JP7022979B2 - Transmission coil for non-contact power supply, its manufacturing method, and non-contact power supply device - Google Patents

Description

The present invention relates to a transmission coil for non-contact power feeding that supplies power to a portable electronic device or the like in a non-contact manner, and a method for manufacturing the same. Further, the present invention relates to a non-contact power feeding device using the same.

In recent years, as a power supply device for mobile electronic devices such as mobile communication terminals and digital cameras equipped with secondary batteries, a non-contact power supply device that uses electromagnetic induction between the primary coil for power transmission and the secondary coil for power reception. Has been proposed. In the non-contact power feeding device, a high-frequency alternating current is applied to the power transmission coil, and the high-frequency magnetic field generated from the power transmission coil is received by the power receiving coil to transmit power in a non-contact manner. Such a non-contact power feeding device is required to be small, particularly thin. Therefore, a spiral flat coil is used as a transmission coil for power transmission and reception.

As a technique for forming a thin coil, for example, Patent Document 1 describes that a print pattern of a conductive ink, a thin film formed on a printed circuit board, and a conductive pattern formed by surface treatment are used for the coil.

However, in the thin coil, since the coil conductor is thin, the magnetic flux lines are concentrated at both ends of the coil conductor due to the skin effect and the proximity effect due to the eddy current, and the current is concentrated. In particular, when the coil film thickness is about the same as the skin depth of the coil, the current concentration is remarkable in the region from the side surface of the coil conductor to the skin depth. Therefore, there is a problem that the AC resistance of the coil increases and the power transmission efficiency decreases.

As a measure against an increase in resistance due to such a skin effect and a proximity effect, for example, Patent Document 2 describes the use of a coil made of an insulated electric wire such as a stranded wire (Ritz wire). Further, Patent Document 3 relating to an induction heating coil describes that a magnetic material is inserted and arranged between coil conductors to reduce high frequency loss.

However, the litz wire of Patent Document 2 is an electric wire, and the magnetic material of Patent Document 3 is ferrite, both of which are bulk, so that the demand for miniaturization and thinning cannot be sufficiently met. Further, the ferrite of Patent Document 3 has a drawback that it is vulnerable to impacts such as vibration and dropping because it is a sintered body.

Japanese Unexamined Patent Publication No. 2016-59323 Japanese Unexamined Patent Publication No. 2006-42519 WO2011 / 030539A

Therefore, in view of the above circumstances, the present invention is for non-contact power feeding that enables miniaturization and thinning of portable electronic devices, reduces high frequency loss due to skin effect and proximity effect, and suppresses increase in AC resistance. It is an object of the present invention to provide a transmission coil. Further, it is an object of the present invention to provide a non-contact power feeding device having high transmission efficiency using this transmission coil.

The non-contact power feeding transmission coil of the first invention is a non-contact power feeding transmission coil including a substrate and a coil arranged on the substrate and wound in a spiral shape, and is a coil conductor cross section of the coil. The first magnetic film is provided on both side surfaces and both ends of the coil conductor, and the magnetic film is not covered on the upper surface of the coil conductor cross section other than the both ends .

In the non-contact power feeding transmission coil according to the first invention, the non-contact power feeding transmission coil according to the second invention is provided with a second magnetic film at a position facing the first magnetic film on the back surface of the substrate. It is characterized by.

The non-contact power feeding transmission coil according to the third invention has the length of a portion of the first magnetic film that covers the coil conductor on one end of the coil conductor cross section in the non-contact power feeding transmission coil according to the second invention. , The second magnetic film is characterized in that the lengths of the magnetic film portions facing each other via the substrate are substantially equal .

The non-contact power feeding transmission coil of the fourth invention is the non-contact power feeding transmission coil according to any one of the first to third inventions, and the magnetism on one end of the coil conductor cross section in the first magnetic film. It is characterized in that the length of the film portion is 1 time or more and 20 times or less the skin depth of the coil conductor .

The non-contact power supply transmission coil according to the fifth aspect of the invention is the non-contact power supply transmission coil according to any one of the first to fourth aspects , wherein the substrate is a flexible substrate. do.

The non-contact power feeding device according to the sixth aspect of the invention is characterized in that the non-contact power feeding transmission coil according to any one of the first to fifth inventions is used as a power transmission coil or as a power transmission coil and a power receiving coil.

According to the first invention, since the thin film magnetic film is provided not only on both side surfaces of the coil conductor cross section but also on both ends of the coil conductor cross section, the magnetic flux lines are distributed so as to bypass the coil conductor. Become. Therefore, the current concentration at both ends of the coil conductor cross section is relaxed, and the AC resistance of the coil can be reduced.

According to the second invention, since the thin film magnetic film is provided not only on both ends of the coil conductor but also on the back surface side of the substrate, the magnetic flux line can easily bypass the coil conductor. As a result, the current concentration is relaxed and the AC resistance can be further lowered.

According to the third invention, the length of the portion covering the coil conductor on one end of the cross section of the coil conductor is made substantially equal to the length of the magnetic film portion facing the second magnetic film via the substrate. AC resistance can be reduced more efficiently .

According to the fourth invention, by setting the length of the magnetic film portion on one end of the coil conductor cross section to be 1 time or more and 20 times or less the skin depth, the magnetic flux line from the side surface of the coil conductor cross section to the skin depth. The part where the magnetic flux is concentrated can be covered with a magnetic film, and the magnetic flux line can be efficiently diverted from the coil conductor to reduce the AC resistance .

According to the fifth invention, by using a flexible substrate as the substrate, it is possible to easily realize the miniaturization and thinning of the transmission coil for non-contact power feeding, and further improve the impact resistance due to its flexibility. ..

According to the sixth invention, since the transmission coil that can be manufactured at low cost by reducing the high frequency loss due to the skin effect and the proximity effect is used, it is possible to provide a non-contact power feeding device having high transmission efficiency and low cost.

It is a plan view (the part of a magnetic film is omitted) of the transmission coil which concerns on 1st and 2nd Embodiment. It is sectional drawing of the transmission coil which concerns on 1st Embodiment. It is sectional drawing of the transmission coil which concerns on 2nd Embodiment. It is a figure explaining the manufacturing process of the magnetic film of a transmission coil by applying a magnetic material. It is a figure explaining the manufacturing process of the magnetic film of a transmission coil by magnetic material plating. It is a figure explaining the manufacturing process of the magnetic film of a transmission coil by magnetic material sputtering. It is a circuit block diagram explaining the non-contact power feeding apparatus which concerns on one Embodiment. It is a figure (plan view) explaining the calculation model of a coil. It is sectional drawing of the transmission coil which has only the first magnetic film. It is a figure which shows the relationship between the AC resistance and D1 and L1 in the transmission coil which has only the first magnetic film. It is sectional drawing of the transmission coil which has the 1st magnetic film and the 2nd magnetic film. It is a figure which shows the relationship between the AC resistance and D1 and L1 in the transmission coil which has the 1st magnetic film and the 2nd magnetic film. It is sectional drawing of the transmission coil which arranged the magnetic film only on both side surface of the coil conductor cross section. It is a figure which shows the relationship between AC resistance and D2 in the transmission coil which arranged the magnetic film only on both side surfaces of the coil conductor cross section.

A transmission coil according to an embodiment of the present invention, a method for manufacturing the same, and a non-contact power feeding device using the transmission coil will be described with reference to the drawings.

<1. Transmission coil>
(First Embodiment)
FIG. 1 is a schematic plan view of only the coil portion of the transmission coil according to the first and second embodiments. The magnetic film portion is not shown by omission. The transmission coil 1 is a flat coil (three turns) in which a coil conductor 11 made of a metal of aluminum, copper or manganin (registered trademark) (alloy of copper, manganese and nickel) is spirally wound on a substrate 2. ) Is provided.

FIG. 2 is a schematic cross-sectional view of the transmission coil according to the first embodiment, and is shown by adding a magnetic film to the cross section of AA'in FIG. A coil conductor 11 is provided on the substrate 2, and a first magnetic film 31 is provided on both side surfaces and both ends of the cross section of the coil conductor 11 of each winding. The first magnetic film 31 can be made of a magnetic composite material containing an iron-based amorphous magnetic powder such as FeSiBCr, a Ni-based or Fe-based magnetic thin film, or the like.

When a high-frequency alternating current is passed through the coil conductor 11, magnetic flux lines are generated around the coil conductor 11, but due to the skin effect and proximity effect, the magnetic flux lines are concentrated at the end of the coil conductor cross section and penetrate the coil conductor 11. Therefore, the current is concentrated at the end of the coil conductor 11, and the resistance at the end increases. This effect is greater as the coil conductor 11 is thinner and the aspect ratio of the cross section is larger.

On the other hand, in the present embodiment, the first magnetic film 31 is arranged on both side surfaces of both ends of the coil conductor cross section and on the both sides thereof. That is, the first magnetic film 31 is arranged so as to cover the coil conductor at both ends of the coil conductor. As a result, the magnetic flux lines around the coil conductor 11 are attracted to and guided by the first magnetic film 31 having a high relative magnetic permeability, and are distributed around the coil conductor 11. Therefore, in the present embodiment, the problems of the concentration of magnetic flux lines and the concentration of current at both ends of the coil conductor 11 can be solved, and the increase in AC resistance can be suppressed.

Further, when the length of the magnetic film portion covering the coil conductor 11 of the first magnetic film 31 is long, the magnetic flux lines flowing around the coil conductor 11 are attracted to the magnetic film portion, but the relative permeability of the magnetic film portion is high. If is small, the magnetic flux line leaks from the magnetic film portion to the coil conductor 11 and easily penetrates the coil conductor 11. Therefore, current concentration occurs in the coil conductor 11, and the AC resistance also increases. This effect is large when the film thickness of the coil conductor 11 is as thin as the skin depth. This is because the current concentration occurs remarkably at a distance from the side surface of the coil conductor cross section to the depth of the skin.

Therefore, in order to efficiently attract and guide the magnetic flux lines, the length L1 of the magnetic film portion of the first magnetic film 31 on one end of the coil conductor cross section may be 1 time or more and 20 times or less the skin depth. preferable. The magnetic film portion can completely cover the skin depth of the coil at both ends of the coil cross section where current concentration occurs, and when the length L1 of the magnetic film portion exceeds 20 times the skin depth, the magnetic film portion is used. This is because the influence of the leakage of the magnetic flux line becomes large. More preferably, the length L1 of the magnetic film portion is 3 times or more and 12 times or less the depth of the epidermis.

The skin depth d can be expressed by the following equation.

ρ：コイル導体の電気抵抗率
ω：電流の角周波数（＝２π×周波数ｆ）
μ：コイル導体の透磁率（＝コイル導体の比透磁率μｒ×真空の透磁率μ_０）

ρ: Electrical resistivity of coil conductor ω: Angular frequency of current (= 2π × frequency f)
μ: Magnetic permeability of coil conductor (= relative magnetic permeability of coil conductor μr × magnetic permeability of vacuum μ ₀ )

Here, assuming that ρ = 1.72 × ^10-8 Ωm (assuming copper) and μ = 4π × ^10-7 H / m (corresponding to μr = 1), the skin depth d = 226 when f = 85 kHz. When .4 μm and f = 1 MHz, the skin depth d = 66 μm, and when f = 13.56 MHz, the skin depth d = 17.9 μm.

Further, regarding the specific magnetic permeability of the first magnetic film 31, the specific magnetic permeability is preferably 2 or more and 10,000 or less, and more preferably 10 or more and 10,000 or less, from the viewpoint of reducing leakage of magnetic flux lines. ..

(Second embodiment)
FIG. 3 is a schematic cross-sectional view of the transmission coil according to the second embodiment. The schematic plan view of the transmission coil (without the magnetic film) according to the second embodiment is the same as that in FIG. 1, and FIG. 3 shows a magnetic film on the AA'cross section of FIG. 1 in the schematic plan view. Is added and illustrated.

In the second embodiment, in the transmission coil according to the first embodiment, a second magnetic film 32 having a rectangular cross section is added to the back surface of the substrate 2 facing the first magnetic film 31 via the substrate 2. It was deployed. With respect to the first magnetic film 31 and the second magnetic film 32, the lengths of the magnetic film portions facing each other via the substrate 2 are substantially equal (that is, the first) from the viewpoint of suppressing leakage of magnetic flux lines to the coil conductor 11. It is preferable that the length L1 of the portion of the magnetic film 31 that covers the coil conductor on the cross section of the coil conductor is substantially equal to the length L2 of the magnetic film portion facing the second magnetic film 32 via the substrate 2).

Like the first magnetic material 31, the second magnetic film 32 can be made of a magnetic composite material containing an amorphous magnetic powder, a Ni-based or Fe-based magnetic thin film, or the like. As for the specific magnetic permeability, the specific magnetic permeability of the second magnetic film 32 is preferably 2 or more and 10,000 or less, and more preferably 10 or more and 10,000 or less, as in the case of the first magnetic film 31. ..

In the second embodiment, since the second magnetic film 32 is arranged at both ends of the coil conductor 11 in addition to the first magnetic film 31, it is possible to further suppress the increase in the AC resistance of the coil.

(Third embodiment)
The transmission coil according to the third embodiment is a transmission coil according to the first or second embodiment in which a flexible substrate is used as a substrate. By using a thin flexible substrate, the thickness of the transmission coil including the substrate can be further reduced, and the transmission coil can be made smaller and thinner. Further, since the flexible substrate has flexibility, excellent impact resistance can be realized for the transmission coil.

<2. Transmission coil manufacturing method>
(Manufacturing process of magnetic film by applying magnetic material)
FIG. 4 is a diagram illustrating a transmission coil manufacturing process according to an embodiment, particularly a first magnetic film manufacturing process by applying a magnetic material. The cross section of the transmission coil of the thin film formed by spirally winding into three turns is shown.

The first magnetic film is manufactured as follows. That is, (a) a copper foil having a predetermined film thickness attached on the substrate 2 is patterned in a spiral shape of a desired size by etching or the like to form the coil conductor 11. Then, a resist is applied or a resist film is attached onto the substrate 2 to form a layer of the resist 41 having a predetermined film thickness. (B) After that, the resist is exposed (irradiated) with ultraviolet rays via a photomask, developed and washed with water to pattern the resist 41, and openings of the resist are provided at both ends of the coil conductor 11. (C) Further, a magnetic material 42 containing an iron-based amorphous magnetic powder such as FeSiBCr in an epoxy resin or a silicon resin is applied to the surface of the substrate 2, and the magnetic material 42 is filled in the opening of the resist. (D) Then, the surface is flattened with a squeegee or the like to remove the unnecessary magnetic material 42 on the resist 41. (e) After that, the magnetic material 42 is 200 ° C. when it is an epoxy resin and 120 when it is a silicon resin. Heat mold at ° C and remove the resist with solvent. As a result, a first magnetic film having a predetermined shape is manufactured on the side surfaces and the upper surface of both ends of the coil conductor 11.

In (e), the resist can be left as it is without being removed. Further, the substrate 2 may be a flexible substrate.

The method for producing the first magnetic film described above can also be applied to the process for producing the second magnetic film. That is, in the same manner as in the above-mentioned manufacturing process, resist is applied or a resist film is attached and patterned on the back surface of the substrate on which the first magnetic film is formed by the above-mentioned manufacturing process, and the opening is filled with a magnetic material to form an unnecessary portion. The second magnetic film can be manufactured by removing the above. In order to allow the first magnetic film and the second magnetic film to be formed at the same positions on the front surface and the back surface of the substrate, a pin penetrating the substrate can also be used as a position marker.

(Manufacturing process of magnetic film by magnetic material plating or magnetic material sputtering)
FIG. 5 is a diagram illustrating a transmission coil manufacturing process according to another embodiment, particularly a first magnetic film manufacturing process by magnetic material plating. Similar to FIG. 4, a cross section of a thin film transmission coil formed by being spirally wound into three turns is shown.

The first magnetic film is manufactured as follows. That is, (a) a copper foil having a predetermined film thickness attached on the substrate 2 is patterned in a spiral shape of a desired size by etching or the like to form the coil conductor 11. Then, an insulating layer 43 made of, for example, silicon oxide (SiO ₂ ) or alumina (Al ₂ O ₃ ) is formed on the entire surface of the substrate 2 by sputtering, and subsequently, for example, nickel (Ni) or permalloy (NiFe). A plating base 44 made of silicon is formed into a film by sputtering or vapor deposition. The insulating layer 43 is for preventing a current from flowing from the coil conductor 11 through the magnetic material 42 made of metal, which will be described later. Then, a resist is applied or a resist film is attached onto the plating base 44 to form a layer of the resist 41 having a predetermined film thickness. (B) After that, the resist is exposed (irradiated) with ultraviolet rays via a photo mast, developed and washed with water to pattern the resist 41, and openings of the resist are provided at both ends of the coil conductor 11. (C) Then, this substrate is immersed in a plating solution containing nickel or nickel and iron (Fe), and an electric field is applied using the plating base 44 as a cathode, for example platinum as an anode, and the resist opens to open the plating base. Nickel or permalloy is plated on the exposed portion of 44 to form a magnetic material 42. (D) Further, the resist 41 is removed with a solvent, and (e) the surface on which the magnetic material 42 and the plating base 44 are exposed is scraped by ion milling with argon gas or the like or reverse sputtering. As a result, a first magnetic film having a predetermined shape is manufactured on the side surfaces and the upper surface of both ends of the coil conductor 11.

FIG. 6 is a diagram illustrating a transmission coil manufacturing process according to another embodiment, particularly a manufacturing process of a first magnetic film by magnetic material sputtering. Similar to FIGS. 4 and 5, a cross section of a thin film transmission coil formed by being spirally wound into three turns is shown.

The first magnetic film is manufactured as follows. That is, (a) a copper foil having a predetermined film thickness attached on the substrate 2 is patterned in a spiral shape of a desired size by etching or the like to form the coil conductor 11. Then, an insulating layer 43 made of, for example, silicon oxide (SiO ₂ ) or alumina (Al ₂ O ₃ ) is formed on the entire surface of the substrate 2 by sputtering, and a resist is applied or a resist film is applied thereto. Is attached to form a layer of resist 41 having a predetermined thickness. The insulating layer 43 is for preventing a current from flowing from the coil conductor 11 through the magnetic material 42 made of metal, which will be described later. (B) After that, the resist is exposed (irradiated) with ultraviolet rays via a photo mast, developed and washed with water to pattern the resist 41, and openings of the resist are provided at both ends of the coil conductor 11. (C) Then, nickel, permalloy or iron is sputtered on the entire surface of the substrate 2, and (d) the resist 41 is further removed by immersing the substrate in a solvent to lift off the magnetic material 42 on the resist 41. As a result, a first magnetic film having a predetermined shape is manufactured on the side surfaces and the upper surface of both ends of the coil conductor 11. As the magnetic material 42, in addition to a ferromagnetic material such as nickel, permalloy, or iron, in addition to silicon steel to which Si or the like is added, amorphous, sendust, metal oxide (ferrite), or the like can be used.

The above-mentioned method of magnetic material plating or magnetic material sputtering can also be applied to the second magnetic film.

In the case of magnetic material plating, a plating base is sputtered or vapor-deposited on the back surface of the substrate on which the first magnetic film is formed, and a resist is applied or a resist film is attached to form a resist layer, and the resist is placed in a predetermined position by exposure and development. An opening is provided, and the entire substrate is immersed in a plating solution to energize the plating base to form a plating film on the second magnetic film. Since the substrate has insulating properties, it is not necessary to form an insulating layer for forming the second magnetic film, unlike the case of the first magnetic film.

In the case of magnetic material sputtering, a resist is applied or a resist film is attached to the back surface of the substrate on which the first magnetic film is formed to form a resist layer, and a resist opening is provided at a predetermined position for exposure and development to provide the substrate. A magnetic material is sputtered on the entire surface of the back surface, the resist and the magnetic material in an unnecessary portion are removed by lift-off, and a second magnetic film is sputtered and formed. Since the substrate has insulating properties, it is not necessary to form an insulating layer for forming the second magnetic film, unlike the case of the first magnetic film.

In order to allow the first magnetic film and the second magnetic film to be formed at the same positions on the front surface and the back surface of the substrate, a pin penetrating the substrate can also be used as a position marker.

<3. Non-contact power supply device>
FIG. 7 is a circuit block diagram illustrating a non-contact power feeding device according to an embodiment. In this example, it is applied to a portable electronic device. This non-contact power supply device includes a power transmission device 5 that functions as a charger and a power receiving device 6 that includes a secondary battery 64 that serves as a power source for the mobile electronic device main body 7. The power transmitting device 5 and the power receiving device 6 are electromagnetically coupled to form a non-contact power feeding device that transmits power in a non-contact manner.

As shown in FIG. 7, the power transmission device 5 includes a power supply 51, a rectifier circuit 52, a power transmission circuit 53, and a power transmission coil 54. The power supply 51 is a system power supply that supplies, for example, a single-phase AC voltage of 100 V. In the rectifier circuit 52, the input end is connected to the power supply 51 and the output end is connected to the power transmission circuit 53, and the AC voltage supplied from the power supply 51 is rectified and converted into a DC voltage, and the converted DC voltage is converted. Output to the power transmission circuit 53. The transmission circuit 53 is a circuit in which an input end is connected to a rectifying circuit 52 and an output end is connected to both ends of a transmission coil 54, and an alternating current having a predetermined frequency is generated using a DC voltage from the rectifying circuit 52. The generated AC voltage is supplied to the transmission coil 54.

As shown in FIG. 7, the power receiving device 6 includes a power receiving coil 61, a power receiving circuit 62, a charge / discharge control circuit 63, and a secondary battery 64.

When the power receiving coil 61 is used so as to be close to and opposed to the power transmission coil 54 of the power transmission device 5, both coils 61 and 54 are electromagnetically coupled to form a transformer between them. The AC voltage induced in the power receiving coil 61 by this electromagnetic induction is supplied to the power receiving circuit 62, rectified in the power receiving circuit 62, and converted into a DC voltage. The DC voltage output from the power receiving circuit 62 is supplied to the secondary battery 64 via the charge / discharge control circuit 63 to charge the secondary battery 64. The charge / discharge control circuit 63 controls the charging of the secondary battery 64 when it is charged by the output from the power receiving circuit 62, and controls the charging when the portable electronic device main body 7 which is the load of the secondary battery 64 is operated. It is a circuit that controls the discharge. As the secondary battery 64, a lithium ion battery, a nickel hydrogen battery, or the like that can be repeatedly used by charging after discharging is used.

In the non-contact power feeding device according to the present embodiment, the above-mentioned transmission coil according to the present invention can be used for the transmission coil 54. As a result, since the transmission coil component that can be manufactured at low cost by reducing the high frequency loss due to the skin effect and the proximity effect is used, it is possible to provide a non-contact power feeding device having high transmission efficiency and low cost.

Further, the transmission coil according to the present invention described above may be used for the power receiving coil 61. Further, it is possible to provide a low-cost non-contact power feeding device having high transmission efficiency.

The non-contact power supply device according to the present invention is not limited to mobile electronic devices such as mobile phones, smartphones, and tablets. It may be used to power a vehicle such as an electric vehicle or a hybrid vehicle. Further, the transmission coil component according to the present invention may also be applied to an inductive heating device or the like. Further, the transmission coil component according to the present invention is not limited to use in an electromagnetic induction type non-contact power feeding device. It may also be applied to a magnetic field resonance type non-contact power feeding device.

Hereinafter, simulation results when the transmission coil component according to the present invention is implemented and applied will be described, but the present invention is not limited to the application examples described here.

<1. Simulation analysis model>
Before explaining an application example of the transmission coil according to the present invention by simulation, first, a simulation model for analyzing the characteristics of the coil (AC resistance, inductance, Q value, coupling coefficient k, transmission efficiency η) will be described. As the analysis software for the simulation, the electromagnetic field analysis software ANSYS Maxwell (manufactured by ANSYS) was used. Table 1 summarizes the conditions of analysis.

FIG. 8 is a diagram (plan view) for explaining the calculation model of the coil. However, the magnetic film is omitted and not shown. The coil conductor is assumed to be a copper material having a resistivity of 1.72 × ^10-8 Ωm. It is a spiral flat coil with three turns. The outer diameter (diameter) of the coil is OD, and the inner diameter (diameter) is ID.

<2. Application to power transmission coil>
When the transmission coil according to the present invention is applied as a power transmission coil, the coil characteristics (AC resistance, inductance, Q value) are calculated by changing the film thickness of the magnetic film and the length on the coil conductor. The outer diameter OD of the power transmission coil is φ73 mm, the inner diameter ID is φ47 mm, and the frequency of the alternating current energizing the coil is 13.56 MHz.

(When having only the first magnetic film)
FIG. 9 is a schematic cross-sectional view of the power transmission coil when it has only the first magnetic film and does not have the second magnetic film. Corresponds to the cross-sectional view taken along the line AA'in FIG. However, although the magnetic film is omitted in FIG. 8, the cross section of the magnetic film (first magnetic film) is also shown in FIG.

In FIG. 9, the thickness T1 of the substrate 2 is 0.025 mm. The coil conductor 11 has a rectangular cross section, the width W1 in the longitudinal direction of the coil conductor cross section is 3 mm, the thickness T2 is 0.035 mm, and the space W2 between the coil conductors is 2 mm. Further, the thickness of the magnetic film portion on the coil conductor of the first magnetic film 31 and the width of the magnetic film portion on the substrate 2 of the first magnetic film 31 arranged on both side surfaces of the coil conductor cross section are equal, and the value is D1. And. Further, the length of the magnetic film portion on the coil conductor of the first magnetic film 31 (distance where the first magnetic film 31 and the coil conductor 11 overlap) is defined as L1.

FIG. 10A is a graph showing the change in the AC resistance of the coil (relationship between the AC resistance and D1 and L1) when D1 and L1 are changed in FIG. From FIG. 10A, it can be seen that the AC resistance decreases with the increase of L1 for any D1, the L1 becomes the minimum at around 0.1 mm, and the AC resistance increases when this value is exceeded. I understand. Therefore, when L1 is 0 mm and the first magnetic film 31 does not overlap on the coil conductor 11 (that is, rectangular first magnetic films 31 having a width of D1 and a thickness of D1 + T2 are arranged on both sides of the coil conductor cross section. It can be seen that the AC resistance can be reduced by arranging the first magnetic film 31 (the length of the magnetic film portion on the coil conductor is L1) on the coil conductor.

10 (b) is an enlarged view of FIG. 10 (a) in which L1 is in the range of 0 to 0.5 mm. From FIG. 10B, when L1 = 0 mm, the AC resistance is the largest when D1 = 1.0 mm. The resistance R _max at this time is R _max = 180 mΩ.

Since the resistivity of the coil conductor = 1.72 × ^10-8 Ωm and the frequency of the current f = 13.56 MHz, the skin depth d is d = 17.9 μm. It can be seen that by using this skin depth d, the AC resistance can be further reduced for any D1 as long as L1 is in the range of d or more and 20 × d or less. Further, when D1 is 0.25 mm or more and L1 is 3 × d or more and 12 × d or less, the first magnetic film 31 described later is arranged in contact with only the side surface of the coil conductor 11 (first magnetic film 31). The thickness of the coil conductor 11 is the same as that of the coil conductor 11), and the AC resistance can be reduced by 15% or more.

Further, the coil characteristics (AC resistance, inductance, Q value) when D1 is 0.1 mm and L1 is 0.1 mm are shown in Table 2 as Example 1. Further, the coil characteristics were calculated in the case of not having the first magnetic film, that is, in the case of only the coil conductor and no magnetic film (corresponding to the case of D1 = 0 mm and L1 = 0 mm in FIG. 9). The obtained AC resistance, inductance, and Q value are summarized in Table 2 as Comparative Example 1.

(If you have a first magnetic film and a second magnetic film)
FIG. 11 is a schematic cross-sectional view of the power transmission coil when the first magnetic film 31 and the second magnetic film 32 are provided. Corresponds to the cross-sectional view taken along the line AA'in FIG. However, although the magnetic film is omitted in FIG. 8, the cross section of the magnetic film (first magnetic film and second magnetic film) is also shown in FIG.

In FIG. 11, the thickness T1 of the substrate 2, the width W1 in the longitudinal direction of the coil conductor cross section, the thickness T2 of the coil conductor cross section, and the space W2 between the coil conductors have only the first magnetic film shown in FIG. It is the same as the one. That is, T1 = 0.025 mm, W1 = 3 mm, T2 = 0.035 mm, and W2 = 2 mm. The thickness of the second magnetic film 32 is D1, and the length of the second magnetic film 32 in the direction parallel to the longitudinal direction of the coil conductor cross section is D1 + L1. The second magnetic film 32 is arranged at a position facing the first magnetic film 31 via the substrate 2. Therefore, the lengths of the respective portions of the first magnetic film 31 and the second magnetic film 32 facing each other via the coil conductor and the substrate are substantially equal.

FIG. 12 is a graph showing the change in the AC resistance of the coil (relationship between the AC resistance and D1 and L1) when D1 and L1 are changed in FIG. 12 (b) is an enlarged view of FIG. 12 (a) in which L1 is in the range of 0 to 0.5 mm. From FIG. 12, it can be seen that the AC resistance decreases with the increase of L1 for any D1, and L1 becomes the minimum at around 0.1 mm, and when this value is exceeded, the AC resistance increases. Table 2 shows the coil characteristics (AC resistance, inductance, Q value) when D1 is 0.1 mm and L1 is 0.1 mm as Example 2.

Further, when the magnetic film is arranged on the entire circumference of the coil conductor cross section, that is, when D1 is 1 mm and L1 is 1.5 mm in FIG. 11, the obtained coil characteristics (AC resistance, inductance, Q value) are compared. It is shown in Table 2 as 2.

(When the magnetic film is placed only on both sides of the coil conductor cross section)
FIG. 13 is a schematic cross-sectional view of a power transmission coil in which magnetic films are arranged only on both side surfaces of the cross section of the coil conductor 11. Corresponds to the cross-sectional view taken along the line AA'in FIG. However, although the magnetic film was omitted in FIG. 8, the cross section of the magnetic film (side magnetic film) is also shown in FIG. The side magnetic film 33 has a rectangular cross section and is arranged on both side surfaces of the cross section of the coil conductor 11. The film thickness of the side magnetic film 33 is equal to the thickness of the coil conductor cross section.

In FIG. 13, the thickness T1 of the substrate 2, the width W1 in the longitudinal direction of the coil conductor cross section, the thickness T2 of the coil conductor cross section, and the space W2 between the coil conductors have only the first magnetic film shown in FIG. It is the same as the one. That is, T1 = 0.025 mm, W1 = 3 mm, T2 = 0.035 mm, and W2 = 2 mm. The film thickness of the side magnetic film 33 is the thickness T2 of the cross section of the coil conductor. Further, the length of the side magnetic film 33 in the direction parallel to the longitudinal direction of the coil conductor cross section is defined as D2.

FIG. 14 is a graph showing the change in the AC resistance of the coil (relationship between the AC resistance and D2) when D2 is changed in FIG. Table 2 shows the coil characteristics (AC resistance, inductance, Q value) when D2 is 0.1 mm as Comparative Example 3.

<3. Application to power transmission coil and power reception coil>
The transmission coil component according to the present invention is used as a power transmission coil and a power reception coil. The coil characteristics (coupling coefficient k and transmission efficiency η) are calculated when the centers of both coils are aligned, the two coils face each other, and the two coils are opposed to each other with a distance (transmission distance) of 10 mm. The coupling coefficient k is a number representing the degree of coupling between the power transmitting coil and the power receiving coil constituting the transformer. Further, the transmission efficiency η can be obtained by the product of the coupling coefficient k and the Q value.

The outer diameter OD and inner diameter ID of the power transmission coil are described in <2. Application to power transmission coil> Similar to the one shown in>, φ73 mm and φ47 mm, respectively. The outer diameter OD and inner diameter ID of the power receiving coil are φ63 mm and φ37 mm, respectively, and the power receiving coil has a structure smaller than that of the transmitting coil.

(When having only the first magnetic film)
As the power transmission coil, the one used in the first embodiment is used.

The power receiving coil is basically the same as in the first embodiment, and the outer diameter OD and the inner diameter ID are different. That is, in FIG. 9, the thickness T1 of the substrate 2 of the power receiving coil, the width W1 in the longitudinal direction of the coil conductor cross section, the thickness T2 of the coil conductor cross section, the space W2 between the coil conductors, and the coil conductor of the first magnetic film 31. Thickness of the magnetic film portion (= width of the magnetic film portion on the substrate 2 of the first magnetic film 31 arranged on both side surfaces of the coil conductor cross section) D1 and the magnetic film portion on the coil conductor of the first magnetic film 31 The length (distance where the first magnetic film 31 and the coil conductor 11 overlap) L1 is the same as that of the first embodiment, T1 = 0.025 mm, W1 = 3 mm, T2 = 0.035 mm, W2 = 2 mm. , D1 = 0.1 mm, L1 = 0.1 mm.

The calculated coil characteristics (coupling coefficient k and transmission efficiency η) are shown in Table 2 as Example 3.

Further, when neither the transmission coil nor the power receiving coil has the first magnetic film, that is, when only the coil conductor has no magnetic film (T1 = 0.025 mm, W1 = 3 mm, T2 = 0.035 mm, W2 = in FIG. 9). Although it is 2 mm, the coil characteristics (coupling coefficient k and transmission efficiency η) were obtained for D1 = 0 mm and L1 = 0 mm. The results are summarized in Table 2 as Comparative Example 4.

(When having a first magnetic film and a second magnetic layer)
As the power transmission coil, the one used in the second embodiment is used.

The power receiving coil is basically the same as in the second embodiment, and the outer diameter OD and the inner diameter ID are different. That is, in FIG. 11, the power receiving coils T1, W1, T2, W2, D1 and L1 are T1 = 0.025 mm, W1 = 3 mm, T2 = 0.035 mm, W2 = 2 mm, D1 = as in the second embodiment. 0.1 mm, L1 = 0.1 mm.

The calculated coil characteristics (coupling coefficient k and transmission efficiency η) are shown in Table 2 as Example 4.

Further, in both the transmission coil and the power receiving coil, when the magnetic film is arranged on the entire circumference of the coil conductor cross section, that is, when D1 is 1 mm and L1 is 1.5 mm in FIG. 11, the obtained coil characteristics (coupling coefficient k and The transmission efficiency η) is shown in Table 2 as Comparative Example 5.

(When the magnetic film is placed only on both sides of the coil conductor cross section)
As the power transmission coil, the one used in Comparative Example 3 is used.

The power receiving coil is basically the same as in Comparative Example 3, and the outer diameter OD and the inner diameter ID are different. That is, in FIG. 13, the power receiving coils T1, W1, T2, W2 and D2 have T1 = 0.025 mm, W1 = 3 mm, T2 = 0.035 mm, W2 = 2 mm and D2 = 0. It is 1 mm.

The calculated coil characteristics (coupling coefficient k and transmission efficiency η) are shown in Table 2 as Comparative Example 6.

From Table 2, in Examples 1 and 2, the AC resistance is reduced, the Q value is high, and the high frequency loss is small as compared with Comparative Examples 1 and 3.

Further, from Table 2, it can be seen that higher transmission efficiency η can be obtained for Examples 3 and 4 as compared with Comparative Examples 4 to 6.

Therefore, it can be seen that by using the transmission coil component according to the present invention as a power transmission coil, and as a power transmission coil and a power reception coil, it is possible to suppress an increase in AC resistance and realize non-contact power supply with high transmission efficiency.

The transmission coil and the non-contact power feeding device according to the present invention can be used in the fields of electronic devices such as mobile phones, automobiles, and inductive heating devices.

1 Transmission coil 11 Coil conductor 2 Substrate 31 First magnetic film 32 Second magnetic film 33 Side magnetic film 41 Resist 42 Magnetic material 43 Insulation layer 44 Plating base 5 Transmission device 51 Power supply 52 Rectification circuit 53 Transmission circuit 54 Transmission coil 6 Power receiving device 61 Power receiving coil 62 Power receiving circuit 63 Charging / discharging control circuit 64 Secondary battery 7 Portable electronic device body

Claims (6)

A non-contact power supply transmission coil including a substrate and a coil arranged on the substrate and wound in a spiral shape.
A first magnetic film is provided on both sides and both ends of the coil conductor cross section of the coil .
The magnetic film is not covered on the upper surface of the coil conductor cross section except for both ends.
A transmission coil for non-contact power supply, which is characterized by the fact that. The non-contact power feeding transmission coil according to claim 1 , wherein a second magnetic film is provided on the back surface of the substrate at a position facing the first magnetic film. The length of the portion of the first magnetic film that covers the coil conductor on one end of the cross section of the coil conductor is substantially equal to the length of the magnetic film portion of the second magnetic film that faces the substrate via the substrate. The non-contact power feeding transmission coil according to claim 2. The invention according to claim 1 to 3, wherein the length of the magnetic film portion on one end of the cross section of the coil conductor in the first magnetic film is 1 time or more and 20 times or less the skin depth of the coil conductor. Transmission coil for non-contact power supply. The non-contact power feeding transmission coil according to claim 1 to 4, wherein the substrate is a flexible substrate. A non-contact power feeding device according to any one of claims 1 to 5 , wherein the non-contact power feeding transmission coil is used as a power transmission coil, or as a power transmission coil and a power receiving coil.

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