WO2013157191A1

WO2013157191A1 - Coil device and mobile wireless terminal

Info

Publication number: WO2013157191A1
Application number: PCT/JP2013/001619
Authority: WO
Inventors: 貴紀廣部; 佐藤　浩; 小柳　芳雄; 上島　博幸
Original assignee: パナソニック株式会社
Priority date: 2012-04-17
Filing date: 2013-03-12
Publication date: 2013-10-24

Abstract

The device is provided with: a first loop coil (2) operating in a first frequency band (f1); and a second loop coil (4) operating in a second frequency band (f2); the first loop coil (2) being electrically connected to an impedance adjustment circuit (3), and the impedance adjustment circuit (3) being configured to have lower impedance in the second frequency band (f2) than in the a first frequency band (f1), for the first loop coil (2). Thus, when the second loop coil (4) is used, degradation in coupling with respect to the first loop coil (2) is reduced, and degradation in performance of the second loop coil (4) can be kept to a minimum.

Description

Coil device and portable radio terminal

The present invention relates to a coil device used for non-contact charging and a portable wireless terminal equipped with the coil device.

In recent years, portable wireless terminals that can be charged in a contactless manner have been distributed in the market, and in particular, a power transmission coil integrated with a battery pack has become the mainstream.

Examples of technologies related to non-contact charging include those described in Patent Documents 1 to 3. The non-contact IC card system described in Patent Document 1 has a non-contact IC card function and a reader / writer function, and a portable electronic device including an IC card circuit and a reader / writer circuit corresponding to each function, In a non-contact IC card system in which a loop antenna for an IC card circuit and a loop antenna for a reader / writer circuit can be electromagnetically coupled, the loop between the IC card circuit loop antenna and the IC card circuit and the loop for the reader / writer circuit A switch is provided between the antenna and the reader / writer circuit, and both switches are configured such that when one switch is closed, the other switch is opened.

The wireless card described in Patent Document 2 is a wireless card that respectively receives a power wave of a first frequency transmitted from an external communication device and a data wave of a second frequency different from the first frequency. The first coil forming the power wave antenna for receiving the power wave is disposed at the center of one surface of the rectangular card-like substrate formed of a member that transmits the radio wave, and the data wave is transmitted. A second coil forming a data wave antenna to be received was disposed so as to form a double ring with the first coil at the center of one surface of the substrate.

A wireless device including a plurality of antennas described in Patent Document 3 includes a plurality of antennas, and in the wireless device that selects and connects these antennas to a wireless circuit, a voltage of a standing wave of each antenna is applied to each antenna. Switch means capable of grounding the maximum distribution point is provided, and among these switch means, means for operating the switch means of the unselected antenna to perform grounding is provided.

Japanese Unexamined Patent Publication No. 2004-342040 Japanese Unexamined Patent Publication No. 2004-110854 Japanese Laid-Open Patent Publication No. 7-29749

However, the techniques described in the above-described prior art documents have the following problems.
In the non-contact IC card system described in Patent Document 1, since current does not flow simultaneously in both the IC card circuit and the reader / writer circuit, an increase in power consumption can be suppressed. Since a switch is required, the apparatus becomes larger and the cost increases.

In the wireless card described in Patent Document 2, since the power wave coil and the data wave coil are arranged in a double ring, the coupling deterioration of both coils occurs.

In the wireless device including a plurality of antennas described in Patent Document 3, mutual coupling is reduced by terminating other antennas when any one of the plurality of antennas is selected. As a countermeasure, a plurality of switches are required, and control for switching the switches is required, which increases the size of the apparatus and increases the cost.

The present invention has been made in view of such circumstances, and a coil device and a portable radio that can suppress the deterioration of coupling between two coils for power transmission and communication and can reduce the size of the device. The purpose is to provide a terminal.

The coil device of the present invention includes a first loop coil that operates in a first frequency band, and a second loop coil that operates in a second frequency band, and the first loop coil has an impedance adjustment. Electrically connected to a circuit, the second loop coil is electrically connected to an input / output unit, and the impedance adjusting circuit is connected to the first loop coil than the first frequency band. In the second frequency band, the impedance is low.

According to the above configuration, the impedance adjustment circuit adjusts the impedance of the terminal end of the first loop coil to be lower in the second frequency band than in the first frequency band. When used, the deterioration of the coupling with the first loop coil is reduced, the performance deterioration of the second loop coil can be kept low, and the communication performance of the second loop coil can be improved.

In the above configuration, the first loop coil and the second loop coil are concentrically arranged.

According to the above configuration, by arranging the first loop coil and the second loop coil concentrically, the range through which the magnetic flux passes can be shared, so that the apparatus can be miniaturized.

In the above configuration, the second frequency band is higher than the first frequency band.

According to the above configuration, when the second frequency band is higher than the first frequency band, when the second loop coil operating in the second frequency band is in an operating state, the termination condition of the first loop coil is By making the impedance low in the second frequency band, it is possible to suppress the performance deterioration of the second loop coil.

In the above configuration, the impedance adjustment circuit has an impedance in the second frequency band of 1 kΩ or less.

In the above configuration, the impedance adjustment circuit has an input impedance in the second frequency band of 200Ω or less.

The portable wireless terminal of the present invention includes the coil device.

According to the above configuration, a portable wireless terminal with good communication performance can be realized by using the second loop coil for wireless communication of a wireless communication standard such as Felica (registered trademark) or NFC (Near Field Communication). Further, since the coil device can be miniaturized, the portable radio terminal can be miniaturized.

According to the present invention, in a coil device provided with two coils for power transmission and communication, it is possible to keep the coupling deterioration of the two coils low and to reduce the size of the device.

1A and 1B are views showing a coil device according to an embodiment of the present invention, where FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along line A-A ′ in FIG. The figure which shows the impedance adjustment circuit of the high pass filter structure used for the coil apparatus of FIG. The figure which shows the impedance characteristic of the impedance adjustment circuit of a high pass filter structure shown in FIG. The figure which shows the impedance adjustment circuit of the band pass filter structure used for the coil apparatus of FIG. The figure which shows the impedance characteristic of the impedance adjustment circuit of a band pass filter structure shown in FIG. It is a figure which shows the specific example of the coil module of the coil apparatus of FIG. 1, (a) is a top view, (b) is the sectional view on the A-A 'line of (a). The top view which shows the 1st loop coil and 1st magnetic body of the coil module of FIG. The top view which shows the 2nd loop coil and 2nd magnetic body of the coil module of FIG. (A), (b) Smith chart showing impedance characteristics of second loop coil of coil module of FIG. The figure which shows the communication distance measurement result at the time of using RC-S461C (R / W: Reader / writer by Sony Corporation) as a coil module of FIG. The figure which showed the impedance characteristic of the 2nd loop coil of the coil module of FIG. 6 with the graph The block diagram which shows schematic structure of a part of portable radio | wireless terminal using the coil apparatus of FIG.

Hereinafter, preferred embodiments for carrying out the present invention will be described in detail with reference to the drawings.

1A and 1B are diagrams showing a coil device according to an embodiment of the present invention, in which FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along line A-A ′ in FIG. In the figure, a coil device 1 according to the present embodiment includes a first loop coil 2 that operates in a first frequency band f1, and an impedance adjustment circuit 3 that is electrically connected to the first loop coil 2. A second loop coil 4 operating in a second frequency band f2 (f2> f1) higher than the first frequency band f1, and an input / output unit 5 electrically connected to the second loop coil 4. And a magnetic body 6 on which the first loop coil 2 and the second loop coil 4 are mounted. The first loop coil 2, the second loop coil 4, and the magnetic body 6 except for the impedance adjustment circuit 3 and the input / output unit 5 of the coil device 1 constitute a coil module 7.

The magnetic body 6 is formed in a square plate shape, and the first loop coil 2 and the second loop coil 4 are mounted on one surface thereof. The first loop coil 2 is used for power transmission for charging, and the second loop coil 4 is used for wireless communication such as Felica (registered trademark) and NFC. The first loop coil 2 and the second loop coil 4 are both formed in a circular spiral shape, and the size of the second loop coil 4 is larger than that of the first loop coil 2. The loop coil 2 is disposed inside the second loop coil 4. That is, the first loop coil 2 and the second loop coil 4 are concentrically arranged on the same plane. By arranging in this way, the range through which the magnetic flux passes can be shared, and the apparatus can be miniaturized. Note that the first loop coil 2 and the second loop coil 4 are not necessarily arranged concentrically, and may be eccentric.

When the second loop coil 4 operates in the second frequency band f2, the impedance adjustment circuit 3 determines the termination condition of the first loop coil 2 operating in the first frequency band f1 as the second frequency band. This is a low impedance for f2. In this case, the impedance in the second frequency band of the impedance adjustment circuit 3 may be 1 kΩ or less, but is preferably 200Ω or less. By having the impedance adjustment circuit 3, the coupling between the second loop coil 4 and the first loop coil 2 is weakened, and the performance degradation of the second loop coil 4 can be suppressed to a low level. Specific examples of the configuration of the impedance adjustment circuit 3 include a high-pass filter configuration and a band-pass filter configuration.

FIG. 2 is a circuit diagram showing the impedance adjustment circuit 3 having a high-pass filter configuration. The circuit configuration has a low impedance between the terminals P1 and P2 connected to the first loop coil 2. The terminals P3-P4 are connected to the charging circuit unit side (see FIG. 12). FIG. 3 is a diagram showing impedance characteristics of the impedance adjustment circuit 3 having the high-pass filter configuration shown in FIG. As shown in the figure, the impedance is low in the second frequency band f2. The first frequency band f1 is, for example, 100 kHz, and the second frequency band f2 is, for example, 13.56 MHz.

FIG. 4 is a circuit diagram showing an impedance adjustment circuit 3 having a band-pass filter configuration. The circuit configuration has a low impedance between the terminals P1 and P2 connected to the first loop coil 2. The terminals P3-P4 are connected to the charging circuit unit side (see FIG. 12). FIG. 5 is a diagram showing impedance characteristics of the impedance adjustment circuit 3 having the bandpass filter configuration shown in FIG. As shown in the figure, the impedance is low in the second frequency band f2.

Here, the result of verifying the effect of the present invention will be described. 6A and 6B are diagrams showing a specific example of the coil module of the coil device 1 shown in FIGS. 1A and 1B. FIG. 6A is a plan view, and FIG. 6B is an AA ′ line in FIG. It is line sectional drawing. 7 is a plan view showing the first loop coil and the first magnetic body of the coil module shown in FIGS. 6A and 6B, and FIG. 8 is the coil shown in FIGS. 6A and 6B. It is a top view which shows the 2nd loop coil and 2nd magnetic body of a module. The coil module of this specific example has a shape different from that of the coil module 7 of FIGS. 1 (a) and 1 (b), but is common to the coil module 7 of FIGS. 1 (a) and 1 (b). Parts are given the same reference numerals.

As shown in FIGS. 6A and 6B, in the coil module 7 of the specific example, the first loop coil 2 is mounted on one surface of the first magnetic body 10 formed in a rectangular shape. The second loop coil 4 is mounted on one surface of the second magnetic body 11 formed in a rectangular ring shape. Both the first loop coil 2 and the second loop coil 4 are formed in a rectangular shape. The first loop coil 2 is disposed inside the second loop coil 4. On the surface of the second magnetic body 11 on the side where the second loop coil 4 is mounted, a rectangular loop is formed so as to sandwich the second loop coil 4 with the second magnetic body 11. A substrate 13 is disposed.

Terminals

2 a and 2 b are formed at both ends of the first loop coil 2, and

terminals

4 a and 4 b are formed at both ends of the second loop coil 4.

As shown in FIG. 7, the first loop coil 2 has a longitudinal dimension of 35 mm, a transverse dimension of 28 mm, the first magnetic body 10 has a longitudinal dimension of 45 mm, and a transverse dimension of 33 mm. It has become. Moreover, as shown in FIG. 8, the dimension of the longitudinal direction of the 2nd magnetic body 11 is 52 mm, and the dimension of a transversal direction is 45 mm. In addition, the dimension in the longitudinal direction of the space formed by the second magnetic body 11 is 46 mm, and the dimension in the lateral direction is 38 mm. Note that the dimensions of the second loop coil 4 are substantially the same as the dimensions of the second magnetic body 11 and are therefore omitted.

FIG. 9 is a Smith chart showing the impedance characteristics of the second loop coil 4 of the coil module 7. (A) of the figure shows the case where the first loop coil 2 side is opened as the condition (1) (that is, the impedance becomes high). As can be seen from the characteristics of the portion indicated by reference numeral 40 in the figure, unnecessary resonance occurs due to the influence of the first loop coil 2. Further, the inductance value of the second loop coil 4 at this time is 0.624 μH. On the other hand, (b) of the figure shows a case where the first loop coil 2 side is short-circuited (that is, the impedance is lowered) as the condition (2). As can be seen from the figure, unnecessary resonance does not occur because the first loop coil 2 is hardly affected. At this time, the inductance value of the second loop coil 4 is 0.837 μH. When the first loop coil 2 side is opened, the inductance value of the second loop coil 4 decreases due to the influence of the first loop coil 2. By providing the impedance adjustment circuit 3 in which the impedance is lowered in the second frequency band f2 that is the operating frequency band of the second loop coil 4, the second loop coil 4 becomes less susceptible to the influence of the first loop coil 2. This prevents a decrease in inductance value.

FIG. 10 is a diagram showing a communication distance measurement result when RC-S461C (R / W: reader / writer manufactured by Sony Corporation) is used as the coil module 7 of FIGS. 6 (a) and 6 (b). . In the case of the above condition (1), the resonance frequency was 13.55 MHz and the communication distance was 108 mm. In the case of condition (2), the resonance frequency was 13.52 MHz and the communication distance was 136 mm. Obviously, in the case of the condition (2) (that is, when the first loop coil 2 side is short-circuited), the communication distance is long. Needless to say, a longer communication distance is better.

FIG. 11 is a graph showing impedance characteristics of the second loop coil 4 of the coil module 7 of FIGS. 6 (a) and 6 (b). The horizontal axis represents the termination resistance (Ω), and the vertical axis represents the inductance value (nH). As can be seen from the figure, the inductance value is higher when the impedance is lower. That is, the inductance value of the second loop coil 4 increases as the impedance value of the first loop coil 2 decreases.

FIG. 12 is a block diagram showing a schematic configuration of a part of a portable radio terminal using the coil device 1 described above. In addition to the coil device 1, the portable wireless terminal 20 shown in FIG. 1 includes a charging circuit unit 21, an external wireless circuit 22, a Felica circuit control CPU (Central Processing Unit) 23, and a battery 24. The charging circuit unit 21 includes a rectifier circuit 210, a load modulation circuit 211, and a charging circuit control CPU (Central Processing Unit) 212. The rectifier circuit 210 and the load modulation circuit 211 perform wireless power transmission with the first loop coil 2. The external radio circuit 22 performs radio transmission as Felica (registered trademark) or NFC communication. The charging circuit control CPU 212 controls the rectifier circuit 210 and the load modulation circuit 211. The Felica circuit control CPU 23 controls the external radio circuit 22.

Thus, according to the coil device 1 according to the present embodiment, the first loop coil 2 that operates in the first frequency band f1 and the second loop that operates in the second frequency band f2 (> f1). The first loop coil 2 is electrically connected to the impedance adjustment circuit 3, the second loop coil 4 is electrically connected to the input / output unit 5, and the impedance adjustment circuit 3 is Since the first loop coil 2 is configured to have a lower impedance in the second frequency band f2 than in the first frequency band f1, the first loop is obtained when the second loop coil 4 is used. The deterioration of the coupling with the coil 2 is reduced, the performance deterioration of the second loop coil 4 can be kept low, and the communication performance of the second loop coil 4 can be improved.

In addition, since the first loop coil 2 and the second loop coil 4 are arranged concentrically and on the same plane, the range through which the magnetic flux passes can be shared by the first and second loop coils 2, 4. 1 can be miniaturized.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.

This application is based on a Japanese patent application filed on April 17, 2012 (Japanese Patent Application No. 2012-094100), the contents of which are incorporated herein by reference.

INDUSTRIAL APPLICABILITY The present invention has an effect that in a coil device including two coils for power transmission and communication, the deterioration of coupling between the two coils can be suppressed to a low level, and the size can be reduced. And can be applied to portable wireless terminals such as smartphones.

DESCRIPTION OF SYMBOLS 1 Coil apparatus 2 1st loop coil 3 Impedance adjustment circuit 4 2nd loop coil 5 Input / output part 6 Magnetic body 7 Coil module 10 1st magnetic body 11 2nd magnetic body 13 Board | substrate 20 Portable wireless terminal 21 Charging circuit Unit 22 External radio circuit 23 CPU for Felica circuit control
24 battery 210 rectifier circuit 211 load modulation circuit 212 CPU for charging circuit control

Claims

A first loop coil operating in a first frequency band;
A second loop coil operating in a second frequency band,
The first loop coil is electrically connected to an impedance adjustment circuit;
The second loop coil is electrically connected to the input / output unit;
The coil device, wherein the impedance adjustment circuit is configured to have a lower impedance in the second frequency band than in the first frequency band for the first loop coil.
The coil device according to claim 1,
The coil device, wherein the first loop coil and the second loop coil are arranged concentrically.
The coil device according to claim 1 or 2,
The coil device, wherein the second frequency band is higher than the first frequency band.
The coil device according to any one of claims 1 to 3,
The coil device, wherein the impedance adjustment circuit has an impedance in the second frequency band of 1 kΩ or less.
The coil device according to any one of claims 1 to 4,
A coil device, wherein an input impedance of the impedance adjustment circuit in the second frequency band is 200Ω or less.
A portable wireless terminal comprising the coil device according to any one of claims 1 to 5.