JPH1153499A - Antenna structure for card type device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the antenna structure of a card type device capable of securing excellent transmission/reception sensitivity even in the case of being provided with an antenna provided with directivity. SOLUTION: The IC card 10 of a non-contact type is provided with the plural antennas 1, 2, 3, 4, 5 and 6 and an IC chip 7 connected to the antennas 1-6 and the antennas 1-6 and the IC chip 7 are entirely embedded in a case 8 made of resin. Half wavelength dipole antennas provided with the directivity are respectively constituted of the antennas 1 and 2, 3 and 4 and 5 and 6. Also, the antennas 1-6 are provided with prescribed width and radio waves are transmitted and received in the wide width part. The antennas are respectively arranged at prescribed positions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a structure of an antenna built in an IC card or the like.

[0002]

2. Description of the Related Art Conventionally, IC cards have been used as shopping cards, hospital outpatient cards, and the like. The IC card has a built-in IC chip, and can store data, input / output data to / from the outside of the card, and the like.

[0003] IC cards are roughly classified into a contact type and a non-contact type according to a method of inputting and outputting data. Contact IC
The card performs input / output of operating power and data by bringing an external electrical contact into contact with an electrical contact formed on the card surface. The non-contact type IC card has no physical contact portion on the card surface, and inputs and outputs data to and from the outside of the card by a method such as wireless or magnetic coupling.

[0004] In particular, when data is input and output wirelessly using a non-contact IC card, there is an advantage that data can be transmitted and received relatively far.

[0005]

The non-contact type I
In order to wirelessly input and output data with the C card, an antenna for transmitting and receiving radio waves is required in the card. As this antenna, a half-wavelength dipole antenna, a one-wavelength loop antenna, and the like are known. Since these antennas have directivity, if the direction of the antenna deviates from the direction in which the transmission / reception sensitivity is maximized, the transmission / reception sensitivity is reduced. For this reason, data input / output may not be performed properly depending on the direction of the IC card.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a card type capable of ensuring good transmission / reception sensitivity even when an antenna having directivity is provided. It is to provide an antenna structure of the device.

[0007]

In order to solve the above-mentioned problems, an antenna structure of a card-type device according to the present invention is provided by arranging a plurality of directional antennas so that the directions of the antennas are different from each other. The transmission / reception of radio waves in the direction in which the transmission / reception sensitivity of one antenna decreases can be compensated for by the other antennas, and good transmission / reception sensitivity can be ensured for radio waves from all directions. In particular, by providing a plurality of antennas so that the directions in which the transmission and reception sensitivities are good are orthogonal to each other, good transmission and reception sensitivities can be obtained for radio waves from all directions.

In addition, since the antenna is a split-line antenna having a meandering shape, the output impedance of the antenna can be increased and impedance matching can be achieved. Therefore, the reflection of a signal generated between the antenna and a circuit connected to the antenna can be achieved. Can be reduced.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a non-contact type IC card to which the present invention is applied will be specifically described with reference to the drawings.

FIG. 1 is a diagram showing the internal structure of a non-contact type IC card 10. As shown in FIG. 1, an IC card 10 as a card-type device includes a plurality of antennas 1, 2,
3, 4, 5, and 6, and an IC chip 7 connected to these antennas 1 to 6. The whole of the plurality of antennas 1 to 6 and the IC chip 7 are buried in a resin case 8 and are protected from external impact and the like.

Each of the antennas 1 to 6 and the like is formed using a conductive material, for example, a thick metal film or a thin film. Further, a first half-wavelength dipole antenna is constituted by the two antennas 1 and 2 arranged with the IC chip 7 interposed therebetween. Similarly, a second half-wavelength dipole antenna is formed by the two antennas 3 and 4 sandwiching the IC chip 7, and a third half-wavelength dipole antenna is formed by the two antennas 5 and 6.

The IC chip 7 includes a nonvolatile memory for storing data, a memory control unit for generating addresses and various control signals for reading and writing data from and to the memory, and a memory for reading data read from the memory. It includes a transmission / reception unit that modulates and transmits and demodulates the received radio waves, and a power supply unit that detects the received radio waves and generates an operating voltage, all of which are integrated on a common semiconductor substrate. I have. In addition, transmission and reception of radio waves are performed by a half-duplex communication method, and an antenna used at the time of transmission and reception is shared.

Next, the detailed structure of the antennas 1 to 6 will be described. FIG. 2 is a diagram showing a partial structure of each antenna. As shown in FIG.
6 has a symmetric structure with the IC chip 7 interposed therebetween. FIG. 2 shows the detailed structure of three antennas 1, 3, and 5 formed on one side thereof.

As shown in FIG. 2, each of the antennas 1, 3, 5
Is a meandering split line antenna having a predetermined width and length, in which the antenna 1 and a part of the antenna 3 are connected in series, and the antenna 5 and a part of the antenna 3 are connected in series. ing. One terminal of each of the antenna 1 and the antenna 5 is connected to each other, and this connection point is connected to one input / output terminal of the IC chip 7 as a feedback point. As described above, by forming each antenna in a meandering shape, the output impedance of the antenna 1 or 5 when viewed from the IC chip 7 can be set high and impedance matching can be performed. Can reduce signal reflection. Further, by connecting the antenna 1 and the antenna 3 in series, or by connecting the antenna 5 and the antenna 3 in series, it is possible to increase the induced voltage applied to the IC chip 7 by the antenna 1 and the like. High antenna gain can be secured.

[0015] Further, the second IC chip 7 is disposed with the IC chip 7 interposed therebetween.
The total length of the two antennas 1 and 2 is set to a value obtained by multiplying a predetermined value by a half wavelength (λ / 2) of the transmission / reception radio wave, and functions as a half-wavelength dipole antenna as a whole. The predetermined value to be multiplied by the half wavelength may be set within a range of 0.85 to 0.9 in order to operate the entire antennas 1 and 2 as a director or a radiator, for example. The specific value may be appropriately adjusted while measuring the actual transmission / reception sensitivity and the like.

The antennas 1 and 2 are set to have a predetermined width, for example, a value obtained by multiplying λ / 16 by a predetermined value, and operate along the longitudinal direction, that is, when operating as the above-described half-wavelength dipole antenna. Transmission and reception of radio waves in the direction in which the sensitivity is most reduced can be performed well.

The antennas 5 and 6 have substantially the same shape as the antennas 1 and 2 described above. The antennas 5 and 6 function as a half-wave dipole antenna, and have a predetermined width (for example, λ / 16). This is also the case in that the signal has good sensitivity to radio waves transmitted and received along the longitudinal direction.

The same applies to the antennas 3 and 4, so that the entire antenna operates as a half-wavelength dipole antenna and can transmit and receive radio waves satisfactorily along its longitudinal direction. Has become. However, in the present embodiment, the width of the antennas 3 and 4 is wider than that of the antenna 1 and the like, and is set to, for example, a value obtained by multiplying λ / 8 by a predetermined value, and operates as a half-wavelength dipole antenna. In such a case, the radio wave in the direction in which the sensitivity is most reduced can be transmitted and received more favorably.

As described above, by forming each of the antennas 1 to 6 in a meandering shape and setting the width thereof to a predetermined value, the wide portion can also be used as an antenna. In particular, the direction in which the transmission / reception sensitivity of the wide portion is maximized and the direction in which the transmission / reception sensitivity is maximized when operating as an original half-wavelength dipole antenna are mutually 9 degrees.
Since the two antennas are shifted by 0 degrees and have the highest transmission / reception sensitivity, the directions in which the transmission / reception sensitivity is reduced can be most efficiently compensated for. Also, by combining such antennas 1 to 6,
As a whole, the transmission / reception sensitivity can be further increased.

FIG. 3 shows a plurality of antennas 1 to 3 of the present embodiment.
6 is a diagram showing the overall transmission / reception sensitivity obtained by combining No. 6. As described above, the antennas 1 and 2 operate as first half-wavelength dipole antennas, the antennas 3 and 4 operate as second half-wavelength dipole antennas, and the antennas 5 and 6 operate as third half-wavelength dipole antennas. Since the directions in which the transmission and reception sensitivities of the three half-wavelength dipole antennas are the same, as shown in FIG. 3, a direction orthogonal to the longitudinal direction of the antenna (the y direction in the figure).
, One peak of the transmission / reception sensitivity appears. Further, each of the antennas 1 to 6 has a predetermined width in the y direction, and a portion along the y direction operates as an antenna. Therefore, as shown in FIG. Another peak of the transmission / reception sensitivity also appears in the direction. Therefore,
With the whole of the antennas 1 to 6, good transmission / reception sensitivity can be secured in almost all directions as shown by the dotted line in FIG.

Note that the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention.

For example, the IC card 1 of the above-described embodiment
At 0, the shape, dimensions, arrangement, etc. of the antenna are as shown in FIG. 2, but these may be changed as appropriate. For example,
A plurality of columnar dipole antennas may be arranged orthogonally.

In the above-described embodiment, the half-wave dipole antenna is formed in the IC card 10, but another antenna may be used. For example, a loop antenna or a slot antenna may be configured in the IC card 10.

In the above-described embodiment, the antennas 1 and 2, 3 and 4, and 5 and 6 constitute half-wave dipole antennas in the IC card 10, respectively.
A parallel straight line portion and a vertical straight line portion in the long side direction of the antennas 1 to 6 may each be configured as a unipole antenna having directivity.

In the above-described embodiment, the antenna is built in the IC card 10, but a PDA (Personal Digital) which is a card-type device or a portable device having no IC chip.
Assistant) or the like.

Further, in the above-described embodiment, the IC chip 7 is arranged near the center of the case 8, but this arrangement may be changed as appropriate. For example, an IC such as a case 8 sled
The chip 7 may be arranged at the corner of the case 8 in consideration of stress.

[0027]

As described above, according to the present invention, by arranging a plurality of directional antennas so that the directions of the antennas are different from each other, even if the directional antenna is provided, Good transmission and reception sensitivity to radio waves from directions can be secured.

In particular, by providing a plurality of antennas so that the directions in which the transmission and reception sensitivities are good are orthogonal to each other, the half-value angle can be widened, and good transmission and reception sensitivities can be obtained for radio waves from all directions.

[Brief description of the drawings]

FIG. 1 is a diagram showing an internal structure of an IC card according to an embodiment.

FIG. 2 is a diagram illustrating a detailed structure of an antenna according to the present embodiment.

FIG. 3 is a diagram illustrating the overall transmission and reception sensitivity obtained by combining a plurality of antennas according to the present embodiment.

[Explanation of symbols]

 1, 2, 3, 4, 5, 6 Antenna 7 IC chip 8 Case 10 IC card

Claims (3)

[Claims] A plurality of antennas having directivity;
An antenna structure for a card-type device, wherein directions of the plurality of antennas are different from each other. 2. The antenna structure of a card-type device according to claim 1, wherein the directions of the plurality of antennas are set such that directions having good transmission / reception sensitivity are orthogonal to each other. 3. The antenna structure of a card-type device according to claim 1, wherein the plurality of antennas are split-line antennas having a meandering shape.