Wireless charging coil and wearable device including the same

Abstract

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

Description

Technical Field

[0001] This invention relates to a wireless charging coil and a wearable device including the same. Background Technology

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

[0003] In the Qi 2.0 Magnetic Power Profile (MPP) standard released in January 2023, the operating frequency was increased to 360kHz to support fast wireless charging, and it was specified that it could supply power of more than 15W.

[0004] However, the wireless charging coils used in the Qi 1.x standard are designed for the 110kHz to 205kHz frequency band. If they are used directly in a high-frequency band such as 360kHz, the skin effect will be aggravated, which may lead to increased resistance and heat generation problems.

[0005] In particular, in the case of patterned coils on flexible printed circuit boards (FPCBs), heat generation is more likely to occur due to eddy current losses in the high-frequency band generated within the area required for pattern formation, as well as the insulating layers present between the patterned layers. This heat generation issue can potentially make it difficult to achieve stable fast charging above 15W, and therefore requires improvement. Summary of the Invention

[0006] The technical problem that the invention aims to solve The present invention aims to solve the above-mentioned problems. The purpose of the present invention is to provide a wireless charging coil and a wearable device including the coil, which can reduce the resistance increase and heat generation problems caused by the skin effect of existing wireless charging coils at a charging operating frequency of 360kHz, which is higher than the operating frequency of the existing Qi 1.x standard, and achieve stable fast charging.

[0007] The subject matter of this invention is not limited to the subject matter described above. Other subject matters not mentioned can be clearly understood by those skilled in the art from the following description.

[0008] Technical solutions for solving the problem According to one aspect of the present invention, a coil for wireless charging is provided, wherein a wire structure is wound into a ring, the wire structure comprising at least one Litz wire formed by a plurality of strands, each of the plurality of strands having a diameter or a maximum width of 0.02 mm to 0.05 mm.

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

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

[0011] On the other hand, the Litz wires constituting the wire structure are configured as a plurality of Litz wires, which can be connected in parallel to form a single loop current.

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

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

[0014] On the other hand, each of the plurality of wires may include a core material made of a conductor.

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

[0016] At this time, each of the plurality of fine wires may also include a heat-fusion coating applied to the outer side of the insulating layer.

[0017] On the other hand, the cross-section of each of the plurality of thin lines can have any shape, such as a circle or a polygon.

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

[0019] Invention Effects According to the above configuration, the wireless charging coil of one aspect of the present invention is made by winding a wire structure 100 comprising at least one Litz wire. Each of the plurality of fine wires constituting the Litz wire has a diameter or maximum width of 0.02 mm to 0.05 mm, thereby having low resistance and low heat generation characteristics in a 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, which is determined as the fast charging frequency in the wireless charging standard Qi2.0, and is capable of performing high-speed fast wireless charging of 15W or more.

[0020] The effects of the present invention are not limited to those described above, but should be understood to include all effects that can be inferred from the inventive structure described in the detailed description or claims of the present invention. Attached Figure Description

[0021] Figure 1 A diagram illustrating a wireless charging coil according to an embodiment of the present invention.

[0022] Figure 2 From Figure 1 The diagram is viewed along line AA in the direction of the arrow.

[0023] Figure 3 To illustrate the composition Figure 2 A diagram of any of the Litz wires in the wire structure shown.

[0024] Figure 4 To illustrate the composition Figure 3 A diagram of any of the thin lines of the Lids line shown.

[0025] Figure 5 A graph showing the experimental results of the resistance of a wireless charging coil according to an embodiment of the present invention. Detailed Implementation

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings to enable those skilled in the art to readily implement the invention. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. For clarity of illustration, parts unrelated to the description have been omitted from the drawings, and the same reference numerals are used throughout the specification for the same or similar constituent elements.

[0027] The words and terms used in this specification and claims should not be limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts consistent with the technical ideas of this invention, in accordance with the principle that inventors may define terms and concepts in order to best illustrate their invention.

[0028] Therefore, the embodiments described in this specification and the configuration shown in the accompanying drawings are preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, at the time of application of the present invention, there may be various equivalents and modifications that can replace the corresponding configurations.

[0029] In this specification, terms such as “comprising” or “having” are intended to describe the presence of features, figures, steps, actions, constituent elements, components, or combinations thereof described in the specification, and should be understood as not precluding the presence or additional possibility of one or more other features, figures, steps, actions, constituent elements, components, or combinations thereof.

[0030] Unless otherwise specified, when a constituent element is located "in front of," "behind," "above," or "below" another constituent element, this includes not only the case where it is directly in contact with the other constituent element and positioned in front of, behind, above, or below it, but also the case where another constituent element is positioned between them. Furthermore, unless otherwise specified, when a constituent element is "connected" to another constituent element, this includes not only the case where they are directly connected, but also the case where they are indirectly connected.

[0031] Figure 1 A diagram illustrating a wireless charging coil according to an embodiment of the present invention is provided. Figure 2 From Figure 1 The diagram viewed along line AA in the direction of the arrow. Figure 3 To illustrate the composition Figure 2 The diagram shows any of the Litz wires in the wire structure shown. Figure 4 To illustrate the composition Figure 3 A diagram of any of the thin lines of the Lids line shown.

[0032] For reference, Figure 2 In the figure, only one of the multiple thin lines 111 that constitute a Lids line 110 is marked with a reference numeral.

[0033] Reference Figures 1 to 4 According to an embodiment of the present invention, the wireless charging coil 10 is made by a wire winding structure 100.

[0034] The wireless charging coil 10 can be mounted on a wearable device as a wireless power receiving antenna, or it can be mounted on a wireless charger as a wireless power transmitting antenna. In other words, the wireless charging coil 10 can be used as part of a wireless charging transmitter, or it can be used 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 can be as follows: Figure 2 The diagram shows multiple Liz lines 110.

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

[0038] In one embodiment of the 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 made relatively thin, the current capacity can be further expanded through parallel connection, thereby ensuring efficient power transmission even in high-speed wireless charging of 15W or more.

[0040] The wire structure extends to a predetermined length of 100.

[0041] The plurality of Litz wires 110 constituting the wire structure 100 extend side by side and can contact and join with each other in the lateral direction. At this time, the plurality of Litz wires 110 constituting the wire structure 100 can be as follows: Figure 2 The configurations shown are on the same plane (XY plane) and combined with each other.

[0042] The cross-section of a wire structure 100 incorporating multiple Litz wires 110 can have an inscribed shape within an imaginary rectangle having a predetermined thickness and width (in... Figure 2 The shape within (represented by dashed lines).

[0043] In other words, the wire structure 100, which includes multiple Litz wires 110 joined together in the lateral direction of each other, can have a flat shape.

[0044] Multiple Litz wires 110 can be bonded together by heat fusion or adhesive bonding. Alternatively, multiple Litz wires 110 can be bonded together by known methods or means.

[0045] The number of multiple Leeds lines 110 is in Figure 2 The number shown is 12, but it is not limited to this.

[0046] A wire structure 100 comprising multiple Litz wires 110 is wound into a loop to form a wireless charging coil. In this case, the wire structure 100 can be wound in the same plane along its width direction to form a wireless charging coil 10.

[0047] The Litz wire 110 has a structure comprising a plurality of thin wires 111, each thin wire 111 having a cross-sectional area smaller than the overall cross-sectional area of ​​the Litz wire 110. Therefore, compared to ordinary wires having a cross-sectional area substantially the same as that of the Litz wire 110 but with a single-strand structure, the Litz wire 110 exhibits reduced skin effect and less heat generation.

[0048] Multiple fine lines 111 are combined in a spiral twisted state or arranged side by side to form a Litz line 110.

[0049] In one embodiment of the present invention, the cross-section of each of the plurality of thin lines 111 can be circular.

[0050] At this point, multiple thin lines 111 can be as follows: Figure 3The arrangement shown is within the imaginary circle C. In other words, the cross-section of the Litz line 110, which includes multiple thin lines 111, is arranged within the imaginary circle C.

[0051] At this point, the plurality of thin lines 111 are externally circumscribed to each other, and the thin lines 111 disposed at the edge of the plurality of thin lines 111 can be configured to be externally circumscribed to the imaginary circle C. At this point, the cross section of the Litz line 110, which includes the plurality of thin lines 111, can be internally circumscribed to the imaginary circle C.

[0052] In this case, within an imaginary circle C with a predetermined diameter D, the unoccupied space of multiple thin lines 111 with a predetermined diameter d can be minimized.

[0053] For example, the diameter d of the thin line 111 can be 1 / 3 times the diameter D of the imaginary circle C.

[0054] At this point, the number of multiple thin wires 111 can be seven. One of the seven thin wires 111 is located in the center, and the other six can be arranged externally around the one located in the center.

[0055] A central thin wire 111 can be configured with six thin wires 111 externally grounded. The center point of the cross-section of the central thin wire 111 can coincide with the center point of the imaginary circle C.

[0056] The seven thin lines 111 can fill the imaginary circle C to the maximum extent. At this time, the empty space inside the imaginary circle C inscribed by the cross section of the Litz line 110 can be minimized.

[0057] On the other hand, the diameter of the imaginary circle C, which is configured with multiple fine lines 111, is preferably no more than 0.1 mm. If the diameter of the imaginary circle C exceeds 0.1 mm, the overall thickness of the coil becomes thicker, and the thickness of the wireless charging transmitter or wireless charging receiver, including the coil, also becomes thicker, which may make it difficult to apply to wearable devices with limited installation space.

[0058] Alternatively, although not shown, the cross-sections of the multiple thin lines can be polygons such as triangles, quadrilaterals, and pentagons.

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

[0060] At this point, the cross-section of the Litz wire, which includes multiple thin lines, can be a polygon such as a triangle or a quadrilateral. The height of the Litz wire's cross-section, in other words, its thickness, is preferably no more than 0.1 mm.

[0061] In one embodiment of the present invention, the plurality of fine lines 111 can be as follows: Figure 3The diagram shows lines formed with identical cross-sections. Alternatively, although not shown, multiple lines can be formed such that any one of the lines has a different cross-section from the others. Here, "different cross-sections" means that at least one of the cross-sections is different, either in shape or area.

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

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

[0064] The insulating layer 111b can be coated on the outer surface of the core material 111a. The insulating layer 111b can be formed from a known insulating material.

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

[0066] If heat is applied while the multiple fine wires 111 are twisted in a spiral shape, the multiple fine wires 111 will bond together with each other during the process of melting and solidifying a portion of the heat-fusion coating 111c of each fine wire 111. In this case, the multiple fine wires 111 can be easily and simply bonded together by heat fusion.

[0067] Furthermore, if the wire structure 100 is wound into a coil shape and then heated, a portion of the heat-fusion coating 111c of the thin wire 111 melts and solidifies, thereby maintaining the coil shape of the wire structure 100.

[0068] Alternatively, although not shown, each wire may not include a heat-fusion coating, but may include a core material and an insulating layer. In this case, multiple wires can be integrally joined together in a spirally twisted state by a known bonding method.

[0069] Alternatively, although not shown, the multiple thin wires that make up the Litz wire may each consist of a core material 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. In this case, the diameter d of the thin wire 111 can be 0.02 mm or more and 0.05 mm or less.

[0071] If the diameter d of the cross-section of the thin wire 111 is less than 0.02 mm, the cost of producing the thin wire 111 will increase dramatically due to the small diameter d. If the diameter d of the thin wire 111 exceeds 0.05 mm, the heat generation will increase dramatically in the operating frequency band above 100 kHz, specifically in the operating frequency band from 200 kHz to 500 kHz, and more specifically at the 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 can be 0.02 mm or more and 0.05 mm or less. Here, the maximum width refers to the longest length among the lengths between two points where the cross-section of the thin line intersects with any straight line.

[0073] For example, when the cross-section of the thin line is a square or rectangular shape, the length between two opposite vertices is the maximum width.

[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 can be more than 0.02 mm and less than 0.05 mm. Here, the maximum width refers to the length of the longest side among the three sides of the triangle.

[0075] Figure 5 A graph showing the resistance test results of a wireless charging coil according to an embodiment of the present invention.

[0076] exist Figure 5 In the example (Case 2), a wireless charging coil is formed by winding a wire structure consisting of 12 Litz wires that are in contact with and bonded together on the same plane. Example (Case 2) is one instance of the wireless charging coil described above according to an embodiment of the present invention.

[0077] Here, the diameter of the imaginary circle inscribed in the cross section of the Litz wire, which includes multiple thin lines, is 0.09 mm, the diameter of the thin lines constituting the Litz wire is 0.03 mm, and the number of thin lines is 7.

[0078] exist Figure 5 In the comparative example (Case 1), a wireless charging coil is formed by winding a wire structure consisting of 12 wires that are in contact with each other and joined together on the same plane.

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

[0080] exist Figure 5In the experimental example (Case 2), the diameter of the imaginary circle inscribed in the cross section of the Litz wire constituting the wire structure is the same as the diameter of the wire constituting the control example (Case 1).

[0081] Reference Figure 5 It can be confirmed that the wireless charging coil of the experimental example (Case 2) has a lower resistance than the wireless charging coil of the control example (Case 1) in the operating frequency band above 100kHz.

[0082] In particular, it can be confirmed that the wireless charging coil of the experimental example (Case 2) has a lower resistance in the frequency band of 200kHz to 500kHz compared with the wireless charging coil of the control example (Case 1).

[0083] In particular, it can be confirmed that at 360kHz, the fast charging frequency determined in the Qi2.0 wireless charging standard, the wire structure has a significantly lower resistance compared to the control example (Case 1).

[0084] like Figure 5 The experimental results shown can also be applied to other experimental examples where the diameter of the thin wire constituting the Litz wire is between 0.02 mm and 0.05 mm.

[0085] The wireless charging coil 10 described above according to an embodiment of the present invention can be mounted on wearable devices such as smartwatches, smart rings, augmented reality (AR), virtual reality (VR), and extended reality (XR), and used as a wireless charging receiving antenna.

[0086] This wireless charging coil 10 is made by winding a wire structure 100 including at least one Litz wire 110. 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, thereby exhibiting low resistance and low heat generation characteristics in a 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, which is determined as the fast operating frequency in the wireless charging standard Qi2.0, and is capable of performing high-speed wireless charging of 15W or more.

[0087] Although embodiments of the present invention have been described, the spirit of the present invention is not limited to the embodiments shown in this specification. Those skilled in the art who understand the spirit of the present invention can easily propose other embodiments by adding, changing, deleting, or supplementing the constituent elements within the same spirit, and these should also fall within the spirit of the present invention.

Claims

1. A coil for wireless charging, comprising a wire structure wound into a loop, said wire structure including at least one Litz wire formed by a plurality of strands. in, Each of the plurality of fine lines has a diameter or maximum width of 0.02 mm to 0.05 mm.

2. The wireless charging coil according to claim 1, wherein, The wireless charging coil operates at a frequency in the range of 200kHz to 500kHz.

3. The wireless charging coil according to claim 2, wherein, The wireless charging coil operates at a frequency of 360kHz.

4. The wireless charging coil according to claim 1, wherein, The Litz wires constituting the wire structure are provided in multiple configurations. The multiple Litz wires are connected in parallel to form a single loop current.

5. The wireless charging coil according to claim 1, wherein, The multiple thin lines are formed to have the same cross-section.

6. The wireless charging coil according to claim 1, wherein, The plurality of fine lines are formed such that any one of the fine lines has a different cross-section from the others.

7. The wireless charging coil according to claim 1, wherein, Each of the plurality of thin wires includes a core material made of conductor.

8. The wireless charging coil according to claim 7, wherein, Each of the plurality of fine wires also includes an insulating layer coated on the outer surface of the core material.

9. The wireless charging coil according to claim 8, wherein, Each of the plurality of fine wires also includes a heat-fusion coating applied to the outer side of the insulating layer.

10. The wireless charging coil according to claim 1, wherein, The cross-sections of each of the plurality of thin lines have either a circular or a polygonal shape.

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

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