JP2005341471A - Noncontact information communications system and noncontact information communications device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a master unit efficiently receive an ID from a slave unit. <P>SOLUTION: In a noncontact information communications system, composed of a first communication device and a plurality of second communications devices for transmitting identification information to the first communications device, the first communications device is designed to detect the collision state of a signal transmitted from the second communications device by bits; to transmit a collision notification to the second communication device, when the collision state is detected; and to translate the detected bit of the collision state to a predetermined logical value. The second communication device is designed to stop the transmission of the identification information, if the last transmission bit is different from the predetermined logical value, when the collision notification is received. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a contactless information communication system including a parent device and a plurality of child devices, and more particularly to a technique for suppressing collision of response signals by a plurality of child devices.

  In recent years, non-contact information communication systems such as ISO / IEC14443 and ISO / IEC15693 are used not only as tickets but also as logistics tags.

  Non-contact information communication is characterized in that half-duplex communication is performed with one access channel by electromagnetic induction for communication between a master unit and a plurality of slave units. Since one access channel is shared by the parent device and the plurality of child devices, the parent device performs communication by designating a specific child device from among the plurality of child devices existing in the communication area. In order to designate a specific child device, the parent device needs to communicate using identification information (ID) unique to each child device, and needs to acquire the ID of the child device.

  Therefore, the parent device transmits an ID request signal in order to obtain the IDs of all the child devices existing in the communication area. Then, since it is not possible to decide the response order between the slave units for the ID request signal of the master unit, a plurality of slave units transmit the ID response signal at the same timing. For this reason, collision of ID response signals occurs, and the parent device cannot receive a normal ID response signal.

  As an example for preventing such a collision, the bit / collision prevention procedure of ISO / IEC1443-TypeA is known. With reference to FIG. 8, the bit correspondence collision prevention procedure of ISO / IEC14443-TypeA will be described.

  FIG. 8 is a timing chart of ISO / IEC14443-TypeA bit-corresponding collision prevention procedure, showing a communication process between the parent device 1001 and the child devices A1002, B1003, and C1004 in the communication area.

  As a premise for explaining the communication process, “0000” is set as the ID for the slave unit A 1002, “0010” is set for the slave unit B 1003, and “1010” is set as the ID for the slave unit C 1004. In addition, the ID request signal transmitted by the parent device 1001 can include a part of the ID (condition ID) that is a condition as to whether or not the child devices 1002, 1003, and 1004 can transmit the ID response signal. Only the slave units 1002, 1003, and 1004 having IDs that match are transmitted to the master unit 1001.

  Further, in order to realize this collision prevention procedure, the slave unit 1002, 1003, 1004 indicates a bit collision state to the master unit 1001 (i.e., the same bit of responses from a plurality of slave units is “0” and “1”). The ID is transmitted using bit encoding that can be detected as a state in which there is a waveform in the entire transfer area), that the base unit 1001 can detect the collision position in bit units, and the slave units 1002, 1003, and 1004 It is necessary to transmit the ID to the base unit 1001 at the same timing with respect to the ID request signal.

  The master unit 1001 that requests the IDs of the slave units 1002, 1003, and 1004 in the communication area transmits the first ID request signal 1008 that does not include the condition ID.

  When the slave units 1002, 1003, and 1004 receive the ID request signal 1008, the slave unit A 1002 sends the IDA response signal 1005, the slave unit B 1003 sends the IDB response signal 1006, and the slave unit C 1004 sends the IDC response signal 1007 to the master unit 1001 at the same timing. Send.

  Base unit 1001 receives ID response signal 1009 including a bit collision state. The second bit and the fourth bit of the ID response signal 1009 are “0”, and the first bit 1020 and the third bit 1021 are in a bit collision state.

  Base unit 1001 reads the first bit, which is the first bit collision state, as ‘0’. Then, base unit 1001 transmits a second ID request signal 1010 including a condition ID whose first bit is “0”.

  In response to the second ID request signal 1010, the slave unit A 1002 and the slave unit B 1003 whose first bit of ID is “0” receives the remaining three bits of the IDA response signal 1011 and the IDB response signal 1012 except the first bit. Transmit to base unit 1001. On the other hand, handset C1004 whose first ID bit is not “0” does not transmit IDC response signal 1013.

  Then, base unit 1001 receives ID response signal 1014 including bit collision state 1022 in the third bit.

  Base unit 1001 replaces the third bit in a bit collision state with “0”. Then, base unit 1001 transmits a third ID request signal 1015 including a condition ID of “000” up to the third bit where the received ID response signal 1014 collides.

  In response to the ID request signal 1015 for the third time, handset A 1002 in which the first to third bits of ID are '000' transmits the remaining 1-bit IDA response signal 1016. On the other hand, the slave unit B 1003 and the slave unit C 1004 whose first to third bits of ID are not “000” do not transmit the response signals 1017 and 1018.

  Master device 1001 receives ID response signal 1019 without a bit collision state, and acquires ID “0000” of slave device 1002.

  By repeating the same operation, the master unit 1001 can acquire the IDs of all the slave units 1003 and 1004 in the communication area.

In addition, there is another method for preventing the collision between the slave units. The slave unit transmits a response signal to the master unit ID request signal when the slave unit transmits a response signal of the other slave unit. A technique is known in which when a signal transmission is detected, the transmission of the response signal is stopped, thereby suppressing the collision of response signals by a plurality of slave units. (For example, see Patent Document 1)
JP 2001-136100 A International Standard ISO / IEC144443-3 Standard

  In the above-described ISO / IEC14443-TypeA bit-corresponding collision prevention procedure, when N slave units exist in the communication area, the number (Q) of the master unit sending the ID request signal is Q = 2 × (N -1) represented by +1.

  Therefore, if the number of slave units existing in the communication area increases, the exchange of the ID request signal and the ID response signal increases, and the master unit takes time to receive the slave unit ID. In the non-contact information communication system, since the slave unit can move within the communication area, an increase in the time for receiving the slave unit ID causes a problem that the slave unit cannot be captured while staying in the communication area.

  It is an object of the present invention to receive all IDs of slave units within a communication area with a single ID request signal, so that the master unit can efficiently receive IDs from the slave units.

  The present invention provides a contactless information communication system including a first communication device and a plurality of second communication devices that transmit identification information to the first communication device. The bit which detected the collision state of the signal which the said 2nd communication apparatus transmitted detected in bit unit, and when the said collision state was detected, transmitted a collision notification to the said 2nd communication apparatus When the second communication device receives the collision notification, the second communication device stops transmitting the identification information when the immediately preceding transmission bit is different from the predetermined logical value. Features.

  ADVANTAGE OF THE INVENTION According to this invention, the time which a main | base station receives ID from a some subunit | mobile_unit can be shortened.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a system configuration diagram of a contactless information communication system according to an embodiment of the present invention.

  The communication system according to the present embodiment includes a single parent device 600, a child device A500 (A), a child device B500 (B), and a child device C500 (C). The child device A 500 (A), the child device B 500 (B), and the child device C 500 (C) are in the communication area 700 of the parent device 600.

  Master device 600 has a reader and writer function. The subunit | mobile_unit 500 is a non-contact IC card etc., and each unique identification information (ID510) is set. Specifically, the slave device A 500 (A) is “0000” (510 (A)), the slave device B 500 (B) is “0010” (510 (B)), and the slave device C 500 (C) is “1010” (510). (C)) is set as ID 510.

  When the parent device 600 requests the ID 510 of the child device 500 in the communication area 700, the parent device 600 transmits an ID request signal to the communication area 700 (701). The slave device 500 that has received the ID request signal 701 transmits the unique ID 510 to the master device 600 as an ID response signal in bit units (702, 703, 704).

  FIG. 2 is a block diagram of base unit 600 according to the embodiment of this invention.

  Antenna coil 601 receives a signal from slave unit 500 and transmits a signal to communication area 700. The transmission unit 602 drives the antenna coil 601 to transmit a signal to the communication area 700.

  The switching unit 603 switches the bit encoding unit 604 or the collision notification generation unit 605 in units of bits and connects to the transmission unit 602 in order to transmit a signal to the communication area 700 at an appropriate timing. The bit encoding unit 604 encodes the ID request signal 701 to be transmitted to the communication area 700 in bit units. The collision notification generation unit 605 generates a collision notification pulse to be transmitted to the communication area 700.

  The bit logical value determination unit 606 determines ‘0’ or ‘1’ for each bit of the signal received from the slave device 500 and decoded. The bit collision detection unit 607 determines whether or not there is a collision in the bit unit of the signal received from the slave unit 500 and decoded. Bit decoding section 608 decodes the signal received from slave unit 500.

  The receiving unit 609 amplifies and detects the signal received by the antenna coil 601 and extracts the signal from the slave unit 500. The RF unit 610 includes a transmission unit 602 and a reception unit 609.

  The external interface unit 611 communicates with a computer device (not shown) connected to the parent device 600. The control unit 612 is configured by a microprocessor and RAM and ROM necessary for processing thereof, and controls the entire base unit 600.

  FIG. 3 is a block diagram of handset 500 according to the embodiment of the present invention.

  The antenna coil 501 receives a signal from the parent device 600 or transmits a signal to the parent device 600. The receiving unit 502 amplifies and detects a signal received by the antenna coil 501 and extracts a signal from the parent device 600.

  Bit decoding section 503 decodes the signal received from base unit 600. The collision notification detection unit 504 determines in bit units whether or not there is a collision notification pulse in the signal received from the parent device 600. The bit logical value determination unit 505 determines whether the decoded signal received from the base unit 600 is “0” or “1” in bit units.

  Bit encoding section 506 encodes ID response signal 702 and the like transmitted to base unit 600 in bit units.

  Transmitting section 507 drives antenna coil 501 to transmit the signal encoded by bit encoding section 506 to base unit 600. The RF unit 508 includes a reception unit 502 and a transmission unit 507.

  The nonvolatile memory 509 stores necessary information such as a program for driving the slave unit. The unique ID 510 stores a unique identification code (ID) of each child device 500. The control unit 511 includes a microprocessor and RAM and ROM necessary for processing thereof, and controls the entire slave unit 500.

  Although not particularly shown, a power supply circuit that supplies power extracted from a signal received from the parent device for the operation of the entire child device 500 is included.

  FIG. 4 is a timing chart of the bit encoding system according to the embodiment of the present invention, and shows a process of transmitting one bit of ID from the slave unit 500 to the master unit 600.

  The 1-bit signal notified from the slave unit 500 to the master unit 600 is “1” (101) or “0” (102). Also, the information of ID1 bit transmitted from the slave unit to the master unit is roughly divided into transfer areas 103 and 105 in the first half and collision notification areas 104 and 106 in the second half.

  The transfer areas 103 and 105 are used for the slave device 500 to transmit an ID to the master device 600. In this embodiment, Manchester encoding is used, and when handset 500 notifies base unit 600 of “1” (103), it transmits a signal to the first half of the transfer area and sets “0” (105). When notifying, a signal is transmitted to the latter half of the transfer area. However, any bit encoding may be used as long as the bit collision state can be detected by an irregular code (a state in which there is a waveform in the entire transfer area). Also, bit encoding by subcarrier modulation may be used.

  On the other hand, the collision notification areas 104 and 106 are used to notify the child device 500 that the parent device 600 has detected a bit collision state. When base unit 600 detects a bit collision state, a collision notification pulse is transmitted to communication area 700 in collision notification areas 104 and 106. Therefore, handset 500 determines that a bit collision state has occurred in the immediately preceding transfer area when a collision notification pulse is received in collision notification areas 104 and 106, and a bit collision state has occurred when not received. Judge that there is no.

  Accordingly, the slave device 500 that has received the ID request signal 701 from the master device 600 performs transmission processing in the transfer areas 103 and 105 and performs reception processing in the collision notification areas 104 and 106. On the other hand, base unit 600 performs reception processing in transfer areas 103 and 105 and performs transmission processing in collision notification areas 104 and 106.

  FIG. 5 is a timing chart of the embodiment of the present invention, and a communication process between the parent device 201 and the child devices A 500 (A), B 500 (B), and C 500 (C) in the communication area 700. Indicates.

  When base unit 600 requests the ID of handset 500 in communication area 700, base unit 600 transmits ID request signal 205 to communication area 700.

  Slave unit 500 receives ID request signal 205 and after a predetermined time Ta has elapsed, transmits each ID to base unit 600 in bit units. This is the first ID response 209. Specifically, the slave device A 500 (A) receives the IDA response signal 206, the slave device B 500 (B) receives the IDB response signal 207, and the slave device C 500 (C) receives the IDC response signal 208 for each bit at the same timing. Send to.

  In the first ID response 209, first, the handset 500 transmits the first bits of the ID response signals 206, 207, and 208 simultaneously. Specifically, the slave device A transmits “0”, the slave device B “0”, and the slave device C simultaneously transmits “1” to the master device 600. Then, base unit 600 detects bit collision state 220.

  Base unit 600 that has detected bit collision state 220 transmits collision notification pulse 210 to communication area 700. Further, base unit 600 determines that the bit having the collision has received ‘0’, and reads the first bit having the collision into ‘0’ having a value different from the transmission stop condition.

  Upon receiving the collision notification pulse 210 from the parent device 600, the child device 500 transmits the ID response signals 206, 207, 208, etc. when the transmission stop condition is met (when the immediately preceding transmission bit is “1”). Stop. That is, when the slave unit 500 receives the collision notification pulse 210, the slave unit C500 (C) that matches the transmission stop condition stops transmission of the IDC response signal 208 after the second bit. On the other hand, the slave unit A 500 (A) and the slave unit B 500 (B) that do not match the transmission stop condition transmit the second bit “0” of the ID response signals 206 and 207 to the master unit 600 at a predetermined timing. Then, base unit 600 receives “0” in the second bit.

  Subsequently, handset A500 (A) sends the third bit “0” of IDA response signal 206 to handset 600, and handset B500 (B) sends the third bit “1” of IDB response signal 207 to base unit 600 at a predetermined timing. Send. Then, base unit 600 detects bit collision state 221.

  Base unit 600 that has detected bit collision state 221 transmits a collision notification pulse in the third bit collision notification area. Furthermore, base unit 600 replaces the third bit in which the collision has occurred with “0”.

  When the slave unit 500 receives the collision notification pulse 211, the slave unit B 500 (B) that matches the transmission stop condition stops transmission of the fourth bit IDB response signal 207. On the other hand, slave unit A 500 (A) that does not match the transmission stop condition transmits “0” of the fourth bit of IDA response 206 to master unit 600.

  As a result, base unit 600 acquires ID of handset A 500 (A) in the first ID response 209. This completes the first ID response 209.

  Since handset A 500 (A) has transmitted all bits of the ID, ID is not transmitted in the second and subsequent ID responses 214, 217, and 218.

  After a certain time Tc has elapsed from the end of the first ID response 209, the slave unit B 500 (B) and the slave unit C 500 (C) have not finished transmitting all bits of the ID. Start. In the second ID response 214, first, the slave device B 500 (B) sets “0” of the first bit of the IDB response signal 212, and the slave device C 500 (C) sets “1” of the first bit of the IDC response signal 213. Simultaneously transmit to base unit 600. Then, base unit 600 detects bit collision state 222.

  Base unit 600 that has detected bit collision state 222 transmits collision notification pulse 215 to communication area 700. Furthermore, base unit 600 replaces the first bit in which the collision has occurred with “0”.

  In the slave unit 500 that has received the collision notification pulse 215, the slave unit C500 (C) that matches the transmission stop condition stops transmission of the IDC response 213 after the second bit. On the other hand, slave unit B 500 (B) that does not match the transmission stop condition transmits IDB response 212 after the second bit to master unit 600 in bit units.

  Thereafter, since a bit collision state does not occur, handset B 500 (B) transmits all bits of the ID to base unit 600. Master device 600 acquires the ID of slave device B 500 (B) in the second ID response 214.

  Slave unit B 500 (B) has transmitted all bits of the ID, and therefore does not transmit the ID in the third and subsequent ID responses 217 and 218.

  After a predetermined time Tc has elapsed from the end of the second ID response 214, the slave C500 (C) has not finished transmitting all the bits of the ID, and therefore starts the third ID response 217. Even in the third ID response 217, handset C 500 (C) transmits IDC response signal 216 to base unit 600 in bit units.

  In the third ID response, only the slave unit C500 (C) transmits the ID, and no bit collision occurs, so the slave unit C500 (C) transmits all the bits of the ID to the master unit 600. Master device 600 acquires the ID of slave device C 500 (C) by the third ID response 217.

  The slave C500 (C) has transmitted all the bits of the ID, and therefore does not transmit in the fourth ID response 218.

  In the fourth ID response 218, since all the slave units 500 have finished transmitting all bits of the ID, the slave unit 500 does not transmit the ID and no response is made.

  When the time when there is no ID response signal from slave device 500 exceeds a certain time, master device 600 determines that the IDs of all slave devices 500 in communication area 700 have been acquired, and performs processing for ID request signal 205. finish.

  In this embodiment, the transmission stop condition of the slave unit 500 that has received the collision notification pulse 210 or the like is “1”, and the master unit 600 has read the collided bit as “0”. The base unit 600 can implement the communication system of the present invention even if the base unit 600 reads the collided bit as “1”.

  FIG. 6 is a flowchart of base unit 600 according to the embodiment of the present invention.

  When an ID request command is issued from a computer device connected to parent device 600, parent device 600 transmits ID request signal 205 to communication region 700 in order to obtain the ID of child device 500 in communication region 700. (401).

  Master device 600 waits for a predetermined time Ta until slave device 500 receives ID request signal 205 and transmits an ID (402).

  After a predetermined time Ta has elapsed, base unit 600 determines whether or not to receive ID response signal 206 or the like of slave unit 500 within response period Tb (403).

  When the base unit 600 does not receive the ID response signal 206 or the like from the handset 500 within the response period Tb, the handset 500 does not exist in the communication area 700 or the handset 500 in the communication area 700 transmits an ID. It is determined that the processing has been completed, and the processing for this ID request signal 205 is terminated (411). On the other hand, when receiving the ID response signal 206 or the like of the child device 500, the parent device 600 performs processing for acquiring the ID of the child device 500 (404 to 410).

  First, base unit 600 receives one bit of ID of handset 500 (404), and determines whether or not the received bit is in a bit collision state (405).

  When a waveform is detected in the entire transfer area and a bit collision state is detected, base unit 600 transmits collision notification pulse 210 to communication area 700 (406), and replaces the bit causing the collision with '0'. (407), go to Step 408. On the other hand, if it is not in the collision state, the process proceeds to step 408 as it is.

  Thereafter, base unit 600 determines whether or not reception of all bits of the received ID of handset 500 has been completed (408).

  If reception of all the bits of the ID has not been completed, the process returns to step 404 in order to receive the next bit of the ID of the slave unit 500. When the reception of all bits of the ID is completed, base unit 600 transmits the received ID through external interface 611, stores the received ID in the computer, and ID response signal 206 from other slave unit 500. Etc. are prepared (409).

  Master device 600 waits for a certain time Tc until slave device 500 transmits an ID (410), and returns to step 403 in order to receive an ID from another slave device 500.

  FIG. 7 is a flowchart of slave unit 500 according to the embodiment of the present invention.

  When receiving the ID request signal 205 transmitted from the parent device 600, the child device 500 transmits an ID response signal 206 or the like to the parent device 600 at the same timing between the child devices, and waits for a predetermined time Ta (301). .

  The slave unit 500 waits for a predetermined time Ta, and then determines whether or not the transmission of all bits of the ID to the master unit 600 is completed in response to the ID request signal 205 (302).

  If handset 500 has finished transmitting all bits of the ID to base unit 600, processing for ID request signal 205 ends (310). On the other hand, if the transmission of all bits of the ID to the parent device 600 has not been completed, the child device 500 performs processing for transmitting the ID to the parent device 500 in bit units (303 to 309).

  First, handset 500 transmits the ID to base unit 600 bit by bit (303).

  The child device 500 that has transmitted 1 bit of ID waits in order to receive the collision notification pulse 210 and the like from the parent device 600 in the collision notification areas 104 and 106 (304).

  Slave device 500 determines whether or not collision notification pulse 210 or the like has been transmitted from parent device 600 to collision notification areas 104 and 106 (305).

  If the collision notification pulse 210 or the like is not received, the slave unit 500 returns to step 302 to continuously transmit the next bit of the ID. On the other hand, when the collision notification pulse 210 or the like is received, the slave unit 500 determines whether or not the bit transmitted immediately before matches the transmission stop condition (306).

  If the bit transmitted immediately before does not match the transmission stop condition, handset 500 returns to step 302 to continue transmitting the next bit of ID. On the other hand, when the transmission stop condition is met, the slave unit 500 stops the ID transmission (307).

  The slave unit 500 that has stopped the ID transmission waits until the ID transmission completion Tb of the other slave unit 500 (308). Further, a plurality of slave units 500 wait for Tc transmission for a certain time until the next ID response transmission timing so that IDs can be transmitted to the master unit 600 at the same timing (309).

  The slave unit 500 that has waited for Tc transmission for a predetermined time returns to step 302 to transmit the ID to the master unit 600 again from the first bit.

  As described above, the contactless communication system of the present invention transmits the collision notification pulse of the base unit 600 and replaces the collision bit, stops the transmission of ID by receiving the collision notification pulse of the slave unit 500, and transmits all bits of the ID. Occasionally, by providing the ID response signal retransmission prohibition function, the IDs of all the slave units 500 in the communication area 700 can be acquired by transmitting the ID request signal 205 once by the master unit 600.

  According to the present invention, the time for the master unit to receive the IDs of a plurality of slave units can be greatly shortened. Therefore, the present invention is preferably applied to a distribution tag that requires communication with a large number of slave units.

1 is a system configuration diagram of a contactless information communication system according to an embodiment of the present invention. It is a block diagram of the main | base station of embodiment of this invention. It is a block diagram of the subunit | mobile_unit of embodiment of this invention. It is a timing chart of the bit encoding system of the embodiment of the present invention. It is a timing chart of an embodiment of the invention. It is a flowchart of the main | base station of embodiment of this invention. It is a flowchart of the subunit | mobile_unit of embodiment of this invention. It is a timing chart of the bit correspondence collision prevention procedure of ISO / IEC14443-TypeA.

Explanation of symbols

500 (A) Handset A
500 (B) Handset B
500 (C) Handset C
501 Antenna coil 502 Reception unit 503 Bit decoding unit 504 Collision notification determination unit 505 Bit logical value determination unit 506 Bit encoding unit 507 Transmission unit 508 RF unit 509 Non-volatile memory 510 ID of the child device
510 (A) ID of handset A
510 (B) ID of handset B
510 (C) ID of handset C
511 Control unit 600 Base unit 601 Antenna coil 602 Transmission unit 603 Switching unit 604 Bit encoding unit 605 Collision notification generation unit 606 Bit logical value determination unit 607 Bit collision detection unit 608 Bit decoding unit 609 Reception unit 610 RF unit 611 Control unit 612 Control unit 700 Communication area 701 of parent device ID request signal 702 of parent device ID response signal 703 of child device A ID response signal 704 of child device B ID response signal of child device C

Claims (7)

In a non-contact information communication system including a first communication device and a plurality of second communication devices that transmit identification information to the first communication device.
The first communication device is:
Detecting a collision state of a signal transmitted by the second communication device in units of bits;
When the collision state is detected, a collision notification is transmitted to the second communication device, and the bit in which the collision state is detected is read as a predetermined logical value,
When the second communication device receives the collision notification, the second communication device stops the transmission of the identification information when the immediately preceding transmission bit is a value different from the predetermined logical value. system.   2. The non-transmission device according to claim 1, wherein the second communication device transmits the identification information again at a next identification information transmission timing when transmission of all bits of the identification information is not completed. Contact information communication system.   The first communication apparatus transmits the collision notification by transmitting a pulse signal at a predetermined timing after a bit in which a collision state is detected and before transmission of a next bit. The contactless information communication system according to 1 or 2. In a non-contact information communication device having a transmission / reception unit that transmits a control signal to another communication device and receives identification information from the other communication device, and a control unit that controls the transmission / reception unit,
Sending identification information requests to other communication devices,
Detecting the logical value or collision state of the signal transmitted by the other communication device in units of bits;
When the bit collision state is detected, after the bit detecting the collision state, at a predetermined timing before transmission of the next bit, the collision state is notified by transmitting a signal to the other communication device,
A non-contact information communication apparatus, wherein a bit having the collision state is read as a predetermined logical value.   5. The contactless information communication according to claim 4, wherein after the identification information request is transmitted, the identification information reception process is terminated when the identification information is not received from the other communication device for a predetermined time or more. apparatus. In a non-contact information communication device having a transmission / reception unit that receives a control signal from another communication device and transmits identification information to the other communication device, and a control unit that controls the transmission / reception unit,
Upon receiving an identification information request from another communication device, the identification information is transmitted to the other communication device in bits,
When a collision state is notified at a predetermined timing after transmission of the identification information from the other communication device and before transmission of the next bit, the immediately preceding transmission bit is different from a predetermined logical value. In addition, transmission of the identification information is stopped.   The contactless information communication apparatus according to claim 6, wherein when the transmission of all bits of the identification information is not finished, the identification information is transmitted again at the next identification information transmission timing.

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