JP2002246830A - Antenna system and non-contact ic card reader/writer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize stable long distance communication at the time of performing long distance communication by enlarging the outer dimension of an antenna, and lengthening a communication validating distance between a card reader and an IC card. SOLUTION: An antenna substrate 14A of a card reader 1 is provided with a first antenna coil L1A formed like a loop with a central point O as a center for generating a magnetic field based on power supply and a second antenna coil L1B formed like a loop with the central point O as a center whose one edge is connected to one edge of the first antenna coil L1A for generating a magnetic field in the same direction as that of the magnetic field generating direction of the first antenna coil L1A based on power supply while the outer dimension is made smaller than that of the first antenna coil L1A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an antenna device and a non-contact IC card reader / writer device.

[0002]

2. Description of the Related Art A non-contact type IC card reader / writer (hereinafter referred to as a card reader) has an antenna, and communicates with the non-contact type IC card (hereinafter referred to as an IC card) through the antenna using electromagnetic waves. To do. In this case, the card reader supplies power to the IC card by electromagnetic induction based on the transmission of the electromagnetic wave before communication with the IC card. After being activated, the IC card supplied with power performs data communication with a card reader to write data to an internal memory and read data from the memory.

[0003]

Conventionally, a round spiral antenna coil L1 as shown in FIG. 5A is used as an antenna of such a card reader. When the IC card is placed on the surface on which the antenna coil L1 is formed as shown in FIG. 5A, an antenna (not shown) of the IC card is electromagnetically induced as described above by a magnetic field generated from the antenna coil L1 due to energization. You. Conventionally, the outer diameter (R1 + R2) of the antenna coil L1 is increased to increase the communication distance between the card reader and the IC card.

However, when the outer diameter of the antenna coil L1 is increased, the surface on which the antenna coil L1 is formed is changed to XY.
Assuming that the axis is the axis, the magnetic field strength on the Z axis orthogonal to this plane depends on the portion where the antenna coil L1 is actually formed (FIG. 5).
The magnetic field intensities are different between the portions A and B in FIG. 5A and the non-formed portion where the antenna coil L1 is not formed (the portion at the center point O in FIG. 5A). That is, as shown in FIG. 5B, while the magnetic field strength on the Z axis orthogonal to the actual forming surfaces A and B of the antenna coil L1 is H2, the center which is the portion where the antenna coil L1 is not formed is H2. The magnetic field strength on the Z axis (central axis) orthogonal to the position plane of the point O is smaller than H2 above H2.
It becomes 1. The magnetic field strength H1 on the central axis decreases as the outer diameter of the antenna coil L1 increases, and as a result, as shown in the graph of FIG. On the axis, there has been a problem that the communicable distance with the IC card has become shorter and shorter, and stable long distance communication cannot be performed when communicating with the IC card.

Accordingly, the present invention provides a card reader and an IC card that can be used for long-distance communication between the card reader and the IC card by increasing the outer diameter of the antenna of the card reader and increasing the communication distance between the card reader and the IC card. An object is to enable stable long-distance communication between cards.

[0006]

In order to solve the above-mentioned problems, an antenna device according to the present invention is formed on an antenna substrate in a loop around one point, and has one end connected to one end of a capacitive element to be energized. A first antenna coil for generating a magnetic field based on the first antenna coil, the first antenna coil being formed in a loop around the one point on the antenna substrate, one end being connected to the other end of the first antenna coil, and the other end being the other end of the capacitive element And a second antenna coil having an outer diameter smaller than the outer diameter of the first antenna coil while generating a magnetic field in the same direction as the direction of the magnetic field of the first antenna coil based on energization. It is.

Further, the present invention provides a non-contact IC card having an antenna forming portion having an antenna coil formed on a surface of an antenna substrate, generating a magnetic field from the antenna coil of the antenna forming portion, and approaching the antenna forming portion. In the non-contact IC card reader / writer device for communicating with the antenna, the antenna forming portion is formed in a loop shape around the antenna substrate at one point, and one end is connected to one end of the capacitive element to generate a magnetic field based on conduction. The first antenna coil is formed in a loop around the one point on the antenna substrate, and one end is connected to the other end of the first antenna coil and the other end is connected to the other end of the capacitive element. A magnetic field in the same direction as the magnetic field generation direction of the first antenna coil is generated, and has an outer diameter smaller than the outer diameter of the first antenna coil. It is provided with a and second antenna coils.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 3 is a block diagram showing the configuration of the non-contact IC card reader / writer device according to the present invention. In FIG. 3, a non-contact IC card reader / writer device (hereinafter, referred to as a card reader) 1 includes a control unit 11 for controlling the entire card reader 1, a modulation circuit 12, and a matching circuit 13
, A resonance circuit 14 and a demodulation circuit 15.

Here, the modulation circuit 12 modulates a carrier generated from an oscillator (not shown) according to the value of the data signal SD output from the control section 11 and outputs the modulated signal to the matching circuit 13. The matching circuit 13 receives an output signal from the modulation circuit 12 and outputs the signal to the resonance circuit 14, and transmits the output signal to the resonance circuit 14 so that the output signal can be efficiently transmitted from the resonance circuit 14 to an IC card described later. The impedance matching is performed.

The resonance circuit 14 is configured such that an antenna coil L1 as an inductive element and a capacitance element C are connected in parallel, and when a modulation signal is given from the modulation circuit 12 via a matching circuit 13, resonance starts and the resonance coil 14 A radio signal is generated and transmitted to an IC card electromagnetically coupled to the antenna coil L1. The demodulation circuit 15 receives a modulation signal returned from the IC card in response to the transmission of the radio signal, demodulates the modulation signal, extracts data, and outputs the data to the control unit 11 as reception data RD.

The control unit 11 in the card reader 1 is connected to a higher-level device (not shown), and performs data communication with the higher-level device so that data received from the higher-level device is recorded on the IC card and read from the IC card. This is for transmitting data to a host device.

FIG. 4 is a block diagram showing a configuration of the IC card which is electromagnetically coupled with the card reader 1. As shown in FIG. In FIG. 4, the IC card 2 includes an antenna coil L2, a wireless interface 21, a control circuit 22 such as a CPU,
A memory 23 for storing an ID and information unique to the C card.

The wireless interface 21 of the IC card 2
When the antenna coil L1 of the card reader 1 and the antenna coil L2 of the IC card 2 are electromagnetically coupled, power is generated based on the radio signal from the card reader 1 and supplied to the control circuit 22 and the memory 23, and the clock is generated. A signal CLK is generated and supplied to the control circuit 22, and data DATA is extracted from the radio signal and output to the control circuit 22. When the power POWER from the wireless interface 21 is supplied, the control circuit 22 of the IC card 2
Data DATA from the wireless interface 21 is read in synchronization with the clock signal CLK, and the data DATA is stored in the memory 2.
3 is recorded in the memory 23 while the data DATA is command data for reading data in the memory 23, the data in the memory 23 is read and output to the wireless interface 21.

The operations of the card reader 1 and the IC card 2 will be described in detail with reference to FIGS. Card reader 1
When receiving the data for the IC card from the host device, the control unit 11 outputs the data SD to the modulation circuit 12. Upon receiving the data SD from the control unit 11, the modulation circuit 12 performs amplitude shift modulation on the carrier from an oscillator (not shown) according to the value of the input data SD, and
3 and a radio signal via the resonance circuit 14.

When the radio interface 21 of the IC card 2 receives a radio signal from the card reader 1 via the antenna coil L2, it supplies the power POWER to the control circuit 22 as described above, activates the signal, and activates the radio signal. Data DATA (that is, data SD) is extracted from the data and output to the activated control circuit 22. Here, the control circuit 22
Means that the data received from the card reader 1 is stored in the memory 23
In the case of write data to
Record in 3. If the data DATA is command data for reading the data in the memory 23, the data in the memory 23 is sequentially read in synchronization with the above-mentioned clock signal CLK and output to the wireless interface 21 side.

Data sequentially read from the memory 23 of the IC card 2 is transmitted as a radio signal to the card reader 1 via the radio interface 21 and the antenna coil L2. When receiving the radio signal from the IC card 2, the resonance circuit 14 of the card reader 1 outputs this radio signal to the demodulation circuit 15 as a modulation signal. The demodulation circuit 15
By demodulating the modulated signal, data is extracted from the modulated signal, and the extracted data RD in the memory 23 of the IC card 2 is output to the control unit 11. When the control unit 11 receives the data RD from the demodulation circuit 15, the data R
D is transmitted to the host device. In this manner, the card reader 1 can write data to the IC card 2 and read data written to the IC card 2.

FIG. 1 shows an antenna substrate 1 of a card reader 1.
It is a figure showing the formation situation of antenna coil L1 on 4A. As shown in FIG. 1, a first antenna coil L1A having a round spiral shape having an outer diameter (R1 + R2) about the center point O is formed on the antenna substrate 14A. A second antenna coil L1B having a round spiral shape with an outer diameter (R3 + R4) smaller than the outer diameter of the first antenna coil L1A is formed.

Here, the first antenna coil L1A and the second antenna coil L1B are connected in series, and are connected in parallel to the capacitive element C shown in FIG. That is, one end T1 of the first antenna coil L1A is connected to one end of the capacitive element C shown in FIG. 3, and the other end of the first antenna coil L1A is connected to one end of the second antenna coil L1B. Then, the other end T2 of the second antenna coil L1B is connected to the other end of the capacitive element C in FIG. Accordingly, if the energizing direction of the first antenna coil L1A is counterclockwise, the energizing direction of the second antenna coil L1B is also counterclockwise, while the energizing direction of the second antenna coil L1B is In the clockwise direction, the first antenna coil L
The energizing direction of 1A is also a clockwise direction, and the energizing directions of both are the same direction. Therefore, both generate a magnetic field in the same direction by energization.

Generally, there are a contact type, a proximity type, and a proximity type as a communication form between the card reader 1 and the IC card 2. The communication distance between the card reader 1 and the IC card 2 is a maximum of several cm in the case of the contact type. The proximity type is defined by ISO at a maximum of 10 cm, and the proximity type is defined at a maximum of 70 cm by ISO. The card reader 1 communicates with an IC card in a proximity type communication mode. The outer diameter of the antenna coil L1 is increased so that the distance from the IC card 2 is up to 70c.
Even in the case of m, communication with the IC card is enabled.

FIG. 2 shows an antenna substrate 1 of the card reader 1.
It is a figure showing the situation of the magnetic field generated by the above-mentioned antenna coil L1 formed on 4A. Antenna substrate 14A
As described above, the first round spiral shape having the outer diameter (R1 + R2) about the center point O is described above.
Is formed, and a second antenna coil L1B having a round spiral shape with an outer diameter (R3 + R4) smaller than the first antenna coil L1A around the center point O is formed.

Here, the first antenna coil L1
Assuming that only the first antenna coil L1A is formed, when the formation surface of the first antenna coil L1A is an XY plane composed of XY axes as shown in FIG. , B, the magnetic field strength on the Z axis perpendicular to FIG.
In contrast to H2 as shown in FIG.
The magnetic field strength on the Z axis (central axis) orthogonal to the position plane of the center point O, which is a non-formed portion of 1, is H1 as shown by a dotted line in FIG. The communicable distance with the IC card 2 is reduced. Therefore,
Since a communication error occurs when communicating with the IC card 2 and stable communication cannot be performed, it is necessary to reduce the communication speed so that a communication error does not occur when performing such long-distance communication.

Therefore, in this embodiment, as described above, the first antenna coil L
Outer diameter (R3 + R) smaller than 1A outer diameter (R1 + R2)
4), and a second antenna coil L1B having a round spiral shape in which the direction of the magnetic field generation is the same as the direction of the magnetic field generation of the first antenna coil L1A,
Connect to the first antenna coil L1A. The magnetic field generated on the central axis can be increased by the generated magnetic field based on the energization of the second antenna coil L1B.
As shown in (1), the magnetic field intensity is substantially equal to the magnetic field intensity H2 corresponding to the formation surfaces A and B of the first antenna coil L1A. As a result, even if the outer diameter of the first antenna coil L1A is increased, as shown in the graph of FIG. 2C, the communicable distance with the IC card on the central axis is reduced. When performing long-distance communication with an IC card by increasing the outer diameter of the antenna coil L1, stable long-distance communication can be performed without lowering the communication speed.

In the present embodiment, the first antenna coil L1A and the second antenna coil L1B are formed in a round spiral shape, but may be formed in a circular or rectangular shape, and may be formed in a loop shape. Good. Further, in the present embodiment, the first antenna coil L1A and the second antenna coil L1B are formed on the antenna substrate 14A of the card reader 1 that communicates with the IC card 2 in a non-contact manner, but the present invention is not limited to this. However, the same effect can be obtained even if the present invention is applied to an antenna of any device that communicates with a communication target in a non-contact manner.

[0024]

As described above, according to the present invention, a first antenna coil is formed on an antenna substrate in a loop around a center point and generates a magnetic field based on energization. A loop is formed around the center point, and one end is connected to one end of the first antenna coil to generate a magnetic field in the same direction as the magnetic field generation direction of the first antenna coil based on the energization, The second antenna coil has an outer diameter smaller than the outer diameter of the first antenna coil. Therefore, when performing the long-distance communication by increasing the outer diameter of the first antenna coil, The magnetic field strength on the central axis passing through the central point and orthogonal thereto can be increased by the magnetic field generated by the second antenna coil, so that the communicable distance on this central axis is large. Become stable long-distance communication is possible.

Also, a card reader having an antenna forming portion having an antenna coil formed on the surface of the antenna substrate and generating a magnetic field from the antenna coil of the antenna forming portion to communicate with an IC card close to the antenna forming portion. Wherein the antenna forming part is formed on the antenna substrate in a loop around the center point and generates a magnetic field based on energization, and a first antenna coil on the antenna substrate is formed in a loop around the center point. And one end is connected to one end of the first antenna coil to generate a magnetic field in the same direction as the magnetic field generation direction of the first antenna coil based on the energization, and to reduce the outer diameter smaller than the outer diameter of the first antenna coil. And the second antenna coil, the outer diameter of the antenna of the card reader is increased, and the card reader and the IC card are integrated. The problem that the strength of the magnetic field on the central axis decreases when the communication distance between the card reader and the IC card is reduced on the central axis can be avoided. Therefore, stable long-distance communication can be performed between the card reader and the IC card.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state of formation of an antenna coil on an antenna substrate of a non-contact IC card reader / writer device according to the present invention.

FIG. 2 is a diagram showing a state of generation of a magnetic field of the antenna coil.

FIG. 3 is a block diagram illustrating a configuration of a non-contact IC card reader / writer device.

FIG. 4 is a block diagram of an IC card.

FIG. 5 is a diagram showing a state of generation of a magnetic field of a conventional antenna coil.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Non-contact IC card reader / writer device, 2 ... IC card, 11 ... Control part, 12 ... Modulation circuit, 13 ... Matching circuit,
14: resonance circuit, 14A: antenna board, 15: demodulation circuit, L1, L2: antenna coil, L1A: first antenna coil, L1B: second antenna coil.

Claims (2)

[Claims] A first antenna coil that is formed in a loop shape around one point on the antenna substrate and that has one end connected to one end of a capacitive element and generates a magnetic field based on energization; and the one point on the antenna substrate. Is formed in a loop around the center, one end is connected to the other end of the first antenna coil, and the other end is connected to the other end of the capacitive element, and the magnetic field generation direction of the first antenna coil based on the energization And a second antenna coil having an outer diameter smaller than the outer diameter of the first antenna coil. 2. An antenna forming part having an antenna coil formed on a surface of an antenna substrate, wherein a magnetic field is generated from the antenna coil of the antenna forming part to communicate with a non-contact IC card close to the antenna forming part. Non-contact I performed
In the C card reader / writer device, the antenna forming portion is formed in a loop shape around one point on the antenna substrate, and has one end connected to one end of the capacitive element and generating a magnetic field based on energization. A first end connected to the other end of the first antenna coil, and the other end connected to the other end of the capacitive element, the first end being connected to the other end of the capacitive element; A non-contact IC card that generates a magnetic field in the same direction as the magnetic field generation direction of the first antenna coil and has a second antenna coil having an outer diameter smaller than the outer diameter of the first antenna coil. Reader / writer device.