JP4497935B2 - Rotary encoder - Google Patents

Description

  The present invention relates to a structure for mounting a rotary slit plate attached to a rotary shaft of an optical rotary encoder, and more particularly to a positioning structure for a rotary slit plate.

  In the optical rotary encoder, a rotary slit plate having a large number of slits for displaying a rotation angle (rotation position) is attached to a flange portion formed on a rotation shaft connected to a detected shaft that is a rotation detection target. Yes. On this rotating slit plate, a light emitting part (LED, etc.) and a light receiving part (phototransistor, etc.) are arranged with a fixed slit formed with slits having the same pitch as the above-mentioned slits. By rotating the rotary slit plate through the connected rotary shaft 1, the transmitted light is detected and the rotation angle is measured. Compared with the absolute type that detects the absolute rotation angle according to the form of the slit. There is an incremental type that detects a simple rotation angle.

  In such a rotary encoder, as shown in, for example, Japanese Patent Application Laid-Open No. 11-83542 (Patent Document 1), the rotary slit plate has a mounting hole with a diameter larger than that of the rotary shaft. This mounting hole is inserted through the rotating shaft and brought into contact with the flange portion, and positioned concentrically while holding the adhesive ring from above the rotating slit plate, and then the outer periphery of the adhesive ring and the rotating slit plate And between the inner periphery of the adhesive ring and the rotary shaft by an adhesive.

  In order to construct an optical rotary encoder having a desired high resolution, it is necessary to position and attach a rotary slit plate with high accuracy to the rotary shaft. In addition, it is necessary to match the mechanical origin of the rotary slit plate and the origin of the electrical signal with high accuracy. However, according to Patent Document 1 described above, the rotating slit plate can be attached with a necessary strength, but positioning means for attaching with high accuracy to the rotating shaft is not considered.

  A normal positioning means for the rotating shaft and the rotating slit plate will be described with reference to FIG. A mounting hole 100b having a diameter larger than that of the rotary shaft 102 is formed in the rotary slit plate 100 in which a large number of slits 100a for displaying the rotation angle (rotation position) are formed. Further, an origin mark 101 indicating the origin position is displayed between the slit 100a and the mounting hole 100b. On the other hand, the rotating shaft 102 is formed with, for example, a D-cut connecting portion 102a so as to be connected to a detected shaft that is a rotation detection target at one end side, and the rotating slit plate 100 is attached to the other end side. A flange portion (not shown) is provided. Furthermore, a center mark 103 is displayed on the axial center on the other end face of the rotating shaft 102.

  When positioning and attaching the rotary slit plate 100 to the rotary shaft 102, first, the connecting portion 102 a of the rotary shaft 102 is installed on the jig 104. The jig 104 is provided with a fitting hole in which a flat surface for joining the connecting portion 102a to the D-cut portion of the connecting portion 102a is formed while lightly press-fitting the connecting portion 102a. The connecting portion 102a is installed in the fitting hole. By doing so, the position of the rotating shaft 102 in the rotational direction is determined using the D-cut portion as a proof. In addition, an index mark 104 a is displayed on the jig 104.

  Next, after inserting the rotary slit plate 100 from the other end of the rotary shaft 102, the origin mark 101 of the rotary slit plate 100, the center mark 103 of the rotary shaft 102, and the index mark 104a of the jig 104 are in a straight line. The rotary slit plate 100 is rotated so as to match. As a result, as shown in FIG. 9B, the origin position of the rotary slit plate 100 can be determined with respect to the rotary shaft 102.

  However, in this state, as shown in FIG. 9A, the centers of the rotary slit plate 100 and the rotary shaft 102 do not coincide with each other, causing a detection error. For this purpose, centering adjustment of the rotary slit plate 100 is performed. The rotating slit plate 100 is formed with a centering line 100c for adjusting the centering on the outer peripheral side. On the other hand, the jig 104 is provided with a confirmation window 105 for confirming the centering line 100c. Then, the centering adjustment is performed by checking the position of the centering line 100c through the confirmation window 105 while rotating the rotary slit plate 100, and adjusting the position of the rotary slit plate 100 so as to be the same position on the entire circumference. .

However, in such centering adjustment, since the rotation of the rotary slit plate 100, the movement in the radial direction, and the positioning of the origin are performed, a great amount of time is required, and the adjustment is performed with high accuracy. In order to do so, considerable skill was required. As a result, there is a problem that the cost increases as the number of assembly steps increases.
JP-A-11-83542

  The problem to be solved by the present invention is to provide a rotary encoder that can improve the origin position of the rotating shaft and the rotating slit plate and the accuracy of centering and can be set in a short time. .

In order to solve the above-mentioned problem, the invention described in claim 1 is a rotary encoder in which a rotary slit plate is positioned and fixed to a rotary shaft connected to a detected shaft, and the rotary slit plate is arranged at the center of the rotary shaft. A loosely-fitting center hole is formed, and at least two slit plate origin marks indicating the origin position of the rotary slit plate are provided at the periphery of the center hole. The rotation axis origin mark and the axis center mark indicating the axis center are provided, and at least two of the virtual extension lines toward the center of the slit plate origin mark coincide with the rotation axis origin mark and the axis mark The gist of the invention is that the rotary slit plate is attached to the rotary shaft at a position where the rotary shaft is placed.

  According to a second aspect of the present invention, in the first aspect of the invention, the rotating slit plate is formed with two fine lines extending radially from the center at the periphery of the center hole, and the two fine lines are centered. The gist is that the virtual extension line toward is formed at an opening angle at which it intersects.

According to the present invention, the slit plate origin mark is provided at at least two locations on the periphery of the center hole formed at the center of the rotary slit plate, and the rotary shaft origin mark is provided on the rotary shaft. By matching the virtual extension line of the slit plate origin mark with the rotation axis origin mark, the origin position and centering of the rotation axis and the rotation slit plate can be matched with high accuracy. As a result, it is possible to accurately match the mechanical origin of the rotating shaft and the rotating slit plate with the origin of the electric signal obtained from the rotary encoder. Furthermore, since the origin position and the centering can be positioned by matching the slit plate origin mark with the rotation axis origin mark, skill is not required and the adjustment work can be greatly shortened, thus reducing costs. It becomes possible.
In addition, a rotation axis origin mark indicating the origin position and an axis center mark indicating the axis center are provided on the rotation axis, and virtual extension lines of the origin marks for the slit plate at the two locations are set as the rotation axis origin mark and the axis center of the rotation axis. By matching with the mark, both the origin position and the centering can be simultaneously adjusted with high accuracy with respect to the rotation axis of the rotary slit plate.

  According to the second aspect of the present invention, two fine lines extending in the radial direction from the center are formed on the rotating slit plate as the origin mark for the slit plate, and the open angle of these fine lines intersects with the virtual extension line. Since the two thin lines and the origin mark for the rotating shaft coincide with each other on the virtual extension line, the rotating slit plate can be positioned with high accuracy. In addition, since the opening angle of the thin lines intersects with the virtual extension line, both the origin position and the centering can be adjusted simultaneously with high accuracy.

  In the rotary encoder, a rotary slit plate is positioned and fixed on a rotary shaft connected to a detected shaft. The rotary slit plate is formed with a central hole loosely fitted to the rotary shaft at the center, and at least two slit plate origin marks indicating the origin position of the rotary slit plate are provided on the periphery of the central hole. On the other hand, the rotation axis is provided with a rotation axis origin mark indicating the origin position of the rotation axis. Then, by making the virtual extension line of the origin mark for the slit plate at least two places coincide with the origin mark for the rotation axis, the rotation slit plate is attached in a state where the origin position and the centering coincide with the rotation axis.

  FIG. 1 shows a state in which a rotary slit plate is attached in a state where an origin position and a centering coincide with a rotation axis in an optical rotary encoder according to the present invention. The principle configuration of this optical rotary encoder will be described first with reference to FIGS. In the optical rotary encoder, two members having slits are interposed in an optical path between a light source 1 such as a light emitting diode (LED) and a light receiving element 2. Among them, the member on the light receiving element 2 side is a rotating slit plate 3 that rotates together with the rotation angle object to be measured, and slits 3a are formed in a circular shape radially and at a predetermined pitch in the circumferential direction. The other member is a fixed slit plate 4, and slits 4 a are formed at equal intervals with the slit 3 a of the rotary slit plate 3. When the slits 3 a and 4 a are aligned, the light from the light source 1 passes through the slits 3 a and 4 a and is detected by the light receiving element 2 disposed behind the rotating slit plate 3.

  FIG. 2 is a side view showing a substantial structure of the optical rotary encoder excluding the light receiving element 2. In FIG. 2, a rotating shaft 5 connected to a detected shaft provided on a detection target is rotatably supported by a housing 6 of the optical rotary encoder via a bearing 7. The rotary slit plate 3 is placed on a flange portion 5 a provided on the rotary shaft 5 and attached coaxially, and rotates integrally with the rotary shaft 5. The fixed slit plate 4 is attached to the housing 6 and faces the rotary slit plate 3. In order to assemble such an optical rotary encoder, first, the rotating shaft 5 is attached to the housing 6 via the bearing 7. Further, the light source 1 is mounted in the housing 6. Next, the fixed slit plate 4 is attached to the housing 6. Thereafter, the rotary slit plate 3 is attached to the rotary shaft 5.

  In the optical rotary encoder configured as described above, the slit 3a is formed in the rotary slit plate 3, and a center hole 3b for being coaxially attached to the rotary shaft 5 is formed in the center. The inner diameter of the center hole 3 b is formed larger than the outer diameter of the rotating shaft 5 and is loosely fitted to the rotating shaft 5. Further, slit plate origin marks 10 and 10 indicating the origin position of the rotary slit plate 3 are provided at two positions at an opening angle of 90 degrees on the periphery of the center hole. These slit plate origin marks 10, 10 are formed by thin lines extending radially from the center. It is desirable that the slit plate origin marks 10 and 10 be formed thin enough to be visible.

  On the other hand, on the end surface of the rotary shaft 5, rotary shaft origin marks 11, 11 indicating the origin position of the rotary shaft 5 are provided at two positions with an opening angle of 90 degrees. The origin marks 11 and 11 for the rotation axis may be changed to various shapes such as a diamond shape and a thin line in addition to the triangular mark as shown in the figure. It is desirable to make it a shape such as a polygon or a line that makes clear. Further, the positions of the rotation axis origin marks 11 and 11 are uniquely set with respect to a reference plane formed of a D-cut portion of the connecting portion 5 b formed on at least one end side of the rotation shaft 5.

  Next, referring to FIGS. 4 and 5, a method for positioning and centering the origin position will be described. First, the connecting portion 5b of the rotary shaft 5 protruding from the lower side of the rotary encoder is inserted into the fitting hole 7a provided in the jig 7 in a light press-fit manner. The fitting hole 7a is formed in a D shape corresponding to the D cut portion of the connecting portion 5b, and the flat portion 7b is joined to the D cut portion of the connecting portion 5b so that the rotary shaft 5 is positioned. Held in a state. Thereafter, the central hole 3b of the rotary slit plate 3 is inserted into the other end side of the rotary shaft 5 and placed on the flange portion 5a. From this state, the origin position and centering of the rotary slit plate 3 with respect to the rotary shaft 5 are adjusted. In this adjustment work, it is desirable to use the adjustment jig 8. The adjustment jig 8 is composed of an optical see-through mirror, a video camera, or the like, and as shown in FIG. 5, an image around the rotary shaft 5 and the central hole 3b of the rotary slit plate 3 can be viewed. . Further, an orthogonal reference line 8 a is provided in the image, and the intersection is made coincident with the center O of the rotation axis 5.

  When adjusting the origin position and centering, since the center hole 3b of the rotary slit plate 3 is loosely fitted to the rotary shaft 5, the rotary slit plate 3 is moved horizontally and vertically and obliquely. Initially, as shown in FIG. 5A, since the slit plate origin marks 10 and 10 are separated from the rotation axis origin marks 11 and 11, the center of the slit plate origin marks 10 and 10 is centered. The intersection C of the virtual extension line directed in the direction is separated from the axis O of the rotation shaft 5. From this state, the rotating slit plate 3 is moved to the reference line 8a of the adjusting jig 8 so that the two slit plate origin marks 10 and 10 overlap. As a result, as shown in FIG. 5B, the virtual extension line toward the center direction of the slit plate origin marks 10 and 10 coincides with the rotation axis origin marks 11 and 11, and the rotation slit with respect to the rotation axis 5 is aligned. The origin position and centering of the plate 3 are positioned with high accuracy.

  That is, both the origin position and the centering can be matched only when the virtual extension lines of the two slit plate origin marks 10 and 10 and the two rotation axis origin marks 11 and 11 are matched. However, when one of the slit plate origin marks 10 is displaced, the centering cannot be matched even if the origin positions can be matched. It should be noted that the adjustment is made visually without using the adjustment jig 8 so that the virtual extension lines of the two slit plate origin marks 10 and 10 and the two rotation axis origin marks 11 and 11 coincide. May be.

  As described above, after positioning the rotary slit plate 3 with respect to the rotary shaft 5, the attachment work is completed by fixing the periphery of the central hole 3b of the rotary slit plate 3 and the rotary shaft 5 with the adhesive.

  FIG. 6 is a plan view showing a second embodiment of the present invention. The second embodiment is different from the first embodiment described above in that the opening angle θ between the slit plate origin marks 12 and 12 and the rotation axis origin marks 13 and 13 is set to 120 degrees. . As described above, in order to position and attach the origin position and centering of the rotary slit plate 3 with high accuracy to the rotary shaft 5, the virtual extension lines of the slit plate origin marks 12 and 12 and the rotary axis origin mark It is only necessary to adjust so that 13 and 13 coincide with each other. At this time, the intersection C of the virtual extension lines of the two slit plate origin marks 12, 12 coincides with the axis O of the rotating shaft 5. As described above, even when the opening angle θ between the slit plate origin marks 12 and 12 and the rotation axis origin marks 13 and 13 is set to 120 degrees, the rotation axis 5 is set in the same manner as in the first embodiment. Thus, the origin position and centering of the rotary slit plate 3 can be positioned and attached with high accuracy.

  Therefore, the opening angle of the slit plate origin mark and the rotation axis origin mark can be set arbitrarily. However, when the open angle is 10 degrees or less, or 170 degrees or more, the intersection C of the virtual extension line is unclear, so it is desirable to set the angle around 90 degrees. In FIG. 6, the rotation axis origin marks 13 are formed by thin lines extending in the radial direction from the center. In order to position the rotary slit plate 3 with high accuracy, it is desirable to form the rotary axis origin marks 13 and 13 as thin as visible.

  7A and 7B are plan views showing a third embodiment of the present invention. This third embodiment is different from the first embodiment described above in that a rotation axis origin mark 14 and an axis mark 15 indicating the axis center are provided on the other end face of the rotation shaft 5. It is provided. When the origin position and the centering are adjusted according to the third embodiment, initially, as shown in FIG. 7A, the slit plate origin mark 10 with respect to the rotation axis origin mark 14 and the axis mark 15, Since 10 is separated, the intersection C of the virtual extension line toward the center of the slit plate origin mark 10, 10 is separated from the axis mark 15. From this state, the rotary slit plate 3 is moved so that the virtual extension lines of the slit plate origin marks 10 and 10 coincide with the rotation axis origin mark 14 and the axis mark 15 as shown in FIG. . As a result, the origin position and centering of the rotary slit plate 3 with respect to the rotary shaft 5 are positioned with high accuracy.

  Also in the third embodiment, only when the virtual extension line of the two slit plate origin marks 10 and 10 and the rotation axis origin mark 14 and the axis mark 15 of the rotation shaft 5 coincide with each other, the origin position is obtained. Both centering can be matched. However, when one of the slit plate origin marks 10 is displaced, the centering cannot be matched even if the origin positions can be matched, as in the first embodiment described above.

  FIG. 8 is a perspective view showing a modified example of the rotation axis origin mark provided on the rotation shaft 5. In each of the above-described embodiments, the origin mark for the rotating shaft and the like are formed by, for example, printing or chemical etching. The rotation axis origin marks 16 and 16 shown in FIG. 8 are mechanically formed. That is, by pressing a punch (not shown) like a knife edge against the peripheral corner of the rotating shaft 5, wedge-shaped origin marks 16 and 16 for the rotating shaft are formed.

  By forming the wedge-shaped rotation axis origin marks 16 and 16 in this way, the apex of the wedge portion accurately represents the origin position. Therefore, the virtual extension line of the slit plate origin marks 10 and 10 is used as the rotation axis origin mark. By aligning with the apexes 16 and 16, the rotary slit plate 3 can be positioned and attached to the rotary shaft 5 with high accuracy.

  In each of the above-described embodiments, two slit plate origin marks and two rotary shaft origin marks are provided, but they may be provided at a plurality of three or more locations. Further, the shape of both marks may be changed to other shapes besides the above-described embodiment. Further, in each figure, the inner diameter of the center hole 3b formed in the rotating slit plate is shown to be significantly larger than the outer diameter of the rotating shaft for convenience, but the difference between these diameters is substantially 1 mm or less. May be. Furthermore, the attachment means between the rotating shaft and the rotating slit plate may be changed to a mechanically known fixing means other than bonding, and is not limited to the above-described embodiments, and does not depart from the present invention. It can be deformed with.

  The present invention can be applied to an absolute type optical rotary encoder that detects an absolute rotation angle or an incremental type optical rotary encoder that detects a relative rotation angle.

It is a top view which shows the 1st Example of the rotary encoder concerning this invention. It is a perspective view which shows the fundamental structure of the rotary encoder concerning this invention. It is a side view which shows the substantial structure of the rotary encoder concerning this invention. It is explanatory drawing which shows the means to adjust the origin position and centering of the rotary encoder concerning this invention. (A) (B) is explanatory drawing which shows the origin position and the adjustment state of centering. It is a top view which shows the 2nd Example of the rotary encoder concerning this invention. (A) (B) is explanatory drawing which shows the origin position and centering adjustment state by 3rd Example in the rotary encoder concerning this invention. It is a perspective view which shows the 4th Example of the rotary encoder concerning this invention, and shows the modification of the origin mark for rotating shafts. (A) (B) is explanatory drawing which shows the positioning means of a rotating shaft and a rotating slit board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Rotating slit board 3a Slit 3b Center hole 5 Rotating shaft 5a Flange part 5b Connection part 7 Fixed support protrusion 8 Movable member 9 Support arm 10 Slit plate origin mark 11 Rotating axis origin mark 15 Axis mark O Axis C C Virtual extension Line intersection

Claims (2)

A rotary encoder in which a rotary slit plate is positioned and fixed to a rotary shaft connected to a detected shaft,
The rotary slit plate is formed with a central hole loosely fitted to the rotary shaft at the center, and at the periphery of the central hole, slit plate origin marks indicating the origin position of the rotary slit plate are provided in at least two places,
The rotation axis is provided with a rotation axis origin mark indicating the origin position of the rotation axis, and an axis mark indicating the axis center ,
The rotary slit plate is attached to the rotary shaft at a position where virtual extension lines toward the centers of the slit plate origin marks at least two positions coincide with the rotary axis origin mark and the axis mark. Rotary encoder.   2. The rotating slit plate according to claim 1, wherein two thin lines extending radially from the center are formed at a peripheral edge of the center hole, and the two thin lines are formed at an opening angle at which a virtual extension line toward the center intersects. The described rotary encoder.

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