A flexible cover plate and a flexible display device

Abstract

The present invention discloses a flexible cover plate, a flexible display device, and a method for thinning the flexible cover plate. The flexible cover plate is used to cover a flexible screen, and the flexible screen includes a first display area, a second display area, and a bending area connecting the first display area and the second display area. The second display area is set as a bendable area. The flexible cover plate includes a first area for covering the first display area, a second area for covering the second display area, and a third area for covering the bending area. Among them, the thickness of the second area and the third area is less than that of the first area, and the surfaces of the first area, the second area, and the third area away from the flexible screen are flush. By reducing the thickness of the flexible cover plate covering the bending area and the second display area, the rigidity is reduced, and the bendability at this position is improved, so that the rigidity of the first area is greater than that of the second area and the third area, and the bendability of the second area and the third area is greater than that of the first area, realizing that the second area and the third area are bendable.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible display. More specifically, it relates to a flexible cover plate and a flexible display device. Background Art

[0002] In recent years, products with foldable display screens have been increasingly widely used. There is great research potential regarding their bending form, bending radius, and impact resistance improvement. Currently, foldable mobile phones often use colorless polyimide film (CPI) as the flexible foldable cover plate to achieve bendability. However, due to insufficient scratch resistance and poor feel on the surface of CPI, the user experience of existing products is not good. Although the glass cover plates used in fixed-curved mobile phones have good feel and mechanical properties, they do not have the ability to bend. How to make a mobile phone have both the characteristics of fixed-curved and flexible folding has become a problem to be solved. The traditional design for a fixed-curved cover plate plus a flexible cover plate generally uses the method of splicing a glass cover plate and a flexible CPI cover plate. This causes fitting gaps due to other problems such as fitting accuracy or adhesive material selection during the cover plate fitting process, and an integrated screen display cannot be achieved. Summary of the Invention

[0003] An object of the present invention is to provide a flexible cover plate and a flexible display device to eliminate the gap between the fixed-curved screen and the foldable screen cover plate and achieve an integrated screen display.

[0004] According to one aspect of the present invention, there is provided a flexible cover plate for covering a flexible screen. The flexible screen includes a first display area, a second display area, and a bending area connecting the first display area and the second display area. The second display area is set as a bendable area. The flexible cover plate includes a first area for covering the first display area, a second area for covering the second display area, and a third area covering the bending area. Among them, the thickness of the second area and the third area is less than the thickness of the first area, and the surfaces of the first area, the second area, and the third area away from the flexible screen are flush.

[0005] Preferably, the second display area includes a third display area, a fourth display area, and a bendable area connecting the third display area and the fourth display area. A thinning area is provided at a position corresponding to the bendable area of the second area of the flexible cover plate.

[0006] Preferably, the thinning area is set as a groove structure, and the thickness of the bottom wall of the groove is half of the thickness of the second area.

[0007] Preferably, the cross-section of the groove is trapezoidal or arc-shaped.

[0008] Preferably, an optically transparent organic coating is applied to the side surface of the second region and the third region close to the flexible screen, and the optically transparent organic coating in the third region is set to an inward concave arc corresponding to the bending region.

[0009] Preferably, the thickness of the optically transparent organic coating in the second region is 0.04 mm.

[0010] Preferably, the thickness of the third region of the flexible cover plate gradually decreases from the thickness of the first region to the thickness of the second region.

[0011] Preferably, the side surface of the third region close to the flexible screen is set to an inward concave arc corresponding to the bending region.

[0012] Preferably, the thickness of the first region of the flexible cover plate is 0.5 mm.

[0013] Preferably, the thickness of the second region of the flexible cover plate is in the range of 0.08 mm to 0.1 mm.

[0014] According to another aspect of the present invention, a flexible display device is provided, including a flexible screen and the flexible cover plate according to any one of the above.

[0015] According to still another aspect of the present invention, a method for thinning a flexible cover plate is provided. The flexible cover plate is made of a glass plate and includes the following steps:

[0016] Divide the first region, the second region and the third region on the glass plate, and apply an acid-resistant protective layer on the surface of the first region;

[0017] Immerse the glass plate in an etching solution to etch and thin the second region and the third region.

[0018] Preferably, the following steps are further included:

[0019] Divide the thinning region on the second region, and apply an acid-resistant protective layer on the surface of the third region and the second region except the thinning region;

[0020] Immerse the glass plate in an etching solution to etch and thin the thinning region.

[0021] Preferably, the following steps are further included:

[0022] Strengthen the etched glass plate by an ion exchange method.

[0023] The beneficial effects of the present invention are as follows:

[0024] The thickness of the second region and the third region of the flexible cover plate of the present invention is less than that of the first region, and the one-side surfaces of the first region, the second region, and the third region away from the flexible screen are flush. By reducing the thickness of the flexible cover plate covering the bending region and the second display region, the rigidity of the flexible cover plate is reduced, and the bendability at this position is improved, so that the rigidity of the first region is greater than that of the second region and the third region, and the bendability of the second region and the third region is greater than that of the first region, enabling the second region and the third region to be bent, and realizing that the flexible cover plate has a certain thickness while being able to be bent and maintaining good impact resistance. Brief Description of the Drawings

[0025] The following further elaborates on the specific implementation manners of the present invention with reference to the drawings.

[0026] Figure 1 A structural schematic diagram showing the unfolded state of the flexible cover plate of the present invention.

[0027] Figure 2 A structural schematic diagram showing the folded state of the flexible cover plate of the present invention.

[0028] Figure 3 A structural schematic diagram showing the flat state of the flexible cover plate of the present invention.

[0029] Figure 4 A structural schematic diagram showing the flexible cover plate of the present invention provided with a thinning region.

[0030] Figure 5 A structural schematic diagram showing the flexible cover plate of the present invention provided with a coating.

[0031] Figure 6 A structural schematic diagram showing the flexible cover plate of the present invention provided with a thinning region and a coating.

[0032] Figure 7 A flowchart showing the thinning method of the flexible cover plate of the present invention. Detailed Description of the Invention

[0033] To more clearly illustrate the present invention, the following further describes the present invention with reference to the preferred embodiments and the drawings. Similar components in the drawings are denoted by the same reference numerals. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0034] To facilitate the understanding of the flexible cover plate provided by the embodiments of the present application, first, its application scenario is described. The flexible cover plate is applied to foldable mobile terminals, such as common mobile terminals like mobile phones and tablet computers. Figure 1 Shows the shape of the flexible cover plate of the mobile terminal when unfolded, Figure 2 Shows the shape of the flexible cover plate of the mobile terminal after folding. First, asFigure 1 As shown, when the mobile terminal is unfolded, the flexible cover plate 10 is also unfolded, generally in a U shape, as shown in the figure. At this time, the upper and lower sides and the left side of the mobile terminal form a display screen. As Figure 2 shown, when the mobile terminal is folded, the flexible cover plate 10 is also folded to form a three-fold structure. At this time, the upper side and the left side of the mobile terminal form a display screen.

[0035] The flexible cover plate 10 provided in the embodiment of the present application covers the surface of the flexible screen, is used to protect the flexible screen, and improve the touch feeling. Among them, the flexible screen can adopt an integral flexible display screen, or can adopt a display screen spliced by a rigid screen and a flexible display screen. The flexible screen in this embodiment is an integral flexible display screen, including a first display area 21, a second display area 22, and a bending area 23 connecting the first display area 21 and the second display area 22. Among them, the second display area 22 is set as a foldable area. As shown in the figure, when the mobile terminal is unfolded, the first display area 21, the second display area 22, and the bending area 23 form a generally U-shaped display screen, that is, the bending area 23 is a static bending area, which only needs to be bent during product production, and only the second display area 22 is folded during use, and the relative positions of the first display area 21 and the bending area 23 remain unchanged.

[0036] As Figure 3 shown, for easy understanding, the flexible cover plate 10 is unfolded into a plane. The flexible cover plate 10 is used to cover the flexible screen, including a first area 11 for covering the first display area 21, a second area 12 for covering the second display area 22, and a third area 13 for covering the bending area 23. In order to protect the flexible screen, the flexible cover plate 10 needs to have a certain strength. At the same time, since the third area 13 and the second area 12 need to be bent, the flexible cover plate 10 at this place also needs to have a certain bendability. In order to enable the flexible cover plate 10 to meet the requirements of strength and bendability at the same time, the thickness of the second area 12 and the third area 13 of the flexible cover plate 10 provided in the embodiment of the present application is less than the thickness of the first area 11, and the surfaces of the first area 11, the second area 12, and the third area 13 away from the flexible screen are flush. That is, by reducing the thickness of the flexible cover plate covering the bending area 23 and the second display area 22, the rigidity of the flexible cover plate is reduced, and the bendability at this place is improved, so as to achieve that the rigidity of the first area 11 is greater than the rigidity of the second area 12 and the third area 13, and the bendability of the second area 12 and the third area 13 is greater than the bendability of the first area 11, so that the second area 12 and the third area 13 can be bent, and the flexible cover plate 10 can have a certain thickness while being able to be bent and maintain good impact resistance.

[0037] The flexible cover plate 10 provided in this example can be made of glass. The main structure of the commonly used aluminosilicate glass is a silicate skeleton. In such a rigid structure, when bent, the maximum bending normal stress on the cross-section acts on the point farthest from the neutral axis, and fractures generally start near this point. However, when the glass is thin enough (<0.1 mm), the upper and lower surfaces are close enough to the layer where the neutral axis is located, and the normal stress on the point farthest from the neutral axis in the entire bent part is not enough to cause the fracture of the silicate skeleton and form permanent deformation. Macroscopically, the glass can exhibit the characteristic of being repeatedly bent.

[0038] In the actual manufacturing process of glass, it is inevitable to form many microcracks on the surface and inside. These microcracks will further expand under the action of external forces, reducing the bending resistance, drop resistance, and impact resistance of the ultra-thin glass. The main method to solve these microcracks is through the ion exchange method. At a certain temperature, the glass containing small-radius alkali metal ions (generally sodium ions) after melting and forming is immersed in a molten salt containing large-radius alkali metal ions (such as potassium ions). Through ion diffusion, large ions are "jammed" into the glass surface layer to form a surface compressive stress layer, eliminating or suppressing the expansion of microcracks, and significantly improving the bending resistance and mechanical strength of the glass.

[0039] Since the glass treated by the ion exchange method forms a compressive stress layer (CS: compressive stress) on its surface, this compressive stress can offset the tensile stress on the outside of the glass in the bent state. When the tensile stress on the outside of the glass is less than CS when the glass is bent, the glass can be bent without being broken. After the cover plate glass is treated by the ion exchange method, the CS value on the surface is generally between 700-1000 Mpa. Assuming a bending radius of R5 mm and a glass modulus of 70 GPa, the tensile stress on the outside of the 100-μm-thick glass after bending is 700 MPa, which is less than the CS value of the glass. Therefore, in the absence of defects such as microcracks, the glass with a modulus of 70 GPa and a thickness less than 100 μm can be folded in half without fracture after being strengthened by the ion exchange method. Therefore, in the embodiment of this application, it is preferably that the thickness of the first area of the flexible cover plate 10 is 0.5 mm, and the thickness of the second area is in the range of 0.08 mm to 0.1 mm, so as to meet the need for protecting the flexible screen, and the second display area 22 of the flexible screen can perform folding operations.

[0040] It can be understood that the thinner the thickness of the flexible cover plate 10, the higher its bendability, that is, the smaller the bending radius. For example Figure 4As shown, in this embodiment, the second display area 22 of the flexible screen includes a third display area 221, a fourth display area 222, and a bendable area 223 connecting the third display area 221 and the fourth display area 222. The second area 12 of the flexible cover plate covering the second display area 22 is provided with a thinning area 121 corresponding to the bendable area 223. Thus, when the second display area 22 is folded and bent at the bendable area 223, since the thickness of the flexible cover plate at this place is relatively thin, the bendability of the second display area 22 is improved. Furthermore, the flexible cover plate 10 can not only ensure the protection of the flexible screen but also improve the bendability of the flexible screen.

[0041] When specifically forming the thinning area 121, the thickness of the flexible cover plate at the bendable area 223 can be directly thinned to form a groove structure. This groove structure extends along the bending axial direction, and the thickness of the bottom wall of this groove structure can be selected according to the thickness of the second area 12. Preferably, the thickness of the bottom wall of this groove structure is half of the thickness of the second area 12, and the cross-section of the groove structure is set to be trapezoidal or arc-shaped.

[0042] Since the thickness of the thinning area 121 is smaller than the thickness of the flexible cover plate 10 at the third display area 221 and the fourth display area 222, the thinning area 121 has higher bendability. Therefore, the thickness of the flexible cover plate 10 at the third display area 221 and the fourth display area 222 can be selected as a larger value, such as 0.1 mm, while the thickness of the bottom wall of the thinning area 121 is 0.05 mm, or the thickness of the flexible cover plate 10 at the third display area 221 and the fourth display area 222 is 0.08 mm and the thickness of the bottom wall of the thinning area 121 is 0.06 mm. Thus, it is realized that the folding and bending area of the second area 12, that is, the thinning area 121, has good bendability, and the impact resistance of other areas will also be greatly improved.

[0043] In actual production, the flexible cover plate 10 can be thinned once to form the second area 12 and the third area 13, and after the second area 12 is thinned a second time, the thinning area 121 can be formed. These two thinning operations can be realized by chemical etching process and are thinned in the same side direction. The etching difficulty is low. The opening part of the groove structure is designed to be trapezoidal or arc-shaped, and the process is relatively simple. A high yield can be ensured during the second thinning.

[0044] Such as Figure 2 and Figure 3As shown, the thickness of the third region 13 is the same as that of the second region 12, and the thickness of the first region 11 is greater than that of the third region 13 and the second region 12. Therefore, a stepped structure is formed at the adjacent position between the first region 11 and the third region 13. When the flexible cover plate 10 is covered on the surface of the flexible screen, this stepped structure is located in the bending region 23. That is to say, at the static bending region 23, a gap is formed between the flexible cover plate 10 and the flexible screen. An optical adhesive (OCA) or optical liquid adhesive (OCR) with strong cohesive force can be selected to fill this gap. Preferably, an OCR adhesive with good fluidity is used, and the filling is carried out by a dispensing or injection process to ensure that there is no gap between the flexible cover plate 10 and the flexible screen and the flexible screen will not be squeezed, achieving a good display effect.

[0045] In some embodiments, the thickness of the third region 13 gradually thins from the thickness of the first region 11 to the thickness of the second region 12, that is, the thickness continuously becomes smaller and thinner between the first region 11 and the second region 12, which can be achieved by a layer-by-layer thinning process during actual production. When the flexible cover plate 10 of this structure is attached to the flexible screen, the gap between the two can be reduced, and the third region 13 can be ensured to have a certain bendability.

[0046] As Figure 4 shown, in some embodiments, the surface 131 of the third region 13 close to the flexible screen is set as an inner concave arc corresponding to the bending region 23. This inner concave arc-shaped third region 13 can be completely attached to the bending region 23 of the flexible screen, avoiding the formation of a gap, and further improving the bending performance of the third region 13 at the same time. The slope structure of the inner concave arc can make the attachment of the third region 13 in the transition area more convenient and not easy to delaminate, and it has good impact resistance due to a certain glass thickness. At the same time, the static bending of the integrated glass does not affect the light extraction efficiency of the side display, and it can also be displayed at a large viewing angle, and there is no splicing seam, which will not cause adverse effects on viewing.

[0047] As Figure 5 shown, in some embodiments, a first coating 30 of an optically transparent organic substance is coated on the surface of the second region 12 close to the flexible screen. The first coating 30 is made of a material with a refractive index similar to that of the flexible cover plate 10 to avoid problems that affect the visual effect. Since no thinning area is provided in the second region 12, to ensure the bendability of the second region 12, the thickness of the second region 12 is set to a small value. For example, the thickness of the second region 12 is 0.08 mm. Although this structure can ensure good bendability, its impact resistance will be affected to a certain extent. Therefore, the first coating 30 is coated on the surface of the second region 12 to enhance the impact resistance of the second region 12. Preferably, the thickness of the first coating 30 is set to 0.04 mm to meet the impact resistance of the second region 12.

[0048] On one side surface of the third region 13 of the flexible cover plate 10 close to the flexible screen, a second coating layer 31 of optically transparent organic matter is coated. The second coating layer 31 is made of the same material as the first coating layer 30. The second coating layer 31 is set as a concave arc corresponding to the bending region 23. The concave arc-shaped second coating layer 31 can be completely attached to the bending region 23 of the flexible screen to avoid forming a gap.

[0049] As Figure 6 shown, in some embodiments, on one side surface of the second region 12 close to the flexible screen, a first coating layer 30 of optically transparent organic matter is coated. The first coating layer 30 is selected from materials with a refractive index similar to that of the flexible cover plate 10 to avoid problems affecting the visual effect. The second region 12 is provided with a thinning region 121. After the first coating layer 30 is coated on the second region 12, a thickening region 32 is formed at the thinning region 121 to make the surface of the first coating layer 30 flush, that is, the thinning region 121 is filled with the first coating layer 30. In this way, the mechanical properties of the thinning region 121 of the flexible folding part can be strengthened without affecting the light output efficiency, and the risk of peeling when filling the groove structure with OCA can be reduced.

[0050] The embodiment of the present application also provides a flexible display device, which includes a flexible screen and the flexible cover plate 10 described in any one of the above. The flexible screen includes a first display region 11, a second display region 12, and a bending region 23 connecting the first display region 21 and the second display region 22. Among them, the second display region 22 is set as a foldable region. The flexible cover plate 10 includes a first region 11 covering the first display region 21, a second region 12 covering the second display region 22, and a third region 13 covering the bending region 23. Among them, the thicknesses of the second region 12 and the third region 13 are less than the thickness of the first region 11, and the surfaces of the first region 11, the second region 12, and the third region 13 away from the flexible screen are flush. That is, by reducing the thickness of the flexible cover plate covering the bending region 23 and the second display region 22, the rigidity of the flexible cover plate is reduced, and the foldability at this place is improved, so that the rigidity of the first region 11 is greater than the rigidity of the second region 12 and the third region 13, and the foldability of the second region 12 and the third region 13 is greater than the foldability of the first region 11, so that the second region 12 and the third region 13 can be folded, and the flexible cover plate 10 can have a certain thickness while maintaining good impact resistance on the premise of being able to be bent.

[0051] As Figure 7 shown, the embodiment of the present application also provides a method for thinning a flexible cover plate. The flexible cover plate is made of a glass plate and includes the following steps:

[0052] S01. Divide the first region 11, the second region 12, and the third region 13 on the glass plate, and coat an acid-resistant protective layer on the surface of the first region 11.

[0053] The flexible cover plate 10 covers the surface of the flexible screen, which is used to protect the flexible screen and improve the touch feeling. Among them, the flexible screen can adopt an integral flexible display screen, including a first display area 21, a second display area 22, and a bending area 23 connecting the first display area 21 and the second display area 22. Among them, the second display area 22 is set as a foldable area. The first area 11, the second area 12, and the third area 13 on the flexible cover plate respectively cover the first display area 21, the second display area 22, and the bending area 23 of the flexible screen.

[0054] S02. Immerse the glass plate in the etching solution to etch and thin the second area 12 and the third area 13.

[0055] The etching solution is composed of hydrofluoric acid and a small amount of NH4F. The acid-resistant protective layer is a protective paint or a paraffin coating. The glass surface without the acid-resistant protective layer reacts with the etching solution, and the generated fluoride is dissolved in the etching solution or deposited on the glass surface. After rinsing, the etching and thinning of the glass are completed, so that the thicknesses of the second area 12 and the third area 13 are less than the thickness of the first area 11, realizing the foldability of the second area 12 and the third area 13.

[0056] Furthermore, the method for thinning the flexible cover plate in this embodiment further includes the following steps:

[0057] S03. Divide a thinning area 121 on the second area 12, and apply an acid-resistant protective layer on the third area 13 and the surface of the second area 12 except the thinning area 121.

[0058] S04. Immerse the glass plate in the etching solution to etch and thin the thinning area 121.

[0059] Thus, the foldable and bendable area of the second area 12, that is, the thinning area 121, has good foldability, and the impact resistance of other areas will also be greatly improved.

[0060] Furthermore, the method for thinning the flexible cover plate in this embodiment further includes the following steps:

[0061] S05. Perform strengthening treatment on the etched glass plate by the ion exchange method.

[0062] The glass after being treated by the ion exchange method can form a compressive stress layer on its surface. This compressive stress can offset the tensile stress on the outside of the glass in the bent state, thereby strengthening the glass plate and making it not easy to break when bent, further improving the foldability of the glass plate.

[0063] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to enumerate all the implementation manners here. Any obvious changes or modifications derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. A flexible cover plate for covering a flexible screen, the flexible screen comprising a first display area, a second display area, and a bending area connecting the first display area and the second display area, characterized in that, The second display area is set as a bendable area. The flexible cover plate includes a first area for covering the first display area, a second area for covering the second display area, and a third area for covering the bending area. Among them, the thickness of the second area and the third area is less than that of the first area. When the flexible screen is unfolded, the first display area, the second display area, and the bending area form a U-shaped display screen, and the bending area is a static bending area; The thickness of the third area of the flexible cover plate gradually thins from the thickness of the first area to the thickness of the second area. The surface of the third area close to the flexible screen is set as a concave arc corresponding to the bending area.

2. The flexible cover plate according to claim 1, wherein The second display area includes a third display area, a fourth display area, and a bendable area connecting the third display area and the fourth display area. A thinning area is provided at a position of the second area of the flexible cover plate corresponding to the bendable area.

3. The flexible cover plate according to claim 2, wherein, The thinning area is set as a groove structure, and the thickness of the bottom wall of the groove is half of the thickness of the second area.

4. The flexible cover plate according to claim 3, characterized in that, The cross section of the groove is trapezoidal or arc-shaped.

5. The flexible cover plate according to claim 1 or 2, characterized in that The surfaces of the second area and the third area close to the flexible screen are coated with an optically transparent organic coating. The optically transparent organic coating of the third area is set as a concave arc corresponding to the bending area.

6. The flexible cover plate according to claim 5, characterized in that The thickness of the optically transparent organic coating of the second area is 0.04 mm.

7. The flexible cover plate according to claim 1, wherein The thickness of the first area of the flexible cover plate is 0.5 mm.

8. The flexible cover plate according to claim 7, characterized in that, The thickness of the second area of the flexible cover plate ranges from 0.08 mm to 0.1 mm.

9. A flexible display device, characterized in that, It includes a flexible screen and the flexible cover plate according to any one of claims 1 to 8.

10. A thinning method for manufacturing a flexible cover plate according to any one of claims 1 to 8, characterized in that, The flexible cover plate is made of a glass plate and includes the following steps: Divide the first area, the second area, and the third area on the glass plate, and coat an acid-resistant protective layer on the surface of the first area; Immerse the glass plate in an etching solution to etch and thin the second area and the third area.

11. The flexible cover plate thinning method according to claim 10, characterized in that, It further includes the following steps: Divide the thinning area on the second area, and coat an acid-resistant protective layer on the surface of the third area and the second area except the thinning area; Immerse the glass plate in an etching solution to etch and thin the thinning area.

12. The flexible cover plate thinning method according to claim 11, wherein, It further includes the following steps: Perform strengthening treatment on the etched glass plate by an ion exchange method.

Images