阅读说明：本技术 编码器 (Encoder for encoding a video signal ) 是由 渡部司 于 2018-08-13 设计创作，主要内容包括：编码器10设置为：M个传感器31～34,将以预定角度间隔配置于基体的表示角度的多个组件予以检测而生成具有周期性的第一信号,M个传感器以预定角度配置,预定角度为360/M×(j-1)(度)与360/N×MOD[(k<Sub>j</Sub>-1)/D](度)所组合出的角度,其中M为2以上的整数,N为组件数量,MOD为将输入值的小数点以下的值输出的函数,D为M的因子或是为M但是不为1,j为在1至M的整数中由M个传感器取各自相异的值,k<Sub>j</Sub>为1至M的整数；生成器41～44,对M个传感器的每一个传感器,基于第一信号而生成第二信号,第二信号内插预定角度间隔；以及运算器50,将对于M个传感器的第二信号合并运算而求得角度位置或旋转角。(The encoder 10 is arranged to: m sensors 31 to 34 arranged at predetermined angles, the predetermined angles being 360/Mx (j-1) (DEG) and 360/NxMOD [ (k) and arranged at predetermined angles, and detecting a plurality of elements arranged at predetermined angular intervals on a substrate and indicating the angles to generate a first signal having periodicity j ‑1)/D](degree) where M is an integer of 2 or more, N is the number of elements, MOD is a function of the output of a value of a decimal point or less of the input value, D is a factor of M or M but not 1, j is a value which is different from each other among the integers 1 to M and is taken by the M sensors, k is a value which is different from each other among the integers 1 to M j Is an integer from 1 to M; generators 41 to 44 for generating a second signal based on the first signal for each of the M sensors, the second signal being interpolatedFixing angle intervals; and an arithmetic unit 50 for calculating the angular position or the rotational angle by combining the second signals for the M sensors.)

1. An encoder, comprising:

m sensors for detecting a plurality of elements arranged on a substrate at predetermined angular intervals and representing angles, and generating a first signal having periodicity, wherein the M sensors are arranged at predetermined angles, and the predetermined angles are 360/Mx (j-1) (degree) and 360/NxMOD [ (k) _j-1)/D](degree) wherein M is an integer of 2 or more, N is the number of elements, MOD is a function of an output of a value of a decimal point or less of an input value, D is a factor of M or M but not 1, j is a value different from each other for M of the sensors in an integer of 1 to M, k is _jIs an integer from 1 to M;

a generator that generates, for each of the M sensors, a second signal based on the first signal, the second signal interpolating the predetermined angular interval; and

and an arithmetic unit for calculating an angular position or a rotation angle by combining the second signals for the M sensors.

2. The encoder of claim 1, wherein the substrate is a disk-shaped scale, and the component arrangements are arranged in a circumferential direction.

3. An encoder, comprising:

m sensors for detecting a plurality of elements arranged on a substrate at predetermined intervals to generate a periodic first signal, wherein the M sensors are arranged at predetermined intervals from each other, and the predetermined intervals are integers (M) of the predetermined intervals (gl) _j) Multiple of gl × m _jAnd gl × MOD [ (k) _j-1)/D]The combined positions where M is an integer of 2 or more, MOD is a function of the output of values below the decimal point of the input value, D is a factor of M or is M but not 1, k _jIs an integer from 1 to M;

a generator that generates, for each of the M number of the sensors, a second signal between components interpolated at the predetermined intervals based on the first signal; and

and an arithmetic unit for calculating a position or a movement amount by combining the second signals for the M sensors.

4. The encoder according to claim 3, wherein a plurality of the components are arranged in the same direction on the base.

5. The encoder of any of claims 1 to 4, wherein said k is _jThe M sensors have different values.

6. The encoder of any one of claims 1 to 5, wherein the D is M.

7. The encoder of any one of claims 1 to 6, wherein the assembly is constituted by a slit for passing light, a member for reflecting light, or a member for absorbing light, and a plurality of the sensors are optical sensors.

8. The encoder according to any one of claims 1 to 6, wherein the component is a convex member or a magnet member made of a ferromagnetic body, and the plurality of sensors are proximity sensors that magnetically detect the convex member or the magnet member.

Technical Field

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

Background

The encoder is a device that reads scales marked on a scale at equal angular intervals to measure positions such as a rotation angle and an absolute angular position. The precision of the scale interval is limited according to the precision of the scribing or the precision of the sensor for detecting the scale, so that the resolution improvement caused by the scale is limited. Therefore, a sine wave further divided into the minimum scale intervals is generated by two analog signals shifted from each other by 90 degrees in phase, and an arctan operation of the two analog signals is performed to determine an angle using an interpolation signal indicating the angle, thereby improving the resolution.

In order to reduce scale scribing errors, encoder mounting errors, and the like, a method is used in which a plurality of sensors are arranged and interpolation signals obtained from the respective sensors are averaged. Further, a method of providing a sensor for correction to perform self-correction of an angle error has been proposed (for example, refer to patent document 1).

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent application laid-open No. 2011-

Disclosure of Invention

[ problems to be solved by the invention ]

The present invention aims to provide a novel and useful encoder capable of achieving both high resolution and high precision.

According to an aspect of the present invention, there is provided an encoder comprising: m sensors for detecting a plurality of elements arranged on a substrate at predetermined angular intervals and representing angles, and generating a first signal having periodicity, wherein the M sensors are arranged at predetermined angles, and the predetermined angles are 360/Mx (j-1) (degree) and 360/NxMOD [ (k) _j-1)/D](degree) where M is an integer of 2 or more, N is the number of elements, MOD is a function of the output of a value of a decimal point or less of the input value, D is a factor of M or M but not 1, j is a value which is different from each other among the integers 1 to M and taken by the M sensors, k is a value _jIs 1An integer up to M; a generator that generates, for each of the M sensors, a second signal based on the first signal, the second signal interpolating the predetermined angular interval; and an arithmetic unit that combines the second signals for the M sensors to calculate an angular position or a rotation angle.

According to the above aspect, the M sensors are arranged at 360/M × (j-1) (degrees) and 360/N × MOD [ (k) by arranging them at predetermined angular intervals with respect to the base body in which the plurality of components representing the angle are arranged _j-1)/D]The angular position of the combined angle can reduce the angular error of the encoder caused by the angular error of the second signal generated based on the first signal generated by the sensor and interpolated at the predetermined angular interval, and also reduce the angular error of the encoder caused by the eccentricity due to the mounting of the rotary shaft to the base and the error of the positions where the plurality of units are arranged at the same angular interval, and as a result, the encoder having both high resolution and high precision can be provided.

According to another aspect of the present invention, there is provided an encoder comprising: m sensors for detecting a plurality of elements arranged on a substrate at predetermined intervals to generate a periodic first signal, wherein the M sensors are arranged at predetermined intervals from each other, and the predetermined intervals are integers (M) of the predetermined intervals (gl) _j) Multiple of gl × m _jAnd gl × MOD [ (k) _j-1)/D]The combined positions where M is an integer of 2 or more, MOD is a function of the output of values below the decimal point of the input value, D is a factor of M or is M but not 1, k _jIs an integer from 1 to M; a generator that generates, for each of the M number of the sensors, a second signal between components interpolated at the predetermined intervals based on the first signal; and an arithmetic unit that combines the second signals for the M sensors to obtain a position or a movement amount.

According to the above aspect, the M sensors are arranged at an integer (M) of a predetermined interval (gl) with respect to the base in which the plurality of modules indicating the positions are arranged at the predetermined interval _j) Multiple gl×m _jAnd gl × MOD [ (k) _j-1)/D]The combined position can reduce the position error of the encoder caused by the position error of the second signal generated based on the first signal generated by the sensor and interpolated by the predetermined interval, and can also reduce the position error of the encoder caused by the installation of the object on the base and the error of the forming position of the plurality of components arranged at the predetermined interval, and as a result, the encoder having both high resolution and high precision can be provided.

Drawings

Fig. 1 is a diagram showing an angular error of a rotary encoder.

FIG. 2 is a diagram showing a Discrete Fourier Transform (DFT) analysis of the angle error shown in FIG. 1 of the rotary encoder.

Fig. 3 is a diagram showing an angle error of an interpolation signal included in fig. 1 of the rotary encoder.

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

Fig. 5 is a diagram showing the arrangement position of a sensor of an encoder according to a first embodiment of the present invention.

Fig. 6 is a diagram showing an example of the arrangement position of each sensor in the first embodiment of the present invention.

Fig. 7 is a diagram showing an angle error of an interpolation signal in an encoder according to a first embodiment of the present invention.

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

Fig. 9 is a diagram showing DFT analysis of an angle error of an encoder according to the first embodiment of the present invention.

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

FIG. 11 is a diagram showing an example of the arrangement positions of the respective sensors in the second embodiment of the present invention.

Detailed Description

The present inventors have studied to achieve high resolution and high precision of a rotary encoder, and have faced the problems described below and found a solution to the problems.

In the rotary encoder, a scale having scales covering 360 degrees is read by a sensor, and a sine wave and a cosine wave are generated based on the scales to generate a signal between interpolated scales (hereinafter referred to as an interpolated signal). Then, an angle signal is generated based on the interpolation signal, and the angle or the rotation angle at which the angle signal appears is detected from the angle signal. In the case where a plurality of sensors are provided, the angle signals from the respective sensors are averaged to obtain the angle. The interpolated signal is used for detecting angles smaller than the minimum scale, in other words for high resolution.

A rotary encoder reduces an eccentricity error of the rotary encoder and an error of an angular position of each scale of a dial by arranging a plurality of sensors at equal angular intervals on the dial and averaging a plurality of output angle signals. However, once the angular error of the rotary encoder is examined, the angular error remains, which is an obstacle to high precision. The present inventors examined the angular error of a rotary encoder in which 4 sensors are arranged at equal angular intervals of 90 degrees. The scale number N of the scale is 360, in other words, the scale is provided at equal intervals at intervals of 1 degree, and is an integral multiple of 32 by interpolating the signal. The 4 sensors detect signals containing the basic scale and the angle error generated by the interpolation division in accordance with the rotation of the dial.

Fig. 1 is a diagram showing an angular error of a rotary encoder, which is an angular error obtained by averaging angular signals from 4 sensors. Referring to fig. 1, it can be seen that the angular error is ± 30 seconds at the maximum over 360 degrees (one week).

Fig. 2 is a diagram showing a Discrete Fourier Transform (DFT) analysis of the angle error shown in fig. 1 of the rotary encoder.

As can be seen from fig. 2, the low-order portion is small, and is effective in reducing the eccentricity error and the angle error of the scale. However, the angular errors of the 360, 720, 1080, 1440 and 1800 fractions were large, ranging from 2 seconds to 11 seconds. These angular error portions are generated as angular errors of the interpolation signal, since the number of sensors M is 4 and the number of scales N is 360, and the number of sensors M is a factor of the number of scales 360, angular errors multiplied by the number of scales. For example, the number of sensors is not 4, even 3, 5 or 6, which likewise produces an angular error of the interpolated signal due to a factor of the scale number 360.

As one method of reducing the angle error of such an interpolation signal, the number of sensors may be 7 or 13 arranged at equal angular intervals. 7 is not a factor of the scale number 360, and thus the angular error of the interpolated signal can be reduced.

Fig. 3 is a diagram showing angle errors of the interpolation signal included in fig. 1 for each sensor, fig. 3 is a diagram showing only angle errors of the interpolation signal among the angle errors separately for each sensor, the horizontal axis is an angle (degrees), the vertical axis is an angle error (seconds), and the position of a black triangle (▲) shows the position of the scale of the dial.

As can be seen from fig. 3, the waveforms of the angular errors of the sensors 1 to 4 are almost the same, and the phases are almost the same. Accordingly, even if the angle signals of the sensors 1 to 4 are averaged, the angle errors of the sensors 1 to 4 cannot be cancelled out, and as shown in fig. 2, the angle error of the interpolated signal remains.

Accordingly, an object of the present invention is to provide an encoder that reduces an angle error of an interpolation signal by mutually shifting positions of a plurality of sensors with respect to a scale of a dial and that achieves both high resolution and high precision.

An embodiment of the present invention is described below with reference to the drawings. In addition, the same reference numerals are assigned to the common components among the plurality of drawings, and the repeated detailed description of the components 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 includes: the angle measuring device includes a scale plate 20 having scales 21 arranged on a rotating shaft 15 as an angle measuring object and formed in a circumferential direction at equal intervals, 4 sensors 31 to 34 for detecting the scales 21 and generating sinusoidal detection signals having phases shifted by 90 degrees periodically from each other based on the detection, interpolation signal generators 41 to 44 for generating interpolation signals (also referred to as angle signals) of intervals of the interpolation scales based on the detection signals of the sensors 31 to 34, and an arithmetic unit 50 for calculating an angle position or a rotation angle by combining the interpolation signals for the sensors 31 to 34 based on the interpolation signals.

The scale 20 is installed concentrically with the rotary shaft 15, and scales 21 are provided at equal intervals in the circumferential direction, and the portions of the scales 21 are permeable to light.

Each of the sensors 31 to 34 has a light emitting element 35, a slit 36 and a light receiving element 37. In fig. 4, the components of the sensors 32 to 34 are not described in detail, but the sensors 32 to 34 have the same components as those of the sensor 31. Light emitted from the light emitting elements 35 of the sensors 31 to 34 passes through the scale 21 and is received by the light receiving element 37 through the slit 36. The light receiving elements 37 of the sensors 31 to 34 generate electrical signals of sine waves having phases shifted by 90 degrees from each other in accordance with the intensity of the received light, and output the electrical signals as detection signals. For example, one of the electrical signals of 2 sine waves shifted by 90 degrees in phase is a Sin voltage signal, and the other is a Cos voltage signal.

Interpolation signal generators 41 to 44 have input sections electrically connected to output sections of the sensors 31 to 34, and 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 arctan of the Cos voltage signal (voltage value of the Sin voltage signal/voltage value of the Cos voltage signal). The interpolated signal is a digital signal. The interpolation signal is a signal obtained by dividing the scale intervals at equal intervals, and is, for example, a signal of several tens of integral multiples to several hundreds of integral multiples.

The arithmetic unit 50 is electrically connected to the output parts of the interpolation signal generators 41 to 44, respectively, and combines the interpolation signals from the interpolation signal generators 41 to 44. Specifically, for example, the angular position or the rotational angle is obtained by counting pulses of an interpolation signal generated by the rotation of the rotary shaft 15, combining the obtained pulse numbers, and dividing the result by the number of sensors. The arithmetic unit 50 can cancel the angle error of each interpolation signal of the interpolation signal generators 41 to 44 by the combination operation, and can reduce the angle error and improve the precision.

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

Referring to FIG. 5, the detection positions of the sensors 31 to 34 are arranged at angles relative to the dial 20

The position of (a). The base point of the angle can be arbitrarily selected, but for example, the position of the sensor 31 can be selected. Angle of rotation

Expressed by equation 1, θ _j(degree) is represented by equation 2, δ _kExpressed by equation 3.

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)

Wherein j is an integer of 1 to M assigned to the sensors 31 to 34. D is a factor of M or is M (but not 1). M is the number of sensors, and is 4 in the first embodiment. N is the number of graduations 21 of the dial 20 covering 360 degrees, 360 in the first embodiment.

MOD in equation 3 is a function for outputting a value equal to or smaller than the decimal point of the input value. MOD [ (k) _j-1)/D]Is a value (decimal) smaller than 1, e.g. MOD [3.75 ]]＝0.75，MOD[1.25]＝0.25，MOD[0.25]0.25. Thus, δ _kjBecomes smaller than 360/N (degrees), in other words, becomes smaller than the minimum scale interval.

Further, a modification of the above equation 1 is

Also, the method can be used. That is, the formula 1 is only required to be θ of the combined formula 2 _jDelta of equation 3 _kjThe angle of (2) is just required.

In FIG. 5, 4 sensors 31 to 34 are arranged. In equations 1 to 3, D-M-4. The sensors 31 to 34 are arranged at angles Wherein k is _j＝1～41, 2.., 4. in addition, the vertex of the triangular mark △ facing the dial indicates the detection position of the sensor.

Fig. 6 is a diagram showing an example of the arrangement positions of the respective sensors in the first embodiment of the present invention, and the arrangement positions of the respective sensors shown in fig. 5 are enlarged. FIGS. 6 (a) to (d) show the positions of the sensors 31 to 34, respectively.

Referring to (a) to (d) of FIG. 6, sensors 31 to 34 are disposed in

(j is an integer of 1 to 4). Theta _jIs an angular position of 360 degrees by quartering, delta _kjThe angle is an angle in units of the angle at which the minimum angular interval of the scale 21 is quartered. When the number of scales N is 360, the sensors 31 to 34 are respectively arranged as follows

And (4, k) ₄) The angle indicated.

The sensor 31:

the sensor 32:

the sensor 33:

the sensor 34:

fig. 7 is a diagram showing an angle error of an interpolation signal in the encoder according to the first embodiment of the present invention. Referring to FIG. 7, it can be seen that the waveforms of the angle errors of the interpolation signals of the sensors 11 to 14 are shifted from each other by 1/4 degrees (0.25 degrees) in phase, and reflect δ of the arrangement of the sensors 31 to 34 _kj。

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, up to ± 16 seconds, is about 1/2 relative to the angular error of fig. 1 shown previously.

Fig. 9 is a diagram showing DFT analysis of an angle error in the encoder according to the first embodiment of the present invention, and the angle error in fig. 8 is subjected to DFT analysis.

Referring to fig. 9, it can be seen that the angular errors of the 360, 720, 1080, and 1800 fractions, which are multiples of 360 times the number of graduations, are less than 2 seconds, and particularly, the 360 fraction is reduced to 6% and the 720 fraction is reduced to 9% with respect to fig. 2. This clearly indicates the efficacy of the present embodiment.

As a modification (first modification) of the arrangement positions of the sensors 31 to 34, δ in the above equation 1 _kjValues of 0,0.25, 0.50 and 0.75 can be taken according to equation 3 and arbitrarily assigned to the sensors 31 to 34. For example: (delta _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 the like. It is understood from the principle of the present invention that the effects of the present embodiment described above are similarly obtained by this modification.

In addition, as another modification (modification two) of the sensor arrangement position, θ of equation 1 is calculated _jThe sensors 31 to 34 may be arranged so as to be shifted by an angle of an integral multiple of 360/N from their respective positions by 0, 90, 180, 270 according to equation 2, but in this case, the error of the low order part increases, and θ _jPreferably, the angular intervals are set to be equal.

Further, as another modification (modification three), when D of expression 3 is a factor of M, each sensor is k in expression 3 _jWhen the number of sensors is 4, D is 2 (δ is one of integers from 1 to M) _k1,δ _k2,δ _k3,δ _k4) (0,0.5,0, 0.5). In this case, the error of the N-fold sub-portion (excluding the (N × D) sub-portion) among the angular errors of the encoder caused by the angular error of the interpolation signal can be reduced.

According to the present embodiment, the plurality of sensors 31 to 34 are arranged on the right side of the expression 2 at 360 degrees/Mx (j-1) and the expression 3 at 360 degrees/NxMOD [ (k) is arranged on the right side of the expression 20 _j-1)/D]The position of the combined angle can be reduced by the error of the N-fold number of times (excluding the (N × D) number of times) of the angle error of the encoder caused by the angle error of the interpolation signal, and the angle error of the encoder caused by the error due to the eccentricity of the attachment of the rotary shaft 15 to the scale plate 20 and the error of the formation position of the scale marks 21 of the scale plate 20.

In this embodiment, although a transmissive optical sensor is used, a reflective optical sensor may be used instead in which a scale is indicated by a dial and optical contrast is used between the scale and the other portions. For example, a dial in which a portion of the scale has a higher or lower reflectance (in other words, a higher absorption rate) than other portions.

The present embodiment can also be applied to a magnetic encoder in which an optical sensor and a dial are replaced with a magnetic sensor and a magnetic scale. The plurality of magnetic sensors for detecting the 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 for detecting the rotation angle or the rotation speed of the rotating shaft 15, and can also be applied to an absolute encoder for detecting 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, an encoder 100 according to the second embodiment includes: the device includes a dial 120 having a scale 121 disposed on an object to be measured (not shown) at a position or a movement amount and formed at regular intervals in a movement direction (direction indicated by arrow MV) of the object, 3 sensors 131 to 133 for detecting the scale 121 and generating sinusoidal detection signals having phases shifted by 90 degrees periodically from each other based on the detection, interpolation signal generators 141 to 143 for generating interpolation signals for interpolating intervals of the scale based on the detection signals of the sensors 131 to 133, and an arithmetic unit 150 for calculating a position or a movement amount by combining the interpolation signals for the sensors 131 to 133 based on the interpolation signals.

The dial 120 is attached along the moving direction of the object (the direction indicated by the arrow MV), and is provided with scale marks 121 at equal intervals. Portions of the scale 121 are capable of reflecting light. In addition, the following may be used: the scale 121 partially absorbs light while the surrounding surface of the scale 120 reflects light.

The sensors 131 to 133 each have a light emitting element 135 and a light receiving element 137. The light emitted from the light emitting elements 135 of the sensors 131 to 133 is reflected by the scale 121 and received by the light receiving element 137. The light receiving elements 137 of the sensors 131 to 133 generate electrical signals of sine waves having phases shifted by 90 degrees from each other in accordance with the intensity of the received light, and output the electrical signals as detection signals. For example, one of the electrical signals of 2 sine waves shifted by 90 degrees in phase is a Sin voltage signal, and the other is a Cos voltage signal.

The interpolation signal generators 141 to 143 and the arithmetic unit 150 have the same configuration and operation as the interpolation signal generators 41 to 44 and the arithmetic unit 50 in the first embodiment, respectively, and determine the position or the movement amount of the dial 120. 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 and improve the precision.

Fig. 11 is a diagram showing an example of arrangement positions of respective sensors in the second embodiment of the present invention. FIGS. 11 (a) to (c) show the positions of the sensors 131 to 133, respectively.

Referring to fig. 11, the detection positions of the sensors 131 to 133 are arranged at positions p (j, k) with respect to the dial 120 _j). The reference point of the position can be arbitrarily selected, but the position of the sensor 131 can be selected, for example. Position p is represented by equation 5, L _jIs expressed by equation 6, δ _kjExpressed 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)

Wherein j is an integer of 1-M assigned to the sensors 131-133. m is _jFor the integers, different integers are selected for j. D is a factor of M or is M (but not 1). gl is the scale interval. M is the number of sensors, and is 3 in the second embodiment. MOD is a function for outputting a value equal to or smaller than the decimal point of the input value, and is similar to the first embodiment. Further, a modification of the above equation 5 is p (j, k) _j)＝L _j-δ _kjAlso, the method can be used. In other words, the formula 5 is L of the formula 6 _jDelta of equation 7 _kjThe combined position is sufficient.

As shown in FIGS. 11 (a) to (c), sensors 131 to 133 are disposed at p (j, k) _j)＝L _j+δ _kj(j is an integer of 1 to 3). L is _jIs an integer multiple (m) of the scale interval gl _jMultiple), delta _kjThe scale is spaced by a distance gl, trisected. The sensors 131 to 133 are arranged at p (1, k) below ₁)、p(2,k ₂)、p(3,k ₃) The indicated position.

The sensors 131: p (1, k) ₁)＝L ₁+δ _k1＝0+0＝0

The sensor 132: p (2, k) ₂)＝L ₂+δ _k2＝gl×10+gl×1/3＝(10+1/3)×gl

The sensors 133: p (3, k) ₃)＝L ₃+δ _k3＝gl×20+gl×2/3＝(20+2/3)×gl

The sensors 131 to 133 are arranged in this way, the phases of the position errors of the interpolation signals are respectively shifted from the 1/3 phase of the scale interval gl, and the interpolation signals to the sensors 131 to 133 are combined and calculated by the calculator 150, thereby reducing the error caused by the position error of the interpolation signals. As a result, the precision of the encoder 100 is improved.

As a modification (fourth modification) of the arrangement positions of the sensors 131 to 133, δ in equation 5 is expressed _kjValues of 0, 1/3, and 2/3 are given by equation 7, but may be arbitrarily assigned to the sensors 131 to 133. It is understood from the principle of the present invention that the effects of the present embodiment described above are similarly obtained by this modification.

According to the present embodiment, the plurality of sensors 131 to 133 are arranged on the right side of the equation 6 with respect to the dial 120, i.e., gl × m _jThe right term of equation 7, gl × MOD [ (k) _j-1)/D]The combined position can reduce the angular error of the encoder caused by the angular error of the interpolation signal, and can also reduce the position error of the encoder 100 caused by the error due to the alignment of the object to be attached to the dial plate 120 and the error in the formation position of the scale 121 of the dial plate 120. Therefore, according to the present embodiment, an encoder having both high resolution and high precision can be provided.

In the present embodiment, transmissive sensors and dials may be used instead of the reflective sensors 131 to 133 and the dial 120. Further, 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 modifications and changes can be made within the scope of the present invention described in the claims. For example, in the first embodiment and the second embodiment, the technical ideas and modifications described in one embodiment may be combined with those of the other embodiment.

Description of the symbols

10. 100 encoder

20. 120 dial

21. 121 scale

31-34, 131-133 sensor

41-44, 141-143 interpolation signal generator

50. 150 arithmetic unit