JP2010108039A - Wireless communication system for automatically switching mode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an IC tag communication system capable of switching a communication mode of a reader from an active mode to a passive mode without troubling a user. <P>SOLUTION: The IC tag communication system has a sensor and transmits an inquiry signal in the active mode. The reader communicating with a tag in the active mode transmits the inquiry signal in the passive mode instead of the active mode and communicates with the tag in the passive mode when the sensor detects that a person enters in a predetermined range adjacent to the own device. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an IC tag system capable of communication in both an active mode and a passive mode, and more particularly to a technique for improving convenience of switching between an active mode and a passive mode.

The IC tag system includes a tag including an IC including data and an antenna, and a reader that reads and writes data of the tag, and there are an active mode and a passive mode as communication modes between the tag and the reader.
In these communication modes, the communication distance between the tag and the reader is different, and is usually several meters in the active mode and several centimeters in the passive mode. That is, in the active mode, communication is possible only by passing within a distance of several meters from the reader, but in the passive mode, it is necessary to hold the tag over the reader.

Therefore, for example, an authentication system that strictly manages entry / exit uses the passive mode, and an authentication system that simply manages traffic uses the active mode.
Here, there are readers that support either the active mode or the passive mode, and readers that support these two modes. In a reader that supports two communication modes, the user can switch from the active mode to the passive mode by pressing a button installed on the front surface of the reader.

  A reader that supports both of these communication modes normally operates in the active mode, and the mode is switched, for example, when the battery runs out in the active mode that operates with the battery built in the tag. Or when it is desired to authenticate with a tag that supports only the passive mode in which power is generated by radio waves from the reader and communicates. Usually, a tag that operates in the active mode has a communication function in the passive mode so that it can be authenticated even when the battery runs out.

However, for the user, in order to be able to communicate with the user's own tag, there is an annoyance that a troublesome operation such as pressing a reader button is required.
Here, there is a technique of automatically switching to perform communication in the active mode without the user's trouble when communicating in the passive mode (see Patent Document 1). Specifically, when the tag passes through the security gate, the gate corresponding to the reader communicates in passive mode to authenticate the tag and transmit a trigger signal to the tag. The tag receives the trigger signal from the gate and changes the passive mode to the active mode.

Certainly, if this technique is used, the communication mode can be switched without bothering the user.
JP 2007-199967 A

However, this technique switches the tag communication method from the passive mode to the active mode, and cannot be applied when the reader communication method is switched from the active mode to the passive mode.
In other words, when switching the communication mode of the reader from the active mode to the passive mode, communication cannot be performed within the communication range of the active mode, so the mode is switched to the passive mode. Therefore, the reader and the tag do not communicate before switching the communication mode. This is because the reader cannot receive the trigger signal.

  Therefore, an object of the present invention is to provide a communication system that can switch the communication mode of a reader from an active mode to a passive mode without bothering the user.

  In order to solve the above problems, a wireless communication system of the present invention includes an interrogator and a responder, and the interrogator is a wireless communication system that performs wireless communication with the responder, and the wireless communication system includes a sensor. The interrogator includes a question transmission unit that repeatedly transmits an interrogation signal including information indicating that communication is performed in the first communication mode; and a predetermined range that is within a reach of the interrogation signal and that is close to the interrogator. Detecting means for detecting that the detection target has entered using the sensor, and the question transmitting means indicates that communication is performed in the first communication mode when the detection means detects the entry of the detection target. A question signal including information indicating that communication is performed in the second communication mode instead of the information, and the responder includes a question receiving means for receiving the question signal, and a response signal for the received question signal. A response transmission means for transmitting, the response transmission means indicates communication in the first communication mode when the received question signal is an inquiry signal including information indicating that communication is performed in the second communication mode. A response signal having a narrower transmittable range than that for an inquiry signal including information is transmitted.

  The response transmission means includes a low-frequency transmission means for transmitting a low-frequency signal and a high-frequency transmission means for transmitting a high-frequency signal, and a response signal for an inquiry signal including information indicating that communication is performed in the second communication mode May be transmitted by the low-frequency transmission means, and when transmitting a response signal to the interrogation signal including information indicating that communication is performed in the first communication mode, the high-frequency transmission means may be used. .

  The responder further includes a battery and a power generation unit that generates power by receiving the interrogation signal, and the response transmission unit is information indicating that the interrogation signal communicates in the first communication mode. Is included, a response signal is transmitted using the battery as a power source, and a response signal is transmitted using the power generated by the power generation means when information indicating that communication is performed in the second communication mode is included. It is good to do.

Since the wireless communication system according to the present invention has the above-described configuration, it can detect that a detection target has entered a predetermined range near the interrogator. The communication mode can be switched and communication with the responder can be performed. The user switches the mode automatically just by approaching the interrogator.
At this time, the communication mode is switched from the first communication mode in which the transmission range of the response signal transmitted by the responder is wide to the narrow second communication mode.

That is, when approaching the interrogator, since it was not possible to respond in the first communication mode, it is assumed that the user would like to respond in the second communication mode, and the second communication mode is entered without waiting for an instruction from the user. Convenience when switching and switching the communication mode is improved.
In addition, when the question transmission means repeatedly transmits a question signal including information indicating that communication is performed in the second communication mode for a predetermined time, the question transmission means is used in the first communication mode instead of the information indicating that communication is performed in the second communication mode. It is good also as transmitting repeatedly the question signal containing the information which shows communicating.

Further, when the question transmission means transmits a question signal including information indicating that communication is performed in the second communication mode a predetermined number of times, the question transmission means performs communication in the first communication mode instead of information indicating that communication is performed in the second communication mode. It is good also as transmitting repeatedly the question signal containing the information which shows doing.
Thus, when a question signal including information indicating that communication is performed in the second communication mode is transmitted for a predetermined time or a predetermined number of times, a question signal including information indicating that communication is performed in the first communication mode is automatically transmitted. Therefore, even if the detection target remains in the predetermined range, the second communication mode can be returned to the first communication mode.

  That is, if, for some reason, the user stays in the vicinity of the interrogator for a long time, or if an object placed near the interrogator is detected, the second communication mode remains. The user who wants to respond cannot respond. It is possible to avoid such inconvenience by automatically returning to the first communication mode when a predetermined time has passed.

  The interrogator further includes response reception means for receiving a response signal transmitted by the response transmission means of the responder, and the question transmission means includes information indicating that communication is performed in the second communication mode. When the response receiving means receives a response signal to the interrogation signal, the interrogation signal including information indicating communication in the first communication mode is repeatedly transmitted instead of information indicating communication in the second communication mode. Also good.

  Thus, when a response signal to the question signal including information indicating that communication is performed in the second communication mode is received, the question signal including information indicating that communication is performed in the first communication mode can be automatically transmitted. Therefore, as soon as the responder that can communicate only in the second communication mode completes the authentication and goes out of the predetermined range, the user who wants to respond in the first communication mode can respond.

  The interrogator of the wireless communication system of the present invention is an interrogator used in a wireless communication system comprising a sensor and an interrogator that performs wireless communication in the first communication mode and the second communication mode, and the first communication mode The question transmission means for repeatedly transmitting the first communication mode question signal including information indicating that communication is performed, and that the detection target has entered a predetermined range that is within the reach of the question signal and is close to the own device Detecting means using the sensor, wherein the question transmitting means, when the detecting means detects the entry of the detection target, is replaced with information indicating that communication is performed in the first communication mode. A question signal for the second communication mode including information indicating that communication is performed in the two communication mode is transmitted.

Since the interrogator can detect that the detection target has entered a predetermined range near the interrogator by providing the above-described configuration, the interrogator can be used as a responder without bothering the user. The communication mode can be switched.
In addition, the sensor is a light detection sensor that detects illuminance, and the detection unit detects the predetermined range when the illuminance detected by the light detection sensor falls from a value exceeding a threshold value to a threshold value or less. It is good also as detecting that the detection target entered.

Further, the sensor is a distance detection sensor that projects radio waves and detects a distance from the own device to a detection target by the reflected wave, and the detection means is based on the distance detected by the distance detection sensor. When it is determined that the detection target is within the predetermined range, it may be detected that the detection target has entered the predetermined range.
The sensor is a heat detection sensor that detects heat, and the detection unit determines that the heat source is within the predetermined range based on the heat detected by the heat detection sensor. It may be detected that the detection target has entered the range.

The sensor is a pressure detection sensor that detects a constant pressure, and the detection means detects that the position where the pressure is detected based on the pressure detected by the pressure detection sensor is within the predetermined range. When it is determined, it may be detected that a detection target has entered the predetermined range.
By using an optimal sensor according to the environment where the interrogator is installed, it is possible to increase the possibility of detecting that the detection target has entered a predetermined range near the interrogator.

<Embodiment>
<Overview>
In the present invention, the communication range in the passive mode is much smaller than the communication range in the active mode, so that the user who wants to communicate in the passive mode approaches to a place where the tag can be held over the reader. It is a thing.

  FIG. 1 shows how the active mode and the passive mode are used. FIG. 1A shows a usage mode in the active mode, and shows that a person wearing a tag passes through a reader 1000 installed on a wall and performs authentication. . On the other hand, FIG.1 (b) shows the use aspect in passive mode, and has shown that it is authenticating by holding a tag over the reader 1000 installed in the wall beside a door.

When the reader of the present invention detects that an object has entered a predetermined range, the reader predicts that a tag for communication in the passive mode will be held over and starts communication in the passive mode. Therefore, it is possible to save the user's trouble of pressing a button to switch the mode.
Here, the active mode and the passive mode will be briefly described.

The active mode is a mode in which each of the tag and the reader generates radio waves to transmit data, and the passive mode is a mode in which only the reader generates radio waves and the tag uses load modulation. This mode generates radio waves.
When communicating in the active mode, the tag transmits a signal using a built-in battery as a power source. When communicating in the passive tag mode, the tag transmits a signal using power generated by receiving radio waves from the reader.

Therefore, the communication distance of the signal transmitted by the tag in the passive mode is shorter than the communication distance of the signal transmitted in the active mode, and the communication range of the passive mode is narrow.
In the active mode, the tag operates using a built-in battery as a power source, and therefore communication is not possible when the battery runs out. Therefore, normally, in order to prevent communication from being lost due to running out of batteries, communication in passive mode is also possible.

Hereinafter, a radio communication system capable of communicating in the active mode and the passive mode will be described. In this embodiment, the reader is called an interrogator and the tag is called a responder.
In addition, in this system, an interrogator installed near the door authenticates the responder possessed by the user, and if the authentication is successful, the door is opened and the user can pass.
<Configuration>
The interrogator 1000 and the responder 2000 that constitute this system will be described.

2 and 3 are functional block diagrams of the interrogator 1000 and the responder 2000 according to the present invention.
The interrogator according to the present embodiment has a function of communicating in two communication modes, an active mode and a passive mode. FIG. 2 is a diagram illustrating a communication method in the active mode, and FIG. It is a figure which shows the communication method.

2 and FIG. 3, the interrogator 1000 and the responder 2000 are the same, respectively, and are different only in that the transmission / reception method of the interrogation signal and the response signal in each mode is shown.
This system is usually composed of a plurality of interrogators and a plurality of responders. However, since the systems have the same configuration, the configurations of the interrogator 1000 and the responder 2000 will be described here. .

The interrogator 1000 is installed on a wall or the like and operates with an external power supply. The responder 2000 operates with a built-in battery and an electromotive force of a receiving unit that receives an LF band (long wave band) signal as a power source.
First, the interrogator 1000 includes a control unit 1100, an optical sensor 1200, a detection unit 1300, a passive mode question signal transmission unit 1400, an active mode question signal transmission unit 1500, a passive mode response signal reception unit 1600, and an active mode response signal reception unit 1700. , An LF signal transmission / reception unit 1800, an LF antenna 1810, an RF signal reception unit 1900, and an RF antenna 1910.

The control unit 1100 includes a CPU, a memory, and the like (not shown), performs general control processing necessary for authentication of the responder 2000, and uses processing unique to the present invention described below, for example, an optical sensor 1200. It detects that the user is approaching and performs processing such as transmitting a question signal in a different communication mode.
The optical sensor 1200 is a sensor that detects visible light. In this embodiment, it is assumed that the sensor is a photodiode, and a current amount proportional to the amount of light hit is generated.

  The optical sensor 1200 is built in the interrogator 1000, and the housing of the interrogator 1000 is provided with an opening so that the built-in optical sensor 1200 can receive external light. The opening is provided at a position where light entering from the opening is reduced when a person approaches. This position needs to be determined in consideration of the environment in which the interrogator 1000 is installed, for example, the positions of surrounding lights and windows.

  The detection unit 1300 has a function of detecting that a person who is a detection target is approaching. The approaching means that it has entered a predetermined range in the vicinity of the interrogator 1000, and the predetermined range is preferably a range in which it can be estimated that the responder 2000 possessed by a user, who is a person, will be held. In this embodiment, the radius is about 30 to 50 centimeters with the interrogator 1000 as the center.

When the amount of current generated by the optical sensor 1200 is equal to or less than the threshold value, that is, when it becomes dark, the main detection unit 1300 determines that a person approaches and the light is blocked. This threshold value is determined in consideration of the position of the light at the place where the interrogator 1000 is installed, the direction of the interrogator 1000, a predetermined range, and the like.
Next, the passive mode interrogation signal transmission unit 1400 generates a passive mode interrogation signal, and the active mode interrogation signal transmission unit 1500 generates an active mode interrogation signal and requests the LF signal transmission / reception unit 1800 to transmit it. Have.

The passive mode response signal receiver 1600 receives a passive mode response signal via the LF signal transmitter / receiver 1800, and the active mode response signal receiver 1700 receives the active mode response signal via the RF signal receiver 1900. To do.
The structure of these interrogation signals and response signals will be described with reference to FIG. 4 in the <Data> section.

The LF signal transmission / reception unit 1800 has a function of superimposing, amplifying, and transmitting from the LF antenna 1810 the interrogation signal passed from the passive mode interrogation signal transmission unit 1400 or the active mode interrogation signal transmission unit 1500. Have
The LF signal transmission / reception unit 1800 has a function of receiving a response signal via the LF antenna 1810 and passing the received response signal to the passive mode response signal receiving unit 1600.

The RF signal receiving unit 1900 has a function of receiving a response signal via the RF antenna 1910 and passing the received response signal to the active mode response signal receiving unit 1700.
Next, the responder 2000 includes a control unit 2100, an interrogation signal reception unit 2200, a passive mode response signal transmission unit 2300, an active mode response signal transmission unit 2400, a mode determination unit 2500, a battery 2600, an LF signal transmission / reception unit 2800, and an LF antenna. 2810, an RF signal transmission unit 2900 and an RF antenna 2910.

The control unit 2100 includes a CPU, a memory, and the like (not shown), and controls other processes such as issuing instructions to other function units and returning a response signal when receiving a question signal.
The question signal receiving unit 2200 has a function of receiving the question signal received from the LF signal transmitting / receiving unit 2800, analyzing the received signal, and passing necessary information to the control unit 2100 and the mode determining unit 2500.

The mode determination unit 2500 has a function of determining from the information received from the question signal reception unit 2200 whether to return a response signal in the active mode or the passive mode and passing the result to the control unit 2100.
Next, the passive mode response signal transmitter 2300 receives the passive mode response signal via the LF signal transmitter / receiver 2800, and the active mode response signal transmitter 2400 receives the active mode response signal via the RF signal transmitter 2900. Send and send.

The LF signal transmission / reception unit 2800 has a function of receiving a question signal via the LF antenna 2810 and passing it to the received question signal reception unit 2200. Further, the LF signal transmission / reception unit 2800 generates power when receiving the interrogation signal, and activates the control unit 2100 and the like with this power.
Furthermore, the LF signal transmission / reception unit 2800 has a function of transmitting the passive mode response signal passed from the passive mode response signal transmission unit 2300 via the LF antenna 2810.

The RF signal transmission unit 2900 has a function of transmitting the active mode response signal passed from the active mode response signal transmission unit 2400 via the RF antenna 2910. The RF signal transmission unit 2900 transmits a response signal using the battery 2600 as a power source.
As shown in FIG. 2, in the active mode, the interrogation signal is transmitted in the LF band by the LF signal transmission / reception unit 1800, and the response signal is transmitted in the RF band by the RF signal transmission unit 2900.

On the other hand, as shown in FIG. 3, in the passive mode, the interrogation signal is transmitted in the LF band by the LF signal transmission / reception unit 1800 as in the active mode, and the response signal is transmitted in the LF band by the LF signal transmission / reception unit 2800.
Here, all or part of each process by each unit such as the control unit 1100 of the interrogator 1000 is realized by a CPU (not shown) executing various programs. All or part of each process performed by each unit of the control unit 2100 is also realized by a CPU (not shown) executing various programs.

<Data>
Hereinafter, main data used by the wireless communication system of the present embodiment will be described with reference to FIG.
FIG. 4 is a diagram illustrating a data configuration and example contents of the question signal and the response signal. FIG. 4A shows an example of the data configuration and contents of the interrogation signal 10 transmitted by the interrogator 1000, and FIG. 4B shows an example of the data configuration and contents of the response signal 20 transmitted by the responder 2000.

4A includes a PR (PReamble) 11, a UW (Unique Word) 12, a communication mode 13, an interrogator ID 14, and a CRC 15.
PR11 is a bit string (synchronization code) indicating the start of data of the interrogation signal 10, and UW12 is a so-called frame synchronization signal. The CRC 15 is data used by the responder 2000 that has received the question signal 10 to detect whether an error has occurred in the received question signal 10.

  The communication mode 13 is information indicating which mode is used for communication between the active mode and the passive mode. In the present embodiment, “1” indicates that communication is performed in the active mode, and “2” indicates that communication is performed in the passive mode. Hereinafter, the question signal having the communication mode 13 of “1” is referred to as an active mode question signal, and the question signal of “2” is referred to as a passive mode question signal.

The interrogator ID 14 is an identifier of the interrogator 1000 that has transmitted the interrogation signal 10, and is assumed to be stored in advance in the internal work memory.
Next, the response signal 20 in FIG. 4B is composed of PR21, UW22, interrogator ID23, responder ID24, and CRC25.
PR21 is a bit string (synchronization code) indicating the start of data of the response signal 20, and UW22 is a so-called frame synchronization signal. The CRC 25 is data for the interrogator 1000 that has received the response signal 20 to detect whether an error has occurred in the received response signal 20.

The interrogator ID 23 represents an identifier of the interrogator 1000, and indicates which interrogator 1000 the response signal 20 corresponds to. In other words, the response signal 20 is a response signal transmitted in response to the interrogation signal transmitted from the interrogator indicated by the interrogator ID23.
The responder ID 24 is an identifier of the responder 2000 that has transmitted the response signal 20, and is assumed to be stored in advance in the internal work memory.

The response signal 20 has the same data configuration and content as in the active mode and the passive mode, and the frequency band to be transmitted and the communication distance are different.
<Communication mode switching timing>
Here, the timing of switching the communication mode from the active mode to the passive mode will be described.

The timing of transmission / reception of the inquiry signal and the response signal and the transmission distance will be described with reference to FIGS. 5 and 6, and the timing at which the interrogator switches the communication mode will be described.
FIG. 5 is a schematic diagram showing the transmission distance between the inquiry signal and the response signal.
The transmission distance of the inquiry signal from the interrogator 1000 is indicated by a dotted line. The active mode interrogation signal and the passive mode interrogation signal have the same transmission distance. This is because the same LF signal transmission / reception unit 1800 transmits (see FIG. 2 and the like).

The transmission distance of the response signal in the active mode from the responder 2001 is indicated by a one-dot chain line. Further, the transmission distance of the response signal in the passive mode from the responder 2002 is indicated by a dense dotted line.
A range indicated by a solid line in the vicinity of the interrogator 1000 indicates a range in which the detection unit 1300 of the interrogator 1000 detects that a person has entered. In the present embodiment, when it is detected that a person has entered this range, the interrogator 1000 stops transmitting the question signal in the active mode and starts transmitting the question signal in the passive mode.

As shown in the figure, the transmission distance of the response signal in the passive mode indicated by the dense dotted line is shorter than the transmission distance of the response signal in the active mode indicated by the alternate long and short dash line. For example, the transmission distance of the response signal in the passive mode is several centimeters, and the transmission distance of the response signal in the active mode is several meters.
Next, FIG. 6 is a timing chart showing the timing of switching from the active mode to the passive mode and the timing of transmission / reception of the inquiry signal and the response signal.

The first level represents the timing 100 when the detection unit 1300 of the interrogator 1000 detects that a person has entered the predetermined range.
In the second row, the question signal transmitted by the interrogator 1000 is represented by a rectangle. The solid-lined white rectangle indicates “active question” indicates the active mode question signal, and the solid-line hatched rectangle indicates “passive question” indicates the passive mode question signal. . The interrogation signal is transmitted at a constant cycle. For example, an interrogation signal of 100 ms is repeatedly transmitted every 300 ms. A response signal is received during 200 ms after the transmission of the interrogation signal. It should be noted that the length of the interrogation signal and the transmission cycle in this figure are not accurately described for convenience of explanation.

  In the third and fourth stages, the response signals transmitted from the responders A and B are indicated by rectangles. The solid-lined white rectangle indicates "active response" indicates the active mode response signal, and the solid-line hatched rectangle indicates "passive response" indicates the passive mode response signal. . In addition, “unlocked” written in a dotted rectangle indicates that the interrogator has authenticated the responder and opened the door.

First, the interrogator transmits an active mode interrogation signal 100 (see arrow 101), and the responder A that has received the interrogation signal 100 transmits an active mode response signal 102 (see arrow 103).
The interrogator receives the response signal from the responder A, and unlocks 104 after authentication. A person who has the responder A can enter the room.

Next, the interrogator B receives the active mode interrogation signal 200 (see arrow 201) and tries to transmit the response signal 202 in the active mode, but the battery is dead and actually transmits the response signal 202. Cannot be done (see arrow 203). In this case, the interrogator does not receive the response signal and therefore does not unlock.
The person carrying the transponder B approaches the interrogator in order to hold the transponder B over the interrogator for authentication.

The detector detects that a person has entered the predetermined range, and the interrogator that knows the detection stops transmitting the question signal in the active mode and transmits the question signal 300 in the passive mode (see arrow 301). ).
The holder of the transponder B approaching the interrogator transmits the response signal 302 in the passive mode by holding the transponder B over the interrogator (see arrow 303), and the interrogator that has received the response signal 302 opens after authentication. Lock 304.

When the interrogator transmits the passive mode interrogation signal for a predetermined time indicated by a white arrow, for example, for 5 seconds, the interrogator starts transmitting the active mode interrogation signal 400 again.
<Operation>
Hereinafter, the operation at the time of switching the communication mode between the interrogator 1000 and the responder 2000 in the above-described wireless communication system will be described.

FIG. 7 is a flowchart showing the communication mode switching process of the interrogator 1000 and the response process of the responder 2000. In this figure, the dotted line represents the transmission of the inquiry signal, and the alternate long and short dash line represents the transmission of the response signal.
First, the process of the interrogator 1000 will be described.
When the control unit 1100 of the interrogator 1000 detects an activation instruction, for example, pressing of an operation switch (not shown), at first, there is no notification that a person has been detected from the detection unit 1300 (step S130: NO). The active mode question signal transmission unit 1500 is requested to transmit a question signal.

  Upon receiving the request, the active mode question signal transmission unit 1500 sets the communication mode 13 to “1”, generates the active mode question signal 10 in which the interrogator ID 14 is set to its own ID, and generates the generated question signal 10. (Refer to FIG. 4A) is passed to the LF signal transmission / reception unit 1800 to request transmission. The active mode question signal transmission unit 1500 stores the generated question signal 10 in the internal work memory, and passes the stored question signal 10 to the LF signal transmission / reception unit 1800 from the next request.

Upon receiving the request, the LF signal transmission / reception unit 1800 transmits the received inquiry signal 10 via the LF antenna 1810 (step S100).
The control unit 1100 that has requested the active mode interrogation signal transmission unit 1500 to transmit the interrogation signal 10 has received a response signal 20 (FIG. 4) from the active mode response signal reception unit 1700 within a predetermined period, for example, 300 ms after the request. If (see (b)) is not received (step S110: NO), the active mode question signal transmission unit 1500 is requested to transmit a question signal (step S100).

  The control unit 1100 that has requested the active mode question signal transmission unit 1500 to transmit the question signal receives a response signal from the active mode response signal reception unit 1700 during a predetermined period after the request is made (step S110: YES). ), The authentication process of the responder 2000 is performed (step S120). Specifically, for example, when the responder ID 24 of the received response signal 20 is on the list of the responder IDs stored in the own device, it is unlocked as being authenticated.

The active mode response signal receiving unit 1700 receives the received response signal 20 from the RF signal receiving unit 1900 that has received the response signal 20 via the RF antenna 1910, and sends the received response signal 20 to the control unit 1100. hand over.
The control unit 1100 requests the active mode question signal transmission unit 1500 to transmit a question signal at a predetermined cycle, repeatedly performs communication processing (steps S130 to S120), and receives a notification from the detection unit 1300 that a person has been detected. If (step S130: YES), measurement for a predetermined time is started. Specifically, the timer is reset (step S140). The predetermined time is a time for performing communication in the passive mode, for example, 1 minute. When there is no notification that the person is detected from the detection unit 1300 (step S130: NO), the active mode question signal transmission unit 1500 is requested to transmit a question signal at a predetermined cycle (step S100).

Since the predetermined time has not yet elapsed (step S150: NO), the control unit 1100 that resets the timer and starts measuring the predetermined time requests the passive mode question signal transmission unit 1400 to transmit the question signal 10. To do.
Upon receiving the request, the passive mode question signal transmission unit 1400 sets the communication mode 13 to “2”, generates the passive mode question signal 10 in which the ID of the own device is set to the interrogator ID 14, and the generated question signal 10 (See FIG. 4B) is passed to the LF signal transmission / reception unit 1800 to request transmission. The passive mode question signal transmission unit 1400 stores the generated question signal 10 in the internal work memory, and passes the stored question signal 10 to the LF signal transmission / reception unit 1800 from the next request.

Upon receiving the request, the LF signal transmission / reception unit 1800 transmits the received inquiry signal 10 via the LF antenna 1810 (step S160).
When the control unit 1100 requesting the passive mode question signal transmission unit 1400 to transmit the question signal receives a response signal from the passive mode response signal reception unit 1600 during a predetermined period after the request is made (step S170: YES) ), The authentication process of the responder 2000 is performed (step S180). This authentication process is the same as when an active mode response signal is received (see step S120).

The passive mode response signal receiving unit 1600 receives the received response signal 20 from the LF signal transmitting / receiving unit 1800 that has received the response signal 20 via the LF antenna 1810, and passes the received response signal 20 to the control unit 1100. hand over.
The control unit 1100 requests the passive mode question signal transmission unit 1400 to transmit a question signal at a predetermined cycle, repeatedly performs communication processing (steps S160 to S180), and detects when a predetermined time has elapsed (step S150: YES). If there is no notification that the person is detected from the unit 1300 (step S130: NO), the active mode question signal transmission unit 1500 is requested to transmit the question signal (step S100), and the person is detected from the detection unit 1300. When there is a notification to that effect (step S130: YES), measurement of a predetermined time is started (step S140), and the passive mode question signal transmission unit 1400 is requested to transmit the question signal 10.

Next, processing of the responder 2000 will be described.
The LF signal transmission / reception unit 2800 of the responder 2000 receives the interrogation signal 10 transmitted by the interrogator 1000 via the LF antenna 2810, and passes the received interrogation signal 10 to the interrogation signal reception unit 2200 (step S200).
The question signal receiving unit 2200 passes the communication mode 13 of the received question signal 10 to the mode determining unit 2500 and passes the interrogator ID 14 to the control unit 2100.

When the communication mode 13 is “1”, the mode determination unit 2500 that has received the communication mode 13 determines that it is an instruction to perform communication in the active mode, and when it is “2”, the mode determination unit 2500 performs communication in the passive mode. It judges that it is the instruction | indication to perform, and notifies that to the control part 2100 (step S210).
Upon receiving the notification, the control unit 2100 requests the active mode response signal transmission unit 2400 to transmit a response signal when the notification is an instruction to perform communication in the active mode (step S210: active). At the time of this request, the interrogator ID 14 received from the question signal receiving unit 2200 is passed.

The active mode response signal transmission unit 2400 that has received the request generates the response signal 20 and passes the generated response signal 20 to the RF signal transmission unit 2900 to request transmission. The active mode response signal transmission unit 2400 sets the received interrogator ID 14 as the interrogator ID 23 of the response signal 20 and sets its own ID as the responder ID 24 to generate the response signal 20.
Upon receiving the request, the RF signal transmission unit 2900 transmits the received response signal 20 via the RF antenna 2910 (step S220, see FIG. 2).

On the other hand, when the control unit 2100 that has received the notification of the determination result from the mode determination unit 2500 is a notification that the communication is an instruction to perform communication in the passive mode (step S210: passive), the passive mode response signal transmission unit 2300 To send a response signal. At the time of this request, the interrogator ID 14 received from the question signal receiving unit 2200 is passed.
The passive mode response signal transmission unit 2300 that has received the request generates the response signal 20, passes the generated response signal 20 to the LF signal transmission unit 2800, and requests transmission. The passive mode response signal transmitter 2300 sets the received interrogator ID 14 to the interrogator ID 23 of the response signal 20 and sets its own ID to the responder ID 24 to generate the response signal 20.

Upon receiving the request, the LF signal transmission unit 2800 transmits the received response signal 20 via the LF antenna 2810 (step S230, see FIG. 3).
<Supplement>
The wireless communication system according to the present invention has been described above based on the embodiment. However, this system can be partially modified, and the present invention is not limited to the above-described embodiment. That is,
(1) In the embodiment, it is assumed that the detection target person has entered a predetermined range around the interrogator using a sensor that outputs a photocurrent according to the illuminance among the optical sensors. Other sensors may be used.

Among the optical sensors, for example, a sensor using an IC that converts light intensity (illuminance) into a frequency of an output pulse may be used. In this case, when the frequency falls below the predetermined frequency, it is determined that the person who is the detection target has entered the predetermined range.
A distance detection sensor may be used as a sensor other than the optical sensor. In this case, when a person approaches the interrogator, it is necessary to install a distance detection sensor at a position and orientation that measures the distance between the interrogator and the person. If the measured distance is, for example, 50 centimeters or less, it is determined that a person who is a detection target has entered the predetermined range. The distance detection sensor, for example, irradiates laser light, captures light scattered by hitting a person with a photodiode, and measures the distance from the irradiation to light reception to the person.

A heat sensor may also be used. In this case, if the sensor detects a temperature equivalent to the body temperature, it is determined that a person who is a detection target has entered the predetermined range. As the heat detection sensor, for example, an infrared sensor that detects infrared rays radiated according to the surface temperature is used.
Further, a pressure detection sensor may be used. In this case, for example, when a pressure equal to or higher than a predetermined pressure is detected on a floor in a predetermined range around the interrogator, it is determined that a person who is a detection target has entered.
(2) In the embodiment, the transmission of the passive mode interrogation signal is terminated, and the condition for starting the transmission of the active mode interrogation signal again is that the passive mode interrogation signal is transmitted for a predetermined time. Condition may be sufficient.

For example, a question signal in the passive mode has been transmitted a predetermined number of times, a response signal has been received, and the like.
The case where transmission of the question signal in the active mode is started again after transmitting the question signal in the passive mode a predetermined number of times will be briefly described with reference to FIGS.
FIG. 8 is a timing chart showing the timing of switching from the active mode to the passive mode and the timing of transmission / reception of the inquiry signal and the response signal, as in FIG. 6, and the meanings of rectangles and arrows are the same as in FIG. It is. 6 differs from FIG. 6 in that the question signal in the passive mode is transmitted for a predetermined time indicated by a white arrow in FIG. 6, but is different in that it is transmitted a predetermined number of times in FIG.

  FIG. 9 is a flowchart showing the communication mode switching process of the interrogator 1000 and the response process of the responder 2000, as in FIG. 7, where the dotted line represents the transmission of the question signal and the alternate long and short dash line represents the transmission of the response signal. The difference between FIG. 7 and FIG. 7 is that in step 300, the control unit 1100 resets a counter for counting a predetermined number of times instead of resetting a timer for measuring a predetermined time, and in step 310, The difference is that it is determined whether or not a predetermined number of times have been transmitted instead of determining the passage of the predetermined time.

Next, when a response signal is received, a case where transmission of an active mode question signal is started again will be briefly described with reference to FIGS.
FIG. 10 is a timing chart showing the timing of switching from the active mode to the passive mode and the timing of transmission / reception of the inquiry signal and the response signal, as in FIG. 6, and the meanings of rectangles and arrows are the same as in FIG. It is. The difference between this figure and FIG. 6 is that in FIG. 6, the question signal in the passive mode is transmitted for a predetermined time indicated by a white arrow, but in this figure, if a response signal is received within the predetermined time, it is again. The difference is that transmission of the inquiry signal 350 in the active mode is started.

  FIG. 11 is a flowchart showing the communication mode switching process of the interrogator 1000 and the response process of the responder 2000, as in FIG. 7, where the dotted line represents the transmission of the question signal and the alternate long and short dash line represents the transmission of the response signal. The difference between FIG. 7 and FIG. 7 is that, in step 400, after receiving the response signal in the passive mode (step S170) and performing the authentication process, the control unit 1100 is passive even if the predetermined time has not elapsed. Do not request the passive mode question signal transmission unit 1400 to transmit the mode question signal, but perform the process of transmitting the question signal 10 in response to the notification of whether or not a person has been detected from the detection unit 1300 (step S130). Is different.

In this example, the case where the response signal is received within the predetermined time has been described, but the case where the response signal is received during the predetermined number of times of transmission may be used.
Further, the condition for terminating the transmission of the question signal in the passive mode and starting the transmission of the question signal in the active mode again is used to detect that the person who is the detection target has entered the predetermined range from the interrogator. This condition may be determined depending on the sensor.

For example, if it is determined that a person to be detected has entered the predetermined range from the interrogator when the illuminance becomes weak using an optical sensor, the charge corresponding to the illuminance exceeds the threshold. It is good as a condition.
Moreover, when using the distance detection sensor, it is good also as conditions on which the measured distance is only what exceeded 50 centimeters, for example.

In the case where a heat detection sensor is used, the temperature detected by the sensor may be a condition that the temperature is lower than the body temperature.
Moreover, when using the pressure detection sensor, it is good also as conditions that the pressure more than predetermined pressure is no longer detected on the floor of the predetermined range around an interrogator.
(3) In the embodiment, the optical sensor is built in the interrogator 1000. However, the optical sensor may be outside the interrogator 1000, and detects that a person who is a detection target has entered the predetermined range from the interrogator. It only has to be installed at a position where it can be made.

Moreover, when there are a plurality of interrogators, it is not necessary to install one sensor in each interrogator, and it is only necessary to detect that a person who is a detection target has entered a predetermined range from each interrogator.
(4) In the interrogator and the responder included in the wireless communication system, all or a part of each component in FIG. 2 and the like may be realized by an integrated circuit of one chip or a plurality of chips.
(5) A program for causing the CPU to execute each control process (see FIG. 7) for realizing each function of the wireless communication system shown in the embodiment is recorded on a recording medium or via various communication paths. It can also be distributed and distributed. Such a recording medium includes an IC card, an optical disk, a flexible disk, a ROM, a flash memory, and the like. The distributed and distributed program is used by being stored in a memory or the like that can be read by the CPU in the device, and each function described in the embodiment is realized by the CPU executing the program.

FIG. 1A is a diagram illustrating a usage mode of the active mode, and FIG. 1B is a diagram illustrating a usage mode of the passive mode. It is a functional block diagram of the interrogator 1000 and the responder 2000 concerning this invention, and is a figure which shows the communication method in active mode. It is a functional block diagram of the interrogator 1000 and the responder 2000 concerning this invention, and is a figure which shows the communication method in passive mode. FIG. 4A shows an example of the data configuration and contents of the interrogation signal 10 transmitted by the interrogator 1000, and FIG. 4B shows an example of the data configuration and contents of the response signal 20 transmitted by the responder 2000. It is the schematic which shows the transmission distance of a question signal and a response signal. It is a timing chart showing the timing of switching from the active mode to the passive mode and the transmission / reception timing of the question signal and the response signal when the passive mode question signal is transmitted for a predetermined time. It is a flowchart which shows the communication mode switching process of the interrogator 1000, and the response process of the responder 2000 when transmitting the question signal of a passive mode for a predetermined time. It is a timing chart showing the timing of switching from the active mode to the passive mode and the transmission / reception timing of the question signal and the response signal when the passive mode question signal is transmitted a predetermined number of times. It is a flowchart which shows the communication mode switching process of the interrogator 1000, and the response process of the responder 2000 in the case of transmitting the question signal in passive mode a predetermined number of times. It is a timing chart showing the timing of switching from the active mode to the passive mode and the transmission / reception timing of the question signal and the response signal when the question signal in the passive mode is transmitted until the response signal is received. It is a flowchart which shows the communication mode switch process of the interrogator 1000, and the response process of the responder 2000 in the case of transmitting a passive mode interrogation signal until the response signal is received.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Question signal 20 Response signal 1000 Interrogator 1100 2100 Control part 1200 Optical sensor 1300 Detection part 1400 Passive mode question signal transmission part 1500 Active mode question signal transmission part 1600 Passive mode response signal reception part 1700 Active mode response signal reception part 1800 2800 LF Signal transmitting / receiving unit 1810 2810 LF antenna 1900 RF signal receiving unit 1910 2910 RF antenna 2000 responder 2200 question signal receiving unit 2300 passive mode response signal transmitting unit 2400 active mode response signal transmitting unit 2500 mode determining unit 2600 battery 2900 RF signal transmitting unit

Claims (12)

An interrogator and a responder, the interrogator is a wireless communication system that performs wireless communication with the responder,
The wireless communication system includes a sensor,
The interrogator is
Question transmitting means for repeatedly transmitting a question signal including information indicating that communication is performed in the first communication mode;
A detection means for detecting, using the sensor, that the detection target has entered a predetermined range in the reach of the question signal and close to the own device;
When the detection means detects the entry of the detection target, the question transmission means receives a question signal including information indicating communication in the second communication mode instead of information indicating communication in the first communication mode. Send repeatedly,
The responder is
A question receiving means for receiving a question signal;
Response transmitting means for transmitting a response signal to the received interrogation signal,
If the received question signal is a question signal including information indicating that communication is performed in the second communication mode, the response transmission means is more than the question signal including information indicating that communication is performed in the first communication mode. A wireless communication system characterized by transmitting a response signal having a narrow transmittable range. When the question transmission means repeatedly transmits a question signal including information indicating that communication is performed in the second communication mode for a predetermined time, it communicates in the first communication mode instead of information indicating that communication is performed in the second communication mode. The wireless communication system according to claim 1, wherein an interrogation signal including information indicating that is repeatedly transmitted. The question transmission means communicates in the first communication mode instead of the information indicating that communication is performed in the second communication mode after transmitting a question signal including information indicating communication in the second communication mode a predetermined number of times. The wireless communication system according to claim 1, wherein the interrogation signal including the information indicating is repeatedly transmitted. The interrogator further comprises response receiving means for receiving a response signal transmitted by the response transmitting means of the responder,
When the response reception means receives a response signal to an inquiry signal including information indicating that communication is performed in the second communication mode, the question transmission means performs the first communication instead of the information indicating that communication is performed in the second communication mode. The wireless communication system according to claim 1, wherein an inquiry signal including information indicating that communication is performed in a mode is repeatedly transmitted. The response transmission means includes a low-frequency transmission means for transmitting a low-frequency signal and a high-frequency transmission means for transmitting a high-frequency signal, and transmits a response signal to the inquiry signal including information indicating that communication is performed in the second communication mode. When transmitting a response signal to an interrogation signal that includes information indicating that communication is performed in the first communication mode, the high-frequency transmission unit transmits the response signal. Item 2. The wireless communication system according to Item 1. The responder further includes a battery and power generation means for generating power by receiving the interrogation signal,
When the received inquiry signal includes information indicating that communication is performed in the first communication mode, the response transmission unit transmits a response signal using the battery as a power source and communicates in the second communication mode. The wireless communication system according to claim 1, wherein a response signal is transmitted using the power generated by the power generation means when the information to be displayed is included. An interrogator used in a wireless communication system comprising a sensor and an interrogator that performs wireless communication in the first communication mode and the second communication mode,
Question transmission means for repeatedly transmitting a first communication mode question signal including information indicating that communication is performed in the first communication mode;
A detection means for detecting, using the sensor, that the detection target has entered a predetermined range in the reach of the question signal and close to the own device;
The question transmission means includes a second communication that includes information indicating that communication is performed in the second communication mode instead of information indicating that communication is performed in the first communication mode when the detection means detects entry of a detection target. An interrogator characterized by transmitting a mode interrogation signal. The sensor is a light detection sensor for detecting illuminance,
The detection means detects that a detection target has entered the predetermined range when the illuminance detected by the light detection sensor falls below a threshold value from a value exceeding the threshold value. Interrogator as described in. The sensor is a distance detection sensor that projects a radio wave and detects a distance from its own device to a detection target by its reflected wave,
The detection means detects that the detection target has entered the predetermined range when it is determined that the detection target is within the predetermined range based on the distance detected by the distance detection sensor. The interrogator according to claim 7. The sensor is a heat sensor for detecting heat,
The detection unit detects that a detection target has entered the predetermined range when it is determined that a heat source is within the predetermined range based on heat detected by the heat detection sensor. Item 8. The interrogator according to Item 7. The sensor is a pressure detection sensor for detecting a constant pressure,
The detection means detects that a detection target has entered the predetermined range when it is determined that the position where the pressure is detected is within the predetermined range based on the pressure detected by the pressure detection sensor. The interrogator according to claim 7. An interrogation signal transmission method used in an interrogator used in a wireless communication system including a sensor and an interrogator performing wireless communication in the first communication mode and the second communication mode,
A question transmission step of repeatedly transmitting a question signal in the first communication mode including information indicating communication in the first communication mode;
A detection step of detecting, using the sensor, that the detection target has entered a predetermined range that is within the reach of the question signal and is close to the own device;
The question transmission step includes information indicating that communication is performed in the second communication mode instead of information indicating that communication is performed in the first communication mode when the entry of the detection target is detected in the detection step. A question signal transmission method characterized by transmitting a mode question signal.

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