JPH05299927A - Information card - Google Patents

Abstract

PURPOSE:To provide a similar directive pattern to that of a half wavelength folded dipole antenna and to prevent destruction of an element due to static electricity by adopting a half wavelength reflected dipole pattern for an antenna pattern provided to the information card. CONSTITUTION:A half wavelength folded dipole pattern is adopted for an antenna pattern provided to the information card 10 used for an information card system utilizing a microwave and sending/receiving data contactless. The half wavelength folded dipole pattern consists of a half wavelength folded dipole antenna part 11, a folded wire 21 in parallel with the antenna part 11, and a connection wire 22 used to interconnect the antenna part 11 and the folded wire 21. Since the half wavelength folded dipole antenna part 11 is provided with the folded wire 21 in parallel with half wavelength antenna parts 11a, 11b, no open state is caused when viewing from an element (FET14) inserted and connected between antenna element, and then element destruction due to static electricity is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information card used in an information card system for transmitting or receiving data in a contactless manner using microwaves.

[0002]

2. Description of the Related Art As an information card (also referred to as a microwave card) system for transmitting or receiving data in a contactless manner using microwaves, the data in the card is transmitted using microwaves having a frequency of, for example, 2.45 GHz. , Non-contact reading within a distance of about 1.5 m has been proposed. The antenna provided in this information card (microwave card) is generally a one-wavelength loop or a half-wavelength dipole because of its simple structure, but each has its advantages and disadvantages.

First, FIG. 10 shows a card reader (card reader) 100 and an information card (microwave card) 110 having a half-wavelength dipole antenna 111. In the information card 110 of FIG. 10, a dipole antenna 111 having a length of a half wavelength (λ / 2) in total of two antenna elements, an IC (integrated circuit) 112 in which information is stored, and a circuit power supply. Battery 113
And a FET (field effect transistor) 114 as a switching element. FET114 is
The half-wave dipole antenna 111 is inserted and connected at an intermediate position between two elements, and is turned on and off according to the data of the IC 112. The impedance of the antenna 111 changes depending on whether the FET 114 is turned on or off.

In the card reading device (card reader) 100 shown in FIG. 10, a signal from a microwave oscillator 101 is sent to a transmitting antenna 102, and the transmitting antenna 1
A non-modulated radio wave is emitted from 02 toward the information card 110, and the reflected wave is received by the receiving antenna 103. In the information card 110, the FET 114 is turned on and off according to the data of the IC 112 to turn on the antenna 1
Since the impedance of 11 changes, the level of the reflected wave changes, and the signal amplitude-modulated by the data is received by the receiving antenna 103. The received signal from the antenna 103 is sent to a multiplier 104 for synchronous detection, is multiplied with the signal from the oscillator 101 to be synchronously detected, and is sent to a signal processing circuit 105 to undergo signal processing to obtain information. The data on the card 110 is read.

Next, FIG. 11 shows a one-wavelength loop antenna 12
1 shows an information card 120 with 1. This information card 120 is provided with a loop antenna 121 having a length of one wavelength for one round, and other parts are the same as the information card 110, such as IC 122, battery 123, and FET 124.
Is provided. FET124 is the loop antenna 1
A part of 21 is cut and inserted and connected to the cut portion. When the FET 124 is turned on and off according to the data of the IC 122, the impedance of the antenna 124 changes,
The card reading device (card reader) 10 shown in FIG.
The reflected waves of the radio waves (microwaves) emitted from 0 are subjected to amplitude modulation, whereby the information card 120
The reading of the data is similar to the above-mentioned example.

[0006]

By the way, the above-mentioned FIG.
In the case of the half-wavelength dipole antenna 111 used in the information card 110 shown in FIG. 12, in the plane including the antenna 111, an 8-shaped directivity is shown as shown in FIG. As shown in, the card reader is nondirectional in the direction of rotation about the antenna 111, that is, in the plane perpendicular to the antenna 111, and the card reader can detect the card in a wide range. On the other hand, since the drain-source of the FET 114 connected between the elements of the antenna 111 is open in terms of direct current, the drain-source voltage V _DS may exceed the rated value of the FET 114 due to static electricity. It has the drawback of being easily destroyed.

On the other hand, the one-wavelength loop antenna 121 used in the information card 120 shown in FIG.
In the case of, as shown in FIG. 13, since a directivity of a figure 8 is shown both in the direction perpendicular to the plane including the antenna 121 and in the rotation direction, the detection range is in the case of the half-wavelength dipole antenna 111. However, since the drain-source of the FET 124 is short-circuited in terms of direct current, the drain-source voltage V _DS becomes static due to static electricity.
Does not exceed the rated value of, and the FET 124 is not destroyed.

Next, FIG. 14 shows an example of an information card in which data can be written in a non-contact manner. The information card 130 includes a receiving (data capturing) half-wavelength dipole antenna 131. A detection circuit 132 connected to the two elements of the antenna 131 is provided. In addition, a half-wavelength dipole antenna 111, an IC 112, a battery 113, and a FET 114 are provided as in the information card 110 of FIG. In addition, the information card 140 includes a single-wavelength loop antenna 14 for reception.
1, a detection circuit 142 connected to the loop antenna 141, a one-wavelength dipole antenna 121, an IC 122, a battery 123, and a FET 124 similar to those in FIG. 11 are provided.

As the information card reading / writing device 150, a microwave oscillator 101, a transmitting antenna 102, a receiving antenna 103, and a synchronous detection multiplication device similar to the card reading device 100 shown in FIG. 10 described above. A signal processing circuit 151 is provided for outputting write data as well as reading data, and a modulator 152 for amplitude-modulating the signal from the microwave oscillator 101 by the write data from the signal processing circuit 151, for example. And an amplifier 153 for amplifying the modulated signal from the modulator 152 and sending it to the transmitting antenna 102.

To write data, the modulated signal radio wave from the transmitting antenna 102 of the device 150 is transmitted to the information card 130.
(Or 140) receiving antenna 131 (141)
The data is read by the detection circuit 132 (142) and is read by the detection circuit 132 (142), and the data is taken into the IC 112 (122).

Here, when a simple amplitude modulation such as so-called ASK (amplitude shift keying) is performed as the data modulation method, the detection circuit 132 (14)
2) is, for example, as shown in FIG.
And the resistor 135 alone. Here, particularly when the half-wavelength dipole antenna 131 is used like the information card 130, when a high voltage is generated in the antenna 131 due to static electricity or the like, the diode 134 and the input stage portion of the IC 112 connected to the detection circuit 132 are connected. May be destroyed.

Next, FIG. 16 shows an example of a system for emitting a radio wave modulated with data from an information card. The information card 170 shown in FIG. 16 includes a half-wavelength dipole antenna 171 for transmission, an IC 172 in which data to be transmitted is stored, and a battery 173 for circuit power supply.
, Microwave oscillator 174, modulation / amplification circuit 175
And a signal from the microwave oscillator 174
The transmitting antenna 17 is modulated and amplified by the data from 72.
I am sending to 1. The information card 180 is the same as the information card 170 except that the one-wavelength loop antenna 181 is used for transmission, and has an IC 182, a battery 183, a microwave oscillator 184, and a modulation / amplification circuit 185. The operation is similar to that of the information card 170.

This information card 170 (or 180)
Modulated wave from the card reading device (card reader)
The detection circuit 1 receives the signal from the receiving antenna 161 of 160.
The signal is detected at 62 and read by the signal processing circuit 163.

Here, the above-mentioned AS is used as the data modulation method.
When K is used, as a modulation / amplification circuit 175 (same for 185), for example, as shown in FIG. 17, an amplification transistor 176 for amplifying an oscillation output from a microwave oscillator 174 and a battery 173. Power on
A switch 177 that is turned off, a resistor 178 that supplies the output (power supply) from the switch 177 to the collector of the amplification transistor 176, and the amplification transistor 176.
Can be configured with a capacitor 179 connected to the collector of the. The microwave (carrier wave) is modulated by amplitude shift keying by controlling the switch 177 on / off by the data from the IC 172.

In the case of such a configuration, particularly when the antenna 171 is separated by two elements and the collector-emitter of the transistor 176 is opened like the information card 170, the transistor 176, The switch 177 etc. may be destroyed.

In the examples shown in FIGS. 14 to 17, in the case of the one-wavelength loop antenna, destruction of the element due to the static electricity is unlikely to occur, but the directivity pattern is narrow as shown in FIG. 13 and is directly above the card. If the card reader or the like is not located directly below, there is a possibility that data cannot be read effectively.

The present invention has been made in view of such circumstances, and provides an information card having a directivity pattern similar to that of the above-mentioned half-wavelength dipole antenna and resistant to destruction of elements due to static electricity. The purpose is.

[0018]

An information card according to the present invention is an information card used in an information card system for transmitting or receiving data in a contactless manner by using microwaves. The above-mentioned problems are solved by using a half-wave folded dipole.

Here, the antenna pattern of the half-wavelength folded dipole comprises a half-wavelength dipole antenna portion, a folding line parallel to the antenna portion, and a connecting line connecting the antenna portion and the folding line. ..

[0020]

Since the half-wavelength folded dipole antenna has the folded line parallel to the half-wavelength antenna part, it does not appear to be open when viewed from the elements inserted and connected between the antenna elements. It becomes possible to prevent element destruction due to static electricity.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a schematic configuration of an embodiment of an information card according to the present invention, and FIG. 2 is a diagram showing details of an antenna portion. In FIG. 1 and FIG. 2, the information card 10 has two antenna elements 11a and 11a.
The dipole antenna part 11 having a length of half a wavelength (λ / 2) as a whole, the folding line 21 provided in parallel with the dipole antenna part 11, and the dipole antenna part 11 and the folding line 21 are provided. Connecting line 2 to connect
2 are provided, and these dipole antenna parts 11 and
The folded line 21 and the connection line 22 constitute a half-wavelength folded dipole antenna. Information card 1
IC (integrated circuit) 1 in which information data is stored in 0
2, a battery 13 for a circuit power supply, and a FET (field effect transistor) 14 as a switching element are provided. The FET 14 is a half-wave dipole antenna 11
Is connected to an intermediate position between the two elements 11a and 11b, and is turned on and off according to the data of the IC 12. The impedance of the antenna 11 changes depending on whether the FET 14 is turned on or off.

The card reading device (card reader) is
It may have the same configuration as the device 100 of FIG.
Further, since the data reading operation is similar, the description thereof will be omitted because it is not shown.

The half-wavelength folded dipole antenna as shown in FIGS. 1 and 2 is an antenna having an intermediate structure between the half-wavelength dipole and the one-wavelength loop, and the directivity pattern is almost the same as that of the half-wavelength dipole antenna. Is the same. Here, for example, as shown in FIG. 3, specific examples of the directivity pattern in the case where the elements 11a and 11b of the dipole antenna unit 11 are provided at a predetermined angle α are shown in FIGS. ing.

That is, FIGS. 4 and 6 show directivity patterns in a plane including the dipole antenna section 11, and FIGS. 5 and 7 show in a plane orthogonal to the axis of the dipole antenna section 11. The directivity patterns are shown respectively. In FIGS. 4 and 5, the width d of the dipole antenna unit 11 is
₁ is 1.0 mm, the width d ₂ of the folded line 21 is 0.5 mm, and the directivity pattern is shown when the distance S between the antenna part 11 and the folded line 21 is changed, and S = 0. 5
When x is mm, it is marked with ×, when S = 2.0 mm, it is marked with ○, and S =
When it is 4.0 mm, it is plotted with a triangle. For reference, the case of a normal half-wave dipole antenna without a folded line is shown by a broken line. Next, FIG. 6 and FIG.
Shows the directivity pattern when the width d ₁ of the antenna part 11 is 1.0 mm, the distance S is 1.0 mm, and the width d ₂ of the folded line 21 is changed. D ₂ = 0.5 mm Is plotted with x, when d ₂ = 1.0 mm is plotted with ◯, and when d ₂ = 2.0 mm is plotted with Δ. In these FIGS. 6 and 7, the case of a normal half-wave dipole antenna is also indicated by a broken line for reference. The level is in dB units, and -68 dB is used as a reference in FIGS. 4 and 6, and -66 dB is used as a reference in FIGS.

From these FIGS. 4 to 7, it is apparent that the directivity pattern of the half-wavelength folded dipole antenna is substantially the same as the directivity pattern of the half-wavelength dipole antenna as shown by the broken line. .. In addition, FET
The ON / OFF ratio of the reflected wave intensity depending on ON / OFF of 14 is smaller than that of the half-wave dipole antenna, but the ratio is changed by changing the pattern widths d ₁ and d ₂ and the distance S in FIG. Can be made Changing these values corresponds to changing the feeding point impedance of the antenna, and the value of this impedance and the on / off ratio of the reflected wave have a predetermined relationship. According to the experiment, d ₂
When / d ₁ is decreased and S is increased within a certain range, the ON / OFF ratio of the half-wave dipole antenna without folding is approached. The reason that d ₂ / d ₁ is small and S is wide is in the direction in which the impedance decreases, and therefore approaches the impedance of the half-wave dipole. this is,
This is because the impedance of the half-wave folded dipole is higher than the impedance of the half-wave dipole.

From the above, in the case of a half-wavelength folded dipole, it is possible to change the signal strength from the information card depending on the shape of the pattern, and when it is desired to reduce the detection distance, the above pattern of the antenna pattern of the card is used. Width d
It is possible to suppress the intensity of the reflected wave by changing ₁ and d ₂ and the distance S. That is, when d ₂ / d ₁ is increased and S is decreased, the detection distance is shortened. If it is reversed, the on / off ratio of the reflected wave can be made close to that of a half-wave dipole. Such an adjustment cannot be easily performed with the half-wavelength dipole antenna without folding and the one-wavelength loop antenna.

Next, FIG. 8 shows two elements 11a and 1a.
A plurality of (for example, n) folded lines 21 ₁ and 21 parallel to the half-wave dipole antenna portion 11 made of 1b.
₂ , ..., 21 _n are shown as an example, and the antenna portion 11 and the folded lines 21 ₁ , 21 ₂ , ..., 21 thereof are shown.
It is connected to _n by a connection line 22. It is also possible to make the characteristics different depending on the number n of the folded lines 21 ₁ , 21 ₂ , ..., 21 _n . That is, when the number n is increased, the impedance is increased and the ON / OFF ratio of the reflected wave is decreased, so that the detection distance is shortened.

Here, in order to be able to variably adjust the number n of the folded lines, a configuration as shown in FIG. 9 may be used. In FIG. 9, two half-wavelength dipole antenna parts 11 each composed of two elements 11a and 11b are provided in parallel with each other, and two elements 3 each are provided.
_{1 1a, 31 1b, 31 2a} , 31 2b, ..., 31 na, 31 folding line 31 ₁ of the n (n set) consisting of _nb, 31 _2, ...,
31 _n are provided. Antenna element 11
a and 11b and folded line elements 31 _1a and 31
_The connection points 32 _1a and 32 _1b , which are respectively surrounded by broken lines, can be connected to _1b by using a method such as bonding or injection of a conductive substance.
_The connection point 33 ₁ can be connected between _1a and 31 _1b in a similar manner. These connection points 32 _1a , 32 _1b ,
And 33 ₁ are connected to form a half-wavelength folded dipole antenna in which the half-wavelength dipole antenna section 11 and the folded line 31 ₁ are connected. Similarly, some of the connection points 32 _2a , 32 _2b , ..., 32 _na , 32 _nb are connected as needed, and desired connection points 33 ₂ ,.
By connecting one of 33 _n , the folding line 3
One of 1 ₂ , ..., 31 _n can be connected to the half-wave dipole antenna unit 11. Here, by cutting the center of each folded line, the connection points 33 ₁ , 33 ₂ , ...,
The value 33 _n is used to prevent the characteristic from being disturbed due to the reflection of the radio wave on the folded line that is not used. The above-mentioned connection points 32 _1a , 32 _1b , 32 _2a , 3
2 _2b , ..., 32 _na , 32 _nb together with a plurality of sets of connection points 33
By connecting a plurality of ₁ , 33 ₂ , ..., 33 _n , a plurality of folded lines can be connected to the antenna unit 11.

As described above, when the antenna pattern of the information card is a half-wave folded dipole, a directivity pattern similar to that of the half-wave dipole is obtained, and the detection range of the card reader (card reader) is increased. As the width becomes wider, the detection distance and the directivity pattern can be changed by changing the line width, the interval, the number of lines, and the like. The half-wavelength folded dipole antenna is a one-wavelength loop structurally, and since the drain and source of the FET are short-circuited, it is resistant to breakdown due to static electricity.
The half-wavelength folded dipole antenna is also capable of reading data by an electromagnetic induction method without using microwaves at a close distance as in the case of a one-wavelength loop antenna. It will have both properties of short-distance type (proximity type) by induction.

The present invention is not limited to the above embodiment, and for example, an information card 130 capable of writing data by radio waves as shown in FIG.
Alternatively, the half-wavelength folded dipole antenna of the present invention can also be used for a half-wavelength dipole antenna such as an information card 170 capable of transmitting data.

[0031]

As is apparent from the above description, according to the information card of the present invention, since the antenna pattern is a half-wavelength folded dipole, it is provided parallel to the antenna portion for half a wavelength. Due to the folded line, the element inserted and connected between the elements of the antenna section is short-circuited in terms of direct current, and it is possible to prevent element destruction due to static electricity. In addition, the half-wavelength folded dipole antenna shows a directivity pattern similar to that of the half-wavelength dipole antenna. The reading distance and the directivity pattern can be adjusted by changing the width and the like. Further, similar to the one-wavelength loop antenna, it is possible to read the data of the information card by utilizing the electromagnetic induction in the vicinity.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of an information card according to the present invention.

FIG. 2 is a diagram showing an antenna pattern of the embodiment.

FIG. 3 is a diagram showing a schematic configuration of an information card used for measuring a directional pattern.

FIG. 4 is a diagram showing a directivity pattern in a plane including an antenna.

FIG. 5 is a diagram showing a directivity pattern in a plane perpendicular to the antenna axis.

FIG. 6 is a diagram showing a directivity pattern in a plane including an antenna.

FIG. 7 is a diagram showing a directivity pattern in a plane perpendicular to the antenna axis.

FIG. 8 is a diagram showing an antenna pattern of another embodiment of the information card according to the present invention.

FIG. 9 is a diagram showing an antenna pattern of still another embodiment of the information card according to the present invention.

FIG. 10 is a diagram showing a schematic configuration of a conventional example of an information card system.

11 is a diagram showing another example of an information card used in the information card system of FIG.

FIG. 12 is a diagram showing a directivity pattern of a half-wavelength dipole antenna.

FIG. 13 is a diagram showing a directivity pattern of a one-wavelength loop antenna.

FIG. 14 is a diagram showing a schematic configuration of another conventional example of the information card system.

15 is a diagram showing a schematic configuration of an antenna and peripheral circuits of an information card used in the information card system of FIG.

FIG. 16 is a diagram showing a schematic configuration of still another conventional example of the information card system.

17 is a diagram showing a schematic configuration of an antenna and peripheral circuits of an information card used in the information card system of FIG.

[Explanation of symbols]

10 ... Information card 11 ... Half-wavelength dipole antenna section 12 ... IC (integrated circuit) 13 ... Battery 14 ... FET 21, 21 _{1 to} 21 _n , 31 _{1 to} 31 _n ... Folded line 22 ... Connection line

Claims (1)

[Claims] 1. An information card used in an information card system for transmitting or receiving data in a contactless manner using microwaves, characterized in that an antenna pattern provided on the information card is a half-wave folded dipole. card.