JP2005079783A - COMMUNICATION SYSTEM, INFORMATION STORAGE MEDIUM, AND COMMUNICATION DEVICE - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new and improved communication system capable of realizing high-speed communication between an IC card having a contact type non-contact type communication card and a communication device for communicating with the IC card. It is to be.
A card communication system that includes a contactless contactless IC card 100 and a communication device 200 that communicates with the IC card. The first electrode unit 110 for forming a capacitive coupler serving as a communication path is formed, and the communication device is integrated with the first electrode unit in the communication unit 210 to which the IC card is closely attached. A second electrode unit 220 that forms the capacitive coupler 270 is formed, and a modulation method in which a carrier or clock frequency is assigned to approximately the center of a band in which communication is possible in the capacitive coupler is employed.
[Selection] Figure 1

Description

  The present invention relates to a communication system, and in particular, a contactless non-contact type information storage capable of holding information in an IC (Integrated Circuit) embedded therein and performing communication without contacting a communication device. The present invention relates to a medium (hereinafter simply referred to as an information storage medium), a communication device that communicates with the information storage medium, and a communication system that includes these information storage medium and communication device as components.

  In recent years, an information storage medium in which an IC (Integrated Circuit) is embedded in a card is rapidly spreading. By mounting a memory capable of rewriting data on an IC, one IC card can be used repeatedly. IC cards are more resistant to failures than conventional magnetic cards and have a large amount of information that can be stored, so they can be used for online electronic commerce over a network, and can also be used for offline identification and passports. It can be used widely for alternatives. Under such circumstances, a non-contact type IC card (hereinafter simply referred to as a non-contact type card) is used for the purpose of eliminating the trouble of taking out the IC card from the card storage case. Such contactless IC cards are embedded with transmission / reception means (antennas) for transmitting and receiving data by radio systems such as radio waves, and hold the contactless cards over a dedicated card terminal (card reader / writer). As a result, data can be transmitted and received and power can be supplied without contacting the contactless card and the card terminal.

  As described above, IC cards can be classified into contact cards and non-contact cards based on the difference in interface. Unlike contact cards that have external terminals for connection to card terminals, contactless cards supply power and read and write data through an internal antenna. The non-contact type mainly composed of memory cards is classified into four types, contact type, proximity type, proximity type, and remote type, depending on the communication distance. The communication distances of the contact type are 2 mm, the proximity type is 10 cm, the proximity type is 70 cm, and the remote type is about several meters. The proximity type is the electromagnetic induction type, and the remote type is the microwave type. Proximity type is being put to practical use as electronic tickets and telephone cards. A card that has both contact type and non-contact type functions is called a combination card or hybrid card. For example, it is expected to be a contact type in the payment field such as electronic money, and a non-contact type for entry / exit management. Has been.

  In the case of a contact-type non-contact type IC card, as another communication method, for example, there is a technique using a capacitive coupler. In this technology, an electrode portion formed on the surface of the IC card and an electrode portion formed on the surface of the card terminal have a function of a capacitor element (also referred to as a capacitor element or a capacitance element). A capacitive coupler is formed and used as a data transmission channel between the IC card and the card terminal (for example, see Patent Document 1).

Japanese Patent Publication No. 6-85191

  As described above, with the rapid spread of IC cards, a technology capable of higher-speed data communication is required. In addition, there is a concept of using IC cards as storage (removable storage media) that can handle large-capacity memories as a new form of use of IC cards. In this respect as well, technology capable of higher-speed data communication is required. It has been.

  The present invention has been made in view of the above-described background art, and an object of the present invention is an information storage medium having a contact type non-contact communication method, and a communication device that performs communication between the information storage medium and an information storage medium. Is to provide a new and improved communication system capable of realizing high-speed communication (data transmission).

  According to a first aspect of the present invention, there is provided a communication system including a contact-type non-contact information storage medium and a communication device that performs communication between the information storage medium and the information storage medium. On the surface of the medium, a first electrode part for forming a capacitive coupler serving as a communication path with the communication device is formed, and the communication device has a communication unit to which the information storage medium is in close contact, A modulation method in which a second electrode portion that forms the capacitive coupler is formed integrally with the first electrode portion, and a carrier or clock frequency is assigned to substantially the center of a band in which communication is possible in the capacitive coupler. A communication system is provided which is characterized by adopting

  According to such a configuration, since the carrier or clock frequency is almost at the center of the band in which communication (data transmission) is possible, all the bands in which data transmission is possible can be effectively used for data transmission. Thus, the present invention enables high-speed communication (high-speed data transmission). In addition, by enabling high-speed data transmission, it can be used without stressing the user even in conventional usage forms of general information storage media such as electronic commerce and identification certificates. It becomes. Furthermore, according to the present invention, as a new usage form of the information storage medium, the information storage medium can be used as a storage (removable storage medium) that can accommodate a large-capacity memory.

  In the communication system of the present invention, the following applications are possible.

  A plurality of first electrode portions may be formed on the surface of the information storage medium, and a plurality of second electrode portions may be formed on the communication portion of the communication device. By forming two or more electrode portions and two or more capacitance couplers on the information storage medium and the communication device, respectively, data of a plurality of channels can be transmitted in parallel. In general, when a plurality of channels are to be transmitted in parallel, there is known a method of clock recovery using a PLL (Phase Locked Loop) without sending a clock. However, when trying to regenerate the clock with the PLL, there is a problem that the circuits interfere with each other and become unstable. In this regard, according to the present invention, data of a plurality of channels is transmitted in parallel by forming two or more electrode portions and two or more capacitance couplers on the information storage medium and the communication device, respectively. It is possible to increase the speed of data transmission while maintaining stability without causing problems.

  As described above, two or more electrode portions and two or more capacitance couplers are formed on the information storage medium and the communication device, respectively, so that a clock for demodulating data is transmitted through a channel different from the data. It is possible.

  As a communication method (modulation method) using the capacitive coupler as a communication path, a BPSK (Bi-phase shift keying) modulation method may be employed. Further, the Manchester encoding method may be adopted. Since the capacitive coupler does not pass direct current (DC), it must be DC-free. In a general DC-free modulation system, when the transmission is performed using the entire channel band, the clock is out of the band. If the clock is put in the band, the data rate is lowered and the clock comes to the end of the band and becomes unstable. Therefore, by adopting the BPSK modulation method or the Manchester coding method as a modulation method, even when transmission is performed using the entire band of the channel, the clock is not out of the band, and the data rate and the stability are made compatible. It becomes possible. In addition, since it is resistant to characteristic fluctuations, it can be used in various situations such as using an information storage medium as a storage (removable storage medium) that can handle a large-capacity memory as described above.

  Further, by adopting the BPSK modulation method or the Manchester encoding method as the modulation method, the circuit configuration is simplified. In particular, it is extremely effective to employ a modulation method that can simplify the circuit configuration in an information storage medium that is required to be thin and small.

  In particular, by adopting the BPSK modulation method as a modulation method, there is an effect that any carrier can be used. On the other hand, by adopting the Manchester encoding method as a modulation method, there is an effect that an IC can be realized only by a digital CMOS (Complementary Metal Oxide Semiconductor).

  The communication device can be configured to transmit and receive data to and from the information storage medium and to supply power to the information storage medium. Since the present invention enables high-speed communication as described above, in addition to reading data from the information storage medium, writing can be performed, and power can be stably supplied to the information storage medium. Is possible. Note that the communication device of the present invention may perform only one of reading and writing of the information storage medium. The power supply to the information storage medium may or may not have the function.

  The area of the second electrode portion can be about 20 mm square. Considering the size and communication characteristics of the information storage medium and the communication unit of the communication device, a configuration in which the area is approximately 20 mm square can be adopted as the configuration of the second electrode unit.

  According to the second aspect of the present invention, a contactless non-contact information storage medium is used for communication with a communication device, and a capacitive coupler serving as a communication path with the communication device is formed on the surface. The communication device is provided with a second electrode portion that is integrated with the first electrode portion to form a capacitive coupler in the communication portion to which the information storage medium is closely attached. There is provided an information storage medium characterized in that a communication system using a capacitive coupler as a communication channel is a communication system in which a carrier or a clock frequency is allocated to almost the center of a band where data transmission is possible in the capacitive coupler. The

  According to such a configuration, since the carrier or clock frequency is almost at the center of the band in which communication (data transmission) is possible, all the bands in which data transmission is possible can be effectively used for data transmission. Thus, the present invention enables high-speed communication (high-speed data transmission). In addition, by enabling high-speed data transmission, it can be used without stressing the user even in conventional usage forms of general information storage media such as electronic commerce and identification certificates. It becomes. Furthermore, according to the present invention, as a new usage form of the information storage medium, the information storage medium can be used as a storage (removable storage medium) that can accommodate a large-capacity memory.

  In the information storage medium of the present invention, the following applications are possible as in the communication system according to the first aspect of the present invention.

  A plurality of first electrode portions may be formed on the surface, and a plurality of second electrode portions may be formed in the communication unit of the communication device, so that data of a plurality of channels may be transmitted in parallel. By forming two or more electrode parts and two or more capacitive couplers on the information storage medium and the communication device, respectively, it is possible to send a clock for demodulating data on a channel different from the data. .

  The modulation method may be a BPSK modulation method or a Manchester encoding method.

  In addition, data may be transmitted to and received from the communication device, and power may be supplied from the communication device.

  According to a third aspect of the present invention, there is provided a communication device that performs communication with an information storage medium having a contact type non-contact communication method, and a communication path with the communication device is provided on the surface of the information storage medium. A first electrode part for forming a capacitive coupler is formed, and a second part is formed integrally with the first electrode part on the communication part to which the information storage medium is closely attached. The communication method in which the electrode part is formed and the capacitive coupler is used as a communication path is a communication method in which a carrier or a clock frequency is assigned to almost the center of a band where data transmission is possible in the capacitive coupler. , A communication device is provided.

  According to such a configuration, since the carrier or clock frequency is almost at the center of the band in which communication (data transmission) is possible, all the bands in which data transmission is possible can be effectively used for data transmission. Thus, the present invention enables high-speed communication (high-speed data transmission). In addition, by enabling high-speed data transmission, it can be used without stressing the user even in conventional usage forms of general information storage media such as electronic commerce and identification certificates. It becomes. Furthermore, according to the present invention, as a new usage form of the information storage medium, the information storage medium can be used as a storage (removable storage medium) that can accommodate a large-capacity memory.

  In the communication apparatus of the present invention, the following applications are possible as in the communication system according to the first aspect of the present invention.

  A plurality of second electrode units may be formed in the communication unit, and a plurality of first electrode units may be formed on the surface of the information storage medium to transmit data of a plurality of channels in parallel. By forming two or more electrode parts and two or more capacitive couplers on the information storage medium and the communication device, respectively, it is possible to send a clock for demodulating data on a channel different from the data. .

  The modulation method may be a BPSK modulation method or a Manchester encoding method.

  In addition, data may be transmitted to and received from the information storage medium, and power may be supplied to the information storage medium.

  In addition, the area of the second electrode portion can be about 20 mm square.

  As described above, according to the present invention, since the carrier or clock frequency is almost at the center of the band where communication (data transmission) is possible, all the bands where data transmission is possible are effectively used for data transmission. can do. Thus, the present invention enables high-speed communication (high-speed data transmission). In addition, by enabling high-speed data transmission, it can be used without stressing the user even in conventional usage forms of general information storage media such as electronic commerce and identification certificates. It becomes. Furthermore, according to the present invention, as a new usage form of the information storage medium, the information storage medium can be used as a storage (removable storage medium) that can accommodate a large-capacity memory.

  Exemplary embodiments of a communication system, an information storage medium, and a communication device according to the present invention will be described below in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted. In the present embodiment, an IC card that is a card-shaped information storage medium is taken as an example of an information storage medium, and a card reader / writer for reading and writing information to and from the IC card is taken as an example of a communication device. Taking the writer as an example, the communication system according to the present embodiment will be described as a card communication system for convenience. However, the information storage medium of the present invention is not limited to a card shape.

A system configuration of the communication system according to the present embodiment will be described.
FIG. 1 is an explanatory diagram of the card communication system according to the present embodiment.
As shown in FIG. 1, the card communication system according to the present embodiment is a card reader as an example of a communication device that performs communication between an IC card 100 with a contact type contactless contactless IC card 100 and the IC card 100. / A system including a writer 200. As shown in FIG. 1, the contact type non-contact type IC card 100 can be held over the card reader / writer 200 to perform communication between them. Hereinafter, these system components will be described in order.

(A) IC Card FIG. 2 is an explanatory diagram of the IC card 100 according to the present embodiment.
As shown in FIG. 2, the IC card 100 has an IC (Integrated Circuit) embedded in an ordinary card having a size of about 8.5 cm × 5.5 cm and a thickness of about 2 mm to hold information therein. Card. The IC card 100 according to the present embodiment includes a communication distance among cards (non-contact type cards) that can communicate without contacting a card reader / writer 200 for reading / writing information to / from the IC. Is assumed to be a card that employs a so-called contactless non-contact communication method of about 2 mm.

  The IC card 100 is a batteryless card designed with power saving and durability operating by capturing minute electromagnetic waves from the card reader / writer 200. As a surface material of the IC card 100, for example, a PET (polyethylene terephthalate) material that has little influence on the environment even when incinerated can be used.

  As such a contact type non-contact type IC card, there is Felica standardized by Sony Corporation. FeliCa can read and write data by simply holding it over a card reader / writer (reading / writing device). In addition, since encryption processing is used for communication between the card reader / writer and the IC card, it can be used for applications that require reliable security. Moreover, since a series of operations in which a card reader / writer detects and activates an IC card, performs mutual authentication, and reads and writes data can be performed at high speed, it is suitable for applications that require speedy processing.

  On the surface of the IC card 100, as shown in FIG. 2, an electrode portion (first electrode portion) 110 for forming a capacitive coupler that becomes a communication path with the card reader / writer 200 is formed. . In the example shown in FIG. 2, two electrode portions 110 are formed. An IC module 120 is embedded in the IC card 100.

(Electrode part 110)
The electrode part (first electrode part) 110 is integrated with an electrode part 220 formed in a card reader / writer 200 described later, and constitutes a capacitive coupler that serves as a communication path with the card reader / writer 200. By exchanging data between the IC card 100 and the card reader / writer 200 with a capacitive coupler, the circuit configuration can be simplified, and as a result, the IC card 100 can be reduced in thickness and size. By forming two or more electrode portions and two or more capacitance couplers on the IC card 100 and the card reader / writer 200, respectively, data of a plurality of channels can be transmitted in parallel. As a result, high-speed data transmission can be realized. The capacitive coupler will be further described later.

(IC module 120)
FIG. 3 is an explanatory diagram conceptually showing the functional configuration of the IC module 120.
As shown in FIG. 3, the IC module 120 includes a processing circuit 121 and a memory 122.

  The processing circuit 121 performs various processes according to predetermined information and requests. For example, a high-speed CPU (Central Processing Unit) can be incorporated as the processing circuit 121. Further, by adopting encryption communication such as TripleDES for communication with a card reader / writer 200 described later, security equivalent to or higher than that of the contact IC card can be realized. In the present embodiment, the processing circuit 121 mounted on the IC card 100 is characterized. That is, a predetermined communication modulation circuit is configured integrally with a processing circuit 230 mounted on a communication unit 210 of the card reader / writer 200 described later. A specific circuit configuration of the processing circuit 121 will be described later.

  The memory 122 is composed of a rewritable storage medium, for example, an electrically erasable and erasable EEPROM (Electrically Erasable and Programmable ROM). Information can be written to the memory 122 in units of a plurality of blocks, for example, up to 8 blocks (1 byte 2 bytes), and writing processing and reading processing can be performed in parallel. The memory 122 can store and store various types of data, and can also record a card-specific operating system and applications. Note that read / write processing with respect to the memory 122 is not an essential feature of the present embodiment, and thus a more detailed description is omitted.

The contact type non-contact type IC card 100 has been described above.
Next, a card reader / writer 200, which is an example of a communication device that performs communication with the IC card 100, will be described with reference to FIG.

(B) Card Reader / Writer FIG. 4 is an explanatory diagram showing a state in which the card reader / writer 200 according to the present embodiment is connected to the computer 250.
As shown in FIG. 4, the card reader / writer 200 is connected to a computer 250 used by the user. The card reader / writer 200 is provided with a communication unit 210 to which the IC card 100 is closely attached. The card reader / writer 200 can transmit / receive data to / from the IC card 100 (read / write) and supply power to the IC card 100 via the communication unit 210.

  As shown in FIG. 5, the communication unit 210 is formed with an electrode unit (second electrode unit) 220. As shown in FIG. 5, the electrode part 220 has an area of about 20 mm square.

FIG. 6 is an explanatory diagram showing a state where the card 100 is held over the communication unit 210.
The electrode unit 220 is connected to a processing circuit 230 mounted on the card reader / writer 200.

(Electrode part 220)
The electrode part (second electrode part) 220 is an electrostatic capacity coupler that is integrated with the electrode part 100 formed on the IC card 100 and has a function of a capacitor element (also referred to as a capacitor element or a capacitance element). 270 is formed. Communication between the IC card 100 and the card reader / writer 200 is performed using the capacitance coupler 270 as a data transmission channel. By forming two or more electrode portions and two or more capacitance couplers on the IC card 100 and the card reader / writer 200, respectively, data of a plurality of channels can be transmitted in parallel. As a result, high-speed data transmission can be realized.

  Communication between the IC card 100 and the card reader / writer 200 is performed by an encrypted signal as necessary. Further, data input / output to / from the IC card 100 is subjected to predetermined processing by the processing circuit 230 and then input / output to / from the computer 250, and if necessary, a network such as the Internet. Is available in

  In general, the communication distance between the card reader / writer 200 and the IC card differs depending on the communication method, that is, the size of the IC card transmission / reception means (antenna). In the present embodiment, a contact-type non-contact type IC card is assumed as the IC card 100, and the communication distance between the card reader / writer 200 and the IC card is about 0.2 mm. The card reader / writer 200 performs a series of processes including detection of the IC card 100, mutual authentication between the IC card 100 and the card reader / writer 200, reading of the IC card 100, and writing (recording) on the IC card 100 approximately 0. It can be done in about 2 seconds.

  In the present embodiment, the processing circuit 230 mounted on the card reader / writer 200 is characterized. That is, a predetermined communication modulation circuit is formed integrally with the processing circuit 121 mounted on the IC card 100 described above. A specific circuit configuration of the processing circuit 230 will be further described later.

The system configuration of the card communication system according to the present embodiment has been described above.
Next, a data transmission method between the IC card 100 and the card reader / writer 200 will be described, and the processing circuit 121 mounted on the unexplained IC card 100 and the processing circuit 230 mounted on the card reader / writer 200. explain.

(C) Communication method In this embodiment, a BPSK modulation method and a Manchester encoding method are adopted as modulation methods used for data transmission between the IC card 100 and the card reader / writer 200. First, the reason for adopting these modulation methods will be described.

In the present embodiment, as described above, the IC card 100 and the card reader / writer 200 are each provided with an electrode portion to constitute a capacitive coupler, thereby performing data transmission. When examining what modulation method is suitable for a transmission system using a capacitive coupler, the characteristics of the capacitive coupler are considered as follows.
(1) DC cannot be transmitted.
(2) There is a band from 400 to 500 MHz.
(3) Transmission characteristics vary depending on the coupling state.
(4) It is easy to parallelize several channels. (5) There is little crosstalk.

The advantages of the capacitive coupler are as follows.
(1) A non-contact transmission method. For this reason, it is possible to realize high-speed data transmission of a contactless non-contact method.
(2) Parallelization is easy. This eliminates the need for clock recovery because the clock can be sent to another channel.

On the other hand, the disadvantages of the capacitive coupler are as follows.
(1) DC cannot be sent. For this reason, a DC-free modulation method is necessary.
(2) The bandwidth varies. For this reason, it is necessary to place the clock frequency at the center of the band.

Therefore, it is most preferable to adopt a method that compensates for the disadvantages of the capacitive coupler and takes advantage of the advantages. From this point of view, the selection criteria for the modulation method in the present embodiment are as follows.
(1) Simple circuit and low power consumption (2) High-speed transmission possible (3) DC-free (4) Clock (carrier) in band (5) Strong against characteristic fluctuation

  Hereinafter, as a comparison of modulation schemes, a Manchester coding scheme, a QPSK (Quadrature Phase Shift Keying) modulation scheme, and a BPSK modulation scheme will be discussed. The QPSK modulation method is one of modulation methods for converting a digital signal into an analog signal. By assigning one value to each of four different phases in the converted wave, four values (2 Bit) data can be transmitted and received. This is a modulation method used for digital satellite broadcasting and cable modems.

The Manchester encoding method, QPSK modulation method, or BPSK modulation method satisfies the above (1) to (5).
The Manchester encoding method does not require an analog modulation / demodulation circuit (EOR), but it is not flexible because the carrier and the data clock must be matched.
The QPSK modulation method or the BPSK modulation method requires an analog modulation / demodulation circuit (MIXER), but the data clock and the carrier do not need to match.
• QPSK can be transmitted at high speed, but phase management is troublesome.
-The DC-free modulation method for storage has a clock outside the band necessary for transmission.
-In multi-value transmission such as PR (Partial Response) and QAM (Quadrature Amplitude Modulation), the gain of the amplifier is variably controlled so that the output signal level is constant even if the input signal level changes. Control) circuit is required.

  From the above, the Manchester encoding method or the BPSK modulation method in which the DC is free, the carrier is at the center of the transmission band, the modulation / demodulation is simple and the AGC circuit is unnecessary is desirable. Hereinafter, these modulation methods will be described.

(BPSK modulation method)
The BPSK modulation method is the simplest phase modulation method, in which the carrier phase is assigned to 0 and the phase opposite to the carrier (phase shifted by 180 degrees) is assigned to 1. The receiving side detects whether the transmitted signal is 0 or 1 by detecting the phase shift from this carrier. In the BPSK modulation system, the amplitude of the modulation output is constant, so that an amplifier with high power efficiency can be used, which is advantageous in terms of power consumption, and the modulation system is simple and not very efficient. It is characterized by being relatively resistant to communication errors. On the other hand, the BPSK modulation method has a drawback that the output spectrum is widened because the phase changes rapidly.

  In the Internet connection service using satellite digital communication, this BPSK modulation method is adopted as a modulation method.

  This BPSK modulation method is the simplest example of digital modulation. In the modulation technique currently used, a plurality of modulation methods are used in combination so that a large amount of information can be encoded simultaneously in one code (called a symbol). It is common to do.

  Hereinafter, a circuit (hereinafter referred to as a BPSK circuit) for realizing communication using the BPSK modulation method between the IC card 100 and the card reader / writer 200 will be described. FIG. 7 is an explanatory diagram showing a configuration example of the BPSK circuit according to the present embodiment. FIG. 8 is an explanatory diagram showing waveforms of (a) transmission data, (b) band-limited signal, and (c) transmission signal in the BPSK circuit 300. FIG. 9A is an explanatory diagram showing frequency characteristics of (a) the band limited signal and (b) the transmission signal in the BPSK circuit 300. FIG. FIG. 9B is an explanatory diagram showing frequency characteristics of (c) noise added signal and (d) equalized signal in the BPSK circuit.

  In FIG. 8, the horizontal axis (X axis): Normalized Time (data rate / clock period To normalized to 1), the vertical axis (Y axis): Amplitude [V] (linear display amplitude) It is. 9A and 9B, the horizontal axis (X axis): Normalized Frequency (frequency obtained by normalizing the reciprocal 1 / To of the data rate clock period To to 1), and the vertical axis (Y axis): Amplitude [ dB] (logarithmic display amplitude).

(BPSK circuit 300)
As shown in FIG. 7, the BPSK circuit 300 includes a band limiting filter 310, a multiplier 320, a channel 340, a multiplier 350, a band limiting filter 360, a binarization unit 370, 2 A valueizing unit 380 and a data flip-flop (DFF) 390 are provided. Although the adder 330 does not exist in an actual circuit, it is added for explaining the operation by simulation, and an actual transmission channel is simulated by the channel 340 and the noise adder 330.

  As described above, the adder 330 does not exist in an actual circuit, but is added for explaining the operation by simulation, and is a means for superposing an AWGN (Additive White Gaussian Noise) on a transmission signal. The AWGN is sent to the adder 330 from a digital modulation signal generator (AWGN generator) that can output necessary AWGN in real time. The adder 330 is used to simulate an actual transmission channel with the channel 340 and the noise adder 330.

The operation of the BPSK circuit 300 having the above configuration will be described.
Here, a case where a signal flows from the card reader / writer 200 to the IC card 100, that is, a data writing operation or power supply operation to the IC card 100 will be described.

  The transmission data is filtered by the band limiting filter 310 and then modulated by a multiplier 320 into a band in which data transmission is possible by a modulation sine wave (clock). The transmission data modulated to a band where data transmission is possible is sent to the subsequent stage as a transmission signal. FIG. 8A shows the waveform of the transmission data, FIG. 8B shows the waveform of the band limited signal, and FIG. 8C shows the waveform of the transmission signal. FIG. 9A (a) shows the frequency characteristic of the band limited signal, and FIG. 9A (b) shows the frequency characteristic of the transmission signal.

  In an actual transmission system, the transmission signal is sent to the channel 340. FIG. 9B (c) shows the frequency characteristics of the noise-added signal after adding noise (AWGN) in the adder 330 for simulating an actual transmission channel. The channel 340 is configured by a capacitive coupler including a capacitor element provided in the above-described IC card 100 and a capacitor element provided in the card reader / writer 200. When a plurality of capacitive couplers are provided, it is possible to select an optimum channel for data transmission.

  The modulation sine wave (clock) is transmitted to the receiving side via a channel different from the data transmission. The received signal is demodulated in the multiplier 350 by a modulating sine wave (clock). The demodulated signal is filtered by the band limiting filter 360 and sent to the subsequent stage as an equalized signal. FIG. 9B (d) shows the frequency characteristics of the equalized signal. The equalized signal is binarized by the binarization unit 370 and converted into data. The modulation sine wave (clock) is converted into data by the binarization unit 380. The binarized equalized signal is input to the data terminal (D) of the data flip-flop (DFF) 390, and the binarized modulation sine wave (clock) is input to the data flip-flop (DFF) 390. It is input to the clock terminal (CK). In the data flip-flop (DFF) 390, the data (D) is latched by the clock (CK), and the received data is output as output data (Q).

  The results of measuring the frequency characteristics of the capacitive coupler with a network analyzer are shown in FIGS. 10A to 10D. 10A to 10D show that the distances (spacing) between electrodes constituting the capacitive coupler are (a) 0.1 mm, (b) 0.5 mm, (c) 1.0 mm, (d). The case of 2.0 mm is shown. When the distance (spacing) between the electrodes constituting the capacitive coupler is increased to (a) 0.1 mm- (b) 0.5 mm- (c) 1.0 mm- (d) 2.0 mm , The transmittable band shifts to a higher frequency, and the frequency with the least loss changes from (a) 200 MHz- (b) 400 MHz- (c) 550 MHz- (d) 700 MHz. As described above, since the band in which the capacitive coupler can be transmitted varies depending on the use condition such as spacing, the carrier system or the clock frequency is likely to change the characteristics, and the entire transmission system becomes unstable. In order to avoid this, it is necessary to place the carrier or clock frequency almost at the center of the transmittable band.

  As shown in FIGS. 9A and 9B, when the carrier or clock frequency is almost at the center of the band in which communication (data transmission) is possible, the entire band in which data transmission is possible is effectively used for data transmission. be able to. In the BPSK modulation method, high-speed communication (high-speed data transmission) is possible in this way.

The BPSK modulation method has been described above.
Next, the Manchester encoding method will be described.

(Manchester encoding method)
The 10Base-type Manchester encoding method takes a complement in the first half of the bit interval (1 for 0, 0 for 1), and performs modulation such that the second half is unchanged, and transmits the data and the clock component together. In this case, at the peak time (1 and 0 are continuous), a pulse wave according to the bit rate (10 MHz if 10 Mbps) flows on the cable as it is. In 100Base-FX and 1000Base-X, NRZI (Non Return to Zero Inverted) that changes a binary signal level in a state of “1” is used. Since “1, 1” changes for one clock, the frequency component at the peak time (continuous “1”) is half the baud rate (62.5 MHz at 125 Mbps). In this modulation method, when “0” continues for a long time, the signal does not change and the clock cannot be detected. Therefore, 8B10B encoding is performed to select a code in which “1” appears moderately from 10-bit codes. Yes. For 100Base-TX signal transmission, three levels of “+, 0, −” are used instead of simple high and low binary values, and MLT-3 (Multi Level Transmission-3 level) in which the signal level is changed by one step with “1”. ) Is used. In this case, since the transition is made for 1 clock with 4 bits of “1, 1, 1, 1”, the substantial frequency component on the cable is suppressed to 31.25 MHz of ¼. Here too, 4B5B encoding, which represents 4 bits in 5 bits, is performed so that the clock transitions appropriately.

  Hereinafter, a circuit (hereinafter referred to as a “Manchester circuit”) for realizing communication using the Manchester encoding method between the IC card 100 and the card reader / writer 200 will be described. FIG. 11 is an explanatory diagram of a configuration example of the Manchester circuit according to the present embodiment. FIG. 12 is an explanatory diagram illustrating waveforms of (a) transmission data, (b) a Manchester signal, and (c) a transmission signal in the Manchester circuit. FIG. 13A is an explanatory diagram showing the frequency characteristics of (a) the Manchester signal and (b) the transmission signal in the Manchester circuit 400. FIG. 13B is an explanatory diagram showing frequency characteristics of the (c) noise added signal and (d) the equalized signal in the Manchester circuit 400.

  In FIG. 12, the horizontal axis (X axis): Normalized Time (data rate / clock period To normalized to 1), the vertical axis (Y axis): Amplitude [V] (linear display amplitude) It is. 13A and 13B, the horizontal axis (X axis): Normalized Frequency (the frequency obtained by normalizing the reciprocal 1 / To of the data rate clock period To to 1), and the vertical axis (Y axis): Amplitude [ dB] (logarithmic display amplitude).

(Manchester circuit 400)
As shown in FIG. 11, the Manchester circuit 400 includes an exclusive OR circuit (XOR) 410, a band limiting filter 420, a channel (440), a band limiting filter 450, a binarization unit 460, A binarization unit 470 and a data flip-flop (DFF) 480 are provided. Although the adder 430 does not exist in an actual circuit, it is added for explaining the operation by simulation, and an actual transmission channel is simulated by the channel 440 and the noise adder 430.

  The exclusive OR circuit (XOR) 410 is used to generate a Manchester signal from transmission data using the data clock CLK.

  The band limiting filter 420, the adder 430, the band limiting filter 420, the adder 430, the channel 440, the band limiting filter 450, the binarizing unit 460, the binarizing unit 470, and the data flip-flop (the other components) DFF) 480 is a component of the above-described BPSK circuit 300, and includes a band limiting filter 310, an adder 330, a channel 340, a band limiting filter 360, a binarizing unit 370, a binarizing unit 380, and a data flip-flop. Substantially the same as DFF 390 can be used.

The operation of the Manchester circuit 400 having the above configuration will be described.
Here, a case where a signal flows from the card reader / writer 200 to the IC card 100, that is, a data writing operation or power supply operation to the IC card 100 will be described.

  Transmission data is modulated by an exclusive OR circuit (XOR) 410 into a Manchester signal having a band in which data transmission is possible by a modulation sine wave (clock). A Manchester signal in a band in which data transmission is possible is filtered by the band limiting filter 420 and sent to the subsequent stage as a transmission signal. 12A shows the waveform of the transmission data, FIG. 12B shows the waveform of the Manchester signal, and FIG. 12C shows the waveform of the transmission signal. FIG. 13A (a) shows the frequency characteristic of the Manchester signal, and FIG. 13A (b) shows the frequency characteristic of the transmission signal.

  In an actual transmission system, the transmission signal is sent to the channel 440. FIG. 13B (c) shows the frequency characteristics of the noise-added signal after adding noise (AWGN) in the adder 430 for simulating an actual transmission channel. The channel 440 is configured by a capacitive coupler configured by a capacitor element provided in the above-described IC card 100 and a capacitor element provided in the card reader / writer 200. When a plurality of capacitive couplers are provided, it is possible to select an optimum channel for data transmission.

  The received signal is filtered by the band limiting filter 450 and sent to the subsequent stage as an equalized signal. FIG. 13B (d) shows the frequency characteristics of the equalized signal. The equalized signal is binarized by the binarization unit 460 and converted into data. On the other hand, the modulation sine wave (clock) is transmitted to the receiving side via a channel different from the data transmission. The modulation sine wave (clock) is converted into data by the binarization unit 470. The binarized equalized signal is input to the data terminal (D) of the data flip-flop (DFF) 480, and the binarized modulation sine wave (clock) is input to the data flip-flop (DFF) 480. It is input to the clock terminal (CK). In the data flip-flop (DFF) 480, the data (D) is latched by the clock (CK), and the received data is output as output data (Q).

  As shown in FIGS. 13A and 13B, when the carrier or clock frequency is almost at the center of the band in which communication (data transmission) is possible, the entire band in which data transmission is possible is effectively used for data transmission. be able to. In the Manchester encoding method, high-speed communication (high-speed data transmission) is possible in this way.

The BPSK modulation method and the Manchester encoding method have been described above.
The BPSK modulation method and the Manchester encoding method are compared.

● BPSK modulation method Even when data is transmitted using the entire band of the channel, it is possible to achieve both data rate and stability without the clock being out of band. Also, since it is resistant to characteristic fluctuations, it can be used in various situations, such as using an IC card as a storage (removable storage medium) that can handle a large-capacity memory as described above. In particular, by adopting the BPSK modulation method, there is an effect that any carrier can be used.

● Manchester encoding method Similar to the BPSK modulation method, even when transmission is performed using the entire band of the channel, it is possible to achieve both a data rate and stability without the clock being out of the band. Also, since it is resistant to characteristic fluctuations, it can be used in various situations, such as using an IC card as a storage (removable storage medium) that can handle a large-capacity memory as described above. In particular, by adopting the Manchester encoding method as a modulation method, there is an effect that an IC can be realized only by a digital CMOS (Complementary Metal Oxide Semiconductor).

(Effect of this embodiment)
As described above, according to the card communication system, the IC card, and the communication device according to the present embodiment, the following excellent effects can be obtained.

(1) High speed transmission is possible.
Since the carrier or clock frequency is almost at the center of the band in which data transmission is possible, all of the band in which data transmission is possible can be effectively used for data transmission. Therefore, high-speed data transmission is possible. By enabling high-speed data transmission, even a conventional contactless card usage mode can be used to give stress to the user. Furthermore, as a new use form of the non-contact type card, the IC card can function as a storage (removable storage medium) that can handle a large capacity memory.

(2) Strong against characteristic fluctuations.
When trying to transmit a plurality of channels in parallel, there is a method of performing clock recovery using a PLL (Phase Locked Loop) without sending a clock.
A PLL (Phase Locked Loop) generally has one controllable oscillator, and the phase difference of the oscillator so as to maintain a constant relationship with the phase of a reference signal. Is detected and feedback controlled. Conventionally, the PLL has been used for demodulating an angle modulation signal, various synchronization circuits, a frequency synthesizer, and the like. Recently, it is also frequently used to generate internal clocks of various logic ICs including a microprocessor, and as the clock frequency becomes higher, the jitter characteristics may become a problem depending on how it is made.
Thus, when trying to regenerate the clock with the PLL, the circuit interferes and becomes unstable. In this regard, in the present invention, a plurality of sets of capacitor elements of the contactless card and the card authentication device are provided, and a plurality of sets of the capacitive couplers are used, thereby transmitting data of a plurality of channels in parallel. Therefore, stability can be maintained without such problems.

(3) The circuit configuration is simple.
By adopting the BPSK modulation method or the Manchester coding method as the modulation method, the circuit configuration is simplified. In particular, it is extremely effective to employ a modulation method that can simplify the circuit configuration in an IC card that is required to be thin and small.

  The preferred embodiments of the communication system, IC card, and communication apparatus according to the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be obvious to those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

  For example, in the above embodiment, the card reader / writer 200 that reads and writes the IC card 100 is described as an example of the communication device of the present invention, but the present invention is not limited to this. The communication apparatus according to the present invention may perform only one of reading and writing of the IC card. Also, the power supply to the IC card may or may not have the function.

  In the above-described embodiment, the area of the electrode unit 210 of the card reader / writer 200 has been described by taking specific numerical values as examples. However, the present invention is not limited to these and any form is possible. Can be adopted.

  As described above, according to the present invention, since the carrier or clock frequency is almost at the center of the band where communication (data transmission) is possible, all the bands where data transmission is possible are effectively used for data transmission. can do. Thus, the present invention enables high-speed communication (high-speed data transmission). In addition, by enabling high-speed data transmission, it can be used without stressing the user even in conventional general IC card usage forms such as use in electronic commerce and identity certificates. Become. Furthermore, according to the present invention, as a new usage form of the IC card, the IC card can be used as a storage (removable storage medium) capable of supporting a large capacity memory.

  INDUSTRIAL APPLICABILITY The present invention can be used in a communication system, and in particular, a contactless non-contact type in which an IC (Integrated Circuit) is embedded and information is held therein and communication can be performed without contacting a communication device. The present invention can be used for an IC card of a type (hereinafter simply referred to as an IC card), a communication device that communicates with the IC card, and a communication system that includes these IC card and communication device as components.

It is explanatory drawing which shows the structure of a card communication system. 1 is an explanatory diagram showing a configuration of an IC card 100. FIG. 2 is an explanatory diagram showing a configuration of an IC module 120. FIG. 2 is an explanatory diagram showing a state in which a card reader / writer 200 is connected to a computer 250. FIG. 4 is a plan view showing a state where an electrode part 220 is formed in a communication part 210. FIG. It is explanatory drawing which shows the state in which the card | curd 100 was held over the communication part 210. FIG. FIG. 3 is an explanatory diagram showing a configuration example of a BPSK circuit 300. FIG. 7 is an explanatory diagram showing waveforms of (a) transmission data, (b) a band limited signal, and (c) a transmission signal in the BPSK circuit 300. 4 is an explanatory diagram showing frequency characteristics of (a) a band limited signal and (b) a transmission signal in the BPSK circuit 300. FIG. FIG. 6 is an explanatory diagram showing frequency characteristics of (c) noise added signal and (d) equalized signal in the BPSK circuit 300. It is explanatory drawing which shows the result of having measured the frequency characteristic of the electrostatic capacity type coupler by the network analyzer in case the distance between the electrodes which comprise an electrostatic capacity type coupler is (a) 0.1 mm. It is explanatory drawing which shows the result of having measured the frequency characteristic of the electrostatic capacity type coupler by the network analyzer in case the distance between the electrodes which comprise an electrostatic capacity type coupler is (b) 0.5 mm. It is explanatory drawing which shows the result of having measured the frequency characteristic of the electrostatic capacity type coupler by the network analyzer in case the distance between the electrodes which comprise an electrostatic capacity type coupler is (c) 1.0 mm. It is explanatory drawing which shows the result of having measured the frequency characteristic of the electrostatic capacity type coupler by the network analyzer in case the distance between the electrodes which comprise an electrostatic capacity type coupler is (d) 2.0mm. FIG. 6 is an explanatory diagram showing a configuration example of a Manchester circuit 400. FIG. 6 is an explanatory diagram showing waveforms of (a) transmission data, (b) a Manchester signal, and (c) a transmission signal in the Manchester circuit 400. It is explanatory drawing which shows the frequency characteristic of (a) Manchester signal and (b) transmission signal in the Manchester circuit 400. FIG. It is explanatory drawing which shows the frequency characteristic of (c) noise addition signal and (d) equalized signal in the Manchester circuit 400.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 IC card 110 Electrode part 120 IC module 121 Processing circuit 122 Memory 200 Card reader / writer 210 Communication part 220 Electrode part 230 Processing circuit 250 Computer 270 Capacitance coupler 300 BPSK circuit 310 Band limiting filter 320 Multiplier 330 Adder 340 Channel 350 Multiplier 360 Band Limit Filter 370 Binary Unit 380 Binary Unit 390 Data Flip-Flop (DFF)
400 Manchester circuit 410 Exclusive OR circuit 420 Band-limiting filter 430 Adder 440 Channel 450 Band-limiting filter 460 Binary unit 470 Binary unit 480 Data flip-flop (DFF)

Claims (20)

A communication system comprising a contactless contactless information storage medium and a communication device for communicating with the information storage medium,
On the surface of the information storage medium, there is formed a first electrode part for forming a capacitive coupler serving as a communication path with the communication device,
In the communication device, a second electrode unit that forms the capacitive coupler integrally with the first electrode unit is formed in a communication unit to which the information storage medium is closely attached,
A communication system using the capacitive coupler as a communication path is a communication system in which a carrier or a clock frequency is assigned to substantially the center of a band in which data transmission is possible in the capacitive coupler. A plurality of the first electrode portions are formed on the surface of the information storage medium, and a plurality of the second electrode portions are formed in the communication portion of the communication device,
The communication system according to claim 1, wherein data of a plurality of channels are transmitted in parallel. The communication system according to claim 2, wherein a clock for demodulating the data is transmitted through a channel different from that of the data. The communication system according to claim 1, wherein a communication system using the capacitive coupler as a communication path is a BPSK modulation system. The communication system according to claim 1, wherein a communication system using the capacitive coupler as a communication path is a Manchester encoding system. The communication system according to claim 1, wherein the communication device transmits and receives data to and from the information storage medium and supplies power to the information storage medium. The communication system according to claim 1, wherein the second electrode unit has an area of approximately 20 mm square. The communication method with the communication device is a contactless non-contact information storage medium,
A first electrode portion for forming a capacitive coupler that serves as a communication path with the communication device is formed on the surface,
In the communication device, a second electrode unit that forms the capacitive coupler integrally with the first electrode unit is formed in a communication unit to which the information storage medium is closely attached,
An information storage medium characterized in that the communication system using the capacitive coupler as a communication path is a communication system in which a carrier or a clock frequency is assigned to substantially the center of a band in which data transmission is possible in the capacitive coupler. . A plurality of the first electrode portions are formed on a surface, and a plurality of the second electrode portions are formed in a communication portion of the communication device, and data of a plurality of channels are transmitted in parallel. 8. An information storage medium according to 8. The information storage medium according to claim 9, wherein a clock for demodulating the data is transmitted through a channel different from that of the data. The information storage medium according to claim 8, wherein a communication system using the capacitive coupler as a communication path is a BPSK modulation system. The information storage medium according to claim 8, wherein a communication system using the capacitive coupler as a communication path is a Manchester encoding system. 9. The information storage medium according to claim 8, wherein data is transmitted to and received from the communication device, and power is supplied from the communication device. A communication device for communicating with an information storage medium having a contact type non-contact type,
On the surface of the information storage medium, there is formed a first electrode part for forming a capacitive coupler serving as a communication path with the communication device,
A second electrode part that is integrated with the first electrode part to form the capacitive coupler is formed in the communication part to which the information storage medium is closely attached,
The communication apparatus using the capacitive coupler as a communication path is a communication system in which a carrier or a clock frequency is assigned to almost the center of a band capable of data transmission in the capacitive coupler. A plurality of the second electrode portions are formed in the communication unit, and a plurality of the first electrode portions are formed on the surface of the information storage medium, and data of a plurality of channels are transmitted in parallel. The communication apparatus according to claim 14. The communication apparatus according to claim 15, wherein a clock for demodulating the data is transmitted through a channel different from that of the data. The communication apparatus according to claim 14, wherein a communication system using the capacitive coupler as a communication path is a BPSK modulation system. The communication apparatus according to claim 14, wherein a communication system using the capacitive coupler as a communication path is a Manchester encoding system. The communication apparatus according to claim 14, wherein data is transmitted to and received from the information storage medium, and power is supplied to the information storage medium. The communication device according to claim 14, wherein the second electrode unit has an area of approximately 20 mm square.

Images