Coil, power transmission device and power receiving device, and power transmission system

Abstract

To provide a coil or the like capable of improving efficiency as wireless power transmission even when a high frequency current is used.SOLUTION: A transmission coil TC1 for non-contact power transmission includes a power transmission loop coil TL11 wound from the outer peripheral side to the inner peripheral side of the power transmission loop coil TC1, and a power transmission loop coil TL12 wound from the inner circumference side to the outer circumference side, and the overall shape of the power transmission loop coil TL11 and the power transmission loop coil TL12 in a plan view is the same quadrangle as each other. The position seen from the center of a copper thin film wire TL111 and a copper thin film wire TL112 constituting the power transmission loop coil TL11 and the position seen from the center of the copper thin film wire TL121 and the copper thin film wire TL122 constituting the power transmission loop coil TL12 match in a plan view.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention belongs to the technical field of coils, power transmission devices, power reception devices, and power transmission systems. More specifically, it belongs to the technical field of coils for non-contact power transmission, non-contact power transmission devices and power reception devices using such coils, and power transmission systems.

Background Art

[0002] In recent years, for example, electric vehicles equipped with storage batteries such as lithium-ion batteries have been increasingly popular. In such electric vehicles, since the motor is driven using the power stored in the storage battery to move, efficient charging of the storage battery is required. Therefore, as a method of charging the storage battery mounted on an electric vehicle without physically connecting a charging plug or the like, research on so-called wireless power transmission using a power reception coil and a power transmission coil that are opposed to each other with a separation therebetween has been conducted. As wireless power transmission methods, generally, there are an electric field coupling method, an electromagnetic induction method, a magnetic field resonance method, and the like. When comparing these methods from viewpoints such as the frequency of the power transmitted and received, the positional freedom in the horizontal and vertical directions, and the transmission efficiency, as a wireless power transmission method for charging the storage battery mounted on an electric vehicle, an electric field coupling method using a capacitor or a magnetic field resonance method using a coil is regarded as promising, and research and development on these are also actively carried out. As a prior art document disclosing such background art, for example, the following Patent Document 1 can be cited. In this Patent Document 1, a coil that performs power transmission by a magnetic field resonance method using a single-turn (1 turn) loop coil and a five-and-a-half-turn (5.5 turns) open coil is disclosed.

[0003] On the one hand, the frequency of the power transmitted and received by the above-mentioned wireless power transmission is predetermined by law for each device responsible for it. In the case of power transmission to the above-mentioned electric vehicle, it is a high frequency of 85 kHz. Generally here, when a high-frequency current flows through a conductor, it is known that the current density is high at the surface of the conductor and becomes lower from the surface toward its center. Also in this regard, as the frequency of the current increases, the current concentrates on the surface, and as a result, the AC resistance of the conductor increases. This phenomenon is known as the so-called "skin effect of the conductor". In the following explanation, the AC resistance of the conductor when a high-frequency current flows through the conductor is simply referred to as "impedance".

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] On the other hand, in the above-mentioned wireless power transmission (contactless power supply) for electric vehicles, it is necessary to transmit (i.e., flow through the coil) a high-output power of at least 3.7 kilowatts while using a high-frequency current (e.g., the above 85 kHz). Therefore, as a result of flowing such a high-output power (current), if the resistance of the conductor (coil) increases due to the above skin effect, the loss as a coil increases due to the generation of Joule heat, and there is a problem that the efficiency of the wireless power transmission is reduced.

[0006] Also, as an electrical phenomenon that similarly reduces the efficiency of wireless power transmission as the above skin effect, there is the so-called "proximity effect of the conductor" caused by the proximity of conductors in the winding of the coil. Therefore, it is also necessary to take measures against the increase in resistance due to this proximity effect.

[0007] Therefore, the present invention has been made in view of the above problems and requirements, and an example of the problem is to improve the efficiency as wireless power transmission even when using a high-frequency current such as 85 kilohertz, etc. An object of the present invention is to provide a coil, a non-contact power transmission device and a power reception device using the coil, and a power transmission system capable of such things.

Means for Solving the Problem

[0008] In order to solve the above problems, the invention according to claim 1 is a coil for non-contact power transmission, which is a first winding wire formed by winding a thin film conductor, and includes a plurality of first straight portions each having a linear shape, and a plurality of first curved portions that connect the first straight portions to each other and each have a curved shape, and a first winding wire composed of the plurality of first straight portions and the plurality of first curved portions; and a second winding wire formed by winding a thin film conductor, and includes a plurality of second straight portions each having a linear shape, and a plurality of second curved portions that connect the second straight portions to each other and each have a curved shape, and a second winding wire composed of the plurality of second straight portions and the plurality of second curved portions, and the second winding wire is laminated on the first winding wire with an insulating layer interposed therebetween. The overall planar shape of each of the first winding wire and the second winding wire is the same polygon as each other, and the position of at least a part of each of the first straight portions as viewed from the center of the coil and the position of at least a part of each of the second straight portions respectively corresponding to at least a part of each of the first straight portions as viewed from the center coincide with each other in plan view.

[0009] According to the invention described in claim 1, a first winding line made of a thin film conductor having a plurality of first straight portions and a plurality of first curved portions, and a plurality of second straight portions and a plurality of second curved portions, made of a thin film conductor and laminated on the first winding line with an insulating layer interposed therebetween. And the overall planar shape of each of the first winding line and the second winding line is a polygon identical to each other, and the position of at least a part of each first straight portion as seen from the coil center and the position of at least a part of each second straight portion corresponding to at least a part of each first straight portion as seen from the coil center coincide with each other in a plan view. Therefore, it is possible to reduce the AC resistance as a coil due to the so-called skin effect or proximity effect caused by forming the winding line with a thin film conductor for weight reduction and cost reduction, and it is possible to achieve both weight reduction and cost reduction and improvement of transmission efficiency and prevention of an increase in operating temperature.

[0010] In order to solve the above problems, the invention described in claim 2 is the coil described in claim 1, wherein in the winding of the first winding line, the winding transition for one turn is performed only in one of the first curved portions included in one turn, and in the winding of the second winding line, the winding transition for one turn is performed only in one of the second curved portions included in one turn.

[0011] According to the invention described in claim 2, in addition to the operation of the invention described in claim 1, in the winding of the first winding line, the winding transition for one turn is performed only in one of the first curved portions included in one turn, and in the winding of the second winding line, the winding transition for one turn is performed only in one of the second curved portions included in one turn. Therefore, it is possible to surely make the positions of the corresponding first straight portion and the second straight portion as seen from the coil center coincide with each other in a plan view.

[0012] In order to solve the above problems, the invention described in claim 3 is the coil described in claim 2, wherein the position of the first curved portion where the winding transition is performed in the first winding line and the position of the second curved portion where the winding transition is performed in the second winding line are configured to be within the same coil region as seen from the center.

[0013] According to the invention described in claim 3, in addition to the operation of the invention described in claim 3, the position of the first curved portion where the winding transition in the first winding line occurs and the position of the second curved portion where the winding transition in the second winding line occurs are within the same region when viewed from the center of the coil. Therefore, more positions of the first straight portions and the second straight portions as viewed from the center of the coil can be made to coincide with each other in a plan view.

[0014] In order to solve the above problems, the invention described in claim 4 is the coil described in claim 1, wherein in the winding of the first winding line, the winding transition for one winding is performed only in one of the first straight portions included in one winding, and in the winding of the second winding line, the winding transition for one winding is performed only in one of the second straight portions included in one winding.

[0015] According to the invention described in claim 4, in addition to the operation of the invention described in claim 1, in the winding of the first winding line, the winding transition for one winding is performed only in one of the first straight portions included in one winding, and in the winding of the second winding line, the winding transition for one winding is performed only in one of the second straight portions included in one winding. Therefore, the positions of the corresponding first winding line and the second winding line as viewed from the center of the coil can be surely made to coincide with each other in a plan view.

[0016] In order to solve the above problems, the invention described in claim 5 is the coil described in claim 4, and is configured such that the position of each of the first curved portions as viewed from the center of the coil and the position of each of the second curved portions corresponding to each of the first curved portions as viewed from the center coincide with each other in a plan view.

[0017] According to the invention described in claim 5, in addition to the operation of the invention described in claim 4, since the positions of each first curved portion as seen from the center of the coil and the positions of each corresponding second curved portion as seen from the center of each first curved portion coincide in a plan view, the portions of the first winding line and the second winding line that coincide in position in a plan view increase, so that weight reduction and cost reduction, and improvement of transmission efficiency and prevention of an increase in operating temperature can be made more compatible.

[0018] In order to solve the above problems, the invention described in claim 6 is the coil described in any one of claims 1 to 5, wherein the first winding line is composed of two first parallel winding lines that are parallel to each other, and the second winding line is composed of two second parallel winding lines that are parallel to each other.

[0019] According to the invention described in claim 6, in addition to the operation of the invention described in any one of claims 1 to 5, since the first winding line is composed of two first parallel winding lines and the second winding line is composed of two second parallel winding lines, the AC resistance as a coil can be reduced, so that weight reduction and cost reduction, and improvement of transmission efficiency and prevention of an increase in operating temperature can be made more compatible.

[0020] In order to solve the above problems, the invention described in claim 7 is the coil described in claim 6, wherein in one turn of the first winding line, the width of the first parallel winding line on the inner peripheral side is wider than the width of the first parallel winding line on the outer peripheral side, and in one turn of the second winding line, the width of the second parallel winding line on the inner peripheral side is wider than the width of the second parallel winding line on the outer peripheral side.

[0021] According to the invention described in claim 7, in addition to the operation of the invention described in claim 6, the width of the first parallel winding line on the inner peripheral side is wider than the width of the first parallel winding line on the outer peripheral side, and the width of the second parallel winding line on the inner peripheral side is wider than the width of the second parallel winding line on the outer peripheral side. Therefore, the AC resistance as a coil can be further reduced, so that weight reduction and cost reduction, and improvement of transmission efficiency and prevention of an increase in operating temperature can be made more compatible.

[0022] In order to solve the above problems, the invention according to claim 8 is the coil according to any one of claims 1 to 7, wherein the widths of the first winding wire and the second winding wire are each configured to be wider as the winding is closer to the center.

[0023] According to the invention described in claim 8, in addition to the operation of the invention described in any one of claims 1 to 7, the widths of the first winding wire and the second winding wire are wider as the winding is closer to the center of the coil. Therefore, since the width as the winding wire is wider closer to the center of the coil where the current concentrates, the AC resistance of the coil can be further reduced.

[0024] In order to solve the above problems, the invention according to claim 9 is the coil according to any one of claims 1 to 8, wherein the innermost peripheral part of the first winding wire and the innermost peripheral part of the second winding wire are connected, and when power is transmitted, power to be transmitted is supplied to the outermost peripheral end parts of the first winding wire and the second winding wire respectively, and when power is received, the power received from each of the outermost peripheral end parts is output, and it is an adjustment winding wire for adjusting the current flowing through the first winding wire and the second winding wire, and further includes an adjustment winding wire laminated at the same position as the first winding wire and the second winding wire, and the adjustment winding wire is composed of a plurality of adjustment straight parts each having a linear shape and a plurality of adjustment curved parts connecting the adjustment straight parts and each having a curved shape, and the overall shape of the adjustment winding wire in a plan view is the same polygon as the overall shape of the first winding wire or the second winding wire in a plan view, and the position of each of the first straight parts as seen from the center of the coil and the position of each of the adjustment straight parts corresponding to each of the first straight parts as seen from the center are configured to coincide in a plan view.

[0025] According to the invention described in claim 9, in addition to the operation of the invention described in any one of claims 1 to 8, it further includes an adjustment winding line composed of a plurality of straight adjustment parts and a plurality of curved adjustment parts. The overall shape of the adjustment winding line in a plan view is the same polygon as the overall shape of the first winding line or the second winding line in a plan view. The position of each first straight part as seen from the center of the coil and the position of each corresponding adjustment straight part of each first straight part as seen from the center are the same in a plan view. Therefore, even when the adjustment winding line is provided, the AC resistance as a coil can be reduced, and both weight reduction and cost reduction, and improvement of transmission efficiency and prevention of increase in operating temperature can be achieved simultaneously.

[0026] In order to solve the above problems, the invention described in claim 10 is the coil described in claim 9, wherein a plurality of the adjustment winding lines are laminated at the same positions as the first winding line and the second winding line.

[0027] According to the invention described in claim 10, in addition to the operation of the invention described in claim 9, since a plurality of adjustment winding lines are laminated at the same positions as the first winding line and the second winding line, it is possible to effectively adjust the current flowing through the first winding line and the second winding line, and at the same time achieve both weight reduction and cost reduction, and improvement of transmission efficiency and prevention of increase in operating temperature.

[0028] In order to solve the above problems, the invention described in claim 11 is the coil described in claim 10, wherein the outermost peripheral ends of a plurality of the adjustment winding lines are connected, and capacitance means for adjusting the current is connected to the innermost peripheral part of a plurality of the adjustment winding lines, and the capacitance of the capacitance means is configured to be equal to or less than a threshold capacitance corresponding to at least the frequency of power transmission by the coil.

[0029] According to the invention described in claim 11, in addition to the operation of the invention described in claim 10, the outermost peripheral ends of a plurality of winding lines for adjustment are connected, and capacitance means for current adjustment is connected to the innermost peripheral part thereof, and since the capacitance is equal to or less than the threshold capacitance, even when capacitance means for current adjustment is provided, it is possible to achieve both weight reduction and cost reduction, and improvement of transmission efficiency and prevention of an increase in operating temperature.

[0030] In order to solve the above problems, the invention described in claim 12 is configured by a power transmission device and a power reception device separated from the power transmission device, and in the power transmission device included in a power transmission system that transmits power from the power transmission device to the power reception device in a non-contact manner, it is a power transmission coil that is the coil described in any one of claims 1 to 11, and includes a power transmission coil disposed to face the power reception device, and output means for outputting power to be transmitted to the power transmission coil.

[0031] In order to solve the above problems, the invention described in claim 13 is configured by a power transmission device and a power reception device separated from the power transmission device, and in the power reception device included in a power transmission system that transmits power from the power transmission device to the power reception device in a non-contact manner, it is a power reception coil that is the coil described in any one of claims 1 to 11, and includes a power reception coil disposed to face the power transmission device, and input means connected to the power reception coil.

[0032] In order to solve the above problems, the invention described in claim 14 includes the power transmission device described in claim 12, and a power reception device separated from the power transmission device and disposed to face the power transmission coil, the power reception device receiving the power transmitted from the power transmission device.

[0033] In order to solve the above problems, the invention described in claim 15 includes a power transmission device and the power reception device described in claim 13, the power reception device being separated from the power transmission device and the power reception coil being disposed to face the power transmission device, the power reception device receiving the power transmitted from the power transmission device.

[0034] According to the invention described in any one of claims 12 to 15, since at least one of the power transmission coil provided in the power transmission device constituting the power transmission system or the power reception coil provided in the power reception device is the coil described in any one of claims 1 to 11, when non-contact power transmission is performed with the power transmission coil or the power reception coil facing each other, the impedance as a coil due to the skin effect or proximity effect can be reduced, and both weight reduction and cost reduction, and improvement of transmission efficiency and prevention of an increase in operating temperature can be achieved simultaneously.

Effect of the Invention

[0035] According to the present invention, a first winding wire made of a thin film conductor having a plurality of first straight portions and a plurality of first curved portions, and a second winding wire made of a thin film conductor having a plurality of second straight portions and a plurality of second curved portions and laminated on the first winding wire with an insulating layer interposed therebetween are provided. The overall planar shapes of the first winding wire and the second winding wire are each a polygon that is the same as each other, and the positions of at least a part of each first straight portion as seen from the coil center and the positions of at least a part of each second straight portion respectively corresponding to at least a part of each first straight portion as seen from the coil center coincide in a plan view.

[0036] Therefore, the impedance as a coil due to the so-called skin effect or proximity effect caused by configuring the winding wire with a thin film conductor for weight reduction and cost reduction can be reduced, and both weight reduction and cost reduction, and improvement of transmission efficiency and prevention of an increase in operating temperature can be achieved simultaneously.

Brief Description of the Drawings

[0037]

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Embodiments for Carrying Out the Invention

[0038] Next, embodiments for carrying out the present invention will be described with reference to the drawings. Each of the embodiments described below is an embodiment when the present invention is applied to a power transmission system that wirelessly transmits power for charging a storage battery mounted on an electric vehicle to the electric vehicle equipped with the storage battery by a magnetic resonance method.

[0039] Here, the power transmission system based on the magnetic resonance method of each embodiment includes a power transmission coil (described later) that transmits power, and a power reception coil (described later) that is arranged so as to face the power transmission coil at a distance (that is, so as to face each other) and receives the power sent from the power transmission coil.

[0040] (A) First Embodiment First, the first embodiment of the present invention will be described with reference to FIGS. 1 to 8.

[0041] (I) Regarding the overall configuration and operation of the power transmission system of the first embodiment First, the overall configuration and operation of the power transmission system of the first embodiment will be described with reference to FIG. 1. Note that FIG. 1 is a block diagram showing the schematic configuration of the power transmission system of the first embodiment.

[0042] As shown in FIG. 1, the power transmission system S of the first embodiment is composed of a power reception device R including a power reception unit RV and the power reception coil RC1, and a power transmission device T including a power transmission unit TR and the power transmission coil TC1. At this time, the power reception device R is mounted on the electric vehicle and is connected to a storage battery (not shown) mounted on the electric vehicle. On the other hand, the power transmission device T is installed on the ground at the position where the electric vehicle moves or stops. When charging the storage battery, the electric vehicle is driven or stopped so that the power reception coil RC1 of the power reception device R and the power transmission coil TC1 of the power transmission device T face each other. When charging the storage battery by the power transmission system S of the first embodiment, power can be transmitted from the power transmission device T to the power reception device R mounted on the parked electric vehicle through the power transmission coil TC1 of the power transmission device T installed on the ground below the parking position. In addition, for the power reception device R mounted on the moving electric vehicle, power may be continuously transmitted from the power transmission device T through the power transmission coils TC1 of a plurality of power transmission devices T installed in a section of a certain distance on the road where the electric vehicle is moving. At this time, the power transmission unit TR corresponds to an example of the "output means" of the present invention, and the power reception unit RV corresponds to an example of the "input means" of the present invention.

[0043] Then, power to be transmitted is input from the power transmission unit TR to the power transmission coil TC1. The power reception coil RC1 outputs the power received from the power transmission coil TC1 by the magnetic resonance method to the power reception unit RV. At this time, the power transmission coil TC1 and the power reception coil RC1 respectively correspond to examples of the "coil" of the present invention.

[0044] In the above configuration, the power transmission unit TR of the power transmission device T outputs the power to be transmitted to the power reception device R to the power transmission coil TC1 while complying with regulations such as the radio wave law in the country where the power transmission system S is used. At this time, the above regulations restrict the leakage magnetic field to be below a predetermined level in consideration of, for example, the influence on the human body. Also, in order to enable mutual connection and use between all the power transmission devices T and the power reception device R, as a result, it is necessary for both to use a predetermined range of frequencies. Therefore, the predetermined range of frequencies or frequency bands should comply with the recommendations of international organizations such as ISO (International Organization for Standardization) or IEC (International Electrotechnical Commission) as the above regulations. Moreover, since the lower limit value of the transmission efficiency considering a predetermined positional deviation between the power transmission coil TC1 and the power reception coil RC1 is also defined by the above international organization, a high power transmission efficiency is also required for the power transmission system S.

[0045] On the other hand, the power reception coil RC1 of the power reception device R that receives power from the power transmission coil TC1 by the magnetic resonance method outputs the received power to the power reception unit RV. As a result, the power reception unit RV converts the output corresponding to the power (for example, high-frequency power of 85 kHz) into a DC (direct current) current by, for example, a power conversion unit (not shown) and outputs it to the battery of the electric vehicle. Thereby, the necessary amount of power is charged in the battery.

[0046] (II) Regarding the configuration of the power transmission coil TC1 (power reception coil RC1) Next, the configurations of the power transmission coil TC1 and the power reception coil RC1 of the first embodiment used in the power transmission system S of the first embodiment described above will be described with reference to FIGS. 2 to 4. Note that the power transmission coil TC1 and the power reception coil RC1 of the first embodiment basically have the same configuration. Therefore, in the following description, the structure of the power transmission coil TC1 will be described. FIGS. 2 to 4 are plan views showing the structure of the power transmission coil TC1 of the first embodiment, and are plan views when the power transmission coil TC is viewed from the power transmission unit TR side in the power transmission device T (see FIG. 1).

[0047] As shown in its plan view in FIG. 2, the power transmission coil TC1 of the first embodiment includes a power transmission loop coil TL11 formed by two parallel copper thin film lines TL111 and TL112, for example, and a power transmission loop coil TL12 (not shown in FIG. 2), which are laminated in a direction perpendicular to the plane of FIG. 2 via an insulating film BF (details will be described later). In the above configuration, the power transmission loop coil TL11 corresponds to an example of the "first winding line" of the present invention, and the power transmission loop coil TL12 corresponds to an example of the "second winding line" of the present invention. Also, the copper thin film lines TL111 and TL112 correspond to an example of the "first parallel winding line" of the present invention. In the first embodiment, the film BF is used for insulation between the power transmission loop coil TL11 and the power transmission loop coil TL12, but in addition to this, an insulating material such as a glass epoxy material can also be used. Also, in order to efficiently dissipate the heat generated as the power transmission coil TC1, a thinned material in which ceramic particles or the like are dispersed can also be used. Further, an appropriate void holding material may be used to laminate through the necessary voids. Furthermore, the winding centers of the copper thin film lines TL111 and TL112 constituting the power transmission loop coil TL11 and the winding centers of the copper thin film lines (to be described later) constituting the power transmission loop coil TL12 are mutually the same or substantially the same.

[0048] As shown in Fig. 2, the power transmission loop coil TL11 is composed of a copper thin film wire TL111 and a copper thin film wire TL112 wound in parallel with each other within the same layer as the power transmission coil TC1 (the surface of the film BF illustrated in Fig. 2). On one side of its outermost peripheral portion, it has an external connection terminal O1 that connects the copper thin film wire TL111 and the copper thin film wire TL112 and is connected to the power transmission unit TR. The power transmission loop coil TL11 is configured such that the copper thin film wire TL111 and the copper thin film wire TL112 are wound six times (6 turns) in parallel counterclockwise from their outermost peripheral portions in Fig. 2, and the outer peripheral end portions (the center of the right side portion in the case shown in Fig. 2) of the copper thin film wire TL111 and the copper thin film wire TL112 are connected to the external connection terminal O1. Also, the inner peripheral end portions (the center side end portions of the power transmission coil TC1 in the case shown in Fig. 2) of the copper thin film wire TL111 and the copper thin film wire TL112 are respectively connected to the copper thin film wires that constitute the power transmission loop coil TL12 formed on the back surface of the film BF through vias V11 and V12 that penetrate the film BF, for each of the copper thin film wire TL111 and the copper thin film wire TL112. Note that the copper thin film wire TL111 has the same width w11 (see Fig. 2) and the same thickness over the entire circumference of the power transmission loop coil TL11. Also, the copper thin film wire TL112 also has the same width w12 (see Fig. 2) and the same thickness over the entire circumference of the power transmission loop coil TL11. Therefore, the width w10 (see Fig. 2) of each winding as the power transmission loop coil TL11 is also the same over the entire circumference of the power transmission loop coil TL11. And in the power transmission loop coil TL11, over its entire circumference, the width w12 of the copper thin film wire TL112 on the inner peripheral side in one winding is made wider than the width w11 of the copper thin film wire TL111 on the outer peripheral side in that one winding. Further, in each of the copper thin film wire TL111 and the copper thin film wire TL112, straight portions are provided on the upper side portion, lower side portion, left side portion, and right side portion in Fig. 2 respectively, and the respective straight portions are connected by substantially concentric arc-shaped curved portions.

[0049] Next, the configuration of the power transmission loop coil TL12 laminated directly below the power transmission loop coil TL11 via the film BF will be described with reference to FIG. 3. Note that FIG. 3 is a plan view showing only the power transmission loop coil TL12 taken out.

[0050] As shown in its plan view in FIG. 3, the power transmission loop coil TL12 laminated on the power transmission loop coil TL11 with the film BF interposed therebetween is composed of two parallel copper thin film lines TL121 and TL122, for example. In this configuration, the copper thin film lines TL121 and TL122 correspond to an example of the "second parallel winding line" of the present invention. At this time, as described above, the centers of winding of the copper thin film lines TL121 and TL122 constituting the power transmission loop coil TL12 and the centers of winding of the copper thin film lines TL111 and TL112 constituting the power transmission loop coil TL11 are mutually the same or substantially the same. Further, the overall shape of the power transmission loop coil TL12 is a substantially square shape identical to the overall shape of the power transmission loop coil TL11.

[0051] As shown in FIG. 3, the power transmission loop coil TL12 is composed of the copper thin film wires TL121 and TL122 wound in parallel with each other within the same layer of the power transmission coil TC1 (the back surface of the film BF illustrated in FIG. 2). On one side of its outermost peripheral portion, it has an external connection terminal O2 that connects the copper thin film wires TL121 and TL122 and is connected to the power transmission unit TR. The power transmission loop coil TL12 is configured such that the copper thin film wires TL121 and TL122 are wound six times (6 turns) in parallel counterclockwise from their respective innermost peripheral portions in FIG. 3, and the outer peripheral end portions (the center of the right side portion in the case shown in FIG. 3) of the copper thin film wires TL121 and TL122 are connected to the external connection terminal O2. On the other hand, the inner peripheral end portion of the copper thin film wire TL121 (the center side end portion of the power transmission coil TC1 in the case shown in FIG. 3) is connected to the copper thin film wire TL111 of the power transmission loop coil TL11 by the via V12, and the inner peripheral end portion of the copper thin film wire TL122 is connected to the copper thin film wire TL112 of the power transmission loop coil TL11 by the via V11. The copper thin film wire TL121 has the same width w11 and the same thickness over the entire circumference of the power transmission loop coil TL12. Also, the copper thin film wire TL122 has the same width w12 and the same thickness over the entire circumference of the power transmission loop coil TL12. For this reason, the width w10 (see FIG. 3) of each winding as the power transmission loop coil TL12 is also the same over the entire circumference of the power transmission loop coil TL12. And in the power transmission loop coil TL12, over its entire circumference, the width w12 of the copper thin film wire TL122 on the inner peripheral side in one winding is made wider than the width w11 of the copper thin film wire TL121 on the outer peripheral side in that one winding. Further, in each of the copper thin film wires TL121 and TL122, straight portions are provided at the upper side portion, lower side portion, left side portion, and right side portion in FIG. 3 respectively, and the respective straight portions are connected by substantially concentric arc-shaped curved portions.

[0052] Next, the positional relationship between the power transmission loop coil TL11 composed of the copper thin film wires TL111 and TL112 and the power transmission loop coil TL12 composed of the copper thin film wires TL121 and TL122 will be described with reference to FIG. 4. Note that FIG. 4 is a plan view showing the overlapping situation between the power transmission loop coil TL11 and the power transmission loop coil TL12. The power transmission loop coil TL11 is shown by a solid line, and the power transmission loop coil TL12 laminated via a film BF (not shown in FIG. 4) directly below it is shown by a dashed line.

[0053] As shown by the solid line in FIG. 4, the power transmission loop coil TL11 is composed of the copper thin film wires TL111 and TL112 wound in parallel from the outer periphery toward the inner periphery, and at its innermost peripheral portion, it is connected to the copper thin film wires TL121 and TL122 constituting the power transmission loop coil TL12 by vias V11 and V12. In the power transmission loop coil TL11, only in one of the four curved portions included in one winding (for example, the curved portion CV11 in the lower right corner portion in FIG. 4), the positions of one pitch (that is, the radial distance of the power transmission coil TC1 in each winding of the adjacent copper thin film wires TL111 and TL112 on each side. The same applies hereinafter. (See FIG. 4)) PT1 of the straight portions of the copper thin film wires TL111 and TL112 are shifted to the inner peripheral side (that is, the winding transitions to the inner peripheral side), and the copper thin film wires TL111 and TL112 are wound counterclockwise. As a result, the curved portion where the winding of the power transmission loop coil TL11 transitions to the inner peripheral side within one pitch PT1 is, for example, six curved portions CV11 arranged from the outer peripheral side to the inner peripheral side in the lower right corner portion in FIG. 4.

[0054] On the other hand, in the power transmission loop coil TL12 formed by winding the copper thin film wires TL121 and TL122, which are connected to the copper thin film wires TL111 and TL112 constituting the power transmission loop coil TL11, and the vias V11 and V12 at their innermost peripheral portions in parallel from the inner periphery to the outer periphery, as shown by the broken line in FIG. 4, only in one of the four curved portions included in one winding (for example, the curved portion CV12 in the lower right corner portion of FIG. 4), the positions of the straight portions of the copper thin film wires TL121 and TL122 shift to the outer peripheral side by one pitch PT1 in each winding (that is, the winding transitions to the outer peripheral side), and the copper thin film wires TL121 and TL122 are wound counterclockwise (that is, in the same direction as the power transmission loop coil TL11). As a result, the curved portion where the winding of the power transmission loop coil TL12 transitions to the outer peripheral side by one pitch PT1 is, for example, six curved portions CV12 arranged from the inner peripheral side to the outer peripheral side in the lower right corner portion of FIG. 4. And the outermost peripheral portion on the right side in FIG. 4 of the power transmission loop coil TL11 is connected to the external connection terminal O1 having a shape protruding outward, and the outermost peripheral portion on the right side in FIG. 4 of the power transmission loop coil TL12 is connected to the external connection terminal O2 having a shape protruding outward.

[0055] The power transmission loop coil TL11 and the power transmission loop coil TL12 each having the above-described shape are laminated as shown in FIG. 4. Thus, the positions of the copper thin film wire TL111 and the copper thin film wire TL121 as viewed from the center of the power transmission coil TC1 are the same except for the curved portions where the respective windings transition and the connection portions to the external connection terminal O1 and the external connection terminal O2. Similarly, the positions of the copper thin film wire TL112 and the copper thin film wire TL122 as viewed from the center of the power transmission coil TC1 are also the same except for the curved portions where the respective windings transition and the connection portions to the external connection terminal O1 and the external connection terminal O2. Therefore, as the power transmission coil TC1, at least each straight portion of the power transmission loop coil TL11 and at least each straight portion of the power transmission loop coil TL12 overlap with each other, and the power transmission loop coil TL11 and the power transmission loop coil TL12 are laminated with the film BF interposed therebetween. As a result, with respect to the counterclockwise winding from the outermost peripheral portion (external connection terminal O1) to the innermost peripheral portion of the power transmission loop coil TL11, the power transmission loop coil TL12 is connected at the innermost peripheral portion so as to have the same winding direction, and while maintaining the winding direction, the power transmission loop coil TL12 is wound from the innermost peripheral portion to the outermost peripheral portion. With this structure, as the power transmission coil TC1 of the first embodiment, a current flows counterclockwise from the outermost peripheral portion to the innermost peripheral portion in the power transmission loop coil TL11, and the current flows in the same counterclockwise direction from the innermost peripheral portion to the outermost peripheral portion in the power transmission loop coil TL12.

[0056] (III) Regarding the manufacturing method of the power transmission coil TC1 and the power reception coil RC1 Next, an outline of a method for manufacturing the power transmission coil TC1 and the power reception coil RC1 of the first embodiment will be described.

[0057] Basically, as the manufacturing method, a first manufacturing method including the following steps (a)-1 to (a)-6, a second manufacturing method including the following steps (b)-1 to (b)-12, or the like, which are the same as those in the prior art, can be used. (a) First Manufacturing Method (a)-1: Form a copper thin film on the entire both surfaces of the film BF (a)-2: Apply a resist on each of the copper thin films (both sides) formed in the above (a)-1. (a)-3: Pattern the resist applied in the above (a)-2 on each surface with respect to the copper thin film lines TL111 and TL112 (copper thin film lines TL121 and TL122) that constitute the power transmission loop coil TL11 (power transmission loop coil TL12). (At this time, the width and thickness of each of the copper thin film lines TL111 and TL112 (copper thin film lines TL121 and TL122) are the same from the outermost peripheral end portion (connection portion to the external connection terminal O1 (external connection terminal O2)) of the power transmission loop coil TL11 (power transmission loop coil TL12) to the portion where the vias V11 and V12 of the innermost peripheral end are connected as described above.) (a)-4: Perform an etching process after the patterning in the above (a)-3 to form the copper thin film lines TL111 and TL112 (copper thin film lines TL121 and TL122). (a)-5: Form vias V11 and V12 that connect the power transmission loop coil TL11 and the power transmission loop coil TL12, and form a power transmission loop coil TC1 including the external connection terminals O1 and O2. (a)-6: Connect the external connection terminals O1 and O2 to the power transmission unit TR (in the case of the power transmission device T) or the power reception unit RV (in the case of the power reception device R). (b) Second Manufacturing Method (b)-1: Form a copper thin film on the entire both sides of the film BF. (b)-2: Form through-holes at positions corresponding to the vias V11 and V12 respectively by a laser or the like. (b)-3: Perform copper plating treatment on the whole including the through-holes by electroless copper plating method and electrolytic copper plating method to form the above vias V11 and V12. (b)-4: Apply a resist on each of the copper plating layers (both sides) formed in the above (b)-3. (b)-5: Pattern the resist applied in the above (b)-4 on each surface with respect to the copper thin film lines TL111 and TL112 (copper thin film lines TL121 and TL122) that constitute the power transmission loop coil TL11 (power transmission loop coil TL12) in the same manner as in the above (a)-3. (b)-6: After the patterning in the above (b)-5, an etching process is performed to form the external connection terminal O1 (external connection terminal O2) and the copper thin film lines TL111 and TL112 (copper thin film lines TL121 and TL122). (b)-7: Connect the external connection terminal O1 and the external connection terminal O2 to the power transmission unit TR (in the case of the power transmission device T) or the power reception unit RV (in the case of the power reception device R). First Embodiment

[0058] Next, regarding the result (simulation result) of measuring the impedance of the power transmission coil TC1 or the power reception coil RC1 by changing the frequency of power transmission of the power transmission system S using the power transmission coil TC1 or the power reception coil RC1 of the first embodiment having the configuration shown in FIGS. 2 to 4, a comparison with the power transmission coil (power reception coil) of the first conventional example will be described with reference to FIGS. 5 to 8 as the first embodiment. FIGS. 5 to 7 are respectively plan views showing the structure of the coils of the first conventional example, and FIG. 8 is a diagram showing the relationship between the frequency and the impedance as an effect of the structure of the power transmission coil TC1 or the power reception coil RC1 of the first embodiment.

[0059] Here, before explaining the above first embodiment, the configuration of the power transmission coil or the power reception coil of the first conventional example, which is the comparison target, will be briefly explained with reference to FIGS. 5 to 7. The power transmission coil and the power reception coil of the first conventional example basically have the same configuration. Therefore, in the following explanation, the structure of the power transmission coil of the first conventional example will be described. Also, FIGS. 5 to 7 are plan views showing the structure of the power transmission coil of the first conventional example when viewed from the same perspective as the power transmission coil TC1 of the first embodiment (see FIG. 1). At this time, in FIGS. 5 to 7, the same member numbers are assigned to the members identical to the power transmission coil TC1 of the first embodiment, and the detailed description thereof is omitted.

[0060] As shown in its plan view in FIG. 5, the power transmission coil TCX of the first conventional example is composed of a power transmission loop coil TLX formed by two parallel copper thin film lines TLX1 and TLX2, and a power transmission loop coil TLY (not shown in FIG. 5), which are laminated in a direction perpendicular to the plane of FIG. 5 via an insulating film BF similar to the power transmission coil TC1 of the first embodiment. At this time, the winding centers of the copper thin film lines TLX1 and TLX2 constituting the power transmission loop coil TLX and the winding centers of the copper thin film lines (to be described later) constituting the power transmission loop coil TLY are mutually the same or substantially the same.

[0061] As shown in FIG. 5, the power transmission loop coil TLX is composed of copper thin film wires TLX1 and TLX2 that are wound parallel to each other within the same layer as the power transmission coil TCX (on the surface of the film BF illustrated in FIG. 5). On one side of its outermost peripheral part, it has an external connection terminal O1 for connecting the copper thin film wire TLX1 and the copper thin film wire TLX2. And the power transmission loop coil TLX is configured such that the copper thin film wire TLX1 and the copper thin film wire TLX2 are wound six times (6 turns) parallel to each other counterclockwise from their outermost peripheral parts in FIG. 5, and the outer peripheral end parts (the center of the right side part in the case shown in FIG. 5) of the copper thin film wire TLX1 and the copper thin film wire TLX2 are connected to the external connection terminal O1. Also, the inner peripheral end parts (the center side end parts of the power transmission coil TCX in the case shown in FIG. 5) of the copper thin film wire TLX1 and the copper thin film wire TLX2 are respectively connected to the copper thin film wires that constitute the power transmission loop coil TLY formed on the back surface of the film BF through vias V11 and V12 that penetrate the film BF, for each of the copper thin film wire TLX1 and the copper thin film wire TLX2. Note that the copper thin film wire TLX1 has the same width w11 (see FIGS. 2 and 5) and the same thickness over the entire circumference of the power transmission loop coil TLX. Also, the copper thin film wire TLX2 also has the same width w12 (see FIGS. 2 and 5) and the same thickness over the entire circumference of the power transmission loop coil TLX. For this reason, the width w10 (see FIGS. 2 and 5) of each winding as the power transmission loop coil TLX is also the same over the entire circumference of the power transmission loop coil TLX. And in the power transmission loop coil TLX, over its entire circumference, the width w12 of the copper thin film wire TLX2 on the inner peripheral side in one winding is made wider than the width w11 of the copper thin film wire TLX1 on the outer peripheral side in one winding. Furthermore, in each of the copper thin film wire TLX1 and the copper thin film wire TLX2, straight parts are provided on the upper side part, lower side part, left side part, and right side part in FIG. 5 respectively, and the respective straight parts are connected by curved parts in a substantially concentric arc shape.

[0062] Next, the configuration of the power transmission loop coil TLY laminated directly below the power transmission loop coil TLX via the film BF will be described with reference to FIG. 6. Note that FIG. 6 is a plan view showing only the power transmission loop coil TLY taken out.

[0063] As shown in its plan view in FIG. 6, the power transmission loop coil TLY laminated on the power transmission loop coil TLX with the film BF interposed therebetween is composed of two parallel copper thin film lines TLY1 and copper thin film line TLY2. At this time, the winding centers of the copper thin film line TLY1 and the copper thin film line TLY2 constituting the power transmission loop coil TLY and the winding centers of the copper thin film line TLX1 and the copper thin film line TLX2 constituting the power transmission loop coil TLX are mutually the same or substantially the same. Further, the overall shape of the power transmission loop coil TLY is a substantially square shape identical to the overall shape of the power transmission loop coil TLX.

[0064] As shown in FIG. 6, the power transmission loop coil TLY is composed of the copper thin film wire TLY1 and the copper thin film wire TLY2 that are wound in parallel with each other within the same layer as the power transmission coil TCX (the back surface of the film BF illustrated in FIG. 5). On one side of its outermost peripheral portion, it has an external connection terminal O2 for connecting the copper thin film wire TLY1 and the copper thin film wire TLY2. And the power transmission loop coil TLY is configured such that the copper thin film wire TLY1 and the copper thin film wire TLY2 are wound six times (6 turns) in parallel counterclockwise from their respective innermost peripheral portions in FIG. 6, and the outer peripheral end portions (the central portion of the right side in the case shown in FIG. 6) of the copper thin film wire TLY1 and the copper thin film wire TLY2 are connected to the external connection terminal O2. On the other hand, the inner peripheral end portion of the copper thin film wire TLY1 (the central side end portion of the power transmission coil TCY in the case shown in FIG. 6) is connected to the copper thin film wire TLX1 of the power transmission loop coil TLX by the via V12, and the inner peripheral end portion of the copper thin film wire TLY2 is connected to the copper thin film wire TLX2 of the power transmission loop coil TLX by the via V11. Note that the copper thin film wire TLY1 has the same width w11 and the same thickness over the entire circumference of the power transmission loop coil TLY. Also, the copper thin film wire TLY2 also has the same width w12 and the same thickness over the entire circumference of the power transmission loop coil TLY. For this reason, the width w10 (see FIG. 6) of each winding as the power transmission loop coil TLY is also the same over the entire circumference of the power transmission loop coil TLY. And in the power transmission loop coil TLY, over its entire circumference, the width w12 of the copper thin film wire TLY2 on the inner peripheral side in one winding is made wider than the width w11 of the copper thin film wire TLY1 on the outer peripheral side in one winding. Further, in each of the copper thin film wire TLY1 and the copper thin film wire TLY2, straight portions are provided at the upper side portion, the lower side portion, the left side portion, and the right side portion in FIG. 6 respectively, and the respective straight portions are connected by substantially concentric arc-shaped curved portions.

[0065] Next, the positional relationship between the power transmission loop coil TLX composed of the copper thin film lines TLX1 and TLX2 and the power transmission loop coil TLY composed of the copper thin film lines TLY1 and TLY2 will be described with reference to FIG. 7. Note that FIG. 7 is a plan view showing the overlapping situation between the power transmission loop coil TLX and the power transmission loop coil TLY. The power transmission loop coil TLX is shown by a solid line, and the power transmission loop coil TLY laminated via a film BF (not shown in FIG. 7) directly below it is shown by a dashed line.

[0066] As shown by the solid line in FIG. 7, the power transmission loop coil TLX is composed of the copper thin film lines TLX1 and TLX2 wound in parallel from the outer periphery toward the inner periphery, and at its innermost peripheral part, it is connected to the copper thin film lines TLY1 and TLY2 constituting the power transmission loop coil TLY by vias V11 and V12. In the power transmission loop coil TLX, for each quarter turn, each curved part is formed such that the position of the straight part is shifted inward by one-fourth of the pitch PT1 (that is, the winding transitions to the inner peripheral side), and the copper thin film lines TLX1 and TLX2 are wound counterclockwise.

[0067] On the other hand, in the power transmission loop coil TLY in which the copper thin film lines TLY1 and TLY2 respectively connected to the copper thin film lines TLX1 and TLX2 constituting the power transmission loop coil TLX by vias V11 and V12 at its innermost peripheral part are wound in parallel from the inner periphery toward the outer periphery, as shown by the dashed line in FIG. 7, for each quarter turn, each curved part is formed such that the position of the straight part is shifted outward by one-fourth of the pitch PT1 (that is, the winding transitions to the outer peripheral side), and the copper thin film lines TLY1 and TLY2 are wound counterclockwise (that is, in the same direction as the power transmission loop coil TLX). And the outermost peripheral part on the right side in FIG. 7 of the power transmission loop coil TLX is connected to an external connection terminal O1 having a shape protruding outward, and the outermost peripheral part on the right side in FIG. 7 of the power transmission loop coil TLY is connected to an external connection terminal O2 having a shape protruding outward.

[0068] The power transmission loop coil TLX and the power transmission loop coil TLY each having the above-described shape are laminated as shown in FIG. 7, so that the positions of the copper thin film wire TLX1 and the copper thin film wire TLY1 as viewed from the center of the power transmission coil TCX are different as shown in FIG. 7. Similarly, the positions of the copper thin film wire TLX2 and the copper thin film wire TLY2 as viewed from the center of the power transmission coil TCX are also different as shown in FIG. 7. Therefore, as the power transmission coil TCX, the power transmission loop coil TLX and the power transmission loop coil TLY are laminated with the film BF interposed therebetween in a state where they do not overlap. As a result, with respect to the counterclockwise winding from the outermost peripheral portion (external connection terminal O1) to the innermost peripheral portion of the power transmission loop coil TLX, the power transmission loop coil TLY is connected at the innermost peripheral portion so as to have the same winding direction, and the power transmission loop coil TLY is wound from the innermost peripheral portion to the outermost peripheral portion while maintaining the winding direction. With this structure, in the power transmission coil TCX of the first conventional example, a current flows counterclockwise from the outermost peripheral portion to the innermost peripheral portion in the power transmission loop coil TLX, and the current flows in the same counterclockwise direction from the innermost peripheral portion to the outermost peripheral portion in the power transmission loop coil TLY.

[0069] And the other specifications of the power transmission coil TC1 of the first embodiment used in the experiment of the first embodiment and the power transmission coil TCX of the first conventional example are as follows. In the following description, the specifications of the power transmission coil TC1 and the power transmission coil TCX will be described. The specifications of the power receiving coil RC1 of the first embodiment used in the experiment are the same as those of the power transmission coil TC1, and the specifications of the power receiving coil of the first conventional example are the same as those of the power transmission coil TCX.

[0070] · Size of the power transmission coil TC1 (power receiving coil RC1) and the power transmission coil TCX (and the power receiving coil of the first conventional example): 280 millimeters × 280 millimeters · Pitch PT1: 15 millimeters · Thickness of the copper thin film wire in the copper thin film wire TL111 etc.: 0.2 millimeters

[0071] As shown in FIG. 8, in the vicinity of the frequency (85 kHz) used for power transmission by the power transmission system S, it can be seen that the impedance is about 2 / 3 lower when using the power transmission coil TC1 and the power reception coil RC1 of the first embodiment than when using the power transmission coil TCX and the power reception coil of the first conventional example. In this regard, when the above power transmission is performed at a frequency of 85 kHz, the inventors of the present application have discovered that it is preferable that the impedance be less than 0.5 ohm. Even considering this point, a configuration such as the above power transmission coil TC1 and the above power reception coil RC1 (that is, a configuration in which the copper thin film wires constituting each of them overlap) can be said to be more preferable for reducing impedance.

[0072] As described above, according to the power transmission using the power transmission system S of the embodiment including the power transmission coil TC1 and the power reception coil RC1 of the first embodiment, the power transmission coil TC1 (power reception coil RC1) includes a power transmission loop coil TL11 (wound from the outer periphery to the inner periphery) and a power transmission loop coil TL12 (wound from the inner periphery to the outer periphery) formed of copper thin film wires TL111 etc. having a plurality of straight portions and a plurality of curved portions, with the film BF sandwiched therebetween. The overall planar shapes of the power transmission loop coil TL11 and the power transmission loop coil TL12 are each a substantially square (it may also be a polygon other than a square) that is the same as each other. The position seen from the center of the power transmission coil TC1 (power reception coil RC1) of each winding of the power transmission loop coil TL11 and the position seen from the center of the power transmission coil TC1 (power reception coil RC1) of each winding of the power transmission loop coil TL12 coincide in plan view (see FIG. 4). Therefore, it is possible to reduce the impedance due to the so-called skin effect or proximity effect caused by configuring the power transmission coil TC1 and the power reception coil RC1 with copper thin film wires for weight reduction and cost reduction, and it is possible to achieve both weight reduction and cost reduction, and improvement of transmission efficiency and prevention of an increase in operating temperature.

[0073] Also, in the winding of the power transmission loop coil TL11, the winding transition for one turn is performed only in one curved portion (CV11 (see FIG. 4)) included in one turn. Further, in the winding of the power transmission loop coil TL12, the winding transition for one turn is performed only in one curved portion (CV12 (see FIG. 4)) included in one turn. Therefore, the positions of the corresponding power transmission coil TC1 and power reception coil RC1 of the thin film conductor, as viewed from their centers, can be surely made to coincide with each other in a plan view.

[0074] Furthermore, since the power transmission loop coil TL11 is composed of the copper thin film wire TL111 and the copper thin film wire TL112, and the power transmission loop coil TL12 is composed of the copper thin film wire TL121 and the copper thin film wire TL122, the impedance can be further reduced, so that weight reduction and cost reduction, and improvement of transmission efficiency and prevention of increase in operating temperature can be made more compatible with each other.

[0075] Moreover, since the width w12 of the inner peripheral side copper thin film wire TL112 (copper thin film wire TL122) is wider than the width w11 of the outer peripheral side copper thin film wire TL111 (copper thin film wire TL121), the impedance can be further reduced, so that weight reduction and cost reduction, and improvement of transmission efficiency and prevention of increase in operating temperature can be made more compatible with each other.

[0076] (B) Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIGS. 9 and 10. FIGS. 9 and 10 are plan views showing the coil structures of the second embodiment, respectively.

[0077] In the power transmission coil TC1 (power reception coil RC1) of the above-described first embodiment, the power transmission loop coil TL11 is composed of a copper thin film wire TL111 and a copper thin film wire TL121 wound in parallel within one layer (the surface of the film BF) in the power transmission coil TC1. Also, the power transmission loop coil TL12 is composed of a copper thin film wire TL121 and a copper thin film wire TL122 wound in parallel within another layer (the back surface of the film BF) in the power transmission coil TC1. This case has been described (see FIGS. 2 to 4). In contrast, in the power transmission coil (and power reception coil) of the second embodiment described below, a first power transmission loop coil made of copper thin film wires wound from the outer peripheral side to the inner peripheral side, and a second power transmission loop coil made of copper thin film wires wound from the inner peripheral side to the outer peripheral side and serially connected to the first power transmission loop coil are formed together within one layer in the power transmission coil (and power reception coil). Further, two such layers are laminated to form the power transmission coil (and power reception coil). In addition to these, in the power transmission coil (and power reception coil) of the second embodiment, a coil for current adjustment (hereinafter referred to as the "current adjustment coil") is connected in series to the first power transmission loop coil and the second power transmission loop coil.

[0078] Note that the configurations of the power transmission coil of the second embodiment and the power reception coil of the second embodiment are basically the same. Also, the configurations of the power reception loop coil in the power reception coil of the second embodiment and the power transmission loop coil in the power transmission coil of the second embodiment are the same. Further, the configurations of the current adjustment coils in the power transmission coil of the second embodiment and the power reception coil of the second embodiment are also the same. Therefore, in the following description, only the configuration of the power transmission coil of the second embodiment will be described. At this time, the same component numbers will be assigned to the same component members as those of the power transmission coil TC1 of the first embodiment, and detailed descriptions thereof will be omitted.

[0079] That is, as shown in the plan view of FIG. 9(a), the power transmission coil TC2 of the second embodiment includes a power transmission loop coil TL21 (corresponding to the first power transmission loop coil and the second power transmission loop coil) formed by two parallel copper thin film lines TL211 and TL212, and a power transmission loop coil TL22 whose plan view is shown in FIG. 9(b), which are laminated in a direction perpendicular to the paper surface of FIG. 9 with an insulating film BF therebetween. Also, the centers of winding of the copper thin film lines TL211 and TL212 constituting the power transmission loop coil TL21 and the centers of winding of the copper thin film lines TL221 and TL222 (see FIG. 9(b)) constituting the power transmission loop coil TL22 are mutually the same or substantially the same.

[0080] As shown in Fig. 9(a), the power transmission loop coil TL21 is composed of a copper thin film wire TL211 and a copper thin film wire TL212 that are wound in parallel with each other within the same layer of the power transmission coil TC2 (the surface of the film BF illustrated in Fig. 9(a)). At one side of its outermost periphery (the center of the right side in the case shown in Fig. 9(a)), there are an external connection terminal O1 for connecting the copper thin film wire TL211 and the copper thin film wire TL212 and connecting to the power transmission unit TR, and connection terminals M1 and M2 for separately connecting the copper thin film wire TL211 and the copper thin film wire TL212 to the current adjustment coils of the second embodiment described later. The power transmission loop coil TL21 is configured such that the copper thin film wire TL211 and the copper thin film wire TL212 are wound counterclockwise in parallel two and a half turns (2.5 turns) from the external connection terminal O1 at their outermost periphery to their innermost periphery in Fig. 9(a), and further wound counterclockwise in parallel two and a half turns (2.5 turns) from the innermost periphery to the connection terminals M1 and M2. Also, the intersecting portions in the winding of the copper thin film wire TL211 and the copper thin film wire TL212 are insulated from each other at four locations (see Fig. 9(a)) by a laminated structure in which an insulating layer is sandwiched and the copper thin film wire TL211 and the copper thin film wire TL212 are conductively connected by vias VV, or a method using jumper wires, etc. Further, in each of the copper thin film wire TL211 and the copper thin film wire TL212, straight portions are provided on the upper side, lower side, left side, and right side in Fig. 9(a), respectively, and each straight portion is connected by a substantially concentric arc-shaped curved portion. Note that the width w21 of the copper thin film wire TL211 becomes wider toward the inner peripheral side of the power transmission coil TC2. This width w21 is the same for each straight portion constituting the copper thin film wire TL211, and in each curved portion connecting the straight portions, the width w21 is changed (i.e., changed to be wider toward the inner peripheral side of the power transmission coil TC2). On the other hand, the thickness of the copper thin film wire TL211 is the same throughout the entire circumference of the power transmission loop coil TL21. On the other hand, the width w22 of the copper thin film wire TL212 also becomes wider toward the inner peripheral side of the power transmission coil TC2, similar to the width w21.This width w22 is the same for each straight portion constituting the copper thin film line TL212, and in each curved portion connecting the straight portions, the width w22 is changed (i.e., changed so as to be wider toward the inner peripheral side of the power transmission coil TC2). On the other hand, the thickness of the copper thin film line TL212 is the same throughout the entire circumference of the power transmission loop coil TL21. With the above configuration, the width w20 (see FIG. 9(a)) of each winding as the power transmission loop coil TL21 is also wider toward the inner peripheral side of the power transmission coil TC2. And in the power transmission loop coil TL21, throughout its entire circumference, the width w22 of the copper thin film line TL212 on the inner peripheral side in one winding is made wider than the width w21 of the copper thin film line TL211 on the outer peripheral side in that one winding.

[0081] Next, the configuration of the power transmission loop coil TL22 laminated directly below the power transmission loop coil TL21 via the film BF will be described with reference to FIG. 9(b). Note that FIG. 9(b) is a plan view showing only the power transmission loop coil TL22 taken out. The overall shape of the power transmission loop coil TL22 is a substantially rectangular shape identical to the overall shape of the power transmission loop coil TL21.

[0082] As shown in the plan view in FIG. 9(b), the power transmission loop coil TL22 laminated on the power transmission loop coil TL21 with the film BF interposed therebetween is composed of a copper thin film wire TL221 and a copper thin film wire TL222 wound in parallel with each other within the same layer of the power transmission coil TC2 (the back surface of the film BF illustrated in FIG. 9(a)). At one side of its outermost peripheral part (the center of the right side part in the case shown in FIG. 9(b)), there are an external connection terminal O1 for connecting the copper thin film wire TL221 and the copper thin film wire TL222 and connecting to the power transmission part TR in parallel with the power transmission loop coil TL21, and a connection terminal M1 and a connection terminal M2 for separately connecting the copper thin film wire TL221 and the copper thin film wire TL222 to the current adjustment coil of the second embodiment, respectively. At this time, the external connection terminal O1, the connection terminal M1, and the connection terminal M2 are the same as the external connection terminal O1, the connection terminal M1, and the connection terminal M2 shown in FIG. 9(a). The power transmission loop coil TL22 is configured such that the copper thin film wire TL221 and the copper thin film wire TL222 are wound counterclockwise in parallel two and a half turns (2.5 turns) from the external connection terminal O1 at their outermost peripheral part to their innermost peripheral part in FIG. 9(b), and further wound counterclockwise in parallel two and a half turns (2.5 turns) from the innermost peripheral part to the connection terminal M1 and the connection terminal M2. Also, the crossing parts in the winding of the copper thin film wire TL221 and the copper thin film wire TL222 are insulated from each other and crossed at four locations (see FIG. 9(b)) by a method such as a laminated structure in which an insulating layer is interposed and the copper thin film wire TL221 and the copper thin film wire TL222 are electrically connected together by vias VV or a method using jumper wires. Further, in each of the copper thin film wire TL221 and the copper thin film wire TL222, straight parts are provided at the upper side part, the lower side part, the left side part, and the right side part in FIG. 9(b), respectively, and the respective straight parts are connected by substantially concentric arc-shaped curved parts. The width w21 of the copper thin film wire TL221 is the same as the width w21 of the copper thin film wire TL211 shown in FIG. 9(a), and becomes wider toward the inner peripheral side of the power transmission coil TC2. This width w21 is the same for each straight part constituting the copper thin film wire TL221, and in each curved part connecting the straight parts, the width w21 is changed (i.e., changed to become wider toward the inner peripheral side of the power transmission coil TC2).On the one hand, the thickness of the copper thin film line TL221 is the same throughout the entire circumference of the power transmission loop coil TL22. On the other hand, the width w22 of the copper thin film line TL222 is the same as the width w22 of the copper thin film line TL212 of the power transmission loop coil TL21 shown in Fig. 9(a). Similar to the width w21 of the copper thin film line TL221, it becomes wider toward the inner peripheral side of the power transmission coil TC2. This width w22 is the same for each straight portion constituting the copper thin film line TL222, and in each curved portion connecting the straight portions, the width w22 is changed (i.e., changed so as to become wider toward the inner peripheral side of the power transmission coil TC2). On the one hand, the thickness of the copper thin film line TL222 is the same throughout the entire circumference of the power transmission loop coil TL21. With the above configuration, the width w20 of each winding as the power transmission loop coil TL22 (the same as the width w20 in the power transmission loop coil TL21 shown in Fig. 9(a). Refer to Fig. 9(b).) also becomes wider toward the inner peripheral side of the power transmission coil TC2. And in the power transmission loop coil TL22, throughout its entire circumference, the width w22 of the copper thin film line TL222 on the inner peripheral side in one winding is made wider than the width w21 of the copper thin film line TL221 on the outer peripheral side in that one winding.

[0083] Next, regarding the configuration of the current adjustment coil further laminated directly below the power transmission loop coil TL22 via a film (made of the same material as the film BF, etc., not shown) in the power transmission coil TC2 of the second embodiment, it will be described with reference to Fig. 10(a). Note that Fig. 10(a) is a plan view showing only the current adjustment coil taken out. Also, the overall shape of the current adjustment coil is a substantially rectangular shape identical to the overall shape of each of the power transmission loop coils TL21 and TL22.

[0084] As shown in its plan view in Fig. 10(a), the current adjustment coil TL23 laminated with a film sandwiched directly below the power transmission loop coil TL22 is composed of a copper thin film wire TL231 and a copper thin film wire TL232 wound in parallel with each other within the same layer of the power transmission coil TC2. The outermost peripheral ends thereof are connection terminals M1 and connection terminals M2 for separately connecting the copper thin film wire TL231 and the copper thin film wire TL232 to the copper thin film wire TL211, the copper thin film wire TL212, the copper thin film wire TL221, and the copper thin film wire TL222, respectively. At this time, the connection terminals M1 and the connection terminals M2 are the same as the connection terminals M1 and the connection terminals M2 shown in Fig. 9, respectively. On the other hand, the innermost peripheral ends of the copper thin film wire TL231 and the copper thin film wire TL232 are external connection terminals O2 for connecting the copper thin film wire TL231 and the copper thin film wire TL232 and connecting to the power transmission unit TR. This external connection terminal O2 is configured to penetrate the film between the current adjustment coil TL23 and the power transmission loop coil TL22 and the film BF between the power transmission loop coil TL22 and the power transmission loop coil TL21 and be exposed on the same surface as the external connection terminal O1 shown in Fig. 9(a). And the current adjustment coil TL23 is configured such that the copper thin film wire TL231 and the copper thin film wire TL232 are wound counterclockwise in parallel five times (5 turns) from the connection terminals M1 and M2 at their outermost peripheral parts to the external connection terminals O2 at their innermost peripheral parts in Fig. 10(a). As a result, the combined electrical winding turns (five turns) of the power transmission loop coil TL21 and the power transmission loop coil TL22 are an integral multiple (one time) of the winding turns of the current adjustment coil TL23. Further, in each of the copper thin film wire TL231 and the copper thin film wire TL232, straight portions are provided at the upper side portion, the lower side portion, the left side portion, and the right side portion in Fig. 10(a), respectively, and the respective straight portions are connected by substantially concentric arc-shaped curved portions. Also, the winding centers of the copper thin film wire TL211 and the copper thin film wire TL212, the winding centers of the copper thin film wire TL221 and the copper thin film wire TL222, and the winding centers of the copper thin film wire TL231 and the copper thin film wire TL232 are the same as or substantially the same as each other.Note that the width w21 of the copper thin film line TL231 is the same as the width w21 of the copper thin film line TL211 of the power transmission loop coil TL21 shown in Fig. 9(a) and the width w21 of the copper thin film line TL221 of the power transmission loop coil TL22 shown in Fig. 9(b), and it becomes wider toward the inner peripheral side of the power transmission coil TC2. This width w21 is the same for each straight portion constituting the copper thin film line TL231, and in each curved portion connecting the straight portions, the width w21 is changed (i.e., changed so as to become wider toward the inner peripheral side of the power transmission coil TC2). On the other hand, the thickness of the copper thin film line TL231 is the same throughout the entire circumference of the current adjustment coil TL23. On the other hand, the width w22 of the copper thin film line TL232 is the same as the width w22 of the copper thin film line TL212 shown in Fig. 9(a) and the width w22 of the copper thin film line TL222 shown in Fig. 9(b), and like the width w21 of the copper thin film line TL231, it becomes wider toward the inner peripheral side of the power transmission coil TC2. This width w23 is the same for each straight portion constituting the copper thin film line TL232, and in each curved portion connecting the straight portions, the width w22 is changed (i.e., changed so as to become wider toward the inner peripheral side of the power transmission coil TC2). On the other hand, the thickness of the copper thin film line TL232 is the same throughout the entire circumference of the current adjustment coil TL23. With the above configuration, the width w20 of each winding as the current adjustment coil TL23 (the same as the width w20 in the power transmission loop coil TL21 shown in Fig. 9(a) and the width w20 in the power transmission loop coil TL22 shown in Fig. 9(b). Refer to Fig. 10(a).) also becomes wider toward the inner peripheral side of the power transmission coil TC2. And in the current adjustment coil TL23, throughout its entire circumference, the width w22 of the copper thin film line TL232 on the inner peripheral side in one winding is made wider than the width w21 of the copper thin film line TL231 on the outer peripheral side in that one winding.

[0085] Next, the positional relationship among the power transmission loop coil TL21 composed of the copper thin film lines TL211 and TL212, the power transmission loop coil TL22 composed of the copper thin film lines TL221 and TL222, and the power transmission loop coil TL23 composed of the copper thin film lines TL231 and TL232 will be described with reference to FIG. 10(b). Note that FIG. 10(b) is a plan view showing the overlapping situation of the power transmission loop coil TL21, the power transmission loop coil TL22, and the current adjustment coil TL23. The power transmission loop coil TL21 is shown by a solid line, the power transmission loop coil TL22 laminated via a film BF (not shown in FIG. 10(b)) directly below it is shown by a dashed line, and the current adjustment coil TL23 laminated via a film directly below the power transmission loop coil TL22 is shown by a one-dot chain line, respectively.

[0086] As shown by the solid line in FIG. 10(b), in the power transmission loop coil TL21 composed of the copper thin film lines TL211 and TL212 wound in parallel, among the four curved portions included in one winding, in only one curved portion (for example, the curved portion at the lower right corner in FIG. 10(b)), the positions of the straight portions of the copper thin film lines TL211 and TL212 are shifted to the outer peripheral side or the inner peripheral side by one pitch PT2 (see FIG. 10(b)) in each winding (that is, the winding transitions to the outer peripheral side or the inner peripheral side). Thus, the copper thin film lines TL211 and TL212 are wound counterclockwise from the external connection terminal O1 to the connection terminals M1 and M2. As a result, the curved portion in the power transmission loop coil TL21 where the winding transitions by one pitch PT2 to the outer peripheral side or the inner peripheral side is included in, for example, the four curved portion groups at the lower right corner in FIG. 10(b).

[0087] On the other hand, in the power transmission loop coil TL22 composed of the copper thin film wires TL221 and TL222 that form the power transmission loop coil TL21, the external connection terminal O1, and the connection terminals M1 and M2, which are respectively connected at their outermost peripheral portions, as shown by the broken line in Fig. 10(b), in only one of the four curved portions included in one winding (for example, the curved portion in the lower right corner in Fig. 10(b)), the positions of the straight portions of the copper thin film wires TL221 and TL222 are shifted to the outer peripheral side or the inner peripheral side by one pitch PT2 in each winding (that is, the winding transitions to the outer peripheral side or the inner peripheral side), and the copper thin film wires TL221 and TL222 are wound counterclockwise (that is, in the same direction as the power transmission loop coil TL21). As a result, the curved portion in the power transmission loop coil TL22 where the winding transitions to the outer peripheral side or the inner peripheral side by one pitch PT2 is included in, for example, the four curved portion groups in the lower right corner in Fig. 10(b). And one outermost end on the right side in Fig. 10(b) of the power transmission loop coil TL21 and the power transmission loop coil TL22 is connected to the external connection terminal O1 having a shape protruding outward, and the other outermost end on the right side in Fig. 10(b) of the power transmission loop coil TL21 and the power transmission loop coil TL22 are the connection terminals M1 and M2.

[0088] Furthermore, in the current adjustment coil TL23 formed by winding the copper thin film lines TL231 and TL232, which are connected to the copper thin film lines TL211 and TL212 and the copper thin film lines TL221 and TL222 via the connection terminals M1 and M2, in parallel from the outer periphery to the inner periphery, as shown by the dashed-dotted line in Fig. 10(b), only in one of the four curved portions included in one winding (for example, the curved portion in the lower right corner in Fig. 10(b)), the positions of the straight portions of the copper thin film lines TL231 and TL232 are shifted inward by one pitch PT2 in each winding (that is, the winding transitions to the inner periphery side), and the copper thin film lines TL231 and TL232 are wound counterclockwise (that is, in the same direction as the power transmission loop coils TL21 and TL22). As a result, the curved portion where the winding of the current adjustment coil TL23 transitions to the inner periphery side within one pitch PT2 is, for example, four curved portion groups arranged from the outer periphery side to the inner periphery side in the lower right corner portion in Fig. 10(b). The outermost peripheral end of the current adjustment coil TL23 is the connection terminals M1 and M2, and its innermost peripheral end is the external connection terminal O2.

[0089] The power transmission loop coil TL21, the power transmission loop coil TL22, and the current adjustment coil TL23, each having the above-described shape, are laminated as shown in FIG. 10(b). Thus, the positions of the copper thin film lines TL211, TL221, and TL231, respectively, viewed from the center of the power transmission coil TC2, are the same except for the curved portions where each winding transitions, the external connection terminals O1 and O2, and the connection portions to the connection terminals M1 and M2. Similarly, the positions of the copper thin film lines TL212, TL222, and TL232, respectively, viewed from the center of the power transmission coil TC2, are the same except for the curved portions where each winding transitions, the external connection terminals O1 and O2, and the connection portions to the connection terminals M1 and M2. Therefore, as the power transmission coil TC2, at least the straight portions of the power transmission loop coil TL21, at least the straight portions of the power transmission loop coil TL22, and at least the straight portions of the current adjustment coil TL23 overlap with each other, and the power transmission loop coil TL21 to the current adjustment coil TL23 are laminated with a film BF or the like interposed therebetween. As a result, the copper thin film lines TL211, TL212, TL221, and TL222 are wound counterclockwise in the order of the outermost peripheral portion of the power transmission loop coil TL21 and the outermost peripheral portion (external connection terminal O1) of the power transmission loop coil TL22 → their innermost peripheral portions → the connection terminals M1 and M2 of their outermost peripheral portions. Then, the copper thin film lines TL231 and TL232 of the current adjustment coil TL23 are wound from the connection terminals M1 and M2 counterclockwise to their innermost peripheral portions, and the innermost peripheral end portions are connected to the external connection terminal O2. With this structure, in the power transmission coil TC2 of the second embodiment, current flows counterclockwise from the external connection terminal O1 to the connection terminals M1 and M2 in the power transmission loop coil TL21 and the power transmission loop coil TL22, and then flows in the same counterclockwise direction from the connection terminals M1 and M2 to the external connection terminal O2 in the current adjustment coil TL23.

[0090] Incidentally, the manufacturing method of the power transmission coil TC2 and the power reception coil RC2 of the second embodiment is basically the same as the above manufacturing method of the power transmission coil TC1 and the power reception coil RC1 of the first embodiment, so the detailed description thereof will be omitted. Second embodiment

[0091] Next, in a power transmission system using the power transmission coil TC2 or the power reception coil RC2 of the second embodiment having the configuration shown in FIGS. 9 and 10, regarding the measurement results (simulation results) of impedance and the like when the configuration of the power transmission coil or the power reception coil is changed, the following Table 1 will be used as a second example for explanation. Note that Table 1 shows the impedance and the like as the effects of the structure of the power transmission coil TC2 or the power reception coil RC2 of the second embodiment, and also describes the impedance and the like as the effects of the structure of the power transmission coil or the power reception coil of the third embodiment to be described later.

Table 1

[0092] Here, the second conventional example, which is the comparison target with the above second example, is such that, as exemplified in Table 1, the number of turns of the power transmission loop coils TL21 and TL22 in the power transmission coil TC2 or the power reception coil RC2 of the second embodiment is eight each, and the other structures such as the number of turns of the current adjustment coil TL23 are the same as those of the power transmission coil TC2 or the power reception coil RC2 of the second embodiment. As a result, in the power transmission coil and the power reception coil of the second conventional example, the number of turns (eight turns) of each power transmission loop coil included therein is not an integer multiple of the number of turns (five turns) of the current adjustment coil RL23. Therefore, the positions of the copper thin film wires constituting the power transmission loop coil and the like and the current adjustment coil RL23 do not overlap when viewed from their centers.

[0093] In addition, the other specifications of the power transmission coil TC2 of the second embodiment and the power transmission coil of the second conventional example, which are used in the experiment of the second embodiment, are as follows. In the following description, the specifications of the power transmission coil TC2 and the power transmission coil of the second conventional example will be described. However, the specifications of the power reception coil RC2 of the second embodiment used in the experiment are the same as those of the power transmission coil TC2, and the specifications of the power reception coil of the second conventional example are the same as those of the power transmission coil of the second conventional example.

[0094] · Dimensions of the power transmission coil TC2 (power reception coil RC2), the power transmission coil, and the power reception coil of the second conventional example: 266 mm in long side × 160 mm in short side · Pitch PT2 (see Fig. 10(b)): 5.5 mm (outermost periphery) to 9.5 mm (innermost periphery) · Thickness of the copper thin film wire in the copper thin film wire TL211, etc.: 0.2 mm · Distance between the power transmission coil and the power reception coil: 40 mm · Ferrite sheets having the same thickness as the power transmission coil and the power reception coil are provided on the surfaces opposite to the opposing surfaces of the power transmission coil and the power reception coil, respectively.

[0095] As shown by hatching in Table 1, at the frequency (85 kHz) used for power transmission by the power transmission system of the second embodiment, the use of the power transmission coil TC2 and the power reception coil RC2 of the second embodiment results in better performance in terms of impedance and Q value than when using the power transmission coil and the power reception coil of the second conventional example. That is, a configuration such as the above power transmission coil TC2 and the above power reception coil RC2 (a configuration in which the copper thin film wires constituting each of them overlap) is more preferable for reducing impedance and inductance and improving the Q value.

[0096] As described above, according to the power transmission using the power transmission system of the second embodiment including the power transmission coil TC2 and the power reception coil RC2 of the second embodiment, in addition to the effects of the power transmission using the power transmission system S of the first embodiment, the widths w21 and w22 of the copper thin film lines TL211 and TL212, the copper thin film lines TL221 and TL222, and the copper thin film lines TL231 and TL232 are wider as the winding approaches the center of the power transmission coil TC2 or the like. Therefore, the impedance as the power transmission coil TC2 or the like can be further reduced by widening the width as the copper thin film line closer to the center where the current concentrates.

[0097] (C) Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIGS. 11 to 16. FIG. 11 is a circuit diagram showing an outline configuration of a power reception coil included in the power transmission system of the third embodiment, FIGS. 12 to 14 are plan views showing the structure of the coil of the third embodiment, FIG. 15 is a diagram showing the relationship between the capacitance and the transmission efficiency as an effect of the configuration of the power reception coil of the third embodiment, and FIG. 16 is a diagram showing the relationship between the capacitance and the loss (copper loss) as an effect of the structure of the power reception coil of the third embodiment.

[0098] In the power transmission coil TC1 (power reception coil RC1) of the first embodiment described above, the case where the power transmission coil TC1 is composed of two power transmission loop coils TL11 and TL12 has been described (see FIGS. 2 to 4). On the other hand, the power reception coil of the third embodiment described below includes a first power reception loop coil having the same configuration as the power transmission loop coil TL21 of the second embodiment, a second power reception loop coil having the same configuration as the power transmission loop coil TL22 of the second embodiment, and a coil for current adjustment (hereinafter referred to as "current adjustment coil") independent of the first power reception loop coil and the second power reception loop coil, which are laminated.

[0099] In the following description, the power receiving coil of the third embodiment will be mainly described. However, the power receiving coil of the third embodiment and the power transmitting coil of the third embodiment may have the same configuration. Further, in the following description, the same component numbers are assigned to the same components as those of the power receiving coil RC1 (i.e., the power transmitting coil TC1) of the first embodiment, and the detailed description thereof will be omitted.

[0100] First, the circuit configuration of the power receiving coil of the third embodiment will be described with reference to FIG. 11. As shown in FIG. 11, the power receiving coil RC3 of the third embodiment includes an external connection terminal O1 and an external connection terminal O2, two power receiving loop coils RL31 and RL32, two current adjustment coils RL33 and RL34, and a current adjustment capacitor Cp. In the following description, the current adjustment capacitor will be simply referred to as the "current adjustment capacitor". The current adjustment capacitor Cp corresponds to an example of the "capacitance means" of the present invention. In the above configuration, the external connection terminal O1 and the external connection terminal O2 are external connection terminals for connecting the power receiving coil RC3 to the power receiving unit RV, respectively. The power receiving loop coils RL31 and RL32 are connected in series to the external connection terminals O1 and O2 and are connected in parallel to each other. Further, the current adjustment coils RL33 and RL34 are insulated from the power receiving loop coils RL31 and RL32 and are connected in series by a connection terminal M3. The current adjustment capacitor Cp is connected to both ends of the current adjustment coils RL33 and RL34. Note that a current adjustment capacitor having the same configuration as the current adjustment capacitor Cp and the two current adjustment coils RL33 and RL34 may be provided in the power transmitting coil of the third embodiment that constitutes the power transmission system of the third embodiment together with the power receiving coil RC3. At this time, the current adjustment capacitor Cp and the current adjustment coils RL33 and RL34 mainly contribute to reducing impedance and improving transmission efficiency.

[0101] Next, the specific configuration of the power receiving coil RC3 of the third embodiment will be described with reference to FIGS. 12 to 14. At this time, the power receiving loop coil RL31 (corresponding to the first power receiving loop coil) of the third embodiment described below has basically the same configuration as the power transmission loop coil TL21 of the second embodiment except for the number of turns. Similarly, the power receiving loop coil RL32 (corresponding to the second power receiving loop coil) of the third embodiment has basically the same configuration as the power transmission loop coil TL22 of the second embodiment except for the number of turns.

[0102] That is, as shown in the plan view of FIG. 12(a), the power receiving coil RC3 of the third embodiment includes a power receiving loop coil RL31 formed by two parallel copper thin film lines RL311 and RL312, and a power receiving loop coil RL32 whose plan view is shown in FIG. 12(b). They are laminated in a direction perpendicular to the plane of FIG. 12 via an insulating film BF. Also, the centers of the windings of the copper thin film lines RL311 and RL312 and the centers of the windings of the copper thin film lines RL321 and RL322 (see FIG. 12(b)) are the same or substantially the same as each other.

[0103] As shown in Fig. 12(a), the power receiving loop coil RL31 is composed of copper thin film wires RL311 and RL312 wound in parallel with each other within the same layer as the power receiving coil RC3 (on the surface of the film BF illustrated in Fig. 12(a)). At one side of its outermost periphery (the center of the right side in the case shown in Fig. 12(a)), it has external connection terminals O1 and O2 for connecting the copper thin film wires RL311 and RL312 and connecting to the power transmission part TR. And in the power receiving loop coil RL31, the copper thin film wires RL311 and RL312 are wound counterclockwise in parallel four times (4 turns) from the external connection terminal O1 at their outermost periphery to their innermost periphery in Fig. 12(a), and further wound counterclockwise in parallel four times (4 turns) from the innermost periphery to the external connection terminal O2 in the same way. Also, the crossing parts in the winding of the copper thin film wires RL311 and RL312 are insulated from each other at seven locations (see Fig. 12(a)) by a laminated structure with an insulating layer sandwiched and electrically connected for each of the copper thin film wires RL311 and RL312 by vias VV, or a method using jumper wires, etc. Further, in each of the copper thin film wires RL311 and RL312, straight parts are provided at the upper side, lower side, left side, and right side in Fig. 12(a), respectively, and each straight part is connected by a substantially concentric arc-shaped curved part. Note that the width w31 of the copper thin film wire RL311 is wider toward the inner peripheral side of the power receiving coil RC3. This width w31 is the same for each straight part constituting the copper thin film wire RL311, and in each curved part connecting the straight parts, the width w31 is changed (i.e., changed to be wider toward the inner peripheral side of the power receiving coil RC3). On the other hand, the thickness of the copper thin film wire RL311 is the same throughout the entire circumference of the power receiving loop coil RL31. On the other hand, the width w32 of the copper thin film wire RL312 is also wider toward the inner peripheral side of the power receiving coil RC3 in the same way as the width w31. This width w32 is the same for each straight part constituting the copper thin film wire RL312, and in each curved part connecting the straight parts, the width w32 is changed (i.e., changed to be wider toward the inner peripheral side of the power receiving coil RC3). On the other hand, the thickness of the copper thin film wire RL312 is the same throughout the entire circumference of the power receiving loop coil RL31.With the above configuration, the width w30 of each winding as the power receiving loop coil RL31 (see Fig. 12(a)) also becomes wider toward the inner peripheral side of the power receiving coil RC3. And in the power receiving loop coil RL31, over its entire circumference, the width w32 of the copper thin film wire RL312 on the inner peripheral side in one winding is made wider than the width w31 of the copper thin film wire RL311 on the outer peripheral side in the same winding.

[0104] Next, the configuration of the power receiving loop coil RL32 laminated directly below the power receiving loop coil RL31 via the film BF will be described with reference to Fig. 12(b). Note that Fig. 12(b) is a plan view showing only the power receiving loop coil RL32 taken out. The overall shape of the power receiving loop coil RL32 is a substantially rectangular shape identical to the overall shape of the power receiving loop coil RL31.

[0105] As shown in its plan view in FIG. 12(b), the power receiving loop coil RL32 laminated on the power receiving loop coil RL31 with the film BF interposed therebetween is composed of a copper thin film wire RL321 and a copper thin film wire RL322 wound in parallel with each other within the same layer of the power receiving coil RC3 (the back surface of the film BF illustrated in FIG. 12(a)). At one side of its outermost peripheral portion (the center of the right side portion in the case shown in FIG. 12(b)), it has an external connection terminal O1 and an external connection terminal O2 for connecting the copper thin film wire RL321 and the copper thin film wire RL322 and connecting to the power transmission unit TR in parallel with the power receiving loop coil RL31. At this time, the external connection terminal O1 and the external connection terminal O2 are the same as the external connection terminal O1 and the external connection terminal O2 shown in FIG. 12(a). And the power receiving loop coil RL32 is configured such that the copper thin film wire RL321 and the copper thin film wire RL322 are wound counterclockwise in parallel four turns (4 turns) from the external connection terminal O1 at their outermost peripheral portion to their innermost peripheral portion in FIG. 12(b), and further wound counterclockwise in parallel four turns (4 turns) from the innermost peripheral portion to the external connection terminal O2 in the same manner. Also, the crossing portions in the winding of the copper thin film wire RL321 and the copper thin film wire RL322 are insulated from each other at seven locations (see FIG. 12(b)) by a laminated structure in which an insulating layer is interposed and the copper thin film wire RL321 and the copper thin film wire RL322 are electrically connected together by vias VV, or a method using jumper wires, etc. Further, in each of the copper thin film wire RL321 and the copper thin film wire RL322, straight portions are provided at the upper side portion, the lower side portion, the left side portion, and the right side portion in FIG. 12(b), and the respective straight portions are connected by substantially concentric arc-shaped curved portions. Note that the width w31 of the copper thin film wire RL321 is the same as the width w31 of the copper thin film wire RL311, and it becomes wider toward the inner peripheral side of the power receiving coil RC3. This width w31 is the same for each straight portion constituting the copper thin film wire RL321, and in each curved portion connecting the straight portions, the width w31 is changed (i.e., changed to be wider toward the inner peripheral side of the power receiving coil RC3). On the other hand, the thickness of the copper thin film wire RL321 is the same over the entire circumference of the power receiving loop coil RL32.On the other hand, the width w32 of the copper thin film line RL322 is the same as the width w32 of the copper thin film line RL312, and like the width w31, it becomes wider toward the inner peripheral side of the power receiving coil RC3. This width w32 is the same for each straight portion constituting the copper thin film line RL322, and in each curved portion connecting the straight portions, the width w32 is changed (i.e., changed so as to become wider toward the inner peripheral side of the power receiving coil RC3). On the other hand, the thickness of the copper thin film line RL322 is the same throughout the entire circumference of the power receiving loop coil RL32. With the above configuration, the width w30 (see FIG. 12(b)) of each winding as the power receiving loop coil RL32 also becomes wider toward the inner peripheral side of the power receiving coil RC3. And in the power receiving loop coil RL32, throughout its entire circumference, the width w32 of the copper thin film line RL322 on the inner peripheral side in one winding is made wider than the width w31 of the copper thin film line RL321 on the outer peripheral side in that one winding.

[0106] Next, regarding the configuration of the current adjustment coil RL33 further laminated directly below the power receiving loop coil RL32 via a film (made of the same material as the film BF shown in the figure) in the power receiving coil RC3 of the third embodiment, it will be described with reference to FIG. 13(a). Note that FIG. 13(a) is a plan view showing only the current adjustment coil RL33 taken out. The overall shapes of the current adjustment coil RL33 and the current adjustment coil RL34 described later are substantially rectangular shapes identical to the overall shapes of the power receiving loop coils RL31 and RL32, respectively.

[0107] As shown in the plan view in Fig. 13(a), the current adjustment coil RL33 laminated with a film sandwiched directly below the power receiving loop coil RL32 is composed of a copper thin film wire RL331 and a copper thin film wire RL332 wound in parallel with each other within the same layer of the power receiving coil RC3. The outermost peripheral end thereof serves as a connection terminal M3 for separately connecting the copper thin film wire RL331 and the copper thin film wire RL332 in series to the copper thin film wire RL341 and the copper thin film wire RL342 of the current adjustment coil RL34, which will be described with reference to Fig. 13(b). At this time, the copper thin film wires RL331 to RL342 correspond to an example of the "winding wire for adjustment" of the present invention. On the other hand, the innermost peripheral ends of the copper thin film wire RL331 and the copper thin film wire RL332 serve as a connection terminal M33 for connecting the copper thin film wire RL331 and the copper thin film wire RL332 and for connecting the current adjustment capacitor Cp. The current adjustment coil RL33 is configured such that the copper thin film wire RL331 and the copper thin film wire RL332 are wound eight times (8 turns) in parallel in the clockwise direction from the connection terminal M3 at the outermost peripheral portion thereof to the connection terminal M33 at the innermost peripheral portion thereof in Fig. 13(a). Further, in each of the copper thin film wire RL331 and the copper thin film wire RL332, straight portions are provided on the upper side portion, the lower side portion, the left side portion, and the right side portion in Fig. 13(a), respectively, and the respective straight portions are connected by substantially concentric arc-shaped curved portions. Also, the centers of winding of the copper thin film wire RL311 and the copper thin film wire RL312, the centers of winding of the copper thin film wire RL321 and the copper thin film wire RL322, and the centers of winding of the copper thin film wire RL331 and the copper thin film wire RL332 are the same as or substantially the same as each other. The width w31 of the copper thin film wire RL331 is the same as the width w31 of the copper thin film wire RL311 and the width w31 of the copper thin film wire RL321, and becomes wider toward the inner peripheral side of the power receiving coil RC3. This width w31 is the same in each straight portion constituting the copper thin film wire RL331, and in each curved portion connecting the straight portions, the width w31 is changed (i.e., changed so as to become wider toward the inner peripheral side of the power receiving coil RC3). On the other hand, the thickness of the copper thin film wire RL331 is the same over the entire circumference of the current adjustment coil RL33.On the other hand, the width w32 of the copper thin film line RL332 is the same as the width w32 of the copper thin film line RL312 of the power receiving loop coil RL31 shown in Fig. 12(a) and the width w32 of the copper thin film line RL322 of the power receiving loop coil RL32 shown in Fig. 12(b). Similar to the width w31 of the copper thin film line RL331, it becomes wider toward the inner peripheral side of the power receiving coil RC3. This width w32 is the same for each straight portion constituting the copper thin film line RL332, and in each curved portion connecting the straight portions, the width w32 is changed (i.e., changed so as to become wider toward the inner peripheral side of the power receiving coil RC3). On the other hand, the thickness of the copper thin film line RL332 is the same throughout the entire circumference of the current adjustment coil RL33. With the above configuration, the width w30 of each winding as the current adjustment coil RL33 (the same as the width w30 in the power receiving loop coil RL31 shown in Fig. 12(a) and the width w30 in the power receiving loop coil RL32 shown in Fig. 12(b). Refer to Fig. 13(a).) also becomes wider toward the inner peripheral side of the power receiving coil RC3. And in the current adjustment coil RL33, throughout its entire circumference, the width w32 of the copper thin film line RL332 on the inner peripheral side in one winding is made wider than the width w31 of the copper thin film line RL331 on the outer peripheral side in the same winding.

[0108] Next, regarding the configuration of the current adjustment coil RL34 further laminated directly below the current adjustment coil RL33 via a film (made of the same material as the film BF etc., not shown) in the power receiving coil RC3 of the third embodiment, it will be described with reference to Fig. 13(b). Note that Fig. 13(b) is a plan view showing only the current adjustment coil RL34 taken out.

[0109] As shown in its plan view in FIG. 13(b), the current adjustment coil RL34 laminated with a film sandwiched thereunder directly below the current adjustment coil RL33 is composed of a copper thin film wire RL341 and a copper thin film wire RL342 wound in parallel with each other within the same layer of the power receiving coil RC3. The outermost peripheral end thereof serves as the connection terminal M3 for separately connecting the copper thin film wire RL341 and the copper thin film wire RL342 in series to the copper thin film wire RL331 and the copper thin film wire RL332 of the current adjustment coil RL33, respectively. At this time, the connection terminal M3 is the same as the connection terminal M3 shown in FIG. 13(a). On the other hand, the innermost peripheral ends of the copper thin film wire RL341 and the copper thin film wire RL342 serve as the connection terminal M34 for connecting the copper thin film wire RL341 and the copper thin film wire RL342 and for connecting the current adjustment capacitor Cp. The current adjustment coil RL34 is configured such that the copper thin film wire RL341 and the copper thin film wire RL342 are wound in parallel eight times (8 turns) in the clockwise direction from the connection terminal M34 at their innermost peripheral portions to the connection terminal M3 at their outermost peripheral portions in FIG. 13(b). Further, in each of the copper thin film wire RL341 and the copper thin film wire RL342, straight portions are provided at the upper side portion, the lower side portion, the left side portion, and the right side portion in FIG. 13(b), respectively, and the respective straight portions are connected by substantially concentric arc-shaped curved portions. Also, the centers of winding of the copper thin film wire RL311 and the copper thin film wire RL312, the centers of winding of the copper thin film wire RL321 and the copper thin film wire RL322, the centers of winding of the copper thin film wire RL331 and the copper thin film wire RL332, and the centers of winding of the copper thin film wire RL341 and the copper thin film wire RL342 are the same as or substantially the same as each other. The width w31 of the copper thin film wire RL341 is the same as the width w31 of the copper thin film wire RL311, the width w31 of the copper thin film wire RL321, and the width w31 of the copper thin film wire RL331, and becomes wider toward the inner peripheral side of the power receiving coil RC3. This width w31 is the same in each straight portion constituting the copper thin film wire RL341, and in each curved portion connecting the straight portions, the width w31 is changed (i.e., changed so as to become wider toward the inner peripheral side of the power receiving coil RC3). On the other hand, the thickness of the copper thin film wire RL341 is the same throughout the entire circumference of the current adjustment coil RL34.On the other hand, the width w32 of the copper thin film line RL342 is the same as the width w32 of the copper thin film line RL312, the width w32 of the copper thin film line RL322, and the width w32 of the copper thin film line RL332. Similar to the width w31 of the copper thin film line RL341, it becomes wider toward the inner peripheral side of the power receiving coil RC3. This width w32 is the same for each straight portion constituting the copper thin film line RL342, and in each curved portion connecting the straight portions, the width w32 is changed (i.e., changed so as to become wider toward the inner peripheral side of the power receiving coil RC3). On the other hand, the thickness of the copper thin film line RL342 is the same throughout the entire circumference of the current adjustment coil RL34. With the above configuration, the width w30 of each winding as the current adjustment coil RL34 (the same as the width w30 in the power receiving loop coil RL31 shown in Fig. 12(a), the width w30 in the power receiving loop coil RL32 shown in Fig. 12(b), and the width w30 in the current adjustment coil RL33 shown in Fig. 13(a). Refer to Fig. 13(b).) also becomes wider toward the inner peripheral side of the power receiving coil RC3. And in the current adjustment coil RL34, throughout its entire circumference, the width w32 of the copper thin film line RL342 on the inner peripheral side in one winding is made wider than the width w31 of the copper thin film line RL341 on the outer peripheral side in the same winding.

[0110] Due to the configurations of the current adjustment coil RL33 and the current adjustment coil RL34, and the power receiving loop coil RL31 and the power receiving loop coil RL32 as described above, the total number of turns (sixteen turns) of the serially connected current adjustment coils TL33 and RL34 is an integer multiple (two times) of the total number of (electrical) turns (eight turns) of the parallel connected power receiving loop coils TL31 and TL32.

[0111] Next, the positional relationship among the power receiving loop coil RL31 composed of the copper thin film lines RL311 and RL312, the power receiving loop coil RL32 composed of the copper thin film lines RL321 and RL322, the current adjustment coil RL33 composed of the copper thin film lines RL331 and RL332, and the current adjustment coil RL34 composed of the copper thin film lines RL341 and RL342 will be described with reference to FIG. 14. Note that FIG. 14 is a plan view showing the overlapping situation of the power receiving loop coil RL31, the power receiving loop coil RL32, the current adjustment coil RL33, and the current adjustment coil RL34. The power receiving loop coil RL31 is shown by a solid line, the power receiving loop coil RL32 laminated via a film BF (not shown in FIG. 14) directly below it is shown by a dashed line, the current adjustment coil RL33 laminated via a film directly below the power receiving loop coil RL32 is shown by a one-dot chain line, and the current adjustment coil RL34 laminated via a film directly below the current adjustment coil RL33 is shown by a two-dot chain line, respectively.

[0112] As shown by the solid line in FIG. 14, in the power receiving loop coil RL31 composed of the copper thin film lines RL311 and RL312 wound in parallel, among the four curved portions included in one winding, only in one curved portion (for example, the curved portion in the lower right corner in FIG. 14), the positions of the straight portions of the copper thin film lines RL311 and RL312 shift to the outer peripheral side or the inner peripheral side by one pitch PT3 (see FIGS. 12(b) and 14) in each winding (that is, the winding transitions to the outer peripheral side or the inner peripheral side), and the copper thin film lines RL311 and RL312 are wound counterclockwise from the external connection terminal O1 to the external connection terminal O2. As a result, the curved portion where the winding of the power receiving loop coil RL31 transitions to the outer peripheral side or the inner peripheral side by one pitch PT3 is included in, for example, the seven-curved portion group in the lower right corner in FIG. 14.

[0113] On the other hand, in the power receiving loop coil RL32 composed of the copper thin film wires RL321 and RL322 that constitute the power receiving loop coil RL31 and the copper thin film wires RL321 and RL322 connected to the external connection terminals O1 and O2 at their outermost peripheral portions respectively, as shown by the dashed line in FIG. 14, only in one of the four curved portions included in one winding (for example, the curved portion in the lower right corner portion in FIG. 14), the positions of the straight portions of the copper thin film wires RL321 and RL322 are shifted to the outer peripheral side or the inner peripheral side by one pitch PT3 in each winding (that is, the winding transitions to the outer peripheral side or the inner peripheral side), and the copper thin film wires RL321 and RL322 are wound counterclockwise (that is, in the same direction as the power receiving loop coil RL31). As a result, the curved portion in the power receiving loop coil RL32 where the winding transitions to the outer peripheral side or the inner peripheral side by one pitch PT3 is included in, for example, the four curved portion groups in the lower right corner portion in FIG. 14. And the outermost peripheral ends on the right side in FIG. 14 of the power receiving loop coil RL31 and the power receiving loop coil RL32 are respectively connected to the external connection terminals O1 and O2.

[0114] Furthermore, in the current adjustment coil RL33 in which the copper thin film wires RL331 and RL332 are wound in parallel from the outer periphery to the inner periphery, as shown by the one-dot chain line in FIG. 14, only in one of the four curved portions included in one winding (for example, the curved portion in the lower right corner portion in FIG. 14), the positions of the straight portions of the copper thin film wires RL331 and RL332 are shifted to the inner peripheral side by one pitch PT3 in each winding (that is, the winding transitions to the inner peripheral side), and the copper thin film wires RL331 and RL332 are wound clockwise. As a result, the curved portion in the current adjustment coil RL33 where the winding transitions to the inner peripheral side by one pitch PT3 is, for example, seven curved portion groups arranged from the outer peripheral side to the inner peripheral side in the lower right corner portion in FIG. 14. And the outermost peripheral end of the current adjustment coil RL33 is the connection terminal M3, and its innermost peripheral end is the connection terminal M33.

[0115] Finally, in the current adjustment coil RL34 formed by winding the copper thin film wires RL341 and RL342 in parallel from the inner circumference to the outer circumference, as shown by the two-dot chain line in Fig. 14, among the four curved portions included in one winding, only one curved portion (for example, the curved portion in the lower right corner in Fig. 14) has the positions of the straight portions of the copper thin film wire RL341 and the copper thin film wire RL342 shifted by one pitch PT3 in the winding of each, so that the winding shifts to the outer circumference side (that is, the winding transitions to the outer circumference side). The copper thin film wire RL341 and the copper thin film wire RL342 are wound clockwise. As a result, the curved portion where the winding of the current adjustment coil RL34 transitions to the outer circumference side by one pitch PT3 is, for example, seven curved portion groups arranged from the outer circumference side to the inner circumference side in the lower right corner portion in Fig. 14. And the innermost peripheral end portion of the current adjustment coil RL34 is connected to the connection terminal M34, and its outermost peripheral end portion is connected to the connection terminal M3.

[0116] The power receiving loop coils RL31, RL32, current adjustment coils RL33 and RL34, each having the above-described shape, are laminated as shown in FIG. 14. Thus, the positions of the copper thin film wires RL311, RL312, RL321, RL322, RL331, RL332, RL341 and RL342, as seen from the center of the power receiving coil RC3, are the same except for the curved portions where the respective windings transition, the external connection terminals O1 and O2, the connection terminal M3, and the connection portions to the connection terminals M33 and M34. Similarly, the positions of the copper thin film wires RL312, RL322, RL332 and RL342, as seen from the center of the power receiving coil RC3, are the same except for the curved portions where the respective windings transition, the external connection terminals O1 and O2, the connection terminal M3, and the connection portions to the connection terminals M33 and M34. Therefore, as the power receiving coil RC3, at least each straight portion of the power receiving loop coil RL31, at least each straight portion of the power receiving loop coil RL32, at least each straight portion of the current adjustment coil RL33, and at least each straight portion of the current adjustment coil RL34 overlap, and the power receiving loop coil RL31 to the current adjustment coil RL34 are laminated with a film BF or the like interposed therebetween. As a result, the copper thin film wires RL311, RL312, RL321 and RL322 are wound counterclockwise in the order of the outermost peripheral portion of the power receiving loop coil RL31 and the outermost peripheral portion (external connection terminal O1) of the power receiving loop coil RL32 → their innermost peripheral portions → the external connection terminal O2 of their outermost peripheral portions. Then, the copper thin film wires RL341 and RL342 of the current adjustment coil RL34 are wound clockwise from the connection terminal M34 to the connection terminal M3 at the outermost peripheral portion thereof. Further, the copper thin film wires RL331 and RL332 of the current adjustment coil RL33 are wound clockwise from the connection terminal M3 to the connection terminal M33 at the innermost peripheral portion thereof, and a current adjustment capacitor Cp is connected to the connection terminals M33 and M34. The optimum value of the capacitance of this current adjustment capacitor Cp will be described later as a third embodiment.With the above structure, as the power receiving coil RC3 of the third embodiment, a current flows between the external connection terminal O1 and the external connection terminal O2 in the power receiving loop coils RL31 and RL32, and the current value is adjusted by the current adjustment coils RL33 and RL34 and the current adjustment capacitor Cp.

[0117] Note that the manufacturing method of the power transmission coil and the power receiving coil RC3 of the third embodiment is basically the same as the above manufacturing method of the power transmission coil TC1 and the power receiving coil RC1 of the first embodiment, so the detailed description is omitted. Third embodiment

[0118] Next, in the power transmission system using the power receiving coil RC3 of the third embodiment having the configuration shown in FIGS. 12 to 14, the measurement results (simulation results) such as impedance when the configuration of the power receiving coil is changed will be described as the third embodiment using Table 1 above. Also, in the power transmission system using the power receiving coil RC3, the experimental results (simulation results) for optimizing the capacitance of the current adjustment capacitor Cp will also be described as the third embodiment using FIGS. 15 and 16. In FIG. 15, the horizontal axis represents the capacitance of the current adjustment capacitor Cp, and the vertical axis represents the transmission efficiency as the power receiving coil RC3. In FIG. 16, the horizontal axis represents the capacitance of the current adjustment capacitor Cp, and the vertical axis represents the losses (copper losses) in the current adjustment coil RL33 (current adjustment coil RL34) and the power receiving loop coils RL31 (power receiving loop coil RL32), respectively.

[0119] Here, as exemplified in Table 1, the third conventional example, which is a comparison target with the above-described third embodiment, has a configuration similar to that of the power receiving coil RC2 (power transmission coil TC2) of the second embodiment for portions other than the current adjustment coils RL33 and RL34 with respect to the power receiving coil RC3 of the third embodiment. As a result, in the power receiving coil of the third conventional example, the total number of turns (sixteen turns) of the serially connected current adjustment coils RL33 and RL34 is not an integral multiple of the number of turns (ten turns) of the power transmission loop coil and the power receiving loop coil connected in parallel, etc. Therefore, the positions of the copper thin film wires constituting the power receiving loop coil, etc. and the current adjustment coils do not overlap when viewed from their centers.

[0120] In addition, other specifications of the power receiving coil RC3 of the third embodiment and the power receiving coil of the third conventional example used in the experiment of the third embodiment are as follows.

[0121] · Size of the power receiving coil RC3 and the power receiving coil of the third conventional example: long side 266 millimeters × short side 160 millimeters · Pitch PT3 (see FIGS. 12(b) and 14): 5.0 millimeters (outermost periphery) to 8.0 millimeters (innermost periphery) · Thickness of the copper thin film wire in the copper thin film wires RL311, etc.: 0.2 millimeters · Distance between the power transmission coil and the power receiving coil: 40 millimeters · Ferrite sheets having the same thickness as the power transmission coil and the power receiving coil are provided on the surfaces opposite to the opposing surfaces of the power transmission coil and the power receiving coil, respectively.

[0122] And as shown by hatching in Table 1, at the frequency (85 kilohertz) used for power transmission by the power transmission system of the third embodiment, it can be seen that the use of the power receiving coil RC3 of the third embodiment results in better performance in terms of impedance and Q value than when using the power transmission coil and the power receiving coil of the third conventional example. That is, it can be said that a configuration such as the above-described power receiving coil RC3 (a configuration in which the copper thin film wires constituting each overlap) is more preferable for reducing impedance and inductance and improving the Q value.

[0123] Also, as shown in FIGS. 15 and 16 respectively, at the above frequency used for power transmission by the power transmission system of the third embodiment, when the capacitance of the current adjustment capacitor Cp is 20 μF or more, the transmission efficiency decreases, while the copper loss in the power receiving loop coil RL31 (power receiving loop coil RL32) decreases. From the above, it can be said that it is desirable that the capacitance of the current adjustment capacitor Cp at the above frequency be 20 μF or less.

[0124] As described above respectively, according to the power transmission using the power transmission system of the third embodiment including the power receiving coil RC3 of the third embodiment, in addition to the effects of the power transmission using the power transmission system S of the first embodiment and the power transmission system of the second embodiment, it further includes a current adjustment coil RL33 and a current adjustment coil RL34, and the overall shape in plan view is the same polygon (rectangle) as the overall shape in plan view of the power receiving loop coil RL31 and the power receiving loop coil RL32, and the position of at least the straight line portion constituting the copper thin film line TL311 etc. as seen from the center of the power receiving coil RC3 and the position of at least the straight line portion constituting the corresponding copper thin film line TL331 etc. as seen from the center coincide in plan view. Therefore, even when the current adjustment coil RL33 and the current adjustment coil RL34 are provided, the impedance can be reduced, and both weight reduction and cost reduction, and improvement of transmission efficiency and prevention of increase in operating temperature can be achieved.

[0125] Also, since the current adjustment coil RL33 and the current adjustment coil RL34 are laminated at the same position as the power receiving loop coil RL31 and the power receiving loop coil RL32, it is possible to effectively adjust the current flowing through the power receiving loop coil RL31 and the power receiving loop coil RL32, and at the same time, both weight reduction and cost reduction, and improvement of transmission efficiency and prevention of increase in operating temperature can be achieved.

[0126] Furthermore, the current adjustment coil RL33 and the current adjustment coil RL34 are connected in series at their outermost peripheral ends, and a current adjustment capacitor Cp is connected to the innermost peripheral portion thereof, and its capacitance is optimized for the frequency of power transmission (set to 20 microfarads or less). Therefore, even when the current adjustment capacitor Cp is provided, it is possible to achieve both weight reduction and cost reduction, and improvement of transmission efficiency and prevention of an increase in operating temperature.

[0127] (D) Fourth Embodiment Next, a fourth embodiment of the present invention will be described with reference to FIGS. 17 and 18. FIGS. 17 and 18 are plan views showing the coil structures of the fourth embodiment, respectively.

[0128] In the power transmission coil TC1 etc. (power reception coil RC1 etc.) of the first to third embodiments described above, for example, in only one of the four curved portions included in one winding of the power transmission loop coil TL11, the position of the straight portion of the power transmission loop coil TL11 is shifted to the outer peripheral side or the inner peripheral side by one pitch in the winding thereof (that is, the winding transitions to the outer peripheral side or the inner peripheral side). The copper thin film wires TL111 and TL112 constituting the power transmission loop coil TL11 are wound (see, for example, FIG. 4 or FIG. 10(b)). On the other hand, in the power transmission coil (and power reception coil) of the fourth embodiment described below, in only one of the four straight portions included in one winding of the power transmission loop coil (and power reception loop coil) that are laminated to form the power transmission coil (and power reception coil), the position of the straight portion of the power transmission loop coil (and the power reception loop coil) is shifted to the outer peripheral side or the inner peripheral side by one pitch in the winding thereof (that is, the winding transitions to the outer peripheral side or the inner peripheral side). The copper thin film wires constituting the power transmission loop coil (and the power reception loop coil) are wound. As a result, in the power transmission coil (and power reception coil) of the fourth embodiment, the overlapping portion of each winding of the laminated power transmission loop coils (and power reception loop coils) that coincides in position when viewed from the center of the power transmission coil (power reception coil) in a plan view is configured to be wider.

[0129] Note that the configurations of the power transmission coil of the fourth embodiment and the power reception coil of the fourth embodiment are basically the same, and the configurations of the power reception loop coil in the power reception coil of the fourth embodiment and the power transmission loop coil in the power transmission coil of the fourth embodiment are the same. Therefore, in the following description, only the configuration of the power transmission coil of the fourth embodiment will be described. At this time, for the same component members as those of the power transmission coil TC1 of the first embodiment, the same member numbers will be assigned and the detailed description will be omitted.

[0130] That is, as shown in its plan view in Fig. 17(a), the power transmission coil TC4 of the fourth embodiment includes a power transmission loop coil TL41 formed of a copper thin film wire TL411, and a power transmission loop coil TL42 whose plan view is shown in Fig. 17(b), which are laminated in a direction perpendicular to the paper surface of Fig. 17 via an insulating film BF. Also, the center of winding of the copper thin film wire TL411 constituting the power transmission loop coil TL41 and the center of winding of the copper thin film wire TL421 (see Fig. 17(b)) constituting the power transmission loop coil TL42 are made to be the same or substantially the same as each other.

[0131] As shown in Fig. 17(a), the power transmission loop coil TL41 is composed of a copper thin film wire TL411 wound within one layer of the power transmission coil TC4 (on the surface of the film BF illustrated in Fig. 17(a)). On one side of its outermost periphery, it has an external connection terminal O1 for connecting the copper thin film wire TL411 to a power transmission part (not shown). The power transmission loop coil TL41 is configured such that the copper thin film wire TL411 is wound six times (6 turns) clockwise from its outermost periphery in Fig. 17(a). The outer peripheral end of the copper thin film wire TL411 (the center of the upper side in the case shown in Fig. 17(a)) is connected to the external connection terminal O1. Also, the inner peripheral end of the copper thin film wire TL411 (the end on the center side of the power transmission coil TC4 in the case shown in Fig. 17(a)) is connected to the copper thin film wire that forms the power transmission loop coil TL42 formed on the back surface of the film BF through a via V11 that penetrates the film BF. Note that the copper thin film wire TL411 has the same width and the same thickness over the entire circumference of the power transmission loop coil TL41. Further, in the copper thin film wire TL411, straight portions are provided on the upper side, lower side, left side, and right side in Fig. 17(a), respectively, and each straight portion is connected by a substantially concentric arc-shaped curved portion.

[0132] Next, the configuration of the power transmission loop coil TL42 laminated directly below the power transmission loop coil TL41 via the film BF will be described with reference to Fig. 17(b). Note that Fig. 17(b) is a plan view showing only the power transmission loop coil TL42 taken out.

[0133] As shown in its plan view in Fig. 17(b), the power transmission loop coil TL42 laminated on the power transmission loop coil TL41 with the film BF sandwiched therebetween is composed of, for example, a copper thin film wire TL421. At this time, as described above, the center of winding of the copper thin film wire TL421 that forms the power transmission loop coil TL42 and the center of winding of the copper thin film wire TL411 that forms the power transmission loop coil TL41 are the same or substantially the same as each other. Further, the overall shape of the power transmission loop coil TL42 is a substantially rectangular shape that is the same as the overall shape of the power transmission loop coil TL41.

[0134] As shown in FIG. 17(b), the power transmission loop coil TL42 is composed of the copper thin film wire TL421 wound within another layer of the power transmission coil TC4 (the back surface of the film BF illustrated in FIG. 17(a)). On one side of its outermost periphery, it has an external connection terminal O2 for connecting the copper thin film wire TL421 to the power transmission part (not shown in the figure). The power transmission loop coil TL42 is configured such that the copper thin film wire TL421 is wound six times (6 turns) in the clockwise direction from its innermost periphery in FIG. 17(b), and the outer peripheral end of the copper thin film wire TL421 (the center of the upper side in the case shown in FIG. 17(b)) is connected to the external connection terminal O2. On the other hand, the inner peripheral end of the copper thin film wire TL421 (the center side end of the power transmission coil TC4 in the case shown in FIG. 17(b)) is connected to the copper thin film wire TL411 of the power transmission loop coil TL41 by the via V11. The copper thin film wire TL421 has the same width and the same thickness over the entire circumference of the power transmission loop coil TL42. Further, in the copper thin film wire TL421, straight portions are provided on the upper side, lower side, left side, and right side in FIG. 17(b), respectively, and each straight portion is connected by a substantially concentric arc-shaped curved portion.

[0135] Next, the positional relationship between the power transmission loop coil TL41 composed of the copper thin film wire TL411 and the power transmission loop coil TL42 composed of the copper thin film wire TL421 will be described with reference to FIG. 18. FIG. 18 is a plan view showing the overlapping situation of the power transmission loop coil TL41 and the power transmission loop coil TL42. The power transmission loop coil TL41 (copper thin film wire TL411) is shown by a solid line, and the power transmission loop coil TL42 (copper thin film wire TL421) laminated via the film BF (not shown in FIG. 18) directly below it is shown by a dashed line.

[0136] As shown by the solid line in Fig. 18, the power transmission loop coil TL41 is composed of a copper thin film wire TL411 wound from the outer periphery toward the inner periphery, and at its innermost peripheral portion, it is connected to a copper thin film wire TL421 that constitutes the power transmission loop coil TL42 by a via V11. In the power transmission loop coil TL41, among the four straight portions included in one winding, only one straight portion (for example, the upper side portion in Fig. 18) is such that the position of the straight portion is shifted inward by one pitch PT4 (see Figs. 17(a) and 18) in the winding of the copper thin film wire TL411 (that is, the winding transitions to the inner peripheral side), and the copper thin film wire TL411 is wound clockwise. As a result, the straight portion in the power transmission loop coil TL41 where the winding transitions inward by one pitch PT4 is, for example, six straight portions LA41 arranged from the outer peripheral side to the inner peripheral side at the upper side portion in Figs. 17(a) and 18.

[0137] On the other hand, in the power transmission loop coil TL42 formed by winding the copper thin film wire TL421, which is connected to the copper thin film wire TL411 constituting the power transmission loop coil TL41 by the via V11, at its innermost peripheral portion, from the inner periphery toward the outer periphery, as shown by the dashed line in Fig. 18, among the four straight portions included in one winding, only one straight portion (for example, the upper side portion in Fig. 18) is such that the position of the straight portion is shifted outward by one pitch PT4 (see Figs. 17(b) and 18) in the winding of the copper thin film wire TL421 (that is, the winding transitions to the outer peripheral side), and the copper thin film wire TL421 is wound clockwise (that is, in the same direction as the power transmission loop coil TL41). As a result, the straight portion in the power transmission loop coil TL42 where the winding transitions outward by one pitch PT4 is, for example, six straight portions LA42 arranged from the inner peripheral side to the outer peripheral side at the upper side portion in Figs. 17(b) and 18. And the outermost peripheral portion of the upper side in Fig. 18 of the power transmission loop coil TL41 is connected to an external connection terminal O1 having a shape protruding outward, and the outermost peripheral portion of the right side in Fig. 18 of the power transmission loop coil TL42 is connected to an external connection terminal O2 having a shape protruding outward.

[0138] The power transmission loop coil TL41 and the power transmission loop coil TL42 each having the above-described shape are laminated as shown in FIG. 18. Thus, the positions of the copper thin film line TL411 and the copper thin film line TL421 as viewed from the center of the power transmission coil TC4 are the same except for the straight portions where each winding transitions and the connection portions to the external connection terminal O1 and the external connection terminal O2. Therefore, as the power transmission coil TC4, the straight portions (excluding the winding transition portions) and the curved portions of the power transmission loop coil TL41 and the straight portions (excluding the winding transition portions) and the curved portions of the power transmission loop coil TL42 are all overlapped, and the power transmission loop coil TL41 and the power transmission loop coil TL42 are laminated with the film BF interposed therebetween. As a result, with respect to the clockwise winding from the outermost peripheral portion (external connection terminal O1) to the innermost peripheral portion of the power transmission loop coil TL41, the power transmission loop coil TL42 is connected at the innermost peripheral portion so as to have the same winding direction, and while maintaining the winding direction, the power transmission loop coil TL42 is wound from the innermost peripheral portion to the outermost peripheral portion. With this structure, as the power transmission coil TC4 of the fourth embodiment, a current flows in the clockwise direction from the outermost peripheral portion to the innermost peripheral portion in the power transmission loop coil TL41, and the current flows in the same clockwise direction from the innermost peripheral portion to the outermost peripheral portion in the power transmission loop coil TL42.

[0139] Note that the manufacturing method of the power transmission coil TC4 (and the power reception coil) of the fourth embodiment is basically the same as the above-described manufacturing method of the power transmission coil TC1 and the power reception coil RC1 of the first embodiment, and thus detailed description thereof is omitted. Fourth Example

[0140] Next, regarding the results (simulation results) of measuring the Q value and the impedance of the power transmission coil TC4 (or the power reception coil) by changing the power transmission frequency of the power transmission system using the power transmission coil TC4 (or the power reception coil) having the configuration shown in FIGS. 17 and 18 in comparison with the power transmission coil (power reception coil) of the fourth comparative example, the fourth embodiment will be described with reference to FIGS. 19 to 21. Note that FIGS. 19 and 20 are plan views showing the structure of the coil of the fourth comparative example, and FIG. 21 is a diagram showing the effect of the structure of the power transmission coil TC4 (or the power reception coil) of the fourth embodiment.

[0141] Here, before describing the above-described fourth embodiment, the configuration of the power transmission coil or the power reception coil of the fourth comparative example, which is the comparison target, will be described in outline with reference to FIGS. 19 and 20. Note that the power transmission coil and the power reception coil of the fourth comparative example basically have the same configuration. Therefore, in the following description, the structure of the power transmission coil of the fourth comparative example will be described. FIGS. 19 and 20 are plan views showing the structure of the power transmission coil of the fourth comparative example when viewed from the same perspective as the power transmission coil TC4 of the fourth embodiment. At this time, in FIGS. 19 and 20, the same members as those of the power transmission coil TC4 of the fourth embodiment are given the same member numbers, and detailed descriptions thereof are omitted.

[0142] As shown in the plan view of FIG. 19(a), the power transmission coil TC4X of the fourth comparative example includes a power transmission loop coil TL4X formed of a copper thin film wire TL4X1 and a power transmission loop coil TL4Y (not shown in FIG. 19(a)), which are laminated in a direction perpendicular to the plane of FIG. 19 via an insulating film BF similar to the power transmission coil TC4 of the fourth embodiment. At this time, the center of winding of the copper thin film wire TL4X1 constituting the power transmission loop coil TL4X and the center of winding of a copper thin film wire (to be described later) constituting the power transmission loop coil TL4Y are the same as or substantially the same as each other.

[0143] As shown in FIG. 19(a), the power transmission loop coil TL4X is composed of a copper thin film wire TL4X1 wound within one layer of the power transmission coil TC4X (on the surface of the film BF illustrated in FIG. 19(a)). It has an external connection terminal O1 for connecting the copper thin film wire TL4X1 to a power transmission unit (not shown) at one side of its outermost periphery. The power transmission loop coil TL4X is configured such that the copper thin film wire TL4X1 is wound six times (6 turns) clockwise from its outermost periphery in FIG. 19(a), and the outer peripheral end portion of the copper thin film wire TL4X1 (the center of the upper side portion in the case shown in FIG. 19(a)) is connected to the external connection terminal O1. Also, the inner peripheral end portion of the copper thin film wire TL4X1 (the end portion on the center side of the power transmission coil TC4X in the case shown in FIG. 19(a)) is connected to the copper thin film wire constituting the power transmission loop coil TL4Y formed on the back surface of the film BF through a via V11 that penetrates the film BF. Note that the copper thin film wire TL4X1 has the same width and the same thickness over the entire circumference of the power transmission loop coil TL4X. Further, in the copper thin film wire TL4X1, straight portions are provided at the upper side portion, lower side portion, left side portion, and right side portion in FIG. 19(a), respectively, and each straight portion is connected by a substantially concentric arc-shaped curved portion.

[0144] Next, the configuration of the power transmission loop coil TL4Y laminated directly below the power transmission loop coil TL4X via the film BF will be described with reference to FIG. 19(b). Note that FIG. 19(b) is a plan view showing only the power transmission loop coil TL4Y taken out.

[0145] As shown in its plan view in FIG. 19(b), the power transmission loop coil TL4Y laminated on the power transmission loop coil TL4X with the film BF interposed therebetween is composed of a copper thin film wire TL4Y1. At this time, the center of winding of the copper thin film wire TL4Y1 constituting the power transmission loop coil TL4Y and the center of winding of the copper thin film wire TL4X1 constituting the power transmission loop coil TL4X are the same or substantially the same as each other. Further, the overall shape of the power transmission loop coil TL4Y is a substantially rectangular shape same as the overall shape of the power transmission loop coil TL4X.

[0146] As shown in FIG. 19(b), the power transmission loop coil TL4Y is composed of the copper thin film wire TL4Y1 wound within another layer of the power transmission coil TC4X (the back surface of the film BF illustrated in FIG. 19(a)). On one side of its outermost periphery, it has an external connection terminal O2 for connecting the copper thin film wire TL4Y1 to a power transmission part (not shown). The power transmission loop coil TL4Y is configured such that the copper thin film wire TL4Y1 is wound six times (6 turns) clockwise from its innermost periphery in FIG. 19(b), and the outer peripheral end of the copper thin film wire TL4Y1 (the center of the upper side in the case shown in FIG. 19(b)) is connected to the external connection terminal O2. On the other hand, the inner peripheral end of the copper thin film wire TL4Y1 (the end on the center side of the power transmission coil TC4X in the case shown in FIG. 19(b)) is connected to the copper thin film wire TL4X1 of the power transmission loop coil TL4X by the via V11. The copper thin film wire TL4Y1 has the same width and the same thickness over the entire circumference of the power transmission loop coil TL4Y. Further, in the copper thin film wire TL4Y1, straight portions are provided on the upper side, lower side, left side, and right side in FIG. 19(b), respectively, and each straight portion is connected by a substantially concentric arc-shaped curved portion.

[0147] Next, the positional relationship between the power transmission loop coil TL4X composed of the copper thin film wire TL4X1 and the power transmission loop coil TL4Y composed of the copper thin film wire TL4Y1 will be described with reference to FIG. 20. FIG. 20 is a plan view showing the overlapping situation of the power transmission loop coil TL4X and the power transmission loop coil TL4Y. The power transmission loop coil TL4X is shown by a solid line, and the power transmission loop coil TL4Y laminated via the film BF (not shown in FIG. 20) directly below it is shown by a dashed line.

[0148] As shown by the solid line in Fig. 20, the power transmission loop coil TL4X is composed of a copper thin film wire TL4X1 wound from the outer periphery toward the inner periphery, and at its innermost periphery, it is connected by a via V11 to a copper thin film wire TL4Y1 that forms a power transmission loop coil TL4Y. In the power transmission loop coil TL4X, only one of the four curved portions included in one winding (for example, the curved portion in the upper left corner in Fig. 20) is such that the position of the straight portion of the copper thin film wire TL4X1 is shifted inward by one pitch PT4 in the winding of the copper thin film wire TL4X1 (that is, the winding transitions to the inner periphery side), and the copper thin film wire TL4X1 is wound clockwise. As a result, the curved portion in the power transmission loop coil TL4X where the winding transitions to the inner periphery side by one pitch PT4 is, for example, six curved portions CV4X arranged from the outer periphery side to the inner periphery side in the upper left corner portions in Figs. 19(a) and 20.

[0149] On the other hand, in the power transmission loop coil TL4Y formed by winding the copper thin film wire TL4Y1 connected to the innermost periphery of the copper thin film wire TL4X1 that forms the power transmission loop coil TL4X and the via V11 from the inner periphery toward the outer periphery, as shown by the dashed line in Fig. 20, only one of the four curved portions included in one winding (for example, the curved portion in the upper left corner in Fig. 20) is such that the position of the straight portion of the copper thin film wire TL4Y1 is shifted outward by one pitch PT4 in the winding of the copper thin film wire TL4Y1 (that is, the winding transitions to the outer periphery side), and the copper thin film wire TL4Y1 is wound clockwise. As a result, the curved portion in the power transmission loop coil TL4Y where the winding transitions to the outer periphery side by one pitch PT4 is, for example, six curved portions CV4Y arranged from the inner periphery side to the outer periphery side in the upper left corner portions in Figs. 19(b) and 20. And the outermost periphery of the upper side in Fig. 20 of the power transmission loop coil TL4X is connected to an external connection terminal O1 having a shape protruding outward, and the outermost periphery of the upper side in Fig. 20 of the power transmission loop coil TL4Y is connected to an external connection terminal O2 having a shape protruding outward.

[0150] The power transmission loop coil TL4X and the power transmission loop coil TL4Y each having the above-described shape are laminated as shown in FIG. 20. As a result, the positions of the copper thin film wire TL4X1 and the copper thin film wire TL4Y1 as viewed from the center of the power transmission coil TC4X are different at two curved portions shown in FIG. 20 and at the connection portions to the external connection terminal O1 and the external connection terminal O2. Therefore, as the power transmission coil TC4X, the power transmission loop coil TL4X and the power transmission loop coil TL4Y are laminated with a film BF sandwiched therebetween in a state where there are more non-overlapping portions than the power transmission coil TC4 of the fourth embodiment. Thereby, with respect to the clockwise winding from the outermost peripheral portion (external connection terminal O1) to the innermost peripheral portion of the power transmission loop coil TL4X, the power transmission loop coil TL4Y is connected at the innermost peripheral portion so as to have the same winding direction, and while maintaining the winding direction, the power transmission loop coil TL4Y is wound from the innermost peripheral portion to the outermost peripheral portion. With this structure, as the power transmission coil TC4X of the fourth comparative example, a current flows in the clockwise direction from the outermost peripheral portion to the innermost peripheral portion in the power transmission loop coil TL4X, and the current flows in the same clockwise direction from the innermost peripheral portion to the outermost peripheral portion in the power transmission loop coil TL4Y.

[0151] The other specifications of the power transmission coil TC4 of the fourth embodiment and the power transmission coil TC4X of the fourth comparative example used in the experiment of the fourth example are as follows. In the following description, the specifications of the power transmission coil TC4 and the power transmission coil TC4X will be described. However, the specifications of the power receiving coil of the fourth embodiment used in the experiment are the same as those of the power transmission coil TC4, and the specifications of the power receiving coil of the fourth comparative example are the same as those of the power transmission coil TC4X.

[0152] · Size of the power transmission coil TC4 (and the power receiving coil of the fourth embodiment) and the power transmission coil TC4X (and the power receiving coil of the fourth conventional example): 160 millimeters × 260 millimeters · Pitch PT4: 8 millimeters · Thickness of the copper thin film wire in the copper thin film wire TL411 etc.: 0.2 millimeters

[0153] As shown in FIG. 21, in the vicinity of the frequency (85 kHz) used for power transmission by the power transmission system, when using the power transmission coil TC4 and the power receiving coil of the fourth embodiment, the impedance is lower than that when using the power transmission coil TC4X and the power receiving coil of the fourth comparative example. Therefore, good characteristics are obtained for the Q value.

[0154] As described above, according to the power transmission using the power transmission system including the power transmission coil TC4 of the fourth embodiment and the power receiving coil of the fourth embodiment, the overall planar shapes of the power transmission loop coils TL41 and TL42 are substantially the same rectangle as each other, and the position of each winding of the power transmission coil TC4 of the power transmission loop coil TL41 as seen from the center of the power transmission coil TC4 and the position of each winding of the power transmission coil TC4 of the power transmission loop coil TL42 as seen from the center of the power transmission coil TC4 coincide in plan view (see FIG. 18). Therefore, it is possible to reduce the impedance due to the so-called skin effect or proximity effect caused by configuring the power transmission coil TC4 and the power receiving coil of the fourth embodiment with a copper thin film wire for weight reduction and cost reduction, and it is possible to achieve both weight reduction and cost reduction, and improvement of transmission efficiency and prevention of an increase in the operating temperature.

[0155] (E) Fifth Embodiment Next, a fifth embodiment of the present invention will be described with reference to FIGS. 22 and 23. FIGS. 22 and 23 are plan views showing the structures of the coils of the fifth embodiment, respectively.

[0156] In the power transmission coil TC1 etc. (power reception coil RC1 etc.) of the first to fourth embodiments described above, for example, the position where the winding of the power transmission loop coil TL11 transitions by one pitch and the position where the winding of the power transmission loop coil TL12 transitions by one pitch are different when viewed from the center of the power transmission coil TC1. The copper thin film wires TL111 and TL112 constituting the power transmission loop coil TL11 and the copper thin film wires TL121 and TL122 constituting the power transmission loop coil TL12 are wound respectively (see, for example, FIG. 4 or FIG. 10(b)). In contrast, in the power transmission coil (and power reception coil) of the fifth embodiment described below, among the four curved portions included in one winding of the power transmission loop coil (and power reception loop coil) that are laminated with each other to form the power transmission coil (and power reception coil), only in one of the curved portions, the position of the straight portion of the power transmission loop coil (and the power reception loop coil) shifts to the outer peripheral side or the inner peripheral side by one pitch in the winding (that is, the winding transitions to the outer peripheral side or the inner peripheral side). The copper thin film wires constituting the power transmission loop coil (and the power reception loop coil) are wound. In addition, in the power transmission coil (and power reception coil) of the fifth embodiment, the copper thin film wires constituting the power transmission loop coil (and the power reception loop coil) are wound so that the position of the one curved portion where the above winding transition occurs is the same when viewed from the center of the power transmission coil (and power reception coil). As a result, in the power transmission coil (and power reception coil) of the fifth embodiment, the positions of each winding of the laminated power transmission loop coils (and power reception loop coils) when viewed from the center of the power transmission coil (reception coil) of the four straight portions and the three curved portions in the one winding are configured to coincide in a plan view.

[0157] Note that the configurations of the power transmission coil of the fifth embodiment and the power reception coil of the fifth embodiment are basically the same, and the configurations of the power reception loop coil in the power reception coil of the fifth embodiment and the power transmission loop coil in the power transmission coil of the fifth embodiment are the same. Therefore, in the following description, only the configuration of the power transmission coil of the fifth embodiment will be described. At this time, for the constituent members identical to those of the power transmission coil TC1 of the first embodiment, the same member numbers are assigned and the detailed description is omitted.

[0158] That is, as shown in its plan view in Fig. 22(a), the power transmission coil TC5 of the fifth embodiment includes a power transmission loop coil TL51 formed of a copper thin film wire TL511 and a power transmission loop coil TL52 shown in its plan view in Fig. 22(b), which are laminated in a direction perpendicular to the paper surface of Fig. 22 via an insulating film BF. Also, the center of winding of the copper thin film wire TL511 constituting the power transmission loop coil TL51 and the center of winding of the copper thin film wire TL521 (see Fig. 22(b)) constituting the power transmission loop coil TL52 are the same or substantially the same as each other.

[0159] As shown in FIG. 22(a), the power transmission loop coil TL51 is composed of a copper thin film wire TL511 wound within one layer of the power transmission coil TC5 (on the surface of the film BF illustrated in FIG. 22(a)). On one side of its outermost periphery, it has an external connection terminal O1 for connecting the copper thin film wire TL511 to a power transmission unit (not shown). The power transmission loop coil TL51 is configured such that the copper thin film wire TL511 is wound five times (5 turns) counterclockwise from its outermost periphery in FIG. 22(a), and the outer peripheral end of the copper thin film wire T511 (the right end of the upper side in the case shown in FIG. 22(a)) is connected to the external connection terminal O1. Also, the inner peripheral end of the copper thin film wire TL511 (the central side end of the power transmission coil TC5 in the case shown in FIG. 22(a)) is connected to the copper thin film wire that forms the power transmission loop coil TL52 formed on the back surface of the film BF through a via V11 that penetrates the film BF. Note that the copper thin film wire TL511 has the same width and the same thickness over the entire circumference of the power transmission loop coil TL51. Further, in the copper thin film wire TL511, straight portions are provided on the upper side, lower side, left side, and right side in FIG. 22(a) respectively, and each straight portion is connected by a substantially concentric arc-shaped curved portion.

[0160] Next, the configuration of the power transmission loop coil TL52 laminated directly below the power transmission loop coil TL51 via the film BF will be described with reference to FIG. 22(b). Note that FIG. 22(b) is a plan view showing only the power transmission loop coil TL52 taken out.

[0161] As shown in its plan view in FIG. 22(b), the power transmission loop coil TL52 laminated on the power transmission loop coil TL51 with the film BF sandwiched therebetween is composed of, for example, a copper thin film wire TL521. At this time, as described above, the center of winding of the copper thin film wire TL521 that forms the power transmission loop coil TL52 and the center of winding of the copper thin film wire TL511 that forms the power transmission loop coil TL51 are the same or substantially the same as each other. Further, the overall shape of the power transmission loop coil TL52 is a substantially square shape that is the same as the overall shape of the power transmission loop coil TL41.

[0162] As shown in FIG. 22(b), the power transmission loop coil TL52 is composed of the copper thin film wire TL521 wound in another layer inside the power transmission coil TC5 (the back surface of the film BF illustrated in FIG. 22(a)). One side of its outermost peripheral part has an external connection terminal O2 for connecting the copper thin film wire TL521 to the power transmission part (not shown in the figure). The power transmission loop coil TL52 is configured such that the copper thin film wire TL521 is wound five times (5 turns) counterclockwise from its innermost peripheral part in FIG. 22(b), and the outer peripheral end part of the copper thin film wire TL521 (the upper right end part in the case shown in FIG. 22(b)) is connected to the external connection terminal O2. On the other hand, the inner peripheral end part of the copper thin film wire TL521 (the central side end part of the power transmission coil TC5 in the case shown in FIG. 22(b)) is connected to the copper thin film wire TL511 of the power transmission loop coil TL51 by the via V11. The copper thin film wire TL521 has the same width and the same thickness over the entire circumference of the power transmission loop coil TL52. Further, in the copper thin film wire TL521, straight parts are provided on the upper side part, lower side part, left side part, and right side part in FIG. 22(b), respectively, and each straight part is connected by a substantially concentric arc-shaped curved part.

[0163] Next, the positional relationship between the power transmission loop coil TL51 composed of the copper thin film wire TL511 and the power transmission loop coil TL52 composed of the copper thin film wire TL521 will be described with reference to FIG. 23. FIG. 23 is a plan view showing the overlapping situation between the power transmission loop coil TL51 and the power transmission loop coil TL52. The power transmission loop coil TL51 (copper thin film wire TL511) is shown by a solid line, and the power transmission loop coil TL52 (copper thin film wire TL521) laminated via the film BF (not shown in FIG. 23) directly below it is shown by a dashed line.

[0164] As shown by the solid line in FIG. 23, the power transmission loop coil TL51 is composed of a copper thin film wire TL511 wound from the outer periphery toward the inner periphery, and at its innermost periphery, it is connected by a via V11 to a copper thin film wire TL521 that forms the power transmission loop coil TL52. In the power transmission loop coil TL51, only at one of the four curved portions included in one winding (for example, the upper right portion in FIG. 23), the position of the straight portion of the copper thin film wire TL511 shifts inward by one pitch PT5 (see FIGS. 22(a) and 23) in the winding of the copper thin film wire TL511 (that is, the winding transitions to the inner periphery side), and the copper thin film wire TL511 is wound counterclockwise. As a result, the straight portion where the winding of the power transmission loop coil TL51 transitions to the inner periphery side within one pitch PT5 is, for example, five curved portions CV51 arranged from the outer periphery side to the inner periphery side at the upper right portion in FIGS. 22(a) and 23.

[0165] On the other hand, in the power transmission loop coil TL52 formed by winding the copper thin film wire TL521, which is connected to the copper thin film wire TL511 forming the power transmission loop coil TL51 by the via V11 at its innermost periphery, from the inner periphery toward the outer periphery, as shown by the dashed line in FIG. 23, only at one of the four curved portions included in one winding (for example, the upper right portion in FIG. 18), the position of the straight portion of the copper thin film wire TL521 shifts outward by one pitch PT5 (see FIGS. 22(b) and 23) in the winding of the copper thin film wire TL521 (that is, the winding transitions to the outer periphery side), and the copper thin film wire TL521 is wound counterclockwise (that is, in the same direction as the power transmission loop coil TL51). As a result, the curved portion where the winding of the power transmission loop coil TL52 transitions to the outer periphery side within one pitch PT5 is, for example, five curved portions CV52 arranged from the inner periphery side to the outer periphery side at the upper right portion in FIGS. 22(b) and 23. And the right end of the upper side of the power transmission loop coil TL51 in FIG. 23 is connected to an external connection terminal O1 having a shape protruding outward, and the upper right end of the power transmission loop coil TL52 in FIG. 23 is connected to an external connection terminal O2 having a shape protruding outward.

[0166] The power transmission loop coil TL51 and the power transmission loop coil TL52 each having the above-described shape are laminated as shown in FIG. 23. Thus, the positions of the copper thin film line TL511 and the copper thin film line TL521 as viewed from the center of the power transmission coil TC5 are the same except for one curved portion where each winding transitions and the connection portions to the external connection terminal O1 and the external connection terminal O2. Therefore, as the power transmission coil TC5, the power transmission loop coil TL51 and the power transmission loop coil TL52 are laminated with the film BF sandwiched therebetween in a state where all the straight portions and the curved portions (excluding the winding transition portions) of the power transmission loop coil TL51 and the straight portions and the curved portions (excluding the winding transition portions) of the power transmission loop coil TL52 overlap. As a result, the power transmission loop coil TL52 is connected at the innermost peripheral portion so as to have the same winding direction as the counterclockwise winding from the outermost peripheral portion (external connection terminal O1) to the innermost peripheral portion of the power transmission loop coil TL51, and the power transmission loop coil TL52 is wound from the innermost peripheral portion to the outermost peripheral portion while maintaining the winding direction. With this structure, as the power transmission coil TC5 of the fifth embodiment, a current flows counterclockwise from the outermost peripheral portion to the innermost peripheral portion in the power transmission loop coil TL51, and the current flows in the same clockwise direction from the innermost peripheral portion to the outermost peripheral portion in the power transmission loop coil TL52.

[0167] Note that the manufacturing method of the power transmission coil TC5 (and the power reception coil) of the fifth embodiment is basically the same as the above-described manufacturing method of the power transmission coil TC1 and the power reception coil RC1 of the first embodiment, and thus detailed description thereof is omitted. Fifth Embodiment

[0168] Next, regarding the results (simulation results) of measuring the inductance, impedance, and Q value of the power transmission coil TC5 (or the power reception coil) of the fifth embodiment having the configuration shown in FIGS. 22 and 23, and changing the frequency of power transmission as a power transmission system using the power transmission coil TC5 (or the power reception coil), in comparison with the power transmission coil (power reception coil) of the fifth comparative example, FIGS. 24 to 26 will be used to explain as the fifth embodiment. Note that FIGS. 24 and 25 are plan views showing the structure of the coil of the fifth comparative example, and FIG. 26 is a diagram showing the effect due to the structure of the power transmission coil TC5 (or the power reception coil) of the fifth embodiment.

[0169] Here, before explaining the above fifth embodiment, the configuration of the power transmission coil or the power reception coil of the fifth comparative example, which is the comparison target, will be briefly explained with reference to FIGS. 24 and 25. Note that the power transmission coil and the power reception coil of the fifth comparative example basically have the same configuration. Therefore, in the following explanation, the structure of the power transmission coil of the fifth comparative example will be described. Also, FIGS. 24 and 25 are plan views showing the structure of the power transmission coil of the fifth comparative example when viewed from the same perspective as the power transmission coil TC5 of the fifth embodiment. At this time, in FIGS. 24 and 25, the same member numbers are assigned to the members identical to the power transmission coil TC5 of the fifth embodiment, and the detailed description thereof is omitted.

[0170] As shown in the plan view of FIG. 24(a), the power transmission coil TC5X of the fifth comparative example includes a power transmission loop coil TL5X formed of a copper thin film wire TL5X1 and a power transmission loop coil TL5Y (not shown in FIG. 24(a)), which are laminated in a direction perpendicular to the paper surface of FIG. 24 via an insulating film BF similar to the power transmission coil TC5 of the fifth embodiment. At this time, the center of the winding of the copper thin film wire TL5X1 constituting the power transmission loop coil TL5X and the center of the winding of the copper thin film wire (described later) constituting the power transmission loop coil TL5Y are the same or substantially the same as each other.

[0171] As shown in FIG. 24(a), the power transmission loop coil TL5X is composed of a copper thin film wire TL5X1 wound within one layer of the power transmission coil TC5X (on the surface of the film BF illustrated in FIG. 24(a)), and has an external connection terminal O1 for connecting the copper thin film wire TL5X1 to a power transmission unit (not shown) at one side of its outermost periphery. The power transmission loop coil TL5X is configured such that the copper thin film wire TL5X1 is wound five times (5 turns) counterclockwise from its outermost periphery in FIG. 24(a), and the outer peripheral end portion of the copper thin film wire TL5X1 (the center of the upper side portion in the case shown in FIG. 24(a)) is connected to the external connection terminal O1. Also, the inner peripheral end portion of the copper thin film wire TL5X1 (the end portion on the center side of the power transmission coil TC5X in the case shown in FIG. 24(a)) is connected to the copper thin film wire that forms the power transmission loop coil TL5Y formed on the back surface of the film BF through a via V11 that penetrates the film BF. Note that the copper thin film wire TL5X1 has the same width and the same thickness over the entire circumference of the power transmission loop coil TL5X. Further, in the copper thin film wire TL5X1, straight portions are provided at the upper side portion, the lower side portion, the left side portion, and the right side portion in FIG. 24(a), respectively, and each straight portion is connected by a substantially concentric arc-shaped curved portion.

[0172] Next, the configuration of the power transmission loop coil TL5Y laminated directly below the power transmission loop coil TL5X via the film BF will be described with reference to FIG. 24(b). Note that FIG. 24(b) is a plan view showing only the power transmission loop coil TL5Y taken out.

[0173] As shown in its plan view in FIG. 24(b), the power transmission loop coil TL5Y laminated on the power transmission loop coil TL5X with the film BF interposed therebetween is composed of a copper thin film wire TL5Y1. At this time, the center of winding of the copper thin film wire TL5Y1 that forms the power transmission loop coil TL5Y and the center of winding of the copper thin film wire TL5X1 that forms the power transmission loop coil TL5X are the same or substantially the same as each other. Further, the overall shape of the power transmission loop coil TL5Y is a substantially square shape that is the same as the overall shape of the power transmission loop coil TL5X.

[0174] As shown in FIG. 24(b), the power transmission loop coil TL5Y is composed of the copper thin film wire TL5Y1 wound in another layer inside the power transmission coil TC5X (the back surface of the film BF illustrated in FIG. 24(a)). On one side of its outermost periphery, it has an external connection terminal O2 for connecting the copper thin film wire TL5Y1 to a power transmission part (not shown). The power transmission loop coil TL5Y is configured such that the copper thin film wire TL5Y1 is wound five times (5 turns) clockwise from its innermost periphery in FIG. 24(b). The outer peripheral end of the copper thin film wire TL5Y1 (the center of the upper side in the case shown in FIG. 24(b)) is connected to the external connection terminal O2. On the other hand, the inner peripheral end of the copper thin film wire TL5Y1 (the center side end of the power transmission coil TC5X in the case shown in FIG. 24(b)) is connected to the copper thin film wire TL5X1 of the power transmission loop coil TL5X by the via V11. The copper thin film wire TL5Y1 has the same width and the same thickness over the entire circumference of the power transmission loop coil TL5Y. Further, in the copper thin film wire TL5Y1, straight portions are provided on the upper side, lower side, left side, and right side in FIG. 24(b), respectively, and each straight portion is connected by a substantially concentric arc-shaped curved portion.

[0175] Next, the positional relationship between the power transmission loop coil TL5X composed of the copper thin film wire TL5X1 and the power transmission loop coil TL5Y composed of the copper thin film wire TL5Y1 will be described with reference to FIG. 25. FIG. 25 is a plan view showing the overlapping situation of the power transmission loop coil TL5X and the power transmission loop coil TL5Y. The power transmission loop coil TL5X is shown by a solid line, and the power transmission loop coil TL5Y laminated via the film BF (not shown in FIG. 25) directly below it is shown by a dashed line.

[0176] As shown by the solid line in Fig. 25, the power transmission loop coil TL5X is composed of a copper thin film wire TL5X1 wound from the outer periphery toward the inner periphery, and at its innermost peripheral part, it is connected to the copper thin film wire TL5Y1 that forms the power transmission loop coil TL5Y by the via V11. In the power transmission loop coil TL5X, only one of the four curved portions included in one winding (for example, the curved portion in the upper right corner in Fig. 25), the position of the straight portion of the copper thin film wire TL5X1 shifts inward by one pitch PT5 in the winding of the copper thin film wire TL5X1 (that is, the winding transitions to the inner peripheral side), and the copper thin film wire TL5X1 is wound counterclockwise. As a result, the curved portion where the winding of the power transmission loop coil TL5X transitions to the inner peripheral side within one pitch PT5 is, for example, the five curved portions CV5X arranged from the outer peripheral side to the inner peripheral side in the upper left corner in Figs. 24(a) and 25.

[0177] On the other hand, in the power transmission loop coil TL5Y formed by winding the copper thin film wire TL5Y1 connected to the copper thin film wire TL5X1 that forms the power transmission loop coil TL5X by the via V11 from the inner periphery toward the outer periphery at its innermost peripheral part, as shown by the dashed line in Fig. 25, only one of the four curved portions included in one winding (for example, the curved portion in the upper left corner in Fig. 25), the position of the straight portion of the copper thin film wire TL5Y1 shifts outward by one pitch PT5 in the winding of the copper thin film wire TL5Y1 (that is, the winding transitions to the outer peripheral side), and the copper thin film wire TL5Y1 is wound clockwise. As a result, the curved portion where the winding of the power transmission loop coil TL5Y transitions to the outer peripheral side within one pitch PT5 is, for example, the five curved portions CV5Y arranged from the inner peripheral side to the outer peripheral side in the upper left corner in Figs. 24(b) and 24. And the outermost peripheral part of the upper side in Fig. 25 of the power transmission loop coil TL5X is connected to the external connection terminal O1 with a shape protruding outward, and the outermost peripheral part of the upper side in Fig. 25 of the power transmission loop coil TL5Y is connected to the external connection terminal O2 with a shape protruding outward.

[0178] The power transmission loop coil TL5X and the power transmission loop coil TL5Y each having the above-described shape are laminated as shown in FIG. 25. Thus, the positions of the copper thin film line TL5X1 and the copper thin film line TL5Y1 as viewed from the center of the power transmission coil TC5X are different at two curved portions and connection portions to the external connection terminal O1 and the external connection terminal O2 as shown in FIG. 25. Therefore, as the power transmission coil TC5X, the power transmission loop coil TL5X and the power transmission loop coil TL5Y are laminated with a film BF sandwiched therebetween in a state where there are more non-overlapping portions than the power transmission coil TC5 of the fifth embodiment. As a result, the power transmission loop coil TL5Y is connected at the innermost peripheral portion so as to have the same winding direction as the clockwise winding from the outermost peripheral portion (external connection terminal O1) to the innermost peripheral portion of the power transmission loop coil TL5X, and the power transmission loop coil TL5Y is wound from the innermost peripheral portion to the outermost peripheral portion while maintaining the winding direction. With this structure, as the power transmission coil TC5X of the fifth comparative example, a current flows in the clockwise direction from the outermost peripheral portion to the innermost peripheral portion in the power transmission loop coil TL5X, and the current flows in the same clockwise direction from the innermost peripheral portion to the outermost peripheral portion in the power transmission loop coil TL5Y.

[0179] And the other specifications of the power transmission coil TC5 of the fifth embodiment and the power transmission coil TC5X of the fifth comparative example used in the experiment of the fifth example are as follows. In the following description, the specifications of the power transmission coil TC5 and the power transmission coil TC5X will be described. However, the specifications of the power receiving coil of the fifth embodiment used in the experiment are the same as those of the power transmission coil TC5, and the specifications of the power receiving coil of the fifth comparative example are the same as those of the power transmission coil TC5X.

[0180] · Size of the power transmission coil TC5 (and the power receiving coil of the fifth embodiment) and the power transmission coil TC5X (and the power receiving coil of the fifth conventional example): 300 millimeters × 300 millimeters · Pitch PT5: 18 millimeters · Thickness of the copper thin film wire in the copper thin film wire TL511, etc.: 0.2 millimeters

[0181] As shown in FIG. 26, in the vicinity of the frequency (85 kHz) used for power transmission by the power transmission system, using the power transmission coil TC5 and the power receiving coil of the fifth embodiment results in a higher inductance and a lower impedance compared to the case of using the power transmission coil TC5X and the power receiving coil of the fifth comparative example. Therefore, good characteristics are obtained for the Q value.

[0182] As described above, according to the power transmission using the power transmission system including the power transmission coil TC5 of the fifth embodiment and the power receiving coil of the fifth embodiment, the overall planar shapes of the power transmission loop coils TL51 and TL52 are substantially the same square as each other, and the positions of each winding of the power transmission coil TC5 of the power transmission loop coil TL51 as viewed from the center of the power transmission coil TC5 and the positions of each winding of the power transmission coil TC5 of the power transmission loop coil TL52 as viewed from the center of the power transmission coil TC5 coincide in plan view (see FIG. 23). Therefore, it is possible to reduce the impedance due to the so-called skin effect or proximity effect caused by configuring the power transmission coil TC5 and the power receiving coil of the fifth embodiment with a copper thin film wire for weight reduction and cost reduction, and it is possible to achieve both weight reduction and cost reduction, and improvement of transmission efficiency and prevention of an increase in the operating temperature. Modification

[0183] Next, a modification of the present invention will be described. Regarding the configuration of the power transmission system of each of the above-described embodiments, the following modifications shown in (A) and (B) may be added. In the present invention, even if each of the modifications is added, an effect equivalent to that of the above power transmission system can be achieved.

[0184] (A) First Modified Form First, as a first modification, in the power transmission system of the second embodiment, the current adjustment coil TL23 may be laminated on the power receiving device R side in the power transmission coil TC2 or on the side opposite to the power receiving device R as long as it is at a position other than between the power transmission loop coils TL21 and TL22.

[0185] (B) Second Modified Form Next, as a second modified form, regarding the positional relationship between the current adjustment coils RL33 and RL34 of the third embodiment and the power reception loop coils RL31 and RL32, it is preferable that the power reception loop coils RL31 and RL32 are stacked on the power transmission device T side (i.e., the opposing side) with respect to the current adjustment coils RL33 and RL34.

[0186] (C) Third Modified Form Next, as a third modified form, the number of turns obtained by connecting the power transmission loop coils TL21 and TL22 of the second embodiment in parallel may be an integer multiple of two or more times the number of turns of the current adjustment coil RL23. Also, the number of turns obtained by connecting the current adjustment coils RL33 and RL34 of the third embodiment in series may be an integer multiple of three or more times the number of turns obtained by connecting the power reception loop coils RL31 and RL32 in parallel. In any case, the copper thin film wires constituting each of them overlap, and the same effects as those of each embodiment can be expected.

Industrial Applicability

[0187] As described above, the present invention can be used in the field of non-contact power transmission, and particularly remarkable effects can be obtained when applied to the field of power transmission for charging a storage battery mounted on an electric vehicle.

Explanation of Reference Numerals

[0188] S Power transmission system T Power transmission device TR Power transmission unit R Power reception device RV Power reception unit BF Film O1, O2 External connection terminals M1, M2, M3 Connection terminals RC1, RC2, RC3 Power reception coils TC1, TCX, TC2, TC4, TC4X, TC5, TC5X Power transmission coils Copper thin film wires of TL111, TL112, TL121, TL122, TLX1, TLX2, TLY1, TLY2, TL211, TL212, TL221, TL222, TL231, TL232, TL411, TL412, TL4X1, TL4Y1, TL511, TL512, TL5X1, TL5Y1, RL311, RL312, RL321, RL322, RL331, RL332, RL341, RL342 Power transmission loop coils of TL11, TL12, TLX, TLY, TL21, TL22, TL41, TL42, TL4X, TL4Y, TL51, TL52, TL5X, TL5Y Power receiving loop coils of RL31, RL32 Vias of V11, V12, VV Curved portions of CV11, CV12, CV51, CV52, CV4X, CV4Y, CV5X, CV5Y Straight portions of LA41, LA42 Current adjustment coils of TL23, RL33, RL34 Capacitor Cp

Claims

[Claim 1] In a coil for contactless power transmission, a first winding circuit formed by winding a thin-film conductor, the first winding circuit including a plurality of first straight line portions each having a straight line shape, and a plurality of first curved lines each having a curved shape and connecting the first straight line portions; a second winding circuit formed by winding a thin-film conductor, the second winding circuit including a plurality of second straight portions each having a straight line shape and a plurality of second curved portions each having a curved line shape connecting the second straight portions, the second winding circuit being laminated on the first winding circuit with an insulating layer sandwiched therebetween; Equipped with The first winding wire and the second winding wire each have an overall shape in a plan view that is the same polygon as each other, A coil characterized in that the position of at least a portion of each of the first straight sections, as viewed from the center of the coil, coincides with the position of at least a portion of each of the second straight sections, which corresponds to at least a portion of each of the first straight sections, as viewed from the center of the coil, in a planar view.

Images