JP2859401B2 - Inbound / outbound counting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an entry / exit counter, and more particularly, to a closed space such as a road, a tunnel, an underground structure, or a building. Is divided into appropriate areas, and an entrance / exit counter that can detect the presence of a person in each area.

<Problems to be solved by the conventional technology and the invention> In a closed space in a road where cables are to be laid, underground tunnels, basements, or buildings, humans can enter and leave work and work as necessary. It can be regarded as a closed space system.

Work in a closed space is difficult to observe from the outside, and if an entrant is left inside, it can lead to a serious accident. For this reason, it is very important to always observe and grasp how many people or who is in which area of the closed space. When an abnormal situation such as a fire accident occurs near the place where the entrant is present, it is also important to inform the outside of the situation and take some measures.

For this reason, in a company that manages a closed space such as a road, a management center is provided so that the number of visitors and their identification numbers in each area in the closed space are grasped.

That is, conventionally, a closed space such as a road is divided into appropriate areas, an infrared counter is provided at the boundary of each area, a person passing therethrough is counted, and the count number of each counter is processed. The number of people in each area was managed.

Although this system is economically advantageous in that it uses a simple infrared counter, human behavior is complex and it can make multiple round trips in front of a single counter or multiple people. If they cross the counter side by side, the number of visitors in each area will not match the calculation. In addition, counting errors occur even if the machine crosses in front of the counter. If such an error occurs, the purpose of the present system for reliably grasping the number of visitors cannot be achieved.

Therefore, each entrant has a wireless transmission terminal,
It is also conceivable to install a receiving antenna in each area of the premises and estimate the position of the entrant in an area corresponding to the receiving antenna that has most strongly received the radio wave emitted from the wireless transmission terminal.

However, in this method, radio waves are considered to travel to a distant place with little attenuation in the road or tunnel, so the radio waves emitted from the wireless transmission terminal owned by the entrant are received by many receiving antennas, and the position of the entrant is Is difficult to determine. It is even more difficult if the radio waves fade.

It is conceivable that the current position is notified from the wireless transmission terminal by voice. However, it is costly to prepare a large number of voice wireless transmitters, and a complicated operation is required for the visitors, and there is almost no practicality.

The present invention has been made in view of the above problems, and an object of the present invention is to make it difficult for an entrant to determine which area the occupant is in a closed space such as an underground structure or a building. It is an object of the present invention to provide an entry / exit counter that does not require a simple operation and can accurately detect.

<Means and Actions for Solving the Problems> To achieve the above object, the entrance / exit counting apparatus of the present invention, as shown in FIG. Electromagnetic waves at frequencies below fc (electromagnetic waves are waves in which a magnetic field and an electric field fluctuate alternately, so they can also be considered as magnetic field waves. Therefore, the expression "electromagnetic field" or "magnetic field" is used to represent electromagnetic waves. It is possible to have a transmitter terminal 4 for generating a (guidance field), vertically divide a closed space 1 such as a road into a plurality of areas along a road in the space, and The guide wire loop antenna 3 is installed so as to be substantially parallel to the road in the area, and a signal is guided from the terminal of the guide wire loop antenna 3 to the central control device 6. Occurred in It is obtained so as to observe the electromotive voltage.

As shown in FIG. 1, the transmitter terminal 4 includes an oscillator 41 for generating an AC having a frequency f equal to or lower than the minimum frequency fc.
, A plurality of transmitting antennas 42a, 42b,... (Two cases are shown in the figure) installed with different directivity directions, and a transmitting antenna 43 for supplying a driving signal with a phase shift to each transmitting antenna. It has.

An AC magnetic field H is generated from the transmitting antennas 42a and 42b by driving the layer proposals 42a and 42b at a frequency f equal to or lower than fc. The AC magnetic field H is an induction field, and has a characteristic that the intensity rapidly decreases with the distance D as shown in FIG.

In addition, since signals having phases shifted from each other are given to the plurality of transmitting antennas 42a and 42b, the induced voltage of the induction wire loop antenna 3 is obtained by synthesizing the induced voltages due to the AC magnetic fields generated from the respective transmitting antennas 42a and 42b. Becomes 4th
The figure is a vector composition diagram showing a state in which the induced voltages VA and VB are combined into VC when the phase shift of the transmission antennas 42a and 42b is 90 °. Depending on the relative angle between the transmitter terminal 4 and the induction loop antenna 3, only one of the transmitting antennas 42a and 42b alone may generate the induced voltage VA or VB.
May be so small that it cannot be detected, but the combined induced voltage VC is always a detectable large value.

When the transmission antenna is used alone, the voltage induced in the induction loop antenna may be too small to be detected depending on the relative angle between the transmitter terminal 4 and the induction loop antenna 3. For the following reasons.

When actually using the transmitter terminal, the transmitting antenna generates a magnetic field, and the induction wire loop antenna is linked to it.When considering the coupling between the two, the induction wire loop antenna generates the magnetic field by the reciprocity theorem. It can be considered that the transmission antenna is linked to this.
Considering this, the magnetic field generated when a reciprocating current is passed through the induction loop antenna is as shown in FIG. 5, and the transmitting antenna interlinking with it matches the direction of the magnetic field as shown in FIG. The maximum degree of coupling. In addition, the coupling is 0 when the angle is a right angle as shown in FIG. Generally, when the direction between the direction of the magnetic field and the transmitting antenna is θ (see FIG. 3C), the coupling is proportional to cos θ. Therefore, if the axis of the magnetic field and the axis of the transmitting antenna are orthogonal to each other, the coupling becomes zero, and the terminal of the transmitter cannot be detected.

In the present invention, the phase shift of the transmitting antennas 42a and 42b is 9
It is not limited to 0 °, but is generally in-phase (0 °)
80 °). This is because when both antennas are driven with an appropriate phase difference, a combined component is always generated. However, it is not preferable to combine the two antennas in the same phase or opposite phases, since the degree of coupling in the combined case becomes zero.

Since the present invention is configured as described above, regardless of the relative angle between the transmitter terminal 4 and the inductive wire loop antenna 3, the magnetic field generated from the transmitter terminal 4 may be intruded due to its locality. A large voltage is induced in the guide wire loop antenna 3 by interlinking only with the guide wire loop antenna 3 installed in the region where the user is located. Therefore,
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 presence area of the entrant.

<Example> Hereinafter, an example will be described in detail with reference to the accompanying drawings.

FIG. 6 is a schematic diagram showing a specific example of an entry / exit counting device, in which a plurality of areas are set in a road, and parallel guide wire loop antennas 3a, 3b,. Representative). Visitors are their own transmitter terminals
4a, 4b,... (Hereinafter represented by reference numeral “4”).
One end of the induction loop antenna 3 is connected to the antenna couplers 8a and 8
b,... (hereinafter represented by reference numeral “8”), are connected to a central management device 6 through a signal line 5.

FIG. 7 is an external view of the transmitter terminal 4, in which ferrite bar antennas 42a and 42b are arranged at right angles to each other. 44 is an emergency abnormality switch, 45 is an indicator lamp, 46 is a power switch, and 47 is an ID number setting device.

FIG. 8 is a circuit configuration diagram of the antenna section of the transmitter terminal 4. The transmitter terminal oscillation circuit 401 is divided into two through the hybrid transformer 402, one is connected to the impedance coupling transformers 404 and 405 via the 90 ° phase shifter 403, and the other is not via the phase shifter. Is done. The ends of the impedance coupling transformers 404, 405 are coupled to the ferrite bar antennas 42a, 42b.

As described above, since the directivities of the ferrite bar antennas 42a and 42b are orthogonal to each other and the phase shifter 403 is used, the AC magnetic field generated from the ferrite bar antenna 42a and the AC magnetic field generated from the ferrite bar antenna 42b are Is radiated to the outside like a circularly polarized wave or an elliptically polarized wave. Therefore, regardless of the angle of the transmitter terminal 4 with respect to the parallel induction wire loop antenna 3, that is, regardless of the orientation of the transmitter terminal 4, the AC magnetic field of the transmitter terminal 4 is as follows.
It links with the parallel guide wire loop antenna 3.

Therefore, with only one ferrite bar antenna,
As compared with a transmitter terminal without a phase shifter, the detection of an entrant can be performed more reliably.

FIG. 9 is a cross-sectional view of the road, where the width of the road is W.
Indicated by Cut-off wavelength λ when viewing the path as a waveguide
Since c can be approximated by λc = 2W, the cutoff frequency fc at which the electromagnetic wave can propagate is fc = c / 2W (c is the speed of light). The transmission frequency f of the transmitter terminal 4 is selected to be lower than the cutoff frequency fc in order to eliminate the propagation of electromagnetic waves in the road.

The induction line loop antenna 3 may be installed at any position according to the shape of the road 1 as long as it can receive an AC magnetic field. For example, it may be installed along the ceiling of the tunnel-shaped road 1 as shown in FIG. 10 (a), or may be installed along both side walls as shown in FIG. 10 (b). As shown in FIG. 3 (c), it may be installed along the bottom of the road 1,
It may be installed along one side wall as shown in FIG. In particular, a position close to the bottom surface as shown in FIG. 3C is preferable because even if an entrant holding the transmitter terminal falls down at the time of an accident, it can be reliably detected.

In order to reduce the influence of noise, it is important that the magnetic field is detected by the induction loop antenna 3 as efficiently as possible. FIG. 11 shows a model for calculating the reception efficiency.
D, the wire diameter is 2r, and the distance from the center of the parallel guide wire loop antenna 3 to the transmitter terminal 4 is X. Coupling coefficient C [d between the induction loop antenna and the transmitter terminal
B] is, given that ω is an angular frequency and A is a predetermined coefficient, Becomes From this equation, it can be seen that the coupling coefficient C increases in proportion to the square of the frequency.
Is preferably higher in a range smaller than fc.

Next, a specific guideline for selecting the frequency f will be described. Ninth
A road having a width W in the drawing is assumed. The cutoff frequency is
Using the formula Since the radio wave does not propagate below this frequency, the only possible electromagnetic wave is a local guidance field. fc
The attenuation constant of the electromagnetic field in the length direction of the path at the following frequency f is approximately calculated using the waveguide theory, It is estimated to be.

If the width of the road is W = 5 m, fc = 30 MHz from the equation. However, with some margin, f = 20 MHz is selected. The equation gives an attenuation coefficient α = 4 dB / m. According to this, the attenuation is 40 dB at a distance of 10 m and 80 dB at a distance of 20 m, so that the locality of the magnetic field can be sufficiently achieved.

The ends of the parallel induction wire loop antenna 3 are preferably connected by a resistor Ro having a value substantially equal to the characteristic impedance of the antenna (see FIG. 12 (a)).

For example, if the frequency f is 20 MHz, the wavelength is 15 m. Assuming that the length of the guide wire loop antenna is 100 m, the length of the loop antenna becomes sufficiently longer than the wavelength. In such a case, if the conductor is short-circuited instead of the resistor Ro, as shown in FIG. 12 (b), the degree of coupling C between the induction wire loop antenna and the transmitter terminal becomes a wave every 1/2 wavelength. It becomes a standing wavy shape. For this reason, when the position of the transmitter terminal 4 comes to the position of the valley of the standing wave, it will not be coupled to the induction loop antenna. Therefore, as shown in FIG. 12 (a), when the terminal end of the induction wire loop antenna is connected by a resistance Ro substantially equal to the characteristic impedance, the coupling degree C between the induction wire loop antenna and the transmitter terminal becomes almost equal at any position. The transmitter terminal can be used at any location.

Note that the present invention is not limited to the above embodiment. Although the transmitter terminals in the above embodiments use the same ferrite bar antennas 42a and 42b orthogonally, any antennas having different directivity directions can be generally used. For example, as shown in FIGS. 13 and 14,
The loop antenna 42c and the ferrite antenna 42a may be used in combination. The number of antennas is not limited to two, but may be three or more. Various other design changes can be made without departing from the scope of the present invention.

<Effects of the Invention> As described above, according to the entry / exit counter of the present invention, due to the locality of the guide field generated from the transmitter terminal, only the guide wire loop antenna installed in the area where the entrant is located is provided. Since the voltage is induced, the central management device can identify the induction loop antenna from which the voltage has been induced and grasp the presence of the entrant.

Further, since the plurality of transmitting antennas installed with different directivity directions are driven at different phases, it is sufficient that the direction of the transmitter terminal with respect to the guide line loop antenna is sufficient. An alternating magnetic field of large magnitude links with the induction loop antenna.

Therefore, in a closed space such as an underground structure or an inside of a building, it is possible to accurately detect the location of the entrant without requiring the entrant to perform complicated work.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a transmitter terminal, FIG. 2 is a diagram showing a schematic configuration of an entry / exit counter, FIG. 3 is a graph showing a distance attenuation characteristic of an inductive field output from the transmitter terminal, FIG. 4 is a graph showing a vector synthesis state of each voltage induced from a radiation magnetic field of the transmission antenna. FIG. 5 is a diagram showing a transmission antenna placed at various angles in a magnetic field generated from a transmitter terminal. FIG. 7 is an external view of a transmitter terminal, FIG. 8 is a circuit configuration diagram of an antenna section of a transmitter terminal 4 using two ferrite antennas, FIG. 9 is a cross-sectional view of the road, FIG. 10 is a diagram showing a guide wire loop antenna arranged in the road, FIG. 11 is a cross-sectional view of the road, and FIG. 12 (a) is a terminal connected by a resistor. A perspective view showing a guide wire loop antenna FIG. 12 (b) is a perspective view showing an induction wire loop antenna with a short-circuited termination, FIG. 13 is a circuit configuration diagram of an antenna section of a transmitter terminal combining a ferrite antenna and a loop antenna, and FIG. FIG. 2 is a schematic internal configuration diagram of the machine terminal. 1 ... closed space, 3 ... guide wire loop antenna, 4 ...
... Transmitter terminal, 5 ... Signal transmission line, 6 ... Central control unit, 41 ... Oscillator, 42a, 42b, 42c ... Transmission antenna, 43 ... Phase shifter

Continued on the front page (72) Inventor Seichi Higuchi 1-3-1 Shimaya, Konohana-ku, Osaka-shi, Osaka Sumitomo Electric Industries, Ltd. Osaka Works (72) Inventor Yoshizo Shibano 1-1-1, Shimaya, Konohana-ku, Osaka-shi, Osaka No. 3 Sumitomo Electric Industries, Ltd. Osaka Works (72) Inventor Haruo Suzuki 1-3-1 Shimaya, Konohana-ku, Osaka, Osaka Prefecture Sumitomo Electric Industries, Ltd. Osaka Works (72) Inventor Yukio Nakayama Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Co., Ltd. 1-1-6 Uchisaiwaicho Nippon Telegraph and Telephone Corporation (72) Inventor Tatsuro Imada Nippon Telegraph and Telephone Corp. 1-16-1 Uchisaiwaicho Chiyoda-ku, Tokyo (72) Inventor Yukio Togo Omori-nishi, Ota-ku Tokyo 7-6-31 Sumiden Opcom Co., Ltd. Examiner Tokio Goto (56) References JP-A-62-287728 (JP, A) JP-A-63-301399 (JP, A) JP-A 1-216629 (JP, A) JP-A-2-268529 (JP, A) JP-B-55-5077 (JP, B2) (58) Field surveyed (Int.Cl. ⁶ , DB name) G06M 7/00-11/00 G08B 25/00

Claims (1)

(57) [Claims] An apparatus for detecting an occupant having a transmitter terminal in a closed space such as an underground structure or an inside of a building, wherein the transmitter terminal and the closed space are located in a space. An induction wire loop antenna that is installed so as to be substantially parallel to the road in each of the areas when divided vertically into a plurality of areas along the road, and detects an electromagnetic wave generated from the transmitter terminal; A central management device that identifies an area where an entrant is present by detecting a voltage induced on any of the induction wire loop antennas, wherein the transmitter terminals are installed with their directivity directions changed with respect to each other. A plurality of transmitting antennas, an oscillator for transmitting an AC signal having a frequency f equal to or lower than the lowest frequency fc that can propagate in the closed space, and providing a phase change to the AC signal from the oscillator. Therefore, there is a phase shifter that supplies drive signals having phases shifted from each other to each transmitting antenna.