JP2009271861A - Noncontact type communication device, and decoding part thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow communication by a plurality of kinds of communication systems, even as to interactive communication in NFC. <P>SOLUTION: A data change point detecting part 21 detects a level change point of a demodulated data, and outputs a detection signal to a reference time generation timer part 22 and a change point detection counter part 23. The change point detection counter part 23 counts a detection frequency of the level change point. The reference time generation timer part 22 conducts prescribed time measurement. A communication system-transfer rate determining part determines the communication system, in response to the detection frequency within a prescribed time, and decodes the demodulated data by a decoding part 26 in response to the determined communication system. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a non-contact type communication device and a data decoding method, and more particularly to a non-contact type communication device including a non-contact IC card reader / writer capable of performing communication using a plurality of different communication methods, and a data decoding method.

  In recent years, contactless IC cards have been widely used in fields such as electronic money and electronic tickets. The non-contact IC card system is composed of a reader / writer and a non-contact IC card, and the non-contact IC card activates an internal IC by a magnetic field radiated from the reader / writer. Communication from the reader / writer to the non-contact IC card is realized by modulating the amplitude of the radiated magnetic field, and communication from the non-contact IC card to the reader / writer is performed with respect to the magnetic field radiated by the reader / writer. This is done by switching the load (load modulation) and detecting this by the reader / writer.

  There are several types of communication methods between IC cards and reader / writers, such as types A, B, and C shown in FIG. 7 as proximity types. Encoding and modulation methods are performed using “reader / writer → IC card” and “IC card → reader / writer”. The specifications such as transfer rate are different.

FIG. 9A shows a waveform at the time of “reader / writer → IC card” communication of the type A communication method.
In the communication system of type A, at the time of “reader / writer → IC card” communication, the transfer rate is 106 kbps, ASK (Amplitude Shift Keying) modulation is performed with a modified mirror code, and magnetic field output in the bit data section is stopped (referred to as a pause pulse). ) Represents 1 and 0 data. A logic “1” is set when there is a pause pulse in the center of bit data, and a logic “0” is set when there is a pause pulse at the beginning of bit data and when there is no pause pulse. The start of the communication frame has a start bit of 1 bit (data value 0).

FIG. 9B shows a waveform at the time of “IC card → reader / writer” communication of the type A communication method.
In the type A communication system, during “IC card → reader / writer” communication, the transfer rate is 106 kbps, and the Manchester code is OOK (ON OFF Keying) modulated with a subcarrier 847 kHz, thereby expressing 1,0 data. The case where there is a subcarrier in the first half of bit data is logic “1”, and the case where there is a subcarrier in the second half of bit data is logic “0”. The start of the communication frame has a 1-bit start bit (data value 1).

FIG. 9C shows a waveform at the time of “reader / writer → IC card” communication of the type B communication method.
In the communication method of type B, during “reader / writer → IC card” communication, the transfer rate is 106 kbps, and ASK modulation is performed with an NRZ code to express 1,0 data. A state where the amplitude of the carrier wave is large (unmodulated state) is a logic “1”, and a state where the amplitude of the carrier wave is small is a logic “0”. The start bit of the data portion of the communication frame has 1 bit (data value 0).

FIG. 9D shows a waveform at the time of “IC card → reader / writer” communication of the type B communication method.
In the type B communication method, during “IC card → reader / writer” communication, the transfer rate is 106 kbps, and BPSK (Binary Phase Shift Keying) modulation of the subcarrier 847 kHz with the NRZ code is used to represent 1 and 0 data. The initial output phase state of the subcarrier is set to logic “1”, and the subsequent phase shift is set to “0 → 1 → 0 →. The start bit of the data portion of the communication frame has 1 bit (data value 0).

FIG. 9E shows waveforms at the time of “IC card → reader / writer” and “IC card → reader / writer” communication of the type C communication method.
In the type C communication system, the transfer rate is 212 kbps, and ASK modulation is performed with Manchester code to express 1,0 data. The first half of the bit is a state where the amplitude of the carrier wave is small, the second half of the bit is a logic “0” when the amplitude of the carrier wave is large (unmodulated state), and the first half of the bit is the state where the amplitude of the carrier wave is large. Is a logic “1” when the amplitude of the carrier wave is small (even if the polarity is inverted, the polarity can be identified when receiving the unique code in the frame). At the beginning of the communication frame, the preamble is 48 bits (data value 0).

In order to communicate with a plurality of IC cards of different communication methods, a conventional reader / writer device performs a demodulation process when receiving a response signal from the IC card with an antenna, and measures the time of the pulse width of the obtained demodulated signal. Based on the measurement result, the communication method of the IC card is determined. As a result, the reader / writer can communicate with a plurality of IC cards of different communication methods (see Patent Document 1).
JP 2002-342725 A

  By the way, the communication technology of the conventional non-contact IC card system has been expanded to standardize near field communication (hereinafter referred to as NFC) featuring two-way communication (IEC / ISO18092, etc.). In the conventional IC card system, the reader / writer modulates a carrier wave of a predetermined frequency and transmits command data, and the IC card transmits response data by load-modulating the carrier wave output from the reader / writer. NFC bidirectional communication is a communication method in which a carrier wave is modulated and transmitted and transmitted, and communication is possible between non-contact communication devices such as reader / writer devices.

  The relationship between the conventional “reader / writer” and “IC card” is called “initiator” and “target” in NFC bidirectional communication. The initiator sends a polling command according to a predetermined initialization / communication procedure, By receiving the response from, the target in the communicable RF magnetic field is detected and communication is performed.

  The conventional mode for performing communication between “reader / writer” and “IC card” is called a passive mode, and the mode for performing NFC bidirectional communication is called an active mode. In the case of a device that can handle these two types of communication modes, communication is performed by selecting one of the modes.

  The passive mode is a communication mode for ensuring backward compatibility with an existing non-contact IC card, and a communication start side (reader / writer) generates a magnetic field modulated with information to be transmitted, The side (IC card) is a mode that returns a response by performing load modulation on an unmodulated magnetic field generated by the reader / writer.

  On the other hand, the active mode is a mode in which communication is performed by generating a magnetic field modulated by information transmitted between the initiator and the target (stopping the generation of the magnetic field after information transmission).

As shown in FIG. 8, in NFC bidirectional communication, the communication method such as the encoding method and the modulation degree differs depending on the transfer rate.
FIG. 10A shows a waveform example of a communication method of bidirectional communication 106 kbps.

The communication system of bidirectional communication 106 kbps is ASK-modulated with a modified mirror code, and is equivalent to the above-described system at the time of type A reader / writer transmission.
FIG. 10B shows a waveform example of a communication method of bidirectional communication 212 kbps.

The two-way communication 212 kbps communication method is equivalent to the method used when transmitting type C reader / writer by performing ASK modulation with Manchester code.
FIG. 10 (c) shows a waveform example of a communication method of bidirectional communication 424kbps.

In the communication system of bidirectional communication 424 kbps, ASK modulation is performed with a Manchester code, and the above-described system at the time of type C reader / writer transmission is speeded up.
In the reader / writer device, when a bidirectional communication function is added in addition to the communication with the conventional IC card, especially in the case of a device that can handle each of a plurality of types of communication methods, the reception control unit is shown in FIG. In addition to the reception function of various communication methods of “card → reader / writer” shown in FIG. 8, it is necessary to have the reception function of various bidirectional communication of NFC shown in FIG. Each specification is different.

  Further, the conventional reader / writer device can wait for a response from the IC card to a command request transmitted by itself by specifying a communication method. Even in NFC bi-directional communication, when operating as an initiator, it is possible to determine the communication method by itself and perform communication.

  However, when it becomes a “target” for bidirectional communication, it is impossible to specify and wait for the communication method because the communication method and transfer rate are unknown when receiving the polling command transmitted by the initiator. For this reason, it has been difficult to perform communication using a plurality of types of communication methods for NFC bidirectional communication.

  An object of the present invention relates to a non-contact type communication device such as a reader / writer device, and in particular, it is possible to perform communication by a plurality of types of communication methods not only for existing communication with an IC card but also for NFC bidirectional communication, The object is to provide a non-contact type communication device capable of performing communication by various communication methods, a decoding unit thereof, and the like.

  The non-contact communication device of the present invention performs non-contact data transmission / reception with a non-contact information medium or other non-contact communication device, and supports at least a plurality of types of communication methods using bidirectional communication. A demodulating unit that demodulates a received signal from an antenna unit and outputs demodulated data; and a decoding unit that inputs the demodulated data and decodes the demodulated data. A data change point detection means for detecting each change point of the demodulated data, and a timer control means for determining a reception start timing from a detection result by the data change point detection means and measuring a predetermined period from the reception start timing A data change point counter control means for counting the number of times the data change point is detected by the data change point detection means, and a plurality of decoding units corresponding to each of a plurality of types of communication methods. Determining a communication method based on the number of detections of the data change point within the predetermined period, and a selection unit that selects a decoding unit that decodes the input demodulated data from the plurality of decoding units, A communication method determining unit that causes the selecting unit to select a decoding unit corresponding to the determined communication method.

  The plurality of types of communication methods are at least “424 kbps bidirectional communication”, “212 kbps bidirectional communication”, and “106 kbps bidirectional communication”. That is, it is a communication method used for communication with other non-contact type communication devices. In the case of such NFC bidirectional communication, when the self receives a transmission signal from the initiator as a target, the conventional communication method could not be specified as described above. However, in the non-contact communication apparatus of the present invention, the communication system can be discriminated by the above configuration, so that it is possible to support a plurality of types of communication systems for NFC bidirectional communication. In addition, since the communication method is determined based on the number of detections of the data change point, it is possible to reduce erroneous reception / detection by adding a certain margin to the determination condition.

  According to the non-contact type communication device of the present invention, its decoding unit, etc., it relates to a non-contact type communication device such as a reader / writer device, and in particular, a plurality of types of NFC bidirectional communication as well as existing communication with IC cards. It is possible to perform communication using various communication methods, and it is possible to perform communication using various communication methods. Furthermore, it is possible to reduce erroneous reception / detection.

Embodiments of the present invention will be described below with reference to the drawings.
Hereinafter, Example 1 will be described first.
FIG. 1 is a diagram illustrating an example of the overall configuration of the contactless communication apparatus of this example.

  The illustrated non-contact communication apparatus 10 includes a control unit 11, an RF transmission control unit 12, an RF reception control unit 13, and an antenna unit 19. The control unit 11 includes a decoding unit 11a. The RF transmission control unit 12 includes a modulation unit 14, an amplification unit 15, and a carrier oscillator 16. The RF reception control unit 13 includes a demodulation unit 18 and an A / D conversion unit 17.

  The non-contact type communication device 10 of this example performs non-contact type communication with a non-contact type information medium (non-contact type IC card or the like) or another non-contact type communication device 10. That is, data transmission / reception by the magnetic field described above is performed. The non-contact type communication device 10 is, for example, an IC card reader / writer device or the like, but is not limited to this example. For example, it may be a portable terminal with a non-contact type IC card.

  The control unit 11 controls RF transmission / RF reception in accordance with an instruction from a host device (not shown). At the time of RF transmission, parameter information such as a transmission mode and a transfer rate and transmission data are received from the host device, general encoding processing is performed, and data is output to the RF transmission controller 12. At the time of reception, the reception signal from the antenna unit 19 is filtered by the RF reception control unit 13, receives the demodulated signal that has been binarized, and is decoded into an NRZ code by the decoding unit 11 a to perform frame generation / reception error check, etc. And reception notification to the host device.

In the RF transmission control unit 12, the carrier oscillator 16 generates a predetermined carrier wave (13.56 MHz) and outputs it to the modulation unit 14.
The RF transmission control unit 12 generates the RF magnetic field by the modulation unit 14 modulating the carrier wave with the transmission data from the control unit 11, amplifying it by the amplification unit 15, and sending it to the antenna unit 19. , And send data.

  The RF reception control unit 13 detects and filters the received signal from the antenna unit 19 and demodulates the demodulated signal, and the A / D conversion unit 17 that binarizes the demodulated signal. Demodulated data (received data) is sent to the decoding unit 11a.

FIG. 2 is a diagram illustrating a configuration example of the decoding unit 11 a in the control unit 11.
The decoding unit 11a in the illustrated example receives the demodulated data from the RF reception control unit 13 and the reference clock used by the control unit 11 of the reader / writer device, and generates and outputs data decoded into the NRZ code. .

  The decoding unit 11a corresponds to the data change point detection unit 21, the reference time generation timer unit 22, the change point detection counter unit 23, the communication method / transfer rate determination unit 24, the data selection units 25 and 27, and a plurality of communication methods. The decoding unit 26 is configured. As the decoding unit 26 corresponding to a plurality of communication methods, in the illustrated example, decoding units 26a, 26b, and 26c corresponding to communication methods A, B, and C, respectively, are shown. The methods A, B, and C are, for example, “424 kbps bidirectional communication”, “212 kbps bidirectional communication”, “106 kbps bidirectional communication”, and the like.

  The demodulated data (binarized data) output from the A / D converter 17 is input to the data change point detector 21 and the data selector 25. The data change point detection unit 21 detects the level change point of the demodulated data and outputs this detection signal to the reference time generation timer unit 22 and the change point detection counter unit 23. The change point detection counter unit 23 counts the number of times the level change point is detected. The reference time generation timer unit 22 measures a predetermined time from the time when the first level change point is detected. The communication method / transfer rate determination unit 24 determines the communication method according to the number of level change point detections within the predetermined time, and controls the data selection unit 25 based on the determination result. Thus, the demodulated data is decoded by the decoding unit 26 according to the determined communication method.

  Note that the communication method / transfer rate determination unit 24 also controls the data selection unit 27 based on the determination result, and the data selection unit 27 outputs the output of the decoding unit 26 that has been decoded, for example, not shown in the control unit 11. Output to CPU.

  3A to 3C show operation timing charts of the decoding unit 11a according to the first embodiment. In this example, operation timing charts when receiving the above-described bidirectional communication 106 kbps, 212 kbps, and 424 kbps are shown in FIGS. 3 (a), 3 (b), and 3 (c), respectively.

  The data change point detector 21 samples the input demodulated data with a reference clock (for example, 1.695 MHz), detects a level change point (rising or falling of demodulated data), and this detection signal as described above. Is output to the reference time generation timer unit 22 and the change point detection counter unit 23. The “data change point” shown in FIGS. 3A to 3C is an example of this detection signal. As shown in the figure, every time there is a rise or fall of demodulated data, one pulse “1” is output.

  The reference time generation timer unit 22 determines the reception start timing based on the detection signal from the data change point detection unit 21, starts a timer that operates with the reference clock from there, and measures a predetermined time. In the example of FIGS. 3A to 3C, as shown in the figure, the start of the data change point (when the first detection signal is received) is set as the reception start timing, and the predetermined time = 9.43 μs (16 counts with the 1.695 MHz reference clock) , Equivalent to 1 bit time of 106 kbps). The “reception start timing” signals shown in FIGS. 3A to 3C are output to the change point detection counter unit 23 by the reference time generation timer unit 22 at the reception start timing.

  The change point detection counter unit 23 starts counting the number of level changes from the time when the “reception start timing” signal is turned on (“1”). That is, every time there is one pulse of the detection signal from the data change point detector 21 from this starting time, the count is incremented by one. The initial value of the counter is “0”, for example. This counter value is output to the communication method / transfer rate determination unit 24 in the next stage. The numerical value of the “data change point counter” shown in FIGS. 3A to 3C is an example of the counter value.

  The communication method / transfer rate determination unit 24 determines the communication method and transfer rate of the received signal from the result of the number of times the demodulated data level changes within a predetermined period. For example, when the reference time generation timer unit 22 expires after the predetermined time elapses, when the timer up signal is output to the communication method / transfer rate determination unit 24, the communication method / transfer rate determination unit 24 The counter value at the time of receiving the timer up signal is referred to as “level change count” as “the result of the level change count of the demodulated data within a predetermined period” (hereinafter simply referred to as the level change count). Based on a communication system etc. determination table (an example is shown in FIG. 6), the communication system and transfer rate of the received signal are determined.

  Here, in FIGS. 3A to 3C, the timer-up time is indicated by a black inverted triangle (▼) mark. As shown in the figure, in the case of bidirectional communication with a transfer rate of 424 (kbps) shown in FIG. 3A, the counter value when the timer is up is “8”, so the number of level changes is “8”. Become. Similarly, in the case of bidirectional communication with a transfer rate of 212 (kbps) shown in FIG. 3B, the number of level changes is “4”, and the transfer rate shown in FIG. 3C is 106 (kbps). In the case of bidirectional communication, the number of level changes is “2”.

  In this way, the number of demodulated data level changes within a predetermined period differs depending on each communication method and transfer rate. Therefore, if determination conditions and determination results are registered in advance in a communication method determination table, which will be described later, accordingly. By referring to this table using the number of level changes, the communication method and transfer rate of the received signal can be determined.

  In the above description, the communication method / transfer rate determination unit 24 determines the communication method and transfer rate of the received signal. This determines the “communication method” as “bidirectional communication”, for example. It corresponds to an example. However, it can be considered as one communication method including the transfer rate. In this case, in the example shown in FIG. 4, there are three types of communication methods of “424 kbps bidirectional communication”, “212 kbps bidirectional communication”, and “106 kbps bidirectional communication”. In this case, the communication method / transfer rate determining unit 24 can be regarded as a communication method determining unit for determining “communication method”, and the data selecting unit 25 is a decoding unit corresponding to the determined “communication method”. This will cause decoding to occur.

FIG. 4 is a diagram illustrating determination conditions in the communication method / transfer rate determination unit 24 according to the first embodiment. That is, it is a diagram illustrating an example of the communication method etc. determination table 30.
In the illustrated communication method etc. determination table 30, a determination result 32 is registered in association with each data change point counter value 31 which is a determination condition. In the example shown in the figure, there are two determination conditions, determination condition 1 and determination condition 2. However, both of these are used instead of using both.

  Determination condition 1 is a case where the condition of the number of level change points is set as a fixed value. In the example shown in FIGS. 3A to 3C, the number of level changes is “8”, “4”, and “2”, respectively, as described above. Accordingly, the determination condition 1 is “8”, “ 4 'and' 2 '. Naturally, for example, when the determination condition 1 is “8”, the determination result 32 is “424 (kbps) bidirectional communication”. Therefore, when the number of level changes is “8”, referring to this table 30, the determination result is “424 (kbps) bidirectional communication”, and the communication method and transfer rate of the received signal are correctly determined. can do.

  However, it is not always as shown in the examples shown in FIGS. 3A to 3C, and there is a possibility that some fluctuations may occur or there is an influence of noise or the like. For example, in the case of “424 (kbps) bidirectional communication”, the number of level changes may be “7” or the like. The determination condition 2 shown in FIG. 4 is a determination condition that takes this into consideration.

  That is, the determination condition 2 is a setting example in the case where the upper limit value and the lower limit value can be arbitrarily set by the determination condition of the number of level change points. In other words, the determination condition is given a certain width (margin) in consideration of the possibility of some fluctuations and the influence of noise and the like.

As shown in the figure, for example, for “212 (kbps) bidirectional communication”, the determination condition 2 is “3 to 5”.
The communication method / transfer rate determination unit 24 outputs the determination result to the data selection unit 25 at the next stage. Alternatively, the data selection unit 25 is controlled according to the determination result. The data selection unit 25 outputs the demodulated data to a predetermined decoding unit 26 (here, any one of 26a, 26b, and 26c) according to the determination result. Naturally, the predetermined decoding unit 26 is a decoding unit corresponding to the communication method of the received signal, and can perform the decoding process without any problem. Accordingly, the predetermined decoding unit 26 can normally perform processing such as decoding the demodulated data into an NRZ code (further, frame generation, reception error check processing, etc., not shown).

  For example, the data selection unit 25 is a switch unit that inputs demodulated data and outputs the demodulated data to any one of the plurality of decoding units 26. The communication method / transfer rate determination unit 24 determines this based on the determination result. You may make it control switching of a switch part. As a result, the switch unit is switched according to the determination result, and the demodulated data is output to the predetermined decoding unit 26. The data selection unit 25 may include a memory for temporarily storing demodulated data.

  As described above, according to the contactless communication apparatus 10, the decoding unit 11a, and the communication method / transfer rate determination method of the first embodiment, the received signal is based on the number of level changes of the demodulated data within a predetermined period. The communication method and the transfer rate can be determined, and the corresponding decoding unit can perform decoding. Even when the device itself is a “target” for bidirectional communication, the communication method and transfer rate can be determined when receiving a polling command transmitted by the initiator. Communication can be performed using various types of communication methods.

  In the above description, the measurement time from the reception start timing is 9.43 μs, but the measurement time can be arbitrarily set. For example, by setting the measurement time to 18.86 μs (corresponding to 2-bit time of 106 kbps) and changing the above-described determination conditions, it becomes possible to identify the communication method and transfer rate.

  In addition, the determination operation by the communication method / transfer rate determining unit 24 is performed by, for example, a microprocessor or the like executing a predetermined application program stored in advance in a memory or the like (in this case, determining the communication method or the like). It may be realized by referring to the table 30) or may be realized by configuring a dedicated hardware circuit. The same applies to Example 2 described later.

Example 2 will be described below.
Also in the second embodiment, the configuration itself of the non-contact communication device 10 and the decoding unit 11a is the same as that of the first embodiment, and may be the configuration illustrated in FIGS. Therefore, the second embodiment will be described below with reference to FIGS.

  The second embodiment is different from the first embodiment in the operation of the reference time generation timer unit 22 and the determination processing content of the communication method / transfer rate determination unit 24. Hereinafter, the points different from the first embodiment will be mainly described, and the description of the same points as the first embodiment will be omitted.

5A and 5B show operation timing charts of the decoding unit 11a according to the second embodiment.
In this example, a timing chart at the time of transmitting a type A and type B IC card, which is the above-described communication method of “card → reader / writer”, is shown. FIG. 5A shows type A, and FIG.

  The second embodiment is different from the first embodiment in that one measurement time in the reference time generation timer unit 22 is 4.72 μs and the timer operation is looped twice (measurement time 4.72 μs is measured twice in succession). The communication method / transfer rate determination unit determines the communication method and transfer rate of the received signal from the number of times of demodulated data level change at two points at different timings.

  In other words, the measurement time for one time in the reference time generation timer unit 22 is half the 1-bit time of the transfer rate of 106 kbps, and the measurement is performed twice continuously, so that 1-bit time from the reception start timing. The communication method and transfer rate of the received signal are determined based on the number of data change point detections at two timings, the timing when half the time has elapsed and the timing when 1 bit time has elapsed from the reception start timing.

  In this determination, not only two types of type A and type B but also five types of communication methods and transfer rates including the three types of bidirectional communication of the first embodiment can be determined. Further, as will be described later, six types of discrimination including type C can be performed.

Details will be described below.
First, as described above, one measurement time in the second embodiment is approximately half of one measurement time (9.43 μs) in the first embodiment. That is, one measurement time of 4.72 μs in this example corresponds to half time of 1 count of 106 counts and 8 counts with a 1.695 MHz reference clock. That is, in this example, the first half of 106 kbps 1 bit is the first measurement period, and the second half is the second measurement period.

  Note that the counter is not reset at the start of the second measurement period, and is continued as it is. Since the timer up signal is input to the communication method / transfer rate determination unit 24 at the end of the first and second measurement periods, the counter value at this time is acquired.

  As shown in FIGS. 9B and 9D, the type A and type B IC card transmission waves have a subcarrier in the first half or the second half of bit data in the case of type A, and bit data in the case of type B. There are subcarriers in almost the whole. In the case of type A, with respect to the start bit, there is a subcarrier in the first half of the bit data.

  As shown in FIGS. 5A and 5B, the data change point detector 21 detects the level change point (the rise or fall of the demodulated data) of the demodulated data by the subcarrier. In the illustrated example, in the case of Type A shown in FIG. 5A, there are seven level changes within the first measurement period, so the number of level changes at the end of the first measurement period is “7”. It becomes. On the other hand, since there is no level change within the second measurement period, the number of level changes (count value) at the end of the second measurement period remains ‘7’.

  On the other hand, in the case of Type B shown in FIG. 5B, since there are eight level changes within the first measurement period, the number of level changes at the end of the first measurement period is ‘8’. Further, since there are seven level changes within the second measurement period, the number of level changes (count value) at the end of the second measurement period is ‘15’.

  Hereinafter, the number of level changes at the end of the first measurement period is referred to as “first level change number (or count value)”, and the number of level changes at the end of the second measurement period is referred to as “second level change number ( Or a count value).

  If only two types of type A and type B are to be distinguished, the measurement period may not be provided (even if the predetermined period of the first embodiment is not divided into the first half and the second half). It is only necessary to perform measurement within a predetermined period of one. However, when the above five types of discrimination are performed, considering that there is a slight variation, both Type A and 424 kbps bidirectional communication both have a level change count of about 7 to 8 in the predetermined period of the first embodiment. And may become indistinguishable. However, for example, in the first measurement period, the number of level changes is about 7 in Type A, whereas the number of level changes is about 3 to 4 in 424 kbps bidirectional communication, so that both can be distinguished. .

Thus, in the second embodiment, the communication method / transfer rate determination unit 24 determines the communication method / transfer rate using, for example, the communication method / etc. Determination table 40 shown in FIG.
FIG. 6 is a diagram illustrating determination conditions in the communication method / transfer rate determination unit 24 according to the second embodiment. That is, it is a diagram illustrating an example of the communication method etc. determination table 40.

  In the illustrated communication method determination table 40, a determination result 42 is registered in association with each data change point counter value 41, which is a determination condition. The determination result 42 is a communication method / transfer rate in the figure, but may be switch switching information of a switch unit in the data selection unit 25 or the like. The same applies to the first embodiment.

  In the illustrated example, there are two determination conditions 41, measurement period 1 (41a) and measurement period 2 (41b). In this example, both of these are basically used. The measurement period 1 (41a) is a determination condition corresponding to the first count value, and the measurement period 2 (41b) is a determination condition corresponding to the second count value.

  When the communication method / transfer rate determination unit 24 acquires the first and second two level change times (count values), the communication method / transfer rate determination unit 24 refers to the communication method / etc. Determine the transfer rate. This determination algorithm may be various, but for example, it may be a condition that both of the two determination conditions of the measurement period 1 (41a) and the measurement period 2 (41b) are satisfied.

  In this case, for example, when the received signal is 424 kbps bidirectional communication, the count value at the end of the first measurement period is about four times, and the count value at the end of the second measurement period (the count of all the above measurement periods). Value) is about 8 times. Therefore, when the determination is made based on the determination condition of the measurement period 2 (41b), the condition of the measurement period 2 (41b) of type A is also met. Therefore, only the 424 kbps bi-directional communication is met, so the determination result is “424 kbps bi-directional communication”, and the communication method / transfer rate can be correctly determined.

  Alternatively, if it is considered that only “424 kbps two-way communication” and “type A card reception” may be indistinguishable in the determination condition of measurement period 2 (41b), basically measurement period 2 (41b) ) Only in the determination condition, and as an exception, the determination by the measurement period 1 (41a) is also performed only when the count value (number of level changes) is a value within the range of 6 to 9, for example. Also good.

  Although there is no determination regarding “type C card reception” in FIG. 6, in the case of “type C card reception”, as shown in FIG. 7, it is a 212 kbps Manchester encoding system, and “212 kbps bidirectional communication” The same. In the communication with the IC card, the non-contact type communication device performs polling, and in this case, since it can recognize that it is communicating in the type C, the "type C card reception" "And" 212 kbps bidirectional communication "can be distinguished.

  In this sense, in the second embodiment, it can be considered that there is no need to determine the existing communication method with the IC card. However, for example, when a reply from the IC card is received in response to polling of type C, when it is necessary to confirm whether this is really “type C card reception”, the method of the second embodiment is also used. It becomes effective.

  As described above, according to the present method, in a non-contact type communication device including a reader / writer device, particularly in a non-contact type communication device such as a non-contact IC card reader / writer capable of NFC bidirectional communication. Since the decoding unit that decodes the received signal received by the antenna can determine which communication method is selected from a plurality of different communication methods based on the received signal waveform, conventional inter-IC card communication In addition, it is possible to support a plurality of types of communication methods in bidirectional communication between reader / writer devices. In addition, since only one of the plurality of decoders is operated, power consumption can be suppressed.

  Patent Document 1 has a polling transmission unit corresponding to a plurality of communication methods and a reception unit having a decoding function corresponding to a plurality of communication methods, and waits for a reception signal of a communication method corresponding to polling. Yes. In addition, a control method has been proposed in which the time width of the demodulated input signal is measured by response signal detection, and the modulation method is determined from the measurement result, but the pulse width differs from that of the regular signal due to the influence of noise and other factors on the demodulated signal. If this happens, there is a possibility of erroneous reception and erroneous detection.

  On the other hand, according to the above-described method, the communication method is determined based on the number of detections of the data change point. Therefore, even if the number of detections changes slightly due to the influence of noise or the like, a certain margin is added to the determination condition. Accordingly, it is possible to reduce erroneous reception / detection. In addition, according to this method, not only conventional inter-IC card communication but also bidirectional communication between reader / writer devices and the like, and the period for counting the number of data change point detections from the reception start timing By extending the length and adjusting the detection threshold, it is possible to improve detection accuracy and reduce erroneous reception / detection.

It is a figure which shows the example of whole structure of the non-contact-type communication apparatus of this example. It is a figure which shows the structural example of the decoding part in the control part of FIG. (A)-(c) is the operation | movement timing chart figure of the decoding part in Example 1. FIG. It is a figure which shows the determination conditions in the communication system and transfer rate determination part of Example 1. FIG. (A), (b) is the operation | movement timing chart figure of the decoding part in Example 2. FIG. It is a figure which shows the determination conditions in the communication system and transfer rate determination part of Example 2. It is a figure which shows the specification of each communication system with an IC card and a reader / writer. It is a figure which shows the specification of each communication system of NFC bidirectional communication. (A)-(e) is a figure which shows the example of a waveform by each communication system of FIG. (A)-(c) is a figure which shows the example of a waveform by each communication system of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Non-contact communication apparatus 11 Control part 11a Decoding part 12 RF transmission control part 13 RF reception control part 14 Modulation part 15 Amplification part 16 Carrier oscillator 17 A / D conversion part 18 Demodulation part 19 Antenna part 21 Data change point detection part 22 Reference time generation timer unit 23 Change point detection counter unit 24 Communication system / transfer rate determination unit 25 Data selection unit 26 Decoding unit 26a System A decoding unit 26b System B decoding unit 26c System C decoding unit 27 Data selection unit 30 Communication system determination Table 31 Data change point counter value (judgment condition)
32 Determination result 40 Communication system etc. determination table 41 Data change point counter value (determination condition)
41a Measurement period 1
41b Measurement period 2
42 Judgment results

Claims (6)

A non-contact type communication device that performs non-contact data transmission / reception with a non-contact type information medium or other non-contact type communication device, and supports at least a plurality of types of communication methods by bidirectional communication,
A demodulating unit that demodulates a received signal from the antenna unit and outputs demodulated data; and a decoding unit that inputs the demodulated data and decodes the demodulated data,
The decoding unit
Data change point detecting means for detecting each change point of the demodulated data;
Timer control means for determining a reception start timing from a detection result by the data change point detection means, and measuring a predetermined period from the reception start timing;
Data change point counter control means for counting the number of times the data change point is detected by the data change point detection means;
A plurality of decoding means corresponding to each of the plurality of types of communication methods;
A selection means for selecting a decoding means for decoding the inputted demodulated data from the plurality of decoding means;
A communication method determination unit that determines a communication method based on the number of times of detection of the data change point within the predetermined period, and causes the selection unit to select a decoding unit corresponding to the determined communication method;
A non-contact communication apparatus characterized by comprising: The timer control means performs measurement for the predetermined period a plurality of times,
The communication method determining means determines the communication method of the received signal based on the number of detections of data change points of the demodulated data at a plurality of different timings from the reception start timing according to the measurement of the plurality of times. The contactless communication apparatus according to claim 1, wherein   The contactless communication apparatus according to claim 1, wherein the predetermined period corresponds to 1 bit time of a transfer rate of 106 kbps.   The predetermined period corresponds to half the time of 1-bit time at a transfer rate of 106 kbps, and the communication method determination unit is configured to perform half of the 1-bit time from the reception start timing by setting the plurality of measurements to two times. The communication method of the received signal is determined based on the number of detections of the data change point at two timings, a timing when the time elapses and a timing when the 1-bit time elapses from the reception start timing. 3. The non-contact communication device according to 2.   5. The non-contact type according to claim 1, wherein the plurality of types of communication methods are at least “424 kbps bidirectional communication”, “212 kbps bidirectional communication”, and “106 kbps bidirectional communication”. Communication device. A device that performs non-contact data transmission / reception with a non-contact type information medium or another non-contact type communication device and supports at least a plurality of types of communication methods using bidirectional communication, and receives a reception signal from an antenna unit. In the decoding unit in the non-contact communication apparatus, including a demodulating unit that demodulates and outputs demodulated data, and a decoding unit that inputs the demodulated data and decodes the demodulated data,
Data change point detecting means for detecting each change point of the demodulated data;
Timer control means for determining a reception start timing from the detection result by the data change point detection means, and measuring a predetermined period from the reception start timing;
Data change point counter control means for counting the number of times the data change point is detected by the data change point detection means;
A plurality of decoding means corresponding to each of the plurality of types of communication methods;
A selection means for selecting a decoding means for decoding the inputted demodulated data from the plurality of decoding means;
A communication method determination unit that determines a communication method based on the number of times of detection of the data change point within the predetermined period, and causes the selection unit to select a decoding unit corresponding to the determined communication method;
The decoding part of the non-contact-type communication apparatus characterized by having.