Foldable film, folding display module, display terminal device

Abstract

This application relates to the field of foldable materials, and provides a foldable film, a foldable display module, and a display terminal device. The foldable film includes a film substrate and reinforcing fibers; the film substrate includes a bendable portion, and the reinforcing fibers are formed at least on the surface of the bendable portion or embedded within the bendable portion; wherein the reinforcing fibers are metal fibers, metal oxide fibers, or carbon nanotube fibers. The foldable film provided by this application improves the elastic modulus of the foldable film and reduces its creep properties by introducing metal fibers, metal oxide fibers, or carbon nanotube fibers into the surface of the bendable area or within the bendable portion of the film substrate, allowing the creases generated after folding to recover, thus improving the folding performance of the foldable film.

Description

Technical Field

[0001] This application belongs to the field of foldable materials technology, and in particular relates to a foldable film, a foldable display module, and a display terminal device. Background Technology

[0002] Foldable screen terminal products are a new type of terminal product with both a folded and unfolded state, such as foldable screen collectibles. When folded, the size of a foldable screen terminal product is comparable to that of current candybar terminal products on the market, making it easy to carry; when unfolded, its screen size can double or even more, enabling it to deliver powerful entertainment interactivity and a widescreen experience.

[0003] Flexible screens are key to realizing foldable screen terminal products. However, current flexible AMOLED screens are prone to developing irreversible creases in the bending areas after repeated folding. The main reason for these creases is that most of the layers in flexible AMOLED screens are composite material films and optically transparent films (including photosensitive transparent films), which exhibit creep, softening, viscoelastic, or plastic properties. When the screen is statically bent for a long time or dynamically bent multiple times, residual strain accumulates, resulting in permanent creases. Summary of the Invention

[0004] The purpose of this application is to provide a foldable film, a foldable display module, and a display terminal device containing the foldable display module, in order to solve the problem that existing flexible AMOLED screens are prone to irreversible creases in the bending area after repeated folding.

[0005] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0006] A first aspect of this application provides a foldable film, including a film substrate and reinforcing fibers; the film substrate includes a bendable portion, and the reinforcing fibers are formed at least on the surface of the bendable portion or embedded inside the bendable portion;

[0007] The reinforcing fiber is a metal fiber, a metal oxide fiber, or a carbon nanotube fiber.

[0008] The foldable film provided in this application improves the elastic modulus and reduces the creep properties of the foldable film by introducing metal fibers, metal oxide fibers, or carbon nanotube fibers onto the surface or inside the bendable portion of the film substrate. This enhances the folding performance of display modules containing the foldable film, such as flexible AMOLED screens, and allows creases formed after folding to recover. Furthermore, the introduction of reinforcing fibers increases the impact resistance of the foldable film, improving the stability and reliability of modules containing it.

[0009] In one possible implementation, the linewidth of the reinforcing fiber is less than or equal to 5 μm. In this case, when the substrate film is an optical film, the foldable film with the reinforcing fiber provides increased folding performance while still maintaining good light transmittance. Furthermore, when the linewidth of the reinforcing fiber is less than or equal to 5 μm, the reinforcing fiber is not visible to the naked eye, thus giving the foldable display module a good appearance while meeting both optical requirements and visual effects.

[0010] The length of the reinforcing fiber can be set according to the specifications of the film substrate. In one possible implementation, the radial dimension of the reinforcing fiber is consistent with that of the reinforcing fiber in the film substrate.

[0011] In one possible implementation, the spacing between the reinforcing fibers is greater than or equal to 1 mm. In this case, the foldable film can maintain good light transmittance; specifically, the light transmittance of the foldable film is greater than or equal to 85%.

[0012] In one possible implementation, the metal in the metal fiber or the metal oxide fiber is selected from at least one of gold, silver, copper, aluminum, gallium, indium, tin, palladium, nickel, cobalt, iron, manganese, and chromium. These metallic materials possess good chemical stability and ductility, which is beneficial for improving the elastic modulus of the foldable film, reducing its creep properties, and allowing creases formed after folding to be recovered. Furthermore, since these metallic elements are non-radioactive, foldable films with improved folding performance using these metallic elements can be used in everyday display terminal devices such as mobile phones, computers, and tablets.

[0013] In one possible implementation, when the reinforcing fibers are embedded at least within the bendable portion of the film matrix, the volume of the reinforcing fibers is less than or equal to 90% of the total volume of the foldable film. By embedding high-modulus reinforcing fibers into the film matrix, the elastic properties of the foldable film can be improved. Furthermore, when the volume of the reinforcing fibers is less than or equal to 90% of the total volume of the foldable film, a good balance between elasticity and stiffness can be achieved, resulting in better stability when the foldable film is bent after being laminated with other films.

[0014] In one possible implementation, the film substrate comprises two or more laminated film layers; the reinforcing fibers are disposed on the surface of at least one of the film layers, or the reinforcing fibers are embedded in at least one of the film layers. By introducing reinforcing fibers into at least one layer of the composite film, the overall elasticity of the composite film can be improved, the creep properties of the composite film can be reduced, and creases generated after folding of the composite film can be recovered, thereby improving the folding performance of the composite film.

[0015] In one possible implementation, the film substrate is an optical adhesive film, PI film, PET film, TPU film, PU film, PO film, PVC film, or flexible glass. Optical adhesive films, PI films, PET films, TPU films, PU films, PO films, PVC films, or flexible glass are widely used. By elastically modifying these films, the folding performance of various terminal products equipped with the aforementioned foldable films can be improved, solving the problem of permanent creases when flexible terminal products are folded. In one possible implementation, the film substrate is an optical adhesive film, specifically an OCA film, PSA film, PU foam film, or photosensitive film.

[0016] A second aspect of this application provides a foldable display module, comprising multiple layers of stacked material; and adjacent material layers are bonded together by an optical adhesive film;

[0017] Wherein, at least one of the material layer and the optical film is the foldable film described in the first aspect.

[0018] The foldable display module provided in this application improves the elastic modulus of the foldable display module and reduces its creep properties by introducing one or more layers of metal fibers, metal oxide fibers, or carbon nanotube fibers into the constituent film layers. This enhances the folding performance of the foldable display module and allows creases to be recovered after folding. Furthermore, the metal fibers, metal oxide fibers, or carbon nanotube fibers can simultaneously increase the elastic modulus of each material layer and the optical film between the material layers, thereby fundamentally improving the overall folding performance of the foldable display module. In addition, the introduction of reinforcing fibers can increase the impact resistance of the foldable display module, improving the stability and reliability of display terminal devices containing this foldable display module.

[0019] In one possible implementation, the linewidth of the reinforcing fiber is less than or equal to 5 μm. In this case, after introducing the reinforcing fiber into the foldable display module, the linewidth of the reinforcing fiber is constrained, and the reinforcing fiber does not significantly affect the light transmittance of the foldable display module. This improves the folding performance of the foldable display module while maintaining good light transmittance. Furthermore, when the linewidth of the reinforcing fiber is less than or equal to 5 μm, the reinforcing fiber is not visible to the naked eye, thus giving the foldable display module a good appearance while simultaneously meeting the optical requirements and visual effects of the display terminal device using the foldable display module.

[0020] In one possible implementation, the spacing between the reinforcing fibers is greater than or equal to 1 mm. In this case, the foldable film can maintain good light transmittance; specifically, the light transmittance of the foldable film is greater than or equal to 85%.

[0021] In one possible implementation, at least one of the material layer and the optical film includes multiple reinforcing fibers, and the multiple reinforcing fibers in the same layer are arranged in parallel. By providing parallel reinforcing fibers in one or more layers of the foldable film material layer and the optical film layer, the anisotropic film materials in the foldable display module are matched, thereby directionally improving the elastic properties of one or more film layers in a certain direction in the foldable display module, thereby improving the folding performance of the foldable display module and reducing the risk of permanent creases when the foldable display module is bent.

[0022] In one possible implementation, in one or more layers of the material layer and the optical film, multiple parallel reinforcing fibers are perpendicular to the rotation axis of the foldable display module. In another possible implementation, in one or more layers of the material layer and the optical film, the reinforcing fibers are parallel to the rotation axis of the foldable display module. In yet another possible implementation, in one or more layers of the material layer and the optical film, the reinforcing fibers form an angle with the rotation axis of the foldable display module, and the angle is not 0°, 90°, or 180°. Based on the anisotropy of the film material in the foldable display module, the above-described arrangement of the reinforcing fibers in one or more layers of the foldable display module can directionally improve the elastic properties of one or more film layers in a certain direction, thereby improving the folding performance of the foldable display module and reducing the risk of permanent creases when the foldable display module is bent.

[0023] In one possible implementation, at least one of the material layer and the optical film includes two sets of mutually perpendicular reinforcing fiber groups, and each set of reinforcing fiber groups includes multiple reinforcing fibers. In this case, the isotropic properties of the film materials in the foldable display module can be used to improve the elasticity of the foldable display module, thereby improving its folding performance and reducing the risk of permanent creases when bent. Furthermore, since the two sets of mutually perpendicular reinforcing fiber groups form a mesh structure, this mesh structure also enhances the structural stability of the foldable display module.

[0024] In one possible implementation, one set of the two sets of reinforcing fibers is perpendicular to the axis of rotation of the foldable display module, while the other set is parallel to the axis of rotation. In another possible implementation, neither set of reinforcing fibers is parallel or perpendicular to the axis of rotation of the foldable display module, and the angle between either set of reinforcing fibers and the axis of rotation is not 0°, 90°, or 180°. Based on the isotropic nature of the film material in the foldable display module, the above-described arrangement of reinforcing fibers in one or more layers of the foldable display module can directionally improve the elastic properties of one or more film layers in a specific direction, thereby improving the folding performance of the foldable display module and reducing the risk of permanent creases when the foldable display module is bent.

[0025] In one possible implementation, at least one of the material layer and the optical film includes two sets of reinforcing fiber groups, and the included angle between the two sets of reinforcing fiber groups is not 0°, 90°, or 180°. In this case, the direction of insufficient elasticity in the film layer of the foldable display module can be specifically set, thereby specifically enhancing the elasticity in one direction, improving the folding performance of the foldable display module, and reducing the risk of permanent creases when the foldable display module is bent.

[0026] In one possible implementation, one set of the two sets of reinforcing fibers is parallel to the axis of rotation of the foldable display module. In another possible implementation, one set of the two sets of reinforcing fibers is perpendicular to the axis of rotation of the foldable display module. In a third possible implementation, neither set of reinforcing fibers is parallel or perpendicular to the axis of rotation of the foldable display module. By flexibly arranging the directions of the two sets of reinforcing fibers according to the direction of the weakly elastic region in the foldable display module, the elastic performance of the foldable display module in one direction is specifically enhanced, improving the folding performance of the foldable display module and reducing the risk of permanent creases when the foldable display module is bent.

[0027] In one possible implementation, the reinforcing fibers are disposed only in the bendable portions of each film layer constituting the foldable display module. In this case, metal fibers, metal oxide fibers, or carbon nanotube fibers improve the elastic modulus of the bendable portions of the foldable display module, reduce the creep properties of this portion, and allow the creases generated after the foldable display module is folded to recover, thereby improving the folding performance of the foldable display module.

[0028] In one possible implementation, the reinforcing fibers are disposed in the bendable portions of each film layer constituting the foldable display module, as well as on the entire surface or interior of at least one film layer. In this case, metal fibers, metal oxide fibers, or carbon nanotube fibers can also improve the elastic modulus of the bendable portions of the foldable display module, reduce the creep properties of this area, and allow creases generated after folding the foldable display module to recover, thereby improving the folding performance of the foldable display module. Furthermore, by providing reinforcing fibers throughout the film layers, the impact resistance of the foldable film can be increased, improving the stability and reliability of the foldable display module.

[0029] In one possible implementation, the reinforcing fibers have different line spacing within a single material layer or a single optical film. In this case, the line spacing of the reinforcing fibers can be adjusted to address the varying degrees of improvement required in the folding performance of different parts of the foldable display module. Specifically, the line spacing can be reduced in areas of the foldable display module where folding performance requirements are high, resulting in a higher elastic modulus in those areas; conversely, the line spacing can be increased in areas of the foldable display module where folding performance requirements are high, resulting in a lower elastic modulus in those areas, thereby improving the efficiency of elastic modulus control.

[0030] In one possible implementation, the line spacing of the reinforcing fibers in the non-bending region of a single material layer or a single optical film is greater than the line spacing in the bending region. In this case, for the hinge area where the crease is most severe in the foldable display module, reinforcing fibers with a smaller line spacing are arranged, resulting in a higher elastic modulus in the hinge area and a lower elastic modulus far from the hinge area.

[0031] In one possible implementation, the spacing of the strong fibers gradually increases along the bending region of the single material layer or the single optical film towards the non-bending region. In this case, the increment of the elastic modulus in the folding display module gradually decreases along the direction away from the pivot, thereby imparting the maximum elastic modulus in the pivot region of the folding display module and improving the folding performance of that area.

[0032] In one possible implementation, the reinforcing fibers have different linewidths in a single material layer or a single optical film. In this case, the linewidth of the reinforcing fibers can be adjusted to address the varying degrees of improvement required in the folding performance of different parts of the foldable display module. Specifically, the linewidth is increased in areas of the foldable display module where folding performance requirements are higher, resulting in a higher elastic modulus in those areas, while the elastic modulus in other areas is relatively lower, thereby improving the efficiency of elastic modulus control.

[0033] In one possible implementation, the linewidth of the reinforcing fiber in the non-bending region of a single material layer or a single optical film is smaller than the linewidth in the bending region. In this case, for the hinge area where the crease is most severe in the foldable display module, the reinforcing fiber with a larger linewidth is arranged, resulting in a higher elastic modulus in the hinge area and a relatively lower elastic modulus in the non-bending area.

[0034] In one possible implementation, the linewidth of the strong fiber gradually increases along the bending region of the single material layer or the single optical film toward the non-bending region.

[0035] Based on the above embodiments, in one possible implementation, the material layer includes a surface layer, a display layer, a first support layer, and a second support layer. The display layer is disposed on one side of the surface layer, the first support layer is disposed on the side of the display layer opposite to the surface layer, and the second support layer is disposed on the side of the first support layer opposite to the display layer. In this case, the foldable display module is a foldable display screen. By adding one or more layers of metal fibers, metal oxide fibers, or carbon nanotube fibers to the above-mentioned material layer and the optical film disposed between adjacent material layers, the elastic modulus of the foldable display screen is improved, thereby improving the folding performance of the foldable display screen. The first support layer and the second support layer provide support for different material layers or modules.

[0036] A third aspect of this application provides a display terminal device, including the foldable display module described in the second aspect of this application.

[0037] The display terminal device provided in this application, due to the inclusion of the aforementioned foldable display module, has an increased overall elastic modulus, allowing creases formed after folding to be recovered, thus improving the folding performance of the foldable display module. Furthermore, the introduction of reinforcing fibers can increase the impact resistance of the foldable display module, thereby improving the stability and reliability of the display terminal device containing this foldable display module. Attached Figure Description

[0038] Figure 1 This is a schematic diagram showing the reinforcing fibers parallel to the pivot of the folding display module provided in an embodiment of this application;

[0039] Figure 2 This is a schematic diagram showing the reinforcing fibers perpendicular to the pivot of the folding display module, as provided in an embodiment of this application.

[0040] Figure 3 This is a schematic diagram showing that the reinforcing fiber provided in the embodiments of this application is neither perpendicular to nor parallel to the hinge of the folding display module;

[0041] Figure 4This is a schematic diagram of a set of vertical reinforcing fiber groups perpendicular to the folding display module pivot axis provided in the embodiments of this application;

[0042] Figure 5 This is a schematic diagram of a set of vertical reinforcing fiber groups provided in the embodiments of this application that are neither perpendicular to nor parallel to the folding display module pivot.

[0043] Figure 6 This is a schematic diagram of a group of cross-reinforced fibers parallel to the pivot axis of the folding display module provided in the embodiments of this application;

[0044] Figure 7 This is a schematic diagram of two groups of cross-reinforced fibers provided in the embodiments of this application, which are neither perpendicular to nor parallel to the folding display module pivot.

[0045] Figure 8 This is a schematic diagram showing that the line width of the reinforcing fiber in the non-bending region of the film substrate is smaller than the line width in the bending region, according to an embodiment of this application.

[0046] Figure 9 This is a schematic diagram showing that the line spacing of the reinforcing fibers in the non-bending area of ​​the film substrate is greater than the line spacing in the bending area, according to an embodiment of this application. Detailed Implementation

[0047] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0048] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0049] In this application, "at least one (layer)" means one or more, and "more than one (layer)" means two or more (layers). "At least one (layer)" or similar expressions refer to any combination of these items, including any combination of a single (layer) or a plurality of (layers). For example, "at least one (layer) of a, b, or c", or "at least one (layer) of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can each be a single (layer) or multiple (layers).

[0050] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0051] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0052] The terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0053] The term "AMOLED" is an abbreviation for "Active-matrix organic light-emitting diode," which refers to an active-matrix organic light-emitting diode.

[0054] The term "PI" is an abbreviation for "Polyimide," which stands for polyimide.

[0055] The term "PET" is an abbreviation for "polyethylene terephthalate," which stands for polyethylene terephthalate, commonly known as polyester resin.

[0056] The term "TPU" is an abbreviation for "Thermoplastic polyurethanes," which refers to thermoplastic polyurethane elastomers.

[0057] The term "PU" is an abbreviation for "Poly Urethane," meaning polyurethane.

[0058] The term "PO" is an abbreviation for "polyolefin," which refers to a polyolefin copolymer.

[0059] The term "PVC" is an abbreviation for "Polyvinyl chloride," which stands for polyvinyl chloride.

[0060] The term "OCA" is an abbreviation for "Optically Clear Adhesive," meaning optical adhesive.

[0061] The term "PSA" is an abbreviation for "pressure sensitive adhesive".

[0062] The term "PU" is an abbreviation for "polyurethane," meaning polyurethane.

[0063] Creases are easily formed during the folding process of flexible screens, which not only affects the image quality of the screen display and reduces the visual experience for consumers, but also reduces the lifespan of foldable display devices. To improve the crease problem of flexible screens, researchers have conducted extensive research and proposed various solutions. One approach involves adjusting the bending shape of the flexible screen's bending area, such as the bending shape and radius, in conjunction with the hinge mechanism to achieve a crease-free design, for example, a teardrop or U-shape. Another approach involves adjusting the screen's layer distribution and thickness, designing different layering schemes, accumulating a large amount of experimental and simulation data, and summarizing patterns to design crease-free layering schemes. However, whether adjusting the bending shape or the screen's layer distribution and thickness, extensive experimental testing and simulation are required. Furthermore, the adjustment of the bending shape must be continuously matched and integrated with the hinge design. Only with sufficient test results can analysis be performed. Therefore, summarizing patterns to guide design is costly and time-consuming. In addition, some researchers have developed composite films and optical films with low creep and high elasticity based on the material properties themselves to improve the elastic properties of the layered materials. However, modified membrane material solutions require laboratory research in the field of materials, which has a long development cycle and uncertain development results.

[0064] In view of this, embodiments of this application provide a display terminal device equipped with a foldable display module. The display terminal device provided in this application includes, but is not limited to, mobile or fixed display terminals with displays such as mobile phones, tablets, laptops, handheld computers, wearable devices, virtual reality devices, and automotive pre-installed devices. Embodiments of this application improve the folding performance of the display terminal device by enhancing the elasticity of the foldable display module, thereby solving the problem of permanent creases easily forming in the display terminal device.

[0065] In this embodiment, the foldable display module, also known as a flexible screen or foldable screen, has a foldable function. The foldable display module includes a bendable portion. The so-called "bendable portion" refers to the part of the foldable display module where bending or folding occurs. Depending on the number of folds the foldable display module can undergo, it may include one or more bendable portions. Correspondingly, based on the area where the bendable portion is located, the foldable display module is further divided into a bending area and a non-bending area. The bending area refers to the area where the bendable portion of the foldable display module is located; the non-bending area refers to other areas of the foldable display module outside the bending area.

[0066] The foldable display module provided in this application includes multiple layers of stacked material layers, and adjacent material layers are bonded together by optical adhesive films. It should be understood that each film layer (including material layers and optical adhesive films) constituting the foldable display module contains a bendable portion corresponding to the foldable display module; correspondingly, each film layer constituting the foldable display module is also divided into a bending area where the bendable portion is located and a non-bending area outside the bending area.

[0067] In this embodiment, the material layer refers to a functional material layer essential for performing specific functions in the foldable display module. For example, it may be a material layer providing surface protection or a material layer providing support. In some possible implementations, the material layer is a polymer material layer, such as a PI film, PET film, TPU film, PU film, PO film, or PVC film. In some possible implementations, the material layer is flexible glass. PI films, PET films, TPU films, PU films, PO films, PVC films, and flexible glass are widely used. By elastically modifying PI films, PET films, TPU films, PU films, PO films, PVC films, and flexible glass, the folding performance of various terminal products equipped with the above-mentioned foldable films can be improved, solving the problem of permanent creases when flexible terminal products are folded.

[0068] In some possible implementations, the material layers of the foldable display module include a surface layer, a display layer, a first support layer, and a second support layer stacked sequentially. The surface layer, also known as the Cover layer, serves as the surface of the foldable display module and provides cushioning to protect it from external forces. The display layer, also known as the Panel layer, is located below the surface layer and is used to display images. In some embodiments, the surface layer can be made of PET or PI. In some embodiments, the display layer has touch functionality and is also called a touch display layer, providing image display and touch operation. In some embodiments, the display layer can be made of an AMOLED panel. The first support layer is located below the display layer, on the side of the display layer facing away from the surface layer, and is also called a Support layer, used to support and protect the display layer. In some embodiments, the first support layer can be made of steel sheet or PU foam. The second support layer is located below the first support layer, on the side of the first support layer facing away from the display layer, and is also called a Spacer layer, used to support the flexible / rigid circuit board of the foldable display module. In some embodiments, the second support layer can be made of foam.

[0069] In a foldable display module, an optical adhesive film is used to bond adjacent material layers, allowing the multi-layered material layers to form a robust whole. For example, the foldable display module includes a surface layer, a display layer, a first support layer, and a second support layer stacked sequentially, with the surface layer and display layer, the display layer and the first support layer, and the first and second support layers bonded together by an optical adhesive film. The optical adhesive film provided in this application embodiment can be an adhesive film formed from one of OCA, PSA, or PU foam adhesive. For example, the optical adhesive film is an OCA film, a PSA film, a PU foam adhesive film, or a photosensitive adhesive film; in some possible embodiments, the optical adhesive film can be a photosensitive adhesive film, i.e., an adhesive film formed after photosensitive adhesive has cured.

[0070] In this embodiment, one or more layers of the material layer and optical film in the foldable display module are foldable films containing reinforcing fibers, wherein the reinforcing fibers are metal fibers, metal oxide fibers, or carbon nanotube fibers. The aforementioned material layer and optical film serve as the film base film. By introducing metal fibers, metal oxide fibers, or carbon nanotube fibers into the film substrate, the elastic modulus of the foldable film is increased, and the creep properties of the foldable film are reduced. This improves the folding performance of display modules containing foldable films, such as flexible AMOLED screens, allowing creases generated after folding to be recovered. Furthermore, the introduction of reinforcing fibers can also increase the impact resistance of the foldable film, improving the stability and reliability of foldable display modules containing this foldable film.

[0071] In one possible implementation, the metal in the metal fiber or metal oxide fiber is selected from at least one of gold, silver, copper, aluminum, gallium, indium, tin, palladium, nickel, cobalt, iron, manganese, and chromium. These metallic materials have good chemical stability and ductility, which is beneficial for improving the elastic modulus of the foldable film, reducing the creep properties of the foldable film, and allowing the creases generated after folding of the foldable display module containing the foldable film to recover. Furthermore, since these metallic elements are non-radioactive, foldable films with improved folding performance through the aforementioned metallic elements can be used in everyday display terminal devices such as mobile phones, computers, and tablets. For example, the reinforcing fiber is selected from silver fiber, copper fiber, silver oxide fiber, and copper oxide fiber.

[0072] In some possible implementations, the material layers in the foldable display module are all foldable films containing reinforcing fibers. In this case, the elastic reinforcement of all material layers by metal fibers, metal oxide fibers, or carbon nanotube fibers effectively improves the folding performance of the foldable display module and facilitates crease recovery. In some possible implementations, the material layers and optical adhesive film in the foldable display module are all foldable films containing reinforcing fibers. In this case, metal fibers, metal oxide fibers, or carbon nanotube fibers simultaneously provide elastic reinforcement to all film layers constituting the foldable display module, maximizing the improvement of the folding performance of the foldable display module and enhancing its crease recovery capability.

[0073] In some embodiments, when the foldable display module includes a surface layer, a display layer, a first support layer, and a second support layer stacked sequentially, and the surface layer and the display layer, the display layer and the first support layer, and the first support layer and the second support layer are bonded together by an optical adhesive film, one or more of the surface layer, the display layer, the first support layer, the second support layer, and the optical adhesive film contain reinforcing fibers. For example, the surface layer contains reinforcing fibers, or the display layer contains reinforcing fibers, or the first support layer contains reinforcing fibers, or the second support layer contains reinforcing fibers, or one layer of the optical adhesive film contains reinforcing fibers. For example, two or more of the surface layer, the display layer, the first support layer, the second support layer, and the optical adhesive film contain reinforcing fibers. For example, the surface layer and the display layer contain reinforcing fibers; for example, the surface layer and the display layer contain reinforcing fibers; for example, the surface layer, the display layer, the first support layer, and the second support layer all contain reinforcing fibers; for example, each optical film contains reinforcing fibers; for example, the surface layer, the display layer, the first support layer, the second support layer, and each optical film all contain reinforcing fibers.

[0074] In this application, the method of introducing reinforcing fibers into the film substrate includes two scenarios. In the first scenario, reinforcing fibers are disposed on the surface of the film substrate, and the reinforcing fibers are formed at least on the surface of the bendable portion; wherein, the reinforcing fibers are metal fibers, metal oxide fibers, or carbon nanotube fibers. This method can directly form reinforcing fibers on the surface of the formed film substrate, which has the advantage of simple process. However, at the same time, the reinforcing fibers formed by this method are at risk of peeling off from the surface of the film substrate.

[0075] In some embodiments, reinforcing fibers are disposed on the surface of the bendable portion of the thin film substrate to modify the bendable portion, thereby increasing the elastic modulus of the bending region and improving the elastic performance of the foldable display module. In some embodiments, reinforcing fibers are disposed on the entire surface of the thin film substrate, forming a reinforcing fiber layer on the thin film substrate. This method can also increase the elastic modulus of the bending region and improve the elastic performance of the foldable display module; in addition, by disposing a reinforcing fiber layer on the surface of the thin film substrate, the impact resistance of the foldable display module can also be improved, thereby enhancing its stability and reliability.

[0076] Reinforcing fibers can be placed on the surface of a thin film substrate by spraying, coating, vacuum evaporation, vacuum ion plating, or vacuum sputtering a chemical solution containing reinforcing fibers onto the surface of the thin film substrate, and then using redox reactions, etching, lasers, or other methods to precipitate the reinforcing fibers according to a preset grid pattern.

[0077] In some embodiments, the film substrate is a polymer material layer or an optical film, and reinforcing fibers are disposed on a local surface of the film substrate, which can be achieved by the following method:

[0078] According to the preset grid of the reinforcing fibers, a chemical solution containing the reinforcing fibers is sprayed onto the surface of the film substrate, dried to form a dry film, and the dry film is exposed to obtain the reinforcing fibers with the preset grid pattern on the surface of the film substrate.

[0079] In some embodiments, the film substrate is a polymer material layer or an optical film, and reinforcing fibers are disposed on the entire surface of the film substrate, which can be achieved by the following method:

[0080] A chemical solution containing reinforcing fibers is sprayed onto at least one surface of a thin film substrate, dried to form a dry film, and then exposed to obtain a reinforcing fiber layer on the surface of the thin film substrate.

[0081] In some embodiments, the film substrate is a TUP film, PU film, PO film, or PVC film, and reinforcing fibers are disposed on a local surface of the film substrate, which can be achieved by the following method:

[0082] Based on the preset grid of the reinforcing fibers, a mask is set on the surface of the thin film substrate, and the reinforcing fibers are vacuum evaporated, vacuum ion plated, or vacuum sputtered to obtain reinforcing fibers with a preset grid pattern on the surface of the thin film substrate.

[0083] In some embodiments, the film substrate is a TPU film, PU film, PO film, or PVC film, and reinforcing fibers are disposed on a local surface of the film substrate, which can be achieved by the following method:

[0084] Reinforcing fibers with a preset grid pattern are formed on the surface of a thin film substrate by vacuum evaporation, vacuum ion plating, or vacuum sputtering on at least one surface of the substrate, and by local etching or laser engraving.

[0085] In the second embodiment, reinforcing fibers are embedded within the film substrate, with the reinforcing fibers at least embedded within the bendable portion; wherein the reinforcing fibers are metal fibers, metal oxide fibers, or carbon nanotube fibers. Compared to the first embodiment, this method is lighter and, by embedding reinforcing fibers within the film substrate, the reinforcing fibers exhibit better stability within the film substrate, but its manufacturing process becomes more complex.

[0086] In some embodiments, reinforcing fibers are embedded within the bendable portion of the film substrate to modify the bendable portion, thereby increasing the elastic modulus of the bending region and improving the elastic performance of the foldable display module. In some embodiments, reinforcing fibers are embedded throughout the entire film substrate. This method can also increase the elastic modulus of the bending region and improve the elastic performance of the foldable display module; furthermore, by embedding a reinforcing fiber layer throughout the entire film substrate, the impact resistance of the foldable display module can also be improved, thereby enhancing its stability and reliability.

[0087] In some embodiments, the volume of reinforcing fibers embedded in the film matrix is ​​less than or equal to 90% of the total volume of the foldable film. By embedding high-elastic-modulus reinforcing fibers in the film matrix, the elastic properties of the foldable film can be improved. When the volume of the reinforcing fibers is less than or equal to 90% of the total volume of the foldable film, a good balance between elasticity and stiffness can be achieved, resulting in better stability when the foldable film is bent after being combined with other films. The higher the volume content of the reinforcing fibers, the greater the force required to bend the foldable film and the foldable display module containing it, which will affect other properties of the foldable display module. In particular, when the reinforcing fiber content of two adjacent layers of the foldable film in the foldable display module is different, and the volume of the reinforcing fibers in one layer of the foldable film is greater than 90% of the total volume of the foldable film, the overall stress on the foldable display module is increased. When the foldable display module is bent, the adjacent layers are more likely to peel off due to the increased bending force.

[0088] The macroscopic structural properties of composite materials are designed based on their microstructure (such as size and shape). For example, the desired composite material can be designed by controlling the size or shape, volume fraction and orientation of the fibers.

[0089] In this embodiment, the arrangement of reinforcing fibers in the material layers and optical films of the foldable film can be flexibly adjusted in conjunction with the film layer composition of the foldable display module containing the foldable film, the material properties of each film layer, and the position of the bendable portion.

[0090] In one possible implementation, at least one layer of the material layer and optical film of the foldable display module includes multiple reinforcing fibers, and the multiple reinforcing fibers in the same layer are arranged in parallel. By providing parallel reinforcing fibers in one or more layers of the foldable film material layer and optical film layer, the anisotropic film material in the foldable display module is matched, thereby directionally improving the elastic properties of one or more film layers in a certain direction in the foldable display module, thereby improving the folding performance of the foldable display module and reducing the risk of permanent creases when the foldable display module is bent.

[0091] In some embodiments, reference Figure 1 In one or more layers of the material layer and optical adhesive film, multiple parallel reinforcing fibers 1 are arranged parallel to the rotation axis of the foldable display module. For example, the film substrate for which multiple parallel reinforcing fibers 1 are arranged parallel to the rotation axis of the foldable display module can be a PET polymer film, a TPU polymer film, a PI polymer film, or UTG glass, or an optical adhesive film such as an OCA film, PSA film, or PU foam film. When the foldable display module includes a surface layer, a display layer, a first support layer, and a second support layer stacked sequentially, and adjacent layers are bonded together by an optical adhesive film, the aforementioned multiple parallel reinforcing fibers parallel to the rotation axis of the foldable display module can be disposed in at least one of the surface layer, display layer, first support layer, and optical adhesive film of the foldable display module.

[0092] In some embodiments, reference Figure 2In one or more layers of the material layer and optical film, multiple parallel reinforcing fibers 1 are perpendicular to the rotation axis of the foldable display module. This embodiment utilizes a uniaxial reinforcing fiber reinforced film matrix. According to the mixing law of composite materials (a schematic diagram of the mixing law of composite materials and the mixing law of uniaxial fiber reinforced composite materials can be found in "McMahon and Graham,: "The Bicycle and the Walkman," Merion (1992) / https: / / www.princeton.edu / ~humcomp / bikes / design / desi_30.htm"), when multiple parallel reinforcing fibers are arranged in the film matrix, the elastic modulus of the foldable film along the tensile direction is:

[0093] E C =E F V F +E M V M

[0094] Among them, E C The modulus of elasticity of the foldable film is represented by F, where F represents the reinforcing fiber material, M represents the film matrix, and V represents the elastic modulus of the foldable film. F V represents the volume percentage of reinforcing fiber materials. M E represents the volume percentage of the thin film substrate in a foldable thin film. F E represents the elastic modulus of the reinforcing fiber material in foldable films. C V represents the elastic modulus of the thin film matrix material; and V F V M Satisfy: V M +V F =1.

[0095] For example, the film substrate for which multiple parallel reinforcing fibers 1 perpendicular to the rotation axis of the foldable display module are disposed can be a PET polymer film, a TPU polymer film, a PI polymer film, or UTG glass, or an optical adhesive film such as an OCA film, a PSA film, or a PU foam film. When the foldable display module includes a surface layer, a display layer, a first support layer, and a second support layer stacked sequentially, and adjacent layers are bonded together by an optical adhesive film, the aforementioned multiple parallel reinforcing fibers perpendicular to the rotation axis of the foldable display module can be disposed in at least one of the surface layer, display layer, first support layer, and optical adhesive film of the foldable display module.

[0096] In some embodiments, reference Figure 3In one or more layers of the material layer and optical adhesive film, multiple parallel reinforcing fibers 1 form an angle with the pivot of the foldable display module, and the angle is not 0°, 90°, or 180°, that is, the multiple parallel reinforcing fibers 1 are neither parallel nor perpendicular to the pivot of the foldable display module. For example, the film substrate for which the multiple parallel reinforcing fibers 1 are set parallel to the pivot of the foldable display module can be a PET polymer film, a TPU polymer film, a PI polymer film, or UTG glass, or an optical adhesive film such as an OCA film, a PSA film, or a PU foam film. When the foldable display module includes a surface layer, a display layer, a first support layer, and a second support layer stacked sequentially, and adjacent layers are bonded together by an optical adhesive film, the multiple parallel reinforcing fibers forming an angle not of 0°, 90°, or 180° with the pivot of the foldable display module can be disposed in at least one of the surface layer, display layer, first support layer, and optical adhesive film of the foldable display module.

[0097] According to the embodiments of this application, based on the anisotropy of the film material in the foldable display module, one or more layers in the foldable display module are modified by the above-mentioned parallel reinforcing fibers, thereby improving the elastic properties of one or more film layers in a certain direction, thereby improving the folding performance of the foldable display module and reducing the risk of permanent creases when the foldable display module is bent.

[0098] In some embodiments, exemplarily, the foldable display module includes a surface layer, a display layer, a first support layer, and a second support layer stacked sequentially, with adjacent layers bonded together by an optical adhesive film. Exemplarily, the surface layer contains a plurality of parallel reinforcing fibers, which are parallel to the rotation axis, thereby enhancing the strength of the foldable display module in the direction parallel to the rotation axis. Exemplarily, both the surface layer and the display layer have a plurality of parallel reinforcing fibers, which are parallel to the rotation axis, thereby enhancing the elastic modulus and strength of the foldable display module in the direction parallel to the rotation axis.

[0099] In one possible implementation, at least one layer of the material layer and optical film of the foldable display module includes two sets of mutually perpendicular reinforcing fiber groups (also known as "vertical reinforcing fiber groups"), and each set of reinforcing fiber groups includes multiple reinforcing fibers. In this case, the elastic properties of the foldable display module can be improved by targeting the isotropy of the film layer materials in the foldable display module, thereby improving the folding performance of the foldable display module and reducing the risk of permanent creases when the foldable display module is bent. Moreover, since the two sets of mutually perpendicular reinforcing fiber groups form a mesh structure, the mesh structure can also enhance the structural stability of the foldable display module. The film substrate in which the two sets of mutually perpendicular reinforcing fiber groups are provided can be a PET polymer film, a TPU polymer film, a PI polymer film, or UTG glass, or an optical film such as an OCA film, a PSA film, or a PU foam film. In some embodiments, the foldable display module includes a surface layer, a display layer, a first support layer and a second support layer stacked sequentially, with adjacent layers bonded together by an optical adhesive film. At least one of the surface layer, display layer, first support layer and optical adhesive film of the foldable display module is provided with two sets of mutually perpendicular reinforcing fiber groups.

[0100] In some embodiments, reference Figure 4 One set of the two sets of reinforcing fibers 2 is perpendicular to the axis of rotation of the foldable display module, and the other set is parallel to the axis of rotation of the foldable display module. In some embodiments, reference is made to... Figure 5 Both sets of reinforcing fiber groups 2 are neither parallel nor perpendicular to the axis of rotation of the foldable display module, and the angle between either set of reinforcing fiber groups 2 and the axis of rotation of the foldable display module is not 0°, 90°, or 180°. Based on the isotropic nature of the film material in the foldable display module, the above-described arrangement of reinforcing fibers in one or more layers of the foldable display module can directionally improve the elastic properties of one or more layers of film in a certain direction, thereby improving the folding performance of the foldable display module and reducing the risk of permanent creases when the foldable display module is bent.

[0101] In some exemplary embodiments, the foldable display module includes a surface layer, a display layer, a first support layer, and a second support layer stacked sequentially, with adjacent layers bonded together by an optical adhesive film. Exemplarily, the surface layer is provided with two sets of mutually perpendicular reinforcing fiber groups, wherein the two sets of mutually perpendicular reinforcing fiber groups are parallel to and perpendicular to the axis of rotation, respectively, thereby enhancing the overall elastic modulus and strength of the foldable display module.

[0102] In one possible implementation, at least one layer of the material layer and optical film of the foldable display module includes two sets of reinforcing fibers, and the angle between the two sets of reinforcing fibers is not 0°, 90°, or 180° (also known as "cross-reinforcing fiber sets"). In this case, the direction with insufficient elasticity in the film layer of the foldable display module can be specifically set to enhance the elasticity in one direction, thereby improving the folding performance of the foldable display module and reducing the risk of permanent creases when the foldable display module is bent. The film substrate with two sets of reinforcing fiber sets at angles other than 0°, 90°, or 180° can be a PET polymer film, a TPU polymer film, a PI polymer film, UTG glass, or an optical film such as an OCA film, a PSA film, or a PU foam film. In some embodiments, the foldable display module includes a surface layer, a display layer, a first support layer and a second support layer stacked sequentially, with adjacent layers bonded together by an optical adhesive film. At least one of the surface layer, display layer and first support layer of the foldable display module and the optical adhesive film contains two sets of reinforcing fiber groups with included angles not of 0°, 90° and 180°.

[0103] In some embodiments, reference Figure 6 One of the two sets of reinforcing fiber groups 2 is parallel to the axis of rotation of the foldable display module. In some embodiments, one of the two sets of reinforcing fiber groups is perpendicular to the axis of rotation of the foldable display module. In some embodiments, reference... Figure 7 Both sets of reinforcing fibers 7 are neither parallel nor perpendicular to the axis of rotation of the foldable display module. Based on the direction of the weakly elastic region in the foldable display module, the above-mentioned arrangement is used to flexibly arrange the directions of the two sets of reinforcing fibers, thereby specifically enhancing the elastic performance of the foldable display module in one direction, improving the folding performance of the foldable display module, and reducing the risk of permanent creases when the foldable display module is bent.

[0104] In some embodiments, the foldable display module includes a surface layer, a display layer, a first support layer, and a second support layer stacked sequentially, with adjacent layers bonded together by an optical adhesive film. For example, two sets of reinforcing fibers intersecting at a 30° angle are provided on the surface layer, with one set of reinforcing fibers perpendicular to the axis of rotation. This enhances the elastic modulus and strength of the foldable display module in the direction of the other set of reinforcing fibers.

[0105] Based on the above embodiments, in some examples, reinforcing fibers are only disposed in the bendable portion that makes up the foldable display module. In this case, metal fibers, metal oxide fibers, or carbon nanotube fibers improve the elastic modulus of the bendable portion of the foldable display module, reduce the creep properties of this portion, and allow the creases generated after the foldable display module is folded to recover, thereby improving the folding performance of the foldable display module.

[0106] In some embodiments, reinforcing fibers are disposed in the bendable portion constituting the foldable display module, as well as on the entire surface or within the entire surface of at least one film layer. In this case, metal fibers, metal oxide fibers, or carbon nanotube fibers can also improve the elastic modulus of the bendable portion of the foldable display module, reduce the creep properties of that area, and allow creases generated after folding the foldable display module to recover, thereby improving the folding performance of the foldable display module. Furthermore, by providing reinforcing fibers throughout the film layer, the impact resistance of the foldable film can also be increased, improving the stability and reliability of the foldable display module.

[0107] In this embodiment, the linewidth of the reinforcing fiber is related to the light transmittance of the foldable film and the foldable display module containing the foldable film. In some possible implementations, the linewidth of the reinforcing fiber is less than or equal to 5 μm. In this case, when the substrate film is an optical film, the foldable film with the reinforcing fiber provides increased folding performance while still maintaining good light transmittance. Furthermore, when the linewidth of the reinforcing fiber is less than or equal to 5 μm, the reinforcing fiber in the film is not visible to the naked eye, thus giving the foldable display module a good appearance while meeting both optical requirements and visual effects.

[0108] In one possible implementation, the linewidth of the reinforcing fibers varies within a single material layer or a single optical film. In this case, the linewidth of the reinforcing fibers can be adjusted to address the varying degrees of improvement required in the folding performance of different parts of the foldable display module. Specifically, the linewidth is increased in areas of the foldable display module where folding performance requirements are higher, resulting in a higher elastic modulus in those areas, while the elastic modulus in other areas is relatively lower, thereby improving the efficiency of elastic modulus control.

[0109] In some embodiments, reference Figure 8 In this case, the linewidth of the reinforcing fiber in the non-bending area of ​​a single material layer or a single optical film is smaller than that in the bending area. Therefore, for the hinge area where the crease is most severe in the foldable display module, a reinforcing fiber with a larger linewidth is arranged, resulting in a higher elastic modulus in the hinge area and a relatively lower elastic modulus in the non-bending area.

[0110] In some embodiments, along the direction from the bending area of ​​a single material layer or a single optical film toward the non-bending area, the linewidth of the strong fibers gradually increases in the single material layer or single optical film.

[0111] In this embodiment, the length of the reinforcing fiber can be set according to the specifications of the thin film substrate. In one possible implementation, the radial dimension of the reinforcing fiber is consistent with the direction in which the reinforcing fiber is located in the thin film substrate. For example, when the direction in which the reinforcing fiber is arranged is parallel to the longitudinal axis of the foldable display module, the length of the reinforcing fiber is consistent with the longitudinal length of the foldable display module.

[0112] In this embodiment of the application, the shape of the reinforcing fiber can be flexibly selected. For example, the cross-section of the reinforcing fiber can be rectangular, circular, elliptical, triangular, polygonal, etc., but is not limited to this.

[0113] In this embodiment, the line spacing of the reinforcing fibers is related to the light transmittance of the foldable film and the foldable display module containing the foldable film. In one possible implementation, the line spacing of the reinforcing fibers is greater than or equal to 1 mm. In this case, the foldable film can maintain good light transmittance; specifically, the light transmittance of the foldable film is greater than or equal to 85%.

[0114] In one possible implementation, the reinforcing fibers have different line spacing within a single material layer or a single optical film. In this case, the line spacing of the reinforcing fibers can be adjusted to address the varying degrees of improvement required in the folding performance of different parts of the foldable display module. Specifically, the line spacing can be reduced in areas of the foldable display module where folding performance requirements are higher, resulting in a higher elastic modulus in those areas; conversely, the line spacing can be increased in areas of the foldable display module where folding performance requirements are higher, resulting in a lower elastic modulus in those areas, thereby improving the efficiency of elastic modulus control.

[0115] In some embodiments, reference Figure 9 In this case, the line spacing of the reinforcing fibers in the non-bending area of ​​a single material layer or a single optical film is greater than that in the bending area. Therefore, for the hinge area where the crease is most severe in the foldable display module, reinforcing fibers with a smaller line spacing are arranged, resulting in a higher elastic modulus in the hinge area and a lower elastic modulus further away from the hinge area.

[0116] In some embodiments, along the bending region of a single material layer or a single optical film toward the non-bending region, the spacing of the strong fibers in the single material layer or single optical film gradually increases. In this case, along the direction away from the pivot, the increment of the elastic modulus in the folding display module gradually decreases, thereby imparting the maximum elastic modulus in the pivot region of the folding display module and improving the folding performance of that area.

[0117] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A foldable film, characterized in that, The foldable film comprises a film substrate and reinforcing fibers; the film substrate includes a bendable portion, and the reinforcing fibers are at least embedded within the bendable portion, with the volume of the reinforcing fibers being less than or equal to 90% of the total volume of the foldable film; the linewidth of the reinforcing fibers is less than or equal to 5 μm, and the line spacing of the reinforcing fibers is greater than or equal to 1 mm; the light transmittance of the foldable film is greater than or equal to 85%. The reinforcing fibers are used to increase the elastic modulus of the foldable film and reduce the creep properties of the foldable film; The reinforcing fiber is a metal fiber, a metal oxide fiber, or a carbon nanotube fiber.

2. The foldable film as described in claim 1, characterized in that, The metal in the metal fiber or the metal oxide fiber is selected from at least one of gold, silver, copper, aluminum, gallium, indium, tin, palladium, nickel, cobalt, iron, manganese, and chromium.

3. The foldable film according to any one of claims 1 to 2, characterized in that, The thin film substrate comprises two or more layers of film stacked together; The reinforcing fibers are disposed on the surface of at least one of the membrane layers, or the reinforcing fibers are embedded in at least one of the membrane layers.

4. The foldable film according to any one of claims 1 to 2, characterized in that, The film substrate is an optical adhesive film, PI film, PET film, TPU film, PU film, PO film, PVC film, or flexible glass.

5. A foldable display module, characterized in that, It includes multiple layers of material stacked together; and adjacent material layers are bonded together by an optical adhesive film; Wherein, at least one of the material layer and the optical film is the foldable film according to any one of claims 1 to 4.

6. The foldable display module as described in claim 5, characterized in that, At least one of the material layer and the optical film includes multiple reinforcing fibers, and the multiple reinforcing fibers in the same layer are arranged in parallel.

7. The foldable display module as described in claim 6, characterized in that, The reinforcing fiber is perpendicular to the pivot of the folding display module; or The reinforcing fiber is parallel to the pivot of the folding display module; or The reinforcing fiber forms an angle with the pivot of the folding display module, and the angle is not 0°, 90°, or 180°.

8. The foldable display module as described in claim 5, characterized in that, At least one of the material layer and the optical film includes two sets of mutually perpendicular reinforcing fiber groups, and each set of reinforcing fiber groups includes multiple reinforcing fibers.

9. The foldable display module as described in claim 8, characterized in that, One set of the two sets of reinforcing fibers is perpendicular to the axis of rotation of the foldable display module, and the other set is parallel to the axis of rotation of the foldable display module; or Both sets of reinforcing fiber groups are neither parallel nor perpendicular to the axis of rotation of the foldable display module, and the angle between either set of reinforcing fiber groups and the axis of rotation of the foldable display module is not 0°, 90°, or 180°.

10. The foldable display module as described in claim 5, characterized in that, At least one of the material layer and the optical film includes two sets of reinforcing fibers, and the included angle between the two sets of reinforcing fibers is not 0°, 90°, or 180°.

11. The foldable display module as described in any one of claims 5-9, characterized in that, The reinforcing fibers are disposed only in the bendable portions of each film layer constituting the foldable display module; or The reinforcing fibers are disposed in the bendable portions of each film layer constituting the foldable display module, as well as on the entire surface or interior of at least one film layer.

12. The foldable display module as described in claim 11, characterized in that, The reinforcing fibers have different line spacing in a single material layer or a single optical film.

13. The foldable display module as described in claim 12, characterized in that, The spacing of the reinforcing fibers in the non-bending region of a single material layer or a single optical film is greater than the spacing in the bending region.

14. The foldable display module as described in claim 12, characterized in that, Along the bending region of the single material layer or the single optical film toward the non-bending region, the spacing of the reinforcing fibers gradually increases in the single material layer or the single optical film.

15. The foldable display module as described in claim 11, characterized in that, The reinforcing fibers have different linewidths in a single material layer or a single optical film.

16. The foldable display module as described in claim 15, characterized in that, The linewidth of the reinforcing fiber in the non-bending region of a single material layer or a single optical film is smaller than the linewidth in the bending region.

17. The foldable display module as described in claim 15, characterized in that, Along the bending region of the single material layer or the single optical film toward the non-bending region, the linewidth of the reinforcing fiber gradually increases in the single material layer or the single optical film.

18. The foldable display module as described in any one of claims 5 to 10, 12 to 17, characterized in that, The material layer includes a surface layer, a display layer, a first support layer, and a second support layer. The display layer is disposed on one side of the surface layer, the first support layer is disposed on the side of the display layer opposite to the surface layer, and the second support layer is disposed on the side of the first support layer opposite to the display layer.

19. A display terminal device, characterized in that, Includes the foldable display module as described in any one of claims 5 to 18.

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