JP2008002977A - Optical rotary encoder and its assembly method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely perform alignment between a rotary slit plate and a stationary slit plate and to securely prevent intrusion of dust. <P>SOLUTION: The optical rotary encoder includes: a rotary shaft 2 rotatably supported by a spindle 1; the rotary slit plate 3 attached to the rotary shaft 2; the stationary slit plate 4 disposed opposite the rotary slit plate 3; a light emitting element 6 irradiating the stationary slit plate 4 and the rotary slit plate 3 with light; and a light receiving element 7 receiving the light transmitted through the stationary slit plate 4 and the rotary slit plate 3. The spindle 1 is formed with a recessed part 10 which opens at an end face to a side of the rotary slit plate 3 and opens to a side face of the spindle 1. The light emitting element 6 is fitted and attached into the recessed part 10. The substrate 5 provided with the light receiving element 7 and the stationary slit plate 4 is arranged at a position facing the rotary slit plate 3. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical rotary encoder and an assembling method thereof, and more particularly, a structure for facilitating alignment between a rotary slit plate and a fixed slit plate, and an optically appropriately adjusted using the structure. The present invention relates to an assembly method for assembling a rotary encoder.

  The optical rotary encoder includes a rotating shaft coupled to a detected shaft that is a rotation detection target, and a rotating slit plate on which a number of slits for displaying a rotation angle (rotating position) are formed is attached to the rotating shaft. A fixed slit plate having a similar slit is placed on the rotary slit plate, and a light emitting element such as an LED and a light receiving element such as a phototransistor are disposed between the rotary slit plate and the fixed slit plate. As the rotating slit plate rotates with the rotation of the detected shaft, the light transmitted through both slits of the rotating slit plate and the fixed slit plate is detected, and the rotation angle of the detected shaft is determined. It measures (refer patent document 1). The optical rotary encoder includes an absolute type that detects an absolute rotation angle and an incremental type that detects a relative rotation angle depending on the form of the slit.

  Specifically, the conventional optical rotary encoder has a structure as shown in FIG. A rotary shaft 22 is rotatably supported by a pair of rolling bearings 23 and 23 on a spindle 21 which is a cylindrical housing. A rotating slit plate 24 is attached to one end of the rotating shaft 22. In addition, the spindle 21 is formed with a recess 25 that opens to an end face on the rotary slit plate 24 side, a light emitting element 26 is provided in the recess 25, and a fixed slit plate 27 is fixed to the opening of the recess 25. ing. Further, a substrate 28 is disposed on the side of the rotary slit plate 24 opposite to the spindle 21 and is fixed to the support portion 21 a of the spindle 21. A light receiving element 29 is provided on the substrate 28 so as to face the light emitting element 26, and the light receiving element 29 receives light transmitted through the fixed slit plate 27 and the rotating slit plate 24. Yes.

  The optical rotary encoder is assembled as follows. That is, as shown in FIG. 9, first, the light emitting element 26 is inserted into the recess 25 of the spindle 21 and attached (T1). Thereafter, the fixed slit plate 27 is attached at a position for closing the recess 25 (T2). Further, the rotary slit plate 24 is attached to one end of the rotary shaft 22 so as to face the fixed slit plate 27 (T3).

  On the other hand, a light receiving element 29 is attached to the substrate 28 by soldering (T4). The substrate 28 is attached to the spindle 21 at a position facing the rotating slit plate 24, and the light receiving element 29 is attached to the rotating slit plate 24. Opposite (T5).

  In the above assembly, if optical parts such as the rotary slit plate 24 and the fixed slit plate 27 are assembled as designed, a predetermined encoder output can be obtained. Since there are assembly errors, these errors may overlap and a predetermined performance may not be obtained. In that case, since the optical system parts that have already been assembled cannot be reconfirmed or adjusted from the light source (light emitting element 26) side, the assembled state of each part has conventionally been As it is, a predetermined encoder output waveform is generated by electrical correction (Т6).

  After that, the cover case 30 is fitted on the side of the spindle 21 where the substrate 28 is attached (Т7), the final test is performed (Т8), and a finished product is obtained.

  If the encoder output cannot be adjusted due to electrical correction, each part is disassembled and assembled again while adjusting.

  As described above, in the conventional optical rotary encoder, electrical adjustment is indispensable, and it is necessary to attach a variable resistor as an electrical component capable of electrical adjustment on the substrate. On the other hand, the present applicant has proposed a structure in which a through-hole penetrating in the rotation axis direction is provided in the spindle, and a light-emitting element and a fixed slit plate are attached to the through-hole (see Patent Document 2).

In the above structure, the slits of the rotating slit plate and the fixed slit plate can be visually observed from the light source side through the through hole. Therefore, accurate alignment between the fixed slit plate and the rotary slit plate can be performed, and electrical adjustment becomes unnecessary. In the above-described position adjustment of the optical system parts, the output signal is improved as compared with the case of electrical adjustment, and an encoder output very close to a required waveform can be obtained. The light emitting element may be inserted and fixed in the through hole from the counter-rotating slit plate side after the above alignment.
Japanese Patent Laid-Open No. 11-83542, FIG. JP 2005-274479 A

  However, in the configuration in which the through-hole is formed in the spindle as described above, an electrical adjustment step is not necessary, and the variable resistor that was necessary for the electrical adjustment can be replaced with a fixed resistor. However, the through hole opens to the outer end side of the spindle, and if the opening of the through hole is left open, dust may enter the inside, which is not preferable in terms of dust prevention.

  In view of the above problems, the present invention provides an optical rotary encoder structure capable of accurately aligning the rotary slit plate and the fixed slit plate and reliably preventing dust from entering, and an assembling method thereof. The issue is to provide.

  An optical rotary encoder according to the present invention is rotatably supported on a spindle and connected to a detected shaft, a rotary slit plate attached to the rotary shaft, and a position facing the rotary slit plate. An optical rotary encoder comprising: a fixed slit plate disposed; a light emitting element that irradiates the fixed slit plate and the rotary slit plate; and a light receiving element that receives light transmitted through the fixed slit plate and the rotary slit plate. The spindle is formed with a recess that opens to the end surface on the side of the rotary slit plate and opens to the side surface of the spindle, and the light emitting element is mounted in the recess and is positioned at a position facing the rotary slit plate. A substrate provided with a light receiving element and the fixed slit plate is disposed.

  In the optical rotary encoder configured as described above, during the assembly process, the rotary slit plate is attached to the rotary shaft, while the substrate provided with the light receiving element and the fixed slit plate is disposed at a position facing the rotary slit plate. An optical means such as a prism or a reflecting mirror is inserted into the recess of the side from the outside, and through this optical means, the rotating slit plate and the fixed slit plate provided on the substrate are visually or visually observed. Through this observation, the fixed slit plate can be accurately aligned with the rotary slit plate.

  According to such position adjustment of the optical system parts, the waveform of the output signal is effectively improved as compared with the case of electrical adjustment, and a required encoder output can be obtained. Therefore, adjustment to electrically correct the output waveform is not required, and the number of assembly steps can be reduced by omitting this adjustment process, and the cost can be reduced by replacing the variable resistor, which is an adjustment component, with a fixed resistor. Can be reduced.

  The light-emitting element may be attached to the spindle by inserting the light-emitting element into the concave portion of the spindle from the outside laterally after the above alignment. In this case, conventionally, since the fixed slit plate attached to the end face of the spindle is provided on the substrate and is located away from the spindle, insertion of the light emitting element into the concave portion of the spindle may be hindered. The light emitting element can be attached to the spindle without any trouble.

  The concave portion of the spindle opens to the end surface on the rotating slit plate side and the side surface of the spindle, and does not open to the outer end surface. Therefore, there is no opening exposed to the outside, and dust can be reliably prevented from entering from the outside.

  In the optical rotary encoder having the above-described configuration, it is desirable that the light receiving element has a fixed slit plate integrally provided on the light receiving surface side like a photodiode array with a slit mask. A slit (fixed slit plate) is formed in the light receiving element at the production stage, so that the positioning of the fixed slit plate with respect to the light receiving element is extremely accurate, and is necessary when the light receiving element and the fixed slit plate are manufactured separately. There is no need for any positioning process.

  In the optical rotary encoder having the above-described configuration, it is desirable that the light emitting element is attached to the concave portion while being held by a holder that is fitted to the concave portion of the spindle from the outside of the side of the spindle. When the light emitting element is mounted in the concave portion of the spindle via the holder, the light emitting element can be securely fixed in the concave portion even though the concave portion is open on the side surface of the spindle. Since the holder is fitted therein, the opening width is relatively wide, so that a relatively large optical means can be inserted into the recess, which is convenient for observation such as visual observation.

  An optical rotary encoder assembling method according to the present invention is a method of assembling an optical rotary encoder having the above-described configuration, in which a rotating slit plate is attached to a rotating shaft in a state where a light emitting element is not mounted in a concave portion of a spindle. A step of attaching, a step of attaching a light receiving element having a fixed slit plate on the light receiving surface side to the substrate, a step of supporting the substrate having the light receiving element on the spindle so as to face the rotating slit plate, and a recess in the spindle Including a step of aligning the fixed slit plate with the rotating slit plate by observation through an optical means inserted from the outside of the side, and a step of attaching the light emitting element in the concave portion of the spindle after the alignment. It is a characteristic.

  According to this assembling method, as described above with respect to the optical rotary encoder, the positioning of the fixed slit plate with respect to the rotating slit plate is accurately performed by visual observation or image observation through the optical means inserted into the concave portion of the spindle. The product can be assembled without the electrical adjustment process.

  According to the present invention, the positioning of the fixed slit plate with respect to the rotary slit plate can be accurately performed, electrical adjustment is not required, and the opening on the outer end side of the spindle is eliminated. Can be prevented.

  1 to 7 show the best embodiment of the present invention. FIG. 1 is a sectional view of an optical rotary encoder according to the best embodiment. FIG. 2 is an exploded perspective view of the optical rotary encoder. 3 is a perspective view of the optical rotary encoder as seen from the lower surface side of the substrate, FIG. 4 is an assembly process diagram of the optical rotary encoder, and FIGS. 5 to 7 are all in the process of assembling. It is the side view which a partially broken optical rotary encoder.

  As shown in FIGS. 1 and 2, the optical rotary encoder according to this embodiment includes a spindle 1, which is a substantially cylindrical housing, a rotating shaft 2, a rotating slit plate 3, a fixed slit plate 4, and a substrate. 5, a light emitting element 6 such as an LED, a light receiving element 7 such as a photodiode, and a cover case 8.

  The rotary shaft 2 is connected to a detected shaft (not shown) and is rotatably supported by a center portion of the spindle 1 by a pair of rolling bearings 9 and 9. The rotary slit plate 3 is formed with a large number of slits 3a for displaying a rotation angle (rotation position) in the circumferential direction, and a flange portion 2a provided at one end (the upper end in FIGS. 1 and 2) of the rotary shaft 2. Is attached. The fixed slit plate 4 has a slit 4 a (shown in FIG. 3) corresponding to the slit 3 a of the rotary slit plate 3.

  The substrate 5 is disposed on the side opposite to the spindle 1 of the rotary slit plate 3 and is supported and fixed to the columnar support portion 1 a of the spindle 1. A light receiving element 7 and a fixed slit plate 4 are provided on the surface of the substrate 5 on the rotating slit plate 3 side. The light receiving element 7 is located at a position facing the light emitting element 6 mounted on the spindle 1 side with the rotary slit plate 3 and the fixed slit plate 4 interposed therebetween, and transmitted through the rotary slit plate 3 and the fixed slit plate 4. The irradiation light of the light emitting element 6 is received.

  The cover case 8 is a bottomed cylindrical body that is externally fitted to the outer periphery of the spindle 1, covers the outside of components such as the rotating slit plate 3 and the substrate 5 on one end side of the spindle 1, and covers the side surface of the spindle 1. It is like that. The open end of the cover case 8 is brought into pressure contact with an O-ring 14 provided in an annular recess 1b on the outer periphery of the outer end portion (the lower end portion in FIGS. 1 and 2) of the spindle 1 to be in a sealed state.

  In the above configuration, when the rotating shaft 2 and the rotating slit plate 3 rotate as the detected shaft rotates, the light emitted from the light emitting element 6 causes both the slits 3 a and 4 a of the rotating slit plate 3 and the fixed slit plate 4 to rotate. The light is transmitted and incident on the light receiving element 7 intermittently. Based on this intermittent incident light, the rotation angle of the detected axis is measured.

  In the present embodiment, in addition to the above-described configuration, a structure is provided for facilitating the positional adjustment of the rotary slit plate 3 and the fixed slit plate 4 and for ensuring dust prevention. That is, the spindle 1 is formed with a recess 10 that opens to the end surface on the side of the rotary slit plate 3 (upper side in FIGS. 1 and 2) and opens to the side surface of the spindle 1 (outer surface along the axial direction). The concave portion 10 has a shape that is cut from the end surface of the spindle 1 on the rotary slit plate 3 side to an intermediate position in the axial direction, and does not open at the outer end portion (the lower end portion in FIGS. 1 and 2) of the spindle 1.

  As will be described in detail later, the concave portion 10 functions as a space for inserting optical means such as a prism and a reflecting mirror from the outside of the side, and also serves as a mounting space for the light emitting element 6. The light emitting element 6 is attached via the holder 11 in a form in which the light emitting part faces the rotary slit plate 3. The holder 11 has an outer shape that can be inserted into the recess 10 from the outside laterally (in the lateral direction from the left side in FIGS. 1 and 2). As shown in FIG. 2, the outer peripheral surface of the split cylindrical body. The mounting pieces 11a and 11a are integrally provided at the two locations, and the mounting pieces 11a are fitted into the concave portion 10 by abutting against the inner surface along the axial direction of the concave portion 10 and fastening with screws 12. It is fixed in the recess 10 in a state. The light emitting element 6 is fitted into the split cylindrical main body of the holder 11 from one side and fixed at a predetermined midway position.

  In the present embodiment, as clearly shown in FIG. 3, the light receiving element 7 is attached to a predetermined position of the substrate 5, and the fixed slit plate 4 is integrally provided on the light receiving surface side of the light receiving element 7. In this case, the light receiving element 7 and the fixed slit plate 4 manufactured separately may be positioned with respect to each other and attached to the substrate 5, but in the illustrated example, the light receiving element 7 is, for example, a photodiode array with a slit mask. As described above, the fixed slit plate 4 is integrally provided on the light receiving surface side. Therefore, the light receiving element 7 and the fixed slit plate 4 are provided on the substrate 5 by attaching the light receiving element 7 to the substrate 5.

  Next, a method for assembling the optical rotary encoder having the above-described configuration will be described with reference to the process diagram of FIG. 4 and side views in the middle of the assembly of FIGS.

  First, as shown in S1 of FIG. 4 and FIG. 5, the rotating slit plate 3 is attached to the flange portion 2 a at one end of the rotating shaft 2. In this case, the rotary slit plate 3 is not misaligned on the rotary shaft 2 by matching the mark on the end face of the flange portion 2a with the mark on the rotary slit plate 3 (both not shown). Installed in a state.

  When the rotary slit plate 3 is attached, neither the holder 11 nor the light emitting element 6 is provided in the recess 10 of the spindle 1 and the recess 10 is open.

  On the other hand, the light receiving element 7 with the fixed slit plate 4 is soldered to the substrate 5 (S2), and the substrate 5 is supported on the support 1a of the spindle 1 with respect to the rotating slit plate 3. 5 is adjusted (S3).

  In this case, as shown in FIG. 6, the optical means 13 having a prism 13p, a reflecting mirror, or the like is inserted into the open recess 10 at the tip. Since the optical means 13 reflects the shape of a part such as the rotary slit plate 3 that is outside the concave portion 10 in the axial direction, the optical slit 13 and the fixed slit provided on the substrate 5 are provided via the optical means 13. The plate 4 can be observed visually or with an image, and through this observation, the fixed slit plate 4 can be accurately aligned with the rotating slit plate 3.

  When the substrate 5 including the fixed slit plate 4 and the rotary slit plate 3 are attached to predetermined positions as described above, the light emitting element 6 is inserted into the holder 11 as shown in FIG. 11 is inserted into the recess 10 from the outside laterally, and is fixed in the recess 10 by fixing the screw 12 of the mounting piece 11a, whereby the light emitting element 6 is mounted in the recess 10 of the spindle 1 (S4).

  After that, the cover case 8 is fitted on the outer periphery of the spindle 1 from the substrate 5 side and assembled (S5). As a result, the outside of the components such as the substrate 5 and the rotary slit plate 3 is covered, and the opening on the side of the spindle 1 on the side of the spindle 10 is shielded from the outside, resulting in the shape shown in FIG. 1 is subjected to a final test (S6) to obtain a finished product.

1 is a cross-sectional view of an optical rotary encoder according to the best embodiment of the present invention. FIG. 3 is an exploded perspective view of the optical rotary encoder. The perspective view seen from the lower surface side of the board | substrate which is a part of said optical rotary encoder. FIG. 4 is an assembly process diagram of the optical rotary encoder. The side view in which the optical rotary encoder in the middle of assembly was partially broken. FIG. 6 is a partially cutaway side view of the optical rotary encoder in the middle of assembly, showing the next state of FIG. FIG. 7 is a partially cutaway side view of the optical rotary encoder in the middle of assembly, showing the next state of FIG. 6. Sectional drawing of the conventional optical rotary encoder. The assembly process figure of the said conventional optical rotary encoder.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Spindle 2 Rotating shaft 3 Rotating slit plate 4 Fixed slit plate 5 Substrate 6 Light emitting element 7 Light receiving element 10 Recessed part 11 Holder 13 Optical means

Claims (4)

A rotating shaft that is rotatably supported by the spindle and connected to the detected shaft, a rotating slit plate that is attached to the rotating shaft, a fixed slit plate that is disposed at a position facing the rotating slit plate, and the fixed An optical rotary encoder having a slit plate and a light emitting element that irradiates the rotary slit plate, and a light receiving element that receives light transmitted through the fixed slit plate and the rotary slit plate,
The spindle is formed with a recess that opens at the end surface on the rotary slit plate side and at the side of the spindle, and the light emitting element is mounted in the recess, and the light receiving element and An optical rotary encoder, wherein a substrate provided with the fixed slit plate is disposed.   The optical rotary encoder according to claim 1, wherein the light receiving element is integrally provided with a fixed slit plate on a light receiving surface side thereof.   3. The optical rotary encoder according to claim 1, wherein the light emitting element is mounted in the recess while being held by a holder that fits in the recess of the spindle from the outside of the side of the spindle. A method for assembling the optical rotary encoder according to any one of claims 1 to 3,
Attaching a rotating slit plate to the rotating shaft in a state where no light emitting element is attached in the concave portion of the spindle;
Attaching a light receiving element having a fixed slit plate on the light receiving surface side to the substrate;
Supporting the substrate provided with the light receiving element on the spindle so as to face the rotating slit plate;
A step of aligning the fixed slit plate with respect to the rotary slit plate by observing through the optical means inserted from the outside laterally into the concave portion of the spindle;
After the alignment, attaching a light emitting element in the recess of the spindle;
A method of assembling an optical rotary encoder, comprising:

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