JP4545703B2 - Wireless tag and wireless tag operation control method - Google Patents

Description

  The present invention relates to a wireless tag that transmits a radio wave of a signal having ID information that can be specified, and an operation control method between a radio device such as a reader that receives the radio wave. In particular, the present invention relates to an active type wireless tag that has a built-in battery and transmits radio waves by itself, and an operation control method thereof.

An active wireless tag that operates on battery power consumes power to transmit and receive radio waves. Therefore, in order to extend the battery life, it is effective to reduce the operation of the above-described wireless tag.
The technology cited in Non-Patent Document 1 uses a technique of shortening the time for receiving radio waves within the same reception interval for the time for receiving radio waves. This technique is shown in FIG. In the same figure, it is checked whether there is a radio wave addressed to me every 3 seconds, but if there is no radio wave addressed to me (b), the reception operation is stopped and even if it is the same reception interval, The radio wave check time is shorter than shown in (a).
Development of ultra-compact, low-power bidirectional low-power wireless module, [online], May 19, 2005, Matsushita Electric Industrial, [March 8, 2006 search], Internet <http: // panasonic. co.jp/corp/news/official.data/data.dir/jn050519-1/jn050519-1.html>

  In the conventional methods listed in the background art, additional power is required for wireless tags under the respective circumstances such as the situation where there is no reader, setting device / interrogator, or other wireless tags. While reducing consumption, it is difficult to operate the wireless tag when necessary.

  The present invention has been made in consideration of such circumstances, and its purpose is to provide a reader, a setter, an interrogator, or the presence or absence of other wireless tags, as described in the above-mentioned problem. An object of the present invention is to provide a wireless tag and a wireless tag operation control method that can be controlled to operate when necessary while reducing power consumption according to the situation.

In order to solve the above problems, the present invention is a wireless tag that communicates wirelessly with a reader, a signal from a sensor mounted on the wireless tag, time synchronization from a clock mounted on the wireless tag , or, receiving a transmission unit for transmitting a synchronization request signal to the reader a start signal from the outside as a trigger, it becomes the reception standby state by the trigger, thereafter, a synchronizing signal the reader in response to the synchronization request signal is transmitted And a receiver configured to establish synchronization with the reader based on a synchronization signal received by the receiver.

Further, the present invention includes a receiver for receiving a signal by a radio wave from the reader, a transmitter which transmits the signal via radio waves to a reader, the control unit includes a radio wave from the reader can no longer be received at the receiving unit If this is detected, control is performed to widen the reception interval at the reception unit , and a standby state for synchronization-related information sent back from the reader is set, and the transmission unit transmits a synchronization request signal at an equal interval to the reception interval. controls to, when the radio wave from the reader detects that it is now capable of receiving at the receiving unit performs the reception of a signal from the reader is controlled so as to narrow the reception interval in the receiver, and controls to stop transmission of the synchronization request signal in the transmission unit, a wireless tag, wherein the this.

The invention also features a sensor as a trigger to continue between at periodic state where the sensor has detected the operation of the actuator, transmission of radio wave, or a control unit for causing the storage of the log, in that it comprises This is a wireless tag.

Further, the present invention is a wireless tag operation control method, wherein the wireless tag includes a receiving unit that receives a signal from a reader by radio waves, and a transmitting unit that transmits a signal to the reader by radio waves, When the receiving unit detects that the radio wave from the reader cannot be received, the reception unit in the receiving unit is widened to enter a standby state for synchronization-related information sent back from the reader, and the transmitting unit receives the reception When the control unit is controlled to transmit a synchronization request signal at regular intervals and the reception unit detects that the radio wave from the reader can be received, the reception interval at the reception unit is reduced to An operation control method for a wireless tag , comprising: receiving a signal and controlling to stop transmission of a synchronization request signal in the transmission unit .

Further, the present invention is a wireless tag operation control method, wherein the wireless tag includes a receiving unit that receives a signal from a reader by radio waves, and a transmitting unit that transmits a signal to the reader by radio waves, When the receiving unit detects that the radio wave from the reader cannot be received, the reception unit in the receiving unit is widened to enter a standby state for synchronization-related information sent back from the reader, and the transmitting unit receives the reception When the control unit is controlled to transmit a synchronization request signal at regular intervals and the reception unit detects that the radio wave from the reader can be received, the reception interval at the reception unit is reduced to The wireless tag operation control method is characterized in that reception of a signal is performed and control is performed to stop transmission of a synchronization request signal in the transmission unit .

Further, the present invention is an operation control method for a radio tag, as a trigger to continue between the at periodic state the wireless tag sensor provided in the detects the operation of the actuator, transmission of radio waves, or, in the log storage And a wireless tag operation control method.

The present invention enables the following.
(1) When there is a reader, timing is assigned between the wireless tag and the reader, and when synchronization is established so that reader reception can be performed reliably, the sensor operation or synchronous activation of the wireless tag is used as a trigger. Synchronization can be established by sending a synchronization request signal from the other side.
(2) When there is no interrogator and there is a reader (receiver), the radio wave reception function is activated and the position tag (
In order to extract the data of (Position Tag), a future event schedule can be written in the wireless tag, and the reception frequency can be increased in the vicinity of the scheduled time.
(3) If Li Da or we gradually wireless tag moves away, the wireless tag radio waves can not be received from the reader, is increased the reception interval as long as the input from the sensor does not change. Further, the wireless tag transmits a synchronization request signal at regular intervals.
(4) When there is only its own wireless tag around, the operation of the actuator, transmission of radio waves, log storage, etc. are performed with the current sensor state change or the state continuation for a certain period of time as a trigger.
As described above, according to each situation such as presence or absence of a reader, setting device, interrogator, or other wireless tag, further reduction of power consumption and simultaneous operation of the wireless tag when necessary be able to.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[First embodiment: Synchronization establishment method when there is a reader and there is a time slot for tag transmission]
In this embodiment, a reader is present around the wireless tag, and the transmission timing of the wireless tag is assigned to synchronize the tag transmission from the wireless tag side so that the reader can be surely received. It is.
When synchronization is established between such a wireless tag and a reader, synchronization is established by transmitting a synchronization request signal from the wireless tag side to the reader, triggered by the operation of a sensor provided in the wireless tag.
Alternatively, when establishing synchronization between the wireless tag and the reader, using the synchronous activation as a trigger, a synchronization request signal is transmitted from the wireless tag side to the reader to establish synchronization.

FIG. 1 shows the configuration of the wireless tag reader (FIG. 1) triggered by sensor operation, and FIG. 2 shows the operations of the wireless tag and reader of FIG. 1 and the exchange of signals between them.
FIG. 3 shows the configuration of the wireless tag reader that triggers the time synchronization of the clock by synchronous activation, and FIG. 4 shows the operation of the wireless tag and reader shown in FIG. The exchange of wireless signals is shown.
Further, FIG. 5 shows the configuration of an RFID tag reader that is triggered by an external activation signal and a LF setting device / interrogator (hereinafter referred to as “LF setting device / interrogator”) that gives the activation signal. FIG. 6 shows operations of the wireless tag and the reader shown in FIG. 5 and signal exchange between the LF setting / interrogator, the wireless tag, and the reader.

  From here, the wireless tag, reader (and LF setting device / interrogator), and their operations and signal exchange will be described in detail in order with reference to FIGS.

FIG. 1 shows the configuration of a wireless tag 10a and a reader 20 triggered by sensor activation.
The wireless tag 10a includes an on-board sensor 11 that generates a signal that activates a plurality of wireless devices at the same time by sensing vibration, illuminance, and the like. Further, the wireless tag 10a receives a sensor activation signal output from the mounted sensor 11 and starts transmission of a wireless signal from the wireless tag 10a (transmission of a synchronization request signal), or a normal wireless signal after synchronization. There is a transmission unit 12 having a transmission function of transmitting And there exists the receiving part 13 provided with the receiving function which receives the radio signal from the reader | leader 20 (for example, the synchronous relation information response transmitted from the reader | leader 20 with respect to a synchronous request signal).
The other reader 20 includes a receiving unit 21 having a receiving function for receiving a wireless signal (the first synchronization request signal or a normal wireless signal) from the wireless tag 10a. In addition, there is a transmission unit 22 having a transmission function for transmitting a wireless signal (for example, a synchronization related information response to a synchronization request signal from the wireless tag) from the reader 20 to the wireless tag 10a.

FIG. 2 shows signal exchange and operation between the wireless tag 10 a and the reader 20.
In addition, in the same figure, the state in which the transmission function in the transmission unit 12 and the reception function in the reception unit 13 of the wireless tag 10a are stopped is indicated by a dashed-dotted rectangular rectangle. A solid line indicates that the sensor activation signal of the on-board sensor 11 is activated and the transmission / reception function shifts to an operation (transmission and reception signal standby) state.

  When the mounted sensor 11 inside the wireless tag 10a is activated (step Sa1), the transmission unit 12 of the wireless tag 10a transmits a synchronization request signal (step Sa2). The reader 20 receives this synchronization request signal at the receiving unit 21. When the synchronization request signal is received, information on the synchronization of the wireless signal transmitted from the wireless tag 10a thereafter (transmission timing is assigned and the reader can be surely received) is transmitted as a synchronization related information response to the transmission of the reader 20. It transmits from the part 22 (step Sa3). The synchronization-related information response establishes the synchronization between the wireless tag 10a and the reader 20, such as how many seconds after the response is received and how many seconds (or minutes) after the transmission. And information on how to transmit the wireless tag 10a after establishment after synchronization.

  The wireless tag 10a receives the synchronization relation information response at the receiving unit 13, and performs normal transmission after establishment of synchronization according to the synchronization relation information (steps Sa4 and Sa5). By establishing such synchronization, a unique timing is assigned to each of the plurality of tags 10a, so that collision of transmission data from the wireless tag 10a is avoided, and the reader 20 ensures transmission data from the wireless tag 10a. Can be received.

Here, if the reader 20 cannot receive the transmission data of the wireless tag 10a that is normally performed after synchronization, that is, if there is no signal of the wireless tag 10a at the designated timing, the following can be assumed. .
(1) The wireless tag 10a has moved out of the receivable range of the reader 20.
(2) Another new wireless tag 10a appeared and collided with a wireless signal transmitted by the new other wireless tag 10a.
(3) An abnormality of the wireless tag 10a such as a battery exhaustion has occurred.

In FIG. 2, the time activation signal from the mounting sensor 11 mounted on the wireless tag 10a also works on the reception unit 13 side, and the reception function that has been stopped is in a reception standby state (step a1).
Since the receiving unit 13 that receives the synchronization-related information response from the reader 20 receives the UHF band (radio wave), power consumption is relatively large even in the reception standby state. For this reason, it is possible to reduce power consumption by taking a control from the on-board sensor 11 to control the time activation signal to change from the stopped state to the reception standby state and creating a period of the stopped state.
The time activation referred to here is not strict time activation by a clock, but refers to, for example, activation of the wireless tag 10a according to the irradiation time by irradiating light. In this case, for example, the illumination of a specific wavelength can be turned on at a port, and the wireless tags 10a attached to the container can be activated in accordance with the lighting time of the illumination.
Further, by applying vibration (acceleration), the wireless tag 10a may be activated at the time when the vibration (acceleration) is applied. In this case, it is possible to activate the radio tags 10a attached to the container all at the same time when the gantry crane is lifted, by catching the impact of gripping the container when it is lifted by the gantry crane.

  In FIGS. 3 and 4, the synchronous activation is the clock time activation. The configuration of the wireless tag 10b shown in FIG. 3 is a substitute for the timepiece 14 having the built-in sensor 11 of FIG. A time activation signal is sent from the clock 14 built in the wireless tag 10b to the transmission unit 12, and a synchronization request signal is transmitted. The other configuration is the same as in FIG.

FIG. 4 shows the exchange and operation of signals between the wireless tag 10b and the reader 20.
In the figure, a state in which the transmission function in the transmission unit 12 and the reception function in the reception unit 13 of the wireless tag 10b are stopped is indicated by a long and short dashed rectangle. When the time activation signal of the clock 14 is activated and these transmission / reception functions are moved to an operation (transmission and reception signal standby) state, a solid line indicates.

  In the exchange and operation of signals between the wireless tag 10b and the reader 20 shown in the figure, a time activation signal works from the clock 14 built in the wireless tag 10b to the transmission unit 12 of the wireless tag 10b (step Sb1). 12 transmits a synchronization request signal to the reader 20 (step Sb2). Subsequent operations of the wireless tag 10b and the reader 20 and exchange of signals (steps Sb3 to Sb5) are the same as steps Sa3 to Sa5 in FIG.

In addition, when the reader 20 side cannot receive the transmission of the wireless tag 10b that is normally performed after synchronization, that is, when there is no signal of the wireless tag 10b at the designated timing, in FIG. The following can be assumed as in the case where the transmission of the tag 10a cannot be received.
(1) The wireless tag 10b has moved out of the receivable range of the reader 20.
(2) Another new wireless tag 10b appears and collides with a wireless signal transmitted by the new other wireless tag 10b.
(3) An abnormality of the wireless tag 10b such as a battery exhaustion has occurred.

In FIG. 4, the time activation signal from the clock 14 built in the wireless tag 10b also works on the reception unit 13 side, and the reception function that has been stopped is in a reception standby state (step Sb1).
For the same reason as in FIG. 2 that the power consumption is relatively large in the reception standby state for receiving the UHF band (radio wave), the reception function of the reception unit 13 is stopped from the stop state under the control of the time activation signal from the internal clock 14 It is possible to reduce power consumption by adopting a configuration in a reception standby state and creating a period of a stop state.

  5 and 6, the synchronous activation is based on an activation signal from the outside. The configuration inside the wireless tag 10c shown in FIG. 5 does not include the on-board sensor 11 shown in FIG. 1, and includes an LF setting / interrogator 30 separately from the wireless tag 10c. The activation signal from the LF setting / interrogator 30 is received by the LF receiver 15 of the wireless tag 10c having the LF reception function. Upon receiving this activation signal, the transmission unit 12 of the wireless tag 10 c transmits a synchronization request signal to the reader 20. Other configurations are the same as those in FIG. As described above, the wireless tag 10c has two types of reception functions. One is a function for receiving a UHF band (radio wave), and the other is a function for receiving an LF (magnetic) signal.

The LF setting / interrogator 30 is a device that transmits an LF signal to the wireless tag. The “LF setting device” is a device that controls a wireless tag by an LF signal, and the “LF interrogator” is a device that transmits an LF signal to obtain a response (activation transmission) from the wireless tag. The “LF gate” is a transmitter that transmits an LF signal, and is synonymous with “LF setter / interrogator”.
As the installation location of the “LF gate” at the port, a gantry crane (a dedicated crane approaching a quay carrying a container from a ship) is assumed. The transmission distance of the “LF gate” is about 100 m.

FIG. 6 shows the exchange and operation of signals between the wireless tag 10 c and the reader 20.
In FIG. 6, a state in which the transmission function in the transmission unit 12 and the reception function in the reception unit 13 of the wireless tag 10 c are stopped is indicated by a long and short dashed rectangle. A solid line indicates that the LF reception signal of the LF reception unit 15 is activated, and that these transmission / reception functions are moved to an operation (transmission and reception signal standby) state.

  In the operation of the wireless tag 10c, the reader 20, and the LF setting / interrogator 30 and the exchange of signals between these devices shown in the figure, first, an activation signal from the LF setting / interrogator 30 is sent to the wireless tag 10c (multiple tags 10c). Is received by the reception function of the LF receiver 15 (the activation signal is synchronous with the wireless tag 10c) (step Sc1). Thereby, the transmission function of the transmission unit 12 is activated (step Sc2), and a synchronization request signal is transmitted to the reader 20 (step Sc3). The subsequent operations of the wireless tag 10c and the reader 20 and the exchange of signals between the two devices (steps Sc4 to Sc6) are the same as steps Sa3 to Sa5 in FIG.

In addition, when the reader 20 side cannot receive the transmission of the wireless tag 10c that is normally performed after synchronization, that is, when there is no signal of the wireless tag 10c at the designated timing, the wireless communication that the reader 20 side normally performs after synchronization in FIG. The following can be assumed as in the case where the transmission of the tag 10a cannot be received.
(1) The wireless tag 10c has moved out of the receivable range of the reader 20.
(2) Another new wireless tag 10c appears and collides with a wireless signal transmitted by the new other wireless tag 10c.
(3) An abnormality of the wireless tag 10c such as a battery exhaustion has occurred.

  In the wireless tag 10c, the LF receiver 15 that receives the LF signal can be in a standby (standby) state with low power consumption. Therefore, in order to reduce the power consumption of the wireless tag 10c, it is important to enable only the function of receiving the LF signal and stop other functions except when necessary.

[Second Embodiment: Method of Changing Reception Frequency of Reception Function of Tag According to Prewritten Information]
The second embodiment is a method in which there is no interrogator but a reader (receiver) is present, and the frequency (interval) of reception of a wireless tag having a reception function is changed, that is, synchronization adjustment is performed from the wireless tag side. It is.
Even in a port where there is no LF gate corresponding to the interrogator, it is transmitted from a dedicated wireless tag that activates the reception function (RX) equipped in the wireless tag and transmits a radio wave of location information for recognizing the arriving port. It is important that the wireless tag absorbs the data to be stored.
In order to effectively perform this operation, a route route is written in the wireless tag when the container ship is loaded, and the reception frequency of the wireless tag is increased in the vicinity of the scheduled arrival time at the port where the LF gate does not exist.

Note that a normal wireless tag has only a transmission function and does not have a reception function. However, the wireless tag of the present embodiment has a reception function, and corresponds to “Position Tag (position tag)”. Since it operates as a “reader”, it is referred to as a “wireless tag (and reader)”.
This “Position Tag” is a device that transmits position information to a wireless tag using UHF waves. As the location of the “LF gate” at the port, a gantry crane or the like is assumed as in the case of the “LF gate”. Further, the transmission distance of “Position Tag” is about several hundred meters (˜1 km). For this reason, in addition to the gantry crane, it can be installed in the management building of the port container yard.
In this embodiment, it is assumed that “LF Gate” does not exist in all ports and “Position Tag” is installed.

As an example, FIG. 7 shows the time at which a container ship with a container wireless tag (and reader) 40 was called. 8 shows the configuration of the container wireless tag (and reader) 40, and FIG. 9 shows an example of the operation of the container wireless tag (and reader) 40.
Here, the port call schedule of the container ship and the configuration and operation of the container wireless tag (and reader) 40 shown in FIGS. 7 to 9 will be described in detail in order in conjunction with the port call of the container ship.

Figure 7 shows the voyage and calling of a container ship. This container ship departed from Yokohama Port at 13:48 on June 16, 200X. After that, the port arrived at Nagoya Port at 6:27 on June 17th, departed from Nagoya Port at 18:14 on the same day, and arrived at Kobe Port at 8:17 on June 18th the following day. Departed from Kobe Port at 12:56 and arrived at Kitakyushu Port at 10:12 on June 19th.
FIG. 8 shows the configuration of the device that effectively operates the container wireless tag (and reader) 40 in accordance with this voyage and port call, and FIG. 9 shows the operation status thereof. is there.

  In the configuration shown in FIG. 8, the container wireless tag (and reader) 40 has a timer 41 having a time by itself, a memory 42 for recording a port call schedule, and a function for recording or changing the schedule in the memory 42. A writing unit 43, a recorded port call schedule and a time information of the timer 41, a control unit 44 that determines activation or operation change of the container wireless tag (and reader) 40, and reception of radio waves according to the control unit 44. It has the receiving part 45 which has RF function to perform. With this RF function, the signal (radio wave) of the Position Tag 90 having a unique ID installed at each port and transmitting a signal identifying the port is received.

FIG. 9 shows that the container wireless tag (and reader) 40 increases the reception frequency of 30 minutes before and after the scheduled port call time to 5 times (every 2 minutes) the reception frequency at other times (for example, every 10 minutes). It shows that it is increasing.
For example, the scheduled time of arrival at Kobe Port is recorded in the container wireless tag (and reader) 40 at 8:30 on June 18, 200X. Therefore, for 30 minutes before and after this, that is, from 8:00 on June 18, 200X to 9:00 on the same day, the container wireless tag (and reader) 40 sets the reception frequency at intervals of 2 minutes. As a result, the radio signal from the Position Tag 90 installed at Kobe Port is 8:02, 8: 4, 8: 6, 8: 8, 8:10, ..., 8:30, 8:32 Minutes, ..., 8:56, 8:58, and more detailed information on event occurrence (arrival) can be accumulated. In this case, as shown in FIG. 7, it was 8:17 on June 18, 200X that the port arrived at Kobe Port, so the record of the container wireless tag (and reader) 40 was recorded on June 18, 200X. At 8:18 (or at 8:16 on June 18, 200X, just before), a record of receiving a radio signal from Position Tag 90 in Kobe Port is left.

If the reception frequency of the container wireless tag (and reader) 40 does not change (every 10 minutes), the arrival at Kobe Port will be 8:20 on June 18, 200X (or June 18, 200X 8). Since it is unlikely that the radio wave from the port will be received at 10:10, it will be 8:30 on the same day after arriving at the port, so there will be no detailed record.
On the other hand, in order to always keep a fine record (every 2 minutes), the power consumption increases according to the reception frequency, and the capacity of the memory 42 for storing the record also increases due to less meaningful data. These issues are overcome by adjusting the reception frequency by having an event schedule and time.

Next, an embodiment in which a synchronization request is made from a tag at the arrival time will be described.
In this case, the transit route is written in the tag when the container ship is loaded, and synchronization is established by transmitting a synchronization request signal from the tag near the scheduled arrival time at the port where no LF gate exists.

In the configuration of the container wireless tag (and reader) 50 shown in FIG. 10, the container wireless tag (and reader) 50 includes a timer 51 having a time by itself, a memory 52 for recording a port call schedule, and the schedule. A writing unit 53 having a function of recording or changing to the memory 52, and a control unit for determining activation or operation change of the container wireless tag (and reader) 50 from the recorded port call schedule and time information of the timer 51 54, and a receiving / transmitting unit 55 having an RF function for receiving radio waves in accordance with the control unit 54. The RF function of the container wireless tag (and reader) 50 includes two types of reception functions RX. One is a function of receiving UHF (radio waves), and power consumption is relatively high even during reception standby. The function of receiving the other LF (magnetic field) requires less power consumption even in a reception standby state.
Therefore, power consumption can be suppressed by stopping the function of receiving UHF (radio waves) while the container ship is sailing. Then, when the container ship approaches the scheduled arrival time, a synchronization request signal is transmitted from the container wireless tag reader.

FIG. 11 shows an example in which a synchronization request is made from the container wireless tag (and reader) 50 at the port arrival time. In the memory 52 of the container wireless tag (and reader) 50, the port to be called and its date and time are written.
Note that the frequency of reception of the container wireless tag (and reader) 50 is low during a period when the port is not calling, that is, while the container ship is sailing. Further, no synchronization request signal is transmitted during this period.
Here, when the port call schedule information and the timer 51 of the clock function are written, the container radio tag (and reader) 50 transmits a synchronization request signal to the port. In addition, increase the reception frequency. When a synchronization information response is returned from the reader installed at the port by this synchronization request signal, synchronization is established according to the information.
When this synchronization is established, the container wireless tag (and reader) 50 stops transmitting the synchronization request signal, further increases the reception frequency, and obtains the reception information from the Position Tag 91 more finely.

[Third Embodiment: Method of Changing Tag Reception Frequency According to Signal Reception Status from Reader ]
If the Lee Da whether we gradually wireless tag moves away, the radio waves of the reader wireless tag can not be received. In this way, when the wireless tag can no longer receive the reader 's radio waves,
The wireless tag itself performs synchronization such that the frequency of reception of the wireless tag is lowered (less) (that is, the reception interval is increased).
At that time, the wireless tag that cannot receive the radio wave from the reader increases the reception interval unless the input from the sensor mounted on the wireless tag is changed. Moreover, such a wireless tag transmits a synchronization request signal at regular intervals. FIG. 12 shows the relationship between the wireless tag and the reader and how the wireless tag operates.
If the wireless tag moves and returns to the reader again, or approaches another reader, the reader receives the synchronization request signal transmitted by the wireless tag at regular intervals. When the reader receives a synchronization request signal from the wireless tag, the reader works to establish synchronization of the wireless tag. FIG. 13 shows the relationship between the wireless tag and the reader and how the wireless tag operates.
FIG. 14 shows the configuration of this wireless tag.

Hereinafter, when the wireless tag 70 moves away from the reader 60 (FIG. 12) and when the wireless tag 70 moves closer to the reader 60 (FIG. 13), the operations will be described in order. To do.
In FIG. 12, the wireless tag 70 is initially in a range where radio waves are captured by the reader 60. In this state, the reception interval at which the wireless tag 70 receives a signal from the reader 60 is short. The same wireless tag 70 does not transmit a synchronization request signal to the reader 60. The reason is that there is a wireless tag 70 in a range where radio waves are captured by the reader 60, and synchronization transmitted by the wireless tag 70 has already been established. When the wireless tag 70 moves from this state and radio waves do not reach the reader 60, the wireless tag 70 increases the reception interval. In addition, the wireless tag 70 transmits a synchronization request signal. In this way, the next time the radio wave is within the radio wave capturing range of the reader 60, it is prepared.

FIG. 13 shows an operation of the wireless tag 70 in a state where the radio wave of the wireless tag 70 is in a place where it does not reach the reader 60. At this time, the wireless tag 70 has a wide reception interval. The wireless tag 70 transmits a synchronization request signal.
When the wireless tag 70 moves and falls within a range where the reader 60 can capture radio waves, the reader 60 corresponds to the synchronization request signal, and synchronization of transmission of the wireless tag 70 is established. The wireless tag 70 stops transmitting the synchronization request signal, and instead receives the signal from the reader 60 frequently by shortening the reception interval.

  As described above, by controlling the operation depending on whether the wireless tag 70 is within the radio wave capturing range of the reader 60 or where the radio wave does not reach, power consumption for reception standby is saved and effective synchronization is achieved. It can be established.

The configuration of the wireless tag 70 that performs such an operation will be described with reference to FIG. The wireless tag 70 roughly holds a transmission unit 75 having a transmission function, a reception unit 71 having a reception function, a control unit 72, and a reception history (the time when a signal sent from the reader to the wireless tag is received). There is a memory 74 and a timer 73 for time information.
When the wireless tag 70 receives an activation (transmission) request signal from the reader 60 by the reception unit 71, the control unit 72 controls the operation of the transmission unit 75 so as to transmit a normal signal after synchronization is established. The receiving unit 71 is also controlled to operate with a short reception interval synchronized with the reader 60.

  However, the radio signal from the reader 60 has not been received for a while based on the reception history in the memory 74 and the information from the timer 73 (for example, the reception times of the nearest several times of the reception history and the timer 73 at that time) When it is determined that the difference from the time is several times the synchronization interval), the control unit 72 of the wireless tag 70 controls the transmission unit 75 to transmit a synchronization request signal. At the same time, the reception unit 71 is placed in a reception standby state with a long reception interval so as to wait for synchronization-related information sent back from the reader 60.

[Fourth Embodiment: Method for Determining Synchronization of Tags When There Is No Other Tag in the Reader or Surrounding Area]
In the present embodiment, the wireless tag performs the operation of the actuator, transmission of radio waves, log storage, and the like, which are triggered by a change in the state of the current sensor mounted on the wireless tag. Alternatively, the operation of the actuator of the wireless tag, transmission of radio waves, log storage, and the like are performed using the state continuation for a certain period of time accumulated in the wireless tag as a trigger. Alternatively, it refers to its own past history to determine whether to change or continue such as transmission. Accordingly, even when there is no reader (interrogator, receiver) or other wireless tags in the vicinity (appropriate power consumption such as unnecessary transmission) can be appropriately handled.
FIG. 15 shows the configuration of the wireless tag 80 that determines synchronization by itself, and FIG. 16 shows the operation of the wireless tag 80. FIG. 17 shows a situation where there are a plurality of wireless tags 80.

As shown in FIG. 15, the wireless tag 80 includes the following various components.
First, there are various sensors 81 such as a vibration sensor and an illuminance sensor. The vibration sensor can recognize that a fixed object is moved by someone touching it. In addition, it is assumed that the illuminance sensor is started from night to noon, or lighting is turned on in a warehouse or the like to start work.
Secondly, there is a control unit 82 that receives the status change signal from the sensor 81 as information input.
Thirdly, there is an actuator 83 (referred to here as an apparatus or device that performs some kind of operation) such as an LED (Light Emitting Diode) or a buzzer controlled by the control unit 82. The LED can emit light, and the buzzer can inform the user of the above-described situation change by sound. For example, when the wireless tag 80 vibrates and the vibration sensor is activated, or when the wireless tag 80 moves out of the range where radio waves from the reader reach, the LED or buzzer is operated to notify the user to that effect. Can do.
Similarly, there is a fourth receiving / transmitting unit 84 having an RF function controlled by the control unit 82. This RF function transmits radio waves and waits for reception of radio waves.
Fifthly, there is a log storage unit 85 that is also controlled by the control unit 82 and stores the above-described log of status change in a record, and sixthly, a storage memory 86 of the storage destination.

FIG. 16 shows the operation of the wireless tag 80. FIG. 16A shows a wireless tag 80 equipped with a vibration sensor as the sensor 81. The vibration sensor works to such an extent that the wireless tag 80 can be recognized as being moved. Then, the RF function (reception function) in the reception / transmission unit 84 of the wireless tag 80 is frequently operated. If the sensor 81 does not work for a while (for example, about 20 minutes), the reception frequency is reduced this time.
FIG. 17 shows a situation where there are a plurality of wireless tags 80. As shown in FIG. 17A, the plurality of wireless tags 80 are simultaneously vibrated, and synchronization is established between the wireless tags 80. That is, the container with the wireless tag 80 mounted thereon is loaded on the anchored container ship, and vibration is applied when the container is loaded. A specific vibration (related to the synchronization of the tag operation) is grasped from the gantry crane and transmitted to the wireless tag 80 of the container loaded on the entire container ship.

  FIG. 16B shows a wireless tag 80 in which an illuminance sensor is mounted as the sensor 81. In the wireless tag 80, the RF function (reception function) of the reception / transmission unit 84 is frequently operated during a period when the illuminance sensor is considered bright. On the other hand, if the illuminance sensor does not work for a while after the illumination is turned off, the reception frequency is reduced. As shown in FIG. 17B, when a plurality of wireless tags 80 are illuminated all at once, synchronization is established between the wireless tags 80. That is, many containers with the wireless tag 80 attached are placed in the container yard, and a dedicated light (illumination) is turned on here. The tag operation is synchronized by the light of the light illumination.

If a standby state with a high reception frequency is always set to obtain detailed information, a large amount of power is consumed as compared with the capacity of a battery that can be mounted on the wireless tag. However, power consumption can be reduced by controlling the reception frequency as in this embodiment.
In addition, since synchronization can be established between neighboring wireless tags, when some notification is required from one wireless tag to another wireless tag, transmission is performed at the timing when the reception function operates. It is possible to reliably notify. If synchronization has not been established, in order to receive notifications from other wireless tags, the reception state must be ensured at all times, which consumes a large amount of power.

  Furthermore, as a method of changing the tag operation from the past history, an example will be described in which actuator operation, transmission of radio waves, log storage, and the like are performed using a state continuation or change trend for a certain period in the past as a trigger.

  Here, a wireless tag equipped with an acceleration sensor is assumed. This wireless tag stores a fixed pattern of acceleration changes that are swaying during transportation for various transportation means such as trucks, railways, ships, and aircraft. Since the stored pattern and the acceleration change during actual transportation are collated to estimate which transportation means is present, if the estimated transportation means is recorded in the memory in the wireless tag, By reading the record, it is possible to obtain a history of how much transportation has been carried by what means of transportation.

FIG. 18 shows an example of recording the result of determining the situation (by what is being carried) that the wireless tag is moving from the change in acceleration.
Although some transportation means are listed in FIG. 18, the change in acceleration by the transportation means has its own characteristics. Freight rail transport, cargo air transport, cargo truck transport, cargo ship maritime transport, and their typical change patterns of acceleration are shown. In addition, there is a cargo transshipment work using forklifts and cranes, and changes in acceleration are also shown.
The characteristics of these acceleration changes can be judged by the wireless tag, and it can be recorded in what is the moving means and from what time to when was the moving means.
From the above, it is possible to obtain information on how the moving means is used and transported by the wireless tag.

Next, a wireless tag equipped with a temperature sensor will be described.
When a wireless tag equipped with a temperature sensor is placed outdoors, the change in temperature is generally the lowest in the early morning, the temperature rises by noon, reaches the highest after noon, and drops until the next morning in the evening. Is done. Using this temperature fluctuation, a simple observation function for transmitting observation data of the lowest temperature or the highest temperature by radio waves or storing it in a memory can be easily realized.

FIG. 19 shows a configuration of a weather (air temperature) observation wireless tag 100 that operates according to a representative value of temperature change.
This weather (temperature) observation wireless tag 100 is equipped with a temperature sensor 110. A sensor information acquisition unit 101 having a function of writing information acquired from the temperature sensor 110 to the memory 102 is provided, and temperature changes are accumulated in the memory 102. Further, the wireless tag 100 for weather (temperature) observation includes a timer 103 having a clock function, a transmission unit 105 having an RF function, and a transmission unit based on a time acquired from the timer 103 and a history of changes in temperature read from the memory 102. The control unit 104 controls the RF function 105.

In FIG. 20, the measured data of the temperature change obtained by installing the weather (air temperature) observation wireless tag 100 having the temperature sensor 110 mounted outdoors (in the shade) for five days is shown in a graph. This change in temperature records a minimum temperature in the early morning every day and reaches a maximum temperature after noon. The only exception is when the weather is bad, the maximum temperature is the time the day moved from the previous day. However, even in such a case, if there is the graph of FIG. 20, it is easy to obtain representative values such as the maximum temperature and the minimum temperature from the change trend of the temperature.
Then, from this accumulated temperature change (temperature change in FIG. 20) and the clock function by the timer 103, the control unit 104, for example, as described above, the daily maximum temperature and the minimum temperature (○ in the temperature change graph of FIG. 20). A representative value such as a point surrounded by) is obtained, and the result is transmitted to the information collection base station by operating the RF function of the transmission unit 105. At this time, the result of the representative value may be collectively transmitted to the information base station for several days, or may be transmitted to the information base station each time the result of the representative value is obtained.

  The present invention suppresses the power consumption of an active type wireless tag to extend the lifetime, and effectively operates the wireless tag when necessary. This makes it possible to use a wireless tag for a long period of time, which has been difficult until now, and a new application expansion can be expected.

It is a block diagram which shows the structure of the wireless tag which uses a sensor starting as a trigger. It is a figure which shows the exchange and operation | movement of a signal of the wireless tag shown in FIG. It is a block diagram which shows the structure of the radio | wireless tag which performs synchronous starting by the time starting of a clock. FIG. 3 is a diagram showing signal exchange and operation of the wireless tag shown in FIG. 2. It is a block diagram which shows the structure of the radio | wireless tag which performs synchronous starting by the synchronizing signal from the outside. FIG. 6 is a diagram showing signal exchange and operation of the wireless tag shown in FIG. 5. It is a figure which shows the port call situation of the container ship which attached the wireless tag for containers. It is a block diagram which shows the structure of the radio | wireless tag for containers (and reader) which performs a synchronous request | requirement at a calling time. It is a figure which shows operation | movement of the wireless tag for containers (and reader) shown in FIG. It is a block diagram which shows the structure of the radio | wireless tag for containers (and reader | leader) which performs a synchronous request | requirement at the arrival time. It is a figure which shows operation | movement of the wireless tag for containers (and reader) shown in FIG. It is a figure which shows the change method of the tag reception frequency by the reception condition from a reader . It is a figure which shows the change method of the tag reception frequency by the reception condition from a reader . It is a block diagram which shows the structure of the tag which changes a receiving frequency with the receiving condition from a reader . It is a block diagram which shows the structure of the structure of the radio | wireless tag which determines a self-synchronization. FIG. 16 is a diagram illustrating an operation of the wireless tag illustrated in FIG. 15. It is a figure which shows the condition where there are two or more radio tags which decide a self-synchronization. It is a figure which shows the example which records the result of having judged the tag condition from the change of acceleration. It is a block diagram which shows the structure of the radio | wireless tag for weather (temperature) observation which operate | moves with the representative value of a temperature change. It is a figure which shows the example of the temperature change obtained with the temperature sensor in FIG. It is a figure for demonstrating the synchronization and current consumption in the wireless module of a prior art.

Explanation of symbols

10a, 10b, 10c, 70, 80 ... wireless tag 11 ... mounted sensor 12, 22, 75, 105 ... transmission unit 13, 21, 45, 71 ... reception unit 14 ... clock 15 ... LF reception unit 20, 60 ... reader 30 ... LF setter / interrogator 40, 50 ... Wireless tag for containers (and reader)
41, 51, 73, 103 ... timer 42, 52, 74, 102 ... memory 43, 53 ... writing unit 44, 54, 72, 82, 104 ... control unit 55, 84 ... reception / transmission unit 81 ... sensor 83 ... Actuator 85 ... Log storage unit 86 ... Recording memory 90, 91 ... Position tag
DESCRIPTION OF SYMBOLS 100 ... Radio tag for weather (temperature) observation 101 ... Sensor information acquisition part 110 ... Temperature sensor

Claims (6)

A wireless tag that communicates with a reader wirelessly,
Signals from sensors mounted to the wireless tag, time synchronization from a clock mounted to the wireless tag, or a transmission unit for transmitting a synchronization request signal to the reader a start signal from the outside as a trigger,
Becomes a reception standby state by the trigger, thereafter, the a receiving portion to which the reader in response to the synchronization request signal to receive a synchronization signal to be transmitted,
Establishing synchronization with the reader by the synchronization signal received by the receiving unit,
A wireless tag characterized by that. A receiver for receiving signals from the reader by radio waves;
And a transmitting unit for transmitting the signal via radio waves to a reader,
The control unit
When the reception unit detects that the radio wave from the reader cannot be received, the reception unit controls the reception interval to be widened to enter a standby state for synchronization-related information sent back from the reader, and the transmission unit Controls to send a synchronization request signal at equal intervals to the reception interval ,
When the reception unit detects that the radio wave from the reader can be received, the reception unit controls the reception interval to be narrowed to receive the signal from the reader, and the transmission unit Control to stop sending synchronization request signal,
Radio tag which is characterized a call. A sensor,
As a trigger continuation between at periodic state where the sensor has detected the operation of the actuator, a radio wave transmitter, or a control unit for causing the storage of the log,
A wireless tag comprising: A wireless tag operation control method for communicating with a reader wirelessly,
A signal from a sensor mounted on the wireless tag, a time synchronization from a clock mounted on the wireless tag , or a synchronization request signal is transmitted to the reader using an activation signal from the outside as a trigger,
Further, it becomes the reception standby state by the trigger, and thereafter, receives a synchronization signal which the reader in response to the synchronization request signal is transmitted,
Establishing synchronization with the reader by the received synchronization signal;
A wireless tag operation control method. A wireless tag operation control method comprising:
The wireless tag is
A receiver for receiving signals from the reader by radio waves;
A transmitter for transmitting signals to the reader by radio waves;
With
When the receiving unit detects that the radio wave from the reader cannot be received, the reception unit in the receiving unit is widened to enter a standby state for synchronization-related information sent back from the reader, and the transmitting unit receives the reception Control to send synchronization request signal at regular intervals ,
When the reception unit detects that radio waves from the reader can be received, the reception interval in the reception unit is narrowed to receive a signal from the reader, and the synchronization request signal in the transmission unit Control to stop sending
A wireless tag operation control method. A wireless tag operation control method comprising:
As a trigger to continue between the at periodic state the wireless tag sensor provided in the detects the operation of the actuator, a radio wave transmitter, or, for saving the log,
A wireless tag operation control method.

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