JP5541461B2 - Communication device - Google Patents

Description

  The present invention relates to a communication device, and in particular, it is possible to easily extend a valid reception area where a portable device can be operated or triggered by electromagnetic waves transmitted from a base station to perform passage management and position management. The present invention relates to a communication device that can be used.

  When a portable device is equipped with a base station and a portable device and passes through the effective reception area of electromagnetic waves transmitted from the base station, the passage is detected and the passage management of the portable device, that is, the person or article accompanying the portable device is performed. Communication devices are known.

  FIG. 16 is a block diagram illustrating a communication device that performs passage management of a portable device using electromagnetic waves in a conventional LF band or UHF band. This communication apparatus includes a base station 1 and a portable device 2. The base station 1 periodically transmits electromagnetic waves in the LF band and the UHF band. When the portable device 2 passes through the effective reception area A of the electromagnetic wave transmitted from the base station 1, the portable device 2 receives the electromagnetic wave and is operated or triggered by an induced electromotive force or induced current due to an electromagnetic induction phenomenon of the electromagnetic wave. Operates and sends a response signal. The base station 1 receives the response signal transmitted from the portable device 2 and can know that the portable device 2 has passed through the effective reception area A. That is, the base station 1 can manage the passage of the portable device 2 by receiving the response signal transmitted from the portable device 2 with the effective reception area A as the passage management area.

The effective reception area A of the portable device 2 is an area within a certain distance from the base station 1 (transmission antenna), and the portable device 2 is an electromagnetic induction phenomenon of electromagnetic waves transmitted from the base station 1 within the effective reception area A. The portable device 2 can operate with the induced electromotive force or induced current.

There are two types of portable devices: passive portable devices and active portable devices. The passive portable device does not include a battery, and operates by using, as operating energy, an induced electromotive force or an induced current due to an electromagnetic induction phenomenon of an electromagnetic wave transmitted from a base station, and transmits a response signal.
An active portable device has a built-in battery and is normally in a sleep state, but is triggered by an induced electromotive force or induced current due to electromagnetic induction phenomenon of electromagnetic waves transmitted from a base station, and enters a normal operation state. A response signal is transmitted using the power of the power as operating energy.

The generation of induced electromotive force and induced current due to the electromagnetic induction phenomenon contributes particularly to the radiated magnetic field of the electromagnetic wave transmitted from the base station. That is, the effective reception area of the portable device is an area in which the radiated magnetic field of the electromagnetic wave transmitted from the base station is effective, and has a size corresponding to the frequency (wavelength) of the transmitted electromagnetic wave and the transmission power. In the range where the distance from the base station (transmitting antenna) is a quarter wavelength (λ / 4) of electromagnetic waves, the magnetic field is dominant over the electric field, but in order to generate induced electromotive force and induced current due to electromagnetic induction phenomenon, In consideration of the limitation of transmission power in the law, the distance range of about λ / 1000 is effective. Within this distance range is an area where the radiated magnetic field is effective, that is, an effective reception area of the portable device. For example, when using electromagnetic waves in the LF (Low Frequency) band of 100 kHz, the mobile device is operated or triggered by using the radiated magnetic field from the base station if it is within a distance of about 3 m from the base station (transmitting antenna). Can be operated.
For example, it is assumed that the effective reception area A is compared when the base station uses the LF band and when the UHF (Ultra-Hight Frequency) band is used. The LF band has a wavelength 100 to 1000 times longer than the UHF band, so if the base station has the same transmission power, the effective reception area of the LF band is much wider than the effective reception area of the UHF band, It can be seen that it is advantageous because the area in which the portable device can be operated or triggered is activated. Also, from the viewpoint of limiting transmission power under the Radio Law, the LF band is advantageous because it can output larger transmission power than the UHF band. However, the effective reception area of the portable device is still limited to a distance range of about λ / 1000 from the base station (transmission antenna).

  Regardless of whether a passive portable device or an active portable device is used in a communication device that performs passage management, the effective reception area of the portable device is an electromagnetic induction phenomenon caused by an electromagnetic wave transmitted from a base station, particularly a radiated magnetic field. It is limited to an area within a certain distance range from the base station (transmitting antenna) that can be operated by triggering or triggering the portable device with induced electromotive force or induced current. That is, the effective reception area is limited to a narrow area near the transmission antenna of the base station (the effective reception area of the LF band radiation magnetic field is about several meters).

  Conventionally, in order to expand the effective reception area in which a portable device can be operated or triggered by an induced electromotive force or induced current due to electromagnetic induction phenomenon of electromagnetic waves transmitted from a base station, the transmitter of the base station Improvements in circuit means have been made such as improving or increasing the output of the receiver, the reception sensitivity of the receiver of the portable device, the transmission efficiency of the transmission antenna of the base station, the reception efficiency of the reception antenna of the portable device.

  In order to expand the base station area and expand the effective reception area, there is also a method of arranging a plurality of transmission antennas on the base station side. An example of following this method in principle is a leaky cable used to expand the effective reception area in a special environment such as in a tunnel. In this case, in order to extend the effective reception area, instead of connecting the transmission antenna to the transmission circuit of the base station, a leakage cable is connected as an antenna. In this method, a dedicated transmission circuit for matching the impedance of the leakage wave cable and driving it is essential, but in principle, there is no difference from arranging a plurality of transmission antennas.

In general, there is no case in which the effective reception area is expanded by laying a leaky cable in communication devices that perform passage management indoors, in individual rooms, buildings, etc. As described above, the improvement is made by improving circuit means such as a transmission circuit and a transmission antenna of a base station and a reception circuit and a reception antenna of a portable device.
Conventionally, keyless entry devices for automobiles, RFID tag devices, IC card devices, etc. have been put to practical use as devices similar to the passage management system, but these devices all carry electromagnetic waves transmitted from base stations. An effective reception area is an area that can be directly received by a machine and operated by triggering or triggering the portable machine with an induced electromotive force or induced current due to an electromagnetic induction phenomenon.

  Non-Patent Document 1 describes an entrance / exit management system that activates a portable device using an LF signal and transmits a response signal from the portable device to a base station using a UHF signal. This entrance / exit management system includes a tag reader, an external antenna, and an active tag. Here, the tag reader includes an LF transmission / reception antenna, an LF transmission / reception circuit, a UHF antenna, a UHF reception circuit, a control circuit (CPU), an external antenna includes an LF antenna and an LF transmission circuit, an active tag includes an LF transmission / reception antenna, LF transceiver circuit, UHF antenna, UHF transmitter circuit, control circuit (CPU) and battery. If the battery is not depleted, the active tag is activated by the activation pattern of the LF signal from the tag reader, and transmits the UHF response signal including the ID number to the tag reader through the UHF transmission circuit. However, when the battery is depleted, the active tag operates with the electric power induced by the LF signal from the tag reader, and sends the binary FSK (Frequency Shift Keying) modulated LF signal to the tag reader. The tag reader receives this LF signal by the LF receiving circuit.

Naoshima Hideo et al., "Hands-free entry / exit management system using active tags" Panasonic Electric Works Technical Report (Vol.57 No.2), pp. 52-57

  Like a device similar to the above passage management system or an entrance / exit management system, an electromagnetic wave transmitted from a base station is directly received by a portable device, and the portable device is operated by an induced electromotive force or induced current due to an electromagnetic induction phenomenon, or Even if the frequency of electromagnetic waves transmitted from the base station is appropriately selected in the passage management system and the position management system that are activated by trigger activation, the effective reception area of the portable device is the radiated magnetic field from the transmission antenna of the base station. There is a problem that the passage management area is uniquely limited to the vicinity of the LF transmission antenna because it is narrow within a certain range of effective distance.

  Conventionally, as described above, in order to expand the effective reception area in which the portable device can be operated or triggered by the induced electromotive force or induced current due to the electromagnetic induction phenomenon of the electromagnetic wave transmitted from the base station, Improvements have been made to the circuit means to increase the output of the transmitter of the base station, the reception sensitivity of the receiver of the portable device, the transmission efficiency of the transmission antenna of the base station, the reception efficiency of the reception antenna of the portable device, etc. . However, when relying on such means, when it is necessary to expand the prescribed management area, it is necessary to review the circuit means constituting the passage management system as a whole, resulting in an increase in cost. There is a problem. Further, the effective reception area is within a certain distance range in which the radiated magnetic field is effective from the transmission antenna of the base station, and there is a problem that the area cannot be expanded freely.

  Making the passage management area and the position management area plural or arbitrarily shaped can be realized by providing a special transmission antenna in accordance with the shape of the passage management area on the base station side. However, in this case, not only the system configuration but also operation complexity such as timing control for transmitting an electromagnetic wave from each transmission antenna is caused, and the cost is further increased. In the method of extending the effective reception area by directly connecting a leaky cable instead of a transmission antenna to the transmission circuit of the base station, a dedicated transmission circuit for impedance matching to the leaky cable and driving it is essential. In addition, special cables such as leaky cables need to be buried. For this reason, this is a technique that is actually used only in a special environment such as in a tunnel.

  An object of the present invention is to use a transmitting magnetic antenna partly composed of a conductive member (specifically, a cable or the like), thereby enabling the effective reception area to be freely expanded at low cost to perform passage management and position management. An object of the present invention is to provide a communication device that can perform the above.

In order to solve the above-described problems, the present invention includes a base station and a portable device. The portable device receives an electromagnetic wave transmitted from the base station and operates or triggers to operate, and the portable device itself notifies that fact. Alternatively , electromagnetic induction phenomenon of electromagnetic waves transmitted from the transmission antenna of the base station in a communication device that performs passage management and position management (either or both of passage management and position management) by transmitting a response signal to the base station side The base station transmitting antenna and the conductive member in a positional relationship in which a part of the conductive member is included in the effective reception area where the portable device can be operated or triggered by the induced electromotive force or induced current by By arranging and electromagnetically coupling a part of the transmission antenna of the base station and the conductive member, the entire conductive member functions as a transmission antenna on the base station side for the portable device. It is characterized in that.
Here, another conductive member in an effective reception area where the portable device can be operated or triggered by an induced electromotive force or induced current due to an electromagnetic induction phenomenon of electromagnetic waves transmitted from the conductive member. The entire conductive member can also function as a transmitting antenna on the base station side.
As described above, the basic feature of the present invention is that the effective reception area on the base station side with respect to the portable device is expanded by arranging the transmission magnetic field antenna that is electromagnetically coupled to the transmission antenna of the base station.

  According to the present invention, in addition to the effective reception area from the original transmission antenna, an equivalent effective reception area based on the conductive member can be constructed, so that the reception effective area can be easily expanded. Thus, unlike the conventional leaky cable system, there is no need to embed a special cable such as a leaky cable and prepare a dedicated transmission circuit for driving the impedance by matching the impedance of the leaky cable.

  Here, in addition, other conductive members can be operated within the effective reception area where the portable device can be operated or triggered by an induced electromotive force or induced current due to electromagnetic induction phenomenon of electromagnetic waves transmitted from the conductive member. If a part is arranged and the entire conductive member functions as a transmission antenna on the base station side, the area can be further expanded (expansion of the area by forming a secondary area).

  Furthermore, since the arrangement and shape of the conductive member that can be used in the present invention are arbitrary, the effective reception area can be freely set and expanded. This also increases the degree of freedom in installation and arrangement of the base station.

  As the conductive member, a low resistance wire such as silver wire, copper wire, aluminum wire, iron wire, brass wire, stainless steel wire, etc., which can be obtained relatively easily can be used. It can be adjusted with a circuit-coupled attenuator.

It is a block diagram which shows embodiment of the communication apparatus which concerns on this invention. It is a figure which shows the specific example of the electromagnetic inductive coupling of LF transmission antenna and LF transmission magnetic field antenna of a base station. It is a figure which shows a mode that LF effective reception area is expanded. It is a figure which shows the donut-shaped effective receiving area formed when the path | route of an electroconductive member is made circular. It is a figure which shows the example of the ampang type effective receiving area formed when the path | route of an electroconductive member is made circular. It is a figure which shows the effective reception area of a square shape formed when the path | route of an electroconductive member is made into a square. It is a figure which shows the castera type | mold effective receiving area formed when the path | route of an electroconductive member is made into a square. It is explanatory drawing of the influence of the distributed constant circuit formed with an electroconductive member. It is a block diagram which shows other embodiment of the communication apparatus which concerns on this invention. It is a block diagram which shows embodiment of the base station and LF transmission magnetic field antenna which can be used by this invention. It is a block diagram which shows embodiment of the portable device which can be used by this invention. It is a time chart which shows an example of the timing of transmission and reception between the base station and the portable device in the communication apparatus according to the present invention. It is a flowchart which shows the basic operation | movement in the communication apparatus which concerns on this invention. It is a block diagram which shows one utilization form of the communication apparatus which concerns on this invention. It is a block diagram which shows the specific example to which the communication apparatus which concerns on this invention was applied. It is a block diagram which shows the communication apparatus which performs the conventional passage management.

  The present invention will be described below with reference to the drawings. In the following, the electromagnetic wave transmitted from the base station to the portable device is an LF band signal (LF signal), the electromagnetic wave transmitted from the portable device to the base station is a UHF band signal (UHF signal), and the portable device is The case of an active portable device will be described as an example.

  FIG. 1 is a block diagram showing an embodiment of a communication apparatus according to the present invention.

  The communication apparatus according to the present embodiment includes a base station 1, a portable device 2, and a conductive member 3. The base station 1 periodically transmits an LF signal and receives a UHF response signal transmitted from the portable device 2 in response thereto. The LF signal transmitted from the base station 1 includes an activation pattern for triggering activation of the portable device 2. The LF signal is encoded by, for example, Manchester encoding. Manchester encoding can be realized with a relatively simple circuit configuration because “1” is represented by a transition from a high potential to a low potential and “0” is represented by a transition from a low potential to a high potential. Therefore, it is preferable for encoding the LF signal in the base station 1.

  The portable device 2 receives the LF signal transmitted from the base station 1, operates by being triggered by an induced electromotive force or induced current due to an electromagnetic induction phenomenon, and transmits a UHF response signal to the base station 1. Here, since it is assumed that the portable device 2 is an active portable device, the portable device 2 is triggered by the induced electromotive force or induced current due to the electromagnetic induction phenomenon of the LF signal transmitted from the base station 1, Operates with the power of the built-in battery. In the illustrated area A, the portable device 2 receives the electromagnetic wave transmitted from the LF transmission antenna of the base station 1 as it is, and is an effective reception area that is triggered by an induced electromotive force or induced current due to an electromagnetic induction phenomenon, that is, a base station This is an area in which the radiated magnetic field of the electromagnetic wave transmitted from one LF transmitting antenna is effective (radiated magnetic field effective area), which is the same as the effective reception area A in the conventional communication apparatus shown in FIG. . The effective reception area A is an area where the portable device 2 can operate with induced electromotive force or induced current due to electromagnetic induction phenomenon of electromagnetic waves transmitted from the LF transmitting antenna of the base station 1, but induced induction due to electromagnetic induction phenomenon. For the generation of electric power or induced current, considering the limitation of transmission power under the Radio Law, the radiated magnetic field in the area of about 1/1000 of the wavelength λ of the electromagnetic wave transmitted from the base station is particularly effective. The area may be considered as an effective reception area A. Of course, if the transmission power of the base station 1 is increased, the effective reception area A becomes wider accordingly.

  A part of the conductive member 3 is included in the effective reception area A so as to be electromagnetically coupled to the LF transmission antenna of the base station 1, but the other part is arranged so as to be outside the effective reception area A. Established. Since the conductive member 3 is only required to function as an LF transmitting magnetic field antenna by generating electromagnetic coupling by electromagnetic induction in the radiated magnetic field of the electromagnetic wave transmitted from the LF transmitting antenna of the base station 1, the surface portion is coated. Alternatively, it may be coated with an insulator.

  When the base station 1 transmits an LF signal, an induced electromotive force or an induced current is generated in the conductive member 3 in the effective reception area A due to an electromagnetic induction phenomenon. As a result, the entire conductive member 3 functions as a magnetic field antenna for LF transmission on the base station 1 side. That is, the effective reception area is expanded. In FIG. 1, the extended effective reception area is shaded. Similarly, the extended effective reception area is indicated by shading in the following.

  The conductive member 3 may be one that has already been stretched as a building structure, or may be newly stretched to expand the effective reception area. Examples of building structures that can be utilized as the conductive member 3 include metallic window frames and door door frames made of iron or aluminum, and metallic foundations of buildings. When using what is already stretched as the conductive member 3, it is connected and circuited so that the conductive member 3 functions as a part of the antenna line of the LF transmission magnetic field antenna, and LF transmission of the base station 1 It is electromagnetically coupled to the antenna (an example is shown in FIG. 15). Since the conductive member 3 functions as a part of the LF transmitting magnetic field antenna, it is hereinafter referred to as the LF transmitting magnetic field antenna 3.

  In this embodiment, in order to improve the efficiency of electromagnetic induction coupling between the LF transmission antenna of the base station 1 and the magnetic field antenna 3 for LF transmission, the coil 4 is used as a part of the LF transmission magnetic field antenna 3, and this coil 4 is The base station 1 is arranged so as to face a coil that is a part of a series resonance circuit or a parallel resonance circuit of the LF transmission antenna of the base station 1.

  FIG. 2 is a diagram illustrating a specific example of electromagnetic inductive coupling between the LF transmission antenna and the LF transmission magnetic field antenna 3 of the base station 1. ATT5 is an attenuator. In FIG. 2, a magnetic circuit is formed between the LF transmission antenna of the base station 1 and the LF transmission magnetic field antenna 3 by disposing the same coil 4 as the coil of the resonance circuit of the LF transmission antenna of the base station 1. A path is formed by conductive members including 4. The coupling efficiency of electromagnetic induction can be easily changed by the distance between the coils and the turn ratio. Also, the LF effective reception area can be adjusted by controlling the induced current with ATT5.

  FIG. 3 is a diagram illustrating a state in which the electromagnetic induction coupling and the LF effective reception area of the LF transmission antenna and the LF transmission magnetic field antenna 3 of the base station 1 are expanded. As shown in FIG. 3, if the coil of the LF transmitting antenna of the base station 1 and the coil 4 forming a part of the LF transmitting magnetic field antenna 3 are brought close to, for example, 1 cm and both are electromagnetically coupled, the conductive member A LF effective reception area having a radius r is formed along Electromagnetic inductive coupling occurs when a part of the LF transmission magnetic field antenna 3 (coil 4) exists in the effective reception area A of the LF signal transmitted from the base station 1, but the LF transmission magnetic field is applied to the transmission antenna of the base station 1. It is preferable in terms of efficiency that a part of the antenna 3 (coil 4) is as close as possible.

  The shape of the path around the conductive member is not limited to a square. 4 and 5 show the LF effective reception area formed when the path of the conductive member is circular. When the path of the conductive member is circular, in general, as shown in FIGS. 4 (a) to 4 (c) (perspective view, top view, side view), an effective donut shape with a hole in the center is effective. A reception area is formed. FIG. 5 shows a case where the path length of the conductive member is shortened. In this case, as shown in FIGS. 5A to 5C (a perspective view, a top view, and a side view), an ampang-type effective reception area without a hole in the center is formed.

  Even in the case where the path of the conductive member is square, similarly, a mouth-shaped effective receiving area having a hole in the center and a castera-type effective receiving area having no hole in the center are formed. FIG. 6 ((a) perspective view, (b) top view, (c) side view) shows a mouth-shaped effective reception area generally formed when the path of the conductive member is square, FIG. 7 ((a) perspective view, (b) top view, (c) side view) is a castella-type effective receiving area with no hole in the center formed when the path length of the conductive member is shortened. Indicates.

  Further, as shown in FIG. 2, if an attenuator (ATT) is provided in the path of the LF transmission magnetic field antenna 3, the induced current in the LF transmission magnetic field antenna 3 can be reduced, and as a result, the LF transmission magnetic field is obtained. The magnetic field radiation radius r from the antenna 3 can be reduced. In this way, by providing an attenuator (ATT) in the path of the magnetic field antenna 3 for LF transmission, not only can the range r of the LF effective reception area be changed, but also the shape of the LF effective reception area is changed from the above-mentioned ampang type to donut type. It can also be easily changed from a castella shape to a mouth shape or vice versa.

  Hereinafter, the operational effects of the present invention will be described with specific numerical values raised.

If a square with a side of 4m is formed from a coated iron wire with a diameter of 0.9mm, a length of 16m, and an electrical resistance of 5Ω, and this is used as part of the path of the magnetic field antenna 3 for LF transmission, as shown in FIG. An empty castella-type LF effective reception area is formed.
Here, for example, if the user who owns the portable device enters this LF effective reception area, the portable device is triggered by receiving the LF radio wave and transmits a UHF response signal such as ID to the base station side. To do. If the user who owns the portable device goes out of the LF effective reception area, the portable device does not receive the LF radio wave, and the trigger is not activated. Therefore, the portable device does not transmit a UHF response signal to the base station.

  By utilizing the extended LF effective reception area in this way, it is possible to confirm the location and position of the person or object that owns the portable device.

  Further, as shown in FIG. 2, an attenuator (ATT) is provided in the path of the LF transmitting magnetic field antenna 3, and the induced current flowing in the LF transmitting magnetic field antenna 3 is reduced to form a covered iron wire that forms the LF transmitting magnetic field antenna. The radius r of the magnetic field radiating from can be reduced. This makes it possible to change from a castella-type LF effective reception area with no hole in the center to a mouth-shaped LF effective reception area with a hole in the center (for example, the resistance value of the attenuator is 1 kΩ) Thus, the radius r of the radiated magnetic field can be changed from 3 m to 1 m radius).

  This method of adjusting the effective reception area of the LF only involves reducing the induced current with an attenuator, so fluctuations in the LF frequency and changes in the Q value occur when an attenuator is provided in the antenna part of the LF transmission circuit of the base station. do not do. Therefore, even if the LF effective reception area is adjusted by changing the length of the conductive member 3 during installation or changing the shape from circular to square, impedance rematching in the transmission circuit of the base station 1 Is superior in that it is unnecessary.

  In an actual arrangement, the conductive member forms a distributed constant circuit. Therefore, when forming a partial circuit of the LF transmitting magnetic field antenna 3 using the conductive member, the path between the conductive member and the ground and the conductive circuit are formed. It is necessary to consider the capacitive coupling between the path of the structural member and the building.

  FIG. 8 is an explanatory diagram of the influence of a distributed constant circuit formed by a conductive member. As shown in FIG. 5A, the distributed constant circuit formed by the conductive member has a resistance component (R), a capacitance component (C), and an inductance component (L).

  The electromagnetic field energy induced in the magnetic field antenna 3 for LF transmission by electromagnetic induction from the LF transmission antenna of the base station 1 causes the high frequency component to move to the ground plane by this distributed constant circuit when passing through the path of this conductive member. Flowing. The magnetic field radiated from the conductive member is attenuated by the distributed constant circuit formed by the conductive member, and the radius r of the LF effective reception area formed thereby gradually decreases along the path. For example, when the path of the conductive member is rectangular as shown in FIG. 8B, the radius r of the magnetic field radiated from the coated iron wire is A along the path as shown in FIG. > B, D> C. In order to obtain a practical and sufficient LF effective reception area radius r, the resistance value and length of the conductive member to be used may be appropriately restricted, for example, 20 m and a resistance of 5Ω. If the circular resistance of the conductive member is about 10 KΩ or less, the entire conductive member can function as a transmitting antenna.

  As described above, since the effective reception area A of the base station 1 shown in FIG. 1 is expanded, the portable device 2 is located near the LF transmitting magnetic field antenna 3 even if it is outside the conventional effective reception area A. If there is, the LF signal transmitted from the base station 1 can be received via the LF transmitting magnetic field antenna 3 and triggered by an induced electromotive force or induced current due to an electromagnetic induction phenomenon. That is, the effective reception area is expanded to include the area of radius r from the magnetic field antenna 3 for LF transmission, and the portable device 2 is triggered by the LF signal transmitted from the base station 1 within the effective reception area. It is activated.

  When triggered by the LF signal transmitted from the base station 1, the portable device (active type) 2 operates with the power of the built-in battery and transmits a UHF response signal. Since the UHF response signal is a radio wave that can be delivered to the base station 1 only for communication, the response from the portable device 2 to the base station 1 does not require the effect of a magnetic field due to electromagnetic induction. The UHF band is more advantageous than the LF band in terms of the distance that the response signal can reach. The UHF response signal transmitted from the portable device is received by the base station 1.

  FIG. 9 is a block diagram showing another embodiment of the communication apparatus according to the present invention. In FIG. 9, the same or equivalent parts as in FIG. In the present embodiment, a part of the path of the LF transmitting magnetic field antenna 3 is grounded and shielded by using a magnetic shield material, so that the LF effective reception area A formed along the path of the conductive member is partially I try to squeeze it. In this way, by grounding using a member with relatively high availability such as a shielded wire, it is possible to partially adjust the LF effective reception area, and to further freely form the LF effective reception area. It becomes possible.

  FIG. 10 is a block diagram showing an embodiment of a base station and an LF transmitting magnetic field antenna that can be used in the present invention.

  The base station and LF transmission magnetic field antenna of this embodiment are LF transmission antenna 21, output adjustment volume 22, power amplifier 23, LF transmission circuit 24, base station control circuit 25, UHF reception circuit 26, UHF reception antenna 27, and power supply 28. Further, as described above, the LF transmitting magnetic field antenna 3 is provided. The LF transmission antenna 21, the power amplifier 23, the LF transmission circuit 24, the base station control circuit 25, and the UHF reception circuit 26 operate with power from the power supply 28. The output adjustment volume 22 may be an output adjustment attenuator.

  The LF transmission circuit 24 digitizes the signal transmitted from the base station control circuit 25, further modulates it, and transmits it as an LF signal. The LF signal includes an activation pattern for triggering the portable device. The LF signal may further include a communication LF signal such as an authentication signal. The LF transmission circuit 24 may have a function of encrypting the LF signal. The LF signal transmitted from the LF transmission circuit 24 is amplified by the power amplifier 3, further level-adjusted by the output adjustment volume 22, and then transmitted from the LF transmission antenna 21. The output volume 22 adjusts the output level transmitted from the LF transmission antenna 21, but can be omitted.

  The UHF receiving antenna 27 and the UHF receiving circuit 26 function as UHF receiving means for receiving a UHF response signal transmitted from the portable device. The UHF receiving circuit 26 also has a function of decrypting the UHF response signal if the UHF response signal transmitted from the portable device is encrypted. The UHF response signal received by the UHF receiving antenna 27 and the UHF receiving circuit 26 is sent to the base station control circuit 25.

  The base station control circuit 25 performs necessary control according to the UHF response signals received by the UHF reception antenna 27 and the UHF reception circuit 26, for example, in the case of an entrance / exit management device, control of opening / closing of the room entrance door. For this purpose, the base station control circuit 25 includes an interface for exchanging data with an external device. When the present invention is used in a system for performing passage management and location management, event information (information such as entry / exit of the portable device) based on the ID authentication result of the portable device is output as logging data from this interface to a log server or the like. That's fine.

  Further, the base station control circuit 25 controls the timing at which the LF transmission circuit 24 and the UHF reception circuit 26 operate. Although this timing control will be described in detail later, the timing at which the base station transmits the LF signal and the timing at which the UHF response signal is received do not overlap. At this time, the spatial propagation delay of the LF signal wraparound is also taken into consideration.

  FIG. 11 is a block diagram showing an embodiment of a portable device that can be used in the present invention.

  The portable device of this embodiment includes an LF reception antenna 31, an LF reception circuit 32, a portable device control circuit 33, a UHF transmission circuit 34, and a UHF transmission antenna 35. Here, since an active portable device is assumed, the portable device further includes a battery, but the illustration is omitted. The LF receiver circuit 32, portable device control circuit 33, and UHF transmitter circuit 34 are triggered by an induced electromotive force or induced current due to electromagnetic induction of electromagnetic waves transmitted from the base station (LF transmitting antenna or LF transmitting magnetic field antenna). Responds with the power of the built-in battery.

  The LF reception antenna 31 and the LF reception circuit 32 have a function of receiving the LF signal transmitted from the base station and demodulating the received LF signal. In addition, the LF receiving circuit 32 has a function of decrypting an LF signal transmitted from the base station if the LF signal is encrypted.

  The portable device control circuit 33 controls the timing at which the LF reception circuit 26 and the UHF transmission circuit 34 operate, and in accordance with the LF signal received via the LF reception antenna 31 and the LF reception circuit 32, Processing such as startup and display on the display is performed. Further, the UHF transmission circuit 34 and the UHF transmission antenna 35 are used to instruct the base station to transmit a UHF response signal including a predetermined command, ID data, and the like. The UHF transmission circuit 34 and the UHF transmission antenna 35 transmit a UHF response signal according to this instruction.

  In the timing control in which the LF reception circuit 32 and the UHF transmission circuit 34 operate, the timing at which the UHF response signal is transmitted and the timing at which the LF signal is received are not overlapped as in the base station. At this time, the spatial propagation delay of the wraparound of the UHF response signal is also taken into consideration. Specifically, timing control by the portable device control circuit 33 is performed in correspondence with timing control by the base station control circuit 25. This timing control can be realized by controlling using a counter, for example, based on the timing at which the signal transmitted from the base station is received by the portable device.

  FIG. 12 is a time chart showing an example of transmission and reception timings between the base station and the portable device in the communication apparatus according to the present invention.

  The base station repeats LF transmission timing (TSL) and pause. Further, the UHF response reception timing (TRU) is set in a preset period within the suspension period. At the LF transmission timing, an LF signal including an activation pattern is transmitted to the portable device, and at the UHF response reception timing, a UHF response signal from the portable device is waited. The pause is provided so as not to continuously occupy one frequency (according to the Radio Law).

  The portable device repeats LF reception timing (TRL) and pause. Also, the UHF response transmission timing (TSU) is set in a preset period within the suspension period. The LF reception timing, pause, and UHF response transmission timing correspond to the LF transmission timing, pause, and UHF response reception timing at the base station, respectively. However, the LF reception timing and pause period in the portable device are delayed by the delay correction amount τ1 with respect to the LF transmission timing and pause period of the base station, and the UHF response reception timing in the base station is the UHF response transmission of the portable device. The timing is delayed by a delay correction amount τ3. τ1 and τ3 are set to be longer than the time corresponding to the spatial propagation delay of the LF signal and UHF response signal.

  Further, the start time of the UHF response transmission timing is delayed by the delay correction amount τ2 from the end time of the LF reception timing. The delay correction amount τ2 is set to, for example, a value corresponding to one bit of the LF signal (data) in order to reliably avoid the UHF response signal from being affected by the reception of the LF signal on the portable device side. Furthermore, when the base station side operates the LF transmission and the UHF reception continuously, the base station prevents the UHF response signal from the portable device from entering the LF transmission circuit side and disturbing the next LF transmission. The UHF transmission timing on the portable device side is set so that the UHF reception timing can be ended with an interval (for example, several msec to several tens msec) before the start time of the LF transmission timing on the side. As a result, in the base station, there is an interval between the LF transmission timing and the UHF response reception timing, so that the interference due to the LF signal wrapping around to the UHF reception circuit side does not occur.

  The portable device receives an LF signal transmitted from the base station at the LF transmission timing at the LF reception timing, is triggered, and transmits a UHF response signal within the UHF response transmission timing as necessary. The base station waits for the UHF response signal transmitted from the portable device at the UHF response reception timing.

  FIG. 12 shows a time chart in the case where the LF signal is transmitted twice from the base station. Actually, the LF signal is transmitted from the base station to the portable device, and the LF signal is received. The operation of transmitting a UHF response signal from a trigger-activated portable device and receiving the UHF response signal at the base station may be completed once or repeated three or more times.

  As shown in the time chart shown in FIG. 12, when transmitting and receiving LF signals and UHF signals between the base station and the portable device, by providing delay correction amounts τ1, τ2, and τ3 at the transmission and reception timing, Noise caused by the electromagnetic field of the LF signal transmitted from the LF transmitting antenna circulates to the UHF receiver circuit, and each other induced on the conductor pattern between the antenna loop of the LF transmitting antenna and the antenna loop of the UHF receiving antenna. Noise due to the antenna effect due to the electromagnetic field can be suppressed. Also, in mobile devices, noise caused by the UHF response signal transmitted from the UHF transmission antenna wrapping around to the LF reception circuit, induced on the conductor pattern between the antenna loop of the LF reception antenna and the antenna loop of the UHF transmission antenna It is possible to suppress noise caused by the antenna effect due to the mutual electromagnetic field.

  In order to ensure security during communication between the base station and the portable device, it is preferable that the base station and the portable device have the function. To ensure security, for example, one or both of a method for individually identifying a base station and a portable device and a method for encrypting an LF signal can be used.

  In the method for individually identifying a base station and a mobile device, individual IDs are assigned to the base station and the mobile device in advance, and communication within the group is enabled based on the ID. To identify a base station belonging to a group capable of communication and a plurality of portable devices, register a combination table of the base station ID and a plurality of portable device IDs in the base station memory and the portable device memory respectively. The base station and the mobile device are individually identified using those IDs.

  Specifically, an LF signal including a base station ID is transmitted from the base station. If the base station ID included in the received LF signal is a base station ID in a communicable group including the mobile device, the mobile device starts normally and transmits a UHF response signal including the mobile device ID . If the base station ID is not applicable, the portable device does not respond and does not output unnecessary UHF radio waves. The base station receives the UHF response signal transmitted from the portable device, and recognizes that it is a correct UHF response signal if the included portable device ID is a portable device ID in a communicable group including its own base station.

  In the method for encrypting the LF signal, a general rolling code method using an M-sequence counter can be adopted. In the arrangement and extraction of the LF signal data to be transmitted and the arrangement and extraction of valid data, the base station and mobile device belonging to the group use unique correspondences and initial values, and the LF signal is encrypted using a method different from the simple rolling code method. The decryption may be performed.

  FIG. 13 is a flowchart showing basic operations in the communication apparatus according to the present invention. Here, a method of individually identifying the base station and the portable device is employed to ensure security.

  First, it is determined whether or not a trigger is given in the base station (S11). The trigger is given at each timing when the LF transmission timing (TSL) starts if the power of the base station is on. If no trigger is given, wait until a trigger is given. If a trigger is given, LF transmission timing (TSL) is reached, and the base station transmits an LF signal including its own base station ID (S12). The transmission of the LF signal is continuously performed during the LF transmission timing period (TSL), and ends when the LF transmission timing period (TSL) elapses. The portable device receives the LF signal transmitted from the base station and is activated by a trigger, whereby the LF reception circuit, the portable device control circuit, and the UHF transmission circuit are activated (S13 to S15).

  Next, the portable device performs validity authentication based on the IF signal transmitted from the base station (S16). If the validity is authenticated here, the portable device transmits a UHF response signal (S17). Specifically, as described above, the validity authentication is performed based on the base station IDs constituting the group, and the base station ID included in the received LF signal includes the base stations in the communicable group including the own mobile device. If it is a station ID, it starts normally and transmits a UHF response signal including the ID of the portable device. However, if the validity is not authenticated, the process returns to the step.

  The portable device transmits a UHF response signal within the UHF response transmission timing period (TSU) (S17). This UHF response signal includes the portable device ID. The base station receives the UHF response signal within the period (TRU) of the UHF response reception timing (S18). Here, the authenticity of the portable device is also performed using the base station ID included in the UHF response signal. Then repeat the steps as needed.

    FIG. 14 is a block diagram showing one usage pattern of the communication apparatus according to the present invention. This mode of use is an example in which two communication devices according to the present invention are used in a system for performing passage management and location management. As shown in FIG. 14, two communication devices of FIG. The base station 1 of the communication device is connected to the log server C. According to this mode of use, each base station 1 periodically sends out an LF signal (trigger signal), so that the LF effective reception area (zone A) of one communication device and the LF effective reception of the other communication device It is possible to determine whether or not there is a user who has a portable device inside and outside the area (zone B), and the user's location management and passage management can be performed in detail.

  Specifically, if the user who possesses the portable device enters the LF effective reception area (zone A) of one communication device, the base station 1 in zone A receives the response ID of the portable device. A determination signal is obtained from station 1, but if the user leaves zone A, the determination signal cannot be obtained. If the user who has the portable device enters the LF effective reception area (zone B) of the other communication device, the base station 1 in zone B receives the response ID of the portable device. Although a determination signal can be obtained, if the user leaves zone B, the determination signal cannot be obtained. Thereby, the location of the user can be determined.

  Since this method is used to determine whether a user who has a portable device is in a freely formed zone or not, it uses a conventional method for determining location based on radio field strength and multiple base stations. The position accuracy can be dramatically improved compared to the position determination system based on three-point surveying. Furthermore, since it can be determined that the user who has the portable device moves from Zone A to Zone B, for example, by placing Zone A and Zone B on the right and left of the corridor, the user can move from the right of the corridor. Whether it has moved to the left or from the left to the right can be determined only by the log data of the log server C connected to the base station 1.

  FIG. 15 is a block diagram showing a specific example to which the communication apparatus according to the present invention is applied.

  This specific example is an example in which the communication device according to the present invention is applied to a system for managing the entrance / exit of a person to / from a classroom of a school building shown in FIG. 15 (a). As shown in Fig. 2, when an area of a certain distance from the base station 1 (LF transmission antenna) is the effective reception area A of the portable device, the base station 1 (LF transmission antenna) It arrange | positions so that a part of frame may be included. Generally, a front door frame and a rear door frame of a classroom are conductively connected to a metallic window frame by a metallic foundation. The front door frame and the rear door frame are also made of metal and are conductive. By providing the coil 4 that is coupled to the coil of the resonance circuit of the LF transmitting antenna in the metallic window frame, effective electromagnetic induction coupling can be realized. If the circular resistance of the path through which the induced current due to the electromagnetic induction phenomenon flows is about 10 KΩ or less, the entire metallic parts such as the window frame, the front door frame, and the rear door frame function as a magnetic field antenna for LF transmission. In this way, if the building window frame or door frame is metallic in terms of the structure of the building, and they are conductively connected on a metallic foundation, the circular resistance of the path through which the induced current due to the electromagnetic induction phenomenon flows Therefore, it is not necessary to newly connect these members with metal to make them conductive. Even without forming the circuit path, the conductive part connected to the path can be viewed as almost the same potential as the connection part, so that this part can also function as the magnetic field antenna 3 for LF transmission. .

  In the above configuration, a part of the metallic window frame in the radiation magnetic field from the transmission antenna of the base station 1 is electromagnetically coupled to this radiation magnetic field. The metal window frame, front door frame and rear door frame are all conductive and they are electrically connected with conductive metal foundation, so the metal window frame, classroom front door frame and rear door The entire frame functions as a transmitting antenna (array) on the base station 1 side. That is, the effective reception area A is expanded to include areas in the vicinity of the front door frame and the rear door frame of the classroom.

Here, when the person carrying the portable device enters and exits through the front door or the rear door of the classroom, the portable device passes through the expanded effective reception area. Therefore, the active portable device is triggered by receiving the LF signal transmitted from the base station, operates with the power of the built-in battery, and transmits the UHF response signal to the base station. By receiving the UHF response signal transmitted from the portable device, the base station can know the entrance / exit of the person to / from the classroom. Even if the person carrying the portable device enters and exits from the window, the portable device receives the LF signal transmitted from the base station and operates by being triggered and transmits a UHF response signal to the base station. This can be known at the base station.
As an actual application example, an abnormal entry / exit and base station when entering / exiting from the front door, rear door or window without holding a portable device in cooperation with infrared sensors or surveillance cameras installed on the corridor side or window side. Judging by the side, it can be used easily in the form of sounding an alarm.

  Although the embodiment has been described above, the present invention is not limited to the above embodiment. For example, in the above embodiment, the signal transmitted from the base station to the portable device is an LF signal, and the signal transmitted from the portable device to the base station is a UHF signal. The frequency band of the signal to be processed is not limited thereto. For example, in the UHF band, the frequency is 10 times different between the 10 MHz class and the 1 GHz class, and the induced electromotive force or induced current due to the electromagnetic induction phenomenon varies depending on the frequency used. In general, if a frequency of 10 MHz class on the low frequency side is selected, it becomes more advantageous in terms of effective reception area than in the case of 1 GHz class frequency, but even in such a case, the effective reception area is further increased by arrangement of conductive members. The present invention can be applied to a communication device that operates a portable device with an induced electromotive force or an induced current due to an electromagnetic induction phenomenon of an electromagnetic wave transmitted from a base station. it can.

  The portable device is not limited to an active portable device, and may be a passive portable device. Unlike batteries built into active portable devices, passive portable devices require sufficient operating energy to operate the portable device by electromagnetic induction using a radiated magnetic field. Only the portable device can be operated. Further, in the method of using the portable device in the present invention, the LED is turned on, the character is displayed on the liquid crystal, the buzzer is displayed, even if the response signal is not transmitted to the base station. It is also effective to inform the user by a method such as making a sound.

  Further, the present invention can be applied not only to the passage of people and the like, but also to the passage management of articles by attaching a portable device to the article. Further, it is not always necessary to transmit a response signal from the portable device to the base station. For example, as described above, a portable device that has received an electromagnetic wave transmitted from a base station may emit light, display, alarm, or the like.

  Furthermore, if another sensor such as an infrared sensor is used in combination, a passage management system that permits passage of people and articles carrying portable devices, and does not allow passage of people and articles not carrying portable devices. Can also be configured. This can be realized by allowing the passage only when both the detection signal of the other sensor and the response signal are obtained from the portable device, that is, when the AND output of both signals is output.

1 ... base station, 2 ... mobile device, 3,3-1 to 3-3 ... conductive member, 4 ... coil, 5 ... attenuator, 21 ... LF transmitting antenna, 22 ... Output adjustment volume, 23 ... Power amplifier, 24 ... LF transmitter circuit, 25 ... Base station control circuit, 26 ... UHF receiver circuit, 27 ... UHF receiver antenna, 28 ..Power supply, 31 ... LF reception antenna, 32 ... LF reception circuit, 33 ... portable device control circuit, 34 ... UHF transmission circuit, 35 ... UHF transmission antenna, C ... log server

Claims (9)

It has a base station and a portable device, and the portable device receives an electromagnetic wave transmitted from the base station and operates or triggers to operate, and the portable device itself notifies that fact or transmits a response signal to the base station side. In the communication device that performs passage management and location management at
Part of the conductive member is included in the effective reception area where the portable device can be operated or triggered by the induced electromotive force or induced current due to the electromagnetic induction phenomenon of the electromagnetic wave transmitted from the transmitting antenna of the base station The base station transmitting antenna and the conductive member are arranged in a positional relationship and a part of the base station transmitting antenna and the conductive member are electromagnetically coupled to each other so that the entire conductive member is A communication device that functions as a transmission antenna.   When the wavelength of the electromagnetic wave transmitted from the transmission antenna of the base station is λ, the transmission antenna and the conductive member of the base station are arranged in a positional relationship in which a part of the conductive member is included in the area of λ / 1000. The communication apparatus according to claim 1.   A coil connected to the conductive member is disposed opposite to a coil constituting a resonance circuit of the transmission antenna of the base station, thereby electromagnetically coupling the transmission antenna of the base station and a part of the conductive member. The communication apparatus according to claim 1 or 2, wherein   The communication apparatus according to claim 1, wherein an attenuator is provided in a path of a transmission antenna formed including the conductive member.   The communication according to any one of claims 1 to 4, wherein a part of a path of a transmission antenna formed including the conductive member is grounded and shielded using a magnetic shield material. apparatus.   A part of another conductive member in an effective reception area where the portable device can be operated or triggered by an induced electromotive force or induced current due to an electromagnetic induction phenomenon of electromagnetic waves transmitted from the conductive member. The communication apparatus according to claim 1, wherein the entire conductive member also functions as a transmission antenna on a base station side.   The LF band signal is transmitted from the base station to the portable device, and the UHF band signal is transmitted from the portable device to the base station. Communication device.   7. The UHF band signal is transmitted from the base station to the portable device, and a different UHF band signal is transmitted from the portable device to the base station. 8. Communication equipment.   The communication apparatus according to any one of claims 1 to 8, wherein the electromagnetic wave transmitted from the base station is a Manchester-encoded digital signal.