JP3599690B2 - Optical displacement sensor using optical fiber and deformation monitoring system using this optical displacement sensor - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention converts a slope displacement into a change in the curvature of an optical fiber in order to measure the displacement of the slope for the purpose of early detection of a slope collapse accident, etc., and utilizes the change in the transmitted light intensity of the optical fiber due to the change in the curvature to change the slope displacement. The present invention relates to an optical displacement sensor using an optical fiber for measuring an amount and a deformation monitoring system using the optical displacement sensor.
[0002]
[Prior art]
Slope such as railroads and roads are not only collapsing due to heavy rain and earthquake, but also collapsing due to various environmental changes. In order to prevent these damages, it is necessary to measure and monitor the displacement of the slope which may cause landslide or collapse, and to detect abnormalities early. Until now, electric expansion / contraction sensors were mainly used as a method of measuring the displacement of a slope, but failures due to lightning strikes and the like have occurred frequently. However, in recent years, along with the development of optical fiber technology, optical fibers are strongly affected by electromagnetic induction and are not easily affected by lightning strikes, and displacement sensors using optical fibers only supply light and do not require power supply and signal lines. Are developed and put into practical use.
[0003]
Japanese Patent Laid-Open Publication No. 2000-298010 discloses an optical displacement sensor (the use name in the specification is the same hereinafter, "strain sensor") utilizing the fact that the intensity of transmitted light changes in proportion to the radius of curvature of an optical fiber. . This optical displacement sensor converts the displacement of the monitoring slope into a change in the curvature of the optical fiber, and measures the amount of displacement using the fact that the transmitted light intensity of the optical fiber changes in proportion to the change in the curvature.
[0004]
[Problems to be solved by the invention]
However, the optical displacement sensor (the name used in the specification of Japanese Patent Application Laid-Open Publication No. 2000-298010 is the same hereinafter) is a method in which the curvature of the optical fiber is directly changed by the displacement of the slope, and a large tension is always applied to the optical fiber. This reduces the durability of the optical fiber. Further, there is a problem that it is difficult to measure the displacement amount of 100 mm or more and to improve the displacement detection sensitivity. Hereinafter, these technical problems will be described.
[0005]
FIG. 9 shows a structure of an optical displacement sensor 101 using an optical fiber disclosed in JP-A-2000-298010, and FIG. 8 shows a state of installation of the sensor on an inclined surface. In FIG. 9 , the optical fiber 102 is wound around a leaf spring 105. When the optical fiber 102 is pulled as shown by the arrow in the drawing, the diameter of the leaf spring 105 and the optical fiber decreases, and when the optical fiber 102 is loosened, the diameter of the leaf spring 105 is increased by the restoring force of the leaf spring 105. . A light source 102a is irradiated from one end of the optical fiber 102, and a light receiving element 102b provided at the other end converts the transmitted light into light / electricity.
[0006]
In FIG. 8 , a plurality of anchors 153 are driven into the inclined surface 151, and the optical displacement sensor 101 is installed on the upper part. The optical fibers 102 from the optical displacement sensor 101 are sequentially fixed to adjacent anchors, and have a mechanism in which the optical loop diameter of the optical displacement sensor 101 changes due to expansion and contraction of the distance between the anchors. In order to change the loop diameter of the optical displacement sensor according to the displacement between the anchors in this method, it is necessary to apply a tension of about 2 kg to lay the fiber 102 without loosening. However, laying the optical fiber made of quartz glass or the like with constant tension is a factor of reducing the durability and life.
[0007]
FIG. 7 shows the optical fiber diameter on the x-axis and the transmitted light intensity on the y-axis in relation to the optical fiber diameter and the transmitted light intensity. From this figure, it can be seen that the transmitted light intensity is not attenuated when the re-fiber diameter is 35 mmφ or more, and the optical fiber is broken when it is 3 mmφ or less. Therefore, in the optical displacement sensor shown in FIG. 9 as well, the maximum diameter of the leaf spring 105 and the optical fiber 102 is about 35 mmφ to about 3 mmφ, and the displacement measurement range is about 100 mm according to the following equation (1).
(35 mm × π) − (3 mm × π) = 100 mm Equation 1
However, monitoring a slope displacement may require a measurement range of 100 mm or more. In this method, the measurement range can be expanded by winding the optical fiber 102 around the leaf spring 105 a plurality of times, but the structure becomes complicated to uniformly change the diameter of the optical fiber having a plurality of turns. In order to increase the displacement measurement sensitivity, it is necessary to improve the detection characteristics of the optical displacement sensor itself. In the optical displacement sensor of FIG. 9, the amount of expansion and contraction of the optical fiber 102 and the amount of change in the diameter of the optical fiber have a 1: 1 relationship. In order to measure the minute displacement with high sensitivity, a mechanism is required such that the slope expansion and contraction amount and the optical fiber diameter change amount have a relationship of 1: n (n> 1).
[0008]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has been made in order to solve the problems. The object of the present invention is to reduce the slope displacement of the optical fiber by applying as little tension as possible to the optical fiber sensor. An optical displacement sensor that uses an optical fiber that has a mechanism that converts it into a change, improves durability, and allows the displacement measurement range and measurement sensitivity to be easily changed as required, and a deformation monitoring using this optical displacement sensor It is to provide a system.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is an optical displacement sensor for measuring a displacement amount using a change in transmitted light intensity due to a change in curvature of an optical fiber, wherein the optical fiber is disposed in a relaxed state. with two discs in optical fiber several times wound optical undamped circular curved portion and the light attenuating circular curved section having different diameters, without the disc diameter of the optical undamped circular curved portion to the attenuation of the transmitted light 35 mm phi above, a disc diameter of the optical attenuating the circular curved portion is more than 30 mm phi of attenuation of transmitted light, under tension disposed are light and non-light-attenuation-circular curved portion stretchable amount of wiring that expands and contracts in response to displacement of the displacement detecting portion It comprises means having a mechanism for changing the number of turns of the optical fiber in the attenuation circular curve portion and changing the winding ratio of the optical fiber to both disks by the measured displacement .
[0012]
According to a second aspect of the present invention, a plurality of optical displacement sensors using the optical fiber according to the first aspect are arranged at a displacement detection location, and the optical displacement sensors are connected in series with an optical fiber in a relaxed state. One end of the optical fiber is connected to the light emitting circuit, the other end of the optical fiber is connected to the light receiving circuit, an alarm output circuit for issuing an alarm is connected to the light receiving circuit, and the winding of the curved portion of the optical fiber at the displacement detection point. It comprises means for detecting a displacement at a displacement detection point by using the fact that the number or radius of curvature changes due to the displacement to change the transmitted light intensity of the light, and issues an alarm.
[0013]
According to a third aspect of the present invention, a plurality of optical displacement sensors using the optical fiber according to the first aspect are arranged at a displacement detection location, and each of the optical displacement sensors is connected in series with an optical fiber in a relaxed state. One end of the optical fiber is connected to a light emitting circuit, the other end of the optical fiber is connected to a light receiving circuit via a switching optical switch, and the light receiving circuit is connected to an alarm output circuit for issuing an alarm. An OTDR circuit that is connected to the other end of the optical fiber via a switching optical switch that is switched by an alarm signal and that specifies the displacement occurrence position of the displacement detection point is provided, and the number of turns or the radius of curvature of the curved portion of the optical fiber at the displacement detection point Is used to detect the displacement of the displacement detection location using the fact that the transmitted light intensity of the light changes due to the displacement, and to issue an alarm. Displacement generation position of those made of means adapted to detect.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described more specifically based on embodiments of the invention illustrated in the drawings.
[0015]
[Embodiment 1]
Here, FIG. 1 is a schematic configuration diagram of an optical displacement sensor using an optical fiber.
[0016]
In FIG. 1, an optical displacement sensor 1 using an optical fiber is configured such that the number of turns of a light-attenuating circular curve portion 3 having a predetermined diameter, for example, a diameter of 30 mmφ or less, of an optical fiber 2 installed at a position for detecting a displacement, for example, a slope anchor, is determined by the displacement. This is a device that detects displacement using the fact that the transmitted light intensity changes due to increase or decrease.
[0017]
An optical displacement sensor 1 using an optical fiber includes an optical fiber 2 disposed in a relaxed state, a housing 5 having therein a light-attenuating circular curve portion 3 and a light-attenuating circular curve portion 4 having a predetermined diameter of the optical fiber 2, It mainly comprises a wiring 6 and the like which are arranged in a tensioned state by rotating the light non-attenuating circular curve portion 4 in conjunction with the displacement.
[0018]
A light source 2a is connected to one end of the optical fiber 2 disposed in a relaxed state, and a light receiving element 2b receiving light emitted from the light source 2a is connected to the other end of the optical fiber 2. The light receiving element 2b detects a change in the transmitted light intensity of the light emitted from the light source 2a, thereby detecting a change in the number of turns of the light attenuation circular curve portion 3 of the optical fiber 2 at the displacement detection point, and The presence / absence of displacement and the direction of displacement can be detected.
[0019]
The optical attenuation circular curve portion 3 of the optical fiber 2 has a configuration in which the optical fiber 2 is wound several times around the side peripheral surface of a disk 3a having a predetermined diameter, for example, 25 mmφ. The light attenuation circular curve portion 3 has a structure in which the transmitted light intensity changes depending on the number of turns of the optical fiber 2. One of the optical fibers 2 wound several times is fixed at a fixing point 3b on the side peripheral surface of the disk 3a, and is taken out of the housing 5 in a relaxed state. The other end of the optical fiber 2 is stretched and wound several times around the side peripheral surface of the disk 4 a of the light non-attenuating circular curve portion 4.
[0020]
One end of a rotating shaft 3c is connected to the center of rotation of the disk 3a. The other end of the rotating shaft 3c is connected to a spring 3e mounted on a mounting plate 5a in the housing 5 via a ball bearing 3d. The mainspring 3e urges the disk 3a connected to one end of the rotating shaft 3c via a ball bearing 3d so as to rotate in the direction of arrow b. The mainspring 3e is pulled in the direction of arrow d with a tension of about 200 g.
[0021]
The non-attenuating circular curve portion 4 of the optical fiber 2 has a configuration in which the optical fiber 2 is wound several times around the side peripheral surface of a disk 4a having a predetermined diameter, for example, 50 mmφ. The light non-attenuation circular curve portion 4 differs from the light attenuation circular curve portion 3 in that the transmitted light intensity does not change due to the increase or decrease in the number of turns of the optical fiber 2. One of the optical fibers 2 wound several times is fixed at a fixing point 4b on the side peripheral surface of the disk 4a and extends out of the housing 5 in a relaxed state. The other end of the optical fiber 2 is stretched and wound several times around the side peripheral surface of the disk 3 a of the light attenuation circular curve portion 3.
[0022]
One end of a rotating shaft 4c is connected to the center of rotation of the disk 4a. The rotating shaft 4c is mounted parallel to the rotating shaft 3c. The other end of the rotating shaft 4c is connected via a ball bearing 4d to a mainspring spring 4e mounted on a mounting plate 5a in the housing 5. The mainspring 4e urges the disk 4a connected to one end of the rotary shaft 4c via a ball bearing 4d so as to rotate in the direction of arrow a. The mainspring 4e is pulled in the direction of arrow c with a tension of about 2 kg.
[0023]
The housing 5 has a light attenuation circular curve portion 3 and a light non-attenuation circular curve portion 4 of the optical fiber 2 therein, and is installed on a displacement detection point, for example, a head of a slope anchor. A mounting plate 5a is mounted inside the housing 5, and a disk 3a of the light attenuation circular curve portion 3 is similarly mounted on the mounting plate 5a via a rotating shaft 3c, a ball bearing 3d, and a mainspring 3e. A disk 4a of the damping circular curve portion 4 is mounted in parallel via a rotating shaft 4c, a ball bearing 4d, and a mainspring 4e.
[0024]
The wiring 6 is arranged in a tensioned state at the displacement detection point, and when the displacement occurs, it expands and rotates the disk 4a of the light non-attenuating circular curve portion 4, and rotates the disk 4a of the light non-attenuating circular curve portion 4. Through this, the number of turns of the optical fiber 2 wound on the disk 4a and the disk 3a several times in a stretched state on the disk 3a side is increased or decreased. For example, a wire or a high tension wire is used for the wiring 6.
[0025]
The wiring 6 is wound several times with one end fixed on a side peripheral surface of a disk 6a whose center is mounted on a rotating shaft 4c coaxial with the disk 4a, and the other end is a pulley 6b mounted in a housing 5. The direction is changed and taken out of the housing 5 in a tensioned state. The tension is about 2 kg in the opposite direction to the arrow c by the mainspring 4 e of the light non-attenuating circular curve portion 4 of the optical displacement sensor 1 installed on the adjacent slope anchor (not shown). Installed. The number of turns of the optical fiber 2 wound several times around the light attenuation circular curve portion 3 is maintained without change in a state where no displacement occurs.
[0026]
Next, the operation based on the configuration of the embodiment of the present invention will be described below.
When a displacement occurs at a displacement detection point where the housing 5 is installed, for example, when an extension displacement occurs between the anchor on which the housing 5 is installed and an adjacent anchor, the tension balance is disturbed and the wiring 6 moves in the direction of the arrow c, so that the disk 6a, The disk 4a rotates in the direction indicated by the arrow a so that the optical fiber 2 wound around the disk 4a is unwound and wound around the disk 3a.
[0027]
Assuming that the diameter of the disk 4a of the light non-attenuating circular curve portion 4 is 50 mmφ and the diameter of the disk 3a of the light attenuating circular curve portion 3 is 25 mmφ, as shown in FIG. Since the transmitted light is attenuated when the diameter is 25 mmφ, the transmitted light intensity decreases in proportion to the amount of the optical fiber wound on the disk 3a from the disk 4a, and the displacement of the wiring 6 can be known. When the displacement between the anchors is contracted, the optical fiber 2 of the disk 3a is wound around the disk 4a, and the intensity of the transmitted light is increased contrary to the above.
[0028]
In the present invention, the displacement between the slope anchors is converted into a wiring expansion and contraction of a tension of about 2 kg. Therefore, the tension applied to the optical fiber is about 200 g of tension provided between the disk 4a and the disk 3a to loosen the optical fiber 2. Is added, and the durability of the optical fiber 2 is improved.
[0029]
To improve the measurement sensitivity, if the diameter ratio between the disk 6a and the disk 4a is 1: 2, the optical fiber 2 expands and contracts at twice the amount of displacement between the anchors. Conversely, if the measurement range is expanded, the disk ratio is set to 2: It should be set to 1. By changing the diameter ratio of the disks 6a, 4a, and 3a in this manner, the displacement detection sensitivity and the measurement range length can be easily changed.
[0045]
[Embodiment- 2 ]
Here, FIG. 2 is a schematic configuration diagram of a modification monitoring system, and FIG. 3 is a schematic configuration diagram of another modification monitoring system.
[0046]
2, Deformation monitoring system 31, for example, an optical displacement sensor 1 using the optical fiber according to Embodiment -1 of said embodiment, a plurality placed at a location to detect the Deformation i.e. displacement, each optical displacement By detecting the deformation, that is, the displacement, by utilizing the fact that the number of turns of the light attenuation circular curve portion 3 of the optical fiber 2 of the optical fiber 2 of the sensor 1 changes due to the displacement and the intensity of the transmitted light of the light changes, it is possible to detect a mountain or a cliff. This is a monitoring system that detects deformation and collapse of slopes, deformation and collapse of structures, etc., and issues an alarm.
[0047]
The deformation monitoring system 31 includes an optical displacement sensor 1 using a plurality of optical fibers arranged at displacement detection locations, an optical fiber 2 for connecting the optical displacement sensors 1 in a relaxed state in series, and one end of the optical fiber 2 . light projecting circuit 32 but which are connected, the light receiving circuit 33 to which the other end of the optical fiber 2 is connected, the alarm output circuit 40 for issuing an alarm connected to the light receiving circuit 33, by switching the light switch 42 to the other end of the optical fiber 2 It mainly includes an OTDR circuit 43 connected thereto.
[0048]
Further, between the light receiving circuit 33 and the alarm output circuit 40, a photoelectric amplifier 34, a measurement range setting circuit 35, a buffer circuit 36, a linearize circuit 37, an alarm value setting circuit 38, and a comparator circuit 39 are sequentially connected. I have. Further, an external interface circuit 41 which branches from the linearize circuit 37 and outputs a transmission signal to the outside is connected.
[0049]
A switching optical switch 42 is provided at the other end of the optical fiber 2 . The switching light switch 42 automatically switches from the light receiving circuit 33 to the OTDR circuit 43 in response to a warning signal from the warning output circuit 40.
[0050]
The OTDR circuit 43 is an abbreviation that takes the initials of the Optical Time Domain Reflectometer, and is a device that can measure deformation or displacement at a specific position of each of the plurality of optical displacement sensors 1 .
[0051]
That is, when an optical pulse is incident on the optical fiber 2 from the OTDR circuit 43, if local deformation or displacement occurs in the optical fiber 2 , Rayleigh backscattered light is generated due to a change in the refractive index of that portion. Then it returns to the incident end. The Rayleigh backscattered light returns after a time proportional to the distance to the reflection point, and its intensity depends on the change in the refractive index at the reflection point, that is, the deformation or displacement. With this principle, the OTDR circuit 43 can know the size and position of the deformation based on the time and intensity.
[0052]
In addition, since the OTDR circuit 43 is expensive, in the case of a low-cost monitoring system that does not need to specify the position of the deformation or displacement, as shown in FIG. 3 , the OTDR circuit 43 is omitted together with the switching optical switch 42. .
[0053]
Next, the operation of the deformation monitoring system 31 based on the configuration of the embodiment of the present invention will be described below.
Sensing light enters from a light projecting circuit 32 to which one end of the optical fiber 2 is connected. The incident sensing light reaches the other end of the optical fiber 2 via the light attenuation circular curve portion 3 of the plurality of optical displacement sensors 1 installed at the deformation, that is, the displacement detection point.
[0054]
A switching optical switch 42 is provided at the other end of the optical fiber 2 , and the switching optical switch 42 is normally selected on the light receiving circuit 33 side, and the transmitted light is converted into an electric signal by the light receiving element of the light receiving circuit 33. , To the photoelectric amplifier 34. The signal amplified by the photoelectric amplifier 34 is set to selectively extract a required portion of the detection characteristic determined by the sensor by the measurement range setting circuit 35, and is linearized by the linearize circuit 37 through the impedance conversion of the buffer circuit 36. Then, it is sent to the alarm value setting circuit 38.
[0055]
This signal is compared with a required set value corresponding to a change in the amount of transmitted light expected due to the occurrence of the deformation, that is, the displacement, by the comparator circuit 39. Is issued from the alarm output circuit 40 in real time.
[0056]
Further, this alarm signal drives the switching optical switch 42 to switch its optical path to the OTDR circuit 43 side. As a result, the altitude monitoring for identifying the location where the deformation or displacement occurs is continued.
[0057]
Note that the signal output from the linearize circuit 37 is also distributed to the external interface circuit 41, where it is digitally converted and can be extracted as a transmission signal.
[0058]
Subsequently, a usage example of the deformation monitoring system 31 based on the configuration of the embodiment of the present invention will be described below.
FIG. 4 shows an example of use of the deformation monitoring system 31 in which the optical displacement sensor 1 using an optical fiber is laid in order to quickly and accurately detect a sign of a landslide on a slope such as a mountain area or a cliff.
[0059]
In FIG. 4 , the deformation monitoring system 31 is the one shown in FIG. 2 or FIG. 3 , and the optical fiber 2 includes an inclined surface 51 and an upper inclined surface 52 together with the optical displacement sensor 1 using a plurality of optical fibers. It is laid so as to go around the required monitoring area vertically. In this case, the optical fiber 2 is attached to the head of an anchor 53 driven at an interval determined according to the situation of the slope 51 such as a mountain or a cliff, and is usually shown in order to avoid disturbance due to small animals and weeds. Not protected by cable troughs etc.
[0060]
FIG. 5 shows details of the laying condition on the inclined surface upper portion 52 in FIG. 4. The light of the present invention in which not only an increase in light transmission loss but also a decrease tendency can be detected by a spring mechanism ( spring springs 3e, 4e ). This is a laying example in which the features of the optical displacement sensor 1 using fibers are effectively used.
[0061]
The slopes 51 such as mountains and cliffs on which the optical fiber 2 is to be laid are usually rarely flat, and are often laid on uneven ground as shown in the figure.
[0062]
Here, the optical displacement sensor 1b using an optical fiber installed on the raised portion of the ground indicated by the broken line in the drawing is located at a position slightly higher than the adjacent optical displacement sensor 1a or 1c . Each of the series of optical fibers 2 is fixed on one side of the housing 5 of the optical displacement sensor 1 and laid at an early stage so as to maintain the middle of the change range of the light attenuation circular curve portion 3 . The deformation (height difference) of each section can be detected as a displacement of the optical displacement sensor 1 , that is, a change of the light attenuation circular curve portion 3 .
[0063]
Therefore, even when the upper slope 52 slightly collapses 54 as a precursor to the landslide, the number of turns of the light attenuation circular curve portion 3 of the optical displacement sensor 1b and the optical displacement sensor 1c is reduced by the settling of the central optical displacement sensor 1b. At first, the length is reduced in the form 55 in which the extra length of the wiring 6 is taken in , and further reduced in the form 56 in which the insufficient length of the wiring 6 is extended as the sedimentation proceeds, so that the light transmission loss corresponding to the number of turns of the light attenuation circular curve portion 3 is obtained. Numeral 57 follows an increase 59 from a decrease 58 as the collapse progresses, but decreases due to the setting of the detection signal in the negative direction in the alarm value setting circuit 38 of the combination monitoring system 31 ( FIG. 2 ) . Trends can also be used as a signal to signal a landslide.
[0064]
Figure 6 is an installation example for detecting conceive 61 of the inclined surface 51 is a precursor of landslides in the inclined surface 51 in FIG. 4. The optical fiber 2 is laid along the inclined surface 51 in the horizontal direction together with the optical displacement sensors 1a , 1b , and 1c .
[0065]
Further, since a series of optical fibers 2 are fixed by the housing 5 of the optical displacement sensor 1 so as to maintain the middle of the change range of the light attenuation circular curve portion 3, the deformation of each section is This is detected as a change in the number of turns of the light attenuation circular curve portion 3.
[0066]
Here, if the conceive 61 of the inclined surface 51 at the site of the optical displacement sensor 1b has occurred, the optical displacement sensor 1a by the optical displacement sensor 1b is conceive 61, since pushed out forward from the optical displacement sensor 1c, light displacement sensor 1a In addition, the number of turns of the light attenuation circular curve portion 3 of the optical displacement sensor 1c increases in a form 62 in which the shortage of the wiring 6 is extended.
[0067]
Accordingly, the optical displacement sensor 1 causes an increase in light transmission loss, and by monitoring this, it is possible to detect the bulge 61 of the inclined surface 51, which is a precursor to the collapse of earth and sand.
[0068]
【The invention's effect】
As is apparent from the above description, according to the optical displacement sensor using the optical fiber according to the first aspect of the present invention, it is possible to detect the deformation, that is, the minute change in the positive and negative directions of the displacement with high sensitivity. Since the optical fiber can be used in a relaxed state instead of a tension state, the durability of the optical fiber can be enhanced.
[0069]
Further, according to the optical displacement sensor using the optical fiber according to the first aspect of the present invention, in addition to the above-described effects, the same is achieved by increasing the diameter ratio between the light attenuation circular curve portion and the light non-attenuation circular curve portion. Can be increased with respect to the amount of displacement.
[0071]
Further, according to the deformation monitoring system according to the second and third aspects of the present invention, by using the optical displacement sensor using the optical fiber according to the first aspect , a change range of expansion and contraction due to the deformation in the optical fiber laying method. Can be selected according to the expected variation and direction. In addition, a single optical fiber used as a sensor can monitor the steepness of the inclined surface and the collapse of the upper part of the inclined surface, so that an economical and effective system for early detection of earth and sand collapse can be configured.
[0072]
Further, according to the deformation monitoring system according to the second aspect of the present invention, in addition to the above-described effects, when configuring a monitoring system, low cost is obtained by adopting a system excluding an expensive OTDR circuit as a monitoring device. Becomes possible.
[0073]
According to the deformation monitoring system according to the third aspect of the present invention, in addition to the above-described effects, when a monitoring system is configured, an OTDR circuit is added as a monitoring device to specify a location where the deformation has occurred. And high-level monitoring can be performed.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an optical displacement sensor using an optical fiber according to a first embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of a deformation monitoring system according to Embodiment 2 of the present invention.
FIG. 3 is a schematic configuration diagram of another modification monitoring system showing Embodiment 2 of the present invention.
FIG. 4 is a schematic perspective view in which a deformation monitoring system according to Embodiment 2 of the present invention is laid on an inclined surface.
FIG . 5A is a schematic front view of a deformed state of an upper part of an inclined surface on which a deformation monitoring system according to Embodiment 2 of the present invention is laid.
(B) is a side sectional view of the same figure (A).
FIG. 6A is a schematic front view showing a deformed state of an inclined surface on which a deformation monitoring system according to Embodiment 2 of the present invention is laid.
(B) is a side sectional view of the same figure (A).
FIG. 7 is a diagram showing a relationship between an optical fiber loop diameter and transmitted light intensity.
FIG. 8 is a view showing a state where a conventional optical displacement sensor is installed on a slope.
FIG. 9 is a schematic configuration diagram of a conventional optical displacement sensor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Optical displacement sensor using optical fiber 2 Optical fiber 2a Light source 2b Light receiving element 3 Light attenuation circular curve part 3a Disk 3b Fixed point 3c Rotating shaft 3d Ball bearing 3e Spring spring 4 Light non-attenuation circular curve part 4a Disk 4b Fixed point 4c Rotation Axis 4d Ball bearing 4e Spring spring 5 Housing 5a Mounting plate 6 Wiring 6a Disk 6b Pulley 31 Deformation monitoring system 32 Light emitting circuit 33 Light receiving circuit 34 Photoelectric amplifier 35 Measurement range setting circuit 36 Buffer circuit 37 Linearize circuit 38 Alarm value setting circuit 39 Comparator circuit 40 Alarm output circuit 41 External interface circuit 42 Switching optical switch 43 OTDR circuit 51 Inclined surface 52 Inclined surface upper portion 53 Anchor 54 Collapse 55 Incorporation form 56 Protrusion form 57 Loss 58 Decrease 59 Increase 61 Slip 62 Extension method

Claims (3)

In an optical displacement sensor that measures the amount of displacement using a change in transmitted light intensity due to a change in the curvature of an optical fiber, the optical fiber is disposed in a relaxed state, and the optical fiber is wound several times around two disks having different diameters. With a non-attenuating circular curve part and a light attenuating circular curve part, the disk diameter of the light non-attenuating circular curve part is 35 mmφ or more that does not attenuate transmitted light, and the disk diameter of the light attenuating circular curve part is 30 mmφ or less that attenuates transmitted light, The number of windings of the optical fiber in the light non-attenuating circular curve and the light attenuating circular curve is changed according to the amount of expansion and contraction of the wiring that is arranged in tension and expands and contracts in response to the displacement of the displacement detection point, and the measured displacement is applied to both disks. An optical displacement sensor using an optical fiber, comprising a mechanism for changing a winding ratio of the optical fiber. A plurality of optical displacement sensors using the optical fiber according to claim 1 are arranged at a displacement detection position, and each of the optical displacement sensors is connected in series with an optical fiber in a relaxed state, and one end of the optical fiber is projected. Connected to the circuit, the other end of the optical fiber is connected to the light receiving circuit, the alarm output circuit that issues an alarm is connected to the light receiving circuit, and the number of turns or the radius of curvature of the curved portion of the optical fiber changes due to displacement at the displacement detection point A deformation monitoring system characterized in that a displacement of a displacement detection point is detected by using a change in transmitted light intensity of the light to generate an alarm. A plurality of optical displacement sensors using the optical fiber according to claim 1 are arranged at a displacement detection position, and each of the optical displacement sensors is connected in series with an optical fiber in a relaxed state, and one end of the optical fiber is projected. Circuit, a light receiving circuit is connected to the other end of the optical fiber via a switching optical switch, an alarm output circuit that issues an alarm is connected to the light receiving circuit, and a switching optical switch that is switched by an alarm signal from the alarm output circuit is connected. An OTDR circuit that is connected to the other end of the optical fiber via a switch and specifies the displacement occurrence position of the displacement detection point is provided. At the displacement detection point, the number of turns or the radius of curvature of the curved portion of the optical fiber changes due to the displacement and light transmission. Utilizing the change in light intensity, the displacement of the displacement detection point is detected and an alarm is issued, and the OTDR circuit detects a specific displacement occurrence position of the displacement detection point. Deformation monitoring system, characterized in that the the like.

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