Coil, power transmitting device, 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 fields of coils, power transmitting devices, power receiving devices, and power transfer systems, and more specifically, to the technical fields of coils for contactless power transfer, and contactless power transmitting devices, power receiving devices, and power transfer systems using such coils. [Background technology]

[0002] In recent years, electric vehicles equipped with storage batteries such as lithium-ion batteries are becoming more widespread. In such electric vehicles, the motor is driven by the power stored in the storage battery to move, so efficient charging of the storage battery is required. Therefore, as a method for charging the storage battery mounted on the electric vehicle without physically connecting a charging plug or the like to the electric vehicle, so-called wireless power transmission using a receiving coil and a transmitting coil that are separated and opposed to each other has been studied. Wireless power transmission methods generally include an electric field coupling method, an electromagnetic induction method, and a magnetic field resonance method. When these methods are compared from the viewpoints of, for example, the frequency of the power transmitted and received, the degree of freedom in the horizontal and vertical directions, and the transmission efficiency, the electric field coupling method using a capacitor or the magnetic field resonance method using a coil is considered to be promising as a wireless power transmission method for charging the storage battery mounted on the electric vehicle, and research and development into these methods is also being actively conducted. For example, the following Patent Document 1 can be given as a prior art document disclosing such background technology. This patent document 1 discloses a coil that transmits power by a magnetic field resonance method using a loop coil with one winding (1 turn) and an open coil with five and a half windings (5.5 turns).

[0003] On the other hand, the frequency of the power transmitted and received by the wireless power transmission is predetermined for each device by law, and in the case of the power transmission to the electric vehicle, it is set to a high frequency of 85 kHz. It is generally known that when a high-frequency current flows through a conductor, the current density is high on the surface of the conductor and decreases from the surface toward the center. In addition, the higher the frequency of the current, the more the current is concentrated 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 description, the AC resistance of a conductor when a high-frequency current flows through the conductor is simply called "impedance." [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-200045 A Summary of the Invention [Problem to be solved by the invention]

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

[0006] In addition, as with the skin effect, another electrical phenomenon that reduces the efficiency of wireless power transmission is the so-called "conductor proximity effect," which occurs when conductors are wound in a coil close to each other. Therefore, measures must be taken to prevent the increase in resistance caused by this proximity effect.

[0007] The present invention has been made in consideration of the above problems and demands, and one example of the object of the present invention is to provide a coil that can improve the efficiency of wireless power transmission even when using a high-frequency current such as 85 kHz, and a non-contact power transmitting device, power receiving device, and power transfer system that use such a coil. [Means for solving the problem]

[0008] In order to solve the above problems, the invention described in claim 1 provides a coil for contactless power transmission, comprising: a first winding circuit formed by winding a thin film conductor, the first winding circuit comprising a plurality of first straight sections, each of which has a straight shape, and a plurality of first curved sections, each of which has a curved shape, connecting the first straight sections; and a second winding circuit formed by winding a thin film conductor, the second winding circuit comprising a plurality of second straight sections, each of which has a straight shape, and a plurality of second curved sections, each of which has a curved shape, connecting the second straight sections, the second winding circuit being laminated on the first winding circuit with an insulating layer sandwiched therebetween, wherein the overall shapes of the first winding circuit and the second winding circuit in a plan view are the same polygonal shape, and a position of at least a part of each of the first straight sections, as viewed from the center of the coil, coincides in a plan view with a position of at least a part of each of the second straight sections, as viewed from the center. In the winding of the first winding line, a winding transition for one turn is made only in one of the first curved portions included in one winding, and in the winding of the second winding line, a winding transition for one turn is made only in one of the second curved portions included in one winding, and the position of the first curved portion where the winding transition is made in the first winding line and the position of the second curved portion where the winding transition is made in the second winding line are configured to be within the same region of the coil when viewed from the center. .

[0009] According to the invention of claim 1, a coil includes a first winding circuit having a plurality of first straight portions and a plurality of first curved portions, the first winding circuit being made of a thin film conductor, and a second winding circuit having a plurality of second straight portions and a plurality of second curved portions, the second winding circuit being made of a thin film conductor, and laminated on the first winding circuit with an insulating layer sandwiched therebetween. The first winding circuit and the second winding circuit have the same overall shape in a plan view, and the position of at least a part of each first straight portion as viewed from the coil center coincides with the position of at least a part of each second straight portion corresponding to at least a part of each first straight portion as viewed from the coil center in a plan view. This makes it possible to reduce the AC resistance of the coil due to the so-called skin effect or proximity effect caused by forming the winding circuit from a thin film conductor for weight and cost reduction, and to simultaneously achieve weight and cost reduction, improved transmission efficiency, and prevention of an increase in operating temperature. In addition, in the winding of the first winding line, a winding transition for one turn is made only in one first curved portion included in one winding, and in the winding of the second winding line, a winding transition for one turn is made only in one second curved portion included in one winding. This makes it possible to reliably match the positions of the corresponding first straight portion and second straight portion as viewed from the coil center in a plan view. Furthermore, since the position of the first curved portion where the winding transition occurs in the first winding line and the position of the second curved portion where the winding transition occurs in the second winding line are within the same region when viewed from the center of the coil, it is possible to make the positions of more first straight portions and second straight portions coincide when viewed from the center of the coil in a plan view.

[0010] In order to solve the above problem, the invention described in claim 2 provides the coil described in claim 1, The positions of the curved portions other than the first curved portion or the second curved portion at which the winding transition occurs are aligned when viewed from the center of the coil in a plan view. .

[0011] According to the invention described in claim 2, in addition to the effects of the invention described in claim 1, Since the positions of the curved sections other than the first curved section or the second curved section where the winding transition occurs coincide when viewed from the center of the coil in a plan view, it is possible to achieve both weight reduction and cost reduction, improved transmission efficiency, and prevention of an increase in operating temperature. It can be done.

[0012] In order to solve the above problem, the invention described in claim 3 comprises: A coil for contactless power transmission comprises: a first winding circuit formed by winding a thin film conductor, the first winding circuit being composed of a plurality of first straight sections, each of which has a straight shape, and a plurality of first curved sections, each of which connects the first straight sections and has a curved shape; and a second winding circuit formed by winding a thin film conductor, the second winding circuit being composed of a plurality of second straight sections, each of which has a straight shape, and a plurality of second curved sections, each of which connects the second straight sections and has a curved shape, the second winding circuit being laminated on the first winding circuit with an insulating layer sandwiched therebetween, wherein the overall shapes of the first winding circuit and the second winding circuit in a plan view are mutually identical polygonal, and at least one of the first straight sections is formed in a curved shape. a position of at least a portion of the coil as viewed from the center coincides with a position of at least a portion of each of the second straight portions corresponding to at least a portion of each of the first straight portions as viewed from the center in a plan view; in the winding of the first winding wire, a winding transition for one turn is made only in one of the first straight portions included in one turn; in the winding of the second winding wire, a winding transition for one turn is made only in one of the second straight portions included in one turn; and a position of each of the first curved portions as viewed from the center of the coil coincides with a position of each of the second curved portions corresponding to each of the first curved portions as viewed from the center in a plan view. It is configured as follows.

[0013] According to the invention described in claim 3, The coil comprises a first winding circuit having a plurality of first straight portions and a plurality of first curved portions and made of a thin film conductor, and a second winding circuit having a plurality of second straight portions and a plurality of second curved portions and made of a thin film conductor and laminated on the first winding circuit with an insulating layer sandwiched therebetween. The first winding circuit and the second winding circuit have the same overall shape in a plan view, and the positions of at least a portion of each of the first straight portions as viewed from the coil center coincide with the positions of at least a portion of each of the second straight portions corresponding to at least a portion of each of the first straight portions as viewed from the coil center in a plan view. This makes it possible to reduce the AC resistance of the coil due to the so-called skin effect or proximity effect caused by forming the winding circuit from a thin film conductor for weight and cost reduction, and to simultaneously achieve weight reduction and cost reduction, improved transmission efficiency, and prevention of an increase in operating temperature. In addition, in the winding of the first winding line, a winding transition for one turn is made only in one first straight portion included in one winding, and in the winding of the second winding line, a winding transition for one turn is made only in one second straight portion included in one winding. This makes it possible to reliably match the positions of the corresponding first winding line and second winding line as viewed from the coil center in a plan view. Furthermore, the position of each first curved portion as viewed from the center of the coil and the position of each second curved portion corresponding to each first curved portion as viewed from the center of the coil coincide in a plan view. This increases the number of portions of the first winding wire and the second winding wire whose positions coincide in a plan view, thereby more effectively achieving weight reduction and cost reduction, improved transmission efficiency, and prevention of increases in operating temperature. It can be done.

[0014] In order to solve the above problem, the invention described in claim 4 comprises: a first winding circuit formed by winding a thin-film conductor and including a plurality of first straight sections, each of which has a straight shape, and a plurality of first curved sections, each of which has a curved shape, connecting the first straight sections; and a second winding circuit formed by winding a thin-film conductor and including a plurality of second straight sections, each of which has a straight shape, and a plurality of second curved sections, each of which has a curved shape, connecting the second straight sections, the second winding circuit being stacked on the first winding circuit with an insulating layer sandwiched therebetween, wherein the first winding circuit and the second winding circuit have overall shapes that are the same polygonal shape as seen in a plan view, a position of at least a portion of each of the first straight sections, as viewed from the center of the coil, coincides with a position of at least a portion of each of the second straight sections, as viewed from the center, corresponding to at least a portion of each of the first straight sections, in a plan view, and an innermost portion of the first winding circuit and an innermost portion of the second winding circuit are connected; When transmitting power, the power to be transmitted is supplied to the outermost end of each of the first winding circuit and the second winding circuit, and when receiving power, the received power is output from each of the outermost end portions. The coil further includes an adjustment winding circuit for adjusting a current flowing through the first winding circuit and the second winding circuit, the adjustment winding circuit being laminated at the same position as the first winding circuit and the second winding circuit, the adjustment winding circuit being composed of a plurality of adjustment straight sections, each of which is linear, and a plurality of adjustment curved sections, each of which is curved, connecting the adjustment straight sections, the adjustment winding circuit having an overall shape in a plan view that is the same polygonal shape as the overall shape in a plan view of the first winding circuit or the second winding circuit, and the position of each of the first straight sections as viewed from the center of the coil and the position of each of the adjustment straight sections corresponding to each of the first straight sections as viewed from the center coincide in a plan view. .

[0015] According to the invention described in claim 4, The coil comprises a first winding circuit having a plurality of first straight portions and a plurality of first curved portions and made of a thin film conductor, and a second winding circuit having a plurality of second straight portions and a plurality of second curved portions and made of a thin film conductor and laminated on the first winding circuit with an insulating layer sandwiched therebetween. The first winding circuit and the second winding circuit have the same overall shape in a plan view, and the positions of at least a portion of each of the first straight portions as viewed from the coil center coincide with the positions of at least a portion of each of the second straight portions corresponding to at least a portion of each of the first straight portions as viewed from the coil center in a plan view. This makes it possible to reduce the AC resistance of the coil due to the so-called skin effect or proximity effect caused by forming the winding circuit from a thin film conductor for weight and cost reduction, and to simultaneously achieve weight reduction and cost reduction, improved transmission efficiency, and prevention of an increase in operating temperature. The coil further includes an adjustment winding consisting of a plurality of adjustment straight sections and a plurality of adjustment curved sections, the adjustment winding having an overall shape in a plan view that is the same polygon as the overall shape in a plan view of the first winding or the second winding, and the position of each first straight section as viewed from the center of the coil coincides with the position of each adjustment straight section corresponding to each first straight section as viewed from the center in a plan view. Thus, even when an adjustment winding is included, the AC resistance of the coil can be reduced, and it is possible to simultaneously achieve weight reduction and cost reduction, improved transmission efficiency, and prevention of an increase in operating temperature. It can be done.

[0016] In order to solve the above problem, the invention described in claim 5 provides the coil described in claim 4, A plurality of the adjustment windings are stacked at the same positions as the first winding and the second winding. It has been done.

[0017] According to the invention described in claim 5, in addition to the effects of the invention described in claim 4, Since the plurality of adjustment windings are laminated at the same position as the first winding and the second winding, the current flowing through the first winding and the second winding can be effectively adjusted while Weight reduction and cost reduction, improvement of transmission efficiency and prevention of increase in operating temperature, Both It can be made to stand.

[0018] In order to solve the above problem, the invention described in claim 6 is In item 5 In the coil described, The outermost ends of the plurality of adjustment windings are connected to each other, and a capacitance means for adjusting the current is connected to the innermost periphery of the plurality of adjustment windings, and the capacitance of the capacitance means is at least equal to or less than a threshold capacitance corresponding to a frequency of power transmission by the coil. It is composed.

[0019] According to the invention described in claim 6, In item 5 In addition to the effects of the invention described above, The outermost ends of the plurality of adjustment windings are connected to each other, and a capacitance means for adjusting the current is connected to the innermost periphery thereof. The capacitance of the capacitance means is equal to or less than the threshold capacitance. Therefore, even when the capacitance means for adjusting the current is provided, Weight reduction and cost reduction, improvement of transmission efficiency and prevention of increase in operating temperature, Both It can be made to stand.

[0020] In order to solve the above problem, the invention described in claim 7 includes the following: 1 to Claims 6 Any one of the following In the coil described in The first winding is made up of two parallel first windings, and the second winding is made up of two parallel second windings. It is composed.

[0021] According to the invention described in claim 7, 1 to Claims 6 Any one of the following In addition to the effects of the invention described above, Since the first winding circuit is composed of two first parallel winding circuits, and the second winding circuit is composed of two second parallel winding circuits, By further reducing the AC resistance of the coil, it is possible to achieve a better balance between weight reduction and cost reduction, improved transmission efficiency, and prevention of an increase in operating temperature.

[0022] In order to solve the above problem, the invention described in claim 8 is In item 7 In the coil described, In one turn of the first winding, the width of the first parallel winding on the inner circumference side is wider than the width of the first parallel winding on the outer circumference side, and in one turn of the second winding, the width of the second parallel winding on the inner circumference side is wider than the width of the second parallel winding on the outer circumference side. It is designed to be spacious.

[0023] According to the invention described in claim 8, In item 7 In addition to the effects of the invention described above, The width of the first parallel winding circuit on the inner circumference side is wider than the width of the first parallel winding circuit on the outer circumference side, and the width of the second parallel winding circuit on the inner circumference side is wider than the width of the second parallel winding circuit on the outer circumference side. This makes it possible to further reduce the AC resistance of the coil, thereby achieving both weight reduction and cost reduction, improved transmission efficiency, and prevention of increases in operating temperature. It is possible.

[0024] In order to solve the above problem, the invention described in claim 9 comprises the following: 6 In the coil according to any one of the preceding claims, The width of each of the first winding wire and the second winding wire is wider in the windings closer to the center. It is structured as follows.

[0025] According to the invention described in claim 9, claims 1 to 9 6 In addition to the effects of the invention described in any one of the above, The width of each of the first and second windings is wider the closer to the center of the coil. Therefore, by making the width of the winding wider toward the center of the coil where the current is concentrated, the AC resistance of the coil is further reduced. It is possible.

[0030] In order to solve the above problem, the following claims are provided: 10 The present invention relates to a power transmission system including a power transmission device and a power receiving device separated from the power transmission device, the power transmission device transmitting power from the power transmission device to the power receiving device in a non-contact manner, the power transmission device comprising: 9 The power transmitting coil according to any one of claims 1 to 5, further comprising: a power transmitting coil disposed opposite the power receiving device; and an output unit configured to output power to be transmitted to the power transmitting coil.

[0031] In order to solve the above problem, the following claims are provided: 11 The present invention relates to a power receiving device included in a power transmission system that includes a power transmitting device and a power receiving device that is separated from the power transmitting device, and transmits power from the power transmitting device to the power receiving device in a non-contact manner. 9 The power receiving coil is the coil according to any one of claims 1 to 4, and includes a power receiving coil arranged to face the power transmitting device, and an input means connected to the power receiving coil.

[0032] In order to solve the above problem, the following claims are provided: 12 The invention described in claim 10and a power receiving device disposed away from the power transmitting device and facing the power transmitting coil, the power receiving device receiving the power transmitted from the power transmitting device.

[0033] In order to solve the above problem, the following claims are provided: 13 The invention described in claim 1 is a power transmission device. 11 the power receiving device being disposed away from the power transmitting device with the power receiving coil facing the power transmitting device, and receiving power transmitted from the power transmitting device.

[0034] Claim 10 From claims 13 According to the invention described in any one of the following: , this When the power transmitting coil and the power receiving coil are placed opposite each other to perform non-contact power transmission, the impedance of the coil due to the skin effect or proximity effect can be reduced, achieving both weight reduction and cost reduction, improved transmission efficiency, and prevention of an increase in operating temperature. Etc. do. Effect of the Invention

[0035] The present invention One aspect of According to the document, the coil comprises a first winding circuit having a plurality of first straight portions and a plurality of first curved portions and made of a thin film conductor, and a second winding circuit having a plurality of second straight portions and a plurality of second curved portions and made of a thin film conductor and laminated on the first winding circuit with an insulating layer sandwiched therebetween. The first winding circuit and the second winding circuit have the same overall polygonal shape in a plan view, and the position of at least a part of each of the first straight portions as viewed from the coil center coincides with the position of at least a part of each of the second straight portions corresponding to at least a part of each of the first straight portions as viewed from the coil center in a plan view.

[0036] Therefore, it is possible to reduce the impedance of the coil due to the so-called skin effect or proximity effect that results from constructing the winding circuit using a thin film conductor to reduce weight and cost, and it is possible to achieve both weight and cost reduction, improved transmission efficiency, and prevention of an increase in operating temperature. In addition, in the winding of the first winding line, a winding transition for one turn is made only in one first curved portion included in one winding, and in the winding of the second winding line, a winding transition for one turn is made only in one second curved portion included in one winding. Therefore, the positions of the corresponding first straight portion and second straight portion as viewed from the coil center can be reliably matched in a plan view. Furthermore, since the position of the first curved portion where the winding transition is made in the first winding line and the position of the second curved portion where the winding transition is made in the second winding line are in the same region as viewed from the coil center, it is possible to match the positions of more first straight portions and second straight portions as viewed from the coil center in a plan view. According to another aspect of the present invention, a coil includes a first winding having a plurality of first straight portions and a plurality of first curved portions and made of a thin film conductor, and a second winding having a plurality of second straight portions and a plurality of second curved portions and made of a thin film conductor and laminated on the first winding with an insulating layer sandwiched therebetween. The first winding and the second winding have the same overall shape in a plan view, and the positions of at least a portion of each of the first straight portions as viewed from the coil center coincide with the positions of at least a portion of each of the second straight portions corresponding to at least a portion of each of the first straight portions as viewed from the coil center in a plan view. This makes it possible to reduce the AC resistance of the coil due to the so-called skin effect or proximity effect caused by forming the winding from a thin film conductor for weight and cost reduction, and to simultaneously achieve weight and cost reduction, improved transmission efficiency, and prevention of an increase in operating temperature. In addition, in the winding of the first winding, a winding transition for one turn is made only in one first straight portion included in one winding, and in the winding of the second winding, a winding transition for one turn is made only in one second straight portion included in one winding. Therefore, the positions of the corresponding first winding and second winding as viewed from the coil center can be reliably matched in a plan view. Furthermore, the positions of each first curved portion as viewed from the coil center and the positions of each second curved portion corresponding to each first curved portion as viewed from the coil center match in a plan view, so that the portions of the first winding and second winding that match in position in a plan view increase, making it possible to more easily achieve weight reduction and cost reduction, improved transmission efficiency, and prevention of an increase in operating temperature. According to yet another aspect of the present invention, a coil includes a first winding having a plurality of first straight portions and a plurality of first curved portions and made of a thin film conductor, and a second winding having a plurality of second straight portions and a plurality of second curved portions and made of a thin film conductor and laminated on the first winding with an insulating layer sandwiched therebetween. The first winding and the second winding have the same overall shape in a plan view, and the positions of at least a portion of each of the first straight portions as viewed from the coil center coincide with the positions of at least a portion of each of the second straight portions corresponding to at least a portion of each of the first straight portions as viewed from the coil center in a plan view. This makes it possible to reduce the AC resistance of the coil due to the so-called skin effect or proximity effect caused by forming the winding from a thin film conductor for weight and cost reduction, and to simultaneously achieve weight and cost reduction, improved transmission efficiency, and prevention of an increase in operating temperature. The coil further includes an adjustment winding consisting of a plurality of adjustment straight portions and a plurality of adjustment curved portions, the adjustment winding having an overall shape in a plan view that is the same polygon as the overall shape in a plan view of the first winding or the second winding, and the positions of each first straight portion as viewed from the center of the coil coincide with the positions of each adjustment straight portion corresponding to each first straight portion as viewed from the center in a plan view. Thus, even when an adjustment winding is included, the AC resistance of the coil can be reduced, and it is possible to achieve both weight reduction and cost reduction, improved transmission efficiency, and prevention of an increase in operating temperature. [Brief description of the drawings]

[0037] [Figure 1] 1 is a block diagram showing a schematic configuration of a power transfer system according to a first embodiment. [Diagram 2] FIG. 2 is a plan view (i) showing the structure of the coil according to the first embodiment. [Diagram 3] FIG. 2B is a plan view (ii) showing the structure of the coil according to the first embodiment. [Figure 4] FIG. 3(iii) is a plan view showing the structure of the coil according to the first embodiment. [Diagram 5] FIG. 11 is a plan view (i) showing the structure of the coil of the first conventional example. [Figure 6] FIG. 2B is a plan view (ii) showing the structure of the coil of the first conventional example. [Figure 7] FIG. 11 is a plan view (iii) showing the structure of the coil of the first conventional example. [Figure 8] FIG. 4 is a diagram showing the relationship between frequency and impedance as an effect of the coil structure of the first embodiment. [Figure 9] 11A and 11B are plan views (I) showing the structure of a coil according to a second embodiment, where (a) is the plan view (i) and (b) is the plan view (ii). [Figure 10] 13A and 13B are plan views (II) showing the structure of a coil according to a second embodiment, where (a) is the plan view (iii) and (b) is the plan view (iv). [Figure 11] FIG. 11 is a circuit diagram showing a schematic configuration of a power receiving coil included in a power transfer system according to a third embodiment. [Figure 12] 11A and 11B are plan views (I) showing the structure of a coil according to a third embodiment, where (a) is the plan view (i) and (b) is the plan view (ii). [Figure 13] 13A and 13B are plan views (II) showing the structure of a coil according to a third embodiment, where (a) is the plan view (iii) and (b) is the plan view (iv). [Figure 14]FIG. 11 is a plan view (v) showing the structure of the coil according to the third embodiment. [Figure 15] FIG. 11 is a diagram showing the relationship between capacitance and transmission efficiency as an effect of the configuration of the power receiving coil according to the third embodiment. [Figure 16] FIG. 11 is a diagram showing the relationship between capacitance and loss (copper loss) as an effect of the receiver coil structure of the third embodiment. [Figure 17] 13A and 13B are plan views showing the structure of a coil according to a fourth embodiment, where (a) is the plan view (i) and (b) is the plan view (ii). [Figure 18] FIG. 11 is a plan view (iii) showing the structure of the coil according to the fourth embodiment. [Figure 19] 13A and 13B are plan views showing the structure of a coil in a fourth conventional example, where (a) is the plan view (i) and (b) is the plan view (ii). [Figure 20] FIG. 11 is a plan view (iii) showing the structure of the coil of the fourth conventional example. [Figure 21] 13A and 13B are diagrams showing the effect of the coil structure of the fourth embodiment, where FIG. 13A is a diagram showing the relationship between frequency and Q value as the effect, and FIG. 13B is a diagram showing the relationship between frequency and inductance as the effect. [Figure 22] 13A and 13B are plan views showing the structure of a coil according to a fifth embodiment, where (a) is the plan view (i) and (b) is the plan view (ii). [Figure 23] FIG. 11 is a plan view (iii) showing the structure of the coil according to the fifth embodiment. [Figure 24] 13A and 13B are plan views showing the structure of a coil of a fifth conventional example, where (a) is the plan view (i) and (b) is the plan view (ii). [Diagram 25] FIG. 11 is a plan view (iii) showing the structure of the coil of the fifth conventional example. [Figure 26] 13A and 13B are diagrams showing the effect of the coil structure of the fifth embodiment, where (a) is a diagram showing the relationship between frequency and inductance as the effect, (b) is a diagram showing the relationship between frequency and impedance as the effect, and (c) is a diagram showing the relationship between frequency and Q value as the effect. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Next, embodiments of the present invention will be described with reference to the drawings. Each embodiment described below is an embodiment in which the present invention is applied to a power transmission system that transmits power for charging a storage battery mounted on an electric vehicle to the electric vehicle equipped with the storage battery in a non-contact manner using a magnetic resonance method.

[0039] Here, the power transmission system using the magnetic field resonance method of each embodiment includes a power transmission coil (described below) that transmits power, and a power receiving coil (described below) that is arranged facing (i.e., opposite) the power transmission coil at a distance from the power transmission coil and receives the power transmitted from the power transmission coil.

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

[0041] (I) 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. 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 configured with a power receiving device R including a power receiving unit RV and the power receiving coil RC1, and a power transmitting device T including a power transmitting unit TR and the power transmitting coil TC1. At this time, the power receiving 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 transmitting device T is installed on the ground at a position where the electric vehicle moves or stops. When charging the storage battery, the electric vehicle is driven or stopped so that the power receiving coil RC1 of the power receiving device R and the power transmitting coil TC1 of the power transmitting device T face each other. Note that, when charging the storage battery by the power transmission system S of the first embodiment, it can be configured to transmit power from the power transmitting device T to the power receiving device R mounted on the stopped electric vehicle via the power transmitting coil TC1 of the power transmitting device T installed on the ground below the stopping position. Alternatively, power may be continuously transmitted from a power transmitting device T to a power receiving device R mounted on a moving electric vehicle via the power transmitting coils TC1 of a plurality of power transmitting devices T installed in a section of a certain distance on the road on which the electric vehicle is moving. In this case, the power transmitting unit TR corresponds to an example of the "output means" of the present invention, and the power receiving unit RV corresponds to an example of the "input means" of the present invention.

[0043] The power to be transmitted is input to the power transmitting coil TC1 from the power transmitting unit TR. The power receiving coil RC1 outputs the power received from the power transmitting coil TC1 to the power receiving unit RV by the magnetic resonance method. In this case, the power transmitting coil TC1 and the power receiving coil RC1 each correspond to an example of the "coil" of the present invention.

[0044] In the above configuration, the power transmitting section TR of the power transmitting device T outputs power to be transmitted to the power receiving device R to the power transmitting coil TC1 while complying with laws and regulations such as the Radio Act in the country in which the power transmission system S is used. At this time, the laws and regulations regulate the leakage magnetic field to be below a predetermined level, for example, taking into account the effect on the human body. In addition, in order to enable interconnection between all the power transmitting devices T and the power receiving devices R, it is necessary for both of them to use a predetermined range of frequencies, and therefore the predetermined range of frequencies or frequency bands must follow the recommendations of international organizations such as ISO (International Organization for Standardization) or IEC (International Electrotechnical Commission) as the laws and regulations. In addition, the lower limit of the transmission efficiency taking into account a predetermined positional deviation between the power transmitting coil TC1 and the power receiving coil RC1 is also specified by the international organization, so that the power transmission system S is also required to have high power transmission efficiency.

[0045] Meanwhile, the power receiving coil RC1 of the power receiving device R that receives power from the power transmitting coil TC1 by the magnetic field resonance method outputs the received power to the power receiving unit RV. As a result, the power receiving unit RV converts the output corresponding to the power (for example, the 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 storage battery of the electric vehicle. As a result, the storage battery is charged with the required amount of power.

[0046] (II) Configuration of the transmitting coil TC1 (receiving coil RC1) Next, the configuration of the power transmitting coil TC1 and the power receiving coil RC1 of the first embodiment used in the power transfer system S of the first embodiment described above will be described with reference to Figs. 2 to 4. The power transmitting coil TC1 and the power receiving coil RC1 of the first embodiment basically have the same configuration. Therefore, in the following description, the structure of the power transmitting coil TC1 will be described. Figs. 2 to 4 are plan views showing the structure of the power transmitting coil TC1 of the first embodiment, and are plan views of the power transmitting coil TC as viewed from the power transmitting unit TR side in the power transmitting device T (see Fig. 1).

[0047] As shown in a plan view in FIG. 2, the power transmission coil TC1 of the first embodiment is configured by stacking a power transmission loop coil TL11, which is configured of two parallel copper thin film wires, for example, TL111 and TL112, and a power transmission loop coil TL12, which is not shown in FIG. 2, in a direction perpendicular to the paper surface of FIG. 2, via an insulating film BF (described in detail 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. The copper thin film wire TL111 and the copper thin film wire 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 other insulating materials such as glass epoxy materials can also be used. In addition, in order to efficiently dissipate heat generated by the power transmission coil TC1, a thin film material in which ceramic particles are dispersed, for example, can also be used. Furthermore, the wires may be laminated with the necessary gaps by using an appropriate gap retaining material. Furthermore, the center of winding of the copper thin-film wire TL111 and the copper thin-film wire TL112 constituting the power transmitting loop coil TL11 and the center of winding of the copper thin-film wire described below constituting the power transmitting loop coil TL12 are set to be the same or approximately the same as each other.

[0048] As shown in Fig. 2, the power transmitting loop coil TL11 is composed of a copper thin film wire TL111 and a copper thin film wire TL112 wound in parallel to each other in the same layer of the power transmitting coil TC1 (the surface of the film BF illustrated in Fig. 2), and has an external connection terminal O1 on one side of its outermost circumference to which the copper thin film wire TL111 and the copper thin film wire TL112 are connected and which is connected to the power transmitting unit TR. The power transmitting loop coil TL11 is composed of the copper thin film wire TL111 and the copper thin film wire TL112 wound in parallel in the counterclockwise direction six times (6 turns) from their outermost circumferences in Fig. 2, and the outer peripheral ends of the copper thin film wire TL111 and the copper thin film wire TL112 (the center of the right side in Fig. 2) are connected to the external connection terminal O1. Also, the inner peripheral end portions (the central end portions of the power transmitting coil TC1 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 copper thin film wires constituting the power transmitting loop coil TL12 formed on the back surface of the film BF by vias V11 and V12 that penetrate the film BF, respectively. The copper thin film wire TL111 has the same width w11 (see FIG. 2) and thickness over the entire circumference of the power transmitting loop coil TL11. The copper thin film wire TL112 also has the same width w12 (see FIG. 2) and thickness over the entire circumference of the power transmitting loop coil TL11. Therefore, the width w10 (see FIG. 2) of each turn of the power transmitting loop coil TL11 is also the same over the entire circumference of the power transmitting loop coil TL11. In the power transmission loop coil TL11, the width w12 of the copper thin-film wire TL112 on the inner side in one turn is wider than the width w11 of the copper thin-film wire TL111 on the outer side in one turn over the entire circumference. Furthermore, each of the copper thin-film wires TL111 and TL112 has straight line portions on the upper, lower, left and right sides in FIG. 2, and the straight line portions are connected by curved portions having a substantially concentric arc shape.

[0049] Next, the configuration of the power transmitting loop coil TL12 layered directly below the power transmitting loop coil TL11 with the film BF interposed therebetween will be described with reference to Fig. 3. Fig. 3 is a plan view showing only the power transmitting loop coil TL12.

[0050] As shown in a plan view in Fig. 3, the power transmitting loop coil TL12 laminated on the power transmitting loop coil TL11 with the film BF sandwiched therebetween is composed of two parallel copper thin film wires, for example, copper thin film wire TL121 and copper thin film wire TL122. In this configuration, the copper thin film wire TL121 and the copper thin film wire TL122 correspond to an example of a "second parallel winding circuit" of the present invention. As described above, the winding center of the copper thin film wire TL121 and the copper thin film wire TL122 constituting the power transmitting loop coil TL12 and the winding center of the copper thin film wire TL111 and the copper thin film wire TL112 constituting the power transmitting loop coil TL11 are the same or approximately the same as each other. Furthermore, the overall shape of the power transmitting loop coil TL12 is approximately square, the same as the overall shape of the power transmitting loop coil TL11.

[0051] As shown in Fig. 3, the power transmitting loop coil TL12 is composed of the copper thin film wire TL121 and the copper thin film wire TL122 wound in parallel to each other in the same layer of the power transmitting coil TC1 (the back side of the film BF illustrated in Fig. 2), and has an external connection terminal O2 on one side of its outermost circumference to which the copper thin film wire TL121 and the copper thin film wire TL122 are connected and which is connected to the power transmitting unit TR. The power transmitting loop coil TL12 is composed of the copper thin film wire TL121 and the copper thin film wire TL122 wound in parallel in the counterclockwise direction six times (6 turns) from their innermost circumferences in Fig. 3, and the outer peripheral ends of the copper thin film wire TL121 and the copper thin film wire TL122 (the center of the right side in Fig. 3) are connected to the external connection terminal O2. On the other hand, the inner peripheral end of the copper thin-film wire TL121 (the end on the center side of the power transmitting coil TC1 in the case shown in FIG. 3) is connected to the copper thin-film wire TL111 of the power transmitting loop coil TL11 by the via V12, and the inner peripheral end of the copper thin-film wire TL122 is connected to the copper thin-film wire TL112 of the power transmitting loop coil TL11 by the via V11. The copper thin-film wire TL121 has the same width w11 and thickness over the entire circumference of the power transmitting loop coil TL12. The copper thin-film wire TL122 also has the same width w12 and thickness over the entire circumference of the power transmitting loop coil TL12. For this reason, the width w10 (see FIG. 3) of each turn of the power transmitting loop coil TL12 is also the same over the entire circumference of the power transmitting loop coil TL12. In the power transmission loop coil TL12, the width w12 of the copper thin-film wire TL122 on the inner side in one turn is wider than the width w11 of the copper thin-film wire TL121 on the outer side in one turn over the entire circumference. Furthermore, each of the copper thin-film wires TL121 and TL122 has straight line portions on the upper, lower, left and right sides in FIG. 3, and the straight line portions are connected by curved portions having a substantially concentric arc shape.

[0052] Next, the positional relationship between the power transmitting loop coil TL11 consisting of the copper thin film wire TL111 and the copper thin film wire TL112, and the power transmitting loop coil TL12 consisting of the copper thin film wire TL121 and the copper thin film wire TL122 will be described with reference to Fig. 4. Fig. 4 is a plan view showing the overlapping state of the power transmitting loop coil TL11 and the power transmitting loop coil TL12, in which the power transmitting loop coil TL11 is indicated by a solid line, and the power transmitting loop coil TL12 laminated directly below it with a film BF (not shown in Fig. 4) interposed therebetween is indicated by a dashed line.

[0053] As shown by solid lines in FIG. 4, the power transmission loop coil TL11 is made up of copper thin film wires TL111 and TL112 wound in parallel from the outer periphery to the inner periphery, and is connected at its innermost periphery to the copper thin film wires TL121 and TL122 that constitute the power transmission loop coil TL12 by vias V11 and V12. One of the four curved portions included in one turn of the power transmission loop coil TL11 (for example, the curved portion CV11 at the lower right corner in FIG. 4) Only in the power transmission loop coil TL111, the copper thin-film wire TL112 is wound counterclockwise so that the position of the straight portion shifts toward the inner circumference (i.e., the winding transitions toward the inner circumference) by one pitch PT1 in the winding of each of the copper thin-film wires TL111 and TL112 (i.e., the radial distance of the copper thin-film wires TL111 and TL112 adjacent to each other on each side in each winding; the same applies below (see FIG. 4)).As a result, the curved portion in the power transmission loop coil TL11 where the winding transitions toward the inner circumference by one pitch PT1 is, for example, six curved portions CV11 lined up from the outer circumference to the inner circumference in the lower right corner of FIG. 4.

[0054] In contrast, in the power transmission loop coil TL12, which is formed by winding the copper thin-film wires TL111 and TL112 that constitute the power transmission loop coil TL11 and the copper thin-film wires TL121 and TL122 that are connected at their innermost portions by vias V11 and V12, respectively, in parallel from the inner circumference to the outer circumference, as shown by the dashed line in Figure 4, in only one curved portion (for example, the curved portion CV12 in the lower right corner of Figure 4) among the four curved portions included in one turn, the copper thin-film wires TL121 and TL122 are wound counterclockwise (i.e., in the same direction as the power transmission loop coil TL11) so that the position of the straight portion in each winding of the copper thin-film wire TL121 and the copper thin-film wire TL122 is shifted toward the outer circumference by one pitch PT1 (i.e., so that the winding transitions toward the outer circumference). As a result, the curved portion where the winding of the power transmitting loop coil TL12 transitions to the outer periphery by one pitch PT1 is, for example, six curved portions CV12 lined up from the inner periphery to the outer periphery in the lower right corner in Fig. 4. The outermost portion of the power transmitting loop coil TL11 on the right side in Fig. 4 is connected to the external connection terminal O1 which protrudes outward, and the outermost portion of the power transmitting loop coil TL12 on the right side in Fig. 4 is connected to the external connection terminal O2 which protrudes outward.

[0055] 4, the positions of the copper thin-film wire TL111 and the copper thin-film wire TL121 as viewed from the center of the power transmitting coil TC1 are the same except for the curved portions where the windings transition and the connection portions to the external connection terminals O1 and 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 transmitting coil TC1 are the same except for the curved portions where the windings transition and the connection portions to the external connection terminals O1 and O2. Thus, in the power transmitting coil TC1, the power transmitting loop coil TL11 and the power transmitting loop coil TL12 are stacked with the film BF sandwiched between them, with at least the straight portions of the power transmitting loop coil TL11 and at least the straight portions of the power transmitting loop coil TL12 overlapping each other. As a result, the power transmitting loop coil TL12 is connected to the innermost portion so as to have the same winding direction as the counterclockwise winding from the outermost portion (external connection terminal O1) to the innermost portion of the power transmitting loop coil TL11, and the power transmitting loop coil TL12 is wound from the innermost portion to the outermost portion while maintaining the winding direction. With this structure, in the power transmitting coil TC1 of the first embodiment, a current flows in the counterclockwise direction from the outermost portion to the innermost portion in the power transmitting loop coil TL11, and this current flows in the same counterclockwise direction from the innermost portion to the outermost portion in the power transmitting loop coil TL12.

[0056] (III) Manufacturing method of the transmitting coil TC1 and the receiving coil RC1 Next, a method for manufacturing the power transmitting coil TC1 and the power receiving coil RC1 of the first embodiment will be outlined.

[0057] The manufacturing method can be, for example, a first manufacturing method including the following steps (a)-1 to (a)-6, or a second manufacturing method including the following steps (b)-1 to (b)-12, which are basically the same as conventional methods. (a) 1st manufacturing method (a)-1: A thin copper film is formed on both sides of film BF. (a)-2: A resist is applied onto each of the copper thin films (both sides) formed in (a)-1 above. (a)-3: The resist applied in (a)-2 above is patterned onto the copper thin film wire TL111 and the copper thin film wire TL112 (the copper thin film wire TL121 and the copper thin film wire TL122) constituting the power transmitting loop coil TL11 (power transmitting loop coil TL12) on each side (at this time, the patterning is performed so that the width and thickness of each of the copper thin film wires TL111 and TL112 (the copper thin film wires TL121 and TL122) are the same from the outermost end (the connection portion to the external connection terminal O1 (external connection terminal O2)) of the power transmitting loop coil TL11 (power transmitting loop coil TL12) to the portion where the vias V11 and V12 at the innermost end are connected, as described above). (a)-4: After the patterning in (a)-3 above, etching is performed to form the copper thin film line TL111 and the copper thin film line TL112 (the copper thin film line TL121 and the copper thin film line TL122). (a)-5: A via V11 and a via V12 that connect the power transmitting loop coil TL11 and the power transmitting loop coil TL12 are formed, and a power transmitting loop coil TC1 including an external connection terminal O1 and an external connection terminal O2 is formed. (a)-6: 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 receiving unit RV (in the case of the power receiving device R). (b) Second manufacturing method (b)-1: A thin copper film is formed on both sides of film BF. (b)-2: Form through holes at positions corresponding to vias V11 and V12 using a laser or the like. (b)-3: The entire surface including the through hole is subjected to copper plating treatment by electroless copper plating and electrolytic copper plating to form the vias V11 and V12. (b)-4: Apply resist to the copper plating (both sides) formed in (b)-3 above. (b)-5: The resist applied in (b)-4 above is patterned on each side in the same manner as in (a)-3 above into the copper thin film wire TL111 and the copper thin film wire TL112 (the copper thin film wire TL121 and the copper thin film wire TL122) that constitute the power transmission loop coil TL11 (the power transmission loop coil TL12). (b)-6: After the patterning in (b)-5 above, an etching process is performed to form the external connection terminal O1 (external connection terminal O2) and the copper thin film wire TL111 and the copper thin film wire TL112 (the copper thin film wire TL121 and the copper thin film wire TL122). (b)-7: External connection terminal O1 and external connection terminal O2 are connected to power transmission unit TR (in the case of power transmission device T) or power receiving unit RV (in the case of power receiving device R) in the first embodiment

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

[0059] Before describing the first example, the configuration of a power transmitting coil or a power receiving coil of a first conventional example, which is a comparison target, will be outlined with reference to Figs. 5 to 7. The power transmitting coil and the power receiving coil of the first conventional example basically have the same configuration. Therefore, in the following description, the structure of the power transmitting coil of the first conventional example will be described. Also, Figs. 5 to 7 are plan views showing the structure of the power transmitting coil of the first conventional example when viewed from the same viewpoint as the power transmitting coil TC1 of the first embodiment (see Fig. 1). In Figs. 5 to 7, the same members as those of the power transmitting coil TC1 of the first embodiment are denoted by the same member numbers, and detailed descriptions will be omitted.

[0060] As shown in a plan view in Fig. 5, the power transmitting coil TCX of the first conventional example is configured by stacking a power transmitting loop coil TLX composed of two parallel copper thin film wires TLX1 and TLX2, and a power transmitting loop coil TLY (not shown in Fig. 5) in a direction perpendicular to the plane of the paper in Fig. 5, via an insulating film BF similar to that of the power transmitting coil TC1 of the first embodiment. In this case, the winding center of the copper thin film wires TLX1 and TLX2 constituting the power transmitting loop coil TLX and the winding center of the copper thin film wire (described below) constituting the power transmitting loop coil TLY are made to be the same or approximately the same as each other.

[0061] As shown in Fig. 5, the power transmitting loop coil TLX is composed of a copper thin film wire TLX1 and a copper thin film wire TLX2 wound in parallel to each other in the same layer of the power transmitting coil TCX (the surface of the film BF illustrated in Fig. 5), and has an external connection terminal O1 to which the copper thin film wire TLX1 and the copper thin film wire TLX2 are connected on one side of its outermost circumference. The power transmitting loop coil TLX is composed of the copper thin film wire TLX1 and the copper thin film wire TLX2 wound in parallel in the counterclockwise direction six times (6 turns) from their outermost circumferences in Fig. 5, and the outer peripheral ends of the copper thin film wire TLX1 and the copper thin film wire TLX2 (the center of the right side in Fig. 5) are connected to the external connection terminal O1. Also, the inner peripheral end portions (the central end portions 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 connected to the copper thin film wires constituting the power transmission loop coil TLY formed on the back surface of the film BF for each of the copper thin film wires TLX1 and TLX2 by vias V11 and V12 that penetrate the film BF. The copper thin film wire TLX1 has the same width w11 (see FIGS. 2 and 5) and thickness over the entire circumference of the power transmission loop coil TLX. The copper thin film wire TLX2 also has the same width w12 (see FIGS. 2 and 5) and thickness over the entire circumference of the power transmission loop coil TLX. Therefore, the width w10 (see FIGS. 2 and 5) of each turn of the power transmission loop coil TLX is also the same over the entire circumference of the power transmission loop coil TLX. In the power transmission loop coil TLX, the width w12 of the copper thin-film wire TLX2 on the inner periphery in one turn is made wider than the width w11 of the copper thin-film wire TLX1 on the outer periphery in one turn over the entire circumference. Furthermore, each of the copper thin-film wires TLX1 and TLX2 has straight line portions on the upper, lower, left and right sides in FIG. 5, and the straight line portions are connected by curved portions having a substantially concentric arc shape.

[0062] Next, the configuration of the power transmitting loop coil TLY layered directly below the power transmitting loop coil TLX with the film BF interposed therebetween will be described with reference to Fig. 6. Note that Fig. 6 is a plan view showing only the power transmitting loop coil TLY.

[0063] As shown in a plan view in Fig. 6, the power transmission loop coil TLY, which is laminated on the power transmission loop coil TLX with a film BF sandwiched therebetween, is composed of two parallel copper thin film wires TLY1 and TLY2. In this case, the center of winding of the copper thin film wires TLY1 and TLY2 constituting the power transmission loop coil TLY is the same as or approximately the same as the center of winding of the copper thin film wires TLX1 and TLX2 constituting the power transmission loop coil TLX. Furthermore, the overall shape of the power transmission loop coil TLY is approximately square, the same as the overall shape of the power transmission loop coil TLX.

[0064] As shown in Fig. 6, the power transmitting loop coil TLY is composed of the copper thin film wire TLY1 and the copper thin film wire TLY2 wound in parallel to each other in the same layer of the power transmitting coil TCX (the back side of the film BF illustrated in Fig. 5), and has an external connection terminal O2 to connect the copper thin film wire TLY1 and the copper thin film wire TLY2 on one side of its outermost circumference. The power transmitting loop coil TLY is composed of the copper thin film wire TLY1 and the copper thin film wire TLY2 wound in parallel in the counterclockwise direction six times (6 turns) from their innermost circumferences in Fig. 6, and the outer peripheral end portions (the center 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 of the copper thin-film wire TLY1 (the central end 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 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. The copper thin-film wire TLY1 has the same width w11 and thickness over the entire circumference of the power transmission loop coil TLY. The copper thin-film wire TLY2 also has the same width w12 and thickness over the entire circumference of the power transmission loop coil TLY. For this reason, the width w10 (see FIG. 6) of each turn of 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, the width w12 of the copper thin-film wire TLY2 on the inner circumference side in one turn is wider than the width w11 of the copper thin-film wire TLY1 on the outer circumference side in one turn over the entire circumference. Further, each of the copper thin-film wires TLY1 and TLY2 has straight line portions on its upper side, lower side, left side and right side in FIG. 6, and the straight line portions are connected by curved portions having an approximately concentric arc shape.

[0065] Next, the positional relationship between the power transmitting loop coil TLX made up of the copper thin-film wires TLX1 and TLX2, and the power transmitting loop coil TLY made up of the copper thin-film wires TLY1 and TLY2 will be described with reference to Fig. 7. Fig. 7 is a plan view showing the overlapping state of the power transmitting loop coil TLX and the power transmitting loop coil TLY, in which the power transmitting loop coil TLX is indicated by a solid line, and the power transmitting loop coil TLY laminated directly below it with a film BF (not shown in Fig. 7) interposed therebetween is indicated by a dashed line.

[0066] As shown by solid lines in FIG. 7, the power transmission loop coil TLX is made up of the copper thin-film wire TLX1 and the copper thin-film wire TLX2 wound in parallel from the outer circumference to the inner circumference, and is connected at its innermost circumference by vias V11 and V12 to the copper thin-film wire TLY1 and the copper thin-film wire TLY2 that constitute the power transmission loop coil TLY. For each quarter of a turn, each curved section is formed so that the position of the straight section shifts toward the inner circumference by a quarter of the pitch PT1 (i.e., so that the winding transitions toward the inner circumference), and the copper thin-film wire TLX1 and the copper thin-film wire TLX2 are wound counterclockwise.

[0067] In contrast, in the power transmission loop coil TLY, which is formed by winding the copper thin-film wires TLY1 and TLY2, which are connected at their innermost periphery by the copper thin-film wires TLX1 and TLX2 constituting the power transmission loop coil TLX, and the copper thin-film wires TLY1 and TLY2, which are connected at their innermost periphery by the vias V11 and V12, in parallel from the inner periphery to the outer periphery, each curved portion is formed so that the position of the straight portion shifts toward the outer periphery by one-quarter of the pitch PT1 (i.e., the winding transitions toward the outer periphery) for each quarter turn, as shown by the dashed lines in Fig. 7, and the copper thin-film wires TLY1 and TLY2 are wound counterclockwise (i.e., in the same direction as the power transmission loop coil TLX). The outermost periphery of the right side of the power transmission loop coil TLX in Fig. 7 is connected to the external connection terminal O1, which protrudes outward, and the outermost periphery of the right side of the power transmission loop coil TLY in Fig. 7 is connected to the external connection terminal O2, which protrudes outward.

[0068] The power transmitting loop coil TLX and the power transmitting loop coil TLY each having the above-mentioned shapes are laminated as shown in Fig. 7, so that the position of the copper thin film wire TLX1 and the position of the copper thin film wire TLY1 when viewed from the center of the power transmitting coil TCX are different as shown in Fig. 7. Similarly, the position of the copper thin film wire TLX2 and the position of the copper thin film wire TLY2 when viewed from the center of the power transmitting coil TCX are also different as shown in Fig. 7. Thus, in the power transmitting coil TCX, the power transmitting loop coil TLX and the power transmitting loop coil TLY are laminated with the film BF sandwiched between them, without overlapping with each other. As a result, the power transmitting loop coil TLY is connected at the innermost periphery so as to have the same winding direction as the counterclockwise winding from the outermost periphery (external connection terminal O1) to the innermost periphery of the power transmitting loop coil TLX, and the power transmitting loop coil TLY is wound from the innermost periphery to the outermost periphery while maintaining the winding direction. With this structure, in the power transmission coil TCX of the first conventional example, a current flows in a counterclockwise direction from the outermost portion to the innermost portion in the power transmission loop coil TLX, and that current flows in the same counterclockwise direction from the innermost portion to the outermost portion in the power transmission loop coil TLY.

[0069] Other specifications of the power transmitting coil TC1 of the first embodiment and the power transmitting coil TCX of the first conventional example used in the experiment of the first example are as follows: In the following explanation, the specifications of the power transmitting coil TC1 and the power transmitting coil TCX are explained, but the specifications of the power receiving coil RC1 of the first embodiment used in the experiment are the same as the specifications of the power transmitting coil TC1, and the specifications of the power receiving coil of the first conventional example are the same as the specifications of the power transmitting coil TCX.

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

[0071] 8, it can be seen that in the vicinity of the frequency (85 kHz) used for power transmission by the power transmission system S, the impedance when the power transmitting coil TC1 and the power receiving coil RC1 of the first embodiment are used is about 2 / 3 lower than when the power transmitting coil TCX and the power receiving coil of the first conventional example are used. In this regard, the inventors of the present application have discovered that when the power transmission is performed at a frequency of 85 kHz, it is preferable that the impedance be less than 0.5 ohms. Even in light of this, it can be said that a configuration such as the power transmitting coil TC1 and the power receiving coil RC1 (i.e., a configuration in which the copper thin film wires constituting each coil overlap) is more preferable in terms of reducing impedance.

[0072] As described above, according to the power transmission using the power transmission system S of the embodiment including the power transmitting coil TC1 and the power receiving coil RC1 of the first embodiment, the power transmitting coil TC1 (power receiving coil RC1) has a configuration in which the power transmitting loop coil TL11 (wound from the outer circumference to the inner circumference) and the power transmitting loop coil TL12 (wound from the inner circumference to the outer circumference) made of a copper thin film wire TL111 having a plurality of straight portions and a plurality of curved portions are laminated with a film BF sandwiched therebetween. The power transmitting loop coil TL11 and the power transmitting loop coil TL12 each have the same overall shape in a plan view as a substantially square (may be a polygon other than a square), and the position of each turn of the power transmitting loop coil TL11 as viewed from the center of the power transmitting coil TC1 (power receiving coil RC1) coincides in a plan view with the position of each turn of the power transmitting loop coil TL12 as viewed from the center of the power transmitting coil TC1 (power receiving coil RC1) (see FIG. 4). Therefore, it is possible to reduce impedance due to the so-called skin effect or proximity effect, which is caused by constructing the transmitting coil TC1 and the receiving coil RC1 using thin copper wire in order to reduce weight and costs, and it is possible to achieve both weight reduction and cost reduction, improved transmission efficiency, and prevention of an increase in operating temperature.

[0073] In addition, in the winding of the transmission loop coil TL11, a winding transition for one turn is made only in one curved portion (CV11 (see Figure 4)) included in one winding, and in the winding of the transmission loop coil TL12, a winding transition for one turn is made only in one curved portion (CV12 (see Figure 4)) included in one winding, so that the positions of the corresponding thin-film conductors of the transmission coil TC1 and the receiving coil RC1 as viewed from the center can be reliably aligned in a planar 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, thereby making it possible to better achieve weight reduction and cost reduction, improved transmission efficiency, and prevention of an increase in operating temperature.

[0075] Furthermore, since the width w12 of the inner copper thin film wire TL112 (copper thin film wire TL122) is wider than the width w11 of the outer copper thin film wire TL111 (copper thin film wire TL121), the impedance can be further reduced, thereby making it possible to better achieve weight reduction and cost reduction, improved transmission efficiency, and prevention of increases in operating temperature.

[0076] (B) Second embodiment Next, a second embodiment of the present invention will be described with reference to Figures 9 and 10. Figures 9 and 10 are plan views each showing the structure of a coil according to the second embodiment.

[0077] In the above-described first embodiment of the power transmitting coil TC1 (power receiving coil RC1), the power transmitting 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 front surface of the film BF) of the power transmitting coil TC1, and the power transmitting 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) of the power transmitting coil TC1 (see Figures 2 to 4). In contrast, in a power transmission coil (and a power receiving coil) of a second embodiment described below, a first power transmission loop coil made of a thin copper wire wound from the outer periphery side to the inner periphery side, and a second power transmission loop coil made of a thin copper wire wound from the inner periphery side to the outer periphery side and connected in series to the first power transmission loop coil are formed in one layer of the power transmission coil (and the power receiving coil), and the power transmission coil (and the power receiving coil) is configured by stacking two such layers. In addition to these, in the power transmission coil (and the power receiving coil) of the second embodiment, a coil for adjusting current (hereinafter referred to as a "current adjustment coil") is connected in series to the first power transmission loop coil and the second power transmission loop coil.

[0078] The configurations of the power transmitting coil of the second embodiment and the power receiving coil of the second embodiment are basically the same, and the configurations of the power receiving loop coil in the power receiving coil of the second embodiment and the power transmitting loop coil in the power transmitting coil of the second embodiment are the same. Furthermore, the configurations of the current adjustment coil in the power transmitting coil of the second embodiment and the current adjustment coil in the power receiving coil of the second embodiment are also the same. Therefore, in the following description, only the configuration of the power transmitting coil of the second embodiment will be described. In this case, the same component parts as the power transmitting coil TC1 of the first embodiment are denoted by the same component numbers and detailed description will be omitted.

[0079] That is, as shown in the plan view of Fig. 9(a), the power transmitting coil TC2 of the second embodiment is configured by stacking a power transmitting loop coil TL21 (corresponding to the first power transmitting loop coil and the second power transmitting loop coil) made of two parallel copper thin-film wires TL211 and TL212, and a power transmitting loop coil TL22, the plan view of which is shown in Fig. 9(b), with an insulating film BF interposed between them in a direction perpendicular to the paper surface of Fig. 9. In addition, the winding center of the copper thin-film wires TL211 and TL212 constituting the power transmitting loop coil TL21 and the winding center of the copper thin-film wires TL221 and TL222 (see Fig. 9(b)) constituting the power transmitting loop coil TL22 are the same or approximately the same as each other.

[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 wound parallel to each other in the same layer of the power transmission coil TC2 (the surface of the film BF illustrated in FIG. 9(a)), and has, on one side of its outermost periphery (the center of the right side in the case shown in FIG. 9(a)), an external connection terminal O1 for connecting the copper thin-film wire TL211 and the copper thin-film wire TL212 and for connecting to the power transmission unit TR, and a connection terminal M1 and a connection terminal M2 for separately connecting the copper thin-film wire TL211 and the copper thin-film wire TL212 to the current adjustment coil of the second embodiment described later. 9(a), the copper thin-film wire TL211 and the copper thin-film wire TL212 are wound in parallel in a counterclockwise direction from the external connection terminal O1 at their outermost periphery to its innermost periphery, making two and a half turns (2.5 turns), and are further wound in parallel in a counterclockwise direction from the innermost periphery to the connection terminal M1 and the connection terminal M2. The copper thin-film wire TL211 and the copper thin-film wire TL212 cross at four points (see FIG. 9(a)) at their intersections while being insulated from each other by a laminated structure sandwiching an insulating layer and electrically connecting the copper thin-film wire TL211 and the copper thin-film wire TL212 to each other through a via VV, or by a method using a jumper wire, or the like. Further, each of the copper thin-film wires TL211 and TL212 has straight portions at the upper, lower, left and right sides in FIG. 9(a), and the straight portions are connected by curved portions having a substantially concentric arc shape. The width w21 of the copper thin-film wire TL211 is wider toward the inner periphery of the power transmission coil TC2. The width w21 is the same in each straight portion constituting the copper thin-film wire TL211, and the width w21 is changed (i.e., changed so as to be wider toward the inner periphery of the power transmission coil TC2) in each curved portion connecting the straight portions. Meanwhile, the thickness of the copper thin-film wire TL211 is the same over the entire circumference of the power transmission loop coil TL21. Meanwhile, the width w22 of the copper thin-film wire TL212 is also wider toward the inner periphery of the power transmission coil TC2, similar to the width w21.The width w22 is the same in each straight section constituting the copper thin-film wire TL212, and the width w22 is changed (i.e., changed to be wider toward the inner periphery of the power transmitting coil TC2) in each curved section connecting the straight sections. Meanwhile, the thickness of the copper thin-film wire TL212 is the same over the entire circumference of the power transmitting loop coil TL21. With the above configuration, the width w20 (see FIG. 9(a)) of each turn of the power transmitting loop coil TL21 also becomes wider toward the inner periphery of the power transmitting coil TC2. And, over the entire circumference of the power transmitting loop coil TL21, the width w22 of the copper thin-film wire TL212 on the inner periphery of one turn is wider than the width w21 of the copper thin-film wire TL211 on the outer periphery of one turn.

[0081] Next, the configuration of the power transmitting loop coil TL22 laminated directly below the power transmitting loop coil TL21 via the film BF will be described with reference to Fig. 9(b). Fig. 9(b) is a plan view showing only the power transmitting loop coil TL22. The overall shape of the power transmitting loop coil TL22 is substantially rectangular, the same as the overall shape of the power transmitting loop coil TL21.

[0082] As shown in a plan view in Fig. 9(b), the power transmission loop coil TL22 laminated on the power transmission loop coil TL21 with the film BF sandwiched therebetween is composed of a copper thin-film wire TL221 and a copper thin-film wire TL222 wound in parallel to each other in the same layer of the power transmission coil TC2 (the back surface of the film BF illustrated in Fig. 9(a)), and has an external connection terminal O1 on one side of its outermost periphery (the center of the right side in the case shown in Fig. 9(b)) for connecting the copper thin-film wire TL221 and the copper thin-film wire TL222 and for connecting the power transmission unit 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. In this case, the external connection terminal O1 and the connection terminal M1 and the connection terminal M2 are the same as the external connection terminal O1 and the connection terminal M1 and the connection terminal M2 illustrated in Fig. 9(a). 9(b), the copper thin-film wire TL221 and the copper thin-film wire TL222 are wound in parallel in the counterclockwise direction from the external connection terminal O1 at their outermost portion to its innermost portion for two and a half turns (2.5 turns), and are further wound in parallel in the counterclockwise direction for two and a half turns (2.5 turns) from the innermost portion to the connection terminal M1 and the connection terminal M2. The copper thin-film wire TL221 and the copper thin-film wire TL222 cross at four points (see FIG. 9(b)) at their intersections while being insulated from each other by a laminated structure sandwiching an insulating layer and electrically connecting the copper thin-film wire TL221 and the copper thin-film wire TL222 to each other through vias VV, or by a method using jumper wires, etc. Furthermore, each of the copper thin-film wires TL221 and TL222 has straight sections at the top, bottom, left and right sides in Fig. 9(b), and the straight sections are connected by curved sections of a substantially concentric arc shape. 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 is wider toward the inner circumference of the power transmission coil TC2. The width w21 is the same for each straight section constituting the copper thin-film wire TL221, and the width w21 is changed (i.e., changed to be wider toward the inner circumference of the power transmission coil TC2) at each curved section connecting the straight sections.On the other hand, the thickness of the copper thin-film wire TL221 is uniform over the entire circumference of the power transmitting loop coil TL22. On the other hand, the width w22 of the copper thin-film wire TL222 is the same as the width w22 of the copper thin-film wire TL212 of the power transmitting loop coil TL21 shown in FIG. 9(a), and like the width w21 of the copper thin-film wire TL221, the width w22 is wider toward the inner circumference of the power transmitting coil TC2. This width w22 is uniform in each straight section constituting the copper thin-film wire TL222, and the width w22 is changed (i.e., changed so as to be wider toward the inner circumference of the power transmitting coil TC2) in each curved section connecting the straight sections. On the other hand, the thickness of the copper thin-film wire TL222 is uniform over the entire circumference of the power transmitting loop coil TL21. With the above configuration, the width w20 of each turn of the power transmitting loop coil TL22 (same as the width w20 in the power transmitting loop coil TL21 shown in FIG. 9(a) (see FIG. 9(b)) also becomes wider toward the inner periphery of the power transmitting coil TC2. And, over the entire circumference of the power transmitting loop coil TL22, the width w22 of the copper thin-film wire TL222 on the inner periphery in one turn is wider than the width w21 of the copper thin-film wire TL221 on the outer periphery in that one turn.

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

[0084] As shown in a plan view in Fig. 10(a), the current adjustment coil TL23 laminated directly below the power transmission loop coil TL22 with a film sandwiched therebetween is composed of a copper thin-film wire TL231 and a copper thin-film wire TL232 wound in parallel to each other in the same layer of the power transmission coil TC2, and its outermost end portion serves as a connection terminal M1 and a connection terminal M2 for separately connecting the copper thin-film wire TL231 and the copper thin-film wire TL232 to the copper thin-film wire TL211 and the copper thin-film wire TL212 and the copper thin-film wire TL221 and the copper thin-film wire TL222, respectively. In this case, the connection terminal M1 and the connection terminal M2 are the same as the connection terminal M1 and the connection terminal M2 shown in Fig. 9. On the other hand, the innermost end portion of the copper thin-film wire TL231 and the copper thin-film wire TL232 serves as an external connection terminal O2 for connecting the copper thin-film wire TL231 and the copper thin-film wire TL232 to the power transmission unit TR. The external connection terminal O2 is configured to pass through the film between the current adjustment coil TL23 and the power transmitting loop coil TL22 and the film BF between the power transmitting loop coil TL22 and the power transmitting loop coil TL21, and is exposed on the same surface as the external connection terminal O1 shown in Fig. 9(a). The current adjustment coil TL23 is configured by winding the copper thin-film wire TL231 and the copper thin-film wire TL232 counterclockwise in parallel from the connection terminals M1 and M2 at their outermost peripheries to the external connection terminal O2 at their innermost periphery in Fig. 10(a) five times (five turns). As a result, the total number of electrical turns (five turns) of the power transmitting loop coil TL21 and the power transmitting loop coil TL22 is an integer multiple (single) of the number of turns of the current adjustment coil TL23. 10(a), each of the copper thin film wires TL231 and TL232 has a straight line portion provided on its upper side, lower side, left side, and right side, and the straight line portions are connected by curved portions having a substantially concentric arc shape. Also, the winding center of the copper thin film wires TL211 and TL212, the winding center of the copper thin film wires TL221 and TL222, and the winding center of the copper thin film wires TL231 and TL232 are the same or substantially the same.The width w21 of the copper thin-film wire TL231 is the same as the width w21 of the copper thin-film wire TL211 of the power transmitting loop coil TL21 shown in Fig. 9(a) and the width w21 of the copper thin-film wire TL221 of the power transmitting loop coil TL22 shown in Fig. 9(b), and is wider toward the inner circumference of the power transmitting coil TC2. The width w21 is the same in each straight portion constituting the copper thin-film wire TL231, and is changed (i.e., changed to be wider toward the inner circumference of the power transmitting coil TC2) in each curved portion connecting the straight portions. Meanwhile, the thickness of the copper thin-film wire TL231 is the same around the entire circumference of the current adjustment coil TL23. On the other hand, the width w22 of the copper thin-film wire TL232 is the same as the width w22 of the copper thin-film wire TL212 shown in Fig. 9(a) and the width w22 of the copper thin-film wire TL222 shown in Fig. 9(b), and like the width w21 of the copper thin-film wire TL231, it becomes wider toward the inner periphery of the power transmission coil TC2. This width w23 is the same in each straight portion constituting the copper thin-film wire TL232, and the width w22 is changed (i.e., changed to become wider toward the inner periphery of the power transmission coil TC2) in each curved portion connecting the straight portions. On the other hand, the thickness of the copper thin-film wire TL232 is the same over the entire circumference of the current adjustment coil TL23. With the above configuration, the width w20 of each turn of the current adjustment coil TL23 (same as the width w20 of the power transmission loop coil TL21 shown in FIG. 9(a) and the width w20 of the power transmission loop coil TL22 shown in FIG. 9(b); see FIG. 10(a)) also becomes wider toward the inner periphery of the power transmission coil TC2. And, in the current adjustment coil TL23, the width w22 of the copper thin-film wire TL232 on the inner periphery in one turn is wider than the width w21 of the copper thin-film wire TL231 on the outer periphery in one turn over the entire circumference.

[0085] Next, the positional relationship between the power transmitting loop coil TL21 made up of the copper thin film wire TL211 and the copper thin film wire TL212, the power transmitting loop coil TL22 made up of the copper thin film wire TL221 and the copper thin film wire TL222, and the power transmitting loop coil TL23 made up of the copper thin film wire TL231 and the copper thin film wire TL232 will be described with reference to Fig. 10(b). Fig. 10(b) is a plan view showing an overlapping state of the power transmitting loop coil TL21, the power transmitting loop coil TL22, and the current adjustment coil TL23, in which the power transmitting loop coil TL21 is indicated by a solid line, the power transmitting loop coil TL22 laminated directly below it with a film BF (not shown in Fig. 10(b)) interposed therebetween is indicated by a dashed line, and the current adjustment coil TL23 laminated directly below the power transmitting loop coil TL22 with a film interposed therebetween is indicated by a dashed line.

[0086] As shown by solid lines in Fig. 10(b), in the power transmission loop coil TL21 made up of the copper thin-film wire TL211 and the copper thin-film wire TL212 wound in parallel, the copper thin-film wire TL211 and the copper thin-film wire TL212 are wound counterclockwise from the external connection terminal O1 to the connection terminal M1 and the connection terminal M2 such that the position of the straight line portion shifts to the outer periphery or inner periphery (i.e., the winding transitions to the outer periphery or inner periphery) by one pitch PT2 (see Fig. 10(b)) in the winding of each of the copper thin-film wire TL211 and the copper thin-film wire TL212 only in one of the four curved portions included in one turn (for example, the curved portion in the lower right corner in Fig. 10(b)). As a result, the curved portion in the power transmission loop coil TL21 where the winding transitions to the outer periphery or inner periphery by one pitch PT2 is included in, for example, the group of four curved portions in the lower right corner in Fig. 10(b).

[0087] In contrast, in the power transmission loop coil TL22, which is composed of the copper thin-film wires TL211 and TL212 that constitute the power transmission loop coil TL21 and the copper thin-film wires TL221 and TL222 that are connected at their outermost portions by the external connection terminal O1 and the connection terminals M1 and M2, as shown by the dashed lines in FIG. 10(b) , the copper thin-film wires TL221 and TL222 are wound counterclockwise (i.e., in the same direction as the power transmission loop coil TL21) such that the position of the straight portion in each winding of the copper thin-film wire TL221 and the copper thin-film wire TL222 shifts to the outer periphery or inner periphery by one pitch PT2 (i.e., the winding transitions to the outer periphery or inner periphery) only in one curved portion (for example, the curved portion in the lower right corner in FIG. 10(b) ) out of the four curved portions included in one winding. As a result, the curved portion in the power transmission loop coil TL22 where the winding transitions to the outer periphery or inner periphery by one pitch PT2 is included in, for example, a group of four curved portions in the lower right corner in Fig. 10(b). One end of the outermost circumference on the right side of the power transmission loop coil TL21 and the power transmission loop coil TL22 in Fig. 10(b) is connected to the external connection terminal O1 that protrudes outward, and the other end of the outermost circumference on the right side of the power transmission loop coil TL21 and the power transmission loop coil TL22 in Fig. 10(b) serves as the connection terminal M1 and the connection terminal M2.

[0088] Furthermore, in the current adjustment coil TL23 formed by winding the copper thin-film wires TL211 and TL212, and the copper thin-film wires TL231 and TL232 connected to the copper thin-film wires TL221 and TL222 via connection terminals M1 and M2, in parallel from the outer circumference to the inner circumference, as shown by the dashed dotted line in FIG. 10(b) , the copper thin-film wires TL231 and TL232 are wound counterclockwise (i.e., in the same direction as the power transmission loop coil TL21 and the power transmission loop coil TL22) such that the position of the straight portion in each winding of the copper thin-film wire TL231 and the copper thin-film wire TL232 shifts toward the inner circumference by one pitch PT2 (i.e., the winding transitions toward the inner circumference) only in one curved portion (for example, the curved portion in the lower right corner in FIG. 10(b) ) out of the four curved portions included in one winding. As a result, the curved portion where the winding of the current adjustment coil TL23 transitions to the inner periphery by one pitch PT2 is, for example, a group of four curved portions lined up from the outer periphery to the inner periphery at the lower right corner in Fig. 10(b). The outermost end of the current adjustment coil TL23 is the connection terminal M1 and the connection terminal M2, and the innermost end is the external connection terminal O2.

[0089] 10(b), the positions of the copper thin-film wire TL211, the copper thin-film wire TL221, and the copper thin-film wire TL231 as viewed from the center of the power transmitting coil TC2 are the same except for the curved portions where the windings transition and the connection portions to the external connection terminals O1 and O2 and the connection terminals M1 and M2. Similarly, the positions of the copper thin-film wire TL212, the copper thin-film wire TL222, and the copper thin-film wire TL232 as viewed from the center of the power transmitting coil TC2 are the same except for the curved portions where the windings transition and the connection portions to the external connection terminals O1 and O2 and the connection terminals M1 and M2. Thus, in the power transmission coil TC2, the power transmission loop coils TL21 to TL23 are laminated with a film BF or the like sandwiched between them, with 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 overlapping each other. As a result, the copper thin-film wires TL211, TL212, TL221, and TL222 are wound counterclockwise in the order of the outermost periphery of the power transmission loop coil TL21 and the outermost periphery of the power transmission loop coil TL22 (external connection terminal O1) →their innermost periphery →the connection terminals M1 and M2 of the outermost periphery. The copper thin-film wires TL231 and TL232 of the current adjustment coil TL23 are then wound counterclockwise from the connection terminals M1 and M2 to their innermost periphery, and the innermost periphery end is connected to the external connection terminal O2. With this structure, in the second embodiment, in the power transmission coil TC2, current flows in the counterclockwise direction from the external connection terminal O1 to the connection terminal M1 and the connection terminal 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 terminal M1 and the connection terminal M2 to the external connection terminal O2 in the current adjustment coil TL23.

[0090] The method for manufacturing the power transmitting coil TC2 and the power receiving coil RC2 of the second embodiment is basically the same as the method for manufacturing the power transmitting coil TC1 and the power receiving coil RC1 of the first embodiment, and therefore detailed description will be omitted.

[0091] Next, measurement results (simulation results) of impedance and the like when the configuration of the power transmitting coil or the power receiving coil is changed in a power transfer system using the power transmitting coil TC2 or the power receiving coil RC2 of the second embodiment having the configuration shown in Figures 9 and 10 will be described as a second example using the following Table 1. Note that Table 1 shows impedance and the like as the effect of the configuration of the power transmitting coil TC2 or the power receiving coil RC2 of the second embodiment, and also lists impedance and the like as the effect of the configuration of the power transmitting coil or the power receiving coil of the third embodiment described later. [Table 1]

[0092] Here, in the second conventional example to be compared with the second embodiment, the number of turns of the power transmission loop coil TL21 and the power transmission loop coil TL22 in the power transmission coil TC2 or the power receiving coil RC2 of the second embodiment is eight, as illustrated in Table 1, and the rest of the structure, such as the number of turns of the current adjustment coil TL23, is the same as that of the power transmission coil TC2 or the power receiving coil RC2 of the second embodiment. As a result, in the power transmission coil and the power receiving coil of the second conventional example, the number of turns of each of the power transmission loop coils included therein (eight turns) is not an integer multiple of the number of turns of the current adjustment coil RL23 (five turns), and therefore the positions of the thin copper wires constituting the power transmission loop coils etc. and the current adjustment coil RL23 do not overlap when viewed from the center.

[0093] Other specifications of the power transmitting coil TC2 of the second embodiment and the power transmitting coil of the second conventional example used in the experiment of the second example are as follows: In the following explanation, specifications of the power transmitting coil TC2 and the power transmitting coil of the second conventional example are explained, but the specifications of the power receiving coil RC2 of the second embodiment used in the experiment are the same as the specifications of the power transmitting coil TC2, and the specifications of the power receiving coil of the second conventional example are the same as the specifications of the power transmitting coil of the second conventional example.

[0094] Size of the transmitting coil TC2 (receiving coil RC2) and the transmitting coil and receiving coil of the second conventional example: long side 266 mm × short side 160 mm Pitch PT2 (see Figure 10(b)): 5.5 mm (outermost part) to 9.5 mm (innermost part) ·Thickness of copper thin film wire in TL211 etc.: 0.2mm Distance between transmitter and receiver coils: 40mm Ferrite sheets of the same thickness as the transmitting coil and the receiving coil are provided on the opposing surfaces of the transmitting coil and the receiving coil.

[0095] As shown by hatching in Table 1, at the frequency (85 kHz) used in power transmission by the power transmission system of the second embodiment, the use of the transmitting coil TC2 and the receiving coil RC2 of the second embodiment provides better performance in terms of impedance and Q value than the use of the transmitting coil and the receiving coil of the second conventional example. In other words, it can be said that a configuration such as the transmitting coil TC2 and the receiving coil RC2 (in which the copper thin film wires constituting each coil overlap) is more preferable in terms of reducing impedance and inductance and improving the Q value.

[0096] As described above, according to power transmission using the power transmission system of the second embodiment including the transmitting coil TC2 and receiving coil RC2 of the second embodiment, in addition to the effects of power transmission using the power transmission system S of the first embodiment, the widths w21 and w22 of the copper thin film wires TL211 and TL212, the copper thin film wires TL221 and TL222, and the copper thin film wires TL231 and TL232 are wider the closer the winding is to the center of the transmitting coil TC2, etc., so that the width of the copper thin film wire is wider toward the center of the transmitting coil TC2, etc. where current is concentrated, and the impedance of the transmitting coil TC2, etc. can be further reduced.

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

[0098] In the above-described power transmitting coil TC1 (power receiving coil RC1) of the first embodiment, the power transmitting coil TC1 is configured from two power transmitting loop coils TL11 and TL12 (see FIGS. 2 to 4). In contrast, the power receiving coil of the third embodiment described below is configured by stacking a first power receiving loop coil having a similar configuration to the power transmitting loop coil TL21 of the second embodiment, a second power receiving loop coil having a similar configuration to the power transmitting loop coil TL22 of the second embodiment, and a coil for adjusting current (hereinafter referred to as a "current adjustment coil") that is independent of the first power receiving loop coil and the second power receiving loop coil.

[0099] In the following description, the power receiving coil of the third embodiment will be mainly described, but the power receiving coil of the third embodiment and the power transmitting coil of the third embodiment may have the same configuration. In the following description, the same components as those in the power receiving coil RC1 (i.e., the power transmitting coil TC1) of the first embodiment will be denoted by the same component numbers and detailed description 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 is configured to include external connection terminals O1 and 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 is simply referred to as a "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 terminals O1 and O2 are external connection terminals for connecting the power receiving coil RC3 to the power receiving unit RV. The power receiving loop coil RL31 and the power receiving loop coil RL32 are connected in series to the external connection terminals O1 and O2 and are connected in parallel to each other. Furthermore, the current adjustment coil RL33 and the current adjustment coil RL34 are insulated from the power receiving loop coil RL31 and the power receiving loop coil RL32 and are connected in series to each other via a connection terminal M3. The current adjustment capacitor Cp is connected to both ends of the current adjustment coil RL33 and the current adjustment coil RL34. Note that the current adjustment capacitor and the two current adjustment coils having the same configuration as the current adjustment capacitor Cp, the current adjustment coil RL33, and the current adjustment coil RL34 may be provided in the power transmitting coil of the third embodiment that configures the power transmission system of the third embodiment together with the power receiving coil RC3. In this case, the current adjustment capacitor Cp, the current adjustment coil RL33, and the current adjustment coil RL34 mainly contribute to reducing impedance and improving transmission efficiency.

[0101] Next, a specific configuration of the power receiving coil RC3 of the third embodiment will be described with reference to Fig. 12 to Fig. 14. A power receiving loop coil RL31 (corresponding to the above-mentioned first power receiving loop coil) of the third embodiment described below has a configuration basically similar to that of the power transmitting loop coil TL21 of the second embodiment, except for the number of turns. Similarly, a power receiving loop coil RL32 (corresponding to the above-mentioned second power receiving loop coil) of the third embodiment has a configuration basically similar to that of the power transmitting 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 is configured by stacking a power receiving loop coil RL31 made up of two parallel copper thin film wires RL311 and RL312, and a power receiving loop coil RL32, the plan view of which is shown in Fig. 12(b), via an insulating film BF in the direction perpendicular to the paper surface of Fig. 12. In addition, the winding center of the copper thin film wires RL311 and RL312 and the winding center of the copper thin film wires RL321 and RL322 (see Fig. 12(b)) are made to be the same or approximately the same as each other.

[0103] As shown in Fig. 12(a), the power receiving loop coil RL31 is composed of a copper thin film wire RL311 and a copper thin film wire RL312 wound in parallel to each other in the same layer of the power receiving coil RC3 (the surface of the film BF illustrated in Fig. 12(a)), and has an external connection terminal O1 and an external connection terminal O2 on one side of its outermost circumference (the center of the right side in the case shown in Fig. 12(a)) for connecting the copper thin film wire RL311 and the copper thin film wire RL312 and for connecting to the power transmitting unit TR. The power receiving loop coil RL31 is composed of the copper thin film wire RL311 and the copper thin film wire RL312 wound in parallel in the counterclockwise direction from the external connection terminal O1 at the outermost circumference to its innermost circumference in Fig. 12(a) four times (four turns), and further wound in parallel in the counterclockwise direction from the innermost circumference to the external connection terminal O2. In addition, the copper thin-film wire RL311 and the copper thin-film wire RL312 cross each other at seven points (see FIG. 12(a)) while being insulated from each other by a laminated structure in which the copper thin-film wire RL311 and the copper thin-film wire RL312 are electrically connected to each other by vias VV sandwiched between insulating layers, or by a method using jumper wires. Furthermore, each of the copper thin-film wire RL311 and the copper thin-film wire RL312 has straight sections at the upper side, lower side, left side, and right side in FIG. 12(a), and the straight sections are connected by curved sections having a substantially concentric arc shape. The width w31 of the copper thin-film wire RL311 is wider toward the inner periphery of the power receiving coil RC3. The width w31 is the same for each straight section constituting the copper thin-film wire RL311, and the width w31 is changed (i.e., changed so as to be wider toward the inner periphery of the power receiving coil RC3) at each curved section connecting the straight sections. On the other hand, the thickness of the copper thin-film wire RL311 is the same all around the power receiving loop coil RL31. On the other hand, like the width w31, the width w32 of the copper thin-film wire RL312 also becomes wider toward the inner periphery of the power receiving coil RC3. This width w32 is the same in each straight section that constitutes the copper thin-film wire RL312, and the width w32 is changed (i.e., changed to become wider toward the inner periphery of the power receiving coil RC3) in each curved section that connects the straight sections. On the other hand, the thickness of the copper thin-film wire RL312 is the same all around the power receiving loop coil RL31.With the above configuration, the width w30 of each turn of the power receiving loop coil RL31 (see FIG. 12(a)) also becomes wider toward the inner periphery of the power receiving coil RC3. Also, over the entire circumference of the power receiving loop coil RL31, the width w32 of the copper thin-film wire RL312 on the inner periphery in one turn is wider than the width w31 of the copper thin-film wire RL311 on the outer periphery in that one turn.

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

[0105] As shown in a plan view in Fig. 12(b), the power receiving loop coil RL32 laminated on the power receiving loop coil RL31 with the film BF sandwiched therebetween is composed of a copper thin-film wire RL321 and a copper thin-film wire RL322 wound parallel to each other in the same layer of the power receiving coil RC3 (the back side of the film BF illustrated in Fig. 12(a)), and has an external connection terminal O1 and an external connection terminal O2 on one side of the outermost circumference (the center of the right side in the case shown in Fig. 12(b)) for connecting the copper thin-film wire RL321 and the copper thin-film wire RL322 and for connecting to the power transmitting unit TR in parallel with the power receiving loop coil RL31. In this case, 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). 12(b), the copper thin film wire RL321 and the copper thin film wire RL322 are wound in parallel in a counterclockwise direction four times (four turns) from the external connection terminal O1 at the outermost periphery to the innermost periphery, and further wound in parallel in a counterclockwise direction four times (four turns) from the innermost periphery to the external connection terminal O2. The copper thin film wire RL321 and the copper thin film wire RL322 cross each other at seven points (see FIG. 12(b)) while being insulated from each other by a laminated structure sandwiching an insulating layer and electrically connecting the copper thin film wire RL321 and the copper thin film wire RL322 to each other via VV, or by a method using a jumper wire, etc. Furthermore, each of the copper thin-film wires RL321 and RL322 has straight sections at the top, bottom, left and right sides in FIG. 12(b), and the straight sections are connected by curved sections that are substantially concentric. 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 is wider toward the inner circumference of the power receiving coil RC3. The width w31 is the same in each straight section constituting the copper thin-film wire RL321, and the width w31 is changed (i.e., changed to be wider toward the inner circumference of the power receiving coil RC3) in each curved section connecting the straight sections. Meanwhile, the thickness of the copper thin-film wire RL321 is the same around the entire circumference of the power receiving loop coil RL32.On the other hand, the width w32 of the copper thin-film wire RL322 is the same as the width w32 of the copper thin-film wire RL312, and like the width w31, it is wider toward the inner circumference of the power receiving coil RC3. The width w32 is the same in each straight section constituting the copper thin-film wire RL322, and the width w32 is changed (i.e., changed to be wider toward the inner circumference of the power receiving coil RC3) in each curved section connecting the straight sections. On the other hand, the thickness of the copper thin-film wire RL322 is the same over the entire circumference of the power receiving loop coil RL32. With the above configuration, the width w30 (see FIG. 12(b)) of each turn of the power receiving loop coil RL32 is also wider toward the inner circumference of the power receiving coil RC3. And, in the power receiving loop coil RL32, the width w32 of the copper thin-film wire RL322 on the inner circumference side in one turn is wider than the width w31 of the copper thin-film wire RL321 on the outer circumference side in one turn over the entire circumference.

[0106] Next, the configuration of the current adjustment coil RL33, which is further laminated directly below the power receiving loop coil RL32 via a film (not shown) (made of the same material as the film BF) in the power receiving coil RC3 of the third embodiment, will be described with reference to Fig. 13(a). Fig. 13(a) is a plan view showing only the current adjustment coil RL33. The overall shape of the current adjustment coil RL33 and a current adjustment coil RL34 (described later) is substantially rectangular, the same as the overall shapes of the power receiving loop coil RL31 and the power receiving loop coil RL32.

[0107] As shown in a plan view in FIG. 13(a), the current adjustment coil RL33, which is laminated directly below the power receiving loop coil RL32 with a film sandwiched therebetween, is composed of a copper thin film wire RL331 and a copper thin film wire RL332 wound in parallel to each other in the same layer of the power receiving coil RC3, and the outermost end portion serves as a connection terminal M3 for separately connecting the copper thin film wire RL331 and the copper thin film wire RL332 in series with the copper thin film wire RL341 and the copper thin film wire RL342 of the current adjustment coil RL34 described with reference to FIG. 13(b). In this case, the copper thin film wire RL331 to the copper thin film wire RL342 correspond to an example of the "adjustment winding circuit" of the present invention. On the other hand, the innermost end portion of the copper thin film wire RL331 and the copper thin film wire RL332 is connected to the copper thin film wire RL331 and the copper thin film wire RL332 and is also connected to the current adjustment capacitor Cp. The current adjustment coil RL33 is configured by winding the copper thin film wire RL331 and the copper thin film wire RL332 in parallel clockwise for eight turns (8 turns) from the outermost connection terminal M3 to the innermost connection terminal M3 in FIG. 13(a). Furthermore, each of the copper thin film wire RL331 and the copper thin film wire RL332 has straight portions on the upper side, lower side, left side, and right side in FIG. 13(a), and the straight portions are connected by curved portions having a substantially concentric arc shape. The winding centers of the copper thin film wire RL311 and the copper thin film wire RL312, the winding centers of the copper thin film wire RL321 and the copper thin film wire RL322, and the winding centers of the copper thin film wire RL331 and the copper thin film wire RL332 are the same or substantially the same. 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 is wider toward the inner circumference of the power receiving coil RC3. The width w31 is the same in each straight section constituting the copper thin-film wire RL331, and the width w31 is changed (i.e., changed to be wider toward the inner circumference of the power receiving coil RC3) in each curved section connecting the straight sections. Meanwhile, the thickness of the copper thin-film wire RL331 is the same over the entire circumference of the current adjustment coil RL33. Meanwhile, the width w32 of the copper thin-film wire RL332 is the same as the width w32 of the copper thin-film wire RL312 of the power receiving loop coil RL31 shown in FIG. 12(a) and the width w32 of the copper thin-film wire RL322 of the power receiving loop coil RL32 shown in FIG. 12(b), and is wider toward the inner circumference of the power receiving coil RC3, like the width w31 of the copper thin-film wire RL331. This width w32 is the same in each straight section that constitutes the copper thin-film wire RL332, and the width w32 varies (i.e., varies so as to become wider toward the inner periphery of the power receiving coil RC3) in each curved section that connects the straight sections. Meanwhile, the thickness of the copper thin-film wire RL332 is the same over the entire circumference of the current adjustment coil RL33. With the above configuration, the width w30 of each turn of the current adjustment coil RL33 (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) (see FIG. 13(a)) also becomes wider toward the inner periphery of the power receiving coil RC3.In the current adjustment coil RL33, the width w32 of the copper thin-film wire RL332 on the inner periphery in one turn is made wider than the width w31 of the copper thin-film wire RL331 on the outer periphery in one turn over the entire circumference.

[0108] Next, in the power receiving coil RC3 of the third embodiment, the configuration of the current adjustment coil RL34 further laminated directly below the current adjustment coil RL33 via a film (not shown, made of the same material as the film BF) 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.

[0109] As shown in a plan view in Fig. 13(b), the current adjustment coil RL34 laminated directly below the current adjustment coil RL33 with a film sandwiched therebetween is composed of a copper thin film wire RL341 and a copper thin film wire RL342 wound in parallel to each other in the same layer of the receiving coil RC3, and its outermost end serves as the connection terminal M3 for separately connecting the copper thin film wire RL341 and the copper thin film wire RL342 to the copper thin film wire RL331 and the copper thin film wire RL332 of the current adjustment coil RL33 in series. 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 end of the copper thin film wire RL341 and the copper thin film wire RL342 serves as a 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 by winding the copper thin film wire RL341 and the copper thin film wire RL342 in parallel clockwise eight times (8 turns) from the connection terminal M34 at the innermost periphery to the connection terminal M3 at the outermost periphery in Fig. 13(b). Furthermore, each of the copper thin film wire RL341 and the copper thin film wire RL342 has a straight line portion at the upper side, lower side, left side, and right side in Fig. 13(b), and each straight line portion is connected by a curved portion having a substantially concentric arc shape. In addition, the winding center of the copper thin film wire RL311 and the copper thin film wire RL312, the winding center of the copper thin film wire RL321 and the copper thin film wire RL322, the winding center of the copper thin film wire RL331 and the copper thin film wire RL332, and the winding center of the copper thin film wire RL341 and the copper thin film wire RL342 are the same or substantially the same. 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 is wider toward the inner periphery of the power receiving coil RC3. The width w31 is the same in each straight portion constituting the copper thin-film wire RL341, and the width w31 is changed (i.e., changed to be wider toward the inner periphery of the power receiving coil RC3) in each curved portion connecting the straight portions. Meanwhile, the thickness of the copper thin-film wire RL341 is the same around the entire circumference of the current adjustment coil RL34.On the other hand, the width w32 of the copper thin film wire RL342 is the same as the width w32 of the copper thin film wire RL312, the width w32 of the copper thin film wire RL322, and the width w32 of the copper thin film wire RL332, and like the width w31 of the copper thin film wire RL341, it becomes wider toward the inner periphery of the power receiving coil RC3. This width w32 is the same in each straight portion constituting the copper thin film wire RL342, and the width w32 is changed (i.e., changed to become wider toward the inner periphery of the power receiving coil RC3) in each curved portion connecting the straight portions. On the other hand, the thickness of the copper thin film wire RL342 is the same around the entire circumference of the current adjustment coil RL34. With the above configuration, the width w30 of each turn of the current adjustment coil RL34 (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); see FIG. 13(b)) also becomes wider toward the inner periphery of the power receiving coil RC3. And in the current adjustment coil RL34, the width w32 of the copper thin-film wire RL342 on the inner periphery in one turn is wider than the width w31 of the copper thin-film wire RL341 on the outer periphery in that one turn, all around the circumference.

[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 (16 turns) of the current adjustment coil TL33 and the current adjustment coil RL34 connected in series is an integer multiple (twice) of the total (electrical) number of turns (8 turns) of the power receiving loop coil TL31 and the power receiving loop coil TL32 connected in parallel.

[0111] Next, the positional relationship between the power receiving loop coil RL31 consisting of the copper thin film wire RL311 and the copper thin film wire RL312, the power receiving loop coil RL32 consisting of the copper thin film wire RL321 and the copper thin film wire RL322, the current adjustment coil RL33 consisting of the copper thin film wire RL331 and the copper thin film wire RL332, and the current adjustment coil RL34 consisting of the copper thin film wire RL341 and the copper thin film wire RL342 will be described with reference to Figure 14. Figure 14 is a plan view showing the overlapping state of the power receiving loop coil RL31, the power receiving loop coil RL32, the current adjustment coil RL33, and the current adjustment coil RL34, with the power receiving loop coil RL31 shown by a solid line, the power receiving loop coil RL32 stacked directly below it with a film BF (not shown in Figure 14) interposed between them shown by a dashed line, the current adjustment coil RL33 stacked directly below the power receiving loop coil RL32 with a film interposed between them shown by a dotted line, and the current adjustment coil RL34 stacked directly below the current adjustment coil RL33 with a film interposed between them shown by a two-dot dashed line.

[0112] As shown by solid lines in Fig. 14, in the power receiving loop coil RL31 consisting of the copper thin film wire RL311 and the copper thin film wire RL312 wound in parallel, the copper thin film wire RL311 and the copper thin film wire RL312 are wound counterclockwise from the external connection terminal O1 to the external connection terminal O2 such that the position of the straight line portion shifts to the outer periphery or inner periphery (i.e., the winding transitions to the outer periphery or inner periphery) by one pitch PT3 (see Figs. 12(b) and 14) in the winding of each of the copper thin film wire RL311 and the copper thin film wire RL312 in only one of the four curved portions included in one turn (for example, the curved portion in the lower right corner in Fig. 14). As a result, the curved portion in the power receiving loop coil RL31 where the winding transitions to the outer periphery or inner periphery by one pitch PT3 is included in, for example, the group of seven curved portions in the lower right corner in Fig. 14.

[0113] In contrast, in the power receiving loop coil RL32, which is composed of the copper thin-film wires RL311 and RL312 that constitute the power receiving loop coil RL31 and the copper thin-film wires RL321 and RL322 that are connected at their outermost portions by the external connection terminals O1 and O2, as shown by the dashed lines in FIG. 14, in only one of the four curved portions included in one turn (for example, the curved portion in the lower right corner in FIG. 14), the copper thin-film wires RL321 and RL322 are wound counterclockwise (i.e., in the same direction as the power receiving loop coil RL31) so that the position of the straight portion in each winding of the copper thin-film wire RL321 and the copper thin-film wire RL322 shifts to the outer or inner side by one pitch PT3 (i.e., so that the winding transitions to the outer or inner side). As a result, the curved portion in the power receiving loop coil RL32 where the winding transitions to the outer or inner side by one pitch PT3 is included in, for example, a group of four curved portions in the lower right corner of Fig. 14. The outermost end portions of the power receiving loop coil RL31 and the power receiving loop coil RL32 on the right side in Fig. 14 are connected to the external connection terminal O1 and the external connection terminal O2, respectively.

[0114] Furthermore, in the current adjustment coil RL33 in which the copper thin film wire RL331 and the copper thin film wire RL332 are wound in parallel from the outer circumference to the inner circumference, as shown by the dashed line in Fig. 14, in only one of the four curved portions included in one turn (for example, the curved portion at the lower right corner in Fig. 14), the copper thin film wire RL331 and the copper thin film wire RL332 are wound clockwise so that the position of the straight portion in each turn of the copper thin film wire RL331 and the copper thin film wire RL332 shifts to the inner circumference side by one pitch PT3 (i.e., the winding transitions to the inner circumference side). As a result, the curved portion in the current adjustment coil RL33 where the winding transitions to the inner circumference side by one pitch PT3 is, for example, a group of seven curved portions arranged from the outer circumference side to the inner circumference side at the lower right corner in Fig. 14. The outermost end of the current adjustment coil RL33 is the connection terminal M3, and the innermost end thereof is the connection terminal M33.

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

[0116] 14, the positions of the copper thin-film wire RL311, the copper thin-film wire RL321, the copper thin-film wire RL331, and the copper thin-film wire RL341 as viewed from the center of the power receiving coil RC3 are the same except for the curved portions where the respective windings transition, and the connection portions to the external connection terminals O1 and O2, the connection terminals M3, and the connection terminals M33 and M34. Similarly, the positions of the copper thin-film wire RL312, the copper thin-film wire RL322, the copper thin-film wire RL332, and the copper thin-film wire RL342 as viewed from the center of the power receiving coil RC3 are the same except for the curved portions where the respective windings transition, and the connection portions to the external connection terminals O1 and O2, the connection terminals M3, and the connection terminals M33 and M34. Therefore, in 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 are stacked with a film BF or the like in between. As a result, the copper thin-film wire RL311, the copper thin-film wire RL312, the copper thin-film wire RL321, and the copper thin-film wire RL322 are wound counterclockwise in the order of the outermost portion of the power receiving loop coil RL31 and the outermost portion of the power receiving loop coil RL32 (external connection terminals O1) → their innermost portions → the external connection terminal O2 of the outermost 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 periphery, and 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 M3 at the innermost periphery, and the 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 explained later as a third embodiment.With the above-described structure, in the receiving coil RC3 of the third embodiment, a current flows between the external connection terminal O1 and the external connection terminal O2 in the receiving loop coil RL31 and the receiving loop coil RL32, and the current value is adjusted by the current adjustment coil RL33, the current adjustment coil RL34 and the current adjustment capacitor Cp.

[0117] The method for manufacturing the power transmitting coil and the power receiving coil RC3 of the third embodiment is basically the same as the method for manufacturing the power transmitting coil TC1 and the power receiving coil RC1 of the first embodiment, and therefore detailed description will be omitted.

[0118] Next, in a power transmission system using the power receiving coil RC3 of the third embodiment having the configuration shown in Figs. 12 to 14, measurement results (simulation results) of impedance and the like when the configuration of the power receiving coil is changed will be described as a third example using Table 1 above. In addition, in a power transmission system using the power receiving coil RC3, experimental results (simulation results) for optimizing the capacity of the current adjustment capacitor Cp will also be described as a third example using Figs. 15 and 16. In Fig. 15, the horizontal axis indicates the capacity of the current adjustment capacitor Cp, and the vertical axis indicates the transmission efficiency of the power receiving coil RC3. In Fig. 16, the horizontal axis indicates the capacity of the current adjustment capacitor Cp, and the vertical axis indicates the loss (copper loss) in each of the current adjustment coil RL33 (current adjustment coil RL34) and the power receiving loop coil RL31 (power receiving loop coil RL32).

[0119] Here, the third conventional example, which is compared with the third embodiment, has the same configuration as the power receiving coil RC2 (power transmitting coil TC2) of the second embodiment, except for the current adjustment coil RL33 and the current adjustment coil RL34, as illustrated in Table 1. As a result, in the power receiving coil of the third conventional example, the total number of turns (16 turns) of the current adjustment coil RL33 and the current adjustment coil RL34 connected in series is not an integer multiple of the number of turns (10 turns) of the power transmitting loop coil and the power receiving loop coil, etc., connected in parallel, and therefore the positions of the copper thin film wires constituting the power receiving loop coil, etc., and the current adjustment coil do not overlap when viewed from the center.

[0120] Other specifications of the receiving coil RC3 of the third embodiment and the receiving coil of the third conventional example used in the experiment of the third example are as follows:

[0121] Dimensions of receiving coil RC3 and the third conventional example: long side 266 mm x short side 160 mm Pitch PT3 (see Figure 12(b) and Figure 14): 5.0 mm (outermost part) to 8.0 mm (innermost part) Copper thin film wire thickness in RL311 etc.: 0.2mm Distance between transmitter and receiver coils: 40mm Ferrite sheets of the same thickness as the transmitting coil and the receiving coil are provided on the opposing surfaces of the transmitting coil and the receiving coil.

[0122] As shown by hatching in Table 1, at the frequency (85 kHz) used for power transmission by the power transmission system of the third embodiment, the use of the receiving coil RC3 of the third embodiment provides better performance in terms of impedance and Q value than the use of the transmitting coil and receiving coil of the third conventional example. In other words, it can be said that a configuration like the receiving coil RC3 (in which the copper thin film wires that make up each coil overlap) is more preferable in terms of reducing impedance and inductance and improving the Q value.

[0123] 15 and 16, at the above frequencies used for power transmission by the power transmission system of the third embodiment, when the capacitance of the current adjustment capacitor Cp is 20 microfarads 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 the capacitance of the current adjustment capacitor Cp at the above frequencies is desirably 20 microfarads or less.

[0124] As described above, 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, the current adjustment coil RL33 and the current adjustment coil RL34 are further provided, and the overall shape in a plan view is the same polygon (rectangle) as the overall shape in a plan view of the power receiving loop coil RL31 and the power receiving loop coil RL32, and the position of at least the straight portion constituting the copper thin film wire TL311, etc. as seen from the center of the power receiving coil RC3 coincides with the position of at least the straight portion constituting the corresponding copper thin film wire TL331, etc. as seen from the center in a plan view. Therefore, even when the current adjustment coil RL33 and the current adjustment coil RL34 are provided, it is possible to reduce impedance, and it is possible to achieve both weight reduction and cost reduction, improvement of transmission efficiency, and prevention of an increase in operating temperature.

[0125] In addition, since the current adjustment coil RL33 and the current adjustment coil RL34 are stacked in 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, while achieving both weight reduction and cost reduction, improved transmission efficiency, and prevention of an increase in operating temperature.

[0126] Furthermore, the current adjustment coil RL33 and the current adjustment coil RL34 are connected in series at their outermost ends, and a current adjustment capacitor Cp is connected to their innermost ends, with its capacity optimized for the power transmission frequency (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, improved 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 Fig. 17 and Fig. 18. Fig. 17 and Fig. 18 are plan views each showing the structure of a coil according to the fourth embodiment.

[0128] In the power transmission coil TC1 etc. (power receiving 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 copper thin film wire TL111 and the copper thin film wire TL112 constituting the power transmission loop coil TL11 are wound so that the position of the straight portion of the winding of the power transmission loop coil TL11 shifts toward the outer periphery or the inner periphery by one pitch (i.e., so that the winding transitions toward the outer periphery or the inner periphery) (see, for example, FIG. 4 or FIG. 10(b)). In contrast, in a power transmission coil (and a power receiving coil) of a fourth embodiment described below, the power transmission loop coil (and the power receiving loop coil) is stacked on top of each other to form the power transmission coil (and the power receiving coil), and only one of the four straight sections included in one turn of the power transmission loop coil (and the power receiving loop coil) is wound with the copper thin film wire that constitutes the power transmission loop coil (and the power receiving loop coil) such that the position of the straight section shifts to the outer or inner side by one pitch in the winding of the power transmission loop coil (and the power receiving loop coil) (i.e., the winding transitions to the outer or inner side).As a result, the power transmission coil (and the power receiving coil) of the fourth embodiment is configured so that the portion where the positions of the turns of the stacked power transmission loop coils (and the power receiving loop coils) coincide in a plan view when viewed from the center of the power transmission coil (power receiving coil) becomes wider.

[0129] The configurations of the power transmitting coil of the fourth embodiment and the power receiving coil of the fourth embodiment are basically the same, and the configurations of the power receiving loop coil of the power receiving coil of the fourth embodiment and the power transmitting loop coil of the power transmitting coil of the fourth embodiment are the same. Therefore, in the following description, only the configuration of the power transmitting coil of the fourth embodiment will be described. In this case, the same component parts as the power transmitting coil TC1 of the first embodiment are denoted by the same component numbers and detailed description will be omitted.

[0130] That is, as shown in the plan view of Fig. 17(a), the power transmitting coil TC4 of the fourth embodiment is configured by stacking a power transmitting loop coil TL41 made of a copper thin-film wire TL411 and a power transmitting loop coil TL42, the plan view of which is shown in Fig. 17(b), with an insulating film BF interposed between them, in a direction perpendicular to the paper surface of Fig. 17. The center of winding of the copper thin-film wire TL411 constituting the power transmitting loop coil TL41 and the center of winding of the copper thin-film wire TL421 (see Fig. 17(b)) constituting the power transmitting loop coil TL42 are the same or approximately the same as each other.

[0131] As shown in FIG. 17(a), the power transmitting loop coil TL41 is made of a copper thin-film wire TL411 wound in one layer of the power transmitting coil TC4 (on the surface of the film BF illustrated in FIG. 17(a)), and has an external connection terminal O1 on one side of its outermost circumference for connecting the copper thin-film wire TL411 to a power transmitting unit (not shown). The power transmitting loop coil TL41 is made of the copper thin-film wire TL411 wound six times (6 turns) clockwise from its outermost circumference in FIG. 17(a), and the outer peripheral end of the copper thin-film wire TL411 (the center of the upper side in the case illustrated in FIG. 17(a)) is connected to the external connection terminal O1. The inner peripheral end of the copper thin-film wire TL411 (the central end of the power transmitting coil TC4 in the case illustrated in FIG. 17(a)) is connected to the copper thin-film wire constituting the power transmitting loop coil TL42 formed on the back surface of the film BF by a via V11 penetrating the film BF. The copper thin-film wire TL411 has the same width and thickness all around the power transmission loop coil TL41. Furthermore, the copper thin-film wire TL411 has straight sections on its upper, lower, left and right sides in FIG. 17(a), and the straight sections are connected by curved sections that are substantially concentric arcs.

[0132] Next, the configuration of the power transmitting loop coil TL42 laminated directly below the power transmitting 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 transmitting loop coil TL42.

[0133] 17(b), the power transmitting loop coil TL42 laminated on the power transmitting loop coil TL41 with a film BF sandwiched therebetween is made of, for example, a thin copper wire TL421. As described above, the center of winding of the thin copper wire TL421 constituting the power transmitting loop coil TL42 and the center of winding of the thin copper wire TL411 constituting the power transmitting loop coil TL41 are the same or approximately the same as each other. Furthermore, the overall shape of the power transmitting loop coil TL42 is approximately rectangular, the same as the overall shape of the power transmitting loop coil TL41.

[0134] As shown in FIG. 17(b), the power transmitting loop coil TL42 is formed of the copper thin-film wire TL421 wound in another layer of the power transmitting coil TC4 (the back surface of the film BF illustrated in FIG. 17(a)), and has an external connection terminal O2 on one side of its outermost circumference for connecting the copper thin-film wire TL421 to the power transmitting unit (not shown). The power transmitting loop coil TL42 is formed by winding the copper thin-film wire TL421 six times (6 turns) clockwise from its innermost circumference in FIG. 17(b), and the outer circumferential 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 circumferential end of the copper thin-film wire TL421 (the end on the center side of the power transmitting coil TC4 in the case shown in FIG. 17(b)) is connected to the copper thin-film wire TL411 of the power transmitting loop coil TL41 by the via V11. The copper thin-film wire TL421 has the same width and thickness all around the power transmission loop coil TL42. Furthermore, the copper thin-film wire TL421 has straight sections on its upper, lower, left and right sides in FIG. 17(b), and the straight sections are connected by curved sections that are substantially concentric arcs.

[0135] Next, the positional relationship between the power transmitting loop coil TL41 made of the copper thin-film wire TL411 and the power transmitting loop coil TL42 made of the copper thin-film wire TL421 will be described with reference to Fig. 18. Fig. 18 is a plan view showing an overlapping state of the power transmitting loop coil TL41 and the power transmitting loop coil TL42, in which the power transmitting loop coil TL41 (copper thin-film wire TL411) is indicated by a solid line, and the power transmitting loop coil TL42 (copper thin-film wire TL421) laminated directly below it with a film BF (not shown in Fig. 18) interposed therebetween is indicated by a dashed line.

[0136] As shown by the solid line in Fig. 18, the power transmitting loop coil TL41 is made of a copper thin-film wire TL411 wound from the outer periphery to the inner periphery and is connected at its innermost periphery to the copper thin-film wire TL421 constituting the power transmitting loop coil TL42 by a via V11. In only one of the four straight lines included in one turn (for example, the upper side in Fig. 18), the copper thin-film wire TL411 is wound clockwise such that the position of the straight line shifts to the inner periphery by one pitch PT4 (see Figs. 17(a) and 18) in the winding of the copper thin-film wire TL411 (i.e., the winding transitions to the inner periphery). As a result, the straight line portions in the power transmitting loop coil TL41 where the winding transitions to the inner periphery by one pitch PT4 are, for example, six straight line portions LA41 lined up from the outer periphery to the inner periphery at the upper side in Figs. 17(a) and 18.

[0137] In contrast, in the power transmitting loop coil TL42, in which the copper thin-film wire TL411 constituting the power transmitting loop coil TL41 and the copper thin-film wire TL421 connected at their innermost periphery by the via V11 are wound from the inner periphery to the outer periphery, as shown by the dashed lines in Fig. 18, the copper thin-film wire TL421 is wound clockwise (i.e., in the same direction as the power transmitting loop coil TL41) so that the position of the straight section shifts to the outer periphery (i.e., the winding transitions to the outer periphery) by one pitch PT4 (see Figs. 17(b) and 18) in the winding of the copper thin-film wire TL421 only in one straight section (e.g., the upper side in Fig. 18) out of the four straight sections included in one turn. As a result, the straight sections in the power transmitting loop coil TL42 whose winding transitions to the outer periphery by one pitch PT4 are, for example, six straight sections LA42 lined up from the inner periphery to the outer periphery at the upper side in Figs. 17(b) and 18. The outermost portion of the upper side of the power transmission loop coil TL41 in Figure 18 is connected to an external connection terminal O1 having a shape that protrudes outward, and the outermost portion of the right side of the power transmission loop coil TL42 in Figure 18 is connected to an external connection terminal O2 having a shape that protrudes outward.

[0138] 18, the power transmitting loop coil TL41 and the power transmitting loop coil TL42 each having the above-mentioned shapes are laminated, so that the position of the thin-film copper wire TL411 and the position of the thin-film copper wire TL421 when viewed from the center of the power transmitting coil TC4 are the same except for the straight line portions where the windings transition and the connection portions to the external connection terminals O1 and O2. Thus, in the power transmitting coil TC4, the power transmitting loop coil TL41 and the power transmitting loop coil TL42 are laminated with the film BF sandwiched between them, with the straight line portions (excluding the winding transition portions) and curved lines of the power transmitting loop coil TL41 all overlapping with the straight line portions (excluding the winding transition portions) and curved lines of the power transmitting loop coil TL42. As a result, the power transmitting loop coil TL42 is connected to the innermost portion so as to have the same winding direction as the clockwise winding from the outermost portion (external connection terminal O1) to the innermost portion of the power transmitting loop coil TL41, and the power transmitting loop coil TL42 is wound from the innermost portion to the outermost portion while maintaining the winding direction. With this structure, in the power transmitting coil TC4 of the fourth embodiment, a current flows in the clockwise direction from the outermost portion to the innermost portion in the power transmitting loop coil TL41, and the current flows in the same clockwise direction from the innermost portion to the outermost portion in the power transmitting loop coil TL42.

[0139] The manufacturing method of the power transmitting coil TC4 (and the power receiving coil) of the fourth embodiment is basically the same as the manufacturing method of the power transmitting coil TC1 and the power receiving coil RC1 of the first embodiment, so a detailed description will be omitted.

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

[0141] Before describing the fourth embodiment, the configuration of a power transmitting coil or a power receiving coil of a fourth comparative example to which the fourth embodiment is compared will be outlined with reference to Figs. 19 and 20. The power transmitting coil and the power receiving coil of the fourth comparative example are basically configured the same. Therefore, in the following description, the structure of the power transmitting coil of the fourth comparative example will be described. Figs. 19 and 20 are plan views showing the structure of the power transmitting coil of the fourth comparative example when viewed from the same viewpoint as the power transmitting coil TC4 of the fourth embodiment. In Figs. 19 and 20, the same members as those of the power transmitting coil TC4 of the fourth embodiment are denoted by the same member numbers, and detailed descriptions thereof will be omitted.

[0142] As shown in a plan view in Fig. 19(a), the power transmitting coil TC4X of the fourth comparative example is configured by stacking a power transmitting loop coil TL4X made of a thin-film copper wire TL4X1 and a power transmitting loop coil TL4Y (not shown in Fig. 19(a)) in a direction perpendicular to the plane of the paper in Fig. 19 via an insulating film BF similar to that of the power transmitting coil TC4 of the fourth embodiment. In this case, the center of winding of the thin-film copper wire TL4X1 constituting the power transmitting loop coil TL4X and the center of winding of a thin-film copper wire (described below) constituting the power transmitting loop coil TL4Y are made to be the same or approximately the same as each other.

[0143] As shown in FIG. 19(a), the power transmitting loop coil TL4X is made of a copper thin-film wire TL4X1 wound in one layer of the power transmitting coil TC4X (on the surface of the film BF illustrated in FIG. 19(a)), and has an external connection terminal O1 on one side of the outermost circumference for connecting the copper thin-film wire TL4X1 to a power transmitting unit (not shown). The power transmitting loop coil TL4X is made of a copper thin-film wire TL4X1 wound six times (6 turns) clockwise from the outermost circumference in FIG. 19(a), and the outer peripheral end of the copper thin-film wire TL4X1 (the center of the upper side in the case shown in FIG. 19(a)) is connected to the external connection terminal O1. The inner peripheral end of the copper thin-film wire TL4X1 (the central end of the power transmitting coil TC4X in the case shown in FIG. 19(a)) is connected to the copper thin-film wire constituting the power transmitting loop coil TL4Y formed on the back surface of the film BF by a via V11 penetrating the film BF. The copper thin-film wire TL4X1 has the same width and thickness around the entire circumference of the power transmission loop coil TL4X. Furthermore, the copper thin-film wire TL4X1 has straight sections on its upper, lower, left and right sides in FIG. 19(a), and the straight sections are connected by curved sections that are substantially concentric arcs.

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

[0145] 19(b), the power transmitting loop coil TL4Y, which is laminated on the power transmitting loop coil TL4X with a film BF sandwiched therebetween, is made of a thin copper wire TL4Y1. At this time, the center of winding of the thin copper wire TL4Y1 constituting the power transmitting loop coil TL4Y and the center of winding of the thin copper wire TL4X1 constituting the power transmitting loop coil TL4X are the same or approximately the same as each other. Furthermore, the overall shape of the power transmitting loop coil TL4Y is approximately rectangular, the same as the overall shape of the power transmitting loop coil TL4X.

[0146] As shown in FIG. 19(b), the power transmitting loop coil TL4Y is formed of the copper thin-film wire TL4Y1 wound in another layer of the power transmitting coil TC4X (the back surface of the film BF illustrated in FIG. 19(a)), and has an external connection terminal O2 on one side of its outermost circumference for connecting the copper thin-film wire TL4Y1 to a power transmitting unit (not shown). The power transmitting loop coil TL4Y is formed by winding the copper thin-film wire TL4Y1 six times (6 turns) clockwise from its innermost circumference in FIG. 19(b), and the outer circumferential 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 circumferential end of the copper thin-film wire TL4Y1 (the end on the center side of the power transmitting coil TC4X in the case shown in FIG. 19(b)) is connected to the copper thin-film wire TL4X1 of the power transmitting loop coil TL4X by the via V11. The copper thin-film wire TL4Y1 has the same width and thickness all around the power transmission loop coil TL4Y. Furthermore, the copper thin-film wire TL4Y1 has straight sections on its upper, lower, left and right sides in FIG. 19(b), and the straight sections are connected by curved sections that are substantially concentric arcs.

[0147] Next, the positional relationship between the power transmitting loop coil TL4X made of the copper thin-film wire TL4X1 and the power transmitting loop coil TL4Y made of the copper thin-film wire TL4Y1 will be described with reference to Fig. 20. Fig. 20 is a plan view showing the overlapping state of the power transmitting loop coil TL4X and the power transmitting loop coil TL4Y, in which the power transmitting loop coil TL4X is indicated by a solid line and the power transmitting loop coil TL4Y laminated directly below it with a film BF (not shown in Fig. 20) interposed therebetween is indicated by a dashed line.

[0148] As shown by the solid line in Fig. 20, the power transmission loop coil TL4X is made of a copper thin-film wire TL4X1 wound from the outer periphery to the inner periphery and is connected at its innermost periphery to the copper thin-film wire TL4Y1 constituting the power transmission loop coil TL4Y by a via V11, and in only one of the four curved portions included in one turn (for example, the curved portion in the upper left corner in Fig. 20), the copper thin-film wire TL4X1 is wound clockwise so that the position of the straight portion in the winding of the copper thin-film wire TL4X1 shifts to the inner periphery by one pitch PT4 (i.e., the winding transitions to the inner periphery). As a result, the curved portions in the power transmission loop coil TL4X where the winding transitions to the inner periphery by one pitch PT4 are, for example, the six curved portions CV4X lined up from the outer periphery to the inner periphery in the upper left corner in Figs. 19(a) and 20.

[0149] In contrast, in the power transmission loop coil TL4Y in which the copper thin-film wire TL4X1 constituting the power transmission loop coil TL4X and the copper thin-film wire TL4Y1 connected at their innermost periphery by a via V11 are wound from the inner periphery to the outer periphery, the copper thin-film wire TL4Y1 is wound clockwise in only one of the four curved portions included in one turn (for example, the curved portion in the upper left corner in FIG. 20) such that the position of the straight portion in the winding of the copper thin-film wire TL4Y1 shifts to the outer periphery by one pitch PT4 (i.e., the winding transitions to the outer periphery), as shown by the dashed line in FIG. 20. As a result, the curved portions in the power transmission loop coil TL4Y where the winding transitions to the outer periphery by one pitch PT4 are, for example, six curved portions CV4Y lined up from the inner periphery to the outer periphery in the upper left corner in FIG. 19(b) and FIG. 20. The outermost portion of the upper edge of the power transmission loop coil TL4X in Figure 20 is connected to an external connection terminal O1 having a shape that protrudes outward, and the outermost portion of the upper edge of the power transmission loop coil TL4Y in Figure 20 is connected to an external connection terminal O2 having a shape that protrudes outward.

[0150] The power transmitting loop coil TL4X and the power transmitting loop coil TL4Y having the shapes described above are laminated as shown in Fig. 20, so that the position of the copper thin film wire TL4X1 and the position of the copper thin film wire TL4Y1 when viewed from the center of the power transmitting coil TC4X are different at two curved portions and at the connection portions to the external connection terminal O1 and the external connection terminal O2 as shown in Fig. 20. Therefore, the power transmitting coil TC4X is laminated with the power transmitting loop coil TL4X and the power transmitting loop coil TL4Y sandwiched between them by the film BF in a state in which the portion where the power transmitting loop coil TL4X and the power transmitting loop coil TL4Y do not overlap is greater than that of the power transmitting coil TC4 of the fourth embodiment. As a result, the power transmitting loop coil TL4Y is connected at the innermost portion so as to have the same winding direction as the clockwise winding from the outermost portion (external connection terminal O1) to the innermost portion of the power transmitting loop coil TL4X, and the power transmitting loop coil TL4Y is wound from the innermost portion to the outermost portion while maintaining the winding direction. With this structure, in the power transmission coil TC4X of the fourth comparative example, a current flows in a clockwise direction from the outermost portion to the innermost portion in the power transmission loop coil TL4X, and the same current flows in the same clockwise direction from the innermost portion to the outermost portion in the power transmission loop coil TL4Y.

[0151] Other specifications of the power transmitting coil TC4 of the fourth embodiment and the power transmitting coil TC4X of the fourth comparative example used in the experiment of the fourth example are as follows: In the following explanation, the specifications of the power transmitting coil TC4 and the power transmitting coil TC4X are explained, but the specifications of the power receiving coil of the fourth embodiment used in the experiment are the same as the specifications of the power transmitting coil TC4, and the specifications of the power receiving coil of the fourth comparative example are the same as the specifications of the power transmitting coil TC4X.

[0152] Size of the power transmitting coil TC4 (and the power receiving coil of the fourth embodiment) and the power transmitting coil TC4X (and the power receiving coil of the fourth conventional example): 160 mm × 260 mm Pitch PT4: 8mm Copper thin film wire TL411 etc. Copper thin film wire thickness: 0.2mm

[0153] As shown in FIG. 21, near the frequency (85 kHz) used for power transmission by the power transmission system, the use of the transmitting coil TC4 and the receiving coil of the fourth embodiment results in lower impedance than the use of the transmitting coil TC4X and the receiving coil of the fourth comparison example, and therefore good Q-factor characteristics are obtained.

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

[0155] (E) Fifth embodiment Next, a fifth embodiment of the present invention will be described with reference to Fig. 22 and Fig. 23. Fig. 22 and Fig. 23 are plan views each showing the structure of a coil according to the fifth embodiment.

[0156] In the power transmission coil TC1, etc. (power receiving coil RC1, etc.) of the first to fourth embodiments described above, the copper thin film wire TL111 and the copper thin film wire TL112 constituting the power transmission loop coil TL11 and the copper thin film wire TL121 and the copper thin film wire TL122 constituting the power transmission loop coil TL12 are wound so that, for example, the position where the winding in the power transmission loop coil TL11 transitions by one pitch and the position where the winding in the power transmission loop coil TL12 transitions by one pitch are different when viewed from the center of the power transmission coil TC1 (see, for example, Figure 4 or Figure 10(b)). In contrast to these, in a power transmission coil (and a power receiving coil) of a fifth embodiment described below, the copper thin-film wire constituting the power transmission loop coil (and the power receiving loop coil) is wound such that the position of the straight portion shifts to the outer or inner circumference by one pitch in the winding of the power transmission loop coil (and the power receiving loop coil) (i.e., the winding transitions to the outer or inner circumference) only in one of four curved portions included in one winding of the power transmission loop coil (and the power receiving loop coil) that are stacked on top of each other to constitute the power transmission coil (and the power receiving coil). In addition, in the power transmission coil (and the power receiving coil) of the fifth embodiment, the copper thin-film wire constituting the power transmission loop coil (and the power receiving coil) is wound such that the position of one curved portion where the winding transition occurs is the same position when viewed from the center of the power transmission coil (and the power receiving coil). As a result, in the fifth embodiment of the power transmission coil (and power receiving coil), the positions of the four straight lines and three curved lines in each turn of the stacked power transmission loop coils (and power receiving loop coils) coincide when viewed from the center of the power transmission coil (power receiving coil) in a planar view.

[0157] The configurations of the power transmitting coil of the fifth embodiment and the power receiving coil of the fifth embodiment are basically the same, and the configurations of the power receiving loop coil of the power receiving coil of the fifth embodiment and the power transmitting loop coil of the power transmitting coil of the fifth embodiment are the same. Therefore, in the following description, only the configuration of the power transmitting coil of the fifth embodiment will be described. In this case, the same component parts as the power transmitting coil TC1 of the first embodiment are denoted by the same component numbers and detailed description will be omitted.

[0158] That is, as shown in the plan view of Fig. 22(a), the power transmitting coil TC5 of the fifth embodiment is configured by stacking a power transmitting loop coil TL51 made of a thin copper wire TL511 and a power transmitting loop coil TL52, the plan view of which is shown in Fig. 22(b), with an insulating film BF interposed between them in a direction perpendicular to the paper surface of Fig. 22. The center of winding of the thin copper wire TL511 constituting the power transmitting loop coil TL51 and the center of winding of the thin copper wire TL521 (see Fig. 22(b)) constituting the power transmitting loop coil TL52 are the same or approximately the same as each other.

[0159] As shown in FIG. 22(a), the power transmitting loop coil TL51 is made of a copper thin-film wire TL511 wound in one layer of the power transmitting coil TC5 (on the surface of the film BF illustrated in FIG. 22(a)), and has an external connection terminal O1 on one side of the outermost circumference for connecting the copper thin-film wire TL511 to a power transmitting unit (not shown). The power transmitting loop coil TL51 is made of the copper thin-film wire TL511 wound counterclockwise five times (5 turns) from the outermost circumference 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. The inner peripheral end of the copper thin-film wire TL511 (the central end of the power transmitting coil TC5 in the case shown in FIG. 22(a)) is connected to the copper thin-film wire constituting the power transmitting loop coil TL52 formed on the back surface of the film BF by a via V11 penetrating the film BF. The copper thin-film wire TL511 has the same width and thickness all around the power transmission loop coil TL51. Furthermore, the copper thin-film wire TL511 has straight sections on its upper, lower, left and right sides in FIG. 22(a), and the straight sections are connected by curved sections that are substantially concentric arcs.

[0160] Next, the configuration of the power transmitting loop coil TL52 laminated directly below the power transmitting 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 transmitting loop coil TL52.

[0161] 22(b), the power transmitting loop coil TL52 laminated on the power transmitting loop coil TL51 with a film BF sandwiched therebetween is made of, for example, a thin copper wire TL521. As described above, the center of winding of the thin copper wire TL521 constituting the power transmitting loop coil TL52 and the center of winding of the thin copper wire TL511 constituting the power transmitting loop coil TL51 are the same or approximately the same as each other. Furthermore, the overall shape of the power transmitting loop coil TL52 is approximately square, the same as the overall shape of the power transmitting loop coil TL41.

[0162] As shown in FIG. 22(b), the power transmitting loop coil TL52 is formed of the copper thin-film wire TL521 wound in another layer of the power transmitting coil TC5 (the back surface of the film BF illustrated in FIG. 22(a)), and has an external connection terminal O2 on one side of its outermost periphery for connecting the copper thin-film wire TL521 to the power transmitting unit (not shown). The power transmitting loop coil TL52 is formed by winding the copper thin-film wire TL521 five times (5 turns) counterclockwise from its innermost periphery in FIG. 22(b), and the outer periphery end of the copper thin-film wire TL521 (the upper right end in the case of FIG. 22(b)) is connected to the external connection terminal O2. On the other hand, the inner periphery end of the copper thin-film wire TL521 (the end on the center side of the power transmitting coil TC5 in the case of FIG. 22(b)) is connected to the copper thin-film wire TL511 of the power transmitting loop coil TL51 by the via V11. The copper thin-film wire TL521 has the same width and thickness all around the power transmission loop coil TL52. Furthermore, the copper thin-film wire TL521 has straight portions on its upper, lower, left and right sides in FIG. 22(b), and the straight portions are connected by curved portions having substantially concentric arc shapes.

[0163] Next, the positional relationship between the power transmitting loop coil TL51 made of the copper thin-film wire TL511 and the power transmitting loop coil TL52 made of the copper thin-film wire TL521 will be described with reference to Fig. 23. Fig. 23 is a plan view showing an overlapping state between the power transmitting loop coil TL51 and the power transmitting loop coil TL52, in which the power transmitting loop coil TL51 (copper thin-film wire TL511) is indicated by a solid line, and the power transmitting loop coil TL52 (copper thin-film wire TL521) laminated directly below it with a film BF (not shown in Fig. 23) interposed therebetween is indicated by a dashed line.

[0164] As shown by the solid line in Fig. 23, the power transmission loop coil TL51 is made of a copper thin-film wire TL511 wound from the outer periphery to the inner periphery and is connected at its innermost periphery to the copper thin-film wire TL521 constituting the power transmission loop coil TL52 by a via V11. In only one curved portion (for example, the upper right portion in Fig. 23) among the four curved portions included in one turn, the copper thin-film wire TL511 is wound counterclockwise so that the position of the straight portion shifts to the inner periphery by one pitch PT5 (see Figs. 22(a) and 23) in the winding of the copper thin-film wire TL511 (i.e., the winding transitions to the inner periphery). As a result, the straight portion in the power transmission loop coil TL51 where the winding transitions to the inner periphery by one pitch PT5 is, for example, five curved portions CV51 lined up from the outer periphery to the inner periphery in the upper right portion in Figs. 22(a) and 23.

[0165] In contrast, in the power transmitting loop coil TL52, in which the copper thin-film wire TL511 constituting the power transmitting loop coil TL51 and the copper thin-film wire TL521 connected at their innermost periphery by the via V11 are wound from the inner periphery to the outer periphery, as shown by the dashed line in Fig. 23, in only one curved portion (for example, the upper right portion in Fig. 18) among the four curved portions included in one turn, the copper thin-film wire TL521 is wound counterclockwise (i.e., in the same direction as the power transmitting loop coil TL51) so that the position of the straight portion in the winding of the copper thin-film wire TL521 shifts to the outer periphery by one pitch PT5 (see Figs. 22(b) and 23) (i.e., so that the winding transitions to the outer periphery). As a result, the curved portions in the power transmitting loop coil TL52 where the winding transitions to the outer periphery by one pitch PT5 are, for example, five curved portions CV52 lined up from the inner periphery to the outer periphery in the upper right portion in Figs. 22(b) and 23. The right end portion 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 that protrudes outward, and the upper right end portion of the power transmission loop coil TL52 in FIG. 23 is connected to an external connection terminal O2 having a shape that protrudes outward.

[0166] 23, the power transmitting loop coil TL51 and the power transmitting loop coil TL52 each having the above-mentioned shapes are laminated as shown in FIG. 23, so that the position of the copper thin-film wire TL511 and the position of the copper thin-film wire TL521 when viewed from the center of the power transmitting coil TC5 are the same except for one curved portion where the windings transition and the connection portions to the external connection terminals O1 and O2. Thus, in the power transmitting coil TC5, the power transmitting loop coil TL51 and the power transmitting loop coil TL52 are laminated with the film BF sandwiched between them, with all of the straight lines and curved portions (excluding the winding transition portions) of the power transmitting loop coil TL51 overlapping with all of the straight lines and curved portions (excluding the winding transition portions) of the power transmitting loop coil TL52. As a result, the power transmitting loop coil TL52 is connected to the innermost portion of the power transmitting loop coil TL51 so that the winding direction is the same as the counterclockwise winding from the outermost portion (external connection terminal O1) to the innermost portion of the power transmitting loop coil TL51, and the power transmitting loop coil TL52 is wound from the innermost portion to the outermost portion while maintaining the winding direction. With this structure, in the power transmitting coil TC5 of the fifth embodiment, a current flows in the counterclockwise direction from the outermost portion to the innermost portion in the power transmitting loop coil TL51, and the current flows in the same clockwise direction from the innermost portion to the outermost portion in the power transmitting loop coil TL52.

[0167] The manufacturing method of the power transmitting coil TC5 (and the power receiving coil) of the fifth embodiment is basically the same as the manufacturing method of the power transmitting coil TC1 and the power receiving coil RC1 of the first embodiment, so a detailed description will be omitted.

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

[0169] Before describing the fifth embodiment, the configuration of the power transmitting coil or the power receiving coil of the fifth comparative example, which is a comparison target, will be outlined with reference to Figs. 24 and 25. The power transmitting coil and the power receiving coil of the fifth comparative example have basically the same configuration. Therefore, in the following description, the structure of the power transmitting coil of the fifth comparative example will be described. Also, Figs. 24 and 25 are plan views showing the structure of the power transmitting coil of the fifth comparative example when viewed from the same viewpoint as the power transmitting coil TC5 of the fifth embodiment. In Figs. 24 and 25, the same members as those of the power transmitting coil TC5 of the fifth embodiment are given the same member numbers, and detailed descriptions are omitted.

[0170] As shown in a plan view in Fig. 24(a), the power transmitting coil TC5X of the fifth comparative example is configured by stacking a power transmitting loop coil TL5X made of a thin copper wire TL5X1 and a power transmitting loop coil TL5Y (not shown in Fig. 24(a)) in a direction perpendicular to the paper surface of Fig. 24 via an insulating film BF similar to that of the power transmitting coil TC5 of the fifth embodiment. In this case, the center of winding of the thin copper wire TL5X1 constituting the power transmitting loop coil TL5X and the center of winding of a copper thin film wire (described below) constituting the power transmitting loop coil TL5Y are made to be the same or approximately the same as each other.

[0171] As shown in FIG. 24(a), the power transmitting loop coil TL5X is made of a copper thin-film wire TL5X1 wound in one layer of the power transmitting coil TC5X (on the surface of the film BF illustrated in FIG. 24(a)), and has an external connection terminal O1 on one side of the outermost periphery for connecting the copper thin-film wire TL5X1 to a power transmitting unit (not shown). The power transmitting loop coil TL5X is made of a copper thin-film wire TL5X1 wound counterclockwise five times (5 turns) from the outermost periphery in FIG. 24(a), and the outer periphery end of the copper thin-film wire TL5X1 (the center of the upper side in the case shown in FIG. 24(a)) is connected to the external connection terminal O1. The inner periphery end of the copper thin-film wire TL5X1 (the center end of the power transmitting coil TC5X in the case shown in FIG. 24(a)) is connected to the copper thin-film wire constituting the power transmitting loop coil TL5Y formed on the back surface of the film BF by a via V11 penetrating the film BF. The copper thin-film wire TL5X1 has the same width and thickness all around the power transmission loop coil TL5X. Furthermore, the copper thin-film wire TL5X1 has straight sections on its upper, lower, left and right sides in FIG. 24(a), and the straight sections are connected by curved sections that are substantially concentric arcs.

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

[0173] 24(b), the power transmitting loop coil TL5Y, which is laminated on the power transmitting loop coil TL5X with a film BF sandwiched therebetween, is made of a thin copper wire TL5Y1. At this time, the center of winding of the thin copper wire TL5Y1 constituting the power transmitting loop coil TL5Y and the center of winding of the thin copper wire TL5X1 constituting the power transmitting loop coil TL5X are the same or approximately the same as each other. Furthermore, the overall shape of the power transmitting loop coil TL5Y is approximately square, the same as the overall shape of the power transmitting loop coil TL5X.

[0174] As shown in FIG. 24(b), the power transmitting loop coil TL5Y is formed of the copper thin-film wire TL5Y1 wound in another layer of the power transmitting coil TC5X (the back side of the film BF illustrated in FIG. 24(a)), and has an external connection terminal O2 on one side of its outermost circumference for connecting the copper thin-film wire TL5Y1 to a power transmitting unit (not shown). The power transmitting loop coil TL5Y is formed by winding the copper thin-film wire TL5Y1 five times (5 turns) clockwise from its innermost circumference in FIG. 24(b), and the outer circumferential 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 circumferential end of the copper thin-film wire TL5Y1 (the end on the center side of the power transmitting coil TC5X in the case shown in FIG. 24(b)) is connected to the copper thin-film wire TL5X1 of the power transmitting loop coil TL5X by the via V11. The copper thin-film wire TL5Y1 has the same width and thickness all around the power transmission loop coil TL5Y. Furthermore, the copper thin-film wire TL5Y1 has straight sections on its upper, lower, left and right sides in FIG. 24(b), and the straight sections are connected by curved sections that are substantially concentric arcs.

[0175] Next, the positional relationship between the power transmitting loop coil TL5X made of the copper thin-film wire TL5X1 and the power transmitting loop coil TL5Y made of the copper thin-film wire TL5Y1 will be described with reference to Fig. 25. Fig. 25 is a plan view showing the overlapping state of the power transmitting loop coil TL5X and the power transmitting loop coil TL5Y, in which the power transmitting loop coil TL5X is indicated by a solid line and the power transmitting loop coil TL5Y laminated directly below it with a film BF (not shown in Fig. 25) interposed therebetween is indicated by a dashed line.

[0176] As shown by the solid line in Fig. 25, the power transmission loop coil TL5X is made of a copper thin-film wire TL5X1 wound from the outer periphery to the inner periphery and is connected at its innermost periphery to the copper thin-film wire TL5Y1 constituting the power transmission loop coil TL5Y by a via V11. In only one of the four curved portions included in one turn (for example, the curved portion in the upper right corner in Fig. 25), the copper thin-film wire TL5X1 is wound counterclockwise so that the position of the straight portion in the winding of the copper thin-film wire TL5X1 shifts to the inner periphery by one pitch PT5 (i.e., the winding transitions to the inner periphery). As a result, the curved portion in the power transmission loop coil TL5X where the winding transitions to the inner periphery by one pitch PT5 is, for example, the five curved portions CV5X lined up from the outer periphery to the inner periphery in the upper left corner in Figs. 24(a) and 25.

[0177] In contrast, in the power transmission loop coil TL5Y in which the copper thin-film wire TL5X1 constituting the power transmission loop coil TL5X and the copper thin-film wire TL5Y1 connected at their innermost periphery by a via V11 are wound from the inner periphery to the outer periphery, the copper thin-film wire TL5Y1 is wound clockwise such that the position of the straight line portion in the winding of the copper thin-film wire TL5Y1 shifts to the outer periphery by one pitch PT5 (i.e., the winding transitions to the outer periphery) only in one curved portion (for example, the curved portion in the upper left corner of FIG. 25) out of the four curved portions included in one turn, as shown by the dashed lines in FIG. 25. As a result, the curved portions in the power transmission loop coil TL5Y where the winding transitions to the outer periphery by one pitch PT5 are, for example, the five curved portions CV5Y lined up from the inner periphery to the outer periphery in the upper left corner of FIG. 24(b) and FIG. 24. The outermost portion of the upper edge of the power transmission loop coil TL5X in Figure 25 is connected to an external connection terminal O1 having a shape that protrudes outward, and the outermost portion of the upper edge of the power transmission loop coil TL5Y in Figure 25 is connected to an external connection terminal O2 having a shape that protrudes outward.

[0178] The power transmitting loop coil TL5X and the power transmitting loop coil TL5Y having the above-mentioned shapes are laminated as shown in Fig. 25, so that the position of the copper thin film wire TL5X1 and the position of the copper thin film wire TL5Y1 when viewed from the center of the power transmitting coil TC5X are different at two curved portions and at the connection portions to the external connection terminal O1 and the external connection terminal O2 as shown in Fig. 25. Therefore, the power transmitting coil TC5X is laminated with the power transmitting loop coil TL5X and the power transmitting loop coil TL5Y sandwiching the film BF in a state in which the portion where the power transmitting loop coil TL5X and the power transmitting loop coil TL5Y do not overlap is greater than the power transmitting coil TC5 of the fifth embodiment. As a result, the power transmitting loop coil TL5Y is connected at the innermost portion so as to have the same winding direction as the clockwise winding from the outermost portion (external connection terminal O1) to the innermost portion of the power transmitting loop coil TL5X, and the power transmitting loop coil TL5Y is wound from the innermost portion to the outermost portion while maintaining the winding direction. With this structure, in the power transmission coil TC5X of the fifth comparative example, a current flows in a clockwise direction from the outermost portion to the innermost portion in the power transmission loop coil TL5X, and the same current flows in the same clockwise direction from the innermost portion to the outermost portion in the power transmission loop coil TL5Y.

[0179] Other specifications of the power transmitting coil TC5 of the fifth embodiment and the power transmitting coil TC5X of the fifth comparative example used in the experiment of the fifth example are as follows: In the following explanation, the specifications of the power transmitting coil TC5 and the power transmitting coil TC5X are explained, but the specifications of the power receiving coil of the fifth embodiment used in the experiment are the same as the specifications of the power transmitting coil TC5, and the specifications of the power receiving coil of the fifth comparative example are the same as the specifications of the power transmitting coil TC5X.

[0180] Size of the power transmitting coil TC5 (and the power receiving coil of the fifth embodiment) and the power transmitting coil TC5X (and the power receiving coil of the fifth conventional example): 300 mm × 300 mm Pitch PT5: 18mm Copper thin film wire TL511 etc. Copper thin film wire thickness: 0.2mm

[0181] As shown in FIG. 26, in the vicinity of the frequency (85 kHz) used for power transmission by the power transmission system, the use of the transmitting coil TC5 and the receiving coil of the fifth embodiment results in higher inductance and lower impedance than the use of the transmitting coil TC5X and the receiving coil of the fifth comparison example, and therefore results in better Q-factor characteristics.

[0182] As described above, according to power transmission using a power transmission system including the power transmitting coil TC5 of the fifth embodiment and the power receiving coil of the fifth embodiment, the overall shape of the power transmitting loop coil TL51 and the power transmitting loop coil TL52 in a planar view is substantially the same square shape, and the position of each turn of the power transmitting loop coil TL51 as viewed from the center of the power transmitting coil TC5 coincides with the position of each turn of the power transmitting loop coil TL52 as viewed from the center of the power transmitting coil TC5 in a planar view (see FIG. 23). Therefore, it is possible to reduce impedance due to the so-called skin effect or proximity effect caused by constructing the power transmitting coil TC5 and the power receiving coil of the fifth embodiment from thin copper wire to reduce weight and cost, and it is possible to achieve both weight reduction and cost reduction, improved transmission efficiency, and prevention of an increase in operating temperature. Modified form

[0183] Next, modified forms of the present invention will be described. The configuration of the power transmission system of each of the above-mentioned embodiments may be modified as shown in (A) and (B) below. Even if each of the modifications is added, the present invention can achieve the same effects as the above-mentioned power transmission system.

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

[0185] (B) Second Variation Next, as a second variant embodiment, with regard to the positional relationship between the current adjustment coil RL33 and current adjustment coil RL34 of the third embodiment and the power receiving loop coil RL31 and power receiving loop coil RL32, it is preferable that the power receiving loop coil RL31 and power receiving loop coil RL32 are stacked on the power transmission device T side (i.e., the opposing side) of the current adjustment coil RL33 and current adjustment coil RL34.

[0186] (C) Third Variation Next, as a third modified embodiment, the number of turns of the parallel connection of the power transmitting loop coil TL21 and the power transmitting loop coil TL22 of the second embodiment 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 of the series connection of the current adjustment coil RL33 and the current adjustment coil RL34 of the third embodiment may be an integer multiple of three or more times the number of turns of the parallel connection of the power receiving loop coil RL31 and the power receiving loop coil RL32. In any case, the thin copper wires constituting each coil overlap, and the same effects as those of the respective embodiments can be expected. [Industrial Applicability]

[0187] As described above, the present invention can be used in the field of contactless power transmission, and particularly when applied to the field of power transmission for charging storage batteries installed in electric vehicles, it can produce particularly significant effects. [Explanation of symbols]

[0188] S Power Transmission System T Power transmission equipment TR Power Transmission Unit R Power receiving device RV power receiving unit BF Film O1, O2 external connection terminals M1, M2, M3 connection terminals RC1, RC2, RC3 receiving coil TC1, TCX, TC2, TC4, TC4X, TC5, TC5X Transmitter coil TL111, TL112, TL121, TL122, TLX1, TLX2, TLY1, TLY2, TL211, TL212, TL221, TL222, TL231, TL232, TL411, T L412, TL4X1, TL4Y1, TL511, TL512, TL5X1, TL5Y1, RL311, RL312, RL321, RL322, RL331, RL332, RL341, RL342 copper thin film wire TL11, TL12, TLX, TLY, TL21, TL22, TL41, TL42, TL4X, TL4Y, TL51, TL52, TL5X, TL5Y Power transmission loop coil RL31, RL32 receiving loop coil V11, V12, VV vias CV11, CV12, CV51, CV52, CV4X, CV4Y, CV5X, CV5Y curved section LA41, LA42 Straight section TL23, RL33, RL34 Current Adjustment Coil Cp Capacitor

Claims

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 position of at least a part of each of the first straight portions as viewed from the center of the coil and a position of at least a part of each of the second straight portions corresponding to at least a part of each of the first straight portions as viewed from the center of the coil coincide with each other in a plan view, In the winding of the first winding line, a winding transition for one turn is performed only in one of the first curved portions included in one winding, In the winding of the second winding line, a winding transition for one turn is performed only in one of the second curved portions included in one turn, A coil characterized in that the position of the first curved portion where the winding transition occurs in the first winding line and the position of the second curved portion where the winding transition occurs in the second winding line are within the same region of the coil when viewed from the center.

2. 2. The coil according to claim 1, A coil characterized in that the positions of each curved portion other than the first curved portion or the second curved portion where the winding transition occurs are aligned when viewed from the center of the coil in a planar view.

3. 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 position of at least a part of each of the first straight portions as viewed from the center of the coil and a position of at least a part of each of the second straight portions corresponding to at least a part of each of the first straight portions as viewed from the center of the coil coincide with each other in a plan view, In the winding of the first winding circuit, a winding transition for one turn is performed only in one of the first straight portions included in one winding, In the winding of the second winding circuit, a winding transition for one turn is performed only in one of the second straight portions included in one winding, A coil characterized in that the position of each of the first curved portions as viewed from the center of the coil coincides with the position of each of the second curved portions corresponding to each of the first curved portions as viewed from the center of the coil in a planar view.

4. 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 position of at least a part of each of the first straight portions as viewed from the center of the coil and a position of at least a part of each of the second straight portions corresponding to at least a part of each of the first straight portions as viewed from the center of the coil coincide with each other in a plan view, The innermost periphery of the first winding wire is connected to the innermost periphery of the second winding wire, When transmitting electric power, electric power to be transmitted is supplied to the outermost end portions of the first winding circuit and the second winding circuit, and when receiving electric power, the received electric power is output from each of the outermost end portions; The coil further includes an adjustment winding for adjusting a current flowing through the first winding and the second winding, the adjustment winding being laminated at the same position as the first winding and the second winding, the adjustment winding circuit includes a plurality of adjustment straight sections, each of which has a straight line shape, and a plurality of adjustment curved sections, each of which has a curved shape and connects the adjustment straight sections to each other; The overall shape of the adjustment winding in a plan view is the same polygon as the overall shape of the first winding or the second winding, A coil characterized in that the position of each of the first straight sections as viewed from the center of the coil coincides with the position of each of the adjustment straight sections corresponding to each of the first straight sections as viewed from the center of the coil in a planar view.

5. The coil according to claim 4, A coil, characterized in that a plurality of the adjustment windings are stacked in the same position as the first winding and the second winding.

6. The coil according to claim 5, The outermost ends of the plurality of adjustment windings are connected to each other, a capacitance means for adjusting the current is connected to the innermost periphery of the plurality of adjustment windings; A coil, characterized in that the capacity of said capacitance means is equal to or less than a threshold capacity corresponding to at least the frequency of power transmission by said coil.

7. A coil according to any one of claims 1 to 6, The first winding circuit is composed of two parallel first winding circuits, A coil characterized in that the second winding circuit is composed of two second parallel winding circuits arranged in parallel.

8. The coil according to claim 7, In one turn of the first winding, the width of the first parallel winding on the inner circumference side is wider than the width of the first parallel winding on the outer circumference side, A coil characterized in that, in one turn of the second winding circuit, the width of the second parallel winding circuit on the inner circumference side is wider than the width of the second parallel winding circuit on the outer circumference side.

9. The coil according to any one of claims 1 to 6, A coil, characterized in that the width of each of the first winding line and the second winding line is wider in the turns closer to the center.

10. A power transmission system including a power transmission device and a power receiving device separated from the power transmission device, the power transmission device transmitting power from the power transmission device to the power receiving device in a non-contact manner, 10. The coil according to claim 1 , wherein the coil is a power transmission coil arranged to face the power receiving device; an output means for outputting power to be transmitted to the power transmitting coil; A power transmitting device comprising:

11. A power transmission system including a power transmission device and a power receiving device separated from the power transmission device, the power receiving device transmitting power from the power transmission device to the power receiving device in a non-contact manner, 10. The coil according to claim 1 , wherein the power receiving coil is disposed opposite the power transmitting device; An input means connected to the receiving coil; A power receiving device comprising:

12. The power transmission device according to claim 10, a power receiving device disposed away from the power transmitting device and facing the power transmitting coil, the power receiving device receiving the power transmitted from the power transmitting device; A non-contact power transmission system comprising:

13. A power transmission device; 12. The power receiving device according to claim 11, wherein the power receiving coil is disposed opposite the power transmitting device and away from the power transmitting device, and the power receiving device receives power transmitted from the power transmitting device; A non-contact power transmission system comprising:

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