JPH05143798A - Non-contact type information medium and its reader/ writer - Google Patents

Abstract

PURPOSE:To detect an abnormal state of a transmission/reception circuit provided on the non-contact type information medium. CONSTITUTION:A high-frequency signal from a transmission circuit 22 of a reader/writer 2 is supplied through a driver 2, coils 20 and 40. Based on this, a power supply circuit 42 generates the power supply voltage. When an abnormality detection means 47 detects the abnormality of a transmission/reception circuit 4, the load of a driver 21 is changed by the operation of the transmission circuit 44' and the amplitude of the high frequency current flowing through the coil 20 is changed. A current detection means 26 detects the high frequency current and a reception circuit 24 detects the amplitude change of the high frequency current flowing through the coil 20. Thus, the transmission/reception circuit 4 is judged to be abnormal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a card-type information medium such as an IC card or a pendant-type or coin-type information medium which is magnetically connected in a contactless manner by coil means to mutually exchange data. The present invention relates to a contact type information medium and its reader / writer.

[0002]

2. Description of the Related Art A conventional IC card has an electric contact, and by bringing this electric contact into contact with an electric contact of a recording medium writing / reading device (hereinafter referred to as a reader / writer),
Although it was a contact type IC card that was connected to a reader / writer, a non-contact type IC card was proposed in which a coil was used instead of an electrical contact, and the reader / writer and the coil were magnetically connected in a non-contact manner. ing. An example of a conventional non-contact type IC card and its reader / writer will be described below with reference to FIG. However, 1 is a host, 2 is a reader / writer, 20 is a coil, 21 is a driver, 22 is a transmission circuit, 23 is an oscillation circuit, 24 is a reception circuit, and 25 is a CPU.
(Central processing unit), 26 is current detection means, 3 is a non-contact type IC card (hereinafter, simply referred to as an IC card), 4 is a transmission / reception circuit, 40 is a coil, 41 is a rectifier circuit, 42 is a power supply circuit, and 43 is reception. Reference numeral 44 is a transmission circuit, 45 is a timing circuit, 46 is a reset circuit, and 5 is a CPU.

In the figure, when data is sent from the reader / writer 2 to the IC card 3, the data from the host 1 or the like is processed by the CPU 25 in the reader / writer 2 and sent to the transmission circuit 22. In the transmission circuit 22, a high frequency signal having a constant amplitude is supplied as a carrier from the oscillation circuit 23, and the carrier is modulated with data to output a modulated high frequency signal. In this case, the modulation method may be any of amplitude modulation, frequency modulation, phase modulation and the like. The modulated high frequency signal output from the transmission circuit 22 is supplied to the coil 20 via the driver 21.

At this time, the IC card 3 is mounted on the reader / writer 2, and the coil 20 of the reader / writer 2 and the coil 40 of the IC card 3 are electromagnetically coupled.

Therefore, in the IC card 3, the modulated high frequency signal is supplied to the transmitting / receiving circuit 4 via the coils 20 and 40. The modulated high frequency signal is rectified by the rectifier circuit 41 and supplied to the power supply circuit 42 to generate a predetermined power supply voltage required for each part of the IC card 3. In addition, the rectifier circuit 41
The output signal of is also supplied to the receiving circuit 43, the data is demodulated and supplied to the CPU 5. The CPU 5 operates based on the outputs of the timing circuit 45 and the reset circuit 46, processes the supplied data, and writes a predetermined one in a memory (not shown).

When data is sent from the IC card 3 to the reader / writer 2, in the reader / writer 2, the transmitter circuit 22 outputs a high-frequency signal having a constant amplitude without modulation,
IC card 3 via driver 21 and coils 20 and 40
Sent to. In the IC card 3, the high frequency signal is rectified by the rectifier circuit 41 and the power supply circuit 42 is operated as in the above.
And the predetermined power supply voltage is generated.

On the other hand, in the IC card 3, the data read from the memory (not shown) is processed by the CPU 5 and supplied to the transmission circuit 44. The transmission circuit 44 is composed of, for example, a load resistance and a switch, and has data "1" and "0".
This switch turns on and off depending on the bit.

In the reader / writer 2, when the switch of the transmission circuit 44 is turned on and off as described above, the coil 2
The load seen from both terminals of 0 on the coil 20 side fluctuates, so that the amplitude of the high frequency current flowing through the coil 20 fluctuates. That is, this high frequency current is amplitude-modulated by the data supplied from the CPU 5 of the IC card 3 to the transmission circuit 44. This high frequency current is detected by the current detecting means 24,
The data is obtained by being demodulated by the receiving circuit 24. This data is processed by the CPU 25 and sent to the host 1 or the like.

[0009]

By the way, in the conventional contact type IC card, when an abnormal state occurs,
The CPU detects this and sends the detection result to the reader / writer. As a result, the host can determine the abnormal state of the IC card and its type.

On the other hand, the IC card 3 as shown in FIG. 6 is different from the contact type IC card in that the coil 40 and the transmission / reception circuit 4 are used.
The function of is essentially the same as the CPU built in the contact type IC card. Therefore, even if the power supply voltage obtained by the abnormal operation of the power supply circuit 42 becomes abnormal, or the transmitting / receiving circuit 4 becomes abnormal due to abnormal heat generation, the CPU 5 cannot detect this. Therefore, even if the transmission / reception circuit 4 is in an abnormal state, the host 1 cannot know this and the reader / writer 2 or I
The C card 3 may be operated, and in the worst case, the IC card 3 may be destroyed. Further, the transmission / reception circuit 4 becomes in an abnormal state, which hinders data transmission / reception. However, even if the CPU 5 can detect this, the host 1 cannot know the cause.

The object of the present invention is to eliminate such problems and
An object of the present invention is to provide a non-contact type information medium capable of detecting an abnormal state of a transmission / reception circuit in an information medium such as a C card and a reader / writer thereof.

[0012]

In order to achieve the above object, the non-contact type information medium according to the present invention is provided with abnormality detecting means for detecting an abnormal state of a transmission / reception circuit.

Further, the reader / writer according to the present invention is provided with a means for detecting the amplitude change because the output of the coil current detecting means changes in amplitude according to the detection output of the transmitting / receiving means.

[0014]

In the non-contact type information medium according to the present invention, the abnormality detecting means detects the abnormal state of the transmission / reception circuit and sends the detection result to the reader / writer in the same manner as normal data.

Further, in the reader / writer according to the present invention, the amplitude of the high-frequency current flowing in the coil changes according to the detection output of the above-mentioned abnormality detecting means. Since the amplitude of the output of the current detecting means also changes, the abnormal state of the transmission / reception circuit in the non-contact type information medium can be determined by detecting the amplitude change.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a non-contact type information medium and a reader / writer according to the present invention.
PU, 44 'is a transmitting circuit, 47 is an abnormality detecting means,
The parts corresponding to those in FIG. 6 are designated by the same reference numerals, and redundant description will be omitted. Here, the non-contact type information medium is a non-contact type IC card.

In the figure, the IC card 3 is provided with an abnormality detecting means 47 for detecting an abnormal state of the transmission / reception circuit 4 such as an abnormal operation of the power supply circuit 42 or abnormal heat generation. Also,
The transmission circuit 44 'has the same function as the transmission circuit 44 in the conventional IC card 3 shown in FIG. 6, but further has a function of transmitting the detection output of the abnormality detecting means 47 to the reader / writer 2 in the same manner. have.

Further, in the reader / writer 2 shown in FIG.
When sending data to the IC card 3, the CPU 25 does not capture the output of the receiving circuit 24, but the CPU 25 'of FIG.
Also captures the output of the receiving circuit 24 at this time.

Next, the operation of this embodiment will be described.

When data is sent from the reader / writer 2 to the IC card 3, it is assumed here that the transmission circuit 22 frequency-modulates or phase-modulates the carrier from the oscillation circuit 23 with the data from the CPU 25 '. Therefore, a modulated high frequency wave voltage having a constant amplitude is applied from the driver 21 to the coil 20 as shown in FIG.
And can be sent to the IC card 3 via the coil 40. However, FIG. 2 shows the case where the carrier is phase-modulated, and FIG.
P1 and P2 are positions where the phase of the carrier at the boundary between the "1" and "0" bits of the data is inverted. In the IC card 3, similarly to the IC card 3 shown in FIG. 6, the power supply circuit 42 generates a power supply voltage from the modulated high frequency voltage, and the reception circuit 43 demodulates the data.

In such a state, the coil 20 is usually used.
The high-frequency current flowing through has a constant amplitude, as shown in FIG. However, when the abnormality detection means 47 detects an abnormality in the transmission / reception circuit 4, the transmission circuit 44 'performs the same operation as when transmitting data by the detection output of the abnormality detection means 47. As a result, in the reader / writer 2, the high frequency current flowing through the coil 20 increases in amplitude during the period in which the abnormality detecting means 47 detects the abnormal state of the transmission / reception circuit 4, as shown in FIG. The output signal of the current detecting means 26 is amplitude-demodulated by the receiving circuit 24, and as shown in FIG. 2D, a signal representing a period t1 to t2 in which the amplitude of the high frequency current flowing through the coil 20 is increased is generated. This signal is taken in by the CPU 25 ', and it is determined that the transmission / reception circuit 4 in the IC card 3 is abnormal.

The operation when data is sent from the IC card 3 to the reader / writer 2 is the same as in the prior art shown in FIG.

Thus, in this embodiment, when data is sent from the reader / writer 2 to the IC card 3 when writing data to the IC card 3, the transmission / reception circuit 4 of the IC card 3 is used.
Can detect abnormalities.

FIG. 3 is a diagram for more specifically explaining the operation of the embodiment shown in FIG. 1. Reference numeral 48 is a switch, and the parts corresponding to FIG.

In the figure, in principle, the transmission circuit 44 'changes the current of the coil 40 according to the data and the detection output of the abnormality detecting means 47 (FIG. 1), and the coil 20 side is seen from both terminals of the coil 20. It changes the load.
As one of the methods, a resistor R is provided in parallel with a load resistor RL that represents a steady load of a circuit in the IC card 3 in the transmission circuit 44 ', and a switch is connected in series with the resistor R. The data 48 and the detection output of the abnormality detection means 47 may be used for on / off control. In this case, the amplitude variation range of the high frequency current detected by the current detecting means 26 is the same regardless of which of the switches 48 is turned on and off. However, ON / OFF control of the switch 48 by data is performed when data is sent from the IC card 3 to the reader / writer 2, and ON / OFF control of the switch 48 by the abnormality detection means 47 is performed by the IC card 3 from the reader / writer 2. Is carried out at the same time, it does not matter even if the amplitude fluctuation range of the high frequency current flowing through the coil 20 is the same.

The data and the abnormality detection signal can be distinguished from each other by controlling the on / off control of different switches depending on the data and the detection output of the abnormality detection means 47. FIG. 4 is a circuit diagram showing a specific example of the transmission circuit 44 'for this purpose.

In the figure, a resistor R1 and a transistor Q
1 and the series circuit of the resistor R2 and the transistor Q2 are connected to the rectifier circuit 41 of FIG. The transistor Q1 is on / off controlled by the data from the CPU 5 (FIG. 1), and the transistor Q2 is set by the detection output of the abnormality detecting means 47 (FIG. 1) flip-flop circuit (hereinafter referred to as FF circuit) 49. ON / OFF control is performed by the Q output of. The FF circuit 49 is reset by a reset signal generated at the time of initial operation at the time of power input or when the abnormality detecting means 47 stops detecting an abnormality.

The transistor Q1 is held in the off state when no data is supplied, and the transistor Q2 is turned on while the Q output of the FF circuit 49 is "1". Here, the current i1 flowing through the resistor R1 when the transistor Q1 is turned on and the current i2 flowing through the resistor R2 when the transistor Q2 is turned on are controlled by the resistors R1 and R2, respectively. The amplitude of the high frequency current flowing through the coil 20 can be controlled.

Further, the FF circuit 49 has an abnormality detecting means 47.
It is also possible to reset by the reset signal only when does not detect an abnormality. In this case,
Even when data is sent from the IC card 3 to the reader / writer 2, if the abnormality detecting means 47 detects an abnormality, the transistor Q2 is turned on. Therefore, the transistors Q1 and Q2 may be turned on at the same time, and at this time, the transmission circuit 4
The output current of 4'is (i1 + i2). So R1
By setting> R2, the amplitude of the high-frequency current flowing through the coil 20 in FIG. 1 is always greater when the abnormality detecting means 47 detects an abnormality than when only the above data is used. Therefore, by making it possible for the receiving circuit 24 of FIG. 1 to detect the difference in amplitude of the high-frequency current, it is possible to detect an abnormality in the transmitting / receiving circuit 4 even when data is sent from the IC card 3 to the reader / writer 2. it can. Also, when the modulated high frequency signal by amplitude modulation is sent from the reader / writer 3 to the IC card 2, it is possible to detect the abnormality of the transmission / reception circuit 4 in the same manner.

In FIG. 5, the transmission circuit 44 'is composed of a current source 50, and the current source 50 can be controlled by the data from the CPU 5 (FIG. 1) and the detection output of the abnormality detecting means 47.

Also in this specific example, when data is sent from the reader / writer 2 to the IC card 3, the abnormality detecting means 4
When the data is sent in the opposite direction with the detection output of No. 7, the current sources 50 may be controlled by the respective data, but in the latter case, the detection output of the abnormality detecting means 47 also controls the current source 50. It may be controlled. In this case, at least the current source I becomes larger when the current source 50 is controlled by the abnormality detection means 47 than when the current source 50 is controlled only by the data, so that the state shown in FIG. The same effect as the specific example can be obtained.

In the above embodiment, an IC card, which is a card-shaped information medium, is illustrated as the non-contact type information medium, but the information medium is not limited to the card-shaped information medium, and an information medium such as a pendant type or a coin type that is easy to carry. Generally applicable.

[0033]

As described above, according to the present invention,
The abnormal state of the transmission / reception circuit in the non-contact type information medium can be detected and discriminated, and any abnormal state of the non-contact type information medium can be discriminated, so that the reliability of the non-contact type information medium is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a non-contact type information medium and a reader / writer thereof according to the present invention.

FIG. 2 is a waveform diagram showing signals of respective parts in FIG.

FIG. 3 is an explanatory diagram of an operation of the embodiment shown in FIG.

4 is a circuit diagram showing a specific example of a transmission / reception circuit in the non-contact type IC card in FIG.

5 is a circuit diagram showing another specific example of a transmission / reception circuit in the non-contact type IC card in FIG.

FIG. 6 is a block diagram showing an example of a conventional non-contact type information medium and its reader / writer.

[Explanation of symbols]

 2 reader / writer 3 non-contact type IC card 4 transmitter / receiver circuit 20 coil 21 driver 22 transmitter circuit 24 receiver circuit 40 coil 41 rectifier circuit 42 power supply circuit 43 receiver circuit 44 'transmitter circuit 47 abnormality detection means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shunen Ieki 26-55 Toranomon, Minato-ku, Tokyo NTay Data Communications Co., Ltd.

Claims (2)

[Claims] 1. A non-contact type information medium comprising a transmission / reception circuit magnetically coupled to a reader / writer by a coil means and transmitting / receiving data via the coil means and generating a power supply voltage by a high frequency signal from the reader / writer. A non-contact type information medium, characterized in that an abnormality detecting means for detecting an abnormal state of the transmission / reception circuit is provided, and a detection output of the abnormality detecting means is transmitted to the reader / writer via the coil means. 2. The reader / writer magnetically coupled to the non-contact type information medium according to claim 1, by the coil means, wherein a high frequency signal is supplied to the coil means by a drive circuit. Current detecting means for detecting a high frequency current of the coil means, and means for detecting and determining an amplitude vibration of a detection output of the current detecting means due to a detection output of the abnormality detecting means in the non-contact type information medium, A reader / writer characterized by being configured to be able to determine an abnormal state of the transmission / reception circuit of the non-contact type information medium.