JP4968056B2 - OPTICAL ENCODER, LIGHT EMITTING DEVICE FIXING METHOD, AND MOTOR HAVING OPTICAL ENCODER - Google Patents

Description

The present invention relates to an optical encoder having a light-emitting element made of a translucent resin, a method for fixing the light-emitting element, and a motor provided with the optical encoder.

As a conventional method of fixing the light emitting element of the encoder to the case, there is a method in which the light emitting element is fitted and inserted into a cylindrical hole provided in the case, and the flange portion of the light emitting element is abutted and fixed to the case. In FIG. 4, 101 is a light emitting element, 102 is a case for fixing and holding the light emitting element, 104 is a translucent resin part of the light emitting element, 106 is a case taper part, 107 is a flange part of the light emitting element, and CL is in the optical axis direction. The light emitting element 101 is fitted and inserted into a cylindrical hole provided in the case 102, the flange portion 107 provided in the light emitting element 101 and the case 102 for fixing and holding are abutted, and the flange portion 107 of the light emitting element 101 is Adhesion is fixed by applying an adhesive to the entire circumference.
There is a gap in the inscribed portion between the translucent resin portion 104 of the light emitting element 101 and the case 102 for fixing and holding, and a small amount of adhesive flows into the gap when the adhesive is applied to the flange portion 107. Adheres to the adhesive resin portion 104 and cures.

    As a method for fixing a light emitting element with an adhesive, a method of fixing an LED lens portion inserted into a frame cylindrical portion with an adhesive is shown as a similar method. (For example, see Patent Document 1).

Further, as a method of fixing the light emitting element without using the adhesive as described above, a method of fixing the light emitting element by a locking means in which a part of the side wall of the case is elastically formed is shown ( For example, see Patent Document 2).

Japanese Patent Laid-Open No. 05-340765 (page 4, FIG. 1) Japanese Utility Model Publication No. 62-055113 (page 6-8, FIG. 1)

  In the fixing method using the adhesive, it is difficult to replace and replace the light emitting element after once bonding, such as a decrease in transmittance due to adhesion of the adhesive to the translucent resin portion in the optical axis direction at the time of bonding, or failure. There were problems such as the complexity of the fixing work with the agent and the increase in assembly man-hours.

  Also, depending on the amount of gap when the light emitting element is fitted and inserted into the case for fixing and holding, the amount of adhesive applied, etc., the central axis between the light emitting element after bonding and fixing and the hole provided in the case for fixing and holding Are not coincident with each other, and the light emitting element may be misaligned with respect to the hole provided in the case for fixing and holding. There is a problem that a deviation occurs, which causes a non-uniform balance of signal outputs of the light receiving elements.

Furthermore, the same axis misalignment may occur due to the shrinkage stress during the curing reaction of the adhesive and the thermal stress after curing, and this axis misalignment may change the output balance of the light receiving element signal over time. As a result, there is a problem that the absolute integration error of the detection angle of the encoder increases due to a change in the optical waveform, resulting in a deterioration in angle detection accuracy.
On the other hand, in the above-described conventional method using no adhesive, the light emitting element is held and fixed by a very small part of the side wall, so that there is a problem that the same shift of the central axis is likely to occur.

  The present invention has been made in view of such problems, and facilitates assembly of the encoder, prevents axial deviation of the central axis between the light emitting element and the case for fixing and holding, and improves detection accuracy. It is an object of the present invention to provide an encoder capable of performing the above, a light emitting element fixing method of the encoder, and a motor including the encoder.

In order to solve the above problems, the present invention is configured as follows.
According to a first aspect of the present invention, a light receiving element, a rotating disk facing the light receiving element through a gap, a light emitting element opposed to the light receiving element across the rotating disk, and a case for holding the light emitting element fixedly, In the optical encoder provided with the signal processing circuit board, the light emitting element has a convex portion on the outer periphery of the bottom surface, the case is an elastic body, and the inner diameter is equal to or less than the outer diameter of the convex portion. It has a concave part.
According to a second aspect of the present invention, the case according to the first aspect is elastically deformed to have a notch when the convex portion is inserted into the concave portion.
According to a third aspect of the present invention, a plurality of protrusions are provided on the convex portion of the optical encoder according to the first or second aspect.
According to a fourth aspect of the present invention, the tip shape of the plurality of protrusions of the optical encoder according to the third aspect is an acute cone shape.
According to a fifth aspect of the present invention, the plurality of protrusions of the optical encoder according to the third to fourth aspects are made of an elastic body that can be elastically deformed.
According to a sixth aspect of the present invention, the plurality of protrusions of the optical encoder according to the third to fifth aspects are integrally formed with the outer peripheral portion of the bottom surface.
The invention according to claim 7 is the light emitting element fixing method of the optical encoder according to any one of claims 1 to 6, wherein the case is elastically deformed, the convex part is inserted into the concave part, A case fixedly holds the light emitting element.
According to an eighth aspect of the present invention, the optical encoder according to the first aspect is attached to a shaft that is a motor rotation shaft.

According to the first to seventh aspects of the invention, since the light emitting element is fixed without using an adhesive, the transmittance decreases due to adhesion of the adhesive when using the adhesive, and the shrinkage stress during the curing reaction of the adhesive. Further, it is possible to prevent the shaft shake due to the influence of the thermal stress after curing and to match the central axes of the light emitting element and the case for fixing and holding, and as a result, it is possible to provide an encoder with high angle detection accuracy. Furthermore, the replacement and replacement of the light emitting elements can be facilitated, and the number of work steps can be reduced by reducing the adhesive fixing work.
According to the eighth aspect of the invention, a motor including an encoder with high angle detection accuracy can be obtained.

    Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The present invention is different from the prior art in that a convex portion 5 is provided in a light-transmitting resin of a light emitting element and a concave portion 3 is provided in a case.
FIG. 1 is a perspective view in which a light emitting element 1 and a case 2 of an encoder of the present invention are fixed. In the figure, 1 is a light emitting element, 2 is a case, 3 is a concave part of the case, 4 is a translucent resin part of the light emitting element, and 5 is a convex part provided on the outer periphery of the bottom surface of the light emitting element. The light emitting element 1 is inserted and fixed to the case 2. A concave portion 3 is provided in the case 2 and a convex portion 5 is provided in the light emitting element 1. The case 2 has a cutout portion that is elastically deformed so that the convex portion 5 of the light emitting element can be inserted into the concave portion 3 of the case when the light emitting element 1 is inserted. In this embodiment, as shown in the figure, the recess 3 is provided in a range slightly larger than a half circumference and is set to 190 degrees. The remaining 170 degrees is the notch. Further, the inner peripheral diameter of the concave portion 3 of the case is smaller than the diameter of the disk-shaped convex portion 5 of the light emitting element. In this embodiment, the diameter of the disk-shaped convex portion 5 of the light emitting element is 10 mm. The inner diameter of the recess 3 is 9.5 mm. The light emitting element can be inserted and fixed from the direction perpendicular to the optical axis direction (CL) by elastic deformation of the notch of the case 2, and the convex part 5 of the light emitting element is firmly fixed by the concave part 3 of the case after the insertion. Retained.

In the above-described embodiment, the light emitting element 1 is inserted and fixed from the direction perpendicular to the optical axis. Therefore, an example in which a cutout portion of about a half circumference is provided is shown, but the light emitting element 1 may be inserted from the optical axis direction. good. In this case, the cutout portion of the case has only to be wide enough to allow the light emitting element 1 to be inserted, the cutout portion can be made small, and the holding and fixing can be more firmly and reliably performed.
Further, if the hole for inserting and fixing the light emitting element provided in the case is elastically deformed so that the convex part of the light emitting element can be accommodated and fixed, it is not necessary to provide a notch.

FIG. 2 shows a second embodiment of the present invention. The difference from the first embodiment is that a plurality of cylindrical protrusions 6 are provided on the circumference of the light emitting element convex portion 5. Compared to the light emitting element convex portion 5 of Example 1, because of the locking between the plurality of intermittent protrusions 6 and the concave portion 3 of the case 2, the light emitting element is less likely to be rotated due to slipping between the two, and the weight is reduced. The light emitting element 1 can be efficiently fixed to the case 2.
The same effect can be obtained by replacing the cylindrical protrusion 6 with a conical protrusion (not shown) having a sharp contact portion with the recess 3 of the case.
If elastically deformable members such as rubber are used for the protrusions 6, the light emitting element can be easily inserted and fixed, and the amount of elastic deformation of the fixing and holding case 2 when the light emitting element 1 is inserted can be reduced. In addition, the notch can be made small.
The protrusion 6 may be formed integrally with the outer peripheral portion of the bottom surface of the light emitting element, or may be bonded after being manufactured as a separate part.

FIG. 3 shows a cross-sectional view (only the encoder portion) when the encoder of the present invention is attached to a motor. In the figure, 1 is a light emitting element, 2 is a case, 8 is a motor body, 9 is an encoder cover, 10 is a signal circuit board for receiving a light receiving element and processing a detection signal, 11 is a housing for storing sensor components, 12 Is a rotating disk, and 13 is a shaft. Light emitted from the light emitting element fixed to the case via the shaft 13 coupled to the motor rotating shaft is detected by the light receiving element, and this signal is processed by the circuit board 10. The rotation angle of the motor shaft is detected, and the rotation angle of the motor is controlled from this signal.

1 is a perspective view of a light emitting element and a case of an optical encoder according to a first embodiment of the present invention. The perspective view of the light emitting element and case of the optical encoder by 2nd Example of this invention Sectional view of a motor equipped with an optical encoder according to the present invention (encoder part only) Sectional view of light emitting element and case of conventional optical encoder

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,101 Light emitting element 2,102 Case 3,103 Case recessed part 4,104 Translucent resin part 5 Light emitting element convex part 6 Projection 106 Case taper part 107 Flange part 8 Motor main body 9 Encoder cover 10 Circuit board 11 Housing 12 Rotating disk 13 Shaft

Claims (8)

A light receiving element; a rotating disk facing the light receiving element through a gap; a light emitting element opposed to the light receiving element across the rotating disk; a case for holding the light emitting element fixed; and a signal processing circuit board. In the optical encoder provided,
The light emitting element has a convex portion on the outer periphery of its bottom surface;
An optical encoder, wherein the case is an elastic body and has a concave portion having an inner diameter equal to or smaller than the outer diameter of the convex portion.   The optical encoder according to claim 1, further comprising a cutout portion when the case is elastically deformed and the convex portion is inserted into the concave portion. The optical encoder according to claim 1, wherein a plurality of protrusions are provided on the convex portion. The optical encoder according to claim 3, wherein tip shapes of the plurality of protrusions have an acute cone shape. 5. The optical encoder according to claim 3, wherein the plurality of protrusions are elastic bodies that can be elastically deformed.   6. The optical encoder according to claim 3, wherein the plurality of protrusions are formed integrally with the outer peripheral portion of the bottom surface of the light emitting element. In the light emitting element fixing method of the optical encoder according to any one of claims 1 to 6,
Elastically deforming the case, inserting the convex portion into the concave portion,
A method for fixing a light emitting element of an optical encoder, wherein the case holds the light emitting element fixedly.   A motor comprising the optical encoder according to claim 1 attached to a shaft that is a motor rotation shaft.

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