JPH0769247B2 - Optical fiber core contrast device - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to an optical fiber core wire reference device used for laying an optical fiber line and performing maintenance work thereof.

[Prior art]

Since an optical fiber cable usually includes a large number of optical fiber cores and is long enough to reach several kilometers with one fiber, when connecting them, a large number of optical fiber cores are provided at both ends of the optical fiber cable. It is necessary to compare each one of them and find the same at both ends. Conventionally, as an optical fiber core wire contrast device for this purpose,
A unidirectional one as shown in FIG. 2 was used. That is, a reference optical signal is made incident from one end side of the optical fiber core wire 42, and the core wire through which the reference optical signal propagates is found at the other end side. As the optical transmitter 41, one that generates an optical signal modulated with a low frequency signal of a specific frequency (usually 270 Hz is often used) is used, and this modulated optical signal is incident on one end of the optical fiber core wire 42. A bending addition device 43 is arranged on the other end side of the optical fiber core wire 42, whereby the optical fiber core wire 42 is bent to a predetermined radius of curvature,
Leaked light is generated. That is, the optical signal propagating to the optical fiber core wire 42 is leaked. The leaked light is received by the photoelectric conversion element 44 and converted into an electric signal. This electric signal is amplified by the narrow band AC amplifier circuit 45. The frequency characteristic of the AC amplification circuit 45 is a bandpass filter characteristic of a narrow width so as to amplify only the above-mentioned modulation frequency component, whereby only the above-mentioned modulation frequency component is taken out, and this is AC / DC conversion. The circuit 46 converts the DC signal. This DC signal is sent to the DC level detection circuit 47, and it is detected that the DC level has exceeded a certain value. This confirms the contrast of the optical fiber core. The reason why the modulated light is used here is that the power of the received optical signal is extremely small, so that the S / N ratio cannot be sufficiently obtained in the unmodulated light, which causes a decrease in the dynamic range and a decrease in reliability. by. As the modulation frequency, it is widely used as the modulation frequency of the light source in optical measuring instruments.
0 Hz is usually used.

[Problems to be Solved by the Invention]

However, since the conventional optical fiber core wire identification device propagates an optical signal in one direction to perform core wire identification, as described above, when performing work in an environment with a poor S / N ratio, There is a problem that there is no certainty in detecting whether or not the optical fiber core on the transmitter side and the optical fiber core on the receiving side are the same. Moreover, since the comparison is judged only on the receiving side, reliability is not sufficient. Furthermore, if a malfunction occurs, it may be judged that the core wire is judged to be able to be compared even though the core wire is not contrasted, and the problem is very serious. That is, if it is determined that they are compared, the core wire is often cut due to a connection or the like, so that the core wire is unnecessarily cut and cannot be recovered. An object of the present invention is to provide an optical fiber core wire checking device which can remarkably improve the reliability of the optical fiber core wire check and can sufficiently ensure a reliable and error-free core wire check.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, in the optical fiber core wire identification device according to the present invention, a first light generation is provided which is placed at one end side of the optical fiber core wire and which generates a first optical signal modulated at a predetermined frequency. A first device having means, and a second device placed on the other end side and having second light generating means for generating a second optical signal modulated at a predetermined frequency. The apparatus of claim 1 further comprises a first light generating means from the first light generating means.
Means for injecting the optical signal into the optical fiber at one end side of the optical fiber and taking out the optical signal propagated from the other end side to the one end side, and a first means for receiving the extracted optical signal. Photoelectric conversion means, first frequency selection means for selecting only the modulation frequency component of the second optical signal from the output of the first photoelectric conversion means, and the level of the selected modulation frequency component is determined, The second device further has a first level detecting means for producing an output when the value is equal to or more than a predetermined value, and the second device further applies a bend to the optical fiber core wire, and the light propagating through the core wire from the bent part. Signal leakage and second
Bending addition means for making the optical signal from the light generating means enter the core wire through the bent portion, second photoelectric conversion means for making the optical signal leaked from the bent portion incident, and the second photoelectric conversion means. Second frequency selection means for selecting only the modulation frequency component of the first optical signal from the output of the conversion means, and a level of the selected modulation frequency component is determined, and an output is produced when the level is a predetermined value or more. It is characterized by having a second level detecting means and a control means for automatically generating a second optical signal from the second light generating means in accordance with the output of the second level detecting means. .

[Action]

A first optical signal modulated at a predetermined frequency is made incident from one end of the optical fiber core wire and propagated through the optical fiber core wire to the other end side. On the other end side, a bend is added to the optical fiber core, and light is leaked from the bent portion. This leaked light is photoelectrically converted, and only the modulation frequency component of the first optical signal in its output is selected. The level of the selected modulation frequency component is determined by the second level detecting means, and when the level is equal to or higher than a predetermined value, the second level detecting means produces an output. Then, the control means is the second
The second light generating means is controlled so that the second light generating means automatically generates a second optical signal modulated at a predetermined frequency in accordance with the output from the level detecting means. This second optical signal enters the optical fiber core wire through the bent portion and propagates to the one end side. At the one end side, the second optical signal propagated by the optical fiber is taken out, and only the modulation frequency component of the second optical signal is selected. The level of the selected modulation frequency component is determined by the level detecting means, and when the level is equal to or higher than a predetermined value, the level detecting means produces an output. Therefore, first, the first optical signal traveling in one direction of the optical fiber is used as the signal for checking the optical fiber, and the first optical signal is detected at the other end side. When the first optical signal is detected at the other end side, the second optical signal is automatically made incident on the other end side as a signal for core wire comparison, and the second optical signal is directed in the opposite direction. Is directed to
This second optical signal is detected at one end. Therefore, as the signals for the core wire comparison,
The second optical signal is used, and when the first optical signal is sent from one end side to the other end side, the second optical signal is automatically returned from the other end side to the one end side, so that the bidirectional The core line will be checked in. Moreover, the second optical signal is conditioned on the condition that the first optical signal is detected on the other end side, and when this condition is satisfied, the second optical signal is automatically made incident on the core wire. The coincidence of the cores will be confirmed only when the cores are contrasted at both ends. Therefore, extremely high reliability of the core wire control is obtained, and there is no possibility of malfunction.

【Example】

Next, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, an optical transmitter 11, optical fibers 12, 14, a multiplexer / demultiplexer 13, a photoelectric conversion element 15, an AC amplification circuit 16, an AC / DC conversion circuit 17, and a DC level are provided on one end side of an optical fiber core wire 20. A first device is arranged which comprises a detection circuit 18 and a microprocessor 19. A second device is provided on the other end side of the optical fiber core wire 20 (the other end side is used to mean one end side, and is not necessarily the other end itself and may be near the center). Are placed. The second device is a bending addition device 21, a photoelectric conversion element 22, AC amplification circuits 23 and 24, AC / DC conversion circuits 25 and 26, DC level detection circuits 27 and 28, and a microprocessor 29, It is composed of a drive circuit 30 and a light emitting element 31. The AC amplification circuits 23 and 24 are amplification circuits each having a narrow bandpass filter characteristic, but their frequency bands are different. The optical transmitter 11 generates an optical signal modulated at a predetermined frequency, and this optical signal is guided to a multiplexer / demultiplexer (for example, an optical fiber type multiplexer / demultiplexer) 13 via an optical fiber 12 and the optical signal is transmitted. It is incident on one end of the fiber core wire 20. Another optical fiber 14 is connected to the multiplexer / demultiplexer 13 so that light emitted from one end of the optical fiber core wire 20 is guided to the photoelectric conversion element 15. The optical signal thus entered from one end of the optical fiber core wire 20 propagates through the core wire 20 and travels to the other side. On the other side, a bending addition device 21 is attached, and by bending the optical fiber core wire 20 with a predetermined radius of curvature, the optical signal propagating in the core wire 20 is leaked. In this way, the optical signal propagating in the core wire 20 is taken out without cutting. This leaked light is converted into an electric signal by the photoelectric conversion element 22. This electric signal is amplified by a narrow band AC amplifier circuit 23 that amplifies only the modulation frequency component of the above-mentioned modulated light with high gain. Therefore, when this optical fiber 20 contains the above-mentioned component of the modulated light, only that component is amplified. The output of the AC amplification circuit 23 is converted into a DC signal by the AC / DC conversion circuit 25, and the DC level detection circuit 27 detects that the DC level is higher than a predetermined level. Therefore, the optical fiber core wire 20 equipped with the bending addition device 21
However, if it is the same as the core wire 20 on which the modulated light is incident from the optical transmitter 11 via the multiplexer / demultiplexer 13 at one end side, an output is generated from the DC level detection circuit 27, and the other If it is a core wire, no output is generated from the DC level detection circuit 27. The microprocessor 29 drives the drive circuit 30 according to the presence or absence of the output of the DC level detection circuit 27.
To operate. That is, when an output is generated from the DC level detection circuit 27, the drive circuit 30 operates, and a drive signal of a predetermined frequency (a frequency different from the modulation frequency of the optical signal from the optical transmitter 11) is supplied to the light emitting element 31. And generate an optical signal modulated to that frequency. The light of the light emitting element 31 is the optical fiber core wire bent by the bending addition device 21.
20 is irradiated in the tangential direction. As a result, even if the optical fiber 20 is not cut, the light from the light emitting element 31 is coupled to the optical fiber core wire 20 and enters it. Thus, the light from the light emitting element 31 enters the optical fiber core wire 20 and is propagated to one end side, that is, the multiplexer / demultiplexer 13 side. The light emitted from this one end is guided by the optical fiber 14 and reaches the photoelectric conversion element 15 without interfering with the light from the optical transmitter 11 by the multiplexer / demultiplexer 13. This light is converted into an electric signal by the photoelectric conversion element 15. This electric signal is amplified by a narrow band AC amplifier circuit 16 that amplifies only the modulation frequency component of the modulated light from the light emitting element 31 with high gain. Therefore, when the component of the above-mentioned modulated light is included in the light traveling toward the one end side in the optical fiber 20, only the component is amplified. The output of the AC amplification circuit 16 is converted into a DC signal by the AC / DC conversion circuit 17, and the DC level detection circuit 18 detects that the DC level is higher than a predetermined constant level. The output of the DC level detection circuit 18 is sent to the microprocessor 19, and whether the light received by the photoelectric conversion element 15 is from the light emitting element 31 or not depending on the presence or absence of the output of the DC level detection circuit 18. A decision is made.
When the microprocessor 19 determines that the light is emitted from the light emitting element 31, it sends a control signal to the optical transmitter 11 to stop the optical signal currently being sent and generate an optical signal modulated at another frequency. This modulated light is sent to the optical fiber 12 and the multiplexer / demultiplexer.
It is made incident on the optical fiber core wire 20 via 13 and propagated to the other end side. Therefore, the photoelectric conversion element 22 receives an optical signal whose modulation frequency is different from that before. Then, this time, an output is generated from the AC amplification circuit 24 whose center frequency matches the modulation frequency, and as a result, the other DC level detection circuit passes through the AC / DC amplification circuit 26.
The output comes from 28. Therefore, the microprocessor 29 generates the output from the one DC level detection circuit 27 first, and then outputs the output from the other DC level detection circuit 28, so that the light emitting element corresponds to the first output.
When light is generated from 31 and returned to the one end side, it can be judged that another modulated light is sent to the other end side again in response to the light. In this way, since the optical fiber signals are bidirectionally exchanged between the two devices placed at both ends of the optical fiber core wire 20 to perform core wire comparison, the reliability thereof is extremely high and there is room for malfunction. Can be completely eliminated. It should be noted that in the above, three different optical signals are first used to distinguish the optical signal sent from the optical transmitter 11, the optical signal sent from the light emitting element 31 and the optical signal sent from the optical transmitter 11 at the different frequencies. Although modulated light is used, other configurations can be adopted. For example, an optical signal blinking with a different code may be used, and the code represented by the blinking may be decoded to confirm the signal. Also, optical fiber 20
Instead of using the multiplexer / demultiplexer 13 for inputting an optical signal to one end of the optical path and extracting the output light, a multiplexer / demultiplexer may be used if the isolation is sufficiently large. further,
The wavelength of light to be incident on the photoelectric conversion element 22 and the light emitting element 31
By changing the wavelength of the light from the light source and providing an optical filter on the incident side of the photoelectric conversion element 22, since these lights can be separated, the photoelectric conversion element 22 and the light emitting element 31 are mounted close to each other. You can also do it. In the above embodiment, the optical transmitter 11 first sends a first optical signal in one direction of the optical fiber core wire 20, then the light emitting element 31 sends a second optical signal in the opposite direction, and finally Although the optical transmitter 11 is configured to send the third optical signal again in the same direction as in the beginning, even if the transmission of the third optical signal is omitted, the core line check in both directions is performed, so that sufficient reliability is ensured. Is obtained.

【The invention's effect】

According to the optical fiber optical fiber comparison apparatus of the present invention, an optical signal traveling in both directions of the optical fiber optical fiber is used as a signal for optical fiber optical fiber identification, and the optical fiber for optical fiber optical fiber first traveling from one end side to the other end side is used. When a signal is output, the other optical fiber signal for fiber core control that goes from the other end side to the one end side is automatically sent on condition that it is detected on the other end side, and this is detected on the one end side. Since it is configured as described above, the coincidence of the core wires is not confirmed until the core wire contrasts on both the one end side and the other end side are aligned, and the reliability of the core wire contrast is significantly improved. , The room for malfunction is eradicated.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional example. 11, 41 ... Optical transmitter, 12, 14 ... Optical fiber, 13 ... Multiplexer / demultiplexer, 15, 22, 44 ... Photoelectric conversion element, 16, 23, 24, 45 ... AC amplification circuit, 17, 25, 26, 46 ... AC / DC conversion circuit, 18,
27, 28, 47 ... DC level detection circuit, 19, 29 ... Microprocessor, 20, 42 ... Optical fiber core wire, 21, 43 ... Bending addition device, 30 ... Driving circuit, 31 ... Light emitting element.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Chennouchi 4-83-3 Shibaura, Minato-ku, Tokyo Kandenko Co., Ltd. (72) Inventor Masao Tanaka 1440 Rokuzaki, Sakura-shi, Chiba Fujikura Electric Wire Co., Ltd. Sakura Factory (72) Inventor Yoshiharu Uwa 1440, Rokkozaki, Sakura City, Chiba Prefecture Fujikura Cable Co., Ltd.Sakura Factory (72) Inventor Toshiyuki Hayakawa 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Electric Line Co., Ltd. (56 ) Reference JP-A-60-220842 (JP, A) JP-B 62-34113 (JP, B2) JP-B 56-16475 (JP, B2)

Claims (1)

[Claims] 1. A first device, which is placed on one end side of an optical fiber core and has a first light generating means for generating a first optical signal modulated at a predetermined frequency, and a first device which is placed on the other end side. And a second device having a second light generating means for generating a second optical signal modulated at a predetermined frequency, the first device further comprising: Means for injecting the first optical signal into the optical fiber at one end side of the optical fiber and taking out the optical signal propagated from the other end side to the one end side, and the extracted optical signal enters A first photoelectric conversion means, and a first photoelectric conversion means for selecting only a modulation frequency component of the second optical signal from the output of the first photoelectric conversion means.
And a frequency selection means for determining the level of the selected modulation frequency component, and produces an output when the level is equal to or higher than a predetermined value.
The second device further includes a level detecting means for adding a bend to the optical fiber core wire to leak an optical signal propagating through the core wire from the bent portion and generate the second light. Bending addition means for making an optical signal from the means incident on the core wire through the bent portion, second photoelectric conversion means for making an optical signal leaked from the bent portion incident, and second photoelectric conversion means of the second photoelectric conversion means. A second frequency selecting means for selecting only the modulation frequency component of the first optical signal from the output, and a second level for determining the level of the selected modulation frequency component and producing an output when the value is equal to or more than a predetermined value. An optical fiber core wire control having a detecting means and a control means for automatically generating a second optical signal from the second light generating means in accordance with an output of the second level detecting means. apparatus.