JPH0888701A - Telephone set - Google Patents

Abstract

PURPOSE: To attain the leak of signals and to prevent the entry of an illegal signal by measuring a time when an electric signal level received from an IC card changes from a ground level into a high level or vice versa and comparing the time with a reference time so as to discriminate whether or not the IC card is an illegal card. CONSTITUTION: An IC card 110 is inserted into a card insert port 104 of a public telephone set 100 to allow terminals of the IC card 110 and a terminal pin 103 of a contact 102 to be in contact with each other. A time measurement circuit 120 counts a time when an electric signal level received from an IC card changes from a ground level into a high level or vice versa by means of a 0(V) detection circuit 121 and a 5(V) detection circuit 122. A reference time taking the level change above is stored in a reference time memory 140. A comparison conputing element 130 compares the time obtained from the measurement circuit 120 with the stored reference time. A waveform appearing at an IC card wired illegally is unsharpened because of a wire capacitance of the illegal wire. Then an IC card is discriminated to be an illegal card when the time obtained from the measurement circuit 120 is larger than the reference time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to illegal use in an IC card system, and more particularly to a telephone (reader / writer) capable of preventing leakage of electric signals to the outside and input of illegal signals from the outside.

[0002]

2. Description of the Related Art IC cards have been attracting attention as new information recording media, especially as information recording media to replace magnetic cards, and are becoming increasingly popular. The IC card is a small card on which an IC module in which a memory, electrodes, and the like are integrated is mounted. Conventionally, in an IC card system in which the IC card is used by inserting it into a telephone
It is used as a C prepaid card. An IC card system that uses a telephone by using an IC card is one in which a user purchases an IC prepaid card as needed, sets the card in a public telephone and makes a call, and is a reader / writer (R / W) public. The telephone reads the frequency in the memory of the IC card by an electric signal and controls the continuous disconnection of the call according to the remaining frequency. When setting a card in a public telephone and making a call, the terminal surface of the IC card and the contact pin on the telephone side are connected.
At this time, the telephone set receives an electric signal (data) sent from the IC cart at an I / O interval at a certain fixed time.
This was done by sampling the state of O Line. Therefore, there is a problem in that even if an IC breadboard (evaluation board) such as shown in FIG. 4 in which illegal wiring is connected to the terminals of the IC card is used, it can be used. In order to deal with this, conventionally, in the case of this system, in order to prevent leakage of an electric signal by connecting the illegal wiring to the terminal of the card and reading the electric signal to the outside, a telephone ( The method of installing at the entrance of the reader / writer was adopted.

[0003]

However, according to this conventional method, the public telephone requires a movable part for opening and closing the lid, which is apt to cause a failure and is easily tampered with by breaking the lid. There was a problem that it was possible to insert various cards. Further, there is a problem that it cannot be prevented if the illegal wiring itself from the IC card is extremely thin. Under such circumstances, the present invention intends to provide a telephone (reader / writer) that has a simple structure, does not cause a failure, and can prevent leakage of an electric signal to the outside and input of an illegal electric signal from the outside. It is what

[0004]

The telephone of the present invention is an IC
A telephone in an IC card using system, wherein a card is inserted into a card insertion opening of a telephone and a terminal of the IC card and a contact pin of the telephone are brought into contact with each other to be used.
Communication means for performing electrical communication with the IC card;
Means for measuring the time until the electric signal (data) level input from the C card changes from the ground level to the high level or from the high level to the ground level, and a reference value for comparing with the measured time And a storage unit for storing the measured time. If the measured time is smaller than the stored reference value, it is determined as a normal IC card, and if it is larger than the reference value, it is determined as an illegal card. It is characterized by that.

[0005]

With the above arrangement, the telephone of the present invention can judge the presence / absence of illegal wiring with a simple structure without causing a failure, and leak an electric signal to the outside or input an illegal electric signal from the outside. Is supposed to be prevented. For more information,
If you use the IC breadboard shown in Fig. 4 and try to use the phone illegally with the IC card having illegal wiring connected, you can use a legitimate card according to the capacity of the wire (wiring) for illegal wiring. Since the waveform of the electric signal is more blunt than in the case of using it, the time from the ground level to the high level state or from the high level to the ground level state uses a regular IC card. By utilizing the fact that it is longer than the case, by comparing the measured time with a predetermined reference time obtained from the corresponding time when using a regular card, the presence or absence of illegal wiring can be determined. It can be judged.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a telephone according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a main part of a telephone of an embodiment, and FIG. 2 is a diagram for explaining the presence / absence of illegal wiring. In FIG. 1, 100 is a public telephone, 102 is a contact, 103 is a contact pin, 104 is a card insertion slot,
107A and 107B are card rotation support portions, and 110 is an IC
It is a card, 120 is a time measuring circuit, 121 is 0
(V) detection circuit, 122 is a 5 (V) detection circuit, 130 is a comparison calculator, and 140 is a reference time storage memory.

In the public telephone 100 of this embodiment, as shown in FIG. 1, after the IC card 110 is inserted through the card insertion slot 104 of the public telephone 100, the terminal portion of the IC card 110 and the contact 102 of the public telephone 100 are inserted. In a telephone of a telephone system using an IC card that is used in contact with the terminal pin 103, when the IC card 110 is set and used at a predetermined position, it is determined whether or not the IC card has illegal wiring. If it is determined that there is illegal wiring, stop sending and receiving electrical signals to and from the IC card (eject the card) to prevent leakage of electrical signals to the outside of the telephone and input of signals from outside. It is what In the telephone of this embodiment, when the IC card is set at a predetermined position and used, the terminal pin 103 of the contact 102 is used.
From the side, the 0 (V) detection circuit 121 detects 0 (V) of the electric signal from the IC card, and the 5 (V) detection circuit 122 detects 5 (V) of the electric signal from the IC card.
Detect. The time measuring circuit 120 counts the time required for a level higher than the ground level or the time required for a level higher than the ground level when detecting the level of the electric signal. Reference time storage memory 14
Reference numeral 0 is a memory for storing the reference time in order to input the reference time for determining the presence or absence of incorrect wiring and use it as comparison data. Comparison calculator 130
Is to compare the time required to change the level of the electric signal from the IC card obtained from the time measuring circuit 120 with the reference time from the reference time storage memory 140.
When the time obtained from the time measuring circuit 120 is longer than the reference time, it is determined that the IC card has defective wiring.

Transmission and reception of electric signals between the telephone and the IC card are performed by changing the electric signal level from the ground level to the high level.
Alternatively, it is performed as a digital signal by the operation of changing the signal level from the high level to the ground level, but when the IC card is used, the ground level is 0 (V) and the high level is 5 (V). ) Detection circuits 121, 5
(V) Each of the detection circuits 122 can know whether the electric signal from the IC card is at the ground level or the high level. Then, the time measuring circuit 120
For example, when detecting the time required when the electric signal level from the IC card changes from the ground level to the high level, 0 (V) is detected when the electric signal level becomes higher than the ground level. This is known by the circuit, and the time when the voltage reaches 5 (V) is known by the 5 (V) detection circuit, and the time measuring circuit 120 counts the time period. On the other hand, the reference time storage memory 140 is an IC in the case of using a regular IC card.
It was determined from the electric signal change time when the telephone receives the electric signal from the card, that is, the time when the electric signal level from the IC card changes from the ground level to the high level or from the high level to the ground level. , A value having a reference time that is an appropriate value for determination is input in advance and stored in a memory. The reference time and the change time of the electric signal obtained from the time measuring circuit 120 are compared and calculated by a calculator. Compare by.

Using the breadboard shown in FIG.
If you try to use the phone illegally with the card having illegal wiring, the waveform of the electric signal will be blunted compared to the case of using a legitimate card due to the capacity of the wire (wiring) for illegal wiring. Therefore, the level change time of the electric signal becomes longer than that in the case where a regular IC card is used. Therefore,
As shown in FIG. 2, when a regular IC card and an illegal card having defective wiring are used in the telephone of this embodiment, when the level of the electric signal changes from the high level to the ground level, the FIG. Time t ₂ required to change the signal level in the case of an illegal card having an illegal wiring shown in (b)
Is longer than the time t ₁ required to change the signal level in the case of the regular card shown in FIG. In FIG.
The time points A1 and A2 are detected by the 5 (V) detection circuit 122, the time points B1 and B2 are detected by the 0 (V) detection circuit 121, and the time between them is obtained by the time measurement circuit (timer). Therefore, t ₁ <reference time t _S <
When the reference time t _S satisfying the relationship of t ₂ is input and stored in the reference time storage memory 140, the reference time t _S is always displayed when an unauthorized card having an unauthorized wiring is used.
Since <t ₂ is satisfied, and t ₁ <reference time t _S is always obtained when a regular card is used, the time obtained from the time measuring circuit 120 and the reference time storage memory 140 are obtained by the comparison calculator 130. It is possible to judge whether or not the card using the telephone is an illegal IC card having illegal wiring by comparing the time with the measured time.

As an example of the operation of the telephone of this embodiment, an example in which the presence or absence of illegal wiring is judged when the electric signal changes from the high level to the ground level to determine whether or not the call can be made will be described. The operation will be described based on the flow chart. First, when the IC card is inserted from the state of waiting for the insertion of the IC card (FIG. 3A), the IC card is activated (FIG. 3B) and set in the data receiving state. (FIG. 3 (c)) Next, after detecting 5 (V) by the 5 (V) detection circuit (FIG. 3 (d)), the 5 (V) detection circuit further detects 5 (V).
The detection of (V) is repeated (FIG. 3E), and the timer is started when 5 (V) is no longer detected. (FIG. 3 (f)) Next, the 0 (V) detection circuit detects 0 (V) in a predetermined time cycle (FIG. 3 (g)), and when 0 (V) is detected, a timer is activated. Stop. (FIG. 3 (h)) After this, the measurement time obtained by stopping the timer is compared with the reference time previously input to the reference time memory 140. (FIG. 3 (i)) If the measurement time of the comparison is longer than the reference time,
Eject the IC card used in the telephone as an unauthorized card. (FIG. 3 (j)) When the measurement time as a result of the comparison is less than or equal to the reference time, the IC card being used is determined to be an authorized card and the call is made possible. (Fig. 3 (k))

As described above, the present invention can prevent leakage of an electric signal to the outside and input of an illegal electric signal from the outside. Further, the circuit (means) for judging the quality of the IC card can be provided relatively easily and does not cause mechanical failure unlike the conventional public telephone.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a telephone according to an embodiment.

FIG. 2 is a diagram for explaining the presence / absence determination of illegal wiring.

FIG. 3 is a flow chart of the operation of the telephone of this embodiment.

FIG. 4 is a diagram showing an example of an IC card having illegal wiring.

[Explanation of symbols]

 100 Telephone 102 Contact 103 Contact Pin 104 Card Insertion Port 107A, 107B Card Rotation Support 110 IC Card 120 Time Measurement Circuit 121 0 (V) Detection Circuit 122 5 (V) Detection Circuit 130 Comparator 140 Reference Time Storage Memory

Claims (1)

[Claims] 1. A telephone in an IC card using system in which an IC card is inserted into a card insertion port of a telephone and a terminal of the IC card and a contact pin of the telephone are brought into contact with each other, and the telephone electrically communicates with the IC card. And a means for measuring the time until the electric signal level input from the IC card changes from the ground level to the high level or from the high level to the ground level, and the measured time is compared. And a storage means for storing a reference value for storing the reference value, and when the measured time is smaller than the stored reference value, it is determined as a normal IC card, and when the measured time is larger than the reference value. A telephone that is characterized as a fraudulent card.