JP2010085253A - Rotary encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary encoder capable of enhancing the positional accuracy between mutual photointerrupters on a circuit board. <P>SOLUTION: In this rotary encoder 1, a cover plate 30 is utilized, when photointerrupters 20, 21 are reflow soldered on the circuit board 6, and the first opening parts S1, S2 to the same number as the number of the photointerrupters 20, 21 are provided on the cover plate 30. Furthermore, a mutual position relation between the photointerrupters 20, 21 is determined beforehand by the first opening parts S1, S2 on the cover plate 30, and the photointerrupters 20, 21 are press-fitted into the first opening parts S1, S2 respectively. When the cover plate 30 is positioned on, the circuit board 6 by the first positioning means 31, the first opening parts S1, S2 can appear on prescribed positions on the circuit board 6. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rotary encoder having a photo interrupter that detects rotation of a rotating shaft.

  Conventionally, as a technique in such a field, there is JP-A-2005-326355. An encoder unit is attached to the output shaft of the motor described in this publication. In this encoder unit, a disk having a slit row is fixed to the output shaft, and a photo arranged on the circuit board so as to sandwich the slit row. The interrupter is fixed with solder. Further, in order to detect the rotation direction of the output shaft, it is necessary to fix two photo interrupters on the circuit board in such a positional relationship that the output waveform is shifted by 90 degrees.

JP 2005-326355 A

  When the above-mentioned two photo interrupters are soldered on the circuit board by reflow, there is an error in the circuit pattern even if each photo interrupter is arranged on the circuit pattern on the circuit board by a high-precision chip mounter. It is difficult to solder the photo interrupter to the correct position. In the case of one photo interrupter, even if there is a slight error in position accuracy, the detection accuracy of the rotary encoder may be little affected. However, in the case of two photo interrupters, the relative relationship between the photo interrupters is sufficient. If the position accuracy is not high, an output waveform shifted by 90 degrees cannot be generated accurately, and there is a problem that the detection accuracy of the rotation direction by the photo interrupter is lowered.

  An object of the present invention is to provide a rotary encoder that improves the positional accuracy between photointerrupters on a circuit board.

The present invention relates to a rotary encoder having a rotating shaft supported by a housing and a photo interrupter for detecting the rotation of the rotating shaft.
A circuit board to which a plurality of photo interrupters are fixed;
A cover plate disposed on the circuit board and having a first opening into which each photo interrupter is press-fitted;
And a first positioning means for positioning the circuit board and the cover plate.

  In this rotary encoder, the cover plate is used when reflow soldering the photo interrupter on the circuit board, and the cover plate is provided with the same number of first openings as the number of photo interrupters. Furthermore, the mutual positional relationship between the photo interrupters is determined in advance by the first opening of the cover plate, and each photo interrupter is press-fitted into each of the first openings. When such a cover plate is positioned on the circuit board by the first positioning means, the first opening can appear at a predetermined position on the circuit board, and a photo is formed in the first opening. By press-fitting the interrupter, even if there is some error in the circuit pattern on the circuit board, the positional accuracy between the photo interrupters on the circuit board can always be kept constant and high. As described above, the cover plate firmly holds the photo interrupter by press-fitting, so that the photo interrupter is hardly peeled off and contributes to a longer product life. Furthermore, the adjustment process due to the positional deviation between the photointerrupters during manufacturing can be eliminated, and the manufacturing process can be simplified simultaneously with the yield of the product, thereby reducing the manufacturing cost.

Further, it is preferable to further include second positioning means for positioning the cover plate and the housing.
By adopting such a configuration, the photo interrupter can be accurately arranged with respect to the rotating shaft supported by the housing. This also increases the accuracy of the rotary encoder.

Further, it is preferable that the wall surface forming the first opening of the cover plate is provided with convex portions that are pressed against the four side surfaces that form the periphery of the rectangle of the photo interrupter.
As described above, the photo interrupter is supported at four points, so that the photo interrupter can be positioned firmly and reliably in the first opening. Furthermore, since the solder pool space can be created between the convex portions adjacent in the circumferential direction in the first opening, it is possible to eliminate solder defects due to excessive solder.

In addition, the apparatus further includes push switch means having a disc spring arranged so as to cover the contact formed on the circuit board, and the cover plate is provided with a second opening into which the disc spring is press-fitted. Is preferred.
Conventionally, a unitized push switch is soldered on a circuit board by reflow. In contrast, in the present invention, the cover plate is provided with a second opening, and a disc spring is press-fitted into the second opening in order to effectively use the cover plate. As a result, the number of parts constituting the switch can be minimized, and the rotary encoder can be simplified and miniaturized, and the number of parts can be reduced.

  According to the present invention, it is possible to improve the positional accuracy between photo interrupters on a circuit board.

  Hereinafter, preferred embodiments of a rotary encoder according to the present invention will be described in detail with reference to the drawings.

  As shown in FIGS. 1 to 3, the rotary encoder 1 includes a housing 10 including a body 11 and a lid portion 12, and the rotating shaft 2 is rotatably supported by the body 11 of the housing 10. The retaining ring 3 fitted to the outer peripheral surface of the rotating shaft 2 abuts on the inner wall surface of the housing 10, and the distal end portion 2 a of the rotating shaft 2 is biased by a disc spring 4 disposed on the lid 12 side. Has been. With such a configuration, backlash of the rotating shaft 2 is prevented.

  One end of the rotating shaft 2 protrudes outside the housing 10 and is used as a rotation input unit for rotating the rotating shaft 2. The other end of the rotating shaft 2 is press-fitted into the center of the rotor 5 inside the housing 10. The rotor 5 includes a cylindrical rotor body 5a, an annular flange portion 5b protruding in the radial direction at the end of the rotor body 5a, and a comb tooth portion 5c provided annularly along the periphery of the flange portion 5b. have. The comb teeth portion 5c is composed of a plurality of comb teeth protruding toward the lid portion 12 in the direction of the axis L of the rotary shaft 2, and slits having a predetermined width are formed between the comb teeth.

  The circuit board 6 is in contact with the inner surface of the lid 12. Transmission-type photo interrupters 20 and 21 for detecting the rotation of the rotary shaft 2 are soldered to the circuit board 6 by reflow. Each of the photo interrupters 20 and 21 has a light emitting element and a light receiving element that emit light, and the comb tooth portion 5c passes through the detection grooves 20a and 21a between the light emitting element and the light receiving element.

  In this rotary encoder 1, when the rotary shaft 2 is rotated, the comb teeth 5c of the rotor 5 rotate, and the comb teeth and slits alternately pass between the light emitting element and the light receiving element. Is received by the light receiving element as strong and weak pulse light, and the amount of rotation of the rotary shaft 2 is detected based on this light reception.

  Furthermore, a tooth portion 5d extending along the axis L direction is formed on the outer peripheral surface of the rotor body 5a over the entire circumference. A tooth groove recessed in an arc shape is formed between the tooth portions 5d, and a barrel-shaped roller 7 is engaged with the tooth groove. The roller 7 is pressed against the tooth gap 5 e by the roller support mechanism 22.

  The roller support mechanism 22 urges the rotation arm 23 and a rotation arm 23 that holds a roller 7 that rotates about a shaft portion 7 a that extends in the same direction as the direction in which the rotation axis L extends. And a coil spring 24 for pressing the roller 7 against the tooth gap between the tooth portions 5d. Accordingly, the roller 7 is continuously engaged with the tooth gap, so that a click feeling can be produced when the rotary shaft 2 rotates.

  Furthermore, in order to detect the rotation direction of the rotating shaft 2, the two photo interrupters 20 and 21 are soldered on the circuit board 6 by reflow in such a positional relationship that the output waveform is shifted by 90 degrees. If the relative positional accuracy between the photo interrupters 20 and 21 is not high, an output waveform shifted by 90 degrees cannot be accurately generated, and the detection accuracy of the rotation direction by the photo interrupters 20 and 21 is reduced. End up.

  Therefore, as shown in FIGS. 4 to 6, in the rotary encoder 1, a resin cover plate 30 disposed on the circuit board 6 is employed. The cover plate 30 is formed with first rectangular openings S1 and S2 in which the layout of the photo interrupters 20 and 21 having a substantially quadrangular prism shape is planned, and the photo interrupters 20 and 20 are formed in the openings S1 and S2. Each 21 is press-fitted.

  The rectangular cover plate 30 and the rectangular circuit board 6 are positioned by the first positioning means 31. The first positioning means 31 includes a protrusion 32 protruding from the back surface of the cover plate 30 and a notch 33 provided at the edge of the circuit board 6 and into which the protrusion 32 is fitted.

  The convex portions 32 of the cover plate 30 are triangular first and second convex portions 32 a and 32 b provided on two opposing sides of the cover plate 30 and triangular shapes provided on the corners of the cover plate 30. It consists of the 3rd convex part 32c. On the other hand, the notch 33 of the circuit board 6 is provided on the two opposite sides of the circuit board 6 and the first substantially triangular shape into which the first and second protrusions 32a and 32b are fitted. The second cutouts 33a and 33b are provided at the corners of the circuit board 6 and the third cutouts 33c for fitting the third protrusions 32c.

  Therefore, the cover plate 30 is firmly positioned on the circuit board 6 by fitting the convex portion 32 of the cover board 30 to the notch 33 of the circuit board 6. The openings S1 and S2 can appear at predetermined positions on the circuit board 6.

  Arc-shaped convex portions 34 and 35 pressed against the four side surfaces surrounding the photointerrupters 20 and 21 are provided on the wall surfaces forming the first rectangular openings S1 and S2, respectively. By holding the photointerrupter 20 by the four convex portions 34 and holding the photointerrupter 21 by the four convex portions 35, the photointerrupters 20 and 21 are supported at four points, so that the first The photo interrupter can be positioned in the openings S1 and S2.

  Further, in the first opening S1, between the protrusions 34a and 34b adjacent in the circumferential direction, between the protrusions 34b and 34c, between the protrusions 34c and 34d, and between the protrusions 34d and 34a. Since the solder pool space P can be created between them, surplus solder H can be poured during reflow and solder defects can be eliminated. The same applies to the first opening S2.

  Furthermore, since the tops of the convex portions 34 and 35 are arcuate, the contact area with the photointerrupters 20 and 21 can be reduced, and the photointerrupters 20 and 21 can be easily placed in the first openings S1 and S2. Can be press-fitted.

  The cover plate 30 described above is preferably made of a material that can withstand the reflow temperature and at the same time has good dimensional stability. For example, PPS (polyphenylene sulfide resin) is optimal.

  Further, as shown in FIGS. 2, 4, and 7, the cover plate 30 has a second opening 36 into which the disc spring 4 forming a part of the push switch means 40 is press-fitted, and various electronic components 37. And a third opening 38 is provided.

  The push switch means 40 covers a circular contact R1 formed on the circuit board 6, a C-shaped contact R2 formed on the circuit board 6 so as to surround the circular contact R1, and a central contact R1. The disc spring 4 whose peripheral edge is always in contact with the C-shaped contact R2 is fixed to the center of the disc spring 4, and the tip portion 2a of the rotary shaft 2 is pressed against it. It consists of a cylindrical seating part 41. The disc spring 4 is press-fitted into the second opening 36 of the cover plate 30.

  Conventionally, the unitized push switch is soldered on the circuit board 6 by reflow. On the other hand, in the present invention, the cover plate 30 is provided with the second opening 36 for effective use, and the disc spring 4 is press-fitted into the second opening 36. As a result, the number of parts constituting the switch can be minimized, and the structure of the rotary encoder 1 can be simplified and downsized, and the number of parts can be reduced.

  Further, as shown in FIGS. 3 and 4, the rotary encoder 1 includes second positioning means 50 for positioning the cover plate 30 and the body 11 of the housing 10. The second positioning means 50 includes a notch 51 having a rectangular shape on two opposite sides of the cover plate 30, and a protrusion 52 that protrudes from the lower end of the body 11 and fits into each notch 51. . By adopting such a configuration, the photo interrupters 20 and 21 can be accurately arranged with respect to the rotating shaft 2 supported by the body 11, and this also increases the accuracy of the rotary encoder 1. Can do.

  In the rotary encoder 1, the cover plate 30 is used when the photointerrupters 20 and 21 are reflow soldered on the circuit board 6. The cover plate 30 has the same number of first interrupters as the number of photointerrupters 20 and 21. Openings S1 and S2 are provided. Further, the mutual positional relationship between the photo interrupters 20 and 21 is determined in advance by the first openings S1 and S2 of the cover plate 30, and the photo interrupters 20 and 21 are located in the first openings S1 and S2. Each is press-fitted.

  As shown in FIG. 8, when such a cover plate 30 is positioned on the circuit board 6 by the first positioning means 31, the first openings S <b> 1 and S <b> 2 appear at predetermined positions on the circuit board 6. Even if there is a slight error in the circuit pattern on the circuit board 6, the photo interrupters 20 and 21 are press-fitted into the first openings S 1 and S 2 from above by the chip mounter. 6, the positional accuracy between the photo interrupters 20 and 21 can always be kept constant and high.

  Thus, the cover plate 30 is effective when an alignment effect due to reflow occurs on the circuit board 6, and the photo interrupters 20 and 21 are firmly held by press fitting with the cover plate 30. , 21 is less likely to be peeled off and contributes to a longer product life. Further, the adjustment process due to the positional deviation between the photointerrupters 20 and 21 at the time of manufacturing can be eliminated, and the manufacturing process can be simplified at the same time as the product yield, thereby reducing the manufacturing cost. .

  Further, various electronic components 37 are arranged in the third opening 38 of the cover plate 30 by the chip mounter, and then heat treatment is performed in the reflow soldering apparatus. After the soldering of the electronic component 37 and the photo interrupters 20 and 21 is completed, the disc spring 4 is press-fitted into the second opening 36 as shown in FIG. Thereafter, as shown in FIG. 3, the convex portion 52 of the body 11 is fitted into the notch 51 of the cover plate 30 to which the rotary shaft 2 is assembled, and the lid 12 is brought into contact with the circuit board 6. In this state, the lid 12 is fixed to the body 11 with the screw 53.

  It goes without saying that the present invention is not limited to the embodiment described above. For example, the present invention is not limited to soldering by a reflow furnace, but can also be applied to flow type soldering.

It is a perspective view which shows one Embodiment of the rotary encoder which concerns on this invention. It is sectional drawing of the rotary encoder which concerns on this invention. It is a disassembled perspective view of the rotary encoder which concerns on this invention. It is a top view which shows a cover board. It is a perspective view which shows a cover board and a circuit board. It is the perspective view which looked at the cover board from the back side. It is a perspective view which shows the state after completion of reflow soldering. It is a perspective view which shows the state before completion of reflow soldering.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Rotary encoder, 2 ... Rotating shaft, 4 ... Disc spring, 6 ... Circuit board, 10 ... Housing, 20, 21 ... Photo interrupter, 30 ... Cover board, 31 ... 1st positioning means, 34, 35 ... Convex part , 36 ... second opening, 40 ... push switch means, 50 ... second positioning means, S1, S2 ... first opening.

Claims (4)

In a rotary encoder having a rotating shaft supported by a housing and a photo interrupter for detecting rotation of the rotating shaft,
A circuit board to which a plurality of the photo interrupters are fixed;
A cover plate disposed on the circuit board and having a first opening into which each of the photo interrupters is press-fitted;
A rotary encoder comprising: first positioning means for positioning the circuit board and the cover plate.   The rotary encoder according to claim 1, further comprising second positioning means for positioning the cover plate and the housing.   The wall surface forming the first opening of the cover plate is provided with convex portions that are pressed against the four side surfaces that form the periphery of the rectangle of the photo interrupter. The described rotary encoder. Further comprising push switch means having a disc spring arranged to cover the contacts formed on the circuit board;
The rotary encoder according to any one of claims 1 to 3, wherein the cover plate is provided with a second opening into which the disc spring is press-fitted.

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