JPH11306297A - Data carrier system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an average ID retrieval time in the case of performing anti-collision by making an interrogator successively transmit four specific response requests and to stop a response to a data carrier (slave unit) which does not transmit a response afterwards. SOLUTION: An interrogator transmits a multi ID recognition command and sequentially transmits a response request signal. A slave unit which has HH in the 1st and 2nd bits of a self-ID returns a response signal. It stops a response to slave unit which does not return a response after that. When a response signal does not come back from all slave unit, the interrogator continuously transmits the response request signal. A slave unit which has HL in the 1st and 2nd bits of a self-ID returns a response signal. If a response also does not come here, the response request signal is continuously transmitted and a slave unit having an ID of LH responds. If a response also does not come here, the response request signal is continuously transmitted and a slave unit having an ID of LL responds.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention performs ID recognition and data retrieval of a plurality of data carriers each having a unique ID or a data code with an interrogator having one antenna. Regarding such a system.

[0002]

2. Description of the Related Art For example, in a data carrier system that performs gate management in a station ticket gate, etc., only one data carrier exists in a search area of an interrogator (or parent machine) for performing data search in principle. The data carrier which has always entered the search area may send its ID to the interrogator. However, in the case of a system in which a data carrier is used for inventory management of products placed on shelves, there are a plurality of data carriers in the search area, and all data in the search area are stored in such a manner. You cannot know the carrier ID. Therefore, a method has been proposed that can recognize an ID code even when a plurality of data carriers (child devices) simultaneously respond to signals. Here, this method is generally called anti-collision.

The invention described in Japanese Patent Application Laid-Open No. 8-36623 is one method for realizing anti-collision. According to the present invention, the period in which the data carrier (tag) responds is divided into two in accordance with the signal level of one bit of the ID code. For example, when the signal level of the ID code is “H”, the data carrier responds to the first period of the first half of the response period, and when the signal level of the ID code is “L”, the data carrier responds to the first period. The data carrier responds during the second period. At that time, in order to recognize one type of ID by one ID search sequence,
If there is a data carrier that responds in the first period, the data carrier having the “L” level ID code to respond in the second period from the interrogator sends a command signal for prohibiting the subsequent response. To send.

FIG. 5 shows an example of a general anti-collision sequence. By continuing such a sequence, by accumulating the history of the response period from the data carrier with respect to the determined ID code length, the interrogator can determine whether a plurality of data carriers exist in the same antenna, The ID can be recognized even in a situation where the data carrier responds at the same time. Note that FIG.
Since it is the same as that described in Japanese Patent Application Laid-Open Publication No. H10-209, its detailed description is omitted.

[0005]

In the conventional method shown in FIG. 5, the time required for ID recognition is long. FIG.
Calculate the time required for a search per bit in the sequence shown in FIG. The one-bit sequence is as follows when the ID is at the “L” level. (1) Response command transmission from the interrogator to the data carrier whose ID is “H” level (2) First data carrier response period (including the waiting time after transmission of the interrogator command) (3) From the interrogator (4) Second data carrier response period (including waiting time after transmission of the command of the interrogator) Here, the unit data period of data transmission / reception (ideal 1
Although a clock period is used, a finite response period is required when data changes regardless of any modulation method such as the FSK method and the ASK method. Therefore, a period of several clocks or more is allocated to a unit data period. ) Is T, the response command transmission time from the interrogator is 2T, and the period required for the tag response period is 4T.
It becomes T. The reason why this time is required is as follows. First, the interrogator takes a long time from the detection of the signal from the data carrier to the transmission of the response command, and since the data transmission can be performed only in unit bits, the command itself cannot be shorter than the unit data period. Is required. Also, during the response period of the data carrier, the time from when the detection system stops accepting a reply to the data carrier due to a large signal mixed into the reception system of the interrogator due to the transmission of the command by the interrogator and returns to normal. (During this period, the data carrier recognizes the response command signal from the interrogator and determines whether it should respond in the next period.) T and the data carrier actually responds after receiving the response command. Is included in the transmission time 3T of the data carrier for canceling the time variation until the data carrier is performed.

As a result, the search period per bit for a data carrier having an ID of "H" level is 6T, "
The H "level is 12T, and the search has been performed with an average of 9T per bit. This search period per bit becomes larger as the number of digits of the ID code assigned to the search target data carrier increases. That is, if the maximum number N of data carriers to be recognized is increased, the overall recognition time is greatly affected, and the average of the total search period is 9T × N. When searching for a plurality of products, luggage, or other data carriers, the search time may not be enough.

An object of the present invention is to reduce the average ID search time when performing anti-collision. It is another object of the present invention to quickly search for an ID when a plurality of data carriers are present in a response area of an interrogator.

[0008]

In order to solve the above problems, a data carrier system according to the present invention uses a data carrier existing in a response area based on an ID number consisting of a plurality of bits assigned to each data carrier. When searching, the interrogator sequentially transmits four response requests according to a continuous 2-bit data pattern, and when there is a response from at least one data carrier for each response request, In the first half of the response request, including the response confirmation data, the data carrier transmits no response confirmation data in the first half of the received response request, and the same data pattern as the search data pattern is included in the search target bit of its own ID. If there is, a response is returned in the second half of the response request, and if there is response confirmation data in the first half of the received response request, the response request is sent. The data carrier as well as change the search target bit in the next 2-bit data carrier that did not send a response request to stop responding in the sequence hereinafter.

A data carrier system according to another aspect of the present invention transmits an acknowledgment signal from an interrogator when a response is received from a data carrier, and instructs the responding data carrier to carry the search target bit. A first period for instructing a data carrier that has not responded to prohibit a response in the sequence, and a period subsequent to the first period, wherein a corresponding data pattern exists in a search target bit. A data carrier system for searching for a data carrier present in a response area based on an ID number consisting of a plurality of bits assigned to each data carrier by using a second period for returning a response from the data carrier. The device transmits a response acknowledgment signal during the first period when a response is received from the data carrier during the second period, If there is no response from the data carrier, the first specific signal is transmitted during the first period, the second specific signal is transmitted during the second period, and the data carrier is transmitted from the interrogator during the first period. When the response confirmation signal is not received, the response reference signal is returned only in the case of the same data pattern by referring to the search target bit of the own ID, and when the response confirmation signal is received from the interrogator in the first period. Moves a search target bit of its own ID by a predetermined bit when a response is returned in the previous second period, and stops a response to a subsequent search when a response is not returned.

Here, the search target bits are carried by two bits at a time, and four data patterns composed of a combination of 2-bit data are sequentially changed until at least one data carrier responds. It is desirable to repeat. When the first period and the second period are defined as a search period, the interrogator searches for the first data pattern of the four data patterns until a response is received from the data carrier. , A second search period predetermined as a timing for searching for the second data pattern of the four data patterns, and a third data pattern of the four data patterns. And a maximum of four search periods up to a fourth search period predetermined as a timing for searching for the fourth data pattern of the four data patterns. Is repeated, and the data carrier determines which of the first to fourth data bases based on the search start signal or the response confirmation signal transmitted from the interrogator. Determining whether the search period, to compare with the search target bit assigned data pattern and its own ID that search period, and returns a response in the second period according to the comparison result.

It is preferable that at least one of the first and second specific signals is a carrier wave having a signal of the same value of all unmodulated bits that can detect a reply from the data carrier.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing an embodiment of the present invention, the principle of the present invention will be described with reference to FIG. FIG. 3 is a diagram showing an example of the operation timing of the anti-collision of the present invention. In the following description, the data carrier will be referred to as a “child device”. FIG. 3 shows an example of the operation timing of the anti-collision of the present invention. In this example, four response periods are provided for every two bits of the ID code of the child device.

At the time of the anti-collision operation from the interrogator, first, a response request data ID indicating the ID search mode is transmitted, and subsequently, 8-bit blank data is transmitted for each response period. The response period is a T1 period for searching for HH, a T2 period for searching for HL, a T3 period for searching for LH, and LL.
The search is divided into T4 periods. A response confirmation signal is transmitted from the interrogator during the first four bits of the 8-bit blank data (response confirmation is made by setting a specific bit of the four bits to "H" or "L"). During the first four bits, each slave unit refers to its own ID and the search target bit. Each slave unit sequentially compares the two bits of its own ID, which is a specific search target, with the T1 period, and returns a response during the latter four bits of the search period if the data pattern is a relevant data pattern. .

When a search is performed in order from the T1 period and a response is received, the subsequent search pattern is not used, and the next 2
Move on to search for bits. When the interrogator receives the response, the interrogator transmits a response confirmation signal in the first half of the next 8-bit blank signal of the response period in which the response was received, and notifies the slave unit of the transition to the next 2 bits, and A response stop is instructed to the child device that did not perform the operation. This basic operation is described in
Since the invention is almost the same as the invention described in JP-B-36623, a detailed description is omitted. If there is no response confirmation signal from the interrogator during the first 4-bit period, the slave determines that it is searching for the next pattern (eg, searching for HL when searching for HH) and searches for its own ID. Reference the target bit.

FIG. 4 is a diagram showing a configuration example of a data carrier system using a data carrier according to the embodiment of the present invention. In the figure, an interrogator 10 includes an oscillating circuit 11 for generating a basic signal of a carrier, and a frequency dividing circuit for dividing the basic signal from the oscillating circuit 11 at different frequency division ratios to generate first and second carrier waves. 12, 13, and a selection circuit 15 for selecting and outputting one carrier wave from the first and second carrier waves, an output amplifier 16, a first tuning circuit 17 and a second tuning circuit 18 are provided. The interrogator 10 further includes an internal processing circuit 19 for generating a transmission signal and a demodulation circuit 20 for processing signals received by the tuning circuits 17 and 18. Internal processing circuit 1
The transmission signal generated in 9 is subjected to FSK modulation of the carrier in the selection circuit 15. The first tuning circuit 17 includes an antenna coil L1 and a tuning capacitor C1, and the second tuning circuit 18 includes an antenna coil L2 and a tuning capacitor C2. First tuning circuit 17 and second tuning circuit 18
Are connected in parallel as shown in the figure, but are connected via an adjustment capacitor C3 for both tuning circuits.

The slave unit 30 includes a transmission / reception coil 31, a tuning capacitor 32 connected in parallel to the transmission / reception coil 31, a rectifier circuit 33, a demodulation circuit 34 for performing FSK demodulation, an internal processing circuit 35, a transmission modulation circuit 36, The transmission load transistor 37 is provided. The internal processing circuit 35 includes a CPU 35a, a RAM 35b, a ROM 35c storing programs and the like, an electrically rewritable EEPROM 35d, and an interface 35e, like a general signal processing circuit.

The oscillation circuit 11 generates a 4 MHz reference signal, for example. This reference signal is supplied to the first and second frequency dividers 1
2 and 13 and the signal (125 KHz) divided by the first frequency dividing circuit 12 to 1/32 and the second frequency dividing circuit 13
Divided by 1/34 (117.6470588)
KHz). The internal processing circuit 19 has the logical value “H”
When the transmission of the data is instructed, the selection circuit 15
The output of the frequency dividing circuit 12 is selected and a signal of 125 KHz is sent to the tuning circuits 17 and 18 via the output amplifier 16. On the other hand, when the internal processing circuit 19 instructs the transmission of the data of the logical value “L”, the output of the second frequency dividing circuit 13 is selected by the selecting circuit 15 and the signal of 117.6470588 KHz is output through the output amplifier 16. To the tuning circuits 17 and 18.

The slave 30 transmits data by ASK modulation. Hereinafter, the operation of the slave unit 30 will be described. The power in the slave unit 30 is used by converting a carrier wave received by a tuning circuit composed of a transmission / reception coil 31 and a tuning capacitor 32 into a direct current by a diode and a smoothing capacitor of a rectifier circuit 33. When data is transmitted from the slave unit 30 to the interrogator 10, data generated by the CPU inside the internal processing circuit 35 is transmitted to the modulation circuit 36 via the interface 35e, and is transmitted to the modulation circuit 36 according to the output of the modulation circuit. The load transistor 37 is turned on / off. Then, the transmitting and receiving coil 31
, The strength of the electromagnetic coupling between the transmitting / receiving coil 31 and the antenna coil L1 changes. The demodulation circuit 20 of the interrogator 10 detects a change in the voltage generated at both ends of the antenna coil 17, specifically, a change in the amplitude of the 125 KHz signal output from the first frequency divider 12, and Demodulate the data. Actually, a demodulation operation is performed by a bandpass filter by detecting changes in the amplitude and phase of the sub-band signal sent from the data carrier with respect to the 125 KHz signal output from the first frequency dividing circuit 12. .

FIG. 1 shows a flow of an anti-collision operation of the data carrier system according to the embodiment of the present invention. The interrogator 10 transmits a multi-ID recognition command (Step 201). A preset waiting time is prepared as a preparation period for starting the data transfer between the interrogator 10 and the slave 30. During this waiting time, a counter (not shown) is set to 1 so that a search target starts from the first two bits as an initialization operation (step 202).

Following transmission of the ID recognition command, an 8-bit blank signal is transmitted (step 203). The 8-bit period T1 is a period in which a slave having an ID of "HH" responds as a first response period. The slave unit having “HH” in the first and second bits of its own ID returns a response signal in a period of 4 bits after the fifth bit of the blank signal. Specifically, the modulation circuit 36 in FIG. 4 turns on the transistor 37 to change the coupling relationship between the coils 31 and 17, modulates the 125 KHz signal representing the blank data from the interrogator 10, This change is detected (step 2
04).

When the interrogator 10 detects a response from the slave unit 30, it transmits a response confirmation signal. Upon receiving this response confirmation signal, the child device that returned the response carries the counter up by two bits and prepares for the next search. On the other hand, the child device that has not returned a response stops the response (step 206). Next, in order to shift to 2-bit search, the process proceeds to step 214, where the counter of the interrogator is carried (step 215), and the process returns to step 203.

If no response signal is returned from any of the slave units, the interrogator 10 continues to transmit an 8-bit blank signal (step 205). This 8-bit period T2
Is a period during which a slave unit having an ID of “HL” responds as a second response period. "H" in the first and second bits of the own ID
The slave having L "returns a response signal in a period of 4 bits after the fifth bit of the blank signal (this is the 8th and 5th bits and beyond when viewed from the ID calling mode signal). Go to step 215 and step 2
Return to 03.

Here, if there is no response, the interrogator 10 continues to transmit an 8-bit blank signal (step 209). The 8-bit period T3 is a period during which a slave having an ID of "LH" responds as a third response period. Since the operation is the same, the description is omitted. If there is no response here, the interrogator 10 continues to transmit an 8-bit blank signal (step 212). The 8-bit period T4 is a period in which a slave having an ID of “LL” responds as a fourth response period. Since the operation is the same, the description is omitted.

Here, a specific example will be described with reference to FIG. As slave units, slave unit 1 (ID: HHHL ...), slave unit 2 (ID: LH ...), slave unit 3 (ID: HHLH...)
The operation will be described using the case where three units are stored on a shelf. The interrogator transmits 8-bit blank data following the response request data ID indicating the ID search mode. The slave units 1 and 2 that have received the response request data ID
No. 3 checks the first and second bits of its own ID, and when it is HH, transmits a response signal in the fourth bit period after the fifth bit of the blank signal. In the example of FIG.
Since the first two bits of the ID are HH, these two slaves return a response. On the other hand, since the first two bits of the ID of the slave unit 2 are LH, no response is returned. When there is a response from at least one slave unit (although it is not possible to recognize how many interrogators have responded), the interrogator transmits a response confirmation signal. When receiving the response confirmation signal, the slave unit, if it has returned a response, carries the counter in its own device and sets the target to be compared with the next blank signal period to I
The third and fourth bits of D are set. On the other hand, the child device that has not returned a response is in a response stop state, and waits until the next response request data ID is sent.

In FIG. 2, since there is a response from the slave units 1 and 3 during the T1 period for searching for the HH, the interrogator sends a response confirmation signal in the first half of the next search period, T1 ', in the 4-bit period. Transmit and start searching for the next 2 bits. If there is no handset having an ID pattern of HH in the first 2 bits, the interrogator continues to transmit an 8-bit blank signal as a T2 period, Waits for a response from the slave unit having the HL ID pattern in the first two bits. If there is no response, an 8-bit blank signal is further transmitted as a T3 period, and the first two bits have the LH ID pattern. Waits for a response from the slave unit, and if there is no response, further T4
An 8-bit blank signal is transmitted as a period, and a response from a slave having an LL ID pattern in the first two bits is awaited.

This time, since there is a response in the T1 period, the process proceeds to the search of the third and fourth bits of the ID. Since the response acknowledgment signal is transmitted in the first four bits of the T1 'period, each child device can know that the search target bit has been shifted to the search of the ID 3 bits and 4 bits. In the period T1 ', there is no response because the slave units 1 and 3 do not have the HH ID pattern in the third and fourth bits. The interrogator continues to transmit an 8-bit blank signal as the T2 period. Handset 1 is 3,
Since the fourth bit has an HL ID pattern, a response is returned during this T2 period.
There is no response because there is no pattern.

Since there is a response from the slave 1, the interrogator does not proceed to the search for the third bit and the fourth bit of the search target period T3, but proceeds to the fifth and sixth bits of the search target. The interrogator transmits an acknowledgment signal in the first four bits of the T1 "period. The slave 1 carries the counter and sets the next comparison target to the 5th and 6th bits of the ID. The child device 3 that has not returned is in a response stop state, and waits until the next response request data ID is sent.

As described above, since two of the three units have stopped responding, the detection periods T1, T2, T2, and T3 correspond to the pattern of every two bits until the last bit of the ID of the slave unit 1 thereafter.
The response is detected at T3 and T4, and the ID of the child device 1 can be determined. The slave 1 stops responding, and thereafter the slaves 2 and 3
Is detected by the same method as described above. In the sequence shown in FIG. 1, the time required for a search per bit is calculated. The one-bit sequence is as follows when the ID is at the “LL” level.

(1) Transmission of a response command from the interrogator to the child device whose ID is “HH” level (2) First child device response period (including waiting time after transmission of the instruction of the interrogator) (3) (4) Second slave unit response period (including waiting time after interrogator command transmission) (5) ID from interrogator (6) Third slave unit response period (including the waiting time after transmission of the command of the interrogator) (7) The ID from the interrogator of which the ID is "LL" level Response command transmission to slave unit (8) Fourth slave unit response period (including the waiting time after transmission of the instruction from the interrogator) As in the case of FIG. Is 2T, and the period required for the response period of the slave unit is 4T. As a result, I
The search period for the slave unit whose D is “LL” is 24T.
However, some slave units respond when the response periods are the first, second, and third. The search periods required for these are 6T, 12T, and 18T, respectively, and the average search period per 2 bits is 15T. Becomes Converted per bit, the search period is 7.5T, which is a 17% improvement compared to the search period 9T in the conventional method shown in FIG.

When the same method is used to search the ID by three bits, the average search period per bit is 9T.
Is longer than in the case of 2 bits. The reason is that eight response periods are set in the case of 3 bits, and the response period of each bit is longer than six response periods in which three bits are repeated. Thus, I
It is desirable to search D every two bits.

[0031]

As described above, according to the present invention, anti-collision can be performed efficiently, and ID search of a data carrier can be performed at high speed.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an operation of a data carrier system according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an operation of the data carrier system according to the embodiment of the present invention.

FIG. 3 is a diagram illustrating an operation principle of the data carrier system according to the embodiment of the present invention.

FIG. 4 is a block diagram illustrating a configuration of a data carrier system according to an embodiment of the present invention.

FIG. 5 is a flowchart illustrating the operation of a conventional data carrier system.

[Explanation of symbols]

 10 interrogator 30 slave (data carrier)

Claims (7)

[Claims] When searching for a data carrier existing in a response area based on an ID number consisting of a plurality of bits assigned to each data carrier, four bits of two-bit data having two consecutive IDs of each data carrier are searched. A first step of issuing an instruction from the interrogator such that a data carrier having one data pattern selected from the combination pattern returns a response after a predetermined delay time; and a response from at least one data carrier. A second step of prohibiting subsequent responses in the same sequence to a data carrier that did not return a response in the event of a response, and instructing the interrogator to shift the search bit of the responded data carrier to the next two bits; If there is no response from any of the slave units, another data pattern different from the above four combination patterns And a third step of repeating the first and second steps by selecting a pattern, and repeating the above steps until all bits of the ID are completed. 2. An interrogator, when searching for a data carrier existing in a response area based on an ID number consisting of a plurality of bits assigned to each data carrier, sets the four bits corresponding to a continuous two-bit data pattern. One response request is transmitted sequentially, and when there is a response from at least one data carrier for each response request, the first response request includes the response confirmation data in the first half, and the data carrier transmits: If there is no response confirmation data in the first half of the received response request and the same data pattern as the search data pattern is in the search target bit of its own ID, a response is returned in the second half of the response request, and the first half of the received response request is returned. If the response carrier has response acknowledgment data, the data carrier that has already returned a response request
A data carrier system in which a data carrier that does not return a response request changes its bit and stops responding in the sequence thereafter. 3. When a data carrier existing in a response area is searched based on an ID number composed of a plurality of bits assigned to each data carrier, a response is made with the first half of a transmission signal of a predetermined bit output by an interrogator. A data carrier system which performs confirmation, and responds by modulating the transmission signal in the second half. 4. When a response is received from a data carrier, a response confirmation signal is transmitted from the interrogator to instruct the responding data carrier to carry the search target bit and to respond to the non-responding data carrier. A first period for instructing a response prohibition in the sequence, and a second period following the first period and returning a response from the data carrier when a data pattern corresponding to the search target bit exists. A data carrier system for searching for a slave unit existing in the response area based on an ID number consisting of a plurality of bits assigned to each data carrier using the interrogator during the second period. When there is a response from the data carrier, the response confirmation signal is transmitted in the first period, and when there is no response from the data carrier. Transmits a first specific signal different from the response acknowledgment signal during the first period, transmits a second specific signal during the second period, and the data carrier transmits the first specific signal during the first period. If the response confirmation signal has not been received from the interrogator,
The search target bit is referred to, and a response signal is returned only when the search target bit is the corresponding data pattern, and when the response confirmation signal is received from the interrogator in the first period, the previous 2. A data carrier system characterized in that if a response is returned during the period 2, the search target bit of the own ID is shifted by a predetermined bit, and if no response is returned, the response is stopped for subsequent searches. . 5. The method according to claim 4, wherein the search target bits are carried by two bits at a time, and four data patterns composed of a combination of 2-bit data are sequentially read from at least one slave unit until a response is received. A data carrier system characterized by repeating a search by changing a pattern. 6. The interrogator according to claim 5, wherein when the first period and the second period are defined as a search period, the interrogator waits until a response is received from the data carrier. A first search period predetermined as a timing for searching for the first data pattern, and a second search period predetermined as a timing for searching for a second data pattern of the four data patterns. A third search period predetermined as a timing for searching for a third data pattern of the four data patterns; and a timing predetermined for searching for a fourth data pattern of the four data patterns. The search is repeated for a maximum of four search periods up to a fourth search period, and the data carrier transmits a search start transmitted from the interrogator. It determines which of the first to fourth search periods is based on the signal or the response confirmation signal, and compares the data pattern assigned to the search period with the search target bit of its own ID, A data carrier system returning a response in the second period according to a comparison result. 7. The data carrier system according to claim 4, wherein at least one of the first and second specific signals is a signal having the same value for all bits.