JPH06194185A - Rotary encoder - Google Patents

Abstract

PURPOSE:To provide a rotary encoder difficult to be broken even when subjected to a violent shock by providing a code disk without a center hole and a rotary shaft whose one end is adhesively connected perpendicularly to the center of the code disk. CONSTITUTION:The rotary encoder is provided with a code disk 10 without a center hole and a rotary shaft 20 whose one end is adhesively connected perpendicularly to the center of the code disk 10. The code disk 10 is made of a highly transparent glass and a code pattern blocking off the light is formed thereon. The rotary shaft 10 is provided with an expanded diameter part 22 adhesively connected to the code disk 10, and the expanded diameter part 22 is provided with a connection face 23 being in perpendicular contact with the code disk 10 and a recessed part 24 which is a little recessed from the connection face 23 and filled with an adhesive agent. The connection face 23 is annular and the recessed part 24 is composed of an outer recessed part 24a and an inner recessed part 24b in the annular connection face 23. The expanded diameter part 22 is provided with the other side outer face 25 almost parallel to the connection face 23, and a plurality of adhesive agent charging holes 26 for communicating the outer face 25 with the inner recessed part 24b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary encoder, and more particularly to a rotary encoder provided with a code disc having high impact strength.

[0002]

2. Description of the Related Art A rotary encoder is an angle detector used in machines such as NC machines and robots to accurately detect a rotation angle. In this rotary encoder, for example, as shown in FIG. 2, a code disk 1 is attached to a rotary shaft 2, and the rotary shaft is connected to a shaft (for example, a ball screw) of a detecting machine. A code pattern (not shown) that blocks light is formed on the surface of the code disk 1. Light from the light emitting diode 3 further passes through the slit 4 and hits the pattern, and a part of the light is detected by the photodiode 5. The angle of the rotary shaft 2 is detected. FIG. 3 is a side sectional view of the rotary encoder,
Light emitting diodes, photodiodes, slits, etc. are omitted. Reference numeral disc 1 is a disc having a central hole,
It is made of highly transparent glass. The disc 1 is fitted into one end of the rotary shaft 2 and fixed by a stopper 6. The rotating shaft 2 is supported by bearings 7 so that it can rotate smoothly.

[0003]

The rotary encoder described above is directly attached to the machine to be used and directly receives the vibration of the machine. Therefore, there is a problem that the rotary encoder may be severely impacted (for example, 1000 G or more) and the code disc of the rotary encoder may be broken. As a result of a detailed examination of the code disc ruptured by impact, the inventors found that the rupture starts from the center hole of the code disc. Further, as a result of inspecting the fracture surface with a microscope or the like, it was found that there are small chippings and microcracks at the corners of the edge of the central hole, which serve as nuclei for stress concentration.

The present invention was created based on the above-mentioned new knowledge. That is, an object of the present invention is to provide a rotary encoder that is hard to break even when it receives a strong impact.

[0005]

According to the present invention, there is provided a rotary encoder provided with a code disk having no central hole and a rotary shaft having one end thereof bonded and joined perpendicularly to the center of the code disk. Will be provided. According to a preferred embodiment of the present invention, the rotary shaft has an enlarged diameter portion that is adhesively joined to the code disc, and the enlarged diameter portion has a joining surface that is in vertical contact with the code disc, And a concave portion slightly recessed from the joint surface and filled with an adhesive. The joint surface is ring-shaped, the concave portion is composed of an outer concave portion and an inner concave portion of the ring-shaped joint surface, and the expanded diameter portion further includes an opposite outer surface substantially parallel to the joint surface and the outer surface. And a plurality of adhesive filling holes for communicating with the inner recess. Further, it is preferable that the code disc has a circular alignment mark concentric with the central axis on the outer peripheral portion thereof.

[0006]

According to the above-mentioned structure of the present invention, the code disc has no central hole, and therefore the rotary disc provided with the code disc is free from chipping and microcracks that are easily formed in the central hole and become cores of stress concentration. An encoder can be provided. Furthermore, according to a preferred embodiment of the present invention, the code disc has a circular alignment mark concentric with the central axis on its outer peripheral portion, and using this alignment mark, the code disc and the rotary shaft are Can be accurately centered.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a copy of the conventional sample discs (A), (B), and (C) fractured by impact, and the arrow in the figure indicates the starting point (start point) of fracture. . Conventionally, it was thought that impact would cause fracture from the outer periphery of the code disc, but the fracture pattern (Walner wire, etc.) that occurred on these samples and fracture surfaces may cause fracture from the center hole of the code disc. all right.

FIG. 5 is an enlarged schematic view of a central hole edge portion of a conventional code disk, which is enlarged by a microscope. Figure 5 (A)
Has a C-face at the edge, and this face is ground with a coarse grindstone of about # 400. There is chipping (indicated by c) at the corner between the C-face and the disc, and these are the cores of stress concentration. It is thought that it has become. Further, in FIG. 5 (B), the edge is C
The surface is ground with a fine grindstone of about # 600. Although it is smaller than that in FIG. 5A, small chipping is still observed and these are the core of stress concentration. it is conceivable that. These chippings occurred only at the edge corners. The present invention was created based on such new knowledge.

FIG. 1 is a plan view (A) showing a rotary encoder according to the present invention and a partial sectional view (B) taken along the line AA. In this figure, a rotary encoder according to the present invention comprises a code disk 10 having no central hole, and a rotary shaft 2 having one end thereof bonded and joined perpendicularly to the center of the code disk 10.
With 0 and. The code disk 10 is made of highly transparent glass, and has a code pattern (not shown) that blocks light, similar to a conventional code disk. Further, the code disk 10
Has a circular alignment mark 12 concentric with its central axis on its outer peripheral portion. By using this circular alignment mark 12, it is possible to accurately align the code disc and the rotation axis with a microscope or the like. In FIG. 1B, the outer peripheral portion of the code disc 10 is omitted for clarity of the drawing.

The rotary shaft 20 has an enlarged diameter portion 22 that is adhesively joined to the code disc 10, and the enlarged diameter portion 22 is a joining surface 23 that is in vertical contact with the reference disc 10 and from this joining surface 23. And a recess 24 that is slightly recessed and filled with adhesive. Since the joint surface 23 is in direct contact with the code disk 10, the rotary shaft 20 can be accurately orthogonal to the code disk 10. The joint surface 23 is ring-shaped, and the recess 24 is
The ring-shaped joint surface 23 has an outer recess 24a on the outer side and an inner recess 24b on the inner side. The adhesive may be filled only in the outer recess 24a, or may be filled in both the outer recess 24a and the inner recess 24b. With this configuration, the rotary shaft 20
It is possible to secure a large adhesion area while keeping the right angle with the code disc 10 accurately.

Further, the expanded diameter portion 22 has an opposite outer surface 25 substantially parallel to the joint surface 23, and the outer surface 25 and the inner recess 24b.
And a plurality of adhesive filling holes 26 for communicating with each other.
Confirming the reliable injection of the filler into the inner recess 24b by filling the inner recess 24b with the adhesive from one of the filling holes 26 and confirming that the adhesive comes out from the other filling hole 26. You can The adhesive used for adhesion is preferably a two-component epoxy resin, a UV type (ultraviolet curing type) adhesive, or the like. In the case of using the UV type adhesive, ultraviolet rays such as a mercury lamp are generated, and the filling of the inner concave portion 24b is performed by irradiating the bonding surface 23 for about 20 seconds through the transparent code disc 10. It can be reliably cured.

[0012]

As described above, according to the present invention, the code disc does not have a center hole, and therefore there is no chipping or microcrack which is easily formed in the center hole and becomes a nucleus of stress concentration. It is possible to provide a rotary encoder provided with. Furthermore, according to a preferred embodiment of the present invention, the code disc has a circular alignment mark concentric with the central axis on its outer peripheral portion, and using this alignment mark, the code disc and the rotary shaft are Can be accurately centered. Therefore, according to the present invention, it is possible to provide a rotary encoder that does not easily break even when subjected to a severe impact.

[Brief description of drawings]

FIG. 1 is a plan view (A) showing a rotary encoder according to the present invention and a partial cross-sectional view (B) taken along the line AA.

FIG. 2 is a configuration diagram of a conventional rotary encoder.

FIG. 3 is a side sectional view of a conventional rotary encoder.

FIG. 4 is a schematic view of samples (A), (B), and (C) of conventional code discs broken by impact.

FIG. 5 is a diagram schematically illustrating a center hole edge portion of a conventional code disc by enlarging it with a microscope.

[Explanation of symbols]

 1 Code Disc 2 Rotation Shaft 3 Light Emitting Diode 4 Slit 5 Photodiode 6 Stopper 7 Bearing 10 Code Disc 12 Alignment Mark 20 Rotation Axis 22 Expanded Part 23 Bonding Surface 24 Recess 25 Outer Surface 26 Adhesive Filling Hole

Claims (4)

[Claims] 1. A rotary encoder comprising: a code disc having no central hole; and a rotary shaft having one end thereof bonded and joined perpendicularly to the center of the code disc. 2. The rotating shaft has an enlarged diameter portion that is adhesively joined to the code disc, and the enlarged diameter portion has a joining surface that is in vertical contact with the reference disc and slightly from the joining surface. The rotary encoder according to claim 1, further comprising a concave portion filled with a concave adhesive. 3. The joint surface is ring-shaped, the recess comprises an outer recess on the outer side and an inner recess on the inner side of the ring-shaped joint surface, and the enlarged diameter portion is substantially parallel to the joint surface. 3. The rotary encoder according to claim 2, further comprising: an opposite outer surface; and a plurality of adhesive filling holes that connect the outer surface and the inner recess. 4. The rotary encoder according to claim 1, wherein the code disc has a circular alignment mark concentric with the central axis of the disc on its outer peripheral portion.