JP5700218B2 - Position detection system - Google Patents

Description

  The present invention relates to a position detection system that detects the position of a portable device by receiving electromagnetic waves transmitted from a base station with a portable device, and in particular, even if the effective reception areas of portable devices for a plurality of base stations overlap. The present invention relates to a position detection system that can easily and clearly detect the position of a machine.

  When a portable device is provided in the effective reception area of electromagnetic waves transmitted from the base station, the presence of the portable device, that is, the position of the portable device, that is, the person or article accompanying the portable device is detected. Position sensing systems are known.

  FIG. 16 is a block diagram illustrating a position detection system that manages the presence of a portable device using electromagnetic waves in a conventional LF band or UHF band. This location management system includes a base station A and a portable device B.

  Base station A periodically transmits electromagnetic waves in the LF band and the UHF band. The effective reception area of portable device B with respect to base station A is the area where portable device B can receive an electromagnetic wave transmitted from base station A and operate or be triggered by an induced electromotive force or induced current due to the electromagnetic induction phenomenon. Zone A. The effective reception area Zone A is an area within a certain distance range from the transmission antenna of the base station A. Hereinafter, the base station including the transmission antenna is referred to as a base station, and similarly, the mobile station including the reception antenna is referred to.

  When the portable device B is present in the effective reception area Zone A, the portable device B receives an electromagnetic wave transmitted from the base station A and operates or is triggered by an induced electromotive force or induced current due to an electromagnetic induction phenomenon of the electromagnetic wave. , Send a response signal.

  The base station A can detect that the portable device B exists in the effective reception area Zone A by receiving the response signal transmitted from the portable device B. That is, the base station A can detect that the portable device B exists in the effective reception area Zone A by receiving a response signal transmitted from the portable device B with the effective reception area Zone A as the management area.

  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. On the other hand, 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. The battery is operated using the power of the battery as operating energy, and a response signal is transmitted.

  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 effective area of the radiated magnetic field, that is, an effective reception area of the portable device with respect to the base station. 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.

  When comparing the effective reception area when using the LF band for the electromagnetic waves transmitted by the base station and using the UHF (Ultra-High Frequency) band, the wavelength of the LF band is 100 to 1000 times that of the UHF band. Since 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, and there is an area that can be operated by operating or triggering the mobile device. wide. Therefore, the use of the LF band is advantageous in terms of the effective reception area. 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 for the position detection system, the effective reception area of the portable device is the electromagnetic wave transmitted from the base station, particularly the induction caused by the electromagnetic induction phenomenon caused by the radiated magnetic field. This is a range where the portable device can be operated or triggered by power or induced current, and is limited to an area within a certain distance from the base station. That is, the effective reception area is limited to a narrow area near the base station (the effective reception area of the LF band radiation magnetic field is about several meters).

  FIG. 17 shows the relationship between the distance from the LF transmission antenna and the magnetic field strength, and FIG. 18 shows the effective reception communication area of the portable device for the base station (LF transmission antenna). As shown in FIGS. 17 and 18, the magnetic field intensity of the electromagnetic wave transmitted from the base station A decreases with the cube of the distance from the base station A. The effective reception area Zone A is a range in which a magnetic field strength equal to or higher than the reception sensitivity threshold of the portable device is obtained. In the case of electromagnetic waves in the LF band, the actual effective reception area Zone A is limited to a range of about a few meters in radius near the transmission antenna of the base station A in consideration of the reception sensitivity of the portable device.

  Non-Patent Document 1 describes an entrance / exit management system in which an electromagnetic wave transmitted from a base station is directly received by a portable device, and the portable device is triggered and operated by an induced electromotive force or induced current due to an electromagnetic induction phenomenon. Yes.

  Patent Document 1 relates to a position information providing system. For example, a sensor provided near each guest room in a hotel receives a weak radio wave emitted from a non-contact tag, detects an IC tag number, and installs the sensor. It is described that information on the location of the facility user is obtained from the information and the detected IC tag number.

  Patent Document 2 discloses an active RFID tag and a dynamic management system that simultaneously detects a tag position and a passing direction by transmitting and receiving electromagnetic waves, and transmits electromagnetic waves (or radio waves) of different position signals to transmission areas A and B in an area boundary C. (Areas where A and B partly overlap) are formed, and carrier waves of position signals to transmission areas A and B are in opposite phases to each other, and within area boundary C, the same part of each other position signal is Depending on the position signal received by the tag, the position signal to the transmission areas A and B is made to be in phase and the position signals are superimposed in the area boundary C. Detecting the tag position and passing direction from the change of the RF signal is described.

  Patent Document 3 relates to a dynamic management system that detects the movement of an ID tag. A main trigger line for detecting a person (ID tag) that has entered the main trigger area is provided in the main trigger area, and is close to the main trigger area. A cancel trigger line is provided in the cancel trigger area, a unique ID number output from the ID tag is received using the magnetic field generated by the main trigger line as a trigger, and the movement of the ID tag is detected, and the magnetic field generated by the main trigger line and the cancel trigger line is triggered. As described above, detecting the moving direction of the ID tag based on the reception time difference when the unique ID number output from the ID tag is received is described.

JP 2003-61131 A JP 2007-299052 A JP 2008-152373 A

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

  By forming a plurality of effective reception areas by a plurality of base stations, it is possible to detect in which effective reception area the portable device exists. In this case, if the base stations (transmission antennas) are provided apart from each other and the effective reception areas of the portable device for each base station do not overlap with each other, but are separated from each other and independent, they exist in each effective reception area. Since only the portable device operates or triggers and responds, the effective reception area where the portable device exists can be distinguished and detected. However, in this case, it is necessary to consider the arrangement of base stations (transmission antennas) so that a sufficient non-response area (an area where the portable device does not respond) is ensured between the effective reception areas.

  As shown in FIG. 19, the effective reception areas Zone A1 and Zone A2 of the portable device having no directivity with respect to the base stations A1 and A2 having no directivity are generally circular around the base stations A1 and A2. It becomes an area. When the base stations (transmitting antennas) A1 and A2 are provided close to each other, a part of the effective reception areas Zone A1 and Zone A2 of the portable device for the base stations A1 and A2 overlap each other to generate a boundary area Zone C. Since the effective reception areas Zone A1 and Zone A2 change depending on the radio wave environment, the boundary area Zone C also changes accordingly. In this boundary area Zone C, the mobile device responds to both base stations A1 and A2, responds to either one, or stops responding to either, so the area where the mobile device is located is clearly defined It cannot be determined by dividing. For example, when the space between guest rooms is the boundary area Zone C, it becomes a problem because the user cannot clearly know which guest room is located. This is because, in the boundary area Zone C, the electromagnetic field intensity of the signal transmitted from the base stations A1 and A2 is equal to or higher than the reception sensitivity threshold of the portable device, and thus the portable device is transmitted from any of the base stations A1 and A2. This is because it is possible to respond to signals. In this case, there is not much difference between the electromagnetic field strengths of the signals transmitted from the two base stations A1 and A2, and this difference cannot be clearly determined and separated when the portable device receives. The same applies when three or more base stations are at a close distance.

  For example, when the trigger activation signals transmitted from a plurality of base stations are not synchronized, the portable device responds to any trigger activation signal in the boundary area where the effective reception areas overlap with each other. The area in which the aircraft is located cannot be identified separately. In addition, when trigger activation signals transmitted from a plurality of base stations are synchronized, it is not possible to determine which trigger activation signal is caused by a response from a portable device in a boundary area where effective reception areas overlap each other. Therefore, the area where the portable device is located cannot be clearly distinguished from the response. In other words, the boundary area where the effective reception areas overlap each other is an “indeterminate area of discrimination” in which the position of the portable device is ambiguous.

  In the position information providing system of Patent Document 1, sensors that receive weak radio waves emitted by IC tags are arranged near each guest room. However, when an IC tag is present in the boundary area of a guest room, both sides of the room are affected by the radio wave environment. There is a phenomenon that the intensity of the radio waves received by the sensors in the guest room becomes almost the same or reverses. For this reason, there may be a case where it is not possible to clearly determine which room the facility user is in.

  Although the above phenomenon can be prevented by reducing the intensity of the radio waves emitted by the IC tag or lowering the reception sensitivity of the sensor, such an approach unnecessarily narrows the effective reception area. Since there is a risk of widening the response area, it is not practical. Therefore, the technique of adjusting the intensity of the transmitted radio wave and the reception sensitivity of the sensor cannot be said to be an effective technique for solving the ambiguity of discrimination at the boundary portion of the effective reception area.

  In the dynamic management system of Patent Document 2, the same part of the position signals received within the area boundary C is canceled, or different parts of the position signals received within the area boundary C are superimposed. For example, the area boundary C is discriminated. However, in this case, the phase of the carrier wave of the position signal received within the area boundary C needs to be opposite or in phase with each other. However, in an actual electromagnetic wave environment including fading, there is no guarantee that the phase of the carrier wave of the position signal received within the area boundary C is opposite or in phase with each other. That is, the same portion of the position signal transmitted to the transmission areas A and B and received by the tag in the area boundary C is not surely canceled or the superimposed position signal is not necessarily superimposed. Therefore, in the dynamic management system of Patent Document 2, there are cases where the tag position and the passing direction cannot be accurately detected.

  In the dynamic management system of Patent Document 3, there is no problem of erroneous detection or erroneous determination due to overlapping of adjacent detection areas. In this dynamic management system, the cancel trigger line is provided close to the main trigger area. However, the main trigger area is determined exclusively on the magnetic field strength by the main trigger line, and the magnetic field by the cancel trigger line is the main trigger area. It is only taken into account when defining the trigger area, and does not clearly define the main trigger area. As described above, in the method of simply determining the detection area on the magnetic field intensity by one trigger line, it is difficult to determine that the detection areas are clearly separated when the detection areas are adjacent to each other. It is not possible to reliably prevent false detection and misjudgment. Furthermore, in order to generate a signal in the coil of the ID tag by the magnetic field generated by the trigger line, it is necessary for the ID tag carrier to move quickly or switch the direction of the current flowing through the trigger line.

  An object of the present invention is to provide a position detection system that can easily and clearly detect the position of a portable device even if the effective reception areas of the portable device for a plurality of base stations overlap.

In order to solve the above-described problems, the present invention includes a base station and a portable device, and the portable device receives a signal transmitted from the base station and notifies that effect or transmits a response signal to the base station. In the position detection system that detects the position of the portable device, the effective reception area of the portable device with respect to the transmission antennas of the plurality of base stations forms a boundary area by overlapping a part of the adjacent effective reception areas, A dummy transmission antenna that transmits a signal to an area including a boundary area is provided, and different signals are periodically transmitted from the transmission antennas of the plurality of base stations and the dummy transmission antenna at different timings; When a signal transmitted from the dummy transmitting antenna is received within a certain period, the base station transmits the signal within the period. It is a signal that is not to respond to received, thereby, is basically characterized in that non-response area that separates the effective receiving area of the neighboring includes the boundary area with one another are formed.

  In the present invention, dummy transmission antennas for transmitting signals are provided in the boundary areas where the effective reception areas of the portable device with respect to the transmission antennas of a plurality of base stations overlap with each other, and signals different from the transmission antennas and dummy transmission antennas of each base station are provided. Are periodically transmitted at different timings, and when the portable device receives a signal transmitted from the dummy transmitting antenna within a certain period, it receives the signal transmitted from the base station within the one period. However, since no response is made to the base station, a non-response area including a boundary area can be formed.

  Thereby, the area where a portable device responds to each base station can be clearly separated. This eliminates the need to place each base station while measuring the radio field intensity so that the effective reception areas of the portable device do not overlap. Since the area that is not to be clearly divided and there is no area in which the portable device responds vaguely, it is possible to easily and clearly detect in which area the portable device exists.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a block diagram showing a first embodiment of a position detection system according to the present invention, and FIG. It is the block diagram (a) which shows 2nd Embodiment of the position detection system based on this invention, and its explanatory drawing (b). It is a time chart which shows the operation | movement in 1st and 2nd embodiment. It is a block diagram which shows 3rd Embodiment of the position detection system which concerns on this invention. It is a figure which shows the effective reception area and non-response area which are formed in 3rd Embodiment. It is a block diagram which shows further 4th Embodiment of the position detection system which concerns on this invention. It is a figure which shows the effective reception area and non-response area which are formed in 4th Embodiment. It is a circuit diagram which shows the structure in the case of forming an effective reception area using the electroconductive member which electromagnetically couples with the LF transmission antenna of a base station. It is a figure which shows the effective receiving area formed when the path | route of an electroconductive member is circular. It is a figure which shows the effective receiving area formed when the path | route of an electroconductive member is 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 embodiment of the base station and LF transmission magnetic field antenna which can be used with the position detection system which concerns on this invention. It is a block diagram which shows embodiment of the portable device which can be used with the position detection system which concerns on 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 position detection system according to the present invention. It is a flowchart which shows the fundamental operation | movement in the position detection system which concerns on this invention. It is a block diagram which shows the conventional position detection system. It is explanatory drawing which shows the relationship between the distance from LF transmission antenna, and magnetic field intensity. It is explanatory drawing which shows the effective reception communication area of the portable apparatus with respect to a base station (LF transmission antenna). It is explanatory drawing which shows a boundary area in case the effective reception area of the portable apparatus with respect to an adjacent base station overlaps mutually.

  The present invention will be described below with reference to the drawings. The present invention particularly relates to a position detection system that detects the position of a portable device by an active tag method that can activate and operate the portable device by electromagnetic waves (mainly magnetic fields) transmitted from a base station. It is assumed that the portable device is an active portable device, the electromagnetic wave transmitted from the base station is an LF band signal (LF signal), and a UHF band signal (UHF response signal) is transmitted from the portable device.

  FIG. 1 is a block diagram (a) and an operation explanatory diagram (b) showing a first embodiment of a position detection system according to the present invention.

  The position detection system of the first embodiment includes base stations A1 and A2. Each base station A1, A2 includes an LF transmitting antenna and a UHF receiving antenna, respectively. The LF transmission antenna transmits an LF signal (LF band electromagnetic wave), and the UHF reception antenna receives a UHF response signal (UHF band electromagnetic wave) transmitted from the portable device.

  The portable device receives the LF signal transmitted from the base stations A1 and A2. Assuming that base stations A1 and A2 exist independently, areas where the electromagnetic field strength of the LF signal transmitted from base stations A1 and A2 is above a certain level (reception sensitivity threshold of the mobile device) It becomes an effective area, that is, an effective reception area. In FIG. 1, the effective reception areas of the mobile devices for the base stations A1 and A2 are Zone A1 and Zone A2, respectively, and are circular areas centering on the base stations A1 and A2. However, when the base stations A1 and A2 are provided close to each other, the effective reception areas Zone A1 and Zone A2 partially overlap to form a boundary area Zone C.

  In the boundary area Zone C, there is no significant difference in the electromagnetic field strength of the LF signal transmitted from the base stations A1, A2, so it is detected that the mobile device is located in the effective reception area Zone A1 of the base station A1, depending on the radio wave environment, The location detection operation of the area where the mobile device is located is ambiguous, because it is detected that it is located in the effective reception area Zone A2 of the base station A2, or the LF signal transmitted from the base stations A1 and A2 cannot be received separately There is a problem of becoming.

In order to solve this problem, in the present invention, a base station (LF transmission antenna) D is provided in the boundary area Zone C. Base station D transmits an LF signal to an area including boundary area Zone C. Area base station D transmits the LF signal can be set to an arbitrary shape by Rukoto adjusting the shape and transmission power stretch around the cable constituting the loop antenna. As will be described later, LF signals having different codes are periodically transmitted from the base stations A1, A2, and D at different timings. When the portable device receives an LF signal transmitted from the base station D within a certain period, it does not transmit a response signal even if it receives a trigger activation signal transmitted from the base stations A1 and A2 within the one period. It is set in advance as follows.

  The base stations A1, A2, and D periodically transmit LF signals (trigger activation signals) having different codes at different timings. The LF signals transmitted by the base stations A1, A2, and D may be the same or close frequencies. When the portable device receives an LF signal transmitted from the base station D within a certain period, the portable device does not respond even if it receives an LF signal transmitted from the base stations A1 and A2 within the period due to the above setting. That is, the portable device has a mechanism that gives priority to reception of the LF signal transmitted from the base station D and does not respond. The portable device receives the LF signal transmitted from the base station D because the electromagnetic field intensity of the LF signal transmitted from the base station D is equal to or greater than the reception sensitivity threshold of the portable device, that is, the portable device for the base station D. This is a case where the portable device is located within the effective reception area of the device. In FIG. 1, this area is indicated by Zone D.

  Thereby, the base station D forms a non-response area Zone D including a boundary area Zone C between the effective reception areas Zone A1 and Zone A2. The LF transmission antenna of the base station D is not for detecting the position of the portable device, but is a dummy transmission antenna for forming the non-response area Zone D.

  Note that “non-response area Zone D ≧ boundary zone Zone C” is maintained even if the radio wave environment changes. Further, in order to make the non-response area as narrow as possible, the non-response area Zone D is preferably close to the shape of the boundary area Zone C.

  With the above settings, the mobile device does not respond to the base stations A1 and A2 in the non-response area Zone D, and the effective reception area excluding the non-response area Zone D (hereinafter referred to as the effective reception area) Zone A1 ', Zone It responds to the base stations A1 and A2 only when it is located at A2 ′. In this way, the communication zone is clearly divided into three areas, the effective reception areas Zone A1 'and Zone A2' and the non-response area Zone D, so that the effective reception areas Zone A1 and Zone A2 are close or overlapping. Even if the base stations A1 and A2 are provided, the position detection operation of the portable device does not cause ambiguity, and the positions can be clearly distinguished and known. That is, the non-response area Zone D is formed by the base station (dummy transmission antenna) D at the boundary between the effective reception areas Zone A1 and Zone A2, and the independent effective reception areas Zone A1'A and Zone A2 ' Therefore, the position of the detected portable device does not become ambiguous and can be clearly determined.

  In FIG. 1, the base station (dummy transmission antenna) C is provided only at the boundary between the effective reception areas Zone A1 and Zone A2. In addition, the effective reception areas Zone A1 and Zone A2 are vertically and horizontally The effective reception areas Zone A1 ′ and Zone A2 ′ can also be defined by providing base stations (dummy transmission antennas) in appropriate portions such as the above portions.

  The method of the present invention is to determine whether or not the mobile device is located within an area, and each area is clearly separated from each other, so a conventional position determination method based on radio wave intensity and a plurality of base stations are used. Compared with the three-point surveying position determination system, the position of the portable device can be determined easily and clearly.

  As described above, if the method of dividing the communication zone by the base station (dummy transmission antenna) is used, for example, as shown in FIG. 2, the effective reception area Zone A1 'Zone A2' By setting the zone immediately below the door as the non-response area Zone D, it is possible to easily and reliably determine the entrance / exit of the door.

  When a person carrying a portable device enters the room through the door, the portable device is first identified by the effective reception Zone A1 ', once it does not respond in the non-response area Zone D, and then is identified by the effective reception area Zone A2'. . Thereby, it can be determined that a person carrying the portable device has entered the room. Similarly, when a person carrying a portable device exits through the door, the portable device is first identified in the effective reception area Zone A2 ', and once responds in the non-response area Zone D, then the effective reception area Zone A1' Is determined. Thereby, it can be determined that the person carrying the portable device has left the room. In addition, when the person carrying the portable device returns without passing through the door, only the effective reception area Zone A1 'or only the effective reception area Zone A2' is determined, so it is determined that the person has not passed through the door. it can.

  FIG. 2 is a block diagram (a) and an operation explanatory diagram (b) showing a second embodiment of the position detection system according to the present invention.

  In the first embodiment shown in FIG. 1, the effective reception areas Zone A1 and Zone A2 of the portable device for the base stations A1 and A2 are circular, but in the second embodiment shown in FIG. It is different in shape. The substantially rectangular effective reception areas Zone A1 and Zone A2 can be easily formed by extending cable-shaped antenna wires in a loop shape. By providing the base station (dummy transmission antenna) D in the boundary area Zone C where the effective reception areas Zone A1 and Zone A2 overlap each other, it is possible to form substantially rectangular effective reception areas Zone A1 ′ and Zone A2 ′. . The substantially rectangular effective reception areas Zone A1 ′ and Zone A2 ′ are preferable for detecting the position of the portable device located in the passage or in the room. Others are the same as those in the first embodiment, and a description thereof will be omitted.

  FIG. 3 is a time chart showing the operation in the first and second embodiments. As shown in FIG. 3, the base stations A1, A2, and D transmit LF signals periodically (cycle T seconds) at different timings. The transmission of the LF signal can be performed by a spontaneous trigger method in which transmission is performed periodically or an external trigger method in which transmission is performed after a human sensor detects that a person has entered a predetermined area. In addition, by transmitting and receiving synchronization signals between the base stations A1, A2, and D, transmission of LF signals can be set at different timings.

  The trigger activation LF signal transmitted from the base station A1 includes, for example, a trigger activation signal of Wake-up code = 1, and the trigger activation LF signal transmitted from the base station A2 includes, for example, Wake-up code = The trigger activation LF signal including two trigger activation signals and transmitted from the base station D includes, for example, a signal of Wake-up code = 3. These trigger activation LF signals are 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 of LF signals at the base stations A1, A2, and D.

  Mobile devices located in the effective reception areas Zone A1 'and Zone A2' are triggered by the LF signal of Wake-up code = 1 and Wake-up code = 2 transmitted from the base stations A1 and A2, and UHF response Send a signal. Note that if the LF signal transmitted from the base stations A1 and A2 includes a timing instruction for the portable device to respond, the timing at which the portable device responds to the base stations A1 and A2 can be determined. According to this, the base stations A1 and A2 can receive only the UHF response signal for the own station through a window of a predetermined timing.

  On the other hand, the portable device located in the non-response area Zone D receives the LF signal of Wake-up code = 3 transmitted from the base station D. Since Wake-up code = 3 is different from Wake-up code = 1 and Wake-up code = 2 of the LF signal transmitted from the base stations A1 and A2, no UHF response signal is transmitted according to the above setting.

  FIG. 3 shows that the base station D, the base station A1, and the base station A2 transmit the trigger activation LF signal in order, and the portable device receives the trigger activation LF signal from the base station D, and simultaneously receives it. Shows a case where no response is made to the trigger activation LF signal from the base station A1 and the trigger activation LF signal received from the base station A2 thereafter, but the base stations A1, A2 within one cycle , The order of transmitting the trigger activation LF signal from D is not limited to this. Therefore, the order in which the portable device receives trigger activation signals from the base stations A1, A2, and D in the non-response area Zone D is merely an example. In short, in any order, the mobile device receives the trigger activation LF signal from the base station D within a certain period, so that the trigger activation from the base stations A1 and A2 within that period. Even if the LF signal for use is received, no response should be made.

  As described above, in the present invention, the base station (dummy antenna) is provided in the boundary area where the mobile device effective reception areas Zone A1 and Zone A2 overlap with the base stations A1 and A2, thereby forming the non-response area Zone D. In the non-response area Zone D, a mechanism for controlling the portable device so as not to respond is used. In the effective reception areas Zone A1 'and Zone A2', the portable device receives a signal including a valid wake-up code or parent ID from the base stations A1 and A2, and a valid wake-up code or parent ID from the base station D. Because it does not receive a signal that contains, it responds to the base station, and the non-response area Zone D receives a signal containing a valid wake-up code or parent ID from the base station D, so it is valid from the base stations A1 and A2. Even if a signal including a wake-up code or parent ID is received, it does not respond to the base station. With such a simple area configuration mechanism, an effective reception area can be constructed, and a position detection system or the like can be configured by utilizing the fact that a base station and a portable device can communicate only within this effective area.

  FIG. 4 shows a third embodiment of the position detection system according to the present invention, and FIG. 5 shows an effective reception area and a non-response area formed thereby.

  The position detection system according to the third embodiment includes ten base stations A1 to A9, D. The base stations A1 to A9, D transmit different signals (signals with different codes) that can be distinguished from each other at different timings. This can be realized by sending a synchronization signal from the base station D to the base stations A1 to A9. The synchronization signal is transmitted from the base station D to the base stations A1 to A9, for example, as illustrated.

  The effective reception area of the portable device with respect to the base stations A1 to A9 is circular, and a part thereof overlaps to form a boundary area. The base station D (LF transmission antenna) is provided in the boundary area, and forms a non-response area Zone D including the boundary area. In the non-response area Zone D, the portable device receives the LF signal transmitted from the base station D, and therefore does not respond even if it receives the LF signals transmitted from the base stations A1 to A9.

  As described above, the independent effective reception areas Zone A1 ′ to Zone A9 ′ not including the boundary area are formed by the non-response area Zone D. The entire non-response area Zone D can be formed by dividing the non-response area Zone D into several parts and forming each divided non-response area with a single loop antenna line. For example, the non-response area Zone D can be easily formed by forming a non-response area between rows and columns with a loop antenna line of each one and combining them. Alternatively, the entire non-response area Zone D may be formed by looping a series of antenna wires.

  As shown in FIG. 4, the base stations A1 to A9 are provided with a UHF reception antenna that receives a UHF response signal returned from the portable device. Log data from each base station A1 to A9 (indicated by arrows derived from each base station A1 to A9) based on the UHF response signal received by each UHF receiving antenna is partially omitted. Are sent from the base stations A1 to A9 to the log server L. The log server L can continuously know in which effective reception area of the effective reception areas Zone A1 ′ to ZoneA9 ′ the portable device is located from the log data transferred from the base stations A1 to A9.

  As described above, in the configurations shown in FIGS. 4 and 5, the communication zone is clearly divided into the independent effective reception areas Zone A1 ′ to Zone A9 ′ and the non-response area Zone D. Even if the effective reception areas of the portable device are formed so as to be close to each other or overlap, the position detection operation of the portable device does not cause ambiguity, and the position can be clearly known.

  Specifically, if a person who has a portable device enters the effective reception area Zone A1 ′ of one base station A1, the base station A1 of the effective reception area Zone A1 ′ receives the response ID of the portable device. If a determination signal is obtained from the station A1, and a person with a portable device enters the effective reception area Zone A2 'of the other base station A2, the base station A2 of the effective reception area Zone A2' Since the ID is received, a determination signal is obtained from the base station A2. These determination signals are collected by the log server L as log data. Here, nine effective reception areas Zone A1 to Zone A9 are formed, and non-response areas Zone D are formed at the boundary portions thereof to form independent effective reception areas Zone A1 'to Zone A9'. By the log data collected by the log server L, it is possible to reliably determine even the complicated movement of the person who has the portable device. In general, by forming three or more independent effective reception areas, it is possible to determine movements inside and outside the area, such as the entry and exit of a person with a portable device.

  FIG. 6 is a block diagram showing a fourth embodiment of the position detection system according to the present invention, and FIG. 7 shows an effective reception area and a non-response area formed by the fourth embodiment.

  The fourth embodiment differs from the third embodiment (FIGS. 4 and 5) in that the effective reception area is substantially rectangular. The substantially rectangular effective reception areas Zone A1 to Zone A9 can be formed by stretching loop antenna wires in a substantially rectangular shape. The effective reception areas Zone A1 to Zone A9 and the effective reception areas Zone A1 'to Zone A9' can be made rectangular, so that the non-response area Zone D can be narrowed, and the independent effective reception areas Zone A1 'to Zone A9' It is preferable because it can be matched to the shape such as. Others are the same as those of the third embodiment, and thus description thereof is omitted.

  The effective reception area of the portable device with respect to the base station can also be formed using a conductive member that is electromagnetically coupled to the LF transmission antenna of the base station. This is not only for base stations for forming non-response areas (base station D in the above embodiment), but also for base stations for forming effective reception areas (base stations A, A1 to A9 in the above embodiment). Is also applicable. Thereby, the effective reception area of each base station and an independent effective reception area can be formed in arbitrary shapes.

  FIG. 8 is a circuit diagram showing a configuration when an effective reception area is formed using an LF transmission magnetic field antenna of a conductive member that is electromagnetically inductively coupled to the LF transmission antenna of the base station.

  The same coil 3 is placed close to the coil 2 of the LF transmitting antenna (resonance circuit) of the base station A, for example, within 1 cm so as to form a magnetic circuit. A path including a coil 3 is formed by a conductive member.

  When the base station A transmits an LF signal, an induced electromotive force or an induced current is generated in the conductive member due to an electromagnetic induction phenomenon. As a result, the entire conductive member functions as the LF transmitting magnetic field antenna 1 of the base station A. The conductive member only needs to function as the LF transmitting magnetic field antenna 1 by generating electromagnetic coupling due to electromagnetic induction in the radiated magnetic field of the electromagnetic wave of the LF signal transmitted from the LF transmitting antenna of the base station A. It may be painted or coated with an insulator. The electromagnetic induction coupling efficiency can be changed by the distance between the coils 2 and 3, the facing area, and the turn ratio.

  If an attenuator (ATT) 4 is provided in the middle of the path of the conductive member, the effective reception area can be adjusted by controlling the induced current. This method of adjusting the effective reception area of the LF is only to reduce the induced current with the attenuator 4, so the LF frequency fluctuation and Q value change that occur when an attenuator is installed in the antenna part of the LF transmission circuit of the base station A Does not occur. Therefore, even if the LF effective reception area is adjusted by changing the length of the conductive member during installation or changing the shape from circular to square, the impedance of the transmission circuit of the base station A can be reduced. It is excellent in that rematching is unnecessary.

  FIG. 9 is a diagram showing a specific example of an effective reception area formed by the LF transmitting magnetic field antenna tener 1 of FIG. FIGS. 9 (a) to 9 (c) show a perspective view, a top view, and a side view, respectively, and by extending the conductive member in a circular shape, the effective shape of the circular shape is radiated from the path of the conductive member by the radiation magnetic field of radius r. A reception area can be formed.

  FIG. 10 is a diagram showing another specific example of the effective reception area formed by the LF transmitting magnetic field antenna tener 1 of FIG. FIGS. 10 (a) to 10 (c) show a perspective view, a top view, and a side view, respectively, and the conductive member is stretched in a substantially rectangular shape so that it is substantially squared by a radiated magnetic field having a radius r from the path of the conductive member. An effective receiving area having a shape can be formed. For example, a square with a side of 4 m is formed by a coated iron wire with a diameter of 0.9 mm, a length of 16 m, and an electrical resistance of 5 Ω, and this is used as part of the path of the magnetic field antenna 1 for LF transmission, so that a substantially rectangular LF effective reception is achieved. An area can be formed.

  In practice, since the conductive member forms a distributed constant circuit, the capacitive coupling between the path by the conductive member and the ground is taken into account when forming the magnetic field antenna 1 for LF transmission using the conductive member. There is a need.

  FIG. 11 is an explanatory diagram of the influence of a distributed constant circuit formed by a conductive member. As shown in FIG. 11A, 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 energy induced in the magnetic field antenna for LF transmission by electromagnetic induction from the LF transmission antenna of the base station causes a high frequency component to flow through the ground plane by the distributed constant circuit when passing through the path of the conductive member. The radius r of the magnetic field radiated from the conductive member is attenuated by the distributed constant circuit formed by the conductive member, and gradually decreases along the path. For example, when the path of the conductive member is rectangular as shown in FIG. 11 (b), the radius r of the magnetic field radiated from the coated iron wire is A along the path as shown in FIG. 11 (c). > B, D> C. In order to obtain a practical and sufficient LF effective reception area, 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.

  FIG. 12 is a block diagram showing an embodiment of a base station that can be used in the position detection system according to the present invention.

  The base station of this embodiment includes an LF transmission antenna 11, an output adjustment volume 12, a power amplifier 13, an LF transmission circuit 14, a base station control circuit 15, a UHF reception circuit 16, a UHF reception antenna 17, and a power source 18. The power amplifier 13, the LF transmission circuit 14, the base station control circuit 15, and the UHF reception circuit 16 are operated by power from the power supply 18. The output adjustment volume 12 may be an output adjustment attenuator.

  Here, the magnetic field antenna for LF transmission using a conductive member is not shown, but if the conductive member is electromagnetically coupled to the coil of the LF transmission antenna 11, an LF transmission magnetic field antenna that extends the effective reception area can be easily obtained. Can be configured.

  The LF transmission circuit 14 digitizes the signal transmitted from the base station control circuit 15, further modulates it, and transmits it as an LF signal. When the base station is for forming an effective reception area, the LF signal includes an activation pattern for triggering activation of the portable device. The LF signal can further include a communication LF signal such as an authentication signal. The LF transmission circuit 14 may have a function of encrypting the LF signal. The LF signal transmitted from the LF transmission circuit 14 is amplified by the power amplifier 13, further level-adjusted by the output adjustment volume 12, and then transmitted from the LF transmission antenna 11. The output volume 12 is for adjusting the output level transmitted from the LF transmission antenna 11, but may be omitted.

  The UHF receiving antenna 17 and the UHF receiving circuit 16 function as UHF receiving means for receiving a UHF response signal transmitted from the portable device. The UHF receiver circuit 16 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 17 and the UHF receiving circuit 16 is sent to the base station control circuit 15.

  The base station control circuit 15 performs necessary control according to the UHF response signal received by the UHF reception antenna 17 and the UHF reception circuit 16, for example, in the case of an entrance / exit management device, controls the 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. In a system that performs position management and passage management, event information (information such as entry / exit of a portable device) based on the ID authentication result of the portable device may be sent to the log server as logging data from this interface.

  Further, the base station control circuit 15 controls the timing at which the LF transmission circuit 14 and the UHF reception circuit 16 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. 13 is a block diagram showing an embodiment of a portable device that can be used in the position detection system of the present invention.

  The portable device of this embodiment includes an LF reception antenna 21, an LF reception circuit 22, a portable device control circuit 23, a UHF transmission circuit 24, and a UHF transmission antenna 25. Here, since an active portable device is assumed, the portable device further includes a battery, but the illustration is omitted.

  The LF reception circuit 22, the portable device control circuit 23, and the UHF transmission circuit 24 are triggered by an induced electromotive force or an induced current due to an electromagnetic induction phenomenon of an electromagnetic wave transmitted from the base station, and perform a response operation with the power of the built-in battery. However, as described above, when the mobile device is located within the non-response area, the portable device receives the LF signal transmitted from the dummy transmitting antenna at a certain level or higher, and therefore receives the LF signal transmitted from the base station. Does not respond.

  The LF reception antenna 21 and the LF reception circuit 22 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 22 has a function of decrypting an LF signal transmitted from the base station if the LF signal is encrypted.

  The portable device control circuit 23 controls the timing at which the LF reception circuit 22 and the UHF transmission circuit 24 operate, and in accordance with the LF signal received via the LF reception antenna 21 and the LF reception circuit 22, Processing such as startup and display on the display is performed. Further, it instructs the base station to transmit a UHF response signal including a predetermined command, ID data, and the like via the UHF transmission circuit 24 and the UHF transmission antenna 25. The UHF transmission circuit 24 and the UHF transmission antenna 25 transmit a UHF response signal according to this instruction.

  In the timing control in which the LF reception circuit 22 and the UHF transmission circuit 24 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, the timing control by the portable device control circuit 23 is performed corresponding to the timing control by the base station control circuit 15. 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. 14 is a time chart showing an example of transmission and reception timings between the base station and the portable device in the position detection system according to the present invention. The position detection system according to the present invention includes a plurality of base stations. Here, the operation when the portable device is located within the effective reception area of one base station (base station for forming the effective reception area) is described. Is shown.

  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. However, as described above, when the mobile device is located within the non-response area, the portable device receives the LF signal transmitted from the dummy transmitting antenna at a certain level or higher, and therefore receives the LF signal transmitted from the base station. Does not respond. The base station waits for the UHF response signal transmitted from the portable device at the UHF response reception timing.

  FIG. 14 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. 14, when transmitting and receiving an LF signal and a UHF signal 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 due to antenna effects due to mutual electromagnetic fields.

  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. In order to ensure security, for example, one or both of a method of individually identifying a base station and a portable device and a method of 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. In addition, as described above, when the mobile device is located within the non-response area, the portable device receives the LF signal transmitted from the dummy transmission antenna at a certain level or higher, and therefore receives the LF signal transmitted from the base station. Does not respond. 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 of 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. 15 is a flowchart showing a basic operation in the position detection system 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). However, as described above, when the mobile device is located within the communication invalid area, the portable device receives the LF signal transmitted from the dummy transmitting antenna at a certain level or higher, and therefore receives the LF signal transmitted from the base station. Even if the trigger is not activated.

Next, the portable device performs legality authentication based on L F 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.

  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 the effective reception area than a frequency of 1 GHz class.

  Further, in the method of using the portable device according to the present invention, it is confirmed that there is a portable device within the effective reception area without transmitting a response signal to the base station, LED lighting, character display on the liquid crystal, and buzzer sound. A method of notifying the user by ringing is also effective. As described above, it is not always necessary to transmit a response signal from the portable device to the base station.

  Further, the present invention can be applied not only to the passage of people such as entering and leaving, but also to the management of the position and passage of an article if a portable device is attached to the article. Furthermore, it is possible to configure a passage management system in which another sensor such as an infrared sensor is used in combination and the passage is permitted only when both the detection signal of the other sensor and the response signal are obtained from the portable device.

1 ... LF transmission magnetic field antenna, 2,3 ... coil, 4 ... attenuator, 11 ... LF transmission antenna, 12 ... output adjustment volume, 13 ... power amplifier, ...・ LF transmission circuit, 15 ... Base station control circuit, 16 ... UHF reception circuit, 17 ... UHF reception antenna, 18 ... Power supply, 21 ... LF reception antenna, 22 ... LF reception Circuit, 23 ... portable device control circuit, 24 ... UHF transmission circuit, 25 ... UHF transmission antenna, A, A1 to A9 ... base station, B ... portable device, L ... log server

Claims (8)

A position that has a base station and a portable device, and that detects the position of the portable device by receiving a signal transmitted from the base station and responding by notifying that effect or transmitting a response signal to the base station In the detection system,
The effective reception area of the portable device for the transmission antennas of a plurality of base stations forms a boundary area by overlapping some of the adjacent effective reception areas with each other,
A dummy transmitting antenna for transmitting a signal to an area including the boundary area is provided;
Different signals are periodically transmitted from the transmission antennas of the plurality of base stations and the dummy transmission antenna at different timings,
When the portable device receives a signal transmitted from the dummy transmitting antenna within a certain period, it does not respond even if it receives a signal transmitted from the base station within the one period. Thus, a non-response area including the boundary area and separating the adjacent effective reception areas from each other is formed.   2. The position detection according to claim 1, wherein a signal is first transmitted from a dummy transmitting antenna within one period, and subsequently, signals are sequentially transmitted from a plurality of base stations at different timings. system.   The position detection system according to claim 1 or 2, wherein there are three or more effective reception areas, and the dummy transmission antenna is provided in a boundary area between them.   4. The dummy transmission antenna includes a conductive member connected to a coil that is electromagnetically coupled to be opposed to a coil constituting a resonance circuit of the dummy transmission antenna. The position detection system described in 1.   The position detection system according to claim 4, wherein the conductive member is stretched in a substantially square shape, thereby forming a non-responsive area having a substantially square shape.   6. The LF band signal is transmitted from the transmission antennas of the plurality of base stations and the dummy transmission antenna, and a UHF band response signal is transmitted from the portable device. The position detection system according to one.   6. The UHF band signal is transmitted from the transmission antennas of the plurality of base stations and the dummy transmission antenna, and a response signal of the UHF band is transmitted from the portable device. The position detection system according to one.   The position detection system according to claim 1, wherein the signal transmitted from the base station is a Manchester-encoded digital signal.