JPH0245774Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a code wheel for a reflective optical rotary encoder, and in particular, a method for irradiating light onto a pattern of reflective and non-reflective parts provided on the code wheel.
This invention relates to a code wheel of a reflective optical rotary encoder that uses this reflected light to read the number of rotations, direction of rotation, etc. of the code wheel.

[Background of the idea]

A conventional code wheel of this type of rotary encoder will be explained based on FIGS. 1, 2, and 3.

FIG. 1 is a perspective view showing the external appearance of a rotary encoder. A disc-shaped code wheel 2 is attached to the shaft 1a of a motor 1, and a disc-shaped code wheel 2 is attached to the flat upper surface 2a of the code wheel 2 at equal intervals radially. Arranged fan-shaped reflective parts 3 and non-reflective parts 4 located between the reflective parts are provided, and the upper surface 2
A light emitting element 5 facing the light emitting element 5 and two light receiving elements 6 and 7 arranged on both sides of the light emitting element 5 are installed via optical fibers 8, 9 and 10, respectively. When the code wheel 2 rotates, the light from the light emitting element 5 is reflected by the reflection section 3,
By receiving the light as continuous pulse signals in the two light receiving elements 6 and 7, the code wheel 2
It is designed to read the rotation speed and direction of rotation.

FIG. 2 shows a conventional example of a code wheel used in the above-mentioned encoder. A code wheel 2 formed in a disc shape from a non-reflective material as shown in FIG. A fan-shaped reflective portion 3 as shown in FIG. 2b is laminated on the upper surface 2a by hot stamping or vapor deposition, and
The upper surface 2a of the code wheel between adjacent reflective parts 3 is configured as a non-reflective part 4.

In this conventional code wheel, the method of forming the reflective portion 3 itself is relatively expensive, and
It is not suitable for mass production and it is difficult to reduce costs.

FIG. 3 shows another conventional code wheel, in which the disc-shaped code wheel 11 itself is made of a reflective material, and the upper surface 11a is made of a non-reflective material with fan-shaped slits 12a arranged radially. A mask 12 is attached, and the upper surface 11a of the code wheel exposed through the slit 12a is used as a reflective part.
The mask 12 is constructed as a non-reflective portion.

However, in the case of this code wheel, since the slit 12a of the mask 12 is formed by press punching of a flat plate or etching, the reflective part and the non-reflective part constituted by the edge of the slit 12a. This has the drawback that the accuracy of the separation between the two and the optical pulses decreases, and the resolution of an encoder that reads data using optical pulses does not improve.

[Purpose of invention]

The present invention has been made in view of the above points, and aims to provide a code wheel for a reflective optical rotary encoder that is mass-producible, low cost, and has high resolution.

[Summary of the idea]

In a reflective optical rotary encoder in which light is irradiated onto a reflective part and a non-reflective part provided on a code wheel, and the number of rotations, rotation direction, etc. of the code wheel are read by the reflected light, the non-reflective part is formed by photo-sensing. A pattern member formed by vapor-depositing an aluminum thin film to serve as the reflective portion on the back surface of a negative film is laminated on the code wheel.

[Example of idea]

Embodiments of the present invention will be described below based on the drawings.

FIG. 4 is an exploded perspective view showing the first embodiment of the present invention, in which a code wheel 17 is formed of a non-reflective material, and a negative film 14 is laminated and pasted on the upper surface 17a with an aluminum thin film 18 interposed therebetween. This is what I wore. This negative film 14 is code wheel 1
7, and a large number of fan-shaped transparent non-exposed portions 14a are formed radially at equal intervals. Therefore, the black exposed portions located between adjacent non-exposed portions 14a serve as non-reflective portions 15. The aluminum thin film 18 is previously formed on the back surface of the negative film 14 by vapor deposition.
4 and the aluminum thin film 18 constitute an integrated pattern member A, and the aluminum thin film 18 seen from the non-exposed portion 14a of the negative film 14 constitutes the reflective portion 18a.

In FIG. 5, a reflective part 20 and a non-reflective part 21 are formed on the outer circumferential surface 19a of the code wheel 19, and a light emitting element 2 is arranged so as to irradiate light onto the outer circumferential surface 19a.
2. The light receiving elements 23 and 24 are connected to optical fibers 25 and 2.
6 and 27 are shown. FIG. 6 shows an example of the code wheel 19 in this type of encoder.
In this embodiment, the code wheel 32 is made of a non-reflective material as in the first embodiment, and a thin aluminum film 33 is deposited on the back surface of the outer peripheral surface 32a of the code wheel 32 by vapor deposition, as in the first embodiment. A laminated negative film 34 is wound and attached.
Therefore, the aluminum thin film 33 seen from the non-exposed portion 34a of the negative film 34 constitutes the reflective portion 35, and the exposed portion constitutes the non-reflective portion 36. This negative film 34 and aluminum thin film 33 constitute an integrated pattern member A.

[Effects of this invention]

As described above, the present invention has a clear boundary between the reflective part and the non-reflective part, extremely high parting accuracy, and improved resolution.
Since it has the function of a non-reflective part, even if the code wheel surface is not precisely machined to be a horizontal plane, there is no risk of deterioration in resolution, and assembly is easy and costs can be reduced.

[Brief explanation of drawings]

Figure 1 is an external view of an encoder in which a reflective part and a non-reflective part are formed on the top surface of the code wheel.
The figures are diagrams explaining the structure and manufacturing method of a conventional code wheel, in which a is a perspective view of the code wheel material, b is a perspective view showing a state in which a reflective part is formed, and Fig. 3 is an exploded view of another conventional encoder. Perspective view, 4th
The figure is an exploded perspective view of the encoder according to the first embodiment of the present invention, FIG. FIG. 2 is an exploded perspective view of a code wheel in a second embodiment of the present invention applied to an encoder of the type; 17, 32... code wheel, 14, 34...
...Negative film, 15, 36...Non-reflective part, 18
a, 35...Reflection part, a...Pattern member.

Claims (1)

[Scope of utility model registration request] In a reflective optical rotary encoder that illuminates a reflective part and a non-reflective part provided on a code wheel and uses the reflected light to read the number of rotations, rotation direction, etc. of the code wheel, the non-reflective part is formed by exposure to light. 1. A reflective optical rotary encoder characterized in that a pattern member formed by vapor-depositing an aluminum thin film to serve as the reflective portion on the back surface of a negative film is laminated on the code wheel.