JP2011197935A - Multipoint optical fiber sensor device and node communication control method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multipoint optical fiber sensor device that eliminates the need for arranging multiple optical fibers, and also performs measurement according to a request from the measurement station side (call origination from the node side).SOLUTION: In the device, multiple measuring points 2 are arranged at intervals in one optical fiber main line 1. The measuring points 2 include: an optical switch 8, which branches an optical fiber branch line 7 from the main line 1, and which is changed into the main line side in an initial state; an optical sensor unit 9 arranged on the tip of the branch line 7; a first optical detector 10 for detecting a transmission light 3 to be transmitted through the main line 1; a second optical detector 11 for detecting a reflected light 5 to be transmitted through the main line 1; a communication control unit 12 configured such that the first optical detector 10 detects the transmission light 3 when a request condition C1 for sending sensor information is satisfied, and switches the optical switch 8 to the branch line side when the second optical detector 11 does not detect the reflected light 5; and a power supply 13 for supplying electric power to at least the communication control unit 12 and the optical switch 8. The communication control unit 12 switches the optical switch 8 to the main line side, after the reflected light 5 from the optical sensor unit 9 is returned to the main line 1.

Description

  The present invention relates to a multipoint optical fiber sensor device and a node communication control method thereof. More specifically, in the present invention, a plurality of optical sensors are connected in the middle of one optical fiber trunk line, transmitted light is transmitted from a transmitter, and sensor information is collected based on reflected light from the optical sensor. The present invention relates to a point-type optical fiber sensor device and a node communication control method thereof.

  As a multipoint optical fiber sensor device, an optical sensor using an optical coupler 123 or a wavelength division multiplexing coupler (WDM coupler) 124 at a measurement point in the middle of one optical fiber 121 as shown in FIGS. 125 is connected, but when the optical coupler 123 is used (FIG. 5), the attenuation of the transmitted light 126 when passing through the optical coupler 123 is significant, and when the WDM coupler 124 is used (FIG. 5). In 6), since it is necessary to change the wavelength characteristics (λ1, λ2, λ3,...) Of the light branched for each WDM coupler 124, it is difficult to provide many measurement points in either case. Therefore, there is a multipoint optical fiber sensor device that uses an optical switch instead of the optical coupler 123 and the WDM coupler 124 to connect the optical sensors (Patent Document 1).

  This multipoint type optical fiber sensor device is shown in FIG. The multi-point optical fiber sensor device includes a sensor selection light source 103 and a sensing light source 104 for operating the optical switch 102 at each measurement point 101, and performs measurement using three optical fibers 105, 106, and 107. Is going.

  For example, when the measurement is performed at the second measurement point 101 from the upstream side, the control device 108 instructs the sensor selection light source 103 to transmit a second selection signal for selecting the optical gas sensor 109 at the measurement point 101. . In response to this command, a second selection signal is transmitted from the sensor selection light source 103 to the selection signal optical fiber 105, and when this selection signal is received by the optical / electrical converter 110 at the second measurement point 101, optical / electrical conversion is performed. The device 110 switches the optical switches 102 and 102 to the optical sensor side. Accordingly, the transmitted light transmitted from the sensing light source 104 to the sensor input signal optical fiber 106 is supplied to the optical sensor side at the second measurement point 101, and after being modulated by the optical gas sensor 109, the sensor output signal The optical fiber 107 is supplied to the branching filter 111, detected by the photodetector 112, and processed by the arithmetic processing unit 113.

  The control device 108 repeats such measurement for each measurement point 101, 101,... In order, and measurement at each measurement point 101 is performed.

  In this multipoint type optical fiber sensor device, the optical switches 102 and 102 are used to connect the optical gas sensor 109, so that the attenuation of the transmitted light passing through the measurement point 101 is slight, and it is like a WDM coupler. In addition, since there is no need to change the wavelength characteristics for each measurement point 101, a large number of measurement points 101 can be provided.

Japanese Patent Laid-Open No. 4-286917

  However, in the above-described multipoint optical fiber sensor device, the optical fiber 105 for operating the optical switch 102 is necessary in addition to the optical fibers 106 and 107 used directly for measurement, and the installation becomes large. .

  Moreover, since the measurement point 101 used by control from the control apparatus 108 is determined, it cannot measure according to the request | requirement from the measurement point 101 side.

  It is an object of the present invention to provide a multi-point optical fiber sensor device that does not need to provide a plurality of optical fibers and can perform measurement in response to a request from the measurement point side (call from the node side). .

  In order to achieve such an object, the invention according to claim 1 is provided with a plurality of measurement points spaced from each other on one optical fiber trunk line, and a transmitter for transmitting outgoing light to the optical fiber trunk line and the measurement point. In the multipoint optical fiber sensor device provided with a receiver that receives the reflected light of the transmitter, the transmitter transmits the transmitted light regardless of the transmission request from the measurement point side, An optical switch that branches one optical fiber branch line from the optical fiber trunk line and is switched to the trunk line side in the initial state, a reflective optical sensor section provided at the tip of the optical fiber branch line, and an optical fiber The first light detection means for detecting the transmitted light transmitted in the down direction through the main line, the second light detection means for detecting the reflected light transmitted in the up direction through the optical fiber main line, and the sensor information transmission request condition are satisfied Case A communication control unit that switches the optical switch to the branch line side when the first light detection unit detects the transmitted light and the second light detection unit does not detect the reflected light, and at least a communication control unit; A power supply for supplying power to the optical switch is provided, and the communication control unit switches the optical switch to the main line side after the reflected light from the optical sensor unit returns to the optical fiber main line.

  In the initial state where the multipoint optical fiber sensor device is installed, the optical switch is switched to the main line side. In this state, the transmitter transmits the transmitted light regardless of the transmission request on the measurement point side, but since the light is not reflected at the farthest end of the optical fiber trunk line, the reflected light does not return from anywhere.

  In this state, when a predetermined transmission request condition C1 is satisfied at a node at a certain measurement point, the communication control unit at the measurement point switches the optical switch to the branch line side. Therefore, the transmitted light transmitted through the optical fiber trunk line is transmitted to the optical fiber branch line, supplied to the optical sensor unit, and modulated according to the sensor information. Then, the reflected light from the optical sensor part returns from the optical fiber branch line through the optical switch to the optical fiber trunk line, travels along the optical fiber trunk line in the upstream direction, and is received by the receiver. Thereby, collection of sensor information is performed.

  In order to perform such a measurement using a single optical fiber trunk line, it is possible to prevent simultaneous communication (returning reflected light on which sensor information is superimposed by taking in outgoing light) at a plurality of measurement points. Therefore, it is necessary to switch the optical switch at the measurement point upstream from the measurement point currently communicating to the main line side so that the reflected light from the measurement point at which communication has been performed reliably reaches the receiver. is there. That is, it is necessary to prevent communication collisions with other measurement points. Therefore, in the present invention, the first light detection means and the second light detection means are provided to detect the presence / absence of communication at other measurement points, and to communicate when communication is not performed at other measurement points. Like to do.

  Now, when the first light detection means detects the outgoing light that travels down the optical fiber trunk line, that is, when the first light detection means is in the ON state, it is upstream from the measurement point (side closer to the transmitter). The optical switches at the measurement points are all switched to the main line side, and it is considered that all the upstream measurement points are not communicating. Further, when the second light detection means does not detect the reflected light that goes up the optical fiber trunk line, that is, when the second light detection means is in the OFF state, it is downstream of the measurement point (far from the transmitter). It is considered that all the measurement points on the side) are not communicating. That is, when the first light detection means is in the on state and the second light detection means is in the off state, communication is not performed at other measurement points. When this condition is satisfied, the communication control unit operates the optical switch to switch to the branch line side, takes in the transmitted light from the transmitter into the optical fiber branch line, and starts communication.

  The communication control unit switches the optical path of the optical switch to the main line side after the reflected light from the optical sensor unit returns from the optical fiber branch line to the optical fiber main line. As a result, communication at the measurement point ends, and other measurement points can communicate.

  In the multipoint optical fiber sensor device according to claim 2, a signal for distinguishing the reflection position is superimposed on the transmitted light. Therefore, it is possible to determine from which measurement point the reflected light is based on the propagation time of the discrimination signal.

  According to a third aspect of the present invention, the transmission request condition is satisfied at a predetermined time or when a state change is detected by the optical sensor unit. Accordingly, periodic measurement is performed at each measurement point, or measurement is performed at a necessary timing.

  Furthermore, in the multipoint optical fiber sensor device according to claim 4, the communication control unit and the optical switch shift to the sleep state except when communication is performed. Therefore, power consumption during non-operation can be suppressed.

  The node communication control method for a multipoint optical fiber sensor device according to claim 5 is provided when a plurality of measurement points are provided on one optical fiber trunk line and a transmission request condition is satisfied at the node of the measurement points. When the communication state of the optical fiber trunk line is checked and it is determined that communication is not performed at another measurement point, communication with the information collecting station is performed. Therefore, it is possible to perform measurement at several points using one optical fiber trunk line. In addition, communication is performed with the information aggregation station in response to a request from the node side of each measurement point.

  In this case, as in the node communication control method of the multipoint optical fiber sensor device according to claim 6, the node detects the transmitted light from the information collecting station and reflects the reflected light from the node at the downstream measurement point. It is preferable to determine that communication is not performed at another measurement point when it cannot be detected.

  According to the multi-point type optical fiber sensor device according to claim 1, since the optical sensor unit is connected to one optical fiber trunk line through the optical switch, a single optical fiber is used at many points. Measurements can be made. Therefore, the configuration can be simplified as compared with the case where a plurality of optical fibers are used, and the apparatus can be prevented from becoming large. Moreover, since the communication control unit performs communication when the sensor information transmission request condition is satisfied, communication can be performed in response to a request from each node side. At this time, since each measurement point performs communication after confirming the vacant state of the optical fiber trunk line, even if only one optical fiber trunk line is used, communication collision can be avoided. The measured sensor information can be reliably sent to the receiver. Furthermore, since an optical switch is used for connection of the optical sensor unit, it is possible to prevent a significant attenuation of the transmitted light as in the case of using an optical coupler, and at each measurement point as in the case of using a WDM coupler. Since there is no need to change the wavelength characteristics, it is possible to provide many measurement points.

  In the multipoint optical fiber sensor device according to claim 2, since the signal for distinguishing the reflection position is superimposed on the transmitted light to be transmitted, the measurement light from which the measurement light is reflected is specified. be able to.

  In the multi-point optical fiber sensor device according to claim 3, the transmission request condition is satisfied at a predetermined time or when a state change is detected by the optical sensor unit. Measurements can be taken when

  Furthermore, in the multipoint optical fiber sensor device according to the fourth aspect, power consumption when the communication control unit and the optical switch are not operated can be suppressed, so that the period until the battery runs out can be extended.

  According to the node communication control method for a multipoint optical fiber sensor device according to claim 5, since a plurality of measurement points are provided on one optical fiber trunk line, a large number of optical fibers are used using one optical fiber. Measurements at points can be made. Therefore, the configuration can be simplified as compared with the case where a plurality of optical fibers are used, and the apparatus can be prevented from becoming large. In addition, since communication is performed when the transmission request condition is satisfied at each measurement point node, communication can be performed according to a request from each node side. At this time, since each node performs communication after confirming the free state of the optical fiber trunk line, even if only one optical fiber trunk line is used, a communication collision can be avoided, and the measured sensor information It can be reliably sent to the information gathering station.

  Further, in the node communication control method of the multipoint optical fiber sensor device according to claim 6, when the node cannot detect the transmitted light from the information collecting station and cannot detect the reflected light from the node at the downstream measurement point. Since it is determined that communication is not being performed at another measurement point, it is possible to easily and reliably detect whether communication is being performed by a node at another measurement point.

It is a block diagram which shows an example of embodiment of the multipoint optical fiber sensor apparatus of this invention, and shows the structure of the node of the measurement point. It is a block diagram which shows schematic structure of the same multipoint type | mold optical fiber sensor apparatus. It is a block diagram which shows the optical sensor part of the multipoint type | mold optical fiber sensor apparatus. It is a flowchart of the communication process which the communication control part of the same multipoint type | mold optical fiber sensor apparatus performs. It is a schematic block diagram which shows the type of multi-point type optical fiber sensor apparatus which connects an optical sensor using an optical coupler. 1 is a schematic configuration diagram showing a multi-point type optical fiber sensor device of a type in which an optical sensor is connected using a wavelength multiplexing coupler. It is a schematic block diagram which shows the multipoint type optical fiber sensor apparatus of the type which connects an optical sensor using the conventional optical switch.

  Hereinafter, the configuration of the present invention will be described in detail based on the form shown in the drawings.

  1 and 2 show an example of an embodiment of the multipoint optical fiber sensor device of the present invention. This multi-point optical fiber sensor device is provided with a plurality of measurement points 2 spaced from one optical fiber main line 1 and from a transmitter 4 and a measurement point 2 for transmitting outgoing light 3 to the optical fiber main line 1. A receiver 6 for receiving the reflected light 5 is provided, and at the measurement point 2, one optical fiber branch line 7 is branched from the optical fiber main line 1 and switched to the main line side in the initial state. Optical switch 8, a reflection-type optical sensor unit 9 provided at the tip of the optical fiber branch line 7, and first light detection means 10 for detecting the outgoing light 3 that travels down the optical fiber trunk 1. And the second light detecting means 11 for detecting the reflected light 5 transmitted in the upward direction on the optical fiber main line 1 and the optical switch 8 when the transmission request condition C2 is satisfied when the sensor information transmission request condition C1 is satisfied. To the branch line side A communication control unit 12 and a power source 13 for supplying power to at least the communication control unit 12 and the optical switch 8 are provided. The communication control unit 12 returns the reflected light 5 from the optical sensor unit 9 to the optical fiber main line 1. Thereafter, the optical switch 8 is switched to the main line side.

  The optical fiber trunk line 1 is formed of one optical fiber. An information aggregating station 14 including a transmitter 4 and a receiver 6 is provided at the upstream end 1 a of the optical fiber main line 1 via an optical circulator 21. The transmitter 4 transmits the transmission light 3 having a time width sufficient to place sensor information on the optical fiber main line 1. For example, an optical transmitter, an E / O converter (electric / optical converter), or the like is used. Is possible. In the present embodiment, the transmitter 4 transmits continuous light as the transmitted light 3. However, the transmitted light 3 is not limited to continuous light, and can be used as long as the light has a time width sufficient to carry sensor information. Further, the transmitter 4 of the present embodiment has a function of superimposing a signal I for distinguishing the reflection position on the transmitted light 3 to be transmitted. The discrimination signal I has a frequency that can be distinguished from the frequency of the sensor signal superimposed on the reflected light 5, and it is generally preferable to use a signal having a higher frequency than the sensor signal. For example, periodic negative polarity pulsed light, light having a waveform representing a code string of a predetermined pattern, or the like can be used. The intensity of the transmitted light 3 is at least large enough to allow the reflected light 5 from the measurement point 2 provided on the most downstream side to be received with the intensity required for measurement. The transmitter 4 transmits the transmitted light 3 regardless of the transmission request from the measurement point 2 side.

  The receiver 6 receives reflected light 5 from the optical fiber trunk line 1. Since the reflected light 5 includes sensor information at the measurement point 2, the sensor information can be collected by receiving the reflected light 5. The receiver 6 can output the waveform information of the received light. As the receiver 6, for example, an optical receiver, an O / E converter (optical / electrical converter), or the like can be used. For example, a commercially available waveform analyzer is connected to the output end of the receiver 6. The waveform analyzer analyzes the waveform based on the waveform information output from the receiver 6, and detects sensor information by modulation, a superimposed discrimination signal I, and the like. For example, an A / D converter can be used as the waveform analyzer. The discrimination signal I is separated from the sensor signal superimposed on the reflected light 5 based on the difference in frequency.

  The measurement points 2 may be provided on the optical fiber main line 1 at regular intervals, for example, or may be provided at a specific position so that the optical sensor unit 9 is arranged at a place where measurement is desired. Alternatively, it may be provided at any other position. The devices provided at each measurement point 2 constitute a node 15.

  The optical switch 8 is a 1 × 2 type optical switch having one port 8a on the upstream side and two ports 8b and 8c on the downstream side. The optical fiber trunk line 1 is connected to the upstream port 8a and the downstream first port 8b, and the optical fiber branch line 7 is connected to the downstream second port 8c. The optical fiber branch line 7 is formed by one optical fiber. The optical fiber branch line 7 has a length sufficient to install the optical sensor unit 9 at a desired position when the optical fiber trunk line 1 is installed at a desired position.

  In the present embodiment, as the optical switch 8, a self-holding optical switch that maintains its switching position even when no power is supplied is used. When receiving a switching command from the communication control unit 12, the switching drive unit 8d of the optical switch 8 is activated from the sleep state and switches the optical path. That is, it is in a sleep state until it receives a switching command from the communication control unit 12, and is activated upon receiving a switching command to the main line side.

  The optical sensor unit 9 is shown in FIG. The optical sensor unit 9 is, for example, universalized, and includes, for example, a sensor body 16, a signal conversion unit 17, and a light modulation element 18. As the sensor body 16, for example, a temperature sensor, a vibration sensor, an electric field / magnetic field sensor, a water immersion sensor, a fire sensor, or the like can be used, and one or a plurality of sensors are appropriately used depending on the purpose and application of measurement. . The output (sensor information) of the sensor body 16 is supplied to the signal converter 17.

  Among the sensor bodies 16 to be used, the sensor body 16 that receives power supply from the power supply 13 sends a state change detection signal to the communication control unit 12 when the measured value changes beyond a preset range. Output.

  The signal converter 17 converts the detection signal from the sensor body 16 into a light modulation signal, and supplies the converted signal to the light modulation element 18. When a plurality of sensor bodies 16 are provided, sensor information from the plurality of sensor bodies 16 is collectively converted into one type of modulation signal. As the type of the modulation signal, one corresponding to the function of the light modulation element 18 is used. For example, when the light modulation element 18 modulates the reflected light 5 by vibration, a signal for vibrating the light modulation element 18 is used as a modulation signal.

  The light modulation element 18 reflects and outputs the input light while modulating it, and is connected to the tip of the optical fiber branch line 7. The outgoing light 3 input from the optical fiber branch line 7 to the light modulation element 18 is reflected by the reflection film 18 a provided on the opposite side of the optical fiber branch line 7 and returns to the optical fiber branch line 7. When the transmitted light 3 and the reflected light 5 pass through the light modulation element 18, the light 3 is modulated by receiving a stimulus from the light modulation element 18, and the sensor information measured by the sensor body 16 is superimposed. The light modulation element 18 of this embodiment modulates light by vibration, vibrates in response to a modulation signal from the signal conversion unit 17, and modulates the transmitted light 3 and its reflected light 5.

  The first light detection means 10 and the second light detection means 11 detect the presence / absence of communication by the node 15 at another measurement point 2. The first light detection means 10 and the second light detection means 11 are connected to the optical fiber trunk line 1 via, for example, an optical coupler 19. The optical coupler 19 is a two-input two-output type optical coupler having two ports 19a, 19b, 19c, and 19d on the upstream side and the downstream side, respectively. The optical fiber trunk line 1 is connected to the upstream transmission port 19a and the downstream transmission port 19c, and the branch line 20 is connected to the upstream branch port 19b and the downstream branch port 19d. . The branch line 20 is formed of an optical fiber. The first photodetecting means 10 is a terminal of the branch line 20 connected to the downstream branching port 19d, and the second photodetecting means 11 is a terminal of the branching line 20 connected to the upstream branching port 19b. Are provided respectively. The first light detection means 10 and the second light detection means 11 are, for example, optical / electrical converters, and the detection signals are supplied to the communication control unit 12.

  The branching characteristic of the optical coupler 19 is such that the signal strength on the branch side is significantly smaller than the signal strength on the transmission side, and the attenuation of the transmitted light 3 and the reflected light 5 transmitted through the optical fiber trunk line 1 is suppressed as much as possible. A large number of measurement points 2 can be installed. The branching characteristic of the optical coupler 19 is, for example, transmitted light: branched light = 95: 5. However, the branching characteristics are not limited to this ratio, and can be appropriately set in consideration of the number of measurement points 2 and the length of the optical fiber trunk line 1.

  The communication control unit 12 determines whether or not a predetermined transmittable condition C2 is satisfied when a predetermined transmission request condition C1 is satisfied, and when the transmittable condition C2 is satisfied Perform communication processing. The communication control unit 12 is configured by a small computer, and performs predetermined communication processing according to a program installed in advance. The input side of the communication control unit 12 is connected to the light sensor unit 9, the first light detection unit 10, and the second light detection unit 11, and the output side includes the light sensor unit 9 and the switching drive unit 8d of the optical switch 8. Is connected.

  The transmission request condition C1 is satisfied at a predetermined time or when a state change is detected by the optical sensor unit 9 (or condition). The communication control unit 12 has a timer circuit and always recognizes the current time. When the preset transmission time is reached, the transmission request condition C1 is satisfied and communication is performed. Thereby, periodic measurement is performed. When the state change detection signal is supplied from the optical sensor unit 9, the transmission request condition C1 is satisfied and communication is performed. The communication control unit 12 constantly monitors the presence or absence of a state change detection signal from the optical sensor unit 9. Thereby, it measures as needed other than a fixed time.

  The communication control unit 12 is activated from the sleep state by using the transmission request condition C1 as a trigger. That is, the communication control unit 12 shifts to a sleep state in which a circuit other than the timer circuit and a circuit that detects a state change is suspended in a standby state in which communication is not performed, and power consumption is suppressed.

  The transmittable condition C2 is satisfied when the first light detection means 10 detects the transmitted light 3 and the second light detection means 11 does not detect the reflected light 5 (and condition). When the transmission request condition C1 is satisfied, the communication control unit 12 is activated from the sleep state, monitors the presence / absence of detection signals from the first and second light detection means 10 and 11, and determines the transmission possible condition C2. Start.

  A communication process performed by the communication control unit 12 is shown in FIG. When the transmission request condition C1 (step S41) is satisfied and the transmission enable condition C2 (step S42) is also satisfied, the communication control unit 12 activates the switching drive unit 8d of the optical switch 8 to move the optical switch 8 from the main line side. Switch to the branch line side (step S43). Specifically, a switching command to the branch line side is transmitted to the switching drive unit 8d of the optical switch 8. Thereby, the optical switch 8 is switched to the branch line side, and the transmitted light 3 from the transmitter 4 is transmitted to the branch line side. Thereafter, when the optical sensor unit 9 is in the sleep state, the communication control unit 12 activates the optical sensor unit 9 (step S44). Specifically, an activation command is transmitted to the sensor main body 16 and the signal conversion unit 17 of the optical sensor unit 9. Then, after a sufficient time t has passed for the reflected light 5 modulated by the optical sensor unit 9 and superimposed with the sensor information to return to the optical fiber main line 1, the optical switch 8 is switched to the main line side (step S46). . Specifically, a command to switch to the main line side is transmitted to the switching drive unit 8d of the optical switch 8. Thereby, the communication of the node 15 of the other measurement point 2 becomes possible. Note that the communication control unit 12 has a timer circuit, and this timer circuit measures the passage of time t. This time t is determined in advance and is stored in the storage unit of the communication control unit 12. Thereafter, the communication control unit 12 shifts the optical sensor unit 9 and the switching drive unit 8d of the optical switch 8 to the sleep state (step S47), and then the communication control unit 12 itself shifts to the sleep state and the transmission request condition C1 is set. Wait until it is satisfied (step S41).

  The power source 13 is a battery, for example, and can be replaced periodically or appropriately. However, it is not necessarily limited to a battery. For example, when there is a power source 13 such as a commercial power source 13 in the vicinity of the measurement point 2, this can be used. In the present embodiment, the power supply 13 supplies power to the communication control unit 12, the switching drive unit 8 d of the optical switch 8, the sensor main body 16 and the signal conversion unit 17 of the optical sensor unit 9. However, the power supply destination is not limited to these. For example, when the first light detection means 10 and the second light detection means 11 require power, they may be supplied with power. . For example, when the sensor main body 16 of the optical sensor unit 9 does not require electric power, it is not necessary to supply electric power thereto.

  Next, the operation of the multipoint optical fiber sensor device will be described.

  In an initial state immediately after the multipoint optical fiber sensor device is installed, the optical switch 8 is switched to the main line side. That is, the optical switches 8 at all the measurement points 2 (nodes 15) are switched to the main line side. When the transmission light 3 is transmitted from the transmitter 4 to the optical fiber main line 1 in this state, the transmission light 3 passes through the optical switch 8 and the optical coupler 19 at each measurement point 2 and is transmitted to the farthest end. Since reflection does not occur at the farthest end of the optical fiber trunk line 1, no reflected light 5 is generated (or, since the reflectance is negligibly lower than that of the optical sensor unit 9, it can be considered that the reflected light 5 is not generated).

  Here, for example, the node 15 at the second measurement point 2 from the upstream side will be described as an example. The processing at the node 15 at the other measurement points 2 is the same. First, the communication control unit 12 repeatedly executes step S41 of FIG. 4 and waits until the transmission request condition C1 is satisfied. The transmission request condition C1 is satisfied by the arrival of a predetermined time (in the case of regular measurement) or the reception of a state detection signal from the optical sensor unit 9 (in the case of measurement other than the regular measurement).

  When the transmission request condition C1 is satisfied, the process proceeds to step S42, and the communication control unit 12 determines whether or not the transmission enable condition C2 is satisfied. If the transmittable condition C2 is not satisfied, the communication control unit 12 repeatedly executes step S42 and waits until the transmittable condition C2 is satisfied. Based on the detection signals from the first light detection means 10 and the second light detection means 11, the communication control unit 12 determines whether or not the transmission possible condition C2 is satisfied.

  If communication is being performed at the measurement point 2 upstream of the measurement point 2, the upstream optical switch 8 is switched to the branch line side, and the first light at the measurement point 2 is switched. Since the detection means 10 cannot detect the transmitted light 3 from the transmitter 4, it is turned off. Further, when communication is performed at the measurement point 2 downstream of the measurement point 2, the reflected light 5 related to the communication is detected, so the second light detection means 11 is turned on. That is, when at least one of the first light detection means 10: off and the second light detection means 11: on is satisfied, communication is performed at the node 15 of the other measurement point 2. Therefore, the communication control unit 12 repeatedly executes step S42 and waits for the communication of the node 15 at another measurement point 2 to end.

  On the other hand, if communication is not performed at the measurement point 2 upstream of the measurement point 2, all the upstream optical switches 8 are switched to the main line side, so the first light detection at the measurement point 2 is performed. The means 10 detects the transmitted light 3 and is turned on. If communication is not performed at the measurement point 2 on the downstream side of the measurement point 2, the second light detection unit 11 is turned off because the reflected light 5 cannot be detected. That is, when both the first light detection means 10: on and the second light detection means 11: off are satisfied, communication is not performed at the other measurement points 2. When both of these are satisfied, the transmittable condition C2 is satisfied, and the communication control unit 12 starts communication. Thereby, the collision of communication with the node 15 of the other measurement point 2 is avoided.

  Note that the node 15 of the measurement point 2 arranged on the most downstream side can communicate if communication is not performed at the measurement point 2 on the upstream side. Therefore, it is sufficient to determine whether communication is possible based only on the signal from the first light detection means 10, but since the reflected light 5 from the downstream side does not originally exist, the second light detection means 11 is always off. Therefore, it is only necessary to determine whether or not both of the first light detection means 10: on and the second light detection means 11: off are satisfied as in the case of the other measurement points 2. It is possible to determine whether or not the transmittable condition C2 is satisfied in the same manner as described above.

  Further, the node 15 of the measurement point 2 arranged on the most upstream side can communicate if communication is not performed at the measurement point 2 on the downstream side. Accordingly, it is sufficient to determine whether communication is possible based only on the signal from the second light detection means 11, but since the first light detection means 10 is always on because the transmitted light 3 can always be detected, eventually, other It is only necessary to determine whether both of the first light detection means 10: on and the second light detection means 11: off are satisfied as in the measurement point 2, and transmission is possible in the same manner as the other measurement points 2. It can be determined whether or not the condition C2 is satisfied.

  In the next step S43, the communication control unit 12 transmits a switching signal to the branch line side to the switching drive unit 8d of the optical switch 8. Thereby, the switching drive unit 8d of the optical switch 8 is activated from the sleep state, and switches the optical switch 8 to the branch line side. As a result, communication at the node 15 is started.

  In the next step S44, if the optical sensor unit 9 is in the sleep state, it is activated. Now, in step S41, when the transmission request condition C1 is satisfied by receiving the state change detection signal from the optical sensor unit 9, the optical sensor unit 9 is already activated, but a predetermined time has arrived. When the transmission request condition C1 is satisfied, the optical sensor unit 9 is in the sleep state. Therefore, in this case, the communication control unit 12 activates the sensor body 16 and the signal conversion unit 17 of the optical sensor unit 9.

  The outgoing light 3 is taken into the optical fiber branch line 7 from the optical fiber trunk line 1 by switching the optical switch 8 to the branch line side. Then, the light is incident on the light modulation element 18 of the optical sensor unit 9, reflected while being modulated light including sensor information, and returned as reflected light 5 from the optical fiber trunk 1 to the optical fiber trunk 1. The reflected light 5 returned to the optical fiber main line 1 is received by the receiver 6 via the optical circulator 21. In this way, communication by the node 15 is performed.

  The communication control unit 12 waits for a sufficient time t for the reflected light 5 on which the sensor information is superimposed to return to the optical fiber main line 1, and then issues a switching command to the switching drive unit 8d of the optical switch 8 to the main line side. Transmit (step S46). As a result, the optical switch 8 is switched to the main line side, the communication of the node 15 is finished, and after the reflected light 5 is received by the receiver 6, the communication by the node 15 of another measurement point 2 becomes possible. .

  Thereafter, the communication control unit 12 proceeds to step S47, and the sensor main body 16 and the signal conversion unit 17 of the optical sensor unit 9 and the switching drive unit 8d of the optical switch 8 are in the sleep state (the state where the power supply from the power source 13 is minimized). ), The process returns to step S41 to wait for the transmission request condition C1 to be satisfied again.

  Since the discrimination signal I is superimposed on the reflected light 5 received by the receiver 6, the propagation time of the reflected light 5, that is, the time until it is transmitted from the transmitter 4 and received by the receiver 6 is obtained. Based on the obtained propagation time, it is possible to determine from which measurement point 2 the reflected light 5 is.

  Moreover, since the reflected light 5 received by the receiver 6 includes sensor information by the optical sensor unit 9, the measurement value by the optical sensor unit 9 can be detected.

  In this multi-point type optical fiber sensor device, since the optical sensor unit 9 is connected to one optical fiber trunk line 1 via the optical switch 8, measurement is performed at multiple points using one optical fiber. be able to. Therefore, the configuration can be simplified as compared with the case where a plurality of optical fibers are used, and the apparatus can be prevented from becoming large.

  Further, since the communication control unit 12 of each node 15 performs communication by determining the transmittable condition C2 when the transmission request condition C1 of the sensor information is satisfied, the communication is performed in response to a request from the node 15 side. Can do. At this time, since each node 15 performs communication after confirming the empty state of the optical fiber trunk line 1 based on the transmission enable condition C2, even if only one optical fiber is used, a communication collision is avoided. The sensor information measured by the optical sensor unit 9 can be reliably sent to the receiver 6.

  Furthermore, since the optical switch 8 that can suppress the attenuation of transmitted light as much as possible is used for the connection of the optical sensor unit 9, the transmitted light is not significantly attenuated as in the case of using an optical coupler, There is no need to change the wavelength characteristics for each measurement point as in the case of using a WDM coupler. Therefore, many measurement points 2 can be provided.

  The multi-point optical fiber sensor device of the present invention uses the power supply 13, but when not required, the communication control unit 12, the switching drive unit 8d of the optical switch 8, the sensor body 16 of the optical sensor unit 9, and the signal conversion. Since the unit 17 has shifted to the sleep state, power consumption can be suppressed and operation can be performed for a long time. Further, the power source 13 having a small capacity can be used, and the apparatus can be easily downsized.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention.

  For example, in the above description, the transmission request condition C1 is satisfied at a predetermined time or when a state change is detected by the optical sensor unit 9, but the present invention is not necessarily limited to this. Alternatively, instead of either one or both of these, for example, the predetermined time may be satisfied after the previous transmission. In the case of this condition, measurement can be performed every predetermined time. The elapse of the predetermined time is measured using a timer circuit provided in the communication control unit 12.

  In the above description, the discrimination signal I is superimposed on the transmission light 3 transmitted from the transmitter 4. However, the reflection from any measurement point 2 can be performed without superimposing the discrimination signal I on the transmission light 3. When the light 5 can be specified, for example, when the optical sensor unit 9 can superimpose a signal for identifying the optical sensor unit 9, the discrimination signal I does not have to be superimposed on the transmitted light 3.

  In the above description, except when transmission processing is performed, the optical sensor unit 9 and the optical switch 8 are set in the sleep state to reduce power consumption and prevent the battery from running out. However, the configuration is not limited to this. For example, when a battery with a large capacity or a commercial power supply 13 is used as the power source 13 and it is not necessary to cause the battery to run out, the optical sensor unit 9 and the optical switch 8 are always started without going into the sleep state. It may be in a state. In this case, quick operation is possible.

  In the above description, the optical sensor unit 9 modulates the transmitted light 3 and its reflected light 5 by the light modulation element 18, but is not necessarily limited to this configuration, for example, the optical fiber branch line 7. Alternatively, the tip portion may be used as the optical sensor unit 9. In this case, the transmitted light 3 is reflected by the reflector provided on the distal end surface of the optical fiber branch line 7 and returns to the optical fiber main line 1. For example, when detecting the vibration of the measurement object, the transmission light 3 and the reflected light transmitted through the tip portion of the optical fiber branch line 7 are transmitted by transmitting the vibration of the measurement object to the tip portion of the optical fiber branch line 7. The light 5 can be modulated.

  In the above description, a self-holding type optical switch 8 is used. However, the optical switch 8 is not necessarily limited to a self-holding type optical switch. An optical switch or the like of the type that holds the switching position in response to the supply of power and returns the position by a spring force or the like when the power supply is cut off may be used. In this case, it is preferable that the main line side is set at the return position and the power supply is activated only when communication is performed.

DESCRIPTION OF SYMBOLS 1 Optical fiber trunk 2 Measurement point 1a Upstream end of optical fiber trunk 1 3 Transmitted light 4 Transmitter 5 Reflected light 6 Receiver 7 Optical fiber branch line 8 Optical switch 9 Optical sensor part 10 1st optical detection means 11 2nd Light detection means 12 Communication control unit 13 Power supply

Claims (6)

  A plurality of measurement points are provided at intervals in one optical fiber main line, and a transmitter for transmitting outgoing light to the optical fiber main line and a receiver for receiving reflected light from the measurement point are provided. In the point-type optical fiber sensor device, the transmitter transmits the transmitted light regardless of a transmission request from the measurement point side, and one optical fiber from the optical fiber trunk line is connected to the measurement point. An optical switch that branches the branch line and is initially switched to the trunk line side, a reflective optical sensor unit provided at the tip of the optical fiber branch line, and the transmission that travels down the optical fiber trunk line A first light detecting means for detecting light, a second light detecting means for detecting the reflected light transmitted in the upward direction on the optical fiber trunk line, and when a transmission request condition of sensor information is satisfied A communication control unit that switches the optical switch to the branch line side when one light detection unit detects the transmitted light and the second light detection unit does not detect the reflected light; and at least the communication control unit And a power supply for supplying power to the optical switch, and the communication control unit switches the optical switch to the main line side after the reflected light from the optical sensor unit returns to the optical fiber main line. A multi-point optical fiber sensor device.   The multipoint optical fiber sensor device according to claim 1, wherein a signal for distinguishing a reflection position is superimposed on the transmitted light.   2. The multipoint optical fiber sensor device according to claim 1, wherein the transmission request condition is satisfied at a predetermined time or when a state change is detected by the optical sensor unit.   The multipoint optical fiber sensor device according to claim 1, wherein the communication control unit and the optical switch shift to a sleep state except when communication is performed.   A plurality of measurement points are provided on one optical fiber trunk line, and when the transmission request condition is satisfied at the node of the measurement point, the communication state of the optical fiber trunk line is checked and communication is performed at another measurement point. A node communication control method for a multipoint optical fiber sensor device, wherein communication with an information aggregating station is performed when it is determined that there is not. The node detects light transmitted from the information aggregation station and determines that communication is not performed at another measurement point when reflected light from a node at a downstream measurement point cannot be detected. A node communication control method for a multipoint optical fiber sensor device according to claim 5.

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