JP2001168618A - Antenna device for reader/writer in non-contact type ic card system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the communicable area of a reader/writer for an IC card. SOLUTION: A pair of two-dimensional coils L, L respectively resonating with operation frequencies is arranged at an obtuse angle and defined as an antenna element. In the coils L, L a synthetic directional characteristic is improved as a whole and transmission and reception sensitivity can be enhanced by complementing each of directional characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a non-contact type IC.
The present invention relates to an antenna device for a reader / writer in a contactless IC card system capable of increasing a communication area of the reader / writer with the IC card in the card system.

[0002]

2. Description of the Related Art A contactless IC card system uses an IC card.
To write and read data to and from the card, a reader / writer using radio wave communication is used. Note that an antenna for transmitting and receiving radio waves is incorporated in the lead writer.

A two-dimensional coil that resonates at a used frequency is used as an antenna in a lead writer. Therefore, this device functions as a loop antenna, and by setting the IC card sufficiently close to the upper surface and in parallel with it,
Can communicate with the card.

[0004]

According to the prior art, the antenna on the reader / writer side must be set in parallel with the IC card sufficiently close to the upper surface in order to maintain stable communication with the IC card. Therefore, there is a problem that the information transmission distance from the IC card is short and the relative attitude of the IC card to the reader / writer is severely restricted, so that the usability of the IC card is not good.

SUMMARY OF THE INVENTION In view of the above-mentioned problems in the prior art, an object of the present invention is to arrange a pair of two-dimensional coils at an obtuse angle to sufficiently increase the communicable area of a reader / writer with respect to an IC card. An object of the present invention is to provide an antenna device for a lead writer in a contactless IC card system which can improve usability.

[0006]

According to the structure of the present invention for achieving the above object, a pair of two-dimensional coils is used as an antenna element, and the coils resonate at respective operating frequencies and are arranged at an obtuse angle. The gist is to supplement the directional characteristics of

Each coil can be formed on a substrate, and an auxiliary conductor can be provided on the substrate along with each coil.

The substrate can be formed separately for each coil and formed in the same pattern.

Further, each coil may be held at the same potential or may be incorporated in a common case.

[0010]

According to the structure of the present invention, a pair of two-dimensional coils are arranged at an obtuse angle to complement their respective directional characteristics, improve the overall combined directional characteristics, increase the transmission / reception sensitivity, and improve the IC sensitivity. The communicable area of the reader / writer with respect to the card can be made sufficiently large. That is, the IC card can be set to any relative posture with respect to the reader / writer, and furthermore, a sufficiently large information transmission distance can be realized. Incidentally, the pair of coils is about 120 to 170 °, particularly preferably 120 to 16 °.
It shall be arranged at an obtuse angle of 0 °. If the arrangement angle of the pair of coils is too large, it is difficult to complement the directional characteristics of each coil.If the arrangement angle is too small, the overall height will be large, which will hinder the miniaturization of the lead writer. It is. Note that the pair of coils are arranged so that their winding directions are opposite to complement each other's directional characteristics.

When each coil is formed on a substrate, each coil can be correctly fixed in a predetermined relative positional relationship via the substrate. The substrate may be formed separately for each coil, or may be formed in common for each coil. However, in the latter case, a flexible substrate is used and bent or bent at a predetermined obtuse angle.

By providing an auxiliary conductor along with each coil, the auxiliary conductor substantially increases the conductor size of the coil, improves the apparent Q of the coil, sharpens the resonance characteristics, and improves the transmission / reception sensitivity at the operating frequency. Can be further increased. At this time, each coil resonates with the auxiliary conductor at the operating frequency, and the auxiliary conductor is preferably formed in one turn with a gap in order to maximize Q at the time of resonance. In addition, the auxiliary conductor is to be electromagnetically coupled to the coil densely, and may be provided along the inside or outside of the coil, or may be disposed so as to be laminated on all or a part of the coil.

By forming the substrate separately for each coil, all the patterns including the coils, auxiliary conductors, and connection lands formed on the substrate can be made the same pattern.

If each coil is held at the same potential, there is no danger that one coil will have an extremely high potential with respect to the other.
The lead writer connected to one of the coils can be operated stably.

When each coil is incorporated in a common case, the coil can be mechanically protected via the case, and the relative positional relationship between the coils can be properly maintained.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

An antenna device for a lead writer in a contactless IC card system has a pair of coils L, L as antenna elements (FIGS. 1 and 2). Each coil L is formed on an individual substrate 21 and housed in the common case 10.

The case 10 is formed by combining a case body 11 and a lid 12. The case main body 11 is formed by bending a conductive plate material into a shallow channel shape, and has obliquely downward supporting pieces 11a, 11a formed at the upper ends of the flange portions on both sides, respectively. . Are provided at the corners on the lower surface of the case body 11, and the support blocks 11c, 11c are fixed on the upper surface of the bottom via set screws 11c1, 11c1. I have. In addition, the upper surface of each support block 11c has a corresponding support piece 11a, 1
It is cut out in a V-shape so as to be on the same plane as 1a. A coaxial connector 13 for connecting a lead writer (not shown) is provided on one of the flange portions of the case body 11 via set screws 13a.

The lid 12 is formed in a shallow box shape that is open to the bottom and fits the case body 11. The lid 12 is integrally formed of an insulating synthetic resin material and has set screws 12a and 12a.
a to the case body 11 via the
Before and after, the upper surface can be closed.

The substrate 21 has mounting holes 21a, 21 at four corners.
a ... and a case body 11
(See FIGS. 1 and 3). On the back side of the substrate 21, a two-dimensional spiral coil L and a land G are formed, and on the front side, an auxiliary conductor D laminated on the coil L and pattern lines P1 and P2 are formed. I have. The outer peripheral end of the coil L is connected to the land G, and the inner peripheral end is connected to the pattern line P1 on the surface of the substrate 21 via the through hole P1a. Also,
The auxiliary conductor D is formed in one turn having a gap D1 and has a sufficiently large conductor width so as to be laminated on the entire coil L. The substrates 21, 21 are formed separately for each coil L, and all the patterns including the coil L, the auxiliary conductor D, the land G, and the pattern lines P1, P2 are formed in the same pattern.

On one substrate 21, a capacitor VC1 for resonance and a capacitor VC2 for impedance matching are mounted, and on the other substrate 21, only a capacitor VC1 for resonance is mounted. Note that the capacitor VC
1, VC1, VC2 are each of a variable capacitance type. The capacitor VC1 is interposed between the land G on the back surface of the substrate 21 and the pattern line P1 on the surface of the substrate 21 via the through hole P1b, and the capacitor VC2 is provided between the pattern lines P1 and P2 on the surface of the substrate 21. It is interposed.

Each of the substrates 21 and 21 has a set screw 21
The support pieces 11a, 11a and the support blocks 11c, 11c are fixed to the case body 11 so as to extend diagonally through the support pieces 11a, 11b,. At this time, each board 21 is inclined with respect to the bottom of the case
°, and they are arranged at an obtuse angle of mutual opening angle θa 角 150 °. Further, the substrates 21 and 21 are provided with coils L and L
Are fixed to each other so that the winding directions are opposite to each other (FIG. 1).

In this manner, the substrate 2 is
When 1, 21 are fixed, the coils L, L, the capacitor VC
1, VC1, VC2 are electrically connected as shown in FIG. That is, the lands G,
The capacitor VC1 is connected via the pattern line P1,
The coils L, L are held at the same potential via the lands G, G, and the case body 11. One end of one coil L is connected to the center pole of the coaxial connector 13 via the pattern line P1, the capacitor VC2, and the pattern line P2, and the other end is connected to the land G and the case body 11 via the case body 11. It is connected to the sheath pole. Note that a lead writer (not shown) is connected to the coaxial connector 13.

Each coil L is provided with a resonance capacitor VC1.
And the auxiliary conductor D that is electromagnetically coupled to the coil L and resonates at the operating frequency. At this time, the gap D1 of the auxiliary conductor D
Forms a part of a resonance capacitor, and in each coil L, the apparent Q becomes high due to the presence of the high-Q auxiliary conductor D, so that sharp resonance characteristics and high transmission / reception sensitivity can be obtained.

The coils L, L are arranged at an obtuse angle of the opening angle θa, so that their directional characteristics A1, A
Complementary to the above, a good combined directional characteristic A2 can be realized as a whole (FIG. 5A). Then, coil L,
L indicates whether the IC card CD is moved laterally along the upper surface of the case 10 (solid line in FIG. 2, in the direction of arrow K1) or vertically moved (single-dot chain line in FIG. 2, in the direction of arrow K2). , And an IC card CD. In other words, the read writer at this time has a larger communicable area with the IC card CD, and can substantially eliminate the restriction on the relative attitude of the IC card CD. FIG. 5B shows a comparative example in which the coils L, L are arranged on the same plane. In this case, the combined directional characteristic A2 has a large drop at the center, which is not practically preferable. .

In the above description, instead of forming the auxiliary conductor D as a pattern on the substrate 21, the auxiliary conductor D is formed of a conductive sheet material such as copper, aluminum, silver, or the like. It may be laminated on top. Also,
The auxiliary conductor D may be tightly electromagnetically coupled to the coil L, and may be deformed into any form other than that shown. The auxiliary conductor D may be omitted entirely.

[0027]

[Other Embodiments] The coils L, L are provided on separate substrates 21,
Instead of forming on the common substrate 21, the common substrate 21 may be used. At this time, the substrate 21 is made of a flexible substrate and is bent or curved at a predetermined opening angle θa.

The coils L, L may be combined in plural pairs (FIG. 6). By arranging the adjacent pairs of coils L, L at the opening angle θa, it is possible to realize better combined directional characteristics as a whole.

[0029]

As described above, according to the present invention, by arranging a pair of two-dimensional coils each resonating at the operating frequency at an obtuse angle as an antenna element, each coil complements its directional characteristic. As a result, good combined directional characteristics can be realized, and transmission / reception sensitivity as a whole can be increased. Therefore, it is possible to increase the communicable area of the reader / writer with respect to the IC card and substantially eliminate the limitation on the relative attitude of the IC card. Thus, there is an excellent effect that the information transmission distance between the reader / writer and the IC card can be increased and the usability of the IC card can be greatly improved.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of the entire configuration.

FIG. 2 is an enlarged cross-sectional view corresponding to line XX of FIG. 1;

FIG. 3 is an enlarged exploded perspective view of a main part.

FIG. 4 is an equivalent circuit diagram

FIG. 5 is a diagram illustrating directivity characteristics;

FIG. 6 is a schematic explanatory view showing another embodiment.

[Explanation of symbols]

 A1 ... directional characteristics L ... coil D ... auxiliary conductor 10 ... case 21 ... board

Claims (6)

[Claims] 1. A non-contact type IC card comprising a pair of two-dimensional coils as antenna elements, wherein the coils resonate at respective operating frequencies and are arranged at obtuse angles to complement their directional characteristics. Antenna device for the lead writer in the system. 2. The antenna device for a reader / writer in a contactless IC card system according to claim 1, wherein each of the coils is formed on a substrate. 3. The antenna device for a reader / writer in a contactless IC card system according to claim 2, wherein an auxiliary conductor is provided on the substrate along with each of the coils. 4. The substrate according to claim 2, wherein said substrate is formed separately for each of said coils and has the same pattern.
4. An antenna device for a lead writer in the contactless IC card system according to claim 3. 5. The antenna device for a read writer in a contactless IC card system according to claim 1, wherein each of the coils is maintained at the same potential. 6. The antenna device for a reader / writer in a contactless IC card system according to claim 1, wherein each of the coils is incorporated in a common case.