Foldable device

Abstract

Disclosed in the present application is a foldable device. The foldable device comprises a first main body, a second main body and a rotating shaft, the first main body and the second main body being connected to each other by means of the rotating shaft. The foldable device can be folded at the position of the rotating shaft. The first main body comprises a first middle frame and a first main board, and the second main body comprises a second middle frame and a second main board. The first main board is fixedly connected to the first middle frame, and the second main board is fixedly connected to the second middle frame. A ground end of the first main board is connected to the first middle frame, and a ground end of the second main board is connected to the second middle frame. The foldable device comprises a first flexible printed circuit (FPC) and a second FPC. The first FPC passes through the rotating shaft to connect the first main board and the second main board, and the second FPC passes through the rotating shaft to connect the ground end of the first main body and the ground end of the second main body. In the embodiments of the present application, providing a return path can reduce the ground return impedance between the different main bodies, reduce overall heat loss, and ensure that battery power is fully discharged.

Description

Foldable device

[0001] The present application claims priority to the Chinese patent application No. 202410745075.6, filed on June 7, 2024, and entitled "Foldable device", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of terminals, and in particular to a foldable device. BACKGROUND

[0003] The foldable device includes at least one rotating shaft and two main bodies, and the two main bodies are connected by the rotating shaft. At least one main board is included in the two main bodies. In order to enable the foldable device to operate normally, the different main boards need to be electrically connected to transmit electrical signals, provide power supply, and complete the whole machine grounding return flow. When the two main boards to be connected are in different main bodies, the connection of the two main boards needs to pass through the rotating shaft. By means of the characteristics of flexible circuit that can be bent and strong flexibility, the flexible circuit board can be used for connection at the rotating shaft.

[0004] However, due to the limited space at the rotating shaft, the thickness of the flexible circuit board is limited, so the whole machine grounding return flow path is greatly limited, the impedance is large, and the battery power cannot be fully released. In addition, if the thickness of the flexible circuit board is increased, the thickness of the whole machine will also be increased, which will affect the use and design of the whole machine. SUMMARY

[0005] The embodiments of the present application disclose a foldable device, which can increase the return flow path of the whole machine, reduce the return flow impedance between different main bodies, reduce the heat loss of the whole machine, and ensure that the battery power is fully released.

[0006] In a first aspect, the present application provides a foldable device, wherein: the foldable device includes a first main body, a second main body, and a rotating shaft, the first main body and the second main body are connected by the rotating shaft, and the foldable device can be folded at the rotating shaft; the first main body includes a first middle frame and a first main board, and the second main body includes a second middle frame and a second main board; the first main board is fixed to the first middle frame; the second main board is fixed to the second middle frame; a grounding end of the first main board is electrically connected to the first middle frame; a grounding end of the second main board is electrically connected to the second middle frame; the foldable device includes a first flexible circuit board (FPC) and a second FPC; the first FPC connects the first main board and the second main board through the rotating shaft; and the second FPC connects the grounding end of the first main body and the grounding end of the second main body through the rotating shaft.

[0007] The first main plate is fixed with the first middle frame; the second main plate is fixed with the second middle frame, which means that the first main plate is mechanically fixed with the first middle frame, and the second main plate is mechanically fixed with the second middle frame. The ground terminal of the first main plate is electrically connected to the first middle frame; the ground terminal of the second main plate is electrically connected to the second middle frame. The ground terminal (i.e. GND) of the main plate of the same main body is electrically connected to the middle frame, without limiting the pin position of the ground terminal and the connection mode.

[0008] In the embodiments of the present application, the second FPC is used to connect the ground terminal of the first main body and the ground terminal of the second main body, thereby increasing the backflow path of the whole machine, reducing the ground backflow impedance between different main bodies, reducing the heat loss of the whole machine, and ensuring the full release of the battery power.

[0009] In a possible implementation, one end of the second FPC is connected to the ground terminal of the first middle frame or the main plate in the first main body; the other end of the second FPC is connected to the ground terminal of the second middle frame or the main plate in the second main body. In this way, the second FPC is used to connect the ground terminal of the first main body and the ground terminal of the second main body, thereby increasing the backflow path of the whole machine, reducing the ground backflow impedance between different main bodies, reducing the heat loss of the whole machine, and ensuring the full release of the battery power.

[0010] In a possible implementation, the first main body further includes a third main plate; the second main body further includes a fourth main plate, the third main plate is fixed with the first middle frame; the fourth main plate is fixed with the second middle frame, the ground terminal of the third main plate is electrically connected to the first middle frame; the ground terminal of the fourth main plate is electrically connected to the second middle frame; the first main body ground terminal includes at least one of the ground terminal of the first main plate, the ground terminal of the third main plate and the first middle frame; the second main body ground terminal includes at least one of the ground terminal of the second main plate, the ground terminal of the fourth main plate and the second middle frame. In this way, the ground terminal of each main plate is connected to the corresponding middle frame, the middle frame can communicate the ground terminals of all main plates, the number of wires required for the communication of the ground terminals of different main plates in the same main body is reduced, the middle frame has large volume and low impedance, the second FPC increases the ground backflow path of the whole machine, the ground backflow impedance of the whole machine is lower, the heat loss is reduced, and the battery power is fully released.

[0011] In a possible implementation, the second FPC passes through the rotating shaft to connect the ground terminal of the first main body and the ground terminal of the second main body, including that the second FPC passes through the rotating shaft to connect the first middle frame and the second middle frame. In this way, the two ends of the second FPC can be directly connected to the middle frame, the length of the second FPC can be reduced, the number of interfaces of the main plate can be reduced, and the wiring design space is optimized. Similarly, the ground backflow path of the whole machine is increased, the ground backflow impedance of the whole machine is lower, the heat loss is reduced, and the battery power is fully released.

[0012] In a possible implementation, the first mainboard is fixed with the first middle frame; the ground end of the first mainboard is electrically connected with the first middle frame, including: the first mainboard is electrically connected with the first middle frame through a first connecting piece; the first connecting piece is electrically connected with the ground end of the first mainboard; the first connecting piece fixes the first mainboard and the first middle frame, and the first connecting piece is a first screw or a first bolt; the second mainboard is fixed with the second middle frame; the ground end of the second mainboard is electrically connected with the second middle frame, including: the second mainboard is electrically connected with the second middle frame through a second connecting piece; the second connecting piece is electrically connected with the ground end of the second mainboard; the second connecting piece fixes the second mainboard and the second middle frame, and the second connecting piece is a second screw or a second bolt. In this way, by means of the conductive function of the screw and the bolt and the fixed connection of the mainboard and the middle frame, the ground end of each mainboard is connected with the corresponding middle frame by connecting the ground end of the mainboard with the screw or the bolt, and the number of wires required for the communication of the ground ends of different mainboards in the same main body can be reduced. Further, the middle frame has large volume and low impedance, and can more fully meet the impedance requirement of the whole machine reflow, reduce heat loss, and ensure sufficient release of battery power.

[0013] In a possible implementation, the first mainboard is fixed with the first middle frame, including: the first mainboard is fixed with the first middle frame by welding, a screw or a bolt; the ground end of the first mainboard is electrically connected with the first middle frame, including: the ground end of the first mainboard is electrically connected with the first middle frame through a spring sheet and / or a wire; the second mainboard is fixed with the second middle frame, including: the second mainboard is fixed with the second middle frame by welding, a screw or a bolt; the ground end of the second mainboard is electrically connected with the second middle frame, including: the ground end of the second mainboard is electrically connected with the second middle frame through a spring sheet and / or a wire. In this way, welding, a screw or a bolt can be used to fix the mechanical structure between the mainboard and the middle frame, and the mainboard ground end is connected with the middle frame through a wire or a spring sheet, so as to ensure the impedance of the whole machine reflow, reduce heat loss, and ensure sufficient release of battery power.

[0014] In a possible implementation, the first FPC includes a power line and a data control line; the data control line includes a camera line and a screen signal line. In this way, the first FPC can complete the transmission of power, camera signal and screen signal.

[0015] In a possible implementation, the first FPC includes a ground wire. In this way, the whole machine can include at least two backflow paths of the FPC, the impedance of the ground backflow between different main bodies can be reduced, the heat loss can be reduced, and the battery capacity can be fully released. In addition, the ground wire can directly backflow through the second FPC, share the thickness of the first FPC, and can reduce the space occupation in the thickness direction of the battery as a whole, and increase the battery capacity. The FPC thickness is reduced, the bending radius of the through shaft is reduced, and the overall bending life of the FPC is improved.

[0016] In a possible implementation, the first FPC does not include a ground wire.

[0017] In a possible implementation, when the second FPC further includes an antenna signal trace, the antenna signal trace is connected to the first main board and the fourth main board. In this way, when the second FPC further includes an antenna signal trace, the antenna signal needs to be transmitted to the main board, so that the design flexibility and the realizability of the scheme are ensured.

[0018] In a possible implementation, the first FPC is two layers or one layer of traces. In this way, the number of FPC layers is reduced, the overall FPC thickness is reduced, the through shaft FPC bending radius is increased to improve the FPC board life, the space occupation in the thickness direction of the whole machine is reduced, and the battery space can be optimized.

[0019] In a possible implementation, the second FPC is two layers or one layer of traces. In this way, the number of FPC layers is reduced, the overall FPC thickness is reduced, the through shaft FPC bending radius is increased to improve the FPC board life, the space occupation in the thickness direction of the whole machine is reduced, and the battery space can be optimized.

[0020] In a possible implementation, the first FPC is three layers or more than three layers.

[0021] In a possible implementation, the second FPC is three layers or more than three layers.

[0022] In a possible implementation, the rotating shaft includes a first rotating component, a second rotating component, and a third rotating component; the second rotating component is between the first rotating component and the third rotating component; a first rotating shaft gap is between the first rotating component and the second rotating component; a second rotating shaft gap is between the second rotating component and the third rotating component; and the first rotating component, the second rotating component, and the third rotating component of the rotating shaft are used to movably connect the first middle frame and the second middle frame. In this way, the rotating shaft gap space in the multiple rotating components is limited, the number of FPCs is increased to reduce the thickness of the FPCs by means of the wire passing through the rotating shaft, the FPC bending life is improved, the space occupied in the thickness direction of the whole machine is reduced, and the battery space is also optimized.

[0023] In a possible implementation, the first body further includes a first battery, and the second body further includes a second battery; the first battery is fixed on one side of the first middle frame; and the second battery is fixed on one side of the second middle frame. In this way, the middle frame, the battery, and the FPC are stacked in the thickness direction of the foldable device, the increase in the number of FPC layers leads to a decrease in the thickness of the battery and a decrease in the capacity of the battery. The introduction of the second FPC reduces the overall thickness of the FPC passing through the rotating shaft, reduces the space occupied in the thickness direction of the whole machine, and increases the thickness of the battery and the capacity of the battery.

[0024] In a possible implementation, the first body includes a first battery; the second body further includes a second battery; the first battery is fixed on the first middle frame; and the second battery is fixed on the second middle frame. In this way, the middle frame, the battery, and the FPC are stacked in the thickness direction of the foldable device, the increase in the number of FPC layers leads to a decrease in the thickness of the battery and a decrease in the capacity of the battery. The introduction of the second FPC reduces the overall thickness of the FPC passing through the rotating shaft, reduces the space occupied in the thickness direction of the whole machine, and increases the thickness of the battery and the capacity of the battery.

[0025] In a second aspect, the present application provides a circuit reflow system, which includes any one of the foldable devices in the first aspect. BRIEF DESCRIPTION OF DRAWINGS

[0026] FIG. 1 is a schematic structural diagram of a foldable device in a folded state according to an embodiment of the present application;

[0027] FIG. 2 is a schematic diagram of an unfolded structure of a foldable device according to an embodiment of the present application;

[0028] FIG. 3 is a schematic diagram of a spatial structure of a foldable device according to an embodiment of the present application;

[0029] FIG. 4 is a schematic diagram of a split structure of a foldable device according to an embodiment of the present application;

[0030] FIG. 5 is a schematic diagram of a cross-sectional structure of a foldable device according to an embodiment of the present application;

[0031] FIG. 6 is a schematic diagram of a cross-sectional structure of a foldable device according to an embodiment of the present application;

[0032] FIG. 7 is a schematic diagram of a cross-sectional structure of an FPC in a foldable device according to an embodiment of the present application;

[0033] FIG. 8 is a schematic diagram of a split structure of a foldable device according to an embodiment of the present application;

[0034] FIG. 9 is a schematic diagram of a structure in which a ground wire of a first mainboard is connected to a first middle frame by a screw according to an embodiment of the present application;

[0035] FIG. 10 is a schematic diagram of a split structure of a foldable device according to an embodiment of the present application;

[0036] FIG. 11 is a schematic diagram of a cross-sectional structure of a first flexible circuit board and a second flexible circuit board according to an embodiment of the present application;

[0037] FIG. 12 is a schematic diagram of a split structure of another foldable device according to an embodiment of the present application;

[0038] FIG. 13 is a schematic diagram of a cross-sectional structure of a second flexible circuit board according to an embodiment of the present application. DETAILED DESCRIPTION

[0039] In the embodiments of the present application, the terms "first", "second", and the like are used to distinguish between items or components that have substantially the same function and effect. For example, the first chip and the second chip are merely used to distinguish between different chips, and do not limit the order of execution. Those skilled in the art can understand that the terms "first", "second", and the like do not limit the number and execution order, and the terms "first", "second", and the like do not necessarily mean different.

[0040] It should be noted that in the embodiments of the present application, the words "exemplary" or "for example" are used to mean "an example of" or "an example, not necessarily the only example" of something. Any embodiment or design solution described as "exemplary" or "for example" in the present application should not be construed as preferred or advantageous over other embodiments or design solutions. Rather, use of "exemplary" or "for example" is intended to present concepts in a concrete manner.

[0041] The embodiments of the present application provide a foldable device, which increases the backflow path, reduces the backflow impedance between different main bodies, reduces the heat loss of the whole machine, and ensures sufficient release of battery power.

[0042] In order to facilitate the understanding of the scheme of the embodiments of the present application, the structure of the foldable device is introduced as follows:

[0043] FIG. 1 is a schematic diagram of a folded state structure of a foldable device disclosed exemplarily by the embodiments of the present application. As shown in FIG. 1, the foldable device is in a completely folded state or a nearly completely folded state. FIG. 2 is a schematic diagram of an unfolded state structure of a foldable device disclosed exemplarily by the embodiments of the present application. As shown in FIG. 2, the foldable device is in a completely unfolded state or a nearly completely unfolded state. FIG. 3 is a schematic diagram of a space structure of a foldable device disclosed exemplarily by the embodiments of the present application.

[0044] For the convenience of description, the width direction of the foldable device 100 is defined as the X direction, the length direction of the foldable device 100 is defined as the Y direction, and the thickness direction of the foldable device 100 is defined as the Z direction. The X direction, the Y direction and the Z direction are perpendicular to each other.

[0045] The foldable device 100 includes, but is not limited to, a cell phone, a notebook computer, a tablet personal computer, a laptop computer, a personal digital assistant, a wearable device or a mobile device, etc. In the embodiments of the present application, the foldable device 100 is taken as a cell phone for example.

[0046] As shown in FIG. 1 and FIG. 2, the foldable device 100 can include a first main body 110, a second main body 120 and a rotating shaft 130. The rotating shaft 130 is located between the first main body 110 and the second main body 120, that is, the first main body 110 and the second main body 120 are rotationally connected through the rotating shaft 130, so that the first main body 110 and the second main body 120 are folded and unfolded.

[0047] In FIG. 1, the first body 110 and the second body 120 rotate in directions away from each other about the rotation shaft 130, that is, the first body 110 rotates in the direction of 11a, and the second body 120 rotates in the direction of 11b. When the first body 110 and the second body 120 rotate to the position farthest apart, as shown in FIG. 2, the foldable device is in a fully unfolded state or a near fully unfolded state.

[0048] In FIG. 2, the first body 110 and the second body 120 rotate in directions close to each other about the rotation shaft 130, that is, the first body 110 rotates in the direction of 22a, and the second body 120 rotates in the direction of 22b. When the first body 110 and the second body 120 rotate to the position closest, as shown in FIG. 1, the foldable device is in a fully folded state or a near fully folded state.

[0049] As shown in FIG. 2, the rotation shaft 130 can include a first rotation component 131, a second rotation component 133, and a third rotation component 135. The first rotation component 131, the second rotation component 133, and the third rotation component 135 are arranged in sequence and spaced apart along the Y direction. Among them, the second rotation component 133 is located between the first rotation component 131 and the third rotation component 135. Among them, there is a rotation shaft gap between adjacent two rotation components, that is, there is a first rotation shaft gap 132 between the first rotation component 131 and the second rotation component 133, and there is a second rotation shaft gap 134 between the second rotation component 133 and the third rotation component 135. In other embodiments, there are two, four, or more than five rotation components. The number of rotation components is not specifically limited in this application. Among them, the rotation shaft 130 can be a rotation shaft structure or a hinge structure, etc.

[0050] The foldable device 100 can further include a first middle frame 111, a second middle frame 121, a first back cover 141, a second back cover 142, and a display screen 150. The first body 110 includes the first middle frame 111, the first back cover 141, and the first part of the display screen 150; the second body 120 includes the second middle frame 121, the second back cover 142, and the second part of the display screen 150.

[0051] The first middle frame 111 and the second middle frame 121 can be used as structural bearing components of the foldable device 100. The first middle frame 111 and the second middle frame 121 can be used to mount the display screen 150, the first back cover 141, and other components. The display screen 150 can cover one side of the first middle frame 111, the second middle frame 121, and the hinge 130, the first back cover 141 covers the other side of the first middle frame 111 and the second middle frame 121, and the second back cover 142 covers the other side of the second middle frame 121. That is, along the thickness direction of the foldable device 100, the display screen 150 and the back cover are connected to the opposite sides of the middle frame, respectively. The first middle frame 111, the display screen 150, and the first back cover 141 cooperatively define a first accommodation space of the foldable device, and the second middle frame 121, the display screen 150, and the second back cover 142 cooperatively define a second accommodation space of the foldable device. The accommodation spaces can be used to accommodate electronic components such as processors, circuit boards, and batteries of the foldable device, and structural components.

[0052] As shown in FIG. 3, the foldable device 100 can exemplarily include a first battery 161, a second battery 162, a first mainboard 171, a second mainboard 172, a third mainboard 173, and a fourth mainboard 174. The first body 110 includes the first battery 161, the first mainboard 171, and the third mainboard 173, and the second body 120 includes the second battery 162, the second mainboard 172, and the fourth mainboard 174. The first accommodation space can include the first battery 161, the first mainboard 171, and the fourth mainboard 174. The first accommodation space can include the second battery 162, the third mainboard 173, and the second mainboard 172. The number, size, and position layout of the batteries and the mainboards in the first accommodation space and the second accommodation space are only exemplarily described, and the embodiments of the present application are not limited thereto.

[0053] It should be noted that in FIG. 3, in order to illustrate the structures of different modules, the modules are two-dimensionally illustrated, that is, the display screen 150, the batteries, the mainboards, the middle frames, the hinge 130, the first back cover 141, and the second back cover 142 are not specifically illustrated in the Z-axis thickness direction, but the actual specific devices have a certain thickness.

[0054] It should be noted that the structures illustrated in FIGS. 1-3 do not constitute a specific limitation on the foldable device 100. In other embodiments of the present application, the foldable device 100 can include more or fewer components than those illustrated, or combine certain components, or split certain components, or different component arrangements. For example, the foldable device 100 can further include a camera module and a flash, and the like.

[0055] In the above FIG. 1-3, the different mainboards need to be electrically connected to realize the basic functions of the foldable device 100. The mainboard in the first receiving space of the first middle frame 111 needs to be electrically connected with the mainboard in the second receiving space of the second middle frame 121. A flexible printed circuit (FPC) can be provided between the first middle frame 111 and the second middle frame 121, which can pass through the gap between the rotating shafts on both sides of the rotating assembly (or the gap between the rotating shafts of two adjacent rotating assemblies), connect the mainboards at different positions of the two middle frames, thereby transmitting power signals, completing the ground return of the whole machine, and also transmitting other signals. After the above connection, the foldable device can operate normally and realize the corresponding functions. The following describes the connection mode of the flexible circuit board passing through the gap between the rotating shafts in combination with FIG. 4-7:

[0056] FIG. 4-7 are schematic diagrams of the connection between different mainboards according to an embodiment of the present application. FIG. 4 is a split structure diagram of a foldable device in an unfolded state. FIG. 5 is a schematic diagram of the cross-sectional structure of cutting surface 1 in FIG. 4; FIG. 6 is a schematic diagram of the cross-sectional structure of cutting surface 2 in FIG. 4. FIG. 7 is a schematic diagram of the cross-sectional structure of the FPC in FIG. 4.

[0057] As shown in FIG. 4, in order to facilitate the description of the layout of the mainboards and the batteries in the first receiving space and the second receiving space, FIG. 4 takes the XOY plane as an example for illustration, and FIG. 4 includes the layout and connection relationship of each component on the XOY plane.

[0058] In combination with the layout of the mainboards and the batteries in FIG. 3, the first receiving space of the first middle frame 111 includes the first mainboard 171, the third mainboard 173, and the first battery 161. The second receiving space of the second middle frame 121 includes the second mainboard 172, the second battery 162, and the fourth mainboard 174. The descriptions of the middle frame, the receiving space, the mainboard, the battery, the rotating shaft assembly, and the gap between the rotating shafts can refer to the related contents of FIG. 3, which will not be repeated here.

[0059] As shown in FIG. 4, the middle frame is placed under the main board and the battery (at this time, the middle frame is covered and invisible), in order to fix each main board on the bottom of the middle frame, each main board needs to be fixed and connected to the middle frame by at least one screw. In FIG. 4, the screw 311, the screw 312, the screw 313, the screw 314 and the screw 315 connect the first main board 171 and the first middle frame 111. The positions of the screw 311, the screw 312, the screw 313, the screw 314 and the screw 315 can be located at five different positions of the first main board 171 respectively, to ensure the stability of the connection. Of course, the number of screws used for the connection between each main board and the middle frame can be different. The second main board 172 is connected to the first middle frame by four screws, and the third main board and the fourth main board can be connected to the middle frame by two screws respectively. The number of screws and the position of the screws for the connection between each main board and the middle frame are not limited in the present application. The connection of other main boards and the middle frame can refer to the connection method of the screws in the first main board, which will not be described in detail.

[0060] As shown in FIG. 4, the foldable device 100 can further include a flexible circuit board FPC 321, which can connect the first main board 171 and the second main board 172. Specifically, the flexible circuit board FPC 321 can pass through the first hinge gap 132, pass through one side of the second battery 162 (the FPC 321 and the side of the second battery 162 are stacked in the thickness direction of the foldable device), and connect the first main board 171 and the second main board 172. The first end of the flexible circuit board FPC 321 is connected to the first main board 171, and the second end is connected to the second main board 172. Among them, the flexible circuit board FPC 321 can include a power line, a ground line and other lines. The power line can transmit a power signal to provide a voltage. The ground line can transmit a ground signal to complete the return flow of the power signal. Other lines can transmit other signals, for example, the power line can include Vph_pwr (main power circuit), Vbus (charging circuit), Vbat (battery circuit) and the like. Other lines can include front camera wiring, microphone wiring, screen IC wiring and antenna switch signal and the like. Among them, the specific line layout of other lines is related to the overall circuit layout, which is not limited in the present application.

[0061] As shown in FIG. 4, in order to pass through the hinge, the FPC 321 needs to pass through the hinge gap, and the sizes of the first main board 171 and the second main board 172 are different. Therefore, the FPC line needs to be bent in the XOY plane to be connected. Therefore, in order to further clearly illustrate the FPC connection in FIG. 4, the line structure is illustrated on the cutting surface 1 before and after the bending, the cutting surface 2 and the FPC cross section respectively, that is, the structure in the thickness direction is illustrated by the cross-sectional views of FIGS. 5-7.

[0062] Further, in FIG. 4, the ground wires of all the mainboards need to be connected to form a signal return flow of the complete folding device 100. As shown in FIG. 4, the first mainboard 171 can be connected with the second mainboard 172 through an FPC 321; the first mainboard 171 can be connected with the third mainboard 173 through a wire 322; and the second mainboard 172 can be connected with the fourth mainboard 174 through a wire 323. The FPC 321, the wire 322 and the wire 323 can each include a ground wire, a power supply wire and other wires, and the specific wire types are related to the specific hardware layout of the device, which is not limited in the present application. The wire 323, the wire 322 and the wire 323 can also be FCBs, or other types of wires, which are not limited in the present application.

[0063] As shown in FIG. 5, on the surface of the cutting surface 1 in FIG. 4, the second battery 162 and the second mainboard 172 are placed on the same side of the second middle frame 121 and in the second receiving space.

[0064] The second mainboard 172 is connected with the second middle frame 121 through a screw. The mainboard (the second mainboard 172) includes a printed circuit board (PCB), a plurality of components and a shielding cover, etc. The plurality of components (such as chips, inductors, etc.) can be welded on the PCB, and the components are connected with each other to realize different functions. The shielding cover is also fixed on the PCB, which can shield external interference signals, reduce electromagnetic radiation, strengthen the strength of the mainboard, etc. The PCB can be fixedly connected with the second middle frame 121 through a screw, that is, one end of the screw passes through the PCB through a hole, and the other end is fixed in the second middle frame 121.

[0065] The PCB can be connected with the FPC wire through a connector, and the FPC wire is routed from one side of the second battery 162, turns through the first shaft gap 132. The connector is fixed on one side of the second mainboard 172, and one end of the connector is connected with the PCB. Alternatively, in the embodiment of the present application, the PCB can also be connected with the FPC wire through a welding manner, and the connection manner of the PCB and the FPC wire is not limited in the present application.

[0066] As shown in FIG. 6, the distribution of the battery and the screw on the plane where the cutting surface 2 in FIG. 4 is located, on the plane where the Z axis and the Y axis are located. In the first rotation shaft gap 132 area, the FPC line is bent (multiple times). As shown in FIG. 6, the rotation shaft gap is adjacent to the first main plate 171 and the second battery 162 at both ends. After the FPC trace passes through the first main plate on one side, it is fixed and bent twice, and after the hole is punched, it is bent twice again. After being fixed again, it continues to pass through the side of the second battery, and then it is connected to the second main plate 172 as shown in FIG. 5. In the above process, the foldable device can bend the FPC line multiple times in the rotation shaft area. In the case of small number of FPC layers and small thickness, the bending radius is large; in the case of large FPC thickness, the bending radius is small. One end of the FPC is connected to the first main plate 171, and after passing through the first rotation shaft gap 132, it is located on the side of the second battery 162. Then the FPC needs to be connected to the second main plate 172 after turning. For specific description, please refer to the related description of FIG. 5, which is not repeated here. During the shaft passing process, the FPC is bent, the thicker the FPC, the smaller the bending radius, and the shorter the service life of the FPC.

[0067] FIG. 7 is a cross-sectional view of the FPC. As shown in FIG. 7, the FPC line includes power lines, ground lines, and other lines 3 kinds of lines. The power line (for example, the Vbus charging path) is used for power supply; the ground line is used to complete the whole machine line return flow. Other lines can provide different main bodies between the transmission of electrical signals. The FPC line includes three layers in total, among which, due to the small impedance required by the whole machine return flow and the high requirement of the ground line signal. However, due to the rotation assembly in the rotation shaft, the space occupied by the rotation assembly is large, and the width of the rotation shaft gap is very narrow, which causes the FPC to be unable to increase the width, the FPC has more trace resources, and the number of layers of the FPC needs to be increased. The FPC is thick, occupies the space in the thickness direction of the whole machine, and is not conducive to the structure layout of the whole machine. In addition, the three-layer FPC line is about 0.162mm, the bending radius is 0.69mm, and the bending life is about 243805 times. Therefore, it is not feasible to increase the number of FPC layers to reduce the impedance.

[0068] In the foldable device of FIGS. 4-7, the whole machine reflow is completed by connecting the mainboards of the two main bodies by the FPC wiring single through shaft. The flexible circuit board FPC includes power lines, ground lines and other lines. Therefore, the ground reflow path between the two main bodies is achieved by the ground line in the flexible circuit board FPC. However, due to the limited gap space of the rotating shaft between the rotating assemblies, the electronic device cannot increase the number of flexible circuit board FPC layers to reduce the reflow impedance, so that the ground reflow impedance is large, the heat loss is serious, and the battery capacity cannot be fully released. In addition, due to the limited width of the through shaft gap in the Y-axis direction, in order to meet the requirement of the whole machine reflow impedance, the number of FPC wiring layers needs to be increased, which occupies the space of the foldable device in the thickness direction, and squeezes the space of the whole machine in the thickness direction. The battery capacity will be reduced. In addition, the increase of the number of FPC wiring layers and the increase of the thickness will also reduce the bending radius, which will introduce problems such as reliability and bending life of FPC wiring. Further, the increase of FPC wiring thickness and the reduction of bending radius increase the risk of FPC line top screen. In addition, the FPC connection between the two mainboards also needs to increase the number of pins BTB PIN. The position of FPC BTB is often in the layout core position of the mainboard, which will occupy more mainboard layout resources.

[0069] Based on the above problems, the present application provides a foldable device. The foldable device includes a first main body, a second main body and a rotating shaft, the first main body and the second main body are connected by the rotating shaft, and the foldable device can be folded at the rotating shaft; the first main body includes a first middle frame and a first mainboard, and the second main body includes a second middle frame and a second mainboard; the first mainboard is fixed to the first middle frame; the second mainboard is fixed to the second middle frame; the ground end of the first mainboard is electrically connected to the first middle frame; the ground end of the second mainboard is electrically connected to the second middle frame; the foldable device includes a first flexible circuit board FPC and a second FPC; the first FPC connects the first mainboard and the second mainboard through the rotating shaft; and the second FPC connects the ground end of the first main body and the ground end of the second main body through the rotating shaft. In this way, by means of the second FPC wiring connecting the ground end of the first main body and the second main body, and the ground end of the mainboard being connected to the middle frame of the main body, the reflow path of the through shaft FPC is increased, which can reduce the impedance of the ground reflow between different main bodies, reduce heat loss, and ensure the full release of battery capacity. In addition, the number of FPC layers on the whole machine can be reduced, the thickness of the FPC can be reduced, the bending radius of the through shaft FPC can be increased to improve the service life of the FPC board, the space occupation in the thickness direction of the whole machine can be reduced, and the battery space can be optimized.

[0070] In some embodiments, one end of the second FPC is connected to the ground end of the mainboard in the first middle frame or the first main body; and the other end of the second FPC is connected to the ground end of the mainboard in the second middle frame or the second main body.

[0071] In some embodiments, the second FPC passes through the rotating shaft to connect the first middle frame and the second middle frame.

[0072] In combination with the above technical solutions and embodiments, the application provides FIGS. 8-13 to illustrate the backflow circuit layout of the foldable device.

[0073] FIG. 8 is a split structure diagram of a foldable device in an unfolded state according to an embodiment of the application.

[0074] The foldable device can include a first middle frame 111, a second middle frame 121, a rotating shaft 130, a first battery 161, a second battery 162, a first mainboard 171, a second mainboard 172, a third mainboard 173, a fourth mainboard 174, a first rotating assembly 131, a second rotating assembly 133, and a third rotating assembly 135. The layout and structure of the above modules and devices can refer to the related description in FIGS. 3 and 4, and will not be repeated here.

[0075] The ground end of each mainboard included in the foldable device is fixedly connected to the middle frame by at least one screw. That is, it can be understood that the ground pin (ground end) of each mainboard is provided at least at the screw. For example, the first mainboard 171 is fixedly connected to the first middle frame 111 by five screws, i.e., a screw 311, a screw 312, a screw 313, a screw 314, and a screw 315. The ground pin of the first mainboard 171 can be provided at least at one of the screws 311, 312, 313, 314, and 315, so as to ensure that the ground line of the first mainboard 171 is in conduction with the first middle frame 111.

[0076] The screw is made of conductive material, such as metal. The middle frame is also made of conductive material, such as aluminum alloy, titanium alloy, etc. By virtue of the structure of the screw fixedly connecting the middle frame and the mainboards, the screw is connected to the ground end of each mainboard, and the screw is connected to the middle frame, so that the ground end of each mainboard can be in conduction with the middle frame through the screw. In addition, after the first middle frame and the second middle frame are connected, the ground end of each mainboard is in conduction, thereby forming a whole-machine ground backflow path.

[0077] Alternatively, the electrical connection between the middle frame and the ground end of the mainboard can be a screw, or a latch or welding, etc., and the application does not limit this.

[0078] Alternatively, the fixed connection between the middle frame and the mainboard can be a screw, a latch, or welding, etc., and the electrical connection between the middle frame and the ground end of the mainboard can be a wire (such as FPC, metal wire, etc.) or a spring piece (the spring piece is a conductor), etc.

[0079] Exemplarily, as shown in FIG. 9, it is a structural schematic diagram of a first mainboard ground wire connected with the first middle frame through a screw. As shown in FIG. 9, the first mainboard 171 includes a PCB board, a shielding cover and a plurality of components and the like. One screw hole passes through the ground pin of the PCB board and is connected to the first middle frame 111. Since the screw and the middle frame are both conductors, the middle frame can be in communication with the ground wire of the first mainboard. It should be noted that FIG. 9 is only an example of connecting the ground wire through one screw, and the ground wire can be connected through a plurality of screws, which is not limited in the present application.

[0080] The foldable device includes a first flexible circuit board 411 and a second flexible circuit board 412 (different from FIG. 4). The first flexible circuit board 411 is located between the first rotating assembly 131 and the second rotating assembly 133; and the second flexible circuit board 412 is located between the second rotating assembly 133 and the third rotating assembly 135. Optionally, in the embodiment of the present application, the number of rotating assemblies of the foldable device can be one, two, four or more. The first flexible circuit board 411 and the second flexible circuit board 412 can be connected to and pass through the shaft gap on both sides (or one side) of at least one rotating assembly. The specific position of the shaft-passing FPC is not limited in the present application. The above process, by means of the second FPC connecting the ground terminals of the first main body and the second main body, increases the return path, which can reduce the impedance of the ground return between different main bodies, reduce heat loss and ensure sufficient release of battery power.

[0081] It should be noted that the fixed connection and the electrical connection are two different meanings of connection. The fixed connection is a mechanical structure connection. The electrical connection is a connection for conducting electrical signals. In the embodiment of the present application, the screw (or the latch, the welding method and the like) is a mechanical connecting piece, which can fix the position of the main body and the middle frame on the same main body, that is, the screw, the welding and the latch all have the effect of fixing the main board and the middle frame. In addition, the screw, the welding and the latch are all conductors, and one end of the screw, the welding and the latch is connected to the ground terminal on the main board, that is, it can be used as a return path of the ground signal, and at this time, the screw, the welding and the latch also have the effect of electrical connection.

[0082] The connection of all ground terminals of each main body through the middle frame can reduce the number of wires required for the communication of different ground terminals of the main body. The middle frame has large volume and low impedance, which can more fully meet the impedance requirement of the ground return of the whole machine, reduce heat loss and ensure sufficient release of battery power.

[0083] The connection structure of the two ends of the first flexible circuit board 411 can refer to the related description of the flexible circuit board 321 in FIG. 4, and can refer to the related description of FIGS. 4-6, which will not be described here.

[0084] The first main body ground end includes at least one of a ground end of the first main board 171, a ground end of the third main board 173 and the first middle frame 111; and the second main body ground end includes at least one of a ground end of the second main board 172, a ground end of the fourth main board 174 and the second middle frame 121.

[0085] In addition, the traces included in the first flexible circuit board and the second flexible circuit board in FIG. 8 are different, the connection lines between the main boards are different, and the formed reflux paths are also different. The following describes the connection of the second FPC through two embodiments based on FIG. 8:

[0086]

Embodiment One

[0087] In a possible implementation, the second flexible circuit board FPC 412 is connected to the first main board 171 and the fourth main board 174 at both ends, and the second flexible circuit board 412 includes a ground wire and a first data control line (which can include an antenna signal line, etc.). The first flexible circuit board 411 includes a power supply line and a second data control line (which can include a screen display line, a camera line, etc.). The first flexible circuit board 411 can or can not include a ground wire. The specific connection of the first flexible circuit board 411 and the second flexible circuit board 412, the power supply reflux path and the path of other signals are described in detail with reference to FIGS. 10 and 11.

[0088] FIG. 10 is a split structure diagram of a foldable device in an unfolded state according to an embodiment of the present application. As shown in FIG. 10, one end of the second flexible circuit board 412 is connected to the first main board 171, and the other end is connected to the fourth main board 174. Specifically, one end of the second flexible circuit board 412 is connected to the first main board 171, passes through the gap between the second rotating assembly 133 and the third rotating assembly 135, continues to pass through the side of the second battery 162, and is connected to the fourth main board 174 through the bending.

[0089] In the above connection structure, the ground ends of the first main body and the second main body are connected by means of the second FPC trace, the reflux path is increased, the impedance of the ground reflux between different main bodies is reduced, the heat loss of the whole machine is reduced, and the battery power is fully released.

[0090] In the connection structure of FIG. 10, the second flexible circuit board 412 can include a ground wire and other signals. The first flexible circuit board 411 can include a power supply line and a first data control line. Optionally, the first flexible circuit board 411 can include or not include a ground wire.

[0091] Exemplarily, FIG. 11 is a schematic cross-sectional view of a first flexible circuit board and a second flexible circuit board disclosed in embodiments of the present application. FIG. 11(a) and (b) show schematic cross-sectional views of the first flexible circuit board. In FIG. 11(a), the first flexible circuit board includes a power line and a first data control line, and does not include a ground line. In FIG. 11(b), the second flexible circuit board includes a power line, a first data control line, and a ground line. In FIG. 11(c), the second flexible circuit board can include a ground line and a second data control line. Wherein, the first flexible circuit board changes from three layers to two layers in FIG. 4, and the thickness of the FPC board changes from 0.162 mm to 0.122 mm, the thickness decreases by 25%, and the manufacturing cost decreases by 40%. After the thickness of the FPC board changes to two layers, the bending radius of the FPC board in the shaft gap is large, and the bending life can be improved by tens of thousands of times. At the same time, the FPC top screen or abnormal sound condition can also be reduced, and the life of the foldable device can be improved. Alternatively, the first flexible circuit board can also be one layer. Alternatively, the first flexible circuit board can be three layers.

[0092] Since the devices included in each main board are different, the connection mode and the power charging, the ground path, etc. are different. The following describes the wiring connection condition and the signal path with FIG. 10 as an example.

[0093] First, the device modules of each main board are described. The first main board includes device modules such as a first power management unit PMU and a first SC. The second main board 172 can include a second PMU and a second SC, etc. The third main board 173 can include a Type C module and an overvoltage protection OVP module. Wherein, the Type C module and the OVP module are connected through the third main board 173.

[0094] The power management unit (PMU) is a chip for managing and controlling the power supply and power consumption of a device. As an integrated circuit, the PMU can effectively manage the power supply, thereby achieving optimal power management and function control. The PMU can connect the battery to manage the battery power and supply power to other modules of the foldable device. As shown in FIG. 10, the first battery 161 can be connected to the first PMU and the first switching charger (SC) chip through the bat1 wiring 512, respectively. The second battery 162 can be connected to the second PMU and the second SC through the bat2 wiring 513, respectively.

[0095] Optionally, the Type C interface module has the function of charging the battery and the PMU by the external charger, and the OTG function of connecting external devices (the foldable device needs to supply power to the Type C interface module). After the Type C interface module is connected to the OVP module, it needs to be connected to the first PMU and the second PMU through the Vbus, and the first SC and the second SC. The first SC and the second SC convert the voltage of the charger into a voltage suitable for charging the battery. When the external charger is connected, the Type C module needs to supply power to the first SC and the second SC, and the first PMU and the second PMU. The first mainboard 171 and the third mainboard 173 are connected through the Vbus wire 511. The Vbus wire 511. The Vbus wire 511 in the first mainboard 171 is connected to the first PMU and the first SC. Further, the Vbus wire 511 is connected to one end of the first FPC (power line in the first FPC); the other end of the first FPC (power line in the first FPC) is connected to the second PMU and the second SC of the second mainboard 172. In the above connection, when the foldable device is connected to the charger, the Type C interface module can supply power to the first PMU and the second PMU, and the first SC and the second SC. In the case of enabling the OTG function, the first PMU or the second PMU can supply power to the Type C interface module.

[0096] Optionally, the fourth mainboard 174 is connected to the antenna metal radiation branch. The fourth mainboard 174 needs to transmit the antenna signal to the first mainboard 171. Therefore, other lines connecting the first mainboard 171 and the fourth mainboard 174 can include an antenna signal line for transmitting the antenna signal.

[0097] In the above line connection, in the case that the foldable device is connected to the charger, the Type C interface module can charge the first battery 161 through the first SC and charge the second battery 162 through the second SC. The following takes the case that the foldable device is connected to the charger as an example to illustrate the backflow path in the charging process. The ground ends of the first mainboard 171 and the third mainboard 173 are connected to the first middle frame 111 through screws; the ground ends of the second mainboard 172 and the fourth mainboard 174 are connected to the second middle frame 121 through screws; the second flexible circuit board 412 is connected to the ground ends of the first mainboard 171 and the second mainboard 172 through the shaft. In the charging process, the backflow path is from the second mainboard 172 to the second middle frame 121, then to the second flexible circuit board 412, then to the first mainboard 171, and then the first mainboard 171 flows through the charging end of the first middle frame 111 to the third mainboard 173 to complete the backflow. The ground ends of the above-mentioned mainboards are connected to the middle frame, the backflow path is increased, the impedance of the middle frame is low, the impedance of the backflow path is smaller, the heat loss is small, the battery power release is more sufficient, and the ground backflow is more ideal. Among them, the Type C interface module is only an example of an interface type, and other interface types can also be used, which are not limited here.

[0098] Optionally, in the case that the first flexible circuit board 411 also includes a ground wire, the reflow path further includes a path from the second main board 172 to the first flexible circuit board 411 to the first main board 171 to the first middle frame 111, and then from the first middle frame 111 to the third main board 173, completing the reflow process of another path.

[0099] It should be noted that each of the above main boards can also include other devices and modules, which are not limited by the present application.

[0100] Optionally, in embodiment one, the two ends of the second flexible circuit board 412 can be connected to any main board in the first middle frame 111 and the second middle frame 121 respectively. The present application only limits that the two main boards are located in the two middle frames, and does not limit the position and size of the main boards, etc. For example, the two ends of the second flexible circuit board 412 can be connected to the third main board 173 and the fourth main board 174 respectively. At this time, the wiring between the first main board 171 and the third main board 173 can include the wiring of the antenna signal.

[0101]

Embodiment two

[0102] In another possible implementation, the two ends of the second flexible circuit board 412 are connected to the first middle frame 111 and the second middle frame 121, the second flexible circuit board 412 includes a ground wire and does not include other lines and power lines. The first flexible circuit board 411 includes power lines and first data control lines. The first flexible circuit board 411 can or can not include a ground wire. The specific connection of the first flexible circuit board 411 and the second flexible circuit board 412 is described in detail in combination with FIG. 12 and FIG. 13.

[0103] FIG. 12 is a split structure diagram of another foldable device in an unfolded state disclosed by the embodiments of the present application. As shown in FIG. 12, one end of the second flexible circuit board 412 is connected to the first middle frame 111, and the other end is connected to the second middle frame 121. In the connection structure of FIG. 12, the second flexible circuit board 412 can include a ground wire and does not include other types of lines (second data control lines). The first flexible circuit board 411 can include power lines and first data control lines. Optionally, the first flexible circuit board 411 can include or not include a ground wire.

[0104] In the above connection structure, the ground end of the first main body and the second main body is connected by means of the second FPC wiring, the reflow path is increased, the impedance of the ground reflow between different main bodies is reduced, the whole machine heat loss is reduced, and the battery power is fully released.

[0105] Exemplarily, FIG. 13 is a schematic cross-sectional view of a second flexible circuit board according to an embodiment of the present application. In FIG. 13, the second flexible circuit board includes a ground wire. It should be noted that the first flexible circuit board 411 in the second embodiment can refer to the related description of (a) and (b) in FIG. 11, and will not be described herein. In this embodiment, the second flexible circuit board is two layers. Alternatively, the second flexible circuit board can be one layer or three layers.

[0106] In FIG. 12, the second flexible circuit board 412 is different from that in FIG. 10 in that the second flexible circuit board 412 only includes a ground wire but does not include other wires. In this case, the fourth main board 174 transmits the antenna signal to the first main board 171, and the second main board 172 needs to be used for transmission. As shown in FIG. 12, the antenna signal wire 514 can transmit the antenna signal from the fourth main board 174 to the second main board 172, and the second main board 172 can continue to transmit the antenna signal to the first main board 171 through other wires in the first flexible circuit board 411. In addition, in FIG. 12, the connection of the first PMU, the second PMU, the first SC, the second SC, the Type-C module, the OVP module, and the battery and the backflow path during charging can refer to the related description of FIG. 10 and FIG. 11 above, and will not be described herein.

[0107] Alternatively, in the embodiment of FIG. 12, one end of the second flexible circuit board 412 is connected to the first middle frame 111, and the other end is connected to the fourth main board 174; or one end of the second flexible circuit board 412 is connected to the second middle frame 121, and the other end is connected to the first main board 171.

[0108] Alternatively, in another possible embodiment, different from the first embodiment and the second embodiment, the second FPC includes a ground wire and a second data control wire (for example, an antenna signal wire, etc.). In this embodiment, the two ends of the ground wire of the second FPC are connected to the first middle frame and the second middle frame, and the two ends of the second data control wire (for example, an antenna signal wire, etc.) of the second FPC are connected to the two main boards respectively located in the first main body and the second main body.

[0109] In the above-mentioned FIG. 8, FIG. 10 and FIG. 12, a second FPC is added, two FPCs, one FPC connects the signal of the fourth mainboard from the second mainboard to the first mainboard, and the other FPC connects the backflow path in a backflow manner. In the above-mentioned foldable device, by means of the second FPC wiring connecting the ground terminals of the first main body and the second main body, adding the backflow path can reduce the impedance of the backflow between different main bodies, reduce heat loss, and ensure that the battery power is fully discharged. In addition, by means of the backflow conducted by the middle frame, due to the small impedance of the middle frame, the structural characteristics of each mainboard can be conducted, an FPC plate is added through the shaft, the number of FPC plate lines is reduced, the thickness of the whole device is reduced, more space in the thickness direction is provided for the battery, the backflow path is complete and stable, the structure and setting of the whole machine are optimized, the battery performance is improved, and the reliability of the through-shaft line is improved. Therefore, the quality of the foldable device is improved.

[0110] In a possible implementation, the foldable device can further include a third main body, and the second main body and the third main body can be rotationally connected through another shaft. The FPC wiring between the second main body and the third main body can refer to the FPC layout between the first main body and the second main body in any one of the above-mentioned FIG. 4 to FIG. 12, and will not be repeated here. At this time, the foldable device is a three-fold device, and the foldable device can be more folded, which is not limited in the present application.

[0111] In a possible implementation, the foldable device can further include a third FPC, and the third FPC can also connect the ground terminal of the first main body and the ground terminal of the second main body. The ground terminal of the first main body can be at least one of the ground terminal of the mainboard in the first main body and the first middle frame. The ground terminal of the second main body can be at least one of the ground terminal of the mainboard in the second main body and the second middle frame. The third FPC can refer to the connection mode of the second FPC, which will not be repeated here. The above-mentioned FPC wiring can include two or more, which is not limited in the present application.

[0112] In the embodiments described above, all or some of the embodiments can be implemented by software, hardware, firmware or any combination thereof. When implemented by software, all or some of the embodiments can be implemented in the form of a computer program product storing the computer program instructions. The computer program instructions can be loaded on a computer and executed. The computer can be a general purpose computer, a special purpose computer, a computer network, or other programmable apparatus. The computer instructions can be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another computer readable storage medium. For example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center through wired (for example, coaxial cable, optical fiber, digital subscriber line) or wireless (for example, infrared, wireless, microwave, etc.) manner. The computer readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server, data center, etc. that integrates one or more available media. The available media can be a magnetic medium (for example, floppy disk, hard disk, magnetic tape), an optical medium (for example, DVD), or a semiconductor medium (for example, solid state disk), etc.

Claims

1. A foldable device, characterized by, Wherein: The foldable device comprises a first body, a second body and a hinge, the first body and the second body are connected through the hinge, the foldable device can be folded at the hinge; the first body comprises a first middle frame and a first mainboard, the second body comprises a second middle frame and a second mainboard; The first mainboard is fixed with the first middle frame; the second mainboard is fixed with the second middle frame; the ground terminal of the first mainboard is electrically connected to the first middle frame; The ground terminal of the second mainboard is electrically connected to the second middle frame; The foldable device comprises a first flexible printed circuit (FPC) and a second FPC; the first FPC connects the first mainboard and the second mainboard through the hinge; the second FPC connects the ground terminal of the first body and the ground terminal of the second body through the hinge.

2. The foldable device of claim 1, wherein, One end of the second FPC is connected to the ground terminal of the mainboard in the first middle frame or the first body; the other end of the second FPC is connected to the ground terminal of the mainboard in the second middle frame or the second body.

3. The foldable device of claim 2, wherein, The first body further comprises a third mainboard; the second body further comprises a fourth mainboard, the third mainboard is fixed with the first middle frame; the fourth mainboard is fixed with the second middle frame, the ground terminal of the third mainboard is electrically connected to the first middle frame; the ground terminal of the fourth mainboard is electrically connected to the second middle frame; the ground terminal of the first body comprises at least one of the ground terminal of the first mainboard, the ground terminal of the third mainboard and the first middle frame; the ground terminal of the second body comprises at least one of the ground terminal of the second mainboard, the ground terminal of the fourth mainboard and the second middle frame.

4. The foldable device of claim 1 or 2, wherein, The second FPC connects the ground terminal of the first body and the ground terminal of the second body through the hinge, comprising: The second FPC connects the first middle frame and the second middle frame through the hinge.

5. The foldable device of any one of claims 1-4, wherein, The first mainboard is fixed with the first middle frame; The ground terminal of the first mainboard is electrically connected to the first middle frame, comprising: The first mainboard is electrically connected to the first middle frame through a first connecting piece; the first connecting piece is electrically connected to the ground terminal of the first mainboard; the first connecting piece fixes the first mainboard and the first middle frame, and the first connecting piece is a first screw or a first bolt; The second mainboard is fixed with the second middle frame; the ground terminal of the second mainboard is electrically connected to the second middle frame, comprising: The second mainboard is electrically connected to the second middle frame through a second connecting piece; the second connecting piece is electrically connected to the ground terminal of the second mainboard; the second connecting piece fixes the second mainboard and the second middle frame, and the second connecting piece is a second screw or a second bolt.

6. The foldable device of any one of claims 1-4, wherein, The first mainboard is fixed with the first middle frame, comprising that the first mainboard is fixed with the first middle frame through welding, screw or bolt; The ground terminal of the first mainboard is electrically connected to the first middle frame, comprising that the ground terminal of the first mainboard is electrically connected to the first middle frame through a spring sheet and / or a wire; The second mainboard is fixed with the second middle frame, comprising that the second mainboard is fixed with the second middle frame through welding, screw or bolt; The ground end of the second mainboard is electrically connected with the second middle frame, and the ground end of the second mainboard is electrically connected with the second middle frame through the spring sheet and / or the wire.

7. The foldable device of any one of claims 1-6, wherein, The first FPC includes a power line and a data control line; the data control line includes a camera line and a screen signal line.

8. The foldable device of any one of claims 1-7, wherein, The first FPC includes a ground wire.

9. The foldable device of claim 3, wherein, In the case that the second FPC further includes an antenna signal trace, the antenna signal trace connects the first mainboard and the fourth mainboard.

10. The foldable device of any one of claims 1-9, wherein, The first FPC is two-layer or one-layer trace.

11. The foldable device of any one of claims 1-10, wherein, The second FPC is two-layer or one-layer trace.

12. The foldable device of any one of claims 1-11, wherein, The rotating shaft includes a first rotating component, a second rotating component and a third rotating component; the second rotating component is between the first rotating component and the third rotating component; there is a first rotating shaft gap between the first rotating component and the second rotating component; there is a second rotating shaft gap between the second rotating component and the third rotating component; the first rotating component, the second rotating component and the third rotating component of the rotating shaft are used for movably connecting the first middle frame and the second middle frame.

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