WO2019039344A1

WO2019039344A1 - Encoder

Info

Publication number: WO2019039344A1
Application number: PCT/JP2018/030237
Authority: WO
Inventors: 渡部　司
Original assignee: 国立研究開発法人産業技術総合研究所
Priority date: 2017-08-22
Filing date: 2018-08-13
Publication date: 2019-02-28
Also published as: CN110785633A; JPWO2019039344A1; JP6845517B2; CN110785633B

Abstract

An encoder 10 is provided with: M sensors 31 to 34 which detect a plurality of elements indicating angles disposed at prescribed angle intervals on a substrate, generate first signals having periodicity, and are disposed at prescribed angles, wherein the prescribed angle is an angle obtained by combining 360/M×(j-1) (degrees) and 360/N×MOD[(kj-1)/D] (degrees), where M is an integer equal to or greater than 2, N is an element number, MOD is a function for outputting the value of the decimal places of an input value, D is M or a divisor of M, excluding 1, j is an integer from 1 to M having a different value for each of the M sensors, and kj is an integer from 1 to M; generators 41 to 44 which generate second signals interpolating the prescribed angle intervals on the basis of the first signals, for each of the M sensors; and a calculator 50 which adds together the second signals relating to the M sensors to obtain an angular position or an angle of rotation.

Description

Encoder

The present invention relates to an encoder for detecting position and angle.

The encoder is a device that reads a scale of equal angular intervals written on a scale plate to measure a position such as a rotational angle or an absolute angular position. Since the interval of the scale is naturally limited by the accuracy of writing and the accuracy of the sensor that detects the scale, there is a limit to the improvement of the resolution by the scale. Therefore, two analog signals are generated by shifting the sine wave further dividing the minimum scale interval by 90 degrees from each other, and arctan calculation of the two analog signals is performed to determine the angle using the interpolation signal representing the angle To improve resolution.

In addition, in order to reduce writing errors on the scale, mounting errors of the encoder, and the like, a method of arranging a plurality of sensors and averaging the interpolation signals obtained from the respective sensors is used. Further, a method has been proposed in which a sensor for calibration is further provided to perform self-calibration of the angular error (for example, see Patent Document 1).

JP 2011-99804 A

An object of the present invention is to provide a new and useful encoder that is compatible with high resolution and high accuracy.

According to an aspect of the present invention, there are provided M sensors for detecting a plurality of elements indicating angles arranged at predetermined angular intervals on a substrate to generate a first signal having periodicity. The sensor is disposed at a predetermined angle, and the predetermined angle is an angle combining 360 / M × (j−1) (degrees) and 360 / N × MOD [(k _j −1) / D]. Here, M is an integer of 2 or more, N is the number of elements, MOD is a function that outputs the decimal value of the input value, D is a divisor of M or M except for 1 , J is an integer from 1 to M and takes different values for M sensors, and k _j is an integer from 1 to M, and for each of the M sensors and the M sensors A generator generating a second signal that interpolates the predetermined angular interval based on the first signal; An arithmetic unit that adds the second signal to the sensor to obtain an angular position or a rotational angle.

According to the above aspect, the M sensors are 360 / M × (j−1) (degrees) and 360 / N × MOD [for a substrate on which a plurality of elements indicating angles at predetermined angular intervals are arranged. (K _j -1) / D] (degrees) is arranged to interpolate the predetermined angular interval generated based on the first signal generated by the sensor The angular error of the encoder due to the angular error of the second signal can be reduced, as well as the error due to eccentricity due to the attachment of the substrate to the rotational axis and the error due to the formation position of multiple elements arranged at equal angular intervals The angular error of the encoder can also be reduced, and as a result, an encoder having both high resolution and high accuracy can be provided.

According to another aspect of the present invention, there are provided M sensors for detecting a plurality of elements indicating positions arranged at predetermined intervals on a substrate to generate a first signal having periodicity. Sensors are spaced apart from each other by a predetermined distance, and the predetermined distance is an integer (m _j ) times the predetermined interval (gl), gl × m _j and gl × MOD [(k _j −1) Position where M is an integer greater than or equal to 2, MOD is a function that outputs the decimal value of the input value, and D is a divisor of M or M, 1 is excluded, k _j is an integer from 1 to M, and for each of the M sensors and the M sensors, the elements at the predetermined intervals are interpolated based on the first signal. A generator that generates a second signal to be generated, and the second signal for the M Or an arithmetic unit for determining a movement amount.

According to the above aspect, with respect to a base on which a plurality of elements indicating positions are disposed at predetermined intervals, M sensors are integers (m _j ) times the predetermined interval (gl) and gl × m _j By arranging at a position in combination with gl × MOD [(k _j −1) / D], the second predetermined interval which is generated based on the first signal generated by the sensor is interpolated. The position error of the encoder due to the position error of the signal can be reduced, and at the same time the position error due to the attachment of the substrate to the object and the error of the encoder due to the errors of formation positions of plural elements arranged at predetermined intervals As a result, an encoder having both high resolution and high accuracy can be provided.

It is a figure which shows the angle error of a rotary encoder. FIG. 2 illustrates discrete Fourier transform (DFT) analysis of the angular error shown in FIG. 1 of a rotary encoder. FIG. 5 shows the angular error of the interpolated signal contained in FIG. 1 of the rotary encoder. FIG. 1 is a diagram showing a schematic configuration of an encoder according to a first embodiment of the present invention. It is a figure which shows the arrangement | positioning position of the sensor of the encoder which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the arrangement | positioning position of each sensor in the 1st Embodiment of this invention. It is a figure which shows the angle error of the interpolation signal of the encoder which concerns on the 1st Embodiment of this invention. It is a figure which shows the angle error of the encoder which concerns on the 1st Embodiment of this invention. It is a figure which shows the DFT analysis of the angle error of the encoder which concerns on the 1st Embodiment of this invention. It is a figure which shows schematic structure of the encoder which concerns on the 2nd Embodiment of this invention. It is a figure which shows an example of the arrangement | positioning position of each sensor in the 2nd Embodiment of this invention.

The inventor of the present invention has been researching to achieve high resolution and high accuracy of a rotary encoder, and has encountered a problem described below and found a solution.

In the rotary encoder, the sensor reads a graduated dial with a scale of 360 degrees, generates sine waves and cosine waves based on the scale, and generates a signal to interpolate between the scales (hereinafter referred to as interpolation). Called a signal). Then, an angle signal is generated based on the interpolation signal, and the current angle or rotation angle is detected from the angle signal. If multiple sensors are provided, the angle signal from each sensor is averaged to determine the angle. The interpolated signal is used to detect an angle smaller than the minimum scale, that is, to improve resolution.

The rotary encoder arranges a plurality of sensors at equal angular intervals with respect to the dial plate, and averages a plurality of output angle signals, so that the eccentricity error of the rotary encoder or the error of the angular position of each scale of the dial plate Reduce etc. However, when the angle error of the rotary encoder is examined, the angle error still remains, which may become an obstacle to high precision. The inventor examined the angular error of a rotary encoder in which four sensors were arranged at equal angular intervals of 90 degrees. The number of graduations N of the graduation plate is 360, that is, it is attached at equal intervals every other degree, and is multiplied by 32 by the interpolation signal. Each of the four sensors detects a signal including an angular error generated by the basic scale and the interpolation division as the dial plate rotates.

FIG. 1 is a diagram showing an angle error of a rotary encoder, which is an angle error obtained by averaging angle signals from four sensors. Referring to FIG. 1, it can be seen that the angular error is up to ± 30 seconds over 360 degrees (one round).

FIG. 2 shows a discrete Fourier transform (DFT) analysis of the angular error shown in FIG. 1 of the rotary encoder.

Referring to FIG. 2, it can be seen that the low order component is small and is effective in reducing eccentricity errors and scale angular errors. However, it can be seen that the angular errors of the 360, 720, 1080, 1440 and 1800 order components are large, on the order of 2 seconds to 11 seconds. These angular error components have a division number N of 360 for the sensor number M of 4, and the sensor number M is a divisor of the division number of 360. Therefore, the angular error of the next multiple of the division number is an interpolation signal This occurs as an angular error of For example, since the number of sensors is a divisor of the number of graduations 360 even if the number of sensors is not four but three, five, or six, an angle error of the interpolation signal will occur similarly.

As a method of reducing such an angular error of the interpolation signal, the number of sensors may be seven or thirteen and arranged at equal angular intervals. Since 7 is not a divisor of the number of graduations 360, the angular error of the interpolation signal can be reduced.

FIG. 3 is a diagram showing an angular error of an interpolation signal included in FIG. 1 of the rotary encoder for each sensor. FIG. 3 shows only the angular error of the interpolation signal among the angular errors, and is shown for each sensor, the horizontal axis is the angle (degrees), and the vertical axis is the angle error (seconds), and black The triangle (▲) position indicates the position of the scale on the dial.

Referring to FIG. 3, it can be seen that the waveforms of the angular errors of the sensors 1 to 4 are almost the same, and the phases are also substantially the same. From this, even if the angle signals of the sensor 1 to the sensor 4 are averaged, the angle errors of the sensor 1 to the sensor 4 do not mutually cancel each other, and as shown in FIG. It will

Therefore, an object of the present invention is to provide an encoder having both high resolution and high accuracy, in which the angular error of the interpolation signal is reduced by mutually shifting the positions of a plurality of sensors with respect to the graduation of the graduation plate. It is to be.

Hereinafter, an embodiment of the present invention will be described based on the drawings. Note that elements common to multiple drawings are given the same reference numerals, and repeated description of the elements is omitted.

First Embodiment
FIG. 4 is a diagram showing a schematic configuration of an encoder according to the first embodiment of the present invention.

Referring to FIG. 4, the encoder 10 according to the first embodiment is disposed on a rotation shaft 15 which is an object of angle measurement, and has a scale plate 20 having graduations 21 formed at equal intervals in the circumferential direction; The scale 21 is detected, and based on the detection, four sensors 31 to 34 that generate detection signals of sinusoidal waves that are 90 degrees out of phase with each other having a periodicity, and the scale based on the detection signals for each sensor 31 to 34 Interpolation signal generators 41 to 44 that generate interpolation signals (also referred to as angle signals) that interpolate the interval between the two, and add the interpolation signals for each of the sensors 31 to 34 based on the interpolation signals to obtain an angular position Or an arithmetic unit 50 for determining the rotation angle.

The scale plate 20 is attached to be concentric with the rotating shaft 15, and the scales 21 are provided at equal intervals in the circumferential direction, so that the portion of the scale 21 transmits light.

The sensors 31 to 34 each have a light emitting element 35, a slit 36, and a light receiving element 37. In FIG. 4, the sensors 32 to 34 are described with details of the components omitted, but have the same components as the sensor 31. In the sensors 31 to 34, the scale 21 transmits the light from the light emitting element 35, and the light receiving element 37 receives the light through the slit 36. The sensors 31 to 34 generate sine wave electrical signals that are 90 degrees out of phase with each other according to the intensity of light received by the light receiving element 37, and output the signals as detection signals. For example, one of the two sine wave electrical signals that are 90 degrees out of phase with each other is a Sin voltage signal, and the other is a Cos voltage signal.

The interpolation signal generators 41 to 44, the input portions of which are electrically connected to the output portions of the sensors 31 to 34, generate interpolation signals based on the input detection signals. Specifically, an interpolation signal is generated by obtaining an angle from the Sin voltage signal of the detection signal and the arctan of the Cos voltage signal (voltage value of Sin voltage signal / voltage value of Cos voltage signal). The interpolation signal is a digital signal. The interpolation signal is a signal obtained by dividing a scale interval at equal intervals, and is, for example, a signal of several tens of multiplication to several hundreds of multiplication.

The computing unit 50 is electrically connected to the outputs of the interpolation signal generators 41 to 44, respectively, and adds up the interpolation signals from the interpolation signal generators 41 to 44. Specifically, for example, the number of pulses of the interpolation signal generated by the rotation of the rotation shaft 15 is counted, the number of pulses obtained is added, and the result is divided by the number of sensors to obtain the angular position or the rotational angle. Ask for The arithmetic unit 50 can cancel the angular error of each of the interpolation signals of the interpolation signal generators 41 to 44 by adding up, and can reduce the angular error and improve the accuracy.

FIG. 5 is a view showing the arrangement position of the sensor of the encoder according to the first embodiment of the present invention.

Referring to FIG. 5, the sensors 31 to 34 are arranged at the detection positions of the angle φ (j, k _j ) (degrees) with respect to the dial plate 20. Although the origin of the angle can be selected arbitrarily, for example, the position of the sensor 31 can be selected. The angle φ (degree) is expressed by Equation 1, θ _j (degree) is expressed by Equation 2, and δ _k is expressed by Equation 3.
φ (j, k _j ) = θ _j + δ _kj (1)
θ _j = 360 / M × (j−1) (j = 1, 2,..., M) (2)
δ _kj = 360 / N × MOD [(k _j -1) / D] (k _j = 1, 2,..., M) (3)
Here, j is an integer of 1 to M assigned to the sensors 31 to 34. D is a divisor of M or M (except 1). M is the number of sensors, which is 4 in the first embodiment. N is the number of graduations 21 over 360 degrees of the scale plate 20, and is 360 in the first embodiment.

MOD in the above equation 3 is a function that outputs the value after the decimal point of the input value. MOD [(k _j -1) / D] is a value (decimal fraction) smaller than 1 and, for example, MOD [3.75] = 0.75, MOD [1.25] = 0.25, MOD [0 .25] = 0.25. By this, δ _kj becomes smaller than 360 / N (degrees), that is, smaller than the minimum scale interval.

As a modification of the above formula _{1, φ (j, k j} ) may be = θ _j -δ _kj. That is, Equation 1 may be an angle obtained by combining θ _{j of} Equation 2 and δ _{kj of} Equation 3.

In FIG. 5, four sensors 31 to 34 are arranged. This is the case where D = M = 4 in the equations 1 to 3. The sensors 31 to 34 are disposed at angles φ (1, k ₁ ), φ (2, k ₂ ), φ (3, k ₃ ), and φ (4, k ₄ ), respectively. Here, k _{j = 1 to 4} = 1, 2,... The vertex of the triangle mark Δ facing the scale plate indicates the detection position of the sensor.

FIG. 6 is a view showing an example of the arrangement position of each sensor in the first embodiment of the present invention, and shows the arrangement position of each sensor shown in FIG. 5 in an enlarged manner. 6 (a) to 6 (d) show the arrangement positions of the sensors 31 to 34, respectively.

Referring to FIG. 6 (a) ~ (d) , sensors 31-34 will be disposed in an angle of _{φ (j, k j) =} θ j + δ kj (j = 1 ~ 4 integer). θ _j is an angular position obtained by equally dividing 360 degrees into four, and δ _kj is an angle in units of an angle formed by equally dividing the minimum angular interval of the scale 21 into four. In the case of the number of graduations N = 360, the sensors 31 to 34 are, for example, the following φ (1, k ₁ ), φ (2, k ₂ ), φ (3, k ₃ ) and φ (4, k ₄₎ It is arranged at the angle shown in).
Sensor 31: φ (1, k ₁ ) = θ ₁ + δ _k ₁ = 0 + 0 = 0 degree Sensor 32: φ (2, k ₂ ) = θ ₂ + δ _k ₂ = 90 + 0.25 = 90.25 degree Sensor 33: φ (3 _{_{, k 3) = θ 3 +}} δ k3 = 180 + 0.50 = 180.50 degrees sensor _{34: φ (4, k 4} ) = θ 4 + δ k4 = 270 + 0.75 = 270.75 °

FIG. 7 is a diagram showing an angular error of the interpolation signal of the encoder according to the first embodiment of the present invention. Referring to FIG. 7, the waveforms of the angular errors of the interpolation signals of the sensors 11 to 14 are out of phase with each other by 1⁄4 degrees (0.25 degrees), and δ _kj of the arrangement of the sensors 31 to 34 is It is understood that it is reflected.

FIG. 8 is a diagram showing an angular error of the encoder according to the first embodiment of the present invention.

Referring to FIG. 8, it can be seen that the angular error of the encoder is at most ± 16 seconds, which is approximately one half of the angular error of FIG. 1 shown above.

FIG. 9 is a diagram showing DFT analysis of the angular error of the encoder according to the first embodiment of the present invention, in which the angular error of FIG. 8 is DFT analyzed.

Referring to FIG. 9, the angular errors of the 360th, 720th, 1080th and 1800th order components which are multiples of the scale number 360 are 2 seconds or less, and in particular, the 360th order component is 6% with respect to FIG. It can be seen that the 720th component significantly decreases to 9%. This clearly shows the effect of the present embodiment.

As a modification (modification 1) of arrangement position of sensors 31-34, although δ _{kj of the} above-mentioned formula 1 takes a value of 0, 0.25, 0.50, and 0.75 by formula 3, sensor 31 It may be arbitrarily assigned to. For example, (δ _k1 , δ _k2 , δ _k3 , δ _k4 ) = (0, 0.50, 0.25, 0.75), (0, 0.75, 0.25, 0.50), (0 .25, 0, 0.50, 0.75) and so on. It is also apparent from the principle of the present invention that the effects of the above-described embodiment can be obtained in the same manner as in the first modification.

In addition, as another modification (modification 2) of the arrangement position of a sensor, although θ _j of Expression 1 is 0, 90, 180, and 270 according to Expression 2, respective positions with respect to the sensors 31 to 34 It is preferable to set θ _j at equal angular intervals because the error of the low-order component increases in this case, although the angle may be shifted by an integer multiple of 360 / N.

As yet another modification (Modification 3), when D in Equation 3 is a divisor of M, each sensor is any integer of k _j = 1 to M in Equation 3, so the number M of sensors is M When D is 4 and D is 2, (δ _k1 , δ _k2 , δ _k3 , δ _k4 ) = (0, 0.5, 0, 0.5). In this case, among the angular errors of the encoder due to the angular error of the interpolation signal, it is possible to reduce the error of the N-th-order component (except for the (N × D) -order component).

According to the present embodiment, with respect to the dial plate 20, the plurality of sensors 31 to 34 are the term 360 degrees / M × (j−1) of the right side of Formula 2 and the term 360 degrees / N × of the right side of Formula 3. By arranging at the position of the angle combined with MOD [(k _j -1) / D], N-order component of the angular error of the encoder due to the angular error of the interpolation signal (however, Error of N × D) except for the following components can be reduced, together with the error due to eccentricity due to the attachment of the dial 20 to the rotary shaft 15 and the angle error of the encoder due to the error of the forming position of the dial 21 of the dial 20 Can also be reduced. Therefore, according to the present embodiment, it is possible to provide an encoder having both high resolution and high accuracy.

In this embodiment, an example using a transmission type optical sensor has been described, but as an alternative example, for example, a scale is shown on a scale plate, and optical contrast between the scale and other portions is shown. You may use the reflective optical sensor utilized. For example, the scale portion is a dial whose reflectance is higher or lower (that is, the absorption coefficient is higher) than other portions.

This embodiment is also applicable to a magnetic sensor and a magnetic encoder that is magnetically calibrated, instead of an optical sensor and a dial. A plurality of magnetic sensors for detecting a magnetic scale may be arranged in the same manner as the optical sensor described above.

The encoder 10 of the present embodiment can be applied to an incremental encoder that detects the rotation angle and rotational speed of the rotation shaft 15, and can be applied to an absolute encoder that detects an absolute angular position.

Second Embodiment
FIG. 10 is a diagram showing a schematic configuration of an encoder according to a second embodiment of the present invention.

Referring to FIG. 10, the encoder 100 according to the first embodiment is disposed on an object (not shown) for measuring the position or movement amount, and is equally spaced in the movement direction of the object (the direction indicated by the arrow MV). A scale plate 120 having a scale 121 formed thereon, and three sensors 131 to 133 which detect the scale 121 and generate detection signals of sine waves having a phase shift of 90 degrees with each other based on the detection. Interpolation signal generators 141 to 143 that generate interpolation signals that interpolate the scale intervals based on detection signals for the sensors 131 to 133, and interpolation signals for the sensors 131 to 133 based on the interpolation signals And a computing unit 150 for obtaining the position or the movement amount.

The scale plate 120 is attached along the moving direction of the object (the direction indicated by the arrow MV), and the scale 121 is provided at equal intervals. The portion of the scale 121 is designed to reflect light. The portion of the scale 121 may absorb light, and the surface of the graduation plate 120 therearound may reflect light.

The sensors 131 to 133 each have a light emitting element 135 and a light receiving element 137. In the sensors 131 to 133, the scale 121 reflects the light from the light emitting element 135, and the light receiving element 137 receives the light. The sensors 131 to 133 generate sine wave electrical signals that are 90 degrees out of phase with each other according to the intensity of the light received by the light receiving element 137, and output the signals as a detection signal. For example, one of the two sine wave electrical signals that are 90 degrees out of phase with each other is a Sin voltage signal, and the other is a Cos voltage signal.

The interpolation signal generators 141 to 143 and the calculator 150 have the same configuration and operation as the interpolation signal generators 41 to 44 and the calculator 50 in the first embodiment, respectively. Find the amount of movement. The arithmetic unit 150 can cancel the position error of the interpolation signal of each of the interpolation signal generators 141 to 143, and can reduce the position error to improve the accuracy.

FIG. 11 is a diagram showing an example of the arrangement position of each sensor in the second embodiment of the present invention. (A) to (c) show the arrangement positions of the sensors 131 to 133, respectively.

Referring to FIG. 11, the sensors 131 to 133 are arranged at positions p (j, k _j ) with respect to the dial plate 120 at their detection positions. Although the origin of the position can be selected arbitrarily, for example, the position of the sensor 131 can be selected. The position p is represented by equation 5, L _j is represented by equation 6, and δ _kj is represented by equation 7.
p (j, k _j ) = L _j + δ _kj (5)
L _j = gl × m _j (6)
δ _kj = gl × MOD [(k _j -1) / D] (k _j = 1, 2,..., M) (7)
Here, j is an integer of 1 to M assigned to the sensors 131 to 133. m _j is an integer, and mutually different integers are selected for j. D is a divisor of M or M (except 1). gl is a scale interval. M is the number of sensors, and is 3 by way of example in the second embodiment. MOD is a function that outputs the value after the decimal point of the input value, and is the same as in the first embodiment. As a modification of the above formula _{5, p (j, k j} ) = it may be _L j _-δ _kj. That is, Equation 5 may be a position where L _j in Equation 6 and δ _{kj in} Equation 7 are combined.

As shown in (a) ~ (c) of FIG. 11, sensors 131-133 are disposed at the position of _{p (j, k j) =} L j + δ kj (j = 1 ~ 3 integer). L _j is an integral multiple (m _j times) of the scale interval gl, and δ _kj is a distance obtained by equally dividing the scale interval gl into three. The sensors 131 to 133 are disposed at positions indicated by p (1, k ₁ ), p (2, k ₂ ), and p (3, k ₃ ) below, respectively.
Sensor 131: p (1, k ₁ ) = L ₁ + δ _k ₁ = 0 + 0 = 0
Sensor 132: p (2, k ₂ ) = L ₂ + δ _k ₂ = gl × 10 + gl × 1/3 = (10 + 1/3) × gl
Sensor _{133: p (3, k 3} ) = L 3 + δ k3 = gl × 20 + gl × 2/3 = (20 + 2/3) × gl
As described above, by disposing the sensors 131 to 133, the phases of the position errors of the interpolation signal become out of phase with each other by 1⁄3 of the scale interval gl. By summing the insertion signals, the error due to the position error of the interpolation signal is reduced. As a result, the accuracy of the encoder 100 is improved.

As a modification (modification 4) of the arrangement position of sensors _131-133 , although delta _kj of formula 5 takes a value of 0, 1/3, and 2/3 by formula 7, it is arbitrary to sensors 131-133. May be assigned to It is apparent from the principle of the present invention that the effects of the present embodiment described above can be similarly obtained by this modification as well.

According to the present embodiment, with respect to the dial plate 120, the plurality of sensors 131 to 133 are the term gl × m _{j on} the right side of Equation 6 and the term gl × MOD [(k _j −1) / D), which reduces the angular error of the encoder due to the angular error of the interpolated signal, together with the error due to the alignment of the attachment of the dial 120 to the object and the dial The position error of the encoder 100 resulting from the error of the formation position of the scale 121 of 120 can also be reduced. Therefore, according to the present embodiment, it is possible to provide an encoder having both high resolution and high accuracy.

In the present embodiment, in place of the reflective sensors 131 to 133 and the dial plate 120, transmissive sensors and dial plates can be used. Furthermore, the present embodiment can be applied to a magnetic encoder.

Although the preferred embodiments of the present invention have been described above in detail, the present invention is not limited to the specific embodiments, and various changes and modifications may be made within the scope of the present invention as set forth in the claims. It is possible. For example, the technical ideas and modifications described in one of the first and second embodiments may be combined with the other embodiment.

Reference Signs List

10, 100

encoder

20, 120

graduation plate

21, 121 graduation 31 to 34, 131 to 133 sensors 41 to 44, 141 to 143

interpolation signal generator

50, 150 computing unit

Claims

M sensors detecting a plurality of elements indicating angles arranged at predetermined angular intervals on a substrate to generate a first signal having periodicity, wherein the M sensors are arranged at predetermined angles, The predetermined angle is an angle combining 360 / M × (j−1) (degrees) and 360 / N × MOD [(k j −1) / D] (degrees), where M is N is an integer number of 2 or more, N is the number of elements, MOD is a function that outputs the value after the decimal point of the input value, D is a divisor of M or M except for 1 where j is 1 to M M sensors having different values for M sensors as integers of k and k j is an integer of 1 to M,
A generator generating, for each of the M sensors, a second signal that interpolates the predetermined angular interval based on the first signal;
An arithmetic unit that adds the second signals to the M sensors to obtain an angular position or a rotational angle;
An encoder comprising:
The encoder according to claim 1, wherein the base is a disc-shaped scale plate, and the elements are arranged circumferentially.
M sensors detecting a plurality of elements indicating positions arranged at predetermined intervals on a substrate to generate a first signal having periodicity, wherein the M sensors are separated from each other by a predetermined distance The predetermined distance is a position obtained by combining gl × m j which is an integer (m j ) times the predetermined interval (gl) and gl × MOD [(k j −1) / D], Here, M is an integer of 2 or more, MOD is a function that outputs the decimal value of the input value, D is a divisor of M or M except for 1 where k j is 1 to M. And the M sensors, which are integers,
A generator generating, for each of the M sensors, a second signal that interpolates between elements of the predetermined interval based on the first signal;
An arithmetic unit for summing the second signals for the M sensors to obtain a position or movement amount;
An encoder comprising:
The encoder according to claim 3, wherein the plurality of elements are arranged in one direction on the substrate.
The encoder according to any one of the preceding claims, wherein the k j have different values for M sensors.
The encoder according to any one of the preceding claims, wherein D is M.
The element comprises a slit that transmits light or a member that reflects or absorbs light,
The encoder according to any one of claims 1 to 6, wherein the plurality of sensors are optical sensors.
The element is a convex member or a magnet member made of a ferromagnetic material,
The encoder according to any one of claims 1 to 6, wherein the plurality of sensors are proximity sensors that magnetically detect the convex member or the magnet member.