JP2859397B2 - Inbound / outbound counting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an inbound / outbound counting device, and more specifically, in 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> Roads where cables are to be laid, underground tunnels, basements, or closed spaces in buildings can be accessed by humans as needed to perform work or work. Can be considered 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 to observe and grasp the number of students and their identification numbers (ID) in each area in the closed space.

That is, conventionally, as shown in FIG. 15, the closed space 1 such as a road is divided into appropriate areas, and infrared counters 21, 22, 23,... Passing was counted, and the number of counts of each counter was processed to control the number of persons present in each area.

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 visitors in each area will not match the calculations. 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 people 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 counter of the present invention, as shown in FIG. Electromagnetic waves at frequencies below fc (electromagnetic waves alternately change between a magnetic field and an electric field, so they can be regarded as waves of a magnetic field. Therefore, in the following, the expressions "AC magnetic field" or "magnetic field" are used to represent electromagnetic waves. Transmitter terminal 4 for generating (guidance field)
The inside of the closed space 1 such as a road is divided vertically into a plurality of regions along a road in the space, and the induction wire loop antenna 3 is disposed in each region so as to be substantially parallel to the road. A signal is guided from the terminal of the induction wire loop antenna 3 to the central control device 6, and the central control device 6 observes the induced voltage generated in each of the induction wire loop antennas 3.

As shown in FIG. 2, the transmitter terminal 4 includes a driver 41 for generating an alternating current having a frequency f equal to or lower than the lowest frequency fc.
And an antenna 42. When the antenna 42 is driven at a frequency f equal to or lower than fc, an AC magnetic field H is generated from the antenna 42. The AC magnetic field H is an induction field,
As shown in the figure, it has a characteristic that the intensity is rapidly attenuated with the distance D.

In addition, the above-mentioned guide wire loop antenna is composed of two parallel guide antenna wires, and the difference between the lengths of the two guide wires is 1 /.
It does not exceed four wavelengths.

With the above configuration, the magnetic field H generated from the transmitter terminal 4 is linked with only the guide wire loop antenna 3 installed in the area where the entrant is located due to its locality, and thus the guide wire loop antenna 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 presence area of the entrant.

Also, due to obstacles and the like, when forming a detour in one of the above-mentioned guide wire loop antenna, the difference between the lengths of the two guide wires should not exceed 1/4 wavelength, Since a detour is formed on the other side, the voltage output induced in the induction wire loop antenna does not greatly decrease as compared with the case where there is no detour.

Further, in the entry / exit counter of the present invention, when the closed space 1 has an elongated shape like a guide or a tunnel,
A guide line taking the induction wire loop antenna 3 is formed as a reciprocating line along the length direction of the tunnel, and an induced voltage is detected at one end thereof.
The other end is desirably terminated with a resistor having a value substantially equal to the characteristic impedance of the reciprocating line.

In this way, a standing wave can be prevented from standing on the induction loop antenna 3 by impedance matching, so that the induction loop antenna 3 can reliably detect the transmitter terminal 4 at any position. Can be.

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

FIG. 4 is a schematic diagram showing a specific example of an entrance / exit counting apparatus, in which a plurality of areas are set in a road, and parallel guide wire loop antennas 3a, 3b, 3c,. "). The entrants have their own transmitter terminals 4a, 4b, 4c,... (Hereinafter represented by reference numeral "4"). One end of the induction loop antenna 3 is connected to a signal transmission line.
.. (Represented by reference numeral “5”) are input to the switching circuit 7 through 5a, 5b, 5c,. Switching circuit 7
Performs switching at a fixed cycle, and any one of the signal transmission lines 5
Is connected to the central management device 6.

The ends of the parallel induction wire loop antenna 3 are connected by a resistor _R0 having a value substantially equal to the characteristic impedance of the antenna (see FIG. 5 (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 _R0 , the coupling degree C between the induction wire loop antenna and the transmitter terminal becomes a wave every 1/2 wavelength as shown in FIG. 5 (b). 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. 5 (a), when the terminal of the induction loop antenna is connected with a resistance _R0 substantially equal to its characteristic impedance, the coupling C between the induction loop antenna and the transmitter terminal is almost equal at any position. The transmitter terminal can be detected at any position.

FIG. 6 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 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. 7 (a), or may be installed along both side walls as shown in FIG. 7 (b). Figure (c)
As shown in FIG. 7, the antenna may be installed along the bottom surface of the road 1, or 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.

However, the guide wire loop antenna 3 is not
Even if it is installed on either side, near the floor, or the like, an existing obstacle such as an evacuation guide light, a ventilation fan, or a fluorescent light may be present on the actual road. In this case, when the arrangement of the induction wire loop antenna 3 is hindered, the antenna wires cannot be symmetrically laid at a predetermined interval.
At least one antenna line must be bypassed.

In this case, it is conceivable that a plurality of areas in the road are separated in front of the obstacle. However, if the length of the guide wire loop antenna 3 is long (may be 500 m), the obstacle may not be avoided. Is not so decisive.

Therefore, as shown in FIG. 8, a configuration was adopted in which the side of the parallel guided wire loop antenna 3 that hits an obstacle is bypassed. FIGS. 7A and 7B detour in the horizontal direction, and FIGS. 7C and 7D detour in the vertical direction. In the figure, the shape of the detour is rectangular or semicircular, but is not limited to this, and may be, for example, circular or waveform. Further, the present invention is not limited to the horizontal direction and the vertical direction, and may be detoured in any direction.

However, when only one of the guide wire loop antennas 3 is bypassed, the length of the two antenna wires is different, and the antenna output at the antenna terminal is reduced. This is because there is a phase difference between the voltages induced in the left and right antenna lines.

This is described in the graph of FIG. The horizontal axis represents a value obtained by converting the difference between the two antenna lengths into a wavelength, and the vertical axis represents the antenna output. The output is reduced by 3 dB when shifted by λ / 4, and is completely eliminated when shifted by λ / 2.

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

Figure 10 shows that the distance X between the left and right antenna lines is 80 cm and the length is 60
An actual measurement example of VSWR when five detours are provided in the m-guide wire loop antenna is shown. A terminating resistor _R0 is connected to the induction loop antenna to prevent a standing wave from being generated in advance. The width w of the detour (see FIG. 8) was set to X / 4 = 20 cm. Each of the three graphs changes the value of the terminating resistor _R0 .

From the graph, it can be seen that the VSWR is 2 or less in the range of 10 to 20 MHz even if there is a detour, and it is sufficiently practical.

FIG. 11 shows the frequency characteristics of the spatial noise level (equivalent noise figure) up to several tens of MHz standardized by CCIR (in the figure, A is a business area, B is a residential area, C is a rural area, D is Shows a quiet rural area, CCIR Report 25
FIG. 12 shows the frequency characteristics of the equivalent noise figure actually measured in the actual road. The higher the frequency, the lower the noise. Therefore, in order to reduce the influence of city noise, it is preferable to select the frequency f as high as possible in a range smaller than fc.

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. 13 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. Sixth
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 the inductive field where it is located. 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.

For example, if the width of the road is W = 5m, fc = 30MH from the formula
Although it becomes z, select f = 20 MHz with some margin. From the equation, an attenuation coefficient α = 4 dB / m is obtained. According to this, 1
At 0m away, 40dB, at 20m away, 80dB attenuation, so
The locality of the magnetic field is fully achieved.

In this entry / exit counter, the transmitter terminal 4 has an identification number (hereinafter, referred to as "ID"), and not only detects the presence of an entrant but also performs individual identification of the entrant. .

FIG. 14 shows the format of a modulated signal of a magnetic field generated from the transmitter terminal 4. The preamble, the synchronization bit, and the start bit are followed by the ID bit representing the participant's affiliation and number, the error detection bit, and the end bit. (PAD). In the central control unit 6, the signal transmission line 5
If each AC voltage signal received through the demodulator is demodulated and the ID bit contained therein is decoded and detected, it is possible to determine the affiliation of the entry and its individual determination.

Table 1 shows each area A, B, C,
., And a table of the IDs (001, 002, 003,...) Of the entrants in the area.

<Effects of the Invention> As described above, according to the entry / exit counter of the present invention, the guidance field generated from the transmitter terminal has a locality, so that the guidance line loop antenna installed in the area where the entrance is located. Induces voltage in linkage with only The central management device can identify the induction loop antenna in which the voltage has been induced, and specify the area where the induction loop antenna is installed as the existing area of the entrant.

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

In addition, even when a detour is formed in one of the guide wire loop antennas due to an obstacle or the like, the difference between the lengths of the two guide wires is reduced to 1/4 by forming a detour in the other. Since the wavelength is not exceeded, the voltage output induced in the induction loop antenna does not drop significantly even when there is no detour, and the signal of the transmitter terminal is detected with sufficient strength. it can.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of an entry / exit counter of the present invention, FIG. 2 is a diagram showing an outline of a transmitter terminal, and FIG. 3 is a graph showing a distance attenuation characteristic of an inductive field output from the transmitter terminal. Fig. 4 is an overall view showing an embodiment of an entry / exit counting device, Fig. 5 (a) is a perspective view showing an induction wire loop antenna whose ends are connected by resistors, and Fig. 5 (b) is a short-circuited end. FIG. 6 is a cross-sectional view of a road, FIG. 7 is a diagram illustrating an example of the arrangement of the guide line loop antenna in the road, and FIG. FIG. 9 is a perspective view showing the shape of a detour portion when one detour portion is formed, FIG. 9 is a graph of antenna output with respect to a difference between two antenna wire lengths, and FIG. Fig. 11 is a graph showing actual measured values of VSWR when a part is formed. Is a graph showing the frequency characteristics of the spatial noise level (equivalent noise figure) up to several tens of MHz, FIG. 12 is a graph showing the frequency characteristics of the equivalent noise figure measured in an actual road, and FIG. 13 is a transmission chart. 14 is a cross-sectional view showing the positional relationship between the transmitter terminal and the induction wire loop antenna. FIG. 14 is a signal format of a modulation signal for modulating an alternating magnetic field generated from the transmitter terminal. FIG. 15 is a conventional input / output using an infrared counter. It is a figure showing a person counting device. 1 ... closed space, 3 ... induction wire loop antenna, 4 ... transmitter terminal, 6 ... central control unit, 42 ... transmission antenna, 41 ... driver

Continuation of the front page (72) Inventor Haruo Suzuki 1-3-1 Shimaya, Konohana-ku, Osaka-shi, Osaka Inside the Osaka Works, Sumitomo Electric Industries, Ltd. No. 3 Sumitomo Electric Industries, Ltd. Osaka Works (72) Inventor Seichi Higuchi 1-3-1 Shimaya, Konohana-ku, Osaka City, 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 Co., Ltd. 7-6-31 Examiner at Sumiden Opcom Co., Ltd. Tokio Goto (56) References JP-A-1-216629 (JP, A) JP-A-62-287727 (JP, A) JP-A-63-301399 (JP, A) JP-A-2-268529 (JP, A) JP-B-55-5077 (JP, B2) (58) Field surveyed (Int. Cl. ⁶ , DB name) G06M 7/00-11/04 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 for identifying a region where an entrant is present by detecting a voltage induced in any of the induction wire loop antennas, wherein the transmitter terminal includes: a transmission antenna; And a driver for driving a transmitting antenna with an AC signal having a frequency f equal to or lower than the lowest frequency fc that can propagate the signal. The induction wire loop antenna includes two parallel induction antenna wires. And out who counting device the difference between the lengths of the two guide wire is characterized in that it does not exceed a quarter wavelength.