JP2004200982A - Reader/writer for non-contact ic card - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To communicate with either of two kinds of IC cards having different ASK modulation system. <P>SOLUTION: A coding/decoding circuit 14 and a coding circuit 15 are operated with a common clock, and execute encoding of a TYPE-A and a TYPE-B of the ISO 14443, respectively. A signal synthesizing circuit 20 generates a synthesized signal Sd as an AND between a carrier signal Sc from the coding circuit 15 and an output signal SA from the coding/decoding circuit 14. An output signal SB from the coding circuit 15 and the synthesized signal Sd are input into a modulation circuit 21 for modulating in the TYPE-B system. In the case of the TYPE-A system, the output signal SA becomes a base band signal Sb(A), and the output signal SB becomes a high level signal. In the case of the TYPE-B system, the output signal SA becomes the high level signal, and the output signal SB becomes a base band signal Sb(B). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a non-contact IC card reader / writer capable of communicating with an IC card by different communication methods.
[0002]
[Prior art]
As a non-contact type response unit that transmits and receives information by transmitting and receiving electromagnetic waves, for example, there is one described in Patent Document 1. This is used, for example, by attaching it to a mobile device or the like in an automatic production line. On the other hand, in recent years, IC cards have been used in many systems such as entrance management systems for business establishments and automatic ticket gates, and accordingly, non-contact information for reading and writing information on the IC cards has been used. An IC card reader / writer is used.
[0003]
[Patent Document 1]
JP-A-10-13295
[Problems to be solved by the invention]
ISO standards are established for non-contact IC cards according to the communication distance and communication frequency, and there are types such as a close contact type (ISO10536), a close proximity type (ISO14443), and a close proximity type (ISO15693). Among them, the proximity type non-contact IC card includes TYPE-A and TYPE-B depending on the data modulation method. Each of TYPE-A and TYPE-B employs an ASK modulation method for transmission from a reader / writer to an IC card.
[0005]
The TYPE-A method is a method generally used for a non-contact IC card having a control circuit constituted by hardware logic without a built-in CPU, and is used for an IC card having a simple protocol. It is often used for cards and prepaid cards. On the other hand, the TYPE-B method is a method used for a non-contact IC card having a built-in CPU, and is often used for a cash card or a credit card for a bank having a relatively complicated protocol.
[0006]
FIG. 6 is a block diagram showing an electrical configuration of a modulation / demodulation circuit portion in an existing reader / writer 1 that adopts the TYPE-B method of ISO14443. The encoding circuit 2 in the form of an IC generates a baseband signal Sb (B) obtained by converting the transmission data sent from the CPU 3 into an NRZ code, receives a 13.56 MHz clock from the oscillation circuit 4, and generates a carrier. The signal is output to the modulation circuit 5 together with the signal Sc. The modulation circuit 5 employs, for example, a single-tuned transmission method, and transmits a signal modulated by the 10% ASK modulation method to the IC card 7 via the antenna 6. On the other hand, the demodulation circuit 8 demodulates a signal received via the antenna 6, and the demodulated signal is input to the encoding circuit 2 via the decoding circuit 9. FIG. 7 shows waveforms of the carrier signal Sc, the baseband signal Sb (B), and the antenna output signal Sw in this configuration.
[0007]
By the way, in recent years, with the spread of non-contact IC cards, a combination card integrating IC cards of various specifications has been proposed. At present, there is an increasing need for a combination card that shares a memory or the like and uses a communication interface between a non-contact proximity type and an external terminal type. On the other hand, a combination card of the TYPE-A type and the TYPE-B type is used. Is also considered. Preparing a reader / writer dedicated to each modulation method for an IC card integrating both types is troublesome and disadvantageous in terms of cost. Therefore, it is necessary to realize a reader / writer that can communicate with any of the TYPE-A and TYPE-B modulation methods.
[0008]
For example, when the TYPE-A method is added to the reader / writer 1 shown in FIG. 6 which adopts the TYPE-B method, an existing TYPE-A coding / decoding IC is combined to reduce the development period and the development cost. It is possible. However, existing encoding / decoding ICs are not designed on the assumption that they are combined with other ICs, and cannot be combined as they are.
[0009]
That is, the modulation circuit 5 of the reader / writer 1 uses a single-tuned transmission system, while the other encoding / decoding ICs that use the TYPE-A system use a double-tuned transmission system.
Due to this difference in transmission schemes, it is necessary to mount two types of antennas on a reader / writer simply by combining the two, which causes problems such as an increase in the size of the device and an increase in cost.
[0010]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a reader / writer for a contactless IC card that can communicate with any of two different ASK modulation methods and can be configured using an existing circuit. To provide.
[0011]
[Means for Solving the Problems]
According to the first aspect, the carrier signal output circuit keeps outputting the carrier signal regardless of the state of the modulation selection signal. When the modulation selection signal is in the first state, the first conversion circuit outputs a first baseband signal obtained by encoding transmission data according to a first ASK modulation scheme, and the second conversion circuit outputs Outputs a constant level signal. At this time, since the signal combining circuit combines the carrier signal and the first baseband signal, the amplitude of the carrier signal varies in multiple stages (for example, 0% / 0%) according to the first baseband signal which is a binary signal. 100%). That is, at this point, the modulation by the first modulation method has been performed.
[0012]
As a result, the constant level signal is input to the baseband signal input terminal of the modulation circuit, and the composite signal is input to the carrier signal input terminal of the modulation circuit. Since the input baseband signal is at a constant level, the modulation circuit outputs the synthesized signal modulated by the first modulation method as it is as a modulated signal.
[0013]
On the other hand, when the modulation selection signal is in the second state, the first conversion circuit outputs a constant level signal, and the second conversion circuit converts the transmission data according to the second ASK modulation method. And outputting a second baseband signal. At this time, the signal combining circuit outputs the carrier signal as it is in order to combine the carrier signal and the constant level signal. Thus, the second baseband signal is input to the baseband signal input terminal of the modulation circuit, and the carrier signal is input to the carrier signal input terminal of the modulation circuit. The modulation circuit outputs a modulated signal according to the second modulation scheme according to the original ASK modulation operation.
[0014]
Therefore, according to the reader / writer for a non-contact IC card, it is possible to communicate with any of two different ASK modulation methods by switching the state of the modulation selection signal, despite having a single modulation circuit. It becomes. As a result, information can be read from and written to a plurality of types of IC cards. The first and second conversion circuits do not need to be specially designed to cooperate with each other, and existing encoding / decoding circuits can be used.
[0015]
According to the second aspect of the present invention, since the signal synthesizing circuit includes an AND circuit, the synthesized signal becomes equal to the carrier signal when the first baseband signal is at a high level, and the first baseband signal is equal to the carrier signal. When the band signal is at a low level, the low level is constant. That is, the combined signal is a signal that has been subjected to 100% ASK modulation by the first baseband signal.
[0016]
According to the means described in claim 3, the received signal received by the single antenna is distributed, and the distributed received signal is used in combination with the first conversion circuit and the first demodulation circuit. Since the data is input to the second demodulation circuit used in combination with the second conversion circuit, bidirectional communication between the IC card and the non-contact IC card reader / writer becomes possible. The communication system from the IC card to the contactless IC card reader / writer is, for example, a load modulation system.
[0017]
According to the means described in claim 4, the first conversion circuit and the first demodulation circuit, and the carrier signal output circuit and the second conversion circuit are each configured as one IC. This form is one of the forms of the communication IC currently used. The present invention makes it possible to use such an existing IC to communicate with an IC card by any of the two types of modulation schemes, thereby saving the labor and cost of newly developing a new IC. .
[0018]
According to the means described in claim 5, the first and second conversion circuits operate based on a common clock, so that the carrier signal is easily synchronized with the first and second baseband signals. be able to.
[0019]
According to the means described in claim 6, since the first modulation method is a 100% ASK modulation method and the second modulation method is a 10% ASK modulation method, the proximity type non-contact IC established by ISO14443. Applicable to communication with cards.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a block diagram showing an electrical configuration of a modulation / demodulation circuit portion in an IC card reader / writer. The IC card reader / writer 11 (hereinafter simply referred to as the reader / writer 11) communicates with the proximity type non-contact IC cards 12A and 12B defined by the standard of ISO14443. ISO14443 defines communication systems of TYPE-A (corresponding to the IC card 12A) and TYPE-B (corresponding to the IC card 12B), and the reader / writer 11 can communicate using either of the two methods. It is characterized by points.
[0021]
When an IC card is transmitted from the reader / writer 11, the TYPE-A method uses 100% ASK (100% ASK (100% ASK) representing data "0" and "1" by a combination of 0% and 100% amplitude of a carrier signal (fc = 13.56 MHz). Amplitude Shift Keying) modulation method is adopted. On the other hand, the TYPE-B system employs a 10% ASK modulation system in which the amplitude of a carrier signal (fc = 13.56 MHz) represents data "0" and "1" by a combination of 90% and 100%.
[0022]
Also, when transmitting from the IC cards 12A and 12B to the reader / writer 11, the IC cards 12A and 12B convert the carrier signal (carrier) into the subcarrier frequency (fc / fc) in both the TYPE-A system and the TYPE-B system. By performing load modulation at 16 = 847 kHz), the signal is transmitted to the reader / writer 11 via the gap of the magnetic coupling.
[0023]
An upper device (not shown) such as a personal computer is connected to the reader / writer 11, and the CPU 13 outputs a modulation selection signal Sm according to a card selection signal sent from the upper device. I have. The reader / writer 11 communicates with the TYPE-A IC card 12A when the modulation selection signal Sm is at a high level, and communicates with the TYPE-B IC card 12B when the modulation selection signal Sm is at a low level. It has become.
[0024]
The encoding / decoding circuit 14 (corresponding to a first conversion circuit and a first demodulation circuit) performs encoding / decoding between transmission / reception data of the CPU 13 and the baseband signal Sb (A) based on the TYPE-A method. It performs decoding and demodulation, and is configured as one IC. When the modulation selection signal Sm is at a high level, for transmission to the IC card 12A, the transmission data from the CPU 13 is converted into a baseband signal Sb (A) by a modified mirror encoding method and output, and the data is transmitted from the IC card 12A. For reception, the reception signal is demodulated by the OOK-Manchester encoding method after demodulating the reception signal from the antenna 16. On the other hand, when the modulation selection signal Sm is at a low level, a constant high-level signal is output instead of the baseband signal Sb (A).
[0025]
On the other hand, the encoding circuit 15 (corresponding to a second conversion circuit) performs encoding between the transmission data of the CPU 13 and the baseband signal Sb (B) based on the TYPE-B method. It is configured as one IC. When the modulation selection signal Sm is at the low level, for transmission to the IC card 12B, the transmission data from the CPU 13 is converted into a baseband signal Sb (B) by the NRZ encoding method and output, and the modulation selection signal Sm is at the high level. In this case, a constant high-level signal is output in place of the baseband signal Sb (B).
[0026]
As for reception from the IC card 12B, a demodulation circuit 17 (corresponding to a second demodulation circuit) for decoding a reception signal from the antenna 16 and a decoding for decoding reception data by the BPSK-NRZ encoding method. This is performed by the circuit 18. The received data is sent to the CPU 13 via the encoding circuit 15.
[0027]
Each of the ICs constituting the encoding / decoding circuit 14 and the encoding circuit 15 is an existing IC. Therefore, the actual modulation selection signal Sm is realized by making the operation permission signal sent from the CPU 13 to each IC a complementary signal. That is, the state in which the CPU 13 outputs the operation permission signal only to the encoding / decoding circuit 14 corresponds to the first state (the high-level state) of the modulation selection signal for selecting the TYPE-A system. The state in which the CPU 13 outputs the operation permission signal only to the encoding circuit 15 corresponds to the second state (the low level state) of the modulation selection signal for selecting the TYPE-B method.
[0028]
A common clock is input from the oscillation circuit 19 to each of the ICs constituting the encoding / decoding circuit 14 and the encoding circuit 15, and the encoding circuit 15 functioning as a carrier signal output circuit is A carrier signal Sc of fc (= 13.56 MHz) is output. As a result, the baseband signals Sb (A) and Sb (B) are synchronized with the carrier signal Sc.
[0029]
The signal combining circuit 20 is specifically composed of an AND circuit, and outputs a combined signal Sd which is a logical product of the carrier signal Sc from the encoding circuit 15 and the output signal SA of the encoding / decoding circuit 14. It is supposed to.
[0030]
The modulation circuit 21 is a circuit that has a single carrier signal input terminal and a baseband signal input terminal and performs TYPE-B modulation. An output signal SB of the encoding circuit 15 (that is, a baseband signal Sb (B) or a constant level signal) is input to a baseband signal input terminal, and a synthesized signal Sd from the signal synthesis circuit 20 is input to a carrier signal input terminal. Is to be entered. The output terminal of the modulation circuit 21 is connected to the antenna 16. The signal received via the antenna 16 is distributed to two systems, one of which is directly input to the encoding / decoding circuit 14 and the other is input to the demodulation circuit 17. The antenna 16 and the antennas of the IC cards 12A and 12B are coupled by electromagnetic induction.
[0031]
Next, the operation of the present embodiment will be described with reference to FIGS.
FIG. 2 shows signal waveforms of each unit when transmitting from the reader / writer 11 to the TYPE-A IC card 12A, and FIG. 3 shows each unit when transmitting from the reader / writer 11 to the TYPE-B IC card 12B. 3 shows a signal waveform of the first embodiment. Each waveform is as follows.
[0032]
(A) Carrier signal Sc output from encoding circuit 15
(B) Output signal SA of encoding / decoding circuit 14
(C) Output signal SB of encoding circuit 15
(D) Synthesized signal Sd output from signal synthesizing circuit 20
(E) Output signal Sw of antenna 16
[0033]
In the case shown in FIG. 2, the modulation selection signal Sm is at a high level. Therefore, the encoding / decoding circuit 14 converts the transmission data into a baseband signal Sb (A) by the modified Miller encoding method and outputs it as an output signal SA. The constant level signal is output as the output signal SB. The signal synthesizing circuit 20 calculates the amplitude of 0% and the baseband signal Sb (A) of the carrier signal Sc when the baseband signal Sb (A) is at a low level by the logical product of the carrier signal Sc and the baseband signal Sb (A). A composite signal Sd having an amplitude of 100% at the high level is output. The synthesized signal Sd is a signal obtained by subjecting the carrier signal Sc to 100% ASK modulation with the baseband signal Sb (A).
[0034]
Since the modulation circuit 21 that performs TYPE-B type modulation outputs the signal at the carrier signal input terminal with 100% amplitude when the signal at the baseband signal input terminal is at a high level, the output signal SB has a high level constant level. In this case, which is a signal, the combined signal Sd is output as it is. As a result, the antenna 16 outputs an output signal Sw that is 100% ASK-modulated according to the TYPE-A method.
[0035]
On the other hand, in the case shown in FIG. 3, the modulation selection signal Sm is at the low level. Therefore, the encoding circuit 15 converts the transmission data into a baseband signal Sb (B) according to the NRZ encoding method and outputs it as an output signal SB, and the encoding / decoding circuit 14 sets a constant high-level signal. The level signal is output as the output signal SA. The signal combining circuit 20 outputs a combined signal Sd equal to the carrier signal Sc by the logical product of the carrier signal Sc and the high-level constant level signal.
[0036]
Therefore, the modulation circuit 21 performs the same operation as when the baseband signal Sb (B) and the carrier signal Sc output from the encoding circuit 15 are directly input, and the TYPE-B The output signal Sw is output via the antenna 16 by performing the 10% ASK modulation of the system.
[0037]
Next, a series of operation contents when the reader / writer 11 communicates with the IC card 12A or 12B will be described. FIG. 4 is a flowchart showing the processing contents of the CPU 13. The CPU 13 first instructs the encoding circuit 15 to turn on the carrier in step S1. Subsequently, in step S2, it is determined whether the modulation method to be applied is the TYPE-A method or the TYPE-B method based on a card selection signal from a higher-level device such as a personal computer. Here, when the card selection signal of the IC card 12A is received, it is determined that the TYPE-A method is applied, and the process shifts to step S3.
[0038]
The CPU 13 sets transmission data in the encoding / decoding circuit 14 in step S3, and outputs an operation permission signal to the encoding / decoding circuit 14 in step S4. As a result, the modulation selection signal Sm is at a high level, the encoding / decoding circuit 14 outputs a baseband signal Sb (A), and the encoding circuit 15 outputs a high-level constant level signal. As a result, the output signal Sw based on the TYPE-A method is output from the modulation circuit 21 via the antenna 16 as described above.
[0039]
The IC card 12A communicates with the reader / writer 11 by load modulating the carrier with the frequency of the subcarrier. The signal received by the antenna 16 is directly input to the encoding / decoding circuit 14, where demodulation and decoding are performed to obtain received data. The CPU 13 reads the received data from the encoding / decoding circuit 14 in step S5.
[0040]
On the other hand, when performing communication with the IC card 12B, it is determined in step S2 that the TYPE-B method is to be applied, and the process proceeds to step S6. The CPU 13 sets the transmission data in the encoding circuit 15 in step S6, and outputs an operation permission signal to the encoding circuit 15 in step S7. As a result, the modulation selection signal Sm is at a low level, the encoding circuit 15 outputs a baseband signal Sb (B), and the encoding / decoding circuit 14 outputs a high-level constant level signal. As a result, the output signal Sw of the TYPE-B system is output from the modulation circuit 21 via the antenna 16 as described above.
[0041]
The IC card 12B also communicates with the reader / writer 11 by performing load modulation.
The signal received by the antenna 16 is demodulated by the demodulation circuit 17, decoded by the decoding circuit 18, and the obtained reception data is set in the encoding circuit 15. The CPU 13 reads the received data from the encoding circuit 15 in step S8. Thereafter, in step S9, the CPU 13 performs processing on the received data that has been read.
[0042]
FIG. 5 is a sequence diagram when the reader / writer 11 communicates with the IC cards 12A and 12B. Here, a case is shown in which communication with the IC card 12A is performed first, and then communication with the IC card 12B is performed. When a TYPE-A card selection signal is transmitted to the reader / writer 11 from a host device such as a personal computer, data transmission and a response to the data are repeated between the reader / writer 11 and the IC card 12A as many times as necessary. When the communication between the reader / writer 11 and the IC card 12A is completed, a processing completion signal is transmitted from the reader / writer 11 to the higher-level device. Upon receiving the processing completion signal, the upper-level device transmits a newly requested card selection signal (TYPE-B selection in FIG. 5) to the reader / writer 11, and the reader / writer 11 receives the request in the same manner as described above. Communication is performed with the TYPE-B IC card 12B.
[0043]
As described above, the reader / writer 11 of the present embodiment performs the encoding / decoding together with the existing encoding / decoding circuits 14 and 15 for encoding TYPE-A and TYPE-B of the modulation method ISO14443. A signal combining circuit 20 for generating a combined signal Sd of the output signal SA of the decoding circuit 14 and the carrier signal Sc is provided. Accordingly, the IC card 12A, 12B of any one of the TYPE-A and TYPE-B can be transmitted from the reader / writer 11 by merely providing the existing modulation circuit 21 for performing the TYPE-B modulation without providing the TYPE-A modulation circuit. Can be transmitted.
[0044]
The signals load-modulated by the IC cards 12A and 12B are distributed immediately after being received by the antenna 16, and are input to an encoding / decoding circuit 14 having a built-in TYPE-A demodulation circuit and decoding circuit. At the same time, the signal is input to the existing demodulation circuit 17 for performing the TYPE-B demodulation, and further to the decoding circuit 18 for performing the TYPE-B system decoding. Therefore, the reader / writer 11 can receive, demodulate, and decode signals from both the TYPE-A and TYPE-B IC cards 12A, 12B.
[0045]
As described above, since the reader / writer 11 of the present embodiment uses the encoding / decoding circuits 14 and 15 and the modulation circuit 21 which are the existing ICs as they are, the reader / writer 11 has the TYPE-A and TYPE-B modulation schemes. Even if they are used, the development cost and manufacturing cost can be minimized. In addition, since the modulation circuit 21 is shared, a single antenna 16 may be provided, and an increase in device size can be prevented.
[0046]
Further, since a common clock is input to the encoding / decoding circuit 14 and the encoding circuit 15 from the oscillation circuit 19, the baseband signals Sb (A) and Sb (B ) Can be synchronized with the carrier signal Sc.
[0047]
The present invention is not limited to the embodiment described above and shown in the drawings. For example, the present invention can be modified or expanded as follows.
Instead of the encoding / decoding circuit 14 configured as one IC, a separately configured encoding circuit, demodulation circuit, and decoding circuit may be provided. Further, instead of the encoding circuit 15, the demodulation circuit 17 and the decoding circuit 18, an IC integrating the encoding circuit, the demodulation circuit and the decoding circuit may be used.
[Brief description of the drawings]
FIG. 1 is a block diagram of a modulation / demodulation circuit part of an IC card reader / writer showing an embodiment of the present invention. FIG. 2 is a signal waveform diagram of each part when transmitting from a reader / writer to a TYPE-A type IC card. 3 A signal waveform diagram of each part when transmitting from a reader / writer to a TYPE-B type IC card. FIG. 4 is a flowchart showing processing contents of a CPU. FIG. 5 is a sequence in a case of communicating with an IC card using a reader / writer. FIG. 6 is a diagram corresponding to FIG. 1 showing the prior art. FIG. 7 is a diagram corresponding to FIG.
11 is a reader / writer (a reader / writer for a non-contact IC card), 14 is an encoding / decoding circuit (first conversion circuit, first demodulation circuit), 15 is an encoding circuit (second conversion circuit, carrier signal) An output circuit), 17 is a demodulation circuit (second demodulation circuit), 20 is a signal synthesis circuit (AND circuit), and 21 is a modulation circuit.

Claims (6)

A modulation circuit having a single carrier signal input terminal and a baseband signal input terminal and outputting an ASK-modulated signal;
A carrier signal output circuit that outputs a carrier signal;
When the modulation selection signal is in the first state, a first baseband signal obtained by encoding transmission data according to a first ASK modulation method is output, and when the modulation selection signal is in the second state, a predetermined constant level signal is output. A first conversion circuit,
When the modulation selection signal is in the first state, a predetermined constant level signal is output. When the modulation selection signal is in the second state, the transmission data is coded according to a second ASK modulation scheme. A second conversion circuit for outputting;
A signal combining circuit that receives the carrier signal and the output signal of the first conversion circuit and generates a combined signal thereof;
A non-contact IC, wherein an output signal of the second conversion circuit is input to a baseband signal input terminal of the modulation circuit, and the composite signal is input to the carrier signal input terminal. Card reader / writer. 2. The reader according to claim 1, wherein the signal synthesizing circuit includes an AND circuit, and the constant level signal output by the first and second conversion circuits is a signal having a high level. lighter. A received signal received by a single antenna is divided into at least two systems, and the divided received signals are respectively used in combination with a first demodulation circuit and a second conversion circuit used in combination with the first conversion circuit. 3. The reader / writer for a contactless IC card according to claim 1, wherein the reader / writer is configured to be input to a second demodulation circuit used in combination. The non-contact IC according to claim 3, wherein the first conversion circuit, the first demodulation circuit, the carrier signal output circuit, and the second conversion circuit are each configured as one IC. Card reader / writer. The reader / writer for a non-contact IC card according to any one of claims 1 to 4, wherein the first and second conversion circuits operate based on a common clock. 6. The non-contact IC card according to claim 1, wherein the first modulation method is a 100% ASK modulation method, and the second modulation method is a 10% ASK modulation method. Reader / writer.

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