JP2005293518A - Interrogator for wireless tag communications system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To securely acquire identification information on a wireless tag circuit element to be communicated irrespective of the type of data length thereof. <P>SOLUTION: Upon creation of access information for accessing a wireless tag circuit element To, to which a signal processing circuit 3 is intended to carry out an interrogation, a transmission part 11 of a high-frequency circuit 2 and an antenna 1 transmit this created access information in a non-contact manner to the wireless tag circuit element To. After transmission of this access information, a receiving part 12 and the antenna 1 receive a response signal transmitted by the wireless tag circuit element To in a non-contact manner to read the signal. A control circuit 4 extracts a CRC code from the read response signal, and specifies, based on this, the data length of the identification information on the wireless tag circuit element To contained in the read response signal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an interrogator of a wireless tag communication system that reads or writes information from and to a wireless tag capable of wireless communication of information with the outside.

  RFID (Ratio Frequency Identification) that reads / writes the information of a wireless tag by transmitting and receiving an inquiry and receiving a response from a reader / writer as an interrogator to a small wireless tag as a responder The system is known.

  For example, a wireless tag circuit element provided in a label-like wireless tag includes an IC circuit unit that stores predetermined wireless tag information and an antenna that is connected to the IC circuit unit and transmits and receives information. The IC circuit unit can be accessed (reading / writing information) from the reader / writer side even when the battery is dirty or placed at an invisible position, and product management, inspection processes, etc. Practical use is expected in various fields.

  When reading / writing the above information, the reader / writer transmits / receives a communication signal to / from a wireless tag to be communicated. This communication signal includes, for example, a preamble and identification information (ID number) of a wireless tag circuit element forming a data body. , Hereinafter referred to as tag identification information as appropriate). At this time, as the length (data length) of the tag identification information, it is known that there are a plurality of types of bits depending on the application and the standard. As a result, there are various lengths of the communication signal as a whole. It exists (for example, refer nonpatent literature 1).

Auto-ID Center, TECHNICAL REPORT “860 MHz-930 MHz Class I Radio Frequency Identification Tag Radio Frequency & Logical Year Information 11 Month V1. 1-17

  As described above, the wireless tag has been dramatically used in recent years and is being used in various fields. However, as described in the related art, tag identification information of various data lengths is dispersed with various wireless tags. It is currently used for.

  Therefore, when an inquiry is made from a reader / writer as an interrogator to a wireless tag as a responder and a response is received, the tag identification information is normally acquired if the data length corresponding to the wireless tag is known in advance. Although it is possible, if the data length is unknown, it is difficult to acquire tag identification information, and it is not possible to sufficiently cope with a plurality of types of data lengths.

  An object of the present invention is to provide a wireless tag information communication apparatus capable of reliably acquiring identification information regardless of the type of data length of a wireless tag circuit element to be communicated.

  To achieve the above object, according to a first aspect of the present invention, there is provided an access information generating means for generating access information for accessing a questionable RFID circuit element, and the access information generated by the access information generating means in a non-contact manner. Information transmitting means for transmitting to and accessing the RFID circuit element, and a response signal transmitted from the RFID circuit element in accordance with the transmitted access information after transmission of the access information by the information transmitting means Is received in a non-contact manner, the information receiving means for reading, and the error detection code is extracted from the response signal read by the information receiving means, and the read response signal is included in the read response signal based on the extracted error detection code And a data length specifying means for specifying the data length of the identification information of the RFID circuit element.

  In the first invention of this application, the information transmitting means transmits the access information generated by the access information generating means to the RFID tag circuit element to be interrogated, and when the response signal is transmitted, the information receiving means receives it. Read. Then, the data length specifying means extracts the error detection code included in the read response signal, and specifies the data length using this. In this way, by utilizing the property of the error detection code that corresponds to the identification information on a one-to-one basis, by specifying the data length from the RFID circuit element, a wide variety of data lengths from a plurality of types of RFID circuit elements The correct identification information can be surely obtained regardless of the tag type.

  According to a second invention, in the first invention, there is provided information identifying means for acquiring identification information of the RFID circuit element based on the data length specified by the data length specifying means.

  In the second invention of this application, the information transmitting means transmits the access information generated by the access information generating means to the RFID tag circuit element to be interrogated, and when the response signal is transmitted, the information receiving means receives it. Read. Then, the data length specifying unit and the information identifying unit extract the error detection code included in the read response signal, and use this to specify the data length and acquire the identification information of the RFID circuit element. In this way, by utilizing the property of the error detection code that corresponds to the identification information one-to-one, by specifying the data length from the RFID circuit element and detecting the identification information, the plurality of types of RFID circuit elements can be detected. It is possible to deal with response signals of various data lengths, and it is possible to reliably obtain correct identification information regardless of the tag type.

  According to a third invention, in the first or second invention, the data length specifying means reads the error detection code from the response signal read by the information receiving means and the information receiving means. The temporary identification information of the RFID circuit element is set based on the response signal, the calculation means for calculating the temporary error detection code based on the temporary identification information, the temporary error detection code calculated by the calculation means, and the extraction Determining means for determining whether or not the error detection code extracted by the means matches.

  In the third invention of the present application, the extraction means detects the error detection code from the response signal, while the calculation means sets temporary identification information from the response signal and calculates the temporary error detection code. Then, the determination unit determines whether or not the detected error detection code matches the calculated temporary error detection code. Thus, if the two match, the temporary identification information is equal to the actual identification information, and correct identification information is obtained and the data length is specified.

  In a fourth aspect based on the third aspect, the computing means includes temporary bit length setting means for setting a temporary bit length of identification information of the RFID circuit element based on the response signal read by the information receiving means. A temporary identification information setting means for setting the temporary identification information by associating the response signal read by the information receiving means with the temporary bit length set by the temporary bit length setting means, and the temporary information setting means. Provisional error detection code determination means for determining the temporary error detection code based on the set temporary identification information.

  In the fourth invention of this application, the provisional bit length setting means sets the provisional bit length of the identification information of the RFID circuit element based on the response signal, and the provisional identification information setting means fits the set provisional bit length to the response signal. Provisional identification information is set, and provisional error detection code determination means determines a provisional error detection code based on the set provisional identification information. In this way, the temporary error detection code can be calculated based on the response signal read by the information receiving means.

  In a fifth aspect based on the fourth aspect, the provisional bit length setting means determines that the provisional bit length setting means determines that the provisional error detection code and the error detection code do not coincide with each other a predetermined number of provisional times. The bit length is reset.

  The temporary bit length is reset by the temporary bit length setting means until the temporary error detection code matches the error detection code, and the setting of temporary identification information and the determination of the temporary error detection code are repeated each time. Both can be matched and correct identification information can be obtained.

  In a sixth aspect based on the fifth aspect, the extracting means includes a bit string obtaining means for obtaining a bit string of the response signal read by the information receiving means, and a predetermined number of the bit strings obtained by the bit string obtaining means. Error detecting code determining means using the error detecting code as the error detecting code.

  In the sixth invention of the present application, the bit string of the response signal is acquired by the bit string acquisition means, and a predetermined number of bits of the acquired bit string is set as the error detection code by the error detection code determination means. In this way, the error detection code can be extracted from the response signal read by the information receiving means.

  In a seventh aspect based on the sixth aspect, the temporary bit length setting means uses the error detection code determination means in the bit string of the response signal acquired by the bit string acquisition means as the initial temporary bit length. A bit number obtained by subtracting a predetermined number of bits of the determined error detection code or a number in the vicinity thereof is set.

  In the case of setting at random by starting the setting of the temporary bit length from the number of bits that would originally be provided or a number close to it, assuming that the read response signal would have been received relatively correctly In comparison, it is possible to increase the possibility that the temporary error detection code and the error detection code coincide with each other earlier, and to obtain correct identification information more quickly.

  In an eighth aspect based on any one of the fifth to seventh aspects, the temporary bit length setting means selects at least the first temporary bit length from a predetermined bit length list. It is characterized by setting.

  If it is known that the bit length of the identification information of the RFID tag circuit element used in the RFID tag communication system is limited to several types in advance or the possibility is high, the plurality of bits By listing the long types and using the temporary bit length setting means at least at the time of initial setting, the temporary error detection code and the error detection code can be matched earlier than when setting at random. The correct identification information can be obtained more quickly.

  In a ninth aspect based on any one of the fifth to eighth aspects, the temporary bit length setting means sets at least the initial temporary bit length to either 64 bits or 96 bits. Features.

  The bit length of the identification information of the RFID tag circuit element used in the RFID tag communication system is usually 64 bits or 96 bits in many cases. Therefore, in the ninth invention of the present application, the temporary bit length setting means sets the temporary bit length to any of them at the time of the initial setting, so that the temporary error detection code can be compared with the case where the setting is made randomly. And the error detection code can be matched more quickly, and correct identification information can be obtained more quickly.

  In a tenth aspect based on the eighth aspect, when the temporary bit length setting means determines that the temporary error detection code and the error detection code do not match by the determination means, the bit length list Another temporary bit length is selected and set.

  If it is known that the bit length of the identification information of the RFID tag circuit element used in the RFID tag communication system is limited to some types in advance, the plurality of bit length types are listed and provisional bits By making the length setting means select the provisional bit length from among them, the provisional error detection code and the error detection code can be matched quickly, and correct identification information can be obtained quickly.

  In an eleventh aspect based on any one of the fifth to ninth aspects, the temporary bit length setting means determines that the temporary error detection code and the error detection code do not match by the determination means. In each case, the provisional bit length is increased or decreased by one bit and a new provisional bit length is set each time.

  Until the temporary error detection code matches the error detection code, the temporary bit length setting means increases or decreases the temporary bit length by 1 bit and resets the temporary identification information and determines the temporary error detection code each time. By repeating the above, it is possible to finally match the two and obtain correct identification information.

  In a twelfth aspect according to any one of the fifth to eleventh aspects, even if the temporary bit length setting unit resets the predetermined number of times, the determination unit performs the temporary error detection code and the error. When it is determined that the detected code does not match, the information transmitting unit transmits the access information again, and the information receiving unit performs the reading again.

  If the temporary error detection code and the error detection code do not match even if the temporary bit length is reset by the temporary bit length setting means a predetermined number of times, the information receiving means reads again and sets the temporary identification information and the temporary error again. By deciding the detection code and repeating the same procedure, it is possible to finally match the two and obtain correct identification information.

  According to the present invention, the data length from the RFID circuit element is specified by utilizing the property of the error detection code that corresponds to the identification information on a one-to-one basis. Regardless, the identification information can be reliably acquired.

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

  FIG. 1 is a system configuration diagram showing an overall outline of an RFID tag communication system to which this embodiment is applied.

  In FIG. 1, the RFID tag communication system S includes an interrogator 100 according to the present embodiment and a RFID tag T as a responder corresponding thereto.

  The wireless tag T has a wireless tag circuit element To including an antenna 51 and an IC circuit unit 52 (details will be described later).

  The interrogator 100 accesses the antenna 1 that transmits and receives signals by wireless communication with the antenna 51 of the RFID circuit element To and the IC circuit section 52 of the RFID circuit element To through the antenna 1 ( A high-frequency circuit 2 for reading or writing), a signal processing circuit 3 for processing a signal read from the RFID circuit element To, and a control circuit 4.

  The control circuit 4 is a so-called microcomputer, and although not shown in detail, it is composed of a central processing unit such as a CPU, a ROM, and a RAM, and is stored in advance in the ROM while using a temporary storage function of the RAM. Signal processing is performed according to the program.

  FIG. 2 is a functional block diagram showing detailed functions of the high-frequency circuit 2. In FIG. 2, the high-frequency circuit 2 includes a transmitter 11 that transmits a signal to the RFID circuit element To via the antenna 1 and a reception that receives a reflected wave from the RFID circuit element To that is received by the antenna 1. It comprises a part 12 and a transmission / reception separator 13.

  The transmission unit 11 generates a carrier wave for accessing (reading or writing) RFID tag information of an IC circuit unit 52 (described later) of the RFID circuit element To, and a PLL (Phase Locked Loop) 22. , And the VCO (Voltage Controlled Oscillator) 23 and the generated carrier wave based on the signal supplied from the signal processing circuit 3 (in this example, amplitude modulation based on the “TX_ASK” signal from the signal processing circuit 3) ) A transmission multiplication circuit 24 (in the case of amplitude modulation, an amplification factor variable amplifier or the like may be used), and a modulated wave modulated by the transmission multiplication circuit 24 is amplified by a “TX_PWR” signal from the control circuit 4 And a variable transmission amplifier 25 for determining and amplifying the rate. The generated carrier wave preferably uses a frequency in the UHF band, and the output of the transmission amplifier 25 is transmitted to the antenna 1 via the transmission / reception separator 13 to be the IC circuit of the RFID circuit element To. Supplied to the unit 52.

  The receiving unit 12 is necessary from the reception first multiplication circuit 31 that multiplies the reflected wave from the RFID circuit element To received by the antenna 1 and the generated carrier wave, and the output of the reception first multiplication circuit 31. Received by the antenna 1, the first band-pass filter 32 for extracting only a signal in a wide band, the reception first amplifier 34 that amplifies the output of the first band-pass filter 32 and supplies the amplified signal to the first limiter 33. The reception second multiplication circuit 35 that multiplies the reflected wave from the RFID circuit element To and the carrier wave that is generated and shifted in phase by 90 °, and the output of the reception second multiplication circuit 35 has a necessary band. A second band pass filter 36 for extracting only the signal and an output of the second band pass filter 36 are inputted and amplified and supplied to the second limiter 37. And a reception second amplifier 38. The signal “RXS-I” output from the first limiter 33 and the signal “RXS-Q” output from the second limiter 37 are input to the signal processing circuit 3 and processed.

  The outputs of the reception first amplifier 34 and the reception second amplifier 38 are also input to an RSSI (Received Signal Strength Indicator) circuit 39, and a signal “RSSI” indicating the strength of these signals is input to the signal processing circuit 3. It has become so. Thus, in this embodiment, the reflected wave from the RFID circuit element To is demodulated by IQ orthogonal demodulation.

  FIG. 3 is a functional block diagram showing a functional configuration of the RFID circuit element To provided in the RFID tag T. In FIG. 3, the RFID circuit element To includes an antenna 51 that transmits and receives signals in a non-contact manner using an antenna 1 on the interrogator 100 side and a high frequency such as a UHF band, and the IC circuit connected to the antenna 51. Part 52.

  The IC circuit unit 52 includes a rectification unit 53 that rectifies the carrier wave received by the antenna 51, a power supply unit 54 that stores energy of the carrier wave rectified by the rectification unit 53 and serves as a drive power source, and the antenna 51. Connected to the antenna 51, a clock extraction unit 56 that extracts a clock signal from the received carrier wave and supplies it to a control unit 55 (described later), a memory unit 57 that functions as an information storage unit that can store a predetermined information signal The modulation / demodulation unit 58, and the control unit 55 for controlling the operation of the RFID circuit element To through the rectification unit 53, the clock extraction unit 56, the modulation / demodulation unit 58, and the like.

  The modem unit 58 demodulates the communication signal received from the antenna 51 of the interrogator 100 received by the antenna 51 and modulates and reflects the carrier wave received from the antenna 51 based on the response signal from the control unit 55. .

  The control unit 55 interprets the received signal demodulated by the modulation / demodulation unit 58, generates a return signal based on the information signal stored in the memory unit 57, and performs basic control such as control of returning by the modulation / demodulation unit 58. Execute proper control.

  In the basic configuration described above, an inquiry (inquiry) signal generated by the transmission unit 52 of the high-frequency circuit 2 of the interrogator 100 is transmitted via the antenna 1, and in response thereto, a response signal is transmitted from the antenna 51 of the RFID circuit element To. The data is transmitted (returned) and received by the antenna 1 of the interrogator 100, and information is read / written based on this.

In such wireless communication, various error controls are usually performed in order to mechanically detect an information communication error caused by noise such as a line surrounding environment. At this time, CRC (Cyclic Redundancy Check) is one of methods for detecting an error between the original data before communication and the data after communication (checking whether the data is broken). Widely used in such fields.
In CRC, a special calculation formula (generator polynomial) is applied to transmission data to create a bit string (error detection code) for error checking. When the transmission bit string P (x), the generator polynomial G (x), and the highest order of the generator polynomial are ⁿ , the remainder of P (x) · x ⁿ / G (x) is the CRC code. For example, the transmission bit is
“01100100” (P (x) = x ⁶ + x ⁵ + x ² )
And the generator polynomial is G (x) = x ⁶ + x ²
If
P (x) · x ⁶ / G (x) = x ⁶ + x ⁴ + x ³ + x ² + x remainder x ³
Therefore, the CRC code is “100000”.
The bit string calculated in this way is added to the transmission data as a CRC code for transmission. On the receiving side, a bit string is calculated by the same calculation formula and compared with the bit string added to the received data. For this CRC code, the same code is always generated from the same data, and if even one bit of data is different, another CRC code is generated. Therefore, by performing the above comparison, the transmitted data and the received data are correctly It is possible to detect whether they match (whether an error has occurred).

  The main part of this embodiment is the identification information (ID number) of the RFID circuit element To using the CRC code included in the response signal from the RFID circuit element To to the inquiry (inquiry) of the interrogator 100. Is to identify. The details will be described below with reference to FIGS.

  As described above, the length (data length) of the tag identification information of various wireless tags currently proposed includes a plurality of types of bits depending on applications and standards. 4A to 4C show the storage status of various types of information having different numbers of bits in the IC circuit section 52 of the RFID circuit element To including the error detection code (CRC code) as described above. FIG. This example is based on the Auto-IDClass I specification established by EPC global (a non-profit corporation established jointly by the International EAN Association, which is an international organization for distribution codes, and the United Code Code Council (UCC), which is an American distribution code organization). This is an example of compliance.

  As shown in the figure, each example stores information including a CRC code, tag identification information (ID), and a password. FIG. 4A shows an ID 64-bit tag, and FIG. A bit tag, FIG. 4C shows a case of an ID 128-bit tag. In both cases, the CRC code is 16 bits and the password is 8 bits.

  5A to 5F are diagrams illustrating examples of response signals of the RFID circuit element To to the interrogator 100. FIG. In this example, the communication signal is composed of a preamble, a CRC code (in this example, 16 bits), and identification information (ID number) of the RFID circuit element To forming the data body, and arranged in this order. .

  FIG. 5A shows a case where the tag identification information is a normal response signal from the 64-bit RFID tag T, and a 16-bit CRC code and subsequent 64-bit tag identification information are received. The total is 80 bits.

  FIG. 5B shows a case where the tag identification information is a normal response signal from a 96-bit wireless tag T, a 16-bit CRC code and 96-bit tag identification information are received, and the total number of received signals is 112. A bit.

  FIG. 5 (c) shows a response signal when the tag identification information is 64 bits in a wireless tag T of a type in which a 16-bit 0 code is added after the tag identification information, and a 16-bit CRC code, 64-bit tag identification information and 16-bit 0 code are received, and the total received signal is 96 bits.

  FIG. 5 (d) is a response signal from the RFID tag T (ID 64 bits) shown in FIG. 5 (a), in which 20-bit noise is mixed, and a 16-bit CRC code, 64-bit Tag identification information and 20-bit noise are received, and the total received signal is 100 bits.

  FIG. 5 (e) is a response signal from the RFID tag T (ID 64 bits) shown in FIG. 5 (c), in which 20-bit noise is mixed, and a 16-bit CRC code, 64-bit Tag identification information, 16-bit 0 code, and 20-bit noise are received, and the total received signal is 116 bits.

  FIG. 5 (f) shows a case where only a part of the response signal from the wireless tag T (ID 96 bits) shown in FIG. 5 (b) is received. A 16-bit CRC code and a 96-bit tag identification are shown. Of the information, 72 bits are received, and the total received signal is 88 bits.

  Note that the value of the CRC portion in FIG. 4 and FIG. 5 described above is a schematic value for ease of explanation, and is not calculated.

  As described above, from the RFID circuit element To in response to an inquiry (inquiry) from the interrogator 100 due to the data length of the tag identification information of the RFID tag T or the specification (type) by the tag manufacturer, further noise, partial reception, etc. The length of the response signal bit string varies. For this reason, it may be difficult to obtain accurate tag identification information because it is not known from which part to which part of the total length of the received signal the tag identification information (ID number). The present invention copes with such a case, and uses the CRC code to reliably identify the identification information (ID number) of the RFID circuit element To.

  FIG. 6 is a flowchart showing a control procedure executed by the control circuit 4.

  In FIG. 6, first, in step S10, a variable N for counting the number of retries (retry) when communication failure is suspected is initialized to zero.

  In step S 20, a “Scroll All ID” command for reading information stored in the RFID circuit element To is output to the signal processing circuit 3. Based on this, a “Scroll All ID” signal as access information is generated in the signal processing circuit 3 and transmitted to the RFID circuit element To via the transmission unit 11 of the high-frequency circuit 2 to prompt a reply.

  Next, in step S30, a response signal (= reply signal) transmitted from the RFID tag circuit element To to be accessed corresponding to the “Scroll All ID” signal is received via the antenna 1, and the high-frequency circuit 2 The data is captured via the receiving unit 12 and the signal processing circuit 3.

  Thereafter, the process proceeds to step S40, and the analog reception data captured in step S30 is converted into digital data (bit string). Then, in step S50, the bit length of the converted bit string is counted and acquired.

  In step S60, a predetermined length (16 bits in this example) of the bit length acquired in step S50 is set as a CRC code (= CRC0; error detection code). When step S60 ends, the process proceeds to step S70.

  Here, in this example, it is known in advance that the tag identification information is either 64 bits, 96 bits, or 128 bits as shown in FIGS. It is speculated that this is likely to be the case), and there are three “64 bits”, “96 bits”, and “128 bits” as the bit length list of the tag identification information in an appropriate location (for example, RAM) in the control device 3. Settings are retained. First, in step S70, it is assumed that the bit length “ID_length” of the tag identification information received in step S30 this time is the smallest 64 bits out of the three bits (provisional bit length).

  Corresponding to this, in step S80, from the 17th bit following the CRC code 16 bits in the bit sequence received in step S30 and digitally converted in step S40, the “ID_length” bits (in this example, 64 bits) Min) is assumed to be tag identification information (temporary identification information).

  Thereafter, in step S90, using the assumed identification information, a CRC code (= CRC1; tentative error detection code) is calculated as described above.

  Then, the process proceeds to step S100, and it is determined whether or not the CRC code (= CRC0) actually measured in step S60 described above matches the CRC code (= CRC1) obtained in step S90.

  If they match, the ID_length and tag identification information that is the basis of CRC1 are both correct due to the above-described CRC code characteristics. Therefore, in step S110, the temporary bit length ID_length is the value of the bit length of the correct tag identification information. In step S120, the temporary identification information is determined as correct identification information, and this flow is terminated.

  On the other hand, if CRC0 and CRC1 do not match in step S100, the determination is not satisfied, and the routine goes to step S129. In step S129, the length of the response bit string is checked to determine whether it is 112 bits (= 96 bits + 16 bits) or more. If it is 112 bits or more, the determination is satisfied, and the routine goes to Step S130. If it is less than 112 bits, the determination is not satisfied, and the routine goes to Step S210 described later (details will be described later).

  In step S130, it is assumed that the bit length “ID_length” of the tag identification information received in step S30 is 96 bits next to 64 bits out of the three listed numbers (provisional bit length). Reset).

  Correspondingly, in the next step S140, as in step S80, the "ID_length" bits (96 bits in this example) from the 17th bit following the CRC code 16 bits are the tag identification information. (Re-setting of temporary identification information).

  Thereafter, in step S150, the CRC code CRC1 is calculated again using the assumed identification information as in step S90.

  Then, the process proceeds to step S160, and it is determined whether or not the CRC code (= CRC0) actually measured in step S60 described above matches the new CRC code (= CRC1) calculated again in step S150.

  If they match, the temporary bit length ID_length and the temporary identification information are both determined as correct values in steps S110 and S120, and the flow ends.

  If CRC0 and CRC1 do not match again in step S160, the determination is not satisfied, and the routine goes to step S169. In step S169, the length of the response bit string is checked to determine whether it is 144 bits (= 128 bits + 16 bits) or more. If it is 144 bits or more, the determination is satisfied, and the routine goes to Step S170. If it is less than 144 bits, the determination is not satisfied, and the routine goes to Step S210 described later (details will be described later).

  In step S170, as in step S130, it is assumed that the bit length “ID_length” of the tag identification information is the remaining 128 bits out of the three listed numbers (temporary bit length is set again). .

  In the next step S180, it is assumed that the 128 bits from the 17th bit following the CRC code 16 bits are the tag identification information (re-setting of the temporary identification information) in the same manner as described above.

  Thereafter, in step S190, the CRC code CRC1 is calculated again using the assumed identification information as described above.

  Then, the process proceeds to step S200, and it is determined whether or not the CRC code CRC0 matches the new CRC code CRC1 calculated again in step S190.

  If they match, the temporary bit length ID_length and the temporary identification information are both determined as correct values in steps S110 and S120, and the flow ends.

  If CRC0 and CRC1 do not match again in step S160, the process proceeds to step S210.

  In step S210, 1 is added to the variable N described above, and it is further determined in step S220 whether N = 5. If N ≦ 4, the determination is not satisfied and the process returns to step S20, and the same procedure is repeated from the retransmission of the “Scroll All ID” signal. If N = 5, the process proceeds to step S230, and an error display signal is output, corresponding to a display means (not shown) provided in the interrogator 100 (or may be an external terminal or the like via the network connection from the interrogator 100). The reading failure (error) display is performed, and this flow is terminated. In this way, even if reading of the RFID tag information is unsuccessful, retry is performed up to five times.

  FIG. 7 is a diagram showing the gist of the identification information identification procedure described above in an easy-to-understand manner. As described above, the provisional bit length and provisional tag identification information are set from the bit string after extracting the CRC code, the provisional CRC code is calculated, matched, and repeated until they match.

  As described above, the signal processing circuit 3 constitutes access information generating means for generating access information for accessing the RFID tag circuit element to be interrogated, and the transmitter 11 and the antenna 1 of the high frequency circuit 2 are generated by the access information generating means. The information transmission means for transmitting and accessing the access information to the RFID circuit element in a non-contact manner is configured, and the receiver 1 of the antenna 1 and the high frequency circuit 2 transmits the access information after the access information is transmitted by the information transmission means. An information receiving means for receiving a response signal transmitted from the RFID circuit element according to the information in a non-contact manner and reading it is configured.

  Further, Step S40 to Step S100, Step S130 to Step S200, and Step S110 of the flow shown in FIG. 6 executed by the control circuit 4 extract the error detection code from the response signal read by the information receiving means, and this extraction is performed. Data length specifying means for specifying the data length of the identification information of the RFID circuit element included in the response signal read based on the error detection code is configured, and step S120 is based on the data length specified by the data length specifying means. Thus, information identification means for acquiring identification information of the RFID circuit element is configured.

  Of these, steps S40 to S60 constitute extraction means for extracting an error detection code from the response signal read by the information receiving means, and steps S70 to S90, steps S130 to S150, and steps S170 to S190 are included. Then, the temporary identification information of the RFID tag circuit element is set based on the response signal read by the information receiving means, and the calculation means is configured to calculate the temporary error detection code based on the temporary identification information. Step S100, Step S160, Step S200 However, it constitutes a determination means for determining whether or not the temporary error detection code calculated by the calculation means matches the error detection code extracted by the extraction means.

  Further, among the above, step S40 and step S50 constitute a bit string acquisition unit that acquires a bit string of the response signal read by the information reception unit, and step S60 includes a predetermined number of bits among the bit string acquired by the bit string acquisition unit. An error detection code determination unit is configured which uses the minutes as error detection codes.

  Steps S70, S130, and S170 constitute provisional bit length setting means for setting the provisional bit length of identification information of the RFID circuit element based on the response signal read by the information reception means, and steps S80, S140, Step S180 configures provisional identification information setting means for setting provisional identification information by associating the response signal read by the information receiving means with the provisional bit length set by the provisional bit length setting means. Steps S90, S150, Step S190 constitutes a temporary error detection code determining means for determining a temporary error detection code based on the temporary identification information set by the temporary information setting means.

  In the present embodiment configured as described above, the inquiry signal (“Scroll All ID” signal) generated by the signal processing circuit 3 of the interrogator 100 is an RFID tag circuit element to be interrogated via the transmitter 11 and the antenna 1. The response signal is transmitted to To and received and read by the antenna 1 and the receiving unit 12. Then, the control circuit 4 extracts an error detection code (CRC0) included in the read response signal in steps S40 to S60, and uses this to detect a temporary data length (ID_length) in steps S70, S130, and S170. Bit length) and provisional tag identification information (provisional ID) are defined in steps S80, S140, and S180, and a provisional error detection code (CRC1) is obtained in steps S90, S150, and S190. Then, the extracted CRC0 and the provisionally defined CRC1 are matched, and when they are equal, the provisional data length is specified as the correct data length. In this way, by specifying the data length from the RFID circuit element To and acquiring the tag identification information by using the property of the error detection code (CRC) that corresponds to the identification information (ID) one-to-one, It is possible to deal with response signals of various data lengths from various types of RFID circuit elements To, and correct identification information can be reliably obtained for unknown RFID tags T regardless of their types.

  Further, when the bit length of identification information of the RFID circuit element To used in the RFID tag communication system is limited to some types in advance, the plurality of bit length types are listed as in this embodiment. By selecting the temporary bit length ID_length from among them, there is an effect that the temporary error detection code CRC1 and the extracted error detection code CRC0 can be matched quickly and correct identification information can be obtained quickly.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the technical idea and spirit thereof. Hereinafter, such modifications will be described.

(1) When Calculation is Started as an Assumed Bit Length Close to the Bit Length of the Received Signal FIG. 8 is a flowchart showing a control procedure by the control circuit 4 in this modification, and corresponds to FIG.

  In the flow shown in FIG. 8, steps S10 to S60 are the same as those in FIG. 6, and after the inquiry signal is transmitted and the response signal is received, the bit length is counted and 16 bits are set as CRC0. Then, it moves to step S70A provided instead of step S70.

  Here, in the above embodiment, three of “64 bits”, “96 bits”, and “128 bits” are set as the list of tag identification information lengths (bit lengths), and there is no need to set a temporary bit length (ID_length). The condition is assumed to be 64 bits → 96 bits → 128 bits in ascending order of the number of bits in the list, and the verification is performed by CRC1. On the other hand, in this modification, the list of tag identification information lengths is not limited to the above three, and more types are set. In step S70A, the nearest bit value smaller than the number of bits obtained by subtracting 16 bits (corresponding to the number of bits corresponding to CRC) from the response signal bit length is picked up from the listed bit lengths (for example, the received signal). If the number of bits is 140 bits, it is 124 bits when subtracting 16 bits, so ID_length = 96 bits from the above list. If the number of bits of the received signal is 144 bits, it is 128 bits when subtracting 16 bits, so ID_length from the above list. = 128 bits). In step S80, the number of bits picked up is used, and the number of bits picked up from the 17th bit of the reply signal bit string is used as tag identification information. Similarly, CRC1 is calculated in step S90 and compared with CRC0 in step S100.

  If the determination is not satisfied in step S100, the process proceeds to step S130A provided in place of step S130, and the provisional identification information bit length ID_length is assumed to be the next smaller value than that set in step S70A (for example, as described above). (If the number of bits of the received signal is 140 bits and the initially assumed bit length ID_length = 96 bits, then ID_length = 128 bits).

  Thereafter, the process proceeds to newly provided step S240, and it is determined whether or not the ID_length temporarily set in step S130A exceeds the bit length itself of the response signal acquired in step S50. If ID_length exceeds the bit length of the acquired response signal, such an assumption itself does not make sense (the tag identification information data length cannot be longer than the received signal length), so this determination is satisfied. After step S210, transmission / reception is retried up to five times as described above.

  If ID_length is less than or equal to the bit length of the acquired response signal, the determination in step S240 is not satisfied, the process returns to step S80, and the same procedure is repeated with a new ID_length.

  In the above, steps S40 to S110, S130A, and S240 of the flow shown in FIG. 8 extract the error detection code from the response signal read by the information receiving means, and the response signal read based on the extracted error detection code The data length specifying means for specifying the data length of the identification information of the RFID circuit element included therein is configured, and the identification information of the RFID circuit element is determined based on the data length specified by the data length specifying means in step S120. Constitutes an information identification means for acquiring.

  Of these, Steps S70 to S90 and Step S130A are used for setting temporary identification information of the RFID circuit element based on the response signal read by the information receiving means and calculating a temporary error detection code based on the temporary identification information. Step S100 constitutes determination means for determining whether or not the temporary error detection code calculated by the calculation means matches the error detection code extracted by the extraction means.

  Further, Step S70A and Step S130A constitute provisional bit length setting means for setting the provisional bit length of the identification information of the RFID circuit element based on the response signal read by the information reception means, and Step S80 is the information reception means. Corresponding to the read response signal is the temporary bit length set by the temporary bit length setting means to constitute temporary identification information setting means for setting temporary identification information. Step S90 is the temporary identification information set by the temporary information setting means. The temporary error detection code determining means for determining the temporary error detection code based on the above is configured.

  According to this modified example, in step S70A, as the first temporary bit length ID_length, the number of bits obtained by subtracting the number of bits of CRC0 (= 16) from the bit string of the response signal acquired in step S50 (or the vicinity thereof) Number). That is, on the assumption that the read response signal has been received relatively correctly, the setting of the temporary bit length ID_length is started at a random number by starting the setting of the number of bits that would originally be provided or a number close thereto. Compared with the case where it carries out, there is an effect that the possibility that the CRC1 and the CRC coincide with each other quickly is increased and correct identification information can be obtained more quickly.

(2) When calculation is repeated while shifting the assumed bit length without using a list FIG. 9 is a flowchart showing a control procedure by the control circuit 4 in this modified example, and FIG. It is a figure corresponding to FIG. 8 of a modification.

  In the flow shown in FIG. 9, steps S10 to S60 are the same as those in FIG. 6, and after the inquiry signal transmission → response signal reception, the bit length is counted and 16 bits are set as CRC0. Then, it moves to step S70B provided instead of step S70.

  Here, in the above embodiment, three of “64 bits”, “96 bits”, and “128 bits” are set as the list of tag identification information lengths (bit lengths), and there is no need to set a temporary bit length (ID_length). The condition is assumed to be 64 bits → 96 bits → 128 bits in ascending order of the number of bits in the list, and the verification is performed by CRC1. On the other hand, in this modified example, the assumption is first made in step S70B as 64 bits. However, the list is not particularly prepared (not limited to this, depending on the range of the assumed RFID tag type, usage, etc.). The bit length initially assumed in step S70B may be 96 bits, 128 bits, or other number of bits).

  Similarly, in step S80, the temporary bit length (ID_length = 64 in this example) is used, and the number of bits from the 17th bit of the reply signal bit string is used as tag identification information, CRC1 is calculated in step S90, and step S100 is calculated. Compare with CRC0.

  If the determination is not satisfied in step S100, the process proceeds to step S130B newly provided in place of step S130 or step S130A, and the temporary identification information bit length ID_length is reset to a value that is one larger than the previous value. (As described above, the value to be increased can be set as appropriate, and may be set to 2 or more instead of 1. Alternatively, the value may be decreased by an appropriate value).

  Thereafter, the process proceeds to step S240 similar to the modified example of (1) above, and it is determined whether the set ID_length does not exceed the response signal bit length itself. If it exceeds, the process proceeds to step S210 and thereafter, as described above. Retry transmission and reception up to 5 times. If ID_length is less than or equal to the bit length of the acquired response signal, the process returns to step S80, and the same procedure is repeated with a new ID_length.

  In the above, Step S40 to Step S110, Step S250, and Step S240 of the flow shown in FIG. 9 executed by the control circuit 4 extract the error detection code from the response signal read by the information receiving means, and the extracted error detection The data length specifying means for specifying the data length of the identification information of the RFID circuit element included in the response signal read based on the code is configured, and step S120 is based on the data length specified by the data length specifying means, Information identification means for acquiring identification information of the RFID circuit element is configured.

  Steps S70B, S80, S90, and S250 are operations for setting temporary identification information of the RFID circuit element based on the response signal read by the information receiving means and calculating a temporary error detection code based on the temporary identification information. Step S100 constitutes determination means for determining whether or not the temporary error detection code calculated by the calculation means matches the error detection code extracted by the extraction means.

  Further, Step S70B and Step S250 constitute temporary bit length setting means for setting the temporary bit length of the identification information of the RFID tag circuit element based on the response signal read by the information receiving means, and Step S80 is the information receiving means. Corresponding to the read response signal is the temporary bit length set by the temporary bit length setting means to constitute temporary identification information setting means for setting temporary identification information. Step S90 is the temporary identification information set by the temporary information setting means. The temporary error detection code determining means for determining the temporary error detection code based on the above is configured.

  According to this modification, until the temporarily set CRC1 matches the extracted CRC0, the temporary bit length ID_length of the tag identification information is increased (or decreased) bit by bit in step S250, and is reset each time. By repeating the setting of temporary identification information in step S80 and the determination of CRC1 in step S90, the two can finally be matched to obtain correct identification information. As a result, the wireless tag T having tag identification information of all unexpected bit lengths can be handled.

  In this modification, the bit length list of the tag identification information set temporarily as shown in FIGS. 6 and 8 is not used, but the initial value setting of the initial bit length in step S70B is performed using a similar list. You may pick it up from the list only when you use it. At that time, a value closest to a value obtained by subtracting the number of bits corresponding to the number of CRC bits from the bit length of the return signal as in step S70A of FIG. 8 may be picked up. Alternatively, the list may not be used at all, and a value obtained by simply subtracting the number of CRC bits from the response signal bit length (or the number in the vicinity thereof) may be used as the initial value.

In the above embodiment and the modifications of (1) and (2), “Scroll”
The case of conforming to the Auto-IDClass I specification established by EPC global such as “All ID signal” has been described as an example. However, the present invention is not limited to this. Is possible. In this case, the same effect is obtained.

1 is a system configuration diagram illustrating an overall outline of a wireless tag communication system including an interrogator according to an embodiment of the present invention. It is a functional block diagram showing the detailed function of the high frequency circuit shown in FIG. FIG. 2 is a functional block diagram illustrating a functional configuration of a wireless tag circuit element provided in the wireless tag illustrated in FIG. 1. It is a figure showing the storage condition of the information containing an error detection code in the IC circuit part of a wireless tag circuit element. It is a figure showing the example of the response signal of the RFID circuit element to an interrogator. 2 is a flowchart showing a control procedure executed by the control circuit shown in FIG. 1. It is explanatory drawing which showed the principal point of the identification procedure of identification information. It is a flowchart showing the control procedure by a control circuit in the modification which starts calculation as assumption bit length close | similar to the bit length of a received signal. It is a flowchart showing the control procedure by a control circuit in the modification which repeats calculation, shifting an assumption bit length without using a list.

Explanation of symbols

1 Antenna (information transmitting means, information receiving means)
2 High-frequency circuit 3 Signal processing circuit (access information generating means)
4 Control circuit (data length identification means, information identification means, extraction means, operator
Stage, determination means, bit string acquisition means, error detection code determination means, temporary video
Length setting means, provisional identification information setting means, provisional error detection code determination means)
11 Transmitter (information transmission means)
12 Receiving part (information receiving means)
100 Interrogator S RFID tag communication system To RFID tag circuit element

Claims (12)

Access information generating means for generating access information for accessing the RFID tag circuit element to be interrogated;
The access information generated by the access information generating means is transmitted to the RFID circuit element in a non-contact manner, and information transmitting means for performing access;
After transmitting the access information by the information transmitting means, an information receiving means for receiving and reading a response signal transmitted from the RFID circuit element according to the transmitted access information in a contactless manner;
An error detection code is extracted from the response signal read by the information receiving means, and a data length that specifies the data length of the identification information of the RFID circuit element included in the read response signal based on the extracted error detection code And an interrogator for the RFID tag communication system. The interrogator of the RFID tag communication system according to claim 1,
An interrogator for an RFID tag communication system, comprising information identification means for acquiring identification information of the RFID circuit element based on the data length identified by the data length identification means. In the interrogator of the RFID tag communication system according to claim 1 or 2,
The data length specifying means includes
Extracting means for extracting the error detection code from the response signal read by the information receiving means;
Calculation means for setting temporary identification information of the RFID circuit element based on the response signal read by the information receiving means, and calculating a temporary error detection code based on the temporary identification information;
An interrogator for an RFID tag communication system, comprising: determination means for determining whether or not the temporary error detection code calculated by the calculation means matches the error detection code extracted by the extraction means. The interrogator of the RFID tag communication system according to claim 3,
The computing means is
Provisional bit length setting means for setting a provisional bit length of identification information of the RFID circuit element based on the response signal read by the information reception means;
A provisional identification information setting unit that sets the provisional identification information by associating the response bit read by the information reception unit with the provisional bit length set by the provisional bit length setting unit;
An interrogator for an RFID tag communication system, comprising: provisional error detection code determination means for determining the provisional error detection code based on the provisional identification information set by the provisional information setting means. The interrogator of the RFID tag communication system according to claim 4,
The tentative bit length setting means resets the tentative bit length a predetermined number of times when the determination means determines that the tentative error detection code and the error detection code do not match. Interrogator for RFID tag communication system. The interrogator of the RFID tag communication system according to claim 5,
The extraction means includes
Bit string acquisition means for acquiring a bit string of the response signal read by the information reception means;
An interrogator for an RFID tag communication system, comprising: an error detection code determination unit that uses a predetermined number of bits of the bit string acquired by the bit string acquisition unit as the error detection code. The interrogator of the RFID tag communication system according to claim 6,
The provisional bit length setting means sets a predetermined number of bits of the error detection code determined by the error detection code determination means out of the bit string of the response signal acquired by the bit string acquisition means as the initial provisional bit length. An interrogator for an RFID tag communication system, wherein the number of subtracted bits or the number in the vicinity thereof is set. The interrogator of the RFID tag communication system according to any one of claims 5 to 7,
The interrogator of the RFID tag communication system, wherein the temporary bit length setting means selects and sets at least the initial temporary bit length from a predetermined bit length list. The interrogator of the RFID tag communication system according to any one of claims 5 to 8,
The interrogator of the RFID tag communication system, wherein the temporary bit length setting means sets at least the initial temporary bit length to either 64 bits or 96 bits. The interrogator of the RFID tag communication system according to claim 8,
The temporary bit length setting means selects another temporary bit length from the bit length list when the determination means determines that the temporary error detection code does not match the error detection code. An interrogator for an RFID tag communication system, characterized in that setting is performed. The interrogator of the RFID tag communication system according to any one of claims 5 to 9,
When the determination unit determines that the temporary error detection code and the error detection code do not match, the temporary bit length setting unit increases or decreases the temporary bit length by one bit each time and newly determines the temporary error detection code and the error detection code. The interrogator of the RFID tag communication system, wherein the temporary bit length is set. The interrogator of the RFID tag communication system according to any one of claims 5 to 11,
Even if the temporary bit length setting means resets the predetermined number of times, if the determination means determines that the temporary error detection code and the error detection code do not match, the information transmission means again The interrogator of the RFID tag communication system, wherein the access information is transmitted, and the information receiving means performs the reading again.

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