JP3969430B2 - Contactless ID system - Google Patents

Description

  The present invention relates to a contactless ID system that performs wireless communication with a contactless IC (Integrated Circuit) card via a carrier wave having a predetermined frequency.

  An RFID system, which is a non-contact ID system using a non-contact information medium such as a non-contact IC (Integrated Circuit) card, has been devised and implemented. An RFID system is used for information communication between an IC chip built in a non-contact information medium and a card reader. For example, it is used for automatic ticket gates at stations and rental of books in libraries. It is expected to be used for exchanging personal information in various fields in the future.

  The non-contact IC card is a general term for a non-contact information medium having a card shape such as a so-called credit card, and a non-contact information medium other than the card shape, for example, a label size smaller than a credit card, a stamp In addition to the card size, the size includes a non-contact information medium having various shapes such as a round shape and a star shape.

  For example, in an RFID system using an electromagnetic induction method, a non-contact information medium receives radio waves transmitted from a card reader, obtains operating power from the received radio waves by electromagnetic induction, and uses the radio waves to communicate with a card reader. Data communication between them. The non-contact information medium and the card reader each have an antenna coil for transmitting and receiving this radio wave. The appropriate communication distance between the electromagnetic induction card reader and the non-contact information medium is approximately several centimeters to several tens of centimeters.

In such an RFID system, a multi-card reader system that can handle a single contactless IC card with different communication standards may be used (see, for example, Patent Document 1).
JP 2001-143023 A

  Such an RFID system includes, for example, a card reader system 200 in which a host management device 210 as shown in FIG. 6 and an interrogator (reader module) 220 are connected by a serial cable 201, and a non-contact IC card 250. Can be realized.

  The host management device 210 of the card reader system 200 makes a card capture request as a question request to the interrogator 220, and the interrogator 220 in response to the request generates a question signal. Queries the communication standard.

  When there is a response from the non-contact IC card 250, non-contact communication is executed between the non-contact IC card 250 and the card reader system 200 according to the inquired communication standard.

  In the RFID system, the card reader system 200 shown in FIG. 6 includes a plurality of interrogators 220, thereby realizing a multi-card reader system that supports one contactless IC card with a different communication standard.

  In such a card reader system 200, each time a question request is output from the higher-level management device 210 to the interrogator 220, a question signal is generated and transmitted by the interrogator 220, so that processing corresponding to the question request is performed. This requires a lot of power consumption.

  In particular, when a query request is continuously output from the host management device 210, the temperature becomes considerably high, and therefore a countermeasure against heat is necessary from the viewpoint of circuit maintenance and safety. However, in the past, there is a problem that effective heat countermeasures have not been taken.

  Therefore, the present invention has been devised to solve the above-described problem, and is suitable for a heat generation due to an increase in processing load on the card reader due to a question request that is continuously output with an inexpensive configuration. An object is to provide a non-contact ID system in which the amount of heat is suppressed by taking measures against heat.

  The non-contact ID system of the present invention includes a non-contact IC (Integrated Circuit) card that stores a unique identifier, and an inquiry signal that inquires about the communication standard of the non-contact IC card in response to an inquiry request transmitted from the outside. A card reader having an interrogator for receiving a response signal including the unique identifier from the non-contact IC card, and a request for inquiring the communication standard of the non-contact IC card to the interrogator. And a higher management device that authenticates the contactless IC card as a communication target from the response signal received by the interrogator, and the card reader is transmitted from the higher management device. Each time the question request is received, the first time measuring means for starting the time measurement and the question request by the interrogator timed by the first time measuring means are processed. A time holding means for holding the processing time to be processed, an end time at which the processing of the question request is completed, a processing time for processing the question request of the interrogator, and an increased heat amount that increases in accordance with the processing time. Stores a heat quantity increase / decrease table comprising a related table, a table that associates an elapsed time since the processing for the question request in the interrogator is completed, and a reduced heat quantity that decreases according to the elapsed time. Each time the question request is transmitted to the table storage means and the interrogator, the heat amount increase / decrease table stored in the table storage means is referred to and the processing time held in the time holding means is determined. The corresponding increase heat quantity is acquired, and the end time held by the time holding means with reference to the heat quantity increase / decrease table stored in the table storage means And a decrease heat amount corresponding to an elapsed time obtained from the time when the question request timed by the first time measuring means is received, and the acquired increase heat amount and the decrease heat amount are cumulatively added each time. Thus, when the heat quantity estimation means for estimating the current heat quantity of the interrogator and the current heat quantity of the interrogator estimated by the heat quantity estimation means exceeds a predetermined threshold value, the heat quantity is stored in the table storage unit. Referring to the heat amount increase / decrease table, a stop request for stopping the transmission of the question request by obtaining a decrease time required for the current heat amount of the interrogator to be equal to or less than the predetermined threshold, and the decrease Stop request transmitting means for transmitting the time to the higher order management apparatus, and the higher order management apparatus receives a second stop request transmitted from the stop request transmission means, and starts a second time measurement. Total Time control means, and control means for controlling to stop transmission of the question request to the interrogator until the time counted by the second time measurement means has elapsed by the decrease time. The above-mentioned problem is solved.

  In the non-contact ID system of the present invention, the card reader can estimate the heat amount of the interrogator by the heat amount estimation means using the heat amount increase / decrease table, and can ask the stop of the question request according to the estimated heat amount. Question requests that are automatically sent from the host management device can be internally adjusted at the card reader side, the receiver side, to ensure a reduction in computing power due to the generated heat and the occurrence of a fire in the worst case. It is possible to suppress it.

  Further, with this configuration, it is not necessary to separately provide sensors for obtaining the amount of heat, so that it is possible to avoid a significant increase in cost and an increase in the size of the apparatus.

  Furthermore, using the fact that a plurality of interrogators are provided, the waiting time is processed by controlling the interrogator that has not been requested to stop to be sent a question request from the host management device. Since it can be devoted to time, it is possible to execute processing for an efficient question request. Since the upper management apparatus is also notified of the time during which transmission is possible from the stopped state, it is possible to transmit the question request with further efficiency by the upper management apparatus.

[First Embodiment]
First, the non-contact ID system shown as the first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, the non-contact ID system shown as the first embodiment of the present invention includes a card having a host management device 20 such as a PC (Personal Computer) and a card reader 10 which is a reader module. A reader system 30 and a non-contact IC card 50 are provided.

  This non-contact ID system is, for example, an RFID (Radio Frequency IDentification) system using an electromagnetic induction method (electromagnetic coupling method) that uses a frequency band of 13.56 MHz or less, and a non-contact IC card 50 that is a non-contact information medium. The radio wave transmitted from the card reader system 30 is received to obtain operating power by electromagnetic induction, and data communication is performed with the card reader system 30 using this radio wave.

  The non-contact ID system shown as the first embodiment of the present invention is not limited to the electromagnetic induction system described above, but is a radio wave system (micro) that secures power using a frequency band higher than the UHF band. (Wave system) may be used. For the sake of explanation, the following description will be made by applying an electromagnetic induction method that secures power using a frequency of 13.56 MHz.

  The card reader system 30 includes an antenna (antenna coil) 17 as an inductor in the card reader 10, and uses a radio wave obtained by modulating a carrier wave with a frequency fc (for example, around 13.56 MHz) as a carrier frequency. Wireless communication with the IC card 50 is performed. In the following description, the carrier frequency is the carrier frequency fc, but the carrier frequency fc is not limited to 13.56 MHz.

  At the time of data transmission, the card reader 10 of the card reader system 30 generates a transmission signal by modulating a carrier wave having a carrier frequency fc with data to be transmitted. As a data modulation method, ASK (Amplitude Shift Keying), PWM (Pulse Width Modulation), PSK (Phase Shift Keying), or the like can be used.

  The modulated and generated transmission signal is supplied to the antenna 17 to generate a magnetic field. The magnetic field generated by the antenna 17 changes based on the transmission signal, and data on the carrier wave having the carrier frequency fc is transmitted as a change in magnetic flux.

  At the time of data reception, the card reader 10 of the card reader system 30 demodulates data received from the non-contact IC card 50 and received as a change in magnetic flux by the antenna 17. When data is transmitted from the non-contact IC card 50, an induced current is generated in the antenna 17 due to a change in magnetic flux.

  The induced current generated in the antenna 17 changes based on the magnetic flux, and data on the carrier wave having the carrier frequency fc is transmitted as a change in the induced current.

  The card reader 10 of the card reader system 30 acquires the data transmitted from the non-contact IC card 50 by demodulating the induced current.

  In such a card reader system 30, the upper management apparatus 20 controls the card reader system 30 in an integrated manner and makes a question request to the card reader 10. The card reader 10 negotiates with the non-contact IC card 50 in response to a question request from the host management apparatus 10 and executes data communication according to a communication standard corresponding to the non-contact IC card 50.

  The non-contact IC card 50 conforms to communication standards such as Type A and Type B, which are communication standards of proximity type (communication distance, about 10 cm or less) compliant with ISO 14443 established by the International Organization for Standardization (ISO). It corresponds.

  The non-contact IC card 50 generates an induced electromotive force in a direction that prevents a change in magnetic flux of a radio wave received by an antenna coil (not shown) that is an inductor, and the induced electromotive force causes a frequency fc = 13.56 MHz. Become synchronized.

  The contactless IC card 50 supplied with the operating power receives data transmitted from the card reader system 30 and transmits data to the card reader system 30.

  At the time of data reception, the non-contact IC card 50 demodulates a radio wave transmitted from the card reader system 30 and received as a change in magnetic flux by the antenna coil, and acquires data.

  At the time of data transmission, the non-contact IC card 50 generates a transmission signal by modulating the data with a carrier wave having a carrier frequency fc. The non-contact IC card 50 performs load modulation for modulating the carrier wave by changing the load of the antenna coil according to the data to be transmitted.

  The modulated and generated transmission signal is supplied to the antenna coil to generate a magnetic field. The magnetic field generated by the antenna coil changes based on the transmission signal, and data on the carrier wave having the carrier frequency fc is transmitted as a change in magnetic flux.

  In this way, the card reader 10 generates a question signal in response to a question request for inquiring about a communication standard or the like from the host management device 20 and transmits it to the non-contact IC card 50. When there is a response from the non-contact IC card 50, the upper management apparatus 20 authenticates a unique identifier that uniquely identifies the non-contact IC card 50 attached to the response signal transmitted via the card reader 10, and performs authentication. If so, communication with the non-contact IC card 50 is started. Communication with the non-contact IC card 50 in the card reader system 30 is executed in response to a command put on the question request from the upper management apparatus 20.

  Next, the configuration of the card reader 10 and the upper management device 20 included in the card reader system 30 will be described in more detail with reference to FIG.

  As shown in FIG. 1, the card reader 10 includes a circuit unit (interrogator) 11 that is a reader module, a timer unit 12, a time holding unit 13, a table storage unit 14, a heat quantity estimation unit 15, and a control unit. 16. Further, the card reader 10 includes an antenna 17 that transmits a question signal to the non-contact IC card 50 and receives a response signal from the non-contact IC card 50.

  The circuit unit (interrogator) 11 generates a question signal by performing predetermined processing on the question request transmitted from the upper management device 20.

  The timer unit 12 is connected to the heat quantity estimation unit 15, and starts measuring time each time a question request transmitted from the upper management device 20 arrives at the heat quantity estimation unit 15.

  The time holding unit 13 holds the processing time for processing the question request in the circuit unit (interrogator) 11 and the end time when the processing of the question request ends. In the following description, this processing time and end time are collectively referred to as time information.

  The table storage unit 14 stores a table used for estimating an increase in heat quantity in the circuit unit (interrogator) 11 in the heat quantity estimation unit 15.

  The table stored in the table storage unit 14 includes, for example, a card standard which is a communication standard of the non-contact IC card 50 as shown in FIG. 2, a question request processing time in the circuit unit (interrogator) 11, This is a table in which the amount of heat (increased heat amount) that is increased by is associated. Also, this table is the same as the card standard, and the question request processing is not executed in the circuit unit (interrogator) 11, more specifically, the idling time that is the elapsed time in the idling state after the question request processing is completed. And a table in which the amount of heat decreased thereby (decreased heat amount) is also stored.

  In the following description, a table showing the two types of correspondence stored in the table storage unit 14 is referred to as a heat quantity increase / decrease table.

  The card reader 10 included in the card reader system 30 shown as the first embodiment includes only one circuit unit (interrogator) 11 that is an interrogator. Therefore, the table storage unit 14 includes the circuit unit. (Interrogator) Only the heat amount increase / decrease table corresponding to the communication standard of 11 need be stored.

  The heat quantity estimation unit 15 estimates the heat quantity increased by the processing in the circuit unit (interrogator) 11 using the heat quantity increase / decrease table stored in the table storage unit 14. The specific processing operation of the heat quantity estimation unit 15 will be described in detail later.

  The control unit 16 comprehensively controls the operation of the card reader 10. The control unit 16 monitors whether or not the heat amount estimated by the heat amount estimation unit 15 exceeds a predetermined threshold value, and if so, stops transmission of a question request to the circuit unit (interrogator) 11. A stop request to be requested is generated and transmitted to the upper management apparatus 20. At this time, the control unit 16 obtains a heat amount decrease time during which the estimated heat amount is equal to or less than the threshold value with reference to the heat amount increase / decrease table stored in the table storage unit 14, and transmits the heat amount decrease time to the upper management device 20 together with the stop request. .

  The upper management device 20 includes an upper timer unit 21, an upper control unit 22, and an upper circuit unit 23 that is controlled by the upper control unit 22 and executes predetermined processing in the upper management device 20. The upper timer unit 21 starts timing each time a stop request transmitted from the control unit 16 of the card reader 10 for stopping the question request is received by the upper control unit 22.

  The upper control unit 22 controls the upper management device 20 in an integrated manner. Further, the upper control unit 22 generates and transmits a question request to the card reader 10 at normal times. Further, the upper control unit 22 receives the stop request and the heat amount decrease time transmitted from the control unit 16 of the card reader 10, and the time counted by the upper timer unit 21 passes the heat amount decrease time. In the meantime, transmission of the question request to the card reader 10 is suppressed.

  When the circuit unit (interrogator) 11 of the card reader 10 executes a process according to the question request transmitted from the higher-level management device 20, particularly when the question request is continuously transmitted, the amount of calculation processing is large. There is a risk that the card reader 10 will be heated to a high temperature because it suddenly increases. Thus, if the circuit unit (interrogator) 11 has a high heat, the occurrence of a fire or the operation guarantee range of the circuit unit (interrogator) 11 will be exceeded, and the processing capacity will be reduced. It will cause various harmful effects.

  Therefore, in the non-contact ID system shown as the first embodiment, a processing mechanism for suppressing heat generated in the card reader 10 is provided in the host management device 20 and the card reader 10 as described above. .

  Next, the heat amount suppression processing operation of the non-contact ID system shown as the first embodiment will be described using the flowchart shown in FIG.

  In step S <b> 11, the heat quantity estimation unit 15 acquires from the timer unit 12 the arrival time when the question request arrives at the heat quantity estimation unit 15.

  In step S <b> 12, the heat quantity estimation unit 15 acquires time information held in the time holding unit 13.

  In step S13, the heat quantity estimation unit 15 refers to the heat amount increase / decrease table stored in the table storage unit 14 using the arrival time acquired in step S11 and the time information acquired in step S12, and increases or decreases the heat amount. Ask.

  The time holding unit 13 holds, as time information, a processing time for processing a question request in the circuit unit (interrogator) 11 and an end time at which the processing of the question request is completed in the previous processing loop. .

  Therefore, the current heat increase amount is obtained by referring to the heat amount increase / decrease table from the processing time for processing this question request. Further, the idling time is known from the end time and the arrival time of the new question request acquired in step S11, and the current reduced heat amount is obtained by referring to the heat amount increase / decrease table.

  The heat quantity estimation unit 15 can obtain the heat quantity increase / decrease amount in the current loop from the increased heat quantity and the reduced heat quantity.

  In step S14, the heat quantity estimation unit 15 integrates the estimated integrated heat quantity estimated and held by the heat quantity estimation unit 15 last time and the current heat quantity increase / decrease obtained in step S13, and obtains the current estimated integration value. Find the amount of heat.

  In Step S15, the control unit 16 compares the current estimated integrated heat amount obtained by the heat amount estimating unit 15 with a predetermined threshold value, and determines whether or not the current estimated integrated heat amount exceeds the threshold value. If the current estimated accumulated heat amount exceeds the threshold value, the process proceeds to step S16. If the current estimated cumulative heat quantity does not exceed the threshold value, the process proceeds to step S18.

  In step S <b> 16, the control unit 16 generates a stop request for requesting to stop transmission of the question request to the circuit unit (interrogator) 11, and transmits the stop request to the upper management device 20.

  In addition, the control unit 16 obtains a heat amount decrease time during which the estimated heat amount is equal to or less than the threshold with reference to the heat amount increase / decrease table stored in the table storage unit 14 and transmits the heat amount decrease time to the upper management device 20 together with the stop request.

  In response to this, since the question request is not transmitted from the host management device 20, the control unit 16 is in a standby state until the threshold value and the current estimated integrated heat quantity match.

  In step S <b> 17, the control unit 16 replaces the current estimated integrated heat amount with the threshold value in response to the threshold value being matched with the current estimated integrated heat amount.

  In step S <b> 18, the question request transmitted from the upper management apparatus 20 is transmitted to the circuit unit (interrogator) 11.

  In step S <b> 19, the time holding unit 13 holds the time taken for the processing for the question request of the circuit unit (interrogator) 11 and the time when the processing is completed.

  In step S20, the current estimated integrated heat amount is held as the previous estimated integrated heat amount and used in the next processing loop. Thereby, every time a question request is transmitted from the upper management device 20, the heat amount estimation unit 15 cumulatively adds the heat amount increase / decrease obtained each time by referring to the heat amount increase / decrease table. The amount of heat of the circuit unit (interrogator) 11 can be accurately estimated.

  In this way, by using the heat amount increase / decrease table stored in the table storage unit 14, the heat amount estimation unit 15 estimates the heat amount of the circuit unit (interrogator) 11, thereby automatically transmitting from the upper management device 20. Can be internally adjusted on the card reader 10 side, which is the receiver side, so that it is possible to reliably suppress the deterioration of the arithmetic processing capability due to the generated heat and the occurrence of a fire that is the worst case. .

  Moreover, since it is not necessary to separately provide sensors for obtaining the amount of heat and the like, there is an advantage that a significant increase in cost and an increase in the size of the apparatus can be avoided.

[Second Embodiment]
Subsequently, a non-contact ID system shown as the second embodiment of the present invention will be described.

In the non-contact ID system shown as the first embodiment, the card reader 10 shown in FIG. 1 has one circuit unit (interrogator) 11 that is an interrogator that processes a question request and generates a question signal. It has a configuration with only. As shown in FIG. 4, a plurality of circuit units (interrogators) 11 _N (N is a natural number) having different communication standards in order to make the configuration of the card reader 10 correspond to a plurality of contactless IC cards 50 having different communication standards. ) the case of the multi-card reader 40 equipped with, it is possible to avoid an adverse effect due to increase in the heat of the circuit portion (interrogator) 11 _N.

  The non-contact ID system shown as the second embodiment is a non-contact ID in which the card reader 10 of the non-contact ID system shown as the first embodiment in FIG. 1 is replaced with a multi-card reader 40 shown in FIG. System.

As shown in FIG. 4, the multi-card reader 40 including a plurality of circuit units (interrogators) 11 _N includes a switching device 18 for switching the circuit units (interrogators) 11 _N that supply question signals to the antenna 17. ing.

Since the other configuration of the multi-card reader 40 is the same as that of the card reader 10, overlapping functional units are denoted by the same reference numerals and description thereof is omitted. In addition, since the heat amount increase / decrease table stored in the table storage unit 14 is necessary for the plurality of circuit units (interrogators) 11 _N corresponding to the communication standards each bears, for example, the heat amount increase / decrease table shown in FIG. Prepare all of the above.

Thus, in the case where a plurality of circuit units (interrogators) 11 _N are provided, not only the suppression of heat generated when processing the question request transmitted from the higher-level management device 20 but also waiting for a decrease in heat. There is the advantage that the query request that is sent can be processed.

For example, if two or more circuit units (interrogators) 11 _N corresponding to the same communication standard are prepared, even if one circuit unit (interrogator) 11 _N is requested to stop the question request Since the question request may be transmitted to the other circuit unit (interrogator) _11N , the question request can be processed efficiently.

  Next, the heat amount suppression processing operation of the non-contact ID system shown as the second embodiment will be described using the flowchart shown in FIG.

  In step S <b> 31, the heat quantity estimation unit 15 acquires from the timer unit 12 the arrival time when the question request arrives at the heat quantity estimation unit 15.

  In step S <b> 32, the heat quantity estimation unit 15 acquires time information held in the time holding unit 13.

  In step S33, the heat quantity estimation unit 15 refers to the heat amount increase / decrease table stored in the table storage unit 14 using the arrival time acquired in step S31 and the time information acquired in step S32, and increases or decreases the heat amount. Ask.

  In step S <b> 34, the heat quantity estimation unit 15 integrates the estimated integrated heat quantity that has been estimated and held by the heat quantity estimation unit 15 last time and the current heat quantity increase / decrease, and obtains the current estimated integrated heat quantity.

  In step S35, the control unit 16 compares the current estimated integrated heat amount obtained by the heat amount estimating unit 15 with a predetermined threshold value, and determines whether or not the current estimated integrated heat amount exceeds the threshold value. If the current estimated accumulated heat amount exceeds the threshold value, the process proceeds to step S36, and if the current estimated accumulated heat amount does not exceed the threshold value, the process proceeds to step S38.

In step S <b> 36, the control unit 16 generates a stop request for requesting to stop transmission of the question request to the corresponding circuit unit (interrogator) 11 </ b> _N, and transmits the stop request to the upper management device 20.

  In addition, the control unit 16 obtains a time when the estimated integrated heat amount matches the threshold with reference to the heat amount increase / decrease table stored in the table storage unit 14, and transmits the time together with the stop request to the upper management device 20.

In step S37, the control unit 16, another circuit portion of the same communication standard are not issued a stop request (interrogator) in 11 _N, query request transmits a signal to the upper management apparatus 20 to be transmitted. When step S37 ends, the process ends.

In step S38, the question request transmitted from the upper management apparatus 20 is transmitted to the circuit unit (interrogator) _11N .

In step S39, the circuit portion (interrogator) 11 times and spent processing to the question request _N, holding the time when the processing is completed to the time holding unit 13.

  In step S40, the current estimated integrated heat amount is held as the previous estimated integrated heat amount.

In this way, the non-contact ID system shown as the second embodiment uses the heat amount increase / decrease table stored in the table storage unit 14 of the multi-card reader 40 to cause the circuit unit (question) ) By estimating the heat quantity of 11 _N, the question request automatically transmitted from the host management device 20 can be internally adjusted on the multi-card reader 40 side which is the receiver side, so that the calculation by the generated heat is performed. It is possible to reliably suppress the deterioration of the processing capacity and the occurrence of a fire that is the worst case.

  Moreover, since it is not necessary to separately provide sensors for obtaining the amount of heat and the like, there is an advantage that a significant increase in cost and an increase in the size of the apparatus can be avoided.

Further, by utilizing the fact that a plurality of circuit units (interrogators) 11 _N are provided, a question request is sent from the upper management device 20 to the circuit unit (interrogator) 11 _{N of the} same communication standard that is not requested to be stopped. By controlling to be transmitted, the waiting time in the first embodiment described above can be used for the processing time for the question request, so that efficient processing can be executed. Since the upper management apparatus 20 is also notified of the time during which transmission is possible from the stopped state, the higher order management apparatus 20 can further increase the efficiency and transmit the question request.

  The above-described embodiment is an example of the present invention. For this reason, the present invention is not limited to the above-described embodiment, and various modifications can be made depending on the design and the like as long as the technical idea according to the present invention is not deviated from this embodiment. Of course, it is possible to change.

It is a figure for demonstrating the structure of the non-contact ID system shown as 1st Embodiment. It is the figure which showed an example of the calorie | heat amount increase / decrease table stored in a card reader. It is a flowchart for demonstrating the processing operation of the non-contact ID system shown as 1st Embodiment. It is the figure which showed the structure of the card reader with which the non-contact ID system shown as 2nd Embodiment is provided. It is a flowchart for demonstrating the processing operation of the non-contact ID system shown as 2nd Embodiment. It is a figure for demonstrating the non-contact ID system shown as a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Card reader 11 Circuit part 12 Timer part 13 Time holding part 14 Table storage part 15 Calorific value estimation part 16 Control part 20 Host management apparatus 30 Card reader system 40 Multi card reader 50 Non-contact IC card

Claims (2)

A contactless IC (Integrated Circuit) card that stores a unique identifier;
A card having an interrogator that transmits a question signal for inquiring about a communication standard of the contactless IC card in response to a question request transmitted from the outside, and receives a response signal including the unique identifier from the contactless IC card With a reader,
A question request including a request for inquiring the communication standard of the non-contact IC card is transmitted to the interrogator, and the interrogator authenticates the non-contact IC card as a communication target from the received response signal. And a higher-level management device
The card reader has a first timing means for starting timing every time the question request transmitted from the host management device is received;
A time holding means for holding a processing time for processing the question request by the interrogator timed by the first time measuring means and an end time at which the processing of the question request is completed;
A table that associates the processing time for processing the question request of the interrogator with an increased amount of heat that increases according to the processing time, and an elapsed time after the processing for the question request in the interrogator is completed. A table storage means for storing a heat quantity increase / decrease table comprising a table relating a decrease heat quantity that decreases in accordance with the elapsed time;
Each time the question request is transmitted to the interrogator, the heat quantity increase / decrease table stored in the table storage means is referred to and the increased heat quantity corresponding to the processing time held in the time holding means is calculated. Acquired,
Referring to the heat quantity increase / decrease table stored in the table storage means, the end time held by the time holding means, and the time when the question request timed by the first time measuring means is received The amount of decrease heat corresponding to the elapsed time obtained from
A calorific value estimation means for estimating the current calorific value of the interrogator by accumulating the acquired calorific value and the calorific value reduced each time;
When the current calorific value of the interrogator estimated by the calorific value estimation means exceeds a predetermined threshold value, the current calorific value of the interrogator is referred to by referring to the calorific value increase / decrease table stored in the table storage unit. It has a stop request for stopping the transmission of the question request, and a stop request transmitting means for transmitting the decrease time to the upper management device, by determining a decrease time required for the amount of heat to be equal to or less than the predetermined threshold. ,
The upper management apparatus has a second timing unit that starts timing each time the stop request transmitted from the stop request transmission unit is received;
Control means for controlling to stop the transmission of the question request to the interrogator until the time counted by the second time measuring means passes by the decrease time. Contact ID system. The card reader comprises a plurality of interrogators,
The control means of the upper management apparatus controls to transmit the question request to other interrogators that have not transmitted the stop request while the transmission of the question request to the interrogator is stopped. The contactless ID system according to claim 1, wherein:

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