Patent Publication Number: US-2022212447-A1

Title: Cover plate, display device and method for preparing cover plate

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. application Ser. No. 16/646,835 filed on Mar. 12, 2020, which is the U.S. national phase of PCT Application No. PCT/CN2019/107724 filed on Sep. 25, 2019, which claims a priority to Chinese Patent Application No. 201811397315.9 filed on Nov. 22, 2018, the disclosures of which are incorporated in their entirety by reference herein. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to the technical field of producing a display product, and in particular, to a cover plate, a display device, and a method for preparing the cover plate. 
     BACKGROUND 
     In the research of display screens, the development of foldable products is in an initial stage. Flexible organic light-emitting diode (OLED) screens can be bent and attached to ensure the realization of foldable products. 
     SUMMARY 
     The present disclosure provides the following technical solutions. 
     An embodiment of the present disclosure provides a cover plate, including a plurality of non-bendable portions and at least one bendable portion, in which every two adjacent non-bendable portions are connected by one bendable portion; and the cover plate includes a first end and a second end arranged opposite to each other, the plurality of non-bendable portions includes a first non-bendable portion located at the first end and a second non-bendable portion located at the second end, the first non-bendable portion including a first curved surface structure, and the second non-bendable portion including a second curved surface structure. 
     In one embodiment, the first curved surface structure is located at an end of the first non-bendable portion away from the second end, and the second curved surface structure is located at an end of the second non-bendable portion away from the first end. 
     In one embodiment, the cover plate includes a first surface and a second surface arranged opposite to each other, and the first curved surface structure and the second curved surface structure are both curved surface structures bent toward the first surface. 
     In one embodiment, when the bendable portion is in a folded state, the bendable portion moves close to the first non-bendable portion to form a curved structure having the same curvature as the first curved surface structure. 
     In one embodiment, the cover plate includes one bendable portion, the first non-bendable portion further includes a first planar structure located between the first curved surface structure and the bendable portion, and the second non-bendable portion further includes a second planar structure located between the second curved surface structure and the bendable portion. 
     In one embodiment, the cover plate includes at least two bendable portions, the at least two bendable portions includes a first bendable portion connected to the first non-bendable portion and a second bendable portion connected to the second non-bendable portion; and the plurality of non-bendable portions further includes at least one third non-bendable portion located between the first bendable portion and the second bendable portion, in which the third non-bendable portion is of a planar structure. 
     In one embodiment, a thickness of the plurality of non-bendable portions is greater than or equal to a thickness of the bendable portion. 
     In one embodiment, the bendable portion includes at least one flexible thin film made of a flexible transparent material along a thickness direction of the bendable portion. 
     In one embodiment, the bendable portion is made of flexible glass, and the non-bendable portion is made of rigid glass. 
     An embodiment of the present disclosure further provides a display device including a flexible display panel and the cover plate described above. 
     In one embodiment, the flexible display panel is connected to the cover plate through attaching, and a portion of the flexible display panel attached to the first curved surface structure and the second curved surface structure is in a curved state. 
     In one embodiment, the above display device further includes an optical adhesive layer, the optical adhesive layer is located between the flexible display panel and the cover plate for connecting the flexible display panel and the cover plate together, a surface of the cover plate away from the flexible display panel is a planar surface, a thickness of the bendable portion is less than the thickness of the non-bendable portion, so that when the cover plate is attached to the flexible display panel, a gap is formed between the bendable portion and the flexible display panel, and the optical adhesive layer has a filling portion capable of filling the gap at a position corresponding to the bendable portion. 
     In one embodiment, the above display device further includes an optical adhesive layer, the optical adhesive layer is located between the flexible display panel and the cover plate for connecting the flexible display panel and the cover plate together, a thickness of the bendable portion is equal to a thickness of the non-bendable portion, and a surface of the optical adhesive layer away from the flexible display panel is a planar surface. 
     In one embodiment, the flexible display panel includes a bending region connected to a main circuit board of the display device, and the display device further includes a spacer located on the surface of the bending region away from the cover plate. 
     An embodiment of the present disclosure further provides a method for preparing a cover plate, including: forming a plurality of non-bendable portions and at least one bendable portion; and connecting a first connection region of the plurality of non-bendable portions, which is configured to connect a corresponding bendable portion, and a second connection region of the at least one bendable portion, which is configured to connect a corresponding non-bendable portion, to form the cover plate described above. 
     In one embodiment, the method specifically includes: forming the non-bendable portion in a molten state and the bendable portion in a molten state; and blending the first connection region and the corresponding second connection region, and then curing the first connection region and the corresponding second connection region. 
     In one embodiment, the step of connecting the first connection region of the plurality of the non-bendable portions, which is configured to connect the corresponding foldable portion, and the second connection region of the at least one bendable portion, which is configured to connect the corresponding non-bendable portion, to form the above cover plate specifically includes: heating and melting the first connection region and the second connection region, to connect the plurality of non-bendable portions and the corresponding bendable portion; and curing the first connection region and the second connection region after blending them. 
     In one embodiment, the step of connecting the first connection region of the plurality of the non-bendable portions, which is configured to connect the corresponding foldable portion and the second connection region of the at least one bendable portion, which is configured to connect the corresponding non-bendable portion, to form the above cover plate specifically includes: bonding the first connection region and the corresponding second connection region by an optical adhesive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view I showing a structure of a cover plate according to an embodiment of the present disclosure; 
         FIG. 2  is a schematic view II showing a structure of a cover plate according to another embodiment of the present disclosure; 
         FIG. 3  is a schematic view III showing a structure of a cover plate according to still another embodiment of the present disclosure; 
         FIG. 4  is a schematic view IV showing a structure of a cover plate according to still another embodiment of the present disclosure; 
         FIG. 5  is a schematic view V showing a structure of a display device according to an embodiment of the present disclosure; and 
         FIG. 6  is a schematic view VI showing a structure of a display device according to another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In order to illustrate the purposes, technical solution and advantages in the embodiments of the present disclosure in a clearer manner, the technical solutions in the embodiments of the present disclosure will be described hereinafter in conjunction with the drawings in a clear and complete manner. Obviously, the following embodiments relate to a part of, rather than all of, the embodiments of the present disclosure. Based on the described embodiments of the present disclosure, a person skilled in the art may obtain the other embodiments, which also fall within the scope of the present disclosure. 
     In related art, the foldable products have the following problems after bending: the folded position is a folded curved surface screen, and both sides thereof without bending are flat, therefore this asymmetrical display state brings a very bad experience to the user. 
     An object of the present disclosure is to provide a cover plate, a display device, and a method for preparing a cover plate, which solve the problem of an asymmetric display state of the screen when being in a folded state. 
     &lt;Cover Plate&gt; 
     As shown in  FIGS. 1 to 4 , an embodiment of the present disclosure provides a cover plate  1 . The cover plate  1  includes a plurality of rigid non-bendable portions  10  and at least one flexible bendable portion  11 . Every two adjacent non-bendable portions  10  are connected by one bendable portion  11 . The cover plate  1  includes a first end and a second end arranged opposite to each other. The plurality of non-bendable portions  10  includes a first non-bendable portion  101  located at the first end and a second non-bendable portion  102  located at the second end. The first non-bendable portion  101  comprises a first curved surface structure  1011 , and the second non-bendable portion  102  comprises a second curved surface structure  1021 . 
     For the cover plate  1  of this embodiment, a rigid non-bendable portion  10  and a flexible bendable portion  11  are combined. The cover plate  1  includes a first end and a second end arranged opposite to each other, the first non-bendable portion  101  located at the first end includes a first curved surface structure  1011 , and the second non-bendable portion  102  located at the second end includes a second curved surface structure  1021 . When the cover plate  1  is in an unfolded state or in a folded state, a display effect that both sides opposite to each other may be formed into a curved surface, thereby improving the user experience. 
     The number of the bendable portions  11  can be set according to actual needs, and is not particularly limited. For example, in this embodiment, the bendable portion  11  may be one, or two or more. For example,  FIG. 1  shows a schematic view of the structure of a cover plate  1  having one bendable portion  11 ,  FIG. 2  shows a schematic view of the structure of a cover plate  1  having three bendable portions  11 , and  FIGS. 3 and 4  show a schematic view of the structure of a cover plate  1  having two bendable portions  11 . When the cover plate  1  is in an unfolded state, that is, when a full screen is displayed, a display effect that both sides are curved surfaces can be achieved by setting the first curved surface structure  1011  and the second curved surface structure  1021 . When any one of the bendable portions  11  is displayed in a folded state, a display effect that both sides are curved surfaces is also achieved. For example,  FIG. 1  is a schematic view showing a folded state of a cover plate  1  having a bendable portion  11 . As shown in  FIG. 1 , when the cover plate  1  is in a folded state, the first curved surface structure  1011  and the second curved surface structure  1021  cooperate with the curved surface at the bending position, so that a display effect that both sides of the cover plate  1  are curved surfaces is achieved along the first direction (X direction).  FIGS. 3 and 4  show a schematic view showing the folded states at different bending positions when there are the two bending portions  11 . As shown in  FIGS. 3 and 4 , regardless how the bend is made, and regardless in which bendable portion  11  the bend position is located, a display effect that both sides are curved surfaces can be achieved, thereby improving the user experience. 
     The cover plate  1  of this embodiment is capable of realizing the adjustability of the size of the display region and the adjustability of the display position by providing one or two or more bendable portions  11 . For example, the cover plate  1  having one bendable portion  11  shown in  FIG. 1  is folded in a center folded state at the bendable portion  11 , thereby realizing ½ area display. The cover plate  1  shown in  FIG. 2  is in an unfolded state, that is, a full screen is displayed. At this time, a display effect that both sides of the cover plate  1  in an unfolded state are still curved surfaces can be achieved by setting the first curved surface structure  1011  and the second curved surface structure  1021 . The folded state of the cover plate  1  shown in  FIG. 3  can realize ⅓ area display or ⅔ area display. The folded state of the cover plate  1  shown in  FIG. 4  can realize ⅓ area display. In actual use, the size of the display region can be freely adjusted according to the setting of the position of the bendable portion  11 , and the area of the display module can be adjusted by bending the bendable portion  11  at different positions, so that it is convenient to carry. 
     In this embodiment, the first curved surface structure  1011  is located at an end of the first non-bendable portion  101  away from the second end, and the second curved surface structure  1021  is located at an end of the second non-bendable portion  102  away from the first end. 
     In this embodiment, the cover plate  1  includes a first surface for connecting the flexible display panel  2  (as shown in  FIG. 6 ) and a second surface arranged opposite to the first surface. The first curved surface structure  1011  and the second curved surface structure  1021  are both curved surface structures bent toward the first surface. 
     The first curved surface structure  1011  and the second curved surface structure  1021  have the same bending direction, thereby being capable of improving the display effect. 
     Typically, when the cover plate  1  is in a unfolded state, the first curved surface structure  1011  and the second curved surface structure  1021  have the same curvature, so that a symmetrical display effect is achieved on opposite sides of the cover plate  1 , thereby being capable of improving the user experience. 
     In this embodiment, when the bendable portion  11  is in a folded state, a portion of the bendable portion  11  moves close to the first non-bendable portion  101  to form a curved structure having the same curvature as the first curved surface structure  1011 , or to form a curved structure having a curvature different from the first curved surface structure  1011 . Typically, a portion of the bendable portion  11  moves close to the first non-bendable portion  101  to form a curved structure having the same curvature as the first curved surface structure  1011 . It should be noted that, in the schematic view of the folded state of the cover plate  1  having a bendable portion  11  shown in  FIG. 1 , the portion of the bendable portion  11  proximate to the first non-bendable portion  101  has a curvature different from the first curved surface structure  1011 , but it is not a limitation on the protection range of the cover plate  1  of the present disclosure. 
     In one embodiment, as shown in  FIG. 1 , the cover plate  1  includes a bendable portion  11 , the first non-bendable portion  101  further includes a first planar structure  1012  located between the first curved surface structure  1011  and the bendable portion  11 , and the second non-bendable portion  102  further includes a second planar structure  1022  located between the second curved surface structure  1021  and the bendable portion  11 . 
     In the folded state, the first planar structure is a planar display region, and both sides of the first planar structure are curved surface display regions. Similarly, the second planar structure is a planar display region, and both sides of the second planar structure are curved surface display regions, thereby being capable of improving the display effect. 
     In another embodiment, the cover plate  1  includes at least two bendable portions  11 . At this time, there may be various specific structures of the cover plate  1 . Exemplarily, as shown in  FIGS. 2 to 4 , there are at least two bendable portions  11 , and the at least two bendable portions  11  include a first bendable portion  111  connected to the first non-bendable portion  101  and a second bendable portion  112  connected to the second non-bendable portion  102 . The non-bendable portion  10  further includes at least one third non-bendable portion  103  located between the first bendable portion  111  and the second bendable portion  112 . The third non-bendable portion  103  is of a planar structure. 
     In this embodiment, the thickness of the non-bendable portion  10  is greater than or equal to the thickness of the bendable portion  11 . Thus, the bendability of the bendable portion  11  is ensured. 
     There may be various specific structural forms of the bendable portion  11 . For example, in this embodiment, the bendable portion  11  includes at least one flexible thin film made of a flexible transparent material along its thickness direction. Exemplarily, the bendable portion  11  is made of flexible glass, and the non-bendable portion  10  is made of rigid glass. 
     &lt;Display Device&gt; 
     As shown in  FIGS. 5 and 6 , an embodiment of the present disclosure further provides a display device including a flexible display panel  2  and the above cover plate  1 . The combination of the flexible display panel  2  and the above cover plate  1  can realize the display effect that the two opposite sides of the display module are curved surfaces, thereby improving the user experience. 
     There are various manners of connecting the flexible display panel  2  and the cover plate  1 . For example, in this embodiment, the flexible display panel  2  is connected to the cover plate  1  through attaching, and a portion of the flexible display panel  2  attached to the first curved surface structure  1011  and the second curved surface structure  1021  is in a curved state. 
     Exemplarily, the flexible display panel  2  and the cover plate  1  may be attached by an optical adhesive layer (not shown in the figure). Since the display surface of the flexible display panel  2  is generally a planar surface, the surface of the optical adhesive layer connected to the flexible display panel  2  is a planar surface in order to avoid affecting the display effect. The surface of the optical adhesive layer connected to the cover plate  1  is used to match the structure of the surface of the cover plate  1  connected to the optical adhesive layer. 
     In one embodiment, an optical adhesive layer is provided between the flexible display panel  2  and the cover plate  1 . The surface of the cover plate  1  away from the flexible display panel  2  is a planar surface. The thickness of the bendable portion  11  is smaller than the thickness of the non-bendable portion  10 , so that when the cover plate  1  is attached to the flexible display panel  2 , a gap is formed between the bendable portion  11  and the display panel  2 , and the optical adhesive layer has a filling portion capable of filling the gap at a position corresponding to the bendable portion. For example, the thickness of the non-bendable portion  10  may be 0.5 mm, and the thickness of the bendable portion  11  may be 0.1 mm, but is not limited thereto. 
     When the attaching process of the flexible display panel  2  and the cover plate  1  is performed, an optical adhesive layer may be provided on the cover plate  1  to form a filling portion, and then an optical adhesive layer may be provided to connect the flexible display panel  2  and the cover plate  1 . 
     In another embodiment, an optical adhesive layer is provided between the flexible display panel  2  and the cover plate  1 . The thickness of the bendable portion  11  is equal to the thickness of the non-bendable portion  10 , and the surface of the optical adhesive layer away from the flexible display panel  2  is a planar surface. 
     In this embodiment, in order to ensure the bending performance of the bendable portion  11 , the bendable portion  11  may include several layer of flexible thin film. For example, the bendable portion  11  includes 5 layers of flexible thin films made of flexible glass. Each layer of the flexible thin film has a thickness of 0.1 mm, and the thickness of the non-bendable portion  10  is 0.5 mm, but is not limited thereto. 
     In this embodiment, as shown in  FIG. 5 , the flexible display panel  2  includes a bending region connected to a main circuit board (not shown in the figure) of the display device, and the display device further includes a spacer  3  located on a surface of the bending region away from the cover plate  1 . Providing the spacer  3  is capable of preventing the flexible display panel  2  from being bent excessively, and reducing the risk of damage to the flexible display panel  2  during the bending process. 
     The display device of the embodiments may include any product or component having a display function, such as a liquid crystal television, a liquid crystal display, a digital photo frame, a mobile phone, and a tablet computer. Further, the display device may further include a flexible circuit board, a printed circuit board, and a backplane. It has application value in the fields of augmented reality (AR)/virtual reality (VR) and other fields in the future. 
     &lt;Method for Preparing a Cover Plate&gt; 
     There are many methods for preparing a cover plate. An embodiment of the present disclosure provides a method for preparing a cover plate, which is applied to the above cover plate and includes: forming a plurality of non-bendable portions and at least one bendable portion; and connecting a first connection region of the plurality of the non-bendable portions, which is configured to connect a corresponding foldable portion, and a second connection region of the at least one bendable portion, which is configured to connect a corresponding non-bendable portion, to form the above cover plate. 
     There are various manner of connecting the bendable portion and the non-bendable portion. For example, the connection can be made by melting or by bonding. Several connection manner of the embodiments will be described hereafter. 
     In one embodiment, the method for preparing the cover plate specifically includes: forming a rigid non-bendable portion in a molten state and a flexible bendable portion in a molten state; and blending the first connection region and the corresponding second connection region, and then curing the first connection region and the corresponding second connection region. 
     Hereafter, a cover plate having a bendable portion is taken as an example to explain the preparing process of the cover plate in detail. Ordinary rigid glass (such as GG3 glass) is put into two molds, to make the rigid glass be in a molten state and be ready for use (i.e., forming the first non-bendable portion and the second non-bendable portion in the molten state). Then, one mold containing flexible glass is added between the two molds, to make the flexible glass be in a molten state and be ready for use (i.e., forming a bendable portion). Then, the three molds are connected, the temperature is well controlled, the joints of the three molds are opened, and the temperature is gradually reduced to achieve the connection between the rigid glass and the flexible glass in the three molds. Then a cover plate is formed after curing. 
     The first curved surface structure on the first non-bendable portion and the second curved surface structure on the second non-bendable portion can be directly formed by using a mold of the corresponding structure, or can be formed by processing after curing. The processing method may be, for example, shown as follows. After curing the rigid glass and flexible glass in three molds, the surfaces of the connected rigid glass and flexible glass are polished and flattened by grinding and CNC cutting (heterosexual cutting), and then the edges of the rigid glass are hot-bent to form a first curved surface structure on the first non-bendable portion and a second curved surface structure on the second non-bendable portion, thereby achieving a final mass production. 
     In one embodiment, the step of connecting the first connection region of the plurality of the non-bendable portions, which is configured to connect the corresponding foldable portion, and the second connection region of the at least one bendable portion, which is configured to connect the corresponding non-bendable portion, to form the above cover plate specifically includes: heating and melting the first connection region and the second connection region, to connect the plurality of non-bendable portions and the corresponding bendable portion; and curing the first connection region and the second connection region after blending them. 
     Specifically, the rigid glass material and the flexible glass material are put into corresponding planar molds, respectively, and then both of them are pre-baked, and attached when cured to a certain degree. Then, the respective melting temperatures of the rigid glass material and the flexible glass material are adjusted to fuse the joints between them. After the fusion, the temperature is gradually reduced. After the curing, the treatment of the binding parts of them is completed by grinding, CNC cutting (heterosexual cutting) and other treatments. Then, the edge of the rigid glass is hot-bent to form a first curved surface structure and a second curved surface structure. 
     In this embodiment, the first curved surface structure and the second curved surface structure may also be formed in a mold of the corresponding structure directly through processes such as melting and curing. 
     In this embodiment, the material of the rigid non-bendable portion may be CG material (composite material), and the material of the flexible bendable portion may be CG material (composite material) or flexible PET (polyethylene terephthalate) material, etc. 
     In one embodiment, the step of connecting the first connection region of the plurality of the non-bendable portions, which is configured to connect the corresponding foldable portion, and the second connection region of the at least one bendable portion, which is configured to connect the corresponding non-bendable portion, to form the above cover plate specifically includes: bonding the first connection region and the corresponding second connection region by an optical adhesive. 
     The above descriptions are optional embodiments of the present disclosure. It should be noted that one skilled in the art would make several improvements and substitutions without departing from the principles of the present disclosure. These improvements and modifications should also be regarded as the protection scope of the present disclosure.