JPH113411A - Ic card - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive IC card which easily adjusts the inductance of an antenna coil that is formed on a plane. SOLUTION: An IC card consists of a circuit that is printed on the surface of a plastic film 1; an antenna coil 2 which has at least one turn; an IC 4 which is connected to the circuit; and a covered member that consists of plastic film or a sheet. In the above IC card, the IC 4 is electrically connected to an end of the coil 2, and one turn coil 3 which has almost the same shape as an area that is created by the outermost and innermost circumferences of the printed coil 2 and whose one end is open is printed on the rear of the antenna 2 of the film 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a non-contact type IC card.

[0002]

2. Description of the Related Art As disclosed in Japanese Patent Application Laid-Open No. Hei 8-216570, an antenna coil for a non-contact type IC card is formed by superposing a plurality of antenna coils printed on a plastic film to form a coil for each layer. In general, the antenna coil is printed on both sides of the plastic film, and the antenna coils on both sides are connected through through holes.

[0003]

In such an antenna coil, it is difficult to finely adjust the value of the inductance of the coil. Adjustment of the inductance of a coil configured on a plane requires increasing or decreasing the number of turns of the coil or changing the size of the coil. Further, forming a through-hole as in the related art not only increases the cost but also reduces the production yield.

According to the present invention, it is possible to easily adjust the inductance of an antenna coil formed on a plane and to use an inexpensive IC.
The purpose is to provide a C card.

[0005]

As shown in FIG. 1, an antenna coil for an IC card according to the present invention is connected to a circuit printed on the surface of a plastic film 1, an antenna coil 2 having at least one turn, and the circuit. In an IC card comprising an IC 4 and a covering member 18 (not shown) made of a plastic film or sheet, the IC 4 is electrically connected to an end of the antenna coil 2 and the printed antenna coil 2 A one-turn coil 3 having a shape substantially equal to the area formed by the outermost and innermost circumferences and having one end opened is printed on the back surface of the printed antenna 2 of the plastic film 1.

In this way, the inductance of the antenna 2 can be adjusted by changing the shape of the one-turn coil 3, and without connecting the one-turn coil 3 on the back surface to the antenna 2. Can be adjusted,
There is no need to provide through holes.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, an antenna coil 2 is printed on the surface of a thin plastic film 1, and the rear surface thereof has a wide width so as to cover the outermost and innermost circumferences of the antenna coil 2. The one-turn coil 3 which is open at one end is printed. The end a of the antenna coil 2 is
The terminal is connected to the terminal 6 of the IC 4 via the terminal b via the jumper wire 5, and the other end of the antenna coil 2 is directly connected to the other terminal 7 of the IC 4. On the other hand, a gap 8 is provided in the one-turn coil 3 on the back surface, and the one-turn coil 3 is open without being connected to the antenna 2 on the front surface. When the one-turn coil 3 is completely closed, the magnetic flux generated by the current flowing through the antenna coil 2 and the one-turn coil are coupled by electromagnetic induction, and a current in a direction opposite to the current is applied to the one-turn coil. It is indispensable to prevent the flow and ohmic loss from occurring, and at the same time to prevent the inductance of the antenna coil 2 from decreasing.

FIG. 2 is a sectional view taken along a line AB in FIG.
As shown in FIG. 3, the antenna coil 2 and the one-turn coil 3 form capacitors C1 and C2 via the thin plastic film 1, and the area of the antenna coil 2 and the one-turn coil 3 facing each other and the thin plastic film 1 It is determined by the relative permittivity εr depending on the material. This capacitance C1
And C2, and the capacitance C3 between the wires of the coil 2, the IC
FIG. 4A shows an equivalent circuit of impedance when the antenna coil side is viewed from the terminals 6 and 7 of FIG. L is the inductance of the antenna coil 2, Rdc is its DC resistance, C1, C2, and C3 are the capacitances described above, and R is C
1, a resistance representing the dielectric loss of the thin plastic film 1 forming C2. C1 and C2 are larger as the thickness of the thin plastic film 1 is smaller, and are smaller as the area where the antenna coil 2 and the one-turn coil 3 face each other is smaller. The larger the resistance R representing the dielectric loss, the smaller the loss, so that a coil with good performance can be obtained. R
Is determined by the material of the plastic film 1,
There is no problem if a material having a small dielectric loss tangent (tan δ) is selected.

Since C1 and C2 are connected in series and C3 is connected in parallel to it, the combined capacitance C is eventually C = C1 · C2 / (C1 + C2) + C3, and the equivalent circuit is shown in FIG. ). The capacitance of the line capacitance C3 is small because the medium is air and the facing area is small. Therefore, the value of C is almost determined by C1 and C2, that is, the area where the antenna coil 2 and the one-turn coil 3 face each other and εr.

In the equivalent circuit of FIG. 4B, the impedance when the coil side is seen from the terminals 6 and 7 of the IC when C changes is as shown in the Smith chart of FIG.
On this Smith chart, only 1 for antenna coil 2
Assuming that the impedance when the turn coil 3 is not present (C = 0) is 9, if the one-turn coil 3 is present and C has a value, the impedance moves clockwise in the Smith chart and is indicated by 10 Value. If the value of C further increases, the impedance moves further clockwise to a value as indicated by 10 '. That is, if the value of C increases, the impedance is equivalent to the adjustment of the inductance L by adjusting the value of C, which is equivalent to the increase of the inductance L of the antenna coil 2.
It is to be noted that the impedances 9, 10, and 10 'are not located at the outermost periphery of the Smith chart and move slightly inside because of the loss due to Rdc shown in FIG. Further, R in FIG.
If the value of is small, the impedances 9, 10, 10 '
Further, the inner locus of the Smith chart is moved. As described above, if the capacitance C is adjusted,
The impedance of the antenna 2 can be adjusted by adjusting the area where the antenna 2 and the one-turn coil 3 face each other.

[0011]

【Example】

Example 1 As shown in FIG. 6, unnecessary portions of aluminum foil on both sides of an aluminum foil-clad flexible laminated film in which aluminum foil was adhered to both sides of a polyethylene terephthalate film 11 were removed by etching.
An antenna coil 12 is formed on the front surface, and a one-turn coil 13 is formed on the back surface, thereby forming a card substrate. The one-turn coil 13 has a gap 20 substantially equal to its width, and is not a closed loop. Antenna coil 12 on the surface
The ends e and f are electrically connected to each other through a conductor provided on the IC 16 using an anisotropic conductive film as an adhesive member.
The ends c and d form an antenna coil and the IC 16
Is connected to the circuit provided in. The spacer 17 made of polyethylene terephthalate film has an IC
The portion corresponding to No. 16 is pierced, and is laminated on the card substrate via an adhesive to reduce unevenness on the surface. A non-contact IC card is formed by laminating a polyethylene terephthalate film coated with an adhesive as a covering member 18 on the uppermost surface and the lowermost surface.

Embodiment 2 As shown in FIG. 7, as a result of increasing the gap 20 of the one-turn coil in the eleventh embodiment to approximately four times the coil width, the impedance could be reduced by 5%.

Example 3 As shown in FIG. 8, the coil width of the one-turn coil in Example 1 was reduced by 20%, and as a result, the impedance could be reduced by about 11%.

In the above description, the antenna coils 12, 1
Although the case where the member forming the turn coil 13 is an aluminum foil-coated polyethylene terephthalate film has been described, the invention is not limited to this, and a conductor portion obtained by etching a copper foil can be used. A printing process using a so-called silver paste may be used.
Needless to say, similar effects can be obtained by using polyethylene, paper, or the like in addition to polyethylene terephthalate for the dielectric portion.

[0015]

As described above, according to the present invention, the inductance of the antenna coil formed on a plane can be easily adjusted, and at the same time, the inductance of the antenna coil can be increased or decreased without providing a through hole. Inexpensive I with high reliability and good yield during production
C card can be provided.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing one embodiment of the present invention.

FIG. 2 is a sectional view taken along a line AB in FIG.

FIG. 3 is a cross-sectional view for explaining the principle of the present invention.

FIGS. 4A and 4B are equivalent circuit diagrams for explaining the principle of the present invention.

FIG. 5 is a Smith chart for explaining the principle of the present invention.

FIG. 6 is an exploded perspective view showing one embodiment of the present invention.

FIG. 7 is a perspective view of a main part showing another embodiment of the present invention.

FIG. 8 is a sectional view showing still another embodiment of the present invention.

[Explanation of Codes] Plastic film 2. Antenna coil 3.1 turn coil 4,16. IC5. 7. Jumper wire Gap 9, 10, 10 '. Impedance 12. Antenna coil 13.1 turn coil 17,18. Polyethylene terephthalate film 20. gap

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04B 5/00 G06K 19/00 K

Claims (5)

[Claims] 1. A circuit printed on the surface of a plastic film (1) and an antenna coil (2) having one or more turns, an IC (4) connected to the circuit, and a covering member (18) made of a plastic film or sheet. ), The above-mentioned IC (4) is electrically connected to the end of the above-mentioned antenna coil (2), and an area formed by the outermost and innermost circumferences of the printed antenna coil (2). An IC card characterized in that a one-turn coil (3) having an end substantially open and having a shape substantially equal to that of the antenna is printed on the back surface of the printed antenna (2) of a plastic film (1). 2. The opposing area of the antenna coil (2) and the one-turn coil (3) is changed by changing the length of the one-turn coil (3) to change the impedance of the antenna coil (2). The IC card according to claim 1, wherein the IC card is changed. 3. The area of the antenna coil (2) facing the one-turn coil (3) is changed by changing the width of the one-turn coil (3) to change the impedance of the antenna coil (2). The IC card according to claim 1, wherein the IC card is operated. 4. The impedance of the antenna coil (2) is changed by shifting the relative position of the antenna coil (2) and the one-turn coil (3) in a direction parallel to the surface of the plastic film (1). I is changed according to any one of claims 1 to 3.
C card. 5. The antenna coil (2) and the one-turn coil (3) are printed on the front and back surfaces of a plastic film (1) using a so-called conductive paste. Item 5. The IC card according to any one of Items 1 to 4.