JP2004220117A - Reader/writer of noncontact information medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost reader/writer of a noncontact information medium which is capable of coping with a plurality of communication methods in accordance with differences in communication method between types A and B specified in ISO14443 and differences in coding method, particularly between Manchester encoding and NRZL, etc. <P>SOLUTION: The operating clock frequency of a microcomputer 11 is the same as the frequency of a carrier wave which is received from a noncontact information medium such as an IC card 1. An output of a binarization circuit 17 is directly input to the microcomputer 11 so that coded information is decoded by the microcomputer 11 and so that the microcomputer 11 identifies the method of communication. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a reader / writer that transmits and receives information to and from a non-contact information medium such as a non-contact IC card, a non-contact data tag, and a so-called data carrier.
[0002]
[Prior art]
In recent years, non-contact IC cards have been put to practical use in fields such as telephone cards and commuter passes. The non-contact type IC card receives radio waves emitted from a so-called reader / writer and performs wireless communication by electromagnetic induction coupling. As a communication method between the non-contact type IC card and the reader / writer, there are a type A and a type B defined in ISO14443 or the like.
[0003]
Hereinafter, a conventional reader / writer will be described with reference to FIG. FIG. 3 is a diagram showing a circuit configuration of a conventional reader / writer and a circuit configuration of a data carrier. The reader / writer 10 has an antenna 14 and the data carrier 1 has an antenna 5, and wireless communication between the reader / writer 10 and the data carrier 1 is performed through these antennas by electromagnetic induction coupling means. The data carrier 1 includes an antenna 5, an IC chip 2 connected to both ends of the antenna 5, an analog switch 3 that is turned on / off by an analog switch control signal A output from the IC chip 2, and a modulation impedance element. 4.
[0004]
In the communication from the reader / writer 10 to the data carrier 1, a method of amplitude-modulating a 13.56 MHz carrier signal by a 106 kbps bit stream signal which is a command signal to the data carrier 1 is used. In the communication with the reader / writer 10, the ON / OFF control of the analog switch 3 is performed using the 848 kbps bit stream signal, which is the response signal to the reader / writer 10 output from the IC chip 2, as the analog switch control signal A. The terminal voltage of the antenna 14 of the reader / writer 10 is changed by inserting / non-inserting the modulation impedance element 4 into / from both ends of the antenna 5 and changing the impedance of the antenna 5 viewed from the antenna 14 of the reader / writer 10. Load modulation method It is.
[0005]
Since the half-duplex system is used for communication between the data carrier 1 and the reader / writer 10, the modulation period by the reader / writer 10 and the modulation period by the data carrier 1 do not overlap.
Next, the circuit operation of the reader / writer will be described.
In the communication from the data carrier 1 to the reader / writer 10, the reception signal B received by the antenna 14 and the tuning circuit 15 is input to the detection circuit 16, and the detection circuit 16 detects the input reception signal B, A detection signal C of 848 kbps is output, and the detection signal C is input to the binarization circuit 17 and converted into a digital demodulated signal D of 848 kbps.
[0006]
On the other hand, the carrier signal G output from the carrier oscillation circuit 21 having the 13.56 MHz oscillator 22 is frequency-divided by the frequency divider circuit 23 into a frequency of 1/16 to become a frequency-divided signal H of 848 kHz, and The peripheral signal H is a 848 kHz synchronous timing signal having a phase capable of synchronizing the digital demodulated signal D with the tuning circuit 18 while the delay time is controlled by the delay time control signal I outputted from the microcomputer 11 by the phase adjusting circuit 24. The digital demodulated signal D is converted into a synchronized digital demodulated signal E by the synchronizing circuit 18 in synchronization with an operation clock signal of the microcomputer 11 described later.
[0007]
The timing discriminating circuit 19 reads a data value from the input synchronized digital demodulation signal E at a timing synchronized with the synchronous timing signal J input at the same time, discriminates the data content, and determines the data content. And a start / stop timing of the effective data period, and outputs a valid data start / stop timing signal K which is a signal indicating the same timing. The serial-to-parallel conversion circuit 20 outputs a synchronized digital demodulated signal which is a serial data signal. E, and the synchronous demodulation signal E is controlled by the synchronous timing signal J and the valid data start / stop timing signal K, which are input at the same time, to convert the synchronous demodulation signal E into a parallel signal. Output.
[0008]
The parallel digital demodulated signal F is input to the microcomputer 11, and is read and processed by the microcomputer 11 at a timing synchronized with the valid data start / stop timing signal K input at the same time.
Next, in the communication from the reader / writer 10 to the data carrier 1, the microcomputer 11 inputs the 848 kHz frequency-divided signal H, and transmits a parallel digital signal which is a 106 kbps parallel signal synchronized with a transfer rate of 1/8 of this signal. The signal L is output. The parallel digital transmission signal L is input to the parallel-to-serial conversion circuit 25, and performs serial conversion of the parallel digital transmission signal L at a timing synchronized with the frequency-divided signal H that is input at the same time, and outputs a digital transmission signal M which is a 848 kbps serial signal. Is output.
[0009]
In the modulation circuit 26, the carrier signal G of 13.56 MHz is amplitude-modulated by the digital transmission signal M, and the transmission signal N is output. The transmission signal N is transmitted to the data carrier 1 by the tuning circuit 15 and the antenna 14.
On the other hand, the microcomputer 11 has a built-in oscillation circuit 12 for generating the operation clock signal, and the operation clock signal of the microcomputer 11 can be generated by connecting an oscillator 13 to the outside. The actual oscillation frequency of the oscillator 13 is 19.66 MHz, which is a value without a margin close to the maximum operation clock frequency of 20 MHz which is the operation limit of the microcomputer 11.
[0010]
As described above, the microcomputer 11 controls the delay time of the phase adjustment circuit 24. However, due to the limitation of the operation clock frequency, in addition to the delay time control, the above-described timing determination circuit 19, serial-to-parallel conversion circuit 20 and the operation of the serial-to-parallel conversion circuit 25 cannot be performed together by software processing inside the microcomputer 11, and as a result, these circuits are external circuits of the microcomputer 11 as shown in the figure.
[0011]
[Patent Document 1]
JP-A-2002-342725
[0012]
[Problems to be solved by the invention]
However, the circuit configuration of the above-mentioned conventional reader / writer has a large circuit scale, and when a reader / writer is actually produced, the circuit mounting space is large and the circuit cost is high. Further, in order to transfer data in phase between the microcomputer 11 operating with the operating clock signal of 19.66 MHz and the peripheral transmitting / receiving circuit of the antenna 14 operating with the carrier signal of 13.56 MHz, the configuration is as follows. However, there is a problem that a circuit which is complicated and requires high timing accuracy is required, and it becomes difficult to secure operation reliability with a low-cost circuit having a simple configuration.
[0013]
Further, as the non-contact type IC card becomes widespread recently, the number of people who possess a plurality of reader / writers at the same time increases. In such a case, it is convenient if a single reader / writer can communicate with a non-contact type IC card of a plurality of communication systems. However, in a conventional reader / writer, the difference between type A and type B, especially encoding There is a problem that it is necessary to develop a dedicated decoding ASIC (application-specific IC) at a high cost in accordance with the system (Manchester, NRZ, etc.).
[0014]
The present invention has been made in view of the above-described problems, and has been made in consideration of a low-cost non-contact type information medium capable of communicating with a plurality of coding-type non-contact type IC cards without developing an ASIC. The purpose is to provide a reader / writer.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, a reader / writer for a non-contact type information medium according to the present invention is a reader / writer for transmitting / receiving information to / from a non-contact type information medium, and transmits the information from the non-contact type information medium. Receiving means for receiving the obtained wireless signal, demodulated signal generating means for detecting and demodulating the wireless signal to generate a digital demodulated signal, and a microcomputer to which the digital demodulated signal generated by the demodulated signal generating means is input And an operation clock signal supply unit for supplying an operation clock signal to the microcomputer, wherein the frequency of the operation clock signal generated by the operation clock signal supply unit is equal to the frequency of a carrier of a radio signal received by the reception unit. The microcomputer receives the input of the digital demodulated signal generated by the demodulated signal generating means. Te is characterized in that it comprises a determining means for determining encoding method of a radio signal transmitted from the noncontact information medium.
[0016]
In this configuration, since the operating clock frequency of the microcomputer and the frequency of the carrier of the radio signal are the same, the digital demodulated signal input to the microcomputer and the operating clock signal of the microcomputer are synchronized, and The digital demodulated signal can be easily read. Therefore, it is possible to cope with a plurality of types of encoding systems without developing a different ASIC for each communication system.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(1) Configuration of Reader / Writer FIG. 1 is a diagram showing a circuit configuration of a reader / writer of the present invention and a circuit configuration of a data carrier. The reader / writer 30 has the antenna 14, and the data carrier 1 has the antenna 5, and the wireless communication between the reader / writer 30 and the data carrier 1 is performed by the electromagnetic induction coupling means through these antennas.
[0018]
The data carrier 1 is the same as the conventional one, and the communication conditions such as the communication power, frequency, and modulation method in the communication between the data carrier 1 and the reader / writer 30 are exactly the same as the conventional one. Hereinafter, the circuit operation of the reader / writer of the present invention will be described.
The circuit of the reader / writer 30 of the present invention is characterized in that the operation clock signal of the microcomputer 11 is also used as a carrier signal for transmission. In the communication from the data carrier 1 to the reader / writer 30, the reception signal B received by the antenna 14 and the tuning circuit 15 is input to the detection circuit 16, and the detection circuit 16 detects the input reception signal B, A detection signal C of 848 kbps is output, and the detection signal C is input to the binarization circuit 17 and converted into a digital demodulation signal D which is a digital signal of 848 kbps, and the digital demodulation signal D is directly input to the microcomputer 11. And processed.
[0019]
Since the communication from the data carrier 1 to the reader / writer 30 is performed by the load modulation method as described above, the digital demodulated signal D obtained from the received signal is synchronized with the carrier signal P. Since the circuit uses the operation clock signal of the microcomputer 11 for the carrier signal P, the digital demodulation signal D is already synchronized with the operation clock signal of the microcomputer 11. Therefore, even if the digital demodulated signal D is directly input to the microcomputer 11, the data content of the digital demodulated signal D can be read by the microcomputer 11.
[0020]
Actually, the microcomputer 11 reads the data content of the digital demodulated signal D while being controlled by software. The read signal is a serial data signal, which is parallelized by software processing of the microcomputer 11.
Next, in the communication from the reader / writer 30 to the data carrier 1, the carrier signal of the transmission signal is similarly used as the operation clock signal of the microcomputer 11, so that the transmission signal is already synchronized with the operation clock signal of the microcomputer 11. The digital transmission signal M, which is a serial data signal, is generated under the direct control of the microcomputer 11 by software.
[0021]
The microcomputer 11 generates the 848 kbps digital transmission signal M while performing necessary serial conversion by software control. The modulation circuit 26 easily obtains the transmission signal N by modulating the carrier signal P, which is the operation clock signal of the microcomputer 11, with the digital transmission signal M directly output from the microcomputer 11, and tunes the transmission signal N. Communication from the reader / writer 30 to the data carrier 1 is performed by transmitting data to the data carrier 1 by the circuit 15 and the antenna 14.
[0022]
(2) Processing contents of microcomputer The microcomputer 11 reads data included in the digital demodulated signal D from the input digital demodulated signal D. Hereinafter, processing contents of the microcomputer 11 of the present embodiment will be described. FIG. 2 is a flowchart showing an outline of the processing contents. When the microcomputer 11 of the reader / writer 30 starts the operation of the program stored in the program memory (not shown), it first transmits a request signal to the outside via the antenna 14 (S101). When transmitting the request signal, the request signal corresponding to the communication method (here, first, type A) is converted into a 848 kbps digital signal by software processing inside the microcomputer 11 and output as a serial digital signal M. The digital signal M is input to the modulation circuit 26 together with the 13.56 MHz carrier wave signal P which is the operation clock signal of the microcomputer 11, and the carrier signal P is modulated to obtain the transmission signal N. The transmission signal N is transmitted to the data carrier 1 by the tuning circuit 15 and the antenna 14. The transmission method is the same in other cases.
[0023]
The request signal is a signal transmitted to confirm a non-contact type information medium such as the data carrier 1 existing in the communicable area of the reader / writer 30. In the present embodiment, it is assumed that a plurality of types of communication systems (type A and type B specified in ISO14443) between the reader / writer 30 and various non-contact information media such as the data carrier 1 are supported. Since it is possible, and the request signal is different for each communication method, as described above, first, the type A request signal is transmitted first.
[0024]
The non-contact information medium such as the data carrier 1 receiving the request signal returns a response signal. By receiving the response signal, the reader / writer 30 can confirm that the non-contact information medium exists in the communicable area. Here, the reader / writer 30 first transmits a type A request signal. When the reader / writer 30 receives the response signal (S102: YES), the reader / writer 30 determines whether or not it is a response signal to the type A request signal (S103). (S103: YES) Since there is a type A non-contact type information medium, the communication method of the microcomputer 11 is set so as to be in the type A communication mode (S104), and the communication is continuously executed. (S105). When the response signal is a type B response signal (S103: NO), the communication method of the microcomputer 11 is set to type B (S106).
[0025]
Here, the communication method will be briefly described. In the case of communication from a reader / writer to a non-contact type information medium in the case of type A (for example, a telephone card) specified in ISO14443, the modulation method is ASK modulation (amplitude modulation) with a modulation factor of 100%. The system is a modified mirror system, the frequency of the carrier is 13.56 MHz, and the communication speed is 106 kbps. On the other hand, the communication from the non-contact type information medium to the reader / writer uses OOK by the load modulation described above, the encoding method is the Manchester method, the carrier frequency is 13.56 MHz, the subcarrier frequency is 848 kHz, and the communication speed is Is 106 kbps.
[0026]
In communication from a type B (for example, a public card) reader / writer to a non-contact type information medium, the modulation scheme is ASK modulation with a modulation factor of 10%, the encoding scheme is NRZL, and the carrier frequency is 13.56 MHz. The communication speed is 106 kbps. On the other hand, in the communication from the non-contact type information medium to the reader / writer, BPSK modulation using a subcarrier of 848 kHz is used, the encoding method is NRZ, the frequency of the carrier is 13.56 MHz, and the communication speed is 106 kbps.
[0027]
The reader / writer according to the present embodiment is compatible with the above-described type A and type B, and is therefore an encoding method for communication from a non-contact type information medium such as a data carrier to the reader / writer. There is a problem in decoding typed data, and in type B, decoding data encoded by the BPSK method. The frequency of the carrier used for communication from the non-contact type information medium to the reader / writer is 13.56 MHz for both type A and type B, which is the same as the operating clock frequency of the microcomputer 11. Further, the frequency of the sub-carrier is the same at 848 kHz, and the operation clock signal of the microcomputer 11 and the carrier signal are the same. Therefore, the sub-carrier is binary at a predetermined rising or falling timing of the operation clock signal of the microcomputer 11. By sampling the digital demodulated signal D output from the digitizing circuit 17, the logic (0 or 1) of the digital demodulated signal from the binarizing circuit 17 input to the input port of the microcomputer 11 can be read as it is. it can.
[0028]
If it is determined that the encoding scheme of the received wireless signal is the Manchester scheme, then if the data array of the encoded digital demodulated signal is “000011111”, it is determined to be “1”, The setting in the microcomputer 11 is changed so that if it is “11110000”, it is determined to be “0”. When it is determined that the NRZL system is used, thereafter, when the data array of the encoded digital demodulated signal is “11111111”, it is determined to be “1”, and when the data array is “00000000”, “ The setting in the microcomputer 11 is changed so as to determine “0”.
[0029]
As described above, if the response signal is a type A response (S103: YES), the decoding method in the microcomputer 11 is switched to the type A (Manchester method) (S104). On the other hand, if the response signal is not a type A signal (S103: NO), the decoding method is switched to type B (NRZL method) (S106). Until the communication is completed (S107: YES), the communication is continuously performed (S105). When the communication is completed, the request signal to be transmitted to the non-contact type information medium is switched from type A to type B (S108). Then, the process returns to step S101.
[0030]
As described above, according to the present invention, first, in the reader / writer circuit of the present invention, all the clock frequencies for circuit operation are unified to 13.56 MHz, that is, the reader / writer circuit of the present invention shown in FIG. In the writer circuit, since the operation clock signal of the microcomputer 11 is used as the carrier signal P, the digital demodulation signal D is already synchronized with the operation clock signal of the microcomputer 11. For this reason, a carrier oscillation circuit 21, which generates a 13.56 MHz carrier signal G, an oscillator 22, a frequency dividing circuit 23, and a digital demodulation signal D, which are included in the conventional reader / writer circuit shown in FIG. A phase adjusting circuit 24 for synchronizing with a 13.56 MHz carrier signal G, a synchronizing circuit 18, and synchronizing the synchronized synchronized digital signal E with a 19.66 MHz operating clock signal of the microcomputer 11; The timing discriminating circuit 19 for performing the timing discrimination necessary for the conversion is not required, and the circuit is simplified.
[0031]
That is, the reader / writer of the present invention can reduce the circuit scale as compared with the conventional reader / writer, and can reduce the circuit size and the circuit cost.
Secondly, similarly, since the clock frequency for circuit operation is unified to 13.56 MHz, the carrier frequency signal of 13.56 MHz and the operating clock signal of the microcomputer of 19.66 MHz are different from each other as in a conventional reader / writer. A complicated circuit operation of synchronizing and transmitting a transmission data signal and a reception data signal between signals is not necessary, and the circuit operation and the circuit configuration are simplified.
[0032]
The simplification of the circuit operation further reduces the required data processing amount of the microcomputer 11 as compared with a conventional reader / writer circuit. The operation clock frequency of the microcomputer 11 is reduced from 19.66 MHz in the conventional reader / writer to 13.56 MHz in the reader / writer of the present invention.
As a result, the serial-to-parallel conversion processing of the received data and the parallel-to-serial conversion processing of the transmission data, which were conventionally performed by the external circuit of the microcomputer 11 in the reader / writer, can be performed by the microcomputer 11 in the reader / writer of the present invention. It is possible to control and perform it.
[0033]
Further, in the reader / writer circuit of the present invention, by unifying the above-mentioned circuit operation clock signal, the microcomputer 11 can directly read a digital signal obtained by demodulating the received signal without time axis conversion, and can read the digital signal transmitted from the microcomputer 11. It is possible to output a signal and to transmit the signal from the antenna 14 without performing time axis conversion of the signal.
[0034]
Therefore, the reader / writer circuit of the present invention eliminates the need for the serial-to-parallel conversion circuit 20 and the parallel-to-serial conversion circuit 25 of the conventional reader / writer circuit, and further reduces the circuit space and the circuit cost. It is possible to push forward.
According to the above series of contents, the reader / writer of the present invention has a simpler configuration and a smaller size and lower cost as compared with the conventional reader / writer circuit, and has the same operational reliability as the conventional reader / writer circuit. It is possible to secure.
[0035]
The program for realizing the processing of the reader / writer of the present invention is, for example, a magnetic disk such as a magnetic tape or a flexible disk, an optical recording medium such as a DVD, a CD-ROM, a CD-R, an MO, or a PD, or Smart Media (registered trademark). ), A computer-readable recording medium such as a flash memory recording medium such as COMPACTFLASH (registered trademark), and may be produced or transferred in the form of the recording medium. In the form of a program, the program may be transmitted and supplied via various wired or wireless networks including the Internet, broadcasting, telecommunication lines, satellite communication, and the like.
[0036]
Further, the program according to the present invention does not need to include all modules for causing a computer to execute the above-described processing. For example, information such as a communication program and a program included in an operating system (OS) may be separately stored. Each processing of the present invention may be executed by a computer using various general-purpose programs that can be installed in the processing device. Therefore, it is not always necessary to record all the modules on the recording medium of the present invention, and it is not necessary to transmit all the modules. Further, in some cases, the predetermined processing can be executed by using dedicated hardware.
[0037]
【The invention's effect】
As described above, according to the reader / writer of the non-contact information medium according to the present invention, the operation clock frequency of the microcomputer is set to be the same as the frequency of the carrier of the radio signal transmitted by the non-contact information medium, Receiving a digital demodulated signal obtained by demodulating a wireless signal, and determining a coding method of a wireless signal transmitted from the non-contact type information medium; There is no need to develop a high-cost ASIC in response to the different coding schemes for each, and there is an effect that it is possible to support a plurality of types of coding schemes at low cost. Further, since the operation clock signal of the microcomputer and the carrier signal are synchronized, there is an effect that the digital demodulated signal can be easily read by the microcomputer.
[Brief description of the drawings]
FIG. 1 is a diagram showing a circuit configuration of a reader / writer and a circuit configuration of a data carrier according to an embodiment of the present invention.
FIG. 2 is a flowchart showing an outline of processing contents of a microcomputer 11 of the present embodiment.
FIG. 3 is a diagram showing a circuit configuration of a conventional reader / writer and a circuit configuration of a data carrier.
[Explanation of symbols]
11 Microcomputer 12 Operating clock oscillation circuit 17 Binarization circuit 30 Reader / writer

Claims (1)

A reader / writer that transmits and receives information to and from a non-contact information medium,
Receiving means for receiving a wireless signal transmitted from the non-contact information medium,
Demodulation signal generation means for detecting and demodulating the radio signal to generate a digital demodulation signal,
A microcomputer to which a digital demodulated signal generated by the demodulated signal generating means is input;
Operating clock signal supply means for supplying an operation clock signal to the microcomputer,
The frequency of the operation clock signal generated by the operation clock signal supply unit is the same as the frequency of the carrier of the radio signal received by the reception unit,
The microcomputer further includes a determination unit that receives an input of the digital demodulation signal generated by the demodulation signal generation unit and determines an encoding method of a wireless signal transmitted from the non-contact type information medium. Reader writer to do.

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