JPS6125019A - Optical rotary encoder - Google Patents

Abstract

PURPOSE:To make it possible to perform accurate measurement, by fixing a light receiving block, in which a light receiving element, a phase plate and a light guide are coupled, at a specified position in a casing, and adjusting the position by a tool through a position adjusting opening part. CONSTITUTION:In a body 11, a light projecting block 2, a rotary block and a light receiving block 4 are accommodated. The light receiving block 4 is constituted by coupling a light receiving element, a phase plate 44 and a light guide 45. The block 4 is fixed at a specified position in the casing 11 by fixing screws 61. A tool 64 is inserted in the casing 11 through a position adjusting opening part. Under the state an interval between the phase plate 44 and a code wheel is kept constant, the light receiving block 4 is moved in the direction perpendicular to the axial direction of a rotary shaft 32. Thus the position of the light receiving block is adjusted.

Description

[Detailed Description of the Invention] [Technical Field 1] The present invention relates to an optical rotary encoder, and more particularly, to an optical rotary encoder used for detecting the rotation speed and rotation direction of a motor and performing feedback control of the motor. It is.

[Background Art 1] Generally, as an optical rotary encoder for detecting the rotation speed and rotation direction of a motor, a structure as shown in FIG. 17 or 18 is provided. That is, this type of optical rotary encoder basically includes a code wheel 31 that is formed into a disk shape, rotates together with the rotating shaft 32, and has a large number of slits periodically formed along the circumferential direction of the rotating shaft 32. , a light emitting element 21 that emits light toward the code wheel 31, and a code wheel 31.
It has a plurality of light receiving elements 41 which receive the light transmitted through the slit and convert it into an electric signal. It is placed at a position to detect the phase. Therefore, when the code wheel 31 rotates, the direction of rotation can be determined from the phase difference between the signals detected by each light receiving element 41, and the number of rotations can be determined from the period of the signals.

However, if the positional relationship between the code wheel 31 and the light receiving element 41 shifts, the amount of light received by the light receiving element 41 will change, and the detected phase difference will also change, making the output waveform unstable. There are also problems such as measurement errors. For this reason, conventionally, by increasing the processing precision of parts, when placing each part, the code wheel 3
1 and the light-receiving element 41, however, increasing the resolution of the device requires extremely high component precision, which is too costly, so it is not practical to increase the resolution too much. It was impossible.

EObject of the Invention 1 The present invention has been made in view of the above-mentioned points, and its main purpose is to make it possible to adjust the positional relationship between the code wheel and the light-receiving element, thereby improving the processing accuracy of the parts. An object of the present invention is to provide an optical rotary encoder that allows accurate measurement through sufficient adjustment even if the cost is not very high.

[Disclosure 1 of the Invention In the present invention, a light receiving element, a phase plate, and a light guide are combined to form a light receiving block, and the light receiving block is fixed at a fixed position in a casing by a fixing means,
A position adjustment opening is formed on the side of the casing at a position corresponding to the light receiving block, and a jig inserted into the casing through the position adjustment opening keeps the distance between the phase plate and code wheel constant. By making it possible to move the light-receiving block in a direction perpendicular to the axial direction of the rotating shaft, even if the machining accuracy of the parts is not very high,
An optical rotary encoder that enables accurate measurement by adjusting the position of a light receiving block is disclosed.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. Second
As shown in the figure, the casing 1 includes a bottomed cylindrical body 11 with an open rear surface, an end cap 12 that closes the opening of the body 11, and a bottomed cylindrical body with an open front surface that is fitted onto the body 11. It is composed of a cover 13 having a shape. As shown in FIG. 14, a holding step 4 part 14 is formed on the inner surface of the body 11 near the opening, and a thin piece 15 extends from the holding step 14 to the opening edge over the entire circumference of the opening. It has become. The end cap 12 is inserted into the body 11 through the opening of the body 11, and is locked by the holding step 14. A tapered portion 16 whose diameter gradually decreases toward the rear is formed on the outer peripheral edge of the end cap 12, and the thin portion 15 is conically bent along the tapered portion 16 by a conical bending punch 8, as shown in FIG. By processing, the end cap 12 is held between the holding step portion 14 and the thin wall portion 15, and the body 11 and the end cap 12 are fixed together. In this way, the body 11 and the end cap 12 are fixed by caulking the thin wall portion 15 of the body 11, so compared to fixing with bolts, the effort of bolt tightening is omitted, This results in increased bonding strength without loosening due to vibration. The cover 13 is inserted into the body 11 with the end cap 12 and the body 11 integrated.

An insertion opening 18 into which a bushing 17 is inserted is opened at the bottom of the cover 13, and the electric wire 9 is drawn out through the bushing 17.

As shown in FIG. 1, a body 11 includes a light emitting block 2 in which a light emitting element 21 is inserted, a rotating block 3 configured by inserting a code wheel 31 into a rotating shaft 32, and a light receiving element 41. A light receiving block 4 having a light receiving block 4 is housed therein. Further, one end portion of the rotating shaft 32 protrudes from the body 11 through a through hole 19 formed in the body 11.

As shown in FIG. 4, the light projection block 2 includes a base 22 formed in a ring shape from an insulating material such as synthetic resin, and a light emitting element 21 such as an infrared light emitting diode fixed on the base 22. The bearing 24 is inserted into a through hole 23 formed in the center of the base 22. As shown in FIG.
5 in a fixed position within the body 11.

As shown in FIG. 5, the rotating block 3 has a code wheel 31 attached to a rotating shaft 32, and the code wheel 31 has a holding bush 33 press-fitted into the rotating shaft 32, and a holding bush 33 facing the holding bush 33. It is held between the disposed end bush 34 and rotates together with the rotating shaft 32. The code wheel 31 is shaped like a thin disk T#, and has a large number of direction detection slits 35 formed at equal intervals along the circumferential direction on its outer periphery. One rotation speed detection slit 36 is formed near the center. The direction detection slit 35 and the rotation speed detection slit 36 are provided at positions corresponding to the light emitting element 21, and the light emitted from the light emitting element 21 is transmitted through the direction detection slit 35 and the rotation speed detection slit 36. Rotating axis 3
2 is a bearing 2 whose one end is provided in the light projection block 2
4, and the other end is supported by a bearing 51 provided in the end cap 12, which will be described later.

The light receiving block 4 is placed on the opposite side of the light emitting block 2 across the code wheel 31, and as shown in FIG.
A substrate 42 is provided with three light receiving elements 41 that receive the light transmitted through the rotation speed detection slit 36 and convert it into an electrical signal, and a correction slit 43 is formed at a position corresponding to each light receiving element 41. phase plate 44
and a light guide 45 that is interposed between the phase plate 44 and the substrate 42 and guides the light transmitted through the 7-ray spray 44 to each light receiving element 41.

A pair of correction slits 43 are provided on the left and right at positions corresponding to the direction detection slit 35 of the code wheel 31, and one correction slit 43 is provided at a position corresponding to the rotation speed detection slit 36.

Each correction slit 43 is formed by a group of small slits, and corrects the light that passes through the direction detection slit 35 and the rotation speed detection slit 36 and whose intensity changes in a rectangular wave pattern so that it changes in a sine wave pattern. Three guide holes 46 are formed in the light guide 45 to correspond to each correction slit 43, and the inner peripheral surface of each guide hole 46 is black with a matte finish. Therefore, the light transmitted through each correction slit 43 is guided to each light receiving element 41 without being scattered or interfering with each other. The light-receiving element 41 converts light into an electrical signal, and a processing circuit (not shown) is mounted on the substrate 42 to which the light-receiving element 41 is fixed, which processes the electrical signal appropriately and outputs it. There is.

A pair of connecting legs 65 protrudes from the rear surface of the light guide 45, and the narrow diameter portion formed at the tip of the connecting legs 65 is inserted into the connecting hole 49 formed in the substrate 42, and in this state, the connecting legs 65 are connected to the substrate 42. The light guide 45 is fixed together with adhesive or heat caulking.

Further, a coupling protrusion 47 is provided protruding from the front surface of the light guide 45, and the coupling protrusion 47 is inserted into an engagement hole 48 formed in the phase plate 44, and the tip of the engagement protrusion 47 is heated and engaged. By engaging with the matching hole 48, the light guide 45 and the phase plate 44 are fixed together. As a result, the board 42 and the light guide 45
and the phase plate 44 are integrated to form the light receiving block 4. The phase plate 44 and the light guide 45 may be integrated by simultaneous molding, as shown in FIGS. 12 and 13.

By the way, as shown in FIG. 1, a through hole 52 is formed in the center of the end cap 12, a bearing 51 is inserted into the first half of the through hole 52, and a female threaded portion 53 is formed in the second half. has been done. The bearing 51 supports one end of the rotating shaft 32 as described above, and the first
As shown in FIG. 1, a locking step 37 is formed on the rotating shaft 32 and comes into contact with the front end surface of the inner ring 54 of the bearing 51. As shown in FIG.

Further, a position adjustment screw 55 is screwed into the female threaded portion 53, and the front end surface of the position adjustment screw 55 abuts on the outer ring 56 of the bearing 51. Therefore, by moving the position adjustment screw 55 back and forth, a preload of approximately 5% of the rated load is applied to the bearing 51, thereby preventing the bearing 51 from shaking back and forth. Furthermore, since the front end surface of the inner ring 54 of the bearing 51 is in contact with the locking step 37 formed on the rotating shaft 32, the axial movement of the rotating shaft 32 can be prevented by moving the position adjustment screw 55 forward or backward. The outside also comes off with prevention. In this way, instead of the conventional method of preventing rattling by stacking thrust washers with different thicknesses on the bearing 51 depending on the degree of rattling in the axial direction of the rotating shaft 32, this method eliminates the need to insert a thrust washer. This prevents the rotating shaft 32 from wobbling in the axial direction by simply adjusting the screwing amount of the position adjusting screw 55.

As shown in FIGS. 8 and 9, a pair of fixing screws 61 with sharp tips are inserted through the periphery of the end cap 12. As shown in FIGS. The fixing screw 61 is attached to the light receiving element 4 in the light receiving block 4.
They are respectively provided at positions rotated approximately 90 degrees left and right in the circumferential direction of the end cap 12 from the position corresponding to 1. When the fixing screw 61 is fully screwed in, its tip will bite into the substrate 42 on the rear side of the light receiving block 4, pressing the light receiving block 4 toward the support piece 62 protruding from the light projecting block 2, and supporting the light receiving block 4. It is held between the piece 62 and the fixing screw 61. As shown in Figure 7, body 1
Long position adjustment openings 63 are formed along the circumferential direction at positions corresponding to both fixing screws 61 on the side surface of the body 11, and a jig 64 is inserted into the body 11 through both position adjustment openings 63. It is designed so that it can be removed by insertion. The tip of the jig 64 is shaped to engage with the base of a connecting leg 65 that connects the substrate 42 of the light receiving block 4 and the light guide 45. A slight gap is formed between the body 11 and the light receiving block 4, and by using a jig 64, the light receiving block 4 can be moved in a direction substantially perpendicular to the rotating shaft 32 with the fixing screw 61 loosened. It is movable. After moving the light receiving block 4 in this way, if the fixing screw 61 is tightened, the light receiving block 4 is held between the fixing screw 61 and the support piece 62, so that the code wheel 31
The distance between the phase plate 44 and the phase plate 44 is
A constant distance is maintained before and after the movement of the light receiving element 4, and only the phase relationship between the code wheel 31 and the light receiving element 41 changes, so that the phase difference between the outputs of the light receiving elements 41 can be adjusted to a predetermined value. This makes it possible to obtain a desired phase difference output by correcting the assembly error of the light receiving block 4 with respect to the code wheel 31 during assembly.

In assembling the optical rotary encoder configured as described above, first, store the light emitting block 2 in the body 11 (herein) and attach it to the body 1 with the bolt 25.
1, then insert the rotating block 3 through the bearing 24 held in the light emitting block 2 and the through hole 19 of the body 11, and then insert the light receiving block 4 into the body 11, as described above. The end cap 12 is inserted into the opening of the body 11, and the thin part 15 formed in the opening of the body 11 is cut into the tapered part 16 by the conical bending punch 8.
, thereby integrating the body 11 and the end cap 12. Thereafter, as shown in FIG. 15, a plurality of V-notches 7 are formed in the thin wall portion 15 to prevent the end cap 12 from rotating relative to the body 11. Further, a cover 13 is fitted onto the body 11.
The cover 13 is prevented from being removed by fitting a plurality of V-notches 6 formed around the opening of the cover into the V-groove 5 formed on the outer peripheral surface of the body 11.

[Effects of the Invention 1] As described above, the present invention comprises a light receiving block by combining a light receiving element, a phase plate, and a light guide, and the light receiving block is fixed at a fixed position in a casing by a fixing means, and A position adjustment opening is formed at a position corresponding to the light receiving block, and a jig inserted into the casing through the position adjustment opening allows the light receiving block to be maintained at a constant distance between the phase plate and the code wheel. Since it is movable in a direction perpendicular to the axial direction of the rotating shaft, it has the advantage that even if the processing precision of the parts is not very high, accurate measurement can be made by adjusting the position of the light receiving block.

[Brief explanation of drawings]

Fig. 1 is an exploded perspective view showing one embodiment of the present invention, Fig. 2 is a vertical cross-sectional view of the same, Fig. 3 is a cross-sectional view of the steps taken along line X-X in Fig. 2, and Fig. 4 is used for the same. Exploded perspective view of fixed block,
Fig. 5 is an exploded perspective view of the code wheel and rotating shaft used in the above, Fig. 6 is an exploded perspective view showing the light receiving block used in the above, Fig. 7 is an exploded perspective view of the body and cover of the above, Fig. 8 is a longitudinal sectional view of the main part of the same as above, Fig. 9 is a cutaway perspective view of the main part of the same as above, Fig. 10 is a longitudinal sectional view of the main part of the same as above, and Fig. 11 is a longitudinal sectional view of the main part of the same as above.
12 is a perspective view showing another embodiment of the light receiving block used in the above, FIG. 13 is a longitudinal sectional view taken along the line X--X in FIG. 2, and FIG. 15 and 15 are cross-sectional views showing how to assemble the end cap and the body, FIG. 16 is a partial perspective view as seen from the end cap side, and FIG. 17 is a vertical cross-sectional view showing a conventional example. FIG. 18 is a longitudinal sectional view showing another conventional example. 1 is a casing, 4 is a light receiving block, 21 is a light emitting element,
31 is a code wheel, 32 is a rotating shaft, 35.36 is a slit, 41 is a light receiving element, 43 is a correction slit, 44 is a phase plate, 45 is a light guide, 61 is a fixing screw, 62 is a support piece, 63 is a position This is an opening for adjustment. Agent Patent Attorney Ishi 1) Chief 7 Figure 10 Figure 11 Figure 12 Figure 13 Figure 17 Old Figure Toro Kita-cho 5 and

Claims (2)

[Claims] (1) A casing, a rotating shaft with at least one end protruding from the casing, and a code wheel that is formed into a disc shape and rotates with the rotating shaft, and has a large number of slits periodically formed along the circumferential direction of the rotating shaft. A light-emitting element that emits light toward the code wheel, a plurality of light-receiving elements that receive the light transmitted through the slit of the code wheel, and convert it into electrical signals, and a light-emitting element that is interposed between the code wheel and the light-receiving element. A rotary encoder comprising a phase plate in which a correction slit corresponding to a light receiving element is formed, and a light guide interposed between the phase plate and the light receiving element to guide light transmitted through the correction slit of the phase plate to the light receiving element. The light-receiving element, the phase plate, and the light guide are combined to form a light-receiving block, and the light-receiving block is fixed at a fixed position in the casing by a fixing means, and a position adjustment device is provided on the side of the casing at a position corresponding to the light-receiving block. An opening is formed, and a jig inserted into the casing through the opening for position adjustment moves the light receiving block in a direction perpendicular to the axial direction of the rotation axis while keeping the distance between the phase plate and code wheel constant. An optical rotary encoder characterized in that it is movable. (2) The fixing means consists of a fixing screw with a pointed tip that is screwed into one end of the casing, and a support piece that is provided at a fixed position in the casing and holds the light receiving block between the tip of the fixing screw. An optical rotary encoder according to claim 1, characterized in that the optical rotary encoder comprises: