JPH11148844A - Optical encoder and method for mounting securing element of optical encoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow an assembly work using the same re-flow solder bath as other substrate assembly works being immune to noise. SOLUTION: Related to an optical encoder provided with a securing element 6 comprising a plurality of photodetecting element and a substrate 3 for fitting the fitting-side element 6, a sub-substrate 7 comprising a curvature structure is employed as such sub-substrate as comprising a pattern for connecting to a common electrode of the fitting-side element 6 and an electrode of each photo- detecting element. Here, the securing element 6 is connected to the pattern of the sub-substrate 7, and the sub-substrate 7 and the substrate 3 are electrically connected by soldering with a positioning member for positioning on the substrate 3 with an arbitrary position as reference.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical encoder having a fixed-side element in which a slit is directly formed on a light-receiving surface of a light-receiving element by photo-etching or the like, and a method of mounting the fixed-side element of the optical encoder. Also, the present invention relates to an optical encoder and a method of attaching a fixed-side element of the optical encoder, which can perform an assembling operation using a reflow soldering tank similar to other substrate assembling operations and is resistant to noise.

[0002]

2. Description of the Related Art Conventionally, in the case of an optical encoder in which a fixed-side element opposed to a rotating disk having a plurality of slits arranged in a circumferential direction through a gap is fixed to a substrate, the surface of the substrate on which the fixed-side element is mounted is the same as that of the optical encoder. In order to dispose other chip components on both sides of the opposite side to which the fixed side element is mounted, and to keep the gap between the fixed side element and the rotating disk small, insert a spacer between the fixed side element and the substrate. In addition, there has been proposed a device in which the height of the fixed-side element from the substrate plane is higher than the height of the other chip components from the substrate plane (for example, Japanese Utility Model Application Laid-Open No. 62-24315: No. 1). Conventional example). However, in the optical encoder of the first conventional example, the chip components other than the fixed-side element are connected to the pattern provided on the substrate by soldering, and the connection between the electrode of the solid-side element and the pattern provided on the substrate is not sufficient. Since the fixing is performed by wire bonding of aluminum or the like, if the fixed-side element breaks down or a connection failure occurs, there is a problem that it cannot be easily removed. To solve the problem of the optical encoder of the first conventional example, Japanese Patent Application No. 7-172 is proposed.
No. 808 discloses an “optical encoder and a method for attaching a fixed-side element of the optical encoder”. FIG.
FIG. 11 is a cross-sectional view for explaining the structure of the optical encoder of the second conventional example, and FIG. 11 is a front cross-sectional view along the BB cross section of FIG. 10 and 11, an optical encoder according to a second conventional example includes a fixed element 6 having a plurality of light receiving elements, a substrate 3 'for fixing the fixed element 6, and a fixed element 6 via a gap. In an optical encoder provided with a rotating disk 5 which opposes, a sub-substrate 7 'having a pattern for connecting to a common electrode of the fixed-side element 6 and an electrode of each light-receiving element is provided. It is arranged between and. FIG. 12 is a perspective view of the fixed-side element 6 placed on the sub-board 7 ′ for explaining the electrical connection between the fixed-side element 6 and the sub-board 7. As shown in the figure, in the optical encoder of the second conventional example, the light receiving element electrodes C1, C2, C3, C4 of the fixed side element 6 and the pattern electrodes 71 ', 72', 73 ', 74 of the sub-substrate 7'. '
Are electrically connected by wire bonding of aluminum or the like.

[0003]

However, in the optical encoder according to the second conventional example, as described above, a special operation called wire bonding is performed when the fixed side element of the optical encoder is attached, so that a wire is required. It is necessary to pay close attention to the handling of the light receiving element after it is attached by bonding so as not to cut the wire, and since wire bonding is a special operation, it increases the cost of the optical encoder, and furthermore, However, due to the structure, the area around the fixed side element cannot be shielded, and there is a situation that it is susceptible to noise. The present invention has been made in view of the above-mentioned conventional problems, and eliminates the need for a special operation called wire bonding in a connection operation between a fixed-side element and a sub-substrate, and reflow soldering similar to other substrate assembly operations. It is an object of the present invention to provide an optical encoder capable of performing an assembling operation using a tank and a method of attaching a fixed-side element of the optical encoder. Another object of the present invention is to provide an optical encoder that is structurally resistant to noise by shielding the periphery of the fixed element.

[0004]

According to a first aspect of the present invention, there is provided an optical encoder comprising: a fixed element having a plurality of light receiving elements; and a substrate for fixing the fixed element. And an optical encoder comprising a rotating disk that opposes the fixed element via a gap,
Including a pattern for connecting to a common electrode of the fixed side element and an electrode of each light receiving element, a sub-substrate having a bent structure is provided, and the sub-substrate is arranged between the fixed side element and the substrate Is what is done. An optical encoder according to a second aspect is the optical encoder according to the first aspect, further comprising a slit plate that can move linearly instead of the rotary disk. An optical encoder according to a third aspect is the optical encoder according to the first or second aspect, wherein the sub-board functions as a spacer for the fixed-side element. Also,
An optical encoder according to a fourth aspect is the optical encoder according to the first, second, or third aspect, wherein the sub-substrate includes a positioning portion for fixing the sub-substrate to the substrate. An optical encoder according to a fifth aspect of the present invention is the optical encoder according to the first, second, third or fourth aspect, wherein the sub-substrate includes a support for positioning and holding the light receiving element. It is. Further, the optical encoder according to claim 6 is based on claim 1,
6. The optical encoder according to 2, 3, 4, or 5, wherein the sub-substrate includes a conductive substrate, and the sub-substrate is connected to a stable potential portion of an electric circuit of the substrate. Things. Furthermore, an optical encoder according to claim 7 is the optical encoder according to claim 1, 2, 3, 4, 5, or 6, wherein the sub-board is electrically connected to the board. Has a shape curled to the side opposite to the substrate. A method for attaching a fixed-side element of an optical encoder according to claim 8 is a method for attaching a fixed-side element having a plurality of light-receiving elements to a substrate, the method comprising: And fixing the fixed-side element to a sub-substrate having a bent structure, including a pattern for connecting to an electrode of each light-receiving element, and connecting the fixed-side element with the pattern of the sub-substrate; The sub-substrate and the substrate are electrically connected by soldering by fixing the sub-substrate and the substrate by a positioning member that positions the sub-substrate relative to an arbitrary position.

In the optical encoder according to the first aspect of the present invention, a fixed element having a plurality of light receiving elements, a substrate for fixing the fixed element, and a rotating disk opposed to the fixed element via a gap are provided. The optical encoder according to claim 8, wherein a sub-substrate having a bent structure is used as a sub-substrate including a pattern for connecting to the common electrode of the fixed side element and the electrode of each light receiving element. In the method of mounting the fixed-side element of the type encoder, after fixing the fixed-side element to the sub-board, the pattern of the sub-board and the fixed-side element are connected, and the board is fixed with a positioning member that positions the board with respect to an arbitrary position. Thus, the sub-substrate and the substrate are electrically connected by soldering. As described above, since the sub-substrate having the bent structure is employed, the shape for supporting the fixed-side element can be easily formed with accurate mechanical precision. In addition, in the work of electrically connecting the fixed-side element and the sub-board and mechanically fixing the same, the special work of wire bonding becomes unnecessary,
Assembly work can be performed using the same reflow soldering tank as other board assembly work, reducing the manufacturing time and replacing the solid side element even if the fixed side element is defective. As a result, the reliability of the fixed-side element portion is improved. In the optical encoder according to the second aspect, by replacing the rotary disk with a slit plate that can move linearly, the present invention can be applied not only to a rotary optical encoder but also to a linear optical encoder.
Further, in the optical encoder according to claim 3, the sub-substrate functions as a spacer for the fixed-side element, for example, the height of the fixed-side element from the substrate plane is increased, and the sub-substrate is also provided on the same substrate plane as the light-receiving element. By mounting the components, the outer diameter of the substrate can be made smaller, and the cost of the device can be reduced. Further, in the optical encoder according to the fourth aspect, by providing the positioning portion for fixing the sub-substrate to the substrate on the sub-substrate, the fixed-side element can be accurately positioned even during reflow soldering. Further, in the optical encoder according to the fifth aspect, a support portion for positioning and holding the light receiving element is provided on the sub-substrate, and the sub-substrate and the substrate are fixed, and the position is fixed and then soldered. It is possible to eliminate the problem that the sub-substrate moves due to vibration at the time of the soldering or adsorption during melting of the solder, and the fixed-side element can be securely fixed to the substrate. Further, in the optical encoder according to claim 6, the sub-substrate includes a base material having conductivity,
By connecting the base material of the sub-substrate to the stable potential portion of the electric circuit of the substrate, the entire sub-substrate can be provided with a shielding effect, and the periphery of the fixed-side element is shielded to improve noise immunity. An optical encoder can be realized. Furthermore, in the optical encoder according to claim 7, the tip of the sub-substrate electrically connected to the substrate has a shape curled to the opposite side to the substrate, so that the amount of solder in the reflow solder is normal and the solder is normal. It is possible to visually check whether the work is being performed reliably.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an optical encoder and a method of attaching a fixed-side element of the optical encoder according to the present invention will be described with reference to [first embodiment], [second embodiment], [third embodiment]. Embodiment] will be described in detail with reference to the drawings. [First Embodiment] FIG. 1 is a sectional view illustrating the structure of an optical encoder according to a first embodiment of the present invention. In the figure, the same reference numerals are given to the portions that overlap with FIG. 10 (second conventional example). In the figure, 1 is an encoder case, 2 is a base fixed to the encoder case 1, 3
Is a substrate fixed to the base 2 and has wiring patterns on both sides. Reference numeral 31 is a reference hole into which a positioning pin is inserted. Reference numeral 4 denotes an L fixed to the base 2 with the substrate 3 interposed therebetween.
ED case, 41 is LE fixed to LED case 4
D and 5 are rotating disks in which a plurality of slits are arranged in a circumferential direction, and are fixed to a rotating shaft 51 via a disk hub 52. Reference numeral 6 denotes a fixed element, which faces the rotating disk 5 via a gap. Further, 7 is a sub-substrate provided between the fixed-side element 6 and the substrate 3, and 8 is a chip component attached to both surfaces of the substrate 3. That is, in the optical encoder of the present embodiment, the sub-substrate 7 having the spacer function and the bending structure is provided between the fixed-side element 6 and the substrate 3, and the fixed-side element 6 has a height from the substrate 3. As a result, the chip component 8 is mounted on the same substrate plane as the fixed-side element 6. Of course, the sub-substrate 7 having a size such that the height of the fixed-side element 6 is higher than the height of the chip component 8 is used. Therefore, in the optical encoder of the present embodiment, the area on which the components can be mounted is about twice as large as the front and back sides, the outer diameter (radial direction) of the substrate 7 can be reduced, and the size of the entire optical encoder can be reduced. Can be miniaturized. As shown in FIG.
Light receiving elements 61, 62, 63, and 64 composed of photodiodes A (+), A (-), B (+), and B (-) are provided on the surface, and connected to the electrodes C1, C2, C3, and C4, respectively. ing. In addition, a common electrode (not shown) is provided on the back surface. When the common electrode is used as the cathode of the light receiving element, the electrodes C1, C2, C3, and C4 become anodes.
The polarity may be reversed. FIG. 2 shows four sets of photodiodes A (+), A (-), B (+), and B (-) having a plurality of slits as the fixed-side element 6, but are arranged on the light receiving surface. The number of the photodiodes described above is one or more, and the number of sets may be one or more. Needless to say, the photodiode is not limited to the photodiode having the structure shown in FIG.

Next, the sub-board 7 will be described. FIG.
FIG. 3 is a cross-sectional view illustrating a cross-sectional structure of a sub-substrate 7. As shown in the figure, the sub-board 7 is a base metal (metal base).
701, an insulating layer 702, a pattern 703, and a resist 704. The sub-substrate 7 is a metal-base printed single-sided wiring board having a bent structure (for example, trade name “Cool Base”; manufactured by Mitsui Chemicals, Inc.).
A thin aluminum substrate having a thickness of about 0.1 [mm] is used. 4 is a perspective view of the sub-substrate 7, and FIG. 5 is a cross-sectional view taken along the line AA of FIG. As shown in FIGS. 4 and 5, the sub-substrate 7 includes electrode patterns T1 and C1 corresponding to the electrodes C1, C2, C3, and C4 of the fixed-side element 6.
T2, T3, and T4, a common electrode T5 corresponding to the back surface common electrode of the light receiving surface, and electrode portions T11 (not shown), T12 (not shown), T13, and T14 connected to the substrate 3 are exposed. The other pattern (the dotted line in the figure) has a structure in which the pattern surface is protected by a resist. Further, supporting portions 71, 72, 73 are arranged at three positions on the sub-board 7 so that the fixed-side element 6 and the sub-board 7 can be accurately positioned. Further, the sub-substrate 7 is provided with a positioning portion 74 so that the sub-substrate 7 and the substrate 3 can be accurately positioned and fixed. Since the sub-board 7 is manufactured using a dedicated bending / punching die, high-precision dimensions are ensured. Therefore, the positioning of the fixed element 6 is
This can be performed with high precision, and when the function of the solid-state element 6 as a spacer is considered, the precision of the height dimension can be accurately manufactured. Next, a method of fixing the fixed-side element 6, the sub-substrate 7, and the substrate 3 will be described. FIG. 6 is a diagram illustrating an assembly process for connecting and fixing the fixed-side element 6, the sub-board 7, and the main board 3. First, as shown in FIGS. 6A and 6B, the electrode portions (C1, C
2, C3, C4) and common electrode pattern T5 of sub-substrate 7
Is applied with high-temperature cream solder, and the fixed-side element 6 is fixed to the sub-substrate 7. In this state, the electrodes are passed through the reflow solder tank, and the respective electrode portions C1, C2, C3, C
4 and the back surface common electrode are connected to the electrode patterns T1, T2, T3, T4, T5 of the sub-substrate 7, respectively. Thereafter, as shown in FIG. 6C, another chip component 8 is placed on the substrate 3.
In the same manner as described above, the sub-substrate 7 on which the fixed-side element 6 is mounted is placed, and the positioning pins 75 are set up on the substrate 3 in which holes are formed in advance in the same size as the positioning portions 74 of the sub-substrate 7, so that the sub-substrate 7 is accurately positioned. And then pass through the reflow solder tank.
In this step, the electrode portions T11, T12, T1 of the sub-substrate 7 are formed.
3, T14 and the pattern of the substrate 3 are electrically connected by solder. After the reflow soldering, the optical encoder is completed except for the positioning pins 75. The reason why the sub-substrate 7 is accurately fixed to the substrate 3 using the positioning pins 75 is that it is necessary to exactly match the mechanical dimensions of the fixed side element 6 and the slit portion of the rotary disk 5. Further, since the fixed-side element 6 and the sub-substrate 7 are connected using high-temperature solder, the fixed-side element 6 is not displaced even after passing through the second reflow solder bath. As described above, according to the optical encoder of the present embodiment, the sub-substrate 7 having the spacer function and the bending structure is disposed between the fixed-side element 6 and the substrate 3, and the substrate plane of the fixed-side element 6 By mounting the components on the same side of the board as the light-receiving element,
The outer diameter of the substrate 3 can be reduced. Further, by using the sub-substrate 3 having the bent structure, a shape for supporting the fixed-side element 6 can be easily formed with accurate mechanical precision. In the manufacturing process,
Since the soldering is performed in the reflow soldering tank, the special operation of wire bonding is not required, and the manufacturing time is reduced. As a result, the reliability of the fixed-side element portion is improved. Further, by providing the support portions 71, 72, 73 for fixing the fixed-side element 6 to the sub-board 7, the fixed-side element 6 can be accurately positioned even during reflow soldering. further,
A positioning portion 74 is provided on the sub-substrate 7, and the positioning portion 74 of the sub-substrate 7 and the hole of the substrate 3 are fixed with the positioning pins 75, and the position is fixed and then soldered. It is possible to eliminate the problem that the sub-substrate 7 moves due to vibration or adsorption at the time of solder melting, so that the fixed-side element 6 can be securely fixed to the substrate 3.

Second Embodiment FIG. 7 is a perspective view centering on a sub-board of an optical encoder according to a second embodiment of the present invention. In the optical encoder of the present embodiment, the screw 76 is used for attaching the sub-substrate 7 to the substrate 3 by the positioning portion 74. Further, in the present embodiment, since the folded portion of the positioning portion 74 is a conductive metal base, the folded portion is electrically connected to the stable potential portion of the electric circuit of the substrate 3 so that the sub-board 7 can have a shielding effect. That is, there is an effect that the peripheral portion of the fixed-side element 6 is shielded and becomes strong against noise. In addition to these, the present embodiment also has features equivalent to those of the sub-substrate 7 in the above-described first embodiment. [Third Embodiment] FIG. 8 is a perspective view of a sub-board and a fixed element of an optical encoder according to a third embodiment of the present invention. 8A is a perspective view of the sub-board 77, and FIG. 8B is a perspective view of the fixed element 6a. As shown in FIG. 8B, the fixed-side element 6a according to the present embodiment includes:
Light receiving output electrodes C1a, C2a, C3a, C4a, C5a
Have a structure arranged on the light receiving surface. Also,
As shown in FIG. 8A, the sub-board 77 has a structure in which a window corresponding to the size of the light-receiving element is opened in the center of the sub-board 77 because all electrodes of the fixed-side element 6a are on the light-receiving surface. It has become. Further, a portion corresponding to the side surface of the fixed side element 6a is provided with a positioning portion 78 having a shape curved inward by applying the elasticity of the metal base material of the sub-substrate 77. In the case of the second reflow soldering at the time of fixing or in case of emergency, the fixed side element 6 does not drop. FIG. 9 is a cross-sectional view of the fixed element 6a, the sub-board 77, and the board 3 of the optical encoder according to the present embodiment. As shown in FIG.
The shape of the tip of 7 is curled to the opposite side of the substrate 3 so that it is possible to visually check whether the amount of solder in the reflow solder is normal and the soldering operation is performed reliably. In addition to these, the present embodiment also has features equivalent to those of the sub-substrate 7 in the above-described first embodiment. In the optical encoders of the first, second and third embodiments described above, the rotary optical encoder provided with the rotary disk 5 has been described as an example. The present invention is also applicable to a linear optical encoder including a slit plate having a plurality of slits in the direction in which the slit is formed.

[0009]

As described above, according to the optical encoder and the method for mounting the fixed element of the optical encoder of the present invention, the pattern for connecting to the common electrode of the fixed element and the electrode of each light receiving element is provided. A sub-substrate having a bent structure is adopted as a sub-substrate including, after fixing the fixed-side element to the sub-substrate, connecting the pattern of the sub-substrate and the fixed-side element, and positioning the substrate with reference to an arbitrary position. Since the sub-substrate and the substrate are electrically connected by soldering by fixing with the positioning member, the shape supporting the fixed-side element can be easily formed with accurate mechanical precision, and In the work of electrically connecting the fixed side element and the sub-board and mechanically fixing it, the special work of wire bonding is not required, and the same re-work as other board assembly work is required. The assembly work can be performed using a low solder tank, which reduces the manufacturing time, and makes it easy to replace the solid side element even if the fixed side element is defective. It is possible to provide an optical encoder in which the reliability of the element section is improved, and a method for attaching the fixed side element of the optical encoder. Further, according to the optical encoder of the present invention, by replacing the rotary disk with a slit plate that can move linearly, the invention can be applied not only to the rotary type but also to a linear type optical encoder. Further, according to the optical encoder of the present invention, the sub-substrate functions as a spacer for the fixed-side element, for example, the height of the fixed-side element from the substrate plane is increased, and the sub-substrate is also arranged on the same substrate plane as the light-receiving element. Since the components are mounted, the outer diameter of the substrate can be made smaller, and an optical encoder with reduced device cost can be provided. Further, according to the optical encoder of the present invention, by providing the positioning portion for fixing the sub-substrate to the substrate on the sub-substrate, the fixed-side element can be accurately positioned even during reflow soldering. According to the optical encoder of the present invention,
A support section is provided to position and hold the light receiving element.The sub board and the board are fixed, and the solder is fixed after positioning.Therefore, the sub board may be damaged due to vibration during reflow soldering or suction during solder melting. Problems such as movement can be eliminated, and the fixed-side element can be securely fixed to the substrate. Further, according to the optical encoder of the present invention, since the sub-substrate is provided with the conductive base material and the base material of the sub-substrate is connected to the stable potential portion of the electric circuit of the sub-board, It is possible to provide an optical encoder in which a shield effect can be provided as a whole and the peripheral portion of the fixed-side element is shielded to improve noise immunity. Further, according to the optical encoder of the present invention, the tip of the sub-substrate electrically connected to the substrate has a shape curled to the opposite side to the substrate, so that the amount of solder in the reflow solder is normal and the solder is normal. It is possible to visually check whether the work is being performed reliably.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of an optical encoder according to a first embodiment of the present invention.

FIG. 2 is a plan view illustrating a structure of a fixed-side element according to the first embodiment.

FIG. 3 is a cross-sectional view illustrating a cross-sectional structure of a sub-substrate according to the embodiment.

FIG. 4 is a perspective view of a sub board according to the first embodiment.

FIG. 5 is a cross-sectional view taken along the line AA of the sub-board of FIG. 4;

FIG. 6 is an explanatory diagram illustrating an assembly process for connecting and fixing the fixed-side element, the sub-substrate, and the substrate according to the first embodiment.

FIG. 7 is a perspective view centering on a sub-board of an optical encoder according to a second embodiment of the present invention.

FIG. 8 is a perspective view of a sub-board and a fixed-side element of an optical encoder according to a third embodiment of the present invention.

FIG. 9 shows a fixed-side element 6a and a sub-board 7 of the third embodiment.
FIG. 7 is a cross-sectional view of 7 and a substrate 3.

FIG. 10 is a cross-sectional view illustrating the structure of an optical encoder according to a second conventional example.

FIG. 11 is a front sectional view taken along the line BB of FIG. 10;

FIG. 12 is an explanatory diagram illustrating electrical connection between the fixed-side element and the sub-board, and is a perspective view of a state where the fixed-side element is mounted on the sub-board.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Encoder case 2 Base 3, 3 'board 31 Reference hole 4 LED case 41 LED 5 Rotating disk 51 Rotating axis 52 Disk hub 6 Fixed side element 7, 7', 77 Sub-substrate T1, T2, T3, T4 Sub-substrate electrode T5 Sub-board common electrodes T11, T12, T13, T14 Electrodes connected to main board 71, 72, 73 Sub-board support 74 Sub-board positioning 75 Positioning pin 76 Screw 78 Positioning 701 Base metal (metal base) 702 Insulating layer 703 pattern 704 resist 8 chip part C5 fixed side element common electrode

Claims (8)

[Claims] A fixed-side element having a plurality of light-receiving elements;
In an optical encoder having a substrate for fixing the fixed-side element and a rotating disk opposed to the fixed-side element via a gap, for connecting to a common electrode of the fixed-side element and an electrode of each light-receiving element. An optical encoder comprising a sub-substrate including a pattern and having a bent structure, wherein the sub-substrate is arranged between the fixed-side element and the substrate. 2. The optical encoder according to claim 1, further comprising a slit plate that can move linearly instead of the rotating disk. 3. The device according to claim 1, wherein the sub-substrate functions as a spacer for the fixed-side element.
The optical encoder according to 1. 4. The optical encoder according to claim 1, wherein the sub-board has a positioning portion for fixing the sub-board to the board. 5. The optical encoder according to claim 1, wherein the sub-substrate has a support for positioning and holding the light receiving element. 6. The substrate according to claim 1, wherein the sub-substrate has a substrate having conductivity, and connects the substrate of the sub-substrate to a stable potential portion of an electric circuit of the substrate. 3,4
Or the optical encoder according to 5. 7. The sub-substrate according to claim 1, wherein the tip of the sub-substrate electrically connected to the substrate has a shape curled to the side opposite to the substrate.
The optical encoder according to 2, 3, 4, 5, or 6. 8. A fixed element mounting method for an optical encoder for fixing a fixed element having a plurality of light receiving elements to a substrate, wherein a pattern for connecting to a common electrode of the fixed element and an electrode of each light receiving element is provided. Including, fixing the fixed-side element to a sub-substrate having a bent structure, connecting the pattern of the sub-board and the fixed-side element,
Fixing the sub-board and the board electrically by soldering by fixing the board to the board with an arbitrary position as a reference, and fixing the optical encoder to the fixed side of the optical encoder. Element mounting method.