG. 7, the horizontal axis represents the mechanical angle θr, and the vertical axis represents the magnetic angle outputs D1 and D2 of the two biaxial magnetic sensor circuits 130 and 230. In the present embodiment, the magnetic angle outputs D1 and D2 of the biaxial magnetic sensor circuits 130 and 230 are each composed of 12 bits. However, in general, the first magnetic angle output D1 of the first two-axis magnetic sensor circuit 130 is a digital signal of N1 bits (N1 is an integer of 2 or more), and the second magnetic field of the second two-axis magnetic sensor circuit 230 is set. The square output D2 can be a digital signal of N2 bits (N2 is an integer of 2 or more). Here, the bit numbers N1 and N2 may be the same value or different values.

  The first magnetic angle output D1 shown in FIG. 7B indicates a change in the magnetic angle accompanying the rotation of the first magnet body 110 (FIG. 4), and is 0 while the mechanical angle θr changes 360 degrees. A value from 1 to 4095 indicates a sawtooth-like change that occurs repeatedly 4 times. That is, the first magnetic angle output D1 shows a linear change that increases from 0 to 4095 during each small period. On the other hand, the second magnetic angle output D2 shown in FIG. 7A shows the change of the magnetic angle accompanying the rotation of the second magnet body 210, from 0 to 4095 while the mechanical angle θr changes 360 degrees. Indicates a linear change that occurs only once. The most significant 2 bits of the second magnetic angle output D2 can be used as the short period interval value Px described with reference to FIG.

  The short period interval value Px is used to determine the absolute position of the mechanical angle θr with high accuracy. The mechanical angle θr can be detected with an accuracy of 12 bits only from the second magnetic angle output D2. However, if both the short period interval value Px and the first magnetic angle output D1 are used, the absolute position of the mechanical angle θr can be determined with higher accuracy (high resolution). Specifically, in the example of FIG. 7, since the short cycle interval value Px is 2 bits and the first magnetic angle output D1 is 12 bits, both of them are used to obtain a mechanical angle with a precision (resolution) of 14 bits. θr can be detected.

  FIG. 8 is an explanatory diagram showing a position signal generator 300 that determines the absolute position (absolute angle) of the rotating body using the outputs of the two two-axis magnetic sensor circuits 130 and 230. The position signal generation unit 300 combines the magnetic angle outputs D1 and D2 of the two two-axis magnetic sensor circuits 130 and 230 to generate an absolute position output Dabs. FIG. 8B shows the processing contents of the position signal generation unit 300. In this example, the first magnetic angle output D1 is a 12-bit signal from the least significant bit M0 to the most significant bit M11, and the second magnetic angle output D2 is also 12 from the least significant bit S0 to the most significant bit S11. It is a bit signal. The most significant 2 bits S11 and S10 of the second magnetic angle output D2 are used as the short period interval value Px. In the absolute position output Dabs, the most significant 2 bits are the short period interval value Px, and the lower 12 bits are the first magnetic angle output D1. This absolute position output Dabs is a signal representing the value of the mechanical angle θr with an accuracy of 14 bits.

  In the present embodiment, each of the biaxial magnetic sensor circuits 130 and 230 uses a plurality of Hall elements (see the example in FIG. 2). Therefore, when the power of the biaxial magnetic sensor circuits 130 and 230 is turned on, the magnetic angle outputs D1 and D2 shown in FIG. 7 are obtained according to the absolute position (mechanical angle θr) of the rotating body at that time. The absolute position (mechanical angle θr) of the rotating body can be determined according to the magnetic angle outputs D1 and D2. Therefore, when the power of the biaxial magnetic sensor circuits 130 and 230 is turned off, it is not necessary to store the absolute position (the value of the mechanical angle θr) of the rotating body at that time, and two magnetic angle outputs D1 obtained when the power is turned on. , D2 alone, there is an advantage that the absolute position of the rotating body when the power is off can be known.

  By the way, in the example of FIG. 7, the boundary of the short period section of the first magnetic angle output D1 and the change position of the value of the short period section value Px obtained from the second magnetic angle output D2 coincide. However, in an actual circuit, there is a possibility that a problem in which the two differ due to some error. In order to prevent such inconvenience, the position signal generation unit 300 detects the timing at which the first magnetic angle output D1 returns from the maximum value D1max to the minimum value 0 in accordance with the increase in the mechanical angle θr, and the small cycle interval value Px ( That is, it is preferable to correct the short period interval value Px so that the timing at which the most significant 2 bits of the second magnetic angle output D2) are incremented.

  FIG. 9 is an explanatory diagram illustrating a correction target range of the short cycle interval value Px performed by the position signal generation unit 300. In the lower part of the figure, a sawtooth change of the first magnetic angle output D1 is shown, and in the upper part, the error width (vertical width) of the second magnetic angle output D2 is shown by hatching. . The first magnetic angle output D1 changes in the range from the minimum value 0 to the maximum value D1max, and returns to the minimum value 0 after reaching the maximum value D1max. If the timing at which the first magnetic angle output D1 returns from the maximum value D1max to the minimum value 0 coincides with the timing at which the most significant 2 bits of the second magnetic angle output D2 are incremented, the result is shown in FIG. As described above, the most significant 2 bits of the second magnetic angle output D2 can be used as they are as the short period interval value Px. On the other hand, when the timings of both are shifted, the short period interval value Px is corrected. The short period interval value Px needs to be corrected in the range R1 immediately after the timing when the first magnetic angle output D1 returns from the maximum value D1max to the minimum value 0 and the range R3 immediately before that timing. In the middle range R2 between these two ranges R1 and R3, the value of the most significant 2 bits of the second magnetic angle output D2 shows a correct value as the short period interval value Px, so there is no need for correction.

FIG. 10 is a flowchart illustrating an example of an algorithm for correcting the short cycle interval value Px. This correction is performed by the position signal generator 300 (FIG. 8). In step S100, the bit number N1 of the first magnetic angle output D1, the bit number N2 of the second magnetic angle output D2, and the bit number Nx of the short period interval value Px are set. Parameters Nss (= N2−Nx) and D1max (= 2 ^N1 −1) are also set. In this embodiment, N1 = N2 = 12, Nx = 2, Nss = 10, and D1max = 4095.

  In step S110, the position signal generator 300 receives the magnetic angle outputs D1 and D2 from the two two-axis magnetic sensor circuits 130 and 230 (FIG. 4). In step S120, it is determined which of the three ranges R1, R2, and R3 shown in FIG. 9 is in the first magnetic angle output D1. In the example of FIG. 10, the first range R1 is 0 ≦ D1 ≦ (D1max / 4), the second range R2 is (D1max / 4) <D1 <(D1max * 3/4), and the third range is set. R3 is set to (D1max * 3/4) ≦ D1 ≦ D1max. In the first range R1 and the third range R3, the second magnetic angle output D2 is corrected in order to correct the short period interval value Px.

Steps S130 to S150, which are correction execution steps, are performed based on the following idea.
(1) When the first magnetic angle output D1 is in the first range R1, the short period interval value Px represented by the upper 2 bits of the second magnetic angle output D2 is erroneously reduced by one. There is a possibility. Therefore, in order to eliminate this possibility, a value half of the maximum value (= 2 ^Nss ) represented by the lower Nss bits of the second magnetic angle output D2 is added to the second magnetic angle output D2, and its upper Nx bits are used as the short cycle interval value Px (steps S130 and S150).
(2) When the first magnetic angle output D1 is in the second range R2, the most significant 2 bits of the second magnetic angle output D2 are used as they are as the short period interval value Px (step S150).
(3) When the first magnetic angle output D1 is in the third range R3, the short period interval value Px represented by the upper 2 bits of the second magnetic angle output D2 is erroneously increased by one. There is a possibility. Therefore, in order to eliminate this possibility, a value half of the maximum value (= 2 ^Nss ) represented by the lower Nss bits of the second magnetic angle output D2 is subtracted from the second magnetic angle output D2, and its upper Nx The bit is used as the short cycle interval value Px (steps S140 and S150).

By performing such correction, it is possible to determine the short cycle interval value Px so that the boundary of the short cycle interval of the first magnetic angle output D1 always coincides with the change point of the short cycle interval value Px. It is. According to the inventor's calculation, if the magnetic angle error of the second magnetic angle output D2 is ± 2 ^N1−Nx−2 or less, it is possible to obtain a correct small period interval value Px by the above correction. For example, if N1 = 12, Nx = 2, the tolerance is ± 2 ⁸ = ± 256. Since this allowable error is quite large, it can be understood that the tolerance to the error is very large and that the correction is extremely effective in practice. However, if the error of the magnetic angle outputs D1 and D2 is negligible, the correction of the short period interval value Px is not necessary.

  Note that the minimum widths of the ranges R1 and R3 that require correction vary depending on the magnitude of the error in the magnetic angle outputs D1 and D2. Therefore, these three ranges R1 to R3 can be set to predetermined ranges different from those described above. However, each of the three ranges R1 to R3 is preferably set to a range in which the width is not zero. Moreover, it is preferable that the ranges R1 and R3 on both sides of the boundary of the short cycle section have the same width.

  As described above, in the second embodiment, the position signal generation unit 300 includes the first magnetic angle output D1 of the first biaxial magnetic sensor circuit 130 and the second magnetic angle output of the second biaxial magnetic sensor circuit 230. In accordance with D2, a position signal (absolute position output Dabs) indicating the absolute position (mechanical angle θr) of the rotating body is generated. If this position signal Dabs is used, the position can be determined with higher accuracy (higher resolution) than that of one two-axis magnetic sensor circuit 130 (or 230). Further, as described above, in this embodiment, since the biaxial magnetic sensor circuits 130 and 230 use a plurality of Hall elements, two magnetic angle outputs obtained when the biaxial magnetic sensor circuits 130 and 230 are powered on. From only D1 and D2, the absolute position of the rotating body when the power is turned off can be directly read.

  In addition, when the number of poles of the first magnet body 110 is M1, and the number of poles of the second magnet body 210 is M2, it is preferable that M1 and M2 are each even numbers, and in particular, M1 is 4 or more. It is preferable that the number is even and M2 is an even number of 2 or more. In this way, position detection can be performed with higher accuracy than when one magnet body is used.

The number of poles M1 of the first magnet body 110 and the number of poles M2 of the second magnet body 210 are preferably integers in which M1 / 2 and M2 / 2 are relatively prime. Here, two integers being “relative to each other” means that they do not have a common divisor other than 1. If M1 / 2 and M2 / 2 are integers that are prime to each other, the boundary of the section of the magnetic angle 2π of the first magnet body 110 (the short period section of FIG. 7) and the magnetic angle of the second magnet body 210 Since the position where the boundary of the 2π section coincides is only the position of the mechanical angle θr = 0, the absolute value of the mechanical angle θr can be determined from the two magnetic angle outputs D1 and D2. In the second embodiment, M1 = 8 and M2 = 2. That is, the number of poles M1 of the first magnet body 110 is equal to 2 ³ .

By the way, in order to use the most significant bits of the second magnetic angle output D2 as the short period interval value Px, the number of poles M1 of the first magnet body 110 is set to 2 ^{Q + 1} (Q is an integer of 1 or more). It is preferable to set the number of poles M2 of the second magnet body 210 to 2. At this time, the position signal generation unit 300 arranges the most significant Q bits of the second magnetic angle output D2 at the most significant position, and arranges all the bits (N1 bits) of the first magnetic angle output D1 below ( It is preferable to generate a signal of N1 + Q) bits as the absolute position output Dabs. For example, in the second embodiment, since N1 = 12, Q = 2, the absolute position output Dabs is a 14-bit signal.

  FIG. 5 is an explanatory diagram illustrating a modification of the rotary encoder according to the second embodiment. 4 differs from the rotary encoder of FIG. 4 in that the second small magnet 210 has a solid disk shape, the second yoke member 220 for the second magnet body 210 is omitted, and the second The two-axis magnetic sensor circuit 230 is arranged at a position facing the center of the second magnet body 210. The rotary encoder of FIG. 5 has almost the same performance as the rotary encoder of FIG.

  FIGS. 6A to 6C are explanatory diagrams illustrating other configuration examples of the first magnet body 110. FIG. 6A is a plan view and a side view showing a small magnet 110 s for the first magnet body 110. The small magnet 110s has an equilateral trapezoidal column shape. That is, it has an isosceles trapezoidal shape in a plan view (left side in FIG. 6A) and a rectangular shape in a side view (right side in FIG. 6A). The equilateral trapezoidal shape in plan view has a height H and base widths WD1 and WD2. Further, the rectangular shape in side view has a depth DP and a height H. This depth DP corresponds to the thickness (the dimension in the direction perpendicular to the paper surface) of the first magnet body 110 shown in FIGS. The widths WD1 and WD2 of the bottom of the trapezoid are determined according to the diameter dimension of the first magnet body 110 and the number of poles M1 of the first magnet body 110. For example, when the diameter of the first magnet body 110 is 30 mm, the number of poles is 64, and the height H of the small magnet 110 s is 5 mm, WD1 = 1.47 mm and WD2 = 0.98 mm. The size of the magnet 110s is extremely small. When trying to manufacture such a small trapezoidal small magnet 110s, it is difficult to taper the side surface TP.

  Therefore, in the example shown in FIGS. 6B and 6C, a small magnet 110s having a rectangular parallelepiped shape instead of a trapezoidal column shape is used, and a small shape having an outer shape substantially equivalent to FIG. 6A. A magnetic body 100d (hereinafter referred to as "divided magnet body 110p") is configured. That is, the divided magnet body 110p is composed of a rectangular parallelepiped small magnet 110s and a covering member 112, and has an isosceles trapezoidal column shape as a whole. The covering member 112 is a member provided to cover at least a part of the periphery of the rectangular parallelepiped small magnet 110s and to make the entire shape of the divided magnet body 110p an isosceles trapezoid. As the material of the covering member 112, it is possible to use a non-magnetic material such as an aluminum material or a resin in consideration of ease of processing and durability. FIG. 6C shows a state in which the multipolar first magnet body 110 is configured by arranging a large number of divided magnet bodies 110p. For example, it is possible to configure the first small magnet body 110 having 64 poles or 32 poles by arranging 64 divided magnet bodies 110p in an annular shape in contact with each other. Moreover, you may provide the supporting member 150 for supporting the some divided magnet body 110p in the inner peripheral side of the small magnet body 110 comprised by the divided magnet body 110p. The support member 150 is preferably formed of a material having sufficient rigidity, for example, a carbon tool steel such as SK5. However, instead of the support member 150, the yoke member 120 shown in FIGS. 1, 4, and 5 may be used to support the plurality of divided magnet bodies 110p.

  By using such a divided magnet body 110p, it is possible to easily manufacture a small magnet body 110 having an extremely large number of poles such as 32 poles and 64 poles. In addition, it is possible to easily configure an encoder with high positional accuracy using such a small magnet body 110. In the example of FIG. 6B, the covering member 112 does not cover one of the short sides of the rectangular parallelepiped small magnet 110s (the portion corresponding to the width WD2 of the trapezoidal base). The entire small magnet 110s may be covered.

C. Third embodiment (rotary encoder using two magnet bodies, part 2)
FIG. 11 is an explanatory diagram showing the configuration and operation of a rotary encoder 100C as the third embodiment. The difference between the rotary encoder 100C of the third embodiment and the rotary encoder 100B (FIG. 4) of the second embodiment is the number of poles of the two magnet bodies 110 and 210. That is, the pole number M1 of the first magnet body 110 of the rotary encoder 100C of the third embodiment is 10, and the pole number M2 of the second magnet body 210 is 4. Other configurations of the third embodiment are the same as those of the second embodiment.

  FIG. 12 is an explanatory diagram illustrating an example of the magnetic angle outputs D1 and D2 in the third embodiment, and corresponds to FIG. 7 in the second embodiment. Since the number of poles of the first magnet body 110 is 10, the first magnetic angle output D1 changes in five small cycles while the mechanical angle θr changes from 0 to 360 degrees. On the other hand, since the number of poles of the second magnet body 210 is 4, the second magnetic angle output D2 changes in two small cycles while the mechanical angle θr changes from 0 to 360 degrees. Therefore, the position signal generator 300 (FIG. 8) can determine the mechanical angle θr with high accuracy based on these two magnetic angle outputs D1 and D2. However, in the third embodiment, the absolute position output Dabs cannot be obtained by directly using the upper bits of the second magnetic angle output D2, and the absolute position output can be obtained by decoding the two magnetic angle outputs D1 and D2. Create Dabs. In order to perform such decoding, for example, it is possible to use a look-up table having two magnetic angle outputs D1 and D2 as inputs and an absolute position output Dabs as an output. Alternatively, the decoding may be performed by an arithmetic operation. In the third embodiment, the number of poles M1 (= 10) of the first magnet body 110 and the number of poles M2 (= 4) of the second magnet body 210 are M1 / 2 (= 5) and M2 / 2 (= 2) is an integer that is relatively prime.

  In the third embodiment, as in the second embodiment, the position can be detected with high accuracy using the two magnet bodies 110 and 210 and the two two-axis magnetic sensor circuits 130 and 230. However, the second embodiment described above is preferable to the third embodiment in that the decoding described in the third embodiment can be omitted.

D. Fourth Embodiment (Rotary Encoder Using Two Magnets, Part 3)
FIG. 13 is an explanatory diagram showing a configuration of a rotary encoder 100D as the fourth embodiment. In this rotary encoder 100D, an annular first magnet body 110d and second magnet body 210d having the same diameter are arranged in parallel around a hollow cylindrical yoke member 120 along a direction parallel to the rotation axis C. It has the structure which was made. Biaxial magnetic sensor circuits 130 and 230 are provided on the substrate 140 at positions with a predetermined gap with respect to the outer peripheral surfaces of the two magnet bodies 110d and 210d.

  The first magnet body 110d is composed of eight small magnets, and its pole number M1 is eight. The second magnet body 210d is composed of two small magnets, and the number of poles M2 thereof is two. However, these pole numbers M1 and M2 can be set to various integers described in the second embodiment and the third embodiment.

  The magnetization directions of the individual small magnets of the two magnet bodies 110d and 210d are the left and right directions in FIG. 13B, and the directions perpendicular to the paper surface in FIGS. This magnetization direction is parallel to the direction intersecting the rotation direction (movement direction) of the magnet body 110d (210d). The magnetizing direction is parallel to the direction perpendicular to the facing direction of the magnet body 110d (210d) and the substrate 140, and parallel to the rotation axis C of the magnet body 110d (210d). The small magnet is preferably magnetized in parallel. Other configurations and operations are the same as those described in the first to third embodiments.

  The rotary encoder 100D of the fourth embodiment also has the same effect as that of the second embodiment or the third embodiment. Whether to use two concentric magnet bodies 110 and 210 as in the second embodiment or the third embodiment, or whether to use two magnet bodies 110d and 210d having the same diameter as in the fourth embodiment Can be selected as appropriate according to the application of the encoder and spatial constraints. For example, when it is desired to arrange the encoder in a space having a smaller outer diameter, the fourth embodiment is more advantageous than the second and third embodiments.

E. Fifth embodiment (linear encoder using two magnet bodies)
FIG. 14 is an explanatory diagram showing a configuration of a linear encoder 100E as the fifth embodiment. The linear encoder 100E has two linear rod-shaped magnet bodies 110e and 210e. These magnet bodies 110e and 210e are provided with yoke members 120 and 220, respectively. The first yoke member 120 may be provided on at least one of both side surfaces of the first magnet body 110e (the upper surface and the lower surface of the magnet body 110e in FIG. 14) or omitted. May be. The same applies to the second yoke member 220. Biaxial magnetic sensor circuits 130 and 230 are provided on the substrate 140 at positions with a predetermined gap with respect to the surfaces of the two magnet bodies 110e and 210e.

  The first magnet body 110e is composed of eight small magnets, and its pole number M1 is eight. The second magnet body 210e is composed of two small magnets, and the number of poles M2 thereof is two. However, these pole numbers M1 and M2 can be set to various integers described in the second embodiment and the third embodiment. As a method for magnetizing the small magnet, it is preferable to use parallel magnetization. In FIG. 14, as an example, the magnetization direction is drawn only on one small magnet of the first magnet body 110e. This magnetization direction is parallel to the direction intersecting the moving direction of the magnet body 110e (the left-right direction in the figure). The magnetization direction is parallel to the direction perpendicular to the facing direction of the magnet body 110e and the substrate 140 and perpendicular to the moving direction of the magnet body 110e. Other configurations and operations are the same as those described in the first to fourth embodiments.

  The linear encoder 100E of the fifth embodiment also has the same effect as that of the second to fourth embodiments. Note that the second magnet body 210e and the related members 220 and 230 may be omitted from the configuration of the linear encoder 100E. In this case, it is possible to obtain a linear encoder that has the same effect as the rotary encoder 100A using one magnet body 110 described in the first embodiment.

F. Sixth Embodiment (Electromechanical device including an encoder)
FIG. 15 is an explanatory diagram illustrating an electromechanical device including the encoder according to the above-described embodiment. The electric motor 500 as an electromechanical device is configured as a coreless two-phase brushless DC motor. The electric motor 500 includes a rotor 510 fixed around the rotating shaft 530 and a stator 520 provided around the rotor 510.

  As shown in FIG. 15B, the stator 520 is provided with an A-phase coil 522A and a B-phase coil 522B. These coils 522A and 522B are concentrated winding coils wound around the radial direction passing through the center of each coil in FIG. 15B, respectively.

  A cylindrical magnet body 110 for generating a driving force is provided on the outer peripheral surface of the rotor 510. This magnet body 110 is composed of eight small magnets, and its pole number M1 is eight. The magnet body 110 also functions as a first magnet body for a rotary encoder. A second magnet body 210 for a rotary encoder is provided on one end face of the rotor 510. Yoke members 120 and 220 are provided on the inner peripheral surfaces of the first magnet body 110 and the second magnet body 210, respectively. On the end surface of the rotor 510 on the side where the second magnet body 210 is provided, a magnetic force adjusting plate 512 that covers the two magnet bodies 110 and 210 and the yoke members 120 and 220 is provided. This magnetic force adjustment plate 512 is made of a soft magnetic material, and is intended to prevent saturation of the output of the magnetic sensor circuit by weakening the magnetic field of the magnet bodies 110 and 210.

  A substrate 140 is provided at a position facing the side surfaces of the two magnet bodies 110 and 210. On the substrate 140, a first two-axis magnetic sensor circuit 130 for detecting the magnetic field of the first magnet body 110 and a second two-axis magnetic sensor for detecting the magnetic field of the second magnet body 210 are provided. A circuit 230 and a control unit 600 are provided. The configuration and operation of the biaxial magnetic sensor circuits 130 and 230 are the same as those described with reference to FIGS. As described with reference to FIG. 3, it is possible to output both the sine wave signal sin θm and the cosine wave signal cos θm from one biaxial magnetic sensor circuit 130. Therefore, it is possible to generate a drive signal for a two-phase coil having a phase difference of 90 degrees by using these two signals sin θm and cos θm. However, in order to use it for generating a drive signal for a two-phase coil, the two two-axis magnetic sensor circuits 130 may be provided at positions where the magnetic angle is 90 degrees out of phase. However, if two-phase coil drive signals are generated using the sine wave signal sinθm and the cosine wave signal cosθm output from one two-axis magnetic sensor circuit 130, two magnetic sensor circuits are provided. This is preferable in that a phase shift caused by a shift in the mounting position of the magnetic sensor circuit does not occur in the drive signal. A method for generating a drive signal for a two-phase coil will be described later.

  The two magnetic bodies 110 and 210 and the two biaxial magnetic sensor circuits 130 and 230 have the same configuration, operation, and effect as the rotary encoder 100B described in the second embodiment (FIGS. 4 to 10). Function as. Individual small magnets constituting the first magnet body 110 are magnetized in a direction crossing the rotation direction of the rotor 510. The magnetization method is preferably parallel magnetization. The same applies to the second magnet body 210.

  FIG. 16 is a block diagram showing an electrical configuration of the electric motor 500. As a motor part of the electric motor 500, a rotor 510, two-phase electromagnetic coils 522A and 522B, and two two-axis magnetic sensor circuits 130 and 230 are depicted. The control unit 600 includes a main control circuit 610, two-phase drive signal generation units 620A and 620B, and two-phase drive circuits 630A and 630B. The main control circuit 610 is supplied with output signals D1, Pa, Pb, Z (see FIG. 3) of the first two-axis magnetic sensor circuit 130 and an output signal D2 of the second two-axis magnetic sensor circuit 230. Based on these signals, position control and speed control are executed. The internal configuration of the main control circuit 610 will be described later. The drive signal generators 620A and 620B for two phases receive digital signals sin θm and cos θm indicating a sine wave and a cosine wave from one two-axis magnetic sensor circuit 130, and perform PWM control based on these digital signals sin θm and cos θm. By executing this, a drive signal for two phases is generated. These drive signals are supplied to drive circuits 630A and 630B, respectively. The drive circuits 630A and 630B are so-called bridge driver circuits. For a method of generating drive signals for two phases by PWM control based on sinusoidal digital signals sin θm and cos θm, and a circuit configuration thereof, for example, FIG. 10 of Japanese Patent Application Laid-Open No. 2008-17678 disclosed by the present applicant. It is possible to use the circuit (excluding the AD converter) shown in FIG. In the present embodiment, the drive signal for two phases is generated using the sine wave signal sinθm and the cosine wave signal cosθm output from one two-axis magnetic sensor circuit 130, and therefore, when two magnetic sensors are used. Compared to the above, it is preferable in that a phase shift of the drive signal due to a shift between two sensor positions does not occur. As a result, it is possible to increase the efficiency of the motor.

  FIG. 17 is a block diagram showing the internal configuration of the main control circuit 610. The communication interface 710 of the main control circuit 610 receives the first magnetic angle output D1 from the first two-axis magnetic sensor circuit 130 and receives the second magnetic angle output D2 from the second two-axis magnetic sensor circuit 230. These magnetic angle outputs D1 and D2 are the same as those shown in FIG. The received magnetic angle outputs D1 and D2 are supplied to the position signal generation unit 730 through the data reception unit 720. The position signal generation unit 730 has the same function as the position signal generation unit 300 described with reference to FIGS. The absolute position output Dabs obtained by the position signal generation unit 730 is supplied to the angular velocity calculation unit 740, and the angular velocity (rotational speed) of the rotor 510 is calculated. The angular velocity is supplied to the angular acceleration calculation unit 750, and the angular acceleration of the rotor 510 is calculated. The output signals Pa, Pb, Z (FIG. 3) of the first two-axis magnetic sensor circuit 130 are supplied to the rotation speed calculation unit 760.

  FIG. 18 is an explanatory diagram showing the internal configuration and operation of the rotation speed calculation unit 760. The B-phase pulse signal Pb is supplied to the data input terminal of the D flip-flop 761, and the A-phase pulse signal Pa is supplied to the clock terminal. The up / down signal Ua / Da that is the output of the D flip-flop 761 is supplied to the input terminal of the up / down counter 762. The high level of the up / down signal Ua / Da indicates that the rotation direction of the rotor 510 is the forward direction (forward direction), and the low level indicates that it is the reverse direction. The periodic signal Z is supplied to the clock terminal of the up / down counter 762, and the count value is changed according to the rising edge of the periodic signal. That is, when the up / down signal Ua / Da is at a high level, the count value is incremented by one, and when the up / down signal Ua / Da is at a low level, the count value is decremented by one. The count value of the up / down counter 762 is supplied to the latch 763. The periodic signal Z is supplied to the clock terminal of the latch 763, and the count value Dn is held in the latch 763 in accordance with the falling edge of the periodic signal Z. The output of the latch 763 is output to the outside as the rotational speed Nr of the rotor 510. The rotation speed Nr indicates the rotation speed of the electric motor 500 from a predetermined reference position with respect to a member (for example, a robot joint) driven by the electric motor 500. The rotational speed Nr is supplied to and stored in the rotational speed storage unit 770 (FIG. 17).

  The main control circuit 610 of FIG. 17 further includes an input / output interface 780, a register 790, and an MPU 795. The input / output interface 780 is connected to the above-described circuits 730, 740, 750, 760, 790, and 795, and supplies outputs from these circuits to the outside as necessary. The register 790 temporarily stores data such as the number of poles of the first magnet body 110 and the absolute position (mechanical angle θr) of the rotor 510. The rotational speed storage unit 770 and the register 790 are preferably backed up by the battery 800 in order to retain the stored contents when the control unit 600 is powered off. In this way, for example, when the electric motor is used as a drive source for the joint of the robot, the position of the joint when the power of the robot is turned off is determined based on the stored contents in the rotation speed storage unit 770 and the register 790. When the power is turned on, the position of the joint can be correctly recognized and controlled. An MPU (Micro Processing Unit) 795 executes various controls (for example, servo control) regarding the electric motor 500. Note that the control process executed by the MPU 795 is realized by the MPU 795 executing a computer program stored in a memory (not shown).

  As described above, when the electromechanical device is configured using the encoder of the above-described embodiment, it is possible to control the electromechanical device while performing position detection with high accuracy. In particular, in the electric motor 500 shown in FIG. 15, since the magnet body 110 for generating the driving force of the electric motor 500 is also used as the first magnet body of the encoder, high accuracy with a small number of members and a simple structure. There is an advantage that a simple encoder can be realized.

  The encoder is applicable not only to an electromechanical device that generates a driving force but also to an electromechanical device that generates power (that is, performs regeneration) and an electromechanical device that can perform both driving and regeneration. is there. Examples of such electromechanical devices include various motors such as a two-phase AC brushless motor, a three-phase AC brushless motor, and a three-phase synchronous motor, a generator, and a motor / generator. As an encoder used for these electromechanical devices, various encoders described in the first to fifth embodiments can be used. Also in the electromechanical apparatus using these various encoders, it is preferable to use the driving or regenerating magnet body in the electromechanical apparatus as the first magnet body of the encoder. However, an encoder may be connected to the outside of the electromechanical device without sharing the magnet body.

G. Various devices Figure utilizing an electromechanical device comprising an encoder 19 is an explanatory diagram showing an example of a double-arm seven-axis robot using an electromechanical device of the above embodiment. The double-arm 7-axis robot 3450 includes a joint motor 3460, a gripper motor 3470, an arm 3480, and a gripper 3490. The joint motor 3460 is disposed at a position corresponding to each joint portion such as a shoulder, an elbow, and a wrist. The joint motor 3460 includes two motors for each joint in order to move the arm 3480 and the grip portion 3490 in a three-dimensional manner. In addition, the gripper motor 3470 opens and closes the gripper 3490 and causes the gripper 3490 to grip an object. In the double-arm 7-axis robot 3450, the electromechanical device described in the above embodiment may be used as the joint motor 3460 or the gripper motor 3470.

  FIG. 20 is an explanatory diagram showing a railway vehicle using the electric machine device of the embodiment. The railway vehicle 3500 includes a transmission-equipped motor 3510 and wheels 3520. The transmission-equipped motor 3510 drives the wheel 3520. Further, the transmission-equipped motor 3510 is used as a generator when the railway vehicle 3500 is braked to regenerate electric power. In addition, as the motor 3510 with a transmission, the electromechanical device described in the above embodiment may be used.

  As can be understood from the examples of FIGS. 19 and 20, the electromechanical device having the encoder of the embodiment can be used for various devices including a moving body such as a robot and a vehicle.

H. Variations:
In the above embodiment, a part of the configuration realized by hardware may be replaced by software, and conversely, a part of the configuration realized by software may be replaced by hardware.

  The present invention is not limited to the above-described embodiments, examples, and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the above effects, replacement or combination can be performed as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 100A-100D ... Rotary encoder 100E ... Linear encoder 110, 110d, 110e ... 1st magnet body 110p ... Split magnet body 110s ... Small magnet 112 ... Cover member 120 ... 1st yoke member 130 ... 1st biaxial magnetic sensor Circuit 131, 132 ... Amplifier circuit 135 ... Signal processing circuit 140 ... Substrate 150 ... Support member 210, 210d, 210e ... Second magnet body 220 ... Second yoke member 230 ... Second biaxial magnetic sensor circuit 300 ... Position Signal generator 500 ... Electric motor 510 ... Rotor 512 ... Magnetic force adjusting plate 520 ... Stator 522A, 522B ... Electromagnetic coil 530 ... Rotating shaft 600 ... Control unit 610 ... Main control circuit 620A, 620B ... Drive signal generator 630A, 630B ... Drive Circuit 710: Communication interface 720 ... Data receiver 730 ... Position signal generator 740 ... Angular velocity calculator 750 ... Angular acceleration calculator 760 ... Rotation speed calculator 762 ... Up / down counter 763 ... Latch 770 ... Rotation speed memory 780 ... I / O interface 790 ... Register 795 ... MPU
800 ... Battery 3460 ... Joint motor 3470 ... Grip motor 3480 ... Arm 3490 ... Grip 3500 ... Railway vehicle 3510 ... Transmission motor 3520 ... Wheel

Claims (13)

An encoder that measures the position of a second member that moves along a predetermined direction of movement with respect to the first member,
A first magnet body provided on the second member and magnetized in a direction crossing the moving direction (M1 is an even number of 4 or more);
A second magnet body provided on the second member and magnetized in a direction crossing the moving direction (M2 is an even number of 2 or more);
A first biaxial magnetic sensor circuit disposed on the first member with a certain gap from the surface of the first magnet body;
A second biaxial magnetic sensor circuit disposed on the first member with a certain gap from the surface of the second magnet body;
A position signal generator for processing output signals of the first two-axis magnetic sensor circuit and the second two-axis magnetic sensor circuit;
With
The position signal generator is configured to output the first member with respect to the first member according to a first magnetic angle output of the first two-axis magnetic sensor circuit and a second magnetic angle output of the second two-axis magnetic sensor circuit. An encoder that generates a position signal indicating the position of the second member. The encoder according to claim 1,
Each of the first two-axis magnetic sensor circuit and the second two-axis magnetic sensor circuit includes a plurality of Xs for measuring a magnetic field along the X axis of the X axis and the Y axis orthogonal to each other. An encoder comprising an axis sensor element and a plurality of Y axis sensor elements for measuring a magnetic field along the Y axis. The encoder according to claim 1 or 2,
The integers M1 and M2 are integers in which M1 / 2 and M2 / 2 are relatively prime,
The position signal generation unit is an encoder that generates the position signal from a first magnetic angle output of the first two-axis magnetic sensor and a second magnetic angle output of the second two-axis magnetic sensor. The encoder according to claim 3, wherein
The integer M1 is equal to 2 ^{Q + 1} (Q is an integer of 1 or more),
The integer M2 is equal to 2,
The first magnetic angle output of the first two-axis magnetic sensor circuit is a digital signal of N1 bits (N1 is an integer of 2 or more) indicating a relative position of the second member with respect to the first member.
The second magnetic angle output of the second two-axis magnetic sensor circuit is a digital signal of N2 bits (N2 is an integer of 2 or more) indicating the relative position of the second member with respect to the first member,
The position signal generation unit arranges the most significant Q bit of the second magnetic angle output at the most significant position, and sets the N1 bit of the first magnetic angle output below the most significant Q bit of the second magnetic angle output. An encoder that generates a signal of (N1 + Q) bits arranged in the position signal as the position signal. The encoder according to claim 4, wherein
The position signal generator is
When the first magnetic angle output of the first two-axis magnetic sensor circuit and the second magnetic angle output of the second two-axis magnetic sensor circuit both increase in accordance with the movement of the second member. The timing at which the first magnetic angle output returns from the maximum value of the first magnetic angle output to the minimum value coincides with the timing at which the most significant Q bit of the second magnetic angle output is incremented. Correcting the most significant Q bit of the second magnetic angle output according to one magnetic angle output;
Generating the position signal of the (N1 + Q) bits using the most significant Q bits of the corrected second magnetic angle output;
encoder. The encoder according to any one of claims 1 to 5,
The second member is a rotating body,
The individual small magnets constituting the first magnet body are magnetized in a direction perpendicular to the opposing direction of the first member and the second member, the center of the individual small magnets, and the rotation axis of the rotating body. An encoder that is magnetized in parallel along the magnetizing direction parallel to the direction connecting the two. The encoder according to claim 6, wherein
The second member has an annular yoke member provided on at least one of an inner periphery and an outer periphery of the first magnet body,
The two-axis magnetic sensor circuit is an encoder arranged at a position where a magnetic flux center portion where the magnetic flux density measured along the radial direction of the second member is zero is removed. The encoder according to any one of claims 1 to 7,
The first magnet body is configured by arranging a plurality of divided magnet bodies in an annular shape,
Each divided magnet body includes a small magnet having a rectangular parallelepiped shape, and a covering member that covers at least a part of the periphery of the small magnet so that the entire shape of the divided magnet body is an isosceles trapezoidal columnar shape. encoder. An electromechanical device,
A magnet for driving or regenerating,
An electromagnetic coil for driving or regeneration;
The encoder according to any one of claims 1 to 8,
A control unit for controlling the operation of the electromechanical device;
With
The driving or regenerating magnet body is shared as the first magnet body of the encoder,
Electromechanical equipment. An electromechanical device according to claim 9,
The electromechanical device is a two-phase AC brushless motor having a two-phase electromagnetic coil;
The control unit includes a drive signal generation unit that generates a drive signal for the two-phase electromagnetic coil from the sine wave signal and the cosine wave signal output from the first two-axis magnetic sensor circuit of the encoder. , Electromechanical devices. An electromechanical device operable as a two-phase AC brushless motor having a two-phase electromagnetic coil,
A magnet body;
A two-phase electromagnetic coil;
The encoder according to any one of claims 1 to 8,
A control unit for controlling the operation of the electromechanical device;
With
The control unit includes a drive signal generation unit that generates a drive signal for the two-phase electromagnetic coil from the sine wave signal and the cosine wave signal output from the first two-axis magnetic sensor circuit of the encoder. , Electromechanical devices. A robot,
A magnet for driving or regenerating,
An electromagnetic coil for driving or regeneration;
The encoder according to any one of claims 1 to 8,
With
A robot having an electromechanical device in which the magnet body for driving or regeneration is shared as the magnet body of the encoder. A railway vehicle,
A magnet for driving or regenerating,
An electromagnetic coil for driving or regeneration;
The encoder according to any one of claims 1 to 8,
With
A railway vehicle having an electromechanical device in which the magnet body for driving or regeneration is shared as the magnet body of the encoder.

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