HK1091605B - Communication system, communication device, wired communication device, and communication method - Google Patents

Description

Communication system, communication device, wired communication device, and communication method

Cross Reference to Related Applications

The present invention comprises the subject matter associated with japanese patent application JP2005-062418, filed at the japanese patent office on 3/7/2005, the entire content of which is incorporated herein by reference.

Technical Field

The invention relates to a communication system, a communication apparatus, a wired communication apparatus and a communication method. More particularly, the present invention relates to a communication system, a communication apparatus, a wired communication apparatus, and a communication method that can perform wired communication with a simple configuration of apparatuses by minimizing the number of lines connecting the apparatuses.

Background

An Integrated Circuit (IC) card capable of performing near field communication, which is one type of wireless communication, has been widely used due to its practicality. Such an IC card that performs near field communication is usable, for example, in an automatic ticketing system in a station or an electronic settlement system that performs settlement by using electronic money.

Due to the popularity of the near field communication IC card, standardization work of a near field communication protocol usable by the IC card is being performed. A typical example of such a Communication protocol is the Near Field Communication Interface and Protocol (NFCIP) -1 defined as ISO/IEC 18092.

NFCIP-1 defines two modes of communication, an active mode and a passive mode. In the active mode, in order to transmit data, a plurality of communication devices each output electromagnetic waves and modulate them by themselves. In the passive mode, in order to transmit data, one of the plurality of communication devices outputs electromagnetic waves and modulates them, and the other communication devices receive the electromagnetic waves and perform load modulation thereon. The NFCIP-1 based Communication device performs Communication in either an active mode or a passive mode (see, for example, Japanese unexamined patent application publication No. 2004-.

In addition to the IC card, cellular phones are now widely used, and devices in which the IC card and the cellular phone are integrated, that is, cellular phones having a built-in IC card for performing near field communication have also come into practical use. More specifically, an IC chip is integrated in a cellular phone instead of an IC card, that is, the IC card and the IC chip are different in shape but similar in function. However, for convenience of description, an IC chip having a function similar to that of an IC card is also referred to as an "IC card".

Some cellular telephones are designed to allow a user to install and remove a Subscriber Identity Module (SIM) card (which includes a SIM chip) that is used to store subscriber information (e.g., a telephone number) that is required by the user to use the cellular telephone. Such a cellular telephone is hereinafter referred to as a "SIM-compatible cellular telephone".

If the user changes the currently used SIM-compatible cellular phone to another SIM-compatible cellular phone, he/she can detach the SIM card from the old cellular phone in order to insert it into the new cellular phone to use the new cellular phone.

As a standard superior to the SIM, a User Identity Module (UIM) may be utilized. The UIM card (which includes a UIM chip) can process not only user subscriber information but also personal information such as a credit card number and authentication information for authentication. SIM cards and UIM cards are defined in ISO 7816.

The SIM card or the UIM card has terminals (pins) for performing wired communication with other devices in order to transmit and receive signals. When the SIM card or the UIM card is mounted in the cellular phone, terminals of the SIM card or the UIM card are brought into contact with terminals of the cellular phone, so that a circuit in the cellular phone can transmit and receive signals to and from the SIM card or the UIM card by wire communication.

Since the SIM card or UIM card is mounted in a portable machine such as a cellular phone, they must be small. Therefore, only a few terminals, for example, around 8 terminals, are provided for transmitting and receiving signals to and from other devices, and some of the terminals are used for transmitting and receiving signals to and from circuits in the cellular phone.

Disclosure of Invention

As described above, at present, there are two types of cellular phones, i.e., one type having a built-in IC card for performing near field communication, and the other type allowing a user to mount and dismount a SIM card or a UIM card (hereinafter simply referred to as "SIM card"). It is therefore desirable to put a cellular phone having a built-in IC card for performing near field communication and compatible with a SIM card into practical use and to make it popular.

In such a cellular phone, a communication interface for performing near field communication by using an IC card may also be used for transmitting and receiving signals between the built-in SIM card and an external device.

In this case, it is necessary to connect such a near field communication interface with the SIM card through a physical line (electric wire).

However, as described above, only a few terminals are provided to the SIM card, and some have been used. Therefore, it is required to minimize the number of physical lines connecting the near field communication interface with the SIM card.

On the other hand, if the number of lines is reduced, signals must be transmitted and received using such a smaller number of lines, which increases the complexity of the communication interface and the SIM card.

More specifically, if only one connection line is used to transmit signals from the communication interface to the SIM card and again from the SIM card to the communication interface, it is necessary to change the impedance (impedance viewed from an external power supply) in the communication interface or the SIM card during transmission and reception of signals. The impedance change may further change the voltage or current, and in this case, signal detection (for example, detecting the level of the received signal) should be performed by accurately considering the change of the voltage or current. In addition, when the SIM card is mounted in the cellular phone, the impedance when viewed from one of the communication interface and the SIM card to the other may vary depending on the contact condition between the cellular phone terminal and the SIM card terminal. Thus, the communication interface and the SIM card must be designed to be able to handle the above-mentioned impedance variations or voltage or current variations. This complicates the structure of the communication interface and the SIM card.

As the structure of the communication interface or the SIM card becomes complicated, the size thereof also increases. This is not desirable since the communication interface and the SIM card, in particular the SIM card, should be small, as described above.

Thus, it is desirable to perform wired communication between a wired communication apparatus such as a SIM card and a communication apparatus such as a communication interface of an IC card capable of performing both wired communication and wireless communication with a simple configuration of the apparatus by minimizing the number of lines connecting the apparatus.

According to an embodiment of the present invention, there is provided a communication system including a wired communication device for performing wired communication, and a communication device capable of communicating with both a wireless communication device performing wireless communication and the wired communication device. The communication apparatus includes a clock output section operable to output a clock to be supplied to the wired communication apparatus, and a modulator operable to perform Amplitude Shift Keying (ASK) modulation on the clock by using a signal corresponding to data to be transmitted to the wired communication apparatus as a modulation object (subject) signal, and output the resultant modulated signal. The wired communication apparatus includes a clock extraction section operable to extract a clock from the modulated signal, a signal extraction section operable to extract a modulation object signal from the modulated signal, and a processing section operable to process the modulation object signal extracted by the signal extraction section in accordance with the clock extracted by the clock extraction section and output a signal corresponding to data to be transmitted to the communication apparatus. The communication device and the wire communication device are connected to each other through a first connection line through which a modulated signal output from the modulator is transmitted from the communication device to the wire communication device, and a second connection line different from the first connection line through which a signal output from the processing section is transmitted from the wire communication device to the communication device.

The system is a logical collection of multiple devices and it is not necessary for the devices to be located within the same housing.

According to another embodiment of the present invention, there is provided a communication device capable of communicating with a wireless communication device for performing wireless communication and a wired communication device for performing wired communication. The communication apparatus includes a clock output section operable to output a clock to be supplied to the wired communication apparatus, and a modulator operable to perform ASK modulation on the clock by using a signal corresponding to data to be transmitted to the wired communication apparatus as a modulation subject signal, and output a resultant modulated signal. The communication device is connected to the wired communication device through a first connection line through which the modulated signal output from the modulator is transmitted from the communication device to the wired communication device, and a second connection line different from the first connection line through which a signal corresponding to data to be transmitted from the wired communication device to the communication device is transmitted from the wired communication device to the communication device.

According to another embodiment of the present invention, there is provided a first communication method for a communication device capable of communicating with a wireless communication device for performing wireless communication and a wired communication device for performing wired communication. The first communication method includes the steps of: the method includes performing ASK modulation on a clock by a modulation object signal using a modulator to output a resultant modulated signal, transmitting the modulated signal to a wired communication apparatus through a first connection line, transmitting the modulated signal output from the modulator from the communication apparatus to the wired communication apparatus through the first connection line, and receiving a signal transmitted from the wired communication apparatus through a second connection line, different from the first connection line, transmitting a signal corresponding to data to be transmitted from the wired communication apparatus to the communication apparatus through the second connection line.

According to another embodiment of the present invention, there is provided a wired communication device for performing wired communication with a communication device capable of communicating with a wireless communication device for performing wireless communication and the wired communication device. The wired communication apparatus includes: a clock extraction section operable to extract a clock from a modulated signal obtained by performing ASK modulation on the clock using a signal corresponding to data as a modulation subject signal and transmitted from the communication apparatus, a signal extraction section operable to extract the modulation subject signal from the modulated signal, and a processing section operable to process the modulation subject signal extracted by the signal extraction section in accordance with the clock extracted by the clock extraction section and output a signal corresponding to data to be transmitted to the communication apparatus. The wired communication device is connected to the communication device through a first connection line through which a modulated signal output from the communication device is transmitted from the communication device to the wired communication device, and a second connection line different from the first connection line through which a signal output from the processing section is transmitted from the wired communication device to the communication device.

In accordance with another embodiment of the present invention, there is provided a second communication method of a wired communication device for performing wired communication with a communication device that is capable of communicating with a wireless communication device for performing wireless communication and the wired communication device. The second communication method includes the steps of: the method includes receiving a modulated signal from the communication apparatus by the wired communication apparatus through a first connection line, transmitting the modulated signal output from the communication apparatus through the first connection line, extracting a clock from the modulated signal by a clock extraction section, and extracting a modulation object signal from the modulated signal by a signal extraction section, and transmitting a signal output from the processing section from the wired communication apparatus to the communication apparatus through a second connection line different from the first connection line, transmitting the signal output from the processor through the second connection line.

Therefore, according to the embodiment of the present invention, the modulated signal obtained by ASK-modulating the clock by the modulation object signal is transmitted from the communication apparatus to the wired communication apparatus through the first connection line, and the signal output from the processor is transmitted from the wired communication apparatus to the communication apparatus through the second connection line.

According to the embodiments of the present invention, it is possible to perform wired communication with a simple device structure by minimizing the number of lines connecting devices.

Drawings

Fig. 1 is a block diagram illustrating a structural example of a communication system according to an embodiment of the present invention;

FIG. 2 illustrates the transmission and reception of data between a message processor and a wireless communication device;

FIG. 3 illustrates the transmission and reception of data between a controller and a message processor;

fig. 4 is a block diagram illustrating a structural example of an NFC interface and a message processor;

fig. 5 is a block diagram illustrating a structural example of a modulator of the NFC interface;

fig. 6 is a waveform diagram illustrating a modulation object signal supplied to a modulator and a SIGOUT signal output from the modulator;

fig. 7 schematically illustrates a modulation object signal and a SIGOUT signal (modulation signal);

fig. 8 is a block diagram illustrating a structural example of a clock extraction section and a signal extraction section;

fig. 9 is a waveform diagram illustrating a SIGIN signal; and is

Fig. 10 illustrates wired communication between the NFC interface and the message processor.

Detailed Description

Before describing embodiments of the present invention, the correspondence between the features of the claims and the specific elements disclosed in accordance with the embodiments of the present invention is discussed below. This description is intended to ensure that embodiments that support the claimed invention are described in this specification. Thus, even if an element in the following embodiments is described not as relating to a certain feature of the present invention, it does not necessarily mean that the element does not relate to the feature of the claims. Conversely, even if described herein with reference to a certain feature of the claims, it is not necessarily intended that the element be referred to other features of the claims.

Furthermore, this description should not be taken in a limiting sense, namely: all aspects of the invention disclosed in the embodiments are described in the claims. That is, the description does not exclude the presence of aspects of the invention which are described in an embodiment but not claimed in the invention of this application, i.e. the presence of certain aspects of the invention which may be claimed later by divisional application or otherwise claimed by modification.

The communication system according to the embodiment of the present invention includes a wired communication device (e.g., the message processor 14 shown in fig. 1) for performing wired communication, and includes a communication device (the NFC interface 12 shown in fig. 1) capable of communicating with a wireless communication device (e.g., the wireless communication device 2 shown in fig. 1) for performing wireless communication and the wired communication device. The communication apparatus includes a clock output section (e.g., a clock selector 46 shown in fig. 4) operable to output a clock to be supplied to the wired communication apparatus, and includes a modulator (e.g., a modulator 47 shown in fig. 4) operable to perform ASK modulation of the clock by using a signal corresponding to data to be transmitted to the wired communication apparatus as a modulation subject signal and output a resultant modulated signal. The wired communication apparatus includes a clock extraction section (e.g., a clock extraction section 52 shown in fig. 4) operable to extract a clock from a modulated signal, a signal extraction section (e.g., a signal extraction section 53 shown in fig. 4) operable to extract a modulation object signal from the modulated signal, and a processing section (e.g., a processing section 54 shown in fig. 4) operable to process the modulation object signal extracted by the signal extraction section in accordance with the clock extracted by the clock extraction section and output a signal corresponding to data to be transmitted to the communication apparatus. The communication apparatus and the wired communication apparatus are connected to each other through a first connection line (e.g., SIGOUT line shown in fig. 1) through which the modulated signal output from the modulator is transmitted from the communication apparatus to the wired communication apparatus and a second connection line (e.g., SIGIN line shown in fig. 1) different from the first connection line through which the signal output from the processing section is transmitted from the wired communication apparatus to the communication apparatus.

A communication device (e.g., the NFC interface 12 shown in fig. 1) according to an embodiment of the present invention is capable of communicating with a wireless communication device (e.g., the wireless communication device 2 shown in fig. 1) for performing wireless communication and a wired communication device (e.g., the message processor 14 shown in fig. 1) for performing wired communication. The communication apparatus includes a clock output section (e.g., a clock selector 46 shown in fig. 4) operable to output a clock to be supplied to the wired communication apparatus, and includes a modulator (e.g., a modulator 47 shown in fig. 4) operable to perform ASK modulation of the clock by using a signal corresponding to data to be transmitted to the wired communication apparatus as a modulation subject signal and output a resultant modulated signal. The communication apparatus is connected to the wired communication apparatus via a first connection line (e.g., SIGOUT line shown in fig. 1) through which the modulated signal output from the modulator is transmitted from the communication apparatus to the wired communication apparatus and a second connection line (e.g., SIGIN line shown in fig. 1) different from the first connection line through which a signal corresponding to data to be transmitted from the wired communication apparatus to the communication apparatus is transmitted from the wired communication apparatus to the communication apparatus.

A first communication method according to an embodiment of the present invention is for a communication device (e.g., the NFC interface 12 shown in fig. 1) capable of communicating with a wireless communication device (e.g., the wireless communication device 2 shown in fig. 1) for performing wireless communication and a wired communication device (e.g., the message processor 14 shown in fig. 1) for performing wired communication. The communication apparatus includes a clock output section (e.g., a clock selector 46 shown in fig. 4) operable to output a clock to be supplied to the wired communication apparatus, and includes a modulator (e.g., a modulator 47 shown in fig. 4) operable to perform ASK modulation of the clock by using a signal corresponding to data to be transmitted to the wired communication apparatus as a modulation subject signal and output a modulated signal. The first communication method includes the steps of: ASK modulation is performed on a clock by a modulation object signal using a modulator to output the modulated signal, the modulated signal is transmitted to a wired communication apparatus through a first connection line (e.g., SIGOUT line shown in fig. 1), the modulated signal output from the modulator is transmitted from the communication apparatus to the wired communication apparatus through the first connection line, and a signal transmitted from the wired communication apparatus is received through a second connection line (e.g., SIGIN line shown in fig. 1) different from the first connection line, and a signal corresponding to data to be transmitted from the wired communication apparatus to the communication apparatus is transmitted from the wired communication apparatus to the communication apparatus through the second connection line.

A wired communication device (e.g., the message processor 14 shown in fig. 1) according to an embodiment of the present invention performs wired communication with a communication device (e.g., the NFC interface 12 shown in fig. 1) that is capable of communicating with a wireless communication device (e.g., the wireless communication device 2 shown in fig. 1) for performing wireless communication and the wired communication device. The wired communication apparatus includes: a clock extraction section (clock extraction section 52 shown in fig. 4) operable to extract a clock from a modulated signal obtained by performing ASK modulation on the clock using a signal corresponding to data as a modulation subject signal and transmitted from the communication apparatus; a signal extraction section (for example, signal extraction section 53 shown in fig. 4) operable to extract the modulation object signal from the modulated signal, and a processing section (processing section 54 shown in fig. 4) operable to process the modulation object signal extracted by the signal extraction section in accordance with the clock extracted by the clock extraction section and output a signal corresponding to data to be transmitted to the communication device. The wired communication apparatus is connected to the communication apparatus via a first connection line (e.g., SIGOUT line shown in fig. 1) via which a modulated signal output from the communication apparatus is transmitted from the communication apparatus to the wired communication apparatus and a second connection line (e.g., SIGIN line shown in fig. 1) different from the first connection line via which a signal output from the processing section is transmitted from the wired communication apparatus to the communication apparatus.

The second communication method according to the embodiment of the present invention is used for a wired communication device (e.g., the message processor 14 shown in fig. 1) that performs wired communication with a communication device (e.g., the NFC interface 12 shown in fig. 1) that is capable of communicating with a wireless communication device (the wireless communication device 2 shown in fig. 1) for performing wireless communication and the wired communication device. The wired communication apparatus includes: a clock extraction section (for example, a clock extraction section 52 shown in fig. 4) operable to extract a clock from a modulated signal obtained by performing ASK modulation on the clock using a signal corresponding to data as a modulation object signal and transmitted from the communication apparatus, a signal extraction section (for example, a signal extraction section 53 shown in fig. 4) operable to extract the modulation object signal from the modulated signal, and a processing section (for example, a processing section 54 shown in fig. 4) operable to process the modulation object signal extracted by the signal extraction section in accordance with the clock extracted by the clock extraction section and output a signal corresponding to data to be transmitted to the communication apparatus. The second communication method includes the steps of: the modulated signal from the communication device is received by the wired communication device through a first connection line (e.g., SIGOUT line shown in fig. 1), the modulated signal output from the communication device is transmitted through the first connection line, the clock is extracted from the modulated signal by the clock extraction means, and the modulation subject signal is extracted from the modulated signal by the signal extraction means, and the signal output from the processing means is transmitted from the wired communication device to the communication device through a second connection line (e.g., SIGIN line shown in fig. 1) different from the first connection line, and the signal output from the processor is transmitted through the second connection line.

Embodiments of the present invention will be described hereinafter with reference to the accompanying drawings.

Fig. 1 illustrates the structure of a communication system according to an embodiment of the present invention.

The communication system includes a cellular phone 1 and a wireless communication device 2, between which wireless communication can be performed.

That is, both the cellular phone 1 and the wireless communication device 2 are configured as devices that: near field communication is performed as wireless communication in accordance with NFCIP-1 (hereinafter such a device is simply referred to as "NFC device").

An NFC device is capable of performing Near Field Communication (NFC) by generating electromagnetic induction with other NFC devices using a carrier wave having a single frequency of, for example, 13.56 megahertz in an Industrial Scientific Medical (ISM) frequency band.

Near field communication is communication that can be performed between devices that are disposed apart from each other at a distance within several tens of centimeters, and includes communication that is performed between devices that are in contact with each other (or a housing in which the devices are housed).

The NFC device is capable of performing near field communication in two communication modes, which are a passive mode and an active mode, as described above. Now assume that two NFC devices (first and second NFC devices) are communicating with each other. In a passive mode, the first NFC device generates electromagnetic waves and modulates a carrier wave corresponding to the electromagnetic waves in order to transmit data to a second NFC device. The second NFC device receives the carrier from the first NFC device and performs load modulation on it to transmit data to the first NFC device.

In active mode, both NFC devices generate electromagnetic waves and modulate a carrier wave corresponding to the electromagnetic waves in order to transmit data.

In near field communication based on electromagnetic induction, an NFC device that starts communication by first outputting an electromagnetic wave, that is, an NFC device that takes the initiative in communication is referred to as an "initiator". In near field communication, the initiator sends a command to another communication device, and the communication device returns a response to the command to the initiator. The communication device used to return the response is referred to as the "target".

If one of the two NFC devices outputs electromagnetic waves to start communication with the other NFC device, the first NFC device is an initiator and the other NFC device is a target.

In the passive mode, the initiator continuously outputs electromagnetic waves and modulates them to transmit data to the target. The target receives electromagnetic waves from the initiator and performs load modulation on them to transmit data to the initiator.

In active mode, the initiator starts outputting electromagnetic waves and modulates them in order to send data to the target. When the data transmission is finished, the starter stops outputting the electromagnetic wave. The target then starts outputting electromagnetic waves and modulates them in order to send data to the initiator. When the transmission of data is finished, the target stops outputting the electromagnetic wave.

An NFC device becomes an initiator by first outputting an electromagnetic wave to start communication. In active mode, the NFC device itself outputs electromagnetic waves, whether it is an initiator or a target. Therefore, it is possible for a plurality of NFC devices to output electromagnetic waves at the same time, and in this case, if such NFC devices are located close to each other, a collision occurs and communication is suspended.

Accordingly, the NFC device checks a Radio Frequency (RF) field formed by electromagnetic waves generated by other devices (e.g., NFC devices), and starts outputting electromagnetic waves only when there are no electromagnetic waves from other devices, thereby avoiding occurrence of a collision. This process is referred to as RF collision avoidance (RFCA) processing.

In the RFCA process, if an electromagnetic wave from another device is not detected for a predetermined continuous period of time (which is determined by using a random number), the NFC device starts outputting an electromagnetic wave. This reduces the possibility that multiple NFC devices start outputting electromagnetic waves at the same time.

The NFC device can transmit data at various transmission rates, such as 106 kilobits per second (kbps), 212kbps, and 424kbps, and can also change the transmission speed while performing communication starting at another transmission speed.

The cellular phone 1 and the wireless communication device 2 configured as described above include NFC interfaces 12 and 22, respectively, which serve as interfaces for performing communication in accordance with NFCIP-1.

More specifically, the cellular phone 1 includes an antenna 11, an NFC interface 12, a controller 13, and a message processor 14.

The antenna 11 forms a closed loop coil, and when a current flowing in the coil is changed, an electromagnetic wave is output from the antenna 11. When an electromagnetic wave (magnetic flux) flowing in a coil serving as the antenna 11 is changed, a current flows in the antenna 11. The signal (current) flowing through the antenna 11 is supplied to the NFC interface 12.

The NFC interface 12 is, for example, a monolithic IC for performing communication in accordance with NFCIP-1 and performing near field communication (wireless communication) with the wireless communication device 2 or another NFC device via the antenna 11.

The NFC interface 12 also serves as an interface for performing wired communication, and is connected to the message processor 14 for performing wired communication through a SIGOUT line (first connection line), a SIGIN line (second connection line), and a GND line.

The SIGOUT line is a wire through which a SIGOUT signal (to be described below) is transmitted from the NFC interface 12 to the message processor 14. The SIGIN line is a wire different from the SIGOUT line, through which a SIGIN signal (to be described below) is transmitted from the message processor 14 to the NFC interface 12. The GND line is grounded.

The NFC interface 12 transmits data (including commands) to the message processor 14 through the SIGOUT line, and receives data from the message processor 14 through the SIGIN line, thereby performing wired communication with the message processor 14.

The NFC interface 12 and the message processor 14 each have terminals connectable to a SIGOUT line, a SIGIN line, and a GND line. However, for simplicity, these terminals are not shown.

The NFC interface 12 also includes an interface for performing communication (wired communication) with the controller 13 in order to transmit and receive various data to and from the controller 13.

The controller 13 controls blocks (not shown) serving as cellular phone components of the cellular phone 1. The blocks used as a cellular phone include a block having a call function and a block having a web browsing and email forming function.

The message processor 14 processes a message, and more particularly, the message processor 14 performs wired communication (transmitting and receiving data by using wired means) to receive data and store it as necessary. The message processor 14 also reads the stored data and transmits it through wired communication.

The message processor 14 is connected to the NFC interface 12 via three connection lines, namely a SIGOUT line, a SIGIN line and a GND line. The message processor 14 transmits data to the NFC interface 12 through the SIGIN line and receives data from the NFC interface 12 through the SIGOUT line, thereby performing wired communication with the NFC interface 12.

The message processor 14 may be integrated into the cellular phone 1. Alternatively, the message processor 14 may be hardware that is easily attached to or detached from the cellular phone 1 by a user, in which case when the message processor 14 is mounted in the cellular phone 1, terminals (not shown) of the message processor 14 are electrically connected to the SIGOUT line, SIGIN line, and GND line.

The message processor 14 can be formed as a SIM card or a UIM card. In this case, the message processor 14 may have a built-in tamper-resistant Secure Application Module (SAM) for managing electronic money or a key used to verify or encrypt data. In the message processor 14 having a built-in SAM, a portion functioning as a SIM card or a UIM card and a portion functioning as a SAM may be integrated into one single IC, or may be formed as different single ICs.

In the cellular phone 1 shown in fig. 1, a line for supplying power Vcc is connected to the message processor 14 in addition to the SIGOUT line, SIGIN line, and GND line, and the power Vcc is supplied to the message processor 14 via the power supply line to operate the message processor 14. There is another line, which is different from the SIGOUT line, SIGIN line, and GND line, for connecting the message processor 14 to the NFC interface 12, and through which power can be supplied from the NFC interface 12 to the message processor 14.

The wireless communication device 2 includes an antenna 21, an NFC interface 22, and a controller 23. The antenna 21 and the NFC interface 22 are configured similarly to the antenna 11 and the NFC interface 12 of the cellular phone 1, respectively.

Since the wireless communication device 2 is not equipped with the block corresponding to the message processor 14, the NFC interface 22 may be provided with or without a function as an interface for performing wired communication with the block corresponding to the message processor 14.

The controller 23 executes various types of processing. More specifically, if the wireless communication device 2 is a reader/writer of an automatic ticket vending machine, the controller 23 controls the NFC interface 22 so as to read information (such as an expiration date and a moving area) from an IC card serving as a round-trip pass by near-field communication when the IC card is located near the wireless communication device 2, and then checks whether information relating to the round-trip pass is appropriate. If the wireless communication device 2 is an IC card capable of electronic settlement, the controller 23 updates the balance of the electronic money in response to an NFC device (not shown) for storing the electronic money and requesting the controller 23 to perform electronic settlement.

The wireless communication device 2 may be formed as a reader/writer and a Personal Computer (PC). In this case, the PC runs an application (program) to realize the controller 23.

The cellular phone 1 and the wireless communication device 2 configured as described above are both NFC devices, and therefore they are capable of performing near field communication in accordance with NFCIP-1.

That is, the NFC interface 12 of the cellular phone 1 is capable of performing near field communication with the NFC interface 22 of the wireless communication device 2 in accordance with NFCIP-1.

The NFC interface 12 of the cellular phone 1 can also perform wired communication with the message processor 14 by being connected thereto through a SIGOUT line, a SIGIN line, and a GND line. The NFC interface 12 may also perform wired communication (controller communication) with the controller 13.

Thus, according to the communication system shown in fig. 1, the NFC interface 12 of the cellular phone 1 can receive data from the NFC interface 22 of the wireless communication device 2 and also transmit the data to the message processor 14 via the SIGOUT line by wired communication. The NFC interface 12 may also receive data from the message processor 14 (e.g., data output from the message processor 14 as a response to data sent from the wireless communication device 2 via the NFC interface 12) via the SIGIN line by wired communication and further transfer the data to the wireless communication device 2 by wireless communication.

Thus, the message processor 14 and the wireless communication device 2 can transmit and receive data to and from each other via the NFC interface 12, as shown in fig. 2. Therefore, if the message processor 14 stores electronic money and the wireless communication device 2 performs electronic settlement, the wireless communication device 2 reads the electronic money stored in the message processor 14 via the NFC interface 12 to perform electronic settlement of products purchased by the user of the cellular phone 1.

According to the communication system shown in fig. 1, the NFC interface 12 of the cellular phone 1 is capable of receiving data from the controller 13 and further transmitting the data to the message processor 14 via SIGOUT line by wired communication. The NFC interface 12 may also receive data from the message processor 14 through wired communication via a SIGIN line and further transmit the data to the controller 13.

Thus, the controller 13 and the message processor 14 can transmit and receive data via the NFC interface 12, as shown in fig. 3. Therefore, if the message processor 14 stores electronic money, the controller 13 can read the current balance of the electronic money from the message processor 14 via the NFC interface 12 and display the balance on the display section (not shown) of the cellular phone 1, thereby allowing the user of the cellular phone 1 to check the balance of the electronic money.

In the communication system 1, the controller 13 and the wireless communication device 2 can also transmit and receive data to and from each other via the NFC interface 12 in a manner similar to the manner in which data is transmitted and received between the message processor 14 and the wireless communication device 2 via the NFC interface 12 as shown in fig. 2 or between the controller 13 and the message processor 14 via the NFC interface 12 as shown in fig. 3.

Thus, if the wireless communication device 2 is an IC card storing electronic money, the controller 13 reads the balance of the electronic money stored in the wireless communication device 2 via the NFC interface 12 and displays the balance on a display section (not shown) of the cellular phone 1, thereby allowing the user to check the balance of the electronic money stored (charged) in the wireless communication device 2 by using the cellular phone 1.

Fig. 4 illustrates a structural example of the NFC interface 12 and the message processor 14 shown in fig. 1. In fig. 4, among the SIGOUT line, SIGIN line, and GND line for connecting the NFC interface 12 and the message processor 14, the GND line is not shown.

In the NFC interface 12, a demodulation processor 41 is connected to the antenna 11 so as to detect a current flowing in the antenna 11 and further detect an RF field formed by an electromagnetic wave generated by another device. The demodulation processor 41 also adjusts the current flowing in the antenna 11 and extracts the information signal to amplify the resulting signal, for example, by performing Amplitude Shift Keying (ASK) demodulation. Thus, the signal can be demodulated. The demodulation processor 41 then supplies the demodulated signal, for example, a manchester code (signal corresponding to data), to the serial data switch 42.

The demodulation processor 41 also generates a clock (clock signal) (external clock) having a frequency of 13.56mhz, which is a carrier frequency employed in NFCIP-1, by adjusting the current flowing in the antenna 11 and extracting the information signal, and supplies the generated clock to the clock selector 46.

The serial data switch 42 supplies the manchester code received from the demodulation processor 41 to the data processor 43 or the modulator 47. The serial data switch 42 also provides the manchester code received from the data processor 43 to either the modulator 44 or the modulator 47. The serial data switch 42 also provides the manchester code received from the message processor 14 via the SIGIN line as a SIGIN signal to either a data processor 43 or a modulator 44.

The data processor 43 encodes data by using a predetermined encoding method, and also decodes data encoded by the predetermined encoding method. More specifically, the data processor 43 encodes data supplied from the controller 13 via a Central Processing Unit (CPU)48 into a manchester code, and supplies the manchester code to the serial data switch 42. The data processor 43 also decodes the manchester code supplied from the serial data switch 42, and supplies the resultant data to the controller 13 via the CPU 48.

Although manchester encoding/decoding is used in the data processor 43, other types of encoding/decoding, such as modified Miller encoding/decoding or non-return to zero (NRZ) encoding/decoding, may be employed.

In the passive mode, the modulator 44 changes impedance when the external power supply looks at the coil serving as the antenna 11 according to a signal (e.g., manchester code) supplied from the serial data switch 42. In this case, if an RF field (magnetic field) is formed around the antenna 11 by an electromagnetic wave output as a carrier wave from another device (e.g., the wireless communication device 2 shown in fig. 1), the RF field changes in response to a change in impedance. Then, a carrier wave as an electromagnetic wave output from the wireless communication apparatus 2 is modulated (load-modulated) in accordance with the signal supplied from the serial data switch 42, and then the signal (manchester code) from the serial data switch 42 is transmitted to the wireless communication apparatus 2 that continuously outputs the electromagnetic wave.

In the active mode, the modulator 44 generates an electromagnetic wave as a carrier wave by allowing a current to flow in the antenna 11, and then modulates the carrier wave by a signal supplied from the serial data switch 42 to output the electromagnetic wave as a modulated signal.

As a modulation method for the modulator 44, ASK modulation can be employed. However, the modulation method is not limited to ASK modulation, and other modulation such as Phase Shift Keying (PSK) modulation or Quadrature Amplitude Modulation (QAM) may also be employed. The modulation factor for ASK modulation according to NFCIP-1 is 8% to 30%.

The clock generator 45 has a quartz oscillator or a ceramic oscillator integrated therein, and generates a clock (internal clock) having a frequency similar to a carrier wave employed in NFCIP-1 to supply the clock to the clock selector 46.

The clock selector 46 selects one of the external clock supplied from the demodulation processor 41 and the internal clock supplied from the clock generator 45, and outputs the selected clock to the modulator 47 and necessary blocks of the NFC interface 12.

More specifically, the clock selector 46 selects the external clock supplied from the demodulation processor 41 when the external clock is supplied from the demodulation processor 41, that is, when an NFC device such as the wireless communication device 2 is located near the NFC interface 12 (cellular phone 1) and an RF field is formed due to the presence of the NFC device. On the other hand, when the external clock is not supplied from the demodulation processor 41, that is: the clock selector 46 selects the internal clock supplied from the clock generator 45 when the RF field is not formed because the NFC device such as the wireless communication device 2 is not located near the NFC interface 12.

The modulator 47 performs ASK modulation on the clock output from the clock selector 46 using the manchester code supplied from the serial data switch 42 (i.e., a signal corresponding to data to be transmitted from the serial data switch 42 to the message processor 14) as a signal to be modulated (hereinafter simply referred to as "modulation subject signal"), and outputs the resultant modulated signal as a SIGOUT signal to the SIGOUT line.

The CPU 48 performs processing on the data as necessary to output the processed data to the data processor 43 or the controller 13. The NFC interface 12 does not have to be equipped with the CPU 48.

The message processor 14 comprises a signal processor 51. The signal processor 51 includes a clock extraction section 52, a signal extraction section 53, and a processing section 54.

The clock extraction section 52 extracts a clock from a modulated signal (SIGOUT signal) transmitted from the modulator 47 via the SIGOUT line, and the clock extraction section 52 supplies the extracted clock to the processing section 54 and necessary blocks of the message processor 14.

The signal extraction section 53 extracts a modulation object signal (manchester code) from a modulation signal (SIGOUT signal) transmitted from the modulator 47 via the SIGOUT line, and the signal extraction section 53 supplies the extracted modulation object signal to the processing section 54.

The processing section 54 decodes the manchester code supplied from the signal extracting section 53 in accordance with the clock extracted by the clock extracting section 52 (in synchronization with the clock), and stores the decoded data. The processing section 54 also encodes the stored data into a manchester code in accordance with the clock extracted by the clock extraction section 52, and outputs the encoded data to the SIGIN line as a SIGIN signal to be transmitted to the NFC interface 12. Then, the SIGIN signal is transmitted from the message processor 14 to the NFC interface 12 via the SIGIN line.

In operation, the NFC interface 12 may receive power from a battery (not shown) of the cellular telephone 1 (fig. 1). Alternatively, the NFC interface 12 may obtain power by using the demodulation processor 41 to rectify current flowing in the antenna 11 from an RF field formed by an NFC device (e.g., the wireless communication device 2) located in the vicinity of the NFC interface 12.

Alternatively, the NFC interface 12 may operate by a combination of the battery of the cellular phone 1 and the current flowing in the antenna 11 due to the presence of the NFC device. More specifically, if the remaining capacity of the battery of the cellular phone 1 is greater than or equal to a predetermined threshold, the NFC interface 12 may be operated by the battery. If the remaining capacity of the battery is less than the threshold value, the NFC interface 12 may operate by using power obtained from the current flowing in the antenna 11 due to the formation of the RF field.

In the NFC interface 12 and the message processor 14 configured as described above, when data is transmitted from the NFC interface 12 to the message processor 14, the modulator 47 of the NFC interface 12 modulates the clock output from the clock selector 46 by using the manchester code to be transmitted to the message processor 14 as a modulation subject signal, and transmits the resulting modulated signal to the message processor 14 via the SIGOUT line as a SIGOUT signal.

In the message processor 14, the signal processor 51 receives the SIGOUT signal via the SIGOUT line, and supplies the SIGOUT signal to the clock extraction section 52 and the signal extraction section 53. The clock extraction unit 52 extracts a clock from the SIGOUT signal and supplies the extracted clock to the processing unit 54. The signal extraction section 53 extracts a manchester code from the SIGOUT signal as a modulation subject signal, and supplies the extracted manchester code to the processing section 54. The processing section 54 processes the manchester codes supplied from the signal extracting section 53 in synchronization with the clock supplied from the clock extracting section 52, and more specifically, the processing section 54 decodes the manchester codes and stores them as necessary.

When transmitting data from the message processor 14 to the NFC interface 12, the modulator 47 of the NFC interface 12 transmits the SIGOUT signal, which is generated by modulating the clock output from the clock selector 46 by using the output from the serial data switch 42 to the message processor 14 via the SIGOUT line. In this case, if the data (manchester code) is not output from the serial data switch 42, the modulator 47 itself transmits the clock from the clock selector 46 to the message processor 14. In the message processor 14, the clock extraction component 52 extracts the clock from the SIGOUT signal and provides the extracted clock to the processing component 54.

The processing section 54 outputs the manchester code to be transmitted to the NFC interface 12 as a SIGIN signal to the SIGIN line in synchronization with the clock output from the clock extraction section 52.

More specifically, the processing section 54 reads data to be transmitted to the NFC interface 12 and encodes the data into a manchester code if they are not encoded. Then, the processing section 54 outputs the manchester code as a SIGIN signal to the SIGIN line. The data can then be sent from the message processor 14 to the NFC interface 12 via the SIGIN line.

In the NFC interface 12, the serial data switch 42 receives the SIGIN signal (manchester code) transmitted from the message processor 14 as described above.

Fig. 5 illustrates a structural example of the modulator 47 shown in fig. 4.

As described above, the modulator 47 receives the manchester code as a signal to be transmitted from the serial data switch 42 to the message processor 14, and receives the clock output from the clock selector 46.

The modulator 47 comprises an amplifier 61. The amplifier 61 amplifies the clock output from the clock selector 46 in accordance with the manchester code (signal) supplied from the serial data switch 42, so as to perform ASK modulation of the clock by using the manchester code as a modulation object signal. Then, the amplifier 61 outputs the ASK-modulated signal to the SIGOUT line as a SIGOUT signal.

In the modulator 47, the ASK modulation factor is 8% to 30%, which is adopted as the modulation factor for the ASK modulation of the carrier in NFCIP-1. However, the modulation factor is not limited to 8% to 30%, but may be any value that allows the clock extraction section 52 of the message processor 14 to extract the clock with high accuracy.

Fig. 6 illustrates an example of a modulation object signal supplied to the amplifier 61 of the modulator 47 shown in fig. 5 and an example of a modulated signal output as a SIGOUT signal from the modulator 47. In fig. 6, the horizontal axis represents time, and the vertical axis indicates amplitude. The same is true of fig. 7 and 9.

The first section from the top in fig. 6 illustrates an example of a modulation target signal. The modulation subject signal is a manchester code, and more specifically, a signal corresponding to data (bits) before being encoded as a manchester code. More specifically, when the data indicates 0 (binary), the manchester code changes from a low (L) level to a high (H) level. When the data indicates 1 (binary), the manchester code changes from the H level to the L level.

The second part from the top in fig. 6 illustrates an example of a modulated signal (SIGOUT signal) generated by modulating a pulse train as a clock using the modulation target signal indicated in the first part in fig. 6.

The amplifier 61 of the modulator 47 amplifies the clock by 1 time when the modulation object signal is at the H level, and the amplifier 61 amplifies the clock by a multiple larger than 0 and smaller than 1 (for example, a multiple from 0.92 to 0.7) when the modulation object signal is at the L level.

The third section from the top in fig. 6 illustrates a waveform of a current (modulation signal) flowing in the antenna 11 when the modulator 44 modulates a sine wave as a carrier wave by the modulation object signal indicated by the first section in fig. 6.

As described above, the modulator 44 performs ASK modulation on the carrier wave using the manchester code obtained by encoding data. In the modulators 44 and 47, the modulation object signal is manchester code, and the modulation method is ASK modulation. Therefore, the current (modulation signal) flowing in the antenna 11 generated by the modulation performed by the modulator 44 is similar to the SIGOUT signal (modulation signal) obtained by the modulation performed by the modulator 47, except that the signal type modulated by the modulation object signal is different, that is, the carrier and the clock.

If the clock frequency output from the clock selector 46 (fig. 4) is 13.56MHz, and if the transmission speed of the manchester code supplied from the serial data switch 42 to the modulator 47 is 212kbps, there are about 64 pulses (≈ 13.56MHz/212kbps) in one symbol (one bit) of data.

Fig. 7 is an enlarged view illustrating a part of the modulation target signal and SIGOUT signal (modulation signal) shown in fig. 6.

The first section from the top of fig. 7 illustrates the clock supplied from the clock selector 46 to the modulator 47. The second section from the top of fig. 7 illustrates a modulation object signal (manchester code) supplied from the serial data switch 42 to the modulator 47. The third section from the top in fig. 7 illustrates a SIGOUT signal (modulation signal) obtained by performing ASK modulation on the clock indicated in the first section by the modulation subject signal indicated in the second section.

It is now assumed that the minimum and maximum voltages of the clock pulses shown in the first section are 0 volts and Vc volts, respectively. In this case, when the modulation object signal is at the H level, the voltage of the SIGOUT signal is Vc V, as shown in the third section. When the modulation object signal is at the L level, the voltage of the SIGOUT signal is Vc' V, which is greater than 0 volt and less than Vc volt, as shown in the third section.

Fig. 7 shows that after ASK modulation of the clock by the modulation object signal, the rising edge and the falling edge of the clock of the resultant SIGOUT signal can be maintained, but at a level different from that of the clock.

Fig. 8 illustrates a structural example of the clock extraction section 52 and the signal extraction section 53 shown in fig. 4.

The clock extraction section 52 includes a comparison voltage output section 71 and a comparator 72.

The comparison voltage output section 71 outputs the predetermined threshold TH1, which is a voltage to be compared with the SIGOUT signal supplied from the NFC interface 12 via the SIGOUT line, to the comparator 72.

In this case, if the voltage of the SIGOUT signal takes three values such as 0, Vc ', and Vc, as shown in the third part of fig. 7, the predetermined threshold TH1 is greater than 0 and smaller than Vc ', for example, Vc '/2.

The comparator 72 compares the SIGOUT signal supplied from the NFC interface 12 via the SIGOUT line with the threshold value supplied from the comparison voltage output section 71 to extract and output the clock from the SIGOUT signal.

More specifically, when comparing the SIGOUT signal with the threshold TH1, if the SIGOUT signal is greater than or equal to the threshold TH1, the comparator 72 outputs the H level, and if the SIGOUT signal is less than the threshold TH1, the comparator 72 outputs the L level, thereby extracting the clock indicated in the first part of fig. 7 from the SIGOUT signal indicated in the third part of fig. 7.

As described above, in the SIGOUT signal, since the rising edge and the falling edge of the clock can be maintained, the clock can be easily and accurately obtained only by comparing the SIGOUT signal with the threshold TH 1.

The signal extraction section 53 includes an envelope detector 81, a comparison voltage output section 82, and a comparator 83.

The envelope detector 81 detects the envelope of the SIGOUT signal supplied from the NFC interface 12 via the SIGOUT line, and supplies the resultant envelope signal to the comparator 83.

The comparison voltage output section 82 outputs a predetermined threshold TH2, which is a voltage to be compared with the envelope signal supplied from the envelope detector 81, to the comparator 83.

In this case, if the voltage of the SIGOUT signal takes three values such as 0, Vc ', and Vc, as shown in the third part of fig. 7, the predetermined threshold TH2 is greater than Vc ' and less than Vc, for example, is the average of Vc ' and Vc.

The comparator 83 compares the envelope signal supplied from the envelope detector 81 with the threshold TH2 supplied from the comparison voltage output section 82 to extract and output the modulation object signal from the SIGOUT signal.

More specifically, when comparing the envelope signal with the threshold TH2, if the envelope signal is greater than or equal to the threshold TH2, the comparator 83 outputs the H level, and if the envelope signal is less than the threshold TH2, the comparator 83 outputs the L level, thereby extracting the modulation object signal indicated in the second part of fig. 7 from the envelope signal of the SIGOUT signal indicated in the third part of fig. 7.

As described above, the SIGOUT signal is a modulated signal generated by modulating the clock with the modulation target signal. Therefore, by obtaining the envelope of the SIGOUT signal and comparing it with the threshold TH2, the SIGOUT signal can be easily and accurately demodulated into the modulation object signal.

Fig. 9 illustrates a SIGIN signal to be output to the SIGIN line by the processing section 54 shown in fig. 4.

The first part from the top in fig. 9 illustrates an example of a SIGIN signal. As described above, the SIGIN signal is a signal obtained by encoding data into manchester code, as in the modulation object signal supplied from the serial data switch 42 to the modulator 47. The SIGIN signal changes from the L level to the H level when the corresponding data indicates 0 (binary), and changes from the H level to the L level when the corresponding data indicates 1 (binary).

As described above, the modulator 44 (fig. 4) modulates the carrier wave by the manchester code. Accordingly, if the SIGIN signal, which is a manchester code, is transmitted from the message processor 14, the serial data switch 42 can directly supply the SIGIN signal to the modulator 44, and thus the SIGIN signal can be transmitted to the NFC device, such as the wireless communication device 2, through near field communication.

More specifically, the second section from the top of fig. 9 illustrates the waveform of the current (modulation signal) flowing in the antenna 11 when the SIGIN signal indicated in the first section from the top of fig. 9 is directly supplied to the modulator 44 and used to modulate the electromagnetic wave as the carrier wave by the modulator 44.

A description will now be given of wired communication performed between the NFC interface 12 and the message processor 14 shown in fig. 4 with reference to fig. 10.

When receiving the manchester code to be transmitted to the message processor 14 from the demodulation processor 41 or the data processor 43, the serial data switch 42 of the NFC interface 12 supplies the manchester code to the modulator 47 as a modulation subject signal.

In step S1, the modulator 47 modulates the clock output from the clock selector 46 by the manchester code supplied as the modulation object signal from the serial data switch 42, and transmits the resulting modulated signal as a SIGOUT signal to the message processor 14 via the SIGOUT line.

At step S11, the message processor 14 receives the SIGOUT signal transmitted from the modulator 47 of the NFC interface 12 via the SIGOUT line, and supplies the SIGOUT signal to the clock extraction section 52 and the signal extraction section 53.

Then, in step S12, the clock extraction section 52 extracts the clock from the SIGOUT signal, and the signal extraction section 53 extracts the manchester code from the SIGOUT signal as the modulation object signal. Then, the clock extraction section 52 supplies the extracted clock to the processing section 54, and the signal extraction section 53 supplies the extracted manchester code as a modulation object signal to the processing section 54.

In step S13, the processing section 54 processes the manchester code supplied from the signal extraction section 53 in synchronization with the clock supplied from the clock extraction section 52.

Then, in step S14, the processing section 54 transmits the manchester code to be transmitted to the NFC interface 12 as a SIGIN signal to the NFC interface 12 via the SIGIN line.

At step S2, the serial data switch 42 of the NFC interface 12 receives the SIGIN signal transmitted as the manchester code from the processing section 54 of the message processor 14 as described above, and supplies the received SIGIN signal to the data processor 43 or the modulator 44.

If the manchester code, which is the SIGIN signal, is supplied from the serial data switch 42 to the data processor 43, the data processor 43 decodes the manchester code into the original data, and supplies the decoded data to the controller 13. If the manchester code is supplied as the SIGIN signal from the serial data switch 42 to the modulator 44, the modulator 44 modulates the electromagnetic wave as a carrier wave by using the manchester code, thereby transmitting data corresponding to the manchester code as the SIGIN signal to the NFC device for generating the electromagnetic wave.

The modulator 47 continuously transmits the SIGOUT signal during the wired communication performed between the NFC interface 12 and the message processor 14. Therefore, if no data is to be transmitted from the NFC interface 12 to the message processor 14, the clock itself output from the clock selector 46 is transmitted as the SIGOUT signal from the modulator 47 to the message processor 14.

As described above, the clock is ASK-modulated by using the modulation target signal (manchester code), and the SIGOUT signal, which is the resulting modulated signal, is transmitted from the NFC interface 12 to the message processor 14 via the SIGOUT line. Thus, by sending the SIGOUT signal, both data and clock can be sent from the NFC interface 12 to the message processor 14.

That is, by using a single connection line, i.e., SIGOUT line, not only data can be transmitted from the NFC interface 12 to the message processor 14, but also a clock can be provided. This does not require connecting the NFC interface 12 and the message processor 14 through a connection dedicated to providing a clock from the NFC interface 12 to the message processor 14.

Instead of providing a clock from the NFC interface 12 to the message processor 14, a clock generator similar to the clock generator 45 (fig. 4) may also be included in the message processor 14, so that the message processor 14 can operate in synchronization with the clock generated by the built-in clock generator.

In this case, however, a quartz oscillator for generating a clock needs to be integrated into the clock generator, which increases the size of the message processor 14.

If the message processor 14 is formed as a SIM card or a UIM card, it should be formed as a small-sized device since the SIM card or the UIM card is small, as described above. Thus, it is inappropriate to integrate a clock generator into the message processor 14.

It is therefore necessary to provide a clock from an external power supply to the message processor 14. However, if the clock is independently supplied to the message processor 14, the message processor 14 should be provided with a terminal to be connected to a line dedicated to supplying the clock.

However, if the message processor 14 is formed as a SIM card, as described above, it is desirable that the number of lines to be connected to the SIM card be minimized because the number of terminals provided for the SIM card is limited.

As described above, the clock is ASK-modulated by using the modulation target signal (manchester code), and the resulting modulated signal is transmitted as a SIGOUT signal from the NFC interface 12 to the message processor 14 via the SIGOUT line. This does not require the provision of a connection dedicated to the provision of a clock from the NFC interface 12 to the message processor 14. Thus, the NFC interface 12 and the message processor 14 can be connected to each other with a minimum number of connection lines.

In addition, since the SIGOUT signal is a signal obtained by performing ASK modulation on a clock, a rising edge (positive edge) and a falling edge (negative edge) can be maintained as they are, but the levels thereof are different. Thus, the message processor 14 can easily extract a clock having a duty cycle of 50 simply by comparing the SIGOUT signal with a predetermined threshold.

Since the SIGOUT signal contains data (manchester code) having different levels, the message processor 14 can easily extract the data by detecting the envelope of the SIGOUT signal and by comparing the envelope with a predetermined threshold value.

That is, the message processor 14 can extract the clock and data from the SIGOUT signal with a simple circuit configuration.

Thereby, the wired communication can be performed by a device (circuit) of a simple structure between the NFC interface 12 capable of performing wireless communication and wired communication, such as a communication interface of an IC card, and the message processor 14, such as a SIM card, and the message processor 14 for performing wired communication, by minimizing the number of lines for connecting the NFC interface 12 and the message processor 14.

According to NFCIP-1, data can be sent at various transmission rates, such as 106kbps, 212kbps, and 424 kbps. The circuit configuration of the NFC interface 12 and the message processor 14 remains the same regardless of the transmission speed with which the clock is subjected to ASK modulation by data (manchester code). That is, it is not necessary to change the circuit configuration of the NFC interface 12 and the message processor 14 according to the transmission speed.

The SIGIN signal transmitted from the message processor 14 to the NFC interface 12 is a manchester code, i.e., a signal obtained by encoding data by an encoding method used when wireless communication is performed between the NFC interface 12 and an NFC device. This allows the NFC interface 12 to modulate an electromagnetic wave as a carrier wave by using the SIGIN signal transmitted from the message processor 14 and transmit the modulated signal to the NFC device.

The signal transmitted and received by the NFC interface 12 through wireless communication is a signal obtained by performing ASK modulation on a carrier wave using a manchester code (modulation object signal). In contrast, the SIGOUT signal is a signal obtained by performing ASK modulation on a clock using a manchester code, and the SIGIN signal is a manchester code. Therefore, the compatibility of the signal transmitted and received by the NFC interface 12 through wireless communication with the SIGOUT signal and the SIGIN signal transmitted and received between the NFC interface 12 and the message processor 14 is high. Thus, it is not difficult to integrate existing NFC device circuitry into the message processor 14. More specifically, the existing NFC device is, for example, an IC card, and the IC card includes not only an NFC interface similar to the NFC interface 12 but also a tamper-resistant SAM for managing an encryption key for performing authentication or encrypting data. The SAM can easily be integrated into the message processor 14.

In addition, the SIGIN line for transmitting data (SIGIN signal) from the message processor 14 to the NFC interface 12 and the SIGOUT line for transmitting data (SIGOUT signal) from the NFC interface 12 to the message processor 14 are physically different connection lines. Thus, the NFC interface 12 and the message processor 14 can be designed without having to take into account precisely the impedance variations, which would otherwise be necessary when using a single line to transmit signals from the communication interface to the SIM card and vice versa, as described above. Therefore, wired communication can become more stable.

In the above-described embodiment, as the communication device capable of performing wired communication and wireless communication, the NFC interface 12 is used as a communication interface that performs wireless communication in accordance with NFCIP-1. However, other communication interfaces that perform wireless communication in accordance with standards other than NFCIP-1 may also be used.

In addition, although the message processor 14 serving as a wired communication device is formed as a SIM card or a UIM card according to this embodiment, it may be configured as other types of devices.

The previous embodiments have been described in the context of a communication system comprising a cellular telephone. However, this is merely exemplary, and the present invention is applicable to a device in which a communication interface that can perform wireless communication, in particular, near field communication and wired communication can be integrated.

It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and variations may be made in accordance with design requirements and other factors, which are included in the scope of the appended claims or their equivalents.

Claims (6)

1. A cellular telephone (1) comprising:

a message processor (14) for performing wired communication; and

a near field communication interface (12) capable of communicating with a near field communication device (2) for performing near field communication and with the message processor (14),

the near field communication interface (12) comprises:

a first modulator (44) connected to the antenna (11);

a demodulation processor (41) connected to the antenna (11) and generating an external clock;

a clock generator (45) that generates an internal clock;

a clock selector (46) that selects one of the external clock and the internal clock to output a clock to be supplied to the message processor (14), an

A second modulator (47) operable to perform amplitude shift keying modulation on the clock output by the clock selector (46) by using a signal corresponding to data to be transmitted to the message processor (14) as a modulation subject signal, and output the resultant modulated signal,

the message processor (14) comprises:

a clock extraction component (52) operable to extract a clock from the modulated signal,

a signal extraction section (53) operable to extract a modulation object signal from the modulation signal, an

A processing section (54) operable to process the modulation object signal extracted by the signal extraction section (53) in accordance with the clock extracted by the clock extraction section (52) and also output a signal corresponding to data to be transmitted to the near field communication interface (12),

wherein the near field communication interface (12) and the message processor (14) are connected to each other via a first connection line and a second connection line different from the first connection line, wherein:

the modulated signal output from the second modulator (47) is transmitted from the near field communication interface (12) to the message processor (14) through the first connection line, and

the signal output from the processing component (54) is transmitted from the message processor (14) to the near field communication interface (12) via a second connection.

2. A near field communication interface (12) capable of communicating with a near field communication device (2) for performing near field communication and a message processor (14) for performing wired communication, the near field communication interface (12) comprising:

a first modulator (44) connected to the antenna (11);

a demodulation processor (41) connected to the antenna (11) and generating an external clock;

a clock generator (45) that generates an internal clock;

a clock selector (46) that selects one of the external clock and the internal clock to output a clock to be supplied to the message processor (14); and

a second modulator (47) operable to perform amplitude shift keying modulation on the clock output by the clock selector (46) by using a signal corresponding to data to be transmitted to the message processor (14) as a modulation subject signal, and output the resultant modulated signal,

wherein the near field communication interface (12) is connected to the message processor (14) via a first connection line and a second connection line different from the first connection line, wherein:

the modulated signal output from the second modulator (47) is transmitted from the near field communication interface (12) to the message processor (14) through the first connection line, and

signals corresponding to data to be transmitted from the message processor (14) to the near field communication interface (12) are transmitted from the message processor (14) to the near field communication interface (12) via the second connection.

3. A near field communication interface (12) as claimed in claim 2, wherein, when the near field communication interface (12) modulates a carrier wave by using a signal obtained by encoding data in accordance with a predetermined encoding method so as to transmit data to the near field communication device (2), the modulation subject signal is a signal obtained by encoding data in accordance with the predetermined encoding method, and a signal corresponding to data to be transmitted from the message processor (14) to the near field communication interface (12) is also a signal obtained by encoding data in accordance with the predetermined encoding method.

4. A communication method for a near field communication interface (12), the near field communication interface (12) being capable of communicating with a near field communication device (2) for performing near field communication and a message processor (14) for performing wired communication,

the near field communication interface (12) comprises:

a first modulator (44) connected to the antenna (11);

a demodulation processor (41) connected to the antenna (11) and generating an external clock;

a clock generator (45) that generates an internal clock;

a clock selector (46) that selects one of the external clock and the internal clock to output a clock to be supplied to the message processor (14), an

A second modulator (47) operable to perform amplitude shift keying modulation on the clock output by the clock selector (46) by using a signal corresponding to data to be transmitted to the message processor (14) as a modulation subject signal, and output the resultant modulated signal, the communication method comprising the steps of:

performing amplitude shift keying modulation on the clock by modulating the object signal using a second modulator (47) to output the modulated signal;

transmitting the modulated signal to the message processor (14) through a first connection line, wherein the modulated signal output from the second modulator (47) is transmitted from the near field communication interface (12) to the message processor (14) through the first connection line; and is

-receiving a signal transmitted from the message processor (14) over a second connection line, wherein the second connection line is different from the first connection line, -transmitting a signal from the message processor (14) to the near field communication interface (12) corresponding to data to be transmitted from the message processor (14) to the near field communication interface (12) over the second connection line.

5. A message processor (14) for performing wired communication with a near field communication interface (12), wherein the near field communication interface (12) is capable of communicating with a near field communication device (2) for performing near field communication and the message processor (14), the message processor (14) comprising:

a clock extraction section (52) operable to extract a clock from a modulated signal obtained by performing amplitude shift keying modulation on the clock using a signal corresponding to data as a modulation object signal and transmitted from the near field communication interface (12);

a signal extraction section (53) operable to extract a modulation target signal from the modulation signal; and

a processing section (54) operable to process the modulation object signal extracted by the signal extraction section (53) in accordance with the clock extracted by the clock extraction section (52) and also output a signal corresponding to data to be transmitted to the near field communication interface (12),

wherein the message processor (14) is connected to the near field communication interface (12) via a first connection line and a second connection line different from the first connection line, wherein:

transmitting the modulated signal output from the near field communication interface (12) to the message processor (14) via a first connection line, and

-sending a signal output from the processing means (54) from the message processor (14) to said near field communication interface (12) via a second connection line.

6. A communication method for a message processor (14), the message processor (14) being adapted to perform a wired communication with a near field communication interface (12), the near field communication interface (12) being adapted to communicate with a near field communication device (2) adapted to perform a near field communication and the message processor (14),

the message processor (14) comprises:

a clock extraction section (52) operable to extract a clock from a modulated signal obtained by performing amplitude shift keying modulation on the clock using a signal corresponding to data as a modulation object signal and transmitted from the near field communication interface (12),

a signal extraction section (53) operable to extract a modulation object signal from the modulation signal, an

A processing section (54) operable to process the modulation object signal extracted by the signal extraction section (53) in accordance with the clock extracted by the clock extraction section (52), and also output a signal corresponding to data to be transmitted to the near field communication interface (12), the communication method comprising the steps of:

receiving, by a message processor (14), a modulated signal from the near field communication interface (12) over a first connection line, wherein the modulated signal output from the near field communication interface (12) is transmitted over the first connection line;

extracting a clock from the modulated signal by a clock extraction section (52), and extracting a modulation object signal from the modulated signal by a signal extraction section (53); and is

Signals output from the processing component (54) are transmitted from the message processor (14) to the near field communication interface (12) over a second connection line different from the first connection line, wherein signals output from the processor are transmitted over the second connection line.