Flexible display module, preparation method thereof and display device

Abstract

The application relates to the technical field of flexible display devices, in particular to a flexible display module, a preparation method thereof and a display device, the flexible display module comprising a module-on-screen, a display panel and a module-under-screen which are sequentially stacked, the module-on-screen being stacked on the display surface of the display panel; the module-under-screen comprising a gel layer and a support body, the gel layer being stacked on the back surface of the display panel; wherein the creep recovery rate of the gel layer is greater than or equal to 90%, and the elastic modulus at-20 DEG C is less than or equal to 100 kPa; the material of the support body comprises a supporting base material and heat-conducting fibers, the heat-conducting fibers are dispersed in the supporting base material, the elastic modulus is 20 GPa-2000 GPa, and the mass of the heat-conducting fibers accounts for 1%-5% of the total mass of the support body, so that the flexible display module is reduced in thickness and weight while the mechanical performance, bending performance and display performance are ensured, and the light and thin design is realized. The display device using the flexible display module is also further lightened and thinned.

Description

Technical Field

[0001] This application relates to the field of flexible display equipment technology, and in particular to flexible display modules, their manufacturing methods, and display devices. Background Technology

[0002] New screen forms such as foldable screens for mobile phones, flexible wearable screens, and rollable displays often feature special structural designs. For example, foldable screens for mobile phones require dedicated under-display modules, including specialized materials and structures, to ensure structural stability and display performance during folding and unfolding. Existing under-display modules for foldable screens mainly consist of a support film, an adhesive layer, and supporting components. The support film, which can be made of polyimide (PI) or polyethylene terephthalate (PET), is bonded to the display panel using PSA adhesive. The adhesive layer can be double-sided or single-sided tape, and the supporting components can be made of stainless steel (SUS), titanium (Ti) alloy, or carbon fiber. Examples of under-display modules in some mass-produced foldable screen models include: support film + double-sided tape + titanium alloy, and support film (including PSA) + single-sided adhesive + carbon fiber. The thickness of the support film is generally 65μm. If the adhesive layer is double-sided tape, the thickness is generally 65μm. If it is single-sided tape, the thickness is generally 20μm. The thickness of the support component is generally 120μm. The overall thickness of the under-screen material is roughly between 200μm and 250μm.

[0003] In addition to the under-display module, the on-display side also requires the sequential application of layers such as the COE (Color Film on Encapsulation) layer, the OCA (Optically Clear Adhesive) layer, and the cover plate. The main manufacturing processes for existing foldable screen display modules are: first, bonding the display panel to the support film in the under-display module; then, bonding the on-display module materials (COE, OCA, and cover plate); and finally, bonding the tape and support components. The tape and support components are generally called brackets. Die-cutting factories bond the tape and support components together to create bracket assemblies, which are then bonded to the support film beneath the display panel using adhesive on the upper surface of the bracket to complete the entire display module production.

[0004] However, the multi-layer bonding process involves many steps, and the foldable screen phones made from existing flexible display modules are too thick and heavy, significantly thicker and heavier than common candybar phones. In particular, the thickness increases further after folding, which does not meet people's demand for thinner and lighter products, nor does it meet the demand for any flexible display form other than folding. Summary of the Invention

[0005] The purpose of this application is to provide a flexible display module, its manufacturing method, and a display device, aiming to solve the problem that existing flexible display modules are bulky in order to ensure performance.

[0006] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0007] In a first aspect, this application provides a flexible display module, including an on-screen module, a display panel, and an under-screen module stacked sequentially. The on-screen module is stacked on the display surface of the display panel, and the under-screen module is stacked on the back side of the display panel away from the display surface.

[0008] The under-display module includes an adhesive layer and a support. The adhesive layer is stacked on the back of the display panel, and the support is stacked on the surface of the adhesive layer facing away from the display panel.

[0009] Among them, the creep recovery rate of the colloidal layer is ≥90%, and the elastic modulus at -20℃ is ≤1000kPa;

[0010] The support material includes a supporting substrate and thermally conductive fibers. The thermally conductive fibers are dispersed in the supporting substrate. The elastic modulus of the supporting substrate is 20 GPa to 2000 GPa. The mass of the thermally conductive fibers accounts for 1% to 5% of the total mass of the support.

[0011] This application's flexible display module replaces the existing multi-layer under-display structure with a combination of a colloidal layer and a support structure. This reduces the overall thickness and weight of the flexible display module while ensuring mechanical, bending, and display performance. The support structure comprises a supporting substrate and thermally conductive fibers dispersed within it. The modulus of the supporting substrate and the content of the thermally conductive fibers work together to enhance the mechanical properties of the support structure, improving toughness and reducing stress concentration while ensuring mechanical support. Furthermore, the thermally conductive fibers optimize heat conduction paths, reduce localized heat accumulation, and facilitate timely heat dissipation, maintaining the mechanical strength of the support structure and ensuring the display stability of the flexible display module. This also contributes to the lightweight design of the support structure. The colloidal layer bonds the display panel and the support structure. The aforementioned advantages of the support structure, combined with the creep recovery rate and elastic modulus of the colloidal layer, ensure a performance match between the colloidal layer and the support structure. This reduces the thickness of the under-display module while improving interface bonding reliability, making it less prone to delamination during bending and improving bending stability. Compared to existing technologies, this application's flexible display module achieves a balance between thinness and lightness and bending reliability.

[0012] Optionally, the thermal conductivity of the thermally conductive fiber is ≥100W / (m·K).

[0013] Optionally, the thermally conductive fiber material includes at least one of carbon nanotube fiber, graphene fiber, carbon fiber, and ceramic fiber.

[0014] Optionally, the length of the thermally conductive fiber is 10μm to 20μm.

[0015] Optionally, the diameter of the thermally conductive fiber is 1μm to 10μm.

[0016] Optionally, the supporting substrate includes at least one of a metal substrate and flexible glass, wherein the metal substrate includes at least one of stainless steel, titanium alloy, aluminum alloy, and magnesium alloy.

[0017] Optionally, the support substrate has a reliability of ≥400,000 bending cycles.

[0018] Optionally, the thickness of the colloidal layer is 15μm to 75μm.

[0019] Optionally, the material of the colloidal layer includes at least one of acrylate pressure-sensitive adhesive, silicone rubber, polyurethane elastomer adhesive, and modified epoxy resin adhesive.

[0020] Optionally, the peel force between the display panel and the adhesive layer is ≥8N / cm.

[0021] Optionally, the peel force between the colloidal layer and the support is ≥8 N / cm.

[0022] Optionally, the thickness of the support can be 25μm to 150μm.

[0023] Optionally, the optical density of the colloidal layer is ≥1.5.

[0024] Optionally, the colloidal layer contains at least one of black filler, black pigment, dark brown filler, and dark brown pigment.

[0025] Optionally, the display panel includes at least one of OLED, AMOLED, mini-LED, and Micro-LED screens.

[0026] Optionally, the thickness of the display panel is 40μm to 60μm.

[0027] Optionally, the on-screen module includes a cover plate layer, an OCA layer, and a COE layer stacked sequentially, with the COE layer stacked on the display surface of the display panel.

[0028] Optionally, the thickness of the cover plate layer is 30μm to 100μm.

[0029] Optionally, the thickness of the OCA layer is 25μm to 75μm.

[0030] Optionally, the thickness of the COE layer is 5μm to 10μm.

[0031] Secondly, this application provides a method for manufacturing a flexible display module, comprising the following steps:

[0032] Provide support structure;

[0033] The raw materials of the colloidal layer are coated on one surface of the support to form a colloidal layer, thus obtaining the under-screen module;

[0034] The on-screen module is attached to the display surface of the display panel;

[0035] The under-display module is bonded to the side of the display panel away from the display surface, and the colloid layer is bonded to the surface of the display panel away from the display surface to obtain a flexible display module.

[0036] The fabrication method described in this application optimizes the material and structural composition of the under-display module. The colloidal layer is formed by coating, eliminating the need for multi-layer lamination as required by existing technologies. This simplifies the fabrication process, reduces manufacturing steps, and lowers material costs. The resulting flexible display module exhibits stable structure, excellent bending resistance and display performance, and also achieves weight reduction.

[0037] Optionally, the method for preparing the support includes the following steps:

[0038] The raw materials, including the supporting substrate and thermally conductive fibers, are sequentially mixed, sintered, and rolled to obtain the support.

[0039] Thirdly, this application provides a display device, which includes the flexible display module described above, or includes a flexible display module prepared by the preparation method described above.

[0040] Because the flexible display module of this application combines reliable bending resistance, light weight, and thinness, it can be applied to various flexible display devices to obtain corresponding display devices. These display devices can be foldable display devices, including foldable screens; rollable display devices, including wearable displays and rollable screens, capable of 360° rollable display; and sliding display devices, including sliding rail screens. Therefore, the display device of this application has excellent display performance and bending resistance, while significantly reducing thickness and weight. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the flexible display module of Embodiment 2 of this application;

[0043] Figure 2 This is a schematic diagram of the flexible display module of Embodiment 6 of this application;

[0044] Figure 3 This is a schematic diagram of the flexible display module of Embodiment 1 of this application;

[0045] Figure 4 This is a schematic diagram of the flexible display module of each embodiment of this application undergoing folding durability testing;

[0046] Figure 5 This is a schematic diagram of the interface peeling test when the flexible display module of each embodiment of this application is bent.

[0047] Figure label:

[0048] 1-On-screen module; 11-Cover layer; 12-OCA layer; 13-COE layer;

[0049] 2-Display panel;

[0050] 3-Under-screen module; 31-Colloid layer; 32-Support body. Detailed Implementation

[0051] 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.

[0052] 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.

[0053] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items.

[0054] 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.

[0055] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass in the embodiments of this application can be a well-known unit of mass in the chemical industry, such as μg, mg, g, or kg.

[0056] 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.

[0057] To ensure structural stability during folding and bending, flexible display modules typically employ a multi-layer bonding process in traditional manufacturing, consisting of a support film, adhesive layer, and support components. This multi-layer bonding works synergistically to balance mechanical support and bendability, resulting in a total module thickness often reaching 200μm–250μm. However, this multi-layered architecture presents several challenges. First, it increases the risk of interface delamination. During repeated bending, the interface between the adhesive layer and the metal support is prone to stress concentration due to modulus mismatch, leading to delamination or permanent deformation. Second, the multi-layer bonding process increases manufacturing complexity and production costs, limiting the large-scale application of flexible display technology. Third, the accumulated thickness further restricts the module's bending radius and dynamic response speed, affecting the deformation uniformity of the display panel and impacting display quality. Finally, the module's bulkiness makes it difficult to meet users' demands for thinner and lighter flexible forms such as rollable displays and wearable displays.

[0058] To address the aforementioned technical problems, the first aspect of this application provides a flexible display module, such as... Figure 1 As shown, the flexible display module includes an on-screen module 1, a display panel 2, and an under-screen module 3 stacked sequentially. The on-screen module 1 is stacked on the display surface of the display panel 2, and the under-screen module 3 is stacked on the back side of the display panel 2 away from the display surface.

[0059] The under-display module 3 includes an adhesive layer 31 and a support 32. The adhesive layer 31 is stacked on the back of the display panel 2, and the support 32 is stacked on the surface of the adhesive layer 31 facing away from the display panel 2.

[0060] Among them, the creep recovery rate of colloidal layer 31 is ≥90%, and the elastic modulus at -20℃ is ≤100kPa;

[0061] The material of the support 32 includes a supporting substrate and thermally conductive fibers. The thermally conductive fibers are dispersed in the supporting substrate. The elastic modulus of the supporting substrate is 20 GPa to 2000 GPa. The mass of the thermally conductive fibers accounts for 1% to 5% of the total mass of the support 32.

[0062] The under-display module 3 of the flexible display module in this embodiment replaces the existing multi-layer under-display structure with a combination of a colloidal layer 31 and a support 32. This reduces the thickness and weight of the entire flexible display module while ensuring mechanical performance, bending performance, and display performance. The support 32 is made of a supporting substrate and thermally conductive fibers dispersed therein. The modulus of the supporting substrate and the content of the thermally conductive fibers work together to enhance the mechanical properties of the support 32, improving toughness and reducing stress concentration while ensuring mechanical support. Furthermore, the thermally conductive fibers optimize the heat conduction path, reduce local heat accumulation, and dissipate heat promptly, maintaining the mechanical strength of the support 32 and ensuring the display stability of the flexible display module. Finally, it also contributes to the lightweight design of the support 32. The colloidal layer 31 bonds the display panel 2 and the support 32 respectively. The aforementioned advantages of the support 32 can synergize with the creep recovery rate and elastic modulus of the colloidal layer 31, making the performance of the colloidal layer 31 and the support 32 match. This reduces the thickness of the under-screen module 3 while improving the reliability of the interface bonding. The interfaces are less prone to peeling when the flexible display module is bent, thus improving bending stability. Compared with the prior art, the flexible display module of this application embodiment can balance thinness and bending reliability.

[0063] [Regarding support structure 32]

[0064] The support body 32 is a major component of the under-display module 3, and it needs to balance performance in terms of mechanical support, bending stability, and heat conduction, while also maintaining a slim profile. Therefore, the support body 32 is made of a supporting substrate and thermally conductive fibers, with the fibers dispersed within the supporting substrate. The elastic modulus of the supporting substrate ranges from 20 GPa to 2000 GPa, and can be selected from 70 GPa to 250 GPa (in the example). It can include, but is not limited to, any value or any two of 20 GPa, 70 GPa, 250 GPa, 1000 GPa, and 2000 GPa. Supporting substrates with these elastic moduli exhibit ideal stiffness, good support, excellent impact resistance, and also possess a certain degree of toughness and bendability.

[0065] Specifically, the supporting substrate includes at least one of a metal substrate and flexible glass. The metal substrate can include at least one of stainless steel, titanium alloy, aluminum alloy, and magnesium alloy. The alloy may also contain metallic elements such as vanadium, tin, zirconium, and zinc. The stainless steel can be SUS stainless steel, such as stainless steel with a chromium content ≥10.5% and a carbon content ≤1.2% as specified in national standards. The flexible glass can be UTG glass, CPI glass, etc. UTG glass is mainly composed of silicates, with silicon dioxide as the primary material, and may also contain modified components such as aluminum oxide. CPI glass is transparent polyimide glass. These supporting substrates possess mechanical properties such as stiffness, support, impact resistance, and bending resistance. Furthermore, their low density helps reduce weight when used as the substrate for the support body 32. Additionally, these supporting substrates have good thermal conductivity, enabling timely transfer of internal thermal stress to the outside. Specifically, the supporting substrate has a reliable bending cycle of ≥400,000 times to ensure good fatigue resistance of the entire support body 32, improve the bending stability of the entire flexible display module, reduce cracking or deformation, and extend its service life.

[0066] The thermally conductive fibers are dispersed in the supporting substrate. On the one hand, the fibers themselves have high mechanical strength, and their dispersion in the supporting substrate enhances the tensile strength, impact resistance, and other mechanical properties of the support 32, providing mechanical support for the display panel 2 and even the entire flexible display module. On the other hand, the fibers also have a certain degree of toughness. Since the flexible display module is prone to stress concentration when bent, the addition of fibers can improve the toughness of the supporting substrate, reduce the phenomenon of stress concentration caused by excessive rigidity, improve bending resistance, and increase fatigue life. Furthermore, during repeated bending, microcracks are easily generated inside the supporting substrate. The addition of fibers can inhibit the propagation of microcracks and improve fatigue life. Moreover, the fibers are thermally conductive, which helps to optimize the heat conduction path, reduce local heat accumulation, and dissipate heat in a timely manner, so that the support 32 maintains mechanical strength and also reduces the impact of temperature on the display panel 2, improving the display stability of the flexible display module. Finally, the density of thermally conductive fibers is often lower than that of the supporting substrate, which allows the support 32 to be further lightweight while maintaining the above properties, thus contributing to the weight reduction of the entire flexible display module.

[0067] Specifically, the thermal conductivity of the thermally conductive fibers is ≥100 W / (m·K) to improve the thermal conductivity of the support 32, maintain the mechanical strength of the support 32, and ensure the display panel 2 maintains display stability. Specifically, the material of the thermally conductive fibers can include at least one of carbon nanotube fibers, graphene fibers, carbon fibers, and ceramic fibers; in the example, the material can include carbon nanotube fibers. These materials combine certain mechanical properties such as toughness and tensile strength with thermal conductivity, which is beneficial to improving the overall performance of the support 32. Specifically, the length of the thermally conductive fibers can be 10 μm to 20 μm, and the diameter of the thermally conductive fibers can be 1 μm to 10 μm; this gives the thermally conductive fibers a good microstructure, allowing them to be better dispersed in the supporting substrate and exert a synergistic effect.

[0068] In the example, the thermal conductivity of the thermally conductive fiber can be selected from 100 W / (m·K) to 6000 W / (m·K). For example, the axial thermal conductivity of carbon nanotube fiber can reach 3500 W / (m·K), and the thermal conductivity of single-walled carbon nanotube fiber can be even higher, with graphene fiber reaching 5300 W / (m·K). The elastic modulus of the thermally conductive fiber can be selected from 50 GPa to 1000 GPa. For example, the elastic modulus of carbon fiber is 200 GPa to 800 GPa, and that of ceramic fiber is 300 GPa to 400 GPa. The tensile strength can be selected from 1.5 GPa to 10 GPa. For example, the tensile strength of carbon nanotube fiber can reach 3 GPa to 6 GPa, and that of graphene fiber is 2 GPa to 4 GPa. The aforementioned thermally conductive fiber materials can be used alone or in combination. For example, carbon nanotube fibers and carbon fibers can be combined in a mass ratio of 3:1, with the fiber length controlled between 12μm and 18μm and the diameter controlled between 2μm and 8μm.

[0069] Specifically, the mass of thermally conductive fibers accounts for 1% to 5% of the total mass of the support 32. In the example, it may include, but is not limited to, any value or a range between any two values ​​of 1%, 2%, 3%, 4%, and 5%. The content of thermally conductive fibers allows the support 32 to take into account the beneficial effects of the above-mentioned mechanical properties, heat conduction and thinness.

[0070] The support 32, formed from the aforementioned thermally conductive fibers and supporting substrate, helps reduce thickness and weight, achieving a thinner and lighter design. Specifically, the thickness of the support 32 can be 25μm to 150μm, preferably 25μm to 50μm. In the example, it can be any value or a range between any two of 25μm, 50μm, 80μm, 100μm, and 150μm. In this embodiment, the support 32 in the flexible display module can be made with a thickness of 25μm to 50μm to achieve a thinner and lighter design. However, depending on the application scenario, user needs, and product design, a thickness of 50μm to 150μm can also be used.

[0071] [Regarding the colloidal layer 31]

[0072] The adhesive layer 31 can bond the display panel 2 and the support 32. Together with the support 32, the adhesive layer 31 forms the under-display module 3, providing support for the display panel 2 and alleviating stress concentration during bending. Furthermore, due to the high strength of the supporting substrate of the support 32, if the deformation during bending is not compatible with the support 32, interlayer delamination is likely. Therefore, the adhesive layer 31 needs to have certain mechanical strength and toughness, with an elastic modulus of ≤100kPa at -20℃. In the example, this can include, but is not limited to, any value or any two of 30kPa, 50kPa, 70kPa, and 100kPa, to improve compatibility with the support 32 and ensure interface stability during bending. Moreover, the adhesive layer 31 will gradually deform (creep) during bending. If it cannot return to its original shape, the adhesive layer 31 is prone to peeling off from the display panel 2 or the support 32, affecting the structural stability and bending reliability of the entire flexible display module. Therefore, the colloidal layer 31 also needs to have certain creep recovery properties, allowing it to recover its initial shape after bending. Its creep recovery rate needs to be ≥90%, which, in the example, may include, but is not limited to, any value or a range between any two of 90%, 92%, 95%, and 97%. The colloidal layer 31 that meets the above elastic modulus and creep recovery properties can be adapted to the support 32 and can be adapted to flexible display module usage scenarios such as bending.

[0073] The primary function of the colloid layer 31 is adhesion. Specifically, the peel force between the display panel 2 and the colloid layer 31 is ≥8 N / cm. In the example, this can include, but is not limited to, any value or a range between any two of 8 N / cm, 12 N / cm, 15 N / cm, and 20 N / cm. Similarly, the peel force between the colloid layer 31 and the support 32 is ≥8 N / cm. In the example, this can include, but is not limited to, any value or a range between any two of 8 N / cm, 12 N / cm, 15 N / cm, and 20 N / cm. These peel forces facilitate tight adhesion between the display panel 2 and the colloid layer 31, and between the colloid layer 31 and the support 32. In flexible display module applications, especially during bending applications, interface peeling (interface peeling phenomenon) is less likely to occur between these adjacent structures.

[0074] Specifically, the thickness of the colloidal layer 31 is 15μm to 75μm, and can be selected as 15μm to 30μm. In the example, it can be any value or any two values ​​of 15μm, 23μm, 30μm, 50μm, and 75μm. Through the synergistic effect of the colloidal layer 31 and the aforementioned support 32, the colloidal layer 31 can be further thinned to the aforementioned thickness, further reducing the thickness of the under-display module 3. In this embodiment, the colloidal layer 31 in the flexible display module can be made with a thickness of 15μm to 30μm to achieve thinness and lightness. However, depending on the application scenario, user needs, and product design, it can also be set with a thickness of 30μm to 75μm.

[0075] Specifically, the material of the colloidal layer 31 may include at least one of the following: acrylic pressure-sensitive adhesive (PSA), silicone rubber, polyurethane elastomer, and modified epoxy resin. In the example, it may include acrylic pressure-sensitive adhesive. These materials have good elastic modulus and creep recovery rate. The formed colloidal layer 31 can work together with the support 32 to support the display panel 2 and has a certain degree of bending resistance. Furthermore, interfacial delamination is not easily observed between the display panel 2 and the colloidal layer 31, or between the colloidal layer 31 and the support 32. In the example, it may be PSA, which can be obtained by polymerization of monomers such as polyester polyol, polyether polyol, and hydroxyethyl acrylate.

[0076] Specifically, in addition to the aforementioned adhesive material, the colloidal layer 31 may also contain at least one of the following: black filler, black pigment, dark brown filler, dark brown pigment, or other dark-colored pigments and fillers. These can be uniformly dispersed in the adhesive material, forming a black, dark brown, or other dark-colored adhesive layer. The proportion of these additives can be adjusted according to the type of colloidal material. The beneficial effects of setting the colloidal layer 31 to a dark color are as follows: Firstly, when the display panel 2 emits light, the light directed towards the screen is absorbed by the colloidal layer 31, reducing reflected light within the flexible display module and minimizing its impact on integrated circuits such as driver ICs and sensor modules. Secondly, this reduction in internal reflected light also reduces the impact on the screen display effect, especially improving the screen's contrast and visual clarity. Thirdly, the dark-colored colloidal layer 31 is also beneficial for shielding the under-screen module structure and concealing wiring. Fourthly, the dark-colored colloidal layer 31 can also absorb infrared radiation generated by the display panel 2, possessing certain heat absorption and auxiliary heat dissipation properties, which is beneficial for thermal auxiliary management. Fifthly, the addition of pigments and fillers is low-cost and the process is simple.

[0077] Specifically, the optical density of the colloidal layer 31 is ≥1.5. Optical density, or OD, can reflect its light-shielding performance. In the example, the optical density of the colloidal layer 31 can be any value or any two values ​​of 1.5, 1.6, 1.7, 1.8, and 1.9, making the colloidal layer 31 a dark-colored adhesive layer. This is beneficial for the flexible display module to reduce the impact on the internal integrated circuits and screen display effect, and is also beneficial for shielding the structure and wiring, thermal management, and cost reduction.

[0078] [About Under-Display Module 3]

[0079] The aforementioned colloidal layer 31 and support 32 form the under-display module 3. Compared to existing under-display modules such as multi-layer modules consisting of a support film, adhesive layer, and support components, the thickness of the under-display module 3 in the flexible display module of this application embodiment can be reduced by at least 130μm, while maintaining high levels of support, impact resistance, and bending resistance. Specifically, the thickness of the under-display module 3 can be 40μm to 225μm, optionally 40μm to 80μm. In the examples, it includes, but is not limited to, any value or any two of 40μm, 60μm, 80μm, 120μm, and 225μm. The under-display module 3 in the flexible display module of this application embodiment can achieve a thickness of 40μm to 80μm, achieving a thinner and lighter design. Depending on the application scenario, user needs, and product design, a thickness of 80μm to 225μm can also be set, which is still thinner than the conventional 200μm to 250μm of existing technologies.

[0080] In addition to the aforementioned colloidal layer 31 and support 32, the under-display module 3 can also be equipped with corresponding components, such as various electronic components, circuit traces, hinge mechanisms, etc., according to the application scenarios and performance requirements of the flexible display module. These components can also be located below the under-display module 3.

[0081] [About Display Panel 2 and On-Screen Module 1]

[0082] The display panel 2 and the on-screen module 1 can adopt corresponding solutions from existing flexible display module technologies. The display panel 2 can be configured according to the display requirements of the flexible display module. Specifically, the display panel 2 can include at least one of OLED, AMOLED, mini-LED, and Micro-LED screens. OLED, or Organic Electroluminescence Display, emits light through carrier injection and recombination; AMOLED, or Active-Matrix Organic Light-Emitting Diode, has pixel addressing technology; mini-LED, or Mini-Light Emitting Diode, refers to LED chips with a size on the order of 100μm, with a size between small-pitch LEDs and Micro-LEDs, and is a further refinement of small-pitch LEDs. Small-pitch LEDs refer to LED backlights or display products where the spacing between adjacent LED beads is less than 2.5 mm. Micro-LED, or Micro-Light Emitting Diode, refers to the integration of a high-density, micro-sized LED array onto a single chip. It inherits the high efficiency, high brightness, high reliability, and fast response time of inorganic LEDs, while also possessing the characteristic of self-illumination without the need for a backlight. It is small, thin, and energy-efficient. In the example, display panel 2 is an OLED screen. These screens offer excellent display effects and flexibility in flexible displays. Specifically, the thickness of display panel 2 can be 40 μm to 60 μm.

[0083] like Figure 2 As shown, the on-screen module 1 can be configured with layers such as an optical optimization layer, a UTG ultra-thin glass layer, a flexible protective layer, a screen encapsulation layer, a touch layer, a polarizing layer, a buffer layer, an anti-reflective coating, and an anti-fingerprint coating, according to the display and protection requirements of the flexible display module. Specifically, the on-screen module 1 may include a cover plate layer 11, an OCA layer 12, and a COE layer 13 stacked sequentially, with the COE layer 13 stacked on the display surface of the display panel 2.

[0084] The cover plate layer 11 serves to protect the module 1 on the screen. Specifically, the thickness of the cover plate layer 11 can be 30μm to 100μm.

[0085] The OCA layer 12 bonds the cover plate layer 11 to the COE layer 13. The OCA layer fills in minor imperfections, improves screen flatness, reduces light scattering, and optimizes display performance such as color, brightness, contrast, and viewing angle. It also absorbs impact, providing some mechanical protection. Specifically, the thickness of the OCA layer 12 can range from 25μm to 75μm.

[0086] COE layer 13 provides anti-reflection and anti-glare properties, significantly reducing screen reflectivity, especially in strong light environments, improving outdoor visibility, and increasing light transmittance for brighter and more vibrant displays. Specifically, the thickness of COE layer 13 can range from 5μm to 10μm.

[0087] [About the entire flexible display module]

[0088] The above-mentioned on-screen module 1, display panel 2, and under-screen module 3 are stacked to form the entire flexible display module. Compared with the existing under-screen modules which consist of a support film, adhesive layer, and support components, such as support film + double-sided tape + titanium alloy, support film + single-sided adhesive + carbon fiber, etc., the thickness of the flexible display module in this application embodiment can be reduced by at least 130μm and the weight can be reduced by 5g, meeting the user's demand for a thin and light product.

[0089] Meanwhile, the flexible display module in this application embodiment has good bendability, and can be used as... Figure 5 As shown, the screen can be slightly bent at a small angle, or even bent so that the ends are connected to form a 360° surround display, or as... Figure 4 The screen was bent at a large angle, and even folded. The bending life of the flexible display module can also reach a high level. It can pass the 20W test with R1.5, that is, the flexible display module is folded and the radius of curvature at the bending point is measured to be 1.5mm. A total of 200,000 folding tests were conducted, and the flexible display module was undamaged.

[0090] A second aspect of this application provides a method for manufacturing a flexible display module, comprising the following steps:

[0091] S10: Provides support body 32;

[0092] S20: The raw material of the colloidal layer 31 is coated on one surface of the support 32 to form the colloidal layer 31, and the under-screen module 3 is obtained.

[0093] S30: The on-screen module 1 is attached to the display surface of the display panel 2;

[0094] S40: The under-display module 3 is bonded to the side of the display panel 2 away from the display surface, and the colloid layer 31 is bonded to the surface of the display panel 2 away from the display surface to obtain a flexible display module.

[0095] The preparation method of this application optimizes the material and structural composition of the under-display module 3. The colloidal layer 31 is formed by coating, eliminating the need for multi-layer lamination as in existing technologies. This simplifies the preparation process, reduces manufacturing steps, and lowers material costs. The resulting flexible display module exhibits stable structure, excellent bending resistance and display performance, and also achieves weight reduction.

[0096] Step S10 is the step of providing the support body 32. Specifically, the raw materials including the supporting substrate and the thermally conductive fiber can be mixed, sintered and rolled in sequence to obtain the support body 32.

[0097] When the supporting substrate is a metal substrate, both the supporting substrate and the thermally conductive fibers can be made from powdered raw materials. The mixing process can be achieved using mechanical stirring to ensure uniform mixing. The mixed powder is then placed in a mold, pressed into shape, and subjected to high-temperature sintering. This process can be referenced in powder metallurgy. Rolling is then performed to reduce the thickness of the metal-fiber composite material. Finally, the required dimensions and shape of the support 32 can be cut using an etching process to obtain the support 32. When the supporting substrate is flexible glass, pre-treated thermally conductive fibers can be embedded during the tempering and modification of UTG flexible glass, followed by shaping and cutting to obtain the support 32. Alternatively, pre-treated thermally conductive fibers can be incorporated into the raw materials of CPI flexible glass, followed by polymerization, stretching, curing, shaping, and cutting to obtain the support 32.

[0098] Step S20 is the step of preparing the under-screen module 3, which mainly involves forming the colloidal layer 31. The method of coating the raw material of the colloidal layer 31 onto a surface of the support 32 can include at least one of slit coating, micro-recessed coating, spraying, and spin coating. Slit coating or micro-recessed coating can be selected. After the adhesive material is formed, the colloidal layer 31 bonded to a surface of the support 32 is obtained, and the under-screen module 3 is obtained.

[0099] Step S30 is the step of bonding the on-screen module 1 and the display panel 2. The structure of the on-screen module 1 can be referred to the above description. The layers can be bonded together in sequence to form the on-screen module 1. The bonding of the on-screen module 1 and the display panel 2 can be set according to the layer structure of the prior art.

[0100] Step S40 completes the final bonding of the under-display module 3. Since the display panel 2 is fragile in material and structure, external impacts must be minimized during the manufacturing process. Therefore, the under-display module 3 can be directly bonded to the surface of the display panel 2 through its adhesive layer 31, relying on the adhesive properties of the adhesive layer 31 itself, eliminating or reducing the need for pressing and bonding processes. After the bonding of the under-display module 3 is completed, the flexible display module is obtained.

[0101] A third aspect of this application provides a display device, which includes a flexible display module according to the above-described application embodiments, or a flexible display module prepared by the preparation method according to the above-described application embodiments.

[0102] Because the flexible display module of this application embodiment combines reliable bending resistance, light weight, and thinness, it can be applied to various flexible display devices to obtain corresponding display devices. These display devices can be foldable display devices, including foldable screens; they can be rollable display devices, including wearable displays and rollable screens, capable of 360° rollable display; and they can be sliding display devices, including sliding rail screens. Therefore, the display device of this application embodiment has excellent display performance and bendability, while significantly reducing thickness and weight.

[0103] The following description is based on specific embodiments.

[0104] Example 1

[0105] This embodiment provides a flexible display module and its manufacturing method. The structure of the flexible display module is as follows: Figure 3 As shown, the flexible display module includes an on-screen module 1, a display panel 2, and an under-screen module 3 stacked sequentially. The on-screen module 1 includes a cover plate layer 11, an OCA layer 12, and a COE layer 13 stacked sequentially, with the COE layer 13 stacked on the display surface of the display panel 2. The display panel 2 is an OLED display panel. The under-screen module 3 includes a colloidal layer 31 and a support 32 stacked sequentially. The colloidal layer 31 is stacked on the back side of the display panel 2; the material of the colloidal layer 31 includes PSA adhesive, in which carbon black particles are dispersed, and the entire colloidal layer 31 is black. The material of the support 32 includes a SUS stainless steel supporting substrate and carbon nanotube thermally conductive fibers, with the carbon nanotube thermally conductive fibers accounting for 3% of the total mass of the support 32. Other parameters of the flexible display module are listed in Table 1.

[0106] The preparation method includes the following steps S1 to S4:

[0107] S1: First, weigh the raw material powders of the supporting substrate and the thermally conductive fiber according to a mass ratio of 97:3, and then perform mixing, sintering and rolling processes in sequence to obtain the support 32.

[0108] S2: The raw materials of the colloidal layer 31 are coated onto one surface of the support 32 by a slit coating process to form a colloidal layer, thereby obtaining the under-screen module 3.

[0109] S3: Attach the on-screen module 1 to the display surface of the display panel 2.

[0110] S4: The under-display module 3 is attached to the back of the display panel 2, and the colloid layer 31 is attached to the surface of the display panel 2 to obtain a flexible display module.

[0111] Example 2

[0112] This embodiment provides a flexible display module and its manufacturing method. The structure of the flexible display module is as follows: Figure 1 As shown, the main difference from Example 1 is that the percentage of the mass of the thermally conductive fiber in the total mass of the support 32 is changed to 5%. The support 32 and the colloid layer 31 form the under-screen module 3, while the over-screen module 1, the display panel 2, and the colloid layer 31 remain unchanged. Other parameter changes are recorded in Table 1.

[0113] Example 3

[0114] This embodiment provides a flexible display module and its preparation method. The main difference from Embodiment 1 is that the adhesive material of the colloidal layer 31 is changed to polyurethane elastomer adhesive. Other parameter changes are recorded in Table 1.

[0115] Example 4

[0116] This embodiment provides a flexible display module and its preparation method. The main difference from Embodiment 1 is that the supporting substrate of the support 32 is changed to titanium alloy. Other parameter changes are recorded in Table 1.

[0117] Example 5

[0118] This embodiment provides a flexible display module and its preparation method. The main difference from Embodiment 1 is that the supporting substrate of the support 32 is changed to aluminum alloy. Other parameter changes are recorded in Table 1.

[0119] Example 6

[0120] This embodiment provides a flexible display module and its preparation method. The main difference from Embodiment 1 is that the supporting substrate of the support 32 is changed to silicate UTG flexible glass. Other parameter changes are recorded in Table 1.

[0121] Example 7

[0122] This embodiment provides a flexible display module and its manufacturing method. The structure of the flexible display module is as follows: Figure 2 As shown, the main difference from Example 1 is that the thermally conductive fiber is replaced with graphene fiber to form a different under-screen module 3. As for the cover plate layer 11, OCA layer 12 and COE layer 13 forming the on-screen module 1 and display panel 2, there is no change. Other parameter changes are recorded in Table 1.

[0123] Example 8

[0124] This embodiment provides a flexible display module and its preparation method. The main difference from Embodiment 1 is that the thickness of the colloidal layer 31 is changed to 20 μm. Other parameter changes are recorded in Table 1.

[0125] Example 9

[0126] This embodiment provides a flexible display module and its preparation method. The main difference from Embodiment 1 is that the thickness of the support 32 is changed to 35 μm. Other parameter changes are recorded in Table 1.

[0127] Comparative Example 1

[0128] This comparative example provides a flexible display module, which differs from Example 1 mainly in that: the under-display module is changed to a multi-layer structure of a support film, adhesive layer, and support component, specifically a support film + double-sided tape + titanium alloy. The support film is a PI film, bonded to the display panel with PSA adhesive, with a total thickness of 65μm; the double-sided tape is 65μm thick; and the support component is SUS stainless steel with a thickness of 120μm. The total thickness of the entire under-display module is 250μm.

[0129] Comparative Example 2

[0130] This comparative example provides a flexible display module, which differs from Example 1 mainly in that: the under-screen module is changed to a multi-layer structure of a support film, adhesive layer, and support component, specifically a support film + single adhesive tape + titanium alloy. The support film is a PET film, bonded to the display panel with PSA adhesive, with a total thickness of 65μm; the single-sided adhesive tape is 20μm thick; and the support component is a titanium alloy with a thickness of 120μm. The total thickness of the entire under-screen module is 205μm.

[0131] Comparative Example 3

[0132] This comparative example provides a flexible display module, which differs from Example 1 mainly in that: doping elements are added to the stainless steel raw material of the supporting substrate, so that the elastic modulus of the supporting substrate increases to 2400 GPa.

[0133] Comparative Example 4

[0134] This comparative example provides a flexible display module, which differs from Example 1 mainly in that: the amount of thermally conductive fiber added is increased, and the mass of the thermally conductive fiber accounts for 10% of the total mass of the support 32.

[0135] Comparative Example 5

[0136] This comparative example provides a flexible display module, which differs from Example 1 mainly in that the raw material of the colloidal layer 31 is replaced by another supplier, the crosslinking density is higher, the creep recovery rate of the colloidal layer 31 is 86%, and the elastic modulus at -20℃ is 1500kPa.

[0137] Performance testing

[0138] 1. Folding durability test

[0139] The flexible display modules obtained from the above cases were subjected to 200,000 folding tests, such as... Figure 4As shown, the flexible display module is bent at a large angle. Ultimately, each fold needs to reach 180° to check for layer fatigue or even damage, display abnormalities, etc. If any layer of the under-screen module has an abnormality, it fails. The results are recorded in Table 1.

[0140] 2. Interface Peeling Observation

[0141] like Figure 5 , Figure 4 As shown, the flexible display modules of each case were subjected to bending tests, including large-angle bending tests, for 200,000 cycles to observe whether the interface peeling phenomenon of layer-to-layer delamination occurred. The results showed that the flexible display modules of all embodiments and comparative examples 1 and 2 passed the test without interface peeling problems, while comparative examples 3, 4, and 5 all showed interface peeling problems.

[0142] In Table 1, "Elastic modulus of colloidal layer / kPa" refers to the elastic modulus at -20℃. "Elastic modulus / GPa" refers to the elastic modulus of the supporting substrate in support 32.

[0143] Table 1

[0144]

[0145] As can be seen from Table 1, the flexible display modules in the embodiments of this application optimize the material composition and structure of the under-screen module 3. The support 32 includes a supporting substrate and thermally conductive fibers. Through the synergistic effect of the colloidal layer 31 and the support 32, it can replace the existing multi-layered under-screen module. While ensuring the requirement of bending resistance, it can significantly reduce the total weight and thickness of the flexible display module, achieving a thinner and lighter product. Furthermore, adopting this structure in the flexible display module can also simplify the manufacturing process and reduce the total material cost.

[0146] The above description is merely a preferred embodiment of this application and is 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 flexible display module, characterized in that: It includes an on-screen module (1), a display panel (2), and an under-screen module (3) stacked in sequence. The on-screen module (1) is stacked on the display surface of the display panel (2), and the under-screen module (3) is stacked on the back side of the display panel (2) away from the display surface. The under-display module (3) includes a colloidal layer (31) and a support (32). The colloidal layer (31) is stacked on the back side of the display panel (2), and the support (32) is stacked on the surface of the colloidal layer (31) away from the display panel (2). Wherein, the creep recovery rate of the colloidal layer (31) is ≥90%, and the elastic modulus of the colloidal layer (31) at -20℃ is ≤100kPa; The material of the support (32) includes a supporting substrate and thermally conductive fibers. The thermally conductive fibers are dispersed in the supporting substrate. The elastic modulus of the supporting substrate is 20 GPa to 2000 GPa. The mass of the thermally conductive fibers accounts for 1% to 5% of the total mass of the support (32).

2. The flexible display module according to claim 1, characterized in that: The thermal conductivity of the thermally conductive fiber is ≥100 W / (m·K); and / or, The thermally conductive fiber is made of at least one of carbon nanotube fiber, graphene fiber, carbon fiber, and ceramic fiber; and / or, The thermally conductive fiber has a length of 10μm to 20μm; and / or, The diameter of the thermally conductive fiber is 1μm to 10μm.

3. The flexible display module according to claim 1 or 2, characterized in that: The supporting substrate includes at least one of a metal substrate and flexible glass, wherein the metal substrate includes at least one of stainless steel, titanium alloy, aluminum alloy, and magnesium alloy; and / or, The reliable bending cycles of the supporting substrate are ≥400,000.

4. The flexible display module according to claim 1 or 2, characterized in that: The thickness of the colloidal layer (31) is 15 μm to 75 μm; and / or, The material of the colloidal layer (31) includes at least one of acrylic pressure-sensitive adhesive, silicone rubber, polyurethane elastomer adhesive, and modified epoxy resin adhesive; and / or, The peel force between the display panel (2) and the colloid layer (31) is ≥8 N / cm; and / or, The peel force between the colloidal layer (31) and the support (32) is ≥8 N / cm; and / or, The thickness of the support (32) is 25μm to 150μm.

5. The flexible display module according to claim 1 or 2, characterized in that: The optical density of the colloidal layer (31) is ≥1.5; and / or, The colloidal layer (31) contains at least one of black filler, black pigment, dark brown filler, and dark brown pigment.

6. The flexible display module according to claim 1 or 2, characterized in that: The display panel (2) includes at least one of OLED, AMOLED, mini-LED, and Micro-LED screens; and / or, The thickness of the display panel (2) is 40μm to 60μm; and / or, The on-screen module (1) includes a cover plate layer (11), an OCA layer (12) and a COE layer (13) stacked in sequence, and the COE layer (13) is stacked on one side surface of the display surface of the display panel (2).

7. The flexible display module according to claim 6, characterized in that: The thickness of the cover plate layer (11) is 30 μm to 100 μm; and / or, The thickness of the OCA layer (12) is 25 μm to 75 μm; and / or, The thickness of the COE layer (13) is 5 μm to 10 μm.

8. A method for manufacturing a flexible display module, characterized in that, Includes the following steps: Provide a support structure (32); The raw material of the colloidal layer (31) is coated on one surface of the support (32) to form the colloidal layer (31) and the under-screen module (3) is obtained. The on-screen module (1) is attached to the display surface of the display panel (2); The under-display module (3) is attached to the side of the display panel (2) away from the display surface, and the colloid layer (31) is attached to the surface of the display panel (2) away from the display surface to obtain the flexible display module.

9. The method for preparing the flexible display module according to claim 8, characterized in that, The method for preparing the support (32) includes the following steps: The raw materials, including the supporting substrate and the thermally conductive fiber, are sequentially mixed, sintered and rolled to obtain the support (32).

10. A display device, characterized in that, It includes the flexible display module according to any one of claims 1 to 7, or the flexible display module formed by the preparation method according to any one of claims 8 to 9.

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