Abstract:
Disclosed is a data communication system and method for communicating data between a first integrated circuit card having a first antenna and a first memory and a second integrated circuit card having a second antenna and a second memory, wherein the first antenna is magnetically coupled with the second antenna through a device having an antenna to transmit data from the first memory to the second memory.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to an IC card and an IC card data communication method. Especially, the present invention is applicable to non-contact type IC cards. 
     With an IC card of non-contact type, various data are recorded and read out by use of a dedicated reader/writer. 
     Referring to FIG. 6, there is shown a schematic diagram illustrating a relationship between an IC card and a reader/writer. An IC card  1  is constituted by a wiring board on which a loop antenna  2  and an integrated circuit  3  are arranged and a sheet material such as a plastic, which are laminated into a sheet. With the IC card  1 , the integrated circuit  3  is operated by a high-frequency signal power induced on the loop antenna  2 , thereby transferring various data with a reader/writer  5  via the loop antenna  2 . 
     With the reader/writer  5 , a loop antenna  6  is driven by a predetermined driver circuit and, when the IC card  1  turns on, a high-frequency signal is induced on its loop antenna  2 , thereby starting the operation of the IC card  1 . Also the reader/writer  5  is adapted to transfer commands and data with the IC card  1  by switching the driving of the loop antenna  6  by a modulation/demodulation circuit  7  and processing the high-frequency signal obtained by the loop antenna  6  under the control of a DPU (Digital Processing Unit)  8 . 
     To be more specific, referring to FIG. 7, a signal generation circuit  9  in the reader/writer  5 , generates a high-frequency signal of 13.56 MHz, for example, under the control of the DPU  8  and drives the loop antenna  6  with this signal. The DPU  8  instructs the signal generation circuit  9  to start its operation in response to a request from a host device, outputs various data to be sent to the IC card  1  to the modulation/demodulation circuit  7 , and captures various data received at the modulation/demodulation circuit  7 . Repeating these processes, the DPU  8  executes the processing such as mutual-authentication with the IC card  1 , records data received from the host device to the IC card  1 , and reads data recorded to the IC card  1  to output the data to the host device. 
     The modulation/demodulation circuit  7  modulates the output data of the DPU  8 , varies the terminal impedance of the antenna  6  on the basis of the modulation result, and thereby sends the modulated output data to the IC card  1 . Also, the modulation/demodulation circuit  7  processes the high-frequency signal at the loop antenna  6  with the terminal impedance of the loop antenna  6  kept to a constant value, thereby detecting an impedance variation at the loop antenna  2  of the IC card  1  coupled to the loop antenna  6 . The modulation/demodulation circuit  7  receives the data sent from the IC card  1  and outputs the received data to the DPU  8 . 
     In the IC card  1 , the high-frequency signal induced on the loop antenna  2  is detected by a low-pass filter formed by a diode  11 , a resistor  12 , and a capacitor  13  incorporated in the integrated circuit  3 . A power supply circuit  14  rectifies the received detected high-frequency signal and stabilizes the rectified signal to generate an operating power supply. 
     The modulation/demodulation circuit  15  receives the detection result via a high-pass filter formed by a capacitor  16  and a resistor  17  and processes the received detection result to demodulate the data transmitted by the reader/writer  5 . Further, the modulation/demodulation circuit  15  modulates output data from a sequencer  19  under the control thereof, thereby controlling the on/off of a field-effect transistor FET on the basis of the modulation result. The on/off control causes the FET to ground load Z connected to the anode of the diode  11 . Consequently, in the IC card  1 , the terminal impedance of the loop antenna  2  coupled with the loop antenna  6  of the reader/writer  5  is switched, transmitting various data to the reader/writer  5 . 
     The sequencer  19  starts operating on the power supplied from the power supply circuit  14  to output various data to the modulation/demodulation circuit  15  in accordance with the data supplied from the reader/writer  5  detected by the modulation/demodulation circuit  15 . Consequently, the IC card  1  approaches the reader/writer  5  and starts operating. Detecting a polling from the reader/writer  5 , the IC card  1  executes processing such as mutual-authentication. After a series of these operations, the sequencer  19  accesses a memory  20  in accordance with the data supplied from the modulation/demodulation circuit  15  to update the contents of the memory  20  and output the updated data to the modulation/demodulation circuit  15 . 
     Consequently, the system based on the IC card  1  is available as a room access control means by storing the personal information of each user into his IC card  1  and as a credit card by recording purchase log information for example about various commercial articles to the IC card  1 . 
     It is possible to use IC cards as entrance tickets for various event places. In this case, the purchase of an entrance ticket for an event place is recorded on the IC card by online access for example before entering the event. Therefore, the organizer of the event can easily and surely manage the entries by checking the recording of their IC cards at the entrance of the event place. This also allows the users to purchase desired entrance tickets from remote places. 
     However, the use of IC cards as entrance tickets requires copying a part of each IC card to another with security. 
     Namely, tickets which are issued in paper may be purchased in bulk for distribution. If the IC cards used as entrance tickets are purchased in bulk, it is possible that the entrance tickets purchased in bulk are recorded in one IC card. If this happens, the record in such an IC card must be copied to other IC cards to distribute the entrance tickets. 
     If the copying of a part of an IC card to others is performed by means of a reader/writer, unauthorized copies may take place. It is therefore necessary to perform the copying as securely as possible. 
     If an IC card is used as a credit card, the IC card may be periodically updated to a new one. If the IC card is updated, the information, such as a purchase log recorded to this IC card, must be all copied to a new IC card and as securely as possible. 
     SUMMARY OF THE INVENTION 
     An advantage of the present invention to provide an IC card and an IC card data communication method for securely copying the contents of one IC card to another. To be more specific, the present invention is intended to directly exchange data between IC cards by use of the coupling between the antennas of the IC cards via the antenna of a reader/writer, thereby securely copying the contents of one IC card onto another IC card. 
     According to one embodiment of the present invention, there is provided a data communication method for communicating data between a first IC card having a first antenna and a first memory and a second IC card having a second antenna and a second memory, wherein the first antenna is magnetically coupled with the second antenna through a device having an antenna to transmit data from the first memory to the second memory. 
     With this configuration, data is directly transferred between IC cards by use of the electromagnetic coupling of their antennas by use of the antenna of a reader/writer. Consequently, the contents of one IC card can be copied to another in security. 
     Various features and advantages of the present invention will become apparent from this description and the appended claims, taken in conjunction with the accompanying drawings in which like parts or elements are denoted by like reference symbols. The features and advantages may be desired, but not necessarily required to practice the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram illustrating an IC card system associated with a first embodiment of the invention; 
     FIG. 2 is a timing chart describing data exchange operations between an IC card and a reader/writer; 
     FIG. 3 is a timing chart describing antenna coupling between the IC cards shown in FIG. 1; 
     FIG. 4 is a schematic diagram illustrating a relationship between a loop antenna and IC cards practiced as another embodiment of the invention; 
     FIG. 5 is a schematic diagram illustrating a relationship between a loop antenna and IC cards practiced as still another embodiment of the invention; 
     FIG. 6 is a schematic diagram illustrating a prior-art IC card system; and 
     FIG. 7 is a block diagram illustrating a detailed configuration of the related-art IC card system shown in FIG.  6 . 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     This invention will be described in further detail by way of example with reference to the accompanying drawings. 
     Referring to FIG. 1, there is shown a block diagram illustrating an IC card system practiced as a first embodiment of the invention. In an IC card system  21 , a reader/writer  23  is configured in the same manner as the related-art reader/writer  5  described before with reference to FIGS. 6 and 7. An IC card  24 A and an IC card  24 B are configured in generally the same manner as the IC card  1  described before with reference to FIGS. 6 and 7, except for the data stored in a memory  20 A and a memory  20 B. 
     To be more specific, the IC card  24 A is loaded alone in the reader/writer  5  as described with reference to FIG. 6 and a predetermined application program of a personal computer, which is a host unit of the IC card system, is executed to store the purchase record about the entrance ticket for an event desired by the user into the memory  20 A. Consequently, the user can carry the IC card  24 A and pass an entrance gate arranged with a reader/writer to the event like passing a ticket barrier in a railway station. 
     As such an entrance ticket purchase record, the IC card  24 A stores data for identifying the event, data for identifying the seat if the event is a music concert, for example, and data for identifying the purchase action, such as a purchase number along with data for providing security by the data unique to these data. If a plurality of tickets have been purchased in bulk, these data are recorded for each of the purchased tickets as purchase records and, in addition to these data, data about the number of tickets purchased is recorded. Further, processing-restricting data is added to the IC card  24 A, as an entrance ticket purchase record, indicative that all of the above-mentioned data are readable only for direct data transfer between IC cards, that is, the reader/writer  5  may only browse the data for identifying the event and seat and the number of purchased tickets but cannot read the security data. 
     Further, the IC cards  24 A and  24 B store, in their memories  20 A and  20 B in a protected manner, commands and their sequences for transferring data having processing-restricting data to the IC card  24 B. Moreover, the IC cards  24 A and  24 B allocate codes, for commands used for these sequences, different from those for commands transferred with the reader/writer  23 , thereby preventing the reader/writer  23  from knowing the sequence of processes being made between the cards. 
     In the IC card system  21 , when a predetermined application program for making the tickets bulk purchased by the IC card  24 A be available in the IC card  24 B is started in a personal computer  22 , the user is prompted on a display screen of the personal computer  22  to load the IC card  24 A in a predetermined position of the reader/writer  23  and the personal computer  22  issues a start command to the reader/writer  23 . 
     Receiving the start command, the reader/writer  23  starts the loop antenna  6  by high-frequency signal, which starts the operation of the IC card  24 A when the IC card  24 A is placed near the reader/writer  23 . As shown in steps SP 1  through SP 6  in FIG. 2, the reader/writer  23  issues a polling to the IC card  24 A. When the IC card  24 A responds, the reader/writer  23  performs mutual-authentication with the IC card  24 A. When mutual-authentication is completed, the reader/writer  23  sends a read command for reading the ticket-associated data to the IC card  24 A under the control of the personal computer  22 . In response to the read command, the IC card  24 A reads from its memory  20 A the data for identifying the object to be transferred by the user (namely, the data for identifying the event and the seat) and returns the data to the reader/writer  23 , except the security data. 
     The reader/writer  23  passes the data received from the IC card  24 A to the personal computer  22 , thereby allowing the user to actually identify the entrance tickets to be transferred to the IC card  24 B on the display screen of the personal computer  22  in the IC card system  21 . 
     When the tickets to be transferred are identified (event place and seat number), the personal computer  22  executes the above-mentioned application program to prompt the user to load the IC card  24 B into the reader/writer  23 . 
     In the IC card system  21 , the personal computer  22  instructs the user to load the IC card  24 B such that it overlaps the IC card  24 A. Consequently, in the IC card system  21 , the loop antenna  6  of the reader/writer  23  and the loop antennas  2 A and  2 B of the IC cards  24 A and  24 B are interconnected, upon which both IC cards  24 A and  24 B are operated by electric power supplied from the reader/writer  23 . Further, as shown in FIG. 3, when the terminal impedance is switched in any one of the loop antennas  6 ,  2 A, and  2 B, the switching is detected by the other devices. 
     FIG. 3 shows transmission results (A 1 ), (B 1 ), and (C 1 ) of each of the reader/writer  23 , and the IC cards  24 A and  24 B and reception results (A 2 ), (B 2 ), and (C 2 ) of the outputs of the modulation/demodulation circuits  7 ,  15 A, and  15 B. In period T 1 , terminal impedance switching is stopped in the reader/writer  23  and the IC card  24 B and terminal impedance is switched in the IC card  24 A. In this case, in response to the terminal impedance switching in the IC card  24 A, the reader/writer  23  and the IC card  24 B can receive data. In period T 2 , terminal impedance switching is stopped in the reader/writer  23  and the IC card  24 A and terminal impedance is switched in the IC card  24 B. In this case, in response to the terminal impedance switching in the IC card  24 B, the reader/writer  23  and the IC card  24 A can receive data. In the present embodiment, these periods T 1  and T 2  are used to transfer entrance ticket data from the IC card  24 A to the IC card  24 B and return processing responses from the IC card  24 B to the IC card  24 A. 
     When the IC cards  24 A and  24 B are loaded in an overlapped manner, the personal computer  22  instructs the reader/writer  23  to recognize the IC card  24 B. The reader/writer  23  issues a new polling and, when a response comes from the IC card  24 B, performs mutual-authentication and then checks the contents of the memory  20 B in the IC card  24 B (steps SP 7  through SP 12  in FIG.  2 ). 
     When the IC cards  24 A and  24 B are found loaded in an overlapping manner, the personal computer  22  instructs the IC card  24 A to transfer the entrance ticket specified by the user in step SP 13 . 
     In response, the IC card  24 A executes a corresponding sequence stored in the memory  20 A to issue a polling to the IC card  24 B and receive a response therefor (steps SP 14  and SP 15 ), and execute mutual-authentication with the IC card  24 B (steps SP 16  and SP 17 ). Further, the IC card  24 A instructs the IC card  24 B to write all or part of the purchase record data specified by the personal computer  22  to the memory  20 B of the IC card  24 B (steps SP 18  and SP 19 ). In response, the IC card  24 A updates the contents of its memory  20 A. 
     If the event data are recorded in the memory  20 A in an amount equivalent to the number of purchased tickets, the data including the security data for the number of tickets specified by the user are transferred to the memory  20 B of the IC card  24 B. The transferred data are deleted from the memory  20 A of the IC card  24 A. If the number of purchased tickets is recorded by recording the data in an amount equivalent to the number of purchased tickets, the same data recorded in the memory  20 A is recorded in the memory  20 B according to the record of the number of tickets specified by the user and the contents of the memory  20 A are updated so as to decrement the number of purchased tickets. It should be noted that, if all of purchased tickets stored in the IC card  24 A are transferred to the IC card  24 B, only the record is kept recorded in the IC card  24 A. 
     In the above-mentioned processes, the data is transferred from the IC card  24 A to the IC card  24 B in the same data format including the processing-restricting data. This allows the IC card system  21  to further transfer the transferred entrance tickets between the IC card  24 B and another IC card and prevent the reader/writer  23  from updating the contents of the IC card  24 B. 
     In order to perform the above-mentioned processes, the memory  20 A and the memory  20 B store commands and their sequences for copying, moving, dividing, connecting, and comparing the data between the IC cards. 
     When the processing specified by the personal computer  22  is completed, the IC card  24 A reports a processing result to the reader/writer  23 , by which the user can check the processing result. 
     It should be noted that the communication of the above-mentioned various data between the IC cards  24 A and  24 B and the reader/writer  23  is encrypted by mutual-authentication. Consequently, the data contents transferred between the IC cards  24 A and  24 B cannot be understood by the reader/writer  23  for example. 
     In the above-mentioned configuration, the IC card system  21  accesses an entrance ticket sales center for example through the personal computer  22  with the IC card  24 A loaded in the reader/writer  23  and performs a sequence of processes to purchase the entrance ticket of a desired event to store the purchase record into the memory  20 A of the IC card  24 A. 
     The IC card system  21  checks the IC card  24 A by the reader/writer arranged at the entrance of the event place to see if the holder of the IC card  24 A is an authorized user having a right for entering the event place, thereby permitting or prohibiting the entry into the event place. 
     Thus, when recording the entrance ticket into the IC card  24 A, the IC card system  21  also records the security data aside from the data identifying the event place, for example, and sets the processing restricting data, thereby allowing the reader/writer  23  to read only the data for identifying the event place, for example, except the security data. Consequently, if the reader/writer  23  at the entry for the event place attempts to read the entrance ticket purchase record and to record the same into another IC card, the IC card system  21  can prevent unauthorized actions by the security data. 
     Conversely, the reader/writer  23  is allowed to read only the data for identifying the event place, for example, which allows the user to check the ticket purchased by use of the reader/writer  23 , thereby executing ticket transfer to any third party in an authorized manner. 
     Namely, in the IC card system  21 , the data about the event place and seat, for example, are read and displayed by the reader/writer  23  from the IC card  24 A by the execution of the application program of the personal computer  22 , thereby allowing the user to accept the contents of the entrance ticket to be transferred to the IC card  24 B. Further, when the user accepts the contents of the ticket, the user is instructed to load the IC cards  24 A and  24 B in an overlapped manner. In this state, the IC cards  24 A and  24 B are thus loaded and operated by the high-frequency signal supplied from the loop antenna  6  of the reader/writer  23 , transferring the data not only between the IC cards and the reader/writer  23  but also between the IC cards themselves. 
     In this state, the reader/writer  23  instructs the IC card  24 A, which is the entrance ticket recording side, to transfer the ticket specified by the user. After mutual-authentication between the IC cards  24 A and  24 B, all or part of the entrance ticket purchase record is transferred from the IC card  24 A to the IC card  25 B in accordance with the sequence recorded in the IC card  24 A. Consequently, the IC card system  21  allows the user having the IC card  24 B to enter the event place. 
     At this time, the IC card system  21  transfers the record from the IC card  24 A to the IC card  24 B by the sequence recorded in the IC card  24 A as instructed by the reader/writer  23  or executes a sequence of processes by the commands unique to the data communication between the IC cards  24 A and  24 B and unrecognizable by the reader/writer  23 , thereby preventing the reader/writer  23  from intervening this sequence of processes. Consequently, the data of this type can be transferred with security and stored in the IC cards  24 A and  24 B. Thus, the present embodiment can perform easy and secure data transfer between the IC cards. 
     In the above-mentioned configuration, the antenna of the reader/writer and the antennas of the IC cards  24 A and  24 B which are operated by the electric power supplied by the reader/writer  23  are coupled to each other to transfer data directly between the IC cards  24 A and  24 B, realizing secure data transfer between the IC cards. 
     In addition, execution of this data transfer by switching the terminal impedance in the antenna and by the signal processing of the high-frequency signal, which vanes by this switching, allows the data transfer between the IC cards in the same manner as the data transfer with the reader/writer. 
     In the security data, of the data stored in memory, having the processing restricting data, which is a predetermined identification code, it is possible to prevent unauthorized copying of entrance tickets by ignoring the access command from the reader/writer. 
     The data transfer with the IC card  24 B in accordance with the sequence stored in memory minimizes the intervention by the reader/writer, thereby providing secure data transfer between the IC cards. 
     The data transfer between the IC cards is encrypted on the basis of mutual-authentication and the data transfer between the IC cards is executed by use of the commands different from those used for the data transfer with the reader/writer, thereby realizing the data transfer between the IC cards more securely. 
     In a second embodiment of the invention, the IC card system is used to update credit cards. In the second embodiment, the IC card system is configured in generally the same manner as the IC card system  21  of the first embodiment, except for the contents of data stored in IC cards. Therefore, the second embodiment will be described by use of the configuration shown in FIG.  1 . 
     In the second embodiment, the IC card  24 A is a credit card conventionally used by the user, recording a commercial product purchase record. In addition to this record, the IC card  24 A is adapted to record the contents of the memory  20 A so as to use the IC card  24 A as electronic money and a membership card, for example, under contract with the credit card company. The contents of the memory  20 A associated with these different kinds of services are each encrypted by a key unique to each service provider. 
     The IC card  24 B is a card newly issued to the user of the IC card  24 A, extending the expiration date of the IC card  24 A. The data indicative of the expiration date is stored in the memory  20 A and the memory  20 B of the IC cards  24 A and  24 B. In the IC card  24 B, data for identifying the IC card  24 A to be updated is stored in the memory  20 B. Further, the IC card  24 B records in its memory  20 B a predetermined processing procedure for automatically starting a predetermined sequence upon the starting of the IC card  24 B. 
     In the second embodiment, after executing the application program for instructing the update of the IC cards  24 A and  24 B, the personal computer  22  displays an operational procedure on the display screen and controls the reader/writer  23  to start sending the high-frequency signal from the antenna  6  of the reader/writer  23 . Consequently, when the IC cards  24 A and  24 B are put close to the reader/writer  23 , these IC cards start operating, the IC card  24 B starting the sequence stored in its memory. 
     In this sequence, data necessary for using the IC card  24 B instead of the IC card  24 A, such as the commercial product purchase record stored in the IC card  24 A, is transferred from the IC card  24 A to the memory  20 B. This sequence is executed by the commands unique to the data transfer between the IC cards, which are different from the commands for data transfer with the reader/writer  23 . 
     When the IC card  24 A starts operating by this sequence, the reader/writer  23  issues a polling to the IC card  24 A for mutual-authentication. Then, the reader/writer  23  determines whether the IC card  24 A is to be updated or not. If the IC card  24 A is to be updated, the reader/writer  23  sequentially reads the contents from the memory  20 A and writes them into the memory  20 B at corresponding memory locations. When the recording has been completed, the IC card  24 A becomes unusable because of the update. The sequence which has executed the above-mentioned processes will not start again. 
     It should be noted that the IC card  24 A, after mutual-authentication with the reader/writer  23  as required, reports the completion of the processing to the reader/writer  23 . 
     Execution of the sequence recorded in the destination side of data transfer can also perform data transfer in security between IC cards as with the second embodiment. 
     In a third embodiment of the invention, the IC card system is used to transfer an entrance ticket record from the IC card  24 A to the IC card  24 B as with the first embodiment. In the third embodiment, the IC card is configured in generally the same manner as the IC card system  21  of the first embodiment, except the processing by the personal computer  22  and the contents recorded to the IC cards. Therefore, the third embodiment will be described by use of the configuration shown in FIG.  1 . 
     In the third embodiment, in response to a command issued from the reader/writer  23 , the IC card  24 A or  24 B transfers commands unique to the data transfer between IC cards, thereby transferring data directly between the IC cards  24 A and  24 B in accordance with the sequence of the application program executed in the personal computer  22  to transfer data between the memory  20 A and the memory  20 B. 
     Thus, the data transfer directly between the IC cards  24 A and  24 B for exchanging the contents of the memories by the processing executed by the sequence of the host unit can also provide the same effects as those of the first embodiment. 
     In the third embodiment, the data recorded to the IC card  24 A by the application program can be transferred to the IC card  24 B after processing by the IC card  24 A in a complex manner. This allows the third embodiment to be widely applied to the creation of child cards by partially limiting the capabilities of the parent card, for example. 
     In the above-mentioned embodiments, the IC cards are loaded in the reader/writer in an overlapped manner. The present invention is also applicable to an arrangement shown in FIG. 4 in which the IC cards  24 A and  24 B are arranged side by side relative to a large loop antenna of the reader/writer, therein electromagnetically coupling the antennas of the IC cards  24 A and  24 B; and an arrangement shown in FIG. 5 in which the IC cards  24 A and  24 B are arranged side by side relative to a loop antenna of the reader/writer which has a form of two same shaped antennas connected to each other, therein electromagnetically coupling the antennas of the IC cards  24 A and  24 B, for example. Namely, the present invention is widely applicable to any arrangements in which the antennas of the IC cards between which data is transferred are electromagnetically coupled via a power supply antenna. 
     In the above-mentioned embodiments, the contents of one IC card are transferred to another and the transferred contents are deleted from the source card or made unusable therein. The present invention is also applicable to an arrangement in which the contents of one card may only be copied to another, retaining the transferred contents in the source card. 
     In the above-mentioned embodiments, the present invention is applied to an arrangement in which an entrance ticket record or a credit card record is transferred. The present invention is also applicable to any arrangement in which the contents of one IC card are copied to another. 
     Also, in the above-mentioned embodiments, data recorded to a plurality of IC cards are transferred via the reader/writer. If only the data transmission is executed, any device having an antenna which electromagnetically couples with each IC card may be used rather than the above-mentioned IC card reader/writer. 
     While the preferred embodiments of the present invention have been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the appended claims.