JPH05118876A - Optical fiber encoder - Google Patents

Abstract

PURPOSE:To enable an entire configuration to be compact by constituting a pattern with a polymerized multiple-layer reflection film with a wavelength dependency having mutually different reflection factor. CONSTITUTION:A pattern 4 is printed and formed by a reflection film which has a different wavelength dependency and consists of polymerized reflection layers 40-42 on a rotary plate 29, thus achieving reflection with different wavelength's lambda1-lambda3. When laser beams 17aA-17cA with a different wavelength are allowed to impinge on the pattern 4 from diodes 17a-17c through an optical fiber 14, the reflection layers 40 42 output signals with a reflection light of mutually different phases when a light with a corresponding wavelength enters, which is received by a photodiode 19 through one optical fiber 14 and another optical fiber 25 and then is output as a parallel signal, thus enabling a diameter of the rotary plate 29 to be reduced and at the same time a plurality of signals to be transmitted with a single optical fiber for achieving a miniaturized entire configuration.

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 more particularly, to a multi-channel rotation detection signal by one track and one optical fiber by using a superposition reflecting film having wavelength dependence of different reflectances. To new improvements to obtain.

[0002]

2. Description of the Related Art There are various optical fiber encoders of this type that have been conventionally used, and a typical one of them will be mentioned as a generally adopted structure shown in FIG. ..

That is, a reference numeral 1 in the drawing is a rotary shaft rotatably provided in a casing 2 through a bearing 3, and an upper portion of the rotary shaft 1 has a predetermined pattern shape. First pattern 4 and second pattern 8
And the rotary plate 29 having the third pattern 6 on its surface 7a.
Are integrally attached. In the casing 2,
An optical connector 8 is provided, and an optical distributor 10 is connected to the optical connector 8 via a first optical fiber 9, and the optical distributor 10 has first and second optical fibers 10 each having a greatly different length. Two optical fibers 11, 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 located correspondingly on the first pattern 4, and the third optical fiber 12
Of the second detection light outlet 12a of the fourth optical fiber 13 is located corresponding to the second pattern 5, and the third detection light outlet 13a of the fourth optical fiber 13 is located corresponding to the third pattern 6. ing.

The lengths of the respective optical fibers 11, 12 and 13 from the optical distributor 10 are represented by the following symbols:
The relationship is 11 <12 <13. An optical coupler 15 is coupled to the optical connector 8 via a fifth optical fiber 14 which is a single-core optical fiber. An input optical fiber 16 is provided in the optical coupler 15 so as to face a light emitting body 17. Has been. The output optical outlet 18a of the output optical fiber 18 provided in the optical coupler 15 is
The light receivers 19 are arranged so as to face each other. The conventional optical fiber absolute encoder is configured as described above, and its operation will be described below. First, the light from the light emitting body 17 is transmitted through the input optical fiber 16,
Optical coupler 15, fifth optical fiber 14, optical connector 8,
Through the first optical fiber 9 and the optical distributor 10, the detection light outlets 11a, 1 of the optical fibers 11, 12 and 13 are provided.
Each pattern 4, 5 and 6 is reached via 2a and 13a. The lengths of these optical fibers 11, 12 and 13 are different from each other and are set to the above-mentioned 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 goes through the above-mentioned route in reverse and the output optical outlet 18a of the output optical fiber 18 is outputted. Received by the photoreceptor 19. In addition, 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 are serially received as a photodetector with a time difference delayed from the first optical signal. 19
To be received.

Therefore, the serial signals obtained by reading the patterns 4, 5 and 6 are read from the photodetector 19 with a time lag from each other, and the number of revolutions of the rotary shaft 1 and Absolute rotation information such as the rotation angle can be obtained.

[0006]

Since the conventional optical fiber absolute encoder is configured as described above, it has the following problems. That is, since the absolute rotation information after reading each pattern on the rotating plate is a serial signal, the length of each optical fiber from the light distributor to each detection light outlet must be changed. Since it was necessary to make a difference of 10 m for each bit signal, the length of the optical fiber became abnormally long, which was the biggest obstacle to miniaturization. In addition, since all the patterns formed on the rotary plate were made of the same material, in the case of an absolute pattern, all the patterns had to be arranged in the radial direction, which resulted in the diameter of the rotary plate. Could not be miniaturized, and the encoder itself had to be upsized due to the use of a plurality of optical fibers.

The present invention has been made to solve the above problems, and in particular, by using a polymerized reflection film having wavelength dependence of different reflectances, one channel and one optical fiber are used for multi-channel. It is an object of the present invention to provide an optical fiber encoder adapted to obtain the rotation detection signal of the.

[0008]

In the optical fiber encoder according to the present invention, incident light from an optical fiber is made incident on a pattern formed on a moving body, and the pattern is read based on the emitted light from this pattern. In the optical fiber encoder, the pattern is
The pattern includes an A-phase signal and a B-phase signal having different phases, and an M-phase signal having a different phase from the A-phase signal. It is composed of a three-layer structure including.

More specifically, the optical fiber has only one optical fiber and the pattern has only one track.

[0010]

In the optical fiber encoder according to the present invention, since the pattern formed on the moving body is composed of the first, second and third reflection films having different wavelength dependences of reflectances, one First, second, and third incident light having different wavelengths in the optical fiber of the first, second, and third incident lights are incident on the pattern, but the first, second, and third reflected light reflected from the pattern As shown in FIG.
It is reflected by each reflective film having a different reflectance depending on the wavelength, and becomes an A-phase signal, a B-phase signal and an M-phase signal, and is converted into an electric signal by the photodiode. Therefore, the optical fiber encoder can be configured with only one optical fiber and one pattern (one track), and the overall configuration can be miniaturized.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the optical fiber encoder according to the present invention will be described in detail below with reference to the drawings. It should be noted that the same or equivalent portions as those of the conventional example will be described by attaching the same reference numerals. 1 to 4 are for showing an optical fiber encoder according to the present invention, in which FIG. 1 is a block diagram,
2 is an enlarged configuration diagram showing a main part of FIG. 1, FIG. 3 is a characteristic diagram of each signal, and FIG. 4 is a waveform diagram of each signal.

In FIG. 1, reference numeral 20 designates a first laser diode 17a, a second laser diode 17b and a third laser diode 17c having different wavelengths.
The first, second, and third laser beams 17aA, 17bA, and 17cA from the respective diodes 17a to 17c are continuous lights, and are a multiplexer 21 and a demultiplexer 22. It is sent to the optical fiber 14 via.

The tip 14a of the optical fiber 14 is arranged so as to face the one-track pattern 4 formed on the rotary plate 29 which is the moving body of the rotary shaft 1.

The demultiplexer 22 is connected via an optical fiber 25 to a photodiode section 19 having three photodiodes, which are photoreceptors, and an A phase signal which is an output from the photodiode section 19 is connected. 26, the B-phase signal 27, and the M-phase signal 28 are configured to be output in parallel via the amplifier 30.

The pattern 4 is composed of a polymerized multilayer reflective film composed of a first reflective layer 40, a second reflective layer 41 and a third reflective layer 42 formed on the rotary plate 29 by printing or the like. As shown in FIGS. 2 and 3, the reflective layers 40, 41, and 42 are configured to have different wavelength dependences of reflectance so as to reflect at different wavelengths of input 1, input 2, and input 3. ..

Therefore, in the above-mentioned structure, when the laser beams 17aA to 17cA having different wavelengths from the respective diodes 17a, 17b and 17c are made incident on the pattern 4 through one optical fiber 14, the incident lights are
In each of the reflection layers 40 to 42, when the incident light having the corresponding wavelength is incident, the reflected light is, as shown in FIG.
0, B-phase signal 51, M-phase signal 52, and this pattern 4 is output as each of these signals 50, 51, 52.
Has a three-layer structure.

Since these signals 50, 51, 52 have different wavelengths from each other, they are received by the photodiode 19 through one optical fiber 14 and another fiber 25, and are parallel signals shown in FIG. 50, B phase signal 51 and M phase signal 52. In addition, A
The phase signal and the B-phase signal 51 are 90 degrees out of phase with each other, and the M-phase signal 52 is a semi-absolute signal having a phase difference of 45 degrees with respect to the A-phase signal 50.

In the above-mentioned embodiment, the case where the moving body is the rotating plate has been described, but the same effect can be obtained not only when using the rotating plate but also when the moving body is a linearly moving moving body. When a plurality of patterns 4 are provided,
A multi-track multi-channel signal can be generated.

[0019]

Since the optical fiber encoder according to the present invention is constructed as described above, the following effects can be obtained. That is, since the patterns are formed of layers having different reflectances depending on wavelengths, a single optical fiber can be used to transmit a plurality of A-phase, B-phase, and M-phase signals. Miniaturization can be achieved. Further, since all of these signals are determined on the moving body, it is not necessary to adjust the phase after assembling, and the number of assembling steps can be greatly reduced.

[Brief description of drawings]

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

FIG. 2 is an enlarged configuration diagram showing a main part of FIG.

FIG. 3 is a characteristic diagram of each signal.

FIG. 4 is a waveform diagram of each signal.

FIG. 5 is a configuration diagram showing a conventional optical fiber encoder.

[Explanation of symbols] 4 patterns 14 optical fiber 29 moving body (rotating plate) 50 A phase signal 51 B phase signal 52 M phase signal

Claims (2)

[Claims] 1. A pattern (4) formed on a moving body (29).
The incident light from the optical fiber (14) is incident on the optical fiber encoder configured to read the pattern (4) based on the emitted light from the pattern (4), the pattern (4), The pattern (4) is composed of a multilayered reflective film which is polymerized with wavelength dependence of reflectance different from each other.
Is an A-phase signal (50) and a B-phase signal (51) whose phases are different from each other.
And an optical fiber encoder having a three-layer structure for generating an M-phase signal (52) having a phase different from that of the A-phase signal (50). 2. The optical fiber encoder according to claim 1, wherein the optical fiber (24) is composed of only one track, and the pattern (4) is composed of only one track.