JP2000011106A - Ic card - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the error of communication accompanying the change of operating currents in an IC card in electromagnetic inductive coupling in the load modulation system of a non-contact IC card system. SOLUTION: A communication controlling part and a memory controlling part are controlled from a processing part so that the non-modulation period of a time for 2 bits or more expressed by a bit rate can be set between the start or end of a signal for permitting a reading operation, or the end of a signal for permitting a writing operation, or a deleting operation which are given from a memory controlling part to a memory part, and the start of the modulation of information for an IC card processor. Thus, a data error can be ignored by detecting this non-modulation period at the IC card processor side, and a point of time (start bit) when a modulation signal from an IC card is started can be exactly recognized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a control circuit, a memory, a modulation / demodulation circuit, and an antenna connected to the modulation / demodulation circuit on a card, which are provided on a card, and perform non-contact information communication and power transmission by electromagnetic induction coupling. The present invention relates to a non-contact type IC card to be realized or the like.

[0002]

2. Description of the Related Art Information communication and I
As an IC card that realizes power transmission to a C card, and particularly relates to an IC card that simultaneously transmits information and power using the same coil, see, for example, JP-A-6-9
No. 6300 “Non-contact IC card and reader / writer by electromagnetic induction coupling” is available.

According to the above publication, an IC card comprises a coil for transmitting information and power, a modulation / demodulation circuit for information connected to the coil, and a power supply circuit for extracting power to obtain power for operating the IC card. It comprises a processing circuit for executing processing in accordance with information from the IC card processing device and a memory for storing information. The transfer of information from the IC card processing device to the IC card is realized by amplitude modulation of a carrier wave. The transfer of information from the card to the IC card processing device is realized by so-called load modulation that changes the load equivalently connected in parallel to the communication coil of the IC card.

The above-mentioned IC card processing device operates as follows. When transmitting information to an IC card, amplitude modulation of a carrier is realized by changing a voltage or a current that drives a coil that performs information communication and power transmission in accordance with the information to be transmitted to the IC card. When receiving information transmitted from an IC card,
Information reception is realized by detecting and demodulating a change in the current flowing through the coil, which changes in response to the load modulation on the C card side.

[0005] The operation of the IC card is as follows. The power required for the operation of the IC card is obtained by extracting and rectifying the carrier wave sent from the IC card processing device, and then stabilizing it. Information transmitted from the IC card processing device is received by demodulating an amplitude-modulated carrier. When transmitting information to the IC card processing device, load modulation is performed using a resistor equivalently connected in parallel to the coil in accordance with the information to be transmitted.

[0006]

As described above, information communication and power transmission are realized using the same coil, and
An IC card that applies load modulation as a method of transmitting information from a C card has the following problems.

[0007] A change in current consumption when each means (circuit) in the IC card operates appears as a change in the current of the communication coil, and equivalently, the same effect as a load change occurs. The IC card processing device receiving this detects the load fluctuation as a modulation signal, and a phenomenon occurs in which correct communication is not performed as erroneous information. In particular, at the time of a read, write, or erase operation of the memory, the current consumption increases, and the equivalent load fluctuation is also detected to be large.

If such a phenomenon occurs when load modulation corresponding to information to be transmitted is started, in other words, immediately before information is transmitted, the frequency of reception errors on the IC card processing device side increases.

[0009]

According to the present invention, in an IC card, a read operation from a memory for storing the information, a read operation, a write operation, an erase operation, and an erase operation are terminated. A non-modulation period of at least two bits represented by the information bit rate is provided before the modulation of the information for the processing device is started. The IC card processing device detects this non-modulation period so that the point in time at which the modulation signal from the IC card is started can be accurately recognized.

[0010]

FIG. 1 shows a non-contact IC according to the present invention.
1 shows an embodiment of a card. The IC card 1 includes an antenna unit 101 for transmitting and receiving a signal, a demodulation unit 102 for demodulating a received signal to obtain information, a modulation unit 103 for modulating information to be transmitted, and delivering the received information to a processing unit 105 and a processing unit 105. A communication control unit 104 for transferring information from the control unit 103 to the modulation unit 103, a processing unit 105 for executing processing according to the received information, and a processing unit 10
5, a memory control section 106 for realizing reading, writing, and erasing, a memory section 107 for storing information, and a power supply section 108 for rectifying a carrier wave and operating as described above inside the IC card. I have.

Although not shown, the antenna unit 101 includes:
It includes an antenna coil, a means for extracting a carrier wave, a means for extracting modulated received information, and a resistor for implementing load modulation necessary for transmitting information. Normally, a rewritable nonvolatile semiconductor memory element is used for the memory unit 107.

In order to make the description easy to understand, the IC card processing device 2 constituting the system will be described. IC
The card processing device does not operate independently, but is used by being connected to a device (for example, a personal computer) that externally controls from a higher level.

The IC card processing device 2 includes an antenna unit 201 for transmitting / receiving information to / from an IC card, a demodulation unit 202 for demodulating a received signal to obtain information, a modulation unit 203 for modulating information to be transmitted, A communication control unit 204 that transfers information to the processing unit 205 and transfers information from the processing unit 205 to the modulation unit 203, a processing unit 205 that performs processing in accordance with received information, and realizes communication with an external control device. And a communication control unit 206 that performs the communication. A memory unit is added as needed.

Although not shown, the antenna unit 201 includes:
Information from the antenna coil, driving means for driving the antenna coil by an output from the modulation section 203, current detection means for detecting a change in the current flowing through the antenna coil which changes due to load modulation of the IC card 1, and information from the current detection means. Means for extracting are included. This detection signal is equivalently an amplitude modulation signal.

The basic communication operation will be described. I
Amplitude modulation, phase modulation, or load modulation is used as a modulation method between the C card 1 and the IC card processing device 2, but the present invention is mainly applied to a case of transmitting data to the IC card processing device. It is applicable to the non-contact communication by the electromagnetic induction coupling using the load modulation method. Further, data modulation is performed to adapt the information to the above load modulation scheme. In the present application, a method of modulating an NRZ code into a modified mirror code is used. This modified mirror code has a feature that, when normal communication is performed, there is no unmodulated portion of 2 bits or more indicated by the communication bit rate between the start bit and the stop bit. .

FIG. 3 shows a signal state of communication between the IC card 1 and the IC card processing device 2. First, IC
A case where information is transmitted from the card processing device 2 to the IC card 1 will be described. FIG. 3A illustrates information of the NRZ code passed from the communication control unit 204 of the IC card processing device 2 to the modulation unit 202. Usually non-contact I
The start-stop synchronization method is adopted for communication of the C card system. First, a start bit is output, followed by a data portion (8 bits in this embodiment), after which a parity bit is added as required, and finally a stop bit is output. (2) of FIG. 3 shows a modified mirror code for the information to be transmitted modulated in the modulation section 202. FIG. 3C shows the IC card 1
2 shows a reception signal at the antenna unit 101 of FIG. The carrier is amplitude-modulated according to the modified mirror code. The IC card 1 extracts information from this signal to obtain a signal shown in (4) of FIG. This signal is a modified mirror code. This code is demodulated in the demodulation section 103, and the NR shown in (5) of FIG.
Get the Z code.

Next, a case where information is transmitted from the IC card 1 to the IC card processing device 2 will be described. Basically, the form is the same as that of the transmission of the IC card 1 from the IC card processing device 2. Therefore, description will be made with reference to FIG.

FIG. 3A shows NRZ code information passed from the communication control unit 104 of the IC card 1 to the modulation unit 102. First, a start bit is output,
Next, a data portion (8 bits in this embodiment) follows.
Thereafter, a parity bit is added as necessary, and finally a stop bit is output. FIG. 3B shows a modified mirror code for the information to be transmitted, which is modulated by the modulator 102. (3) in FIG.
Indicates a reception signal output from the current detection unit in the antenna unit 201 of the IC card processing device 2. The carrier is amplitude-modulated according to the modified mirror code. Actually, the modulation unit 103 of the IC card 1
, Load modulation is performed using the resistance of the antenna unit 101 for load modulation. The IC card processing device 2 extracts information from this signal to obtain a signal shown in (4) of FIG. This signal is a modified mirror code. This code is demodulated in the demodulation unit 203 to obtain the NRZ code shown in (5) of FIG.

As described above, in the case of the load modulation method, a change in the current flowing through the antenna coil causes a phenomenon equivalent to the load modulation. This phenomenon is a major cause of information communication errors. In addition, the above IC card 1
, The current consumption increases when reading, writing, or erasing is performed. In particular, the current consumption greatly changes at the start and end of reading.

The problem of non-contact communication by electromagnetic inductive coupling using a load modulation method will be described with reference to FIG. A problem occurs when information is transmitted from the IC card 1 to the IC card processing device 2.

FIG. 4A shows the modulation section 10 of the IC card 1.
3 is an NRZ code corresponding to the information to be communicated. FIG. 4B shows a modified mirror code obtained by data-modulating the NRZ code output from the modulation unit 103 of the IC card 1. FIG. 4 (3) shows an IC
The signal received by the antenna unit 201 of the card processing device 2 is a signal modulated by the modified mirror code extracted by the current detection unit in the antenna unit 201 in FIG. (5) in FIG. 4 is an NRZ code obtained by demodulating the modified mirror code extracted by the current detection means in the antenna unit 201 in the demodulation unit 203. This NRZ code becomes information transmitted from the IC card 1. (6) of FIG. 4 is a signal that permits reading of information from the memory unit 107 included in the IC card 1, and a high level indicates that reading is permitted.

Here, in the case of a normal semiconductor memory, a transition occurs at a portion where a signal permitting reading of information from the memory portion 107 changes (a rising portion in FIG. 4 or a falling portion not particularly shown). Consumes current. When such a condition occurs, a current that is not allowed in the power supply flows through the antenna coil, causing the same condition as the load modulation. This is detected as data of one bit or more on the IC card processing device 2 side, and appears as a communication error.

In particular, if the above-mentioned problem occurs within 1 bit indicated by the bit rate before the start bit of the originally communicated information, as shown by the dotted line frame in FIG. As a result, the generated data error cannot be distinguished from the original information, and the communication error cannot be deleted. In this example, the start bit appears before the original information, and the start bit of the original information is recognized as information of “0”.

FIG. 5 is a diagram for solving the problem that the data error and the original information cannot be identified.
5 shows a timing chart of a communication state realized by the present invention. In this figure, the meanings of the signals (1) to (6) are the same as those of (1) to (6) in FIG.

The present invention is caused by a transiently consumed current at a portion where a signal permitting reading of information from the memory portion 107 changes (a rising portion in FIG. 5 or a falling portion not particularly shown). The part which appears as a communication error due to the same state as the load modulation is controlled so that the above problem does not occur within a time period of less than two bits indicated by the bit rate before the start bit of the originally communicated information.

If there is a non-modulation period of 2 bits or more indicated by the bit rate, the IC card processing device 2 can recognize the generated data error and delete or correct it. The reason is that the modified mirror code has a communication bit rate of 2 between the start bit and the stop bit during normal communication.
This is because there is a feature that no non-modulated portion equal to or more than bits exists.

In the present application, the modified mirror code has been described. However, the code is not particularly limited as long as there is no unmodulated portion of 2 bits or more indicated by the communication bit rate between the start bit and the stop bit. Not something.

More specifically, as shown in FIG. 5, the start or end of a signal for permitting a read operation from the memory control unit 106 to the memory unit 107, or the end or erase operation of a signal for permitting a write operation. Between the communication control unit 104 and the memory so as to provide a non-modulation period of at least two bits represented by the bit rate between the end of the signal for permitting the communication and the start of the modulation of information to the IC card processing device 2. The control unit 106 is controlled from the processing unit 105. By doing so, the IC card processing device 2 can detect the non-modulation period and ignore the data error, and can accurately recognize the time (start bit) at which the modulated signal from the IC card 1 has started. Looks like

The timing for providing the non-modulation period is I
When transmitting information to the IC card processing device 2 while reading information from the memory unit 107 in the C card 1, the start of a signal for permitting a read operation given to the memory unit 107 is targeted, and reading, writing, and erasing are performed. If the operation always ends before information is communicated to the IC card processing device 2, the end of those operations is targeted.

[0030]

According to the present invention, by detecting the non-modulated portion on the card processing device side, an information communication error due to the operation noise of the IC card can be easily and inexpensively eliminated, and a highly reliable load modulation can be achieved. Non-contact communication by electromagnetic induction coupling using the method can be realized. Also, the unit price of the IC card can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an IC card according to one embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of an IC card processing device according to one embodiment of the present invention.

FIG. 3 is a timing chart of communication between the IC card and the IC card processing device according to the present invention.

FIG. 4 is a timing chart showing a problem of a non-contact communication method using a load modulation method.

FIG. 5 is a timing chart of a non-contact communication method using a load modulation method according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... IC card, 101 ... antenna part, 102 ... reception / demodulation part, 103 ... modulation part, 104 ... communication control part, 105 ... processing part, 106 ... memory control part, 107 ... memory part, 10
Reference numeral 8: memory unit, 109: power supply unit 2: IC card processing unit, 201: antenna unit, 202: demodulation unit, 203: modulation unit, 204: communication control unit, 205: processing unit, 206 ...
Communication control unit.

Continuing on the front page (72) Inventor Kimiaki Ando 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (72) Inventor Shinji Ikezawa 1 Horiyamashita, Hadano-shi, Kanagawa F-term within Hitachi Information Technology Co., Ltd. 5B035 AA00 BB09 CA22 CA23 5B058 CA17 KA40 5K012 AB02 AB12 AB18 AB19 AC09 AD02 AE02 AE13 BA03 BA07

Claims (4)

[Claims] At least means for communicating information with an IC card processing device by electromagnetic induction coupling, means for demodulating received information, memory means for storing information,
Processing means for executing predetermined processing according to the information received from the IC card processing device and determining information to be transmitted to the IC card processing device according to the processing result; and means for modulating information to be transmitted to the IC card processing device; , According to the processing of the processing means and the processing result,
An IC having means for performing reading, writing and erasing processing of the memory means, and an antenna for transmitting information and power by electromagnetic induction coupling of the processing means;
In the card, at least two bits represented by the bit rate of the transmission information from the start and / or end of the read operation to the memory means to the start of the modulation of the information to be transmitted to the IC card processing device. IC having a non-modulation period of time
card. 2. At least means for communicating information with an IC card processing device by electromagnetic induction coupling, means for demodulating received information, and memory means for storing information.
Processing means for executing predetermined processing according to the information received from the IC card processing device and determining information to be transmitted to the IC card processing device according to the processing result; and means for modulating information to be transmitted to the IC card processing device; , According to the processing of the processing means and the processing result,
An IC having means for performing reading, writing and erasing processing of the memory means, and an antenna for transmitting information and power by electromagnetic induction coupling of the processing means;
In the card, at least two bits or more indicated by the bit rate of the transmission information between the end of the writing operation or the erasing operation to the memory means and the start of the modulation of the information transmitted to the IC card processing device. An IC card characterized by providing a non-modulation period. 3. The IC card according to claim 1, further comprising means for adjusting the length of the non-modulation period in time units of one bit represented by a bit rate. card. 4. An IC card according to any one of claims 1 to 3, wherein means for communicating information with an IC card processing device by electromagnetic induction coupling, means for demodulating received information, Memory means for storing information; processing means for executing predetermined processing according to the information received from the IC card processing apparatus and determining information to be transmitted to the IC card processing apparatus according to the processing result;
Means for modulating information to be transmitted to the C card processing device, and means for reading, writing, and erasing the memory means in accordance with the processing and processing results of the processing means are incorporated in a one-chip semiconductor integrated circuit. Characteristic IC card.