JPH10261984A - Noncontact ic card system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a stable identification communication by simultaneously using an information communicating means together due to an alternating current magnetic field coupling that uses a modulation wave of a subcarrier of a frequency which is lower than a carrier in accordance with transmission information. SOLUTION: An identifying device 1 and a noncontact IC card 2 undergo subcarrier modulation of transmission information and mutually communicate through carrier communication functioning parts 7a and 7b. The device 1 simultaneously supplies a subcarrier modulation wave to a subcarrier communication functioning part 9a and sends it through an antenna part 10a. The card 2 receives through an antenna part 10b and a subcarrier communication functioning part 9b and sends response through the part 10a. A controlling part 3a of the device 1 compensates effects that are caused by reflected waves due to the existence of other surrounding objects in carrier communication by using response information that is received through the parts 10b and 9a and response information that is acquired through the part 7a together.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises an identification device and a non-contact IC card, and is used in office automation (Office Automation, OA), factory automation (Factory Automation, FA), security, security, and transportation. The present invention relates to a non-contact type IC card system used in, for example, a personal computer.

[0002]

2. Description of the Related Art A communication system using reflection of radio waves receives an interrogator having a data transmission / reception function and a radio wave modulated in accordance with information transmitted from the interrogator, and obtains information by demodulation. A "mobile unit identification device" comprising: a transponder having a function of receiving radio waves emitted from an interrogator, modulating according to individual information, reflecting the information to the interrogator, and transmitting the information.
It has been widely known as (mobile object identification system).

Under the Radio Law, such a mobile object identification system is referred to as “mobile object identification device standard RCR STD-
1, STD-29 ", and the system in this rule consists of an interrogator installed in a fixed station and a transponder used in conjunction with a mobile object such as a vehicle or a conveyed article. Has become. It is also possible to configure a non-contact IC card system in which the responder is a non-contact IC card that can be carried by a person and the interrogator is an identification device.
In this case, the exchange of information between the non-contact IC card and the identification device is performed by a radio wave reflection method.

In a non-contact IC card system of a radio wave reflection type, when an information signal of a non-contact IC card is generally obtained on the identification device side, a configuration as shown in FIG. 4 is used. In the identification device 50, the carrier wave generated by the microwave oscillating unit 51 is modulated based on the transmission data by the microwave modulating unit 52, and transmitted from the transmitting antenna 54 via the splitter 53 to a radio-reflection type non-contact IC card (hereinafter simply referred to as “contactless IC card”). (Referred to as a non-contact IC card) 60.

[0005] Further, a reflected wave from the radio wave reflection type non-contact IC card 60 received by the receiving antenna 55 and a part of a radio wave emitted from the identification device 50 divided by the splitter 53 are added to a mixer 56. A homodyne detection (synchronous detection) is performed to obtain a detection signal, and the signal processing circuit unit 5
Process at step 7. At this time, the level of the detected signal reproduced on the identification device 50 side is the same as that of the identification device 50 and the non-contact IC card 60.
FIG. 5 shows the relationship between the positions. here,
The + side of the vertical axis of the graph shown in FIG.
0 indicates that the information signal to be transmitted and the detection signal reproduced on the identification device side have the same phase, and the-side indicates the opposite phase.

As can be seen from FIG. 5, the homodyne detection includes a sign inversion phenomenon in which the phase of the signal transmitted by the non-contact IC card and the phase of the signal detected by the identification device are inverted by 180 °. There are two problems, namely, a null point phenomenon in which no signal can be obtained.

The sign inversion phenomenon means that information to be transmitted by a non-contact IC card, for example, FIG. 6A is converted into bi-phase coding as shown in FIG. When modulation and retransmission are performed, depending on the positional relationship between the identification device and the non-contact IC card, information obtained by the identification device due to the sign inversion phenomenon becomes completely opposite data. That is, when the sign inversion phenomenon occurs, even if the non-contact IC card transmits data of "1", the identification device reproduces data of "0".

[0008] The null point phenomenon refers to a null point (see points A to E in FIG. 5) in a detection signal in the identification device in the positional relationship between the identification device and the non-contact IC card.
When the identification device and the non-contact IC card have such a positional relationship, data cannot be reproduced on the identification device side. This null point phenomenon occurs when the distance between the identification device and the non-contact IC card is every λ / 4.

As a method for solving these problems, first, as a countermeasure against sign inversion, when a specific process is performed on information to be transmitted by a non-contact IC card, and when a carrier is modulated as an information signal, the processing method is used. A method of modulating a carrier wave based on an information signal obtained by frequency-modulating the subcarrier using information to be transmitted as a subcarrier (FIG. 6)
(See FIG. 6C) and a method of modulating a carrier based on an information signal obtained by amplitude-modulating a subcarrier (see FIG. 6D). In FIGS. 6C and 6D, the transmission data (a) is directly converted into subcarriers. However, in order to extract a timing clock required for communication from a received signal, the transmission data (a) is The same processing may be performed after the bi-phase encoding shown in FIG.

On the other hand, as a measure against null points, a quadrature detection method as shown in FIG. 7 is used. In FIG. 7, the same reference numerals are given to parts corresponding to the respective parts of the non-contact IC card system shown in FIG. 4, and the description thereof will be omitted. In the quadrature detection method shown in FIG.
When the homodyne detection is performed on the side, a part of the carrier output from the splitter 53 is divided into two parts by the power divider 71, and one of them is shifted to the mixer 73, and the other is shifted the phase by 90 ° by the 90 ° phase shifter 74 to the mixer 75. And the reflected wave from the non-contact IC card 60 is divided into two by the power divider 72 into the same phase and the same level.
It is added to each of the mixers 73 and 75.

FIG. 8 shows the detection output levels I and Q of the respective mixers 73 and 75 according to the quadrature detection method with respect to the distance between the identification device 70 and the non-contact IC card 60. Therefore, even when one detection output is at the null point, the other detection output can be obtained. In the signal processing circuit section 76, a method of reproducing the information data by switching the two systems of detection outputs using an analog switch, or a method of judging the phase and level of the detection output and switching the multiplexer to reproduce the information data. A method for performing the method is known.

[0012]

However, in such a non-contact IC card system of the radio wave reflection type, the radio wave emitted from the identification device hits other objects around it.
Of the radio waves reflected from the object, the radio wave arriving at the non-contact IC card and the radio wave arriving directly at the non-contact IC card from the discrimination device have a phase and amplitude relationship that cancel each other. The positional relationship of the contact IC card has a disadvantage that normal communication cannot be performed.
This depends on the surrounding situation, but may occur many times in the communication area.

As a method of avoiding this phenomenon, conventionally, two or more transmitting and receiving antennas are used and arranged so as to be spaced apart from each other so that the communication between the identification device and the non-contact IC card becomes impossible. Is for each antenna
There is a diversity system in which an operating antenna is switched and the distance between the antenna and the non-contact IC card is changed to cancel the canceling phenomenon. However, this diversity system could not completely remove the incommunicable area. In addition, since an interval between the antennas is required, the installation space tends to be large.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object the cancellation of radio waves caused by direct radio waves from an identification device and reflected radio waves from surrounding objects. An object of the present invention is to provide a non-contact IC card system capable of obtaining stable communication with a main object of removing communication failure due to a phenomenon.

[0015]

According to a first aspect of the present invention, a non-contact IC is provided from an identification device.
The transmission of information to the card is performed by transmitting a radio wave obtained by modulating a carrier wave according to the information transmitted by the identification device, and the transmission of information from the non-contact IC card to the identification device is performed by the non-contact IC. The card receives a predetermined radio wave emitted from the identification device, modulates the received radio wave according to the information transmitted by the non-contact IC card, and reflects the modulated radio wave to the identification device. In a non-contact IC card system for exchanging information between each other, the non-contact IC card and the identification device
In each case, a subcarrier modulation unit that modulates a subcarrier of a lower frequency than the carrier according to information to be transmitted, and a carrier modulation unit that modulates the carrier according to a modulation wave output from the subcarrier modulation unit, A subcarrier transmitting / receiving means for transmitting / receiving a modulated wave output from the subcarrier modulating means, and a subcarrier demodulating means for demodulating the modulated wave received by the subcarrier transmitting / receiving means.

According to a second aspect of the present invention, in the non-contact IC card system according to the first aspect, the subcarrier transmitting / receiving means is configured such that the non-contact IC card and the identification device are coupled by an AC magnetic field. It is characterized by transmitting and receiving a modulated wave output from the subcarrier modulation means.

According to a third aspect of the present invention, in the contactless IC card according to the first or second aspect, the subcarrier modulating means changes the amplitude of the subcarrier based on information to be transmitted. Features.

According to a fourth aspect of the present invention, in the contactless IC card according to the first or second aspect, the subcarrier modulating means changes the frequency of the subcarrier based on information to be transmitted. Features.

[0019]

Embodiments according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of a contactless IC card system having a subcarrier communication function according to the present invention. The large configuration includes an identification device 1 having a communication function using a carrier and a subcarrier, a radio wave reflection communication function, and a non-contact IC card 2 having a subcarrier communication function used in the radio wave reflection communication. Become.

The identification device 1 includes a communication control section 3a for controlling communication with the non-contact IC card 2 and a host computer (not shown), a carrier wave oscillating section 4 for generating a carrier wave used in a radio wave reflection system, and a non-contact IC card 2 The subcarrier modulation unit 5a and the oscillating unit 6a necessary for converting the transmission data into a subcarrier modulation wave, the carrier generated by the carrier oscillating unit 4, and the subcarrier modulation wave output from the subcarrier modulation unit 5a Communication function unit 7 for enabling communication with the non-contact IC card 2 by the radio wave reflection method
a, a carrier wave transmitting antenna 8a and a carrier wave receiving antenna 8b for transmitting and receiving a carrier wave exchanged with the non-contact IC card 2, a sub-carrier communication function unit 9a for enabling communication with the non-contact IC card 2 by AC magnetic field coupling by using a sub-carrier modulated wave. , A subcarrier transmitting antenna 10a for transmitting and receiving a subcarrier modulated wave and a subcarrier receiving antenna 10b.

The contactless IC card 2 has a communication control unit 3b for controlling communication with the identification device 1, a memory unit 11 for storing necessary data, and a carrier communication function having a function of performing communication using a carrier from the identification device 1. Unit 7b, carrier wave transmitting / receiving antenna 8c, subcarrier modulating unit 5b and oscillating unit 6 for converting transmission data to the identification device into a subcarrier modulated wave.
b, a subcarrier communication function unit 9b, a subcarrier transmission antenna 10a, and a subcarrier reception antenna 10 for performing communication by AC magnetic field coupling on subcarriers
b.

When transmitting the transmission data from the identification device 1 to the non-contact IC card 2, the transmission data is sent out from the communication control unit 3a and is transmitted by the subcarrier modulation unit 5a to the above-mentioned FIGS. 6 (c) and 6 (d). Subcarriers as shown in
In the form of frequency modulation or amplitude modulation. Then, in the case of communication based on the radio wave reflection method based on this modulated wave, the carrier wave generated by the carrier wave oscillating unit 4 is added to an ASK (Amplitude Shif).
t Keying) The signal is subjected to a modulation process, and is radiated to the non-contact IC card 2 via the carrier wave transmitting antenna 8a.
Generally, a microwave band is used as a carrier wave.

On the other hand, in the case of communication by AC magnetic field coupling using subcarriers, the modulated wave output from the subcarrier modulation unit 5a is converted into a signal sufficient for the subcarrier communication function unit 9a to generate an AC magnetic field. It is radiated from the subcarrier transmitting antenna 10a to the non-contact IC card 2 as an AC magnetic field coupling means.

In the non-contact IC card 2, the carrier wave from the identification device 1 is received by the carrier wave transmitting / receiving antenna 8c, and the carrier wave communication function unit 7b reproduces the transmission data of the identification device 1 and then sends it to the communication control unit 3b. In communication by AC magnetic field coupling, a subcarrier from the identification device 1 is received by the subcarrier receiving antenna 10b, and transmission data from the identification device 1 is reproduced by the subcarrier communication function unit 9b, and the communication control unit 3b Sent to The data is processed by the communication control unit 3b and stored in the memory unit 11 as needed.

When the non-contact IC card 2 transmits the contents in the memory unit 11 and the response signal to the identification device 1 as transmission data, in the radio wave reflection communication, the transmission data sent from the communication control unit 3b is used. The subcarrier modulating unit 5b generates a modulated wave in which the subcarriers shown in FIGS. 6C and 6D are in the form of frequency modulation or amplitude modulation. This is a very good means for removing the sign inversion phenomenon, which is a problem peculiar to homodyne detection (synchronous detection), which is a means for reproducing a received signal on the identification device side in radio wave reflection communication.

The modulated wave is sent to the carrier communication function unit 7b. The unmodulated carrier wave radiated from the identification device 1 is received by the carrier wave transmitting / receiving antenna 8c, and the carrier wave is phase-modulated by the carrier wave communication function unit 7b according to the modulated wave, and again via the carrier wave transmitting / receiving antenna 8c. It is re-emitted to the identification device 1. In the identification device 1, the carrier wave re-radiated from the non-contact IC card 2 is used as a carrier receiving antenna 8
b, the carrier wave communication function unit 7a performs homodyne detection by the orthogonal detection method as shown in FIG. 5, and takes measures against a null point which is a problem peculiar to homodyne detection. The carrier communication function unit 7a reproduces the subcarrier modulation signal sent from the non-contact IC card 2 from the homodyne-detected signal, detects a subcarrier frequency change or amplitude change in the signal, and detects the non-contact IC card. 2 to reproduce the transmission data. Then, the data is sent to the communication control unit 3a to perform data processing.

On the other hand, in communication by AC magnetic field coupling on the subcarrier, the communication control unit 3 of the non-contact IC card 2
Communication is performed by using a modulated wave on which frequency modulation or amplitude modulation has been performed by the subcarrier modulation unit 5b on the transmission data sent out from b. The modulated wave generated by the subcarrier modulation unit 5b is converted into a signal sufficient to generate an AC magnetic field by the subcarrier communication function unit 9b, and is radiated to the identification device 1 via the subcarrier transmission antenna 10a as AC magnetic field coupling means. .

The identification device 1 receives the subcarrier from the non-contact IC card 2 by the subcarrier receiving antenna 10b, and the non-contact I
The transmission data from the C card 2 is reproduced and the communication control unit 3a
Sent to Then, the data is processed by the communication control unit 3a. Here, in the radio wave reflection communication, the carrier wave radiated from the identification device 1 directly reaches the carrier wave transmitting / receiving antenna 8c of the non-contact IC card 2, and the carrier wave transmitting / receiving antenna is reflected by being hit by other surrounding objects. 8c may be present.

At this time, depending on the phase / amplitude relationship between the two waves, the two waves cancel each other out, and the non-contact IC card 2 cannot obtain a sufficient carrier wave level, so that communication may become impossible. However, even in such a state, in the contactless IC card system according to the present embodiment, the communication means by the AC magnetic field coupling by the subcarrier operates normally.
No problem occurs in the communication of the entire system. Therefore, it is possible to provide a non-contact IC card system capable of always obtaining stable communication.

Next, the detailed configuration and operation of the above-described contactless IC card system will be described with reference to FIG. In FIG. 2, as in FIG. 1, a large configuration includes an identification device 1 having a communication function using a carrier and a subcarrier, a radio wave reflection communication function, and a subcarrier communication function used in the radio wave reflection communication. And a non-contact IC card 2.

Communication control between the identification device 1 and the non-contact IC card 2 is performed by the microprocessors 12a and 12b. The transmission data from the identification device 1 to the non-contact IC card 2 is generated by the microprocessor 12a, and the subcarrier modulation unit 5a multiplies the subcarrier obtained from the oscillation unit 6a by frequency modulation or amplitude modulation to generate a subcarrier modulation signal. And In the radio wave reflection communication, a microwave is usually used as a carrier wave.
To obtain a carrier. ASK modulation is performed on the basis of the subcarrier modulation signal on which the transmission data is superimposed by the microwave modulator 14, amplified to a predetermined level by the microwave transmitter 15, and transmitted to the non-contact IC via the microwave transmission antenna 16 a. It is emitted to the card 2.

On the other hand, in order to use a subcarrier modulation signal on which transmission data is superimposed for communication by AC magnetic field coupling,
The signal is amplified to a predetermined level sufficient to generate an AC magnetic field by the subcarrier transmitting unit 17a, and is radiated from the subcarrier transmitting antenna coil 18a to the non-contact IC card 2 as AC magnetic field coupling means. In general, the frequency of the subcarrier is relatively easy to generate an AC magnetic field.
It is about 0 KHz to several MHz.

On the side of the non-contact IC card 2, the microwave from the identification device 1 is received by the microwave transmitting / receiving antenna 16c, and the microwave receiving unit 19b detects, amplifies, and obtains the subcarrier modulation signal component again. Analog processing such as shaping is performed, and the same subcarrier modulation signal as on the identification device side is reproduced. Then, in the signal processing unit 20b,
The subcarrier frequency change or the amplitude change is detected from the reproduced subcarrier modulation signal, the transmission data of the identification device 1 is reproduced, and sent to the microprocessor 12b.

The subcarrier modulated wave radiated from the discriminating apparatus 1 by the AC magnetic field coupling means is received by the subcarrier receiving antenna coil 18b and converted into a subcarrier modulated signal that can be processed by the signal processing unit 20d. Analog processing such as amplification and waveform shaping is performed in the receiving unit 21b. Then, the signal processing unit 20d detects a change in the frequency or amplitude of the subcarrier from the subcarrier modulation signal, reproduces the transmission data of the identification device 1, and sends the data to the microprocessor 12b, as in the radio wave reflection system. . The data is processed in the microprocessor 12b and stored in the memory unit 11 as necessary.

When the non-contact IC card 2 transmits the contents in the memory unit 11 and a response signal to the identification device 1 as transmission data, in the radio wave reflection communication, the transmission data generated by the microprocessor 12b is used. The subcarrier modulation unit 5b generates a subcarrier modulation signal in which the subcarrier obtained from the oscillation unit 6b is frequency-modulated or amplitude-modulated.

Then, the subcarrier modulation signal is sent to the microwave phase modulator 22. In addition, the unmodulated microwave radiated from the identification device 1 is received by the microwave transmitting / receiving antenna 16c, and the microwave is phase-modulated by the microwave phase modulator 22 according to the subcarrier modulation signal,
It is radiated again to the identification device 1 via the microwave transmitting / receiving antenna 16c again.

In the identification device 1, the microwave re-radiated from the non-contact IC card 2 is used for the microwave receiving antenna 16.
b) a homodyne detection (synchronous detection) method of adding a part of the microwave emitted from the identification device 1 by the microwave receiver 19a and the microwave re-emitted from the non-contact IC card 2 to a mixer to obtain a detection signal And, furthermore,
A non-contact IC card 2 using a quadrature detection method that takes measures against null points, which is a problem unique to homodyne detection,
Are detected.

The detected signal is subjected to analog processing such as amplification and waveform shaping to reproduce a subcarrier modulated signal equivalent to that of the non-contact IC card 2. Then, a subcarrier frequency change or an amplitude change is detected from the subcarrier modulation signal reproduced by the signal processing unit 20a, and the transmission data from the non-contact IC card 2 is reproduced.
The data is sent to 2a for data processing.

On the other hand, in the communication by the AC magnetic field coupling, the subcarrier modulation signal on which the transmission data is superimposed is amplified to a predetermined level sufficient to generate the AC magnetic field by the subcarrier transmitting section 17b, and the subcarrier transmitting antenna coil 18a It is radiated to the discriminating device 1 as AC magnetic field coupling means.

On the identification device 1 side, the sub-carrier modulation wave radiated from the non-contact IC card 2 by the AC magnetic field coupling means is received by the sub-carrier receiving antenna coil 18b and processed by the signal processing unit 20c. Analog processing such as amplification and waveform shaping is performed by the subcarrier receiving unit 21a so as to become a signal. Then, as in the radio wave reflection system, the signal processing unit 20c detects a change in the frequency or amplitude of the subcarrier from the subcarrier modulation signal, reproduces the transmission data of the non-contact IC card 2, and sends it to the microprocessor 12a. .

As described above, in the non-contact IC card according to the present embodiment, the communication is established by the two communication means of the radio wave reflection system and the communication system using the AC electromagnetic coupling. Also, each microprocessor on the identification device side can always know the communication state by monitoring the data received by the two communication means.

In the case of wireless communication, the transmitting side attaches a communication error detection code depending on the content of the transmission data to the end of the transmission data and transmits the transmission data, and the receiving side applies specific processing to the reception data in order to detect a communication error. It is general to compare the executed communication error detection code with the last communication error detection code, determine that the reception is established if there is no abnormality, disable the reception if it is abnormal, and perform a process such as a request for retransmission to the transmitting side. Therefore, if the above-mentioned non-contact IC card is also operated by the method to which the communication error detection code is added, each microprocessor can always determine the communication state of the two communication means and select and accept only correct data. If both communication means receive correct data, either one may be arbitrarily selected.

Also, in the reception disabled state of only one communication means, processing such as a retransmission request to the transmission side occurs, which causes the overall communication time to be prolonged. Unless the state is reached, processing such as a retransmission request does not occur, and communication time is not prolonged much. Therefore, it is very advantageous for an application in which communication time is restricted.

Therefore, the microwave radiated from the identification device 1 in the radio wave reflection communication directly reaches the microwave transmitting / receiving antenna 16c of the non-contact IC card 2 and is reflected by another object and reflected by the microwave. Since the communication means by the AC magnetic field coupling by the subcarrier operates normally even if the communication becomes impossible due to the canceling phenomenon of the wave arriving at the transmitting / receiving antenna 16c, the microprocessor is operated by the communication method as described above. With this, it is possible to provide a non-contact IC card that does not cause any problem in communication of the entire system and can always obtain stable communication.

Next, a non-contact IC card system is constructed by using the above-mentioned non-contact IC card together with an identification device having only a communication function of a radio wave reflection system using microwaves. A case where a non-contact IC card system is configured together with an identification device having only a communication function will be described with reference to FIG. In FIG. 3, (a) shows an identification device 1a provided only with a communication means based on a radio wave reflection system using microwaves and a non-contact I.
(B) is a system including an identification device 1b provided only with a communication unit by AC magnetic field coupling of subcarriers and a non-contact IC card 2.

Although the above two systems have advantages and disadvantages, if an identification device is selected according to an application and a use environment, an economical system can be constructed without increasing the cost of the identification device. However, the non-contact IC card side is a non-contact IC card compatible with both communication systems. The characteristic of the radio wave reflection system is that it uses microwaves, so the radiated or received radio waves can be restricted to a specific direction depending on the configuration method of the transmitting and receiving antennas,
It is relatively easy to limit the communicable area.

Further, unlike the communication means by AC magnetic field coupling, there is no communication deterioration due to the influence of the steel frame inside the building when the transmitting / receiving antenna is mounted, for example. Don't do it.
However, as described above, it is very weak to a reflected wave from other surrounding objects. Further, in communication means using AC magnetic field coupling, it is very difficult to limit the communicable area by adjusting the radiation pattern, but the influence of reflection by other objects is extremely small.

In the radio wave reflection method, if an object enters between the transmitting / receiving antenna on the identification device side and the transmitting / receiving antenna on the non-contact IC card so as to block the radio wave, the radio wave is greatly attenuated and the influence on communication is large. However, communication means using AC magnetic field coupling has little effect except for a metal plate and the like, and is advantageous over the radio wave reflection method under the same conditions. Therefore, it is possible to cope with a usage mode in which the non-contact IC card is covered by the user's hand or a usage mode in which the non-contact IC card is stored inside the bag. Utilizing the features of each system, selecting a method according to the application and the use environment, and constructing a comprehensive system will improve the convenience compared to the related art.

[0049]

As described above, according to the present invention,
In addition to the information communication means using the conventional radio wave reflection method, the information communication means using subcarriers is provided. The same information can be communicated by all of the information communication means, so that in the conventional radio wave reflection type non-contact IC card system, the positional relationship between the radio waves directly reaching the non-contact IC card from the identification device Even if the phase and amplitude relationship cancels each other due to the radio waves reflected and arriving at other surrounding objects, communication will not be disabled and non-contact will always be able to obtain stable communication An IC card system can be provided.

For a non-contact IC card, a radio-wave reflection type information communication means or an information communication means using AC magnetic field coupling by subcarriers is used in a non-contact IC card system together with a separate identification device. By constructing, the characteristics of each communication means, for example, in the radio wave reflection type communication means using microwave, the communicable area is limited by the configuration method of the transmitting and receiving antenna, the degree of freedom of the transmitting and receiving antenna mounting place on the identification device side, In addition, in the communication means of AC magnetic field coupling in the subcarrier, taking advantage of the fact that there is no influence of reflected waves by other objects and the superiority in attenuation when passing through objects, etc., the communication method is adjusted according to the application and use environment. By selecting and constructing a comprehensive system, the convenience is further improved and a wide range of usage forms is possible. It made.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a contactless IC card system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a more detailed configuration of the contactless IC card system.

FIG. 3 is a schematic diagram showing a configuration of a non-contact IC card system different from the non-contact IC card system.

FIG. 4 is a block diagram showing an example of a schematic configuration of a detection method in a conventional contactless IC card system.

FIG. 5 is a non-contact IC with an identification device in the detection method.
FIG. 4 is a diagram illustrating a relationship between a distance to a card and a detection signal level.

FIG. 6 illustrates an example of a modulated wave of a subcarrier.

FIG. 7 is a block diagram showing an example of a schematic configuration of another detection method in a conventional non-contact IC card system.

FIG. 8 is a diagram showing a detection signal level in another detection method of the conventional non-contact IC card system.

[Explanation of symbols]

 Reference Signs List 1 identification device 2 non-contact IC card 3a, 3b communication control unit 4 carrier oscillation unit 5a, 5b subcarrier modulation unit 6a, 6b subcarrier oscillation unit 7a, 7b carrier communication unit 8a carrier transmission antenna 8b carrier reception antenna 8c carrier transmission / reception Antennas 9a, 9b Subcarrier communication function unit 10a Subcarrier transmission antenna 10b Subcarrier reception antenna 11 Memory

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shigeru Fukai 1-5-1, Taito, Taito-ku, Tokyo Letterpress Printing Co., Ltd.

Claims (4)

[Claims] An information transmission from an identification device to a contactless IC card is performed by transmitting a radio wave obtained by modulating a carrier wave according to information transmitted by the identification device.
The transmission of information from the C card to the identification device is performed according to the information transmitted by the non-contact IC card when the non-contact IC card receives a predetermined radio wave emitted from the identification device and transmits the received radio wave. In a non-contact IC card system for transmitting and receiving information between each other by a radio wave reflection method performed by modulating and reflecting the information to the identification device, the non-contact IC card and the identification device each correspond to information to be transmitted. A subcarrier modulation unit that modulates a subcarrier having a lower frequency than the carrier, a carrier modulation unit that modulates the carrier in accordance with a modulation wave output from the subcarrier modulation unit, and a subcarrier modulation unit that outputs the subcarrier. Subcarrier transmitting and receiving means for transmitting and receiving the modulated wave, and a subkey for demodulating the modulated wave received by the subcarrier transmitting and receiving means. And a carrier demodulation means. 2. The non-contact IC card system according to claim 1, wherein the sub-carrier transmission / reception unit is output from the sub-carrier modulation unit when the non-contact IC card and the identification device are coupled by an AC magnetic field. Transmitting and receiving modulated waves. 3. The non-contact IC card according to claim 1, wherein the subcarrier modulation means changes the amplitude of the subcarrier based on information to be transmitted. 4. The non-contact IC card according to claim 1, wherein the sub-carrier modulating means changes the frequency of the sub-carrier based on information to be transmitted.