Flexible circuit board and smart glasses

Abstract

The application is suitable for the field of near-eye display devices, and discloses a flexible circuit board and smart glasses. The flexible circuit board has a bending area and a non-bending area. The flexible circuit board comprises a base body and a ground wire layer. The ground wire layer comprises an electromagnetic shielding film, and the electromagnetic shielding film covers at least the bending area. The electromagnetic shielding film comprises a first base material layer, a conductive layer and a protective layer. The first base material layer is connected to the base body. The conductive layer is arranged on the surface of the first base material layer away from the base body. The protective layer covers one side of the conductive layer away from the first base material layer.

Description

Technical Field

[0001] This application relates to the field of near-eye display devices, and more particularly to a flexible circuit board and smart glasses. Background Technology

[0002] With the rapid development of display technology, sensor technology, and computer vision technology, a new generation of near-eye display devices, such as AR (Augmented Reality) glasses, are gradually emerging. Smart glasses can display virtual projection information generated through optical waveguides, allowing real-world images and virtual projection information to be superimposed on each other and enter the user's field of vision, thus achieving augmented reality display.

[0003] Electronic devices can be installed in the frames and temples of smart glasses. To enable communication between these electronic devices, they can be connected via flexible printed circuit boards (FPCs).

[0004] Because the frame and temples need to be opened and closed frequently, the FPC will be repeatedly bent. However, the existing FPC has a poor bending life, which can easily cause damage to the FPC during long-term use, thereby affecting the circuit connection of the smart glasses. Summary of the Invention

[0005] The purpose of this application is to provide a flexible circuit board and smart glasses, which aim to improve the bending life of the flexible circuit board.

[0006] To achieve the above objectives, this application provides a flexible circuit board for use in smart glasses, the flexible circuit board having a bending area and a non-bending area; the flexible circuit board includes:

[0007] Matrix;

[0008] A ground layer, the ground layer including an electromagnetic shielding film, the electromagnetic shielding film at least covering the bending area;

[0009] The electromagnetic shielding film includes a first substrate layer, a conductive layer, and a protective layer. The first substrate layer is connected to the substrate, the conductive layer is disposed on the surface of the first substrate layer away from the substrate, and the protective layer covers the side of the conductive layer away from the first substrate layer.

[0010] This application also provides a smart glasses, including a frame, temples, and a flexible circuit board as described above;

[0011] The frame and temples are hinged together, the flexible circuit board passes through the frame and temples, the bending area is located inside the frame, and the non-bending areas are located inside the frame and temples respectively, for connecting electronic devices. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of the structure of the smart glasses provided in the embodiments of this application;

[0014] Figure 2 This is a schematic diagram of the structure of the flexible circuit board provided in the embodiments of this application;

[0015] Figure 3 This is one of the schematic diagrams of the stacked structure of the flexible circuit board provided in the embodiments of this application;

[0016] Figure 4 This is a schematic diagram of the stacked structure of the electromagnetic shielding film provided in the embodiments of this application;

[0017] Figure 5 This is a second schematic diagram of the stacked structure of the flexible circuit board provided in the embodiments of this application; wherein, the ground layer in the non-bending area is the first copper foil layer;

[0018] Figure 6 This is one of the cross-sectional structural schematic diagrams of the protective layer of the electromagnetic shielding film provided in the embodiments of this application; wherein, the protective layer has a wavy microstructure;

[0019] Figure 7 This is a second schematic diagram of the structure of the protective layer of the electromagnetic shielding film provided in this application embodiment; wherein, the protective layer has a honeycomb microstructure;

[0020] Figure 8 This is the third schematic diagram of the stacked structure of the flexible circuit board provided in the embodiments of this application; wherein, the substrate includes a functional layer;

[0021] Figure 9 This is the fourth schematic diagram of the stacked structure of the flexible circuit board provided in the embodiments of this application; wherein, the substrate includes two functional layers;

[0022] Figure 10 This is a schematic diagram of the signal layer structure provided in an embodiment of this application.

[0023] Explanation of icon numbers:

[0024] 1000: Smart glasses;

[0025] 100: Flexible circuit board; 101: Bending area; 102: Non-bending area; 1021: First non-bending area; 1022: Second non-bending area;

[0026] 10: Substrate; 11: Signal layer; 111: Second substrate layer; 112: Signal transmission device; 12: Charging layer; 13: Adhesive layer; 14: Second cover film; 15: Second adhesive layer;

[0027] 20: Ground layer;

[0028] 21: Electromagnetic shielding film; 211: First substrate layer; 212: Conductive layer; 213: Protective layer; 214: First adhesive layer;

[0029] 22: First copper foil layer; 23: Third substrate layer; 24: First cover film; 25: Third adhesive layer;

[0030] 200: Picture frame;

[0031] 300: Temples. Detailed Implementation

[0032] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0033] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0034] It should also be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or may be connected to an intermediary component. When a component is referred to as being "connected to" another component, it can be directly connected to the other component or indirectly connected to the other component through an intermediary component.

[0035] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0036] like Figure 1 As shown, this application embodiment provides a flexible circuit board 100 applied to smart glasses 1000. The smart glasses 1000 are wearable on the wearer's head and can be VR (Virtual Reality) glasses, AR (Augmented Reality) glasses, XR (Extender Reality) glasses, MR (Mixed Reality) glasses, or other wearable glasses.

[0037] In some embodiments, the smart glasses 1000 includes a frame 200, temples 300, and a flexible circuit board 100. The frame 200 and temples 300 are hinged together, and the flexible circuit board 100 passes through the frame 200 and temples 300 to connect electronic devices. It should be noted that there are two temples 300, each connected to one side of the frame 200, allowing them to rest stably on the user's ears. The flexible circuit board 100 at the hinge points between the temples 300 and the frame 200 has bending areas, allowing it to bend and deform with the rotation of the temples 200, adapting to changes in the relative position of the temples 300 and the frame 200.

[0038] For ease of explanation, this description focuses on the hinged connection between one side of the temple 300 and the frame 200, and the rotation of the temple 300 relative to the frame 200. One end of the flexible circuit board 100 is located within the temple 300 to connect electronic devices, and the other end is located within the frame 200 to connect electronic devices. As the temple 300 rotates relative to the frame 200, the bending area 101 of the flexible circuit board 100 will bend or straighten due to the rotation of the rotating component between the temple 300 and the frame 200. In some embodiments, the temple 300 can rotate relative to the frame 200 to an unfolded state and a folded state. When the temple 300 is rotated to the folded state relative to the frame 200, the temple 300 and the frame 200 are arranged side by side. At this time, the smart glasses 1000 is in a stored state and can be used for storage or charging. The bending area 101 of the flexible circuit board 100 is bent. When the temple 300 is rotated to the unfolded state relative to the frame 200, the temple 300 extends away from the frame 200. At this time, the smart glasses 1000 can be worn by the user, and the bending area 101 of the flexible circuit board 100 returns to a straight state. The flexible circuit board 100 can bend as the temple 300 rotates relative to the frame 200 to ensure the stability of the temple 300's rotation and the stable connection between the electronic components on the temple 300 and the electronic components on the frame 200.

[0039] like Figure 2 As shown, in some embodiments, the flexible circuit board 100 has a bending region 101 and a non-bending region 102. The bending region 101 of the flexible circuit board 100 has high flexibility and can still maintain the integrity of its structure under large-amplitude and high-frequency bending. The non-bending region 102 of the flexible circuit board 100 can have a certain degree of flexibility or can be a rigid board, without limitation.

[0040] In some embodiments, the flexible circuit board 100 passes through the frame 200 and the temple 300, with a bending region 101 disposed within the frame 200 and non-bending regions 102 disposed within the frame 200 and the temple 300, respectively. The bending region 101 of the flexible circuit board 100 can bend with the relative rotation of the temple 300 and the frame 200, while the non-bending regions 102 of the flexible circuit board 100 can be stably installed within the frame 200 and the temple 300 to stably connect electronic devices.

[0041] In some embodiments, the flexible circuit board 100 has two non-bending regions 102 and a bending region 101 located between the two non-bending regions 102. The two non-bending regions 102 are respectively placed within the temple 300 and the frame 200, and the bending region 101 is placed within the frame 200. Specifically, as... Figure 2As shown, the non-bending area 102 includes a first non-bending area 1021 and a second non-bending area 1022. The first non-bending area 1021 is disposed within the temple 300, and the second non-bending area 1022 is disposed within the frame 200.

[0042] In some embodiments, the end of the temple 300 is provided with a battery compartment assembly, and the frame 200 is provided with electronic devices such as an optical engine. The optical engine is used for light output display. The battery compartment assembly is provided with a main control board and electronic devices such as a battery. A flexible circuit board 100 passes through the frame 200 and the temple 300 to connect the electronic devices and the optical engine in the battery compartment assembly.

[0043] like Figure 3 As shown, in some embodiments, the flexible circuit board 100 includes a substrate 10 and a ground layer 20. The ground layer 20 includes an electromagnetic shielding film 21, which at least covers the bending region 101. It is understood that the substrate 10 is the upper structure of the flexible circuit board 100, and it includes at least one signal layer 12, without limitation. The ground layer 20 is the lower structure of the flexible circuit board 100, serving as a ground line. It provides a low-impedance return path, reduces EMI, ensures signal integrity, enhances power integrity, assists in heat dissipation, and simplifies wiring, significantly improving the performance, stability, and reliability of the electronic circuit. While conventional ground layers 20 are generally copper foil layers, in this application, the electromagnetic shielding film 21 serves as at least a portion of the ground layer 20.

[0044] like Figure 4 As shown, in some embodiments, the electromagnetic shielding film 21 includes a first substrate layer 211, a conductive layer 212, and a protective layer 213. The first substrate layer 211 is connected to the substrate 10, the conductive layer 212 is disposed on the surface of the first substrate layer 211 facing away from the substrate 10, and the protective layer 213 covers the side of the conductive layer 212 facing away from the first substrate layer 211. The first substrate layer 211 provides mechanical support and electrical insulation, the conductive layer 212 provides a current path, and the protective layer 213 protects both the conductive layer 212 and the first substrate layer 211. The conductive layer 212, compared to a copper foil layer, offers better flexibility while still meeting basic conductivity requirements. Furthermore, with the protective layer 213 already present, there is no need to provide a cover film on the side of the electromagnetic shielding film 21 facing away from the substrate 10.

[0045] It is understood that the electromagnetic shielding film 21 covers at least the bending area 101, which means that the electromagnetic shielding film 21 can be set only in the bending area 101. Of course, the electromagnetic shielding film 21 can also be set in the non-bending area 102. For example, the entire ground layer 20 is the electromagnetic shielding film 21.

[0046] In the flexible circuit board 100 of this embodiment, the electromagnetic shielding film 21, while meeting basic conductivity requirements, also possesses superior flexibility. By using the electromagnetic shielding film 21 as at least the ground layer 20 of the bending region 101 of the flexible circuit board 100, the flexibility of the flexible circuit board 100 in the bending region 101 can be significantly improved. Furthermore, since the electromagnetic shielding film 21 already has a protective layer 213, there is no need to provide a cover film for its protection; therefore, the thickness of the flexible circuit board 100 in the bending region 101 can be significantly reduced. This improves the dynamic bending life of the flexible circuit board 100, ensuring stable circuit connections between the electronic components of the smart glasses 1000.

[0047] In some embodiments, the thickness of the electromagnetic shielding film 21 is 20μm-50μm. It should be noted that the conventional ground layer 20 is generally a copper foil layer, and to protect the copper foil layer, a cover film is required on the side of the copper foil layer away from the substrate 10, resulting in a conventional ground layer 20 thickness of 80-150μm. Therefore, the thickness of the electromagnetic shielding film 21 is significantly lower than that of the conventional ground layer 20; for example, the thickness of the electromagnetic shielding film 21 is reduced by 32.5μm compared to the conventional ground layer 20. Therefore, using the electromagnetic shielding film 21 as at least the ground layer 20 of the bending region 101 of the flexible circuit board 100 can significantly reduce the thickness of the flexible circuit board 100 in the bending region 101. This improves the dynamic bending life of the flexible circuit board 100, ensuring stable circuit connections between the electronic components of the smart glasses 1000.

[0048] For example, but not limitingly, the thickness of the electromagnetic shielding film 21 may be 20 μm, 22 μm, 25 μm, 30 μm, 35 μm, 38 μm, 40 μm, 45 μm, 50 μm, or any range of two such values.

[0049] like Figure 6 As shown, in some embodiments, the electromagnetic shielding film 21 has at least a protective layer 213 with a wavy microstructure. The wavy microstructure consists of multiple undulating, curved waves; that is, the protective layer 213 corresponding to the bending region 101 is folded. In this embodiment, the multiple waves of the wavy microstructure are arranged along the direction from the non-bending region 102 to the bending region 101. It can be understood that this wavy microstructure can absorb energy when the flexible circuit board 100 unfolds during bending, alleviating stress concentration. This wavy microstructure can greatly improve the bending performance of the electromagnetic shielding film 21, thereby significantly improving the bending performance of the flexible circuit board 100 in the bending region 101, and thus increasing the dynamic bending life of the flexible circuit board 100 to ensure stable circuit connections between the electronic components of the smart glasses 1000.

[0050] In some embodiments, the layer structure of the other layers of the electromagnetic shielding film 21 and the substrate 10 in the bending region 101 can also be configured as a wavy microstructure. This significantly improves the bending performance of the flexible circuit board 100 in the bending region 101, thereby increasing the dynamic bending life of the flexible circuit board 100. For example, the second cover film 14 on the top layer of the substrate 10 can be configured with a wavy microstructure, such as the protective layer 213.

[0051] like Figure 7 As shown, in some embodiments, at least the protective layer 213 is provided with a honeycomb microstructure. In some embodiments, the honeycomb microstructure has multiple perforations; specifically, the honeycomb structure is constructed from multiple hexagons. Compared to a solid structure, it can deform and unfold to absorb energy when bent while ensuring stability, thus improving the flexibility of the electromagnetic shielding film 21. This significantly improves the flexibility of the flexible circuit board 100 in the bending region 101, thereby increasing the dynamic bending life of the flexible circuit board 100 and ensuring stable circuit connections between the electronic components of the smart glasses 1000.

[0052] In some embodiments, the layer structure of the other layers of the electromagnetic shielding film 21 and the substrate 10 in the bending region 101 can also be configured as a honeycomb microstructure. This significantly improves the flexibility of the flexible circuit board 100 in the bending region 101, thereby increasing the dynamic bending life of the flexible circuit board 100. For example, the second cover film 14 on the top layer of the substrate 10 can be configured with a honeycomb microstructure, such as the protective layer 213.

[0053] like Figure 4 As shown, in some embodiments, the first substrate layer 211 and the conductive layer 212 are configured as a conductive polymer composite film. Such an electromagnetic shielding film 21 combines conductivity and flexibility, so as to improve the bending performance of the bending region 101 while ensuring conductivity, thereby improving the dynamic bending life of the flexible circuit board 100.

[0054] For example, the sheet resistance of the electromagnetic shielding film 21 is less than 0.1 Ω / sq. This allows the electromagnetic shielding film 21 to have better conductivity.

[0055] For example, the elongation at break of the electromagnetic shielding film 21 is greater than 50%. This allows the electromagnetic shielding film 21 to have better ductility.

[0056] In some embodiments, the conductive layer 212 is configured as either a nano-metal layer or a graphene-metal composite layer. Compared to a traditional copper foil layer, the nano-metal layer possesses conductivity and nanoscale ductility. The graphene-metal composite layer, in addition to its conductivity, exhibits increased flexibility due to the addition of graphene.

[0057] For example, the nanometal layer is a silver nanowire layer. The silver nanowire layer is conductive and also has nanoscale ductility. In a specific process, conductive areas can be etched on the surface of the first substrate layer 211 using an ultraviolet laser to achieve high-precision ground line patterning, with a line width or spacing of no more than 20 μm. Then, the silver nanowire layer is deposited on the surface of the first substrate layer 211 by sputtering silver. Compared with a copper foil layer, the silver nanowire layer is more resistant to crack propagation, giving the flexible circuit board 100 higher dynamic bending performance.

[0058] For example, the nanometal layer is a copper nanowire layer. The copper nanowire layer is conductive and also has nanoscale ductility. In a specific process, conductive areas are etched on the surface of the first substrate layer 211 using an ultraviolet laser to achieve high-precision ground line patterning, with line width or spacing not exceeding 20 μm. Then, copper nanowire layer is deposited on the surface of the first substrate layer 211 by sputtering copper. Compared with copper foil layers, copper nanowire layers are more resistant to crack propagation, giving the flexible circuit board 100 higher dynamic bending performance.

[0059] For example, the conductive layer 212 is a composite layer of graphene and copper. Compared to the copper foil layer, the conductive layer 212 also incorporates graphene to enhance its flexibility, thereby improving the dynamic bending performance of the flexible circuit board 100.

[0060] In some embodiments, the first substrate layer 211 is a PI polyimide layer. This first substrate layer 211 has excellent mechanical and insulating properties, so that the conductive layer 212 can be stably disposed on the first substrate layer 211.

[0061] In some embodiments, the protective layer 213 is a friction-resistant coating that can provide better mechanical protection for the first substrate layer 211 and the conductive layer 212.

[0062] For example, the protective layer 213 is a diamond-like carbon film protective layer. This material provides excellent mechanical protection.

[0063] In other examples, the protective layer 213 is a thermoplastic polyurethane protective layer. This material provides a degree of elasticity, which can improve the dynamic bending performance of the flexible circuit board 100.

[0064] In some embodiments, the electromagnetic shielding film 21 further includes an adhesive layer 214, and the protective layer 213 is bonded to the first substrate layer 211 and the conductive layer 212 through the adhesive layer 214, so that the protective layer 213 can stably protect the first substrate layer 211 and the conductive layer 212. Exemplarily, the adhesive layer 214 is a silicone-based conductive adhesive.

[0065] like Figure 5As shown, in some embodiments, the ground layer 20 further includes a first copper foil layer 22, which is disposed in the non-bending region 102 and electrically connected to the conductive layer 212. It should be noted that the first copper foil layer 22 is also disposed on a substrate layer; for example, the substrate layer can be a PI polyimide layer. The first copper foil layer 22 is disposed on the surface of the substrate layer opposite to the substrate 10 by etching copper foil. Disposing of the first copper foil layer 22 in the non-bending region 102 does not affect the dynamic bending performance of the flexible circuit board 100, and compared to disposing of the electromagnetic shielding film 21, it can reduce costs and has stable conductivity.

[0066] In some embodiments, the conductive layer 212 and the first copper foil layer 22 are bonded together with conductive adhesive. Since the conductive layer 212 and the first copper foil layer 22 have different structures and materials, an electrical connection between them is required to ensure the overall electrical conductivity of the flexible circuit board 100. Connecting the conductive layer 212 and the first copper foil layer 22 with conductive adhesive achieves this electrical connection. Furthermore, the conductive adhesive possesses a certain degree of elasticity, allowing for some extensibility in the connection between the electromagnetic shielding film 21 of the ground layer 20 and the first copper foil layer 22, which is beneficial for improving the overall dynamic bending performance of the flexible circuit board 100.

[0067] In some embodiments, the conductive layer 212 and the first copper foil layer 22 are connected by thermoplastic adhesive. Connecting the conductive layer 212 and the first copper foil layer 22 by thermoplastic adhesive enables a stable electrical connection between them.

[0068] like Figure 5 As shown, in some embodiments, the ground layer 20 further includes a first cover film 24, which covers the side of the first copper foil layer 22 facing away from the substrate 10. The first cover film 24 serves to protect the first copper foil layer 22. Since the electromagnetic shielding film 21 already has a protective layer 213, the first cover film 24 does not need to cover the electromagnetic shielding film 21 again, which can reduce the thickness of the flexible circuit board 100 at the location where the electromagnetic shielding film 21 is provided. Therefore, the thickness of the flexible circuit board 100 in the bending region 101 can be significantly reduced, thereby improving the dynamic bending life of the flexible circuit board 100.

[0069] The first covering film 24 forms a first opening at least in the bending region 101. The width of the first opening may be greater than the width of the bending region 101, or it may be equal to or less than the width of the bending region 101. Preferably, as shown... Figure 5As shown, in some embodiments, the first cover film 24 forms a first opening at least in the bending area 101, and the width of the first opening is 0.5mm-1.0mm wider than the width of the bending area 101. It can be understood that since the first cover film 24 covers the first copper foil layer 22, the first opening formed by the first cover film 24 is also the location of the electromagnetic shielding film 21. In this embodiment, the width of the first opening is the width from the non-bending area 102 to the bending area 101 of the flexible circuit board 100, that is, the distance along the length of the flexible circuit board 100. The width of the first opening is greater than the width of the bending area 101. On the one hand, the first cover film 24 leaves sufficient area for the electromagnetic shielding film 21, allowing the electromagnetic shielding film 21 to cover the bending area 101, thereby improving the flexibility of the bending area 101. On the other hand, in some embodiments, the electromagnetic shielding film 21 can extend to the non-bending area 102, optimizing the transition between the bending area 101 and the non-bending area 102, further improving the bending performance of the flexible circuit board 100. Along the length of the flexible circuit board 100, the area of ​​the first opening covers the area of ​​the bending region 101. Specifically, the starting point of the first opening may coincide with the starting point of the bending region 101, or the ending point of the first opening may coincide with the ending point of the bending region 101, or the bending region 101 may be completely located inside the area of ​​the first opening. By limiting the width of the first opening, the electromagnetic shielding film 21 can be reduced as much as possible in the ground layer 20, so that the first copper foil layer 22 can be used as the ground layer 20 as much as possible in the non-bending region 102, saving costs and improving electrical performance.

[0070] As an example, but not a limitation, the width of the first opening is greater than the width of the bending area 101 by 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, or any combination of two values.

[0071] like Figure 8 As shown, in some embodiments, the substrate 10 includes at least one functional layer and at least one adhesive layer 13. The adhesive layer 13 is used to bond adjacent functional layers and ground layers 20 in the non-bending area 102. It is understood that when the substrate 10 includes multiple functional layers, the adhesive layer 13 can also be used to bond adjacent functional layers. The functional layers have specific functions; for example, the functional layers can be signal layers 11 and / or charging layers 12. The adhesive layer 13 is used to fix and connect adjacent functional layers and ground layers 20, enabling the flexible circuit board 100 to be stably connected as a whole.

[0072] In some embodiments, adjacent functional layers and ground layers 20 are separated in the bending region 101. It is understood that in the bending region 101, the functional layers and ground layers 20 are not connected by adhesive layers 13, and when the substrate 10 includes multiple functional layers, adjacent functional layers are not connected by adhesive layers 13. This allows for better stress distribution when the flexible circuit board 100 is bent, reducing the risk of breakage and improving the dynamic bending life of the flexible circuit board 100.

[0073] For example, in the bending area 101 of the flexible circuit board 100, there may be a gap between adjacent functional layers and ground layers 20, and the bonding is achieved only through the adhesive layer 13 in the non-bending area 102, while the bending area 101 is not bonded by the adhesive layer 13.

[0074] In other examples, at the bending area 101 of the flexible circuit board 100, adjacent functional layers and ground layers 20 can also be pressed together to further reduce the thickness of the bending area 101 and improve the flexibility of the flexible circuit board 100 in the bending area 101.

[0075] In some embodiments, the thickness of the adhesive layer 13 is 10μm-20μm. This thickness of adhesive layer 13 can ensure a stable connection between adjacent functional layers and ground layer 20, while also avoiding excessive thickness to prevent delamination risk.

[0076] For example, but not limitingly, the thickness of adhesive layer 13 is 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm or any range of two values.

[0077] like Figure 10 As shown, in some embodiments, the functional layer includes a signal layer 11 for transmitting signals, and the signal layer 11 has serpentine signal lines. In some embodiments, the signal transmission device 112 of the signal layer 11 can be a copper foil etched on the second substrate layer 111, conductive ink printed circuits, or circuits formed by conductive nanotubes, etc., which can be used to transmit signals to facilitate electrical connections between the various electronic devices of the smart glasses 1000. The serpentine signal lines can enhance the ductility of the signal layer 11 and reduce the risk of breakage of the signal layer 11 due to bending of the flexible circuit board 100. This further improves the stable circuit connection between the electronic devices of the smart glasses 1000. Specifically, the signal lines can extend in a serpentine shape in the thickness direction of the flexible circuit board 100 or in a serpentine shape in the width direction of the flexible circuit board 100.

[0078] For example, signal layer 11 has serpentine signal lines at least in the bending region 101. Since the flexible circuit board 100 bends frequently and with a large amplitude in the bending region 101, the serpentine signal lines further improve the flexibility of the flexible circuit board 100 in the bending region. It is understood that, as needed, serpentine signal lines can also be provided in the non-bending region 102, without limitation.

[0079] like Figure 8 As shown, in some embodiments, the substrate 10 further includes a second cover film 14, which is disposed on the top layer of the flexible circuit board 100. The second cover film 14 serves to protect the substrate 10.

[0080] In some embodiments, the flexible circuit board 100 further includes a reinforcing sheet disposed in the non-bending region 102. The reinforcing sheet can improve the strength of the non-bending region 102, thereby improving the load-bearing capacity of the bending region 101 of the flexible circuit board 100 and increasing the dynamic bending life of the flexible circuit board 100.

[0081] For example, the reinforcing sheet is a polyimide (PI) film reinforcing sheet or a stainless steel sheet. This application does not limit the material of the reinforcing sheet; any reinforcing sheet that can be used to reinforce the non-bending area 102 can be used in this application.

[0082] like Figure 8 As shown, in some embodiments, the substrate 10 of the flexible circuit board 100 is provided with a functional layer. Specifically, the substrate 10 includes a signal layer 11, and a second cover film 14 covers the surface of the signal layer 11 away from the ground layer 20 through a second adhesive layer 15. The ground layer 20 includes an electromagnetic shielding film 21, a third substrate layer 23, a first copper foil layer 22, and a first cover film 24. The electromagnetic shielding film 21 is disposed in the bending region 101, and the third substrate layer 23, the first copper foil layer 22, and the first cover film 24 are disposed in the non-bending region 102. The third substrate layer 23 is bonded to the signal layer 11 through an adhesive layer 13, the first copper foil layer 22 is disposed on the surface of the third substrate layer 23 away from the substrate 10, and the first cover film 24 covers the surface of the first copper foil layer 22 away from the third substrate layer 23 through a third adhesive layer 25.

[0083] like Figure 9As shown, in some embodiments, the substrate 10 of the flexible circuit board 100 is provided with two functional layers. Specifically, the substrate 10 includes two signal layers 11, adjacent signal layers 11 are bonded together by an adhesive layer 13, and a second cover film 14 is located on the top layer of the flexible circuit board 100 and covers the surface of the signal layers 11 away from the ground layer 20 by a second adhesive layer 15. The ground layer 20 includes an electromagnetic shielding film 21, a third substrate layer 23, a first copper foil layer 22, and a first cover film 24. The electromagnetic shielding film 21 is disposed in the bending area 101, the third substrate layer 23, the first copper foil layer 22, and the first cover film 24 are disposed in the non-bending area 102, the third substrate layer 23 is bonded to the signal layer 11 by the adhesive layer 13, the first copper foil layer 22 is disposed on the surface of the third substrate layer 23 away from the substrate 10, and the first cover film 24 covers the surface of the first copper foil layer 22 away from the third substrate layer 23 by a third adhesive layer 25.

[0084] In this application, the flexible circuit board 100 may also be provided with more functional layers as described above, and the functional layers are not limited to the signal layer 11, but may also be the charging layer 12, without limitation.

[0085] In some embodiments, the layers of the flexible circuit board 100 are connected by a vacuum lamination process to ensure that there are no air bubbles remaining in the flexible circuit board 100 and to ensure the stability of the flexible circuit board 100 structure.

[0086] like Figure 2 As shown, in some embodiments, the dynamic bending radius of the flexible circuit board 100 is not less than 3-5 times the thickness of the flexible circuit board 100. This ensures that the flexible circuit board 100 has a sufficient dynamic bending radius to allow it to rotate relative to the frame 200 as the temple 300 rotates. It should be noted that the thickness of the flexible circuit board 100 mentioned here refers to its maximum thickness; for example, the thickness of the flexible circuit board 100 is the distance between the surface of the second cover film 14 and the surface of the first cover film 24. The dynamic bending radius of the flexible circuit board 100 is the radius of the curved surface formed by the electromagnetic shielding film 21 in the bending area away from the surface of the substrate 10 when the flexible circuit board 100 bends.

[0087] The dynamic bending radius of the flexible circuit board 100 can be 3 times, 3.5 times, 4 times, or 5 times the thickness of the flexible circuit board 100. For example, if the thickness of the flexible circuit board 100 is 0.1 mm, the dynamic bending radius of the flexible circuit board 100 is not less than 0.3 mm. In some embodiments, the bending region 101 of the flexible circuit board 100 has a rounded transition during bending. This avoids right-angle bending of the flexible circuit board 100, reduces stress concentration, and improves the dynamic bending life of the flexible circuit board 100.

[0088] For example, the radius of the bending area 101 of the flexible circuit board 100 when bending is not less than 1.0mm. In this way, the bending area 101 can have a large bending arc, avoiding the flexible circuit board 100 from bending at a right angle due to too small a bending arc.

[0089] In some embodiments, the frame 200 and temple 300 are rotatably connected by a hinge structure. The hinge structure includes a rotating column and a rotating member. The rotating column is located on the frame 200, and the rotating member is located on the front end of the temple 300 facing the frame 200, surrounding the rotating column. One end of the flexible circuit board 100 is connected to the temple 300, and the other end is connected to the frame 200. The temple 300 rotates relative to the frame 200. As the rotating member rotates, the bending area 101 of the flexible circuit board 100 bends or straightens. Providing an electromagnetic shielding film 21 in the bending area 101 can effectively improve the bending life of the flexible circuit board 100.

[0090] like Figure 1 and Figure 2 As shown, in some embodiments, the flexible circuit board 100 includes a charging layer 12 disposed on the temple 300, with the charging layer 12 located on the side of the flexible circuit board away from the other temple 300. The charging layer 12 can connect to a battery and a charging interface to charge the battery through the charging interface. It is understood that when a user wears the smart glasses 1000, the charging layer 12 is located on the outer side of the flexible circuit board 100 away from the user's head, so that the charging layer 12 can connect to the charging interface located on the outer side.

[0091] In some embodiments, the charging interface is located on the rotating part of the temple 300. The charging layer 12 and the flexible circuit board 100 are layered at the rotating part, with the layered portion of the charging layer 12 extending along the rotating part and connecting to the charging interface. It can be understood that the charging interface, charging layer 12, and battery compartment assembly are all located on the same temple 300, and the charging layer 12 is not located in the bending area. This allows the charging assembly to be completely located on a single temple 300, thus facilitating adaptation to different frames 200 and ensuring the reliability of the flexible circuit board 100 during bending.

[0092] In some embodiments, when the smart glasses 1000 is in a folded state, the charging port is at least partially exposed to the external environment; when the smart glasses 1000 is in an unfolded state, the charging port has a smaller exposed area or is not exposed to the external environment compared to the folded state. When the smart glasses 1000 is in the unfolded state, the user can wear them. In this state, the charging port is essentially not exposed to the external environment, thus preventing corrosion of the charging port during wear and reducing its lifespan, ensuring the normal charging function of the smart glasses 1000. When the smart glasses 1000 is in a folded state, the charging port is exposed to the external environment, allowing the smart glasses 1000 to be charged while being stored.

[0093] In this application, the charging layer can be set according to the location of the charging interface. Specifically, if the charging interface is set only at one temple 300, then only the charging layer 12 needs to be set on the flexible circuit board 100 of the corresponding temple 300; if the charging interface is set at both temples 300, then the charging layer 12 needs to be set on the flexible circuit board 100 in both temples 300.

[0094] The above description is merely a preferred embodiment of this application and does not limit the patent scope of this application. Any equivalent structural transformations made based on the content of this application's specification and drawings under the concept of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A flexible circuit board for use in smart glasses, characterized in that, The flexible circuit board has a bending region and a non-bending region; the flexible circuit board includes: Matrix; A ground layer, the ground layer including an electromagnetic shielding film, the electromagnetic shielding film at least covering the bending area; The electromagnetic shielding film includes a first substrate layer, a conductive layer, and a protective layer. The first substrate layer is connected to the substrate, the conductive layer is disposed on the surface of the first substrate layer away from the substrate, and the protective layer covers the side of the conductive layer away from the first substrate layer.

2. The flexible circuit board as described in claim 1, characterized in that, The thickness of the electromagnetic shielding film is 20μm-50μm.

3. The flexible circuit board as described in claim 1, characterized in that, At least the protective layer has a wavy microstructure, and / or at least the protective layer has a honeycomb microstructure.

4. The flexible circuit board as described in claim 1, characterized in that, The first substrate layer and the conductive layer are configured as a conductive polymer composite film; and / or, the conductive layer is configured as a nano-metal layer or a composite layer of graphene and metal.

5. The flexible circuit board as described in claim 1, characterized in that, The ground layer also includes a first copper foil layer, which is disposed in the non-bending area and electrically connected to the conductive layer.

6. The flexible circuit board as described in claim 5, characterized in that, The conductive layer is bonded to the first copper foil layer with conductive adhesive. Alternatively, the conductive layer is bonded to the first copper foil layer via thermoplastic adhesive.

7. The flexible circuit board as described in claim 5, characterized in that, The ground layer further includes a first cover film, which covers the side of the first copper foil layer opposite to the substrate. The first cover film forms a first opening at least in the bending area, and the width of the first opening is 0.5 mm to 1.0 mm greater than the width of the bending area.

8. The flexible circuit board as described in claim 1, characterized in that, The substrate includes at least one functional layer and at least one adhesive layer, the adhesive layer being used to bond adjacent functional layers and the ground layer in the non-bending area.

9. The flexible circuit board as described in claim 8, characterized in that, In the bending area, the adjacent functional layers and the ground layer are arranged in layers.

10. The flexible circuit board as described in claim 8, characterized in that, The thickness of the adhesive layer is 10μm-20μm.

11. The flexible circuit board as described in claim 1, characterized in that, The substrate includes at least one functional layer, the functional layer including a signal layer for transmitting signals, and the signal layer having serpentine signal lines.

12. The flexible circuit board as described in claim 1, characterized in that, The flexible circuit board also includes a reinforcing sheet, which is disposed in the non-bending area.

13. The flexible circuit board as described in claim 1, characterized in that, The dynamic bending radius of the flexible circuit board is not less than 3-5 times the thickness of the flexible circuit board.

14. A type of smart glasses, characterized in that, Includes the frame, temples, and the flexible circuit board as described in any one of claims 1 to 13; The frame and temples are hinged together, the flexible circuit board passes through the frame and temples, the bending area is located inside the frame, and the non-bending areas are located inside the frame and temples respectively, for connecting electronic devices.

15. The smart glasses as described in claim 14, characterized in that, The flexible circuit board includes a charging layer disposed on the temple of the eyeglass, and the charging layer is located on the side of the flexible circuit board away from the other temple.

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