JP4763296B2 - Detection device - Google Patents

Description

  The present invention relates to a detection apparatus that detects a change in a physical quantity by measuring a change in optical transmission characteristics of an optical fiber due to a change in the physical quantity.

2. Description of the Related Art Conventionally, various detection devices that measure changes in optical transmission characteristics of optical fibers caused by changes in physical quantities and detect changes in physical quantities have been used.
These detectors use, for example, the fact that the intensity of light scattering such as Raman scattered light or Rayleigh scattered light in an optical fiber varies with temperature, and the optical transmission of these scattered light depends on the ambient temperature to which the optical fiber is exposed. There is a temperature detection device that measures changes in characteristics and detects the temperature of a measurement location (see, for example, Patent Document 1).

There is also a detection device that uses a movable part that is movable by a change in physical quantity, applies stress to the optical fiber by the movable part, and measures a change in optical transmission characteristics of the optical fiber due to the stress to detect a change in physical quantity.
As a detection device using a movable portion, for example, a water level detection device using a float mechanism as a movable portion, and an open / close detection device using a lid, a door, or the like as a movable portion are known. Patent Documents 2, 3 and the like disclose a configuration in which an optical fiber is wound as a configuration of an optical fiber that catches the movement of a movable portion.

In these detectors, as shown in FIG. 14, a plurality of measurement points 4, 4,... Are provided in series on a single optical fiber line 3, and an optical pulse measuring device (Optical Time Domain Reflectometry, hereinafter referred to as OTDR). 2) Measure the optical transmission characteristic change (typically the optical transmission loss change) of the optical fiber at each measurement location in 2), and the presence or absence of the physical quantity change that occurred at the measurement locations 4, 4 ... on the optical fiber line 3 Is detected.
In OTDR2, averaging processing is performed to improve the S / N ratio of signal light. That is, since the scattered light measured by OTDR2 is weak and greatly affected by irregularly generated noise, the measurement is repeated a plurality of times within a predetermined time, and the measurement values obtained by averaging a plurality of times are output as an output value. Thus, the influence of irregularly generated noise is reduced. FIG. 15 schematically shows this state.
Measurement by OTDR2 is performed at a time interval of t1 as shown in a diagram 5, while output is performed at a time interval of t2, which is five times t1, for example, as shown in a diagram 6. Since the output value 8 in the diagram 6 is an average of the five measured values 9, 9,... In the diagram 5, the irregular noise 10 is diluted to 1/5 in this case and the output value 8 is a true value. And close.
Such an averaging process is disclosed in Patent Document 4, for example.
JP-A-8-233668 Japanese Patent Laid-Open No. 10-82621 Japanese Patent Laid-Open No. 6-148017 JP-A-7-218354

In such an averaging process, the measurement time interval t1 requires a longer time as the length of the optical fiber line becomes longer, and the influence of noise can be reduced as the number of times of measurement for one output is increased. The time interval t2 becomes longer.
In one example in which the measured value of the change in optical transmission characteristics of the optical fiber is binarized to detect the presence or absence (ON / OFF) of a change in physical quantity, when the optical fiber line length is 30 km, the output time interval t2 is about 10 seconds are required. For this reason, there are restrictions on use in places where high-speed detection is required.

In order to solve the above-described problems and provide a detection device capable of high-speed detection, the present inventor has conceived the following concept as a result of intensive studies. That is, (1) The detection device according to claim 1 has an optical transmission system composed of an optical fiber line and a measurement point directly connected to the optical fiber line, and changes in the optical transmission characteristics of the measurement point due to changes in physical quantities. And detecting a change in the physical quantity,
A plurality of transmission systems and an optical transmission characteristic measuring device provided in each of the plurality of transmission systems for one measurement location, and each of the optical transmission characteristic measuring devices is arranged on the same side in the plurality of transmission systems. Te, outputs the optical transmission characteristic values of the measuring points at different times from each other, the combined output of each of the optical transmission characteristic value, to shorten the time interval of the output of the optical transmission characteristic values with,
And at least a first measurement location and a second measurement location that are installed in the flow path and are capable of measuring the presence or absence of water, wherein the first measurement location is upstream of the second measurement location. The flow velocity can be measured from the difference in operating time of each measurement location and the distance of each measurement location.
(2) The detection apparatus according to claim 2 is the detection apparatus according to claim 1, wherein the plurality of transmission systems are a plurality of optical fiber lines.
(3) detecting apparatus according to claim 3, a detecting apparatus according to claim 1, wherein the plurality of transmission lines is the different transmission systems having wavelengths propagating Thus one optical fiber line in a wavelength division multiplexing It is characterized by that.
(4) The detection device according to claim 4 is the detection device according to claim 2 or claim 3, wherein the optical transmission characteristic value output from the optical transmission characteristic measuring device is measured within a predetermined time. It is a value obtained by optimizing a plurality of measured values.
(5) The detection device according to claim 5 is the detection device according to claim 1, wherein the second measurement location further includes a plurality of measurement locations, and at least two measurement locations of the plurality of measurement locations. Are installed with vertical differences from each other.
(6) The detection device according to claim 6 is the detection device according to claim 5, wherein the two measurement locations are installed at a location where liquid is accumulated with a vertical difference in height.
(7) The detection device according to claim 7 is the detection device according to any one of claims 1 to 6, wherein the measurement portion is attached to the optical fiber by a movable portion that is movable in accordance with a change in the physical quantity. It is characterized in that a stress is applied and a change in optical transmission characteristics is caused in the optical fiber by the stress.
(8) Claim 8 is a first measurement location installed upstream of the overflow pipe of the sewer, a second measurement location installed downstream of the overflow pipe, and the first and second An optical transmission system comprising an optical fiber line directly connected to each of the measurement points, the optical transmission system having an optical transmission characteristic measuring instrument, and the first and second optical transmission characteristic measuring instruments are used to A physical quantity change detecting method for measuring a change in physical quantity at each measurement location as a change in optical transmission property at each measurement location, wherein a plurality of optical transmission systems and optical transmission property measuring instruments are provided for each measurement location. In addition, the optical transmission characteristic measuring device of each of the plurality of optical transmission systems combines the output of the optical transmission characteristic values at the measurement locations at different times, thereby shortening the time interval between the output of the optical transmission characteristic values. In addition, the sewage flow caused by the overflow of the sewer operates the first and second measurement points, and the difference between the operation times of the measurement points and the distance between the measurement points known in advance, It is characterized by measuring the flow rate.
(9) Claim 9 is the physical quantity change detection method according to claim 8,
Having a third measurement location above either the first or second measurement location, and measuring the water level of the sewage flow according to the physical quantity change of the first, second, or third measurement location. Features.
(10) Claim 10 is the physical quantity change detection method according to claim 9,
The flow rate of the sewage flow is measured from the measured water level of the sewage flow and the dimension of the cross section of the overflow pipe known in advance.

  According to the detection device of the first aspect, since the optical transmission characteristic values are output at different times from the respective optical transmission characteristic measuring devices provided in the plurality of transmission systems, it is based on the optical transmission characteristic measurement values of one transmission system. Even when the time required for output is long, output based on the measured values of the optical transmission characteristics of other transmission systems can be performed between the previous output and the current output. As a result, the characteristic value can be output at a substantially short time interval, and the request for high-speed detection can be met.

The plurality of transmission systems can be realized, for example, by providing a plurality of optical fiber lines as in the detection device of claim 2.
Further, even when only one optical fiber line is provided as in the detection device of claim 3, a plurality of transmission systems are configured by propagating different wavelengths through one optical fiber line and wavelength division multiplexing. You can also.
In particular, when the optical transmission characteristic value output from the optical transmission characteristic measuring device is a value obtained by optimizing a plurality of measured values measured within a predetermined time, it is preferable in terms of the accuracy of the output value. However, the time interval from the previous output to the current output tends to be longer. Therefore, in the detection device according to claim 4, since the optimization process and each of the optical transmission characteristic measuring devices output the optical transmission characteristic value of the optical fiber line at different times, the accuracy is improved. And shortening the output time interval.

Further, even when a plurality of transmission systems are not provided, according to the detection device of the fifth aspect, output is possible at the n + a-th measurement time and the n + c-th measurement time. That is, if this operation is repeated, the characteristic value is also output at the (n + c) th measurement time between the (n + a) th measurement time and the (n + 2a) th measurement time. Can be used.
Since these output values are values obtained by optimizing a plurality of measured values, the influence of noise can be reduced.

All of the above-described detection devices supply high-speed detection. For this reason, when the first and second measurement locations are installed in the flow path as in the detection device of claim 1 , it is possible to detect that the liquid has reached the flow path where there was no liquid until a certain point in time, This is useful for detecting the difference in time when the flow path reaches the first measurement location and the second measurement location, and the flow velocity can also be known from the time difference.
Similarly, according to the detection device of the fifth aspect , it is possible to detect whether or not the liquid level (the water level when the liquid is water) has reached each measurement location and the rising speed of the liquid level.

According to the detection method described in claims 8, 9 and 10, the flow velocity is obtained from the difference in detection time between the first measurement location provided on the upstream side and the second measurement location provided on the downstream side. The liquid level can be known by detecting which measurement point of the second measurement point, which is composed of a plurality of measurement points provided with a vertical difference in the vertical direction, has reached the liquid. That is, the flow rate can be known by considering the dimension of the cross section of the flow path.

  The measurement part of the above-described detection apparatus preferably applies various stresses by applying stress to the optical fiber by the movable part that moves in accordance with the change in the physical quantity, and causing the optical fiber to change in the optical fiber due to the stress. Changes in physical quantities can be converted into changes in optical transmission characteristics.

The best mode for carrying out the present invention will be described below. As shown in FIG. 1, the detection device in the present embodiment is configured as a flood detection device for an overflow outlet of a sewer.
1, overflow pipes 101, 102,... Are connected to predetermined locations of the sewer pipe 11, and discharge overflow from the sewer pipe 11 to the outside of the system 12. The outside of the system 12 is, for example, a river or the sea. The presence and flow rate of overflowing sewage is a serious concern for sewer managers. Therefore, the overflow pipes 101, 102,... Are provided with three measurement points 21, 22, 23 and 24, 25, 26,.

  Now, taking the overflow pipe 101 as an example, the measurement location installed in the overflow pipe 101 is firstly a probe 21a connected in series on the optical fiber line 31 and a probe 21b connected in series on the optical fiber line 32. A measurement point 21 comprising: a second probe 22 a connected in series on the optical fiber line 31; a second measurement point 22 comprising a probe 22 b connected in series on the optical fiber line 32; and a third on the optical fiber line 31. There are three measurement points 23, which are a probe 23 a connected in series and a probe 23 b connected in series on the optical fiber line 32.

Probes 24a, 25a, 26a, and probes 24b, 25b, 26b constituting measurement points 24, 25, 26 installed in other overflow pipes 102 are also connected in series on the optical fiber lines 31, 32, respectively. The optical fiber lines 31 and 32 are connected to OTDRs 41 and 42, respectively.
A light pulse is incident on the optical fiber lines 31 and 32 from the OTDRs 41 and 42 and the intensity of the backscattered light is measured, so that the optical fiber lines 31 and 32 are measured at predetermined locations (in the present embodiment, measurement locations 21 and 26). Change in transmission characteristics can be known.

  However, as described above in the Background Art section, the backscattered light is weak, and an averaging process as an optimization process is useful to reduce the influence of noise. In this case, the time for outputting the optical transmission characteristic value The interval will be longer. In this embodiment, the averaging process is performed as an optimization process, but the time interval for outputting the optical transmission measurement value is shortened as described below.

In other words, the OTDR 41 measures the optical transmission characteristics of the first optical transmission system including the optical fiber line 31 and the probes 21a... 26a at the time interval t1 starting from the time A, and is an averaged value at the time interval t2. Is output.
On the other hand, the OTDR 42 measures the optical transmission characteristics of the second optical transmission system composed of the optical fiber line 32 and the probes 21b... 26b at a time interval t1 starting from a time B delayed by t2 / 2 from the time A. The averaged value at the interval t2 is output. Then, when the outputs from the two OTDRs 41 and 42 are considered together, the output time interval is t2 / 2, and the time interval can be reduced to half.
FIG. 2 schematically shows this state. In FIG. 2, a diagram 51 is a measured value of OTDR 41, a diagram 52 is an output value of OTDR 41, a diagram 53 is a measured value of OTDR 42, and a diagram 54 is OTDR 42. Is the output value. In this embodiment, the number of optical transmission systems is two. However, if the number of optical transmission systems is increased, the output time interval can be shortened accordingly.

Next, how to install the measurement locations 21, 22, and 23 in one overflow pipe, for example, the overflow pipe 101 will be described.
As shown in FIG. 3, the overflow pipe 101 is provided with a measurement location 21 at the height H1 from the bottom of the tube on the upstream side, and the measurement location 22 at a height H1 from the bottom of the tube downstream of the measurement location 21. Is installed, and a measurement location 23 is installed at a height of H2 from the bottom of the tube vertically above the measurement location 22.

Now, assuming that a sewage flow due to overflow has occurred, the sewage flow first changes the optical transmission characteristics of the measurement location 21 (hereinafter referred to as operation), and after a predetermined time t3, only the measurement location 22 or the measurement locations 22 and 23. Is activated.
In the present embodiment, since the output time interval from the OTDR 41 is shortened, a change within the predetermined time t3 that is a relatively short time can be output.
Then, the difference between the operation time of the measurement location 21 and the operation time of the measurement location 22 can be known. Thereby, since the distance between the measurement location 21 and the measurement location 22 is known, the speed of the sewage flow can be known. When the water level of the sewage flow is above the measurement point 22 and below the measurement point 23, the sewage flow activates only the measurement point 22, and when the water level is above the measurement point 23, the measurement points 22 and 23 are set. Since it is operated, it is possible to know the water level of the sewage flow by detecting whether only 22 measurement points are operated or both measurement points 22 and 23.
As a result, since the dimension of the cross section of the overflow pipe 101 is known, the flow rate of the sewage flow can be known.
In this embodiment, the number of measurement points is three. However, if the number of measurement points, especially the number of measurement points installed downstream, is increased and installed at various heights, the resolution of flow rate detection can be improved. Can do.

Next, the structure of the measurement location will be described. As shown in FIG. 4, in the measurement location 21, two optical fibers 211 and 212 are wound around supports 201 and 202 to form probes 21a and 21b. The optical fibers 211 and 212 are connected in series to the optical fiber lines 31 and 32, respectively.
As shown in FIG. 5, the support tool 202 is fixed, and the support tool 201 is connected to the float 220 and is movable. If the float 220 and the support tool 201 rise as the water level rises, the probes 21a and 21b wound around the support tools 201 and 202 are deformed, causing an increase in transmission loss due to macrobending and being detected by the OTDRs 41 and 42. It becomes.

  In this way, in the present embodiment, the time interval for outputting the change in the optical transmission characteristics is shortened, so that the flow velocity and flow rate can be detected, and a detection device suitable for monitoring the overflow of the sewer is realized. Yes.

Other embodiments will be described below.
First, in order to shorten the time interval for outputting the change in the optical transmission characteristics, instead of using a plurality of optical fiber lines, light having different wavelengths is propagated to one optical fiber line, and a plurality of transmission systems are transmitted by wavelength division multiplexing. May be configured. In this case, for example, as shown in FIG. 6, it is realized by a detection device including OTDRs 41 and 42, an optical multiplexer / demultiplexer 50, an optical fiber line 31, and measurement points 27 and 28.

  Further, the detection device may not perform an output value optimization process. For example, as shown in FIG. 7, the first optical transmission measuring device outputs the measured value as it is every time it is measured (diagram 55), and the second optical transmission measuring device also outputs the measured value as it is every time it is measured. (Diagram 56) Even in the case, the output time interval can be shortened by changing the output time.

  Further, even if only one transmission system is provided, as shown in FIG. 8, the output value 500 is obtained by measuring the optical transmission characteristics a plurality of times and optimizing the first measurement value to the fifth measurement value. , And output the output value 501... That has been optimized for five measurement values thereafter, and output the output value 510 that has been optimized from the third measurement value to the seventh measurement value. It is also possible to achieve both optimization processing and shortening of the output time interval by repeating output of output values 511.

  As for the optimization process, in addition to the averaging process described above, one that outputs a median value selected from a plurality of measurement values, one that outputs a mode value, or a measurement value outside a predetermined range Various methods such as a method that ignores the above or a combination thereof can be adopted.

  Furthermore, as an optical transmission characteristic measuring device, light sources 45 and 46 and power meters 43 and 44 may be used instead of the OTDR as shown in FIG.

Regarding the configuration of the measurement location, in addition to the configuration described above, as shown in FIG. 10, one end of the optical fiber constituting the optical fiber tape core wire 213 is formed by winding the optical fiber tape core wire 213 around the support tools 201 and 202. It can be configured by short-circuiting as appropriate.
In addition, even if a winding part is not necessarily provided, the linear part of the optical fiber 230 is pressed by the movable part as shown in FIG. 11 (a) and stress is applied, and the movable part as shown in FIG. 11 (b). Various configurations can be employed, such as those that are pulled to apply stress.

  When the detection device of the present invention is used for inundation detection, the arrangement of the measurement points may be as follows. That is, as shown in FIG. 12, if the two measurement locations 21 and 22 are installed at locations with different flow directions, they are unsuitable for detecting the flow rate but can detect the flow velocity. Moreover, as shown in FIG. 13, if the measurement locations 21 and 22 are installed with a height difference in the vertical direction at the location where the liquid accumulates, the liquid level and the rising speed of the liquid level can be detected.

  The detection device according to the present invention can be applied not only to detection of flooding but also to detection of changes in various physical quantities such as detection of opening / closing of lids, doors, etc., temperature detection and the like.

  As described above, according to the present invention, since the output time interval of the optical transmission characteristic value is shortened, it is possible to provide a detection device applicable to various scenes.

The schematic diagram which shows the detection apparatus which concerns on this invention. The conceptual diagram which shows the measurement and output state in the detection apparatus based on this invention. The schematic diagram which shows the measurement location installation state of the detection apparatus which concerns on this invention. The schematic diagram which shows the structure of the measurement location of the detection apparatus which concerns on this invention. The schematic diagram which shows the structure of the measurement location of the detection apparatus which concerns on this invention. The schematic diagram which shows the detection apparatus which concerns on this invention. The conceptual diagram which shows the measurement and output state in the detection apparatus based on this invention. The conceptual diagram which shows the measurement and output state in the detection apparatus based on this invention. The schematic diagram which shows the detection apparatus which concerns on this invention. The schematic diagram which shows the structure of the measurement location of the detection apparatus which concerns on this invention. The schematic diagram which shows the structure of the measurement location of the detection apparatus which concerns on this invention. The schematic diagram which shows the measurement location installation state of the detection apparatus which concerns on this invention. The schematic diagram which shows the measurement location installation state of the detection apparatus which concerns on this invention. The schematic diagram which shows the conventional detection apparatus. The conceptual diagram which shows the measurement and output state in the conventional detection apparatus.

Explanation of symbols

1 Detector 2 OTDR
DESCRIPTION OF SYMBOLS 3 Optical fiber line 4 Measurement location 5 Measurement diagram 6 Output diagram 8 Output value 9 Measurement value 10 Noise 11 Sewage pipe 12 Out-of-system 101 Overflow pipe 102 Overflow pipe 21 Measurement location 21a Probe 21b Probe 22 Measurement location 22a Probe 22b Probe 23 Measurement location 23a Probe 23b Probe 24 Measurement location 24a Probe 24b Probe 25 Measurement location 25a Probe 25b Probe 26 Measurement location 26a Probe 26b Probe 27 Measurement location 28 Measurement location 201 Support fixture 202 Support fixture 211 Optical fiber 212 Optical fiber 213 Optical fiber tape core Line 220 Float 230 Optical fiber 31 Optical fiber line 32 Optical fiber line 41 OTDR
42 OTDR
43 Power meter 44 Power meter 45 Light source 46 Light source 50 Optical multiplexer / demultiplexer 51 Measurement diagram 52 Output diagram 53 Measurement diagram 54 Output diagram 55 Measurement / output diagram 56 Measurement / output diagram 500 Output value 501 Output value 510 Output value 511 Output value

Claims (10)

An optical transmission system comprising an optical fiber line and a measurement point directly connected to the optical fiber line, and detecting a change in the physical quantity by measuring a change in the optical transmission characteristic of the measurement point due to a change in the physical quantity A device,
A plurality of transmission systems and an optical transmission characteristic measuring device provided in each of the plurality of transmission systems for one measurement location, and each of the optical transmission characteristic measuring devices is arranged on the same side in the plurality of transmission systems. Te, outputs the optical transmission characteristic values of the measuring points at different times from each other, the combined output of each of the optical transmission characteristic value, to shorten the time interval of the output of the optical transmission characteristic values with,
And at least a first measurement location and a second measurement location that are installed in the flow path and are capable of measuring the presence or absence of water, wherein the first measurement location is upstream of the second measurement location. A detection apparatus, which is installed on the side and capable of measuring a flow velocity from a difference in operating time of each measurement location and a distance between each measurement location.   The detection device according to claim 1, wherein the plurality of transmission systems are a plurality of optical fiber lines. A detecting device according to claim 1, wherein the plurality of transmission lines, detecting device, characterized in that the different transmission systems having wavelengths propagating Thus one optical fiber line in wavelength division multiplexing.   4. The detection device according to claim 2, wherein the optical transmission characteristic value output from the optical transmission characteristic measuring device is a value obtained by optimizing a plurality of measured values measured within a predetermined time. A detection device characterized by being.   The detection apparatus according to claim 1, wherein the second measurement location further includes a plurality of measurement locations, and at least two of the plurality of measurement locations are installed with a height difference in the vertical direction. A detection device characterized by that.   6. The detection device according to claim 5, wherein the two measurement locations are installed with a height difference in a vertical direction at a location where the liquid accumulates.   7. The detection device according to claim 1, wherein the measurement portion applies stress to the optical fiber by a movable portion that is movable according to a change in the physical quantity, and the optical fiber is applied by the stress. A sensing device characterized by causing a change in optical transmission characteristics. A first measurement location installed upstream of the overflow pipe of the sewer,
A second measurement location installed downstream of the overflow pipe;
An optical transmission system comprising an optical fiber line directly connected to each of the first and second measurement points;
The optical transmission system has an optical transmission characteristic measuring device,
A physical quantity change detection method for measuring a change in physical quantity at the first and second measurement points as a change in optical transmission characteristic at each measurement point by the optical transmission characteristic measuring device,
The optical transmission system and the optical transmission characteristic measuring instrument are plural for each measurement point,
And the optical transmission characteristic measuring device of each of the plurality of optical transmission systems is adapted to output the optical transmission characteristic value of the measurement location at different times, and shorten the time interval of output of the optical transmission characteristic value,
The sewer flow caused by the overflow of the sewer operates the first and second measurement points, and the flow velocity of the sewer flow is measured from the difference between the operation times of the measurement points and the distance between the measurement points known in advance. A method for detecting a change in physical quantity, characterized by: The physical quantity change detection method according to claim 8,
Having a third measurement location above either the first or second measurement location, and measuring the water level of the sewage flow according to the physical quantity change of the first, second, or third measurement location. A method for detecting changes in physical quantities. The physical quantity change detection method according to claim 9,
A physical quantity change detection method, comprising: measuring a flow rate of a sewage flow from a measured water level of the sewage flow and a cross-sectional dimension of a known overflow pipe.

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