JPS6211297B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting information via an optical transmission body arranged in a band where information is to be detected, such as detecting fluid leakage in a long transport line or detecting a leak in an optical transmission line. This allows it to be applied to light leakage detection.

Conventionally, in oil transmission pipelines, electrical cables whose dielectric constant changes due to oil are installed along the pipelines, and this is used as an oil leak detection wire, and the change in impedance that occurs in the electrical cable due to oil leaks is detected by the cable. There are those that detect oil leaks by monitoring at the end, and those that have a spring structure that uses the weight of the oil leak collected at the oil leak part to press down on a spring rod and close the electrical contact for indicating oil leaks. Some oil leaks are detected by placing a detector at each detection point along the length of the pipeline, but in the former case, it is difficult to increase the amount of change in cable impedance so that it can be identified. Therefore, this must be converted into pulses for detection, and even if the detection signal is converted into pulses in this way, the pulses will not travel far enough due to loss due to the electric cable and external noise added to it. Therefore, by providing such means in a long oil pipeline, it has not been possible to satisfactorily detect oil leaks.

In addition, in the latter case, expensive detectors must be installed at each of the many detection points set in the long pipeline, which requires a large number of parts and a lot of work to install them. In some respects, this caused diseconomies in terms of facilities.

The above describes the case where the object to be detected is a liquid such as oil, but even when detecting a gas leak using the former detection method described above, the same problems arise as when detecting a liquid. When detecting light leakage in an optical transmission line using this method, in addition to the above-mentioned problems, there is an uneconomical need to incorporate photoelectric converters at multiple locations (each light leakage detection section) on the electric cable, and in addition, the latter method described above Since the detection method detects the weight of leaked materials, it was not possible to apply it to the detection of gas or light leaks.

In view of the above-mentioned problems, the present invention is designed to optically detect the presence or absence of various fluids, the presence or absence of light, etc. within a specific area with high precision and sensitivity. When detecting light leakage in a transmission body, the leakage state and leakage location can be detected using these leakage materials as information media.The detection method will be explained below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a transport path as a fluid transport path or an optical transmission path, and the transport path 1
If this is a fluid flow path, it is constituted by a tube or the like, and if it is an optical transmission path, it is constituted by an optical fiber cable.

The feeding path 1 has one end serving as a starting end 2 for a fluid transport path or optical transmission, and the other end serving as a terminal end 3, but depending on the case, both ends 2, 3 , one or both of them may be a relay end, and this feed route 1
is installed, erected, or buried in the required location,
The total length in the longitudinal direction becomes the band in which leakage is to be detected, that is, the information detection band L, and the detection band L consists of a large number of detection sections l ₁ , l ₂ , l ₃ ...l _o-2 , l _o-1 , l It is classified into _o .

In the first embodiment of the present invention shown in FIG. Information detection is performed.

Both optical transmission bodies 4A and 4B are made of optical fibers or optical fiber cables, and in this embodiment, the light propagation speed of one 4A is faster than the light propagation speed of the other 4B, and as shown in the figure. When one optical transmission body 4 is arranged in parallel with
A light transmitting unit 5 equipped with a light transmitter etc. that transmits light pulses is provided at one end of A, and both optical transmitters 4A, 4
At the other end of B, light receiving sections 6A and 6B each having a photo-electrical converter that converts light into electricity, a waveform analyzer, etc. are provided.

Furthermore, both optical transmitters 4A and 4B have respective detection sections.
A plurality of detection units 7 ₁ , 7 ₂ , corresponding to l ₁ to l _o
7 ₃ ... 7 _o-2 , 7 _o-1 , 7 _o are provided, and each of these detection units 7 ₁ to 7 _o is an information intrusion space into which the leakage material (information medium) from the feed path 1 can enter. The optical transmission bodies 4A and 4B are locally arranged in close parallel to each other via the information intrusion space 8, and each detection unit ₇₁
The optical coupling between the optical transmission bodies 4A and 4B at ~7 _o is now possible.

In the case where the present invention consists of the above-described embodiment, the optical pulse transmitted from the light transmitting section 5 toward the light receiving section 6A is passed through the optical transmission body 4A, and is transmitted to the light receiving sections 6A, 6B.
Information detection is carried out using the leakage from the feed path 1 as an information medium while monitoring from the side.

In this information detection, a state in which there is no leakage accident in the feed path 1 is considered normal, and in the same state, each detection unit 7
₁ to 7 _o The information medium (leakage) from the transmission path 1 will not enter, so the optical pulses emitted from the light transmitting section 5 will only reach the light receiving section 6A and will not reach the light receiving section 6B. , This state determines the above normal state.

Furthermore, in this information detection, if a leakage accident occurs in any of the detection sections l ₁ , _{l 2 . .} . The leaked matter enters the extension space 8 as an information medium, and the optical pulse of the optical transmission body 4A is branched to the optical transmission body 4B by optical coupling via the medium, so that the transmission The light pulse from the light section 5 reaches not only one light receiving section 6A but also the other light receiving section 6B.

Therefore, it was found that a leakage accident had occurred in the transmission path 1 because the optical pulse, which normally reaches only the light receiving section 6A, also reached the light receiving section 6B. In these relative comparisons, the light propagation speed of one 4A is faster than the light propagation speed of the other 4B, so the light pulse to the light receiving part 6A side arrives first, and the light pulse to the light receiving part 6B side arrives later. In the case where the optical pulse passes through the optical transmission body 4B side, the detection unit 7 ₁
The longest distance is from to the light receiving part 6B, and the shortest distance is from the detecting part _7o to the light receiving part 6B, so when the light pulse reaches the light receiving part _6B from each of the detecting parts ₇₁ to ₇₂ ... There is also a difference in the time required for each pulse to arrive at the light receiving section 6A, so the time interval between the light pulse (first arriving pulse) to the light receiving section 6A and the light pulse (later arriving pulse) reaching the light receiving section 6B is determined by By performing calculations and analysis on the 6B side, it becomes clear in which detection section the information medium enters and from which detection section the optical pulse is branched and reaches the light receiving section 6B.

For example, information media (leakage) in the detection zone l ₁ above.
enters and the optical pulse is branched at the detection section ₇₁ , the time interval between the first arriving pulse and the second arriving pulse becomes maximum, the information medium enters the detection section _LO , and the optical pulse is branched at the detection section _7o . In such a case, the above-mentioned time interval is the minimum, so it becomes clear where the leakage accident occurred.

Furthermore, if a simultaneous leakage accident occurs in arbitrary multiple detection sections (for example, l ₁ and l ₃ ), light branches will occur at two locations, detection parts 7 ₁ and 7 ₃ , and the aforementioned first-arrival pulse will be sent to the light receiving part 6A. In addition, two later arriving pulses arrive at the light receiving section 6B.

In this case, since the two later arriving pulses have a difference in the distance between 7 ₁ - 6B and the distance between 7 ₃ - 6B, the latter arriving pulse branched at the detection unit 7 ₃ is branched at the detection unit 7 ₁ . Therefore, the first-arriving pulse and the preceding second-arriving pulse, as well as the first-arriving pulse and the succeeding second-arriving pulse, are determined based on their relative relationships. By analyzing on the light receiving sections 6A and 6B, it becomes possible to detect the occurrence of simultaneous leakage accidents as described above and their positions.

In addition, in the above-mentioned simultaneous information (leakage) detection, the later arriving pulse of the transition that is optically branched by the detection unit ₇₁ is redirected from the optical transmission body 4B to the optical transmission body 4A by the intermediate detection unit ₇₃ that has an optical branching effect. However, each of the detection units 7 ₁ to 7 _o is designed to prevent such secondary light branching, or to sufficiently reduce the amount of branching even if secondary light branching occurs. If configured, the above-mentioned pulse can be received to the light receiving section 6B side without any problem.

Furthermore, if the transport path 1 in the above is a transport path for oil or gas, liquids or gases (some of which have poor light propagation characteristics) are leaked from the transport path.
serves as an information medium, and light is branched at each of the detection units 7 ₁ to 7 _o .

Moreover, when the above-mentioned transmission line 1 is an optical transmission line,
The leaked light from this came to be used as an information medium,
In this case, the light pulses on the optical transmitter 4A side are modulated by the leaked light that enters each of the detection units ₇₁ to _7o , and the leaked light passes through the optical transmitter 4B side, so these states can be detected by light reception. When the parts 6A and 6B perform the analysis, it becomes possible to detect the desired information.

Next, a second embodiment of the present invention will be explained with reference to FIG. 2. In this embodiment, both optical transmission bodies 4A, 4B
The light propagation velocity characteristics are the same, and the lengths of these optical transmission bodies 4A and 4B in the information detection band L are made different from each other.

In this case, the short optical transmission body 4A is linear,
The elongated optical transmission body 4B is spirally shaped, and the optical transmission body 4A is arranged inside or outside the spiral winding part of the optical transmission body 4B, so that both 4A and 4B are arranged side by side in the longitudinal direction, and By arranging the optical transmission body 4B locally close to and parallel to the optical transmission body 4A, the detection section 7 with the information extension space 8 is detected as described above.
₁ , 7 ₂ . . . 7 _o , and other aspects are the same as in the first embodiment.

In this second embodiment, the light pulse transmitted from the light transmitting section 5 toward the light receiving section 6A is passed through the optical transmission body 4A,
Information is detected while monitoring this on the light receiving parts 6A and 6B side. If the optical pulse reaches only the light receiving part 6A, there is no information, and if the information medium enters one of the detection parts and is removed from the optical transmission body 4A. The optical pulse is branched to the optical transmitter 4B, and if the optical pulse also reaches the light receiving section 6B, information is present.

In this case, both optical transmitters 4A and 4B have the same light propagation speed, but their lengths are 4
Since A<4B, the light pulse on the light receiving section 6A side arrives first, and the light pulse on the light receiving section 6B side arrives later. Therefore, by calculating and analyzing the time interval between the first-arriving pulse and the second-arriving pulse, the information position can be confirmed as in the first embodiment.

Next, a third embodiment of the present invention will be explained with reference to FIG.
A, 4B is used, and the optical transmitters 4A, 4B are placed close to each other in parallel over the entire length of the information detection band L, thereby providing a continuous detection section ₇₀ . is the same as

In the case of the third embodiment, information can be detected in the same manner as in the first embodiment, but in this case, since the detection parts ₇₀ are continuous, it is possible to information media can be received at any location.

In addition, in each of the above embodiments, when detecting leaked information using the leakage material in the transmission path 1 as an information medium, an outer cylinder to cover the transmission path 1 and the optical transmission bodies 4A and 4B may be provided in the detection band L. well, each detection interval
In the case of arranging l ₁ to _{l o} , each detection section l ₁ to _{l o}
A separate partition wall may be provided within the outer cylinder.

Further, when using the method of the present invention, by using a plurality of pairs of optical transmission bodies 4A and 4B and distributing them over a wide area, wide area information detection can be performed. Whether a liquid, gas, light, etc. has entered a specific area as an obstacle, or whether a liquid, gas, light, etc. has emitted from a certain point.
Information such as whether an information medium such as light has passed through a predetermined point can also be detected.

Since the information detection method using the optical transmission body of the present invention is as described above, the following characteristic effects can be obtained.

In other words, since it detects the desired information by passing light through an optical transmission body, there is almost no external influence such as noise compared to electrical detection methods, and it uses only a single light transmitter and two light beams. In a detection system that has a transmitter and two light receivers, the presence of information is determined by whether a light pulse reaches the two light receivers, and the presence of information is determined by the difference in the light propagation state between the two light transmitters. Since the information position can also be confirmed, there is no need to place a special detection element in the information detection band, and it is sufficient to branch the light from one optical transmission medium to the other optical transmission medium via the information medium, which can prevent malfunctions. There is no room for this, and overall the desired information detection can be carried out accurately and economically.

[Brief explanation of the drawing]

1 to 3 are schematic illustrations showing various embodiments of the system of the present invention. 4A, 4B... Optical transmission body, 5... Light transmitting section, 6
A, 6B... Light receiving section, 7 ₀ , 7 ₁ , 7 ₂ to 7 _o ...
...Detection unit, L...Information detection band, l ₁ - l _o ...Detection section.

Claims (1)

[Claims] 1. Two optical transmission bodies having different optical pulse arrival speeds or times from one end to the other end are arranged in parallel in the longitudinal direction, and an information medium is provided in the longitudinal direction of both optical transmission bodies. A detection section for optically coupling the two optical transmission bodies to each other is provided in an intermittent or continuous manner, and a light transmitting section is provided at one end of one of the optical transmission bodies, and a light receiving section is provided at the other end of both optical transmission bodies. When both optical transmission bodies are arranged in the band where information should be detected, and optical pulses are transmitted from the light transmitting part of one of the optical transmission bodies towards the light receiving part of the body, random numbers are scattered intermittently. Optical coupling is caused by the information medium that has entered any part of the detection section or continuous detection section, and the optical pulse is branched and transmitted to the other optical transmission body, and reaches each light receiving section of both optical transmission bodies. An information detection method using an optical transmission body, characterized in that the presence of an information medium in the detection area or detection location is detected by analyzing the optical pulses on the side of the light receiving unit. 2. Claim 1, in which two optical transmission bodies having different light propagation velocity characteristics are used, and the arrival speed of the optical pulse from one end of each optical transmission body to the other end is made different from each other.
An information detection method using an optical transmission body as described in . 3 Information provided by an optical transmission body according to claim 1, which uses two optical transmission bodies of different lengths and makes the arrival time of a light pulse from one end of each optical transmission body to the other end different from each other. Detection method.