Coil for wireless charging and wearable device comprising same

Abstract

A coil for wireless charging and a wearable device comprising same are disclosed. The coil for wireless charging according to one aspect of the present invention is a coil for wireless charging in which a wire structure including at least one Litz wire formed of a plurality of strands is wound in an annular shape, wherein each of the plurality of strands may have a diameter or maximum width of 0.02 mm to 0.05 mm.

Description

Wireless charging coil and wearable device including the same

[0001] The present invention relates to a wireless charging coil and a wearable device including the same.

[0002] The basic operating frequency of the wireless charging system used in the Qi 1.x standard is 100 kHz, and the operating frequency is adjusted between 105 and 205 kHz depending on the alignment status and load conditions between the wireless charging transmitter and receiver coils, and the maximum output power is 5 W.

[0003] The Qi 2.0 MPP (Magnetic Power Profile) standard, announced in January 2023, stipulates that the operating frequency be increased to 360 kHz to support rapid wireless charging, enabling power supply of 15 W or more.

[0004] However, the wireless charging coil used in the Qi 1.x standard was designed for the 110kHz to 205kHz frequency band, and if it is used as is in a high-frequency band such as 360kHz, the skin effect will be aggravated, which may cause increased resistance and heat generation.

[0005] In particular, FPCB patterned coils are more susceptible to heat generation due to eddy current losses in the high-frequency band arising from the area required for pattern formation and the presence of insulating layers between the pattern layers. This heat generation issue can hinder stable rapid charging at 15W or higher, and therefore requires improvement.

[0006] The present invention is to solve the above problems, and the purpose of the present invention is to provide a wireless charging coil and a wearable device including the same that reduces resistance increase and heat generation problems caused by the skin effect of existing wireless charging coils at a charging operating frequency of 360 kHz band, which is relatively higher than the operating frequency of the existing Qi 1.x standard, and enables stable rapid charging.

[0007] The tasks of the present invention are not limited to the tasks mentioned above, and other tasks not mentioned will be clearly understood by those skilled in the art to which the present invention pertains from the description below.

[0008] According to one aspect of the present invention, a wireless charging coil is provided, which comprises a wire structure including at least one Litz wire formed of a plurality of strands and wound in a circular shape, wherein each of the plurality of strands has a diameter or maximum width of 0.02 mm to 0.05 mm.

[0009] At this time, the wireless charging coil can operate at an operating frequency in the range of 300 kHz 200 kHz to 400 500 kHz.

[0010] At this time, the wireless charging coil can operate at an operating frequency of 360 kHz.

[0011] Meanwhile, the Litz wires constituting the wire structure are provided in plurality, and the plurality of Litz wires can be electrically connected in parallel to form a single loop current.

[0012] Meanwhile, the plurality of thin lines can be formed to have the same cross-section.

[0013] Meanwhile, the plurality of fine lines may be formed such that any one of the plurality of fine lines has a different cross-section from the other.

[0014] Meanwhile, each of the plurality of fine wires may include a core made of a conductor.

[0015] At this time, each of the plurality of fine wires may further include an insulating layer coached on the outer surface of the core material.

[0016] At this time, each of the plurality of fine lines may further include a heat-sealing coating layer coated on the outer surface of the insulating layer.

[0017] Meanwhile, the cross-section of each of the plurality of lines may have either a circular or polygonal shape.

[0018] According to another aspect of the present invention, a wearable device including the wireless charging coil is provided.

[0019] According to the above configuration, a wireless charging coil according to one aspect of the present invention is made by winding a wire structure (100) including at least one Litz wire, wherein a plurality of fine wires constituting the Litz wire each have a diameter or maximum width of 0.02 mm to 0.05 mm, so that in an operating frequency band exceeding 100 kHz, preferably in a frequency band of 200 kHz to 500 kHz, and more preferably in a frequency band of 360 kHz determined as a rapid charging frequency in the wireless charging standard Qi2.0, the coil has low electrical resistance characteristics and low heat generation characteristics, and can perform high-speed rapid wireless charging of 15 W or more.

[0020] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the detailed description of the present invention or the composition of the invention described in the claims.

[0021] FIG. 1 is a drawing showing a wireless charging coil according to one embodiment of the present invention.

[0022] Figure 2 is a drawing viewed in the direction of the arrow from line AA of Figure 1.

[0023] FIG. 3 is a drawing showing one of the Litz wires constituting the wire structure illustrated in FIG. 2.

[0024] FIG. 4 is a drawing showing one of the fine wires constituting the Ritz wire illustrated in FIG. 3.

[0025] FIG. 5 is a diagram showing the results of a resistance test for a wireless charging coil according to one embodiment of the present invention.

[0026] Hereinafter, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily practice the present invention. The present invention may be implemented in various different forms and is not limited to the embodiments described herein. To clearly explain the present invention, parts irrelevant to the description are omitted in the drawings, and the same reference numerals designate identical or similar components throughout the specification.

[0027] The words and terms used in this specification and claims should not be construed as limited to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, in accordance with the principles by which the inventor can define terms and concepts in order to best explain his or her invention.

[0028] Therefore, the embodiments described in this specification and the configurations illustrated in the drawings correspond to a preferred embodiment of the present invention, and do not represent all of the technical ideas of the present invention, so there may be various equivalents and modified examples that can replace the configuration at the time of filing of the present invention.

[0029] In this specification, terms such as “include” or “have” are intended to describe the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but should be understood not to exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0030] When a component is said to be "in front of," "behind," "above," or "below" another component, this includes not only being placed "in front of," "behind," "above," or "below" the other component in direct contact with it, but also if there is another component intervening therebetween. Furthermore, when a component is said to be "connected" to another component, this includes not only being directly connected to one another, but also being indirectly connected to one another, unless there are special circumstances.

[0031] FIG. 1 is a drawing showing a wireless charging coil according to one embodiment of the present invention, FIG. 2 is a drawing viewed in the direction of an arrow from line AA of FIG. 1, FIG. 3 is a drawing showing one Litz wire constituting the wire structure shown in FIG. 2, and FIG. 4 is a drawing showing one thin wire constituting the Litz wire shown in FIG. 3.

[0032] For reference, in Fig. 2, only one of the multiple thin wires (111) constituting one Ritz wire (110) is indicated with a drawing symbol.

[0033] Referring to FIGS. 1 to 4, a wireless charging coil (10) according to one embodiment of the present invention is made by winding a wire structure (100).

[0034] The wireless charging coil (10) may be mounted on a wearable device and used as a wireless power reception antenna, or mounted on a wireless charger and used as a wireless power transmission antenna. In other words, the wireless charging coil (10) may be used as part of a wireless charging transmitter or as part of a wireless charging receiver.

[0035] The wire structure (100) may include at least one Litz wire (110).

[0036] In one embodiment of the present invention, the wire structure (100) may include a plurality of Litz wires (110) as shown in FIG. 2.

[0037] Alternatively, although not shown, the wire structure may comprise a single Litz wire.

[0038] In one embodiment of the present invention, a plurality of Litz wires (110) constituting the wire structure (100) are electrically connected in parallel to form a single loop current.

[0039] In this case, even if the thickness of the wire structure (100) is configured thinly, the current capacity is further expanded through parallel connection, so that efficient power transmission can be guaranteed even in high-speed wireless charging of 15 W or more.

[0040] The wire structure (100) is extended to a predetermined length.

[0041] A plurality of Litz wires (110) constituting the wire structure (100) may extend in parallel with each other and be joined by being in contact with each other laterally. At this time, a plurality of Litz wires (110) constituting the wire structure (100) may be arranged on the same plane (XY plane) as shown in FIG. 2 and joined to each other.

[0042] The cross-section of a wire structure (100) in which a plurality of Ritz wires (110) are combined may have a shape inscribed within a virtual rectangle (indicated by a dashed line in FIG. 2) having a predetermined thickness and width.

[0043] In other words, a wire structure (100) including a plurality of Litz wires (110) that are coupled to each other laterally may have a flat shape.

[0044] A plurality of Litz wires (110) may be mutually bonded by a heat-fusion method or an adhesive method. Alternatively, a plurality of Litz wires (110) may be mutually bonded by a known method or method.

[0045] The number of multiple Ritz wires (110) is shown as 12 in FIG. 2, but is not limited thereto.

[0046] A wire structure (100) including a plurality of Litz wires (110) is wound in a circular shape to form a wireless charging coil. At this time, the wire structure (100) may be wound on the same plane as the width direction of the wire structure (100) to form a wireless charging coil (10).

[0047] The Litz wire (110) has a structure including a plurality of fine wires (111) having a relatively small cross-sectional area compared to the entire cross-sectional area of ​​the Litz wire (110). As a result, the Litz wire (110) has a reduced skin effect and reduced heat generation compared to a general wire having a cross-sectional area substantially the same as the cross-sectional area of ​​the Litz wire (110) but having a single-strand structure.

[0048] A plurality of wires (111) are combined in a state of being twisted in a spiral or arranged in parallel adjacent to each other to form a Ritz wire (110).

[0049] In one embodiment of the present invention, the cross-section of each of the plurality of thin wires (111) may be circular.

[0050] At this time, a plurality of fine wires (111) can be arranged within a virtual circle (C) as shown in Fig. 3. In other words, the cross-section of the Litz wire (110) including a plurality of fine wires (111) is arranged within the virtual circle (C).

[0051] At this time, the plurality of fine lines (111) may be arranged to be mutually external, and the fine lines (111) arranged at the edges among the plurality of fine lines (111) may be arranged to be external to the virtual circle (C). At this time, the cross-section of the Litz wire (110) including the plurality of fine lines (111) may be internal to the virtual circle (C).

[0052] In this case, the empty space not occupied by a plurality of thin lines (111) having a predetermined diameter (d) within a virtual circle (C) having a predetermined diameter (D) can be minimized.

[0053] For example, the diameter (d) of the thin line (111) may be 1 / 3 times the diameter (D) of the virtual circle (C).

[0054] At this time, the number of multiple thin lines (111) may be seven. One of the seven thin lines (111) may be located in the center, and the remaining six may be arranged to be mutually circumscribed with the one located in the center as the center.

[0055] A single thin line (111) located in the center can be arranged in contact with six thin lines (111). The center point of the cross-section of the single thin line (111) located in the center can coincide with the center point of the virtual circle (C).

[0056] Seven thin wires (111) can fill the virtual circle (C) as much as possible. At this time, the empty space within the virtual circle (C) inscribed by the cross section of the Ritz wire (110) can be minimized.

[0057] Meanwhile, it is preferable that the diameter of the virtual circle (C) in which the plurality of thin wires (111) are arranged does not exceed 0.1 mm. If the diameter of the virtual circle (C) exceeds 0.01 mm, the overall thickness of the coil becomes thicker, and the thickness of the wireless charging transmitter or wireless charging receiver including the coil becomes thicker, making it difficult to apply it to a wearable device with a narrow installation space.

[0058] Alternatively, although not shown, the cross-section of each of the plurality of lines may be a polygon, such as a triangle, square, or pentagon.

[0059] For example, if the cross section of each thin line is a regular polygon, multiple thin lines can be arranged so that no empty space is created between the thin lines that are circumscribed.

[0060] At this time, the cross-section of the Litz wire including multiple fine lines may be a polygon such as a triangle or a square. At this time, it is preferable that the height of the cross-section of the Litz wire, or in other words, the thickness, does not exceed 0.1 mm.

[0061] In one embodiment of the present invention, a plurality of thin wires (111) may be formed to have the same cross-section, as illustrated in FIG. 3. Alternatively, although not illustrated, the plurality of thin wires may be formed such that one of the thin wires has a cross-section different from the other. Here, "different cross-sections" means that at least one of the cross-section shapes or areas is different.

[0062] In one embodiment of the present invention, each wire (111) may include a core material (111a), an insulating layer (111b), and a heat-sealing coating layer (111c).

[0063] The core material (111a) can be made of a conductor with high electrical conductivity, such as copper. The core material (111a) can have a predetermined length and a circular cross-section.

[0064] An insulating layer (111b) may be coated on the outer surface of the core material (111a). The insulating layer (111b) may be formed of a known insulating material.

[0065] A heat-sealing coating layer (111c) is formed on the outer surface of the insulating layer (111b). The heat-sealing coating layer (111c) can be formed of a known heat-sealing material such as varnish.

[0066] When heat is applied to a plurality of fine wires (111) in a spirally twisted state, a portion of the heat-sealing coating layer (111c) of each fine wire (111) melts and hardens, thereby bonding the plurality of fine wires (111) to each other. In this case, the plurality of fine wires (111) can be easily and simply bonded by the heat-sealing method.

[0067] Furthermore, when the wire structure (100) is wound into a coil shape and heat is applied, a portion of the heat-sealing coating layer (111c) of the thin wire (111) melts and hardens, thereby maintaining the coil shape of the wire structure (100).

[0068] Alternatively, although not shown, each wire may include a core and an insulating layer, excluding a heat-sealing coating layer. In this case, a plurality of wires may be helically twisted and integrally bonded to each other using a known adhesive method.

[0069] Alternatively, although not shown, the plurality of wires that make up the Litz wire may each contain only a core made of a conductor such as copper.

[0070] In one embodiment of the present invention, the cross-section of the thin wire (111) is circular. At this time, the diameter (d) of the thin wire (111) may be 0.02 mm or more and 0.05 mm or less.

[0071] If the cross-sectional diameter (d) of the fine wire (111) is less than 0.02 mm, the diameter (d) of the fine wire (111) is too small, so the cost for producing the fine wire (111) increases rapidly, and if the diameter (d) of the fine wire (111) exceeds 0.05 mm, heat generation increases rapidly in an operating frequency band exceeding 100 kHz, specifically in an operating frequency band ranging from 200 kHz to 500 kHz, and more specifically in an operating frequency of 360 kHz.

[0072] As another embodiment of the present invention, although not shown, when the cross-section of the thin line is a polygon other than a triangle, the maximum width of the thin line may be 0.02 mm or more and 0.05 mm or less. Here, the maximum width means the longest length between two points where the cross-section of the thin line and any straight line intersect.

[0073] For example, if the cross section of the line is a square or rectangle, the maximum width is the length between two opposite vertices.

[0074] As another embodiment of the present invention, although not shown, when the cross section of the thin wire is triangular, the maximum width of the thin wire may be 0.02 mm or more and 0.05 mm or less. Here, the maximum width means the length of the longest side among the three sides of the triangle.

[0075] FIG. 5 is a diagram showing the results of a resistance test for a wireless charging coil according to one embodiment of the present invention.

[0076] In Fig. 5, the experimental example (Case 2) is a wireless charging coil having a wire structure in which 12 Litz wires are wound in contact with each other on the same plane. The experimental example (Case 2) corresponds to an example of a wireless charging coil according to an embodiment of the present invention described above.

[0077] Here, the diameter of the virtual circle inscribed by the cross-section of the Litz wire including multiple fine wires is 0.09 mm, the diameter of the fine wires constituting the Litz wire is 0.03 mm, and the number of fine wires is 7.

[0078] In Fig. 5, the control example (Case 1) is a wireless charging coil that is wound with a wire structure in which 12 wires are connected to each other on the same plane.

[0079] Here, the cross-sectional diameter of the wire is 0.09 mm, and the wire has a general wire structure consisting of a single strand rather than a Litz wire structure.

[0080] In Fig. 5, the diameter of the virtual circle inscribed by the cross section of the Litz wire constituting the wire structure of the experimental example (Case 2) and the diameter of the wire constituting the wire structure of the control example (Case 1) are the same.

[0081] Referring to Fig. 5, it was confirmed that the wireless charging coil of the experimental example (Case 2) had lower electrical resistance than the wireless charging coil of the control example (Case 1) in an operating frequency band exceeding 100 kHz.

[0082] In particular, it was confirmed that the wireless charging coil of the experimental example (Case 2) had lower electrical resistance than the wireless charging coil of the control example (Case 1) in the frequency band of 200 kHz to 500 kHz.

[0083] In particular, it was confirmed that the wire structure of the control example (Case 1) had a significantly lower electrical resistance at 360 kHz, which was determined as a rapid charging frequency in the wireless charging standard Qi2.0.

[0084] The experimental results, such as those in Fig. 5, can be equally applied to other experimental examples in which the diameter of the fine wires constituting the Ritz wire satisfies the range of 0.02 mm or more and 0.05 mm or less.

[0085] The wireless charging coil (10) according to one embodiment of the present invention described above can be installed in a wearable device such as a smart watch, a smart ring, AR (Augmented Reality), VR (Virtual Reality), or XR (Extended Reality) and used as a wireless charging receiving antenna.

[0086] Such a wireless charging coil (10) is made by winding a wire structure (100) including at least one Litz wire (110), and each of the plurality of fine wires (111) constituting the Litz wire (110) has a diameter or maximum width of 0.02 mm to 0.05 mm, so that it has low electrical resistance characteristics and low heat generation characteristics in an operating frequency band exceeding 100 kHz, preferably in a frequency band of 200 kHz to 500 kHz, and more preferably in a frequency band of 360 kHz determined as a rapid operating frequency in the wireless charging standard Qi2.0, and can perform high-speed wireless charging of 15 W or more.

[0087] Although the embodiments of the present invention have been described, the spirit of the present invention is not limited to the embodiments presented in this specification, and those skilled in the art who understand the spirit of the present invention will be able to easily propose other embodiments by adding, changing, deleting, or adding components within the scope of the same spirit, but this will also be considered to fall within the spirit of the present invention.

Claims

1. A wireless charging coil comprising a wire structure including at least one Litz wire formed of a plurality of strands wound in a circular shape, A wireless charging coil, wherein each of the plurality of fine wires has a diameter or maximum width of 0.02 mm to 0.05 mm.

2. In paragraph 1, The above wireless charging coil is a wireless charging coil that operates at an operating frequency in the range of 200 kHz to 500 kHz.

3. In paragraph 2, The above wireless charging coil is a wireless charging coil that operates at an operating frequency of 360 kHz.

4. In paragraph 1, The Litz wires constituting the above wire structure are provided in multiples, A wireless charging coil wherein the plurality of Litz wires are electrically connected in parallel to form a single loop current.

5. In paragraph 1, A wireless charging coil, wherein the plurality of wires are formed to have the same cross-section.

6. In paragraph 1, The above multiple lines are, A wireless charging coil, wherein one of the plurality of wires is formed to have a different cross-section from the other.

7. In paragraph 1, The above multiple lines are each, A wireless charging coil comprising a core made of a conductor.

8. In paragraph 7, The above multiple lines are each, A wireless charging coil further comprising an insulating layer coated on the outer surface of the core material.

9. In paragraph 8, The above multiple lines are each, A wireless charging coil further comprising a heat-sealing coating layer coated on the outer surface of the insulating layer.

10. In paragraph 1, A wireless charging coil, wherein each cross-section of the plurality of wires has a shape of either a circle or a polygon.

11. A wearable device comprising a wireless charging coil according to any one of claims 1 to 10.

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