Display screen, display module, and electronic device

Abstract

A display screen (11), a display module (10), and an electronic device (100), which relate to the technical field of display modules. The display screen (11) comprises a display panel (114) and a back film (115) that are stacked and connected, wherein the material of the back film (115) comprises a thermoplastic material, the glass transition temperature of which is in the range of 60 degrees Celsius to 120 degrees Celsius; and the thermoplastic material for preparing the back film (115) exhibits a Young's modulus of less than or equal to 800 MPa in an elastic state, and a Young's modulus of greater than 1000 MPa in a glassy state. By means of defining the material of the back film (115) as a thermoplastic material, the Young's modulus of the back film (115) can be reduced in the side-edge hot-bending process of the display screen (11), so that the display screen (11) is bent better, without causing a surface layer (111) and the back film (115) to forcefully compress the display panel (114), thereby preventing the display screen (11) from being damaged in the hot-bending process.

Description

Display screens, display modules and electronic devices

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on December 29, 2023, with application number 202311864322.6, and priority to the Chinese patent application entitled “Display screen, display module and electronic device”, all contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of display technology, and in particular to a display screen, a display module and an electronic device. Background Art

[0003] To enhance the display's refinement and grip, electronic devices are increasingly adopting curved edge designs. By applying downward pressure on the edges, the edge area is bent, creating a curved screen. Currently, most curved screen electronic devices use flexible organic light-emitting diode (OLED) display modules. Typically, a flat display is first prepared, including a laminated glass cover (CG), optically clear adhesive (OCA), polarizer (POL), display touch layer (PANEL), back film (BF), silicone gel (SEPA), and the bottom support structure.

[0004] When manufacturing a curved screen, a flat glass cover, transparent optical adhesive, polarizing film, display touch layer, backing film, silicone gel, and the underlying support structure are typically connected. Pressure is then applied to the edge of the glass cover to create the bend. During this process, the backing film, due to its relative hardness, compresses the display touch layer together with the glass cover, causing wrinkles to form in the curved area. These wrinkles are particularly noticeable in corners. Summary of the Invention

[0005] The present application provides a display screen, a display module and an electronic device. By limiting the back film in the display screen to be made of thermoplastic material, it is possible to facilitate the bending preparation of the display screen and improve the yield rate of the curved display screen.

[0006] In a first aspect, the present application provides a display screen comprising a stacked display panel and a back film, wherein the material of the back film comprises a thermoplastic material, the glass transition temperature of the thermoplastic material is in the range of 60 degrees Celsius to 120 degrees Celsius, the Young's modulus of the thermoplastic material in the elastic state is less than or equal to 800 MPa, and the Young's modulus of the thermoplastic material in the glassy state is greater than 1000 MPa.

[0007] The embodiment of the present application limits the material of the back film to a thermoplastic material, which can complete the transition from the glass state to the elastic state during the hot bending process of the display screen. At the same time, since the Young's modulus of the back film decreases during the transition process, plastic deformation can easily occur, reducing the force on the display panel, so that the display screen can be bent better, avoiding wrinkles in the corners of the display panel, and preventing the display screen from being damaged during the hot bending process.

[0008] In some feasible implementations, the thermoplastic material includes at least one of polycarbonate, polyvinyl butyral, polypropylene, polyethylene, and polymethyl methacrylate. The glass transition temperature of these materials can be lowered by varying their molecular weight, such that the glass transition temperature is within a range of 60°C to 120°C. This results in a relatively low Young's modulus during the display screen bending process, facilitating the display screen's bending process.

[0009] In some feasible implementations, the backing film includes at least two stacked layers, the at least two layers including a first backing film, the first backing film being made of the thermoplastic material. The backing film can have multiple layers and form a multi-layered structure. While reducing the Young's modulus of the backing film during thermal bending of the display screen, shear slip can also occur between the multiple layers of backing film, which helps reduce the stress on the display panel. Any of the at least two layers of backing film can be made of the thermoplastic material. The multiple layers of backing film are all supported by the thermoplastic material, which facilitates increasing the shear slip of the thermoplastic material layers during thermal bending, thereby reducing the stress on the display panel.

[0010] In some feasible implementations, the at least two layers of back films include a second back film, the materials of the first back film and the second back film are different thermoplastic materials, and the back film can be a composite layer composed of multiple layers of different types of thermoplastic materials. For example, the back film can be a composite layer of three layers of back films made of three materials: acrylate + polycarbonate + polyurethane.

[0011] In some feasible implementations, the display screen further includes a first connecting layer, the material of the first connecting layer includes a pressure-sensitive material, and the first connecting layer is located between the display panel and the back film and fixedly connects the display panel and the back film. The Young's modulus of the pressure-sensitive adhesive material at the hot bending temperature is about 25 kPa, and the Young's modulus at room temperature after cooling is about 160 kPa. Under high temperature conditions during hot bending, the Young's modulus is small to reduce the fitting stress of the first connecting layer with the display panel and the back film respectively, facilitating compression deformation. The Young's modulus of the pressure-sensitive adhesive increases after deformation and cooling at room temperature to ensure that it does not rebound after bending.

[0012] In some feasible implementations, the display screen further includes a surface layer, a second connecting layer, and an optical film layer stacked in sequence, the second connecting layer fixedly connects the surface layer and the optical film layer, the display panel is fixed between the optical film layer and the back film, the material of the second connecting layer includes a thermoplastic material, the glass transition temperature of the second connecting layer is in the range of 60 degrees Celsius to 120 degrees Celsius, the Young's modulus of the thermoplastic material used to prepare the second connecting layer in the elastic state is less than or equal to 100 kPa, and the Young's modulus of the thermoplastic material used to prepare the second connecting layer in the glassy state is greater than 200 kPa.

[0013] In the embodiments of the present application, a certain bending force and temperature are applied to the edges and corners of the display screen where bending is required. Since the second connecting layer made of thermoplastic material is in an elastic state and can bend along with the surface layer, and since the backing film is also made of thermoplastic material and is in an elastic state at this temperature, the polarizing layer and the display panel themselves do not have high hardness. Therefore, the second connecting layer, polarizing layer, display panel, and backing film can all bend well under the pressure of the surface layer, and the layers are tightly fitted together. After bending to a set degree, the temperature is lowered, and the second connecting layer formed of thermoplastic resin gradually solidifies and fixes the surface layer and polarizing layer. The backing film also solidifies to support the back side of the display panel. During the entire bending process, the display panel is not subjected to excessive pressure from both sides, which reduces the degree of wrinkles, or even completely eliminates wrinkles, thereby improving the display effect of the display panel.

[0014] In some feasible implementations, the 180-degree peel force of the second connecting layer is greater than or equal to 1200 g-force / inch, and / or the vertical pull-out strength of the second connecting layer is greater than or equal to 0.05 MPa. A greater 180-degree peel force can prevent the display from separating during the thermal bending process, ensuring a tight fit between the layers within the display. A greater vertical pull-out strength can prevent the layers within the display from shifting along the connecting interface due to lateral impact forces in situations such as a drop, thereby preventing misalignment of the layers within the display due to a drop during use and improving the display's impact resistance.

[0015] In some feasible implementations, the thermoplastic material includes at least one of silicone resin, silicone rubber, polyvinyl butyral, and acrylate. The material described in the embodiments of the present application has good light transmittance, improving the transmittance of light from the display panel through the second connecting layer. Furthermore, its glass transition temperature can be lowered by varying its molecular weight, such that the glass transition temperature of the second connecting layer prepared from the material described in the embodiments of the present application is within a range of 60 to 120 degrees Celsius. This results in a relatively low Young's modulus during the thermal bending process of the display, facilitating thermal bending of the display.

[0016] In some feasible implementations, the second connecting layer includes at least two stacked connecting layers, the at least two connecting layers including a third connecting layer, the material of the third connecting layer being the thermoplastic material. The second connecting layer can have multiple layers and form a multi-layer stacked structure. While the Young's modulus of the second connecting layer is reduced during the thermal bending of the display screen, shear slip can also be generated between the multiple second connecting layers, which is beneficial to reducing the stress on the display panel. The material of any one of the at least two connecting layers can be the thermoplastic material. The multiple second connecting layers are all supported by the thermoplastic material, which facilitates increasing the shear slip of the thermoplastic material layers during thermal bending, which is beneficial to reducing the stress on the display panel.

[0017] In some feasible implementations, the at least two connecting layers include a fourth connecting layer, the materials of the third connecting layer and the fourth connecting layer are different thermoplastic materials, and the second connecting layer can be a composite layer composed of multiple layers of different types of thermoplastic materials. For example, the second connecting layer can be a composite layer composed of three second connecting layers made of silicone resin, acrylate and polyvinyl butyral.

[0018] In second aspect, the present application provides a display screen comprising a surface layer, a second connecting layer and an optical film layer stacked in sequence, wherein the second connecting layer fixedly connects the surface layer and the optical film layer, the material of the second connecting layer comprises a thermoplastic material, the glass transition temperature of the second connecting layer is in the range of 60 degrees Celsius to 120 degrees Celsius, the Young's modulus of the thermoplastic material used to prepare the second connecting layer in the elastic state is less than or equal to 100 kPa, and the Young's modulus of the thermoplastic material used to prepare the second connecting layer in the glassy state is greater than 200 kPa.

[0019] When preparing a display screen, a thermoplastic resin heated to an elastic state can be first applied between a flat surface layer and a polarizing layer, and a certain clamping force is applied to the surface layer and the polarizing layer. A certain bending force is applied to the edges and corners of the display screen where bending is required. Since the thermoplastic resin is in an elastic state, it can bend along with the surface layer, and combined with the fact that the back film is also a thermoplastic material and is in an elastic state at this temperature, the polarizing layer and the display panel themselves do not have a high hardness. The second connecting layer, the polarizing layer, the display panel and the back film can all bend well under the pressure of the surface layer, and the layers are tightly fitted together. After bending to a set degree, the temperature is lowered, and the second connecting layer formed by the thermoplastic resin gradually solidifies and fixes the surface layer and the polarizing layer, and the back film is also solidified to support the back side of the display panel. During the entire bending process, the display panel will not be subjected to too much squeezing force on both sides, thereby reducing the degree of wrinkles, or even completely eliminating wrinkles, thereby improving the display effect of the display panel.

[0020] In some feasible implementations, the 180-degree peel force of the second connecting layer is greater than or equal to 1200 g-force / inch, and / or the vertical pull-out strength of the second connecting layer is greater than or equal to 0.05 MPa. A greater 180-degree peel force can prevent the display from separating during the thermal bending process, ensuring a tight fit between the layers within the display. A greater vertical pull-out strength can prevent the layers within the display from shifting along the connecting interface due to lateral impact forces in situations such as a drop, thereby preventing misalignment of the layers within the display due to a drop during use and improving the display's impact resistance.

[0021] In some feasible implementations, the second connecting layer is made of at least one of silicone resin, silicone rubber, polyvinyl butyral, and acrylate. The material described in the embodiments of the present application has good light transmittance, improving the transmittance of light from the display panel through the second connecting layer. Furthermore, the glass transition temperature (GTP) of the second connecting layer prepared from the material described in the embodiments of the present application can be lowered by varying the molecular weight, such that the GTP of the second connecting layer is within a range of 60°C to 120°C. This material exhibits a relatively low Young's modulus during the thermal bending process of the display, facilitating thermal bending of the display.

[0022] In some feasible implementations, the second connecting layer includes at least two stacked connecting layers, the at least two connecting layers including a third connecting layer, the material of the third connecting layer being the thermoplastic material. The second connecting layer can have multiple layers and form a multi-layer stacked structure. While the Young's modulus of the second connecting layer is reduced during the thermal bending of the display screen, shear slip can also be generated between the multiple second connecting layers, which is beneficial to reducing the stress on the display panel. The material of any one of the at least two connecting layers can be the thermoplastic material. The multiple second connecting layers are all supported by the thermoplastic material, which facilitates increasing the shear slip of the thermoplastic material layers during thermal bending, which is beneficial to reducing the stress on the display panel.

[0023] In some feasible implementations, the at least two connecting layers include a fourth connecting layer, the materials of the third connecting layer and the fourth connecting layer are different thermoplastic materials, and the second connecting layer can be a composite layer composed of multiple layers of different types of thermoplastic materials. For example, the second connecting layer can be a composite layer composed of three second connecting layers made of silicone resin, acrylate and polyvinyl butyral.

[0024] In a third aspect, the present application provides a display module comprising any of the above-described display screens and a support member, wherein the support member is located inside the display screen to support the display screen. The beneficial effects of the display module are similar to those of any of the above-described display screens and will not be further elaborated here.

[0025] In a fourth aspect, the present application provides an electronic device, comprising the display module described in any one of the above items, and further comprising a shell, wherein the shell and the outer edge of the display module are fixedly connected. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG1 is a schematic diagram of an electronic device provided in an embodiment of the present application;

[0027] FIG2 is a front view of an electronic device provided in an embodiment of the present application;

[0028] FIG3 is a schematic diagram of a 2.5D and 3D curved display screen provided in an embodiment of the present application;

[0029] FIG4 is an exploded schematic diagram of the surface layer, screen stack and housing provided in an embodiment of the present application;

[0030] FIG5 is a schematic diagram of the assembly of the surface layer, screen stack and housing provided in an embodiment of the present application;

[0031] FIG6 is a schematic diagram of a stacked layer of a display module provided in an embodiment of the present application;

[0032] FIG7 is another schematic diagram of a stacked layer of a display module provided in an embodiment of the present application;

[0033] FIG8 is a schematic diagram of a double-layer structure of a support structure provided in an embodiment of the present application;

[0034] FIG9 is a schematic diagram of another double-layer structure of a support structure provided in an embodiment of the present application;

[0035] FIG10 is a schematic diagram of the back film structure of a hyperbolic display screen provided in an embodiment of the present application;

[0036] FIG11 is a schematic diagram of the back film structure of a four-curved display screen provided in an embodiment of the present application;

[0037] FIG12 is a schematic structural diagram of a double-layer backing film provided in an embodiment of the present application;

[0038] FIG13 is a schematic diagram of another structure of a double-layer back film provided in an embodiment of the present application;

[0039] FIG14 is a schematic diagram of another structure of a double-layer back film provided in an embodiment of the present application;

[0040] FIG15 is a schematic diagram of a laminate of a backing film and a second connecting layer using thermoplastic materials according to an embodiment of the present application;

[0041] FIG16 is a schematic structural diagram of a double-layer second connecting layer provided in an embodiment of the present application;

[0042] FIG17 is a schematic diagram of another structure of a double-layer second connecting layer provided in an embodiment of the present application;

[0043] FIG18 is a schematic diagram of another structure of a double-layer second connecting layer provided in an embodiment of the present application;

[0044] FIG19 is a schematic diagram of a laminate in which a second connecting layer is made of a thermoplastic material according to an embodiment of the present application;

[0045] FIG20 is a schematic structural diagram of a double-layer second connection layer provided in an embodiment of the present application;

[0046] FIG21 is a schematic diagram of another structure of a double-layer second connecting layer provided in an embodiment of the present application;

[0047] FIG22 is another structural schematic diagram of the double-layer second connection layer provided in an embodiment of the present application. DETAILED DESCRIPTION

[0048] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0049] For ease of understanding, the English abbreviations and related technical terms involved in the embodiments of this application are explained and described below.

[0050] It should be clear that the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0051] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. The singular forms "a", "an", "the" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0052] It should be understood that the term "and / or" as used herein is simply a term used to describe the existence of three possible relationships between related objects. For example, "A and / or B" can represent the existence of A alone, the existence of both A and B, and the existence of B alone. Furthermore, the character " / " in this document generally indicates that the related objects are in an "or" relationship.

[0053] The word "if," as used herein, may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to the determination" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)," depending on the context.

[0054] It should be understood that the terms “first”, “second”, etc. used in this application are only used for the purpose of distinguishing descriptions, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying an order.

[0055] In the description of this application, the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting this application.

[0056] When used in this application, "within the range of...", unless it is specifically stated that the end value is not included, it is assumed that both end values ​​of the range are included. For example, in the range of 1 to 5, the two values ​​1 and 5 are included.

[0057] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "install", "connect" and "connect" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, a conflicting connection or an integrated connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0058] In recent years, the technology used to manufacture display panels for electronic devices has advanced rapidly. Among them, flexible, bendable screens are widely used as curved screens in electronic devices. Currently, quad-curved displays, which offer better full-screen display quality, are widely used. Quad-curved displays have curvatures on all four sides and corners. During the manufacturing process, particularly at the junctions between adjacent curved surfaces, at the four corners, the materials are easily squeezed and generate unrelieved stress, leading to wrinkles and affecting the display's visual quality.

[0059] This application provides an electronic device 100, which may include, but is not limited to, a mobile phone, a tablet computer, a laptop computer, an ultra-mobile personal computer, a handheld computer, a walkie-talkie, an Internet-connected television, a wearable device, an in-vehicle device, a driving recorder, a security device, and other products with a display interface. The embodiments of this application do not impose any particular restrictions on the form of the above-mentioned electronic devices.

[0060] For example, referring to FIG1 , the electronic device 100 in the embodiment of the present application is described using a curved screen mobile phone as an example. FIG1 is a three-dimensional schematic diagram of the electronic device 100 provided in the embodiment of the present application. FIG2 is a formal schematic diagram of the electronic device 100 provided in the embodiment of the present application. The electronic device 100 includes a display module 10 and a housing 20. The display module 10 is connected to the housing 20. Specifically, the housing and the display module can be fixedly connected at their outer edges. The housing 20 can include a middle frame and a back cover. The middle frame and the back cover can be split structures or integrated structures. This embodiment of the present application does not specifically limit this.

[0061] The display module 10 is mounted on the housing 20, wherein the housing 20 has a accommodating cavity, and components such as the circuit board, electronic components, camera module, processor and battery of the electronic device 100 can be installed in the accommodating cavity of the housing 20. The display module 10 covers the opening of the accommodating cavity of the housing 20, and the display module 10 and the housing 20 are sealed to form a sealed accommodating cavity, which protects the components in the accommodating cavity from water and dust. The housing 20 can be made of materials such as metal (such as aluminum alloy, titanium alloy and stainless steel), plastic (such as acrylonitrile-butadiene-styrene, polycarbonate and polypropylene) or glass (such as anti-glare glass). The housing 20 made of materials such as metal, plastic or glass can meet the requirements of wear resistance, impact resistance, corrosion resistance and aesthetics of the appearance of the electronic device 100.

[0062] In some possible implementations, the display module 10 may be a quad-curved screen, as shown in Figures 1 and 2 . The side edges of the display module 10 in the X direction, the reverse X direction, the Z direction, and the reverse Z direction are all bent toward the reverse Y direction to form a quad-curved screen. The four corners of the display module 10 are also bent toward the reverse Y direction to form a curved display module 10 with curved outer edges. In one embodiment, the display module 10 may also be a dual-curved screen (not shown). For a dual-curved screen, as shown in Figure 2 , only the side edges of the display module 10 in the X direction and the reverse X direction are bent toward the reverse Y direction, while the side edges in the Z direction and the reverse Z direction are not bent.

[0063] Among them, the curved screen can be a 2.5D curved screen or a 3D curved screen. Referring to Figure 3, in a 2.5D curved screen, the edges of the display screen in the X direction and the opposite X direction are curved only on the Y direction side, and are flat on the opposite Y direction side. In a 2.5D screen, only the outer surface edge of the surface layer (which can be a glass cover plate) can be made into a curved surface, while the inner side of the surface layer is flat. Under this structure, the polarizing layer, display panel, back film and other layers can be flat structures. Referring to Figure 3, in a 3D curved screen in this application, the edges of the display screen in the X direction and the opposite X direction are bent toward the opposite Y direction side, and the outer surface on the Y direction side is a protruding curved surface, while the inner surface on the opposite Y direction side is a concave curved surface. Regarding 3D curved screens, the embodiments of the present application take a four-curved screen as an example. When the side edges are bent, especially in the curved areas at the corners of the four-curved screen, the side bending will cause the display panel within the display screen to be subjected to a lateral squeezing force (perpendicular or inclined to the thickness direction, which can be the extension direction on the extension surface of the display panel), resulting in wrinkles. The wrinkles will make the thickness of the display panel uneven in the thickness direction, resulting in unclear display imaging in the corner areas of the display screen. The wrinkling phenomenon is particularly obvious in the corner areas.

[0064] This application provides a display module 10 that can be used in the electronic devices described in the above embodiments. The four sides of the display module 10 are curved to form a four-curved screen. See Figures 4, 5, 6, and 7. The display module 10 includes a display screen 11 and a support structure 12. Both the display screen 11 and the support structure 12 are plate-shaped and are stacked.

[0065] The display screen 11 includes at least a surface layer 111, a second connecting layer 112, a polarizing layer 113, a display panel 114, and a backing film 115. These layers are stacked in sequence. Referring to Figures 4 and 5 , the surface layer 111, located at the outermost surface, may be a glass cover plate. This glass cover plate may be transparent, allowing the display panel 114 to display through it. The stacked structure of the second connecting layer, polarizing layer, display panel, and backing film constitutes a screen stack 11a. The screen stack 11a is located inside the surface layer 111 and protects it from water, dust, and other debris, as well as from damage caused by compression. The side edges of the surface layer 111 may be connected to the housing 20. For example, the screen stack 11a is located within the cavity formed by the surface layer 111 and the housing 20.

[0066] The second connecting layer 112 can be a transparent optically clear adhesive (OCA), which can connect the surface layer 111 and the polarizing layer 113 to form an integral structure and facilitate the passage of light emitted by the display panel 114 for display. The polarizing layer 113 can be a polarizer (POL) film, which can eliminate reflections from the metal traces on the display panel 114 to improve the visibility of the display screen. The display panel 114 can be a display touch layer (PANEL), for example, a display layer and a touch layer are sequentially formed on a substrate to form a display panel with touch and display functions; at the same time, the display touch layer can also detect user actions on the display screen, realize the acquisition of user actions, and convert them into electrical signals for processing to realize interaction between the electronic device and the user. The back film 115 can be a back film provided on one side of the display panel 114. The display touch layer is usually a flexible layer. The display panel 114 is attached to the back film 115, and the back film 115 provides support for the display panel 114.

[0067] In one embodiment, the surface layer 111 can be located on the display surface side of the display screen 11. Thus, when the display module 10 is mounted on the electronic device 100, the surface layer 111 can protect the other layers of the display screen 11 while allowing light emitted by the display panel 114 to pass through. The surface layer 111 can be a cover plate for the surface of the display screen. The material of the surface layer 111 includes, but is not limited to, glass and transparent polyimide. This application does not impose any specific restrictions on the material of the surface layer 111.

[0068] With the rapid development of display panel manufacturing technology for electronic devices, flexible screens are widely used as curved screens in electronic devices. Current flexible screen support structures primarily consist of a support structure 12 positioned beneath the display screen 11. In one embodiment, the support structure 12 includes a fifth connecting layer 121 and a support member 122. The fifth connecting layer 121 may be an adhesive layer that securely connects the support member 122 to the display screen 11. The support member 122 is typically copper foil, which enhances the screen's support and bendability. The support structure 12 has a certain structural strength to meet the required support strength for the display screen 11. However, when manufacturing the curved portion of a curved screen, the flat display screen 11 and the support structure 12 are typically stacked and fixed together, and then the surface layer 111 of the display screen 11 is bent to form the curved screen structure. During the bending process, the surface layer 111 presses downward against the polarizing layer 113 and the display panel 114, with the support structure 12 providing support on the other side of the polarizing layer 113 and the display panel 114. Under the pressure of the surface layer 111 and the support structure 12, the polarizing layer 113 and the display panel 114 are easily damaged, especially the display panel 114, which can cause structural defects in the display module 10 and affect the display quality of the display module 10. In addition, at the corners of the display module 10, the curved corners formed by bending the flat display module 10 will cause the surface layers 111 and the back film 115 above and below the display panel 114 to press the display panel 114 along the direction of the extended surface during the bending process, resulting in multiple wrinkles on the display panel 114 and a decrease in the display quality of the display panel 114.

[0069] The embodiment of the present application improves the display screen of the display module 10 , which will be described below with reference to the accompanying drawings.

[0070] The present application provides a display screen 11, comprising a laminated surface layer 111, a second connection layer 112, a polarizing layer 113, a display panel 114, and a back film 115. The surface layer 111 may be made of, but not limited to, glass and transparent polyimide. The surface layer 111 may be first formed into a flat plate, and then softened by heating to be bent at the sides and corners to produce a dual-curved screen or a quad-curved screen with curved sides and corners.

[0071] During the heating and bending process, the hardness of the surface layer 111 will decrease accordingly to be more conducive to bending. The temperature can be in the range of 60 degrees Celsius to 80 degrees Celsius, for example, about 70 degrees Celsius. At this temperature, the layers in the display screen 11 can be softened appropriately to be more conducive to bending, and to avoid damage to the structure and performance caused by excessively high temperature. At this temperature, the back film 115 is still at a relatively high hardness, and its bendability is relatively poor. After hot bending, more obvious wrinkles will appear in the corners of the display panel 114. If the back film 115 is made of a material with lower hardness, the back film 115 will not produce a strong squeeze on the display panel 114 during hot bending, and the wrinkles in the corners of the display panel 114 will be improved after hot bending. However, after the hot bending is completed and cooled, the strength of the back film 115 is relatively low, which cannot meet the support strength requirements of the display panel 114.

[0072] In the embodiment of the present application, the material of the back film 115 includes a thermoplastic material. A thermoplastic material refers to a material that can be plastic when heated to a certain temperature and solidifies to increase hardness when the temperature is lowered. After being heated to a certain temperature, the corresponding hardness of the thermoplastic material decreases to become plastic, and after the temperature is lowered, it returns to a solid state to maintain a high hardness. In addition, the thermoplastic material is in an elastic state with plasticity at high temperatures and in a glassy state with high hardness at low temperatures. The elastic state and the glassy state can switch with changes in temperature.

[0073] In an embodiment of the present application, the material of the back film 115 may include a thermoplastic material, wherein the glass transition temperature (Tg) of the back film 115 may be in the range of 60 degrees Celsius to 120 degrees Celsius, the Young's modulus of the thermoplastic material used to prepare the back film 115 in the elastic state is less than or equal to 800 MPa, and the Young's modulus of the thermoplastic material used to prepare the back film 115 in the glassy state is greater than 1000 MPa.

[0074] The embodiment of the present application limits the material of the back film 115 to a thermoplastic material, which can reduce the Young's modulus of the material used to make the back film 115 during the side hot bending process of the display screen 11, so that the display screen 11 can be bent better without causing the surface layer 111 and the back film 115 to forcibly squeeze the display panel 114, thereby preventing the display screen 11 from being damaged during the hot bending process.

[0075] Referring to FIG. 10 , for a hyperbolic display screen, the shape of backing film 115 is shown in FIG. Backing film 115 includes a central planar region 115a and curved regions 115b located to the sides of planar region 115a. Backing film 115 is made of a thermoplastic material. Backing film 115 can be first formed into a flat plate, then heated to a thermal bending temperature, and then bent at the edges to form planar region 115a and curved region 115b. During the heating process, the material of backing film 115 transitions from a glassy state to an elastic state, reducing its Young's modulus and facilitating the bending of curved region 115b.

[0076] Referring to Figure 11 , for a four-curved display screen, the shape of backing film 115 is shown in Figure 11 . Backing film 115 includes a central flat region 115a and curved regions 115b located to the sides of flat region 115a. Curved regions 115b undergo significant bending deformation at the four corners. Backing film 115 is made of thermoplastic material. Backing film 115 can be first prepared into a flat plate, then heated to a thermal bending temperature, and bent at the edges to form flat region 115a and curved region 115b. During the heating process, the material of backing film 115 transforms from a glassy state to an elastic state, reducing its Young's modulus and facilitating the bending of curved region 115b.

[0077] In a feasible embodiment, the thermoplastic material used for the back film 115 can be at least one of polycarbonate (PC), polyvinyl butyral (TPU), polypropylene (PP), polyethylene (PE) and polymethyl methacrylate (PMMA).

[0078] The above-mentioned materials can lower their glass transition temperature by changing the molecular weight, so that the glass transition temperature Tg of the above-mentioned materials is in the range of 60 degrees Celsius to 120 degrees Celsius, and have a relatively small Young's modulus during the hot bending process of the display screen, which is beneficial to the hot bending molding of the display screen.

[0079] In the embodiment of the present application, the material of the back film 115 is designed to include a thermoplastic material, and the glass transition temperature Tg of the thermoplastic material is in the range of 60 degrees Celsius to 120 degrees Celsius. It can be specifically selected according to the thermal bending temperature of the surface layer 111, so that the glass transition temperature Tg of the back film 115 is lower than the thermal bending temperature of the surface layer 111. When the display module 10 is prepared for a curved screen, the surface layer 111 and the back film 115 are softened to a certain extent by heating. In one embodiment, the Young's modulus of the thermoplastic material used to prepare the back film 115 in the elastic state (when the temperature of the back film 115 is greater than its glass transition temperature Tg, the back film 115 softens and becomes elastic) is less than or equal to 800 MPa. At this strength, the back film 115 will not cause strong extrusion on the display panel 114 when it is bent. The surface layer 111 bends and squeezes the display panel 114 and the back film 115. The clamping force of the surface layer 111 and the back film 115 on the display panel 114 is small, which reduces or even prevents wrinkles on the display panel 114.

[0080] Furthermore, the glass transition temperature Tg of the back film 115 is greater than or equal to 60 degrees Celsius, so that the glass transition temperature of the back film 115 is greater than the ambient temperature of the display module 10 when in use. During the use of the display module 10 after bending and forming, the surface layer 111 and the back film 115 both have a certain hardness to protect the display panel 114 sandwiched therebetween. In one embodiment, the thermoplastic material used to make the back film 115 has a Young's modulus greater than 1000 MPa in the glassy state (when the back film 115 is at a temperature lower than its glass transition temperature Tg, the back film 115 hardens and becomes a glassy state). At this hardness, the back film 115 can better support the display panel 114 when the display module 10 is in use, preventing the display panel 114 from being deformed or even damaged by stress.

[0081] In one embodiment, the glass transition temperature Tg of thermoplastic materials such as polycarbonate is related to the size of its own molecular weight. In order to prepare a thermoplastic material with a glass transition temperature Tg in the range of 60 degrees Celsius to 120 degrees Celsius, it is necessary to reduce the molecular weight of the material. The present application can obtain a thermoplastic material with a glass transition temperature Tg in the range of 60 degrees Celsius to 120 degrees Celsius by reducing the molecular weight of the thermoplastic material. Taking into account the mechanical properties and strength of the thermoplastic material, the material is prevented from becoming brittle and the material is ensured to have a certain creep (applied force rebound) performance to prevent the reduction of the mechanical properties of the thermoplastic material from causing significant damage to the display panel. In addition, when the thermoplastic material in the present application is applied to the back film 115, it is necessary to design a lower modulus. On the one hand, it can reduce the large extrusion of the back film 115 on the display panel during hot bending. On the other hand, the reduction of Young's modulus can accelerate the hot bending speed of the display screen and improve the production efficiency of the display screen.

[0082] In some possible embodiments, as shown in FIG12 , the number of back films 115 can be at least two layers, and the at least two layers of back films 115 are stacked, and at least one of the at least two layers of back films 115 is made of the thermoplastic material. The back film includes at least two stacked layers of back films. Taking the double-layer back film 115 structure shown in FIG12 as an example, the back film 115 can include a first back film 1151 and a second back film 1152 stacked, wherein at least one of the first back film 1151 and the second back film 1152 can be made of a thermoplastic material. The first back film 1151 can be made of a thermoplastic material, and the second back film 1152 can be made of a thermoplastic material, or the first back film 1151 can be made of a thermoplastic material, and the second back film 1152 can be made of a non-thermoplastic material. In the embodiment of the present application, the material of the first back film 1151 is a thermoplastic material, and the second back film 1152 can be made of plastic (polyethylene terephthalate) or other materials for example, so as to reduce the Young's modulus of the entire back film 115 during hot bending.

[0083] In one embodiment, as shown in FIG13 , the backing film 115 can have at least two layers, with the at least two layers of backing film 115 being stacked, and any one of the at least two layers being made of the thermoplastic material. Taking the double-layer backing film 115 structure shown in FIG12 as an example, a first backing film 1151 and a second backing film 1152 are stacked, wherein the first backing film 1151 and the second backing film 1152 can both be made of thermoplastic materials to minimize the Young's modulus of the overall backing film 115 during thermal bending.

[0084] In one embodiment, referring to FIG. 14 , when there are at least two layers of back film 115, and two or more of the at least two layers of back film 115 are made of thermoplastic materials, for example, in FIG. 14 , the materials of first back film 1151 and second back film 1152 can both be thermoplastic materials, and the materials of first back film 1151 and second back film 1152 can be different thermoplastic materials. In one embodiment, the material of first back film 1151 can be polycarbonate, and the material of second back film 1152 can be polyethylene. In one embodiment, when three layers of back film 115 are made of thermoplastic materials, the materials of the three layers of back film 115 can be polycarbonate, polyvinyl butyral, and polypropylene, respectively.

[0085] In some possible embodiments, the material of the back film 115 can be plastic, for example, polyethylene terephthalate (PET) material. The glass transition temperature Tg of the PET material is greater than or equal to 150 degrees Celsius. When the hot bending temperature is above 150 degrees Celsius, the back film 115 made of plastic or other materials can be used. It has low production cost, good optical performance, and high transmittance, which is conducive to the recognition of optical fingerprints.

[0086] In some possible embodiments, referring to FIG7 , the display screen described in the embodiment of the present application further includes a first connecting layer 116, which is located between the display panel 114 and the back film 115 to fix the display panel 114 and the back film 115. The material of the first connecting layer includes a pressure-sensitive material, specifically a pressure-sensitive adhesive tape (PSA). The pressure-sensitive tape is a tape that applies an adhesive on a strip-shaped substrate. The adhesive can be a pressure-sensitive adhesive that has a characteristic of sensing pressure. The pressure-sensitive tape can be pasted between the display panel 114 and the back film 115, and through a clamping mechanism, a certain pressure is applied to the display panel 114 and the back film 115 so that the pressure-sensitive tape tightly bonds the display panel 114 and the back film 115. Moreover, by applying pressure for a short time, the pressure-sensitive tape can have a good bonding effect and has certain heat resistance. Wherein, the Young's modulus of the pressure-sensitive adhesive material at the hot bending temperature is about 25 kPa, and the Young's modulus at room temperature after cooling is about 160 kPa. Under the high temperature conditions of hot bending, the Young's modulus is small, which reduces the lamination stress between the first connecting layer and the display panel 114 and the back film 115, facilitating compression deformation. After deformation and cooling to room temperature, the Young's modulus of the pressure-sensitive adhesive increases, ensuring that it does not rebound after bending.

[0087] When preparing the display module 10, a flat surface layer 111, a second connecting layer 112, a polarizing layer 113, a display panel 114, and a back film 115 can be prepared first. The display panel 114 and the back film 115 are fixedly connected as a whole by a first connecting layer 116 composed of a pressure-sensitive adhesive tape. The edges and corners of the display module 10 that need to be bent are heated to a certain temperature, for example, 100 degrees Celsius, by a heating device. At this temperature, the surface layer 111 and the back film 115 soften to facilitate bending. The first connecting layer 116 is heat-resistant and can maintain good adhesion within the temperature range of 0 degrees Celsius to 200 degrees Celsius, so as to better bond the display panel 114 and the back film 115, prevent the display panel 114 and the back film 115 from separating when bending, and ensure that the display panel 114 and the back film 115 are always in contact with each other.

[0088] In some possible embodiments, as shown in FIG15 , a display screen 11 is provided. Display screen 11 includes a stacked surface layer 111, a second connection layer 112, a polarizing layer 113, a display panel 114, and a backing film 115. Second connection layer 112 may be an optically clear adhesive (OCA) layer that connects surface layer 111 and polarizing layer 113 to form an integrated structure.

[0089] The second connecting layer 112 is made of a thermoplastic material. A thermoplastic material is a material that becomes plastic when heated to a certain temperature and solidifies to increase its hardness when the temperature drops. When heated to a certain temperature, the hardness of the thermoplastic material decreases, becoming plastic. When the temperature drops, the material returns to a solid state, maintaining a high hardness. Furthermore, thermoplastic materials exhibit an elastic state with plasticity at high temperatures and a glassy state with high hardness at low temperatures. These states can switch between the elastic and glassy states depending on temperature.

[0090] In an embodiment of the present application, the material of the second connecting layer 112 may include a thermoplastic material, specifically a thermoplastic resin. The glass transition temperature Tg of the second connecting layer 112 may be in the range of 60 degrees Celsius to 120 degrees Celsius. The Young's modulus of the thermoplastic material used to prepare the second connecting layer 112 in the elastic state is less than or equal to 100 MPa, and the Young's modulus of the thermoplastic material used to prepare the second connecting layer 112 in the glassy state is greater than 200 MPa.

[0091] In one embodiment, when preparing the display screen 11, a thermoplastic resin heated to an elastic state can be first applied between the flat surface layer 111 and the polarizing layer 113, and a certain clamping force is applied to the surface layer 111 and the polarizing layer 113. A certain bending force is applied to the edges and corners of the display screen 11, and since the thermoplastic resin is in an elastic state, it can bend along with the surface layer 111. In addition, since the back film 115 is also a thermoplastic material and is in an elastic state at this temperature, and the polarizing layer 113 and the display panel 114 do not have a high hardness, the second connecting layer 112, the polarizing layer 113, the display panel 114, and the back film 115 can all bend well under the pressure of the surface layer 111, and the layers are tightly fitted together. After bending to a set degree, the temperature is lowered, and the second connecting layer 112 formed by the thermoplastic resin gradually solidifies and fixes the surface layer 111 and the polarizing layer 113. The back film 115 also solidifies to support the back side of the display panel 114. During the entire bending process, the display panel 114 will not be subjected to too much squeezing force from both sides, thereby reducing the degree of wrinkles, or even completely eliminating wrinkles, thereby improving the display effect of the display panel 114 .

[0092] In one embodiment, the thermoplastic material used for the second connection layer 112 may be at least one of silicone resin, silicone rubber, polyvinyl butyral (TPU), and acrylic ester.

[0093] The material described in the embodiment of the present application has good light transmittance, improves the transmittance of light of the display panel through the second connecting layer, and can lower its glass transition temperature by changing the molecular weight, so that the glass transition temperature Tg of the second connecting layer prepared by the material described in the embodiment of the present application is in the range of 60 degrees Celsius to 120 degrees Celsius, and has a relatively small Young's modulus during the hot bending process of the display screen, which is beneficial to the hot bending molding of the display screen.

[0094] In the embodiment of the present application, the material of the second connecting layer 112 is designed to include a thermoplastic material, and the glass transition temperature Tg of the thermoplastic material is in the range of 60 degrees Celsius to 120 degrees Celsius. It can be specifically selected according to the thermal bending temperature of the surface layer 111, so that the glass transition temperature Tg of the second connecting layer 112 is lower than the thermal bending temperature of the surface layer 111. When the display module 10 is prepared for a curved screen, the surface layer 111 and the second connecting layer 112 are softened to a certain extent by heating. In one embodiment, the Young's modulus of the thermoplastic material used to prepare the second connecting layer 112 in the elastic state (when the temperature of the second connecting layer 112 is greater than its glass transition temperature Tg, the second connecting layer 112 softens and becomes elastic) is less than or equal to 100 MPa. At this strength, the second connecting layer 112 will not cause strong extrusion on the display panel 114 when bent. Combined with the fact that the back film 115 is also a thermoplastic material and is in an elastic state at this temperature, the polarizing layer 113 and the display panel 114 themselves do not have a high hardness. The second connecting layer 112, the polarizing layer 113, the display panel 114 and the back film 115 can all be bent well under the extrusion of the surface layer 111. The surface layer 111 bends and squeezes the second connecting layer 112, the display panel 114 and the back film 115. The layers are tightly fitted together, and the clamping force of the surface layer 111 and the back film 115 on the display panel 114 is small, thereby reducing or even preventing wrinkles on the display panel 114.

[0095] Furthermore, the glass transition temperature (Tg) of the second connecting layer 112 is greater than or equal to 60 degrees Celsius, so that the glass transition temperature of the second connecting layer 112 is greater than the ambient temperature of the display module 10 during use. During use of the display module 10 after bending and forming, both the surface layer 111 and the second connecting layer 112 have a certain hardness to protect the attached display panel 114. In one embodiment, the thermoplastic material used to make the second connecting layer 112 has a Young's modulus greater than 200 MPa in the glassy state (when the second connecting layer 112 is at a temperature less than its glass transition temperature (Tg), the second connecting layer 112 hardens and becomes glassy). At this hardness, the second connecting layer 112 can better protect the display panel 114 during use of the display module 10, and the pressure transmitted from the surface layer 111 (when a person presses the screen during operation) can be accurately and quickly transmitted to the display panel 114, ensuring the sensitivity of the touch function of the display module 10.

[0096] In one embodiment, the glass transition temperature (Tg) of a thermoplastic material, such as silicone resin, is related to its molecular weight. To prepare a thermoplastic material with a Tg between 60 and 120 degrees Celsius, the molecular weight of the material needs to be reduced. The present application can obtain a thermoplastic material with a Tg between 60 and 120 degrees Celsius by reducing the molecular weight of the thermoplastic material. This approach takes into account the mechanical strength of the thermoplastic material, prevents the material from becoming brittle, and ensures that the material has a certain creep (force-applied rebound) property to prevent the reduction in the mechanical properties of the thermoplastic material from causing significant damage to the display panel. Furthermore, in the present application, the thermoplastic material, when applied to the second connecting layer 112, needs to be designed with a lower modulus. This can reduce the significant extrusion of the second connecting layer 112 on the display panel during thermal bending. Furthermore, the reduction in Young's modulus can accelerate the thermal bending speed of the display screen, improving the production efficiency of the display screen.

[0097] In one possible embodiment, the 180-degree peel force of the second connecting layer 112 is greater than or equal to 1200 gf / inch. The peel force of the second connecting layer 112 can be measured using a 180-degree peel force tester. The second connecting layer 112 serves as a connecting layer between the surface layer 111 and the polarizing layer 113. Testing has shown that the 180-degree peel force of the second connecting layer 112 is greater than or equal to 1200 gf / inch. This ensures that the second connecting layer 112 effectively connects the surface layer 111 and the polarizing layer 113, preventing peeling during bending preparation and post-molding use, thereby improving the connection strength and integrity of the display module 10.

[0098] In one embodiment, the vertical pull-out strength of the second connection layer 112 is greater than or equal to 0.05 MPa. The vertical pull-out strength refers to the stress required for the connection interface to be damaged when the two sides of the laminate are bonded with 40*40 steel plates and strong glue, and then a tensile force is applied in a direction perpendicular to the bonding surface. Specifically, the vertical pulling force is perpendicular to the connection interface to correspond to the scenario where the entire screen is bent and deformed. The 180-degree peeling force is parallel to the connection interface, corresponding to the scenario where the two adjacent layers inside the entire screen move in the direction extending along the connection interface when the entire screen falls. A larger 180-degree peeling force can prevent the display screen from separating during the hot bending process to ensure that the layers inside the display screen are tightly fitted. A larger vertical pull-out strength can prevent the layers inside the display screen from moving in the direction extending along the connection interface due to lateral impact force in scenarios such as the display screen falling, prevent the layers inside the display screen from being dislocated when the display screen falls during use, and improve the anti-collision strength of the display screen.

[0099] In some possible embodiments, as shown in FIG16 , the number of second connecting layers 112 can be at least two, with the at least two second connecting layers 112 being stacked, and at least one of the at least two second connecting layers 112 being made of the thermoplastic material. The second connecting layer can include at least two stacked connecting layers. For example, in the double-layer second connecting layer 112 structure shown in FIG16 , the second connecting layer 112 can include a third connecting layer 1121 and a fourth connecting layer 1122 stacked, wherein at least one of the third connecting layer 1121 and the fourth connecting layer 1122 can be made of a thermoplastic material. For example, the third connecting layer 1121 can be made of a thermoplastic material, while the fourth connecting layer 1122 can be made of a non-thermoplastic material, to reduce the Young's modulus of the overall second connecting layer 112 during hot bending.

[0100] In one embodiment, as shown in FIG17 , the number of second connecting layers 112 can be at least two, and the at least two second connecting layers 112 are stacked, and the material of any of the at least two second connecting layers 112 is the thermoplastic material. Taking the double-layer second connecting layer 112 structure shown in FIG17 as an example, the third connecting layer 1121 and the fourth connecting layer 1122 are stacked, and the materials of the third connecting layer 1121 and the fourth connecting layer 1122 can both be thermoplastic materials to minimize the Young's modulus of the entire second connecting layer 112 during hot bending.

[0101] In one embodiment, referring to FIG. 18 , when there are at least two second connecting layers 112, and two or more of the at least two second connecting layers 112 are made of thermoplastic materials, for example, in FIG. 18 , the third connecting layer 1121 and the fourth connecting layer 1122 can both be made of thermoplastic materials, and the third connecting layer 1121 and the second backing film 1152 can be made of different thermoplastic materials. In one embodiment, the third connecting layer 1121 can be made of silicone, and the fourth connecting layer 1122 can be made of acrylate. In one embodiment, when three of the second connecting layers 112 are made of thermoplastic materials, the materials of the three second connecting layers 112 can be silicone, acrylate, and polyvinyl butyral, respectively.

[0102] In one embodiment, the backing film 115 has at least two layers, and the second connecting layer 112 has at least two layers. The multi-layer backing film 115 can have some or all layers made of thermoplastic materials, and two or more layers of the thermoplastic backing film 115 can be made of different thermoplastic materials. Similarly, the multi-layer second connecting layer 112 can have some or all layers made of thermoplastic materials, and two or more layers of the thermoplastic second connecting layer 112 can be made of different thermoplastic materials. The above embodiments can be adaptively adjusted and combined to meet different application requirements.

[0103] The present application also provides a specific embodiment of a display screen. Referring to FIG. 19 , this embodiment provides a display screen 11, which includes a stacked surface layer 111, a second connection layer 112, a polarizing layer 113, a display panel 114, and a backing film 115. The second connection layer 112 may be an optically clear adhesive (OCA) layer that connects the surface layer 111 and the polarizing layer 113 to form an integrated structure.

[0104] The second connecting layer 112 is made of a thermoplastic material. A thermoplastic material is a material that becomes plastic when heated to a certain temperature and solidifies to increase its hardness when the temperature drops. When heated to a certain temperature, the hardness of the thermoplastic material decreases, becoming plastic. When the temperature drops, the material returns to a solid state, maintaining a high hardness. Furthermore, thermoplastic materials exhibit an elastic state with plasticity at high temperatures and a glassy state with high hardness at low temperatures. These states can switch between the elastic and glassy states depending on temperature.

[0105] In an embodiment of the present application, the material of the second connecting layer 112 may include a thermoplastic material, specifically a thermoplastic resin. The glass transition temperature Tg of the second connecting layer 112 may be in the range of 60 degrees Celsius to 120 degrees Celsius. The Young's modulus of the thermoplastic material used to prepare the second connecting layer 112 in the elastic state is less than or equal to 100 MPa, and the Young's modulus of the thermoplastic material used to prepare the second connecting layer 112 in the glassy state is greater than 200 MPa.

[0106] In one embodiment, when preparing the display screen 11, a thermoplastic resin heated to an elastic state can be first applied between the flat surface layer 111 and the polarizing layer 113, and a certain clamping force is applied to the surface layer 111 and the polarizing layer 113. A certain bending force is applied to the edges and corners of the display screen 11, and since the thermoplastic resin is in an elastic state, it can bend along with the surface layer 111. In addition, since the back film 115 is also a thermoplastic material and is in an elastic state at this temperature, and the polarizing layer 113 and the display panel 114 do not have a high hardness, the second connecting layer 112, the polarizing layer 113, the display panel 114, and the back film 115 can all bend well under the pressure of the surface layer 111, and the layers are tightly fitted together. After bending to a set degree, the temperature is lowered, and the second connecting layer 112 formed by the thermoplastic resin gradually solidifies and fixes the surface layer 111 and the polarizing layer 113. The back film 115 also solidifies to support the back side of the display panel 114. During the entire bending process, the display panel 114 will not be subjected to too much squeezing force from both sides, thereby reducing the degree of wrinkles, or even completely eliminating wrinkles, thereby improving the display effect of the display panel 114 .

[0107] In some possible embodiments, the material of the back film 115 can be plastic, for example, polyethylene terephthalate (PET) material. The glass transition temperature Tg of the PET material is greater than or equal to 150 degrees Celsius. When the hot bending temperature is above 150 degrees Celsius, the back film 115 made of plastic or other materials can be used. It has low production cost, good optical performance, and high transmittance, which is conducive to the recognition of optical fingerprints.

[0108] In some possible embodiments, the material of the back film 115 can be a thermoplastic material, including at least one of polycarbonate, polyvinyl butyral, polypropylene, polyethylene and polymethyl methacrylate. And the glass transition temperature of the thermoplastic material used to prepare the back film 115 is in the range of 60 degrees Celsius to 120 degrees Celsius, the Young's modulus of the thermoplastic material used to prepare the back film 115 in the elastic state is less than or equal to 800 MPa, and the Young's modulus of the thermoplastic material used to prepare the back film 115 in the glassy state is greater than 1000 MPa. It is possible to complete the transition from the glassy state to the elastic state during the hot bending process of the display screen. At the same time, since the Young's modulus of the back film is reduced during the transition process, plastic deformation can be easily caused, reducing the force on the display panel, so that the display screen can be bent better, avoiding wrinkles in the corners of the display panel, and preventing the display screen from being damaged during the hot bending process.

[0109] In one embodiment, the thermoplastic material used for the second connection layer 112 may be at least one of silicone resin, silicone rubber, polyvinyl butyral (TPU), and acrylic ester.

[0110] The material described in the embodiments of the present application has good light transmittance, improves the transmittance of light of the display panel through the second connecting layer, and can lower its glass transition temperature by changing the molecular weight, so that the glass transition temperature Tg of the second connecting layer prepared by the material described in the embodiments of the present application is in the range of 60 degrees Celsius to 120 degrees Celsius, and has a relatively small Young's modulus during the hot bending process of the display screen, which is beneficial to the hot bending molding of the display screen.

[0111] In an embodiment of the present application, the material of the second connecting layer 112 is designed to include a thermoplastic material, and the glass transition temperature Tg of the thermoplastic material is in the range of 60 degrees Celsius to 120 degrees Celsius. It can be specifically selected according to the thermal bending temperature of the surface layer 111, so that the glass transition temperature Tg of the second connecting layer 112 is lower than the thermal bending temperature of the surface layer 111. When the display module 10 is prepared for a curved screen, the surface layer 111 and the second connecting layer 112 are softened to a certain extent by heating. In one embodiment, the Young's modulus of the thermoplastic material used to prepare the second connecting layer 112 in the elastic state (when the temperature of the second connecting layer 112 is greater than its glass transition temperature Tg, the second connecting layer 112 softens and becomes elastic) is less than or equal to 100 MPa. At this strength, the second connecting layer 112 will not cause strong extrusion on the display panel 114 when bent. The surface layer 111 bends and squeezes the second connecting layer 112 and the display panel 114. The layers are tightly fitted together, and the second connecting layer 112 exerts a small extrusion force on the display panel 114, thereby reducing or even preventing wrinkles on the display panel 114.

[0112] The glass transition temperature (Tg) of the second connecting layer 112 is greater than or equal to 60 degrees Celsius, so that the glass transition temperature of the second connecting layer 112 is greater than the ambient temperature of the display module 10 during use. During the use of the display module 10 after bending and forming, the surface layer 111 and the second connecting layer 112 both have a certain hardness to protect the attached display panel 114. In one embodiment, the thermoplastic material used to make the second connecting layer 112 has a Young's modulus greater than 200 MPa in the glassy state (when the second connecting layer 112 is at a temperature lower than its glass transition temperature (Tg), the second connecting layer 112 hardens into a glassy state). At this hardness, the second connecting layer 112 can better protect the display panel 114 during use of the display module 10. The pressure transmitted from the surface layer 111 (when a person presses the screen during operation) can be accurately and quickly transmitted to the display panel 114, ensuring the sensitivity of the touch function of the display module 10.

[0113] In one possible embodiment, the 180-degree peel force of the second connecting layer 112 is greater than or equal to 1200 gf / inch. The peel force of the second connecting layer 112 can be measured using a 180-degree peel force tester. The second connecting layer 112 serves as a connecting layer between the surface layer 111 and the polarizing layer 113. Testing has shown that the 180-degree peel force of the second connecting layer 112 is greater than or equal to 1200 gf / inch. This ensures that the second connecting layer 112 effectively connects the surface layer 111 and the polarizing layer 113, preventing peeling during bending preparation and post-molding use, thereby improving the connection strength and integrity of the display module 10.

[0114] In one embodiment, the vertical pull-out strength of the second connection layer 112 is greater than or equal to 0.05 MPa. The vertical pull-out strength refers to the stress required for the connection interface to be damaged when the two sides of the laminate are bonded with 40*40 steel plates and strong glue, and then a tensile force is applied in a direction perpendicular to the bonding surface. Specifically, the vertical pulling force is perpendicular to the connection interface to correspond to the scenario where the entire screen is bent and deformed. The 180-degree peeling force is parallel to the connection interface, corresponding to the scenario where the two adjacent layers inside the entire screen move in the direction extending along the connection interface when the entire screen falls. A larger 180-degree peeling force can prevent the display screen from separating during the hot bending process to ensure that the layers inside the display screen are tightly fitted. A larger vertical pull-out strength can prevent the layers inside the display screen from moving in the direction extending along the connection interface due to lateral impact force in scenarios such as the display screen falling, prevent the layers inside the display screen from being dislocated when the display screen falls during use, and improve the anti-collision strength of the display screen.

[0115] In some possible embodiments, as shown in FIG20 , the number of second connecting layers 112 can be at least two, with the at least two second connecting layers 112 stacked together, and at least one of the at least two second connecting layers 112 being made of the thermoplastic material. The second connecting layer 112 includes at least two connecting layers. For example, in the double-layer second connecting layer 112 structure shown in FIG20 , a third connecting layer 1121 and a fourth connecting layer 1122 are stacked together, with at least one of the third connecting layer 1121 and the fourth connecting layer 1122 being made of a thermoplastic material. For example, the third connecting layer 1121 can be made of a thermoplastic material, while the fourth connecting layer 1122 can be made of a non-thermoplastic material, to reduce the Young's modulus of the overall second connecting layer 112 during hot bending.

[0116] In one embodiment, as shown in FIG21 , the number of second connecting layers 112 can be at least two, and the at least two second connecting layers 112 are stacked. The material of any of the at least two second connecting layers 112 is the thermoplastic material. Taking the double-layer second connecting layer 112 structure shown in FIG21 as an example, the third connecting layer 1121 and the fourth connecting layer 1122 are stacked, and the materials of the third connecting layer 1121 and the fourth connecting layer 1122 can both be thermoplastic materials to minimize the Young's modulus of the entire second connecting layer 112 during hot bending.

[0117] In one embodiment, referring to FIG. 22 , when there are at least two second connecting layers 112, and two or more of the at least two second connecting layers 112 are made of thermoplastic materials, for example, in FIG. 22 , the third connecting layer 1121 and the fourth connecting layer 1122 can both be made of thermoplastic materials, and the third connecting layer 1121 and the second backing film 1152 can be made of different thermoplastic materials. In one embodiment, the third connecting layer 1121 can be made of silicone, and the fourth connecting layer 1122 can be made of acrylate. In one embodiment, when three of the second connecting layers 112 are made of thermoplastic materials, the materials of the three second connecting layers 112 can be silicone, acrylate, and polyvinyl butyral, respectively.

[0118] The present application also provides a specific embodiment of a display module, as shown in FIG7 . The display module includes the display screen 11 described in any of the above embodiments, and also includes a support structure 12. The display screen 11 and the support structure 12 are both plate-shaped, and the display screen 11 and the support structure 12 are stacked. The display screen 11 includes a stacked surface layer 111, a polarizing layer 113, a display panel 114, and a back film 115. The support structure 12 is attached to the side of the back film 115 facing away from the display panel 114. The support structure 12 may include a fifth connecting layer 121 and a support member 122. The fifth connecting layer 121 can fix the support member 122 to the back side of the display screen 11.

[0119] As shown in FIG8 , the support member 122 can be at least one layer, such as the double-layer structure shown in FIG8 . The support member 122 is composed of a copper plate and a steel plate stacked together, wherein the copper plate can be fixed by the fifth connecting layer 121 and the back film 115 , and the back film 115 , the fifth connecting layer 121 , the copper plate, and the steel plate are stacked in sequence. The support member 122 with a double-layer structure can form a connection interface between the copper plate and the steel plate. When the display screen is bent, the double-layer structure inside the support member 122 can undergo a certain degree of shear slip along the connection interface, which helps to reduce the stress on the display panel.

[0120] In one embodiment, as shown in FIG9 , the positions of the steel plate and the copper plate can be interchanged, and the steel plate can be fixed by the fifth connecting layer 121 and the back film 115 , and the back film 115 , the fifth connecting layer 121 , the steel plate and the copper plate are stacked in sequence.

[0121] In one embodiment, the backing film 115 of the display screen 11 is made of a thermoplastic material. A thermoplastic material is a material that becomes plastic when heated to a certain temperature and solidifies to increase its hardness when the temperature is lowered. When heated to a certain temperature, the hardness of the thermoplastic material decreases, becoming plastic. When the temperature is lowered, the thermoplastic material returns to a solid state, maintaining a high hardness. Furthermore, the thermoplastic material exhibits an elastic state with plasticity at high temperatures and a glassy state with high hardness at low temperatures. The elastic and glassy states can switch between these two states depending on temperature.

[0122] In the embodiment of the present application, the material of the back film 115 is designed to include a thermoplastic material, and the glass transition temperature Tg of the thermoplastic material is in the range of 60 degrees Celsius to 120 degrees Celsius. It can be specifically selected according to the thermal bending temperature of the surface layer 111, so that the glass transition temperature Tg of the back film 115 is lower than the thermal bending temperature of the surface layer 111. When the display module 10 is prepared for a curved screen, the surface layer 111 and the back film 115 are softened to a certain extent by heating. In one embodiment, the Young's modulus of the thermoplastic material used to prepare the back film 115 in the elastic state (when the temperature of the back film 115 is greater than its glass transition temperature Tg, the back film 115 softens and becomes elastic) is less than or equal to 800 MPa. At this strength, the back film 115 will not cause strong extrusion on the display panel 114 when it is bent. The surface layer 111 bends and squeezes the display panel 114 and the back film 115. The clamping force of the surface layer 111 and the back film 115 on the display panel 114 is small, which reduces or even prevents wrinkles on the display panel 114.

[0123] Furthermore, the glass transition temperature Tg of the back film 115 is greater than or equal to 60 degrees Celsius, so that the glass transition temperature of the back film 115 is greater than the ambient temperature of the display module 10 when in use. During the use of the display module 10 after bending and forming, the surface layer 111 and the back film 115 both have a certain hardness to protect the display panel 114 sandwiched therebetween. In one embodiment, the thermoplastic material used to make the back film 115 has a Young's modulus greater than 1000 MPa in the glassy state (when the back film 115 is at a temperature lower than its glass transition temperature Tg, the back film 115 hardens and becomes a glassy state). At this hardness, the back film 115 can better support the display panel 114 when the display module 10 is in use, preventing the display panel 114 from being deformed or even damaged by stress.

[0124] In one embodiment, the material of the second connecting layer 112 may include a thermoplastic material, specifically a thermoplastic resin. The glass transition temperature Tg of the second connecting layer 112 may be in the range of 60 degrees Celsius to 120 degrees Celsius. The Young's modulus of the thermoplastic material used to prepare the second connecting layer 112 in the elastic state is less than or equal to 100 MPa, and the Young's modulus of the thermoplastic material used to prepare the second connecting layer 112 in the glassy state is greater than 200 MPa.

[0125] In one embodiment, when preparing the display module 10, a thermoplastic resin heated to an elastic state can be first applied between the flat surface layer 111 and the polarizing layer 113, and a certain clamping force is applied to the surface layer 111 and the polarizing layer 113. A certain bending force is applied to the edges and corners of the display module 10 where bending is required. Because the thermoplastic resin is in an elastic state, it can bend with the surface layer 111. In addition, since the backing film 115 is also a thermoplastic material and is in an elastic state at this temperature, and the polarizing layer 113 and the display panel 114 do not have high hardness, the second connecting layer 112, the polarizing layer 113, the display panel 114, and the backing film 115 can all bend well under the pressure of the surface layer 111, and the layers are tightly bonded to each other. After bending to a predetermined degree, the temperature is lowered, and the second connecting layer 112 formed by the thermoplastic resin gradually solidifies and securely connects the surface layer 111 and the polarizing layer 113. The backing film 115 also solidifies to support the back side of the display panel 114. During the entire bending process, the display panel 114 will not be subjected to too much squeezing force from both sides, thereby reducing the degree of wrinkles, or even completely eliminating wrinkles, thereby improving the display effect of the display panel 114 .

[0126] The present application provides an electronic device 100, as shown in Figures 1 and 2, comprising the display module 10 described in the above embodiment, and further comprising a housing 20, wherein the housing 20 is connected to the display module 10. In the present application, at least one of the back film 115 and the second connecting layer 112 in the display screen 11 can be made of a thermoplastic material. When the display module 10 of the electronic device 100 is provided with a curved portion, one of the back film 115 and the second connecting layer 112 can be in an elastic state with a low Young's modulus when bent, thereby alleviating the compression on the display panel 114, reducing or even eliminating wrinkles on the display panel 114, and improving the display clarity of the electronic device 100.

[0127] The electronic devices in this application may include, but are not limited to, mobile phones, tablet computers, laptop computers, ultra-mobile personal computers, handheld computers, walkie-talkies, Internet-connected televisions, wearable devices, vehicle-mounted devices, driving recorders, and security equipment, etc. The embodiments of this application do not impose any particular restrictions on the form of the above-mentioned electronic devices.

[0128] For example, referring to FIG1 , the electronic device 100 in the embodiment of the present application is described using a curved screen mobile phone as an example. FIG1 is a perspective schematic diagram of the electronic device 100 provided in the embodiment of the present application. FIG2 is a formal schematic diagram of the electronic device 100 provided in the embodiment of the present application. The electronic device 100 includes a display module 10 and a housing 20. The display module 10 is connected to the housing 20. The housing 20 may include a middle frame and a back cover. The middle frame and the back cover may be a separate structure or an integrated structure, which is not specifically limited in the embodiment of the present application.

[0129] The display module 10 is mounted on the housing 20, wherein the housing 20 has a accommodating cavity, and components such as the circuit board, electronic components, camera module, processor and battery of the electronic device 100 can be installed in the accommodating cavity of the housing 20. The display module 10 covers the opening of the accommodating cavity of the housing 20, and the display module 10 and the housing 20 are sealed to form a sealed accommodating cavity, which protects the components in the accommodating cavity from water and dust. The housing 20 can be made of materials such as metal (such as aluminum alloy, titanium alloy and stainless steel), plastic (such as acrylonitrile-butadiene-styrene, polycarbonate and polypropylene) or glass (such as anti-glare glass). The housing 20 made of materials such as metal, plastic or glass can meet the requirements of wear resistance, impact resistance, corrosion resistance and aesthetics of the appearance of the electronic device 100.

[0130] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A display screen, characterized in that, It includes a display panel and a back film connected in a stacked manner. The material of the back film includes a thermoplastic material. The glass transition temperature of the thermoplastic material is in the range of 60 degrees Celsius to 120 degrees Celsius. The Young's modulus of the thermoplastic material in the elastic state is less than or equal to 800 MPa, and the Young's modulus of the thermoplastic material in the glassy state is greater than 1000 MPa.

2. The display screen according to claim 1, characterized in that, The thermoplastic material includes at least one of polycarbonate, polyvinyl butyral, polypropylene, polyethylene, and polymethyl methacrylate.

3. The display screen according to claim 1 or 2, characterized in that, The back film includes at least two back films stacked. The at least two back films include a first back film, and the material of the first back film is the thermoplastic material.

4. The display layer according to claim 3, characterized in that, The at least two back films include a second back film, and the materials of the first back film and the second back film are different thermoplastic materials.

5. The display screen according to any one of claims 1-4, characterized in that, The display screen further includes a first connection layer. The material of the first connection layer includes a pressure-sensitive material. The first connection layer is located between the display panel and the back film and fixedly connects the display panel and the back film.

6. The display screen according to any one of claims 1-5, characterized in that, The display screen further includes a stacked surface layer, a second connection layer, and an optical film layer. The second connection layer fixedly connects the surface layer and the optical film layer. The display panel is fixed between the optical film layer and the back film. The material of the second connection layer includes a thermoplastic material. The glass transition temperature of the thermoplastic material for preparing the second connection layer is in the range of 60 degrees Celsius to 120 degrees Celsius. The Young's modulus of the thermoplastic material for preparing the second connection layer in the elastic state is less than or equal to 100 kPa, and the Young's modulus of the thermoplastic material for preparing the second connection layer in the glassy state is greater than 200 kPa.

7. The display screen according to claim 6, characterized in that The 180-degree peel strength of the second connection layer is greater than or equal to 1200 g / inch, and / or the vertical pull-out strength of the second connection layer is greater than or equal to 0.05 MPa.

8. The display screen according to claim 6 or 7, characterized in that, The thermoplastic material includes at least one of silicone resin, silicone rubber, polyvinyl butyral, and acrylate.

9. The display screen according to any one of claims 6-8, characterized in that, The second connection layer includes at least two connection layers stacked. The at least two connection layers include a third connection layer, and the material of the third connection layer is the thermoplastic material.

10. The display layer according to claim 9, wherein The at least two connection layers include a fourth connection layer, and the materials of the third connection layer and the fourth connection layer are different thermoplastic materials.

11. A display screen, characterized in that, It includes a surface layer, a second connection layer, and an optical film layer stacked in sequence. The second connection layer fixedly connects the surface layer and the optical film layer. The material of the second connection layer includes a thermoplastic material. The glass transition temperature of the thermoplastic material is in the range of 60 degrees Celsius to 120 degrees Celsius. The Young's modulus of the thermoplastic material for preparing the second connection layer in the elastic state is less than or equal to 100 kPa, and the Young's modulus of the thermoplastic material for preparing the second connection layer in the glassy state is greater than 200 kPa.

12. The display screen according to claim 11, characterized in that, The 180-degree peel strength of the second connection layer is greater than or equal to 1200 g / inch, and / or the vertical pull-out strength of the second connection layer is greater than or equal to 0.05 MPa.

13. The display screen according to claim 11 or 12, characterized in that, The manufacturing material of the second connection layer includes at least one of silicone resin, silicone rubber, polyvinyl butyral, and acrylate.

14. The display screen according to any one of claims 11-13, characterized in that, The second connection layer includes at least two connection layers arranged in a stacked manner, the at least two connection layers include a third connection layer, and the material of the third connection layer is the thermoplastic material.

15. The display layer according to claim 14, wherein The at least two connection layers include a fourth connection layer, and the materials of the third connection layer and the fourth connection layer are different thermoplastic materials.

16. A display module, characterized in that, It includes the display screen and the support member according to any one of claims 1-15, and the support member is located inside the display screen to support the display screen.

17. An electronic device, characterized in that, It includes the display module according to claim 16, and further includes a housing, and the housing is fixedly connected to the peripheral edge of the display module.

Images