JP5652233B2 - Detection device, detection system, and detection method - Google Patents

Description

  The present invention relates to a detection device, a detection system, and a detection method.

  A magnetic field detection system may be used as a method for detecting an object, a person, or the like in a partitioned area such as a room. In this magnetic field detection system, a detection target (an object, a person, etc.) is equipped with a magnetic field detection device that detects a magnetic field intensity and transmits a unique identification signal. On the other hand, a coil is installed in the divided area, and a magnetic field is generated by passing an alternating current through the coil. Thereby, a magnetic field having a certain intensity or more can be generated in the region. When the magnetic field detection device detects a magnetic field, the magnetic field detection device determines that the detection target exists in the area and transmits a signal.

  For example, Patent Document 1 is a technology in which an RFID tag is provided with a three-dimensional magnetic field detection coil in the XYZ directions, detects a vector component in the XYZ direction of the magnetic field, and transmits an identification signal of the RFID tag when the magnetic field strength exceeds a certain level. Is disclosed.

JP 2008-217494 A

  By the way, in the security system, it is necessary to prevent false detection outside the partitioned area. That is, the magnetic field intensity outside the region must be equal to or less than the strength that the magnetic field detection device detects as being within the region. However, if a magnetic field is generated by a coil so that the magnetic field in the region has a certain level or more, a magnetic field is also generated outside the region due to the nature of the magnetic field. In the technique of Patent Document 1, a magnetic field having a certain intensity or more is detected even outside the area, and thus erroneous detection may occur.

  The present invention has been made in view of the above problems, and provides a detection device, a detection system, and a detection method capable of detecting the presence of an object, a person, and the like in a specific region while suppressing erroneous detection. With the goal.

In order to solve the above-described problem, the detection device disclosed in the specification includes an AC magnetic field intensity generated by a coil, an axial component on a plane formed by the coil, and an axial component perpendicular to the plane formed by the coil. And a detection unit that determines whether or not the detection unit exists in a predetermined region according to a ratio between the axial component on the plane and the vertical axis component. And when the ratio of the axial component on the plane to the vertical axial component is lower than a predetermined value when the vertical axial component exceeds a predetermined value, It is determined that it exists in the predetermined area .

In order to solve the above-described problem, the detection system disclosed in the specification includes an alternating magnetic field intensity generated by a coil, an axial direction on a plane formed by the coil, and an axial component perpendicular to the plane formed by the coil. And a detection unit that determines whether or not the detection unit exists in a predetermined region according to a ratio between the axial component on the plane and the vertical axis component. And a transmitter that transmits a determination result of the determination unit, and a receiver that receives a signal transmitted from the transmission unit of the detection device . When the axial component exceeds a predetermined value, and the ratio of the axial component on the plane to the vertical axial component falls below a predetermined value, it is determined that the detection unit exists in the predetermined region. .

In order to solve the above-described problem, the detection method disclosed in the specification uses a detection unit to determine the AC magnetic field intensity generated by the coil, the axial component on the plane formed by the coil, and the plane formed by the coil. and separately detecting the vertical direction of the axis component, depending on the ratio of the axial component and the vertical axis component on the plane, the detection unit to determine whether present in a given area When the axial component in the vertical direction exceeds a predetermined value, the detection unit exists in the predetermined region when the ratio of the axial component on the plane to the vertical axial component is lower than the predetermined value. Then, it is determined .

  According to the detection device, the detection system, and the detection method disclosed in the specification, it is possible to detect the presence of an object, a person, or the like in a specific region while suppressing erroneous detection.

1 is a block diagram for explaining an overall configuration of a detection system according to Embodiment 1. FIG. (A) is the permeation | transmission figure which looked at the area | region (alpha) from the perpendicular upper direction, (b) is the beta-beta sectional view taken on the line of the area | region (alpha). It is a block diagram for demonstrating the whole structure of a detection apparatus. It is a figure for demonstrating magnetic field distribution information. It is the figure which represented typically the magnetic field of the Z-axis direction which a coil generates. (A) is a figure for demonstrating the relationship between X-axis and magnetic field strength Hx, (b) is a figure for demonstrating the relationship between X-axis and magnetic field strength Hy, (c) is X-axis. It is a figure for demonstrating the relationship between magnetic field intensity Hz. It is a figure for demonstrating the relationship between a coil and magnetic field intensity. (A) is a figure for demonstrating the height of line1 with respect to the plane which a coil forms, (b) is a top view of a coil. It is a diagram for explaining the relationship between "r _1" and "r _3". (A) is a figure for demonstrating the magnetic field strength ratio (Hx / Hz) of a X-axis direction component and a Z-axis direction component, (b) is a magnetic field strength ratio of a Y-axis direction component and a Z-axis direction component. It is a figure for demonstrating (Hy / Hz). It is a figure for demonstrating an example of the flowchart performed by the setting apparatus when setting threshold value a, b, and c. It is a figure for demonstrating an example of the flowchart performed when determining whether a detection apparatus exists in the area | region (alpha).

  Hereinafter, embodiments will be described with reference to the drawings.

  FIG. 1 is a block diagram for explaining the overall configuration of the detection system 200 according to the first embodiment. Referring to FIG. 1, a detection system 200 includes a detection device 100, an alternating current supply source 210, a coil 220, a receiver 230, a management server 240, a setting device 250, and the like.

  The alternating current supply source 210 supplies an alternating current to the coil 220. Thereby, the coil 220 generates an alternating magnetic field. The detection device 100 detects whether or not the device itself is located within the predetermined region α, and transmits a signal when the device is located. The receiver 230 transmits a signal to the management server 240 when receiving a signal from the detection device 100. With the above configuration, it is possible to detect whether a person carrying the detection device 100, an object equipped with the detection device 100, or the like is located within the predetermined region α. Each parameter used by the detection device 100 is set by the setting device 250.

  2A and 2B are schematic diagrams for explaining an example of the region α. FIG. 2A is a transmission diagram of the region α viewed from vertically above. FIG. 2B is a cross-sectional view of the region α taken along the line β-β. With reference to FIG. 2A and FIG. 2B, the region α is a region inside a rectangular parallelepiped surrounded by wall surfaces. The coil 220 is disposed so as to surround the outer peripheral portion of one of the wall surfaces. Thereby, the coil 220 surrounds the region α in a plane. In other words, the region α is included in a region obtained by extending a plane formed by the coil 220 in a direction perpendicular to the plane.

  In the example of FIG. 2A and FIG. 2B, the coil 220 is disposed so as to surround the outer periphery of the floor of the region α. Moreover, although the coil 220 is arrange | positioned along the inner wall which defines the area | region A in the example of Fig.2 (a) and FIG.2 (b), you may arrange | position along the outer wall. In addition, the coil 220 surrounds the outer periphery of the floor of the region α in the examples of FIGS. 2A and 2B, but may surround the outer periphery of the ceiling of the region α. The outer periphery may be surrounded.

  FIG. 3 is a block diagram for explaining the overall configuration of the detection apparatus 100. Referring to FIG. 3, detection device 100 includes a magnetic field detection unit 10, an angle detection unit 20, a storage unit 30, a calculation unit 40, a control unit 50, a transmission unit 60, and the like.

  The magnetic field detection unit 10 detects the AC magnetic field intensity generated by the coil 220 separately into a biaxial component on a plane formed by the coil 220 and a component perpendicular to the plane formed by the coil 220. It is. As an example, the magnetic field detection unit 10 is a three-axis sensor, and includes an X-axis sensor 11x, a Y-axis sensor 11y, a Z-axis sensor 11z, and amplifiers 12x, 12y, and 12z. The X-axis sensor 11x, the Y-axis sensor 11y, and the Z-axis sensor 11z detect an electromotive force generated by a change in magnetic flux generated by the coil 220, using a resonance circuit including a coil and a capacitor. The X-axis sensor 11x, the Y-axis sensor 11y, and the Z-axis sensor 11z detect an electromotive force generated by a change in magnetic flux in the directions of three axes (X axis, Y axis, Z axis) orthogonal to each other. The Z-axis direction is a direction perpendicular to the plane formed by the coil 220. The X-axis direction and the Y-axis direction are two directions orthogonal to each other on a plane formed by the coil 220.

  The X-axis sensor 11x detects an electromotive force in the X-axis direction. The Y axis sensor 11y detects an electromotive force in the Y axis direction. The Z-axis sensor 11z detects an electromotive force in the Z-axis direction. The amplifier 12x amplifies and outputs the output signal of the X-axis sensor 11x. The amplifier 12y amplifies and outputs the output signal of the Y-axis sensor 11y. The amplifier 12z amplifies and outputs the output signal of the Z-axis sensor 11z.

  The axial direction detected by the three-axis sensor may deviate from the three orthogonal axes. Therefore, the angle detection unit 20 uses a gyro sensor or the like to detect angles θx, X, Y, and Z that are detected by the X-axis sensor 11x, the Y-axis sensor 11y, and the Z-axis sensor 11z, respectively. Measure θy and θz and output.

  The storage unit 30 includes a measurement intensity storage unit 31, a measurement angle storage unit 32, a magnetic field information storage unit 33, and a condition storage unit 34. The measurement strength storage unit 31 stores the output value of the amplifier 12x as the measurement magnetic field strength Hx, stores the output value of the amplifier 12y as the measurement magnetic field strength Hy, and stores the output value of the amplifier 12z as the measurement magnetic field strength Hz. The measurement angle storage unit 32 stores the angles θx, θy, and θz. The magnetic field information storage unit 33 stores magnetic field distribution information. The condition storage unit 34 stores threshold conditions. Details of the magnetic field distribution information and the threshold condition will be described later.

  The calculation unit 40 includes a correction unit 41 and a processing unit 42. The correction unit 41 acquires the measurement magnetic field strengths Hx, Hy, Hz from the measurement intensity storage unit 31 and acquires the angles θx, θy, θz from the measurement angle storage unit 32. The correction unit 41 determines the correction magnetic field strength Hx ′ in the X-axis direction by correcting the measurement magnetic field strength Hx using the angle θx. Further, the correction unit 41 obtains the corrected magnetic field strength Hy ′ in the Y-axis direction by correcting the measured magnetic field strength Hy using the angle θy. Further, the correction unit 41 determines the correction magnetic field intensity Hz ′ in the Z-axis direction by correcting the measurement magnetic field intensity Hz using the angle θz.

  The processing unit 42 functions as a magnetic field information extraction unit 43, a comparison unit 44, a ratio calculation unit 45, and a determination unit 46. The magnetic field information extraction unit 43 acquires the magnetic field distribution information Hxn, Hyn, Hzn (n is an integer equal to or greater than 1) from the magnetic field information storage unit 33 and supplies the information to the comparison unit 44. The comparison unit 44 compares the corrected magnetic field strengths Hx ′, Hy ′, Hz ′ obtained by the correction unit 41 with the magnetic field distribution information Hxn, Hyn, Hzn, and gives the result to the determination unit 46. The ratio calculation unit 45 calculates the ratio of the corrected magnetic field strengths Hx ′, Hy ′, and Hz ′ obtained by the correction unit 41 and gives the ratio to the determination unit 46. The determination unit 46 determines whether or not the magnetic field detection unit 10 exists in the region α based on the information given from the comparison unit 44 or the ratio calculation unit 45, and gives the result to the control unit 50.

  In addition, it can be determined whether the detection apparatus 100 exists in the area | region (alpha) by determining whether the magnetic field detection part 10 exists in the area | region (alpha). By determining whether or not the detection device 100 exists in the region α, it is possible to determine whether a person carrying the detection device 100, an object equipped with the detection device 100, or the like exists in the region α.

  The control unit 50 causes the transmission unit 60 to transmit a signal when it is determined that the detection device 100 exists in the region α, and transmits the signal when the detection device 100 is not determined to exist within the region α. Do not send a signal. Alternatively, the control unit 50 may cause the transmission unit 60 to transmit different signals depending on whether or not the detection device 100 is determined to exist within the region α. As described above, the transmission unit 60 transmits the determination result of the determination unit 46. Note that the transmission unit 60 may also transmit the identification information of the detection device 100 when transmitting the determination result of the determination unit 46. Thereby, the management server 240 can determine which detection device exists in the region α.

  Next, the magnetic field distribution information will be described. FIG. 4 is a diagram for explaining magnetic field distribution information. The magnetic field strength in each block (position) within the region α is determined according to the magnitude of the alternating current flowing through the coil 220. Therefore, the magnetic field strength in each block in the region α can be acquired in advance. Each of the values in FIG. 4 represents the magnetic field strength (magnetic field distribution information Hxn) in the X-axis direction, the magnetic field strength (magnetic field distribution information Hyn) in the Y-axis direction, and the Z-axis direction in each block in the region α. It is an example of magnetic field intensity (magnetic field distribution information Hzn). In the example of FIG. 4, “n” indicates any value from 1 to 9. “N / A” means outside the region α.

  When the combination of the correction magnetic field strengths Hx ′, Hy ′, and Hz ′ obtained by the correction unit 41 matches the combination of the values of any of the blocks in FIG. 4, the detection device 100 is present in the region α. Judgment can be made. Since the magnetic field strength in the region α changes continuously, the magnetic field strength changes continuously according to the position in the region α. Therefore, the combination of the correction magnetic field strengths Hx ′, Hy ′, and Hz ′ may not completely match the combination of the values of any of the blocks in FIG. Specifically, if each value of the correction magnetic field strengths Hx ′, Hy ′, and Hz ′ is included in a predetermined range including the value of any block in FIG. 4, the detection device 100 exists in the region α. It can be determined.

  Next, threshold conditions will be described. When the magnetic field information is not stored in the magnetic field information storage unit 33, it can be determined whether or not the detection device 100 exists in the region α using a threshold value. In the present embodiment, the threshold condition includes a first threshold value a, a second threshold value b, and a third threshold value c.

  FIG. 5 is a diagram schematically showing a magnetic field in the Z-axis direction generated by the coil 220. In the example of FIG. 5, it is assumed that the coil 220 has a rectangular shape. Each vertex of the rectangle formed by the coil 220 is defined as a point P, a point Q, a point R, and a point S. The side formed by the points P and Q is the first side, the side formed by the points Q and R is the second side, and the side formed by the points R and S is the third side. The side formed by the points S and P is the fourth side. The positive X-axis direction is a direction from point S to point P and a direction from point R to point Q. The positive Y-axis direction is a direction from point P to point Q and a direction from point S to point R. The Z-axis positive direction is a direction perpendicular to the plane formed by the point PQRS, and in the example of FIG. 2B, is the direction from the floor of the region α to the ceiling.

  A predetermined value equal to or greater than the intensity that can be detected by the magnetic field detector 10 in the Z-axis direction is defined as a first threshold value a. When a magnetic field in the Z-axis direction is generated in the region α with an intensity greater than or equal to the first threshold value a, a region β in which the magnetic field strength in the Z-axis direction is greater than or equal to the first threshold value a extends beyond the region α. . Therefore, if the inside / outside of the region α is determined using only the magnetic field strength in the Z-axis direction, there is a possibility that erroneous detection occurs in the region β. Therefore, in this embodiment, the inside / outside of the region α is determined using the ratio of the magnetic field strengths in the respective axial directions.

  FIG. 6A is a diagram for explaining the relationship between the X axis and the magnetic field strength Hx. FIG. 6B is a diagram for explaining the relationship between the X-axis and the magnetic field strength Hy. FIG. 6C is a diagram for explaining the relationship between the X axis and the magnetic field strength Hz. The magnetic field strengths Hx, Hy, Hz are the X-axis component, the Y-axis component, and the Z-axis component of the magnetic field generated by the coil 220. 6A to 6C, the first line is a line passing through the center of the first side PQ and the center of the third side RS in FIG. 5, and the second line is the fourth side SP. It is a line that passes through. The first line and the second line pass through “Zero” in the Z-axis direction.

  Referring to FIG. 6A, the magnetic field strength Hx is larger in the first line than in the second line. Further, the magnetic field strength Hx shows zero at the center of the region α in both the first line and the second line, increases as it goes away from the center, reaches a maximum value outside the region α, and increases further away from the region α. Get smaller. Therefore, the magnetic field strength Hx increases as the distance from the center increases in the region α. The reason why the magnetic field intensity Hx shows a maximum value outside the region α will be described below.

First, the magnetic field strength at the predetermined point T (X, Y, Z) in the region α will be described. FIG. 7 is a diagram for explaining the relationship between the coil 220 and the magnetic field strength. The current I flowing through the coil 220 flows in the order of the point P, the point Q, the point R, and the point S from the vicinity of the center of the fourth side SP, and is taken out from the vicinity of the center of the fourth side SP. The number of turns of the coil 220 is “N”. The height of the point T from the rectangular plane formed by the coil 220 is “h”. The lengths of the second side QR and the fourth side SP are “L ₁ ”. The lengths of the first side PQ and the third side RS are “L ₂ ”. An angle formed by the side TP and the side PQ is “θ ₁ ”. The angle formed by the side TQ and the side PQ is “θ ₂ ”. The distance between the point T and the first side PQ is “r ₁ ”.

Point T is the magnetic field _{H 1} received from the first side PQ is represented by the following formula (1).

When a magnetic field _{H 1} is an angle formed between the X axis and the theta _3, Z-axis component _{H 1Z} of the magnetic field _{H 1} is represented by the following formula (2), the X-axis component _{H 1X} of the magnetic field _{H 1} by the following formula (3) expressed. The magnetic field H ₂ received by the point T from the second side QR, the magnetic field H ₃ received from the third side RS, and the magnetic field H ₄ received from the fourth side SP can also be obtained by the same expression.

Therefore, the X-axis component H _X of the magnetic field at the point T is expressed by the following formula (4), the Y-axis component H _Y is expressed by the following formula (5), and the Z-axis component H _Z is expressed by the following formula (6). Is done. H _3x is the X-axis component of the magnetic field H ₃ . H _2y is the Y-axis component of the magnetic field H ₂ . H _4y is the Y-axis component of the magnetic field H ₄ . H _2z is a Z-axis component of the magnetic field H ₂ . H _3z is the Z-axis component of the magnetic field H ₃ . H _4z is the Z-axis component of the magnetic field H ₄ .

Next, the magnetic field intensity on the line (line 1) in the X-axis direction in the region between the second side QR and the fourth side SP will be described. FIG. 8A is a view for explaining the height of the line 1 with respect to the plane formed by the coil 220, and is a front view of the coil 220 as viewed from the fourth side SP. FIG. 8B is a plan view of the coil 220. 8A and 8B, the height of line1 is “h”, and the distance in the Y-axis direction from the fourth side SP of line1 is “d”. The distance between an arbitrary point on line 1 and the third side RS is “r ₃ ”.

Here, the magnetic field strength Hx in the X-axis direction in a range satisfying the relationship of r ₁ <r ₃ and r ₃ ≧ √2 on line ₁ will be described. It is assumed that the conditions of L ₁ = 1, L ₂ = 3, h = 1, d = 1.5, and I = 1.5 are satisfied. In this case, the magnetic field strength Hx can be expressed as the following formula (7). The relationship between the distance r ₁ and the distance r ₃ can be expressed as in the following formula (8). In Expression (7), “θ ₄ ” is an angle formed by the side TR and the side RS, “θ ₅ ” is an angle formed by the side TS and the side RS, and “θ ₆ ” is the magnetic field H ₃ is X This is the angle that becomes the axis.

The maximum value of the magnetic field strength Hx and its coordinates can be obtained from the values of “r ₁ ” and “r ₃ ” at which the differential function of Equation (7) becomes zero. FIG. 9 is a diagram for explaining the relationship between “r ₁ ” and “r ₃ ”. Referring to FIG. 9, the local maximum value of Expression (7) is not on the first side PQ but outside the coil 220. From the above, the magnetic field strength Hx shows a maximum value outside the region α.

  Referring to FIG. 6B again, the magnetic field strength Hy becomes almost zero at any point on the first line. This is because the magnetic field generated by the second side QR and the magnetic field generated by the fourth side SP cancel each other. The magnetic field strength Hy has a predetermined magnitude as the distance from the first line increases. For example. In the second line, the magnetic field strength Hy becomes maximum at the center of the region α, and decreases as the distance from the center of the region α increases.

  Referring to FIG. 6C, the magnetic field intensity Hz becomes maximum at the center of the region α, and decreases as the distance from the center of the region α increases. Therefore, the magnetic field intensity Hz is the smallest at each rectangular apex formed by the coil 220.

As described with reference to FIGS. 6A to 6C, the magnetic field generated by the coil 220 has different intensity distributions depending on the position and each axis component. A point where the magnetic field intensity in the Z-axis direction is the smallest in the region α is used as the reference point in the ideal model. In the coil 220 having a rectangular shape, each vertex is a reference point. In this embodiment, the point S is used as a reference point. The magnetic field strength at the reference point is represented as (Hxref, Hyref, Hzref). When L ₁ = 1, L ₂ = 3, h = 1, I = 1.5, and N = 1, the magnetic field strength at the reference point is (593, 808, 648). In this example, the first threshold value a is set to “648” or less. Considering a margin for sufficiently exceeding the first threshold value a in all of the region α, the first threshold value a is set to, for example, Hzref × 0.8 (a = 518).

  The components in the Z-axis direction in the region α are all a = 518 or more, while there are positions where a = 518 or more outside the region α. Here, using the difference in intensity distribution between the X-axis direction and the Y-axis direction, the intensity ratio between the Z-axis direction component and the X-axis direction component and the intensity ratio between the Z-axis direction component and the Y-axis direction component are calculated. And used for determination of the inside and outside of the region α.

  FIG. 10A is a diagram for explaining the magnetic field strength ratio (Hx / Hz) between the X-axis direction component and the Z-axis direction component. FIG. 10B is a diagram for explaining the magnetic field strength ratio (Hy / Hz) between the Y-axis direction component and the Z-axis direction component. In FIG. 10A and FIG. 10B, both the first line and the second line are drawn.

  Referring to FIG. 10A, in both the first line and the second line, Hx / Hz indicates zero at the center in the region α and increases as the distance from the center increases. Accordingly, Hx / Hz at the end of the region α is used as the second threshold value b, and if Hx / Hz is less than the second threshold value b, it can be determined that the detection device 100 exists in the region α. Since Hx / Hz is the largest at the reference point, Hx / Hz at the reference point can be set as the second threshold value b. In the present embodiment, the second threshold value b = 0.92.

  Referring to FIG. 10B, Hy / Hz in the first line is zero because Hy in the first line is zero. Since Hy has a predetermined size when moving away from the first line, Hy / Hz also has a predetermined size. In this case, Hy (≠ 0) / Hz is the smallest at the center in the region α and increases as the distance from the center increases. Therefore, Hy / Hz at the end of the region α is used as the third threshold value c, and if Hy / Hz is less than the third threshold value c, it can be determined that the detection device 100 exists in the region α. Since Hy / Hz is the largest at the reference point, Hy / Hz at the reference point can be set as the third threshold value c. In the present embodiment, the third threshold value c = 1.25.

Table 1 shows the calculation results of the magnetic field strengths Hx, Hy, Hz and the respective ratios at points inside and outside the region α. Referring to FIG. 5 again, the point A is a point located outside the region α on the first line. Point O is the center point of region α and is located on the first line. Point B is a reference point that coincides with vertex S and is located on the second line. Point C is a point located at the center of the second line. Point D is a point located at the end of region α in the first line. Point E is an arbitrary point between the first line and the second line.

  Referring to Table 1, in the region α, the Hz at any point was larger than the Hz at the point B. Further, in the region α, Hx / Hz at any point was smaller than Hx / Hz at point B. Furthermore, within the region α, Hy / Hz at any point was smaller than Hy / Hz at point B. Therefore, the value of Hz at point B or lower is used as the first threshold value a, Hx / Hz at point B is used as the second threshold value b, and Hy / Hz at point B is the third threshold value. Can be used as the value c.

  The determination unit 46 determines that Hz ′ exceeds the first threshold value a, and (Hx ′ / Hz ′) <second threshold value b and (Hy ′ / Hz ′) <third threshold value c. When either one is established, it is determined that the detection device 100 exists in the region α. In this case, erroneous determination can be suppressed. It should be noted that Hz ′ exceeds the first threshold value a, and (Hx ′ / Hz ′) <the second threshold value b and (Hy ′ / Hz ′) <the third threshold value c. When it is established, it may be determined that the magnetic field detection unit 10 exists in the region α. In this case, erroneous determination can be further suppressed.

FIG. 11 is a diagram for explaining an example of a flowchart executed by the setting device 250 when setting the threshold values a, b, and c. Referring to FIG. 11, setting device 250 sets parameters “L ₁ ”, “L ₂ ”, “h”, “I”, and “N” (step S 1). These parameters are input to the setting device 250 by the user.

  Next, the setting device 250 determines the coordinates (x, y, z) of the reference point in FIG. 5 (step S2). Next, the setting device 250 calculates the magnetic field strength (Hxref, Hyref, Hzref) at the reference point (step S3). Next, the setting device 250 sets Hzref × 0.8 to the first threshold value a, sets Hxref / Hzref to the second threshold value b, and sets Hyref / Hzref to the third threshold value c. (Step S4). Each threshold value is set by the above procedure. These threshold values are stored in the condition storage unit 34.

  FIG. 12 is a diagram for explaining an example of a flowchart executed when determining whether or not the detection apparatus 100 exists in the region α. Referring to FIG. 12, the magnetic field detection unit 10 measures the magnetic field strength (Hx, Hy, Hz) at an arbitrary point (position of the three-axis sensor) (step S11). The measured magnetic field strength is corrected by the correction unit 41, and the corrected magnetic field strength (Hx ′, Hy ′, Hz ′) is obtained. Next, the ratio calculation unit 45 calculates the magnetic field strength ratios Hx ′ / Hz ′ and Hy ′ / Hz ′ (step S12).

  Next, the determination unit 46 determines whether Hz ′ is equal to or lower than the first threshold value a (step S13). When it determines with "Yes" in step S13, the determination part 46 determines with the detection apparatus 100 being outside the area | region (alpha) (step S17), and complete | finishes the execution of a flowchart. When it determines with "No" in step S13, the determination part 46 determines whether magnetic field intensity ratio Hx '/ Hz' is more than the 2nd threshold value b (step S14). When it determines with "Yes" in step S14, the determination part 46 determines with the detection apparatus 100 being outside the area | region (alpha) (step S17), and complete | finishes the execution of a flowchart. When it determines with "No" in step S14, the determination part 46 determines whether magnetic field intensity ratio Hy '/ Hz' is more than the 3rd threshold value c (step S15).

  When it determines with "Yes" in step S15, the determination part 46 determines with the detection apparatus 100 being outside the area | region (alpha) (step S17), and complete | finishes execution of a flowchart. When it determines with "No" in step S15, the determination part 46 determines with the detection apparatus 100 being in the area | region (alpha) (step S16), and complete | finishes execution of a flowchart. With the above procedure, it can be determined whether the detection device 100 is inside or outside the region α.

  According to the present embodiment, by using the ratio between the axial component on the plane formed by the coil 220 and the axial component in the direction perpendicular to the plane, the detection of an object, a person, etc. Presence can be detected.

  In the present embodiment, the magnetic field detection unit 10 detects magnetic field strength components in three axial directions, but at least an axial component on a plane formed by the coil 220 and an axial component perpendicular to the plane. May be detected. Further, in the present embodiment, the magnetic field strength components in the two orthogonal (X-axis, Y-axis) directions perpendicular to the plane formed by the coil 220 are directly detected, but the present invention is not limited to this. For example, a non-orthogonal biaxial magnetic field strength component on the plane formed by the coil 220 may be detected and converted to a biaxial component that is orthogonal.

  In the present embodiment, the region α has a rectangular parallelepiped shape, but is not limited thereto. For example, the region α may be a polygonal column, a cylinder, a sphere, or the like. In this case, the coil 220 only needs to have a shape surrounding the region α in a plane. For example, the coil 220 may have a circular shape, a diamond shape, or a polygonal shape in accordance with the shape of the region α.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

DESCRIPTION OF SYMBOLS 10 Magnetic field detection part 11 Axis sensor 12 Amplifier 20 Angle detection part 30 Storage part 31 Measurement intensity storage part 32 Measurement angle storage part 33 Magnetic field information storage part 34 Condition storage part 40 Calculation part 41 Correction part 42 Processing part 43 Magnetic field information extraction part 44 Comparison unit 45 Ratio calculation unit 46 Judgment unit 50 Control unit 60 Transmission unit 100 Detection device 200 Detection system 210 AC current supply source 220 Coil 230 Receiver 240 Management server 250 Setting device

Claims (9)

A detection unit that detects an alternating magnetic field intensity generated by the coil separately into an axial component on a plane formed by the coil and an axial component perpendicular to the plane formed by the coil;
A determination unit that determines whether or not the detection unit exists in a predetermined region in accordance with a ratio between an axial component on the plane and the vertical axis component ;
In the case where the vertical axis component exceeds a predetermined value, the determination unit determines that the detection unit detects the predetermined region when the ratio of the axial component on the plane to the vertical axis component is lower than a predetermined value. A detection device characterized in that it is determined to be present in the inside . The detection unit detects a biaxial component on a plane formed by the coil from the alternating magnetic field intensity generated by the coil,
When the vertical axis component exceeds a first threshold value, the determination unit is configured such that one ratio of the two axis components to the vertical axis component is lower than a second threshold value and the vertical axis component is lower than the first threshold value. The detection device according to claim 1, wherein when the other ratio of the two-axis component to the axis component is lower than a third threshold value, it is determined that the detection unit exists in the predetermined region. The detection device according to claim 2 , wherein the first threshold value is a value equal to or less than a minimum value of the axial component in the vertical direction in the predetermined region. The second threshold value and the third threshold value are values equal to or less than the respective ratios of the biaxial component to the vertical axial component at a point where the vertical axial component in the predetermined region shows a minimum value. The detection device according to claim 2 or 3, wherein The coil has a rectangular winding, and surrounds the predetermined area in a plane,
5. The detection device according to claim 2 , wherein a biaxial direction on a plane formed by the coil coincides with the rectangular sides that are orthogonal to each other. The detection apparatus according to claim 1 , further comprising a transmission unit that transmits a determination result of the determination unit. The detection device according to claim 6 , wherein the transmission unit transmits identification information of the detection device. A detection unit that detects an alternating magnetic field intensity generated by the coil separately into an axial direction on a plane formed by the coil and an axial component perpendicular to the plane formed by the coil; and an axial component on the plane And a determination unit that determines whether or not the detection unit exists within a predetermined region according to a ratio between the vertical axis component and the vertical axis component, and a transmission unit that transmits a determination result of the determination unit A detection device;
A receiver for receiving a signal transmitted from the transmission unit of the detection device ,
In the case where the vertical axis component exceeds a predetermined value, the determination unit determines that the detection unit detects the predetermined region when the ratio of the axial component on the plane to the vertical axis component is lower than a predetermined value. The detection system characterized by determining that it exists in the inside . Using the detection unit, the alternating magnetic field intensity generated by the coil is detected by separating the axial component on the plane formed by the coil and the axial component perpendicular to the plane formed by the coil,
Depending on the ratio of the axial component and the vertical axis component on the plane, when the detection unit to determine whether present in a given area, the axial component of the vertical direction exceeds a predetermined value In this case, when the ratio of the axial component on the plane to the vertical axial component is lower than a predetermined value, it is determined that the detection unit is present in the predetermined region .

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