JP2008003773A - Wireless tag and id reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten the time required for reading ID data by limiting wireless tags for sending ID data, to wireless tags having ID data belonging to a specific group. <P>SOLUTION: An ID data reader 10 sends a group designation command (S252) before sending an ID data request command (S254). Each of wireless tags (20a and 20b) stores data specifying a group to which it belongs, and the wireless tag sets itself to a no response mode of not responding to the ID request command send from the ID reader for a preliminarily determined time (S204b), in response to reception of the group designation command in the case that the group designated by the group designation command is not the group to which it belongs. Since the ID reader reads ID data sent from only wireless tags belonging to the specified group, the time required for reading ID data can be shortened. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wireless tag and an ID reader that reads ID data stored in the wireless tag. The wireless tag referred to in this specification is sometimes called an IC tag, an electronic tag, or an RFID.

A wireless tag system that can simultaneously read ID data transmitted by a plurality of wireless tags has been developed. Each wireless tag transmits stored ID data when receiving an ID request command transmitted by the ID reader. The ID reader can simultaneously read ID data transmitted by a plurality of wireless tags. Simultaneous reading of ID data is sometimes called multi-reading, congestion control, or anti-collision. Since the wireless tag system can be multi-read, it can be applied to various systems that identify and manage each of many articles with ID data.
In the article management by the wireless tag system, there is a case where it is desired to read only the ID data of the wireless tag attached to the article belonging to a specific group among various articles attached with the wireless tag. For example, in a car production factory, it is desired to read only ID data of parts constituting a cylinder block from a collection of parts attached with wireless tags.
In a conventional wireless tag system, a plurality of wireless tags that have received an ID request command transmitted by an ID reader transmits ID data. The ID request command is not sent to a specific wireless tag, but is sent to an unspecified number of tags. All the wireless tags that have received the ID request command transmit ID data. The ID reader reads ID data transmitted from each wireless tag. The read ID data is organized, and information on ID data belonging to a specific group is displayed as necessary. That is, in the conventional RFID tag system, even when it is desired to read the ID data of RFID tags belonging to a specific group, the ID data is read after reading the ID data of all RFID tags within the range that can communicate with the ID reader. There was a need to group.
In order to reduce the time cost, it is better to read the ID data faster. For this purpose, it is only necessary that all wireless tags that have received the ID request command do not transmit ID data, but only wireless tags belonging to a specific group can transmit ID data. By doing so, it is not necessary for the ID reader to read the ID data of all the wireless tags within the communicable range, and the time required for reading can be shortened.
Patent Document 1 discloses a technique for transmitting ID data only to RF tags belonging to a specific group (wireless tags referred to in the present specification). In Patent Document 1, data indicating the hierarchy to which each RF tag belongs is stored in each RF tag. Then, the hierarchical data is incorporated into a communication packet representing an ID request command transmitted to the RF tag by the tag reader / writer (ID reader referred to in this specification). When the RF tag receives the communication packet representing the ID request command, the RF tag reads the hierarchical data incorporated in the communication packet. When the read hierarchical data does not match the hierarchical data stored in itself, no response is made to the communication packet. On the other hand, if the hierarchical data incorporated in the communication packet matches the hierarchical data stored in the communication packet, processing for transmitting the own ID data is executed.

JP 2004-185070 A

According to the technique of Patent Document 1, by incorporating hierarchical data in an ID request command transmitted by a tag reader / writer, ID data is not transmitted to an RF tag belonging to a layer different from the layer embedded in the ID request command. . The number of RF tags that transmit ID data can be reduced. As a result, the time for reading the ID data of the RF tag can be shortened.
By the way, in order to realize multi-read in the wireless tag system, it is often necessary to perform communication a plurality of times between the ID reader and the wireless tag before reading one ID data. The details of the multi-read method will be omitted, but for example, when a wireless tag receives an ID request command transmitted by an ID reader, it sequentially transmits ID data stored by itself from the most significant bit. There is. In that case, communication is performed a number of times corresponding to the number of bits of the ID data between the ID reader and the wireless tag before reading one ID data. Until all ID data is read, the same number of communications as the number of bits is repeated as many times as the number of wireless tags transmitting ID data.
In the conventional technique described above, hierarchical data is incorporated into the ID request command. When hierarchical data is incorporated into an ID request command, it is necessary to perform communication as many times as the number of bits of the hierarchical data before all wireless tags read the hierarchical data. That is, in the conventional technique, as preparation for transmitting ID data only from a wireless tag having an ID belonging to a specific hierarchy, the ID reader performs communication with all wireless tags as many times as the number of bits of the hierarchical data. There is a need. Even if the number of wireless tags that transmit ID data is limited by incorporating hierarchical data in the ID request command, it takes a certain amount of time for all wireless tags to read the hierarchical data. There is a possibility that the effect of shortening the total time when reading is canceled out.
A technique for transmitting ID data in response to an ID request command only to wireless tags belonging to a specific group in a short time is desired.

The present invention can be embodied in a wireless tag that receives an ID request command transmitted from an ID reader without specifying a destination and transmits stored ID data to the ID reader. This wireless tag stores data for specifying a group to which the wireless tag belongs, and when the group specified command transmitted by the ID reader is received, the group specified by the group specified command is not a group to which the wireless tag belongs. No response is made to the ID request command transmitted by the ID reader during a predetermined time.
The wireless tag according to the present invention accepts a group designation command which is a command independent of the ID request command. Once the ID reader transmits a group designation command, a wireless tag that transmits ID data in response to an ID request command transmitted within a predetermined time thereafter is a wireless tag belonging to the group designated by the group designation command. Limited to tags. The number of wireless tags to be read by the ID reader can be limited to wireless tags belonging to a specific group. In multi-read, a process of reading a plurality of ID data transmitted simultaneously with time is often performed. That is, the total time required for the ID reader to read ID data is roughly proportional to the number of ID data transmitted. According to the present invention, since ID data is not transmitted from a wireless tag storing ID data that does not belong to a specific group, the time required for the ID reading process can be shortened.
Here, since the ID request command and the group designation command are independent commands, the group designation command does not request the wireless tag to transmit ID data. Therefore, the transmission of the group designation command from the ID reader to the wireless tag can be configured to be established by one communication. In one communication, each wireless tag can specify whether or not it belongs to a group that should respond to an ID request command transmitted from the ID reader next. That is, the ID reader needs only to send a group designation command once to prepare only the wireless tags belonging to a specific group to respond to the ID request command. Accordingly, it is possible to realize a wireless tag in which only wireless tags belonging to a specific group can transmit ID data in response to an ID request command in a short time.
Furthermore, the wireless tag according to the present invention can use the conventional ID request command as it is. That is, the wireless tag according to the present invention has an advantage that it is compatible with a wireless tag system including a conventional ID reader. For example, a conventional ID reader is disposed in a place where it is not necessary to manage articles attached with wireless tags for each group, and an ID reader capable of transmitting a group designation command is disposed in a place where it is necessary to manage each group. It becomes possible. A conventional ID reader can be used effectively.

  The wireless tag according to the present invention divides the stored ID data into a plurality of sub-data when responding to the ID request command transmitted by the ID reader, and divides the ID tag every time the ID request command is received. The sub data may be transmitted sequentially. Such a wireless tag is suitable for multi-reading as described above. On the other hand, such a wireless tag requires a plurality of communications between the ID reader and the wireless tag when reading one ID data. In multi-reading, the total time required to read ID is [number of ID data to be read] × [time required to read one ID data]. That is, even if the time required for one communication slightly increases, the total time required for reading increases as the number of ID data to be read increases and the number of communication required for reading one ID increases. Will increase greatly. If it takes time to prepare for transmitting ID data only to wireless tags belonging to a specific group as in the technique of Patent Document 1, the number of wireless tags that transmit ID data is limited as a result. The effect may be offset. In the wireless tag according to the present invention, the communication between the ID reader and the wireless tag performed when reading the ID data can be the same as the conventional one. That is, when the wireless tag according to the present invention is used, wireless tags that transmit ID data can be limited to wireless tags belonging to a specific group without increasing the time required to read one ID data. That is, the total time required for reading the required number of ID data can be shortened.

  The data specifying the group to which it belongs may be data independent of the stored ID data, or part or all of the stored ID data may be combined. In the former case, wireless tag groups having non-common ID data can be grouped. In the latter case, the amount of data that the wireless tag should store does not increase. Furthermore, when all of the stored ID data also serves as data for specifying a group, it is possible to easily confirm whether or not there is a wireless tag having specific ID data.

  The present invention can also be embodied in an ID reader that reads ID data from the above-described wireless tag. Prior to the transmission of the ID request command, the ID reader receives a group designation command for instructing that wireless tags belonging to a group other than a specific group do not respond to the ID request command for a predetermined time. It is characterized by sending. In other words, the ID reader stores the data specifying the same group as the group designated by the group designation command by transmitting the group designation command and transmitting the RFID tag for transmitting the ID data for a predetermined time. The wireless tag can be limited. Thereby, the total time required for reading the ID data can be shortened.

  The ID reader preferably includes a notification means for notifying that when a radio signal transmitted from the wireless tag cannot be demodulated or decoded. There is a possibility that the communication between the wireless tag and the ID reader is not normally performed. In particular, in the case of a wireless tag that obtains power from a wireless signal transmitted by an external device, the wireless signal transmitted by the wireless tag is extremely weak. In such a case, the wireless signal from the wireless tag received by the ID reader may not be strong enough to be demodulated or decoded into a digital signal. In such a case, by providing a notification means for notifying that the received radio signal cannot be demodulated or decoded, there is at least a radio tag belonging to the group designated by the group designation command even if the ID data cannot be read. It is possible to notify the user of the wireless tag to do so.

  According to the present invention, only the wireless tag belonging to a specific group responds to the ID request command without increasing the time required for one communication performed between the wireless tag and the ID reader when reading ID data. Thus, a wireless tag capable of transmitting ID data can be provided. In addition, an ID reader suitable for such a wireless tag can be provided.

Embodiments according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an outline of a wireless tag system. In this embodiment, a wireless tag system is applied to a production management system for managing parts constituting an automobile in an automobile production line. The wireless tag system includes a plurality of wireless tags 20a, 20b, 20c, and 20d, and an ID reader 10 that reads ID data stored in each wireless tag. The wireless tags 20a, 20b, 20c, and 20d are attached to the automobile parts 30a, 30b, 30c, and 30d, respectively. In addition, although a motor vehicle is comprised from a huge number of components, in FIG. 1, only four components 30a-30d are illustrated.
The ID reader 10 includes an ID reader main body 12, an antenna 14, a keyboard 16, and a display 18. The ID reader 10 is also connected to a host system 50 that manages the automobile parts 30a-30d.
When the automobile parts 30a-30d to which the wireless tags 20a-20d are attached are collected in front of the antenna 14 and an operator (not shown) operates the keyboard 16, the ID reader main body 12 operates and wirelessly passes through the antenna 14. The ID data stored in each of the tags 20a-20d can be read. The read ID data is displayed on the display 18 and transmitted to the host system 50.

  Each wireless tag stores unique ID data. An example of ID data is shown in FIG. In this embodiment, the ID data is represented by a 9-digit number. The upper two digits represent a number that identifies the vehicle type. The second digit of the third digit and the fourth digit represent a number for identifying the assembly module. For example, in the third and fourth digits, 01 represents a cylinder block, and 02 represents a cylinder head block. The lower five digits represent numbers that identify individual components. By using the ID data defined as described above, it is possible to manage the parts constituting the automobile for each vehicle type and each assembly module. For example, by specifying the upper two digits of the ID data, parts of a specific vehicle type can be grouped and managed. Alternatively, by specifying the third digit and the fourth digit, parts related to a specific assembly module can be managed as a group. Alternatively, by specifying the upper 4 digits, it is possible to manage by grouping parts related to a specific assembly module of a specific vehicle type.

  When the operator operates the keyboard 16 and inputs data specifying a group of automobile parts, for example, specifying the number “01” in the upper two digits of the ID data, the parts 30a-30d collected in front of the antenna 14 are entered. ID data of a wireless tag having ID data belonging to a group identified from among the IDs is read by the ID reader 10 and displayed on the display 18. In this way, the operator can confirm that the automobile parts attached with the wireless tags belonging to a specific group are surely collected in front of the antenna 14. The ID data read by the ID reader 10 is sent to a host system 50 that manages automobile parts. In this way, automobile parts are managed on the host system 50 for each group.

Next, communication performed between the ID reader 10 and the wireless tags 20a and 20b will be described with reference to FIG. FIG. 3 is a time chart of communication between the ID reader 10 and the wireless tag 20a and communication between the ID reader 10 and the wireless tag 20b. FIG. 3 shows the passage of time from top to bottom. First, the ID reader 10 transmits a group designation command (step S252). The designation of the group is to designate a specific number in the upper two digits of the ID data as described above, for example. Specifically, the signal transmitted from the ID reader 10 including the group designation command has, for example, the following contents.
Header portion: Contains data indicating the start of the signal.
Command part: Contains data specifying the type of command indicated by this signal. The data included in the command part is, for example, data indicating that a signal starting from the header part is a group designation command, or data indicating that it is an ID request command described later.
Parameter part: Data specifying parameters used when the wireless tag receiving this signal performs processing in response to the command part is included. When the command is a group designation command, a group is designated by data included in this parameter part. For example, when specifying a group of ID data whose ID data is 9 digits and whose upper 2 digits are “01” as in the example shown in FIG. 2, “01 *******” is set in this parameter part. Is set. Here, “*” (asterisk) means a wild card. Among the 9-digit ID data in total, the upper 2 digits are “01”, and the remaining 7 digits are optional ID data groups. Means to specify.

  The signal having the above configuration is converted into a radio signal and transmitted from the antenna 14 of the ID reader 10. Here, as shown above, the signal (group designation command or ID request command) transmitted from the ID reader 10 has no data specifying the wireless tag that should receive the signal. That is, the signal transmitted from the ID reader 10 is a signal transmitted to an unspecified number of wireless tags. Such a signal may be referred to as a broadcast notification or broadcast.

The group designation command transmitted from the ID reader 10 in step S252 is received by the wireless tags 20a and 20b (step S202a and step S202b). Here, it is assumed that the ID data stored in the wireless tag 20a is ID data belonging to the group designated by the group designation command transmitted from the ID reader 10 in step S252. On the other hand, it is assumed that the ID data stored in the wireless tag 20b is ID data that does not belong to the group designated by the group designation command transmitted from the ID reader 10 in step S252.
In the wireless tag 20a, the group designation command received in step S202a is analyzed, and the group designated by the group designation command is determined to be a group to which the ID data stored in itself (wireless tag 20a) belongs. (Step S204a). In this case, the wireless tag 20a does nothing. On the other hand, in the wireless tag 20b, the group designation command received in step S202b is analyzed, and it is determined that the group designated by the group designation command is not a group to which the ID data stored by itself (the wireless tag 20b) belongs. (Step S204b). In this case, the wireless tag 20b thereafter sets itself to a no-response mode that does not respond to the ID request command transmitted from the ID reader 10 during the period T2.

  The ID reader 10 transmits a group designation command in step S252, and then transmits an ID request command after a period T1 (step S254). Note that the period T1 is set to a time required for the wireless tag to receive and analyze the command after the ID reading device 10 transmits the group designation command, and set itself to the no-response mode. That is, when the ID reader 10 transmits an ID request command, the wireless tag that does not belong to the group designated by the group designation command is set to the no-response mode.

As described above, the ID request command is also a signal transmitted to an unspecified number of wireless tags. Accordingly, both the wireless tag 20a and the wireless tag 20b receive the ID request command (steps S206a and S206b).
The wireless tag 20a that has received the ID request command transmits the ID data stored therein in response to the ID request command (step S208a). The ID data transmitted from the wireless tag 20a is received by the ID reader 10 (step S256). That is, the ID data stored in the wireless tag 20 a is read by the ID reading device 10. On the other hand, the wireless tag 20b is set to the no-response mode when the ID request command is received (step S206b). Therefore, the wireless tag 20b does not respond at all to Step S206b. That is, even if the wireless tag 20b receives an ID request command from the ID reader 10, it does not transmit ID data.
As described above, among the wireless tags 20a and 20b, ID data is transmitted from the wireless tag 20a that stores ID data belonging to the group designated by the group designation command. On the other hand, ID data is not transmitted from the wireless tag 20b that stores ID data that does not belong to the group specified by the group specifying command. Since ID data is not transmitted from the wireless tag 20b, the ID reader 10 does not execute processing for reading the ID data of the wireless tag 20b. Thereby, in the ID reading process for the wireless tags 20a and 20b, the time required for reading the ID data of the wireless tag 20b can be shortened.

  The ID reader 10 performs a process of displaying the received ID data (step S258). Alternatively, a process (not shown) for transmitting the received ID data to the host system is performed. On the other hand, in the wireless tag 20b, after the no-response mode is set in step S210b, a process for canceling the no-response mode is performed after the period T2 (step S212b). That is, after the process of step S212b, the wireless tag 20b returns to the state of transmitting ID data in response to receiving an ID request command transmitted by the ID reader 10.

In FIG. 3, the wireless tags 20a and 20b have been described as an example, but the same is true even when a large number of wireless tags exist. Prior to the transmission of the ID request command, the ID reading device 10 stores the ID tag belonging to the group designated by the group designation command by sending the group designation command to the radio tag for sending the ID data. The wireless tag can be limited. In the ID data reading process, the ID reader 10 only needs to read ID data transmitted only from a wireless tag storing ID data belonging to a specific group. In multi-read, a process of reading a plurality of ID data transmitted simultaneously with time is often performed. That is, the total time required for the ID reader 10 to read the ID data is roughly proportional to the number of ID data transmitted. According to the present embodiment, since the process of reading the ID data of the wireless tag storing ID data that does not belong to a specific group is not performed, the time required for the ID reading process can be shortened.
In FIG. 3, the processing group indicated by the broken line 260 indicates the ID reading process itself. The ID reading process may be the same as the conventional process. Therefore, the time required to read one ID data is equivalent to that of a conventional wireless tag system. By transmitting the group designation command as a command independent of the ID request command, the number of wireless tags that transmit ID data can be increased without increasing the time required to read one ID data. Can be limited to tags. Thus, the total time required for the ID data reading process can be shortened.

In FIG. 3, the ID reading process indicated by the broken line 260 is achieved by one ID request command transmission (step S254) and one ID data transmission (step S208a) in response thereto. In multi-read, the wireless tag divides the stored ID data into a plurality of sub-data (typically divided for each bit of the ID data), and responds to an ID request command transmitted by the ID reader. In many cases, a protocol for transmitting sub-data of ID data is employed. That is, the process indicated by the broken line 260 in FIG. 3 includes a plurality of ID request command transmission processes and a plurality of ID data transmission processes.
Here, unlike the present embodiment, a case where data specifying a group is incorporated in an ID request command in order to cause only the wireless tag storing ID data belonging to a specific group to transmit ID data will be considered. In order to exchange ID data between the ID reader and the wireless tag by the ID request command, communication of the same number of times as the number of bits of the ID data is often required. In that case, the ID reader needs to perform communication with all the wireless tags as many as the number of bits of data specifying the group incorporated in the ID request command. That is, the ID reader needs to communicate with all the wireless tags a plurality of times before it can be determined whether or not each wireless tag belongs to a specific group. Multiple preparations are required for preparation for limiting the number of wireless tags that transmit ID data. Even if the number of wireless tags transmitting ID data is limited, the effect of shortening the total time required for the ID data reading process is diminished depending on the time required for the preparation.
On the other hand, in the wireless tag system of this embodiment, the group designation command and the ID request command are separate and independent commands, and the wireless tag does not need to return a response to the group designation command. A group designation command can be sent to all wireless tags with only one command transmission. The ID reader can limit the number of wireless tags that respond to the ID request command to be transmitted next by transmitting the group designation command only once. Since the time required to limit the number of wireless tags that transmit ID data only needs to be transmitted once as a group designation command, the total time required to read ID data can be reduced.

Next, ID data reception processing (step S256 in FIG. 3) by the ID reader 10 will be described. Here, although the ID reader 10 has received the radio wave indicating the ID data transmitted by the wireless tag, the process when the radio wave cannot be demodulated into the ID data will be described. In particular, in the case of a so-called passive wireless tag that obtains electric power from a radio wave transmitted from the outside, the power that can be supplied is weak, so that the intensity of the transmitted radio wave is insufficient for the ID reader to decode. there is a possibility. The following processing is effective in such a case. FIG. 4 is a flowchart of ID data reception processing in the ID reader 10.
The ID reader 10 executes the ID request command transmission process (step S254) shown in FIG. 3 and then executes the ID data reception process shown in FIG.
First, in step S402, a timer is started. This timer is for measuring a period during which a response carrier (wireless signal indicating ID data) transmitted by the wireless tag is detected. That is, the response carrier is continuously detected until a predetermined time is measured by the timer (steps S404 and S424).

When the response carrier is detected (step S404: YES), the next detected response carrier is demodulated (detected) (step S406). If the demodulation is performed normally (step S408: YES), the ID data is decoded from the demodulated response carrier (step S410). Here, the decoding includes a process of reading digital data including ID data from a response carrier including a noise error. If the decryption has been performed normally (step S412: YES), the response data is checked in step S414. The response data here is digital data obtained by the decoding process in step S410, and includes ID data and parity data for verifying whether the ID data is correct. In step S414, a parity check is performed. If the parity check is normal (step S416: YES), one ID data has been read normally and the ID data is stored (step S418). If the predetermined time has not elapsed (step S424: NO), the timer started in step S402 is prepared for detection of the next response carrier (step S404). If the result of the parity check in step S416 is abnormal (step S416: NO), the process in step S420 is performed. If the parity check result is abnormal, the response carrier from one wireless tag is normally decoded, so the number of times that the parity check result is determined to be abnormal can be read normally. Indicates the number of wireless tags that did not exist. Therefore, in step S420, the number of times that the result of the parity check is determined to be abnormal is counted.
On the other hand, if the response carrier is not demodulated normally (step S408: NO), or if the decoding is not normally performed (step S412: NO), the process of step S422 is performed. In this case, it can be determined that there is a response carrier, but it is not possible to determine the number of wireless tags that are transmitting response carriers. Therefore, in step S422, it is stored that demodulation or decoding has not been performed normally. By notifying the operator or the host system later that the demodulation or decoding has not been performed normally, it is possible to notify that there is a wireless tag whose ID data could not be read. The notification can indicate that some action is required for the worker or the higher-level system.

Specific examples of the present invention have been described above in detail, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of purposes at the same time, and has technical utility by achieving one of the purposes.

It is a schematic diagram of a wireless tag system. It is a figure which shows an example of ID data. It is a timing chart figure of communication of an ID reader and a wireless tag. It is a flowchart figure of ID data reception processing.

Explanation of symbols

10: ID reader 12: ID reader body 14: Antenna 16: Keyboard 18: Displays 20a, 20b, 20c, 20d: Wireless tags 30a, 30b, 30c, 30d: Automobile parts 50: Host system

Claims (5)

  Data that identifies the group to which the device belongs is stored, and when a group designating command transmitted by the ID reader is received, a predetermined time when the group designated by the group designating command is not a group to which the device belongs. The wireless tag does not respond to the ID request command transmitted by the ID reader during the period.   When responding to an ID request command transmitted by the ID reader, the stored ID data is divided into a plurality of sub-data, and the divided sub-data is sequentially transmitted every time the ID request command is received. The wireless tag according to claim 1.   3. The wireless tag according to claim 1, wherein at least a part of the stored ID data also serves as data for specifying a group to which the ID data belongs.   An ID reader that reads ID data from the wireless tag according to any one of claims 1 to 3, wherein a wireless tag belonging to a group other than a specific group is for a predetermined time prior to transmission of an ID request command. An ID reader which transmits a group designation command instructing not to respond to an ID request command.   5. The ID reader according to claim 4, further comprising notification means for notifying when a radio signal transmitted from a radio tag cannot be demodulated or decoded.

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