JP3121874B2 - Optical fiber encoder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber encoder, and in particular, a reflection section and a non-reflection section are alternately formed as one of the patterns, and the ratio of the reflection section and the non-reflection section in one pitch is evenly divided. The formed temperature compensating track is provided, and the voltage of the temperature compensating signal obtained from this track is changed to an angle or speed detecting signal (1 or 0) by the amount of reflected light at the time of reflection being about half that at the time of total reflection. ) For a new improvement to half the level.

[0002]

2. Description of the Related Art Conventionally, in the case of an optical fiber encoder generally employed, as an angle or speed detection signal, as shown in FIG. 5, one of an angle or speed detection signal A indicated by a solid line is used. The temperature compensation signal B was output at the level position.

[0003]

The conventional optical fiber encoder has the following problems since it has been configured as described above. That is, the temperature compensation signal is
Since a one-level signal is always obtained by using a track based on total reflection, it is not possible to compensate for a zero-level movement due to a change in temperature, and it is only possible to achieve one-level compensation. It was extremely difficult to improve the accuracy.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and in particular, a reflection portion and a non-reflection portion are alternately formed in a pattern, and the reflection portion and the non-reflection portion within one pitch are formed. A temperature compensating track is formed in which the ratio is formed in half, and the voltage of the temperature compensating signal obtained from this track is used to detect the angle or speed by detecting that the amount of reflected light at the time of reflection is about half that at the time of total reflection. It is an object of the present invention to provide an optical fiber encoder in which a signal (1 or 0) has a half level.

[0005]

SUMMARY OF THE INVENTION An optical fiber encoder according to the present invention guides light from a light emitter to first, second, and third patterns formed on a movable body via an optical fiber. In an optical fiber encoder wherein light detected by reflection from first, second, and third patterns is detected by a photoreceptor, the first pattern has a pitch shorter than a core diameter of the optical fiber and a reflecting portion. And a non-reflection portion are formed alternately, and the pitch is formed such that the ratio of the reflection portion and the non-reflection portion is half and half in the pitch.

[0006] More specifically, the moving body is constituted by a rotating body.

[0007] More specifically, the moving body is constituted by a linear moving body.

[0008]

In the optical fiber encoder according to the present invention, as described above, the proportion of the reflection part and the non-reflection part of the temperature compensating track in which the reflection part and the non-reflection part are alternately formed is formed in half. Since the pitch L is shorter than the core diameter of the optical fiber, the output voltage of the temperature compensation signal obtained from this optical fiber is located at half of the light quantity of the 1 or 0 angle or speed detection signal, that is, at the center. This is an output level, and therefore, even if a temperature change occurs, the temperature compensation signal always becomes the center of the angle or speed detection signal, and can compensate for any of the 1 level and the 0 level.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the optical fiber encoder according to the present invention will be described below in detail with reference to the drawings. FIG.
1 to 4 show an optical fiber encoder according to the present invention. FIG. 1 is a configuration diagram, FIG. 2 is an enlarged perspective view showing an optical fiber, FIG. 3 is a pattern diagram, and FIG. FIG.

That is, what is indicated by the reference numeral 1 in FIG. 1 is a rotating shaft rotatably provided in a casing 2 via a bearing 3.
A rotating plate 29 having a first pattern 4, a second pattern 5, and a third pattern 6 having a predetermined pattern shape shown on the surface 7a thereof is integrally mounted. The first pattern 4 constitutes a track for temperature compensation, and the track for temperature compensation has, as shown in FIG. 3, reflection portions 4a and non-reflection portions 4b formed alternately and continuously.

An optical connector 8 is provided in the casing 2, and an optical distributor 10 is connected to the optical connector 8 via a first optical fiber 9. , The second optical fibers 1 each having a significantly different length
1, a third optical fiber 12 and a fourth optical fiber 13 are provided.

The first detection light outlet 11a of the second optical fiber 11 is positioned corresponding to the first pattern 4, and the second detection light outlet 12a of the fourth optical fiber 12 is connected to the second pattern. 5 correspondingly, and the fourth
The second detection light outlet 13 a of the optical fiber 13 is located corresponding to the third pattern 6, and the core diameter d which is the inner diameter of the second optical fiber 11 is smaller than the pitch L of the first pattern 4. , D> L. Also, this pitch L
As shown in FIG. 3, the ratio of the reflection portion 4a and the non-reflection portion 4b is formed in half.

The length of each of the optical fibers 11, 12, and 13 from the optical distributor 10 is represented by a code.
11 <12 <13. The optical connector 8 has a fifth optical fiber 14 which is a single-core optical fiber.
The optical coupler 15 is provided with a human-powered optical fiber 16 facing the light-emitting body 17.

A photoreceptor 19 is disposed opposite the output light outlet 18a of the output optical fiber 18 provided in the optical coupler 15.

The optical fiber encoder according to the present invention is configured as described above, and its operation will be described below. First, light from the light emitter 17 is transmitted through the optical fiber for human power 16, the optical coupler 15, the fifth optical fiber 14, the optical connector 8, the first optical fiber 9, and the optical distributor 10,
Each detection light outlet 11 of each optical fiber 11, 12 and 13
a, 12a and 13a, each pattern 4, 5 and 6
Reach the top.

Each of these optical fibers 11, 12 and 13
Are different from each other and are set to the above-described relationship, the light from the second optical fiber 11 reaches the first pattern 4 earliest, reads the first pattern 4, and the read optical signal is The light is received by the photoreceptor 19 from the output light outlet 18a of the output optical fiber 18 through the above-described path in reverse.

The optical signals obtained by reading the second pattern 5 and the third pattern 6 through the other third optical fiber 12 and the fourth optical fiber 13 have a time difference delayed from the first optical signal. The light is received by the photoreceptor 19 as a serial signal.

Accordingly, the serial signals obtained by reading the patterns 4, 5 and 6 are read out from the photoreceptor 19 with a time difference from each other, and the temperature is compensated by the first pattern 4. Signal B and angle or speed detection signal A such as the number of rotations and rotation angle of the rotating shaft 1
Can be obtained.

The temperature compensating signal B is equal to the aforementioned d.
Due to the relationship> L, as described above, the ratio of the reflection portion 4a and the non-reflection portion 4b within the pitch L is half, so that the amount of reflected light is half of the total reflection, as shown in FIG. As described above, one level of the angle or speed detection signal A and 0
Since the level is １ ／ of the level, even when a temperature change occurs, the temperature compensation signal B is always located at the center between the 1 level and the 0 level of the angle or speed detection signal A,
It is possible to perform temperature compensation including a 0 level fluctuation due to a temperature change. Further, in the above-described embodiment, the moving body 29 is a rotating body. However, a similar effect can be obtained when the moving body 29 is a linear moving type.

[0020]

The optical fiber encoder according to the present invention has the following features.
With the above configuration, the following effects can be obtained. That is, the first of the temperature compensating trucks
While making the pattern a repetitive type of reflective part and non-reflective part,
The ratio of the reflection part and the non-reflection part in the pitch is halved, and the relationship between the pitch and the core diameter d which is the inner diameter of the optical fiber is represented by
> L, the amount of light in the temperature compensation signal is half of the total reflection and is half the level of the angle or speed detection signal, and is always at the center. can do.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an optical fiber encoder according to the present invention.

FIG. 2 is an enlarged perspective view showing the optical fiber of FIG.

FIG. 3 is a development view showing a first pattern (temperature compensation track) of FIG. 1;

FIG. 4 is a waveform chart showing an output signal.

FIG. 5 is a waveform diagram showing an output signal of a conventional optical fiber encoder.

[Explanation of symbols]

 4 pattern (track for temperature compensation) 4a reflective part 4b non-reflective part 5 pattern 6 pattern d core diameter (inner diameter) 11 optical fiber 12 optical fiber 13 optical fiber 17 light emitter 19 light receiver 21 light receiver L pitch

Claims (3)

(57) [Claims] The light from the luminous body (17) is transmitted to an optical fiber (1).
1, 12, 13...) To the first, second, and third patterns (4, 5, 6) formed on the moving body (29), and the first, second, and third patterns are guided. In an optical fiber encoder configured to detect light detected by reflection from a pattern (4, 5, 6) by a photoreceptor (19), the first pattern (4) has a core diameter of the optical fiber (11). d) having a pitch (L) shorter than that and having a track for temperature compensation in which the reflection part (4a) and the non-reflection part (4b) are formed alternately, and the reflection part ( An optical fiber encoder characterized in that the ratio of 4a) to the non-reflection portion (4b) is formed in half. 2. The optical fiber encoder according to claim 1, wherein said moving body comprises a rotating body. 3. The optical fiber encoder according to claim 1, wherein said moving body (29) comprises a linear moving body.