JPH11272826A - Radio receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of an antenna even at the time of receiving power feeding from the antenna and to increase a communicable distance by specifying a coil interval of a loop antenna and connecting coils nondensely in an IC card, etc. SOLUTION: In a loop antenna 14 which manages communication with a reader/writer, coils L1 to L3 are helically formed and the coil L1 of the outermost periphery among them is formed on an IC card 12 in an allowable maximum size. One end of the coil L2 which is separated only by an isolation distance D and is formed in a small size is connected to one end of the coil L1 and further, one end of the coil L3 which is separated by the distance D and is formed in a small size is connected to the other end of the coil L2. Here, the distance D is made 0.8 times as wide as the coil wire or more, connection of the coils is made nondensely and the increase of self-inductance is kept in a practically sufficient range. Thus, even if power for an operation is generated from the antenna 14, it is possible to increase the efficiency of the antenna.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio receiver, and can be applied to, for example, an IC card. The present invention improves the efficiency of the antenna even in a configuration in which power is supplied from the antenna by forming a loop antenna with a plurality of windings by loosening the coupling of each winding, thereby improving the communication distance. Can be increased.

[0002]

2. Description of the Related Art Conventionally, an IC card system using an IC card has been applied to a ticket gate system for transportation, a room entrance / exit management system, and the like.
Such an IC card system is composed of an IC card carried by a user and a reader / writer (that is, an IC card processing device) for transmitting / receiving various data to / from these IC cards. There has been proposed one in which various data are transmitted and received between writers without contact.

That is, in this type of IC card system, a read writer modulates a carrier of a predetermined frequency with a desired data sequence to generate a transmission signal, and sends the transmission signal to the IC card via an antenna.

[0004] The IC card receives the transmission signal via the antenna and demodulates the data transmitted from the reader / writer based on the transmission signal. Further, in accordance with the received data, the IC card modulates data such as personal information held therein by a predetermined carrier wave and sends the modulated data to a reader / writer.

[0005] The read writer receives data sent from the IC card, and based on the received data, opens and closes the door of the ticket gate, and permits entry and exit of the room.

Some of such IC cards are operated by the power received by the antenna. In such an IC card, there is no need to incorporate a battery, so that the usability is improved. Can be.

[0007]

By the way, in the IC card which operates by the power received by the antenna, the communicable distance can be increased by increasing the efficiency of the antenna.

As a method of increasing the efficiency of the antenna, a method of forming an antenna by a loop and increasing the number of windings of the loop antenna can be considered. That is, if the number of windings of the antenna is increased, the number of interlinkage magnetic fluxes of the antenna can be increased accordingly, and the efficiency of the antenna can be increased.

However, when the number of windings is simply increased, the self-inductance of the loop antenna rapidly increases due to coupling between the windings. As a result, in the case of an IC card that operates using the power received by the antenna, when the number of windings is increased, power cannot be efficiently obtained through the antenna.

FIG. 8 is a connection diagram showing an equalizing circuit of a power transmission system in this type of IC card system. In the IC card system 1, the read writer 2 can represent a signal processing circuit for supplying power to the antenna with the signal source 3, and an antenna receiving power supply from the signal source 3 with the coil 4 having a self-inductance L1. . In the IC card 5, the antenna can be represented by the coil 6 having the self-inductance L2, and the internal resistance of the antenna can be represented by the resistor R2. Further, the capacitance component connected to the antenna can be represented by the capacitor C, and the load circuit can be represented by the resistor R.

In the IC card system 1, it can be modeled that the antenna on the side of the reader / writer 2 and the antenna on the side of the IC card 5 are magnetically coupled to transmit and receive electric power. L1 and L
Assuming that the mutual inductance between the two coils 4 and 6 is M, the whole can be modeled.

In such a model, the transmission signal S1
Is set to V1, and the current of coils 4 and 6 is set to I
1 and I2, a potential difference V2 between both ends of the resistor R as a load.
Can be expressed by the following equation. Here, ω is the angular frequency of the carrier in the transmission signal S1.

[0013]

(Equation 1)

[0014]

(Equation 2)

Here, in the IC card 5, the value of the capacitor C is set so as to resonate with the transmission signal S1 transmitted from the signal source 3, so that power can be transmitted and received efficiently. From, the resistance R2 = 0
By modifying the equations (1) and (2) under the condition of the resonance, the following relational expression can be obtained.

[0016]

(Equation 3)

[0017] Here, if is sufficiently large distance leads writer 2 and the IC card 5, since it can be expressed as L1L2 >> M ^2, to obtain a (3) by transforming the expression, the following relational expression Thus, when the current I2 flows out of the coil 6 serving as an antenna, it can be understood that power can be supplied efficiently if the self-inductances L1 and L2 are reduced and the mutual inductance M is increased.

[0018]

(Equation 4)

On the other hand, when the number of windings is simply increased in the loop antenna, the self inductance L2 becomes
It changes in proportion to the square of the number of turns, and the mutual inductance M
Changes in proportion to the number of windings. Thus, when power is supplied from the antenna, it is understood that the efficiency of the antenna cannot be improved merely by increasing the number of windings of the loop antenna.

The present invention has been made in view of the above points. Even in a configuration in which power is supplied from an antenna,
An object of the present invention is to propose a wireless receiving device capable of improving the antenna efficiency and increasing the communicable distance.

[0021]

According to the present invention, in order to solve the above-mentioned problems, the present invention is applied to a radio receiving apparatus which operates by power received via an antenna and processes a signal received via the antenna. This antenna is constituted by a loop-shaped antenna wound spirally on substantially the same plane, and in this antenna, adjacent windings are separated by at least 0.8 times the width of the wire of the winding. .

Similarly, in the antenna, the width of the winding is set to be at least 35 times the thickness of the wire of the winding.

Further, on a substantially same plane, a loop-shaped antenna is formed by at least a first winding and a second winding having one end connected to the first winding. In the second winding, the wire is arranged in a meandering direction in the inner and outer circumferences of the winding in a direction opposite to the meandering in the first winding. .

In the antenna, if the interval between adjacent windings is set to be 0.8 times or more the width of the wire of the windings, the coupling between the windings is reduced, and the self-inductance with respect to the number of windings is reduced. Therefore, even in a configuration in which power is supplied from the antenna, the number of windings can be increased and the efficiency of the antenna can be increased.

The width of the winding is 35 times the thickness of the winding wire.
Even if it is more than twice, loosen the coupling between the windings,
The increase in self-inductance with respect to the number of windings can be reduced, so that even in a configuration where power is supplied from the antenna, the number of windings can be increased to increase the efficiency of the antenna.

Further, in the first winding, the wire is arranged in a meandering manner in the inner and outer circumferential directions of the winding, and in the second winding, the inner and outer windings are wound in a direction opposite to the meandering in the first winding. If the wires are arranged in a meandering direction in the circumferential direction, the first and second windings are opposite to the first and second windings at a portion where the first and second windings overlap and intersect or where each winding is displaced inward and outward. Current will flow in the direction. The portion where the current flows in the opposite direction can reduce the coupling coefficient between the first and second windings, thereby reducing the coupling between the windings and reducing the increase in self-inductance with respect to the number of windings. Therefore, even in a configuration in which power is supplied from the antenna, the number of windings can be increased and the efficiency of the antenna can be increased.

[0027]

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

(1) First Embodiment FIG. 2 is a block diagram showing an IC card system according to a first embodiment of the present invention. This IC card system 11 is applied to, for example, a ticket gate system for transportation,
Data is exchanged between the IC card 12 and the reader / writer 13.

Here, the IC card 12 is formed in a card shape by laminating a substrate on which an integrated circuit is mounted and a protective sheet. In the IC card 12, the loop antenna 14 is formed by the wiring pattern on the substrate. The modulation and demodulation circuit 15 and the signal processing circuit 16 are formed by the integrated circuit mounted on the substrate.

Here, the loop antenna 14 is coupled to the loop antenna 18 of the reader / writer 13, receives the transmission signal transmitted from the loop antenna 18, and
The response signal generated by the modulation / demodulation circuit 15 is emitted.

The modulation / demodulation circuit 15 generates power, a clock and the like necessary for the operation of the IC card 12 from the transmission signal received by the loop antenna 14. Further, a modulation / demodulation circuit 1
5 operates with the power and the clock, demodulates a data sequence (hereinafter referred to as a transmission data sequence) D (R → C) transmitted from the reader / writer 13 from the transmission signal, and outputs it to the signal processing circuit 16. In addition, a response signal is generated from a data sequence (hereinafter referred to as a response data sequence) D (C → R) which is prompted by the transmission data sequence D (R → C) to be input from the signal processing circuit 16 and which responds. Loop antenna 1 by signal
4 to emit a response signal.

The signal processing circuit 16 operates on the power and clock generated by the modulation / demodulation circuit 15 to generate the transmission data stream D.
(R → C) is analyzed, and the response data sequence D (C
→ R) is output to the modulation / demodulation circuit 15.

In the lead writer 13, the modulation / demodulation circuit 1
9 generates a transmission signal from a transmission data sequence D (R → C) input from an SPU (Signal Processing Unit) 20, and drives the loop antenna 18 with this transmission signal. The modulation / demodulation circuit 19 performs signal processing on the response signal received by the loop antenna 18 to demodulate the response data sequence D (C → R) sent from the IC card 12, and this response data sequence D (C → R) R) to the SPU 20.

The SPU 20 is composed of an arithmetic processing unit that executes a relatively simple processing procedure.
2 transmits and receives the transmission data sequence D (R → C) to the modulation / demodulation circuit 1
9 and processes the response data sequence D (C → R) input from the modulation / demodulation circuit 19. In this processing, the SPU 20 displays the processing progress and the processing result on the display unit 21 as necessary. The operation is switched by a command from the input unit 22, and data such as a processing procedure is input / output to / from the external device 23 as necessary.

FIG. 1 is a perspective view showing the loop antenna 14 of the IC card 12 in detail. The loop antenna 14 is 77.5 [m
m] x 46 [mm], thickness 20 stuck on a substrate
It is prepared by etching a [μm] copper foil. The loop antenna 14 includes first to third windings L1, L2, L3 sequentially formed on the same plane formed on the substrate from the outer peripheral side.
Are formed in a spiral shape.

Here, the outermost first winding L1 is formed 5 mm inside the outermost periphery of the substrate. Here, the dimension of 5 [mm] is a size necessary for bonding members such as a protective sheet with sufficient strength. Thus, the outermost first winding L <b> 1 is formed to have a maximum allowable size in the IC card 12.

Here, each of the first to third windings L1, L2, L
Nos. 3 are formed with a pattern width of 0.5 [mm]. The first winding L2 is arranged such that an insulation distance D between the second winding L2 and the pattern formed by the first winding L1 is 2 mm, which is four times the width of the winding L1. It is formed small inside L1. Further, the insulation distance D between the third winding L3 and the pattern formed by the second winding L2 is 2 [mm].
Is formed inside this second winding L2 in a small size. Here, the insulation distance D is a distance between adjacent windings, and is a distance from the inner edge of the outer winding to the outer edge of the inner winding.

In the above configuration, in the IC card system 11 (FIG. 2), the read writer 13 modulates the transmission data string D (R → C) at a predetermined frequency to generate a transmission signal, and this transmission signal is looped. It is transmitted from the antenna 18. When a transmission signal is induced in the loop antenna 14 by approaching the reader / writer 13, the IC card 12 starts operating by the power of the induced transmission signal, and transmits a transmission data sequence D transmitted by the transmission signal.
(R → C) is received. Further, this transmission data sequence D
A response signal is generated by a response data sequence D (C → R) corresponding to (R → C), and this response signal is
4 to the read / writer 13.

As described above, in the loop antenna 14 which controls communication with the lead writer 13 (FIG. 1), the loop antenna 14 is formed spirally by the first to third windings L1 to L3 having a thickness of 20 μm. And the outermost first winding L1
Are formed in the IC card 12 at the maximum size that can be tolerated. Further, one end of the first winding L1 is connected to one end of a second winding L2, which is formed to be smaller than the first winding L1 by an insulation distance D and is formed in a small size. The other end of the line L2 is connected to one end of a small third winding L3 which is separated from the second winding L2 by an insulation distance D, thereby connecting the first to third windings. In this case, the mutual coupling is reduced, the increase in the self-inductance is reduced, and the loop antenna 18 on the
And the mutual inductance between them is increased. Therefore, when power for operation is generated from the loop antenna 14 as in this embodiment, the efficiency of the loop antenna 14 is increased and the communication distance is extended accordingly.

FIG. 3 is a characteristic curve diagram obtained by measuring the change in the self-inductance by variously changing the insulation distance D, which is the interval between the windings. In this measurement, the pattern thickness was 20 μm, the pattern width was 0.5 mm,
The self-inductance was measured with three windings. According to the measurement results, it was confirmed that the increase in self-inductance can be reduced to a practically sufficient level by setting the insulation distance D to 0.4 [mm] or more.

This was examined in relation to the width of the wire of the winding.
It was confirmed that if the windings were formed at least eight times apart, the increase in self-inductance could be reduced to a practically sufficient degree.

With respect to such a characteristic of self-inductance, in the IC card 12, the outermost first winding L
1 are formed in the maximum size that can be tolerated in the IC card 12, and are further separated from each other by an insulation distance D in order.
Since the third windings L2 and L3 are formed, the number of interlinkage magnetic fluxes of the windings L1 to L3 is also sufficiently ensured, so that the communication distance can be increased.

According to the above configuration, three windings L1 to L3 are sequentially formed inward by 2 mm, which is four times the width of each winding L1 to L3, to form three windings L1 to L3. By securing D at least 0.8 times the width of the wire material of the winding, the coupling of each winding is reduced, and the increase in self-inductance in the loop antenna is kept within a practically sufficient range. Mutual inductance with the antenna 18 can be increased. Therefore, even when power for operation is generated from the loop antenna 14, the efficiency of the loop antenna 14 can be increased and the communication distance can be increased.

(2) Second Embodiment FIG. 4 in comparison with FIG. 1 is a perspective view showing an IC card applied to an IC card system according to a second embodiment of the present invention.

In this IC card 32, similarly to the IC card 12 described above with reference to FIG.
m] is etched to form the loop antenna 34 by the first to third windings. Here, the loop antenna 34 has an insulation distance D1 between the windings of 0.15
[Mm], and the width W of the pattern is set to 2.7 [mm] which is 135 times the thickness of the pattern.

FIG. 5 is a characteristic curve diagram showing the relationship between the pattern width W and the self-inductance. In this measurement, the pattern thickness was 20 [μm], and the insulation distance was 0.15.
[Mm], the self-inductance was measured using three windings. According to this measurement result, the width W of the pattern was about 0.7
[Mm] or more, it was confirmed that the increase in self-inductance can be reduced to a practically sufficient degree.

When this was examined in relation to the thickness of the winding, it was found that if the pattern width was set to be at least 35 times the thickness of the wire material of the winding, the increase in self-inductance could be reduced to a practically sufficient level. Was confirmed.

According to the structure shown in FIG.
Is set to 2.7 [mm], and the pattern width is set to be 35 times or more the thickness of the wire material of the winding, so that the coupling of each winding is reduced and the self-inductance in the loop antenna can be increased practically. Keep it in a sufficient range
Mutual inductance with the loop antenna 18 on the third side can be increased. Therefore, even when power for operation is generated from the loop antenna 34, the efficiency of the loop antenna 34 can be increased and the communication distance can be increased.

(3) Third Embodiment FIG. 6, which is a comparison with FIG. 1, is a perspective view showing an IC card applied to an IC card system according to a third embodiment of the present invention.

In this IC card 42, similarly to the IC card 12 described above with reference to FIG.
m] is etched to form the loop antenna 44 by the first to third windings. Here, the loop antenna 44 has an insulation distance D1 between the windings of 2 [m
m], and the width W of the pattern is set to 2.7 [mm].

According to the configuration shown in FIG. 6, each of the windings L1 to L
The three windings L1 to L3 are sequentially formed inward by 2 [mm], which is 0.8 times or more the width of 3, and the width W of the pattern of each winding is determined by the thickness of the wire material of the winding. By setting the value to 2.7 [mm], which is 35 times or more, the increase in self-inductance in the loop antenna is further reduced and the mutual inductance between the loop antenna 18 is further increased as compared with the above-described embodiment. Accordingly, the efficiency of the loop antenna 34 can be increased and the communication distance can be increased.

(4) Fourth Embodiment FIG. 7 in comparison with FIG. 1 is a perspective view showing an IC card applied to an IC card system according to a fourth embodiment of the present invention.

In this IC card 52, the first and second windings L1A and L1B are formed on both sides of the substrate by etching the copper foil adhered to both sides of the substrate.
The loop antenna 54 is formed by connecting the first and second windings L1A and L1B.

Here, each winding L1A and L1B is connected to this I
It is created with the maximum size allowable in the C card 52. Further, the first winding L1A is formed such that the pattern is shifted at a predetermined period on the inner peripheral side and the outer peripheral side, so that the first winding L1A meanders at a predetermined period when viewed along the outer periphery of the IC card 52. You.

The second winding L1B is formed with a pattern shifted to the opposite side of the first winding L1A at the same period as the first winding L1A, thereby forming the outer periphery of the IC card 52. When viewed along, the first winding L1A overlaps with a portion A1 meandering at a predetermined cycle and displacing inward and outward.

As a result, in the overlapping portion A1, current flows in the windings L1A and L1B in opposite directions, and the coupling coefficient between the first and second windings L1A and L1B is reduced. Accordingly, the loop antenna 54 can reduce the coupling between the windings and reduce the increase in the self-inductance with respect to the number of windings. Even in a configuration where power is supplied from the antenna, the number of windings is increased. It has been made possible to increase the efficiency of the antenna.

According to the configuration shown in FIG. 7, in the first and second windings formed on substantially the same plane, the wire is arranged in a meandering manner in the inner and outer circumferential directions of the winding, and the meandering direction is reversed at this time. By setting the direction, the coupling between the windings can be reduced, the increase in self-inductance with respect to the number of windings can be reduced, and even in a configuration where power is supplied from the antenna, the number of windings can be reduced. This can increase the efficiency of the antenna.

(5) Other Embodiments In the first to third embodiments, the case where the number of windings is set to three has been described. However, the present invention is not limited to this, Therefore, the present invention can be widely applied to the case where various numbers of windings are used.

In the above-described fourth embodiment,
Although the case where the number of windings is set to two has been described, the present invention is not limited to this, and can be widely applied to the case where various numbers of windings are used as necessary.

In the first to fourth embodiments described above, the case where the loop antenna is formed by etching the copper foil has been described. However, the present invention is not limited to this. In the case where a loop antenna is formed by the method described above, the present invention can be widely applied to a case where a loop antenna is formed by winding a magnet wire.

Further, in the above-described fourth embodiment, the case where the winding is meandering by shifting the pattern at a predetermined period has been described. However, the present invention is not limited to this, and the winding may meander in a sinusoidal shape. Good.

Further, in the above-described embodiment, the case where the present invention is applied to an IC card has been described. However, the present invention is not limited to this and can be widely applied to various wireless receiving devices.

[0063]

As described above, according to the present invention, the coupling between the windings is reduced and the loop antenna is formed by a plurality of windings. And the communication distance can be increased.

[Brief description of the drawings]

FIG. 1 is a perspective view showing in detail a loop antenna of an IC card applied to an IC card system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing an IC card system according to the first embodiment.

FIG. 3 is a characteristic curve diagram showing a relationship between an insulation distance and a self-inductance.

FIG. 4 is a perspective view showing in detail a loop antenna of an IC card applied to an IC card system according to a second embodiment of the present invention.

FIG. 5 is a characteristic curve diagram showing a relationship between a pattern width and a self-inductance.

FIG. 6 is a perspective view showing in detail a loop antenna of an IC card applied to an IC card system according to a third embodiment of the present invention.

FIG. 7 is a perspective view showing in detail a loop antenna of an IC card applied to an IC card system according to a fourth embodiment of the present invention.

FIG. 8 is a connection diagram modeling a power transmission system in an IC card system.

[Explanation of symbols]

1, 11 ... IC card system, 2, 13 ... Lead writer, 5, 12, 32, 42, 52 ... IC card,
14, 34, 44, 54 ... loop antenna, L1 to L
3 ... winding

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI H04B 5/02 H04B 5/02

Claims (9)

[Claims] 1. A radio receiving apparatus which operates by power received through an antenna and processes a signal received through the antenna, wherein the antenna has a loop shape wound spirally on substantially the same plane. An antenna, wherein the adjacent windings are arranged at a distance of at least 0.8 times the width of a wire of the windings. 2. The antenna according to claim 1, wherein the antenna is formed of a conductive pattern disposed on a predetermined base material, and a width of the wire of the winding is a width of the conductive pattern. 2. The wireless receiving device according to 1. 3. The wireless receiving device according to claim 1, wherein the wireless receiving device is formed in a flat plate shape as a whole, and transmits a signal responsive to the received signal from the antenna. 4. A radio receiving apparatus which operates with power received via an antenna and processes a signal received via said antenna, wherein said antenna has a loop shape wound spirally on substantially the same plane. An antenna, wherein the width of the winding is set to be at least 35 times the thickness of the wire of the winding. 5. The antenna according to claim 1, wherein the antenna is formed of a conductive pattern disposed on a predetermined base material, and a thickness of the wire of the winding is a thickness of the conductive pattern. The wireless receiving device according to claim 4. 6. The radio receiving apparatus according to claim 4, wherein the radio receiving apparatus is formed in a flat plate shape as a whole, and transmits a signal responsive to the received signal from the antenna. 7. A radio receiving apparatus which operates by power received through an antenna and processes a signal received through the antenna, wherein the antenna is provided on at least a first winding and a substantially same plane, A loop-shaped antenna formed by a first winding and a second winding having one end connected thereto, wherein the first winding has a wire meandering in the inner and outer circumferential directions of the winding; The wireless receiving device according to claim 1, wherein the second winding is arranged in a meandering manner in a direction opposite to a meandering direction of the first winding in an inner and outer circumferential direction of the winding. 8. The wireless receiving device according to claim 7, wherein the antenna is formed by a conductive pattern disposed on a predetermined base material. 9. The radio reception apparatus according to claim 7, wherein the radio reception apparatus is formed in a flat plate shape as a whole, and transmits a signal responsive to the received signal from the antenna.