JP4775750B2 - Optical encoder and optical encoder manufacturing method - Google Patents

Description

[0001]
BACKGROUND 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 photoetching or the like.
[0002]
[Prior art]
Conventionally, a fixed-side element including a plurality of light-receiving elements, a common electrode of the fixed-side elements, and a pattern for connecting to the electrodes of each light-receiving element are fixed, and the sub-board having a bent structure and the fixed-side element are fixed In an optical encoder having a substrate and a rotating disk facing the fixed-side element via a gap, the sub-substrate is disposed between the fixed-side element and the substrate to fix the fixed-side element to the substrate. (For example, JP-A-11-148844). In this case, the positioning of the fixed-side element with respect to the substrate is based on the external dimensions and attachment holes of the sub-board.
[0003]
[Problems to be solved by the invention]
However, such a conventional optical encoder has the following problems.
(1) Since the sub-substrate having a bent structure is manufactured by press working, an outer shape processing dimension error is about ± 0.1 mm, and it is not possible to accurately attach both in the connection process between the fixed side element and the sub-substrate.
(2) Even when the sub-substrate and the substrate having a bent structure are fixed, there is an attachment dimensional error of about ± 0.1 mm, and the sub-substrate and the substrate cannot be attached accurately.
Therefore, at the time of assembly, these dimensional errors are overlapped to generate a positioning error of maximum ± 0.2 mm, and there is a problem that the fixed side element cannot be fixed to the substrate at an accurate position. As a result, the mechanical dimensions of the fixed-side element and the slit portion of the rotating disk are shifted, and there is a problem that an accurate detection signal cannot be obtained from the optical encoder.
The present invention has been made to solve such a problem, and an object of the present invention is to provide an optical encoder capable of accurately mounting a fixed side element at a reference position.
[0004]
[Means for Solving the Problems]
In order to solve the above problems, the present invention includes a fixed side element including a plurality of light receiving elements, a pattern for connecting to the common electrode of the fixed side element and the electrode of each light receiving element, and has a bent structure. In the optical encoder having a sub-substrate, a substrate for fixing the fixed-side element, and a movable disk facing the fixed-side element via a gap, a part of the outer shape of the fixed-side element is formed on the sub-substrate. An exposed fixed-side element exposed portion is provided, and an attachment reference portion for attaching the fixed-side element to a reference position is provided on the substrate.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a side sectional view showing a rotary optical encoder in an embodiment of the present invention. 2A and 2B are perspective views showing an assembly process for connecting and fixing the sub-board and the fixed-side element in the embodiment of the present invention. FIG. 2A shows the sub-board, and FIG. 2B shows the connection and fixing inside the sub-board. (C) shows a state in which the sub-board and the fixed element are connected and fixed. FIG. 3 is a perspective view showing an assembly process for connecting and fixing the sub-board and the fixed-side element to the board in the embodiment of the present invention. FIG. 3A shows a positioning jig for positioning the fixed-side element on the board. (B) shows a state in which the stationary side element is attached to the substrate together with the sub-substrate using a positioning jig.
In FIG. 1, 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 wiring patterns are provided on both sides. Reference numeral 31 denotes an attachment reference portion, which is constituted by a reference hole for inserting a positioning pin, for example. Reference numeral 4 denotes an LED case fixed to the base 2 with the substrate 3 interposed therebetween, 41 denotes an LED fixed to the LED case 4, and 5 denotes a rotating disk in which a plurality of slits are arranged in the circumferential direction. It is fixed via the hub 52. Reference numeral 6 denotes a fixed-side element that faces the rotating disk 5 through a gap. Further, 7 is a sub-board provided between the fixed element 6 and the board 3, and 8 is a chip component attached to both sides of the board 3. That is, in the optical encoder of the present invention, the sub-substrate 7 having a spacer function and a bent structure is provided between the fixed-side element 6 and the substrate 3, and the fixed-side element 6 has a high 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 dimension such that the height of the fixed side element 6 is higher than the height of the chip component 8 is used.
In FIG. 2, the sub-substrate 7 includes electrode patterns T1, T2, T3, T4 corresponding to the electrodes C1, C2, C3, C4 of the fixed side element 6, and a common electrode T5 corresponding to the back surface common electrode C5 of the light receiving surface. The electrode portions T11 (not shown), T12 (not shown), T13, and T14 connected to the substrate 3 are exposed, and the surface of the other patterns is protected by a cover film and a resist.
The sub-board 7 is manufactured using a dedicated bending / punching die.
Further, the fixed-side element exposure portion A is formed by cutting out two corner portions of the sub-substrate 7. On the fixed side element 6, electrode patterns T1, T2, T3, T4 of four light receiving elements and a common electrode T5 corresponding to the back surface common electrode C5 of the light receiving surface are arranged.
Next, a method for fixing the fixed element 6, the sub-substrate 7, and the substrate 3 will be described.
First, high temperature cream solder (not shown) is applied to the electrode portions C1, C2, C3, C4 and the common electrode C5 of the fixed side element 6, and the fixed side element 6 is fixed to the sub-substrate 7 (FIGS. 2A and 2B). )).
In this state, it passes through the reflow solder tank, and each electrode portion of the fixed side element 6 is connected to the electrode pattern of the sub-substrate 7 (FIG. 2C).
Thereafter, as in the case of the other chip components 8, the sub-board 7 on which the fixed-side element 6 is mounted is placed on the board 3 and the reference hole 31 for the attachment reference is opened, as shown in FIG. For example, a fixed-side element positioning jig 75 made of a positioning pin or the like is fitted into the reference hole 31 (FIG. 3B), and the sub-substrate 7 is accurately positioned and fixed, and then passed through the reflow solder tank. In this step, the electrode portion of the sub-substrate 7 and the pattern of the substrate 3 are electrically connected by solder.
In this case, if the sub-substrate 7 having a bent structure is fixed to the substrate 3 through the screw 76 in the sub-substrate attachment hole 74, the fixed-side element 6 can be more firmly fixed to the substrate 3 (FIG. 3 ( b)).
Then, after the reflow soldering, the fixed side element positioning jig is removed except for 75.
Further, since the fixed side element 6 and the sub-board 7 are connected using high-temperature solder, the fixed side element 6 is not displaced even after passing through the second reflow solder bath.
In this way, the present invention cuts off a portion of the sub-substrate 7 having the bent structure, exposes a portion of the fixed side element 6, and uses the outer shape portion of the fixed side element 6 as a reference to fix the fixed side element 6. The fixed side element 6 can be accurately attached to the substrate 3 by performing the attaching operation of the above. The reason why the fixed side element 6 can be accurately positioned and fixed to the substrate 3 is as follows. .
That is, since the fixed side element 6 having a plurality of light receiving elements is a semiconductor, a large number of light receiving elements are formed on a silicon wafer and are individually cut by a cutting apparatus called a dicing saw in a subsequent process.
Usually, a photomask for manufacturing a light receiving element is drawn up to the outer shape to be cut, and a dimensional error between the light receiving element and this outer shape is drawn within ± l μm.
In addition, the cutting dimension accuracy of the cutting device that cuts the product in the subsequent process is about ± 1 μm, and the position dimension of the light receiving element and the outer dimension of the fixed side element 6 are processed with very accurate dimensions.
Therefore, if the positioning is performed with reference to the external dimension of the fixed side element 6 without using the processing dimension and the mounting hole of the sub-substrate having the bent structure as a reference as in the prior art, the fixed side element 6 is fixed to the substrate 3. That is, it can be accurately fixed to the substrate 3 at a predetermined position.
Although the foregoing embodiment has been described with respect to a rotary optical encoder having a rotating disk, it goes without saying that the present invention can be similarly applied to a linear optical encoder having a linear moving disk.
[0006]
【The invention's effect】
As described above, according to the present invention, the fixed-side element and the board are attached without using the external dimensions of the sub-board or the mounting holes, and by cutting out a part of the sub-board. As the assembly is performed while positioning using the external dimensions of the fixed-side element as the positioning reference, the fixed-side element can be mounted with extremely high accuracy.
[Brief description of the drawings]
FIG. 1 is a side sectional view showing a rotary optical encoder in an embodiment of the present invention.
FIGS. 2A and 2B are perspective views showing an assembly process for connecting and fixing a sub-board and a fixed element in an embodiment of the present invention, wherein FIG. 2A shows the sub-board, and FIG. 2B is connected to the inside of the sub-board. The fixed side element to be fixed is shown, and (c) shows a state where the sub-board and the fixed side element are connected and fixed.
FIG. 3 is a perspective view showing an assembly process for connecting and fixing a sub-board and a fixed-side element to a board in an embodiment of the present invention, and FIG. 3A is a positioning jig for positioning the fixed-side element on the board. (B) has shown the state which attached the stationary side element to the board | substrate with the sub board | substrate using the positioning jig.
[Explanation of symbols]
1 Encoder case,
2 base,
3 substrate,
31 Mounting reference part (reference hole),
4 LED case,
41 LED,
5 rotating discs,
51 rotation axis,
52 disk hub,
6 Fixed side element,
7 Sub-board,
74 Sub board mounting hole,
75 Fixed side element positioning jig,
76 screws,
8 Chip parts,
A Fixed side exposed element

Claims (4)

A fixed-side element including a plurality of light receiving elements;
A sub substrate having a bending structure comprises a pattern for connection to the common electrode and the electrode of the light receiving elements of the fixed-side elements,
A substrate for fixing the fixed side element;
A movable disk facing the fixed element via a gap ;
A fixed-side element exposure portion that is provided by cutting out the sub-substrate and exposes a part of the outer shape of the fixed-side element ;
For providing a fixed-side element positioning jig to the substrate at a position corresponding to a part of the outer shape of the fixed-side element exposed by the fixed-side element exposing portion, when positioning the fixed-side element. A mounting reference portion which is a reference hole ;
An optical encoder.   The fixed side element is fixed to the sub-board,
  The optical encoder according to claim 1, wherein the sub-board is screwed to the board at a location different from a reference hole formed by the attachment reference portion.   A fixed-side element including a plurality of light-receiving elements; a sub-board having a bent structure including a pattern for connecting to the common electrode of the fixed-side element and an electrode of each light-receiving element; and a board for fixing the fixed-side element And a movable disk facing the fixed side element via a gap, and a manufacturing method of an optical encoder,
  When positioning the fixed side element,
  Attach a fixed-side element positioning jig to the mounting reference part, which is a reference hole provided in the substrate,
  The fixed-side element is positioned by bringing a part of the outer shape of the fixed-side element exposed at the fixed-side element exposure portion provided by cutting out the sub-board into contact with the fixed-side element positioning jig. A method for manufacturing an optical encoder.   The method of manufacturing an optical encoder according to claim 3, wherein the fixed-side element is fixed to the sub-board and then positioned with respect to the sub-board as a unit with the sub-board.

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