JP4284745B2 - IC card communication system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention includes a reader / writer applied to telephones, vending machines and other various devices, and a plurality of IC cards functioning as prepaid cards (for example, telephone cards) and other various cards. The present invention relates to an IC card communication system in which communication is performed with a card.
[0002]
[Prior art]
Conventionally, in some IC card communication systems, a reader / writer recognizes a plurality of IC cards individually using a plurality of time slots.
[0003]
[Problems to be solved by the invention]
By the way, in the IC card communication system, the reader / writer recognizes each IC card individually with a fixed number of time slots according to the number of IC cards used at the same time.
However, with the widespread use of a wide variety of IC cards in recent years, there has begun to be a situation where IC cards corresponding to applications different from the reader / writer application are mixed.
[0004]
For this reason, as described above, if the number of time slots of the reader / writer is fixed, an IC card that cannot be recognized is generated. As a result, the recognition probability of the IC card is lowered.
On the other hand, assuming that a mixture of IC cards with different applications as described above is assumed, if the number of reader / writer time slots is increased in advance, the recognition time of the IC card becomes longer uniformly. Arise.
[0005]
Therefore, in order to deal with the above, the present invention changes the number of time slots so as to adjust the number of collisions to an appropriate number of collisions according to the number of collisions of the previous communication. An object of the present invention is to provide an IC card communication system that efficiently performs individual recognition.
[0006]
[Means for Solving the Problems]
In solving the above problem, according to the invention described in claim 1, the IC card communication in which the reader / writer (RW) communicates with a plurality of IC cards (A to F) using a plurality of time slots. In the system, the reader / writer changes the number of time slots so as to adjust the number of collisions to an appropriate number of collisions in accordance with the number of collisions of return signals from each IC card in each time slot. have a 200 to 240), the number of time slots changing means, a confirmation means for confirming the number of collisions of the reply signal from the IC card in each time slot (200), number criteria check collision of this confirmation means The time slot number increasing means (210, 220) for increasing the number of time slots when larger, and the number of confirmation collisions of the confirmation means are smaller than the criterion. And a time slot number reducing means (230, 240) to reduce the number of time slots when.
[0007]
As described above, by changing the number of time slots according to the number of collisions with the IC card by the time slot number changing means, individual recognition of a plurality of IC cards can be performed efficiently .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an example in which the present invention is applied to a non-contact type IC card communication system.
The IC card communication system includes a single reader / writer RW. In this embodiment, the reader / writer RW communicates with six IC cards A, B, C, D, E, and F within the communicable area Area as illustrated in FIG.
[0010]
As shown in FIG. 2, the reader / writer RW includes a microcomputer 10, a memory 20, a modulation circuit 30, a transmission / reception antenna 40, and a demodulation circuit 50.
The microcomputer 10 executes a reader / writer program according to the flowchart shown in FIG. 4, and during this execution, the microcomputer 10 performs communication processing with the IC card via the memory 20, the modulation circuit 30, the transmission / reception antenna 40, and the demodulation circuit 50. And an arithmetic process for identifying the IC card. The reader / writer program is stored in advance in the ROM of the microcomputer 10.
[0011]
The memory 20 stores in advance the applications and identification codes of the IC cards A, B, C, D, E, and F.
The modulation circuit 30 outputs a modulation signal based on the output data of the microcomputer 10 to the transmission / reception antenna 40 as a transmission signal. The transmission / reception antenna 40 transmits a transmission signal from the modulation circuit 30 using an electromagnetic wave as a medium, and receives a return signal from the IC card using the electromagnetic wave as a medium, and outputs it to the demodulation circuit 50.
[0012]
The demodulation circuit 50 demodulates the received signal of the transmission / reception antenna 40 and outputs it to the microcomputer 10 as a demodulated signal.
Each of the IC cards A to F includes a transmission / reception antenna 60, a power supply circuit 70, a demodulation circuit 80, a memory 90, a microcomputer 100, and a modulation circuit 110, as shown in FIG.
[0013]
The configuration of the IC card A will be described in detail. The transmission / reception antenna 60 receives a transmission signal from the transmission / reception antenna 40 of the reader / writer RW as an electromagnetic wave and outputs it to the demodulation circuit 80.
The demodulation circuit 80 demodulates the received signal from the transmission / reception antenna 60 and outputs the demodulated signal to the microcomputer 100.
[0014]
The microcomputer 100 executes a card program according to a flowchart (not shown), and during this execution, the IC card is subjected to communication processing with the reader / writer RW via the demodulation circuit 80, the memory 90, the modulation circuit 110, and the transmission / reception antenna 60. An arithmetic process for the application identification request of A is performed.
In the memory 90, unique information of the IC card A, that is, an application of the IC card A, an identification code, and the like are stored in advance.
[0015]
The modulation circuit 110 modulates the output data of the microcomputer 100 and outputs it to the transmission / reception antenna 60 as a reply signal. The transmission / reception antenna 60 outputs a transmission signal from the transmission / reception antenna 40 of the reader / writer RW as a reception signal to the demodulation circuit 80, and returns a return signal from the modulation circuit 110 to the reader / writer RW using an electromagnetic wave as a medium.
[0016]
The power supply circuit 70 supplies power to each component of the IC card A.
In the present embodiment configured as described above, it is assumed that six IC cards A to D are in the communicable area Area of the reader / writer RW as shown in FIG. Here, it is assumed that the microcomputer 10 of the reader / writer RW starts the execution of the reader / writer program according to the flowchart of FIG.
[0017]
Next, in step 200 of FIG. 4, the microcomputer 10 designates a response to be returned in four time slots (see symbol a in FIG. 5), and the transmission signal indicating the response request is transmitted to the modulation circuit 30 and the transmission / reception antenna. Through 40, the electromagnetic wave is transmitted as a medium. Accordingly, among the reply signals from IC cards A to F, the reply signals from both IC cards A and C collide with each other in the corresponding time slots, and the reply from both IC cards B and E. It is assumed that the signals collide with each other in the corresponding time slot, and the return signals from both IC cards D and F collide with each other in the corresponding time slot (see the symbol x in FIG. 5). .
[0018]
Next, in step 200, the microcomputer 10 confirms the number of collisions in the time slot. At this stage, the microcomputer 10 cannot normally receive a reply signal from the IC card due to the above-described collisions.
Thereafter, in step 210, it is determined whether or not the number of collisions confirmed in step 200 is large. In this case, since the number of collisions is three, which is large, it is determined as YES in step 210.
[0019]
Accordingly, in step 220, processing for increasing the number of time slots is performed. For example, the number of time slots is increased to 8 (see symbol b in FIG. 5).
Then, the reader / writer RW designates a response to be returned in eight time slots in substantially the same manner as described above, and transmits a response request as a transmission signal.
Among the reply signals from the IC cards A to F, the reply signals from both the IC cards B and E collide with each other in the corresponding time slots, and the reply signals from both the IC cards C and F. Collide with each other in the corresponding time slot, and only the return signals of both IC cards A and D are normally received by the reader / writer RW (refer to the crosses x and o in FIG. 5).
[0020]
Then, in step 250, only the IC cards A and D are recognized.
Thereafter, in step 200, the number of collisions in the time slot of the previous reply signal is confirmed again. Since the number of collisions was as small as two, it is determined as YES in step 230 after determining NO in step 210.
[0021]
Accordingly, in step 240, the number of time slots is reduced. For example, the number of time slots is reduced to four (see symbol c in FIG. 5). Thereafter, the reader / writer RW designates a response to be returned in four time slots in substantially the same manner as described above, and transmits the response request as a transmission signal.
Among the reply signals from each IC card, the reply signals from both IC cards C and E collide with each other in the corresponding time slot, and only the reply signals from both IC cards B and F are the reader / writer RW. (Refer to the x mark and the ◯ mark in the code c in FIG. 5).
[0022]
Then, in step 250, only the IC cards B and F are recognized.
After that, since the number of collisions was neither large nor small based on the previous number of collisions in step 200, the number of time slots was not changed under the determination of NO in both steps 210 and 230. Processing is done. Here, similarly to the above, the reader / writer RW designates a response to be returned in four time slots (see symbol d in FIG. 5) in substantially the same manner as described above, and transmits the response request as a transmission signal. To do.
[0023]
Assume that each reply signal from each of the IC cards C and E is normally received by the reader / writer RW (see the mark “◯” in FIG. 5).
Accordingly, recognition processing is performed on each of the IC cards C and E.
Next, since there was no collision in the previous time based on the previous number of collisions in step 200, a determination of YES is made in step 230 under the determination of NO in step 210, and the number of time slots is determined in step 240. For example, a process of reducing to two is performed (see symbol e in FIG. 5).
[0024]
Accordingly, similarly to the above, the reader / writer RW designates a response to be returned in two time slots substantially as described above, and transmits a response request as a transmission signal.
On the other hand, if there is no reply signal from the IC card, the process proceeds to step 200 without performing the IC card confirmation process in step 250.
[0025]
As described above, according to the present embodiment, as described above, the number of time slots is changed to be adjusted to an appropriate number of collisions according to the number of collisions of the previous communication with the IC card. Individual recognition of a plurality of IC cards can be performed efficiently. In carrying out the present invention, the present invention may be applied to a contact IC card communication system instead of the non-contact IC card communication system described in the above embodiment.
[0026]
In implementing the present invention, the criteria for determining the collision situation in each of steps 210 and 230 may be a fixed value or a variable value. Here, when the determination criterion is a fixed value, the determination may be made with the absolute value of the number of collisions, or with the ratio of the number of collisions. Further, when the determination criterion is a variable value, the variable value is determined based on the number or ratio of time slots in which there is no IC card return signal, the number of collisions, the number of IC card recognition processes performed, or You may make it change according to these combinations.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of the present invention.
2 is a block diagram of the reader / writer of FIG. 1. FIG.
3 is a block diagram of each IC card in FIG. 1. FIG.
4 is a flowchart showing the operation of the microcomputer of the reader / writer of FIG. 1. FIG.
FIG. 5 is a timing chart in which the number of time slots of the reader / writer in FIG. 1 is changed.
[Explanation of symbols]
A to F: IC card, RW: reader / writer, 10: microcomputer.

Claims (1)

In an IC card communication system in which a reader / writer (RW) communicates with a plurality of IC cards (A to F) using a plurality of time slots,
The reader / writer changes the number of time slots so as to adjust the number of collisions to an appropriate number of collisions in accordance with the number of collisions of return signals from the IC cards in the time slots. 200 to 240) have a,
The time slot number changing means includes:
Confirmation means (200) for confirming the number of collisions of return signals from the IC card in each time slot;
Time slot number increasing means (210, 220) for increasing the number of time slots when the number of confirmation collisions of the confirmation means is greater than the criterion,
An IC card communication system comprising: time slot number reduction means (230, 240) for reducing the number of time slots when the number of confirmation collisions of the confirmation means is smaller than a criterion .

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