Folding display equipment

Abstract

The embodiment of the utility model provides folding display equipment, relates to the technical field of electronic products, and is used for weakening the problem of abnormal sound generated in the opening and closing process of the folding display equipment. The folding display equipment comprises a first door plate, a second door plate, a third door plate, a hinge structure and a flexible circuit board, the first door plate and the third door plate are positioned on two opposite sides of the second door plate; the hinge structure is located on one side of the second door plate. The first door plate and the third door plate are rotationally connected with the hinge structure; the flexible circuit board comprises a fixed part and a bendable part; the folding display device further comprises a limiting structure which is located between the flexible circuit board and the second door plate and covers at least part of the bendable part. By utilizing the limiting structure, the mechanical property of the flexible circuit board can be improved, the sudden change of the form of the flexible circuit board can be limited, the problem of the sudden change of the form in the opening and closing process of the folding display equipment can be effectively solved, and the problem of abnormal sound generated in the opening and closing process of the folding display equipment can be further solved.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the technical field of electronic products, and in particular to a folding display device. BACKGROUND

[0002] Due to the folding screen, a user can have a more rich visual experience while keeping portability. With the continuous breakthrough and innovation of folding screen technology, folding display devices are increasingly appearing on the market.

[0003] The folding display device connects components of two adjacent areas through a rotating shaft, and covers a complete foldable flexible screen on the surface of the rotating shaft and the components of the two adjacent areas. The components on both sides of the rotating shaft transmit various signals by using a flexible printed circuit (FPC) penetrating the rotating shaft. However, during the opening and closing process of the folding display device, the space for the rotating shaft to penetrate gradually decreases from the maximum size, which may squeeze the FPC and cause the FPC to produce abnormal sound. How to solve the abnormal sound generated during the opening and closing process of the folding display device is a problem to be solved at present. UTILITY MODEL CONTENT

[0004] Embodiments of the present application provide a folding display device, which can effectively suppress the problem of shape mutation of the flexible circuit board during the opening and closing process of the folding display device, and further weaken the abnormal sound generated during the opening and closing process of the folding display device.

[0005] To achieve the above-mentioned purpose, embodiments of the present application adopt the following technical solutions:

[0006] In a first aspect, embodiments of the present application provide a folding display device, comprising: a first door plate, a second door plate, a third door plate, a hinge structure, a flexible circuit board, and a limiting structure. The first door plate and the third door plate are located on opposite sides of the second door plate. The hinge structure is located on one side of the second door plate, and the first door plate and the third door plate are both rotationally connected with the hinge structure. In the direction from the second door plate to the first door plate, the flexible circuit board comprises a first fixed part and a bendable part connected with the first fixed part. The first fixed part is fixed on the side of the second door plate facing the hinge structure. The limiting structure is located on the side of the flexible circuit board facing the second door plate, and the limiting structure covers at least part of the bendable part.

[0007] During the opening and closing process of the folding display device, the limiting structure can improve the mechanical properties of the flexible circuit board, and also limit the shape mutation of the flexible circuit board, effectively suppress the problem of shape mutation during the opening and closing process of the folding display device, and further weaken the problem of abnormal sound generated during the opening and closing process of the folding display device.

[0008] In a possible implementation, the hinge structure includes a first end portion close to the first door panel. The part of the bendable portion is above the first end portion. The part of the limiting structure is fixed between the second door panel and the flexible circuit board, and the other part extends towards the first door panel and beyond the first end portion.

[0009] In the folding and unfolding process of the folding display device, the flexible circuit board is subjected to the extrusion force directed to the second door panel and the elastic force for maintaining its shape, and is prone to deformation towards the position of the second door panel. By extending the other part of the limiting structure towards the first door panel and beyond the first end portion, the limiting structure has a better limiting effect on the deformation of the flexible circuit board towards the position of the second door panel.

[0010] In a possible implementation, the folding display device further includes a middle frame. The middle frame includes a first portion and a second portion, and the first portion and the second portion are located on opposite sides of the hinge structure. The flexible circuit board further includes a second fixed portion and a third fixed portion, and the second fixed portion is fixed on the first portion and the third fixed portion is fixed on the second portion. The part of the flexible circuit board between the first fixed portion and the second fixed portion has a segmented slot, and the bendable portions located on opposite sides of the segmented slot include a first bendable portion and a second bendable portion. The limiting structure covers at least part of the first bendable portion and at least part of the second bendable portion.

[0011] This is because the flexible circuit board containing the segmented slot is also called a segmented flexible circuit board. For the segmented flexible circuit board, the bendable portion of the flexible circuit board of each segment is likely to have a morphological mutation. The limiting structure covers at least part of the first bendable portion and at least part of the second bendable portion, which can limit the morphological mutation of the bendable portion of each segment of the flexible circuit board.

[0012] In a possible implementation, the limiting structure includes a first limiting structure and a second limiting structure. The first limiting structure covers at least part of the first bendable portion, and the second limiting structure covers at least part of the second bendable portion. The first limiting structure and the second limiting structure are connected as one. This is because, for the segmented flexible circuit board, the widths of the two segments on both sides of the segmented slot can be different, and the morphological changes of different segments also have differences in the folding and unfolding process of the folding display device. In this way, the first limiting structure and the second limiting structure can limit the morphological changes of the first bendable portion and the second bendable portion, respectively. The one-piece design of the first limiting structure and the second limiting structure is more convenient for the processing and installation of the limiting structure.

[0013] In a possible implementation, a size of the first bendable part in the first direction is S1, a size of the second bendable part in the first direction is S2, S1 is not equal to S2. A size of the first limiting structure in the second direction is h1, a size of the second limiting structure in the second direction is h2, h1 is not equal to h2. The first direction is parallel to a length direction of the hinge structure, and the second direction is parallel to an arrangement direction of the first door plate, the second door plate, and the third door plate.

[0014] The size in the first direction is defined as a width, and the size in the second direction is defined as a length. When the widths of the two flexible circuit boards on both sides of the segmented slot are different, the morphological changes of the two flexible circuit boards during the opening and closing of the foldable display device are also different. The narrower the flexible circuit board, the greater the elastic force or extrusion force generated during the opening and closing of the foldable display device, and the longer the limiting structure required.

[0015] In a possible implementation, S1 is less than S2, and h1 is greater than h2. When the size S1 of the first bendable part in the first direction is less than the size S2 of the second bendable part in the first direction, the elastic force or extrusion force generated by the first bendable part during the opening and closing of the foldable display device is greater than the elastic force or extrusion force generated by the second bendable part, and the deformation degrees of the first bendable part and the second bendable part to the position of the second door plate are different. The size h1 of the first limiting structure in the second direction is greater than the size h2 of the second limiting structure in the second direction, and the deformation of the first bendable part and the second bendable part to the position of the second door plate can be correspondingly offset.

[0016] In a possible implementation, a side of the limiting structure facing the flexible circuit board has an insulating layer, or a surface of the flexible circuit board facing the limiting structure is provided with a film. In this way, the circuit board and the limiting structure can be prevented from being electrically connected, short circuits between different signal lines or electrical elements can be avoided, and normal operation of the circuit can be ensured.

[0017] In a possible implementation, the limiting structure includes at least one of a polyester film plate or a polyimide plate. Both the polyester film plate and the polyimide plate have good high-temperature resistance, corrosion resistance, and chemical resistance. Using the polyester film plate and the polyimide plate as the material of the limiting structure can help improve the durability and stability of the circuit board, thereby prolonging the service life of the product.

[0018] In a possible implementation, the rigidity of the bendable part is less than the rigidity of the first fixed part. During the opening and closing of the foldable display device, the rigidity of the bendable part is reduced, the limiting effect of the limiting structure on the morphological mutation of the flexible circuit board is better, the problem of morphological mutation during the opening and closing of the foldable display device can be effectively inhibited, and the problem of abnormal sound generated during the opening and closing of the foldable display device can be further weakened.

[0019] In a possible implementation, the volume fraction of the metal traces of the bendable part is less than the volume fraction of the metal traces of the first fixed part. In this way, the rigidity of the bendable part can be less than the rigidity of the first fixed part, and the limiting effect of the limiting structure on the shape mutation of the flexible circuit board is better.

[0020] In a possible implementation, the flexible circuit board includes a first layer of metal traces and a second layer of metal traces arranged in layers, and the first layer of metal traces is closer to the second door panel than the second layer of metal traces. The volume fraction of the first layer of metal traces of the bendable part is less than the volume fraction of the first layer of metal traces of the first fixed part. In this way, when the flexible circuit board is a multilayer flexible circuit board, two of the layers of the multilayer flexible circuit board, one of which is closer to the second door panel, is the first layer, and the other is the second layer. The rigidity of the first layer of the bendable part is less than the rigidity of the second layer of the bendable part, which can better adapt to the different bending radii of each layer and better cooperate with the limiting structure to limit the shape mutation of the flexible circuit board.

[0021] In a possible implementation, the first layer of metal traces is a surface layer of metal traces. In this way, for a multilayer flexible circuit board that has been processed, it is more convenient to process the first layer of metal traces as a surface layer of metal traces.

[0022] In a possible implementation, the elastic modulus of the bendable part is less than the elastic modulus of the first fixed part. In this way, the elastic modulus of the bendable part is reduced, the rigidity of the bendable part is also reduced, the probability of shape mutation of the flexible circuit board can be reduced, and the limiting structure can better cooperate with the limiting structure to limit the shape mutation of the flexible circuit board.

[0023] In a possible implementation, the flexible circuit board includes a first flexible substrate and a second flexible substrate arranged in layers, and the first flexible substrate is closer to the second door panel than the second flexible substrate. The elastic modulus of the first flexible substrate of the bendable part is less than the elastic modulus of the second flexible substrate. In this way, the rigidity of the inner layer is less than the rigidity of the outer layer, which can better adapt to the different bending radii of each layer and better cooperate with the limiting structure to limit the shape mutation of the flexible circuit board.

[0024] In a possible implementation, the flexible circuit board further includes a third flexible substrate, and the second flexible substrate is located between the first flexible substrate and the third flexible substrate. The elastic modulus of the second flexible substrate of the bendable part is less than or equal to the elastic modulus of the third flexible substrate. In this way, the rigidity of the inner layer is less than the rigidity of the middle layer and the outer layer, the rigidity of the middle layer is less than the rigidity of the outer layer, and the rigidity of the different layers of the flexible circuit board is distributed in a gradient, which can better cooperate with the limiting structure to limit the shape mutation of the flexible circuit board.

[0025] In a second aspect, the embodiments of the present application provide a folding display device, comprising a first door plate, a second door plate, a third door plate, a hinge structure and a flexible circuit board. The first door plate and the third door plate are located on two opposite sides of the second door plate. The first door plate and the third door plate are rotationally connected with the hinge structure. In the direction from the second door plate to the first door plate, the flexible circuit board comprises a first fixed part, a bendable part connected with the first fixed part, and the first fixed part is fixed on the side of the second door plate facing the hinge structure. The rigidity of the bendable part is less than the rigidity of the first fixed part.

[0026] At the position where the structure shape changes sharply, stress concentration phenomenon often occurs. This phenomenon can cause the structure made of flexible material to deform, and can also cause the structure made of brittle material to break under static load. One of the methods to reduce stress concentration is to reduce the rigidity of the stress concentration point. Rigidity is a physical quantity used to describe the ability of a structure or material to resist deformation. The bendable part is the stress concentration point of the flexible circuit board. The rigidity of the bendable part is less than the rigidity of the first fixed part, which can make the stress more evenly distributed on the flexible circuit board when subjected to external force, reducing the probability of stress concentration, thereby reducing the probability of shape mutation of the flexible circuit board. Ultimately, the abnormal sound generated by the shape mutation of the flexible circuit board during the opening and closing process of the folding display device can be reduced.

[0027] In a possible implementation, the volume fraction of the metal traces of the bendable part is less than the volume fraction of the metal traces of the first fixed part. Within the elastic limit of a structure or material, the rigidity of the structure or material can be measured by the elastic modulus. Reducing the volume fraction of the metal traces can weaken the local elastic modulus. In this way, the elastic modulus of the bendable part is weakened, the rigidity is reduced, and the elastic force of the stress concentration point of the flexible circuit board can be effectively reduced, and the abnormal sound generated by the shape mutation of the flexible circuit board during the opening and closing process of the folding display device can be reduced.

[0028] In a possible implementation, the flexible circuit board comprises a first layer of metal traces and a second layer of metal traces arranged in layers, and the first layer of metal traces is closer to the second door plate than the second layer of metal traces.

[0029] When the flexible circuit board is a multilayer flexible circuit board, each layer can have metal traces. Due to the different bending radii of each layer, the flexible circuit board layer closer to the second door plate has more redundancy and a higher probability of shape mutation. Among them, the flexible circuit board layer closest to the second door plate is the surface layer, the layer farthest from the flexible circuit board is the bottom layer, and the remaining layers are collectively referred to as the intermediate layer.

[0030] In a possible implementation, the volume fraction of the first layer metal trace of the bendable part is less than the volume fraction of the first layer metal trace of the first fixed part. In this way, when the flexible circuit board is a multi-layer flexible circuit board, two layers of the multi-layer flexible circuit board, one of which is closer to the second door panel, is the first layer, and the other is the second layer. The rigidity of the first layer of the bendable part is less than the rigidity of the second layer of the bendable part, which can better adapt to the case that the bending radius of each layer is different, and better cooperate with the limiting structure to limit the shape mutation of the flexible circuit board.

[0031] In a possible implementation, the first layer metal trace is a surface layer metal trace. In this way, when the process of the multi-layer flexible circuit board that has been processed is improved, the first layer metal trace is a surface layer metal trace, which is more convenient for processing.

[0032] In a possible implementation, the elastic modulus of the bendable part is less than the elastic modulus of the first fixed part. In this way, the elastic modulus of the bendable part is reduced, and the rigidity of the bendable part is also reduced, which can reduce the probability of shape mutation of the flexible circuit board.

[0033] In a possible implementation, the flexible circuit board includes a first flexible substrate and a second flexible substrate arranged in layers, and the first flexible substrate is closer to the second door panel than the second flexible substrate. The elastic modulus of the first flexible substrate of the bendable part is less than the elastic modulus of the second flexible substrate. In this way, the rigidity of the inner layer is less than the rigidity of the outer layer, which can reduce the probability of shape mutation of the inner layer, thereby reducing the probability of shape mutation of the flexible circuit board and reducing the probability of producing abnormal sound in the opening and closing process of the foldable display device.

[0034] In a possible implementation, the flexible circuit board further includes a third flexible substrate, and the second flexible substrate is located between the first flexible substrate and the third flexible substrate. The elastic modulus of the second flexible substrate of the bendable part is less than or equal to the elastic modulus of the third flexible substrate. In this way, the rigidity of the inner layer is less than the rigidity of the middle layer and the outer layer, and the rigidity of the middle layer is less than the rigidity of the outer layer, and the rigidity of the different layers of the flexible circuit board is distributed in a gradient. The probability of shape mutation of the inner layer can be reduced, thereby reducing the probability of shape mutation of the flexible circuit board and reducing the probability of producing abnormal sound in the opening and closing process of the foldable display device.

[0035] During the unfolding or closing process of the foldable display device, the rigidity of the bendable part of the flexible circuit board is reduced, which is more likely to deform when subjected to an external force and absorb more energy during the deformation process, thereby reducing the abnormal sound generated by the shape mutation of the flexible circuit board in the opening and closing process of the foldable display device. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 A first structure diagram of a foldable display device provided by an embodiment of the present application;

[0037] Figure 2 This is a schematic diagram of the structure of a second type of foldable display device provided in an embodiment of this application;

[0038] Figure 3 This is a schematic diagram of the structure of a foldable display device in its closed state, provided in an embodiment of this application.

[0039] Figure 4 for Figure 3 A schematic diagram of the intermediate state of the foldable display device in the diagram;

[0040] Figure 5 for Figure 3 A schematic diagram of the unfolded state of the foldable display device in the diagram;

[0041] Figure 6 for Figure 5 A two-dimensional structural diagram of a foldable display device;

[0042] Figure 7A for Figure 6 A two-dimensional structural diagram of the unfolded state of the foldable display device in the image shows that the extrusion force is greater than the elastic force, and the bendable part is arched.

[0043] Figure 7B for Figure 6 A two-dimensional structural diagram of the intermediate state of the foldable display device in the image shows that the extrusion force is greater than the elastic force, and the bendable part is arched.

[0044] Figure 7C for Figure 6 A two-dimensional structural diagram of the intermediate state of the foldable display device in the image shows that the extrusion force is less than the elastic force, and the arch of the bendable part disappears.

[0045] Figure 8 A two-dimensional structural diagram of a foldable display device with an added limiting structure in the unfolded state, provided as an embodiment of this application;

[0046] Figure 9 This is a two-dimensional structural diagram of a foldable display device in its unfolded state, provided as an embodiment of this application. The flexible circuit board of the foldable display device includes segmented slots.

[0047] Figure 10A for Figure 9 A two-dimensional structural diagram of the foldable display device from another angle, with the width of the reinforcing plate being a constant;

[0048] Figure 10B for Figure 9 A two-dimensional structural diagram of the foldable display device from another angle, showing that the width of the reinforcing plate varies with the width of each segment of the flexible circuit board;

[0049] Figure 10C forFigure 10A and Figure 10B a structure diagram of a flexible circuit board in a folding display device in

[0050] Figure 11 A two-dimensional structure diagram of a folding display device with an added limiting structure in an unfolded state is provided in embodiments of the present application, and the flexible circuit board of the folding display device comprises a segmented slot.

[0051] Figure 12A A two-dimensional structure diagram of a folding display device in another angle is provided in Figure 11 The three limiting structures can be separately arranged.

[0052] Figure 12B Another implementation of the limiting structure can be two-segmented. Figure 12A

[0053] Figure 13A A two-dimensional structure diagram of a folding display device in another angle is provided in Figure 11 The three limiting structures can be connected as a whole.

[0054] Figure 13B Another implementation of the limiting structure can be two-segmented. Figure 13A

[0055] A two-dimensional structure diagram of a folding display device in another angle is provided in Figure 14A The sizes of the three limiting structures can be different. Figure 11

[0056] Another implementation of the limiting structure can be two-segmented. Figure 14B Figure 14A A folding display device with an optimized flexible circuit board structure is provided in embodiments of the present application, and a stress concentration point is used for reducing copper distribution design.

[0057] Figure 15 A folding display device with an optimized flexible circuit board structure is provided in embodiments of the present application, and a stress concentration point is used for removing surface copper design.

[0058] Figure 16 A folding display device with an optimized flexible circuit board structure is provided in embodiments of the present application, and a stress concentration point is used for stripe copper design.

[0059] Figure 17 A folding display device with an optimized flexible circuit board structure is provided in embodiments of the present application, and a stress concentration point is used for grid copper design.

[0060] Figure 18 DETAILED DESCRIPTION

[0061] ​​​In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings.

[0062] Hereinafter, the terms "first", "second", and the like are only used for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second", and the like can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise stated, the meaning of "a plurality of" is two or more.

[0063] In addition, in the present application, the orientation terms such as "upper", "lower", and the like are defined with respect to the orientation in which the components in the drawings are placed, and it should be understood that these directional terms are relative concepts, which are used for relative description and clarification, and can be changed accordingly according to the change of the orientation in which the components are placed in the drawings.

[0064] The folding display device provided in the embodiments of the present application can be applied to various communication systems or communication protocols, such as Bluetooth (BT) communication technology, global positioning system (GPS) communication technology, global system of mobile communication (GSM) communication technology, wireless fidelity (WiFi) communication technology, wideband code division multiple access wireless (WCDMA) communication technology, long term evolution (LTE), 5G communication technology, and other future communication technologies.

[0065] The folding display device in the embodiments of the present application can be a mobile phone, a tablet computer (pad), a notebook computer, a smart home, a smart wearable device (for example, a smart watch, a smart bracelet, smart glasses, a smart helmet), a virtual reality (VR) display terminal, an augmented reality (AR) display terminal, and the like. The display terminal can also be a handheld device with wireless communication function, a computing device or other processing device connected to a wireless modem, a vehicle-mounted device, a display terminal in a 5G network, or a display terminal in a future evolved public land mobile network (PLMN), and the like, and the embodiments of the present application are not limited thereto.

[0066] This application provides a foldable display device. The foldable display device may include various electronic devices having a flexible screen and capable of changing the unfolded or folded form of the flexible screen and itself. Under different usage requirements, the foldable display device can be unfolded to a flattened state, folded to a closed state, or in an intermediate state between the flattened and closed states. That is, the foldable display device has at least two states: a flattened state and a closed state. In some cases, a third state may be further included, namely, an intermediate state between the flattened and closed states. It is understood that the intermediate state is not a unique state, but can be any one or more states between the flattened and closed states of the foldable display device.

[0067] In the embodiments of this application, the foldable display device is illustrated by taking a foldable mobile phone as an example.

[0068] In some embodiments, such as Figure 1 The diagram shows a structural representation of a foldable display device, specifically a dual-screen foldable phone. This dual-screen foldable phone includes a first housing 100a, a second housing 100b, a first printed circuit board 101a, a second printed circuit board 101b, a flexible circuit board 102, a display module 11, and a hinge structure. The display module 11 can continuously cover the first housing 100a and the second housing 100b. The first housing 100a and the second housing 100b are located on both sides of the hinge structure and are respectively connected to it. Under the action of the hinge structure, the display module 11 can be flattened and closed. The first printed circuit board 101a is connected to the second printed circuit board 101b via the flexible circuit board 102, enabling signal transmission on both sides of the hinge structure.

[0069] In one possible implementation, the portion of the display module 11 on the first housing 100a is the left half of the screen of the foldable display device, and the portion of the display module 11 on the second housing 100b is the right half of the screen of the foldable display device; that is, the foldable display device is a horizontally folding phone. Compared to foldable display devices with non-foldable screens, the foldable display device provided in this embodiment has a larger screen area within the same volume, making it more suitable for different user scenarios.

[0070] In another possible implementation, the portion of the display module 11 on the first housing 100a is the upper half of the foldable display device's screen, and the portion of the display module 11 on the second housing 100b is the lower half of the foldable display device's screen; that is, the foldable display device is a vertically folding phone. Compared to foldable display devices with non-foldable screens, the foldable display device provided in this embodiment is smaller in size for the same screen area, making it more convenient for users to carry.

[0071] In another possible implementation, with the display module 11 closed, it is positioned between the first housing 100a and the second housing 100b, meaning the foldable display device is an inward-folding phone. Compared to foldable display devices with non-foldable screens, the foldable display device provided in this embodiment has its screen protected when folded, reducing the risk of damage from direct screen exposure. This design is not only safer but also reduces the possibility of accidental touches, giving users greater peace of mind during use.

[0072] In another possible implementation, with the display module 11 closed, the first housing 100a and the second housing 100b are inside the display module 11, meaning the foldable display device is an outward-folding phone. Compared to display devices with non-foldable screens, the foldable display device provided in this embodiment is relatively lighter and more suitable for users who prioritize portability. Compared to inward-folding phones, the foldable display device provided in this embodiment has a less noticeable screen crease, making it more suitable for users who prioritize visual experience.

[0073] In some embodiments, such as Figure 2 The diagram shows the structure of another foldable display device, specifically a three-screen foldable phone. This three-screen foldable phone may include a first housing 100a, a second housing 100b, a third housing 100c, a first hinge structure, a second hinge structure, a first printed circuit board 101a, a second printed circuit board 101b, a third printed circuit board 101c, a flexible circuit board 102, and a display module 11. The display module 11 can continuously cover the first housing 100a, the second housing 100b, and the third housing 100c. The first housing 100a and the second housing 100b are located on opposite sides of the first hinge structure and are connected to it respectively. The first hinge structure is movable, allowing the first housing 100a and the second housing 100b to fold or unfold relative to each other, thus flattening and closing the display module 11 disposed on the first housing 100a and the second housing 100b. The second housing 100b and the third housing 100c are disposed on both sides of the second rotating shaft structure and are respectively connected to the second rotating shaft structure. The second rotating shaft structure is movable, so that the second housing 100b and the third housing 100c are folded or unfolded relative to each other, realizing the flattening and closing of the display module 11 disposed on the second housing 100b and the third housing 100c. The first printed circuit board 101a is connected to the second printed circuit board 101b through the flexible circuit board 102, and the second printed circuit board 101b is connected to the third printed circuit board 101c through the flexible circuit board 102, realizing signal transmission on both sides of the first rotating shaft structure and the second rotating shaft structure respectively.

[0074] The number of hinge structures in the folding display device is not limited in the embodiments of the present application. For the convenience of description, one hinge structure is described below. The hinge structure includes a first door plate, a second door plate, a third door plate, and a hinge structure. When the folding display device is a mobile phone and the number of hinge structures is one, the folding display device is described below by taking a double-screen folding mobile phone as an example. Figure 1 The direction perpendicular to the display module 11 in the unfolded state is the z direction, the direction parallel to the long side of the hinge structure is the y direction, and the direction perpendicular to the long side of the hinge structure is the x direction to establish a coordinate system. Figures 3 to 18 The coordinate system directions in the above are the same.

[0075] In some embodiments, as shown in Figure 3 , Figure 4 and Figure 5 , the folding display device is sequentially shown from the closed state to the unfolded state. The folding display device includes a hinge structure and a middle frame 204. The hinge structure includes a first door plate 201, a second door plate 202, a third door plate 203, a hinge structure 205, a reinforcing plate 206, and a flexible circuit board 102. The first door plate 201 and the third door plate 203 are located on the opposite sides of the second door plate 202. The hinge structure 205 is located on one side of the second door plate 202. The first door plate 201 and the third door plate 203 are both rotationally connected with the hinge structure 205. The first door plate 201 and the third door plate 203 can move towards or away from each other to switch the folding display device between the unfolded state and the closed state.

[0076] It should be noted that the hinge structure is usually contained in the hinge back cover, so in the embodiments of the present application, the hinge structure contained in the hinge back cover is shown. As shown in Figure 6 , it is a view along the opposite direction of the x direction. Figure 5 The middle frame 204 includes a first part 2041, a second part 2042, a third part 2043, and a fourth part 2044. The reinforcing plate 206 includes a first reinforcing plate 2061, a second reinforcing plate 2062, and a third reinforcing plate 2063. The flexible circuit board 102 includes a first fixed part B1, a second fixed part B2, and a third fixed part B3. The first reinforcing plate 2061 is fixed on the first fixed part B1, and the first fixed part B1 is fixed on the side of the second door plate 202 facing the hinge structure 205. The second reinforcing plate 2062 is fixed on the second fixed part B2, and the second fixed part B2 is fixed on the first part 2041. The third reinforcing plate 2063 is fixed on the third fixed part B3, and the third fixed part B3 is fixed on the second part 2042.

[0077] In the direction from the second door plate 202 to the first door plate 201 (as shown in the opposite direction of the x direction), Figure 6 the flexible circuit board 102 further includes a first bendable part A1 connected with the first fixed part B1.

[0078] Along the direction from the second door panel 202 to the third door panel 203 (e.g.) Figure 6 (As shown in the x direction), the flexible circuit board 102 also includes a second bendable portion A2 connected to the first fixed portion B1.

[0079] It is understandable that the structures on both sides of a hinge structure are symmetrical. When one side has a certain design, the other side can have the same design and achieve the same technical effect. For ease of explanation, the following descriptions of symmetrical structural designs will use the left side of the hinge structure as an example.

[0080] This application does not limit the method of fixing the flexible circuit board 102 and the second door panel 202. For example, the flexible circuit board 102 and the second door panel 202 can be fixed by adhesive.

[0081] This application does not limit the materials that can be selected for the reinforcing plate 206. The reinforcing plate 206 can be sheet material, such as steel plate; or, it can be glass fiber epoxy resin copper clad laminate, which can be called FR-4 material; or, other materials can be used.

[0082] This application does not limit the method of fixing the reinforcing plate 206 and the flexible circuit board 102. For example, an adhesive layer can be used to fix the flexible circuit board to the reinforcing plate. For instance, pressure-sensitive adhesive (PSD) can be used to fix the reinforcing plate and the flexible circuit board. Since PSD is an adhesive that is sensitive to pressure, it can enhance the flexibility of the flexible circuit board to adapt to increased length when it is bent.

[0083] Combination Figures 7A to 7C Analyze the closing process of the rotating shaft structure.

[0084] like Figure 7A As shown, the rotating shaft structure is in a flattened state, and the first bendable portion A1 of the flexible circuit board is subjected to an extrusion force F1 pointing towards the center of rotation and an elastic force F2 that restores its own shape. Since the extrusion force F1 is greater than the elastic force F2, the first bendable portion A1 of the flexible circuit board is arched.

[0085] like Figure 7B As shown, the rotating shaft structure is in an intermediate state, and the space through the shaft is relatively... Figure 7A When the flattened state of the flexible circuit board shrinks, the first bendable portion A1 is subjected to an extrusion force F1 pointing towards the center of rotation and an elastic force F2 that restores its shape. When the extrusion force F1 is greater than the elastic force F2, the first bendable portion A1 of the flexible circuit board still maintains its arched shape.

[0086] likeFigure 7C As shown, the rotation shaft structure is in the intermediate state, and the rotation shaft space is relative to the hinge structure Figure 7B In the intermediate state, the first bendable part A1 of the flexible circuit board is subjected to the extrusion force F1 directed to the rotation center and the elastic force F2 for restoring the shape of the first bendable part A1. When the extrusion force F1 is less than the elastic force F2, the first bendable part A1 of the flexible circuit board disappears, and the shape of the first bendable part A1 changes suddenly, thereby generating the abnormal sound.

[0087] It can be understood that the flattening process of the rotation shaft structure is from the intermediate state of the hinge structure Figure 7C to the intermediate state of the rotation shaft structure to the flattening state of the rotation shaft structure. In this process, the extrusion force F1 gradually exceeds the elastic force F2, and the first bendable part A1 of the flexible circuit board still changes suddenly, thereby generating the abnormal sound. Figure 7B Figure 7A It should be noted that the first fixed part B1 of the flexible circuit board 102 has no obvious boundary with the first bendable part A1 and the second bendable part A2. The first fixed part B1, the first bendable part A1 and the second bendable part A2 are defined to facilitate the description of the shape change of the flexible circuit board 102 in the folding and unfolding process of the folding display device.

[0088] To solve the problem of abnormal sound generated by the shape change of the flexible circuit board in the large-angle folding and unfolding process of the folding display device, the present application provides another folding display device, which will be described in detail below.

[0089] To solve the problem of abnormal sound generated by the shape change of the flexible circuit board in the large-angle folding and unfolding process of the folding display device, the present application provides another folding display device, which will be described in detail below.

[0090] To solve the problem of abnormal sound generated by the shape change of the flexible circuit board in the large-angle folding and unfolding process of the folding display device, the present application provides another folding display device, which will be described in detail below.

[0091] Figure 8 The present application provides a folding display device, which comprises a first door plate 201, a second door plate 202, a third door plate 203, a hinge structure 205, a flexible circuit board 102 and a limiting structure 300. The first door plate 201 and the third door plate 203 are located on the opposite sides of the second door plate 202. The hinge structure is located on one side of the second door plate 202. The first door plate 201 and the third door plate 203 are rotationally connected with the hinge structure 205. In the direction from the second door plate 202 to the first door plate 201, the flexible circuit board 102 comprises a first fixed part B1 and a first bendable part A1 connected with the first fixed part. The first fixed part B1 is fixed on the side of the second door plate facing the hinge structure 205. The limiting structure 300 is arranged on the side of the flexible circuit board 102 facing the second door plate 202, and the limiting structure 300 covers at least part of the first bendable part A1.

[0092] ​In a possible implementation, the limiting structure 300 is connected with the second door plate 202, and the limiting structure 300 is connected with the flexible circuit board 102. The embodiments of the present application do not limit the fixing process of the limiting structure 300, the second door plate 202 and the flexible circuit board 102. For example, the limiting structure 300, the second door plate 202 and the flexible circuit board 102 can be directly connected through a glue layer. For example, a hot pressing process can be used. The hot pressing process can be understood as converting the glue layer into a semi-solid state and having viscosity at a certain temperature, so that the limiting structure 300 and the flexible circuit board 102 are bonded.

[0093] It can be understood that the first fixed part B1 in the embodiments of the present application is the part connected with the flexible circuit board 102 and the second door plate 202. Due to the physical properties of the flexible circuit board 102, each section on the flexible circuit board 102 has a bendable characteristic. The bendable part in the embodiments of the present application specifically refers to the part that will cause a shape mutation in the folding and unfolding process of the folding display device. The bendable part is usually located in the part connected with the first fixed part B1 in the structure of the flexible circuit board 102. For example, as shown in FIG. 1, the bendable part includes a bendable part first section A1 and a bendable part second section A2. Figure 8

[0094] In the large-angle folding and unfolding process of the folding display device, the bendable part is subjected to an extrusion force directed to the rotation center and an elastic force for restoring its shape. The limiting structure 300 has an acting force on the flexible circuit board 102, which can balance the elastic force and the extrusion force of the first bendable part A1 of the flexible circuit board 102, limit the deformation of the flexible circuit board 102, effectively suppress the shape mutation problem in the folding and unfolding process of the folding display device, and thus weaken the problem of abnormal sound generated in the large-angle folding and unfolding process of the folding display device.

[0095] In some embodiments, the flexible circuit board is a multi-layer flexible circuit board. The multi-layer flexible circuit board is obtained by laminating two or more flexible circuit board together, and forming a conductive path between different layers through a metal via.

[0096] Due to the different bending radii of each layer, the closer to the second door plate, the more redundant the flexible circuit board layer, and the higher the probability of shape mutation. The number of layers of the multi-layer flexible circuit board is not limited in the embodiments of the present application. The layer closest to the second door plate is the surface layer (also referred to as the “inner layer”), and the layer farthest from the door plate is the bottom layer (also referred to as the “outer layer”). If there are remaining layers, they are collectively referred to as intermediate layers. The surface layer has the most bending redundancy and a higher probability of shape mutation.

[0097] ​It can be understood that the limiting structure is arranged between the surface layer of the flexible circuit board and the second door plate. During the large-angle opening and closing of the folding display device, the limiting structure has an acting force on the multi-layer flexible circuit board, which can balance the elastic force and extrusion force of the bendable part of the multi-layer flexible circuit board, limit the deformation of the multi-layer flexible circuit board, and thus weaken the problem of abnormal sound generated during the large-angle opening and closing of the folding display device.

[0098] In a possible implementation, as shown in Figure 8 , the hinge structure 205 includes a first end portion 205A close to the first door plate 201. Part of the first bendable part A1 is located above the first end portion 205A. Part of the limiting structure 300 is fixed between the second door plate 202 and the flexible circuit board 102, and the other part extends towards the first door plate 201 and beyond the first end portion 205A. By extending the other part of the limiting structure 300 towards the first door plate 201 and beyond the first end portion 205A, the limiting structure 300 has a better limiting effect on the deformation of the flexible circuit board 102.

[0099] It can be understood that the hinge structure 205 further includes a second end portion 205B close to the third door plate 203. Part of the second bendable part A2 is located above the second end portion 205B. Part of the limiting structure 300 is fixed between the second door plate 202 and the flexible circuit board 102, and the other part extends towards the third door plate 203 and beyond the second end portion 205B.

[0100] In a possible implementation, as shown in Figure 9 , Figure 10A and Figure 10C , the folding display device further includes a middle frame 204 and a reinforcing plate 206. The middle frame 204 includes a first portion 2041 and a second portion 2042. The first portion 2041 and the second portion 2042 are located on opposite sides of the hinge structure. The reinforcing plate 206 includes a first reinforcing plate 2061, a second reinforcing plate 2062, and a third reinforcing plate 2063. The flexible circuit board 102 further includes a second fixed portion B2 and a third fixed portion B3. The second fixed portion B2 is fixed on the first portion 2041, and the third fixed portion B3 is fixed on the second portion 2042. The first reinforcing plate 2061 is fixed on the first fixed portion B1. The second reinforcing plate 2062 is fixed on the second fixed portion B2. The third reinforcing plate 2063 is fixed on the third fixed portion B3.

[0101] In a possible implementation, the projection of the fixed part of the flexible circuit board 102 and the limiting structure 300 on the second door plate 202 is an X1 area (not shown in the figure), and the projection of the fixed part of the flexible circuit board 102 and the first reinforcing plate 2061 on the second door plate 202 is an X2 area (not shown in the figure). The X1 area and the X2 area are equal in size and coincide.

[0102] In one possible implementation, the projection of the portion of the flexible circuit board 102 and the limiting structure 300 fixed on the second door panel 202 is region X1 (not shown in the figure), and the projection of the portion of the flexible circuit board 102 and the first reinforcing plate 2061 fixed on the second door panel 202 is region X2 (not shown in the figure). Region X1 is located inside region X2.

[0103] In some embodiments, such as Figure 10C As shown, is Figure 10A The image shows a view of the flexible circuit board 102 along the z-direction. The flexible circuit board 102 may also include segmented slots 400. The segmented slots 400 penetrate the flexible circuit board 102 along its thickness direction (i.e., the z-direction), dividing the flexible circuit board 102 into multiple segments to establish connections between different circuit portions of different segments. The design of the segmented slots 400 helps to distribute stress and improve the durability and reliability of the circuit board. A flexible circuit board 102 containing segmented slots 400 is also called a segmented flexible circuit board. This application does not limit the number of segmented slots 400 on the flexible circuit board 102; for ease of explanation, the following description uses two segmented slots 400 (i.e., the first segmented slot 401 and the second segmented slot 402).

[0104] Continue as Figure 9 and Figure 10A As shown, the portion of the flexible circuit board 102 located between the first fixing portion B1 and the second fixing portion B2 has a first segmentation groove 401 and a second segmentation groove 402. The first segmentation groove 401 and the second segmentation groove 402 divide the flexible circuit board into three segments: a first segment 102a, a second segment 102b, and a third segment 102c.

[0105] This application does not limit the width of the multi-segment flexible circuit board. In some embodiments, the first segment 102a, the second segment 102b, and the third segment 102c have the same width. This design simplifies the manufacturing process and facilitates production. In other embodiments, the widths of the first segment 102a, the second segment 102b, and the third segment 102c may be different. Through the non-uniform distribution design of the multi-segment flexible circuit board, the flexible circuit board can better adapt to various space constraints and special shape requirements. In this case, since the widths of the two flexible circuit boards on both sides of the segmented slot may be different, the shape changes of different segments will also differ during the opening and closing of the folding display device.

[0106] In some embodiments, the width of the reinforcing plate 206 can be a fixed value. For example... Figure 10A As shown, the lengths of the first reinforcing plate 2061, the second reinforcing plate 2062, and the third reinforcing plate 2063 (along...) Figure 10AThe dimension in the x-direction does not vary with the width of the first segment 102a, the second segment 102b, and the third segment 102c (along the x-direction). Figure 10A It changes with the change in the dimension in the y-direction.

[0107] In other embodiments, the width of the reinforcing plate 206 can vary according to the width of different segments of the flexible circuit board. For example... Figure 10B As shown, the widths of the first segment 102a, the second segment 102b, and the third segment 102c (along...) Figure 10B The dimensions in the y-direction are S1, S2, and S3, respectively, and the lengths of the fixed portions of the first reinforcing plate 2061 and the first segment 102a (along the y-direction) are... Figure 10B The dimension in the x-direction is L11, the length of the fixed portion of the first reinforcing plate 2061 and the second segment 102b is L12, and the length of the fixed portion of the first reinforcing plate 2061 and the third segment 102c is L13. When S1, S2, and S3 satisfy S1 < S2 < S3, then L11 < L12 < L13. It is understandable that the widths of the second reinforcing plate 2062 and the third reinforcing plate 2063 also vary according to the width of different segments of the flexible circuit board, which will not be elaborated here.

[0108] This application embodiment does not limit the form of the reinforcing plate 206 for the multi-segment flexible circuit board. For ease of explanation, this application embodiment uses a fixed width for the reinforcing plate 206 as an example. To accommodate the difference in deformation of the flexible circuit boards on both sides of the segmented groove, this application embodiment... Figure 8 Further improvements will be made to the foldable display devices.

[0109] In one possible implementation, such as Figure 11 and Figure 12A As shown, the first segment 102a includes a first bendable portion, a first segment A11; the second segment 102b includes a first bendable portion, a second segment A12; and the third segment 102c includes a first bendable portion, a third segment A13. The limiting structure 300 includes a first limiting structure 301 covering at least a portion of the first bendable portion, a second limiting structure 302 covering at least a portion of the first bendable portion, a second limiting structure 302 covering at least a portion of the first bendable portion, a third limiting structure 303 covering at least a portion of the first bendable portion, a third segment A13. Thus, the first limiting structure 301, the second limiting structure 302, and the third limiting structure 303 can respectively limit the morphological changes of the first bendable portion, the first bendable portion, the second bendable portion, and the first bendable portion, the third segment A13. At this time, the X1 region ( Figure 11 and Figure 12A (not shown in the image) and the X2 region ( Figure 11 and Figure 12A (Not shown in the image) are equal in size and overlap.

[0110] It is understandable that, such as Figure 10CThe part of the flexible circuit board 102 between the first fixed part B1 and the third fixed part B3 can also have the same design if it has a segmented slot.

[0111] The number of the limiting structures is not limited in the embodiments of the present application. It can be understood that the number of the limiting structures is adapted to the number of the segments divided by the segmented slot.

[0112] In a possible implementation, as shown in Figure 12B the first limiting structure 301 can include a first block 3011 and a second block 3012, the second limiting structure 302 can include a third block 3021 and a fourth block 3022, and the third limiting structure 303 can include a fifth block 3031 and a sixth block 3032. At this time, the X1 region (not shown in Figure 12B ) is inside the X2 region (not shown in Figure 12B ). In this way, a part of the material of the limiting structure can be saved, so that the rotating shaft structure is more portable.

[0113] In a possible implementation, as shown in Figure 13A the first limiting structure 301, the second limiting structure 302 and the third limiting structure 303 are connected into one body. In this way, the processing and installation of the limiting structure 300 are more convenient. At this time, the X1 region (not shown in Figure 13A ) and the X2 region (not shown in Figure 13A ) are equal in size and coincide.

[0114] In a possible implementation, as shown in Figure 13B the first limiting structure 301 can include a first block 3011 and a second block 3012, the second limiting structure 302 can include a third block 3021 and a fourth block 3022, and the third limiting structure 303 can include a fifth block 3031 and a sixth block 3032. At this time, the X1 region (not shown in Figure 13B ) is inside the X2 region (not shown in Figure 13B ). In this way, a part of the material of the limiting structure can be saved, so that the rotating shaft structure is more portable.

[0115] In a possible implementation, as shown in Figure 14A the size of the first bendable part in the first direction (the y direction shown in Figure 14A ) is S1, the size of the second bendable part in the first direction is S2, and S1 is not equal to S2. The size of the first limiting structure 301 in the second direction (the x direction shown in Figure 14A ) is h1, the size of the second limiting structure 302 in the second direction is h2, and h1 is not equal to h2. The first direction is parallel to the length direction of the hinge structure, and the second direction is parallel to the arrangement direction of the first door plate, the second door plate and the third door plate.

[0116] The size in the first direction is defined as width, and the size in the second direction is defined as length. When the widths of the two sections of the flexible circuit board on both sides of the segmentation groove are different, the morphological changes of the two sections of the flexible circuit board during the folding and unfolding of the folding display device are also different. The narrower the flexible circuit board is, the greater the elastic force or extrusion force generated during the folding and unfolding of the folding display device is, and the longer the limiting structure required is.

[0117] In a possible implementation, as shown in Figure 14A S1 is less than S2, and h1 is greater than h2. When the size S1 of the first bendable section in the first direction is less than the size S2 of the second bendable section in the first direction, the elastic force or extrusion force generated by the first bendable section is greater than the elastic force or extrusion force generated by the second bendable section during the folding and unfolding of the folding display device, and the first bendable section and the second bendable section deform to different degrees towards the second door plate position. The size h1 of the first limiting structure 301 in the second direction is greater than the size h2 of the second limiting structure 302 in the second direction, which can correspondingly offset the deformation of the first bendable section and the second bendable section generated during the large-angle folding and unfolding of the folding display device.

[0118] For example, as shown in Figure 11 and Figure 14A The first section 102a includes a first bendable section first section A11, the second section 102b includes a first bendable section second section A12, and the third section 102c includes a first bendable section third section A13. The limiting structure 300 includes a first limiting structure 301 covering at least part of the first bendable section first section A11, a second limiting structure 302 covering at least part of the first bendable section second section A12, and a third limiting structure 303 covering at least part of the first bendable section third section A13. The size of the first bendable section first section in the first direction (y direction) is S1, the size of the first bendable section second section in the first direction is S2, and the size of the first bendable section third section in the first direction is S3. The size of the first limiting structure 301 in the second direction (x direction) is h1, the size of the second reinforcing structure 302 in the second direction is h2, and the size of the third limiting structure 303 in the second direction is h3. Because S1 < S2 < S3, h1 > h2 > h3. Figure 14A Figure 14A In a possible implementation, as shown in S1 and S2 are equal in ratio to h1 and h2. In this way, the relationship between the width of the flexible circuit board and the length of the limiting structure can be further quantified.

[0119] Figure 14A For example, the size of the first bendable section first section in the first direction (y direction) is S1, the size of the first bendable section second section in the first direction is S2, and the size of the first bendable section third section in the first direction is S3. The size of the first limiting structure 301 in the second direction (x direction) is h1, the size of the second reinforcing structure 302 in the second direction is h2, and the size of the third limiting structure 303 in the second direction is h3. Because S1 < S2 < S3, h1 > h2 > h3.

[0120] For example, the size of the first bendable section first section in the first direction (y direction) is S1, the size of the first bendable section second section in the first direction is S2, and the size of the first bendable section third section in the first direction is S3. The size of the first limiting structure 301 in the second direction (x direction) is h1, the size of the second reinforcing structure 302 in the second direction is h2, and the size of the third limiting structure 303 in the second direction is h3. Because S1 < S2 < S3, h1 > h2 > h3. Figure 14A ​The dimension of the first bendable portion in the y-direction is S1, the dimension of the second segment of the first bendable portion in the first direction is S2, and the dimension of the third segment of the first bendable portion in the first direction is S3. The first limiting structure 301 in the second direction (as shown in the y-direction) is S1, the dimension of the second segment of the first bendable portion in the first direction is S2, and the dimension of the third segment of the first bendable portion in the first direction is S3. Figure 14A The dimension of the second reinforcement structure 302 in the x-direction is h1, the dimension of the third limiting structure 303 in the x-direction is h2, and the dimension of the third limiting structure 303 in the x-direction is h3. When S1:S2:S3=1:1:1, then h1:h2:h3=1:1:1.

[0121] For example, the first bendable portion, the first segment, in the first direction ( Figure 14A The dimension of the first bendable portion in the y-direction is S1, the dimension of the second segment of the first bendable portion in the first direction is S2, and the dimension of the third segment of the first bendable portion in the first direction is S3. The first limiting structure 301 in the second direction (as shown in the y-direction) is S1, the dimension of the second segment of the first bendable portion in the first direction is S2, and the dimension of the third segment of the first bendable portion in the first direction is S3. Figure 14A The dimension of the second reinforcement structure 302 in the x-direction is h1, the dimension of the third limiting structure 303 in the x-direction is h2, and the dimension of the third limiting structure 303 in the x-direction is h3. When S1:S2:S3=1:2:2, we have h1:h2:h3=1:2:2.

[0122] In one possible implementation, combining Figure 11 and Figure 14B The first segment 102a includes a first bendable portion A11, the second segment 102b includes a first bendable portion A12, and the third segment 102c includes a first bendable portion A13. The limiting structure 300 includes a first limiting structure 301, a second limiting structure 302, and a third limiting structure 303. The first limiting structure 301 includes a first block 3011 and a second block 3012, the second limiting structure 302 includes a third block 3021 and a fourth block 3022, and the third limiting structure 303 includes a fifth block 3031 and a sixth block 3032. The first block 3011 covers at least a portion of the first bendable portion A11, the third block 3021 covers at least a portion of the first bendable portion A12, and the fifth block 3031 covers at least a portion of the first bendable portion A13. The first bendable portion A11 is in a first direction ( Figure 14A The dimension of the first bendable part in the y-direction is S1, the dimension of the second segment of the first bendable part in the first direction is S2, and the dimension of the third segment of the first bendable part in the first direction is S3. The first block 3011 in the second direction (… Figure 14A The dimension of the first block (in the x-direction) is h11, the dimension of the second block 3012 in the second direction is h21, and the dimension of the third block 3021 in the second direction is h31. Since S1 < S2 < S3, h11 > h21 > h31.

[0123] In a possible implementation, the flexible circuit board includes a flexible substrate and metal traces. The flexible substrate provides support for the metal traces, ensuring that the flexible circuit board can be bent without damage. When the flexible circuit board is a multi-layer flexible circuit board, each layer includes a flexible substrate and metal traces.

[0124] In a possible implementation, as shown in Figure 8 The limiting structure 300 is arranged between the second door plate 202 and the flexible circuit board 102, and the surface of the flexible circuit board 102 close to the limiting structure 300 has metal traces. The limiting structure 300 includes a first side close to the flexible circuit board 102 and a second side close to the second door plate 202, and the first side of the limiting structure 300 has an insulating layer. In this way, the flexible circuit board 102 and the limiting structure 300 can be prevented from being electrically connected, avoiding short circuit between different signal lines or electrical elements, and ensuring normal operation of the circuit.

[0125] In another possible implementation, the surface of the flexible circuit board 102 close to the limiting structure 300 has metal traces, and the metal traces are covered with a film. In this way, the flexible circuit board 102 and the limiting structure 300 can also be prevented from being electrically connected.

[0126] In a possible implementation, the limiting structure includes at least one of a polyester film (PET) plate or a polyimide (PI) plate. Both the PET plate and the PI plate have good high-temperature resistance, corrosion resistance and chemical resistance, which helps to improve the durability and stability of the circuit board, thereby prolonging the service life of the product.

[0127] In addition to using the limiting structure to limit the shape mutation of the bendable part of the flexible circuit board, the structure of the flexible circuit board can be further optimized to reduce the rigidity of the bendable part of the flexible circuit board, so that the probability of shape mutation of the bendable part when the folding display device is opened and closed at a large angle.

[0128] The embodiments of the present application provide a folding display device, as shown in Figure 6As shown, it comprises: a first door plate 201, a second door plate 202, a third door plate 203, a hinge structure 205 and a flexible circuit board 102. The first door plate 201 and the third door plate 203 are located on the opposite sides of the second door plate 202. The first door plate 201 and the third door plate 203 are rotationally connected with the hinge structure 205. In the direction from the second door plate 202 to the first door plate 201, the flexible circuit board comprises a first fixed part B1 and a bendable part connected with the first fixed part. The bendable part comprises a first part A1 of the bendable part and a second part A2 of the bendable part. In the direction from the second door plate 202 to the third door plate 203, the flexible circuit board 102 comprises a first fixed part B1 and a bendable part second part A2 connected with the first fixed part B1. The first fixed part B1 is fixed on the side of the second door plate 202 facing the hinge structure 205.

[0129] In order to limit the deformation of the bendable part, the present application also gives some ways that can be implemented. For example, the rigidity of the bendable part first part A1 and the bendable part second part A2 can be reduced by some technical means, so that the rigidity of the bendable part is less than the rigidity of the first fixed part B1. The following gives the implementation way of reducing the rigidity of the bendable part.

[0130] It can be understood that the flexible circuit board comprises a flexible substrate and a metal trace layer, to reduce the rigidity of the bendable part first part A1, either the method of changing the metal trace layer can be used, or the method of changing the flexible substrate can be used. The following gives the implementation way from these two angles.

[0131] The bendable part first part A1 and the bendable part second part A2 are the stress concentration points of the flexible circuit board 102. The elastic force of the stress concentration points of the flexible circuit board 102 is weakened, which can also reduce the abnormal sound generated by the shape mutation of the flexible circuit board in the folding and unfolding process of the folding display device. In the unfolding or closing process of the folding display device, the shaft space of the shaft structure gradually decreases from the maximum size, and the rigidity of the bendable part first part A1 and the bendable part second part A2 of the flexible circuit board 102 decreases, so that the elastic force and the extrusion force of the bendable part first part A1 and the bendable part second part A2 of the flexible circuit board are reduced, and the probability of deformation of the flexible circuit board to the second door plate position is reduced. Reducing the rigidity of the bendable part of the flexible circuit board can also effectively solve the problem of abnormal sound generated by the shape mutation in the folding and unfolding process of the folding display device.

[0132] The implementation way of reducing the rigidity of the bendable part of the present application embodiment is not limited, and the following scheme of reducing the rigidity of the bendable part is given. For convenience of description, the following takes the flexible circuit board without segmented slots as an example for description. It can be understood that when the flexible circuit board has segmented slots, all the technical solutions can be applied to any one segment or any several segments of the flexible circuit board.

[0133] In some embodiments, the rigidity of the bendable part can be reduced by reducing the volume fraction of the metal traces in the bendable part.

[0134] In one possible implementation, the volume fraction of the metal traces in the bendable part is less than the volume fraction of the metal traces in the first fixed part. Reducing the volume fraction of the metal traces can weaken the local modulus.

[0135] In this way, the modulus of the bendable part is weakened and the rigidity is reduced, which can effectively reduce the elastic force of the stress concentration point (i.e., the bendable part) of the flexible circuit board and weaken the abnormal sound generated by the shape mutation of the flexible circuit board during the opening and closing of the folding display device. The metal material of the metal traces in the bendable part is not limited in the embodiments of the present application. For the convenience of description, the metal traces are taken as copper wires in the following description.

[0136] As shown in FIG. 5A, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part. As shown in FIG. 5B, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part. Figure 15 As shown in FIG. 5A, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part. As shown in FIG. 5B, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part. Figure 15 As shown in FIG. 5A, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part. As shown in FIG. 5B, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part.

[0137] As shown in FIG. 5A, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part. As shown in FIG. 5B, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part. Figure 16 As shown in FIG. 5A, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part. As shown in FIG. 5B, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part. Figure 16 As shown in FIG. 5A, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part. As shown in FIG. 5B, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part.

[0138] As shown in FIG. 5A, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part. As shown in FIG. 5B, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part. Figure 17 As shown in FIG. 5A, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part. As shown in FIG. 5B, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part. Figure 17 As shown in FIG. 5A, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part. As shown in FIG. 5B, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part.

[0139] As shown in FIG. 5A, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part. As shown in FIG. 5B, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part. Figure 18 As shown in FIG. 5A, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part. As shown in FIG. 5B, the volume fraction of the metal traces in the bendable part can be reduced by the stress concentration point (i.e., the bendable part) to reduce the rigidity of the bendable part. Figure 18The first part of the bendable part has a first copper-removed area 501, which is a grid-shaped copper design. It can be understood that the second part of the bendable part has a second copper-removed area 502, which has the same design as the first copper-removed area 501.

[0140] It can be understood that when the flexible circuit board is a multi-layer flexible circuit board, the stress concentration point copper reduction, the stress concentration point copper-removed design, the grid-shaped copper design, and the stripe-shaped copper design can be applied to a certain layer of the multi-layer flexible circuit board alone or simultaneously applied to several layers of the flexible circuit board.

[0141] In a possible implementation, the flexible circuit board includes a first layer of metal traces and a second layer of metal traces arranged in layers, and the first layer of metal traces is closer to the second door panel than the second layer of metal traces. The volume fraction of the first layer of metal traces of the bendable part is less than the volume fraction of the first layer of metal traces of the first fixed part. At this time, the flexible circuit board is a multi-layer flexible circuit board. Each layer of the multi-layer flexible circuit board can have metal traces. Two of the layers of the multi-layer flexible circuit board, one of which is closer to the second door panel, is the "first layer", and the other is the "second layer". The stiffness of the first layer of the bendable part is less than the stiffness of the second layer of the bendable part, which can better adapt to the different bending radii of each layer and better cooperate with the limiting structure to limit the shape mutation of the flexible circuit board.

[0142] In a possible implementation, the flexible circuit board is a multi-layer flexible circuit board, and the layer closest to the second door panel is the surface layer. The first layer of metal traces in the above embodiment is the surface layer metal trace. In this way, for a multi-layer flexible circuit board that has been processed, it is more convenient to process the first layer of metal traces as the surface layer metal trace.

[0143] In a possible implementation, the volume fraction of the metal traces of the bendable part of each layer of the multi-layer flexible circuit board, from the layer closest to the second door panel to the layer farthest from the second door panel, is greater than the volume fraction of the metal traces of the bendable part of the previous layer. In this way, it can better adapt to the different bending radii of each layer and better cooperate with the limiting structure to limit the shape mutation of the flexible circuit board.

[0144] In some embodiments, reducing the stiffness of the bendable part can adopt a method of differentiating the elastic modulus of different layers of the multi-layer flexible circuit board.

[0145] In a possible implementation, the elastic modulus of the bendable part is less than the elastic modulus of the first fixed part. In this way, the stiffness of the bendable part is reduced, and the probability of shape mutation of the flexible circuit board can be reduced.

[0146] In a possible implementation, when the flexible circuit board is a multi-layer flexible circuit board, each layer of the flexible circuit board has a flexible substrate. For example, the multi-layer flexible circuit board includes two layers arranged in a stack. The inner layer is a first layer including a first flexible substrate. The outer layer is a second layer including a second flexible substrate. Ignoring other layers inside the flexible circuit board, the first flexible substrate and the second flexible substrate are arranged in a stack, and in terms of position, the first flexible substrate is closer to the second door panel than the second flexible substrate.

[0147] In some other examples, the elastic modulus of the first flexible substrate of the bendable part is equal to the elastic modulus of the second flexible substrate.

[0148] In some other examples, the elastic modulus of the first flexible substrate of the bendable part is less than the elastic modulus of the second flexible substrate.

[0149] That is, the inner layer adopts the first flexible substrate with a smaller elastic modulus, and the other layers adopt the second flexible substrate with a larger elastic modulus. For example, the elastic modulus of the first flexible substrate is less than 4 GPa, and the elastic modulus of the second flexible substrate is greater than 6 GPa. In this way, the rigidity of the inner layer is less than the rigidity of the other layers, which can reduce the probability of shape mutation of the inner layer, thereby reducing the probability of shape mutation of the flexible circuit board and the probability of producing abnormal sound in the folding and unfolding process of the folding display device.

[0150] For example, the multi-layer flexible circuit board includes three layers, which are an inner layer, a middle layer, and an outer layer. The inner layer adopts the first flexible substrate with an elastic modulus of 3 GPa. The middle layer and the outer layer adopt the second flexible substrate with an elastic modulus of 6.5 GPa.

[0151] In a possible implementation, the flexible circuit board further includes a third flexible substrate, and the second flexible substrate is located between the first flexible substrate and the third flexible substrate. The elastic modulus of the second flexible substrate of the bendable part is less than or equal to the elastic modulus of the third flexible substrate.

[0152] That is, the inner layer adopts the first flexible substrate with a smaller elastic modulus, the middle layer adopts the second flexible substrate with a larger elastic modulus, and the outer layer adopts the third flexible substrate. For example, the elastic modulus of the first flexible substrate is less than 4 GPa, the elastic modulus of the second flexible substrate is greater than 4 GPa and less than 6 GPa, and the elastic modulus of the third flexible substrate is greater than 6 GPa.

[0153] In this way, the rigidity of the inner layer is less than the rigidity of the middle layer and the outer layer, the rigidity of the middle layer is less than the rigidity of the outer layer, and the rigidity of different layers of the flexible circuit board is distributed in a gradient. The probability of shape mutation of the inner layer can be reduced, thereby reducing the probability of shape mutation of the flexible circuit board and the probability of producing abnormal sound in the folding and unfolding process of the folding display device.

[0154] For example, the multilayer flexible circuit board has an inner layer, a middle layer, and an outer layer. The inner layer uses a first flexible substrate with an elastic modulus of 3 GPa. The middle layer uses a second flexible substrate with an elastic modulus of 5 GPa. The outer layer uses a third flexible substrate with an elastic modulus of 6.5 GPa.

[0155] For example, the multilayer flexible circuit board has an inner layer, a first middle layer, a second middle layer, and an outer layer. The inner layer uses a first flexible substrate with an elastic modulus of 3 GPa. The first middle layer and the second middle layer both use a second flexible substrate with an elastic modulus of 5 GPa. The outer layer uses a third flexible substrate with an elastic modulus of 6.5 GPa.

[0156] It can be understood that, Figure 8 The technical solutions of adding a limiting structure in the middle and Figure 15 The optimized flexible circuit board given in the middle can be combined in the same folding display device.

[0157] For example, in an implementable folding display device, it includes a first door plate, a second door plate, a third door plate, a hinge structure, a flexible circuit board, and a limiting structure. The first door plate and the third door plate are located on the opposite sides of the second door plate. The first door plate and the third door plate are both rotationally connected with the hinge structure. In the direction from the second door plate to the first door plate, the flexible circuit board includes a first fixed part, a bendable part connected with the first fixed part, and the first fixed part is fixed on the side of the second door plate facing the hinge structure. The limiting structure is located on the side of the flexible circuit board facing the second door plate, and the limiting structure covers at least part of the bendable part. The rigidity of the bendable part is less than the rigidity of the first fixed part.

[0158] It can be understood that in the folding display device, not only is the limiting structure provided, but the rigidity of the bendable part is also designed to be less than the rigidity of the first fixed part. In this way, the limiting effect of the limiting structure on the shape mutation of the flexible circuit board is better.

[0159] In the above-mentioned device integrated with reinforcement and rigidity, the volume fraction of the metal traces of the bendable part can be less than the volume fraction of the metal traces of the first fixed part. In this way, the rigidity of the bendable part can be less than the rigidity of the first fixed part.

[0160] Alternatively, in some embodiments, the flexible circuit board is a multilayer flexible circuit board, and the first flexible substrate and the second flexible substrate can be stacked. The first flexible substrate is closer to the second door plate than the second flexible substrate. The elastic modulus of the first flexible substrate of the bendable part is less than the elastic modulus of the second flexible substrate. In this way, the rigidity of the inner layer is less than the rigidity of the outer layer, which can better adapt to the case where the bending radius of each layer is different and better cooperate with the limiting structure to limit the shape mutation of the flexible circuit board.

[0161] In the description of the present specification, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in an appropriate manner.

[0162] The above description is merely illustrative of the application and is not intended to limit the scope of the application. Any variations and modifications that fall within the scope of the application are intended to be included. Therefore, the scope of the application should be determined by the scope of the claims.

Claims

1. A foldable display device, characterized by, The folding display device comprises: a first door plate, a second door plate and a third door plate, the first door plate and the third door plate being located on opposite sides of the second door plate; a hinge structure located on one side of the second door plate, the first door plate and the third door plate being rotationally connected with the hinge structure; a flexible circuit board comprising a first fixed part, a bendable part connected with the first fixed part, the first fixed part being fixed on a side of the second door plate facing the hinge structure, in a direction from the second door plate to the first door plate; a limiting structure located on a side of the flexible circuit board facing the second door plate, the limiting structure covering at least part of the bendable part. 2.The foldable display device of claim 1, wherein, The hinge structure comprises a first end part close to the first door plate. Part of the bendable part is located above the first end part. Part of the limiting structure is fixed between the second door plate and the flexible circuit board, and the other part extends towards the first door plate and beyond the first end part.

3. The folded display device of claim 1 or 2, wherein, The folding display device further comprises a middle frame; the middle frame comprises a first part and a second part; the first part and the second part are located on opposite sides of the hinge structure; The flexible circuit board further comprises a second fixed part and a third fixed part, the second fixed part being fixed on the first part, and the third fixed part being fixed on the second part; The part of the flexible circuit board between the first fixed part and the second fixed part has a segmented groove, the bendable part located on opposite sides of the segmented groove comprising a first bendable part and a second bendable part; The limiting structure covers at least part of the first bendable part and at least part of the second bendable part. 4.The foldable display device of claim 3, wherein, The limiting structure comprises a first limiting structure and a second limiting structure; the first limiting structure covers at least part of the first bendable part, and the second limiting structure covers at least part of the second bendable part; the first limiting structure and the second limiting structure are connected as one.

5. The folding display device according to claim 4, wherein: The size of the first bendable part in a first direction is S1, and the size of the second bendable part in the first direction is S2, S1 and S2 are not equal; The size of the first limiting structure in a second direction is h1, and the size of the second limiting structure in the second direction is h2, h1 and h2 are not equal; The first direction is parallel to the length direction of the hinge structure, and the second direction is parallel to the arrangement direction of the first door plate, the second door plate and the third door plate. 6.The foldable display device of claim 5, wherein, S1 is smaller than S2, and h1 is larger than h2. 7.The foldable display device of claim 1 or 2, wherein, The side of the limiting structure facing the flexible circuit board has an insulating layer, or the surface of the flexible circuit board facing the limiting structure is provided with a film. 8.The foldable display device of claim 1 or 2, wherein, The limiting structure comprises at least one of a polyester film plate or a polyimide plate. 9.The foldable display device of claim 1 or 2, wherein, The rigidity of the bendable part is smaller than the rigidity of the first fixed part. 10.The foldable display device of claim 9, wherein, The volume fraction of metal wires of the bendable part is smaller than the volume fraction of metal wires of the first fixed part. 11.The foldable display device of claim 10, wherein, The flexible circuit board comprises a first layer of metal traces and a second layer of metal traces arranged in a stack, the first layer of metal traces being closer to the second door panel than the second layer of metal traces; the first layer of metal traces of the bendable portion has a volume fraction less than that of the first layer of metal traces of the first fixed portion. 12.The foldable display device of claim 11, wherein, The first layer of metal traces is a surface layer of metal traces. 13.The foldable display device of claim 9, wherein, The elastic modulus of the bendable portion is less than that of the first fixed portion.

14. The foldable display device of claim 13, wherein, The flexible circuit board comprises a first flexible substrate and a second flexible substrate arranged in a stack, the first flexible substrate being closer to the second door panel than the second flexible substrate; The elastic modulus of the first flexible substrate of the bendable portion is less than that of the second flexible substrate.

15. The foldable display device of claim 14, wherein, The flexible circuit board further comprises a third flexible substrate, the second flexible substrate being located between the first flexible substrate and the third flexible substrate; The elastic modulus of the second flexible substrate of the bendable portion is less than or equal to that of the third flexible substrate.

16. A foldable display device, characterized by Comprise: a first door panel, a second door panel and a third door panel, the first door panel and the third door panel being located on opposite sides of the second door panel; a hinge structure, the first door panel and the third door panel being rotationally connected with the hinge structure; a flexible circuit board, in the direction from the second door panel to the first door panel, the flexible circuit board comprises a first fixed portion and a bendable portion connected with the first fixed portion, the first fixed portion being fixed on the side of the second door panel facing the hinge structure; The stiffness of the bendable portion is less than that of the first fixed portion.

17. The folded display device of claim 16, wherein, The volume fraction of metal traces of the bendable portion is less than that of the first fixed portion.

18. The folded display device of claim 17, wherein, The flexible circuit board comprises a first layer of metal traces and a second layer of metal traces arranged in a stack, the first layer of metal traces being closer to the second door panel than the second layer of metal traces; The first layer of metal traces of the bendable portion has a volume fraction less than that of the first layer of metal traces of the first fixed portion.

19. The folded display device of claim 18, wherein, The first layer of metal traces is a surface layer of metal traces.

20. The folded display device of any of claims 16-19, wherein, The elastic modulus of the bendable portion is less than that of the first fixed portion.

21. The folded display device of claim 20, wherein, The flexible circuit board comprises a first flexible substrate and a second flexible substrate arranged in a stack, the first flexible substrate being closer to the second door panel than the second flexible substrate; The elastic modulus of the first flexible substrate of the bendable portion is less than that of the second flexible substrate.

22. The folded display device of claim 21, wherein, The flexible circuit board further comprises a third flexible substrate, the second flexible substrate being located between the first flexible substrate and the third flexible substrate; The elastic modulus of the second flexible substrate of the bendable portion is less than or equal to that of the third flexible substrate.

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