JP2019109093A - Rotary encoder, driving device, torque sensor, robot, and laser beam machine - Google Patents

Abstract

To reduce a measurement difference due to electric noise.SOLUTION: An optical scale 201 has multiple patterns 202 that are periodically arranged at an equal pitch. A sensor head 211 reads a pattern 202 of the optical scale 201 and outputs an A-phase signal S1a and a B-phase signal S1b. The sensor head 212 is arranged to face the sensor head 211 across a rotation axial line O, so as to read the pattern 202 of the optical scale 201 and to output an A-phase signal S2a and a B-phase signal S2b. The phases of the A-phase signal S1a and the A-phase signal S2a are allowed to mutually differ by 180 degrees by the pattern 202 and arrangement relation between the sensor head 211 and the sensor head 212, and also the phases of the B-phase signal S1b and the B-phase signal S2b are allowed to mutually differ by 180 degrees.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rotary encoder.

  Generally, a rotary encoder is used to control industrial equipment such as a robot and a laser processing machine. For example, robots and laser processing machines have a motor, and a rotary encoder is used for position control of the motor. The rotary encoder is also applied to a torque sensor.

  In general, a rotary encoder has a rotary disk and a sensor head arranged to face the rotary disk, and a periodic signal corresponding to the rotational position of the rotary disk is output from the sensor head. If the relative position of the rotary disk with respect to the sensor head is deviated, that is, if the rotary disk is decentered, accurate rotational position information can not be obtained. Patent Document 1 proposes a rotary encoder in which two sensor heads are disposed at positions facing each other 180 degrees, and the detection result of each sensor head is averaged to cancel the eccentricity component of the rotary disk.

Patent No. 4956217 gazette

  By the way, the power supply device is connected to the rotary encoder as well as to the industrial device on which the rotary encoder is mounted, and operates by receiving the supply of power from the power supply device. Therefore, lightning surges and electrical noise from other devices may enter the rotary encoder through the power supply device, and electrical noise may be superimposed on the periodic signal from the sensor head. In addition, electrical noise emitted from another device may be superimposed on the periodic signal propagating through the signal line. Therefore, there has been a problem that a large error resulting from the electrical noise occurs at the rotational position of the rotary disk determined based on the periodic signal.

  Then, an object of the present invention is to reduce a measurement error caused by electrical noise.

  The rotary encoder according to the present invention has a plurality of patterns periodically arranged at equal pitches, and a rotating portion that rotates about a rotation axis, and reads the pattern, and a first periodic signal and the first periodic signal A first sensor unit that outputs a second periodic signal that is 90 ° out of phase with the first sensor unit, and the first sensor unit is disposed to face the first sensor unit with the rotation axis interposed therebetween, and the pattern is read; And a second sensor unit that outputs a fourth periodic signal whose phase is different by 90 degrees with respect to the third periodic signal, wherein the plurality of patterns, the first sensor unit, and the second sensor unit The phase of the periodic signal is 180 degrees different from that of the third periodic signal, and the phase of the second periodic signal is 180 degrees different from that of the fourth periodic signal.

  According to the present invention, the measurement error caused by the electrical noise is reduced.

It is explanatory drawing of the rotary encoder which concerns on 1st Embodiment. It is a top view of the optical scale in a 1st embodiment. It is a Lissajous figure which shows the relationship of A-phase signal and B-phase signal in 1st Embodiment. It is a graph which shows the waveform of the encoder signal obtained from a sensor head in 1st Embodiment. (A) And (b) is a graph which shows the experimental result in 1st Embodiment. (A) And (b) is a graph which shows the experimental result in 1st Embodiment. (A) And (b) is a graph which shows the experimental result in 1st Embodiment. It is a graph which shows the waveform of the encoder signal obtained from a sensor head in a comparative example. (A) And (b) is a graph which shows the experimental result in a comparative example. (A) And (b) is a graph which shows the experimental result in a comparative example. (A) And (b) is a graph which shows the experimental result in a comparative example. (A) is a top view of the optical scale of a rotary encoder concerning a 2nd embodiment, and a sensor head. (B) is explanatory drawing which shows the arrangement | positioning relationship between the pattern group in 2nd Embodiment, and a sensor head. (A) is a top view of the optical scale of a rotary encoder concerning a 3rd embodiment, and a sensor head. (B) is explanatory drawing which shows the arrangement | positioning relationship between the pattern group in 3rd Embodiment, and a sensor head. It is a perspective view of the robot concerning a 4th embodiment. It is an explanatory view around one joint of a robot concerning a 5th embodiment. It is a perspective view of a torque sensor concerning a 5th embodiment. It is a schematic diagram of the laser processing machine concerning 6th Embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First Embodiment
FIG. 1 is an explanatory view of a rotary encoder 100 according to the first embodiment. The rotary encoder 100 is an incremental optical encoder. The rotary encoder 100 may be either transmissive or reflective, but is a reflective encoder in the first embodiment.

  The rotary encoder 100 includes an encoder main body 200 and a processing circuit 300 which is an example of a processing unit. The encoder main body 200 includes an optical scale 201 which is an example of a rotating unit, and a sensor head 211 which is a first sensor unit and a sensor head 212 which is a second sensor unit, which are disposed to face the optical scale 201. The sensor heads 211 and 212 and the processing circuit 300 are connected by signal lines L1 and L2.

  FIG. 2 is a plan view of the optical scale 201. FIG. The optical scale 201 is a disk-shaped member that rotates about the rotation axis O, and has a plurality of patterns 202 periodically arranged at equal pitches (angles about the rotation axis O) P. The plurality of patterns 202 are formed by patterning a member having a relatively high light reflectance, such as a chromium reflection film, on a member having a relatively low light reflectance (that is, absorbing or transmitting light), such as a glass substrate. It is configured. The plurality of patterns 202 radially extend in a radial direction R centered on the rotation axis O, and are arranged along a circumferential direction C centered on the rotation axis O. The radial direction R is a direction orthogonal to the direction in which the rotation axis O extends. The circumferential direction C is a direction orthogonal to the radial direction R and the direction in which the rotation axis O extends, and is a direction that rotates about the rotation axis O.

  As shown in FIG. 1, the sensor heads 211 and 212 and the processing circuit 300 are supplied with power by the power supply device 400 and operate. The power supply device 400 converts AC power supplied from a commercial power source or the like into DC power, and supplies power to the sensor heads 211 and 212 and the processing circuit 300.

  The sensor head 212 is disposed to face the sensor head 211 across the rotation axis O. The sensor head 211 is configured to include a light emitting unit 221 formed of, for example, a light emitting diode or a laser diode, and a light receiving unit 231 formed of, for example, a photodiode. The sensor head 212 has the same configuration as the sensor head 211, and includes, for example, a light emitting unit 222 configured by a light emitting diode or a laser diode, and a light receiving unit 232 configured by, for example, a photodiode. The light emitting units 221 and 222 of the sensor heads 211 and 212 emit light to the pattern 202. The respective light receiving portions 231 and 232 receive the reflected light of the pattern 202 and perform photoelectric conversion, and encoder signals S1a, S1b, S2a and S2b which are electric signals according to the reflected light amount (the intensity of light) are transmitted to the signal lines L1 and L2. It outputs to the processing circuit 300 via L2.

  That is, the sensor head 211 reads the pattern 202, and as an encoder signal, a sinusoidal A-phase signal (first periodic signal) S1a and a sinusoidal B-phase signal having a phase difference of 90 degrees with respect to the A-phase signal 2 period signal) S1 b is output. Similarly, the sensor head 212 reads the pattern 202, and as an encoder signal, a sinusoidal A-phase signal (third periodic signal) S2a and a sinusoidal B-phase signal having a phase difference of 90 degrees with respect to the A-phase signal S2a (Fourth period signal) S2b is output.

  The sensor head 211 advances or delays the phase according to the increase or decrease of the rotational position (rotational angle) of the optical scale 201, and outputs encoder signals S1a and S1b. Similarly, the sensor head 212 advances or delays the phase according to the increase or decrease of the rotational position (rotational angle) of the optical scale 201, and outputs encoder signals S2a and S2b. In the first embodiment, the sensor heads 211 and 212 output sinusoidal encoder signals S1a, S1b, S2a, and S2b in the same cycle as the pitch P of the optical scale 201.

  Each sensor head 211, 212 outputs a Z phase signal (not shown) at the origin position. The current position of the optical scale 201 can be measured by counting the wave numbers of the encoder signals S1a, S1b, S2a, and S2b from the Z-phase signal.

  The sensor head 211 and the sensor head 212 are arranged at 180 ° rotational symmetry with each other with respect to the rotation axis O.

Assuming that the pitch of the pattern 202 is P [rad] and the actual rotation angle of the optical scale 201 is θ _m [rad], the encoder signals S1a and S1b are expressed by the following equations (1) and (2).
S1a = cos (P × θ _m ) (1)
S1b = sin (P × θ _m ) (2)

The encoder signals S2a and S2b are expressed by the following equations (3) and (4).
S2a = cos (P × (θ _m + π)) (3)
S2b = sin (P × (θ _m + π)) (4)

  The processing circuit 300 includes A / D converters 311 and 312, which are an example of analog-to-digital conversion means, comparators 321 and 322, which is an example of binarization means, counters 331 and 332, which are an example of counting means, And an arithmetic circuit 350 which is an example of the means.

  The comparator 321 outputs a rectangular wave binarized signal obtained by binarizing the encoder signals S1a and S1b to the counter 331. The comparator 322 outputs a rectangular wave binarized signal obtained by binarizing the encoder signals S2a and S2b to the counter 332.

  The counter 331 counts up or down the wave number based on the input binarized signal, and outputs the count value, that is, the wave value to the arithmetic circuit 350. The counter 332 counts up or down the wave number based on the input binarized signal, and outputs the count value, that is, the wave value to the arithmetic circuit 350.

  The arithmetic circuit 350 is formed of, for example, a microcomputer, and includes a CPU, a ROM, a RAM, an I / O, and the like. Arithmetic circuit 350 obtains position information Count1 of angular resolution π / 2P as a rotation amount corresponding to the wave value (count value) received from counter 331. Further, the arithmetic circuit 350 obtains position information Count2 of angular resolution π / 2P as a rotation amount corresponding to the wave value (count value) received from the counter 332.

  On the other hand, the A / D converter 311 performs A / D conversion on the A-phase and B-phase signals S1a and S1b, and outputs the converted signals to the arithmetic circuit 350. Similarly, the A / D converter 312 A / D converts the A-phase and B-phase signals S2a and S2b, and outputs the result to the arithmetic circuit 350.

The arithmetic circuit 350 interpolates using the inverse tangent function according to the relational expressions shown in the following equations (5) to (7) with a high resolution of angular resolution π / 2 P or less, and the measurement angle of the optical scale 201 Determine θ.
θ ₁ = 1 / P × a tan 2 (S 1 b, S 1 a) + Count 1 (5)
θ ₂ = 1 / P × a tan 2 (S 2 b, S 2 a) + Count 2 (6)
θ = (θ ₁ + θ ₂ ) / 2 (7)

Here, a tan 2 (X, Y) is a function for obtaining the arctangent of four quadrants defined in “math. H” of C language which is a programming language, and takes a phase value of 0 to 2π [rad]. θ ₁ [rad] is a measurement angle (first rotation amount) of the optical scale 201 obtained from the sensor head 211. θ ₂ [rad] is a measurement angle (second rotation amount) of the optical scale 201 obtained from the sensor head 212. Arithmetic circuit 350, a counting processing described above, in the interpolation calculation processing, A-phase, B-phase signal S1a, and measuring the angle theta ₁ which is based on S 1 b, A-phase, B-phase signal S2a, based on S2b measured angle theta ₂ To determine the measurement angle θ which is the rotational position of the optical scale 201. As a result, the measurement angle θ at which the eccentricity of the optical scale 201 with respect to the sensor heads 211 and 212 is canceled is obtained.

By the way, the rotary encoder 100 is often mounted on various industrial devices disposed in a factory or the like. Therefore, electrical noise is superimposed on the encoder signals S1a, S1b, S2a, and S2b through the power supply device 400 or through space. The encoder signals S1a, S1b, S2a, and S2b are superimposed as the electrical noise N in phase with the encoder signals S1a, S1b, S2a, and S2b, and are expressed by the following equations.
S1a = cos (P × θ _m ) + N
S1b = sin (P × θ _m ) + N
S2a = cos (P × (θ _m + π)) + N
S2b = sin (P × (θ _m + π)) + N

Therefore, the measurement angle theta which is obtained from the encoder signal, so that the relative actual angle theta _m, with a measurement error. In the first embodiment, in the pattern 202 and the sensor heads 211 and 212, the A-phase signal S1a and the A-phase signal S2a have a phase difference of 180 degrees, and the B-phase signal S1b and the B phase signal S2b have a phase difference of 180 degrees. It is arranged as. In other words, the phases of the four encoder signals S1a, S1b, S2a, and S2b differ by 90 degrees.

  Specifically, the sensor head 211 and the sensor head 212 are disposed at positions rotationally symmetrical to each other by 180 degrees with respect to the rotation axis O, and the number of the patterns 202 disposed at equal pitches P is an odd number. Therefore, by setting the number of patterns 202 to an odd number, the relative position between the pattern 202 and the sensor head 212 is shifted by half the pitch P with respect to the relative position between the pattern 202 and the sensor head 211. That is, the signals output from the sensor heads 211 and 212 are shifted by a half cycle (180 degrees). The arrangement relationship between the pattern 202, the sensor head 211 and the sensor head 212 makes the A-phase signal S1a and the A-phase signal S2a different in phase by 180 degrees, and the B-phase signal S1b and the B-phase signal S2b mutually different. 180 degrees out of phase.

FIG. 3 is a Lissajous figure showing the relationship between the A-phase signal and the B-phase signal. The horizontal axis is the signal level of the A-phase signals S1a and S2a, and the vertical axis is the signal level of the B-phase signals S1b and S2b. If the electrical noise N is not superimposed on the encoder signals S1a, S1b, S2a and S2b, a circular Lissajous waveform shown by a broken line is obtained. Electrical noise N encoder signals S1a, S1b, S2a, if not superimposed on S2b, an A-phase signal S1a and the phase obtained by arctangent calculation of the B-phase signal S1b from the sensor head 211 and phi _10. Electrical noise N encoder signals S1a, S1b, S2a, if not superimposed on S2b, the resulting phase with arctangent calculation with the A-phase signal S2a and the B-phase signal S2b from the sensor head 212 and phi _20. The phase φ ₁₀ and the phase φ ₂₀ differ from each other by 180 degrees. In FIG. 3, the case where the phase φ ₁₀ is 135 degrees and the phase φ ₂₀ is 315 degrees (−45 degrees) is illustrated as an example.

When the electrical noise N is superimposed on each of the encoder signals S1a, S1b, S2a, and S2b, the circular Lissajous waveform deviates in the direction of 45 degrees as indicated by a solid line. At this time, the phase obtained by arctangent calculation of the phase obtained by arctangent calculation of the A-phase signal S1a and the B-phase signal S 1 b phi _1, A-phase signal S2a and the B-phase signal S2b and phi _2.

In the example of FIG. 3, the phase φ ₁ is smaller than the phase φ ₁₀ by the error Δφ ₁ due to the influence of the electrical noise N. On the other hand, phase φ ₂ becomes larger than phase φ ₂₀ by error Δφ ₂ due to the influence of electrical noise N.

In the first embodiment, as shown in the equation (7), the measurement angle θ is determined by averaging the _two measurement angles θ ₁ and θ _2, that is, adding and dividing by two. The error Δφ ₁ is subtracted from the error Δφ ₂ to cancel the fluctuation due to the electrical noise N. Therefore, the error of the measurement angle θ caused by the electrical noise N can be reduced, and the accuracy of the measurement angle θ can be improved.

  The phase difference between the A-phase signal S1a and the A-phase signal S2a and the phase difference between the B-phase signal S1b and the B-phase signal S2b are 180 degrees, but they include a tolerance of ± 10 degrees. That is, the phase difference of 180 degrees means (180 ± 10) degrees including the allowable range.

  In the first embodiment, the sensor heads 211 and 212 output sinusoidal encoder signals S1a, S1b, S2a, and S2b at the same cycle as the pitch P. Therefore, the relative position between the pattern 202 and the sensor head 212 is shifted by half the pitch P with respect to the relative position between the pattern 202 and the sensor head 211. Specifically, the number of patterns 202 is an odd number, and the sensor heads 211 and 212 are disposed at positions rotationally symmetric by 180 degrees with respect to the rotation axis O. As described above, the encoder signals can be made to differ in phase by 90 degrees with a simple configuration in which the pattern 202 is shifted, specifically, the number of the patterns 202 is odd.

  Hereinafter, an experimental result in which the measurement angle θ is obtained by the configuration of the rotary encoder 100 in the first embodiment and an experimental result in which the measurement angle θ is obtained by the configuration of the rotary encoder of the comparative example will be described.

  First, as a first embodiment, the results of experiments conducted in the case where the number of patterns 202 is “99” will be described. FIG. 4 is a graph showing the waveforms of encoder signals S1a, S1b, S2a, S2b obtained from the sensor head. FIG. 4 illustrates the waveforms of the encoder signals S1a, S1b, S2a, and S2b when the electrical noise N is superimposed when the angle of the optical scale 201 is 0.3 degrees. When the amplitudes (voltages) of the encoder signals S1a, S1b, S2a, and S2b are normalized to “1”, the electrical noise N (voltage) to be superimposed is “0.1”. In the first embodiment, the A-phase signal S1a and the A-phase signal S2a are 180 degrees out of phase with each other, and the B-phase signal S1b and the B phase signal S2b are 180 degrees out of phase with each other.

Hereinafter, the experimental results in the first embodiment, the measurement angle theta ₁ with respect to the rotation angle theta _m of the optical scale 201, theta _2, the error of _{θ θ 1err, θ 2err, θ} err will be described. Here, θ _1err = θ ₁ -θ _m , θ _2err = θ ₂ -θ _m , and θ _err = θ-θ _m .

5 (a), 5 (b), 6 (a), 6 (b), 7 (a) and 7 (b) are graphs showing experimental results in the first embodiment. The horizontal axes shown in FIGS. 5 (a), 5 (b), 6 (a), 6 (b), 7 (a) and 7 (b) represent the rotation angle θ _m of the optical scale 201. Yes, the range of 0 to 2π is illustrated. 5 (b), 6 (b) and 7 (b) are a part of the horizontal axis in FIGS. 5 (a), 6 (a) and 7 (a) (0 to 2π of the rotation angle θ _m / 50) is enlarged. As shown in FIGS. 5 (b) and 6 (b), it can be _seen that the error θ _1err and the error θ _2err have substantially the same magnitude and have an angle error with the sign reversed. Therefore, by averaging (addition), the two errors θ _1err and θ _2err cancel each other. Therefore, as shown in FIGS. 7A and 7B, the maximum value of the error θ _err decreases to 1.0 × 10 ⁻⁴ [rad].

  As a comparative example, the results of experiments conducted when the number of patterns is “100” will be described. FIG. 8 is a graph showing the waveform of an encoder signal obtained from the sensor head in the comparative example. FIG. 8 illustrates the waveform of the encoder signal when the electrical noise N is superimposed when the angle of the optical scale is 0.3 degrees. When the amplitudes (voltages) of the encoder signals S1a, S1b, S2a, and S2b are normalized to “1”, the electrical noise N (voltage) to be superimposed is “0.1”. In the comparative example, the A-phase signal S1a and the A-phase signal S2a are in the same phase, and the B-phase signal S1b and the B-phase signal S2b are in the same phase.

Hereinafter, the experimental results of the comparative example, the measurement angle theta ₁ with respect to the rotation angle theta _m of the optical scale 201, theta _2, the error of _{θ θ 1err, θ 2err, θ} err will be described.

FIGS. 9 (a), 9 (b), 10 (a), 10 (b), 11 (a) and 11 (b) are graphs showing experimental results of comparative examples. The horizontal axes shown in FIGS. 9 (a), 9 (b), 10 (a), 10 (b), 11 (a) and 11 (b) represent the rotation angle θ _m of the optical scale. , 0 to 2π are illustrated. 9 (b), 10 (b) and 11 (b) are a part of the horizontal axes of FIGS. 9 (a), 10 (a) and 11 (a) (0 to 2π of the rotation angle θ _m / 50) is enlarged.

As shown in FIGS. 9B and 10B, it can be seen that the error θ _1err and the error θ _2err have substantially the same magnitude and have the same sign angular error. As shown in FIGS. 11A and 11B, the maximum value of the error θ _err is approximately 1.5 × 10 ⁻³ [rad]. From the above experimental results, according to the first embodiment, the error θ _err of the measurement angle θ can be made smaller than that of the comparative example.

Second Embodiment
The rotary encoder according to the second embodiment will be described. FIG. 12A is a plan view of an optical scale and a sensor head of a rotary encoder 100A according to the second embodiment. The rotary encoder 100A includes, as an encoder main body, an optical scale 201A, which is an example of a rotating unit, and sensor heads 211A and 212A, which is an example of a sensor unit. The sensor heads 211A and 212A have substantially the same configuration as the sensor heads 211 and 212 described in the first embodiment, and have a light emitting unit and a light receiving unit substantially the same as the first embodiment. Although not shown, the rotary encoder 100A has a processing circuit 300 having substantially the same configuration as that of the first embodiment.

  In the second embodiment, the movable range of the optical scale 201A is less than 360 degrees, for example, ± 10 degrees at an angle about the rotation axis O. Therefore, the pattern is omitted outside the movable range of the optical scale 201A.

  The optical scale 201A includes a rotating member 210A that rotates about the rotation axis O, a pattern group (scale piece) 206A that is a first pattern group formed on the rotating member 210A, and a pattern group that is a second pattern group ( Scale piece) 207A.

  FIG. 12B is an explanatory view showing the arrangement of the pattern groups 206A and 207A and the sensor heads 211A and 212A in the second embodiment. The pattern group 206A is a reading target of the sensor head 211A, and is arranged to face the sensor head 211A. The pattern group 207A is a reading target of the sensor head 212A, and is disposed to face the sensor head 212A. Each pattern group 206A, 207A has a plurality of patterns 202A, 203A periodically arranged at an equal pitch λ.

  The patterns 202A of the pattern group 206A are arranged at equal intervals at a pitch λ in a linear direction X orthogonal to a radial direction R centered on the rotation axis O. Similarly, the patterns 203A of the pattern group 207A are arranged at equal intervals at a pitch λ in a linear direction X orthogonal to the extending direction of the rotation axis O and orthogonal to the radial direction R centered on the rotation axis O . Since the movable range of the optical scale 201A is narrow by ± 10 degrees, the plurality of patterns 202A and 203A can be regarded as being arranged in the circumferential direction even if arranged in parallel in the easy linear direction X of manufacture. Of course, the plurality of patterns 202A and 203A may be arranged in the circumferential direction orthogonal to the radial direction R.

  In the second embodiment, each of the sensor heads 211A and 212A uses sinusoidal diffraction encoder signals S1a and S1b at a period finer than the pitch λ, specifically at a half period of the pitch λ by using diffraction interference of light. , S2a, S2b. In the rotary encoder 100A, minute angular displacement can be measured with high accuracy by using diffraction interference of light.

  In the second embodiment, the sensor head 211 </ b> A and the sensor head 212 </ b> A are disposed at positions rotationally symmetrical to each other by 180 degrees with respect to the rotation axis O. Then, the pattern group 207A is arranged to be shifted in the linear direction X with respect to the position where the pattern group 206A is rotated 180 degrees around the rotation axis O. As a result, the relative position of the sensor head 212A with respect to the pattern group 207A deviates in the linear direction X with respect to the relative position of the sensor head 211A with respect to the pattern group 206A.

Here, in the second embodiment, each sensor head 211A, 212A outputs sinusoidal encoder signals S1a, S1b, S2a, S2b at a period of half the pitch λ. That is, in the encoder signals S1a, S1b, S2a, and S2b, the pattern group 207A is only 1/4 the pitch λ in the linear direction X with respect to the 180 ° rotational symmetric position of the pattern group 206A so that the phases are shifted by 90 degrees. It is offset. As described above, by arranging the pattern group 207A by a quarter cycle of the pitch λ, the A-phase signals S1a and S2a (B-phase signals S1b and S2b) obtained from the two sensor heads 211A and 212A are mutually different. The 180 degree phase can be made different. As a result, as in the first embodiment, the errors between the two encoder signals on which the electrical noise N is superimposed cancel each other, and the error θ _err of the obtained measurement angle θ can be reduced.

Third Embodiment
The rotary encoder according to the third embodiment will be described. FIG. 13A is a plan view of an optical scale and a sensor head of a rotary encoder 100B according to a third embodiment. The rotary encoder 100B includes, as an encoder main body, an optical scale 201A, which is an example of a rotating unit, and sensor heads 211A and 212A, which is an example of a sensor unit, as in the second embodiment described above. Although not shown, the rotary encoder 100B has a processing circuit 300 having the same configuration as that of the first embodiment.

  FIG. 13B is an explanatory view showing the arrangement of the pattern groups 206A and 207A and the sensor heads 211A and 212A in the third embodiment. In the third embodiment, the pattern group 206A and the pattern group 207A are arranged at positions rotationally symmetrical by 180 degrees with respect to the rotation axis O. Then, the sensor head 212A is disposed so as to be displaced in the linear direction X with respect to the position where the sensor head 211A is rotated 180 degrees around the rotation axis O. As a result, the relative position of the sensor head 212A with respect to the pattern group 207A deviates in the linear direction X with respect to the relative position of the sensor head 211A with respect to the pattern group 206A.

  Also in the third embodiment, each sensor head 211A, 212A outputs sinusoidal encoder signals S1a, S1b, S2a, S2b at a period of half the pitch λ. That is, the sensor head 212A is displaced by a quarter of the pitch λ in the linear direction X with respect to the 180 ° rotational symmetric position of the sensor head 211A so that the encoder signals S1a, S1b, S2a, S2b are out of phase by 90 degrees. Only shifted.

As described above, by arranging the sensor heads 212A by a quarter cycle of the pitch λ, the A-phase signals S1a and S2a (B-phase signals S1b and S2b) obtained from the two sensor heads 211A and 212A are mutually different. The 180 degree phase can be made different. As a result, as in the first embodiment, the errors between the two encoder signals on which the electrical noise N is superimposed cancel each other, and the error θ _err of the obtained measurement angle θ can be reduced.

Fourth Embodiment
The robot which is an example of the industrial equipment concerning a 4th embodiment is explained. In the fourth embodiment, the case where the rotary encoder described in the above-described first embodiment is mounted on a robot will be described. FIG. 14 is a perspective view of a robot 500 according to the fourth embodiment.

  As shown in FIG. 14, the robot 500 is a vertical articulated robot, and includes a robot body 600 that is a manipulator, and a robot control device 650 that controls the operation of the robot body 600.

  The robot main body 600 includes a robot arm 601 and a robot hand 602 which is an example of an end effector attached to the tip of the robot arm 601. The proximal end of the robot arm 601 is fixed to a pedestal. The robot hand 602 grips a workpiece W such as a part or a tool.

Robot arm 601 has a plurality of links ₆₁₀ 0-610 ₆ which is rotatably connected at each joint _J 1 through J _6. In the fourth embodiment, the direction from the proximal side to the distal side, the link 610 _{0-610 6} are sequentially connected in series. The robot arm 601 can direct the tip (robot hand 602) of the robot arm 601 to any three-dimensional posture at any three-dimensional position within the movable range.

The robot arm 601 has a joint _{J i} disposed a drive device 700 _i (i is an integer of 1 to 6). A link _{610 i-1} is the first link of the robotic arm 601, the link 610 _i is the second link is rotatably articulated _{J i.} The drive 700 _i comprises a motor 710 _i having a rotation axis 711 _i . Link 610 _i are rotated relative to the link _{610 i-1} by the driving force of the motor 710 _i. The drive device 700 _i is arranged to measure the rotational position of the rotary shaft 711 _i of the motor 710 _i, and outputs a signal indicative of the rotational position, the same configuration as the rotary encoder 100 described in the first embodiment having a rotary encoder 100 _i. The drive device 700 _i includes a motor driver 750 _i is a drive controller for feedback controlling the motor 710 _i acquires the signal indicating the rotational position of the rotary encoder 100 _i.

A plurality of motor drivers ₇₅₀ 1 to 750 ₆ is, can receive the position command of the rotational position from the robot controller 650 is connected to a wiring to the robot controller 650. Each motor driver 750 _i performs feedback control (position control) on the motor 710 _i such that the rotational position approaches the position command. Measurement error in each rotary encoder 100 _i is reduced, because the measurement accuracy is improved, it is possible to realize highly accurate position control of the robot arm 601.

Fifth Embodiment
The robot which is an example of the industrial equipment concerning a 5th embodiment is explained. Figure 15 is an explanatory view around one joint J _i of the robot according to the fifth embodiment. i is an integer of 1 to 6, as in the fourth embodiment. In the fifth embodiment, the driving device 700 _i includes a motor 710 _i, a motor driver 750 _i and the torque sensor 800 _i. A link _{610 i-1} is the first link and the link 610 _i is a second link, is articulated _{J i} via the motor 710 _i and the torque sensor 800 _i of the drive unit 700 _i. Link 610 _i are relatively rotated by the driving force of the motor 710 _i for the link _{610 i-1.} The torque sensor 800 _i acts on link 610 _i for the link _{610 i-1,} a signal corresponding to the torque around the rotation axis of O, outputs to the motor driver 750 _i. The motor driver 750 _i, based on the torque value and controls the motor 710 _i.

FIG. 16 is a perspective view of the torque sensor 800 _i according to the fifth embodiment. The torque sensor 800 _i has a rotary encoder 100C _i having the same configuration as the rotary encoder 100A or 100B described in the second or third embodiment. The torque sensor 800 _i includes, for example, a link _{610 i-1} support section is a first support portion fixed to the side 804, and a support portion 805 is a second support portion fixed for example to the link 610 _i side Have. The support portions 804 and 805 are flat members, and the support portions 804 and the support portions 805 are arranged at intervals so as to face each other in the direction in which the rotation axis O extends. The support portions 804 and 805 are relatively displaceable in the circumferential direction about the rotation axis O.

The support portion 804 and the support portion 805 are connected by an elastic portion 803. The elastic portion 803 is configured to have a plate spring 806 which is a plurality of elastic members extending radially around the rotation axis O. The plurality of leaf springs 806 are spaced apart from one another in the circumferential direction around the rotation axis O. Between the link 610 _i-1 and the link 610 _i, i.e. the support portion 804 when the torque around the rotation axis O between the supporting portion 805 is exerted, the support portion 804 by the rotation amount corresponding to the magnitude of the torque exerted The support portion 805 is relatively rotationally displaced about the rotation axis O.

Pattern group 206A and pattern groups 207A of the rotary encoder 100C _i, one of the support portions 504 and 505, and is fixed for example to the supporting portion 804. The sensor head 211A and the sensor head 212A of the rotary encoder 100C _i are fixed to the other of the support portions 804 and 805, for example, the support portion 805.

Since the measurement error in the rotary encoder 100C _i becomes smaller and the measurement accuracy is improved, the robot can measure the torque with high accuracy.

Sixth Embodiment
The laser processing machine which is an example of the industrial equipment concerning a 6th embodiment is explained. FIG. 17 is a schematic view of a laser beam machine 900 according to the sixth embodiment. The laser processing machine 900 has a laser light source 901, a biaxial galvano scanner 902, and an fθ lens 903. The two-axis galvano scanner 902 has two drive devices 700X and 700Y.

The driving device 700X outputs a signal indicating the rotational position of the rotation shaft 711X of the motor 710X and the motor 710X, and the rotary encoder 100X having the same configuration as the rotary encoder 100A or 100B described in the second or third embodiment. Have. Furthermore, the driving device 700X includes a motor driver 750X of the same structure as the motor driver 750 _i described in the fourth embodiment.

Similarly, the drive device 700Y outputs a signal indicating the rotational position of the motor 710Y and the rotational shaft 711Y of the motor 710Y. The rotary encoder has the same configuration as that of the rotary encoder 100A or 100B described in the second or third embodiment. And 100Y. Furthermore, the driving device 700Y includes a motor driver 750Y having the same configuration as the motor driver 750 _i described in the fourth embodiment.

  Further, the two-axis galvano scanner 902 has two mirrors 910X and 910Y that reflect the laser light L emitted from the laser light source 901 and rotate by the driving force of the motors 710X and 710Y. The laser light L emitted from the laser light source 901 is reflected by the mirrors 910X and 910Y, passes through the fθ lens 903 and is irradiated onto the surface of the object to be processed.

  An object to be processed by the laser processing machine 900 is, for example, a printed wiring board B, and the laser processing machine 900 forms a via or the like on the substrate to be the printed wiring board B with the laser light L. The manufactured printed wiring board B is mounted on portable electronic devices such as digital cameras, mobile phones, and smartphones. The printed wiring board B has been downsized and densified, and in drilling processing, the demand for smaller diameter and higher precision has been increasing. Therefore, it is necessary to position the motors 710X and 710Y mounted on the laser processing machine 900 with high accuracy.

  Also in the sixth embodiment, even if the electrical noise is superimposed on the encoder signal, the measurement error of each of the rotary encoders 100X and 100Y can be reduced. As a result, the mirrors 910X and 910Y can be positioned with high accuracy, and the accuracy of drilling can be improved.

  The present invention is not limited to the embodiments described above, and many modifications can be made within the technical concept of the present invention. In addition, the effects described in the embodiment only list the most preferable effects arising from the present invention, and the effects according to the present invention are not limited to those described in the embodiment.

  In the first to sixth embodiments described above, the optical rotary encoder has been described. However, the present invention is not limited to the optical rotary encoder. For example, the present invention is applicable to a magnetic rotary encoder.

  Further, in the first embodiment described above, the sensor head 211 and the sensor head 212 are arranged at positions rotationally symmetrical 180 degrees with respect to the rotation axis O, and the number of the plurality of patterns 202 is an odd number. Although explained, it does not limit to this. The number of the plurality of patterns 202 may be an even number, and the sensor head 212 may be circumferentially shifted by half the pitch P with respect to the position where the sensor head 211 is rotated 180 degrees about the rotation axis O. Or, since the pitch P is an angle, the sensor in the linear direction orthogonal to the extending direction of the rotation axis O and the radial direction R, as in the third embodiment, by a half of the distance (angle × radius) corresponding to the pitch P The head 212 may be shifted. Thus, the relative position of the sensor head 212 with respect to the pattern 202 may be shifted in the circumferential direction or in the linear direction with respect to the relative position of the sensor head 211 with respect to the pattern 202 by displacing the sensor head 212 .

  In the second embodiment described above, the pattern group 207A has been described, and in the third embodiment described above, the sensor head 212 is displaced in the linear direction X. However, a circle centered on the rotation axis O It may be the case where it is arranged by being shifted in the circumferential direction. Thus, by shifting the pattern group 207A or the sensor head 212 in the circumferential direction, the relative position of the sensor head 212 to the pattern group 207 with respect to the relative position of the sensor head 211 to the pattern group 206 is a circle. It may be shifted in the circumferential direction.

DESCRIPTION OF SYMBOLS 100 ... Rotary encoder, 201 ... Optical scale (rotary part), 202 ... Pattern, 211 ... Sensor head (1st sensor part), 212 ... Sensor head (2nd sensor part), 300 ... Processing circuit (process part), 500 ... Robot, 900 ... laser processing machine, O ... rotation axis, P ... pitch

Claims (13)

A rotating unit having a plurality of patterns periodically arranged at equal pitches and rotating around a rotation axis;
A first sensor unit that reads the pattern and outputs a first periodic signal and a second periodic signal that is 90 degrees out of phase with the first periodic signal;
A fourth periodic signal disposed so as to face the first sensor unit with the rotation axis interposed therebetween, reading the pattern, and outputting a third periodic signal and a fourth periodic signal different in phase by 90 degrees with respect to the third periodic signal 2 sensor unit, and
The plurality of patterns, the first sensor unit, and the second sensor unit have a phase difference of 180 degrees between the first periodic signal and the third periodic signal, and the second periodic signal is the fourth periodic signal. A rotary encoder characterized in that the phase is arranged to differ by 180 degrees with respect to.   Providing a processing unit for obtaining a rotational position of the rotating unit by averaging a first rotation amount based on the first and second periodic signals and a second rotation amount based on the third and fourth periodic signals The rotary encoder according to claim 1, characterized in that: The plurality of patterns extend radially in a radial direction about the axis of rotation, and are arranged circumferentially about the axis of rotation,
With respect to the relative position of the first sensor unit with respect to the pattern, the relative position of the second sensor unit with respect to the pattern is deviated in the linear direction orthogonal to the circumferential direction or the radial direction. The rotary encoder according to claim 1, characterized in that: The first sensor unit and the second sensor unit are disposed at positions rotationally symmetric by 180 degrees with respect to the rotation axis,
The rotary encoder according to claim 3, wherein the number of the plurality of patterns is an odd number. The movable range of the rotating part is less than 360 degrees,
The plurality of patterns include a first pattern group to be read by the first sensor unit and a second pattern group to be read by the second sensor unit.
With respect to the relative position of the first sensor unit with respect to the first pattern group, the relative position of the second sensor unit with respect to the second pattern group is a circumferential direction centered on the rotation axis or The rotary encoder according to claim 1 or 2, wherein the rotary encoder is offset in a linear direction orthogonal to a radial direction centering on the rotation axis. The first sensor unit and the second sensor unit are disposed at positions rotationally symmetric by 180 degrees with respect to the rotation axis,
The second pattern group is disposed so as to be deviated in the circumferential direction or in the linear direction with respect to a position obtained by rotating the first pattern group by 180 degrees with respect to the rotation axis. The rotary encoder according to Item 5. The first pattern group and the second pattern group are disposed at positions rotationally symmetric by 180 degrees with respect to the rotation axis,
The second sensor unit is disposed so as to be displaced in the circumferential direction or the linear direction with respect to a position obtained by rotating the first sensor unit by 180 degrees with respect to the rotation axis. The rotary encoder according to Item 5.   The rotary encoder according to any one of claims 1 to 7, wherein each of the first sensor unit and the second sensor unit has a light emitting unit and a light receiving unit. A rotary encoder according to any one of claims 1 to 8,
And a motor having a rotating shaft,
The rotary encoder outputs a signal indicating a rotational position of the rotary shaft. A rotary encoder according to any one of claims 1 to 8;
A first support portion and a second support portion relatively displaceable about the rotation axis;
An elastic portion connecting the first support portion and the second support portion;
The torque sensor characterized in that the rotating portion is supported by the first support portion, and the first sensor portion and the second sensor portion are supported by the second support portion. A driving device according to claim 9;
With the first link,
A second link connected to the first link by a joint and rotated by a driving force of the motor. A torque sensor according to claim 10;
With the first link,
A second link connected to the first link via the torque sensor. A driving device according to claim 9;
Laser light source,
The laser processing machine provided with the mirror which reflects the laser beam radiate | emitted from the said laser light source, and is rotated by the driving force of the said motor.

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