JP2000113127A - Wireless tag system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the collision of responses from a plurality of wireless tags and to remarkably reduce read time by securing time slots more than the number of read wireless tags concerning a multi-read system for a wireless tag system. SOLUTION: In the multi-read state of the wireless tag system, responses are continuously returned from wireless tags 5 to a reader/writer 2 in the order of time slots but when no response is returned for certain fixed time, the absence of tag data of wireless tags 5 in that time slot is judged so as to transmit a command to the wireless tags 5 for calling the next time slot number.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless tag system for performing wireless communication between a reader / writer connected to a host device and a plurality of wireless tags in a readable area of the reader / writer.

[0002]

2. Description of the Related Art At present, in a distribution business or the like, a bar code system printed on a product box or a product itself is generally used to manage each product information.

[0003] However, in printing bar codes or the like, information cannot be stored in the product itself, and all information must be managed and updated on the host side. Further, when reading barcodes, the reader must be brought into contact with each barcode, which requires a great deal of labor and time for the operator.

[0004] Recently, the wireless tag system which has begun to be used in the distribution industry and the transportation industry is an innovative invention in this respect. A wireless tag (wireless card) is defined as an IC card function added with a wireless data communication function. Since the wireless tag itself has a built-in memory, information can be individually stored in the wireless tag. In terms of security, the use of technologies such as an authentication function and encryption between the reader / writer and the wireless tag can improve the security.

[0005] In addition, the data contents can be changed or updated at any time via the reader / writer without contact with the wireless tag from the reader / writer for wireless communication, and the wireless tag within the same reading range can be timed. T using slot
The use of the multi-read method of the DMA (time-division multiplexing) method makes it possible to save labor by a so-called multi-read method of reading all at once.

[0006] Such a wireless tag system comprises a reader / writer (including an antenna unit) system for executing a read (write) command of the tag data of the wireless tag and storing the read tag data of the wireless tag, and a wireless tag. Most of the communication methods between the reader / writer and the wireless tag are half-duplex communication using the electromagnetic induction method.

For this reason, an article to which the wireless tag is attached is brought closer to the reader / writer to read and write. Data exchange between the reader / writer and the wireless tag differs depending on whether the wireless tag is a single wireless tag or a plurality of wireless tags in the communication area of the reader / writer.

In the case of single reading (writing), that is, when reading (writing) tag data of a single wireless tag, the reader / writer transmits a reading (writing) request command to the wireless tag. In response, the wireless tag transmits a response to the reader / writer.

On the other hand, in the case of multi-read, that is, when reading tag data of a plurality of wireless tags existing in the same electric field collectively, TDMA (time division multiplexing) is adopted.

Specifically, the reader / writer transmits a multi-read command to the wireless tag. On the other hand, each wireless tag selects a time slot to respond with a random number generated internally, and transmits the requested data to the reader / writer.

In this case, it is calculated by (one multi-read reading time) = (set number of time slots) × (time slot time per unit).

Therefore, in order to shorten the reading time, the number of time slots to be set may be reduced. However, when the number of time slots is small relative to the number of wireless tags existing in the same electric field, the tag data of a plurality of wireless tags assigned to each time slot compete with each other to cause collision. However, there is a problem that the time slot data becomes error data (transmission error or the like).

However, if the number of time slots is increased in order to avoid collision, there is a problem that the number of time slots of empty data increases, resulting in much waste.

That is, FIGS. 6 and 8 show a multi-read (a plurality of wireless tags can be stored in one) when the wireless tag system is used.
This is an excerpt of the case where the reading is performed every time, and shows the flow of the command response of the reader / writer ← → each wireless tag and the comparison of the reading time.

For example, if the set value of the time slot is 8,
The case where there are five wireless tags existing simultaneously in the reading area will be described.

First, a command for requesting multi-read is transmitted from the transmission antenna section of the reader / writer to the wireless tag. On the other hand, each wireless tag internally generates a random number to determine a time slot number.

Thereafter, the reader / writer sets the ID of each wireless tag.
In order to acquire D data, T (old) time = (number of time slots × one time slot time) is required.

In order to shorten the T (old) time, the number of time slots can be reduced, but in this case, responses of a plurality of wireless tags are transmitted in the same time slot. A transmission error occurs during reception by the reader / writer, and a phenomenon occurs in which tag data of either wireless tag cannot be received.

As a result, the number of repetitions of the multi-read operation is increased, and the read time is not necessarily shortened.

[0020]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems by performing wireless communication between a reader / writer and a plurality of wireless tags in a readable area of the reader / writer. It is an object of the present invention to provide a wireless tag system that can take a large time slot value with respect to the number of wireless tags and can greatly reduce the time required to read tag data of each wireless tag as compared with the related art. .

[0021]

A wireless tag system according to the present invention performs wireless communication between a reader / writer and a plurality of wireless tags in a readable area of the reader / writer. A first transmitting means for transmitting a multi-read command including a number to the wireless tag, and a response from the wireless tag within a predetermined time from a response reception start time for each time slot responding to the transmission by the first transmitting means. Determining means for determining whether or not there is a response; and when the determining means determines that there is no response from the wireless tag within a predetermined time, a response reception start time for each time slot is determined from the wireless tag. First changing means for making a change shorter than the time for receiving a response, When it is determined that there is no response from the wireless tag, the wireless tag includes a second transmitting unit that transmits a call command for the next time slot to the wireless tag, and the wireless tag performs multi-read from the reader / writer. When a command is supplied, setting means for setting a response response time based on the number of time slots included in the multi-read command, and before the time set by the setting means, a call command from the reader / writer is transmitted. A second changing unit for changing the set time by the setting unit when supplied, and a third transmitting unit for transmitting a response to the reader / writer when the set time by the setting unit comes. .

A wireless tag system according to the present invention performs wireless communication between a reader / writer and a plurality of wireless tags in a readable area of the reader / writer, wherein the reader / writer includes a multi-read command including a number of time slots. Transmitting means for transmitting to the wireless tag, first setting means for setting a response reception start time for each time slot in response to the transmission by the first transmitting means, and first setting means Determining means for determining whether there is a response from the wireless tag within a predetermined time from a response reception start time for each time slot according to,
When the determination unit determines that there is no response from the wireless tag within a predetermined time, the response reception start time for each time slot set by the first setting unit is set as a response from the wireless tag. A first changing unit for performing a change for shortening the received time by a time shorter than the receiving time, and a calling command for the next time slot when the determining unit determines that there is no response from the wireless tag within a predetermined time. A second transmitting unit for transmitting to the wireless tag, wherein the wireless tag is configured to transmit a time slot based on the number of time slots included in the multi-read command when the multi-read command is supplied from the reader / writer. Selecting means for selecting a number, and a response corresponding to the time slot number selected by the selecting means. A second setting means for setting a response time, before the set time according to the second setting means,
When a call command is supplied from the reader / writer, a second time for changing the time set by the second setting means is changed.
And a third transmitting means for transmitting a response to the reader / writer when the time set by the second setting means has come.

A wireless tag system according to the present invention performs wireless communication between a reader / writer and a plurality of wireless tags in a readable area of the reader / writer, wherein the reader / writer includes a multi-read command including a time slot number. Transmitting means for transmitting to the wireless tag, first setting means for setting a response reception start time for each time slot in response to the transmission by the first transmitting means, and first setting means Determining means for determining whether there is a response from the wireless tag within a predetermined time from a response reception start time for each time slot according to,
When the determination unit determines that there is no response from the wireless tag within a predetermined time, the response reception start time for each time slot set by the first setting unit is set as a response from the wireless tag. A first changing unit for performing a change for shortening the received time by a time shorter than the receiving time, and a calling command for the next time slot when the determining unit determines that there is no response from the wireless tag within a predetermined time. A second transmitting unit for transmitting to the wireless tag, wherein the wireless tag includes a random number,
Storage means for storing an identification number, and a time slot based on the number of time slots included in the multi-read command and a random number stored in the storage means when a multi-read command is supplied from the reader / writer. Selecting means for selecting a number, second setting means for setting a response time corresponding to the time slot number selected by the selecting means, and setting the reader before the time set by the second setting means. A second changing means for changing a set time by the second setting means when a call command is supplied from the writer; and a storage means when the set time by the second setting means is reached. And third transmission means for transmitting a response including the stored identification number to the reader / writer.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of a wireless tag system according to the present invention.

That is, the wireless tag system comprises a reader / writer 2 connected to a personal computer (PC) 1 as an upper device and an antenna unit 3 of the reader / writer 2.
Wireless communication with a plurality of multi-read type wireless tags (wireless cards) 5,... In the readable area 4.

The PC 1 comprises a control unit (not shown), an operation unit, a display unit, and a connection unit of the reader / writer 2.

As shown in FIG. 2, the reader / writer 2 comprises a control circuit 11 for controlling the whole, a control program, a memory 12 for storing various information, a transmission circuit 13, and a reception circuit 14.

The control circuit 11 is connected to the PC 1 and
Data is exchanged. For example, in response to reception of a multi-read command, transmission of a multi-read response is performed.

The antenna section 3 includes a transmitting antenna 15 and a receiving antenna 16.

The transmission circuit 13 is connected to the transmission antenna 15 and transmits data transmitted from the control circuit 11 to the wireless tag 5 using the transmission antenna 15.

The receiving circuit 14 is connected to the receiving antenna 16 and outputs received data from the wireless tag 5 received by the transmitting antenna 15 to the control circuit 11.

The wireless tag 5 is, as shown in FIG.
1 and a transmitting / receiving antenna 22.

As shown in FIG. 3, a control circuit 23 for controlling the whole, a control program, a random number, an ID
(Recognition number) Memory 2 for storing various information such as data
4, a demodulation circuit 25 and a power generation circuit 26.

The modulation / demodulation circuit 25 includes a transmitting / receiving antenna 22
And demodulates the received data from the reader / writer 2 received by the transmission / reception antenna 22 and outputs the demodulated data to the control circuit 23 and the power generation circuit 26, and transmits the transmission data from the control circuit 23 to the reader / writer 2 to the transmission / reception antenna 22 Is transmitted using the

The power supply generation circuit 26 generates a power supply voltage based on the received data (radio wave) from the modulation / demodulation circuit 25,
It is supplied to the control circuit 23 and the modulation / demodulation circuit 25.

Next, the multi-read processing in the above configuration will be described with reference to the flowcharts shown in FIGS. 4 and 5 and the exchange of commands and responses shown in FIGS. 6 and 7.

First, the processing of the reader / writer 2 will be described with reference to the flowchart shown in FIG.

That is, when a multi-read command is supplied from the PC 1, the control circuit 11 generates a multi-read command including the number of time slots (ST1). Then, the control circuit 11 generates the multi-read command (transmission). (Time tm1 = 2 ms) using the transmitting circuit 13 and the transmitting antenna 15 to transmit the wireless tag 5 in the readable area 4;
And turns on a timer for determining the presence or absence of a response from the wireless tag 5 (ST2).

Thereafter, the control circuit 11 counts up a timer (ST3) and determines whether or not there is data received from the wireless tag 5 within a predetermined time (t2 = 5 ms) (S3).
T4).

As a result, when the reception data from the wireless tag 5 is received within the predetermined time (t2 = 5 ms), the control circuit 11 resets the timer and turns it on again (ST5), and the remaining reception number (set time slot) (Number = initial value) is subtracted by “−1” (ST6), and it is determined whether the remaining reception number is “0” (ST7).

If the result of this determination is that the number of remaining receptions is "0", the control circuit 11 shifts to the next processing. If the number of remaining receptions is other than "0", the control circuit 11 returns to step 3.

In step 4 described above, if the reception data from the wireless tag 5 has not been received after a lapse of a predetermined time (t2 = 5 ms), the control circuit 11 issues a calling slot command designating a time slot number. , And transmits the generated calling slot command to the wireless tags 5 in the readable area 4 using the transmitting circuit 13 and the transmitting antenna 15, and proceeds to step 5 (S5).
T8). Post-transmission, time slot number designation (ST8) Next, the processing of the wireless tag 5 will be described with reference to the flowchart shown in FIG.

That is, when the multi-read command from the reader / writer 2 is received by the transmission / reception antenna 22, demodulated by the modulation / demodulation circuit 25, and supplied to the control circuit 23 (ST11), the control circuit 23 records it in the memory 24. The calculation is performed using the random numbers set in advance, and a time slot within the number of time slots included in the multi-read command is selected (ST12).

Next, the control circuit 23 sets a timer at a time corresponding to the time slot number, and then turns on the timer (ST13).

Thereafter, the control circuit 23 waits for a call command from the reader / writer 2 (ST1).
4) When the timer times out without receiving this command (ST16), the response including the ID data recorded in the memory 24 is modulated by the modulation / demodulation circuit 25 and transmitted from the transmission / reception antenna 22 to the reader / writer. 2 (ST17), and enters a command waiting state.

When the call command is received in step 14 before the timer expires, the control circuit 23 determines the time of the timer (earlier than the set time) according to the time slot number of the call command. After resetting the response start time as (time), the timer is turned on (ST15), and the process returns to step 14.

If the timer has not timed out in step 16, the process returns to step 14.

For example, the reading time of the wireless tag when the set value of the number of time slots is eight and the number of wireless tags is five will be described with reference to FIGS.

That is, from the reader / writer 2 to a plurality of wireless tags 5 existing in the readable area 4,
A multi-read command (transmission time tm1 = 2 ms) is transmitted. In contrast, the wireless tag 5 has an internal processing time (t
1 = 5 ms), each time slot (Tt = 20)
ms) and returns a response (T3 = 15 ms) according to each timing. At this time, when there is a response in the time slot, the actual response start time from the time slot start time is time t3 shown in FIG. The time t3 is 0 <t3 <t2. In this embodiment, each time slot interval> (t3 +
Response time).

The internal processing time (t1) is a command processing time inside the wireless tag 5 after receiving the command, and is a time required for command recognition, time slot selection, and the like.

6 and 7, when it is determined that there is no wireless tag 5 in the time slot 3 (t2 = 5 ms),
Call slot 4 command (transmission time tm2 = 4 ms)
Send

As a result, the reader / writer 2 calculates “the internal processing time t1 (5 ms) of the wireless tag 5 + the wireless tag presence / absence determination time (t2 = Tt−T3 = 20−15 = 5 ms) = 10”.
If no response is received from the wireless tag 5 after waiting for “ms”, a call slot 5 command is transmitted. The wireless tag presence / absence determination time (t2) is a time that the reader / writer 2 waits to determine whether or not a response is returned within the time slot.

In time slot 4, it is determined that there is no wireless tag 5 (t2 = 5 ms), and a calling slot 4 command (transmission time tm2 = 4 ms) is transmitted.

As a result, the reader / writer 2 operates for 10 ms.
If there is no response from the wireless tag 5, the calling slot 5 command is transmitted.

In time slot 5, it is determined that there is no wireless tag 5 (t2 = 5 ms), and a calling slot 4 command (transmission time tm2 = 4 ms) is transmitted.

As a result, the reader / writer 2 operates for 10 ms.
If there is no response from the wireless tag 5, a call slot 6 command is transmitted.

That is, when no response is returned from the wireless tag 5 even after the lapse of time t2 from the start point of the time slot 3, the reader / writer 2 determines that the wireless tag 5 is not allocated to the time slot 3. Then, a “wireless tag call command (slot NO4)” is transmitted.

When this is received, each wireless tag 5 determines the "time slot 4 start time" at the time of receiving, and resets each response start time. (However, the time slot number value of each wireless tag 5,... Does not change).

Similarly, the reader / writer 2 determines whether or not there is a response from the wireless tag 5 during the time t2 from the start of the next time slot, and performs the same operation if there is no response (the remaining time slot is 0). Until it becomes).

Therefore, the conventional wireless tag read time Told is the number of time slots “8” * 1 time slot (Tt = 20 ms) + multi-read command transmission time (tm1 = 2 ms) + internal processing of the wireless tag 5 Time (t
1 = 5 ms) = 167 ms.

On the other hand, the reading time Tnew of the wireless tag of the present invention is equal to the tag response meter “5” * 20 ms.
+ ｛Multi-read command transmission time (tm1 = 2m
s) + Internal processing time of wireless tag 5 (t1 = 5 ms)｝ +
3 * ｛Transmission time of call command (tm2 = 4ms) +
Time for determining that there is no wireless tag 5 in the time slot (t2 = 5 ms) + Internal processing time of wireless tag 5 (t1 =
5ms)｝ = 5 * 20 + (2 + 5) + 3 * (4 + 5 +
5) = 149 ms.

As a result, as described above,
The read time Tnew of the wireless tag is 149 ms, the read time Told of the conventional wireless tag is 167 ms, the shortened time Ta is 18 ms, and the read time of the wireless tag can be reduced by 10%.

As described above, in the multi-read state of the wireless tag system, a response is continuously returned from the wireless tag to the reader / writer in the order of the time slot, but if no response is returned for a certain period of time,
It is determined that there is no tag data of the wireless tag in the time slot, and a command for calling the next time slot number is transmitted to the wireless tag.

A wireless tag used in a wireless tag system is usually a multi-read command (a specific command).
Is received, each time slot to be responded to by a random number generated inside is selected, and the apparatus is in a standby state until the time slot is reached. Then, when a corresponding time slot is reached, a response (such as an ID of a wireless tag) is transmitted.

Here, in addition to the above functions, the wireless tag used in the present invention has a wireless tag having the designated time slot number when a "call command (time slot number designation)" is received from the reader / writer in the standby state. A response (such as the ID of a wireless tag) is immediately transmitted from the standby state to the reader / writer.

In addition, the reader / writer determines whether or not the tag data of the wireless tag exists in the time slot so that the time is equal to or less than half the time slot time.

Further, when the "time slot call command of the designated number" is transmitted, the time at the time of reception is set as the start time of the time slot of the designated number, and the radio which does not return a response according to the designated number is set. All tags reset the response start time, and the reader / writer performs the processing in accordance with the reset time.

As a result, it is possible to prevent the collision of responses from a plurality of wireless tags by setting the number of time slots larger than the number of read wireless tags, and to significantly reduce the read time.

As described above, the present invention provides a method for multi-reading data of a plurality of (not fixed) wireless tags simultaneously existing in a readable area of a reader / writer.
The number of timeslots set is reduced → the number of multi-reads increases due to the occurrence of many collisions (collisions), and the number of times of multi-reads is reduced → the collisions are reduced. It addresses the problem that it is very difficult to select the number of time slots to minimize time.

That is, according to the present invention, even if the value of the time slot is considerably large with respect to the number of wireless tags, it is possible to suppress an increase in the time of one multi-read, and to greatly reduce the reading time.

The present invention is particularly effective when the amount of transmission data such as image data is large, or when the data transmission speed is low in communication using the medium wave band or the like.

[0073]

As described above in detail, according to the present invention, in a wireless communication between a reader / writer and a plurality of wireless tags in a readable area of the reader / writer, the wireless tag can be used in a multi-read mode. It is possible to provide a wireless tag system in which the time slot value can be set larger than the number and the reading time of the tag data of each wireless tag can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a wireless tag system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an internal configuration of a reader / writer.

FIG. 3 is a block diagram showing an internal configuration of the wireless tag.

FIG. 4 is a flowchart for explaining a multi-read process.

FIG. 5 is a flowchart illustrating a multi-read process.

FIG. 6 is a diagram illustrating a reading time of a wireless tag.

FIG. 7 is a diagram illustrating a reading time of a wireless tag.

FIG. 8 is a diagram for explaining a reading time of a conventional wireless tag.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... PC 2 ... Reader / writer 3 ... Antenna part 4 ... Readable area 5 ... Wireless tag (wireless card) 11, 23 ... Control circuit 12, 24 ... Memory

Claims (6)

[Claims] 1. A wireless tag system for performing wireless communication between a reader / writer and a plurality of wireless tags in a readable area of the reader / writer, wherein the reader / writer transmits a multi-read command including a time slot number to the wireless tag. A first transmitting unit for transmitting to the wireless tag, and determining whether there is a response from the wireless tag within a predetermined time from a response reception start time for each time slot in response to the transmission by the first transmitting unit. Means for reducing the response reception start time for each time slot by a time shorter than the time for receiving a response from the wireless tag when the determination means determines that there is no response from the wireless tag within a predetermined time. First changing means for performing a change to be performed, and a response from the wireless tag within a predetermined time by the determining means. When it is determined that no second to send a call command for the next time slot to the wireless tag
Setting means for setting a response response time based on the number of time slots included in the multi-read command, when the multi-read command is supplied from the reader / writer, When a call command is supplied from the reader / writer before the time set by the setting means, a second changing means for changing the time set by the setting means, and the time set by the setting means is reached. And a third transmitting means for transmitting a response to the reader / writer. 2. The wireless tag system according to claim 1, wherein the predetermined time determined by said determination means is equal to or less than one half of the time of one time slot. 3. A wireless tag system for performing wireless communication between a reader / writer and a plurality of wireless tags in a readable area of the reader / writer, wherein the reader / writer transmits a multi-read command including a number of time slots to the wireless tag. First transmitting means for transmitting to the first transmitting means, first setting means for setting a response reception start time for each time slot responding to transmission by the first transmitting means, and each time slot by the first setting means. Determining means for determining whether or not there is a response from the wireless tag within a predetermined time from the response reception start time for each, and when determining that there is no response from the wireless tag within the predetermined time The response reception start time for each time slot set by the first setting means is First changing means for making a change shorter than the time for receiving a response, and calling for the next time slot when the determining means determines that there is no response from the wireless tag within a predetermined time. The second to send a command to the wireless tag
Selecting means for selecting a time slot number based on the number of time slots included in the multi-read command, when the wireless tag is supplied with the multi-read command from the reader / writer, Second setting means for setting a response time corresponding to the time slot number selected by the selection means; and a call command from the reader / writer is supplied before the time set by the second setting means is reached. A second changing means for changing the time set by the second setting means, and a third transmission for transmitting a response to the reader / writer when the time set by the second setting means has come. And a wireless tag system. 4. The wireless tag system according to claim 3, wherein the predetermined time determined by said determining means is not more than one half of the time of one time slot. 5. A wireless tag system for performing wireless communication between a reader / writer and a plurality of wireless tags in a readable area of the reader / writer, wherein the reader / writer transmits a multi-read command including a time slot number to the wireless tag. First transmitting means for transmitting to the first transmitting means, first setting means for setting a response reception start time for each time slot responding to transmission by the first transmitting means, and each time slot by the first setting means. Determining means for determining whether or not there is a response from the wireless tag within a predetermined time from the response reception start time for each, and when determining that there is no response from the wireless tag within the predetermined time The response reception start time for each time slot set by the first setting means is First changing means for making a change shorter than the time for receiving a response, and calling for the next time slot when the determining means determines that there is no response from the wireless tag within a predetermined time. The second to send a command to the wireless tag
The wireless tag comprises: a storage means for storing a random number and an identification number; and the number of time slots included in the multi-read command when the multi-read command is supplied from the reader / writer. Selecting means for selecting a time slot number based on the random number stored in the storage means; second setting means for setting a response time corresponding to the time slot number selected by the selecting means; A second changing means for changing the set time by the second setting means when a call command is supplied from the reader / writer before the set time by the second setting means; A third transmission for transmitting a response including the identification number stored in the storage means to the reader / writer when the time set by the means has come. RFID system characterized by comprising a means. 6. The wireless tag system according to claim 5, wherein the predetermined time determined by said determining means is equal to or less than half of the time of one time slot.