WO2024079787A1 - 磁気式エンコーダ - Google Patents

磁気式エンコーダ Download PDF

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Publication number
WO2024079787A1
WO2024079787A1 PCT/JP2022/037887 JP2022037887W WO2024079787A1 WO 2024079787 A1 WO2024079787 A1 WO 2024079787A1 JP 2022037887 W JP2022037887 W JP 2022037887W WO 2024079787 A1 WO2024079787 A1 WO 2024079787A1
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WO
WIPO (PCT)
Prior art keywords
magnetic
magnetic field
magnets
source
magnet
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2022/037887
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English (en)
French (fr)
Japanese (ja)
Inventor
明良 堀田
武史 武舎
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Priority to KR1020257010213A priority Critical patent/KR20250054106A/ko
Priority to JP2024550943A priority patent/JP7767641B2/ja
Priority to DE112022007894.4T priority patent/DE112022007894T5/de
Priority to CN202280100624.3A priority patent/CN119998630A/zh
Priority to PCT/JP2022/037887 priority patent/WO2024079787A1/ja
Priority to TW112137365A priority patent/TWI860109B/zh
Publication of WO2024079787A1 publication Critical patent/WO2024079787A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/244—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains
    • G01D5/245—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains using a variable number of pulses in a train
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/142—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage using Hall-effect devices
    • G01D5/145—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage using Hall-effect devices influenced by the relative movement between the Hall device and magnetic fields
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/003—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring position, not involving coordinate determination
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/30—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring angles or tapers; for testing the alignment of axes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/244—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains
    • G01D5/24428—Error prevention
    • G01D5/24433—Error prevention by mechanical means
    • G01D5/24438—Special design of the sensing element or scale

Definitions

  • This disclosure relates to a magnetic encoder having a magnetic detection unit and a position detection unit that move relative to each other.
  • a magnetic encoder has a magnetic detection unit and a position detection unit that move relative to one another.
  • Such magnetic encoders are used in rotary encoders, which are rotation detectors for controlling rotary servo motors, and linear encoders, which are position detectors for controlling linear motors.
  • Patent Document 1 shows a magnetic scale unit having multiple magnetic poles.
  • the magnetic scale unit has a magnetic pole row in which multiple magnetic poles of the same polarity are arranged at equal intervals.
  • the interval between the magnetic poles is greater than the width in the arrangement direction of the magnetic poles, but is less than twice the width in the arrangement direction of the magnetic poles.
  • the magnetic sensor outputs the magnetic field change of the magnetic scale unit as an electrical signal, and position information is obtained from the voltage peak.
  • Patent Document 1 the widths of the multiple magnets of the same polarity are all the same, so there is a problem in that only the peak position of the magnetic field and discrete position information corresponding to the peak position can be obtained.
  • the present disclosure has been made in consideration of the above, and aims to provide a magnetic encoder that can obtain a smooth, long-period sine wave signal and can acquire continuous, highly accurate position information over a wide range.
  • the magnetic encoder of the present disclosure is a magnetic encoder in which a magnetic scale unit and a position detection unit move relative to each other along a first direction
  • the magnetic scale unit includes a first magnetic field source and a second magnetic field source arranged side by side in the first direction and having magnetization directions opposite to each other, a magnetic body arranged at a distance from the first magnetic field source and the second magnetic field source along the magnetization directions of the first magnetic field source and the second magnetic field source, and a base for positioning the first magnetic field source, the second magnetic field source, and the magnetic body.
  • the position detection unit includes a magnetic detection element arranged at a distance from each of the first magnetic field source, the second magnetic field source, and the magnetic body in a region sandwiched between the first magnetic field source, the second magnetic field source, and the magnetic body, and outputs a change in the magnetic field as an electrical signal.
  • the length of the magnetic body in the first direction corresponds to one wavelength of a wavelength determined based on the resolution of position detection of the magnetic scale unit in the first direction
  • the surface facing the first magnetic field source and the second magnetic field source is a curved surface that is most convex at positions corresponding to 1/4 and 3/4 of the wavelength from the end in the first direction.
  • the first magnetic field source is disposed at a position facing the position corresponding to 1/4 of the wavelength of the magnetic body
  • the second magnetic field source is disposed at a position facing the position corresponding to 3/4 of the wavelength of the magnetic body.
  • the magnetic encoder disclosed herein has the advantage of being able to obtain a smooth, long-period sinusoidal signal, enabling continuous, highly accurate position information to be obtained over a wide range.
  • FIG. 1 is a perspective view showing a magnetic encoder according to a first embodiment
  • FIG. 1 is a front view showing a magnetic encoder according to a first embodiment
  • FIG. 1 is a front view of a magnetic encoder according to a comparative example of the first embodiment
  • FIG. 4 is a diagram showing a flow of magnetic flux in a magnetic encoder according to a comparative example of the first embodiment
  • FIG. 13 is a diagram showing a waveform of the strength of a magnetic field applied to a magnetic detection element by a magnetic scale unit of a magnetic encoder according to a comparative example of the first embodiment.
  • FIG. 1 is a diagram showing a flow of magnetic flux in a magnetic encoder according to a first embodiment
  • FIG. 1 is a diagram showing a flow of magnetic flux in a magnetic encoder according to a first embodiment
  • FIG. 13 is a diagram showing a waveform of the strength of a magnetic field applied to a magnetic detection element by a magnetic scale unit of a magnetic encoder according to the first embodiment.
  • FIG. 13 is a diagram showing the waveform of the strength of the magnetic field applied to the magnetic detection element by the magnetic scale unit when the distance between the magnetic scale and the magnetic detection element of the magnetic encoder according to the comparative example of the first embodiment varies.
  • FIG. 13 is a diagram showing the waveform of the strength of the magnetic field applied to the magnetic detection element by the magnetic scale unit when the distance between the magnetic scale and the magnetic detection element of the magnetic encoder according to the first embodiment varies;
  • FIG. 13 is a front view of a magnetic encoder according to a second embodiment of the present invention; FIG.
  • FIG. 13 is a diagram showing the direction of internal magnetization of a magnet group in a magnetic encoder according to a second embodiment.
  • FIG. 13 is a diagram showing a waveform of the strength of a magnetic field applied to a magnetic detection element by a magnetic scale unit of a magnetic encoder according to a second embodiment.
  • FIG. 13 is a front view of a magnetic encoder according to a third embodiment;
  • FIG. 13 is a diagram showing the direction of internal magnetization of a magnet group in a magnetic encoder according to a third embodiment.
  • FIG. 13 is a perspective view showing a configuration of a magnetic encoder according to a fourth embodiment;
  • FIG. 13 is a front view showing the configuration of a magnetic encoder according to a fourth embodiment;
  • FIG. 1 is a perspective view showing a magnetic encoder according to the first embodiment.
  • FIG. 2 is a front view showing a magnetic encoder according to the first embodiment.
  • the magnetic encoder 100 according to the first embodiment includes a magnetic scale unit 101 and a position detection unit 106 that detects a magnetic field generated by the magnetic scale unit 101.
  • the magnetic encoder 100 according to the first embodiment is a linear encoder.
  • the magnetic scale unit 101 includes a magnet 103 that is a first magnetic field generation source, a magnet 104 that is a second magnetic field generation source, a magnetic body 102 that is arranged at an interval from each of the magnets 103 and 104 in the magnetization directions of the magnets 103 and 104, and a non-magnetic base 105 that fixes each of the magnets 103 and 104 and the magnetic body 102.
  • the base 105 may be formed of resin.
  • the position detection unit 106 has a plurality of magnetic detection elements 107 that detect the magnetic field generated from the magnetic scale unit 101, and a substrate 108 on which the magnetic detection elements 107 are attached.
  • the magnetic encoder 100 is shown in a three-dimensional Cartesian coordinate system of xyz.
  • the x direction corresponds to the movement direction of the magnetic scale unit 101
  • the z direction corresponds to the direction in which the magnetic scale unit 101 and the position detection unit 106 face each other
  • the y direction is perpendicular to the x and z directions.
  • the x direction corresponds to the first direction.
  • Tsm indicates the minimum length of the magnetic body 102 in the z direction
  • Lsm indicates the length of the magnetic body 102 in the x direction
  • Lm indicates the magnet width, which is the length in the x direction of each of the magnets 103 and 104
  • G indicates the distance from each of the surfaces of the magnets 103 and 104 to the sensing surface of the magnetic detection element 107.
  • the z direction length dTsm of the convex portion of the magnetic body 102 is in the relationship dTsm>Lsm/50.
  • the x direction length Lsm of the magnetic body 102 is twice the magnet width Lm of each of the magnets 103 and 104. Note that the length Lsm of the magnetic body 102 in the x direction, which is the first direction, corresponds to one wavelength of the wavelength determined based on the position detection resolution of the magnetic scale unit 101 in the x direction.
  • the surface of magnetic body 102 facing magnets 103 and 104 is curved and convex toward magnets 103 and 104.
  • the distance between magnetic body 102 and magnets 103 and 104 is maximum at both ends and the center of magnetic body 102 in the x direction.
  • the distance between magnetic body 102 and magnets 103 and 104 is minimum at a position 1/4 times the x-direction length Lsm of magnetic body 102 and a position 3/4 times Lsm from the end of magnetic body 102 in the x direction.
  • the magnetic scale unit 101 and the position detection unit 106 move relative to one another.
  • the magnetic scale unit 101 is a mover that moves in the x direction.
  • the position detection unit 106 is a stator that is fixed at a certain distance from the magnetic scale unit 101 in the z direction. The position detection unit 106 detects the position of the magnetic scale unit 101 from the change in the magnetic field when the magnetic scale unit 101 passes by.
  • the substrate 108 is strip-shaped with a surface extending parallel to the xy plane, with the x direction being the longitudinal direction. As shown in FIG. 2, multiple magnetic detection elements 107 are arranged on the substrate 108 at equal pitch in the x direction.
  • the pitch at which the magnetic detection elements 107 are arranged is set to a pitch equal to or less than the wavelength of the sine wave formed by the magnetic scale unit 101 so as to prevent the occurrence of areas where position detection is not possible.
  • the magnetic detection elements 107 are arranged in the area between the magnets 103 and 104 and the magnetic material 102, with a space between each of the magnets 103 and 104 and the magnetic material 102, and output the change in the magnetic field as an electrical signal.
  • FIG. 3 is a front view of a magnetic encoder according to a comparative example of embodiment 1.
  • the magnetic scale unit 111 does not include a magnetic material
  • the base 115 has magnets 113 and 114 fixed thereto.
  • the position detection unit 116 has a plurality of magnetic detection elements 117 that detect the magnetic field generated by the magnetic scale unit 111, and a substrate 118 on which the magnetic detection elements 117 are attached.
  • the substrate 118 is strip-shaped with a surface extending parallel to the xy plane, and the x direction is the longitudinal direction.
  • the multiple magnetic detection elements 117 of the position detection unit 116 are arranged on the substrate 118 at equal pitch in the x direction, as shown in FIG. 3.
  • FIG. 4 is a diagram showing the flow of magnetic flux in a magnetic encoder according to a comparative example of embodiment 1.
  • magnetic encoder 110 according to a comparative example of embodiment 1 for example, most of the magnetic flux emitted from magnet 113 dissipates without returning to magnet 114, and only a small portion of the magnetic flux returns to magnet 114. For this reason, in magnetic encoder 110 according to the comparative example, the magnetic flux becomes significantly weaker as it moves away from the surfaces of magnets 113 and 114, and as the distance G from each surface of magnets 113 and 114 to the sensing surface of magnetic detection element 117 increases, the amplitude of the strength of the magnetic field applied to magnetic detection element 117 decreases.
  • FIG. 5 is a diagram showing the waveform of the strength of the magnetic field applied to the magnetic detection element by the magnetic scale unit of the magnetic encoder according to the comparative example of the first embodiment.
  • the magnetization direction of the magnet 113 is the +z direction
  • the magnetization direction of the magnet 114 is the -z direction.
  • the vertical axis shows the magnetic flux density Bz
  • the horizontal axis shows the position of the magnetic scale unit 111. Note that the [a.u.] on the vertical and horizontal axes indicates arbitrary units.
  • the solid line shows the strength of the magnetic field applied to the magnetic detection element 117 by the magnetic scale unit 111 of the magnetic encoder 110 according to the comparative example of the first embodiment
  • the dashed line shows the waveform of a sine wave, which is an ideal waveform.
  • the magnetic encoder 110 according to the comparative example has a steeper rise and fall of the magnetic flux density compared to a sine wave, and the section of the magnet position where the amplitude is close to the maximum value is longer.
  • FIG. 6 is a diagram showing the flow of magnetic flux in the magnetic encoder according to the first embodiment.
  • magnetic flux emitted from magnet 103 flows into magnetic body 102 and flows toward magnet 104 via magnetic body 102. Therefore, a magnetic circuit is formed by magnet 103, magnetic body 102, and magnet 104, suppressing the divergence of magnetic flux, and the magnetic flux density is high in the area surrounded by magnets 103, 104, and magnetic body 102, and the variation in magnetic flux density is small even when away from the surfaces of magnets 113 and 114.
  • FIG. 7 is a diagram showing the waveform of the strength of the magnetic field applied to the magnetic detection element by the magnetic scale unit of the magnetic encoder according to the first embodiment.
  • the magnetization direction of the magnet 103 is the +z direction
  • the magnetization direction of the magnet 104 is the -z direction.
  • the vertical axis shows the magnetic flux density Bz
  • the horizontal axis shows the position of the magnetic scale unit 101. Note that the [a.u.] on the vertical and horizontal axes indicates arbitrary units.
  • the solid line shows the strength of the magnetic field applied to the magnetic detection element 107 by the magnetic scale unit 101 of the magnetic encoder 100 according to the first embodiment
  • the dashed line shows the waveform of an ideal sine wave.
  • the waveform of the strength of the magnetic field applied to the magnetic detection element 107 by the magnetic scale unit 101 is a waveform close to a sine wave.
  • FIG. 8 is a diagram showing the waveform of the strength of the magnetic field applied to the magnetic detection element by the magnetic scale unit when the distance between the magnetic scale and the magnetic detection element of the magnetic encoder according to the comparative example of embodiment 1 varies.
  • the dashed line shows the waveform of an ideal sine wave.
  • the medium-thickness solid line shows the strength of the magnetic field applied to the magnetic detection element 117 by the magnetic scale unit 111.
  • the thick solid line shows the strength of the magnetic field applied to the magnetic detection element 117 by the magnetic scale unit 111 when the distance G from the surfaces of the magnets 113 and 114 to the sensing surface of the magnetic detection element 117 becomes large.
  • FIG. 8 shows the waveform of the strength of the magnetic field applied to the magnetic detection element by the magnetic scale unit when the distance G from the surfaces of the magnets 113 and 114 to the sensing surface of the magnetic detection element 117 becomes large.
  • the thin solid line shows the strength of the magnetic field applied to the magnetic detection element 117 by the magnetic scale unit 111 when the distance G from the surfaces of the magnets 113 and 114 to the sensing surface of the magnetic detection element 117 becomes small.
  • the strength of the magnetic field applied to the magnetic detection element 117 differs greatly from an ideal sine wave, regardless of whether the distance G increases or decreases.
  • the waveform of the strength of the magnetic field applied to the magnetic detection element 117 has a longer section at the magnet position where the wave is flattened and the amplitude approaches the maximum value than a sine wave. For this reason, it is difficult to accurately match the strength of the magnetic field applied to the magnetic detection element 117 with the magnet position, resulting in low position detection accuracy.
  • FIG. 9 is a diagram showing the waveform of the magnetic field strength applied to the magnetic detection element by the magnetic scale unit when the distance between the magnetic scale and the magnetic detection element of the magnetic encoder of embodiment 1 varies.
  • the dashed line shows an ideal sine wave waveform.
  • the medium-thickness solid line shows the magnetic field strength applied to the magnetic detection element 107 by the magnetic scale unit 101.
  • the thick solid line shows the magnetic field strength applied to the magnetic detection element 107 by the magnetic scale unit 101 when the distance G from the surfaces of the magnets 103 and 104 to the sensing surface of the magnetic detection element 107 becomes large.
  • FIG. 9 shows the waveform of the magnetic field strength applied to the magnetic detection element by the magnetic scale unit when the distance between the magnetic scale and the magnetic detection element of the magnetic encoder of embodiment 1 varies.
  • the dashed line shows an ideal sine wave waveform.
  • the medium-thickness solid line shows the magnetic field strength applied to the magnetic detection element 107 by the magnetic scale unit 101.
  • the thick solid line shows the magnetic field
  • the thin solid line shows the magnetic field strength applied to the magnetic detection element 107 by the magnetic scale unit 101 when the distance G from the surfaces of the magnets 103 and 104 to the sensing surface of the magnetic detection element 107 becomes small.
  • the difference between the strength of the magnetic field applied to the magnetic detection element 107 and an ideal sine wave is small.
  • the waveform of the strength of the magnetic field applied to the magnetic detection element 107 is approximately sine wave shaped. Therefore, the strength of the magnetic field applied to the magnetic detection element 107 can be accurately matched to the magnet position, improving the position detection accuracy.
  • the magnetic body 102 has a curved surface that is convex toward the magnets 103 and 104, and the magnetic scale unit 101 can generate a smooth sinusoidal signal with a long period by the magnets 103 and 104.
  • the magnetic body 102 forms a magnetic circuit together with the magnets 103 and 104, so that the absolute position of the magnetic scale unit 101 can be detected continuously and with high accuracy over a wide range.
  • magnets 103 and 104 and magnetic body 102 may also be spaced apart in the z direction.
  • Embodiment 2. 10 is a front view of a magnetic encoder according to embodiment 2.
  • the magnetic encoder 200 according to embodiment 2 includes a magnet group 123 which is a first magnetic field generation source and a magnet group 124 which is a second magnetic field generation source.
  • Each of the magnet group 123 and the magnet group 124 is formed of a plurality of magnets 10.
  • Each of the magnet group 123 and the magnet group 124 and the magnetic body 202 are fixed by a base body 205.
  • the surface of the magnetic body 202 facing the magnet group 123 and the magnet group 124 is a curved surface that is convex toward the magnet group 123 and the magnet group 124.
  • the distance between the magnetic body 202 and each of the magnet group 123 and the magnet group 124 is maximum at both ends and the center of the magnetic body 202 in the x direction.
  • the distance between the magnetic body 202 and each of the magnet groups 123 and 124 is smallest at a position 1/4 of the x-directional length Lsm of the magnetic body 202 and at a position 3/4 of Lsm from the end of the magnetic body 202 in the x-direction.
  • FIG. 11 is a diagram showing the direction of internal magnetization of the magnet group in the magnetic encoder according to the second embodiment.
  • a magnet width modulation method is used that changes the magnet width Lm, which is the length of the magnet 10 in the first direction, the x-direction.
  • the arrows in the magnet group 123 and the magnet group 124 shown in FIG. 11 indicate the direction of internal magnetization after magnetization.
  • the tip of each arrow indicates the N pole, and the base end indicates the S pole. Therefore, all the magnets 10 constituting the magnet group 123 have an N pole on the side facing the position detection unit 206.
  • All the magnets 10 constituting the magnet group 124 have an S pole on the side facing the position detection unit 206.
  • each magnet 10 is simply referred to as the magnetization direction.
  • all the magnets 10 constituting the magnet group 123 are magnetized in the same magnetization direction, and all the magnets 10 constituting the magnet group 124 are magnetized in the magnetization direction opposite to that of the magnets 10 constituting the magnet group 123.
  • the number of magnets 10 constituting magnet group 123 and the number of magnets 10 constituting magnet group 124 are the same, and are three or more.
  • the distance between magnets 10 is constant.
  • Magnet width Lm increases and decreases in the x direction according to a sine function, which is a sine wave function. That is, in each of magnet group 123 and magnet group 124, magnet width Lm increases in the x direction from the end to the center. In other words, in each of magnet group 123 and magnet group 124, magnet width Lm increases stepwise from one end to the center in the x direction, and then decreases stepwise from the center to the other end in the x direction. Meanwhile, distance Ld between magnets 10 is constant.
  • the number of magnets 10 constituting magnet group 123 is seven.
  • the number of magnets 10 constituting magnet group 124 is also seven.
  • the position a distance a away in the -x direction from the -x end of the magnet 10 that is placed at the farthest position from magnet group 124 among the magnets 10 constituting magnet group 123 corresponds to 0 degrees of the sine function.
  • the position a distance a away in the +x direction from the +x end of the magnet 10 that is placed at the farthest position from magnet group 123 among the magnets 10 constituting magnet group 124 corresponds to 360 degrees of the sine function.
  • the position a distance a away in the +x direction from the +x end of the magnet 10 that is placed at the closest position to magnet group 124 among the magnets 10 constituting magnet group 123, and the position a distance a away in the -x direction from the -x end of the magnet 10 that is placed at the closest position to magnet group 123 among the magnets 10 constituting magnet group 124 correspond to 180 degrees of the sine function.
  • the distance a is set so that the midpoint between the -x end of the magnet 10 that is located farthest from magnet group 124 among the magnets 10 that make up magnet group 123 and the +x end of the magnet 10 that is located closest to magnet group 124 corresponds to 90 degrees in the sine function, and the midpoint between the +x end of the magnet 10 that is located farthest from magnet group 123 among the magnets 10 that make up magnet group 124 and the -x end of the magnet 10 that is located closest to magnet group 123 corresponds to 270 degrees in the sine function.
  • the position detection unit 206 is similar to the position detection unit 106 of the magnetic encoder 100 according to the first embodiment, and has a plurality of magnetic detection elements 207 that detect the magnetic field generated by the magnetic scale unit 201, and a substrate 208 on which the magnetic detection elements 207 are attached.
  • the magnetic scale unit 201 and the position detection unit 206 move relative to one another.
  • the magnetic scale unit 201 is a mover that moves in the x direction.
  • the position detection unit 206 is a stator that is fixed at a fixed distance in the z direction from the magnetic scale unit 201.
  • the position detection unit 206 detects the position of the magnetic scale unit 201 from the change in the magnetic field when the magnetic scale unit 201 passes by.
  • the substrate 208 is strip-shaped with a surface extending parallel to the xy plane, with the x direction being the longitudinal direction. As shown in FIG. 10, multiple magnetic detection elements 207 are arranged on the substrate 208 at equal pitches in the x direction.
  • the pitch at which the magnetic detection elements 207 are arranged is set to a pitch equal to or less than the wavelength of the sine wave formed by the magnetic scale unit 201, so as to prevent the occurrence of areas where position detection is not possible.
  • FIG. 12 is a diagram showing the waveform of the magnetic field strength applied to the magnetic detection element by the magnetic scale unit of the magnetic encoder of embodiment 2.
  • the vertical axis shows the magnetic flux density Bz
  • the horizontal axis shows the position of the magnetic scale unit 201. Note that [a.u.] on the vertical and horizontal axes indicates arbitrary units.
  • the solid line shows the magnetic field strength applied to the magnetic detection element 207 by the magnetic scale unit 201 of the magnetic encoder 200 of embodiment 2
  • the dashed line shows the waveform of an ideal sine wave.
  • the waveform of the magnetic field strength applied to the magnetic detection element 207 by the magnetic scale unit 201 is close to a sine wave.
  • the waveform of the magnetic field strength applied to the magnetic detection element 207 by the magnetic scale unit 201 of the magnetic encoder 200 according to embodiment 2 is closer to a sine wave.
  • the magnetic encoder 200 according to the second embodiment has a waveform of the magnetic field strength applied to the magnetic detection element 207 by the magnetic scale unit 201 that is closer to a sine wave than the waveform of the magnetic field strength applied to the magnetic detection element 107 by the magnetic scale unit 101 of the magnetic encoder 100 according to the first embodiment, and therefore can further improve the position detection accuracy compared to the magnetic encoder 100 according to the first embodiment.
  • the magnet width is changed to generate a sinusoidal change in the magnetic field, but the magnet width may be kept the same and the magnetic force of each magnet 10 may be changed to generate a sinusoidal change in the magnetic field.
  • Methods for changing the magnetic force include gradually changing the thickness of the magnet 10, gradually changing the distance from the magnetic detection element 207, gradually changing the magnetization rate of the magnet 10, or gradually changing the magnetic material of the magnet 10.
  • Embodiment 3. 13 is a front view of a magnetic encoder according to embodiment 3.
  • the magnetic encoder 300 according to embodiment 3 includes a magnet group 133 which is a first magnetic field generation source and a magnet group 134 which is a second magnetic field generation source.
  • Each of the magnet group 133 and the magnet group 134 is formed of a plurality of magnets 10.
  • Each of the magnet group 133 and the magnet group 134 and the magnetic body 302 are fixed by a base body 305.
  • the surface of the magnetic body 302 facing the magnet group 133 and the magnet group 134 is a curved surface that is convex toward the magnet group 133 and the magnet group 134.
  • the distance between the magnetic body 302 and each of the magnet group 133 and the magnet group 134 is maximum at both ends and the center of the magnetic body 302 in the x direction.
  • the distance between the magnetic body 302 and each of the magnet groups 133 and 134 is smallest at a position 1/4 of the x-directional length Lsm of the magnetic body 302 and at a position 3/4 of Lsm from the end of the magnetic body 302 in the x-direction.
  • FIG. 14 is a diagram showing the direction of internal magnetization of the magnet group in the magnetic encoder according to the third embodiment.
  • a magnet interval modulation method is used to change the interval between the magnets 10.
  • the arrows in the magnet group 133 and the magnet group 134 shown in FIG. 14 indicate the direction of internal magnetization after magnetization.
  • the tip of each arrow indicates the N pole, and the base end indicates the S pole. Therefore, all the magnets 10 constituting the magnet group 133 have an N pole on the side facing the position detection unit 306.
  • All the magnets 10 constituting the magnet group 134 have an S pole on the side facing the position detection unit 306.
  • the direction of internal magnetization of each magnet 10 is simply referred to as the magnetization direction. In this way, all the magnets 10 constituting the magnet group 133 are magnetized in the same magnetization direction, and all the magnets 10 constituting the magnet group 134 are magnetized in the magnetization direction opposite to that of the magnets 10 constituting the magnet group 133.
  • the position detection unit 306 has a number of magnetic detection elements 307 that detect the magnetic field generated by the magnetic scale unit 301, and a substrate 308 on which the magnetic detection elements 307 are attached.
  • the number of magnets 10 constituting magnet group 133 and the number of magnets 10 constituting magnet group 134 are the same, and are 3 or more.
  • magnet width Lm is constant.
  • the distance between magnets 10 increases and decreases according to a sine function, which is a sine wave function. That is, in each of magnet group 123 and magnet group 124, distance Ld between magnets 10 decreases from the end to the center in the x direction. In other words, in each of magnet group 133 and magnet group 134, distance Ld between magnets 10 decreases stepwise from one end to the center in the x direction, and then increases stepwise from the center to the other end in the x direction.
  • the number of magnets 10 constituting magnet group 133 is nine.
  • the number of magnets 10 constituting magnet group 134 is also nine.
  • the position a distance a away in the -x direction from the -x end of the magnet 10 constituting magnet group 133 that is placed at the farthest position from magnet group 134 corresponds to 0 degrees of the sine function.
  • the position a distance a away in the +x direction from the +x end of the magnet 10 constituting magnet group 134 that is placed at the farthest position from magnet group 133 corresponds to 360 degrees of the sine function.
  • the position a distance a away in the +x direction from the +x end of the magnet 10 constituting magnet group 133 that is placed at the closest position to magnet group 134, and the position a distance a away in the -x direction from the -x end of the magnet 10 constituting magnet group 134 that is placed at the closest position to magnet group 133 correspond to 180 degrees of the sine function.
  • the distance a is set so that the midpoint between the -x end of the magnet 10 that is located farthest from magnet group 134 among the magnets 10 that make up magnet group 133 and the +x end of the magnet 10 that is located closest to magnet group 134 corresponds to 90 degrees in the sine function, and the midpoint between the +x end of the magnet 10 that is located farthest from magnet group 133 among the magnets 10 that make up magnet group 134 and the -x end of the magnet 10 that is located closest to magnet group 133 corresponds to 270 degrees in the sine function.
  • the waveform of the magnetic field strength applied to the magnetic detection element 307 by the magnetic scale unit 301 is closer to a sine wave than the waveform of the magnetic field strength applied to the magnetic detection element 107 by the magnetic scale unit 101 of the magnetic encoder 100 according to embodiment 1. Therefore, the magnetic encoder 300 according to embodiment 3 can further improve the position detection accuracy compared to the magnetic encoder 100 according to embodiment 1.
  • Fig. 15 is a perspective view showing the configuration of a magnetic encoder according to embodiment 4.
  • Fig. 16 is a front view showing a magnetic encoder according to embodiment 4.
  • a magnetic encoder 400 according to embodiment 4 is a rotary encoder.
  • the magnetic encoder 400 according to embodiment 4 includes a ring-shaped magnetic scale unit 401 and a position detection unit 406 that detects a magnetic field generated from the magnetic scale unit 401.
  • the magnetic scale unit 401 is a mover
  • the position detection unit 406 is a stator.
  • the magnetic scale unit 401 has a magnet 403 which is a first magnetic field generating source, a magnet 404 which is a second magnetic field generating source, a magnetic body 402 which is arranged at a distance from the magnets 403 and 404 in the magnetization direction of the magnets 403 and 404, and a non-magnetic base 405 which fixes the magnetic body 402, the magnets 403 and 404.
  • the surface of the magnetic body 402 which faces the magnets 403 and 404 is a curved surface which is convex towards the magnets 403 and 404.
  • the base 405 is cylindrical.
  • the magnetic scale unit 401 is mounted on a rotating shaft (not shown) and rotates. In the present disclosure, in the case of a rotary encoder, the circumferential direction which is the direction of rotation of the magnetic scale unit 401 corresponds to the first direction.
  • the position detection unit 406 comprises a ring-shaped substrate 408 and a magnetic detection element 407 mounted on the substrate 408.
  • the magnetic detection element 407 detects the magnetic field generated by the magnetic scale unit 401.
  • the magnetic detection element 407 is fixed on the substrate 408 at a fixed distance in the z direction from the magnetic scale unit 401.
  • the position detection unit 406 detects the position of the magnetic scale unit 401 based on the change in the magnetic field when the magnetic scale unit 401 rotates. Note that the substrate 408 is not shown in Figure 15.
  • the magnet width modulation method shown in embodiment 2 or the magnet spacing modulation method shown in embodiment 3 may be applied to the magnetic encoder 400 of embodiment 4.
  • the magnetic body 402 forms a magnetic circuit together with the magnet 403 and the magnet 404, so that the absolute position of the magnetic scale unit 401 can be detected with high accuracy.
  • 10,103,104,113,114,403,404 magnets 100,110,200,300,400 magnetic encoders, 101,111,201,301,401 magnetic scale units, 102,202,302,402 magnetic materials, 105,115,205,305,405 base bodies, 106,116,206,306,406 position detection units, 107,117,207,307,407 magnetic detection elements, 108,118,208,308,408 substrates, 123,124,133,134 magnet groups.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Transmission And Conversion Of Sensor Element Output (AREA)
PCT/JP2022/037887 2022-10-11 2022-10-11 磁気式エンコーダ Ceased WO2024079787A1 (ja)

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KR1020257010213A KR20250054106A (ko) 2022-10-11 2022-10-11 자기식 인코더
JP2024550943A JP7767641B2 (ja) 2022-10-11 2022-10-11 磁気式エンコーダ
DE112022007894.4T DE112022007894T5 (de) 2022-10-11 2022-10-11 Magnetischer encoder
CN202280100624.3A CN119998630A (zh) 2022-10-11 2022-10-11 磁式编码器
PCT/JP2022/037887 WO2024079787A1 (ja) 2022-10-11 2022-10-11 磁気式エンコーダ
TW112137365A TWI860109B (zh) 2022-10-11 2023-09-28 磁式編碼器

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013238485A (ja) * 2012-05-15 2013-11-28 Asahi Kasei Electronics Co Ltd エンコーダ及びそれを用いたアクチュエータ
JP2019143991A (ja) * 2018-02-16 2019-08-29 Tdk株式会社 磁気センサシステムおよび磁気スケール

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Publication number Priority date Publication date Assignee Title
US5936319A (en) * 1998-02-26 1999-08-10 Anorad Corporation Wireless permanent magnet linear motor with magnetically controlled armature switching and magnetic encoder
US5545985A (en) * 1994-03-16 1996-08-13 Campbell; Peter Magnetoresistive position sensor including an encoder wherein the magnetization extends greater than 0.5 times the pole pitch below the surface
JP2001227904A (ja) 2000-02-14 2001-08-24 Sumitomo Metal Mining Co Ltd 磁気スケールユニット及びその応用装置
JP2006322811A (ja) * 2005-05-19 2006-11-30 Uchiyama Mfg Corp 磁気エンコーダ及び被検出部材
JP5759867B2 (ja) * 2011-10-28 2015-08-05 山洋電気株式会社 磁気エンコーダ

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013238485A (ja) * 2012-05-15 2013-11-28 Asahi Kasei Electronics Co Ltd エンコーダ及びそれを用いたアクチュエータ
JP2019143991A (ja) * 2018-02-16 2019-08-29 Tdk株式会社 磁気センサシステムおよび磁気スケール

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