JP2008217407A - Boundary sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a boundary sensor installable over a wide range and capable of easily specifying a passage position at low cost. <P>SOLUTION: The boundary sensor 1 is provided with an elastically deformable sensor main body 2 having elastomer and spherical conductive filler, which is mixed in a substantially single-particle state with a high fill factor in the elastomer, and increases electric resistance along with increase of a deformation quantity, and an electrode 3 connected to the sensor main body 2 and capable of outputting the electric resistance. The boundary sensor 1 is installed outdoors in the vicinity of a boundary, across which passage without permission is prohibited. The boundary sensor 1 can detects passage across the boundary based on change in the electric resistance due to deformation of the sensor main body 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a boundary sensor that can detect, for example, illegal entry into a restricted access area.

For example, in important security facilities such as a power plant, a fuel storage base, a military base, etc., it is necessary to restrict access from outside over a wide range. In order to prevent such illegal entry into the restricted area, an intrusion sensor, a monitoring camera, and the like are installed on a fence or the like that divides the restricted area. As an intrusion sensor, an infrared sensor, a vibration sensor, an optical fiber sensor, etc. are known (for example, refer to patent documents 1 to 3).
JP-A-6-251264 JP-A 63-40068 JP-A-3-53400

  For example, in the case of an infrared sensor or a vibration sensor, the detectable range is narrow. For this reason, in order to monitor a wide range, it is necessary to install many sensors. In addition, there are many malfunctions due to small animals such as birds and wind. On the other hand, according to the optical fiber sensor, it is relatively easy to route in a wide area, but it is difficult to identify the intrusion site. If it is going to identify an intrusion location, the monitoring range must be divided and an optical fiber sensor must be arranged for every division. In this case, a light emitting source and a light receiving / receiving source are required for each optical fiber sensor, which is costly.

  This invention is made | formed in view of such a situation, and makes it a subject to provide the boundary sensor which can be installed in a wide range and can specify a passage location easily.

  (1) The boundary sensor of the present invention has an elastomer and a spherical conductive filler blended in the elastomer in a substantially single particle state with a high filling rate, and the electrical resistance increases as the deformation amount increases. An elastically deformable sensor body that increases, and an electrode that is connected to the sensor body and that can output the electrical resistance, and is disposed near a boundary where unauthorized passage is prohibited outdoors, The passage of the boundary can be detected from a change in electrical resistance based on deformation of the sensor body (corresponding to claim 1).

  Here, the “boundary where unauthorized passage is prohibited” includes the boundary between the area where unauthorized entry is prohibited and the outside (hereinafter referred to as “intrusion prohibited boundary”), and unauthorized escape. This includes both areas where bans are prohibited and boundaries with the outside (hereinafter referred to as “prohibited boundaries”). Examples of the intrusion prohibition boundaries include boundaries that demarcate airport runways, various managed areas, in addition to the important security facilities as described above. On the other hand, the boundary for escaping is a boundary that divides prisons and the like. In other words, the boundary sensor of the present invention is disposed in the vicinity of a boundary that divides a predetermined area where access is restricted (hereinafter referred to as “restricted area” as appropriate).

  For example, when a fence, a fence, or the like is installed at the boundary that divides the restricted area, the intruder attempts to enter the restricted area by climbing or damaging the fence, the fence, or the like. When the boundary sensor according to the present invention is arranged on the fence or the fence, the sensor main body is deformed by the above action of the intruder. Here, the electrical resistance of the sensor body increases as the amount of deformation increases. Thus, according to the boundary sensor of the present invention, an attempt to enter the restricted area can be detected based on an increase in electrical resistance due to deformation of the sensor body. Note that “electric resistance can be output” means that electric resistance can be output directly or indirectly. That is, not only the case where the electrical resistance is directly output from the electrode but also the case where the other electrical quantity related to the electrical resistance such as voltage or current is output.

  In the boundary sensor of the present invention, the sensor body is elastically deformable and includes an elastomer and a spherical conductive filler. In this specification, “elastomer” includes rubber and thermoplastic elastomer. The conductive filler is blended in the elastomer in a substantially single particle state and with a high filling rate. Here, the “substantially single particle state” means that 50% by weight or more when the total weight of the conductive filler is 100% by weight exists not in the form of aggregated secondary particles but in the form of single primary particles. It means that Further, “high filling rate” means that the conductive filler is blended in a state close to closest packing.

  As described above, when the conductive filler is blended in a substantially single particle state and at a high filling rate, a three-dimensional conductive path is formed by contact between the conductive fillers via the elastomer component. Therefore, the sensor body in the boundary sensor of the present invention (hereinafter referred to as “sensor body in the present invention” as appropriate) is in a state where no load is applied (hereinafter referred to as “no-load state” as appropriate), in other words, deformation In a natural state that is not, it has high conductivity. Note that “elastic deformation” in this specification includes all deformation due to compression, extension, bending, and the like.

  For example, a conventional pressure-sensitive conductive resin has a large electric resistance in an uncompressed state, and the electric resistance decreases when deformed by compression. This can be explained from the configuration of the pressure-sensitive conductive resin as follows. That is, the pressure sensitive conductive resin is composed of a resin and a conductive filler blended in the resin. Here, the filling rate of the conductive filler is low. For this reason, the conductive fillers are separated from each other in a no-load state. That is, in the no-load state, the electric resistance of the pressure sensitive conductive resin is large. On the other hand, when a load is applied and the pressure-sensitive conductive resin is deformed, the conductive fillers come into contact with each other to form a one-dimensional conductive path. This reduces the electrical resistance.

  On the other hand, the electrical resistance of the sensor body according to the present invention increases as the amount of deformation increases. The reason is considered as follows. FIG. 1 and FIG. 2 show changes in the conductive path of the sensor body according to the present invention before and after applying a load as a model. However, what is shown in FIGS. 1 and 2 is an example of the sensor main body, and the sensor main body, the shape and material of the conductive filler in the present invention are not limited at all.

  As shown in FIG. 1, in the sensor main body 100, most of the conductive fillers 102 are present in the state of primary particles in the elastomer 101. Moreover, the filling rate of the conductive filler 102 is high, and it is blended in a state close to closest packing. Thereby, in a no-load state, a three-dimensional conductive path P is formed in the sensor body 100 by the conductive filler 102. Therefore, in the no-load state, the electrical resistance of the sensor body 100 is small. On the other hand, as shown in FIG. 2, when a load is applied to the sensor main body 100, the sensor main body 100 is deformed (the dotted line frame in FIG. 2 indicates the no-load state in FIG. 1). Here, since the conductive filler 102 is blended in a state close to closest packing, there is almost no space where the conductive filler 102 can move. Therefore, when the sensor body 100 is deformed, the conductive fillers 102 repel each other, and the contact state between the conductive fillers 102 changes. As a result, the three-dimensional conductive path P collapses and the electrical resistance increases.

  The boundary sensor of the present invention having such a sensor main body passes through the intrusion prohibition boundary and the escape prohibition boundary (restricted area) based on an increase in electrical resistance due to various deformations such as compression, expansion, and bending generated in the sensor main body. Intrusion and escape from restricted areas). In addition, since the boundary sensor of the present invention performs detection based on an increase in electrical resistance due to deformation of the sensor body, it is less likely to malfunction due to small vibrations that are not accompanied by deformation of the sensor body.

  The sensor body uses an elastomer as a base material. For this reason, the boundary sensor of this invention is excellent in workability, and has a high freedom degree of shape design. Therefore, it is possible to route in a wide range regardless of the length or shape of the placement location. In addition, fine sensing is possible by adjusting the number and arrangement of electrodes connected to the sensor body. That is, the intrusion location can be easily identified by simply arranging the electrodes for each predetermined section.

  In the boundary sensor of the present invention, the electric resistance value in the no-load state can be set within a predetermined range by adjusting the type of the elastomer and the conductive filler, the filling rate of the conductive filler, and the like. For this reason, the range of the deformation amount that can be detected, that is, the detection range can be increased. In addition, since the increase behavior of the electric resistance with respect to the deformation amount can be adjusted, a desired response sensitivity can be realized.

  Moreover, the boundary sensor of the present invention has high conductivity in a no-load state. That is, the boundary sensor of the present invention is in a conductive state in a no-load state. For this reason, in a no-load state, operation diagnosis is easier as compared with a sensor having low conductivity (for example, a sensor using a conventional pressure-sensitive conductive resin). That is, in the case of a sensor having low conductivity in a no-load state, it is difficult to determine whether the sensor is normal or abnormal (for example, whether a circuit is disconnected) in the no-load state. For this reason, it is necessary to dare to apply a relatively high voltage to a sensor having low conductivity. Alternatively, it is necessary to check the energized state by operating the sensor on a trial basis. Therefore, the operation diagnosis is complicated. In contrast, the boundary sensor of the present invention has high conductivity in a no-load state. For this reason, it is easy to discriminate between normal and abnormal in a no-load state. Therefore, operation diagnosis is easy.

  (2) Preferably, in the configuration of (1) above, a boundary partition member that prohibits unauthorized passage is disposed at the boundary, and the boundary partition member may be disposed. Correspondence).

  Usually, a boundary partition member such as a fence or a fence is arranged at the boundary that partitions the restricted area in order to prohibit unauthorized passage. Therefore, when trying to pass the boundary illegally, it is assumed that actions such as climbing, deforming, and cutting the boundary partition member are performed. Therefore, according to this structure, the said action can be detected by arrange | positioning the boundary sensor of this invention to the existing boundary partition member. That is, illegal passage of the boundary can be detected at an early stage.

  (3) Preferably, in the configuration of (2) above, the sensor body may have a configuration in which the electrical resistance increases as the temperature rises (corresponding to claim 3).

  According to the sensor main body of the present invention, the above-described three-dimensional conductive path P collapses due to the expansion of the elastomer at a predetermined temperature or higher. For this reason, electrical resistance increases above a predetermined temperature. Therefore, for example, when the boundary partition member breaks with a rapid temperature change, such as when the boundary partition member is burned out by a burner, the electrical resistance increases due to the temperature rise in addition to the deformation of the sensor body. Thereby, passage of the boundary which divides a restriction area can be detected earlier and reliably.

  (4) Preferably, in the configuration of (1) above, the configuration may be embedded in the ground near the boundary (corresponding to claim 4). According to this configuration, when an intruder or the like approaches the detection target boundary, a load is applied to the embedded boundary sensor of the present invention due to the weight of the intruder. As a result, the sensor body is deformed and the electrical resistance is increased. Therefore, according to this configuration, it is possible to detect passage of a boundary that divides a restricted area regardless of the presence or absence of a boundary partition member such as a fence. Further, by embedding in the ground, there is little possibility that an intruder or the like will know the presence of the boundary sensor of the present invention.

  (5) Preferably, in the configuration of any one of the above (1) to (4), the sensor main body may be further provided with a protection member that covers the sensor main body so that the sensor main body is not exposed. Correspondence). By covering the sensor body with a protective member, it is possible to ensure the waterproofness, insulation, etc. of the sensor body. Moreover, since the sensor main body is cut off from the external environment, deterioration of the sensor main body is suppressed.

  (6) Preferably, in any one of the configurations (1) to (5), the sensor body has a long shape, and a plurality of the electrodes are arranged along the longitudinal direction of the sensor body. (Corresponding to claim 6). According to this structure, since the sensor main body is exhibiting the elongate shape, it can route continuously over a long distance. Further, finer sensing is possible by arranging the electrodes at predetermined intervals in the longitudinal direction of the sensor body. Thereby, the passage location of an intruder etc. can be specified easily.

  (7) Preferably, in any one of the constitutions (1) to (6), the sensor body is made of an elastomer composition containing the elastomer and the conductive filler as essential components, In the percolation curve representing the relationship between the blending amount of the conductive filler and the electrical resistance, the blending amount (saturated volume fraction: φs) of the conductive filler at the second inflection point where the electrical resistance change is saturated is 35 vol% or more It is good to have a configuration (corresponding to claim 7).

  Generally, when an electrically conductive filler is mixed with an insulating elastomer to form an elastomer composition, the electrical resistance of the elastomer composition varies depending on the blending amount of the conductive filler. In FIG. 3, the relationship between the compounding quantity of an electroconductive filler and an electrical resistance in an elastomer composition is shown typically.

  As shown in FIG. 3, when the conductive filler 102 is mixed with the elastomer 101, the electrical resistance of the elastomer composition is almost the same as the electrical resistance of the elastomer 101 at first. However, when the blending amount of the conductive filler 102 reaches a certain volume fraction, the electric resistance rapidly decreases and an insulator-conductor transition occurs (first inflection point). A blending amount of the conductive filler 102 at the first inflection point is referred to as a critical volume fraction (φc). Further, when the conductive filler 102 is further mixed, from a certain volume fraction, the change in electrical resistance is reduced and the change in electrical resistance is saturated (second inflection point). The blending amount of the conductive filler 102 at the second inflection point is referred to as a saturated volume fraction (φs). Such a change in electrical resistance is called a percolation curve and is considered to be due to the formation of a conductive path P1 by the conductive filler 102 in the elastomer 101.

  For example, if the conductive filler aggregates and forms an aggregate due to the small particle size of the conductive filler or poor compatibility between the conductive filler and the elastomer, one-dimensional conductive A path is easily formed. In such a case, the critical volume fraction (φc) of the elastomer composition is relatively small, such as about 20 vol%. Similarly, the saturated volume fraction (φs) is also relatively small. In other words, when the critical volume fraction (φc) and the saturated volume fraction (φs) are small, the conductive filler hardly exists as primary particles, and secondary particles (aggregates) are easily formed. Therefore, in this case, it is difficult to blend a large amount of the conductive filler in the elastomer. That is, it is difficult to mix the conductive filler in a state close to closest packing. Further, when a large amount of a conductive filler having a small particle diameter is blended, the aggregated structure grows three-dimensionally, so that the change in conductivity with respect to deformation becomes poor.

  According to this configuration, the sensor body is made of an elastomer composition having a saturated volume fraction (φs) of 35 vol% or more. Since the saturated volume fraction (φs) is as large as 35 vol% or more, the conductive filler is stably present in a substantially single particle state in the elastomer. Therefore, the conductive filler can be blended in a state close to closest packing.

  (8) Preferably, in any one of the constitutions (1) to (7), the filling rate of the conductive filler is 30 vol% or more and 65 vol% or less when the total volume of the sensor body is 100 vol%. It is good to have a configuration (corresponding to claim 8).

  According to this configuration, the conductive filler is blended in the elastomer in a state close to closest packing. Therefore, a three-dimensional conductive path by the conductive filler is easily formed in the sensor body.

  (9) Preferably, in any one of the configurations (1) to (8), the conductive filler may be a carbon bead (corresponding to claim 9).

  Carbon beads have good conductivity and are relatively inexpensive. Moreover, since it has a substantially spherical shape, it can be blended at a high filling rate.

  (10) Preferably, in any one of the configurations (1) to (9), the conductive filler may have an average particle size of 0.05 μm or more and 100 μm or less (corresponding to claim 10). .

  According to this configuration, the conductive filler hardly aggregates and tends to exist in a primary particle state. In addition, an average particle diameter means the average particle diameter of the electroconductive filler which exists in the state of a primary particle.

  (11) Preferably, in any one of the constitutions (1) to (10), the elastomer is silicone rubber, ethylene-propylene copolymer rubber, natural rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer. It is good to set it as the structure containing 1 or more types chosen from rubber | gum and acrylic rubber (corresponding to claim 11).

  According to this configuration, the compatibility between the elastomer and the conductive filler is good. For this reason, it becomes easy for a conductive filler to exist in the state of a primary particle.

  Hereinafter, embodiments of the boundary sensor of the present invention will be described. First, an embodiment of the boundary sensor of the present invention will be described, and then a sensor main body constituting the boundary sensor of the present invention will be described in detail.

<Boundary sensor>
(1) First Embodiment First, the arrangement of the boundary sensor of this embodiment will be described. FIG. 4 shows a front view of a fence in which the boundary sensor of the present embodiment is arranged. As shown in FIG. 4, the fence 9 includes a column 90, an upper trunk edge 91, a lower trunk edge 92, and a wire mesh panel 93. The fence 9 is included in the boundary partition member of the present invention.

  The support 90 is made of steel and has a cylindrical shape. The support columns 90 are erected upward from the ground G with a predetermined interval. The upper trunk edge 91 is made of steel and has a cylindrical shape. The upper trunk edge 91 is installed in the left-right direction in the vicinity of the upper ends of the many columns 90. The lower trunk edge 92 is made of steel and has a cylindrical shape. The lower trunk edge 92 is installed in the left-right direction in the vicinity of the lower ends of the multiple columns 90.

  The metal mesh panel 93 has a long band shape and is made of a steel wire knitted in a rhombus net shape. The upper edge of the metal mesh panel 93 is attached to the upper body edge 91, and the lower edge is attached to the lower body edge 92. A gap between the upper trunk edge 91 and the lower trunk edge 92 is sealed by the metal mesh panel 93.

  The boundary sensor 1 has a linear shape. The boundary sensor 1 is installed in the left-right direction in the middle part of many pillars 90. The boundary sensor 1 is also attached to the wire mesh panel 93. The boundary sensors 1 are arranged in three upper and lower rows.

  The control device 8 is disposed in a house (not shown) separated from the fence 9. The control device 8 and the boundary sensor 1 are electrically connected. In addition, the control device 8 is also electrically connected to the alarm device 86 and the anemometer 87. The alarm device 86 is attached to the outdoor wall of the house. The anemometer 87 is attached to the upper end of the column 90.

  Next, the configuration of the boundary sensor 1 will be described. In the following, the boundary sensor 1 arranged in the middle of the three rows of boundary sensors 1 will be described. However, the configuration of the upper and lower boundary sensors 1 and the connection state with the control device 8 are the same as those of the middle boundary sensor 1. Therefore, explanation is omitted here.

  FIG. 5 is a perspective view of the vicinity of the boundary sensor 1 mounting portion in the support column 90. FIG. 6 shows a cross-sectional view of the boundary sensor 1 in the axial direction. For convenience of explanation, the column 90 is shown in FIG. As shown in FIGS. 5 and 6, the boundary sensor 1 includes a sensor body 2, an electrode 3, and a protective cover 4.

  The sensor body 2 has a long round bar shape extending in the left-right direction. The sensor body 2 is an elastomer composite material in which carbon beads (“Nika Beads (registered trademark) ICB0520” manufactured by Nippon Carbon Co., Ltd., average particle diameter of about 5 μm) are blended in EPDM (ethylene-propylene-diene terpolymer). Consists of. The filling rate of the carbon beads is 48 vol% when the volume of the sensor body 2 is 100 vol%. In the percolation curve of the elastomer composition in which carbon beads are mixed with EPDM, the critical volume fraction (φc) is 43 vol%, and the saturated volume fraction (φs) is 48 vol%.

  The protective cover 4 is made of an elastic elastomer and has a long cylindrical shape. The protective cover 4 covers the outer peripheral surface of the sensor body 2. For this reason, the sensor body 2 is blocked from the external environment. The protective cover 4 is fixed to the support column 90 with a bracket (not shown). The protective cover 4 is included in the protective member in the present invention.

  The electrode 3 is made of copper and has a strip shape. One end of the electrode 3 is embedded in the side peripheral surface of the sensor body 2. The other end of the electrode 3 penetrates the protective cover 4 and protrudes outside. A large number of electrodes 3 are arranged at each position where the boundary sensor 1 and the support column 90 intersect. The protruding end of the electrode 3 from the protective cover 4 reaches the inside of the column 90. The protruding end of the electrode 3 is connected to one end of the conducting wire 30. As shown in FIG. 4, the conducting wire 30 is routed inside the column 90 and inside the lower trunk edge 92. The other end of the conducting wire 30 is connected to the control device 8. For this reason, the sensor body 2 can output an electrical resistance value to the control device 8 at every interval between the adjacent electrodes 3.

  Next, the electrical configuration of the control device 8 will be described. FIG. 7 shows a block diagram of the control device 8. As shown in FIG. 7, the control device 8 includes a bridge circuit 80, an amplifier circuit 81, input circuits 82 a and 82 b, a calculation unit 83, a storage unit 84, and an output circuit 85.

  The sensor body 2 of the boundary sensor 1 includes resistors r1, r2, r3... Rn-2, rn-1, and rn. Each of these resistors r1 to rn corresponds to the interval between adjacent electrodes 3 (that is, the interval L1 between the columns 90 shown in FIG. 4).

  Resistors R <b> 1 to R <b> 3 are arranged in the bridge circuit 80. A Wheatstone bridge circuit is configured by the resistors R1 to R3 and the resistors r1 to rn of the sensor body 2. More specifically, the resistors r1 to rn are sequentially connected to the control device 8 while being switched from r1 → r2 → r3. Therefore, the Wheatstone bridge circuit is configured by the resistors R1 to R3 and any of the resistors r1 to rn (hereinafter referred to as “rk”). The voltage of the power source Vin (specifically, the internal power source of the control device 8) and the electric resistance values of the resistors R1 to R3 are each known. Therefore, the resistance rk of the sensor body 2 can be substantially measured by measuring the potential difference between the intermediate potential V1 between the resistor R2 and the resistor R3 and the intermediate potential V2 between the resistor rk and the resistor R1. .

  Intermediate potentials V 1 and V 2 are input to the amplifier circuit 81. The potential difference ΔV between the intermediate potentials V1 and V2 is amplified by the amplifier circuit 81 and input to the input circuit 82a. The potential difference ΔV is converted from analog to digital and becomes potential difference data. On the other hand, the wind force signal detected by the anemometer 87 is input to the input circuit 82b. The detection signal is converted from analog to digital into wind power data. These potential difference data and wind power data are transmitted to the calculation unit 83.

  The storage unit 84 is connected to the calculation unit 83. The storage unit 84 stores a map. FIG. 8 shows a schematic diagram of a map stored in the storage unit 84. As shown in FIG. 8, in the case of weak wind (wind power data ≦ wind power threshold th2), the potential difference threshold th10 is set low. On the other hand, in the case of strong wind (wind power data> wind power threshold th2), the potential difference threshold th11 is set high. As described above, the thresholds for potential difference th10 and th11 are set in two stages according to the wind power. The computing unit 83 compares the potential difference data and the wind power data with the map of FIG. The calculation unit 83 is connected to the alarm device 86 via the output circuit 85.

  Next, the movement of the boundary sensor 1 of the present embodiment will be described. First, the normal time will be described. In normal times, the sensor body 2 is in a natural state with no load. Here, as shown in FIG. 1, the conductive filler 102 is filled in a state close to closest packing. For this reason, many conductive paths P are formed in normal times. Therefore, the electrical resistance value of the sensor body 2 is the minimum value.

  As shown in FIG. 7, the potential difference ΔV between the intermediate potentials V1 and V2 is amplified by the amplifier circuit 81 and is always input to the arithmetic unit 83 via the input circuit 82a. On the other hand, the storage unit 84 stores the map shown in FIG. In the case of weak wind (wind power data ≦ wind power threshold th2), the calculation unit 83 compares the potential difference data with the potential difference threshold th10. In the case of strong wind (wind power data> wind power threshold th2), the potential difference data is compared with the potential difference threshold th11. Under normal conditions, the potential difference data is set so that the potential difference threshold th10 (when the wind is weak) or the potential difference data ≦ the potential difference threshold th11 (when the wind is strong).

  Next, an emergency will be described. When an intruder tries to break through the fence 9, an arbitrary part of the boundary sensor 1 is deformed (see FIG. 4). For this reason, an arbitrary part of the sensor body 2 is also deformed (see FIGS. 5 and 6). Therefore, the resistance rk corresponding to the deformed portion of the sensor body 2 is increased (see FIG. 7 above). More specifically, as shown in FIG. 2, the conductive fillers 102 repel each other. For this reason, the conductive path P collapses. Therefore, the resistance rk becomes larger than normal.

  When the resistance rk increases, the amount of voltage drop of the power source Vin when passing through the resistance rk increases accordingly. Therefore, the intermediate potential V2 is lower than that in the normal state. When the intermediate potential V2 becomes low and potential difference ΔV, that is, potential difference data> potential difference threshold th10 (when the wind is weak), or potential difference data> potential difference threshold th11 (when the wind is strong), the switching element of the output circuit 85 Is turned on. As a result, the alarm device 86 is activated.

  Next, the effect of the boundary sensor 1 of this embodiment is demonstrated. According to the boundary sensor 1 of the present embodiment, passage of the boundary due to cutting of the fence 9 or the like can be detected early and reliably. Further, according to experiments by the present inventors, when the sensor body 20 reaches about 80 ° C. or higher, the electrical resistance increases as the temperature rises. Therefore, for example, when the wire mesh panel 93 and the boundary sensor 1 are burned out by a burner or the like, in addition to an increase in electrical resistance due to deformation, the electrical resistance increases due to a rapid temperature rise, so an intruder can be brought in earlier. Can be detected.

  In addition, since the boundary sensor 1 performs detection based on an increase in electrical resistance due to deformation of the sensor body 2, it rarely malfunctions due to small vibrations that do not involve deformation of the sensor body 2. In addition to the potential difference data, detection is also performed using wind power data from the anemometer 87, so that malfunction due to wind is small and detection accuracy is high.

  The sensor body 20 has a long round bar shape extending in the left-right direction. For this reason, it can route continuously over a long distance. Moreover, since the electrode 3 is arrange | positioned for every support | pillar 90, the passage location, such as an intruder, can be specified easily. The sensor body 2 is covered with a protective cover 4. For this reason, the waterproofness and insulation of the sensor body 2 are high. Moreover, since the sensor main body 2 is not exposed, deterioration of the sensor main body 2 is suppressed.

  In the present embodiment, the presence or absence of intrusion is determined based on the potential difference data. For this reason, the time from the deformation of the sensor main body 2 to the operation of the alarm device 86 can be shortened as compared with the case where the determination is performed after the potential difference is once converted into the electric resistance. Moreover, since the boundary sensor 1 is always in an energized state, operation diagnosis can be easily performed.

(2) Second Embodiment The difference between the present embodiment and the first embodiment is that the boundary sensor is attached to the upper trunk edge. In addition, the sensor main body is fixed to the protective cover via a spacer. Therefore, only the differences will be described here.

  In FIG. 9, the perspective view of the boundary sensor attachment part vicinity of this embodiment in a support | pillar is shown. In addition, about the site | part corresponding to FIG. 5, it shows with the same code | symbol. FIG. 10 shows a cross-sectional view perpendicular to the axis of the boundary sensor. In addition, about the site | part corresponding to FIG. 6, it shows with the same code | symbol.

  As shown in FIGS. 9 and 10, the boundary sensor 1 of the present embodiment extends in the left-right direction along the upper surface of the upper trunk edge 91. The protective cover 4 of the boundary sensor 1 is attached to the upper trunk edge 91 via a bracket 910. Specifically, the bracket 910 includes a large hole 910a and a small hole 910b. An upper trunk edge 91 is inserted and fixed in the large hole 910a. The protective cover 4 is inserted and fixed in the small hole 910b. The brackets 910 are arranged at predetermined intervals along the axial direction of the protective cover 4.

  A gap is formed between the outer peripheral surface of the sensor body 2 and the inner peripheral surface of the protective cover 4. A ring-shaped spacer 5 is interposed in the gap. The spacers 5 are arranged at predetermined intervals along the axial direction of the sensor body 2.

  The boundary sensor 1 according to the present embodiment and the boundary sensor according to the first embodiment have the same functions and effects with respect to parts having the same configuration. Further, according to the boundary sensor 1 of the present embodiment, the boundary sensor 1 is arranged on the upper trunk edge 91. For this reason, it is possible to detect the intruder's climbing over the fence 9.

  Further, according to the boundary sensor 1 of the present embodiment, the spacer 5 is interposed between the sensor body 2 and the protective cover 4. For this reason, a gap is defined between the sensor body 2 and the protective cover 4 on the entire circumference. Therefore, there is little possibility that the sensor body 2 is deformed by a small animal such as a bird or wind.

(3) Third Embodiment A difference between the present embodiment and the second embodiment is that a conducting wire connecting the electrode and the control device is arranged in a gap between the sensor main body and the protective cover. Therefore, only the differences will be described here.

  In FIG. 11, the perspective view of the boundary sensor attachment part vicinity of this embodiment in a support | pillar is shown. In addition, about the site | part corresponding to FIG. 9, it shows with the same code | symbol. FIG. 12 is a cross-sectional view perpendicular to the axis of the boundary sensor. In addition, about the site | part corresponding to FIG. 10, it shows with the same code | symbol.

  As shown in FIGS. 11 and 12, a small hole 50 is formed in the spacer 5. The conducting wire 30 is inserted into the small hole 50. In FIG. 11, for convenience of explanation, the conducting wire 30 penetrates the upper portion of the spacer 5, but actually, the conducting wire 30 penetrates the lower portion of the spacer 5 as shown in FIG. 12.

  The conducting wire 30 is routed in the gap between the sensor body 2 and the protective cover 4. One end of the conducting wire 30 is connected to an electrode embedded in the sensor body 2 (an electrode (not shown) adjacent to the left side of the electrode 3 in FIG. 11). The other end of the conducting wire 30 is connected to a control device (not shown) through the inside of the support column 90.

  The boundary sensor 1 according to the present embodiment and the boundary sensor according to the second embodiment have the same functions and effects with respect to parts having the same configuration. Moreover, according to the boundary sensor 1 of this embodiment, the number of the support | pillars 90 which need the arrangement | positioning of the conducting wire 30 becomes a half with respect to 2nd embodiment. For this reason, it is easy to carry out the routing work and, in turn, the work of attaching the boundary sensor 1.

(4) Fourth Embodiment A difference between the present embodiment and the third embodiment is that a conducting wire connecting the electrode and the control device is routed along the outer peripheral surface of the protective cover. Therefore, only the differences will be described here.

  FIG. 13 shows a cross-sectional view in the direction perpendicular to the axis of the boundary sensor of the present embodiment. In addition, about the site | part corresponding to FIG. 12, it shows with the same code | symbol. As shown in FIG. 13, the conducting wire 30 is attached to the outer peripheral surface of the protective cover 4 by a restraining ring 40. A plurality of restraining rings 40 are arranged at predetermined intervals in the axial direction of the protective cover 4. The boundary sensor 1 according to the present embodiment and the boundary sensor according to the third embodiment have the same functions and effects.

(5) Fifth Embodiment The difference between this embodiment and the first embodiment is that the boundary sensor is embedded in the ground. Therefore, only the differences will be described here.

  First, the arrangement and configuration of the boundary sensor of this embodiment will be described. FIG. 14 is a cross-sectional perspective view of the boundary sensor of the present embodiment. FIG. 15 is a cross-sectional view in the short-side direction of the boundary sensor. As shown in FIGS. 14 and 15, an upper cushioning material 94, a boundary sensor 1 a, and a lower cushioning material 95 are arranged in the ground G from the top to the bottom. The upper cushioning material 94 and the lower cushioning material 95 are made of rubber and have a strip shape extending in the left-right direction. The boundary sensor 1 a is interposed between the upper cushioning material 94 and the lower cushioning material 95.

  The boundary sensor 1a includes a protective cover 4a, a sensor body 2a, an electrode 3a, and a substrate 7a. The protective cover 4a is made of an elastomer having elasticity and has a flat rectangular tube shape extending in the left-right direction. A substrate 7a, a sensor body 2a, and an electrode 3a are accommodated in the protective cover 4a. The board | substrate 7a is resin, Comprising: The strip | belt shape extended in the left-right direction is exhibited. The substrate 7a is disposed on the bottom surface inside the protective cover 4a. The sensor body 2a is made of an elastomer composite material similar to the sensor body of the first embodiment, and has a strip shape extending in the left-right direction. The sensor body 2a is fixed on the substrate 7a. The electrode 3a is made of copper and has a strip shape. The electrode 3a is interposed between the sensor body 2a and the substrate 7a. A large number of electrodes 3a are arranged at predetermined intervals along the longitudinal direction of the sensor body 2a.

  Next, the electrical configuration of the boundary sensor 1a of this embodiment will be described. FIG. 16 shows a wiring diagram (top view) of the boundary sensor of this embodiment. In FIG. 16, the upper cushioning material 94 and the protective cover 4a are omitted.

  As shown in FIG. 16, the boundary sensor 1 a is disposed between the fence F and the house H. The plurality of electrodes 3a and the control device 8a are each connected by a conducting wire 30a. The control device 8a is disposed in the house H. The configuration of the control device 8a is the same as that obtained by deleting the input circuit 82b for the anemometer 87 from the configuration of the control device 8 shown in FIG. Therefore, explanation is omitted here.

  Next, the movement of the boundary sensor 1a of this embodiment will be described. First, the normal time will be described. In normal times, the sensor body 2a is in a natural state with no load. Here, as shown in FIG. 1, the conductive filler 102 is filled in a state close to closest packing. For this reason, many conductive paths P are formed in normal times. Therefore, the electrical resistance value of the sensor body 2 is the minimum value. Next, an emergency will be described. FIG. 17 is a cross-sectional view in the short-side direction in the emergency of the boundary sensor of the present embodiment. When the intruder who has overcome the fence F in FIG. 16 passes the ground G on the boundary sensor 1a, the boundary sensor 1a sinks downward due to the weight of the intruder as shown in FIG. As shown in FIG. For this reason, the electrical resistance between the pair of electrodes 3a corresponding to the portion through which the intruder has passed increases. Therefore, the potential difference data input to the calculation unit of the control device 8a is increased. When the potential difference data becomes larger than the potential difference threshold value stored in the storage unit of the control device 8a, the alarm device 86a is activated.

  Next, the effect of the boundary sensor 1a of this embodiment is demonstrated. The boundary sensor 1a according to the present embodiment has the same operational effects as the boundary sensor according to the first embodiment with respect to parts having the same configuration. In addition, the boundary sensor 1a of the present embodiment has a strip shape having a plane substantially parallel to the surface of the ground G. For this reason, intruders who pass over the ground G can be detected in a relatively wide range.

(6) Sixth Embodiment The difference between this embodiment and the fifth embodiment is that the boundary sensor is arranged on the upper surface of the block cage. Therefore, only the differences will be described here. FIG. 18 shows a cross-sectional perspective view of the boundary sensor of the present embodiment. As shown in FIG. 18, the block ridge B extends in the left-right direction. The boundary sensor 1b is disposed on the upper surface of the block cage B. The block ridge B is included in the boundary partition member of the present invention.

  The boundary sensor 1b includes a protective cover 4b, a sensor body 2b, an electrode 3b, and a substrate 7b. The protective cover 4b is made of an elastic elastomer and has a flat rectangular tube shape extending in the left-right direction. A substrate 7b, a sensor body 2b, and an electrode 3b are accommodated in the protective cover 4b. The substrate 7b is made of resin and has a strip shape extending in the left-right direction. The substrate 7b is disposed on the bottom surface inside the protective cover 4b. The sensor body 2b is made of an elastomer composite material similar to the sensor body of the first embodiment, and has a strip shape extending in the left-right direction. The sensor body 2b is fixed on the substrate 7b. The electrode 3b is made of copper and has a strip shape. The electrode 3b is interposed between the sensor body 2b and the substrate 7b. A large number of electrodes 3b are arranged at predetermined intervals along the longitudinal direction of the sensor body 2b.

  The boundary sensor 1b according to the present embodiment has the same effects as the boundary sensor according to the fifth embodiment with respect to the parts having the same configuration. Further, according to the boundary sensor 1b of the present embodiment, an intruder trying to get over the block fence B can be detected.

(7) Others The embodiments of the boundary sensor of the present invention have been described above. However, the embodiment is not particularly limited to the above embodiment. Various modifications and improvements that can be made by those skilled in the art are also possible.

  For example, the location of the boundary sensor of the present invention is not limited to the above embodiment (fence, underground, block fence). Moreover, in the said 1st thru | or 4th embodiment, the boundary sensor was constructed in the left-right direction with respect to the fence. However, you may arrange | position a boundary sensor along an up-down direction in the support | pillar outer peripheral surface of a fence.

  Moreover, in the said embodiment, many electrodes were arrange | positioned for every predetermined space | interval with respect to the sensor body on a single elongate. However, boundary detection may be performed by arranging a short sensor body and a pair of electrodes arranged at both ends in the longitudinal direction of the sensor body as a single unit and arranging the units in series. In this way, when the boundary sensor is damaged, it is only necessary to replace each unit, and management is easy. Further, the boundary sensor and the fence may be modularized by making the unit length substantially coincide with, for example, the interval L1 (see FIG. 4) between the support columns 90 of the first embodiment.

  The configuration of the sensor body is not limited to the above embodiment. This will be described later. The shape of the sensor body is not particularly limited. In addition to the long round bar shape and band shape of the above embodiment, a long square bar shape, a square plate shape, a disc shape, and the like may be used. When the electrode is fixed to the sensor body by vulcanization adhesion, the electrode can be disposed simultaneously with the vulcanization molding of the sensor body.

  The arrangement of the control device and the alarm device connected to the boundary sensor of the present invention is not particularly limited. In the said embodiment, although these were connected with the conducting wire, you may transmit the voltage data from a sensor main body, etc. to a control apparatus wirelessly. In this case, since wiring is not required, the degree of freedom of arrangement of the control device and the like is increased. In the above embodiment, the potential difference data is output from the boundary sensor. However, the electrical resistance data may be output. Also, the type of alarm device is not particularly limited. In addition to sounding an alarm, notification to a security company or the like may be performed. A patrol lamp or the like installed outdoors may be connected to the control device.

<Sensor body>
The sensor body constituting the boundary sensor of the present invention has an elastomer and a conductive filler. The elastomer can be appropriately selected from rubber and thermoplastic elastomer. The elastomer is desirably insulative. In addition, when a mixture (elastomer composition) with a conductive filler is prepared, it is desirable to use one having a saturated volume fraction (φs) in a percolation curve of 35 vol% or more. This is because when the saturated volume fraction (φs) is less than 35 vol%, it is difficult to blend the conductive filler in a substantially single particle state with a high filling rate. Further, in the region of the saturated volume fraction (φs) or more, the electric resistance is low and stable conductivity is expressed. Therefore, when the saturated volume fraction (φs) is 35 vol% or more, the range of change in electrical resistance from the conductor to the insulator when deformed is widened. Further, it is more preferable to use a saturated volume fraction (φs) of 40 vol% or more. In addition, the “elastomer composition” in the present specification includes an elastomer and a spherical conductive filler as essential components. That is, a mixture of an elastomer and a spherical conductive filler may be used, or a mixture of an elastomer, a spherical conductive filler, and other additives may be used.

In consideration of the affinity with the conductive filler, an elastomer having a gel fraction represented by the following formula (1) of 15% or less may be used. The gel fraction is more preferably 10% or less.
Gel fraction (%) = (Wg−Wf) / Wf × 100 (1)
[Wg in formula (1) is a solvent-insoluble content (gel content of conductive filler and elastomer) obtained when an elastomer composition obtained by mixing a conductive filler in an elastomer is dissolved in a good solvent for the elastomer. It is weight. Wf is the weight of the conductive filler. In addition, as a good solvent of an elastomer, the thing with the close SP value (solubility parameter) of a solvent and an elastomer is desirable, For example, toluene, tetrahydrofuran, chloroform, etc. are mentioned. ]

  The value of the gel fraction is an indicator of the critical volume fraction (φc) in the percolation curve. That is, when the critical volume fraction (φc) is less than 30 vol%, the gel fraction becomes a relatively large value because a large amount of elastomer adsorbed and bonded to the aggregate of the conductive filler exists. On the other hand, when the critical volume fraction (φc) is 30 vol% or more, the conductive filler exists in a substantially single particle state, so that the amount of elastomer adsorbed and bonded to the aggregate of the conductive filler is small, and the gel The fraction is a relatively small value of 15% or less.

  Specific examples of elastomers include, for example, natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), acrylonitrile-butadiene copolymer rubber (NBR), styrene-butadiene copolymer rubber (SBR), Ethylene-propylene copolymer rubber [ethylene-propylene copolymer (EPM), ethylene-propylene-diene terpolymer (EPDM), etc.], butyl rubber (IIR), halogenated butyl rubber (Cl-IIR, Br-IIR, etc.) ), Hydrogenated nitrile rubber (H-NBR), chloroprene rubber (CR), acrylic rubber (AR), chlorosulfonated polyethylene rubber (CSM), hydrin rubber, silicone rubber, fluorine rubber, urethane rubber, synthetic latex and the like. . Examples of the thermoplastic elastomer include various thermoplastic elastomers such as styrene, olefin, urethane, polyester, polyamide, and fluorine, and derivatives thereof. Of these, one kind may be used alone, or two or more kinds may be used in combination. Of these, EPDM having extremely good compatibility with the conductive filler is preferable. Also suitable are NBR and silicone rubber, which have good compatibility with the conductive filler.

  The conductive filler has a spherical shape. The spherical shape includes not only a true sphere and a substantially true sphere, but also an oval sphere, an oval sphere (a shape in which a pair of opposing hemispheres are connected by a cylinder), a partial sphere, a sphere having a different radius for each portion, a water droplet shape, and the like. included. For example, the aspect ratio of the conductive filler (the ratio of the long side to the short side) is preferably in the range of 1 or more and 2 or less. This is because when the aspect ratio is larger than 2, a one-dimensional conductive path is easily formed by contact between the conductive fillers. In this case, the saturated volume fraction (φs) may be less than 35 vol%. Further, from the viewpoint of bringing the filling state of the conductive filler in the elastomer closer to the closest packing state, it is preferable to employ particles having a true sphere or a shape very close to a true sphere (substantially spherical) as the conductive filler.

  The conductive filler is not particularly limited as long as it is conductive particles. Examples thereof include fine particles such as carbon materials and metals. Of these, one can be used alone, or two or more can be used in combination.

  It is desirable that the conductive filler is not aggregated as much as possible and exists in the form of primary particles. Therefore, when selecting the conductive filler, it is preferable to consider the average particle diameter, compatibility with the elastomer, and the like. For example, the average particle diameter (primary particles) of the conductive filler is desirably 0.05 μm or more and 100 μm or less. If it is less than 0.05 μm, it tends to aggregate and form secondary particles. Moreover, there exists a possibility that the said saturated volume fraction ((phi) s) may be less than 35 vol%. Preferably it is 0.5 micrometer or more, More preferably, it is 1 micrometer or more. On the other hand, when the thickness exceeds 100 μm, the translational motion (parallel motion) of the conductive filler due to elastic deformation becomes relatively smaller than the particle diameter, and the change in electric resistance against the elastic deformation of the sensor body becomes slow. Preferably it is 60 micrometers or less, More preferably, it is 30 micrometers or less. In addition, the critical volume fraction (φc) and the saturated volume fraction (φs) are within the desired ranges by appropriately adjusting the combination of the conductive filler and the elastomer, the average particle diameter of the conductive filler, and the like. Can be adjusted.

  Moreover, as for the value of D90 / D10 in the particle size distribution of an electroconductive filler, it is desirable that it is 1-30. Here, D90 is the particle diameter at which the cumulative weight is 90% in the cumulative particle size curve, and D10 is the particle diameter at which the cumulative weight is 10%. When the value of D90 / D10 exceeds 30, since the particle size distribution becomes broad, the increase behavior of the electric resistance with respect to the deformation amount of the sensor body becomes unstable. Thereby, the reproducibility of detection may be reduced. It is more preferable that the value of D90 / D10 is 10 or less. In addition, when using 2 or more types of particle | grains as an electroconductive filler, the value of D90 / D10 should just be 100 or less.

  As such a conductive filler, for example, carbon beads are suitable. Specifically, Osaka Gas Chemical Co., Ltd. mesocarbon micro beads [MCMB6-28 (average particle size of about 6 μm), MCMB10-28 (average particle size of about 10 μm), MCMB25-28 (average particle size of about 25 μm)], Carbon micro beads manufactured by Nippon Carbon Co., Ltd .: Nika beads ICB, Nika beads PC, Nika beads MC, Nika beads MSB [ICB 0320 (average particle size of about 3 μm), ICB 0520 (average particle size of about 5 μm), ICB 1020 (average particle size of about 10 μm), PC 0720 ( Average particle diameter of about 7 μm), MC0520 (average particle diameter of about 5 μm)], Nisshinbo carbon beads (average particle diameter of about 10 μm), and the like.

  The conductive filler is blended in the elastomer at a high filling rate. In order to develop desired conductivity, the conductive filler is desirably blended at a ratio equal to or higher than the critical volume fraction (φc) in the percolation curve. From the viewpoint of blending the conductive filler in a substantially single particle state with a high filling rate, the critical volume fraction (φc) is desirably 30 vol% or more. It is more preferable that it is 35 vol% or more. In other words, the filling rate of the conductive filler is desirably 30 vol% or more when the entire volume of the sensor body is 100 vol%. In the case of less than 30 vol%, the conductive filler is not blended in a state close to the closest packing, and thus desired conductivity is not exhibited. In addition, the change in the electric resistance with respect to the elastic deformation of the sensor body becomes slow, and it becomes difficult to control the increase behavior of the electric resistance. It is more preferable that it is 35 vol% or more. On the other hand, the filling rate of the conductive filler is desirably 65 vol% or less when the entire volume of the sensor body is 100 vol%. When it exceeds 65 vol%, mixing with an elastomer becomes difficult and molding processability is lowered. In addition, the sensor body is less likely to be elastically deformed. It is more preferable that it is 55 vol% or less.

  In addition to the elastomer and the conductive filler, various additives may be blended in the sensor body. Examples of the additive include a crosslinking agent, a vulcanization accelerator, a vulcanization aid, an antiaging agent, a plasticizer, a softening agent, and a colorant. In addition to the spherical conductive filler, a conductive filler having an irregular shape (for example, a needle shape) may be blended.

  The sensor body can be manufactured, for example, as follows. First, additives such as a vulcanization aid and a softening agent are added to the elastomer and kneaded. Subsequently, after adding a conductive filler and kneading, a crosslinking agent and a vulcanization accelerator are further added and kneaded to obtain an elastomer composition. Next, the elastomer composition is formed into a sheet, filled in a mold, and press vulcanized under predetermined conditions.

It is a schematic diagram which shows the electroconductive path before the load application of the sensor main body in this invention. It is a schematic diagram which shows the conductive path after the load application of the sensor main body. It is a schematic diagram of the percolation curve in an elastomer composition. It is a front view of the fence where the boundary sensor of the first embodiment of the present invention is arranged. It is a perspective view of the attachment part vicinity of the boundary sensor in a support | pillar. It is an axial perpendicular direction sectional view of the boundary sensor. It is a block diagram of the control device in the first embodiment. It is a schematic diagram of the map stored in the memory | storage part of the same control apparatus. It is a perspective view of the attachment part vicinity of the boundary sensor of 2nd embodiment in a support | pillar. It is an axial perpendicular direction sectional view of the boundary sensor. It is a perspective view near the attachment part of the boundary sensor of 3rd embodiment in a support | pillar. It is an axial perpendicular direction sectional view of the boundary sensor. It is a cross-sectional view perpendicular to the axis of a boundary sensor according to a fourth embodiment. It is a section perspective view of the boundary sensor of a 5th embodiment. It is a transversal direction sectional view of the boundary sensor. It is a wiring diagram (top view) of the boundary sensor. It is a transversal direction sectional view in the emergency of the boundary sensor. It is a section perspective view of the boundary sensor of a 6th embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a, 1b: Boundary sensor 2, 2a, 2b: Sensor main body 3, 3a, 3b: Electrode 30, 30a: Conductor 4, 4a, 4b: Protective cover (protective member) 40: Restraint ring 5: Spacer 50: Small Hole 7a, 7b: Substrate 8, 8a: Control device 80: Bridge circuit 81: Amplification circuit 82a, 82b: Input circuit 83: Calculation unit 84: Storage unit 85: Output circuit 86, 86a: Alarm device 87: Anemometer 9: Fence (boundary partition member) 90: support 91: upper trunk edge 92: lower trunk edge 93: wire mesh panel 94: upper cushioning material 95: lower cushioning material 910: bracket 910a: large hole 910b: small hole 100: sensor main body 101: Elastomer 102: Conductive filler B: Block fence (boundary partition member) F: Fence G: Ground H: House L1: Spacing P: Conductive path P1: Conductive paths r1 to rn, rk: resistance R1 to R3: resistance ΔV: potential difference V1, V2: intermediate potential Vin: power supply

Claims (11)

An elastically deformable sensor body having an elastomer and a spherical conductive filler blended in the elastomer in a substantially single particle state and with a high filling rate, and the electrical resistance increases as the amount of deformation increases; ,
An electrode connected to the sensor body and capable of outputting the electrical resistance;
With
A boundary sensor which is disposed near a boundary where unauthorized passage is prohibited outdoors and can detect passage of the boundary from a change in electrical resistance based on deformation of the sensor body. A boundary section member that prohibits unauthorized passage is disposed at the boundary,
The boundary sensor according to claim 1, wherein the boundary sensor is disposed on the boundary partition member.   The boundary sensor according to claim 2, wherein the sensor body increases in electrical resistance as the temperature rises.   The boundary sensor according to claim 1, wherein the boundary sensor is embedded in the ground near the boundary.   Furthermore, the boundary sensor in any one of Claim 1 thru | or 4 provided with the protection member which coat | covers this sensor main body so that the said sensor main body may not expose. The sensor body has a long shape,
The boundary sensor according to claim 1, wherein a plurality of the electrodes are arranged along a longitudinal direction of the sensor body. The sensor body is composed of an elastomer composition containing the elastomer and the conductive filler as essential components,
In the percolation curve representing the relationship between the blending amount of the conductive filler and the electrical resistance of the elastomer composition, the blending amount of the conductive filler at the second inflection point at which the electrical resistance change is saturated (saturated volume fraction: φs ) Is 35 vol% or more, The boundary sensor according to any one of claims 1 to 6.   The boundary sensor according to any one of claims 1 to 7, wherein a filling rate of the conductive filler is 30 vol% or more and 65 vol% or less when the entire volume of the sensor main body is 100 vol%.   The boundary sensor according to claim 1, wherein the conductive filler is carbon beads.   The boundary sensor according to any one of claims 1 to 9, wherein an average particle diameter of the conductive filler is 0.05 µm or more and 100 µm or less.   11. The elastomer according to claim 1, wherein the elastomer includes one or more selected from silicone rubber, ethylene-propylene copolymer rubber, natural rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, and acrylic rubber. Boundary sensor as described in

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