Foldable display device

Abstract

A foldable display device, the foldable display device comprising a first frame, a second frame, a rotary shaft assembly, a flexible heat sink, and a flexible circuit board, and the flexible heat sink and the flexible circuit board extend through the rotary shaft assembly; the rotary shaft assembly comprises a shaft seat, a door plate, a first support plate, and a second support plate, wherein the door plate is mounted on the shaft seat, the first support plate and the second support plate are distributed on two sides of the door plate, in a process of folding the foldable display device, an end belonging to the first support plate and which is close to the door plate and an end belonging to the second support plate and which is close to the door plate move in a direction away from the door plate, and an end belonging to the first support plate and which is remote from the door plate and an end belonging to the second support plate and which is remote from the door plate move close to each other; a first side of the first frame and a first side of the second frame are configured to mount a flexible display, a second side of the first frame and a second side of the second frame are configured to mount an electronic element, the first side of the first frame is opposite the second side of the first frame, and the first side of the second frame is opposite the second side of the second frame; the two opposite ends of the flexible heat sink are connected to the first side of the first frame and the first side of the second frame, and two opposite ends of a part of the flexible heat sink in the rotary shaft assembly are each attached to a first attachment surface belonging to the first support plate and facing the shaft seat, and a second attachment surface belonging to the second support plate and facing the shaft seat; and the two opposite ends of the flexible circuit board are connected to the second side of the first frame and the second side of the second frame.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of terminal devices and, in particular, to a foldable display device. BACKGROUND

[0002] Currently, a foldable display device usually includes a rotary shaft and two bodies. The rotary shaft is rotatably connected to the two bodies. Electronic elements such as a circuit board are arranged in each body. To implement electrical connection of electronic elements in the two bodies, the foldable display device connects the two bodies using a flexible circuit board that can pass through a shaft. Typically, the flexible circuit board retains an extra length to implement an unfolded state and a folded state of the foldable display device. To prevent the flexible circuit board from being easily broken or scratched against another structure, the flexible circuit board can be redundant in the rotary shaft to reduce a space occupied by the flexible circuit board.Alternatively, the flexible circuit board can be redundantly placed under the door plate of the rotary shaft, but this requires it to occupy a large space. Additionally, to implement heat dissipation of the electronic elements of the two bodies, graphite foils can be placed under flexible displays covering the surfaces of the two bodies. Specifically, the foldable display device is attached to the two bodies using two graphite foils and separated from the rotary shaft area. Therefore, heat cannot be transferred between the two bodies, which may lead to uneven heat dissipation between the two bodies. SUMMARY

[0003] In view of the above, it is necessary to provide a foldable display device to avoid uneven heat dissipation between two bodies and to arrange two opposite ends of a part of the flexible heat sink in the rotary shaft assembly.

[0004] One embodiment of this application provides a foldable display device, the foldable display device comprising a first frame, a second frame, a rotary shaft assembly, and a flexible circuit board. The flexible circuit board extends through the rotary shaft assembly, and the rotary shaft assembly includes a shaft seat, a door plate, a first support plate, and a second support plate.The door plate is mounted on the shaft seat, the first support plate and the second support plate are slidably connected to the shaft seat, the first support plate and the second support plate are distributed on two sides of the door plate, an end belonging to the first support plate and which is close to the door plate and an end belonging to the second support plate and which is close to the door plate can move in a direction away from the door plate, and an end belonging to the first support plate and which is remote from the door plate and an end belonging to the second support plate and which is remote from the door plate can move close to each other.The foldable display device further comprises a flexible heat sink, wherein the flexible heat sink extends through the rotary shaft assembly and two opposite ends of the flexible heat sink are connected to the first frame and the second frame, and two opposite ends of a part of the flexible heat sink in the rotary shaft assembly are respectively attached to a first attachment surface belonging to the first support plate and facing the shaft seat, and a second attachment surface belonging to the second support plate and facing the shaft seat.

[0005] In this application, the flexible heat sink passes through the rotary shaft assembly, the two ends of the flexible heat sink are connected to the first frame and the second frame, and heat transfer between the first frame and the second frame through the flexible heat sink can be implemented.The two opposite ends of a part of the flexible heat sink in the rotary shaft assembly are fixed under the movable first support plate and the movable second support plate, and the two opposite ends of a part of the flexible heat sink in the rotary shaft assembly can be arranged so that two opposite ends of a part of the flexible heat sink can be arranged in the rotary shaft assembly to avoid a case where the flexible heat sink moves in a longitudinal direction when the foldable display device is folded or unfolded, resulting in large-scale deformation and positional change of the flexible heat sink.

[0006] According to some embodiments of this application, the flexible heat sink covers the flexible circuit board in the rotary shaft assembly.

[0007] In this application, the flexible heat sink covers the flexible circuit board, which improves the space utilization of the rotary shaft assembly.

[0008] According to some embodiments of this application, the rotary shaft assembly further comprises a housing, the shaft seat is mounted to the housing, the shaft seat and the housing together form a receiving cavity, and the flexible heat sink and the flexible circuit board are partially received in the receiving cavity.

[0009] In this application, the flexible heat sink and the flexible circuit board are redundant in the receiving cavity to avoid breakage of the flexible circuit board and the flexible heat sink and a larger space occupied by the foldable display device.

[0010] According to some embodiments of this application, a receiving groove is formed on the shaft seat, the receiving groove penetrates the shaft seat, the shaft seat and the housing together form the receiving cavity at the receiving groove, further, a cross member is formed on the shaft seat at the receiving groove, and the cross member is separated from the housing; and a center segment position of the flexible heat sink is attached to a surface belonging to the cross member and facing the housing.

[0011] In this application, the shaft seat forms the cross member at the receiving cavity that accommodates the flexible heat sink. The center segment position of the flexible heat sink is fixed below the cross member, allowing the center segment position of the flexible heat sink to be located and the flexible heat sink to be divided into two segments of similar lengths in a longitudinal direction. Therefore, the displacement and bending deformation generated when the flexible heat sink is folded or unfolded by the foldable display device are smaller, and the displacement and bending amount can be more easily controlled.

[0012] According to some embodiments of this application, the cross member extends from a first side wall of the shaft seat near the receiving groove to a second side wall opposite the first side wall and is separated from another side wall of the shaft seat near the receiving groove.

[0013] According to some embodiments of this application, the cross member and another side wall of the shaft seat near the receiving groove form a first interval and a second interval, and the flexible heat sink and the flexible circuit board enter the receiving cavity through the first interval and exit the receiving cavity through the second interval.

[0014] In this application, the cross member and the shaft seat form the first interval and the second interval, so that the flexible heat sink and the flexible circuit board can enter the receiving cavity through the first interval and exit the receiving cavity through the second interval, and the flexible heat sink and the flexible circuit board can pass through the rotary shaft assembly.

[0015] According to some embodiments of this application, the housing comprises an inner housing surface and a positioning element, the positioning element is fixedly mounted to the inner housing surface and located in the receiving cavity, and the cross member and the positioning element are separated from each other and together position mid-segment positions of the flexible circuit board and the flexible heat sink.

[0016] In this application, a positioning element mounted in the housing and the cross member jointly position the center segment positions of the flexible circuit board and the flexible heat sink, so that the flexible circuit board and the flexible heat sink can be divided into two segments of similar lengths in a longitudinal direction. Therefore, the displacement and bending deformation generated when the flexible circuit board and the flexible heat sink are folded or unfolded by the foldable display device are smaller, and the displacement and bending amount can be more easily controlled.

[0017] According to some embodiments of this application, the foldable display device further comprises a buffer element, the buffer element is arranged on the positioning element and separated from the cross member, and the buffer element is configured to prevent damage to the flexible circuit board by the positioning element due to elastic deformation.

[0018] In this application, the buffer element is arranged on the positioning element and separated from the cross member, so that damage to the flexible circuit board caused by the positioning element can be avoided. Additionally, the connection position between the flexible circuit board and the cross member can be easily changed by using the buffer element, thus avoiding the risk of breakage due to the stretched flexible circuit board.

[0019] According to some embodiments of this application, a first side of the first frame and a first side of the second frame are configured to mount a flexible display, and a second side of the first frame and a second side of the second frame are configured to mount an electronic element; the two opposite ends of the flexible heat sink are connected to the first side of the first frame and the first side of the second frame; and two opposite ends of the flexible circuit board are connected to a second side of the first frame and a second side of the second frame, and the second side is opposite to the first side.

[0020] In this application, the flexible heat sink and the flexible circuit board are arranged on different sides of the first frame and the second frame, so that heat dissipation of the flexible heat sink to the frame and connection of electronic components to the flexible circuit board can be implemented and mutual interference between the flexible heat sink and the flexible circuit board can be avoided.

[0021] According to some embodiments of this application, the foldable display device further comprises a first bracket, a second bracket, a first synchronization arm, a second synchronization arm, and a cam gear structure; wherein the first bracket is rotatably connected to the first support plate, the second bracket is rotatably connected to the second support plate, and the first bracket and the second bracket are rotatably connected to the shaft seat; the first synchronization arm is slidably connected to the first bracket and rotatably connected to the first bracket, and the second synchronization arm is slidably connected to the second bracket and rotatably connected to the second bracket;and the cam wheel structure is arranged on the shaft seat and includes a concave and convex structure, and the first synchronization arm and the second synchronization arm are connected to the cam wheel structure through the concave and convex structure to implement damping of the rotation of the first bracket and the second bracket.;

[0022] In this application, the first synchronization arm and the second synchronization arm are connected to the cam wheel structure through the concave and convex structure to implement damping of the rotation of the first bracket and the second bracket, so that a speed of folding or unfolding the foldable display device can be slightly slow to improve the folding or unfolding stability of the foldable display device and improve a user's use experience. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram showing a structure of a conventional foldable display device in a flattened state; Fig. 2 is a schematic diagram showing a structure of a conventional foldable display device in a folded state; Fig. 3 is a schematic diagram showing a structure of a foldable display device in a flattened state according to a first embodiment of this application; Fig. 4 is a schematic sectional view of a foldable display device in a flattened state according to a first embodiment of this application; Fig. 5 is a schematic diagram showing a structure of a foldable display device in a folded state according to a first embodiment of this application; Fig. 6 is a schematic sectional view of a foldable display device in a folded state according to a first embodiment of this application; Fig. 7 is a schematic representation of a connection between a rotary shaft assembly, a flexible printed circuit board and graphite of the Fig. 4 shown foldable display device; Fig. 8 is a schematic exploded view of the rotary shaft arrangement of the Fig. 7 shown foldable display device; Fig. 9 is a schematic representation of a structure in which a shaft seat of the Fig. 8 is mounted on a housing; Fig. 10 is a schematic exploded view of a damping device of the Fig. 8 shown rotary shaft arrangement; Fig. 11 is a schematic arrangement diagram of a damping device of the Fig. 8 shown rotary shaft arrangement; Fig. 12 is a schematic sectional view of a foldable display device in a flattened state according to a second embodiment of this application; Fig. 13 is a schematic sectional view of a foldable display device in a folded state according to a second embodiment of this application; and Fig. 14 is a schematic exploded view of a rotary shaft assembly of a foldable display device in a flattened state according to a second embodiment of this application. DESCRIPTION OF EMBODIMENTS

[0023] The terms "first" and "second" mentioned below are intended for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly specifying a set of specified technical features. Therefore, a feature limited by "first" or "second" may explicitly indicate or imply one or more features. In the description of embodiments of this application, words such as "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design scheme described as an "example" or "for example" in embodiments of this application should not be declared more preferred or having more advantages than another embodiment or design scheme. In particular, words such as "for example" are intended to represent relevant concepts in a specific way.

[0024] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used in this application are intended to describe specific embodiments only and are not intended to limit this application.

[0025] Fig. 1 is a schematic diagram of a structure of a conventional foldable display device in a flattened state; and Fig. 2 is a schematic diagram of a structure of a conventional foldable display device in a folded state. The foldable display device 1 supports the arrangement of two ends of the flexible circuit board 13, which can pass through a shaft using a steel foil 11. Specifically, the foldable display device 1 includes a first frame 14, a second frame 15, and a rotary shaft assembly 16. The rotary shaft assembly 16 is rotatably connected between the first frame 14 and the second frame 15. The flexible circuit board 13 passes through the rotary shaft assembly 16 and is connected to the first frame 14 and the second frame 15.The steel foil 11 is pressed onto the flexible circuit board 13 and can be fixed to the first frame 14 and the second frame 15 in a manner such as locking with a screw or a buckle, so that the flexible circuit board 13 can be fixed to the first frame 14 and the second frame 15, which comprise the foldable display device 1. However, the conventional foldable display device 1 is only configured such that the flexible circuit board 13 extends within a portion of the rotary shaft assembly 16, the space efficiency of the rotary shaft assembly 16 is low, and the heat dissipation of the conventional first frame 14 and the second frame 15 is uneven.

[0026] See Fig. 3 to Fig. 6. Fig. 3 is a schematic diagram of a structure of a foldable display device in a flattened state according to this application; Fig. 4 is a schematic exploded view of a foldable display device in a flattened state according to a first embodiment of this application; Fig. 5 is a schematic diagram of a structure of a foldable display device in a folded state according to a first embodiment of this application; and Fig. Figure 6 is a schematic exploded view of a foldable display device in a folded state according to a first embodiment of this application. The foldable display device 1 may be a foldable display mobile phone, a foldable display e-book, a foldable display laptop computer, or the like. The following specifically describes the solution provided in this embodiment of this application by using an example in which this embodiment of this application is applied to a foldable display mobile phone. A flexible display is in Fig. 3 and Fig. 4 is not shown. However, it should be understood that the flexible display is included when the foldable display device is in a deployed state.

[0027] A foldable display device 3 includes a first frame 4, a second frame 5, a rotating shaft assembly 6, a flexible display 7, a flexible circuit board 8, and a flexible heat sink 9. Electronic elements within the foldable display device 3, such as a circuit board, a processor, a memory, a battery, a camera module, an earphone module, a speaker module, a microphone module, an antenna module, and a sensor module, can be separately attached to the first frame 4 and the second frame 5. The first frame 4 and the second frame 5 are rotatably connected using the rotating shaft assembly 6 and can be rotated about the rotating shaft assembly 6 into a flattened state or a folded state. The flexible display 7 covers both the first frame 4 and the second frame 5.The flexible circuit board 8 extends through the rotary shaft assembly 6 and is connected to the first frame 4 and the second frame 5 to implement connection of electronic elements in the first frame 4 and the second frame 5. The flexible heat sink 9 extends through the rotary shaft assembly 6, two ends of the flexible heat sink 9 are connected to the first frame 4 and the second frame 5, and the two ends of the flexible heat sink 9 are fixed to the first frame 4 and the second frame 5. The flexible heat sink 9 and the flexible circuit board 8 extend through the rotary shaft assembly 6 through a same area of ​​the rotary shaft assembly 6. The flexible heat sink 9 can transfer heat from the first frame 4 and the second frame 5 to each other, so that the temperatures of the first frame 4 and the second frame 5 are uniform. The flexible heat sink 9 can be made of a thermally conductive material.The heat-conducting material may be a material such as graphite or carbon fiber. To implement an unfolded state and a folded state of the foldable display device 3, the flexible circuit board 8 and the flexible heat sink 9 retain an additional length. When the foldable display device 3 is in an unfolded state, as shown in FIG. Fig. 3, the first frame 4 and the second frame 5 are approximately parallel and coplanar to each other, and in this case, the flexible display 7 unfolds to form a larger display area. Apparently, the first frame 4 and the second frame 5 may not be approximately parallel, that is, an included angle existing between the first frame 4 and the second frame 5 may have some deviations relative to 180°. For example, an included angle between the first frame 4 and the second frame 5 may be 176°, 182°, or the like. When the foldable display device 3 is in a folded state, the first frame 4 and the second frame 5 can be completely closed, and there is no gap or a small gap between the first frame 4 and the second frame 5, which can play a good role in sealing against water, dust, and foreign matter.The first frame 4 and the second frame 5 may be completely closed to expose the rotary shaft assembly 6. In this way, the first frame 4, the second frame 5, and the rotary shaft assembly 6 together form an outer surface of the foldable display device 3, and the flexible display 7 is also in a folded state and located on an inner side of the foldable display device 3, and the foldable display device 3 has a small size. It should be understood that the first frame 4 and the second frame 5 may not be completely closed, but only ends that are of the first frame 4 and the second frame 5 and that are remote from the rotary shaft assembly 6 are in contact with each other.

[0028] It is understood that the first frame 4 and the second frame 5 may also be relatively unfolded or relatively folded into an intermediate state, the intermediate state may be any state between the flattened state and the folded state, and the flexible display 7 moves with the first frame 4 and the second frame 5.

[0029] It is understood that the foldable display device 3 may comprise two frames, for example, the above first frame 4 and the above second frame 5, or the foldable display device 3 may comprise three or more frames. Any two adjacent frames may be connected using a rotary shaft assembly 6. The flexible display 7 covers the three or more frames. The following specifically describes the solution provided in this embodiment of this application, using an example in which the foldable display device 3 comprises two frames.

[0030] With reference to Fig. 4 and Fig. 7 is Fig. 7 is a schematic diagram of a connection between a rotary shaft assembly, a flexible circuit board, and a flexible heat sink of the foldable display device. As shown in Fig. As shown in Figure 7, in order to prevent the flexible circuit board 8 and the flexible heat sink 9 from being easily broken or scratched against another structure, the flexible circuit board 8 and the flexible heat sink 9 pass through the rotary shaft assembly 6 and are redundant in the rotary shaft assembly 6. The flexible circuit board 8 can be arranged at a position of an end part using a first positioning device and a second positioning device. For example, the position of an end part of the flexible circuit board 8 is fixed to the first frame 4 and the second frame 5 using a first steel foil and a second steel foil, so that large-scale deformation and position change of the flexible circuit board 8 can be avoided when the foldable display device 3 is folded or unfolded. The flexible heat sink 9 is arranged in the rotary shaft assembly 6 through the rotary shaft assembly 6.The flexible heat sink 9 is arranged in the rotary shaft assembly 6 by the rotary shaft assembly 6, and this will be described in more detail below.

[0031] Fig. 8 is a schematic exploded view of the rotary shaft assembly of the foldable display device; and Fig. Figure 9 is a schematic diagram of a structure in which a shaft seat of the rotary shaft assembly is mounted on a housing. The rotary shaft assembly 6 includes a housing 60, a shaft seat 61, a first bracket 62, a second bracket 63, a damper 64, a door plate 65, a first support plate 66, and a second support plate 67.

[0032] The housing 60 includes a housing surface 600 and a mounting cavity 601. The housing surface 600 is a smooth surface and the shaft seat 61 is mounted in the mounting cavity 601.

[0033] With reference to Fig. 6, Fig. 8 and Fig. 9, the shaft seat 61 may be mounted in the mounting cavity 601 of the housing 60 using a fastening structure (for example, may be a screw or a bolt), or the shaft seat 61 may be mounted in the mounting cavity 601 of the housing 60 using an adhesive, welding, a snap fit, or another method. This is not limited in this application. A receiving groove 610 is formed on the shaft seat 61, and the receiving groove 610 penetrates the shaft seat 61. The shaft seat 61 and the housing 60 together form a receiving cavity 611 at the receiving groove 610. The receiving cavity 611 is configured to receive the flexible circuit board 8 and the flexible heat sink 9. In this embodiment, the flexible heat sink 9 and the flexible circuit board 8 are partially received in the receiving cavity 611.

[0034] Furthermore, a cross member 612 is formed on the shaft seat 61 at the receiving groove 610. The cross member 612 extends from a first side wall 613 of the shaft seat 61 near the receiving groove 610 to a second side wall 614 opposite the first side wall 613, and therefore, the cross member 612 covers a part of the receiving groove 610. The cross member 612 is separated from another side wall of the shaft seat 61 near the receiving groove 610 to form a first interval 615 and a second interval 616. Fig. 9, the cross member 612 is separated from a third side wall 617 and a fourth side wall 618 of the shaft seat 61 near the receiving groove 610 to form the first interval 615 and the second interval 616. The cross member 612 is separated from the housing 60. The flexible circuit board 8 and the flexible heat sink 9 enter the receiving cavity 611 through a first interval 615, are redundant in the receiving cavity 611, and exit the receiving cavity 611 through a second interval 616. In the receiving cavity 611, the flexible heat sink 9 is located above the flexible circuit board 8 and covers the flexible circuit board 8, and the flexible heat sink 9 may or may not be in contact with the flexible circuit board 8.In the accommodation cavity 611, a size of the flexible heat sink 9 in a longitudinal direction of the rotary shaft assembly 6 may be equal to a size of an area occupied by the flexible circuit board 8 in that direction. In this case, all areas of the flexible circuit board 8 in the rotary shaft assembly 6 are covered by the flexible heat sink 9, so no additional space of the rotary shaft assembly 6 is required to accommodate the flexible heat sink 9, thereby improving the space utilization of the rotary shaft assembly 6.

[0035] The first bracket 62 can be rotatably connected to the shaft seat 61, the second bracket 63 can be rotatably connected to the shaft seat 61, the first bracket 62 and the second bracket 63 are arranged on two opposite sides of the shaft seat 61, and the shaft seat 61 is mounted in the housing 60. The first bracket 62 is fixedly connected to the first frame 4, and the second bracket 63 is fixedly connected to the second frame 5. Therefore, when the first bracket 62 rotates relative to the shaft seat 61 and the second bracket 63 rotates relative to the shaft seat 61, the first frame 4 moves relative to the second frame 5, that is, the first frame 4, which is driven by the first bracket 62, and the second frame 5, which is driven by the second bracket 63, are relatively folded or relatively unfolded.

[0036] With reference to Fig. 4, Fig. 8, Fig. 9, Fig. 10 and Fig. 11 is Fig. 10 is a schematic exploded view of a damping device of the rotary shaft assembly; and Fig. 11 is a schematic diagram of the arrangement of a damping device of the rotary shaft assembly. The damping device 64 can be mounted on the shaft seat 61. The damping device 64 includes a rotary shaft 640, an elastic element 641, a cam gear structure 642, a first damping arm 643, and a second damping arm 644. The rotary shaft 640 can be mounted on the shaft seat 61. The rotary shaft 640 is configured to connect to the cam gear structure 642, the first damping arm 643, and the second damping arm 644. In this embodiment, there are a plurality of rotary shafts 640.The plurality of rotary shafts 640 are spaced apart on the shaft seat 61, and the plurality of rotary shafts 640 separately cooperate with the cam gear structure 642, the first damping arm 643, and the second damping arm 644 to implement a rotary connection between each of the cam gear structure 642, the first damping arm 643, and the second damping arm 644 and the shaft seat 61. It should be noted that in . Fig. 9, there are four rotary shafts 640, and the following specifically describes the solution provided in this embodiment of this application, using an example in which the damping device 64 includes four rotary shafts 640. However, the number of rotary shafts 640 in this embodiment is not limited to four. Fig. 9 is merely an exemplary illustration. The number of rotating shafts 640 may be three, five, or the like, and may be arranged based on requirements and mounting space. The elastic member 641 is slid onto the rotating shaft 640.

[0037] The cam gear structure 642 is fitted onto the rotary shaft 640 to abut against one end of the elastic member 641. The cam gear structure 642 includes two first cam gears 6420 that are fixedly connected. The two first cam gears 6420 are fitted onto the outermost sides of two rotary shafts 640. A concave and convex structure 6421 is arranged on each of the surfaces remote from the first cam gear 6420 and the elastic member 641. In this embodiment, the two first cam gears 6420 are fixedly connected using a connector 6422. A through hole 6423 is formed on the connector 6422. The through hole 6423 is configured so that two rotary shafts 640 extend through the center.

[0038] One end of the first damping arm 643 is slidably connected to the first bracket 62, the other end of the first damping arm 643 is rotatably connected to the shaft seat 61 and engages with the cam gear structure 642 on the shaft seat 61 using the concave and convex structure 6421. One end of the second damping arm 644 is slidably connected to the second bracket 63, the other end of the second damping arm 644 is rotatably connected to the shaft seat 61 and engages with the cam gear structure 642 on the shaft seat 61 using the concave and convex structure 6421.The cam wheel structure 642 is configured to hinder the movement of the first damping arm 643 and the second damping arm 644 in a process of moving the foldable display device 3, slow down the movement of the first bracket 62 and the second bracket 63 driven by the first damping arm 643 and the second damping arm 644, and slow down the movement of the first frame 4 and the second frame 5 driven by the first bracket 62 and the second bracket 63, so as to implement the stability of folding or unfolding the first frame 4 and the second frame 5 to improve the operating experience of the foldable display device 3.

[0039] The first damping arm 643 includes a movable end 6430, a damping end 6433, and a connecting segment 6438, and the connecting segment 6438 is connected to the movable end 6430 and the damping end 6433. A rotary shaft hole 6431 is located at an end remote from the movable end 6430 of the first damping arm 643 and from the connecting segment 6438. The rotary shaft hole 6431 penetrates the movable end 6430. The first damping arm 643 is slidably connected to the first bracket 62 using the rotary shaft hole 6431. The damping end 6433 of the first damping arm 643 is in contact with the cam gear structure 642. The damping end 6433 of the first damping arm 643 includes a second cam wheel 6434. The concave and convex structure 6421 is arranged on a surface that is of the second cam wheel 6434 and that is in contact with the first cam wheel 6420.The second cam gear 6434 engages with the first cam gear 6420 using the concave and convex structure 6421. The first damper arm 643 may be integrally formed with a structural member to have high structural strength.

[0040] The second damping arm 644 includes a movable end 6440, a damping end 6443, and a connecting segment 6448, and the connecting segment 6448 is connected to the movable end 6440 and the damping end 6443. For a specific structure of the movable end 6440 and the damping end 6443 of the second damping arm 644, they refer to a structure of the movable end 6440 and the damping end 6443 of the first damping arm 643. Details will not be described again here. The second damping arm 644 may be integrally formed with a structural member to have high structural strength.

[0041] In a process of switching between a flattened state and a folded state, the first damping arm 643 rotates relative to the shaft seat 61, and the first damping arm 643 slides relative to the first bracket 62 and rotates relative to the first bracket 62. The second damping arm 644 rotates relative to the shaft seat 61, and the second damping arm 644 can slide relative to the second bracket 63 and rotate relative to the second bracket 63. In this case, the damping device 64 can provide damping for the rotation and sliding of the first damping arm 643 and the second damping arm 644.Specifically, the first damper arm 643 rotates relative to the shaft seat 61, and the damper end 6433 of the first damper arm 643 drives the cam gear structure 642 toward the elastic member 641 using the concave and convex structure 6421 to further compress the elastic member 641 or drive the elastic member 641 to rotate. The second damper arm 644 rotates relative to the shaft seat 61, and the damper end 6443 of the second damper arm 644 drives the cam gear structure 642 toward the elastic member 641 using the concave and convex structure 6421 to further compress the elastic member 641 or drive the elastic member 641 to rotate. Therefore, the elastic member 641 can provide an opening / closing damping force.In this way, in a process in which the first damping arm 643 drives the first bracket 62 and the second damping arm 644 drives the second bracket 63 to rotate synchronously, the opening / closing damping force provided by the elastic member 641 can slow down a speed of folding or unfolding the foldable display device 3, improve the stability of folding or unfolding the foldable display device 3, and improve a user's use experience.

[0042] Since the two first cams 6420 of the cam structure 642 are firmly connected, the magnitudes of the rotation angles originating from the damping end 6433 of the first damping arm 643 and the damping end 6443 of the second damping arm 644 are equal, and the rotational actions originating from the first damping arm 643 and the second damping arm 644 relative to the shaft seat 61 are synchronous. The first damping arm 643 and the second damping arm 644 drive the first bracket 62 and the second bracket 63 to move synchronously, and the first bracket 62 and the second bracket 63 drive the first frame 4 and the second frame 5 to move synchronously, thereby implementing relative folding or relative unfolding of the first frame 4 and the second frame 5 and improving a user's usage experience.

[0043] The damping device 64 further includes a synchronization device 645, and the synchronization device 645 can be mounted on the shaft seat 61. The synchronization device 645 is rotatably connected to the shaft seat 61. The other end of the first damping arm 643 further engages the synchronization device 645 on the shaft seat 61 using a gear. The other end of the second damping arm 644 further engages the synchronization device 645 on the shaft seat 61 using a gear. The synchronization device 645 may include two synchronization gears 6450, wherein the synchronization gears 6450 include a first rotary part 6451 and a first gear part 6453 arranged around the first rotary part 6451, the first rotary part 6451 is provided with a first rotary hole 6452, and the first rotary hole 6452 penetrates the first rotary part 6451.The first rotation hole 6452 is configured so that the rotation shaft 640 passes therethrough. The first gear part 6453 is provided with a plurality of gears, and the plurality of gears protrude relative to the first rotation part 6451.

[0044] It is understood that there are a plurality of synchronization gears 6450, the plurality of synchronization gears 6450 are arranged in a row, and first gear parts 6453 of two adjacent synchronization gears 6450 mesh with each other. The synchronization gear 6450 may be integrally formed with a structural member to have high structural strength.

[0045] The quantity, size, and the like of the synchronization gear 6450 of the synchronization device 645 can be designed based on product models, such as a specific shape and size. This is not strictly limited in this application. A larger quantity of synchronization gears 6450 and a smaller size of synchronization gears 6450 can free up more space; and a smaller quantity of synchronization gears 6450, a larger size of synchronization gears 6450, and a smaller cumulative drive error of synchronization gears 6450 contribute to improving movement accuracy.

[0046] The damping end 6433 of the first damping arm 643 further includes a second rotating part 6435 and a second gear part 6437 arranged around the second rotating part 6435. The second rotating part 6435 is connected to the connecting segment 6438 of the first damping arm 643. An end remote from the second rotating part 6435 and from the connecting segment 6438 of the first damping arm 643 is fixedly connected to the second cam gear 6434. The second gear part 6437 is provided with a plurality of gears. The plurality of gears of the second gear part 6437 are configured to mesh with the plurality of gears of the first gear part 6433. The second rotating part 6435 is provided with a second rotating hole 6436, and the second rotating hole 6436 penetrates the second rotating part 6435. The second rotating hole 6436 is configured so that the rotating shaft 640 passes therethrough.

[0047] Further, when the first damper arm 643 rotates relative to the shaft seat 61, the damper end 6433 of the first damper arm 643 engages with the damper end 6443 of the second damper arm 644 using a gear of the synchronizer 645, so that magnitudes of rotation angles originating from the damper end 6433 of the first damper arm 643 and the damper end 6443 of the second damper arm 644 are equal, and rotations originating from the first damper arm 643 and the second damper arm 644 relative to the shaft seat 61 are synchronous.The first damping arm 643 and the second damping arm 644 drive the first bracket 62 and the second bracket 63 to move synchronously, and the first bracket 62 and the second bracket 63 drive the first frame 4 and the second frame 5 to move synchronously, thereby implementing relative folding or relative unfolding of the first frame 4 and the second frame 5 and improving a user's use experience.

[0048] With reference to Fig. 6, Fig. 8 and Fig. 9, the door plate 65 is mounted on the shaft seat 61. When the foldable display device 3 is in a process of switching between a flattened state and a folded state, the door plate 65 can be moved in a direction away from the shaft seat 61 and the door plate 65 can be moved in a direction close to the shaft seat 61. In other words, the door plate 65 is a rising / falling plate body, and the door plate 65 can be connected to the shaft seat 61 in a rising / falling manner. Specifically, in a process of unfolding the foldable display device 3, the door plate 65 moves in a direction away from the shaft seat 61, that is, the door plate 65 gradually rises to support the flexible display 7.In a process of folding the foldable display device 3, the door plate 65 moves in a direction close to the shaft seat 61, that is, the door plate 65 gradually descends to cooperate with the first support plate 66 and the second support plate 67 to form a receiving space for receiving the flexible display 7.

[0049] The first support plate 66 is rotatably connected to the first bracket 62, and the first support plate 66 is slidably connected to the shaft seat 61. The first support plate 66 can rotate relative to the first bracket 62, and at the same time, the first support plate 66 can slide relative to the shaft seat 61. In addition, there are gaps between the first support plate 66 and each of the first bracket 62 and the shaft seat 61, and the gaps are configured so that the flexible circuit board 8 and the flexible heat sink 9 pass through them. The first support plate 66 includes a first support surface 660 and a first attachment surface 661 opposite the first support surface 660. The first support surface 660 is used to support the flexible display 7. The first attachment surface 661 faces the shaft seat 61 and is used to attach the flexible heat sink 9.The first support plate 66 and the second support plate 67 are distributed on two sides of the door plate 65. The second support plate 67 is rotatably connected to the second bracket 63, and the second support plate 67 is slidably connected to the shaft seat 61. The second support plate 67 can rotate relative to the second bracket 63, and at the same time, the second support plate 67 can slide relative to the shaft seat 61. In addition, there are gaps between the second support plate 67 and each of the second bracket 63 and the shaft seat 61, and the gaps are configured so that the flexible circuit board 8 and the flexible heat sink 9 pass therethrough. The second support plate 67 includes a second support surface 670 and a second mounting surface 671 opposite the second support surface 670. The second support surface 670 is used to support the flexible display 7.The second mounting surface 671 faces the shaft seat 61 and is used to mount the flexible heat sink 9.

[0050] Before entering the receiving cavity 611 through the first interval 615, the flexible heat sink 9 can be attached to the first frame 4 and is connected to a first side 41 that is from the first frame 4 and that is close to the flexible display 7, and enters the receiving cavity 611 through a gap between the first support plate 66 and the shaft seat 61, a gap between the first support plate 66 and the first bracket 62, and a first interval 615. After exiting the receiving cavity 611 through the second interval 616, the flexible heat sink 9 can be attached to the second frame 5 through a gap between the second support plate 67 and the shaft seat 61 and a gap between the second support plate 67 and the second bracket 63 and is connected to a first side 51 that is from the second frame 5 and that is close to the flexible display 7.The first side 41 of the first frame 4 and the first side 51 of the second frame 5 mount the flexible display 7.

[0051] To prevent the flexible heat sink 9 from moving in a longitudinal direction when the foldable display device 3 is folded or unfolded, resulting in large-scale deformation and a positional change of the flexible heat sink 9, the flexible heat sink 9 may be arranged at two ends. Specifically, before the flexible heat sink 9 enters the receiving cavity 611, the flexible heat sink 9 is fixed to the first fixing surface 661 of the first support plate 66. After the flexible heat sink 9 leaves the receiving cavity 611, the flexible heat sink 9 is fixed to the second fixing surface 671 of the second support plate 67.That is, two opposite ends of a part of the flexible heat sink 9 in the rotary shaft assembly 6 are respectively fixed to a first fixing surface 661 belonging to the first support plate 66 and facing the shaft seat 61, and a second fixing surface 671 belonging to the second support plate 67 and facing the shaft seat 61. The flexible heat sink 9 can be fixed to the first fixing surface 661 of the first support plate 66 using a fixing structure (for example, a screw or a bolt). The flexible heat sink 9 can be fixed to the second fixing surface 671 of the second support plate 67 using a fixing structure (for example, a screw or a bolt).Alternatively, the flexible heat sink 9 can be attached to the first mounting surface 661 of the first support plate 66 using an adhesive, a snap fit, or another method. Alternatively, the flexible heat sink 9 can be attached to the second mounting surface 671 of the second support plate 67 using an adhesive, a snap fit, or another method.

[0052] To prevent a center segment of the flexible heat sink 9 from being in a suspended state of free bending, a length of a part of the flexible heat sink 9 may be shortened so that the flexible heat sink 9 is divided into two segments of similar lengths in a longitudinal direction, so that displacement and bending deformation generated when the flexible heat sink 9 is folded or unfolded by the foldable display device 3 are smaller, and the displacement and bending amount can be more easily controlled, and the flexible heat sink 9 can be located in a center segment position. Specifically, when the flexible heat sink 9 is accommodated in the accommodation cavity 611, the flexible heat sink 9 is fixed to a surface belonging to the cross member 612 and facing the housing 60.The flexible heat sink 9 can be attached to a surface of the cross member 612 in the receiving cavity 611 using a fastening structure (for example, a screw or a bolt). Alternatively, the flexible heat sink 9 can be attached to a surface of the cross member 612 in the receiving cavity 611 using an adhesive, a snap fit, or another method.

[0053] Before entering the receiving cavity 611 through the first interval 615, the flexible circuit board 8 can be connected to an electronic element fixed to the first frame 4, that is, connected to a second side 42 which is from the first frame 4 and which is remote from the flexible display 7 and located by the first positioning device, and can enter the receiving cavity 611 through a gap between the first support plate 66 and the shaft seat 61, a gap between the first support plate 66 and the first holder 62 and a first interval 615.After leaving the receiving cavity 611 through the second interval 616, the flexible circuit board 8 can be positioned by the second positioning device through a gap between the second support plate 67 and the shaft seat 61 and a gap between the second support plate 67 and the second holder 63, and is connected to an electronic element fixed to the second frame 5, that is, connected to a second side 52 that is remote from the second frame 5 and from the flexible display 7. The second side 42 of the first frame 4 is opposite to the first side 41 of the first frame 4. The second side 52 of the second frame 5 is opposite to the first side 51 of the second frame 5. The second side 42 of the first frame 4 and the second side 52 of the second frame 5 are configured to mount the electronic element.It is understood that the first side 41 of the first frame 4 and the first side 51 of the second frame 5 may also be configured to mount the electronic element.

[0054] With reference to Fig. 5, Fig. 6, Fig. 8 and Fig. 9, in a process of folding the foldable display device 3, the door plate 65 moves in a direction close to the shaft seat 61, and an end belonging to the first support plate 66 and which is close to the door plate 65 and an end belonging to the second support plate 67 and which is close to the door plate 65 move in a direction away from the door plate 65. An end belonging to the first support plate 66 and which is far from the door plate 65 and an end belonging to the second support plate 67 and which is far from the door plate 65 move close to each other, and the door plate 65, the first support plate 66, and the second support plate 67 are automatically avoided and together form an accommodating space, the accommodating space being used to accommodate the flexible display 7.

[0055] In a process of folding the foldable display device 3, the first support plate 66 and the second support plate 67 further drive the flexible heat sink 9 to move. The flexible heat sink 9 includes three parts based on a positional relationship between the first support plate 66 and the second support plate 67, and the three parts are a first part 91, a second part 92, and a third part 93, respectively. The first part 91 of the flexible heat sink 9 is located on a side belonging to the first support plate 66 and remote from the second support plate 67, the second part 92 of the flexible heat sink 9 is located between the first support plate 66 and the second support plate 67, and the third part 93 of the flexible heat sink 9 is located on a side belonging to the second support plate 67 and remote from the first support plate 66.The first part 91 of the flexible heat sink 9 is fixed to the first support plate 66 and the first frame 4, a middle position of the second part 92 of the flexible heat sink 9 is fixed to the cross member 612 between the first support plate 66 and the second support plate 67, and another part of the second part 92 of the flexible heat sink 9 is in an unfixed state between the first support plate 66 and the cross member 612 and between the second support plate 67 and the cross member 612. The third part 93 of the flexible heat sink 9 is fixed to the second support plate 67 and the second frame 5. When the first support plate 66 and the second support plate 67 drive the flexible heat sink 9 to move, a shape of the second part 92 of the flexible heat sink 9 changes and bends into an approximate heart shape and is located on outer sides of the first support plate 66, the door plate 65 and the second support plate 67.

[0056] In a process of folding the foldable display device 3, the first positioning device and the second positioning device also move simultaneously. The first positioning device and the second positioning device drive the flexible printed circuit board 8 to move. The flexible printed circuit board 8 includes three parts based on a positional relationship between the first positioning device and the second positioning device, and the three parts are a first part 83, a second part 84, and a third part 85, respectively.The first part 83 of the flexible circuit board 8 is located on a side that is away from the first positioning device and that is remote from the second positioning device, the second part 84 of the flexible circuit board 8 is located between the first positioning device and the second positioning device, and the third part 85 of the flexible circuit board 8 is located on a side that is away from the second positioning device and that is remote from the first positioning device. The first part 83 of the flexible circuit board 8 is fixed to the first positioning device and the first frame 4, and a second part 84 of the flexible circuit board 8 is in an unfixed state between the first positioning device and the second positioning device. The third part 85 of the flexible circuit board 8 is fixed to the second positioning device and the second frame 5.When the first positioning device and the second positioning device drive the flexible circuit board 8 to move, a shape of the second part 84 of the flexible circuit board 8 changes and bends into an approximate water drop and is located on outer sides of the first support plate 66, the door plate 65, and the second support plate 67.

[0057] With reference to Fig. 3, Fig. 4, Fig. 8 and Fig. 9, the door plate 65 moves in a process of unfolding the foldable display device 3 in a direction away from the shaft seat 61. When the foldable display device 3 is completely in a flattened state, a support surface 650 of the door plate 65 is flush with the first support surface 660 of the first support plate 66 and the second support surface 670 of the second support plate 67. In other words, when the foldable display device 3 is in the flattened state, the support surface 650 of the door plate 65, the first support surface 660 of the first support plate 66, and the second support surface 670 of the second support plate 67 are used to allow the flexible display 7 (as shown in Fig. 6) is in the flattened state. When the user performs a touch operation, the door plate 65, the first support plate 66, and the second support plate 67 can provide a flat and strong support for the flexible display 7, thereby improving the user's operating experience and image viewing experience.

[0058] In a process of unfolding the foldable display device 3, the first support plate 66 and the second support plate 67 further drive the flexible heat sink 9 to move. The second part 92 of the flexible heat sink 9 becomes approximately horizontal and is fixed to the first support plate 66, the cross member 612, and the second support plate 67.

[0059] In a process of unfolding the foldable display device 3, the first positioning device and the second positioning device also move simultaneously. The first positioning device and the second positioning device drive the flexible circuit board 8 to move. A shape of the second part 84 of the flexible circuit board 8 changes and is in a free bending state in the rotary shaft assembly 6.

[0060] In this application, the flexible circuit board 8 and the flexible heat sink 9 can pass through the rotary shaft assembly 6 in a same area of ​​the rotary shaft assembly 6 to effectively utilize a space of the rotary shaft assembly 6, and the flexible heat sink 9 can transfer heat from the first frame 4 to the second frame 5. The flexible circuit board 8 and the flexible heat sink 9 are redundant in the rotary shaft assembly 6 to prevent breakage of the flexible circuit board 8 and the flexible heat sink 9 and to prevent larger space occupied by the foldable display device 3.By fixing two ends of the flexible heat sink 9 to the first support plate 66 and the second support plate 67, a structure can be used within the rotary shaft assembly 6, so that displacement and bending deformation generated when the flexible heat sink 9 is folded or unfolded by the foldable display device 3 are smaller, and displacement and a bending amount can be easily controlled. The flexible circuit board 8 and the flexible heat sink 9 are redundant in the receiving cavity 611 consisting of the shaft seat 61 and the housing 60, so that the flexible circuit board 8 and the flexible heat sink 9 can be redundant in the rotary shaft assembly 6 by using a structure within the rotary shaft assembly 6.A cross member 612 is formed in the receiving cavity 611 by using the shaft seat 61, so that a case where the flexible circuit board 8 and the flexible heat sink 9 detach from the receiving cavity 611 is avoided. By fixing a center segment of the flexible heat sink 9 to the cross member 612 of the shaft seat 61, the flexible heat sink 9 can be divided into two segments of similar lengths in a longitudinal direction, so that displacement and bending deformation generated when the flexible heat sink 9 is folded or unfolded by the foldable display device 3 are smaller, and displacement and a bending amount can be more easily controlled.The flexible circuit board 8 is arranged on the first frame 4 and the second frame 5 by using the first positioning device and the second positioning device to avoid a case where displacement and bending deformation generated when the flexible circuit board 8 is folded or unfolded by the foldable display device 3 are smaller and displacement and a bending amount can be easily controlled.

[0061] See Fig. 12 to Fig. 14. Fig. 12 is a schematic sectional view of a foldable display device in a flattened state according to a second embodiment of this application; Fig. 13 is a schematic sectional view of a foldable display device in a folded state according to a second embodiment of this application; and Fig.14 is a schematic exploded view of a rotary shaft assembly of a foldable display device in a flattened state according to a second embodiment of this application. The foldable display device in the second embodiment is similar to the foldable display device in the first embodiment, and one difference is that the foldable display device 12 in the second embodiment further includes a buffer element 120, and the housing 121 in the second embodiment further includes a positioning element 1210. In particular:

[0062] To arrange the flexible printed circuit board 122 at a mid-segment position, the housing 121 further includes an inner housing surface 1211 and the positioning element 1210, and the inner housing surface 1211 faces the housing surface 1212. The positioning element 1210 may be fixedly mounted to the inner housing surface 1211 and located in the mounting cavity 1213. The positioning element 1210 may further be a structure that protrudes from the inner housing surface 1211 of the housing 121. A shaft seat 123 is located above the positioning element 1210 in the mounting cavity 1213. The receiving groove 1231 is formed on a portion of the shaft seat 123 above the positioning element 1210. The cross member 1232 is located above the positioning element 1210, is separate from the positioning element 1210, and is configured so that the flexible circuit board 122 and the flexible heat sink 124 extend therethrough.The positioning element 1210 and the cross member 1232 together clamp the flexible circuit board 122 and the flexible heat sink 124, so that the flexible circuit board 122 and the flexible heat sink 124 are clamped between the positioning element 1210 and the cross member 1232. In this case, the positioning element 1210 and the cross member 1232 together can arrange mid-segment positions of the flexible circuit board 122 and the flexible heat sink 124, so that the flexible circuit board 122 and the flexible heat sink 124 can be divided into two segments of similar lengths in a longitudinal direction. Therefore, displacement and bending deformation generated when the flexible circuit board 122 and the flexible heat sink 124 are folded or unfolded by the foldable display device 12 are similar and smaller, and displacement and a bending amount can be controlled more easily.

[0063] To prevent damage to the flexible circuit board 122 by the positioning element 1210, the buffer element 120 is further arranged between the positioning element 1210 and the cross member 1232. The buffer element 120 is arranged on the positioning element 1210 and separated from the cross member 1232. The buffer element 120 can be fixed to the positioning element 1210. The buffer element 120 is made of an elastic material, for example, rubber or foam. The buffer element 120 can prevent damage to the flexible circuit board 122 by the positioning element 1210 due to elastic deformation. In addition, the buffer element 120 can cause a connection position between the flexible circuit board 122 and the cross member 1232 to be slightly changed to avoid a risk of breakage due to the stretched flexible circuit board 122.

[0064] In this application, the positioning member 1210 can clamp the flexible circuit board 122 and the flexible heat sink 124 between the positioning member 1210 and the cross member 1232, so that the positioning member 1210 and the cross member 1232 together form a positioning point at a center segment of the flexible circuit board 122 and position the flexible circuit board 122 at a center segment position, and the flexible circuit board 122 can be divided in a longitudinal direction into two segments with similar lengths on two sides of the positioning member 1210, and therefore, displacement and bending deformation generated when the flexible circuit board 122 is folded by the foldable display device are similar and smaller, and displacement and a bending amount can be more easily controlled;and damage to the flexible circuit board 122 by the positioning member 1210 can be avoided by elastic deformation of the buffer member 120. In addition, a connection position between the flexible circuit board 122 and the cross member 1232 can be easily changed by using the buffer member 120 to avoid a risk of breakage due to the stretched flexible circuit board 122.

[0065] Finally, it should be noted that the above embodiments are used only to describe the technical solutions of this application and are not intended to be limiting. Although this application is described in detail with reference to the above exemplary embodiments, one of ordinary skill in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the spirit and scope of the technical solutions of this application.

Claims

[1] A foldable display device, the foldable display device comprising a first frame, a second frame, a rotary shaft assembly, a flexible heat sink, and a flexible circuit board, and the flexible heat sink and the flexible circuit board extend through the rotary shaft assembly; the rotary shaft assembly comprises a shaft seat, a door plate, a first support plate, and a second support plate, wherein the door plate is mounted on the shaft seat, the first support plate and the second support plate are distributed on two sides of the door plate, in a process of folding the foldable display device, an end belonging to the first support plate and which is close to the door plate and an end belonging to the second support plate and which is close to the door plate move in a direction away from the door plate, and an end belonging to the first support plate and which is remote from the door plate and an end belonging to the second support plate and which is remote from the door plate move close to each other; a first side of the first frame and a first side of the second frame are configured to mount a flexible display, a second side of the first frame and a second side of the second frame are configured to mount an electronic element, the first side of the first frame is opposite the second side of the first frame, and the first side of the second frame is opposite the second side of the second frame; the two opposite ends of the flexible heat sink are connected to the first side of the first frame and the first side of the second frame, and two opposite ends of a part of the flexible heat sink in the rotary shaft assembly are each attached to a first attachment surface belonging to the first support plate and facing the shaft seat, and a second attachment surface belonging to the second support plate and facing the shaft seat; and the two opposite ends of the flexible circuit board are connected to the second side of the first frame and the second side of the second frame. [2] The foldable display device according to claim 1, wherein the flexible heat sink covers the flexible circuit board in the rotary shaft assembly. [3] The foldable display device according to claim 1, wherein the rotary shaft assembly further comprises a housing, the shaft seat is mounted on the housing, the shaft seat and the housing together form a receiving cavity, and the flexible heat sink and the flexible circuit board are partially received in the receiving cavity. [4] Foldable display device according to claim 3, wherein a receiving groove is formed on the shaft seat, the receiving groove penetrates the shaft seat, the shaft seat and the housing together form the receiving cavity at the receiving groove, furthermore, a cross member is formed on the shaft seat at the receiving groove and the cross member is separate from the housing; and a center segment position of the flexible heat sink is attached to a surface belonging to the cross member and facing the housing. [5] A foldable display device according to claim 4, wherein the cross member extends from a first side wall of the shaft seat near the receiving groove to a second side wall opposite the first side wall and is separated from another side wall of the shaft seat near the receiving groove. [6] A foldable display device according to claim 5, wherein the cross member and another side wall of the shaft seat near the receiving groove form a first interval and a second interval, and the flexible heat sink and the flexible circuit board enter the receiving cavity through the first interval and exit the receiving cavity through the second interval. [7] The foldable display device of claim 4, wherein the housing comprises an inner housing surface and a positioning element, the positioning element is fixedly mounted to the inner housing surface and is located in the receiving cavity, and the cross member and the positioning element are separated from each other and together locate center segment positions of the flexible circuit board and the flexible heat sink. [8] The foldable display device according to claim 7, wherein the foldable display device further comprises a buffer member, the buffer member is arranged on the positioning member and is separated from the cross member, and the buffer member is configured to prevent damage to the flexible circuit board by the positioning member due to elastic deformation. [9] The foldable display device according to claim 1, wherein the foldable display device further comprises a first bracket, a second bracket, a first synchronization arm, a second synchronization arm, and a cam wheel structure; the first bracket is rotatably connected to the first support plate, the second bracket is rotatably connected to the second support plate, and the first bracket and the second bracket are rotatably connected to the shaft seat; the first synchronization arm is slidably connected to the first bracket and rotatably connected to the first bracket, and the second synchronization arm is slidably connected to the second bracket and rotatably connected to the second bracket;and the cam wheel structure is arranged on the shaft seat and includes a concave and convex structure, and the first synchronization arm and the second synchronization arm are connected to the cam wheel structure through the concave and convex structure to implement damping of the rotation of the first bracket and the second bracket.;

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