JP2002267549A - Optical fiber collision detecting sensor and forming method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a collision detecting sensor capable of always dispensing with power supply and easily remote-monitoring at a long distance. SOLUTION: A plurality of poles 2 are erected on the ground 6 in a monitoring area, and an optical fiber passing pipe 1 is continuously turned and constructed on the poles. A flexible pipe part 11 is provided in at least one portion of the optical fiber passing pipe between the poles. An optical fiber or an optical unit 3 is stored in the optical fiber passing pipe 1 to constitute an optical fiber collision sensor. The optical fiber turned and penetrated through the optical fiber passing pipe is connected to an optical fiber in another optical cable 5 for transmitting a signal, and monitored by an OTDR at the other end of the optical fiber. When the optical fiber passing pipe 1 suffers a collision, the flexible pipe part 11, the optical fiber init, or the optical unit 3 is increased in curvature to be produced as a difference in lever on the OTDR monitoring screen. Thus, the position of the collision can be specified, and the degree of the collision can be estimated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sensor for detecting a collision. The purpose of the collision detection sensor is to install this sensor on a railway, road, mountain slope close to a residential area where a significant risk is expected when a rock falls, for example, a rock falling event or a precursor to the occurrence of rock falling And immediately link them to appropriate disaster prevention measures. As will be described later, the present invention has many uses as a sensor for detecting a collision or impact. Hereinafter, a case where the present invention is used for detecting a falling rock will be mainly described as a prominent example.

[0002]

2. Description of the Related Art A typical example of a conventional collision detection sensor is to stretch an electric wire having a metal conductor coated with an insulation coating in an area where a rock may fall, and to cause insulation of the insulated wire or breakage of a conductor portion caused by the falling rock hitting the electric wire. Is electrically detected and an alarm is issued. Since power supply is required and the power is greatly attenuated, it is difficult to perform long-term remote monitoring at all times. For example, what is called the electric wire type used in railways has a diameter of 1 to
A 3mm vinyl insulated wire is used, which is held almost horizontally by columns at 5 to 10m intervals, and when the required section length is extended, the upper and lower wire intervals are set to 20 to 30cm and folded back in parallel. . If the insulation or the conductor is damaged by a falling rock, the detection line is electrically detected and an alarm is issued.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a collision detection sensor using an optical fiber, which does not require power supply at all times and which can easily perform remote monitoring over a long distance.

[0004]

SUMMARY OF THE INVENTION According to the present invention, there is provided an optical fiber conduit comprising a normal tube and at least one flexible tube between posts. An impact detection sensor having an optical fiber or an optical unit inserted therein, wherein the flexible fiber portion and the optical fiber or the optical unit in the flexible tube portion have a large curvature when an impact object hits the optical fiber conduit. The optical fiber collision detection sensor is characterized in that, by bending, the size and position of the bending can be detected by OTDR.
Here, the optical fiber means a single optical fiber having a protective coating, and the optical unit means an optical fiber unit obtained by collecting a plurality of single optical fibers and appropriately protecting the outer periphery thereof. .

[0005] The optical fiber conduit is held substantially horizontally by supporting columns at appropriate intervals, and after the necessary section has been extended, the optical fiber in the optical fiber conduit or the optical fiber in the optical unit is replaced with another signal. It is connected to the optical fiber in the transmission optical cable and is monitored by the OTDR at the other end of the optical cable. It is preferable to use an optical fiber conduit tube that is folded in parallel with an appropriate vertical spacing. When the optical fiber conduit of the collision detection sensor receives, for example, rockfall, the curvature of the flexible tube portion and the optical fiber or optical unit inside the flexible tube portion becomes large, appears as a step on the OTDR monitor screen, and the position of the rockfall can be specified. , And the degree of rock fall is estimated. Since the optical fiber in the signal transmission optical cable has low loss, the incident pulse light used in the OTDR and the reflected pulse light which is a monitoring signal can be accurately transmitted to a considerably remote place.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings. FIG. 1A is a schematic diagram showing the entire configuration of an embodiment of the present invention, in which an optical fiber conduit tube 1 is supported substantially horizontally by a support column 2 standing vertically at a certain distance from the ground 6. I have. 21 is the upper part of the column 2 (top side), 2
Reference numeral 2 denotes a lower portion (ground side) of the column 2. At the post striking the end of the area, the fiber optic conduit turns 180 degrees and is again substantially horizontally supported by the post. In the example shown in FIG. 1A, substantially horizontal optical fiber conduits are erected up and down at certain intervals in four stages, but they can be folded back to the required number of stages.

FIG. 1B shows a cross section of the optical fiber conduit tube 1. That is, an optical fiber or an optical unit 3 accommodating a plurality of optical fibers is housed inside the optical fiber conduit 1.
However, it is inserted in a loose state. The material of the optical fiber conduit is preferably a plastic such as polyethylene, and preferably has a smooth inner surface and a small coefficient of friction with the optical fiber and the optical unit. As a material forming the outer periphery of the optical fiber or the optical unit, an ultraviolet curable resin is generally used. The inner diameter of the optical fiber conduit depends on the outer diameter of the optical fiber and the optical unit to be housed, but is suitably about 2 mm to 8 mm. An appropriate thickness of the optical fiber conduit is about 0.5 mm to 1.0 mm.

The optical fiber or the optical unit 3 is entirely run through the optical fiber conduit 1 as described above. At one end of the optical fiber conduit 1, an internal optical fiber is connected to another signal transmission optical cable 5. Connected with the optical fiber in the
The outside of the connection part is covered with a protective cover 4.

In FIG. 1, reference numeral 11 denotes a flexible tube portion of the optical fiber conduit tube 1. The flexible tube portion is a portion that is more easily bent than the ordinary tube portion 10 that is not the flexible tube portion of the optical fiber conduit tube. The normal pipe portion 10 is a portion that has not been specially processed to make it easy to bend. In the example of FIG.
Is provided between the portion of the support 2 and the middle of the support, but the sensor function of the present invention is provided if there is at least one flexible tube between the supports.

Next, the operation of the present invention will be described with reference to FIG. FIG. 2 shows a state in which FIG.
Shows a state in which it falls from above in the figure as indicated by an arrow and hits the collision detection sensor of the present invention and stops. When the stone 8 is smaller than the interval between the columns 2, the flexible tube portion 11 at the point A in the middle of the column 2 and the points B and C in the column 2 is strongly bent, and the light leaks through the optical fiber there. And the reflection becomes large, so that it is observed as a step on the OTDR monitor screen.

OTDR stands for Optical Time
This is an abbreviation for Domain Reflect-meter, and is generally used to observe the state of an optical fiber in a longitudinal direction. When an optical pulse is incident from one end of the optical fiber using OTDR, a weak reflected optical pulse returns to the incident side from a place where the optical fiber is distorted by an external force. The magnitude of the obstacle can be read from the magnitude of the reflected light (the above-described step).

The overall configuration of the optical fiber collision detection sensor according to the present invention shown in FIG. 1 is a mesh formed by weaving an optical fiber conduit tube 1 and a support 2, and the size of this mesh depends on the expected size of the impact object. It must be determined in consideration. In the case of rock fall detection, if the stone is too small, it passes through the mesh, and if the stone is too large, it straddles two or more columns 2 and does not bend locally as shown in FIG. Therefore, the size of the mesh is a design item in consideration of the size of the falling rock to be detected depending on the terrain of the observation area. If a falling stone of pebble size is considered as a sign of a major disaster, the mesh size must be reduced so that the pebbles of that size do not pass through. If the size of the falling rock is excessively large, the column 2 may be broken by jumping over the state shown in FIG. 2 and the optical fiber conduit tube 1 may be torn, but in this case, the internal optical fiber or optical unit is also broken. , OTDR captures a large reflected pulse light, which can be clearly detected as a remarkable phenomenon.

Next, the structure of the flexible tube portion of the optical fiber conduit will be described. FIG. 3 is the simplest example, in which a circumferential groove is provided in the normal tube portion 10 of the optical fiber conduit tube itself in a multi-layered manner and the portion is processed into a flexible portion 11. . This is similar to the configuration of a bending straw used for beverages. Ideally, the number of grooves is provided until the length of the flexible tube portion 11 becomes about three to ten times the diameter of the normal tube portion 10. In addition, each of the grooves may have an independent ring shape or a continuous spiral groove.

FIG. 4 shows another example of the structure of the flexible tube. 7
If there is no flexible part 71, pipe insertion flanges 72 at both ends
Although it is a normal pipe joint with, since it has the flexible part 71 in the middle part, it can be said that it is a pipe joint having a flexible part. When the ordinary pipe sections 10 are connected to each other by the pipe joint 7 having the flexible section as shown in the drawing, the same operation as when the flexible pipe section 11 is provided in a part of a series of optical fiber communication pipes. That is, the pipe joint 7 having the flexible portion becomes the flexible tube portion 11. The method for forming the flexible portion in FIG. 4 is the same as that described in the previous section. The material and dimensions of the pipe joint 7 are in accordance with the contents (item 0007) described above for the optical fiber conduit tube. However, the inner diameter of the flange 72 is usually substantially equal to the outer diameter of the tube portion 10.

One method of passing an optical fiber or an optical unit through an optical fiber conduit is to integrally fabricate it in a pre-wired shape, that is, as shown in FIG. There is a method of manufacturing the optical fiber or the optical unit 3 at a factory so that the optical fiber or the optical unit 3 is accommodated in the hollow pipe 1 in a loose state. Another method is
First, there is a method in which an optical fiber conduit is installed, and thereafter, the optical fiber or the optical unit 3 is connected to the optical fiber conduit.

An air blown method can be applied to the latter method. In the airbron method, a one-way airflow is created in a pipe, and an optical fiber or an optical unit is passed through the pipe by using the airflow. In order for this method to be applicable, the radius of curvature of the folded portion of the optical fiber conduit of FIG. 1 needs to be 150 mm or more. By doing so, the passage of the optical fiber or the folded portion of the optical unit can be smoothly performed. It goes without saying that the air blow method may be applied not only to the installation but also to the recovery in the event of a failure of the internal optical fiber or optical unit, and to the installation of the optical fiber or optical unit again.

[0017] Even if an optical fiber or an optical unit is preliminarily housed in an optical fiber conduit at a factory, and the optical fiber or optical unit is erected and used for actual use, the recovery of the internal optical fiber or the optical unit in the event of failure can be performed. When the optical fiber or the optical unit is laid again, the air blown method may be applied. Therefore, it is desirable that the radius of curvature of the bent portion of the optical fiber conduit be 150 mm or more in this case also during the installation.

[0018]

As described above, the present invention is not a conventional collision detection sensor of the type in which an electric wire is stretched using a metal conductor, but a collision detection sensor of the type in which an optical fiber is extended. There is no necessity, and it has an excellent merit that continuous monitoring can be performed from a long distance at all times, which has great significance in disaster prevention. In addition, the optical fiber operates in a state protected by a full-length optical fiber conduit, so there is little risk of damage.Even if it is damaged, it is immediately detected, and it is easily recovered by the air blow method, etc. A high monitoring system can be constructed.

Since the collision detection sensor of the present invention is suitable for remote monitoring at all times, it is used not only as a rockfall detection sensor but also installed alongside a livestock breeding fence on a ranch or the like to prevent livestock collision or damage to the fence. Can also be used for the purpose of detecting It can also be used in conjunction with a guardrail on a mountain road to detect car collisions or damage to the guardrail. Further, if the collision detection sensor of the present invention is installed around the building, it can be used for crime prevention.

[Brief description of the drawings]

FIG. 1A is a front view showing a configuration of an embodiment of an optical fiber collision detection sensor of the present invention. (B) is a cross-sectional view showing a relationship between an optical fiber conduit as an element of the present invention and an optical fiber or an optical unit.

FIG. 2 is a plan view showing the operation of the optical fiber collision detection sensor according to the present invention.

FIG. 3 is a perspective view showing one embodiment of a flexible tube portion of an optical fiber conduit as a component of the present invention.

FIG. 4 is a perspective view showing another embodiment of a flexible tube portion of an optical fiber conduit as a component of the present invention.

[Explanation of symbols]

 1: Optical fiber conduit 10: Normal tube of optical fiber conduit 11: Flexible tube of optical fiber conduit 12: Folded part of optical fiber conduit 2: Column 21: Upper column 22: Column Lower part 3: Optical fiber or optical unit 4: Connection part cover 5: Signal transmission cable 6: Ground 7: Pipe joint having flexible part 71: Flexible part 72: Pipe insertion flange 8: Stone

Claims (5)

[Claims] An optical fiber conduit comprising a normal tube and at least one flexible tube is laid substantially horizontally between pillars which are substantially vertically erected, and an optical fiber conduit is provided in the optical fiber conduit. A collision detection sensor into which a fiber or an optical unit is inserted, wherein the flexible tube portion and the optical fiber or the optical unit in the flexible tube portion are bent at a large curvature when an impact object hits the optical fiber passage tube. Thus, the optical fiber collision detection sensor can detect the size and position of the bend by OTDR. 2. The optical fiber collision detection sensor according to claim 1, wherein the flexible tube portion is formed by directly corrugating the thickness of the normal tube portion. 3. The optical fiber rockfall sensor according to claim 1, wherein the flexible tube portion is formed by directly corrugating a thickness of an intermediate portion of a pipe joint connecting the normal tube portion. . 4. The optical fiber conduit is held substantially horizontally by supporting columns at appropriate intervals, and when the required section length is completed, the upper and lower optical fiber conduits are appropriately folded and turned back in parallel. The optical fiber rockfall sensor according to claim 1. 5. The optical fiber collision according to claim 1, wherein the optical fiber or the optical unit is inserted into the optical fiber conduit by an air blow method after the optical fiber conduit is laid. A method for forming a detection sensor.