JP2009175976A - Transmission and receiving circuit, information processing device, communication method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission and receiving circuit, an information processing device, and a communication method, for preventing occurrence of a communication impossible range in a non-contact communication using a carrier wave, and a program. <P>SOLUTION: The transmission and receiving circuit includes a communication antenna for receiving the carrier wave transmitted from a reader/writer and generating induced voltage, a carrier wave detection section for outputting a detection signal, a voltage control oscillation section for outputting an output signal of frequency corresponding to input voltage on the basis of the detection signal, a phase comparison section for outputting a phase difference signal according to the phase difference between the detection signal and the output signal, a data processing section for processing the carrier wave signal and outputting the control signal on the basis of the phase difference signal, a loop filter for outputting phase compensation voltage on the basis of the phase difference signal, a level retention section selectively inputting the phase compensation voltage by corresponding to the control signal and outputting phase compensation voltage or retained retention voltage as input voltage, and a modulation section for selectively outputting the output signal to the communication antenna on the basis of the control signal and transmitting a synchronized carrier wave. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a transmission / reception circuit, an information processing apparatus, a communication method, and a program.

  In recent years, reader / writers (or communication devices having a reader / writer function) such as non-contact IC (Integrated Circuit) cards, RFID (Radio Frequency Identification) tags, and mobile phones equipped with non-contact IC chips are not used. Information processing apparatuses that can communicate in a contact-type have become widespread.

  A reader / writer and an information processing apparatus such as an IC card or a mobile phone use a magnetic field (carrier wave) having a specific frequency such as 13.56 MHz for communication. Specifically, the reader / writer transmits a carrier wave carrying a carrier wave signal, and an information processing device such as an IC card that has received the carrier wave by an antenna returns a response signal to the carrier wave signal received by load modulation, whereby the reader / writer / The writer and the information processing apparatus can communicate with each other.

  In addition, an information processing apparatus that can communicate with a reader / writer in a non-contact manner includes an IC chip having tamper resistance, and performs non-contact communication using a carrier wave using the IC chip. For example, it is possible to safely transmit / receive and update data such as electronic money where data alteration is a problem. Accordingly, the provision of various services using an information processing apparatus equipped with an IC chip capable of non-contact communication with the reader / writer as described above is spreading socially. With the spread of service provision, information processing apparatuses equipped with non-contact IC chips such as IC cards and mobile phones are becoming more widespread.

  Under such circumstances, various techniques for stabilizing non-contact communication using a carrier wave between a reader / writer and an information processing apparatus have been developed. For example, Patent Literature 1 and Patent Literature 2 can be cited as techniques for shifting the frequency to be tuned by estimating the communication distance. Further, as a technique for determining the difficulty of detecting a modulation component and weakening the carrier wave according to the determination result, for example, Patent Document 3 is cited. Moreover, as a technique for switching the output impedance in accordance with the passage of time when no response is received, for example, Patent Document 4 can be cited. Further, as a technique for setting the resonance frequency of the antenna lower by a predetermined value in advance in order to enable communication at a close range, for example, Patent Document 5 is cited.

JP 2006-279813 A JP 2006-238398 A JP 2007-74153 A JP 2004-240716 A JP 2003-67689 A

  A communication device (hereinafter simply referred to as “reader / writer”) having a reader / writer or a reader / writer function (that is, a function of transmitting a carrier wave mainly) and an information processing device such as an IC card or a mobile phone For example, since communication is performed using a magnetic field having a predetermined frequency such as 13.56 MHz (hereinafter referred to as “carrier wave”), the closer the communication distance is, the larger the magnetic field energy becomes, and the stabilization of communication. Can be expected. However, in practice, communication may not be performed even when the communication distance between the reader / writer and the information processing apparatus is short (that is, within a communicable range). This can occur when the reader / writer cannot detect a change in state before and after load modulation in the information processing apparatus and cannot demodulate it even though it receives a response signal transmitted from the information processing apparatus. .

  Here, the conventional technique for estimating the communication distance and shifting the tuning frequency merely shifts the tuning frequency on the reader / writer side or the information processing apparatus side by estimating the communication distance. Therefore, for example, when the point where communication cannot be performed shifts due to the antenna size or the number of windings used for communication (that is, when the point where communication cannot be performed is not constant), the frequency to be tuned by estimating the communication distance is shifted. Even if the conventional technology is used, stabilization of communication cannot be expected.

  In addition, the technology that determines the difficulty of detecting the modulation component and weakens the carrier wave according to the determination result has to deliberately weaken the carrier wave used for communication in order to avoid points where communication cannot be performed. I can't expect it. In addition, the technique of determining the difficulty of detecting the modulation component and weakening the carrier wave according to the determination result cannot sufficiently avoid the point where communication cannot be performed unless the auxiliary antenna is provided. Therefore, even if a technique for determining the difficulty of detecting the modulation component and weakening the carrier according to the determination result is used, stabilization of communication cannot be expected.

  Further, the conventional technique for switching the output impedance with the passage of time when no response is received merely switches the output impedance in order to avoid a point where communication cannot be performed. Therefore, since the switched output impedance is not necessarily an output impedance suitable for communication, stabilization of communication can be expected even if the conventional technique of switching the output impedance over time when no response is received is used. Absent.

  Furthermore, since the conventional technique of setting the resonance frequency of the antenna lower by a predetermined value in advance in order to enable communication at a close range is merely setting the resonance frequency of the antenna in advance, for example, When the point at which communication cannot be performed shifts due to the antenna size or the number of windings (that is, when the point at which communication cannot be performed is not constant), communication may not be performed at a preset resonance frequency. Therefore, even if a conventional technique in which the resonance frequency of the antenna is set low by a predetermined value in order to enable communication at a close distance, the stabilization of communication cannot be expected.

  Therefore, the conventional technology for stabilizing communication between the reader / writer and the information processing apparatus cannot solve the problem that communication cannot be performed within the communicable range.

  The present invention has been made in view of the above problems, and an object of the present invention is to prevent a non-communication area from being generated within a communicable range in non-contact communication using a carrier wave. Another object of the present invention is to provide a new and improved transmission / reception circuit, information processing apparatus, communication method, and program.

  In order to achieve the above object, according to a first aspect of the present invention, a communication antenna that receives a carrier wave of a predetermined frequency transmitted from a reader / writer and generates an induced voltage according to the carrier wave; A carrier wave detection unit that detects an induced voltage and outputs a detection signal; a voltage that receives the detection signal and an input voltage and outputs an output signal having a frequency corresponding to the input voltage based on the detection signal A control oscillation unit, a phase comparison unit that compares the phase difference between the phase of the reference signal from which the induced voltage is detected and the phase of the output signal, and outputs a phase difference signal corresponding to the phase difference; and the induced voltage A data processing unit that processes a demodulated carrier wave signal based on the phase difference signal and outputs a control signal corresponding to the process based on the phase difference signal, and removes an AC component of the phase difference signal and outputs a phase compensation voltage You The phase compensation voltage is selectively input in accordance with the loop filter and the control signal to hold the phase compensation voltage, and the phase compensation voltage input in accordance with the control signal or the held holding voltage is A level holding unit that selectively outputs to the voltage controlled oscillator as the input voltage, and a modulation that selectively outputs the output signal to the communication antenna based on the control signal and transmits a synchronized carrier wave from the communication antenna. And a transmission / reception circuit including the unit.

  With this configuration, it is possible to prevent the occurrence of a communication disabled area within a communicable range in non-contact communication using a carrier wave.

  The modulation unit includes a first switch that is turned on / off according to the control signal, and the level holding unit is turned off when the first switch is on according to the control signal. A second switch that turns on when the first switch is off and selectively outputs the phase compensation voltage as the input voltage; holds the phase compensation voltage output from the second switch; and And a capacitor that outputs the held voltage held when the switch of 2 is off as the input voltage.

  With this configuration, modulation can be performed using a reference signal based on a carrier wave and an output signal whose frequency and phase are synchronized.

  The data processing unit may output a control signal corresponding to the process when the phase difference indicated by the phase difference signal is zero.

  With this configuration, modulation can be performed using a reference signal based on a carrier wave and an output signal whose frequency and phase are synchronized.

  In addition, a phase correction unit that corrects the phase of the output signal that is selectively output from the modulation unit according to the control signal and transmits the corrected signal to the communication antenna may be further provided.

  With this configuration, it is possible to more reliably prevent the occurrence of a communication disabled area within a communicable range.

  Further, the phase correction unit may delay the phase of the output signal by a predetermined amount.

  With this configuration, it is possible to more reliably prevent the occurrence of a communication disabled area within a communicable range.

  Further, an amplification unit that amplifies the gain of the output signal that is selectively output from the modulation unit according to the control signal may be further provided.

  With this configuration, it is possible to increase the possibility that communication can be normally performed by transmitting a sync carrier wave having a larger gain.

  In addition, a frequency divider that divides the output signal output from the voltage controlled oscillator may be further provided.

  With this configuration, since the output signal output from the voltage controlled oscillation unit and the frequency of the carrier wave are different, it is possible to adjust the duty to 50% while avoiding the malfunction of the synchro.

  Moreover, you may further provide the detection part which envelope-detects the said induced voltage and outputs the said reference signal.

  With this configuration, the reference signal based on the induced voltage can be generated.

  The demodulator may further include a demodulator that detects an envelope of the induced voltage, binarizes the envelope detected signal, and outputs the signal as the carrier signal.

  With this configuration, the carrier signal can be demodulated based on the induced voltage.

  In order to achieve the above object, according to a second aspect of the present invention, a communication antenna that receives a carrier wave of a predetermined frequency transmitted from a reader / writer and generates an induced voltage corresponding to the carrier wave; A carrier wave detector that detects the induced voltage and outputs a detection signal; a voltage-controlled oscillator that is activated by the detection signal and generates an output signal; a reference signal detected by the induced voltage; and the output signal A phase comparison unit that outputs a phase difference signal corresponding to the phase difference, a loop filter that smoothes the phase difference signal and outputs a phase compensation voltage, and is demodulated based on the induced voltage A data processing unit that processes a carrier wave signal and outputs a control signal according to the processing based on the phase difference signal, and the phase compensation voltage is selectively input according to the control signal. A level holding unit that holds the phase compensation voltage and outputs the phase compensation voltage held in response to the control signal as an input voltage to the voltage controlled oscillation unit, and selects the output signal based on the control signal. An information processing apparatus including a modulation unit that outputs to the communication antenna and transmits a synchronized carrier wave from the communication antenna is provided.

  With this configuration, it is possible to prevent the occurrence of a communication disabled area within a communicable range in non-contact communication using a carrier wave.

  The information processing apparatus may be a portable communication apparatus.

  In order to achieve the above object, according to a third aspect of the present invention, a communication antenna that performs contactless communication using a reader / writer and a carrier wave, and the communication antenna that is generated in response to reception of the carrier wave A reference signal from which the induced voltage is detected is input, a phase synchronization unit that outputs an output signal that is synchronized in frequency and phase with the reference signal, a carrier signal that is demodulated from the induced voltage is processed, and the phase synchronization is performed. A data processing unit that outputs a control signal corresponding to the processing based on the synchronization in the unit, and selectively outputs the output signal to the communication antenna based on the control signal, and outputs a synchronized carrier wave from the communication antenna. A communication method used in an information processing apparatus including a modulation unit to transmit, the step of detecting reception of the carrier wave, and the detection of the detecting step The step of synchronizing the reference signal and the output signal in the phase synchronization unit according to the results, the step of processing the carrier signal according to the carrier detected in the detecting step, and the phase synchronization unit Determining the phase synchronization of the reference signal and the output signal in step, outputting the control signal according to the processing result of the processing step based on the determination result of the determining step, A step of keeping the frequency and phase of the output signal output from the phase synchronization unit constant according to the control signal, and an output signal whose frequency and phase are kept constant in the step of keeping constant according to the control signal And transmitting to the communication antenna and transmitting a synchronized carrier wave.

  By using such a method, it is possible to prevent the occurrence of a non-communication area within a communicable range in non-contact communication using a carrier wave.

  In order to achieve the above object, according to a fourth aspect of the present invention, a communication antenna that performs non-contact communication using a reader / writer and a carrier wave, and generated in response to reception of the carrier wave at the communication antenna. A reference signal from which the induced voltage is detected is input, a phase synchronization unit that outputs an output signal that is synchronized in frequency and phase with the reference signal, a carrier signal that is demodulated from the induced voltage is processed, and the phase synchronization is performed. A data processing unit that outputs a control signal corresponding to the processing based on the synchronization in the unit, and selectively outputs the output signal to the communication antenna based on the control signal, and outputs a synchronized carrier wave from the communication antenna. A program that can be used in an information processing apparatus including a modulation unit to transmit, the step of detecting reception of the carrier wave, and the step of detecting The step of synchronizing the reference signal and the output signal in the phase synchronization unit according to the detection result of the step, the step of processing the carrier signal according to the carrier detected in the detecting step, the phase synchronization unit Determining the phase synchronization between the reference signal and the output signal, outputting the control signal according to the processing result of the processing step based on the determination result of the determining step, the control signal The frequency and phase of the output signal output from the phase synchronization unit in accordance with the control signal, the output signal in which the frequency and phase are maintained constant in the step of maintaining the constant in accordance with the control signal A program for causing the computer to execute the steps of transmitting to the computer and transmitting the synchronized carrier wave It is subjected.

  With such a program, it is possible to prevent the occurrence of a non-communication area within a communicable range in non-contact communication using a carrier wave.

  In order to achieve the above object, according to a fifth aspect of the present invention, a communication antenna that receives a carrier wave of a predetermined frequency transmitted from a reader / writer and generates an induced voltage corresponding to the carrier wave; A carrier wave detector for detecting the induced voltage and outputting a detection signal; the detection signal and the input voltage are input; and an output signal having a frequency corresponding to the input voltage is output based on the detection signal Comparing the phase difference between the phase of the reference signal from which the induced voltage is detected and the phase of the output signal, and outputting a phase difference signal corresponding to the phase difference; and A data processing unit that processes a demodulated carrier wave signal based on the induced voltage and outputs a control signal corresponding to the processing based on the phase difference signal; and an AC component of the phase difference signal is removed, and a phase compensation voltage The The phase compensation voltage is selectively input according to the control signal and the phase compensation voltage is held according to the control signal, and the phase compensation voltage input according to the control signal is held. A level holding unit that selectively outputs a voltage as the input voltage to the voltage controlled oscillation unit, and the output signal is selectively output to the communication antenna based on the control signal, and a synchronized carrier wave is transmitted from the communication antenna. There is provided an information processing apparatus including a modulation unit.

  With this configuration, it is possible to prevent the occurrence of a communication disabled area within a communicable range in non-contact communication using a carrier wave.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the communication impossibility area | region within the communicable range can be prevented in non-contact communication using a carrier wave.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

(Non-contact communication system consisting of a conventional reader / writer and a conventional information processing device)
Before describing an information processing apparatus according to an embodiment of the present invention (an information processing apparatus including a transmission / reception circuit according to an embodiment of the present invention), first, between a conventional reader / writer and a conventional information processing apparatus Non-contact communication using a carrier wave will be described. FIG. 1 is an explanatory diagram showing a conventional non-contact communication system including a conventional reader / writer and a conventional information processing apparatus.

  Referring to FIG. 1, a conventional contactless communication system includes a conventional reader / writer 10 that mainly transmits a carrier wave, and a conventional information processing apparatus 50 that receives the carrier wave and responds.

[Reader / Writer 10]
The reader / writer 10 includes a carrier wave signal generation unit 12, a carrier wave transmission unit 14, a demodulation unit 16, and a control unit 18. Further, the reader / writer 10 is connected to, for example, the HostComputer 20 and can transmit a carrier wave signal in response to a transmission command from the HostComputer 20.

  The carrier signal generation unit 12 receives a carrier signal generation command from the control unit 18 and generates a carrier signal according to the carrier signal generation command.

  The carrier wave transmission unit 14 is configured by a resonance circuit including, for example, a coil L10 (inductor) having a predetermined inductance and a capacitor C10 having a predetermined capacitance, and corresponds to the carrier wave signal generated by the carrier wave signal generation unit 12. Send a carrier wave. Further, the carrier wave transmission unit 14 receives the response signal from the information processing device 50 by causing it to resonate at a predetermined resonance frequency. That is, the carrier wave transmission unit 14 serves as a communication antenna for the reader / writer 10.

  The demodulation unit 16 demodulates the response signal from the information processing device 50 by, for example, detecting the change in the amplitude of the voltage at the antenna end of the carrier wave transmission unit 14 by envelope detection and binarizing the detected signal.

  The control unit 18 is configured by, for example, an MPU (Micro Processing Unit) or the like, and transmits the data demodulated by the demodulation unit 16 to the Host Computer 20 or generates a carrier signal generation command based on the data demodulated by the demodulation unit 16. Various processes can be performed.

  The reader / writer 10 can demodulate a response signal from the information processing apparatus 50 by transmitting a carrier wave with the above-described configuration, for example.

[Information processing apparatus 50]
The information processing apparatus 50 includes an IC chip 52 that can receive a carrier wave and transmit a response signal by load modulation. The information processing apparatus 50 includes a control unit (not shown) configured by an MPU or the like and controls the entire information processing apparatus 50, and a storage unit (not shown) capable of storing applications, data, and the like used in the information processing apparatus 50. Or the like).

[Configuration of IC chip 52]
The IC chip 52 includes a communication antenna 54, a detection unit 56, a regulator 58 (Regulator), a filter unit 60, a demodulation unit 62, a data processing unit 64, and a load modulation unit 66. The IC chip 52 includes a ROM 68 in which control data such as a program used by the data processing unit 64 and calculation parameters are recorded, and a RAM 70 that primarily stores programs executed by the data processing unit 64, calculation results, execution states, and the like. A recording medium 72 capable of storing data processed by the data processing unit 64 can be provided. The data processing unit 64, the ROM 68, the RAM 70, and the recording medium 72 are connected by, for example, a bus as a data transmission path.

  The communication antenna 54 includes a resonance circuit including a coil (inductor) L11 having a predetermined inductance and a capacitor C11 having a predetermined capacitance, and generates an induced voltage by electromagnetic induction in response to reception of a carrier wave. Then, the communication antenna 54 outputs a reception voltage obtained by resonating the induced voltage at a predetermined resonance frequency. Here, the resonance frequency in the communication antenna 54 is set according to the frequency of the carrier wave such as 13.56 MHz, for example. With the above configuration, the communication antenna 54 can receive a carrier wave and can transmit a response signal transmitted by load modulation performed by the load modulation unit 66.

  The detector 56 rectifies the received voltage output from the communication antenna 54. Here, the detection unit 56 includes, for example, a diode D10 and a capacitor C12.

  The regulator 58 smoothes and constants the received voltage and outputs a drive voltage to the data processing unit 64. Here, the regulator 58 uses the direct current component of the received voltage as the drive voltage.

  The filter unit 60 is constituted by, for example, a high-pass filter including a capacitor C13 and a resistor R10, and filters the received voltage.

  The demodulator 62 demodulates the received voltage output from the filter unit 60 and extracts data corresponding to the carrier signal included in the carrier wave. Here, the demodulator 62 extracts the AC component of the received voltage as data.

  The data processing unit 64 processes the data demodulated by the demodulating unit 62 by using the drive voltage output from the regulator 58 as a power source. Here, the data processing unit 64 is configured by an MPU, for example.

  The load modulation unit 66 includes, for example, a load Z and a transistor Tr, and performs load modulation according to the processing result of the data processing unit 64, for example. Here, when load modulation is performed in the load modulation unit 66, the impedance of the information processing apparatus 50 as viewed from the reader / writer 10 changes. The reader / writer 10 detects the change in the impedance by using, for example, the change in the amplitude of the voltage at the antenna end of the carrier wave transmission unit 14, thereby receiving the response signal transmitted from the information processing apparatus 50 to the reader / writer 10. Can be received.

  The information processing apparatus 50 performs, for example, data processing based on the carrier wave transmitted from the reader / writer 10 with the above-described configuration, and returns a response signal.

  As described with reference to FIG. 1, in the conventional contactless communication system, the reader / writer 10 transmits a carrier wave, and the reader / writer 10 generates a carrier wave transmission unit 14 generated by load modulation in the information processing apparatus 50. The response signal from the information processing device 50 is demodulated by detecting the change in the amplitude of the voltage at the antenna end of the antenna. Therefore, in the conventional contactless communication system, contactless communication using a carrier wave between the reader / writer 10 and the information processing apparatus 50 is established.

[Problems in conventional non-contact communication systems]
However, the conventional reader / writer 10 may not be able to communicate within the communicable range as described above. Then, next, the problem in the conventional non-contact communication system is demonstrated.

  FIG. 2 is a first explanatory diagram for explaining a problem in the conventional contactless communication system. 2 shows the communication antenna of the reader / writer 10 when load modulation is not performed in the information processing apparatus 50 (load modulation OFF) and when load modulation is performed in the information processing apparatus 50 (load modulation ON). The amplitude of the voltage in (carrier wave transmission part 14) is shown. FIG. 3 is a second explanatory diagram for explaining a problem in the conventional non-contact communication system, and the correct answer rate of response data obtained by demodulating the response signal transmitted from the information processing device 50 in the reader / writer 10. Is shown.

  Referring to FIG. 2, the voltage at the communication antenna of the reader / writer 10 is obtained when load modulation is not performed in the information processing apparatus 50 (load modulation OFF) and when load modulation is performed in the information processing apparatus 50 ( It can be seen that the load modulation changes. This is because a demagnetizing field in the opposite direction to the magnetic field transmitted by the reader / writer 10 is generated from the information processing apparatus 50 by the information processing apparatus 50 performing load modulation (transmission of a response signal from the information processing apparatus 50). This is because the communication antenna of the reader / writer 10 receives the demagnetizing field.

  As described above, the conventional reader / writer 10 receives response data from a response signal received using a change in the amplitude of a voltage generated in the communication antenna (carrier wave transmission unit 14) by ON / OFF of load modulation in the information processing apparatus 50. Is demodulated. However, as shown in FIG. 2A, the voltage generated in the communication antenna of the reader / writer 10 may not change before and after the load modulation in the information processing apparatus 50 is turned off and on. Here, the carrier wave transmitted by the reader / writer 10 is, for example, a predetermined frequency such as 13.56 MHz (hereinafter, the predetermined frequency of the carrier wave output by the conventional reader / writer 10 and the reader / writer according to the embodiment of the present invention). (It is referred to as “output carrier frequency.”) Although it has f0, it may not be resonated at the output carrier frequency due to various factors (that is, the output carrier frequency f0 and the resonance frequency fc for reception may be shifted). The above factors include, for example, the antenna size and the number of turns of the communication antenna (carrier transmission unit 14) of the reader / writer 10 and the communication antenna 54 of the information processing apparatus 50, and the communication antenna (carrier transmission of the reader / writer 10). Part 14) and a change in the coupling coefficient depending on the distance between the antennas of the communication antenna 54 of the information processing apparatus 50.

  In the above case, the reader / writer 10 cannot demodulate even though the response signal transmitted from the information processing apparatus 50 is received. Therefore, as shown in FIG. 3, even when the communication distance between the information processing device 50 and the reader / writer 10 is short, the demodulated response data is a region where the correct answer rate is extremely low (hereinafter, “communication impossible region”). Will be born). Here, the distance a shown in FIG. 3 is a communication distance between the information processing apparatus 50 and the reader / writer 10 and indicates that the distance a is in the state shown in FIG.

  As shown in FIGS. 2 and 3, the conventional reader / writer 10 may not be able to demodulate the response signal transmitted from the information processing apparatus 50, so that a communication disabled area occurs even within the communicable range. End up. Therefore, the conventional non-contact communication system cannot eliminate the non-communication area and cannot stabilize the communication between the reader / writer 10 and the information processing apparatus 50.

(Problem solving approach according to embodiments of the present invention)
As described above, in a conventional non-contact communication system, a non-communication area occurs, so that a user holds an information processing device such as a mobile phone mounted with an IC card or a non-contact IC chip on a reader / writer (information Even if the processing device is positioned within the communication range of the reader / writer, communication may not be performed. In the above case, the user must perform an operation of holding the information processing apparatus over the reader / writer again. Therefore, the conventional contactless communication system imposes an excessive burden on the user.

  Therefore, in the contactless communication system according to the embodiment of the present invention, communication is stabilized by preventing the occurrence of a communication disabled area. Thereby, the non-contact communication system which concerns on embodiment of this invention can remove the above burdens which the conventional non-contact communication system imposed on the user.

[Problem solving approach]
The contactless communication system according to the embodiment of the present invention supports an information processing apparatus that receives a carrier wave transmitted from a reader / writer and responds in response to reception of the carrier wave in order to prevent the occurrence of a non-communication area. I do. More specifically, the information processing apparatus according to the embodiment of the present invention synchronizes the carrier wave transmitted by the reader / writer, while the conventional information processing apparatus 50 responds by load modulation. A response to the reader / writer is performed by transmitting the synchronized sync carrier wave by itself. Note that the information processing apparatus according to the embodiment of the present invention can also transmit a synchronized carrier wave whose phase is shifted from that of the carrier wave transmitted by the reader / writer.

The information processing apparatus according to the embodiment of the present invention responds by transmitting a synchronized carrier wave to the reader / writer by the following processes (1) to (3).
(1) Reception of carrier wave (2) Generation of output signal in which frequency and phase are synchronized with reference signal (described later) based on carrier wave (3) Selective transmission of synchronized carrier wave based on output signal (transmission of response signal)

  FIG. 4 is an explanatory diagram for explaining the effect of the problem solving approach according to the embodiment of the present invention. FIG. 4 shows the reader / writer when load modulation is not performed in the information processing apparatus (load modulation OFF) and when load modulation is performed in the information processing apparatus (load modulation ON), as in FIG. The amplitude of the voltage in the communication antenna is shown.

  Referring to FIG. 4, the voltage at the communication antenna of the reader / writer changes between when the information processing device is not modulated (modulation OFF) and when the information processing device is modulated (modulation ON). I understand that Here, since the information processing apparatus according to the embodiment of the present invention transmits a response signal by transmitting a synchronized carrier wave, the voltage at the antenna end of the reader / writer according to the embodiment of the present invention is in the case of modulation OFF. The waveform of slid upward or downward is shown. Here, as shown in FIG. 4, in the reader / writer according to the embodiment of the present invention, the voltage generated in the communication antenna of the reader / writer does not change before and after the modulation is turned off and on in the information processing apparatus (that is, 2 does not occur. That is, the non-communication area does not occur in the non-contact communication system according to the embodiment of the invention.

  Therefore, in the contactless communication system according to the embodiment of the present invention, the information processing apparatus selectively transmits a synchronized carrier wave to prevent the occurrence of a non-communication area within the communicable range, and the reader / writer and the information Communication with the processing device can be stabilized.

(Non-contact communication system according to an embodiment of the present invention)
Hereinafter, the non-contact communication system according to the embodiment of the present invention will be described in more detail. FIG. 5 is an explanatory diagram showing a contactless communication system according to an embodiment of the present invention.

[Reader / Writer 100]
The reader / writer 100 includes a carrier wave signal generation unit 102, a carrier wave transmission unit 104, a demodulation unit 106, and a control unit 108. Further, the reader / writer 100 is connected to, for example, the HostComputer 120 and can transmit a carrier wave signal in response to a transmission command from the HostComputer 120.

  The reader / writer 100 also stores a ROM (Read Only Memory; not shown) in which control data such as a program used by the control unit 108 and calculation parameters are recorded, a program executed by the control unit 108, and the like. RAM (Random Access Memory; not shown), a register (register; not shown) for holding the calculation result and execution state in the control unit 108, an encryption circuit (not shown) for encrypting communication, a reader A storage unit (not shown) that can store applications, data, and the like used in the writer 100, an interface (not shown) for connecting to the host computer 120 and other circuits, and the like may be provided. The reader / writer 100 connects each component by a bus as a data transmission path, for example.

  Here, examples of the storage unit (not shown) include a magnetic recording medium such as a hard disk and a non-volatile memory such as a flash memory. I can't. Examples of the interface include a UART (Universal Asynchronous Receiver Transmitter) and a network terminal, but are not limited to the above.

  The carrier signal generation unit 102 receives a carrier signal generation command from the control unit 108 and generates a carrier signal according to the carrier signal generation command. Here, in FIG. 5, an AC power supply is shown as the carrier wave signal generation unit 102, but the carrier wave signal generation unit 102 according to the embodiment of the present invention is not limited to the above, for example, ASK modulation (Amplitude Shift Keying) And a modulation circuit (not shown) for amplifying the output of the modulation circuit. Note that the carrier wave signal generated by the carrier wave signal generation unit 102 can include, for example, various processing instructions for the information processing device 150 and data to be processed, but is not limited thereto. For example, the carrier wave signal according to the embodiment of the present invention may be a signal for causing the carrier wave transmission unit 104 to generate a carrier wave that supplies power to the information processing apparatus 150 (that is, in this case, a reader / Writer 100 functions as a power transmission device).

  The carrier wave transmission unit 104 is constituted by a resonance circuit including, for example, a coil L0 (inductor) having a predetermined inductance and a capacitor C0 having a predetermined capacitance, and corresponds to the carrier wave signal generated by the carrier wave signal generation unit 102. Send a carrier wave. Further, the carrier wave transmission unit 104 receives the response signal from the information processing apparatus 150 by resonating at a predetermined resonance frequency. That is, the carrier wave transmission unit 104 serves as a communication antenna for the reader / writer 100.

  For example, the demodulation unit 106 demodulates the response signal from the information processing device 150 by performing envelope detection on the amplitude change of the voltage at the antenna end of the carrier wave transmission unit 104 and binarizing the detected signal. Note that the means for demodulating the response signal in the demodulation unit 106 is not limited to the above, and for example, the response signal can be demodulated using the phase change of the voltage at the antenna end of the carrier wave transmission unit 104.

  The control unit 108 includes, for example, an MPU and transmits various data demodulated by the demodulation unit 106 to the HostComputer 120 or generates a carrier signal generation command based on the data demodulated by the demodulation unit 106. It can be performed.

  The reader / writer 100 can demodulate the response signal by transmitting a carrier wave with the above-described configuration and receiving the synchronized carrier wave transmitted from the information processing apparatus 150, for example.

[Information processing apparatus 150]
Next, the information processing apparatus 150 will be described. As described above, the information processing apparatus according to the embodiment of the present invention transmits a response signal by transmitting a synchronized carrier wave by itself. Therefore, hereinafter, an information processing apparatus including a transmission / reception circuit that receives a carrier wave transmitted from the reader / writer 100 and transmits a synchronized carrier wave will be described. In FIG. 5, each constituent element constituting the transmission / reception circuit of the information processing apparatus 150 is realized in the form of an IC chip, that is, each constituent element constituting the transmission / reception circuit by the information processing apparatus 150 is realized by an integrated circuit. Although not shown in the form, it is needless to say that the information processing apparatus according to the embodiment of the present invention can realize each component constituting the transmission / reception circuit in the form of an IC chip.

  Referring to FIG. 5, the information processing apparatus 150 includes a communication antenna 152, a detection circuit 154, a carrier wave detection circuit 156, a demodulation circuit 158, a PLL circuit 160 (Phase-Locked Loop Circuit), data, and the like. A processing circuit 162, a modulation circuit 164, a phase correction circuit 166, an amplification circuit 168, and a battery 170 are provided.

  Here, FIG. 5 illustrates a configuration including the battery 170 as a power source included in the information processing device 150, but the information processing device according to the embodiment of the present invention is not limited to the configuration including the battery 170. For example, the information processing apparatus according to the embodiment of the present invention is provided in the subsequent stage of a regulator (not shown) detection circuit 154 similar to the regulator 58 shown in FIG. 1 described above, and is generated in a communication antenna in response to reception of a carrier wave. By using a DC component of the induced voltage (or a reception voltage described later) as a drive voltage, power can be supplied to each component of the information processing apparatus. The information processing apparatus according to the embodiment of the present invention includes both a battery (first power supply) and a regulator (second power supply), and selectively supplies power to each component. You can also. For example, power may be supplied from a battery to a component (for example, an amplifier circuit) that consumes larger power, and power may be supplied from a regulator to another component (for example, a data processing circuit). However, since the basic concept of the present invention is to improve communication malfunctions due to the card side reply, it is based on the "energy" reply rather than the reply based on the card side impedance change as in the past. A basic configuration is provided with a power source such as.

  In addition, the information processing apparatus 150 includes a control unit (not shown) configured by an MPU or the like to control the entire information processing apparatus 150, or a ROM (program data used by the control unit, control data such as calculation parameters, etc.). (Not shown), a RAM (not shown) that primarily stores programs executed by the control unit, a register (not shown) that holds calculation results and execution states in the control unit, and applications used in the information processing apparatus 150 A storage unit (not shown) capable of storing data and the like, an interface (not shown) for connecting to other devices, and the like may be provided. For example, the information processing apparatus 150 can connect the data processing circuit 162 to each of the above-described constituent elements and between the above-described constituent elements by a bus as a data transmission path. The data processing circuit 162 can also function as the control unit (not shown).

  Here, as the storage unit (not shown), for example, a magnetic recording medium such as a hard disk, EEPROM (Electronically Erasable and Programmable Read Only Memory), flash memory, MRAM (Magnetoresistive Random Access Memory), FeRAM (Ferroelectric Random Access) Non-volatile memories such as Memory) and PRAM (Phase change Random Access Memory) are mentioned, but not limited to the above. Further, examples of the interface include UART and network terminal, but are not limited to the above.

  The communication antenna 152 includes a resonance circuit including a coil (inductor) L1 having a predetermined inductance and a capacitor C1 having a predetermined capacitance, and generates an induced voltage by electromagnetic induction in response to reception of a carrier wave. Then, the communication antenna 152 outputs a reception voltage obtained by resonating the induced voltage at a predetermined resonance frequency. Here, the resonance frequency in the communication antenna 152 can be set according to the frequency of the carrier wave such as 13.56 MHz, for example. Needless to say, the communication antenna according to the embodiment of the present invention may be configured not to include the capacitor C1, that is, the communication antenna may not be configured by a resonance circuit. In the above case, an induced voltage generated in response to reception of a carrier wave is output from the communication antenna.

  The communication antenna 152 also functions as a transmission antenna that transmits a synchronized carrier wave in accordance with an output signal output from the amplifier circuit 168. The output signal will be described later.

  The detection circuit 154 rectifies (detects) the reception voltage output from the communication antenna 152, and outputs a reference signal based on the carrier wave transmitted from the reader / writer 100 to the PLL circuit 160. Here, the reference signal is a signal serving as a reference for the frequency and phase of an output signal output from a PLL circuit 160 described later. In addition, the detection circuit 154 can be configured with, for example, a diode and a capacitor, but is not limited thereto. The detection circuit 154 can also include an AGC (Automatic Gain Control) and output a reference signal having a predetermined gain level.

  Carrier wave detection circuit 156 detects the reception voltage output from communication antenna 152, and outputs a detection signal to PLL circuit 160 when the reception voltage is detected. Here, the carrier wave detection circuit 156 can be configured by a band-pass filter that passes only a signal in a specific frequency band such as 13.56 MHz and attenuates signals in other bands, for example. However, it is not limited to the above.

  The demodulation circuit 158 demodulates the carrier wave signal transmitted from the reader / writer 100 using the carrier wave by detecting the received voltage output from the communication antenna 152 by envelope detection and binarizing the detected signal.

  The PLL circuit 160 outputs an output signal having the same frequency and phase as the reference signal output from the detection circuit 154 to the modulation circuit 164. Here, the PLL circuit 160 can output an output signal having the same frequency and phase as the reference signal by feedback control. In the following, it is said that the PLL has “locked (synchronized)” that the frequency and phase of the output signal match the frequency and phase of the reference signal.

  The PLL circuit 160 holds and outputs an output signal when the PLL is locked by feedback control. Here, the hold of the output signal means that the output signal in the locked state is output without depending on the reference signal even when the reference signal changes after locking due to an external factor or the like. Unlike a so-called general PLL circuit, the PLL circuit 160 according to the embodiment of the present invention can hold and output an output signal by selectively performing feedback control.

  The PLL circuit 160 transmits a PLL lock detection signal indicating that the PLL is locked to the data processing circuit 162 according to the lock of the PLL, and also according to a control signal (described later) output from the data processing circuit 162. Hold the output signal. Therefore, the hold of the output signal in the PLL circuit 160 is controlled by the data processing circuit 162.

[Configuration of PLL Circuit 160]
Here, the configuration of the PLL circuit 160 according to the embodiment of the present invention will be described. The PLL circuit 160 includes a voltage controlled oscillation circuit 180 (Voltage Controlled Oscillator; hereinafter referred to as “VCO”), a frequency dividing circuit 182, a phase comparison circuit 184, a loop filter 186, and a level holding circuit 188. Is provided.

  The voltage controlled oscillation circuit 180 outputs an output signal having a frequency corresponding to the input voltage that has been input. The voltage control oscillation circuit 180 receives a detection signal output from the carrier wave detection circuit 156, and can selectively output an output signal when the detection signal is input. Here, the voltage controlled oscillation circuit 180 can be configured with a varicap, for example, but is not limited thereto.

  The frequency dividing circuit 182 divides the output signal output from the voltage controlled oscillation circuit 180 by two. Needless to say, the frequency division in the frequency dividing circuit according to the embodiment of the present invention is not limited to the frequency division by two.

  5 illustrates a configuration in which the information processing apparatus 150 includes the frequency dividing circuit 182. However, the embodiment of the present invention is not limited to the above. For example, the information processing apparatus according to the embodiment of the present invention may be configured not to include the frequency dividing circuit 182. Here, the frequency dividing circuit 182 prevents a malfunction (synchronous malfunction) of the PLL circuit due to, for example, a jump of a carrier wave to the circuit. Further, the frequency dividing circuit 182 serves to reduce the duty difference between the output signal output from the voltage controlled oscillation circuit 180 and the reference signal output from the detection circuit 154, and to more reliably determine the phase difference. You can also.

  The phase comparison circuit 184 outputs a phase difference signal corresponding to the phase difference between the phase of the reference signal output from the detection circuit 154 and the phase of the divided output signal output from the frequency dividing circuit 182 and the loop filter 186 and The data is output to the data processing circuit 162. Hereinafter, the frequency-divided output signal output from the frequency dividing circuit 182 is referred to as “output signal” without being particularly distinguished from the output signal output from the voltage-controlled oscillation circuit 180. Hereinafter, the phase difference signal output to the data processing circuit 162 is referred to as a “PLL lock detection signal”. Here, since the phase comparison circuit 184 outputs a PLL lock detection signal corresponding to the phase difference between the reference signal and the output signal, the data processing circuit 162 uses the PLL lock detection signal to lock the PLL. It can be determined whether or not. The phase comparison circuit 184 can be configured using, for example, ExOR, but is not limited thereto.

  The loop filter 186 outputs a phase compensation voltage by removing the AC component of the phase difference signal output from the phase comparison circuit 184. The PLL circuit 160 includes the loop filter 186, so that phase compensation in feedback control can be performed. Here, the loop filter 186 can be constituted by, for example, a low-pass filter that passes only a signal having a frequency equal to or lower than the cutoff frequency and attenuates a signal having a frequency higher than the cutoff frequency. Not limited to.

  The level holding circuit 188 includes a level holding switch 190 (second switch) and a capacitor C2 having a predetermined capacitance. The level holding circuit 188 is not limited to the above as long as it can hold the level, and may be, for example, an “A / D, D / A conversion circuit” and a “memory (memory device)” that stores digital values thereof. .

  The level holding switch 190 is turned on / off according to the control signal output from the data processing circuit 162, and selectively takes in the phase compensation voltage. Here, the on / off operation of the level holding switch 190 is the reverse of the on / off operation in the modulation circuit 164 described later. That is, the level holding switch 190 is turned off when the modulation circuit 164 is on, and the level holding switch 190 is turned on when the modulation circuit 164 is off. The level holding switch 190 can be configured by, for example, a pMOS transistor in which a control signal is applied to the control electrode, but is not limited to the above, and can also be configured by an nMOS transistor.

  Capacitor C2 holds the phase compensation voltage output from level holding switch 190. Hereinafter, the phase compensation voltage held in the capacitor C2 is referred to as “holding voltage”.

  Further, the level holding circuit 188 selectively selects the phase compensation voltage output from the loop filter 186 or the holding voltage held in the capacitor C2 as an input voltage input to the voltage controlled oscillation circuit 180 according to the control signal. Output to.

  Here, an example of the relationship between the control signal, the operation of the level holding switch 190, and the output input voltage according to the embodiment of the present invention is shown. In the following description, it is assumed that the level holding switch 190 is composed of a pMOS transistor.

[I] When the control signal is at a low level (Low) When the control signal is at a low level, the level holding switch 190 is turned on. Accordingly, the phase compensation voltage output from the loop filter 186 is input to the level holding circuit 188, and the phase compensation voltage is output from the level holding circuit 188. The capacitor C2 holds the input phase compensation voltage.

[Ii] When the control signal is at a high level (High) When the control signal is at a high level, the level holding switch 190 is turned off. Accordingly, the phase compensation voltage output from the loop filter 186 is not input to the level holding circuit 188, and the holding voltage held in the capacitor C2 is output. Therefore, the voltage controlled oscillation circuit 180 to which the holding voltage is input outputs an output signal having the same frequency as that of the holding voltage, so that the output signal is held.

  The level holding circuit 188 can output the phase compensation voltage output from the loop filter 186 or the holding voltage held in the capacitor C2 to the voltage controlled oscillation circuit 180 in accordance with the control signal as described above.

  Further, when the level holding circuit 188 includes the “A / D, D / A conversion circuit” and a “memory (memory device)” that stores the digital value, for example, a new one is generated each time. Depending on whether a digital value is used or a value stored in a “memory (memory device)” is used, the same function as that of the pMOS transistor (or nMOS transistor) and the capacitor C2 can be achieved. The operation when the level holding circuit 188 includes the “A / D, D / A conversion circuit” and the “memory (memory device)” that stores the digital value is not limited to the above. Needless to say.

  The PLL circuit 160 includes the voltage control oscillation circuit 180, the frequency dividing circuit 182, the phase comparison circuit 184, the loop filter 186, and the level holding circuit 188, so that the reference signal, frequency, and phase output from the detection circuit 154 are provided. Can hold the same output signal and output it to the modulation circuit 164.

  The data processing circuit 162 performs data processing on the carrier wave signal demodulated by the demodulation circuit 158. Here, the data processing circuit 162 can be configured by an MPU, for example.

  Further, when the PLL lock detection signal transmitted from the phase comparison circuit 184 is input to the data processing circuit 162 and the PLL lock detection signal indicates that the PLL is locked (the phase difference indicated by the PLL lock detection signal is 0 ( When zero), a control signal corresponding to the data processing result is output. Here, the control signal output from the data processing circuit 162 is input to the level holding switch 190 of the PLL circuit 160 and the modulation circuit 164, the switching operation of the level holding switch 190 of the PLL circuit 160, and a modulation circuit 164 described later. Used to control modulation in Therefore, the data processing circuit 162 outputs the control signal to hold the output signal output from the PLL circuit 160 (the output signal output from the voltage controlled oscillation circuit 180), and uses the held output signal. Can control the modulation.

  The modulation circuit 164 receives the control signal output from the data processing circuit 162 and the output signal output from the PLL circuit 160, and selectively outputs the output signal to the phase correction circuit 166 according to the control signal. The modulation circuit 164 includes, for example, a switch (first switch) and performs an on / off operation according to a control signal. Here, the on / off operation in the modulation circuit 164 is the reverse of the on / off operation in the level holding switch 190. Needless to say, the modulation circuit 164 is not limited to an nMOS transistor in which a control signal is applied to the control electrode, for example, and may be a pMOS transistor, for example.

  The phase correction circuit 166 corrects the phase of the output signal that is selectively output from the modulation circuit 164 according to the control signal. Here, the significance of the information processing apparatus 150 correcting the phase of the output signal will be described.

  As described above, the information processing apparatus 150 includes the PLL circuit 160 and transmits an output signal in which the reference signal based on the carrier wave transmitted from the reader / writer 100 is synchronized with the frequency and phase. The information processing apparatus 150 transmits a response signal by transmitting a synchronized carrier wave based on the output signal. However, in the information processing apparatus 150, for example, the phase of the signal for transmitting the synchronized carrier wave transmitted to the communication antenna 152 due to the delay of the output signal due to wiring or the like, and the phase of the output signal output from the PLL circuit 160 There may be a case where the deviation occurs.

  Here, a problem will be described in the case where there is a difference between the phase of the signal for transmitting the synchronized carrier wave transmitted to the communication antenna 152 and the phase of the output signal output from the PLL circuit 160.

  FIG. 6 is an explanatory diagram for explaining a problem in a case where there is a difference between the phase of the signal for sync carrier transmission and the phase of the output signal according to the embodiment of the present invention. FIG. 6A to FIG. 6D each represent a carrier wave transmitted from the reader / writer 100, a synchronized carrier wave transmitted from the information processing device 150, and a combined wave of the carrier wave and the synchronized carrier wave in vector representation. FIG. 6 indicates the combined wave detected by the signal detection circuit in the demodulator 106 of the reader / writer 100. When the information processing apparatus 150 controls the transmission timing of the synchronized carrier wave, the reader / writer 100 can obtain the combined wave shown in FIG. Hereinafter, the problem in the case where the phase of the signal for the synchronized carrier transmission and the phase of the output signal are shifted will be described with reference to FIG. 6. This problem is related to various readers equipped with a general signal detection circuit. / Can also occur in the writer. In the following, the phase difference between the carrier wave and the sync carrier wave is represented by “θ”.

(1) FIG. 6 (a): First example of communicable state Referring to FIG. 6 (a), when θ is 0 ° <θ <90 °, the difference in level between the carrier wave and the synthesized wave It can be seen that This difference in level is regarded as transmission of a response signal from the information processing apparatus 150 in the reader / writer 100, and the reader / writer 100 can demodulate the response signal by ASK modulation. Therefore, communication between the reader / writer 100 and the information processing apparatus 150 is normally performed.

(2) FIG. 6 (b): Second example of communicable state Referring to FIG. 6 (a), when θ is 180 ° <θ <270 °, it is combined with a carrier wave as in FIG. 6 (a). It can be seen that there is a level difference between the waves. Therefore, also in the case of FIG. 6B, communication between the reader / writer 100 and the information processing apparatus 150 is normally performed.

(3) FIG. 6 (c): First example in a state where communication is not possible Referring to FIG. 6 (c), when θ is 90 ° <θ <180 ° and the sync carrier is small (ie, reader / writer) 100 and the information processing apparatus 150 (when the communication distance is long), it can be seen that there is no level difference between the carrier wave and the synthesized wave. At this time, since the reader / writer 100 cannot detect the response signal from the information processing apparatus 150, it cannot demodulate the response signal by ASK modulation. Therefore, the reader / writer 100 and the information processing apparatus 150 cannot communicate normally.

(4) FIG. 6 (d): Second example in a state where communication is not possible Referring to FIG. 6 (d), when θ is θ = 180 ° and the sync carrier is large (that is, information with the reader / writer 100) When the communication distance with the processing device 150 is short), it can be seen that there is no level difference between the carrier wave and the synthesized wave. At this time, the reader / writer 100 cannot detect a response signal from the information processing apparatus 150, as in FIG. Therefore, the reader / writer 100 and the information processing apparatus 150 cannot communicate normally.

  As shown in FIG. 6, when the phase difference between the carrier wave and the sync carrier wave and the communication distance between the reader / writer 100 and the information processing apparatus 150 are predetermined, the reader / writer 100 and the information processing apparatus 150 communicate with each other. There are cases where it cannot be done. That is, in the above case, a communication impossible area occurs.

  Accordingly, when an unintentional shift occurs between the phase of the signal for sync carrier transmission and the phase of the output signal output from the PLL circuit 160 in the information processing apparatus 150, the reader / writer 100 is used as described above. And the information processing apparatus 150 may not be able to communicate with each other.

  Therefore, the information processing apparatus 150 according to the embodiment of the present invention includes a phase correction circuit 166 in order to prevent a non-communication area from being generated even if an unintended shift due to wiring or the like occurs. More specifically, the phase correction circuit 166 corrects the phase of the output signal to a phase where no communication disabled area occurs by intentionally delaying the phase of the output signal.

  Here, the relationship between the carrier wave and the sync carrier wave in which the communication disabled area may occur is shown. FIG. 7 is an explanatory diagram showing a relationship between a carrier wave and a sync carrier wave that can cause a communication disabled area. Here, FIG. 7 shows the phase difference between the carrier wave and the sync carrier wave when there is no level difference between the carrier wave and the synthesized wave as shown in FIGS. 6 (c) and 6 (d). It is the figure which showed the relationship.

  As shown in FIG. 7, when the phase difference θ between the carrier wave and the sync carrier wave is 90 ° ≦ θ ≦ 270 °, it can be seen that there is no level difference between the carrier wave and the synthesized wave. That is, in the above case, there is a possibility that a non-communication area may occur. Conversely, when the phase difference θ between the carrier wave and the sync carrier wave is −90 ° <θ <90 °, a difference in level occurs between the carrier wave and the synthesized wave. Will not occur.

  Therefore, the phase correction circuit 166 according to the embodiment of the present invention has the phase of the input output signal so that the phase difference θ between the carrier wave and the sync carrier wave is in the range of −90 ° <θ <90 °. Is delayed by the delay amount. Here, the delay amount by which the phase correction circuit 166 delays the phase of the output signal includes the phase of the output signal output from the PLL circuit 160 when the phase correction circuit is not provided, and the synchronized carrier wave transmitted to the communication antenna 152. This can be determined by measuring in advance the phase difference of the signal for transmission. In addition, as the phase correction circuit 166, for example, an integration circuit may be used, but is not limited thereto.

  The amplifier circuit 168 amplifies the output signal with the phase corrected output from the phase correction circuit 166 and outputs the amplified signal to the communication antenna 152. When the information processing apparatus 150 includes the amplifier circuit 168 as a constituent element of the transmission / reception circuit, it is possible to increase the possibility that the synchronization carrier wave having a larger gain can be transmitted and communication can be normally performed.

  A diode D1 and a capacitor C3 are provided between the amplifier circuit 168 and the communication antenna 152, and an amplified output signal output from the amplifier circuit 168 is rectified and transmitted to the communication antenna 152. When an output signal (amplified output signal output from the amplifier circuit 168) is input to the communication antenna 152, a synchronized carrier wave is transmitted from the communication antenna 152.

  The battery 170 supplies power to each component constituting the transmission / reception circuit of the information processing apparatus 150 and other components (for example, a storage unit (not shown)) of the information processing apparatus 150. 5 illustrates a configuration in which the battery 170 supplies power to the data processing circuit 162, the amplifier circuit 168, and the voltage controlled oscillation circuit 180, the configuration of the information processing apparatus according to the embodiment of the present invention. Needless to say, is not limited to the above. Further, as described above, the information processing apparatus according to the embodiment of the present invention includes a regulator (not shown), and obtains power from a carrier wave transmitted from the reader / writer 100 and supplies the power to each component. it can.

  For example, the information processing apparatus 150 includes a transmission / reception circuit having the configuration shown in FIG. 5 to receive a carrier wave transmitted from the reader / writer 100 (reception of a carrier wave signal) and send a synchronized carrier wave by itself (reply ( Response signal transmission).

[Communication method]
Here, the communication method according to the embodiment of the present invention will be described. FIG. 8 is a flowchart showing an example of the communication method according to the embodiment of the present invention. Here, FIG. 8 shows a communication method in the information processing apparatus 150.

  The information processing apparatus 150 detects whether a carrier wave has been detected (S100). The processing in step S100 can be performed by the detection circuit 154, the carrier detection circuit 156, and the demodulation circuit 158 based on the induced voltage generated in response to reception of the carrier wave in the communication antenna 152.

  When the carrier wave is detected in step S100, the information processing apparatus 150 demodulates the carrier wave signal and performs data processing on the carrier wave signal (S102). Here, the demodulation in step S102 can be performed by the demodulation circuit 158, and the data processing can be performed by the data processing circuit 162.

  Further, when a carrier wave is detected in step S100, the information processing apparatus 150 activates a PLL (Phase-Locked Loop) (S104). The activation of the PLL in step S104 is performed, for example, when the detection signal output from the carrier wave detection circuit 156 is transmitted to the voltage control oscillation circuit 180 constituting the PLL circuit 160, and the output signal is output from the voltage control oscillation circuit 180. Is done.

  When the PLL is activated in step S104, the information processing apparatus 150 determines whether the PLL is locked (S106). If it is not determined in step S106 that the PLL is locked, the process is not advanced until it is determined that the PLL is locked. Here, the processing in step S106 can be performed by the data processing circuit 162 based on the PLL lock detection signal transmitted from the PLL circuit 160.

  If it is determined in step S106 that the PLL has been locked, the information processing apparatus 150 determines whether it is time to modulate (S108). The processing in step S108 can be performed by the data processing circuit 162 based on the result of the data processing in step S102. Although FIG. 8 illustrates an example in which steps S104 and S106 are performed after step S102, the communication method according to the embodiment of the present invention is not limited to the above. For example, the communication method according to the embodiment of the present invention can perform the processes of Step S102 and Steps S104 and S106 in parallel.

  If it is determined in step S108 that it is not the timing for modulation, the information processing apparatus 150 determines whether a carrier wave is detected (S110). If it is determined in step S110 that a carrier wave has been detected, the process of step S108 is performed again. If it is not determined in step S110 that a carrier wave has been detected, the process from step S100 is performed again.

  If it is determined in step S108 that the modulation timing is reached, the information processing apparatus 150 turns on the level holding switch 190 to hold the level (S112). Here, the processing of step S112 corresponds to holding the output of the VCO of the PLL. Further, the processing in step S112 can be performed by the data processing circuit 162 transmitting the control signal to the voltage controlled oscillation circuit 180 (VCO) that constitutes the PLL circuit 160. Here, the output of the VCO corresponds to an output signal output from the voltage controlled oscillation circuit 180.

  When the output of the VCO is held in step S112, the information processing apparatus 150 responds by transmitting a synchronized carrier wave (S114). Here, the transmission of the synchronized carrier wave in step S114 corresponds to the transmission of a response signal from the information processing apparatus 150. Further, the processing in step S114 can be performed by controlling the output of the output signal from the modulation circuit 164 by the data processing circuit 162 selectively applying the control signal to the modulation circuit 164.

  When the synchronized carrier wave is transmitted in step S114, the information processing apparatus 150 releases the output of the VCO (S116). Then, the information processing apparatus 150 determines whether or not the PLL has been relocked (S118). If it is not determined in step S118 that the PLL has been re-locked, the information processing apparatus 150 does not proceed. Here, the processing in step S118 can be performed by the data processing circuit 162 as in step S106.

  If it is determined in step S118 that the PLL has been re-locked, the information processing apparatus 150 determines whether all response signals have been transmitted (S120). The processing in step S120 can be performed by the data processing circuit 162 based on the result of the data processing in step S102.

  If it is not determined in step S120 that all response signals have been transmitted, the information processing apparatus 150 repeats the processing from step S110.

  If it is determined in step S120 that all response signals have been transmitted, the information processing apparatus 150 stops the PLL and VCO (S122), and ends communication.

  The information processing apparatus 150 receives a carrier wave transmitted from the reader / writer 100 (reception of a carrier wave signal) by using, for example, the communication method shown in FIG. 8, and returns a response (response signal) by transmitting a synchronized carrier wave itself. Send). Note that the communication method shown in FIG. 8 is not a method that is completed once it is performed, and it goes without saying that the information processing apparatus 150 can use the communication method shown in FIG. 8 every time it receives a carrier wave signal. .

  In the contactless communication system according to the embodiment of the present invention, as described above, the information processing apparatus 150 that has received the carrier wave transmitted from the reader / writer 100 performs communication by transmitting the synchronized carrier wave by itself. Then, next, in order to show more concretely the communication in the non-contact communication system which concerns on embodiment of this invention mentioned above, the outline of the communication in the non-contact communication system which concerns on embodiment of this invention is shown.

  FIG. 9 is an explanatory diagram for explaining an outline of communication in the contactless communication system according to the embodiment of the present invention. Here, FIG. 9A shows a carrier wave detection waveform in the reader / writer 100 (a voltage waveform of the demodulation unit 106 in the communication antenna (carrier wave transmission unit 104) of the reader / writer 100). 9B shows the PLL operation in the information processing apparatus 150 together with the waveform of the output signal of the PLL circuit 160, and FIG. 9C shows the output waveform of the synchronized carrier wave transmitted from the information processing apparatus 150. . The outline of communication in the contactless communication system according to the embodiment of the present invention will be described below based on the PLL operation shown in FIG.

  When the carrier wave is detected (A in FIG. 9), the information processing apparatus 150 activates the PLL. When the PLL is activated, an output signal is output from the VCO (voltage controlled oscillation circuit 180) of the PLL circuit 160, and the PLL is locked (B in FIG. 9).

  When the PLL is locked, the information processing apparatus 150 performs modulation according to the result of data processing (C and D in FIG. 9). Here, C in FIG. 9 shows a state in which the modulation is off, and D in FIG. 9 shows a state in which the modulation is on.

  When the modulation shown in FIG. 9D is on, the output (output signal) of the VCO is held, and a signal based on the held VCO output is transmitted to the communication antenna 152 of the information processing apparatus 150. Therefore, the information processing apparatus 150 can output a synchronized carrier wave as shown in FIG. FIG. 9 shows an example in which the phase of the VCO output (output signal) is corrected by the phase correction circuit 166.

  At this time, the demodulator 106 of the reader / writer 100 that receives the transmission of the synchronized carrier wave from the information processing apparatus 150 as shown in FIG. 9C, as shown in FIG. 9A according to the reception of the synchronized carrier wave. A change in amplitude occurs.

  The above amplitude change corresponds to a waveform in which the waveform in the case of modulation OFF shown in FIG. 4 is slid upward. That is, the reader / writer 100 does not generate a non-communication area as indicated by point A in FIG. Therefore, the reader / writer 100 can demodulate the response signal transmitted from the information processing apparatus 150 using the amplitude change (ASK modulation).

  Similarly, when the information processing apparatus 150 performs modulation according to the data processing result (E, F, and G in FIG. 9), a synchronized carrier wave is transmitted from the information processing apparatus 150, and the reader / writer 100 performs ASK modulation. To demodulate the response signal.

  Then, when the transmission of the response signal is completed, the information processing apparatus 150 turns off the PLL and ends the communication (F in FIG. 9).

  As illustrated in FIG. 9, in the contactless communication system according to the embodiment of the present invention, the information processing device 150 receives a carrier wave transmitted from the reader / writer 100, and the synchronization according to the carrier wave received by the information processing device 150 is performed. By transmitting the carrier wave, a response from the information processing apparatus 150 to the reader / writer 100 is performed. Therefore, the contactless communication system according to the embodiment of the present invention can perform normal communication between the reader / writer 100 and the information processing apparatus 150.

  As described above, the contactless communication system according to the embodiment of the present invention includes the reader / writer 100 and the information processing apparatus 150. Whereas the conventional information processing apparatus 50 constituting the conventional non-contact communication system replies to the conventional reader / writer 10 by load modulation, the non-contact communication system according to the embodiment of the present invention includes the information processing apparatus. 150 replies to the reader / writer 100 by transmitting a synchronized carrier wave by itself.

  An information processing apparatus 150 according to an embodiment of the present invention includes a PLL circuit 160 as a component of a transmission / reception circuit, and selectively transmits a synchronized carrier wave based on an output signal output from the PLL circuit 160. Here, the PLL circuit 160 includes a level holding circuit 188, and holds and outputs an output signal based on a control signal output from the data processing circuit 162. The control signal is output from a data processing circuit 162 that processes the carrier signal obtained by demodulating the carrier wave. The data processing circuit 162 performs data processing based on the PLL lock detection signal output from the PLL circuit 160. A control signal corresponding to the result is output. Therefore, the information processing apparatus 150 can transmit a synchronized carrier wave based on an output signal (held output signal) that is output from the PLL circuit 160 and is synchronized in frequency and phase with the carrier wave.

  Here, the change in the amplitude of the voltage at the antenna end of the reader / writer 100 that has received the synchronized carrier wave corresponds to the waveform in which the waveform in the case of modulation OFF shown in FIG. The direction depends on the phase of the sync carrier.) That is, the reader / writer 100 does not generate a non-communication area as indicated by point A in FIG. Therefore, the reader / writer 100 can demodulate the response signal transmitted from the information processing apparatus 150 using the amplitude change.

  Therefore, in the non-contact communication system according to the embodiment of the present invention, the information processing apparatus 150 receives a carrier wave (receives a carrier wave signal) transmitted from the reader / writer 100 as described above and transmits a synchronized carrier wave by itself (response). By transmitting a signal, it is possible to prevent the occurrence of a communication disabled area. Therefore, the contactless communication system according to the embodiment of the present invention can stabilize communication between the reader / writer 100 and the information processing apparatus 150.

  Further, the information processing apparatus 150 includes a phase correction circuit 166 that delays the phase of the output signal output from the PLL circuit 160 by a predetermined delay amount as a transmission / reception circuit. Therefore, for example, even when there is an unintended shift between the phase of the signal for transmitting the synchronized carrier wave transmitted to the communication antenna 152 by wiring and the phase of the output signal output from the PLL circuit 160, The phase can be corrected to the intended phase by the phase correction circuit 166. Therefore, since the information processing apparatus 150 includes the phase correction circuit 166, the reader / writer 100 can transmit a synchronized carrier wave having a phase that can be demodulated more reliably. can do.

  In the above description, the reader / writer 100 has been described as a constituent element of the contactless communication system according to the embodiment of the present invention. However, the embodiment of the present invention is not limited to such a configuration, for example, a reader / writer function. The present invention can be applied to a portable communication device such as a mobile phone having a PC and a computer such as a UMPC (Ultra Mobile Personal Computer) having a reader / writer function.

  Further, although the information processing apparatus 150 has been described as a constituent element of the contactless communication system according to the embodiment of the present invention, the embodiment of the present invention is not limited to such a configuration, for example, an RFID tag, a contactless communication Applied to various devices that perform non-contact communication using a carrier wave, such as IC cards, portable communication devices such as mobile phones equipped with non-contact IC chips, and computers such as PCs (Personal Computers) equipped with non-contact IC chips can do.

(Program according to an embodiment of the present invention)
With the program for causing the information processing apparatus according to the embodiment of the present invention to function as a computer, it is possible to prevent the occurrence of a non-communication area within a communicable range in non-contact communication using a carrier wave.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the information processing apparatus 150 according to the embodiment of the present invention illustrated in FIG. 5, the detection circuit 154 and the demodulation circuit 158 that configure the transmission / reception circuit are illustrated as separate circuits. However, in the embodiment of the present invention, The configuration is not limited to this. For example, the information processing apparatus according to the embodiment of the present invention can be configured as an integrated circuit by sharing the parts related to detection of the detection circuit and the demodulation circuit. Even with the above-described configuration, it is possible to transmit a synchronized carrier wave similarly to the information processing apparatus 150 according to the embodiment of the present invention described above, and therefore, the same effects as the information processing apparatus 150 can be obtained. .

  Further, in the information processing apparatus 150 according to the embodiment of the present invention illustrated in FIG. 5, the configuration including the phase correction circuit 166 and the amplification circuit 168 as the transmission / reception circuit is illustrated, but the embodiment of the present invention is not limited to this configuration. . For example, the information processing apparatus according to the embodiment of the present invention may be configured not to include a phase correction circuit and / or an amplifier circuit. Even with the above configuration, it is possible to transmit a synchronized carrier wave in accordance with the output signal output from the PLL circuit, so that it is possible to prevent the occurrence of a communication disabled area.

  The configuration described above shows an example of the embodiment of the present invention, and naturally belongs to the technical scope of the present invention.

It is explanatory drawing which shows the conventional non-contact communication system which consists of the conventional reader / writer and the conventional information processing apparatus. It is the 1st explanatory view for explaining the problem in the conventional non-contact communication system. It is the 2nd explanatory view for explaining the problem in the conventional non-contact communication system. It is explanatory drawing for demonstrating the effect of the problem-solving approach which concerns on embodiment of this invention. It is explanatory drawing which shows the non-contact communication system which concerns on embodiment of this invention. It is explanatory drawing for demonstrating the problem in case the shift | offset | difference arises in the phase of the signal for the synchronized carrier wave transmission concerning embodiment of this invention, and the phase of an output signal. It is explanatory drawing which shows the relationship between the carrier wave which can produce a communication impossible area | region, and a synchronous carrier wave. It is a flowchart which shows an example of the communication method which concerns on embodiment of this invention. It is explanatory drawing for demonstrating the outline of communication in the non-contact communication system which concerns on embodiment of this invention.

Explanation of symbols

10, 100 Reader / Writer 12, 102 Carrier signal generator 14, 104 Carrier transmitter 16, 106 Demodulator 18, 108 Controller 50, 150 Information processing device 54, 152 Communication antenna 154 Detection circuit 156 Carrier detection circuit 158 Demodulation circuit 160 PLL circuit 162 Data processing circuit 164 Modulation circuit 166 Phase correction circuit 168 Amplification circuit 170 Battery 180 Voltage control oscillation circuit 182 Frequency division circuit 184 Phase comparison circuit 186 Loop filter 188 Level holding circuit 190 Level holding switch

Claims (13)

A communication antenna that receives a carrier wave of a predetermined frequency transmitted from the reader / writer and generates an induced voltage corresponding to the carrier wave;
A carrier wave detector for detecting the induced voltage and outputting a detection signal;
A voltage-controlled oscillator that receives the detection signal and the input voltage and outputs an output signal having a frequency corresponding to the input voltage based on the detection signal;
A phase comparator that compares the phase difference between the phase of the reference signal from which the induced voltage is detected and the phase of the output signal, and outputs a phase difference signal corresponding to the phase difference;
A data processing unit that processes a carrier wave signal demodulated based on the induced voltage and outputs a control signal corresponding to the processing based on the phase difference signal;
A loop filter that removes an AC component of the phase difference signal and outputs a phase compensation voltage;
The phase compensation voltage is selectively input according to the control signal to hold the phase compensation voltage, and the phase compensation voltage input according to the control signal or the held holding voltage is used as the input voltage. A level holding unit that selectively outputs to the voltage controlled oscillation unit;
A modulation unit that selectively outputs the output signal to the communication antenna based on the control signal and transmits a synchronized carrier wave from the communication antenna;
A transmission / reception circuit comprising: The modulation unit includes a first switch that performs an on / off operation according to the control signal,
The level holding unit is
A second switch that turns off when the first switch is on and turns on when the first switch is off and selectively outputs the phase compensation voltage as the input voltage in response to the control signal;
A capacitor that holds the phase compensation voltage output from the second switch and outputs the held voltage held when the second switch is off as the input voltage;
The transmission / reception circuit according to claim 1, comprising:   The transmission / reception circuit according to claim 1, wherein the data processing unit outputs a control signal corresponding to the processing when a phase difference indicated by the phase difference signal is zero.   The transmission / reception according to claim 1, further comprising: a phase correction unit that corrects a phase of the output signal selectively output from the modulation unit according to the control signal and transmits the corrected signal to the communication antenna. circuit.   The transmission / reception circuit according to claim 4, wherein the phase correction unit delays the phase of the output signal by a predetermined amount.   The transmission / reception circuit according to claim 1, further comprising an amplifying unit that amplifies a gain of an output signal selectively output from the modulation unit in accordance with the control signal.   The transmission / reception circuit according to claim 1, further comprising a frequency divider that divides the output signal output from the voltage controlled oscillator.   The transmission / reception circuit according to claim 1, further comprising a detection unit that detects an envelope of the induced voltage and outputs the reference signal.   The transmission / reception circuit according to claim 1, further comprising: a demodulator that detects an envelope of the induced voltage, binarizes the envelope detected signal, and outputs the signal as the carrier signal. A communication antenna that receives a carrier wave of a predetermined frequency transmitted from the reader / writer and generates an induced voltage corresponding to the carrier wave;
A carrier wave detector for detecting the induced voltage and outputting a detection signal;
A voltage controlled oscillator that is activated by the detection signal and generates an output signal;
A phase comparison unit that compares the phase difference between the reference signal detected by the induced voltage and the output signal and outputs a phase difference signal corresponding to the phase difference;
A loop filter for smoothing the phase difference signal and outputting a phase compensation voltage;
A data processing unit that processes a carrier wave signal demodulated based on the induced voltage and outputs a control signal corresponding to the processing based on the phase difference signal;
The phase compensation voltage is selectively input according to the control signal to hold the phase compensation voltage, and the phase compensation voltage held according to the control signal is output as an input voltage to the voltage controlled oscillator. A level holding part;
A modulator that selectively outputs the output signal to the communication antenna based on the control signal and transmits a synchronized carrier wave from the communication antenna;
An information processing apparatus comprising:   The communication apparatus according to claim 10, wherein the information processing apparatus is a portable communication apparatus. A communication antenna for performing contactless communication using a reader / writer and a carrier wave;
A phase synchronization unit that receives a reference signal in which an induced voltage generated in response to reception of the carrier wave in the communication antenna is detected, and outputs an output signal that is synchronized in frequency and phase with the reference signal;
A data processing unit that processes the carrier wave signal from which the induced voltage is demodulated and outputs a control signal corresponding to the processing based on the synchronization in the phase synchronization unit;
A modulator that selectively outputs the output signal to the communication antenna based on the control signal and transmits a synchronized carrier wave from the communication antenna;
A communication method used in an information processing apparatus comprising:
Detecting reception of the carrier;
Synchronizing the reference signal and the output signal in the phase synchronization unit according to the detection result of the detecting step;
Processing the carrier signal in response to the carrier detected in the detecting step;
Determining phase synchronization between the reference signal and the output signal in the phase synchronization unit;
Outputting the control signal according to the processing result of the processing step based on the determination result of the determining step;
Maintaining a constant frequency and phase of an output signal output from the phase synchronization unit in response to the control signal;
Transmitting an output signal whose frequency and phase are kept constant in the step of keeping constant, transmitting the output signal to the communication antenna according to the control signal, and transmitting a synchronized carrier wave;
A communication method characterized by comprising: A communication antenna for performing contactless communication using a reader / writer and a carrier wave;
A phase synchronization unit that receives a reference signal in which an induced voltage generated in response to reception of the carrier wave in the communication antenna is detected, and outputs an output signal that is synchronized in frequency and phase with the reference signal;
A data processing unit that processes the carrier wave signal from which the induced voltage is demodulated and outputs a control signal corresponding to the processing based on the synchronization in the phase synchronization unit;
A modulation unit that selectively outputs the output signal to the communication antenna based on the control signal and transmits a synchronized carrier wave from the communication antenna;
A program that can be used in an information processing device comprising:
Detecting reception of the carrier;
Synchronizing the reference signal and the output signal in the phase synchronization unit according to the detection result of the detecting step;
Processing the carrier signal in response to the carrier detected in the detecting step;
Determining phase synchronization between the reference signal and the output signal in the phase synchronization unit;
Outputting the control signal according to the processing result of the processing step based on the determination result of the determining step;
Maintaining a constant frequency and phase of an output signal output from the phase synchronization unit in response to the control signal;
Transmitting an output signal, the frequency and phase of which are kept constant in the step of keeping constant, to the communication antenna according to the control signal, and transmitting a synchronized carrier wave;
A program that causes a computer to execute.

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