JP2015017916A - Detection head, optical encoder, and adjustment method of optical encoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detection head and optical encoder capable of reducing the displacement of the generation position of an origin pulse without requiring assembling labor.SOLUTION: A detection head 120 of the present invention includes: a light source 121; a light receiving unit 122 including a plurality of light receiving elements 123 arranged in the length measurement direction of a scale 110; and origin pulse creating means 131 for creating an origin pulse from an analog signal detected by the light receiving elements 123. The light receiving element 123 having the smallest axis deviation amount from the light source 121 is selected. The optical encoder 100 of the present invention includes the detection head 120, and a scale 110 having an origin pattern 111.

Description

  The present invention relates to a detection head, an optical encoder, and a method for adjusting an optical encoder.

  The optical incremental encoder is a displacement sensor that detects the relative movement amount of the detection head on the scale. Among optical incremental encoders, for example, in a reflective encoder, the detection head includes a light source and a light receiving element. By detecting the light emitted from the light source and reflected by the incremental pattern on the scale by the light receiving element, the relative movement amount of the detection head with respect to the scale is detected. Optical incremental encoders are applied to many industrial devices because they can measure the absolute position on the scale by combining an origin signal generator.

  The basic principle of the origin signal generator is that the reflected light or transmitted light from the origin pattern on the scale is detected by the light receiving element to obtain an analog signal, and the origin pulse, which is a digital signal obtained by binarizing it, is controlled. To be transmitted to the system. The control system can calculate the absolute position on the scale from the reference position to which the origin pulse is transmitted and the relative movement amount obtained from the encoder.

  As an origin signal generator, an origin signal is generated from an analog signal obtained by irradiating light from a light source onto an origin pattern and detecting reflected light by a light receiving element (Patent Document 1). . An encoder having a plurality of origin patterns and light receiving elements is also disclosed in order to improve detection robustness (Patent Document 2).

  FIG. 9 shows an optical encoder 800. The optical encoder 800 includes a scale 110 and a detection head 820 that moves relative to the scale 110. (The casing of the detection head 820 is omitted for easier viewing of the figure.) The detection head 820 includes a light source 121, a light receiving unit 822, and an incremental pattern detection unit 124. The light receiving unit 822 includes a light receiving element 823.

  As shown in FIG. 9, the general reflection type optical encoder 800 is designed such that the light source 121 and the light receiving element 823 are placed on a plane P <b> 1 perpendicular to the length measurement direction of the scale 110. . This is a design for preventing the origin position from changing even if the interval (gap) between the detection head 820 and the scale 110 changes. On the other hand, the light source 121 and the light receiving unit 822 are not necessarily the same height, and are often assembled slightly differently. This is because of the space for assembling parts in the detection head 820. In FIG. 9, the difference in height between the light source 121 and the light receiving unit 822 is indicated by ΔH.

  FIG. 12 is a diagram showing a positional relationship among the light source 121, the light receiving unit 822, and the origin pattern 111 (corresponding to a diagram viewed from an arrow XII in FIG. 9). In FIG. 12, the incremental pattern detector 124 is not shown for convenience of explanation. As shown in FIG. 12, since there is a difference in height (ΔH) between the light source 121 and the light receiving unit 822 in the detection head 820, the height from the scale 110 differs between the light source 121 and the light receiving unit 822.

With reference to FIGS. 9 to 11, how the origin pulse is generated when the detection head 820 moves on the scale 110 will be described.
As shown in FIG. 9, when the detection head 820 is at the position of x = x1 on the scale 110, most of the light reflected by the origin pattern 111 does not reach the light receiving element 823. Therefore, as shown in FIG. 11, the intensity of the analog signal of the reflected light of the origin pattern 111 is equal to or less than the threshold value, and no origin pulse is generated.

  FIG. 10 shows the detection head 820 at the origin position. In other words, the light source 121, the light receiving unit 822, and the origin pattern 111 are on the same plane P1. The position of the plane P1 at this time is expressed as x = x2. For this reason, the light reflected by the origin pattern 111 reaches the light receiving element 823. As shown in FIG. 11, the intensity of the analog signal of the reflected light of the origin pattern 111 becomes equal to or greater than a threshold value, an origin pulse is generated, and the origin is detected.

  Using FIG. 12 to FIG. 14, it will be described that the origin detection position does not change even when the distance between the detection head 820 and the scale 110 changes. In FIG. 12, it is assumed that the distance between the detection head 820 and the scale 110 is as designed. It is a figure which shows the positional relationship of the light source 121, the light receiving element 823, and the origin pattern 111. FIG. 13 is a diagram illustrating a state in which the distance between the detection head 820 and the scale 110 has shifted by ΔD from the design value. In FIG. 13, as in FIG. 12, the incremental pattern detection unit 124 is not shown for convenience of explanation. 12 and 13 are views of the optical encoder 800 viewed from the light source 121 side (arrow XII in FIG. 9) on the plane P1.

  First, as shown in FIG. 12, an origin pulse is generated with the distance between the detection head 820 and the scale 110 as a design value, and the position of the origin pattern 111 is detected. When the interval between the detection head 820 and the origin pattern 111 is a design value, an origin pulse is generated with x = x2 as described above (see FIG. 11).

  Next, it is assumed that the distance between the detection head 820 and the scale 110 is shifted from the design value by ΔD (FIG. 13). Also in the case of FIG. 13, it is natural that the origin pulse is generated when the light source 121, the light receiving element 823, and the origin pattern 111 are on the plane P1, as in FIG. As shown in FIG. 14, even if the distance between the detection head 820 and the scale 110 is changed, the intensity of the analog signal may be weakened, but the origin pulse is generated when x = x2. That is, there is no deviation of the origin.

  As described above, when the light source 121, the origin pattern 111, and the light receiving element 823 are on the plane P1, even if the distance between the detection head 820 and the scale 110 changes, the origin pulse is not generated. It can be said that does not occur.

Special table 2008-503745 gazette JP 7-318371 A

  In the reflective optical encoder 800, it is ideal that the light source 121 and the light receiving element 823 are manufactured so as to be on the plane P1. This is because, as described above, if the light source 121 and the light receiving element 823 are on the plane P1, even if the distance between the detection head 820 and the scale 110 slightly deviates from the design value, the origin detection position does not deviate. . However, due to manufacturing errors and adjustment errors during assembly, the light source 121 and the light receiving element 823 may not be on the plane P1 and may be displaced. This deviation is called an axis deviation.

  With reference to FIGS. 15 to 18, how the origin pulse is generated when the detection head 820 having an axis deviation moves on the scale 110 will be described. In FIG. 15, a plane perpendicular to the length measurement direction of the scale 110 and on which the light source 121 rides is P2, and a plane on which the center of the light receiving element 823 rides is P3. The distance in the length measurement direction of the scale 110 between the plane P2 and the plane P3 is the axis deviation amount L.

  In FIG. 15, the plane P <b> 3 overlaps the origin pattern 111. The position of the detection head 820 is represented by the position of the light source 121, and the position in FIG. 15 is represented as x = x3. In the state of FIG. 15, considering the path of light rays from the light source 121 to the light receiving element 823 via the scale 110, this path does not pass through the origin pattern 111. In FIG. 15, the path of this light beam is indicated by a one-dot chain line. Therefore, as shown in FIG. 18, the intensity of the analog signal of the reflected light of the origin pattern 111 does not exceed the threshold value, and no origin pulse is generated.

  In FIG. 16, the origin pattern 111 is between the plane P2 and the plane P3. The position of the detection head in FIG. 16 is expressed as x = x4. In the state of FIG. 16, considering the path of light rays from the light source 121 to the light receiving element 823, the light reflected by the origin pattern 111 reaches the light receiving element 823. For this reason, as shown in FIG. 18, since the light reflected by the origin pattern 111 reaches the light receiving element 823, the intensity of the received light signal exceeds the threshold value, and the origin pulse is generated.

  FIG. 17 is a diagram illustrating a state in which the plane P2 and the origin overlap each other. The detection head position in FIG. 17 is represented as x = x5. At this time, the light path from the light source 121 to the light receiving element 823 via the scale 110 is deviated from the origin pattern 111. Therefore, as shown in FIG. 18, the intensity of the analog signal of the reflected light of the origin pattern 111 does not exceed the threshold value, and no origin pulse is generated.

  When there is an axial misalignment between the light source 121 and the light receiving element 823, the origin pulse generation position is deviated as compared with a case where the axial misalignment is zero. However, if the axis deviation amount L is constant, the deviation amount of the origin pulse generation position caused by the axis deviation should be the same, so it is considered that calibration should be performed appropriately. However, the present inventors have found that if there is an axis deviation, the origin detection position also varies due to a change in the distance between the detection head 820 and the scale 110.

  A change in the origin pulse generation position when the distance between the detection head 820 and the scale 110 changes when there is an axial deviation between the light source 121 and the light receiving element 823 will be described with reference to FIGS. 19 to 21, the incremental pattern detection unit 124 is not shown for convenience of explanation.

  FIG. 19 is a diagram showing a positional relationship among the light source 121, the light receiving element 823, and the origin pattern 111. FIG. 19 is a side view of the state of FIG. 16 viewed from the light source 121 side. In this case, as shown in FIG. 18, the origin pulse is generated when x = x4 as described above.

  FIG. 20 shows a state in which the distance between the detection head 820 and the scale 110 is shifted from FIG. 19 by ΔD. As can be seen from FIG. 20, when the distance between the detection head 820 and the scale 110 changes, the reflected light from the origin pattern 111 does not enter the light receiving element 823 even at the position of x = x4.

  When the position of the origin pattern 111 is detected in a state where the distance between the detection head 820 and the scale 110 has changed by ΔD from the state of FIG. 19, in this case, as shown in FIGS. 21 and 22, x = x4−Δx. An origin pulse is generated.

  Incidentally, if the heights of the light source 121 and the light receiving unit 822 are the same, even if the distance between the detection head 820 and the scale 110 is deviated from FIG. 19, the reflected light from the origin pattern 111 is similarly received by the light receiving element 823. Is incident on. However, there may be a case where a step is generated between the light source 121 and the light receiving unit 822 due to the installation space.

  As described above, when the distance between the detection head 820 and the scale 110 changes in a state where the light source 121 and the light receiving element 823 are misaligned and the light source 121 and the light receiving element 823 are not at the same height, There is a problem that the origin pulse generation position is deviated from the relationship. This means that the position of the origin changes depending on the interval when the user attaches the encoder.

  When the encoder is manufactured, the deviation of the origin position can be eliminated by assembling the detection head 820 so that the axial deviation between the light source 121 and the light receiving element 823 becomes sufficiently small. However, since it is necessary to assemble with high accuracy, there is a problem that it takes time and labor to assemble and the manufacturing cost increases.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a detection head and an optical encoder that can reduce the deviation of the generation position of the origin pulse without taking the time and effort of assembly. To do.

The detection head according to the present invention includes:
A light source;
A light receiving section in which a plurality of light receiving elements are arranged in the length measuring direction of the scale;
Origin pulse generating means for generating an origin pulse from the analog signal detected by the light receiving element;
A detection head comprising:
The light receiving element having a minimum amount of axial deviation from the light source is selected.

The optical encoder according to the present invention is:
The detection head described above;
A scale having an origin pattern;
Is provided.

The adjustment method of the optical encoder according to the present invention is as follows:
A scale having an origin pattern;
A detection head having a light source, a light receiving unit in which a plurality of light receiving elements are arranged in the length measuring direction of the scale, and an origin pulse generating unit that generates an origin pulse from an analog signal detected by the light receiving element;
A method for adjusting an optical encoder comprising:
Using one or more light receiving elements,
By detecting an origin pulse at an interval of two or more different scales and the detection head,
The light receiving element having a minimum amount of axial deviation from the light source is obtained.

Other optical encoder adjustment methods according to the present invention include:
A scale having an origin pattern;
A detection head having a light source, a light receiving unit in which a plurality of light receiving elements are arranged in the length measuring direction of the scale, and an origin pulse generating unit that generates an origin pulse from an analog signal detected by the light receiving element;
A method for adjusting an optical encoder comprising:
Generating an origin pulse with an interval between the detection head and the origin pattern as a first interval, and detecting a generation position of the origin pulse;
Changing an interval between the detection head and the origin pattern, generating an origin pulse as a second interval, and detecting a generation position of the origin pulse;
The amount of movement of the origin pulse when the interval between the detection head and the origin pattern is changed from the origin pulse generation position at the first interval and the origin pulse generation position at the second interval. Calculating
Calculating the amount of axial deviation between the light source and the light receiving element from the geometric relationship between the light source, the light receiving element and the origin pattern, and the amount of movement of the origin pulse;
A step of selecting the light receiving element having the smallest amount of axial deviation with respect to the light source from the calculated amount of axial deviation;
It is characterized by having.

  ADVANTAGE OF THE INVENTION According to this invention, the detection head and optical encoder which can reduce the shift | offset | difference of the origin pulse generation position can be provided, without taking the effort of an assembly.

1 is a perspective view illustrating a configuration of an optical encoder according to a first embodiment. 6 is a first half of a flowchart illustrating an adjustment method of the optical encoder according to the first embodiment. FIG. 5B is the second half of the flowchart showing the adjustment method of the optical encoder according to the first embodiment. It is the figure which looked at the light-receiving part of the optical encoder concerning Embodiment 1 from the scale side. FIG. 5 is a diagram illustrating a positional relationship among a light source, a light receiving element, and an origin pattern when the distance between the detection head and the scale is a design value of the optical encoder according to the first embodiment. In the optical encoder according to the first exemplary embodiment, it is a diagram illustrating an output signal when the distance between the detection head and the scale is a design value. FIG. 3 is a diagram illustrating a positional relationship among a light source, a light receiving element, and an origin pattern when the distance between a detection head and a scale is shifted from a design value in the optical encoder according to the first embodiment. In the optical encoder according to the first embodiment, it is a diagram illustrating an output signal when an interval between a detection head and a scale is shifted from a design value. In the conventional optical encoder, it is a 1st perspective view which shows a mode that a detection head moves on a scale. In the conventional optical encoder, it is a 2nd perspective view which shows a mode that a detection head moves on a scale. In the conventional optical encoder, it is a figure which shows the signal output when the space | interval of a detection head and a scale is made into a design value. In the conventional optical encoder, it is a figure which shows the positional relationship of a light source, a light receiving element, and an origin pattern when the space | interval of a detection head and a scale is made into a design value. In the conventional optical encoder, it is a figure which shows the positional relationship of a light source, a light receiving element, and an origin pattern when the space | interval of a detection head and a scale has shifted | deviated from the design value. In the conventional optical encoder, it is a figure which shows the signal output when the space | interval of a detection head and a scale has shifted | deviated from the design value. In the conventional optical encoder, it is a 1st perspective view which shows a mode that a detection head moves on a scale when there exists an axial shift of a light source and a light receiving element. In the conventional optical encoder, it is a 2nd perspective view which shows a mode that a detection head moves on a scale, when there exists an axial shift of a light source and a light receiving element. In the conventional optical encoder, it is a 3rd perspective view which shows a mode that a detection head moves on a scale when there exists an axial shift of a light source and a light receiving element. In the conventional optical encoder, it is a figure which shows the signal output when the space | interval of a detection head and a scale is made into a design value when there exists an axial shift of a light source and a light receiving element. In a conventional optical encoder, when the light source and the light receiving element are misaligned, the positional relationship between the light source, the light receiving element, and the origin pattern when the distance between the detection head and the scale is a design value. is there. In a conventional optical encoder, when the distance between the detection head and the scale is shifted from FIG. 19 without changing the position of the origin pattern in the length measuring direction, the light reflected by the origin pattern enters the light receiving element. FIG. FIG. 20 is a diagram illustrating a state in which light reflected by an origin pattern is incident on a light receiving element when a distance between a detection head and a scale is deviated from FIG. 19 in a conventional optical encoder. In the conventional optical encoder, it is a figure which shows the signal output when the space | interval of a detection head and a scale has shifted | deviated from the design value, when there exists an axial shift of a light source and a light receiving element.

[Embodiment 1]
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view illustrating a configuration of an optical encoder 100 according to the first embodiment. The optical encoder 100 is an incremental optical encoder. The optical encoder 100 includes a scale 110 and a detection head 120, and detects a relative movement amount of the detection head 120 with respect to the scale 110.

The scale 110 is an incremental scale, and has an origin pattern 111 and an incremental pattern 112. The longitudinal direction of the scale 110 is the length measuring direction.
The detection head 120 includes a light source 121, a light receiving unit 122, an incremental pattern detection unit 124, and a signal processing unit 130. In FIG. 1, the casing of the detection head 120 is omitted. The light source 121, the origin pattern 111, and the light receiving unit 122 are designed to ride on the same plane perpendicular to the length measurement direction of the scale 110.
The light source 121 emits divergent light. For example, an LED (Light Emitting Diode) can be used.

  The light receiving unit 122 receives the light reflected by the origin pattern 111. In the light receiving unit 122, two or more light receiving elements 123 are arranged. The arrangement direction of the light receiving elements 123 is parallel to the length measuring direction. The light receiving unit 122 has a length in the length measuring direction. Even if there is an assembly error when the light source 121 and the light receiving unit 122 are assembled to the detection head 120, at least one of the plurality of light receiving elements 123 comes to a position where there is no axial deviation with respect to the light source 121. ing. One optimal light receiving element 123 can be selected from a plurality of light receiving elements 123 and used.

Various methods are conceivable for selecting and using the optimum single light receiving element 123. On the substrate on which the light receiving elements 123 are arranged, the light receiving elements 123 may be selected by connecting wires to the light receiving elements 123 to be used by soldering. Further, a microcomputer may be incorporated so that the light receiving element 123 can be selected in accordance with an external switching command.
The selected light receiving element 123 detects the reflected light from the origin pattern 111 on the scale 110 and converts it into an analog signal. A method for selecting the optimum light receiving element 123 will be specifically described later.

  The incremental pattern detection unit 124 receives the light reflected by the incremental pattern 112 and detects a periodic signal corresponding to the incremental pattern 112. The relative movement amount of the detection head 120 can be detected from the change in the periodic signal when the detection head 120 moves.

The signal processing unit 130 includes an origin pulse generation unit 131 and a light receiving element selection processing unit 140.
The light receiving element selection processing unit 140 includes an origin pulse movement amount calculating unit 141, an axis deviation amount calculating unit 142, and an axis deviation minimum light receiving element selecting unit 143. The specific operations of the origin pulse movement amount calculation means 141, the axis deviation amount calculation means 142, and the axis deviation minimum light receiving element selection means 143 will be described in the flowcharts of FIGS.
2 and 3 are flowcharts showing an adjustment method of the optical encoder 100. FIG. Specifically, a procedure for selecting an optimum one from a plurality of light receiving elements 123 will be described.

  In the adjustment of the optical encoder 100, the movement amount of the origin pulse is evaluated while changing the distance and the positional relationship between the detection head 120 and the scale 110. In changing the distance and the positional relationship between the detection head 120 and the scale 110, a position adjusting jig is used (not shown). The position adjustment jig has a mechanism for changing the distance (z direction) between the detection head 120 and the scale 110 and a mechanism for moving the detection head 120 in the length measurement direction (x direction). Further, the displacement in the x direction and the z direction is measured by a displacement sensor.

  FIG. 4 is a view of the light receiving unit 122 as viewed from the scale 110 side. Of the plurality of light receiving elements arranged on the light receiving unit 122, the light receiving elements 123 (a) to 123 (g) are shown. The initial reference light receiving element is 123 (a). With reference to the light receiving element 123 (a), a light receiving element adjacent in the −x direction is 123 (b), and a light receiving element adjacent in the + x direction is 123 (c). The light receiving element 123 (a) is a light receiving element disposed at the center in the length measuring direction of the light receiving unit 122. In the design value, the light source 121 and the light receiving element 123 (a) are placed on a plane perpendicular to the length measurement direction of the scale 110.

  However, after actual assembly, an axis deviation occurs between the light receiving element 123 (a) and the light source 121, and they do not lie on one plane perpendicular to the length measurement direction of the scale 110. In FIG. 1, it is assumed that the light source 121 is on the plane P1, and the light receiving element 123 (a) is on the plane P2.

  FIG. 5 is a view of the optical encoder 100 viewed from the light source 121 side (corresponding to a view viewed from the arrow V in FIG. 1). In FIG. 5, the incremental pattern detection unit 124 is not shown for convenience of explanation. At this time, the distance between the light source 121 and the scale 110 is D1, and the distance between the scale 110 and the light receiving unit 122 is D2. Adjustment is performed using the three adjacent light receiving elements 123 (a) to 123 (c) on the light receiving unit 122.

The adjustment method of the optical encoder 100 will be described along the flow of FIGS.
First, the light receiving elements 123 (a) to 123 (c) are connected to the origin pulse generating means 131 using the interval between the detection head 120 and the scale 110 as a design value (ST201). Thereafter, the detection head 120 is relatively moved in the length measuring direction of the scale 110 (ST202).

  The light receiving elements 123 (a) to 123 (c) receive the reflected light from the origin pattern 111 and generate pulses by the origin pulse generator 131. Then, the generation position of the generated origin pulse is detected for each of the light receiving elements 123 (a) to 123 (c) (ST203). At this time, the origin pulse generation position in the light receiving element 123 (a) is x = x1a, the origin pulse generation position in the light receiving element 123 (b) is x = x1b, and the origin pulse generation position in the light receiving element 123 (c) is Let the generation position be x = x1c. FIG. 6 is a diagram showing an analog signal generated in the light receiving element 123 (a) and an origin pulse generated from the analog signal.

Next, the origin pulse generation positions x1a to x1c at the light receiving elements 123 (a), 123 (b), and 123 (c) are stored in the origin pulse movement amount calculation means 141 (ST204).
Next, the distance between the detection head 120 and the scale 110 is changed by ΔD using a jig (ST205). The fluctuation amount ΔD does not need to be measured accurately. Then, with the distance between the detection head 120 and the scale 110 changed by ΔD, the detection head 120 is relatively moved in the length measurement direction of the scale 110 (ST206).

  Thereafter, the origin pulse is generated again, and the origin pulse generation position is detected for each of the light receiving elements 123 (a) to 123 (c) (ST207). At this time, the origin pulse generation position in the light receiving element 123 (a) is x = x2a, the origin pulse generation position in the light receiving element 123 (b) is x = x2b, and the origin pulse generation position in the light receiving element 123 (c) is Let the generation position be x = x2c.

  As shown in FIG. 7, in this case, the distance between the light source 121 and the scale 110 is D1 + ΔD, and the distance between the scale 110 and the light receiving unit 122 is D2 + ΔD. The origin pulse generation positions x2a to x2c in the light receiving elements 123 (a), 123 (b), 123 (c) are stored in the origin pulse movement amount calculation means 141 (ST208). In FIG. 7, as in FIG. 5, the incremental pattern detection unit 124 is not shown for convenience of explanation.

  Next, the origin pulse movement amount calculation means 141 detects the origin head from the origin pulse generation positions x1a to x1c at the design value interval and the origin pulse generation positions x2a to x2c at an interval shifted by ΔD from the design value. The movement amount of the origin pulse when the distance between 120 and scale 110 is changed by ΔD is calculated (ST209). FIG. 8 is a diagram illustrating a signal output from the light receiving element 123 (a) when the interval between the detection head 120 and the scale 110 is shifted from the design value.

  At this time, the movement amount of the origin pulse when the reference light receiving element 123 (a) is used is XA, the movement amount of the origin pulse when the light receiving element 123 (b) is used is XB, and the light receiving element 123 (c). Let XC be the amount of movement of the origin pulse when using. XA = x2a-x1a, XB = x2b-x1b, XC = x2c-x1c.

Next, the axis deviation amount calculation means 142 calculates the light source 121, the light receiving element 123 (a), and the geometric relationship between the light source 121, the origin pattern 111, and the light receiving element 123, and the movement amounts XA to XC of the origin pulse. Is calculated (ST210).
When the pitch of the light receiving elements 123 is P, the following formula (1) is established for the axis deviation amount L.

  Next, the minimum misalignment light receiving element selection unit 143 is closest to a plane perpendicular to the scale 110 passing through the light source 121 so that the misalignment between the light source 121 and the light receiving element 123 is minimized based on the calculated misalignment amount. The light receiving element 123 is selected (ST211). In FIG. 5, the light receiving element 123 (h) directly under the light source is selected.

  As described above, in the optical encoder 100 according to the present invention, by selecting an optimum light receiving element from among the plurality of light receiving elements 123 on the light receiving unit 122, the axis shift between the light source 121 and the light receiving element 123 is performed. Can be reduced. If the light receiving element 123 having no axis deviation is selected at the time of product shipment, even if the interval between the detection head 120 and the scale 110 is deviated from an intended value by the user's assembly after that, the origin position does not deviate. . Therefore, the user does not have to perform home calibration.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention. In the above embodiment, the optimum light receiving element is obtained from the appropriate three light receiving elements by calculation, but the present invention is not limited to this. For example, if all the light receiving elements are tried one by one, an optimum light receiving element can be found. Furthermore, although the light receiving element 123 (a) is used as a reference, the reference may be any light receiving element, and the light receiving element 123 (b) or 123 (c) may be used as a reference. In addition, the present invention is not limited to a linear encoder, but can also be applied to a rotary encoder.

DESCRIPTION OF SYMBOLS 100 Optical encoder 110 Scale 111 Origin pattern 112 Incremental pattern 120 Detection head 121 Light source 122 Light receiving part 123 Light receiving element 124 Incremental pattern detection part 130 Signal processing part 131 Origin pulse generation means 140 Photoreception element selection processing part 141 Origin pulse movement amount calculation means 142 Axis deviation amount calculation means 143 Axis deviation minimum light receiving element selection means

Claims (4)

A light source;
A light receiving section in which a plurality of light receiving elements are arranged in the length measuring direction of the scale;
Origin pulse generating means for generating an origin pulse from the analog signal detected by the light receiving element;
A detection head comprising:
The detection head, wherein the light receiving element having a minimum amount of axial deviation from the light source is selected. A detection head according to claim 1;
A scale having an origin pattern;
An optical encoder comprising: A scale having an origin pattern;
A detection head having a light source, a light receiving unit in which a plurality of light receiving elements are arranged in the length measuring direction of the scale, and an origin pulse generating unit that generates an origin pulse from an analog signal detected by the light receiving element;
A method for adjusting an optical encoder comprising:
Using one or more light receiving elements,
By detecting an origin pulse at an interval of two or more different scales and the detection head,
A method for adjusting an optical encoder, comprising: obtaining the light receiving element having a minimum amount of axial deviation from the light source. A scale having an origin pattern;
A detection head having a light source, a light receiving unit in which a plurality of light receiving elements are arranged in the length measuring direction of the scale, and an origin pulse generating unit that generates an origin pulse from an analog signal detected by the light receiving element;
A method for adjusting an optical encoder comprising:
Generating an origin pulse with an interval between the detection head and the origin pattern as a first interval, and detecting a generation position of the origin pulse;
Changing an interval between the detection head and the origin pattern, generating an origin pulse as a second interval, and detecting a generation position of the origin pulse;
The amount of movement of the origin pulse when the interval between the detection head and the origin pattern is changed from the origin pulse generation position at the first interval and the origin pulse generation position at the second interval. Calculating
Calculating the amount of axial deviation between the light source and the light receiving element from the geometric relationship between the light source, the light receiving element and the origin pattern, and the amount of movement of the origin pulse;
A step of selecting the light receiving element having the smallest amount of axial deviation with respect to the light source from the calculated amount of axial deviation;
A method for adjusting an optical encoder, comprising:

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