JPH04102989A - Entering/leaving person counter - Google Patents

Abstract

PURPOSE:To detect a signal outputted from a transmitter terminal with sufficiently high intensity by setting up a length difference between two guide lines to a value less than 1/4 wavelength when forming a by-pass part in one of the two guide lines in each guide line loop antenna and forming a by-pass part also the other guide line. CONSTITUTION:Each guide line loop antenna 3 consists of two parallel guide antenna lines, and when forming a by-pass part in one of the two guide antenna lines, the length difference between the two guide lines is set up to a value <=1/4 wavelength and a bypass part is formed also in the other guide line. A voltage output induced on the antenna 3 is not sharply reduced from a case having no by-pass part. Thereby, the position of the transmitter terminal 4 can surely be detected by any one of the guide line loop antennas 3.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a crowd counting device, and more specifically,
A people counting device that can divide a closed space such as a tunnel, underground structure, or inside a building into appropriate areas and detect the presence of people entering each area. Regarding.

<Prior art and the problem to be solved by the invention> In tunnels, underground tunnels, basements, or closed spaces in buildings where cables are laid, people enter and exit as necessary to carry out work. It can be understood as a closed space system.

Working in a closed space can lead to a serious accident if a person who enters the building is left behind to observe the work from the outside. For this reason, it is extremely important to constantly observe and understand how many people or people are in a closed space. Additionally, if an abnormal situation such as a fire occurs in the vicinity of a person entering the premises, it is important to inform the outside and take some measures.

For this reason, corporate entities that manage closed spaces such as tunnels have established management centers to observe and understand the number of people entering the premises and their identification numbers (IDs) in each area of the closed space.

That is, conventionally, as shown in FIG. 15, a closed space 1 such as a tunnel is divided into appropriate areas, and infrared counters 21, 22, 23, . ... was set up, and the number of people passing in front of it was counted, and the number of counts from each counter was processed to manage the number of people in each area.

This system is economically advantageous because it uses a simple infrared counter, but human behavior is complex, and it requires multiple people to walk back and forth in front of a single counter many times. When they line up and cross the counter,
The number of people entering the campus in each area no longer matches the calculations.

In addition, there is a clang when the machine crosses in front of the counter]・
make a mistake. If such an error occurs, the purpose of this system, which is to accurately grasp the number of people, will not be achieved.

Therefore, each person entering the campus is required to carry a wireless transmitting terminal, receiving antennas are installed in each area of the campus, and the location of the person entering the campus is estimated in the area corresponding to the receiving antenna that most strongly received the radio waves emitted by the wireless transmitting terminal. can also be considered.

However, with this method, radio waves are thought to be able to travel long distances with little attenuation inside tunnels, so the radio waves emitted from wireless transmission terminals owned by visitors are received by many receiving antennas, and It becomes difficult to determine the location.

It becomes even more difficult if radio waves cause fading.

It is conceivable to notify the current location via voice from a wireless transmitter terminal, but it would be costly to prepare a large number of voice wireless transmitters, and it would require complicated work for those entering the premises, so it would be of little practical use.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide information to visitors in a closed space, such as an underground structure or inside a building, in order to inform them of the area in which they are located. To provide a crowd counting device that does not require extensive work and can accurately detect people.

<Means and operations for solving the problems> As shown in FIG.
The transmitter terminal 4 is equipped with a transmitter terminal 4 that generates an alternating current magnetic field (inductive field) at a frequency of less than A signal is guided from the terminal of the guide wire loop antenna 3 to a central control device 6, and the induced voltage generated in each guide wire loop antenna 3 is observed in the central control device 6.

As shown in FIG. 2, the transmitter terminal 4 has a driver 41 that generates an alternating current with a frequency f below the antenna cutoff frequency fo, and an antenna 42.
An alternating current magnetic field H is generated from the antenna 42 by driving the antenna 42 at a frequency f equal to or less than o. AC magnetic field H
is an induced field, and as shown in Fig. 3, it has the characteristic that its intensity rapidly attenuates with distance.

The guide wire loop antenna 3 is composed of two parallel guide antenna wires, and when a detour is formed in one of the two guide wires, the difference in length between the two guide wires is 1/4 wavelength. A detour is also formed on the other side so as not to exceed .

With the above configuration, the magnetic field H generated from the transmitter terminal 4, due to its locality, interlinks only with the guide wire loop antenna 3 installed in the area where the person entering the premises is located. 3 to induce a voltage. The central management device 6 can identify the guide wire loop antenna 3 in which the voltage is induced, and specify the area where the guide wire loop antenna 3 is installed as the area where the visitor is present.

In addition, when forming a detour in one of the guide wire loop antennas due to an obstacle, etc., make sure that the difference in length between the two guide wires does not exceed 174 wavelengths, and Since the detour is also formed, the voltage output induced in the guide wire loop antenna does not decrease significantly compared to the case where there is no detour.

In addition, in the crowd counting device of the present invention, when the closed space 1 has an elongated shape such as a tunnel or a tunnel,
The induction wire loop antenna 3 is a tunnel, a reciprocating line along the length of the tunnel, and the induced voltage is detected at one end of the tunnel.
It is desirable that the other end be terminated with a resistor having a value approximately equal to the characteristic impedance of the reciprocating line.

In this way, impedance matching can prevent standing waves from forming in the guide wire loop antenna 3, so no matter where the transmitter terminal 4 is located,
It can be reliably detected using the guide wire loop antenna 3.

<Example> Embodiments will be described in detail below with reference to the accompanying drawings showing embodiments.

FIG. 4 is a schematic diagram showing a specific example of a crowd counting device, in which a plurality of regions are set in opposite directions, and each region has parallel guiding wire loop antennas 3a, 3b3c, . . . (hereinafter referred to as "3"). ) has been established. Those entering the campus should each use their own transmitter terminals 4a4b, 4c,... (hereinafter coded "4").
”). Guide wire loop antenna 3
One end is input to the switching circuit 7 through signal transmission lines 5a, 5b, 5c, . . . (hereinafter represented by the symbol "5"). The switching circuit 7 performs switching at regular intervals and connects one of the signal transmission lines 5 to the central management device 6.

The ends of the parallel induction wire loop antenna 3 are connected to a resistor RO having a value approximately equal to the characteristic impedance of the antenna (see FIG. 5(a)).

For example, if the frequency f is 20 MHz, the wavelength will be 15 m. The length of the induction wire loop antenna is 100m.
In this case, the length of the loop antenna becomes sufficiently long compared to the wavelength. In such a case, if a conductor is used instead of the resistor RO to short-circuit it, the coupling degree C between the conductor loop antenna and the transmitter terminal will decrease as shown in Figure 5(b).
has a standing wave shape with waves every 172 wavelengths. Therefore, when the position of the transmitter terminal 4 comes to the position of the trough of the standing wave, it is no longer coupled to the guide wire loop antenna.

Therefore, as shown in Fig. 5(a), the terminal end of the induction wire loop antenna is connected to a resistor Ro which is approximately equal to its characteristic impedance.
When connected at , the degree of coupling C between the guide wire loop antenna and the transmitter terminal becomes almost uniform even at the positions of , and the transmitter terminal can be detected at any position.

FIG. 6 is a sectional view of the tunnel, and the width of the tunnel is indicated by W. Cutoff wavelength λC when the tunnel is viewed as a waveguide
can be approximated by λc = 2W, so the cutoff frequency fc at which electromagnetic waves propagate is f c = c / 2 W
(c is the speed of light)...■. The transmission frequency f of the transmitter terminal 4 is of course selected to be lower than the lowest frequency fo at which radio waves are radiated from the antenna as described above, and is also selected to be cut in order to eliminate the propagation of electromagnetic waves in the opposite direction. The frequency is also selected to be smaller than the off frequency fc (in this example, ta<t
o).

The guide wire loop antenna 3 may be installed at any position depending on the shape of the tunnel 1, etc., as long as it can receive an alternating current magnetic field. For example, it may be installed along the ceiling of the tunnel-like tunnel 1 as shown in FIG. 7(a), or along both side walls as shown in FIG. 7(b). As shown in the same figure (C), it may be installed along the bottom of tunnel 1.
It may be installed along one side wall as shown in FIG. 2(d). In particular, a position close to the bottom surface as shown in FIG. 2(C) is preferable because even if a person entering the premises holding the transmitter terminal falls down in the event of an accident, it can be reliably detected.

However, no matter where the guide wire loop antenna 3 is installed on the ceiling of the tunnel, on both sides, near the floor, etc., existing obstacles in the actual tunnel, such as evacuation guide lights, etc.
There may be ventilation fans, fluorescent lights, etc. In this case, if it interferes with the arrangement of the guide wire loop antenna 3, at least one antenna wire must be detoured because the antenna wires cannot be laid symmetrically at predetermined intervals.

In this case, it may be possible to divide multiple areas in opposite directions in front of the obstacle, but if the length of the guide wire loop antenna 3 is long (sometimes 500 m), there is a possibility that the obstacle cannot be avoided. is high, so it cannot be used as a deciding factor.

Therefore, as shown in FIG. 8, a configuration was adopted in which the one of the parallel guide wire loop antennas 3 that hits the obstacle is detoured. In Figures (a) and (b), the detour is made horizontally, and in Figures (c) and (d), it is detoured in the vertical direction.

In the figure, the shape of the detour portion is rectangular or semicircular, but it is not limited to this, and may be circular or wavy, for example. Further, the detour is not limited to the horizontal direction or the vertical direction, and may be detoured in any direction.

However, if only one of the guide wire loop antennas 3 is detoured, there will be a difference in the length of the two antenna wires, and the antenna output at the antenna terminal will decrease. This is because there is a phase difference between the voltages induced in the left and right antenna wires.

The graph in FIG. 9 explains this situation.

The horizontal axis represents the difference between the lengths of the two antennas converted into wavelength, and the vertical axis represents the antenna output. If it shifts by λ/4, the output is 3
The output decreases by dB, and the output completely disappears when it shifts by λ/2.

Therefore, in this embodiment, when one antenna wire is detoured, an appropriate length correction is applied to the other antenna wire so that the difference between the left and right antenna lengths does not exceed λ/4. ing.

In Figure 10, the distance between the left and right antenna wires is X or 80 cm.

An example of actual measurement of VSWR is shown when five detours are provided in a guide wire loop antenna with a length of 60 m.

A terminating resistor RO is connected to the guide wire loop antenna to prevent the generation of standing waves in advance. The width W of the detour (see FIG. 8) was set to X/4=20 cm.

The three tree graphs are obtained by changing the value of the terminating resistor RO.

From the graph, it can be seen that even if there is a detour, the VSWR is 2 or less within the range of 10 to 20 MHz, which is sufficient for practical use.

Figure 11 shows the frequency characteristics of the spatial noise level (equivalent noise figure) up to several tens of MHz, which is standard in CCIR (in the figure, A is a business area, B is a residential area, and C
indicates a rural area, and D indicates a quiet rural area. C.C.II.
? (Refer to Report 258-4), FIG. 12 shows the frequency characteristics of the equivalent noise figure actually measured in the reverse direction, and the higher the frequency, the lower the noise. Therefore, in order to reduce the influence of urban noise, it is preferable to select the frequency f to be as high as possible within a smaller range than fc.

Furthermore, in order to reduce the influence of noise, it is also important that the magnetic field is detected as efficiently as possible by the guide wire loop antenna 3. Figure 13 is a model for calculating reception efficiency, in which the distance between the parallel guiding wire loop antennas 3 is set to 2D.
, the wire diameter is 2r, and the distance from the center of the parallel guiding wire loop antenna 3 to the transmitter terminal 4 is X. The coupling coefficient between the guided wire loop antenna and the transmitter terminal is 0 [c
l B], where ω is the angular frequency and A is a predetermined coefficient, C=101og fA (ω) 21 [dB]D
2 +X2, ■. From this equation, it can be seen that the coupling coefficient C increases in proportion to the square of the frequency, so from this point also the frequency f
is preferably higher than fc within a smaller range.

Next, specific guidelines for selecting the frequency f will be explained.

Assume a tunnel with width W shown in Figure 6. The cutoff frequency is calculated using the formula: fc[MHz co-c = 1
50 . . . ■2W W[m] Since radio waves no longer propagate below this frequency, the only electromagnetic waves that can exist are local induced fields. fc
The attenuation constant of the electromagnetic field in the length direction of the tunnel at the following frequency f is approximately determined by adopting waveguide theory as a [dB/ml=O,181,9f [MH! ]
It is estimated that the pressure is 4.

For example, if the tunnel width W = 5 m, then f
c=30MHz, but with some margin, f=20
Choose MHz. ■From the formula, the damping coefficient α-4c3 B/
m can be obtained. According to this, 40d if 10m away.
B, if the distance is 20 m, the attenuation will be 80 dB, so the locality of the magnetic field can be sufficiently achieved.

This person counting device has an identification number (hereinafter referred to as rlDJ) in the transmitter terminal 4, and is designed to not only detect the presence of people entering the premises, but also individually identify them. There is.

Figure 14 shows the format of the magnetic field modulation signal generated from the transmitter terminal 4, including a preamble, a synchronization bit, a start bit, the ID bit representing the affiliation of the start bit, a number, an error detection bit, and an end bit (PAD). It is made up of.

In the central management device 6, by demodulating each AC voltage signal received through the signal transmission line 5, decoding and detecting the ID bits contained therein, it is possible to determine the affiliation of the persons entering the premises and their individual status.

Table 1 shows each area AB, C identified as above.
,... Number of visitors for each area, and ID of visitors entering that area (001.002,003, ・)
shows the table. (Leaving space below) Table 1 <Effects of the Invention> As described above, according to the people counting device of the present invention, the AC magnetic field H generated from the transmitter terminal is localized to the location of the person entering the premises. A voltage is induced by interlinking only with the induction wire loop antenna installed in the area. The central management device can identify the guide wire loop antenna in which the voltage is induced, and specify the area where the guide wire loop antenna is installed as the area where the visitor is present.

Therefore, in a closed space such as an underground structure or inside a building, it is possible to accurately detect which area a visitor is in without requiring the visitor to perform complicated operations.

Also, due to obstacles etc., one of the guide wire loop antennas
When forming a detour in a book, the difference in length between the two guide wires should not exceed 1/4 wavelength, and a detour is also formed on the other, so the guide wire loop antenna is The induced voltage output is even compared to the case without the bypass section.
The signal from the transmitter terminal can be detected with sufficient strength without significant deterioration.

[Brief explanation of drawings]

Figure 1 is a diagram showing an outline of the people counting device of the present invention, Figure 2 is a diagram showing an outline of the transmitter terminal, and Figure 3 is a diagram showing the distance attenuation characteristics of the induced field output from the transmitter terminal. Graph, Fig. 4 is an overall view showing an example of the turnout counting device, Fig. 5 (a) is a perspective view showing an inductive wire loop antenna whose terminal ends are connected with a resistor, and Fig. 5 (b) is a terminal diagram. Figure 6 is a cross-sectional view of the tunnel, Figure 7 is a diagram illustrating the arrangement of the guide wire loop antenna in the opposite direction, and Figure 8 is the two induction antennas. A perspective view showing the shape of the detour when one of the lines is formed with a detour, Figure 9 is a graph of antenna output versus the difference in length between the two antenna wires, and Figure 10 is a graph of both left and right antenna wires. A graph showing the actual measured value of VSWR when a detour is formed in the CCI
A graph showing the frequency characteristics of the spatial noise level (equivalent noise figure) up to several tens of MHz, which is standard in R. Figure 12 is a graph showing the frequency characteristics of the equivalent noise figure actually measured in the opposite direction. The figure is a cross-sectional view showing the positional relationship between the transmitter terminal and the guide wire loop antenna, Figure 14 is the signal format of the modulation signal that modulates the alternating current magnetic field generated from the transmitter terminal, and Figure 15 is the signal format using an infrared counter. It is a diagram showing a conventional turnout 8-1 number device. 1... Closed space, 3... Guide wire loop antenna, 4
...Transmitter terminal, 6...Central control device, 42...
・Transmission antenna, 41...Driver patent applicant Sumitomo Electric Industries, Ltd. Patent applicant Nippon Telegraph and Telephone Corporation Patent applicant Sumiden Opcom Co., Ltd. Kufu - ``0 Sunshu ha carving N Sho!!!!! Kyoukaifun 齽 Suesundai - Sunsun, ) → Four books h /7/ , ) - 11 To r'Itll → Vertical carving 抛漻輻輻``0 psi kumu) Horo → psi ′-)抛E变-〇(a) (C) fig.(b) (d) fig.,) 4 images 1' rtt Shiro % a dimension

Claims (1)

[Claims] 1. A person who enters a closed space such as an underground structure or inside a building is given a transmitter terminal, the closed space is divided into a plurality of areas, and each area is , a guide wire loop antenna is installed to detect the alternating current magnetic field generated from the transmitter terminal, and the voltage induced in one of the guide wire loop antennas is detected via the signal transmission line to detect the presence of a person entering the premises. The transmitter terminal includes a central management device that specifies an area, and the transmitter terminal has a transmitting antenna and a frequency f that is lower than the lowest frequency fo that can emit radio waves from the transmitting antenna.
and a driver for driving the transmitting antenna with an AC signal of An entry/exit counting device characterized in that the length difference between the guide wires does not exceed 1/4 wavelength, and a detour is formed on the other guide wire.