JPH04275694A - Ic card system - Google Patents

Abstract

PURPOSE:To solve magnetic mutual interference between coils for exchanging power and data without increasing the number of parts and to present the compact and high-performance IC card system concerning the IC card system in a conventional non contact system due to magnetic coupling. CONSTITUTION:For the non contact coupling circuits for exchanging power and data, one circuit is composed of a magnetic coupling circuit and the other is composed of a capacity coupling circuit. A coil 320 for power reception in an IC card 102 and an electrode plate 422 for data transmission/reception are arranged so that the direction of a magnetic flux change generated by a displaced current in the capacity coupling circuit can be orthogonal to the direction of a magnetic flux change at the gap part of the magnetic coupling circuit and corresponding to these coil and electrode plate, a power transmission coil 214 in a reader/writer 100 and an electrode plate 416 for data transmission/ reception are arranged.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to an IC card system, and more specifically, the present invention relates to a magnetic coupling system for transmitting and receiving data to and from an external device such as an IC card reader/writer (hereinafter referred to as a reader/writer) in a non-contact manner. This invention relates to an IC card system that applies capacitive coupling.

0002

[Prior art] I using non-contact coupling such as magnetic circuit
Various C card systems have been proposed. FIG. 2 shows a block diagram of essential parts of an example of a conventional non-contact type IC card system. 100 is a contactless reader/writer, and 102 is an IC card. 104 is a power supply circuit for the reader/writer, which supplies power to each part of the reader/writer. IC
As for the power that serves as the power source for the card 102, first, a sine wave power signal, for example, is generated from the oscillation circuit 106 of the reader/writer 100, and is transmitted via the power transmission coupling circuit 114. The power receiving coupling circuit 1 of the IC card 102 is coupled to the power transmitting coupling circuit 114 in a non-contact state.
20. This AC power received in the form of magnetic energy or electrostatic energy by the power reception coupling circuit 120 passes through a rectification/smoothing circuit 126 that serves as a power supply circuit for the IC card 102, thereby converting it into power at a predetermined DC voltage. can get. And this rectification/smoothing circuit 12
The electric power passing through 6 is passed through a constant voltage circuit 128, for example, an IC.
Voltage fluctuations due to changes in current consumption of the card's internal circuits,
Voltage fluctuations due to differences in the distance between the IC card and the reader/writer when the IC card is attached to the reader/writer are absorbed, and after the power supply voltage is stabilized, it is supplied to the circuits of each part of the IC card.

Regarding data transmission and reception, first, data transmitted from the reader/writer 100 to the IC card 102 is sent from a data processing circuit 112 having a microprocessor and memory, and is modulated by a data transmission circuit 108 in a predetermined manner. and is transmitted to the IC card 102 via the switch circuit 118 and the data transmission/reception coupling circuit 116. As in the case of power transmission, the I
The data is received by the data transmission/reception coupling circuit 122 of the C card 102. The received data is demodulated by a data receiving circuit 130 via a switch circuit 124, and sent to a data processing circuit 134 having a microprocessor and memory for processing.

On the other hand, data transmitted from the IC card 102 to the reader/writer 100 is sent from the data processing circuit 134 of the IC card 102 and sent to the data transmission circuit 13.
2 in a predetermined manner, and the switch circuit 124
and is transmitted to the reader/writer 100 via the data transmission/reception coupling circuit 122. and data transmission/reception coupling circuit 12
2 and the reader/writer 100 in a non-contact state.
The data is received by the data transmitting/receiving coupling circuit 116 on the side. The received data is demodulated by the data receiving circuit 110 via the switch circuit 118, and sent to the data processing circuit 112 for processing.

FIG. 3 shows a conventional non-contact type I using magnetic coupling.
FIG. 2 is a perspective view showing the structure and arrangement of each magnetic coil and each core of the reader/writer of the C card system and each magnetic coil of the IC card. However, parts with the same functions as those in FIG. 2 are given the same numbers. The power transmitting coil 214 and the data transmitting/receiving coil 216 on the reader/writer side are wound around U-shaped cores 300 and 302, respectively. The terminals 220 and 222 of these coils are not shown in FIG. 3, but the oscillation circuit 106 of the reader/writer 100 shown in FIG.
and are connected to a data transmitting circuit 108 and a data receiving circuit 110 via a switch circuit 118, respectively.

[0006] The IC card 102 includes a power receiving coil 32.
0, a data transmitting/receiving coil 322 is provided, the power receiving coil 320 is connected to the rectifying/smoothing circuit 126 of the IC card 102, and the data transmitting/receiving coil 322 is connected to the data receiving circuit 130 and the data transmitting circuit via the switch circuit 124. It is connected to circuit 132. Reader/writer 1
Each core of 00 is configured such that when an IC card is inserted or mounted, each coil provided on the IC card
It is arranged to be located within the gap of each coil of the lighter.

[0007]

[Problem to be Solved by the Invention] In the case of FIG. 3, the magnetic flux changes from the front side to the back side of the IC card or from the back side to the front side at the gap portions of the magnetic coupling circuits for power transmission/reception and data transmission/reception. . That is, the direction of change in magnetic flux of this non-contact magnetic coil changes in the Z-axis direction when shown on the coordinate axes. Therefore, when a data transmitting/receiving coil that transmits data by magnetic coupling is placed adjacent to a power transmitting/receiving coil, the directions of magnetic flux changes are parallel, so leakage magnetic flux from the closed magnetic circuits of each magnetic coupling circuit interlinks. It easily jumps into other magnetic coupling coils and interferes with them. For this reason, there is a very high possibility that pulse signals such as clock signals, various control signals, and data signals on the reader/writer side will enter the power transmission/reception system of the IC card as pulse noise. Therefore, if pulse-like noise gets mixed into the magnetic coupling circuit for supplying power, this noise cannot be removed even by the rectifying/smoothing circuit, and the pulse-like noise appears in the DC voltage output from the power supply. Therefore, it is not possible to achieve sufficient voltage stabilization, and this pulse-like noise causes malfunctions of various circuits to which power is supplied. In particular, in IC cards, data processing circuits,
That is, since a microprocessor and memory are built-in, the probability of malfunctions caused by pulsed noise is extremely high, and the effects thereof are extremely serious.

[0008] In order to solve such problems, in a contactless IC card that receives power from a reader/writer in the form of magnetic energy of a specific frequency, only the frequency of the magnetic energy supplied with power, or By inserting a bandpass filter that passes only the nearby frequencies into the power supply circuit of the power receiving system, the reader
It has been proposed to remove pulsed noise from the writer and signal system (Japanese Patent Laid-Open No. 1-181179). However, the frequency components of the pulsed noise of these various control signals are extremely densely distributed over a wide band from 0 Hz to several tens of MHz. Therefore, when inserting a bandpass filter that passes only the frequency of the magnetic energy supplied by the power supply or only the frequencies in the vicinity thereof into the power supply circuit of the power receiving system of the IC card, or when the frequency of the magnetic energy transmitted from the IC card is inserted. When inserting a band-pass filter into the receiving coil of a reader/writer that passes only frequencies at or near frequencies, it is necessary to insert a multi-stage filter with extremely steep characteristics. For this reason,
The number of capacitors and coils constituting the filter increases, making it difficult to miniaturize and lower the cost of the IC card system. In particular, it will be difficult to make IC cards smaller and thinner. The present invention was made to solve these problems, and it solves the drawback that pulse noise is superimposed on the DC power supply of the IC card, causing malfunctions of various circuits of the IC card, and provides stable power and The purpose of the present invention is to provide a low-cost, small-sized, non-contact type IC card system capable of transmitting and receiving data.

[0009]

[Means for Solving the Problems] In order to achieve the above object, the present invention consists of an IC card and a reader/writer,
An IC card having a contactless power coupling circuit for transmitting power from the reader/writer to the IC card, and a contactless coupling circuit for data for transmitting and receiving data between the IC card and the reader/writer. In the system, a coil of a magnetic coupling circuit, which is one of the coupling circuit for power and the coupling circuit for data, is attached to the IC card so that two ends of a magnetic path formed by the coil face the opposing surface of the IC card. The electrode plate of the capacitive coupling circuit, which is the other one of the coupling circuits, is provided in a plane parallel to the surfaces facing the two ends of the magnetic path, and the reader/writer also has an electrode plate between the coil and the electrode plate. It is characterized by correspondingly provided with a coil and an electrode plate constituting a coupling circuit.

0010

[Operation] In this way, the reader/writer is equipped with a coupling circuit that supplies power to the IC card, and a coupling circuit that transmits and receives data between the reader/writer and the IC card. One of the coupling circuits is a magnetic coupling circuit that transmits and receives data in the form of electrostatic energy, and the other coupling circuit is a capacitive coupling circuit that transmits and receives electrostatic energy. By changing the form of energy, interference between coupling paths is prevented. Furthermore, the direction of magnetic flux change in the gap portion of the magnetic coupling circuit is made not to be the same as the direction of magnetic flux change due to the displacement current inside the capacitive coupling circuit. That is, by arranging the coupling circuits so that the directions of magnetic flux change are orthogonal to each other, it is possible to prevent leakage flux from interlinking. For this reason, it is possible to prevent pulse-like noise from entering and mixing with each signal system inside the reader/writer, which has the drawback that pulse-like noise is superimposed on the DC power supply of the IC card, causing malfunction of various circuits of the IC card. can be solved.

[0011]

Embodiments will be described in detail below based on the drawings. FIG. 1 is a perspective view showing the structure and arrangement of the magnetic coil, core, and electrode plate of the reader/writer of the non-contact type IC card system of the present invention, and the magnetic coil and electrode plate of the IC card. This is an IC card system that uses a magnetic coupling circuit to transmit and receive power and a capacitive coupling circuit to transmit and receive data. However, parts with the same functions as those in FIGS. 2 and 3 are given the same numbers. A power receiving coil 320 and a data transmitting/receiving electrode plate 422 are provided on the IC card 102 side. It is desirable to embed a magnetic material in the center of the power receiving coil 320. By embedding the magnetic material, it becomes easier to form a closed magnetic path of the magnetic coupling circuit when attached to the reader/writer 100, and leakage magnetic flux from the gap portion of the core is reduced. In this case, power receiving coil 3
20, the magnetic flux changes from the front side to the back side or from the back side to the front side of the IC card at the gap portion of the magnetic coupling circuit, as is clear from the figure. In other words, the direction of magnetic flux change in the gap portion of this magnetic coupling circuit changes in the Z-axis direction when shown on the coordinate axes. The data transmitting/receiving electrode plate 422 is connected to the reader/writer 1 as shown in the figure.
They are arranged so as to form a pair with the data transmitting/receiving electrode plate 416 of 00 to form a parallel plate capacitor. A displacement current flows in this capacitor, and this displacement current creates a magnetic field just like a conduction current. The direction of the magnetic field at this time changes within the XY plane because the displacement current flows in the Z-axis direction. Further, one electrode plate of the data transmitting/receiving electrode plate 422 is grounded to form a retrace loop. In this case, as will be described in detail later, it is desirable to arrange it close to the corner in order to reduce the influence of deflection force due to external force. These coils and electrode plates are fixed in grooves pre-cut in the IC card so as not to be displaced. Its outer surface is covered with a plastic covering. Power receiving coil 3
20 is connected to a rectifying/smoothing circuit 126 of the IC card, and a data transmitting/receiving electrode plate 422 is connected to a data receiving circuit 130 and a data transmitting circuit 132 via a switch circuit 124, respectively.

Power transmitting coil 2 of reader/writer 100
14. The data transmitting/receiving electrode plate 416 is connected to the IC card 102
When the IC card 102 is inserted or mounted, the IC card 102 is placed at a predetermined position so as to be combined with the power receiving coil 320 and data transmitting/receiving electrode plate 422 provided in the IC card 102. The power transmitting coil 214 is wound around a U-shaped core 300. A dielectric piece 4 is placed on the data transmitting/receiving electrode plate 416.
It is preferable to arrange 30. By arranging the dielectric piece 430 so that it is sandwiched between the parallel plate capacitors formed by the data transmission/reception electrode plates 416 and 422 when the IC card is installed, a capacitive coupling circuit is created when the IC card is installed in the reader/writer. impedance decreases. Further, one electrode plate of the data transmitting/receiving electrode plate 416 is grounded to form a retrace loop. Although the terminals 220 and 222 of the power transmitting coil 214 and the data transmitting/receiving electrode plate 416 are not shown in FIG. 1, they are connected to the reader/writer 100 shown in FIG.
The oscillation circuit 106, data transmission circuit 108, and data reception circuit 110 are connected to each other via a switch circuit 118.

The magnetic material embedded in the center of the power receiving coil 320 and the material of the U-shaped core 300 are made of, for example, ferrite. Ferrite has excellent frequency characteristics, so the frequency of transmission and reception is, for example, several hundred K.
It has the advantage of being resistant to magnetic saturation even at frequencies from Hz to several tens of MHz, and having little core loss. If the transmitting and receiving frequency is lower, for example up to about 100KHz,
Permalloy, which is an alloy of nickel and iron, Sendust, which is made of iron, silicon, and aluminum, and boron-based amorphous alloys, which are made by rapidly cooling molten alloys such as iron, cobalt, and nickel from a high temperature state, have low magnetic permeability. It is better than ferrite. In addition, when using ferrite, it is preferable to use porous ferrite impregnated with phenol resin to increase the bending strength, and there is almost no chance of damage due to impact when the card body is dropped.

Data transmission/reception electrode plate 4 of IC card 102
22 and the data transmitting/receiving electrode plate 41 of the reader/writer 100
For example, mica, polypropylene, polyester, or the like is used as the material of the dielectric piece 430 disposed on the dielectric member 6 . Mica is extremely stable electrically and against heat, and has high stability over time. Polypropylene is the lightest plastic material with a specific gravity of 0.9, and is among the best among plastic materials due to its stable capacitance, frequency characteristics, and low internal heat generation. Polyester is inexpensive if used at low frequencies.

[0015] Since the card body is made of plastic or the like, it is likely that it will bend due to external force applied to it during use or carrying.In this case, the maximum stress is generally at the center of the card body. It is desirable to avoid placing each coupling circuit in the center, similar to an integrated circuit. That is, by incorporating it in an eccentric position in the card body, the influence of deflection force due to external force can be reduced. In particular, in the case of a rectangular card, the influence of deflection force is further reduced at corner portions on the diagonal line and near the outside. The corner portion also has the advantage that the magnetic coil with the reader/writer is structurally advantageous. Furthermore, by inserting a reinforcing material around the coil made of a non-magnetic material, such as plastic similar to that of the card body, the effect of bending stress on the card body can be reduced.

In the embodiment, an example was explained in which a magnetic coupling circuit was used for power transmission and reception, and a capacitive coupling circuit was used for data transmission and reception. It goes without saying that a magnetic coupling circuit can be used for transmission and reception, so a description thereof will be omitted.

[0017]

[Effects of the Invention] As described above, according to the present invention, the IC
In an IC card system configured to supply power and send and receive data by connecting a reader/writer to the card in a non-contact manner, one coupling circuit is a magnetic coupling circuit that transmits and receives data in the form of magnetic energy, and the other One of the coupling circuits is a capacitive coupling circuit that uses electrostatic energy, and the IC
When a card and a reader/writer are connected in a non-contact manner, interference between the coupling paths is prevented by changing the form of energy for power transmission/reception and data transmission/reception. Further, by arranging the magnetic coupling circuit so that the direction of magnetic flux change in the gap portion and the direction of magnetic flux change due to the displacement current inside the capacitive coupling circuit are perpendicular to each other, it is possible to prevent leakage magnetic flux from interlinking. Therefore, it is possible to prevent pulse noise from entering and mixing from each signal system inside the reader/writer.
Pulse noise is superimposed on the DC power supply of the IC card, and the IC
It is possible to solve the drawback of causing malfunction of various circuits of the card. Therefore, since no filter is required to remove these pulse-like noises, a compact and low-cost IC card system can be realized.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of essential parts of a non-contact type IC card system showing one embodiment of the present invention.

FIG. 2 is a block diagram of main parts of a conventional non-contact type IC card system.

FIG. 3 is a perspective view of the main parts of a conventional non-contact type IC card system.

[Explanation of symbols]

100 Reader/Writer 102 IC card 114 Power transmission coupling circuit 120 Power reception coupling circuit 116 Data transmission/reception coupling circuit 122 Data transmission/reception coupling circuit 118 Switch circuit 124 Switch circuit 300 core 302 Core 108 Data transmission circuit 132 Data transmission circuit 110 Data receiving circuit 130 Data receiving circuit 214 Power transmitting coil 216 Data transmission/reception coil 320 Power receiving coil 322 Data transmission/reception coil 416 Data transmitting and receiving electrode plate 422 Data transmitting and receiving electrode plate 430 Dielectric piece

Claims (1)

[Claims] 1. A non-contact power coupling circuit comprising an IC card and a reader/writer, and transmitting/receiving data between the IC card and the reader/writer. In an IC card system having a contactless coupling circuit for data,
A coil of a magnetic coupling circuit, which is one of the power coupling circuit and data coupling circuit, is attached to the IC card so that the two ends of the magnetic path formed by the coil face the opposing surface of the IC card. An electrode plate of a capacitive coupling circuit, which is the other one of the coupling circuits, is provided in a plane parallel to the planes facing the two ends of the magnetic path, and the reader/writer is also provided in a manner corresponding to the coil and the electrode plate. An IC card system characterized by being provided with a coil and an electrode plate that constitute a coupling circuit.