Glass cover plate and preparation method thereof, flexible display screen and electronic device

Abstract

The application provides a glass cover plate and a preparation method thereof, a flexible display screen and an electronic device. The glass cover plate comprises a first planar part, a bendable part and a second planar part connected in sequence, the thickness of the bendable part is less than the thickness of the first planar part, the thickness of the bendable part is less than the thickness of the second planar part, the difference between the surface compressive stress CS1 of the first planar part and the surface compressive stress CS3 of the bendable part is in the range of CS1-CS3≤50Mpa, and the difference between the surface compressive stress CS2 of the second planar part and the surface compressive stress CS3 of the bendable part is in the range of CS2-CS3≤50Mpa. The difference between the surface compressive stress of the first planar part and the bendable part and the surface compressive stress of the second planar part and the bendable part is small, so that the distortion between the first planar part and the bendable part and the second planar part and the bendable part of the glass cover plate is small, there is no obvious light and shadow distortion phenomenon, and the appearance effect is better.

Description

Technical Field

[0001] The present application relates to the field of electronics, and in particular to a glass cover plate and a preparation method thereof, a flexible display screen and an electronic device. Background Art

[0002] With the development of flexible displays, ultra-thin glass (Ultra Flexible Glass) is widely used as a cover plate for flexible displays, used to protect and form flexible displays. To improve the mechanical strength of ultra-thin glass, ultra-thin glass is usually chemically strengthened. However, to improve the bending performance of ultra-thin glass, the bending area of ​​the ultra-thin glass is usually thinned, that is, the thickness of the bending area is smaller than the thickness of the flat areas on both sides. After chemical strengthening, due to the different surface compressive stresses in the bending area and the flat areas, the bending area will experience severe distortion after chemical strengthening, affecting the appearance and bendability of the ultra-thin glass. Summary of the Invention

[0003] To address the above-mentioned problems, an embodiment of the present application provides a glass cover plate, in which the difference in surface compressive stress between the first planar portion and the bendable portion, and between the second planar portion and the bendable portion, of the glass cover plate is relatively small. As a result, the distortion deformation between the first planar portion and the bendable portion, and between the second planar portion and the bendable portion, of the glass cover plate is relatively small, thereby eliminating obvious light and shadow distortion and providing a better appearance.

[0004] In a first aspect, an embodiment of the present application provides a glass cover, comprising: a first planar portion, a bendable portion, and a second planar portion connected in sequence, wherein the bendable portion has a thickness less than that of the first planar portion, and the bendable portion has a thickness less than that of the second planar portion. A difference between a surface compressive stress CS1 of the first planar portion and a surface compressive stress CS3 of the bendable portion is in the range of CS1-CS3≤50 MPa, and a difference between a surface compressive stress CS2 of the second planar portion and a surface compressive stress CS3 of the bendable portion is in the range of CS2-CS3≤50 MPa.

[0005] A second aspect of the present application provides a glass cover plate, comprising a first planar portion, a bendable portion, and a second planar portion connected in sequence, wherein the bendable portion has a thickness less than that of the first planar portion, and the bendable portion has a thickness less than that of the second planar portion, and the glass cover plate is obtained by chemically strengthening a glass substrate with a molten salt, wherein the molten salt comprises potassium nitrate, sodium nitrate, and lithium nitrate; and along an arrangement direction of the first planar portion, the bendable portion, and the second planar portion, before and after the chemical strengthening, a ratio of an expansion rate e3 of the bendable portion to an expansion rate e1 of the first planar portion is in a range of 1.01≤e3 / e1≤1.2, and a ratio of an expansion rate e3 of the bendable portion to an expansion rate e2 of the second planar portion is in a range of 1.01≤e3 / e2≤1.2.

[0006] A third embodiment of the present application provides a method for preparing a glass cover plate, comprising:

[0007] providing a glass substrate;

[0008] A glass substrate is placed in a molten salt for chemical strengthening to obtain the glass cover plate. The glass cover plate includes a first planar portion, a bendable portion, and a second planar portion connected in sequence. The thickness of the bendable portion is less than the thickness of the first planar portion, and the thickness of the bendable portion is less than the thickness of the second planar portion. The difference between the surface compressive stress CS1 of the first planar portion and the surface compressive stress CS3 of the bendable portion is in the range of CS1-CS3≤50MPa, and the difference between the surface compressive stress CS2 of the second planar portion and the surface compressive stress CS3 of the bendable portion is in the range of CS2-CS3≤50MPa.

[0009] A fourth embodiment of the present application provides a flexible display screen, characterized by comprising:

[0010] Display layer; and

[0011] The glass cover plate according to any one of the first aspect or the second aspect of the present application is stacked with the display layer to protect the display layer.

[0012] A fifth aspect of the present application provides an electronic device, comprising:

[0013] The flexible display screen according to the fourth aspect of the present application;

[0014] a foldable mechanism, the foldable mechanism being used to support the flexible display screen and to drive the flexible display screen to fold or flatten, wherein the glass cover plate of the flexible display screen is further away from the foldable mechanism than the display layer of the flexible display screen; and

[0015] A processor is electrically connected to the flexible display screen and is used to control the display screen to display.

[0016] The glass cover plate of the embodiment of the present application includes a first planar portion, a bendable portion, and a second planar portion connected in sequence. The thickness of the bendable portion is smaller than the thickness of the first planar portion, and the thickness of the bendable portion is smaller than the thickness of the second planar portion. The difference between the surface compressive stress of the first planar portion and the surface compressive stress of the bendable portion is within a range of 50 MPa, and the difference between the surface compressive stress of the second planar portion and the surface compressive stress of the bendable portion is within a range of 50 MPa. As a result, the difference in surface compressive stress between the first planar portion and the bendable portion, and between the second planar portion and the bendable portion of the glass cover plate is small, thereby reducing the distortion deformation between the first planar portion and the bendable portion, and between the second planar portion and the bendable portion of the glass cover plate. Therefore, there is no obvious light and shadow distortion phenomenon, and the appearance effect is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 Schematic diagram of the planar structure of a glass cover according to an embodiment of the present application.

[0019] Figure 2 The glass cover of one embodiment of the present application is Figure 1 Schematic diagram of the cross-sectional structure in the AA direction.

[0020] Figure 3 The glass cover edge of another embodiment of the present application Figure 1 Schematic diagram of the local cross-sectional structure in the AA direction.

[0021] Figure 4 1 is a flow chart of a method for preparing a glass cover according to an embodiment of the present application.

[0022] Figure 5 FIG. 1 is a schematic cross-sectional structural diagram of a glass cover according to an embodiment of the present application.

[0023] Figure 6 Schematic diagram of the structure of a flexible display screen according to an embodiment of the present application.

[0024] Figure 7 This is a structural schematic diagram of a foldable electronic device in a flattened state according to an embodiment of the present application.

[0025] Figure 8 2 is a schematic structural diagram of a foldable electronic device in a folded state according to an embodiment of the present application.

[0026] Figure 9 This is a circuit block diagram of an electronic device according to an embodiment of the present application.

[0027] Figure 10 yes Figure 8 Enlarged view of the dotted box I.

[0028] Description of reference numerals:

[0029] 100-glass cover, 10-first planar portion, 12-first compressive stress layer, 30-bendable portion, 31-first transition sub-portion, 33-equal thickness sub-portion, 35-second transition sub-portion, 32-third compressive stress layer, 50-second planar portion, 52-second compressive stress layer, 100a-glass substrate, 10a-first substrate portion, 30a-thinning portion, 50a-second substrate portion, 200-flexible display, 210-display layer, 300-foldable electronic device, 310-foldable mechanism, 311-first supporting member, 313-connecting axis, 315-second supporting member, 330-processor, 350-memory, 370-camera module. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0031] The terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish between different objects, not to describe a particular order. Furthermore, the terms "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0032] The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

[0033] It should be noted that, for the convenience of explanation, in the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments.

[0034] With the development of flexible displays, ultra-thin glass (Ultra Flexible Glass) is widely used as a cover plate for flexible displays to protect and make flexible displays. In order to make ultra-thin glass have better mechanical strength, ultra-thin glass is usually chemically strengthened. However, in order to improve the bending performance of ultra-thin glass, the bending area of ​​ultra-thin glass is usually thinned, that is, the thickness of the bending area is less than the thickness of the flat areas on both sides. After chemical strengthening, due to the difference in surface compressive stress (Compressed Stress, abbreviated CS) and expansion rate formed in the bending area and the flat area, the bending area after chemical strengthening will produce severe distortion and deformation, resulting in light and shadow distortion in the bending area (i.e., the thinned area) of the ultra-thin glass, affecting the appearance and bendability of the ultra-thin glass.

[0035] See Figure 1 and Figure 2 An embodiment of the present application provides a glass cover 100, comprising: a first planar portion 10, a bendable portion 30, and a second planar portion 50, which are connected in sequence. The bendable portion 30 has a thickness less than that of the first planar portion 10, and the bendable portion 30 has a thickness less than that of the second planar portion 50. The difference between the surface compressive stress CS1 of the first planar portion 10 and the surface compressive stress CS3 of the bendable portion 30 is in the range of CS1-CS3≤50 MPa, and the difference between the surface compressive stress CS2 of the second planar portion 50 and the surface compressive stress CS3 of the bendable portion 30 is in the range of CS2-CS3≤50 MPa.

[0036] Optionally, the glass cover 100 may be, but is not limited to, ultra-thin glass or ultra-flexible glass.

[0037] Optionally, the glass cover plate 100 may be made of, but is not limited to, high-aluminum glass. High-aluminum glass has excellent etching properties, making it easier to manufacture a glass cover plate 100 having uneven thicknesses of the first planar portion 10, the second planar portion 50, and the bendable portion 30. High-aluminum glass also has excellent bending resistance, allowing the resulting glass cover plate 100 to exhibit improved bending properties.

[0038] The glass cover plate 100 of the present application can be applied to a flexible display screen to protect and support the display layer of the flexible display screen. When the glass cover plate 100 is applied to a flexible display screen, the glass cover plate 100 is closer to the outer surface of the flexible display screen than the display layer.

[0039] It should be noted that the thicknesses of the first planar portion 10 , the bendable portion 30 and the second planar portion 50 all refer to the thicknesses perpendicular to the arrangement direction of the first planar portion 10 , the bendable portion 30 and the second planar portion 50 .

[0040] It can be understood that the thickness of the first planar portion 10 is uniform, that is, the thickness of each position of the first planar portion 10 is equal. The thickness of the second planar portion 50 is uniform, that is, the thickness of each position of the second planar portion 50 is equal.

[0041] Optionally, the bendable portion 30 has an uneven thickness (ie, unequal thickness). It is understandable that the bendable portion 30 has an uneven thickness in at least a portion of the region.

[0042] The thickness of the bendable portion 30 is smaller than the thickness of the first planar portion 10 and smaller than the thickness of the second planar portion 50 . It can be understood that the glass cover 100 has unequal thickness.

[0043] Specifically, the difference between the surface compressive stress CS1 of the first planar portion 10 and the surface compressive stress CS3 of the bendable portion 30 may be, but is not limited to, 5 MPa, 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa, 40 MPa, 45 MPa, 50 MPa, etc. The smaller the difference between the surface compressive stress CS1 of the first planar portion 10 and the surface compressive stress CS3 of the bendable portion 30, the better. When the thickness of the glass cover 100 varies greatly, it is difficult for the surface compressive stress CS1 of the first planar portion 10 and the surface compressive stress CS3 of the bendable portion 30 to be equal. If the difference between the surface compressive stress CS1 of the first planar portion 10 and the surface compressive stress CS3 of the bendable portion 30 is too large, the distortion between the first planar portion 10 and the bendable portion 30 is increased, and the light and shadow distortion phenomenon is increased, which affects the appearance of the glass cover 100.

[0044] Specifically, the difference between the surface compressive stress CS2 of the second planar portion 50 and the surface compressive stress CS3 of the bendable portion 30 may be, but is not limited to, 5 MPa, 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa, 40 MPa, 45 MPa, 50 MPa, etc. The smaller the difference between the surface compressive stress CS2 of the second planar portion 50 and the surface compressive stress CS3 of the bendable portion 30, the better. When the thickness of the glass cover 100 varies greatly, it is difficult for the surface compressive stress CS2 of the second planar portion 50 to be equal to the surface compressive stress CS3 of the bendable portion 30. If the difference between the surface compressive stress CS2 of the second planar portion 50 and the surface compressive stress CS3 of the bendable portion 30 is too large, the distortion between the second planar portion 50 and the bendable portion 30 is increased, and the light and shadow distortion phenomenon is increased, which affects the appearance of the glass cover 100.

[0045] Optionally, the range of the difference between the surface compressive stress CS1 of the first planar portion 10 and the surface compressive stress CS3 of the bendable portion 30 is: 20Mpa≤CS1-CS3≤50Mpa; the range of the difference between the surface compressive stress CS2 of the second planar portion 50 and the surface compressive stress CS3 of the bendable portion 30 is: 20Mpa≤CS2-CS3≤50Mpa.

[0046] The glass cover plate 100 of the present embodiment includes a first planar portion 10, a bendable portion 30, and a second planar portion 50 connected in sequence. The thickness of the bendable portion 30 is smaller than that of the first planar portion 10 and smaller than that of the second planar portion 50. The difference between the surface compressive stress of the first planar portion 10 and the surface compressive stress of the bendable portion 30 is within a range of 50 MPa, and the difference between the surface compressive stress of the second planar portion 50 and the surface compressive stress of the bendable portion 30 is also within a range of 50 MPa. As a result, the difference in surface compressive stress between the first planar portion 10 and the bendable portion 30, and between the second planar portion 50 and the bendable portion 30 of the glass cover plate 100 is small. As a result, the distortion deformation between the first planar portion 10 and the bendable portion 30, and between the second planar portion 50 and the bendable portion 30 of the glass cover plate 100 is small, resulting in less obvious light and shadow distortion and a better appearance.

[0047] In some embodiments, the bendable portion 30 includes a first transition sub-portion 31, a uniform thickness sub-portion 33, and a second transition sub-portion 35, which are connected in sequence. The end of the first transition sub-portion 31 facing away from the uniform thickness sub-portion 33 is connected to the first planar portion 10, and the end of the second transition sub-portion 35 facing away from the uniform thickness sub-portion 33 is connected to the second planar portion 50. The thickness of the uniform thickness portion is less than the thickness of the first planar portion 10 and less than the thickness of the second planar portion 50. The thickness of the first transition sub-portion 31 gradually decreases from the end connected to the first planar portion 10 to the end closer to the uniform thickness sub-portion 33. The thickness of the second transition sub-portion 35 gradually decreases from the end connected to the second planar portion 50 to the end closer to the uniform thickness sub-portion 33.

[0048] Optionally, the thickness d1 of the first planar portion 10 is in the range of 70 μm ≤ d1 ≤ 150 μm. Specifically, the thickness of the first planar portion 10 may be, but is not limited to, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, etc. If the thickness of the first planar portion 10 is too thin, the mechanical strength of the first planar portion 10 is reduced, and when applied to a flexible display, the support and protection function of the first planar portion 10 on the flexible display is affected; if the thickness of the first planar portion 10 is increased, it has better support and flatness. However, if the thickness of the first planar portion 10 is too thick, the flexible display is too thick, which is not conducive to the ultra-thinness of the flexible display.

[0049] Optionally, the thickness d2 of the second planar portion 50 is in the range of 70 μm ≤ d2 ≤ 150 μm. Specifically, the thickness of the second planar portion 50 may be, but is not limited to, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, etc. If the thickness of the second planar portion 50 is too thin, the mechanical strength of the second planar portion 50 is reduced, and when applied to a flexible display, the second planar portion 50's support and protection function for the flexible display is affected. Increasing the thickness of the second planar portion 50 provides better support and flatness. However, if the thickness of the second planar portion 50 is too thick, the flexible display is too thick, which is not conducive to ultra-thin flexible displays.

[0050] Optionally, the thickness d3 of the uniform thickness sub-section 33 is in the range of 20 μm ≤ d3 ≤ 50 μm. Specifically, the thickness of the uniform thickness sub-section 33 may be, but is not limited to, 20 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, etc. The thinner the uniform thickness sub-section 33, the better the bending resistance of the uniform thickness sub-section 33. However, if the uniform thickness sub-section 33 is too thin, the mechanical strength of the uniform thickness sub-section 33 will be reduced. When applied to a flexible display, the protective and supporting effect of the uniform thickness sub-section 33 on the flexible display will be reduced. If the uniform thickness sub-section 33 is too thick, the bending performance of the uniform thickness sub-section 33 will be reduced.

[0051] Optionally, the ratio d1 / d3 of the thickness d1 of the first planar portion 10 to the thickness d3 of the uniform thickness sub-portion 33 is in the range of 1.4 ≤ d1 / d3 ≤ 5. Specifically, the ratio d1 / d3 of the thickness d1 of the first planar portion 10 to the thickness d3 of the uniform thickness sub-portion 33 may be, but is not limited to, 1.4, 1.7, 2.0, 2.5, 3, 3.5, 4, 4.5, 5, etc. If the ratio d1 / d3 of the thickness d1 of the first planar portion 10 to the thickness d3 of the uniform thickness sub-portion 33 is too small, it will be difficult for the glass cover 100 to simultaneously satisfy the requirements of good bendability of the bendable portion 30 and good mechanical strength of the first planar portion 10. If the ratio d1 / d3 of the thickness d1 of the first planar portion 10 to the thickness d3 of the uniform thickness sub-portion 33 is too large, the thickness of the uniform thickness sub-portion 33 may be too thin, thereby reducing the mechanical strength of the uniform thickness sub-portion 33. When applied to a flexible display screen, the protection and support function of the flexible display screen at the position of the uniform thickness sub-portion 33 is reduced. Alternatively, the thickness d1 of the first planar portion 10 may be too thick, which is not conducive to the lightweight and thinning of the glass cover 100.

[0052] Optionally, the ratio d2 / d3 of the thickness d2 of the second planar portion 50 to the thickness d3 of the uniform thickness sub-portion 33 is in the range of 1.4≤d2 / d3≤5. Specifically, the ratio d2 / d3 of the thickness d2 of the second planar portion 50 to the thickness d3 of the uniform thickness sub-portion 33 may be, but is not limited to, 1.4, 1.7, 2.0, 2.5, 3, 3.5, 4, 4.5, 5, etc. If the ratio d2 / d3 of the thickness d2 of the second planar portion 50 to the thickness d3 of the uniform thickness sub-portion 33 is too small, it will be difficult for the glass cover 100 to simultaneously satisfy the requirements that the bendable portion 30 has good bendability and the second planar portion 50 has good mechanical strength. If the ratio d2 / d3 of the thickness d2 of the second planar portion 50 to the thickness d3 of the uniform thickness sub-portion 33 is too large, the thickness of the uniform thickness sub-portion 33 may be too thin, thereby reducing the mechanical strength of the uniform thickness sub-portion 33. When applied to a flexible display screen, the protection and support function of the flexible display screen at the position of the uniform thickness sub-portion 33 is reduced. Alternatively, the thickness d2 of the second planar portion 50 may be too thick, which is not conducive to the lightweight and thinning of the glass cover 100.

[0053] Optionally, along the arrangement direction of the first planar portion 10, the bendable portion 30, and the second planar portion 50, the width w of the bendable portion 30 is in the range of 30 mm ≤ w ≤ 45 mm. Specifically, the thickness of the bendable portion 30 may be, but is not limited to, 30 mm, 32 mm, 34 mm, 36 mm, 38 mm, 40 mm, 42 mm, 44 mm, 45 mm, etc.

[0054] Optionally, along the arrangement direction of the first planar portion 10, the bendable portion 30, and the second planar portion 50, the width w1 of the first transition sub-portion 31 is in the range of 10 mm ≤ w1 ≤ 15 mm. Specifically, the thickness of the first transition sub-portion 31 can be, but is not limited to, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, etc.

[0055] Optionally, along the arrangement direction of the first planar portion 10, the bendable portion 30, and the second planar portion 50, the width w2 of the second transition sub-portion 35 is in the range of 10 mm ≤ w2 ≤ 15 mm. Specifically, the thickness of the second transition sub-portion 35 can be, but is not limited to, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, etc.

[0056] Optionally, along the arrangement direction of the first planar portion 10, the bendable portion 30, and the second planar portion 50, the width w3 of the uniform thickness sub-portion 33 is in the range of 10 mm ≤ w3 ≤ 15 mm. Specifically, the thickness of the uniform thickness sub-portion 33 can be, but is not limited to, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, etc.

[0057] Optionally, the range of the surface compressive stress CS1 of the first planar portion 10 is: 470Mpa≤CS1≤550Mpa. Specifically, the surface compressive stress CS1 of the first planar portion 10 can be, but is not limited to, 470Mpa, 480Mpa, 490Mpa, 500Mpa, 510Mpa, 520Mpa, 530Mpa, 540Mpa, 550Mpa, etc. If the surface compressive stress CS1 of the first planar portion 10 is too low, the mechanical strength (such as impact strength) of the first planar portion 10 is greatly reduced. When applied to a flexible display screen, the protection and support function of the glass cover 100 on the flexible screen is reduced. If the surface compressive stress CS1 of the first planar portion 10 is too large, a large surface stress difference is likely to occur between the first planar portion 10 and the bendable portion 30, thereby making it easy for the glass cover 100 to have light and shadow distortion at the bendable portion 30.

[0058] Optionally, the range of the surface compressive stress CS2 of the second planar portion 50 is: 470Mpa≤CS2≤550Mpa. Specifically, the surface compressive stress CS2 of the second planar portion 50 can be, but is not limited to, 470Mpa, 480Mpa, 490Mpa, 500Mpa, 510Mpa, 520Mpa, 530Mpa, 540Mpa, 550Mpa, etc. If the surface compressive stress CS2 of the second planar portion 50 is too low, the mechanical strength (e.g., impact resistance) of the second planar portion 50 is greatly reduced. When applied to a flexible display screen, the protective and supporting function of the glass cover 100 on the flexible screen is reduced. If the surface compressive stress CS2 of the second planar portion 50 is too large, a large surface stress difference is easily generated between the second planar portion 50 and the bendable portion 30, thereby causing the glass cover 100 to be prone to light and shadow distortion at the bendable portion 30.

[0059] Optionally, the range of the surface compressive stress CS3 of the bendable portion 30 is: 450Mpa≤CS3≤530Mpa. Specifically, the surface compressive stress CS3 of the bendable portion 30 may be, but is not limited to, 450Mpa, 460Mpa, 470Mpa, 480Mpa, 490Mpa, 500Mpa, 510Mpa, 520Mpa, 530Mpa, etc. If the surface compressive stress CS3 of the bendable portion 30 is too low, the mechanical strength (e.g., impact resistance) of the bendable portion 30 is greatly reduced. When applied to a flexible display screen, the protective and supporting effect of the glass cover 100 on the flexible screen is reduced. If the surface compressive stress CS3 of the bendable portion 30 is too high, the bending performance of the bendable portion 30 is reduced.

[0060] Optionally, the glass cover plate 100 is a glass cover plate 100 obtained by chemically strengthening a glass substrate with molten salt, and the molten salt includes potassium nitrate, sodium nitrate, and lithium nitrate.

[0061] Chemical strengthening refers to forming a compressive stress layer on the surface of the glass substrate through ion exchange. When the glass cover plate 100 is subjected to external force, this compressive stress layer can offset the tensile stress at the end of the crack or defect, preventing the crack of the glass cover plate 100 from further spreading, thereby achieving the purpose of improving the strength of the glass cover plate 100.

[0062] When the glass substrate is chemically strengthened using the molten salt of this embodiment, the potassium ions (K + ) the sodium ions (Na + ) are replaced by potassium ions, which have a larger radius. Due to the compression of potassium ions on the surface of the glass substrate, a compressive stress layer is formed on the surface of the glass substrate, thereby improving the mechanical strength of the glass cover plate 100. Furthermore, after chemical strengthening, the concentration of potassium ions in the glass cover plate 100 gradually decreases from the surface toward the center of the glass, forming a particle concentration difference. This particle concentration difference creates a compressive stress curve that gradually decreases from the surface to the inside.

[0063] The glass cover 100 for the flexible display screen is usually made of high-aluminum glass, which usually does not have lithium ions (Li + When lithium nitrate is added to the molten salt, lithium ions will enter the glass substrate and replace the sodium ions in the glass substrate. Lithium ions have a smaller radius than sodium ions, thereby achieving negative expansion of the glass substrate and reducing the overall expansion rate of the glass cover plate 100, especially in the direction perpendicular to the thickness (such as Figure 1 The expansion rate in the X direction and the Y direction) can better reduce the expansion rate difference between the first planar portion 10 or the second planar portion 50 and the bendable portion 30, and can better improve the light and shadow distortion phenomenon of the glass cover 100.

[0064] Adding sodium nitrate to the molten salt can reduce the exchange rate of potassium ions and sodium ions, thereby reducing the surface stress difference and expansion rate difference between the first plane portion 10 or the second plane portion 50 and the bendable portion 30, thereby better avoiding the light and shadow distortion phenomenon caused by the bendable portion 30. In addition, sodium ions can also inhibit the lithium ions (Li + ) replaces the sodium ions in the glass substrate, limiting the amount of lithium ions entering the glass substrate, thereby preventing the mechanical strength of the manufactured glass cover 100 from being too low.

[0065] In the embodiment of the present application, when there is a significant difference in thickness between the first planar portion 10 and the second planar portion 50 and the bendable portion 30, the formulation of the molten salt is adjusted so that the surface compressive stress differences between the first planar portion 10 and the bendable portion 30, and between the second planar portion 50 and the bendable portion 30, are all below 50 MPa, and the ratio of the expansion rate in the width or length direction between the bendable portion 30 and the first planar portion 10, and between the bendable portion 30 and the second planar portion 50 is less than 1.2, thereby avoiding distortion and light and shadow distortion caused by chemically strengthened glass cover 100.

[0066] Optionally, in the molten salt, the ratio of the mass fraction w1 of the potassium nitrate to the mass fraction w2 of the sodium nitrate is in the range of 19≤w1 / w2≤49. Specifically, the ratio of the mass fraction w1 of potassium nitrate to the mass fraction w2 of sodium nitrate can be, but is not limited to, 19, 20, 22, 25, 28, 30, 32, 35, 38, 40, 43, 45, 47, 49, etc. The ratio of the mass fraction w1 of potassium nitrate to the mass fraction w2 of sodium nitrate is too small, indicating that the content of potassium nitrate in the molten salt is too little and the content of sodium nitrate is too much, which will excessively reduce the exchange rate of potassium ions and sodium ions, thereby making the mechanical strength of the obtained glass cover plate 100 too low. When applied to a flexible display screen, it cannot provide sufficient support and protection, and the drop resistance is also greatly reduced; the ratio of the mass fraction w1 of potassium nitrate to the mass fraction w2 of sodium nitrate is too large, indicating that the content of potassium nitrate in the molten salt is too much and the content of sodium nitrate is too little, then the compressive stress of the obtained glass cover plate 100 at a distance of 3 μm to 7 μm from the surface of the glass cover plate 100 along the thickness direction will drop sharply, thereby making the protective effect of the compressive stress layer on microcracks worse, making it difficult to prevent the spread of microcracks. When microcracks exist in the glass cover plate 100, the mechanical properties of the glass cover plate 100 are greatly reduced.

[0067] In the embodiments of the present application, when a numerical value range from a to b is involved, unless otherwise specified, it means that the numerical value can be any numerical value between a and b, including the endpoint numerical value a and the endpoint numerical value b.

[0068] Optionally, the ratio of the mass fraction w2 of the sodium nitrate to the mass fraction w3 of the lithium nitrate is in the range of 4≤w2 / w3≤25. Specifically, the ratio of the mass fraction w2 of the sodium nitrate to the mass fraction w3 of the lithium nitrate can be, but is not limited to, 4, 5, 8, 10, 12, 14, 16, 18, 20, 22, 24, 25, etc. If the ratio of the mass fraction w2 of sodium nitrate to the mass fraction w3 of lithium nitrate is too large, the amount of lithium ions entering the glass substrate will be excessively suppressed, thereby increasing the expansion rate of the glass cover plate 100 in a direction perpendicular to the thickness (such as the X direction or the Y direction) and increasing the difference in expansion rate between the first planar portion 10 or the second planar portion 50 and the bendable portion 30, causing the light and shadow distortion phenomenon of the glass cover plate 100 to be more severe. If the ratio of the mass fraction w2 of sodium nitrate to the mass fraction w3 of lithium nitrate is too small, the sodium ions will have too little effect on suppressing the entry of lithium ions into the glass substrate, resulting in an excessive lithium ion content in the glass substrate and reduced mechanical strength. In addition, if the sodium nitrate content is too low, the compressive stress of the manufactured glass cover plate 100 will drop sharply at a distance of 3 μm to 7 μm from the surface of the glass cover plate 100 in the thickness direction, thereby weakening the compressive stress layer's protective effect against microcracks and making it difficult to prevent the microcracks from propagating. When microcracks exist in the glass cover plate 100, the mechanical properties of the glass cover plate 100 are greatly reduced.

[0069] Optionally, the molten salt comprises, by mass fraction, 94.5% to 97.8% of potassium nitrate, 2% to 5% of sodium nitrate, and 0.2% to 0.5% of lithium nitrate.

[0070] Specifically, the mass fraction of potassium nitrate in the molten salt may be, but is not limited to, 94.5%, 95%, 95.5%, 96%, 96.5%, 97%, 97.4%, 97.8%, etc. The mass fraction of sodium nitrate may be, but is not limited to, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc. The mass fraction of lithium nitrate may be, but is not limited to, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, etc.

[0071] See Figure 3 In some embodiments, the first planar portion 10 includes a first compressive stress layer 12 , the second planar portion 50 includes a second compressive stress layer 52 , and the bendable portion 30 includes a third compressive stress layer 32 .

[0072] It should be noted that the first planar portion 10 includes at least two first compressive stress layers 12, which are located at opposite ends of the first planar portion 10 along the thickness direction. The second planar portion 50 includes at least two second compressive stress layers 52, which are located at opposite ends of the second planar portion 50 along the thickness direction. The bendable portion 30 includes at least two third compressive stress layers 32, which are located at opposite ends of the bendable portion 30 along the thickness direction.

[0073] It can be understood that the first compressive stress layer 12, the second compressive stress layer 52, and the third compressive stress layer 32 are all formed by replacing smaller-radius ions in the glass substrate with larger-radius ions in the molten salt. For example, sodium ions in the glass substrate are replaced by potassium ions in the molten salt. The thickness of the first compressive stress layer 12, the second compressive stress layer 52, and the third compressive stress layer 32 is determined by the penetration depth of the ions (e.g., potassium ions) in the molten salt into the glass substrate.

[0074] Optionally, a difference between the thickness DOL1 of the first compressive stress layer 12 and the thickness DOL3 of the third compressive stress layer 32 is in the range of: 0.1 μm ≤ DOL1 - DOL3 ≤ 0.3 μm. Specifically, the difference between the thickness DOL1 of the first compressive stress layer 12 and the thickness DOL3 of the third compressive stress layer 32 may be, but is not limited to, 0.1 μm, 0.13 μm, 0.15 μm, 0.18 μm, 0.2 μm, 0.23 μm, 0.25 μm, 0.28 μm, 0.3 μm, etc. If the difference between the thickness DOL1 of the first compressive stress layer 12 and the thickness of the third compressive stress layer 32 is too great, the surface compressive stress difference between the first planar portion 10 and the bendable portion 30 will be too great, increasing the light and shadow distortion phenomenon of the bendable portion 30. If the difference between the thickness DOL1 of the first compressive stress layer 12 and the thickness of the third compressive stress layer 32 is too small, it will be difficult to achieve in terms of technology, or only a glass cover plate 100 with a first planar portion 10 and a bendable portion 30 of similar thickness can be used, which will affect the bending performance of the glass cover plate 100.

[0075] Optionally, a difference between the thickness DOL2 of the second compressive stress layer 52 and the thickness DOL3 of the third compressive stress layer 32 is in the range of: 0.1 μm ≤ DOL2 - DOL3 ≤ 0.3 μm. Specifically, the difference between the thickness DOL2 of the second compressive stress layer 52 and the thickness DOL3 of the third compressive stress layer 32 may be, but is not limited to, 0.1 μm, 0.13 μm, 0.15 μm, 0.18 μm, 0.2 μm, 0.23 μm, 0.25 μm, 0.28 μm, 0.3 μm, etc. If the difference between the thickness DOL2 of the second compressive stress layer 52 and the thickness of the third compressive stress layer 32 is too great, the surface compressive stress difference between the second planar portion 50 and the bendable portion 30 will be too great, increasing the light and shadow distortion phenomenon of the bendable portion 30. If the difference between the thickness DOL2 of the second compressive stress layer 52 and the thickness of the third compressive stress layer 32 is too small, it will be difficult to achieve in terms of technology, or only a glass cover plate 100 with a second planar portion 50 and a bendable portion 30 of similar thickness can be used, which will affect the bending performance of the glass cover plate 100.

[0076] Optionally, the thickness DOL1 of the first compressive stress layer 12 is in the range of 5μm≤DOL1≤7μm. Specifically, the thickness DOL1 of the first compressive stress layer 12 can be, but is not limited to, 5μm, 5.3μm, 5.5μm, 5.8μm, 6μm, 6.2μm, 6.5μm, 6.8μm, 7μm, etc. If the first compressive stress layer 12 is too thin, the mechanical strength (such as impact strength) of the first planar portion 10 is reduced. When applied to a flexible display screen, the protective and supporting effect of the glass cover 100 on the flexible screen is reduced. If the first compressive stress layer 12 is too thick, the surface compressive stress of the first planar portion 10 is too large, which easily causes a large surface stress difference between the first planar portion 10 and the bendable portion 30, thereby causing the glass cover 100 to be prone to light and shadow distortion at the bendable portion 30.

[0077] Optionally, the thickness DOL2 of the second compressive stress layer 52 is in the range of 5μm≤DOL2≤7μm. Specifically, the thickness DOL2 of the second compressive stress layer 52 can be, but is not limited to, 5μm, 5.3μm, 5.5μm, 5.8μm, 6μm, 6.2μm, 6.5μm, 6.8μm, 7μm, etc. If the second compressive stress layer 52 is too thin, the mechanical strength (such as impact strength) of the second planar portion 50 is reduced. When applied to a flexible display screen, the protection and support function of the glass cover 100 on the flexible screen is reduced. If the second compressive stress layer 52 is too thick, the surface compressive stress of the second planar portion 50 is too large, which easily causes a large surface stress difference between the second planar portion 50 and the bendable portion 30, thereby causing the glass cover 100 to be prone to light and shadow distortion at the bendable portion 30.

[0078] Optionally, the thickness DOL3 of the third compressive stress layer 32 is in the range of 5μm≤DOL3≤7μm. Specifically, the thickness DOL3 of the third compressive stress layer 32 may be, but is not limited to, 5μm, 5.3μm, 5.5μm, 5.8μm, 6μm, 6.2μm, 6.5μm, 6.8μm, 7μm, etc. If the third compressive stress layer 32 of the bendable portion 30 is too thin, the mechanical strength (e.g., impact resistance) of the bendable portion 30 is greatly reduced. When applied to a flexible display screen, the protective and supporting effect of the glass cover 100 on the flexible screen is reduced. If the third compressive stress layer 32 of the bendable portion 30 is too thick, the bending performance of the bendable portion 30 is reduced.

[0079] Optionally, along the arrangement direction of the first planar portion 10, the bendable portion 30, and the second planar portion 50, before and after chemical strengthening, the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e1 of the first planar portion 10 is in the range of 1.01 ≤ e3 / e1 ≤ 1.2. In other words, along the direction perpendicular to the thickness of the glass cover 100, before and after chemical strengthening, the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e1 of the first planar portion 10 is in the range of 1.01 ≤ e3 / e1 ≤ 1.2.

[0080] Specifically, along the arrangement direction of the first planar portion 10, the bendable portion 30 and the second planar portion 50, before and after the chemical strengthening, the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e1 of the first planar portion 10 can be, but is not limited to, 1.01, 1.02, 1.05, 1.08, 1.1, 1.12, 1.15, 1.18, 1.2, etc. The smaller the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e1 of the first planar portion 10, the weaker the light and shadow distortion phenomenon of the glass cover plate 100. However, if the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e1 of the first planar portion 10 is too small, it is difficult to achieve in terms of technology, or it can only be achieved by reducing the thickness difference between the first planar portion 10 and the bendable portion 30. In this way, it is difficult to ensure that the glass cover plate 100 simultaneously meets the requirements of the bendable portion 30 having good bending performance and the first planar portion 10 having good protection and support performance. If the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e1 of the first planar portion 10 is too large, the connection between the bendable portion 30 and the first planar portion 10 is severely distorted, and the light and shadow distortion phenomenon is severe.

[0081] It can be understood that along the arrangement direction of the first planar portion 10, the bendable portion 30, and the second planar portion 50, the expansion rate e1 of the first planar portion 10 is equal to the ratio of the length L of the first planar portion 10 after chemical strengthening to the length L0 of the first planar portion 10 before chemical strengthening, that is, e1 = L / L0. The expansion rate of the second planar portion 50 and the bendable portion 30 is calculated in the same manner as that of the first planar portion 10 and will not be further described here.

[0082] Optionally, along the arrangement direction of the first planar portion 10, the bendable portion 30, and the second planar portion 50, the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e2 of the second planar portion 50 is in the range of 1.01 ≤ e3 / e2 ≤ 1.2. In other words, along the direction perpendicular to the thickness of the glass cover 100, the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e2 of the second planar portion 50 is in the range of 1.01 ≤ e3 / e2 ≤ 1.2.

[0083] Specifically, along the arrangement direction of the first planar portion 10, the bendable portion 30 and the second planar portion 50, the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e2 of the second planar portion 50 can be but is not limited to 1.01, 1.02, 1.05, 1.08, 1.1, 1.12, 1.15, 1.18, 1.2, etc. The smaller the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e2 of the second planar portion 50, the weaker the light and shadow distortion phenomenon of the glass cover plate 100. However, if the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e2 of the second planar portion 50 is too small, it is difficult to achieve in terms of technology, or it can only be achieved by reducing the thickness difference between the second planar portion 50 and the bendable portion 30. In this way, it is difficult to ensure that the glass cover plate 100 simultaneously meets the requirements of the bendable portion 30 having good bending performance and the second planar portion 50 having good protection and support performance. If the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e2 of the second planar portion 50 is too large, the connection between the bendable portion 30 and the second planar portion 50 is severely distorted, and the light and shadow distortion phenomenon is severe.

[0084] Optionally, the range of the difference between the expansion rate e3 of the bendable portion 30 and the expansion rate e1 of the first planar portion 10 is: (percent or ten thousandth sign)≤e3-e1≤ Specifically, the difference between the expansion rate e3 of the bendable portion 30 and the expansion rate e1 of the first planar portion 10 can be, but is not limited to, The smaller the difference between the expansion rate e3 of the bendable portion 30 and the expansion rate e1 of the first planar portion 10, the weaker the light and shadow distortion phenomenon of the glass cover 100. However, if the difference between the expansion rate e1 of the first planar portion 10 and the expansion rate e3 of the bendable portion 30 is too small, it is difficult to achieve in terms of technology, or it can only be achieved by reducing the thickness difference between the first planar portion 10 and the bendable portion 30. In this way, it is difficult to ensure that the glass cover 100 simultaneously meets the requirements of the bendable portion 30 having good bending performance while the first planar portion 10 has good protection and support performance. If the difference between the expansion rate e1 of the first planar portion 10 and the expansion rate e3 of the bendable portion 30 is too large, the connection between the bendable portion 30 and the first planar portion 10 is severely distorted, and the light and shadow distortion phenomenon is severe.

[0085] Optionally, the range of the difference between the expansion rate e3 of the bendable portion 30 and the expansion rate e2 of the second planar portion 50 is: Specifically, the difference between the expansion rate e3 of the bendable portion 30 and the expansion rate e2 of the second planar portion 50 can be, but is not limited to, The smaller the difference between the expansion rate e3 of the bendable portion 30 and the expansion rate e2 of the second planar portion 50, the weaker the light and shadow distortion phenomenon of the glass cover 100. However, if the difference between the expansion rate e2 of the second planar portion 50 and the expansion rate e3 of the bendable portion 30 is too small, it is difficult to achieve in terms of technology, or it can only be achieved by reducing the thickness difference between the second planar portion 50 and the bendable portion 30. In this way, it is difficult to ensure that the glass cover 100 simultaneously meets the requirements of the bendable portion 30 having good bending performance while the second planar portion 50 has good protection and support performance. If the difference between the expansion rate e2 of the second planar portion 50 and the expansion rate e3 of the bendable portion 30 is too large, the connection between the bendable portion 30 and the second planar portion 50 will be severely distorted, and the light and shadow distortion phenomenon will be serious.

[0086] Optionally, the expansion rate e1 of the first planar portion 10 is in the range of Specifically, the expansion rate e1 of the first planar portion 10 may be, but is not limited to, If the expansion rate of the first planar portion 10 is too low, the difference in expansion rate between it and the bendable portion 30 is too large, which can easily cause severe distortion and deformation at the connection between the first planar portion 10 and the bendable portion 30, resulting in severe light and shadow distortion. If the expansion rate of the first planar portion 10 is too high, it means that the chemical strengthening depth is deep. Because the first planar portion 10 and the bendable portion 30 are strengthened in the same system during chemical strengthening, the strengthening depth of the bendable portion 30 is also deepened, resulting in a larger expansion rate of the bendable portion 30, further widening the difference in expansion rate between the bendable portion 30 and the first planar portion 10. This will also cause severe distortion and deformation at the connection between the first planar portion 10 and the bendable portion 30, resulting in severe light and shadow distortion.

[0087] Optionally, the expansion rate e2 of the second planar portion 50 is in the range of Specifically, the expansion rate e2 of the second planar portion 50 may be, but is not limited to, If the expansion rate of the second planar portion 50 is too low, the difference in expansion rate between it and the bendable portion 30 is too large, which can easily cause severe distortion and deformation at the connection between the second planar portion 50 and the bendable portion 30, resulting in severe light and shadow distortion. If the expansion rate of the second planar portion 50 is too high, it means that the chemical strengthening depth is deep. Because the second planar portion 50 and the bendable portion 30 are strengthened in the same system during chemical strengthening, the strengthening depth of the bendable portion 30 is also deepened, resulting in a larger expansion rate of the bendable portion 30, further widening the difference in expansion rate between the bendable portion 30 and the second planar portion 50. This will also cause severe distortion and deformation at the connection between the second planar portion 50 and the bendable portion 30, resulting in severe light and shadow distortion.

[0088] Optionally, the expansion rate e3 of the bendable portion 30 is in the range of Specifically, the expansion rate e3 of the bendable portion 30 may be, but is not limited to, If the expansion rate e3 of the bendable portion 30 is too low, the thickness of the bendable portion 30 needs to be increased to reduce the thickness difference between the bendable portion 30 and the first planar portion 10 and the second planar portion 50. Alternatively, the reinforcement depth of the first planar portion 10 and the second planar portion 50 may be insufficient, reducing the mechanical strength of the first planar portion 10 and the second planar portion 50. If the expansion rate e3 of the bendable portion 30 is too high, the expansion rate difference between the first planar portion 10 and the second planar portion 50 and the bendable portion 30 is increased, exacerbating the light and shadow distortion between the first planar portion 10 and the second planar portion 50 and the bendable portion 30.

[0089] Please see again Figure 1 and Figure 2 The present application also provides a glass cover plate 100, comprising a first planar portion 10, a bendable portion 30, and a second planar portion 50 connected in sequence. The bendable portion 30 is thinner than the first planar portion 10, and thinner than the second planar portion 50. The glass cover plate 100 is formed by chemically strengthening a glass substrate with a molten salt, wherein the molten salt comprises potassium nitrate, sodium nitrate, and lithium nitrate. Before and after the chemical strengthening, along the arrangement direction of the first planar portion 10, the bendable portion 30, and the second planar portion 50, a ratio of an expansion coefficient e3 of the bendable portion 30 to an expansion coefficient e1 of the first planar portion 10 is within a range of 1.01≤e3 / e1≤1.2, and a ratio of an expansion coefficient e3 of the bendable portion 30 to an expansion coefficient e2 of the second planar portion 50 is within a range of 1.01≤e3 / e2≤1.2.

[0090] Specifically, along the arrangement direction of the first planar portion 10, the bendable portion 30 and the second planar portion 50, before and after the chemical strengthening, the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e1 of the first planar portion 10 can be, but is not limited to, 1.01, 1.02, 1.05, 1.08, 1.1, 1.12, 1.15, 1.18, 1.2, etc. The smaller the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e1 of the first planar portion 10, the weaker the light and shadow distortion phenomenon of the glass cover plate 100. However, if the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e1 of the first planar portion 10 is too small, it is difficult to achieve in terms of technology, or it can only be achieved by reducing the thickness difference between the first planar portion 10 and the bendable portion 30. In this way, it is difficult to ensure that the glass cover plate 100 simultaneously meets the requirements of the bendable portion 30 having good bending performance and the first planar portion 10 having good protection and support performance. If the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e1 of the first planar portion 10 is too large, the connection between the bendable portion 30 and the first planar portion 10 is severely distorted, and the light and shadow distortion phenomenon is severe.

[0091] Specifically, along the arrangement direction of the first planar portion 10, the bendable portion 30 and the second planar portion 50, the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e2 of the second planar portion 50 can be but is not limited to 1.01, 1.02, 1.05, 1.08, 1.1, 1.12, 1.15, 1.18, 1.2, etc. The smaller the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e2 of the second planar portion 50, the weaker the light and shadow distortion phenomenon of the glass cover plate 100. However, if the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e2 of the second planar portion 50 is too small, it is difficult to achieve in terms of technology, or it can only be achieved by reducing the thickness difference between the second planar portion 50 and the bendable portion 30. In this way, it is difficult to ensure that the glass cover plate 100 simultaneously meets the requirements of the bendable portion 30 having good bending performance and the second planar portion 50 having good protection and support performance. If the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e2 of the second planar portion 50 is too large, the connection between the bendable portion 30 and the second planar portion 50 is severely distorted, and the light and shadow distortion phenomenon is severe.

[0092] When the glass substrate is chemically strengthened using the molten salt of this embodiment, the potassium ions (K + ) the sodium ions (Na +) are replaced, potassium ions have a larger radius, and the surface of the glass substrate is squeezed by potassium ions, thereby forming a compressive stress layer on the surface of the glass substrate, thereby improving the mechanical strength of the glass cover 100. In addition, after chemical strengthening, the concentration of potassium ions in the glass cover 100 gradually decreases from the surface of the glass cover 100 to the center of the glass, forming a particle concentration difference, and the particle concentration difference forms a compressive stress curve that gradually decreases from the surface to the inside. The glass cover 100 for flexible display screens usually uses high aluminum glass, which usually does not have lithium ions (Li + ). When lithium nitrate is added to the molten salt, lithium ions will enter the glass substrate and reversely replace the sodium ions in the glass substrate. Lithium ions have a smaller radius than sodium ions, so that negative expansion of the glass substrate can be achieved, reducing the overall expansion rate of the glass cover 100, especially the expansion rate of the glass cover 100 perpendicular to the thickness direction (such as the X direction or the Y direction), which can better reduce the expansion rate difference between the first plane portion 10 or the second plane portion 50 and the bendable portion 30, and can better improve the light and shadow distortion phenomenon of the glass cover 100. Adding sodium nitrate to the molten salt can reduce the exchange rate of potassium ions and sodium ions, thereby reducing the surface stress difference and expansion rate difference between the formed first plane portion 10 or the second plane portion 50 and the bendable portion 30, thereby better avoiding the light and shadow distortion phenomenon generated by the bendable portion 30. In addition, sodium ions can also inhibit the lithium ions (Li + ) replaces the sodium ions in the glass substrate, limiting the amount of lithium ions entering the glass substrate, thereby preventing the mechanical strength of the manufactured glass cover 100 from being too low.

[0093] The glass cover plate 100 of the embodiment of the present application includes a first planar portion 10, a bendable portion 30, and a second planar portion 50 connected in sequence. The bendable portion 30 is thinner than the first planar portion 10 and thinner than the second planar portion 50. The glass cover plate 100 is formed by chemically strengthening a glass substrate with molten salt. Before and after chemical strengthening, the ratio of the expansion coefficient e3 of the bendable portion 30 to the expansion coefficient e1 of the first planar portion 10 is in the range of 1.01≤e3 / e1≤1.2, and the ratio of the expansion coefficient e3 of the bendable portion 30 to the expansion coefficient e2 of the second planar portion 50 is in the range of 1.01≤e3 / e2≤1.2. This indicates that the difference in expansion rate between the first planar portion 10 and the bendable portion 30, and between the second planar portion 50 and the bendable portion 30, before and after chemical strengthening is controlled within a range of 20%. This small difference in expansion rate results in minimal distortion between the first planar portion 10 and the bendable portion 30, and between the second planar portion 50 and the bendable portion 30 of the glass cover 100. Consequently, there is no obvious light and shadow distortion, resulting in a better appearance.

[0094] Optionally, the range of the difference between the expansion rate e3 of the bendable portion 30 and the expansion rate e1 of the first planar portion 10 is: The difference between the expansion rate e3 of the bendable portion 30 and the expansion rate e2 of the second planar portion 50 is in the range of:

[0095] Specifically, the difference between the expansion rate e3 of the bendable portion 30 and the expansion rate e1 of the first planar portion 10 can be, but is not limited to, The smaller the difference between the expansion rate e3 of the bendable portion 30 and the expansion rate e1 of the first planar portion 10, the weaker the light and shadow distortion phenomenon of the glass cover 100. However, if the difference between the expansion rate e1 of the first planar portion 10 and the expansion rate e3 of the bendable portion 30 is too small, it is difficult to achieve in terms of technology, or it can only be achieved by reducing the thickness difference between the first planar portion 10 and the bendable portion 30. In this way, it is difficult to ensure that the glass cover 100 simultaneously meets the requirements of the bendable portion 30 having good bending performance while the first planar portion 10 has good protection and support performance. If the difference between the expansion rate e1 of the first planar portion 10 and the expansion rate e3 of the bendable portion 30 is too large, the connection between the bendable portion 30 and the first planar portion 10 is severely distorted, and the light and shadow distortion phenomenon is severe.

[0096] Specifically, the difference between the expansion rate e3 of the bendable portion 30 and the expansion rate e2 of the second planar portion 50 can be, but is not limited to, The smaller the difference between the expansion rate e3 of the bendable portion 30 and the expansion rate e2 of the second planar portion 50, the weaker the light and shadow distortion phenomenon of the glass cover 100. However, if the difference between the expansion rate e2 of the second planar portion 50 and the expansion rate e3 of the bendable portion 30 is too small, it is difficult to achieve in terms of technology, or it can only be achieved by reducing the thickness difference between the second planar portion 50 and the bendable portion 30. In this way, it is difficult to ensure that the glass cover 100 simultaneously meets the requirements of the bendable portion 30 having good bending performance while the second planar portion 50 has good protection and support performance. If the difference between the expansion rate e2 of the second planar portion 50 and the expansion rate e3 of the bendable portion 30 is too large, the connection between the bendable portion 30 and the second planar portion 50 will be severely distorted, and the light and shadow distortion phenomenon will be serious.

[0097] Optionally, the expansion rate e1 of the first planar portion 10 is in the range of Specifically, the expansion rate e1 of the first planar portion 10 may be, but is not limited to, If the expansion rate of the first planar portion 10 is too low, the difference in expansion rate between it and the bendable portion 30 is too large, which can easily cause severe distortion and deformation at the connection between the first planar portion 10 and the bendable portion 30, resulting in severe light and shadow distortion. If the expansion rate of the first planar portion 10 is too high, it means that the chemical strengthening depth is deep. Because the first planar portion 10 and the bendable portion 30 are strengthened in the same system during chemical strengthening, the strengthening depth of the bendable portion 30 is also deepened, resulting in a larger expansion rate of the bendable portion 30, further widening the difference in expansion rate between the bendable portion 30 and the first planar portion 10. This will also cause severe distortion and deformation at the connection between the first planar portion 10 and the bendable portion 30, resulting in severe light and shadow distortion.

[0098] Optionally, the expansion rate e2 of the second planar portion 50 is in the range of Specifically, the expansion rate e2 of the second planar portion 50 may be, but is not limited to, If the expansion rate of the second planar portion 50 is too low, the difference in expansion rate between it and the bendable portion 30 is too large, which can easily cause severe distortion and deformation at the connection between the second planar portion 50 and the bendable portion 30, resulting in severe light and shadow distortion. If the expansion rate of the second planar portion 50 is too high, it means that the chemical strengthening depth is deep. Because the second planar portion 50 and the bendable portion 30 are strengthened in the same system during chemical strengthening, the strengthening depth of the bendable portion 30 is also deepened, resulting in a larger expansion rate of the bendable portion 30, further widening the difference in expansion rate between the bendable portion 30 and the second planar portion 50. This will also cause severe distortion and deformation at the connection between the second planar portion 50 and the bendable portion 30, resulting in severe light and shadow distortion.

[0099] Optionally, the expansion rate e3 of the bendable portion 30 is in the range of Specifically, the expansion rate e3 of the bendable portion 30 may be, but is not limited to, If the expansion rate e3 of the bendable portion 30 is too low, the thickness of the bendable portion 30 needs to be increased to reduce the thickness difference between the bendable portion 30 and the first planar portion 10 and the second planar portion 50. Alternatively, the reinforcement depth of the first planar portion 10 and the second planar portion 50 may be insufficient, reducing the mechanical strength of the first planar portion 10 and the second planar portion 50. If the expansion rate e3 of the bendable portion 30 is too high, the expansion rate difference between the first planar portion 10 and the second planar portion 50 and the bendable portion 30 is increased, exacerbating the light and shadow distortion between the first planar portion 10 and the second planar portion 50 and the bendable portion 30.

[0100] Optionally, in the molten salt, the ratio of the mass fraction w1 of the potassium nitrate to the mass fraction w2 of the sodium nitrate is in the range of 19≤w1 / w2≤49; the ratio of the mass fraction w2 of the sodium nitrate to the mass fraction w3 of the lithium nitrate is in the range of 4≤w2 / w3≤25.

[0101] Specifically, the ratio of the mass fraction w1 of potassium nitrate to the mass fraction w2 of sodium nitrate can be, but is not limited to, 19, 20, 22, 25, 28, 30, 32, 35, 38, 40, 43, 45, 47, 49, etc. The ratio of the mass fraction w1 of potassium nitrate to the mass fraction w2 of sodium nitrate is too small, indicating that the content of potassium nitrate in the molten salt is too little and the content of sodium nitrate is too much, which will excessively reduce the exchange rate of potassium ions and sodium ions, thereby making the mechanical strength of the obtained glass cover plate 100 too low. When applied to a flexible display screen, it cannot provide sufficient support and protection, and the drop resistance is also greatly reduced; the ratio of the mass fraction w1 of potassium nitrate to the mass fraction w2 of sodium nitrate is too large, indicating that the content of potassium nitrate in the molten salt is too much and the content of sodium nitrate is too little, then the compressive stress of the obtained glass cover plate 100 at a distance of 3 μm to 7 μm from the surface of the glass cover plate 100 along the thickness direction will drop sharply, thereby making the protective effect of the compressive stress layer on microcracks worse, making it difficult to prevent the spread of microcracks. When microcracks exist in the glass cover plate 100, the mechanical properties of the glass cover plate 100 are greatly reduced.

[0102] Specifically, the ratio of the mass fraction w2 of the sodium nitrate to the mass fraction w3 of the lithium nitrate can be, but is not limited to, 4, 5, 8, 10, 12, 14, 16, 18, 20, 22, 24, 25, etc. If the ratio of the mass fraction w2 of sodium nitrate to the mass fraction w3 of lithium nitrate is too large, the amount of lithium ions entering the glass substrate will be excessively suppressed, thereby increasing the expansion rate of the glass cover plate 100 in a direction perpendicular to the thickness (such as the X direction or the Y direction) and increasing the difference in expansion rate between the first planar portion 10 or the second planar portion 50 and the bendable portion 30, causing the light and shadow distortion phenomenon of the glass cover plate 100 to be more severe. If the ratio of the mass fraction w2 of sodium nitrate to the mass fraction w3 of lithium nitrate is too small, the sodium ions will have too little effect on suppressing the entry of lithium ions into the glass substrate, resulting in an excessive lithium ion content in the glass substrate and reduced mechanical strength. In addition, if the sodium nitrate content is too low, the compressive stress of the manufactured glass cover plate 100 will drop sharply at a distance of 3 μm to 7 μm from the surface of the glass cover plate 100 along the thickness direction, thereby weakening the compressive stress layer's protective effect on microcracks and making it difficult to prevent the microcracks from propagating. When microcracks exist in the glass cover plate 100, the mechanical properties of the glass cover plate 100 are greatly reduced.

[0103] Optionally, the molten salt comprises, by mass fraction, 94.5% to 97.8% of potassium nitrate, 2% to 5% of sodium nitrate, and 0.2% to 0.5% of lithium nitrate.

[0104] Optionally, the range of the difference between the surface compressive stress CS1 of the first planar portion 10 and the surface compressive stress CS3 of the bendable portion 30 is: CS1-CS3≤50MPa, and the range of the difference between the surface compressive stress CS2 of the second planar portion 50 and the surface compressive stress CS3 of the bendable portion 30 is: CS2-CS3≤50MPa.

[0105] Specifically, the difference between the surface compressive stress CS1 of the first planar portion 10 and the surface compressive stress CS3 of the bendable portion 30 may be, but is not limited to, 5 MPa, 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa, 40 MPa, 45 MPa, 50 MPa, etc. The smaller the difference between the surface compressive stress CS1 of the first planar portion 10 and the surface compressive stress CS3 of the bendable portion 30, the better. When the thickness of the glass cover 100 varies greatly, it is difficult for the surface compressive stress CS1 of the first planar portion 10 and the surface compressive stress CS3 of the bendable portion 30 to be equal. If the difference between the surface compressive stress CS1 of the first planar portion 10 and the surface compressive stress CS3 of the bendable portion 30 is too large, the distortion between the first planar portion 10 and the bendable portion 30 is increased, and the light and shadow distortion phenomenon is increased, which affects the appearance of the glass cover 100.

[0106] Specifically, the difference between the surface compressive stress CS2 of the second planar portion 50 and the surface compressive stress CS3 of the bendable portion 30 may be, but is not limited to, 5 MPa, 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa, 40 MPa, 45 MPa, 50 MPa, etc. The smaller the difference between the surface compressive stress CS2 of the second planar portion 50 and the surface compressive stress CS3 of the bendable portion 30, the better. When the thickness of the glass cover 100 varies greatly, it is difficult for the surface compressive stress CS2 of the second planar portion 50 to be equal to the surface compressive stress CS3 of the bendable portion 30. If the difference between the surface compressive stress CS2 of the second planar portion 50 and the surface compressive stress CS3 of the bendable portion 30 is too large, the distortion between the second planar portion 50 and the bendable portion 30 is increased, and the light and shadow distortion phenomenon is increased, which affects the appearance of the glass cover 100.

[0107] Please see again Figure 3Optionally, the first planar portion 10 includes a first compressive stress layer 12 (DOL for short), the second planar portion 50 includes a second compressive stress layer 52, and the bendable portion 30 includes a third compressive stress layer 32. The difference between the thickness DOL1 of the first compressive stress layer 12 and the thickness DOL3 of the third compressive stress layer 32 is in the range of: 0.1 μm ≤ DOL1 - DOL3 ≤ 0.3 μm; the difference between the thickness DOL2 of the second compressive stress layer 52 and the thickness DOL3 of the third compressive stress layer 32 is in the range of: 0.1 μm ≤ DOL2 - DOL3 ≤ 0.3 μm.

[0108] Specifically, the difference between the thickness DOL1 of the first compressive stress layer 12 and the thickness DOL3 of the third compressive stress layer 32 can be, but is not limited to, 0.1 μm, 0.13 μm, 0.15 μm, 0.18 μm, 0.2 μm, 0.23 μm, 0.25 μm, 0.28 μm, 0.3 μm, etc. If the difference between the thickness DOL1 of the first compressive stress layer 12 and the thickness of the third compressive stress layer 32 is too great, the surface compressive stress difference between the first planar portion 10 and the bendable portion 30 will be too great, increasing the light and shadow distortion phenomenon of the bendable portion 30. If the difference between the thickness DOL1 of the first compressive stress layer 12 and the thickness of the third compressive stress layer 32 is too small, it will be difficult to achieve in terms of process, or only a glass cover plate 100 with similar thicknesses for the first planar portion 10 and the bendable portion 30 can be used, which will affect the bending performance of the glass cover plate 100.

[0109] Specifically, the difference between the thickness DOL2 of the second compressive stress layer 52 and the thickness DOL3 of the third compressive stress layer 32 can be, but is not limited to, 0.1 μm, 0.13 μm, 0.15 μm, 0.18 μm, 0.2 μm, 0.23 μm, 0.25 μm, 0.28 μm, 0.3 μm, etc. If the difference between the thickness DOL2 of the second compressive stress layer 52 and the thickness of the third compressive stress layer 32 is too great, the surface compressive stress difference between the second planar portion 50 and the bendable portion 30 will be too great, increasing the light and shadow distortion phenomenon of the bendable portion 30. If the difference between the thickness DOL2 of the second compressive stress layer 52 and the thickness of the third compressive stress layer 32 is too small, it will be difficult to achieve in terms of process, or it may be necessary to use a glass cover plate 100 with similar thicknesses for the second planar portion 50 and the bendable portion 30, which will affect the bending performance of the glass cover plate 100.

[0110] Optionally, the thickness DOL1 of the first compressive stress layer 12 is in the range of 5 μm ≤ DOL1 ≤ 7 μm. Optionally, the thickness DOL2 of the second compressive stress layer 52 is in the range of 5 μm ≤ DOL2 ≤ 7 μm. Optionally, the thickness DOL3 of the third compressive stress layer 32 is in the range of 5 μm ≤ DOL3 ≤ 7 μm.

[0111] Regarding the glass cover 100 , the first planar portion 10 , the bendable portion 30 , the second planar portion 50 and other parts having the same features as those in the above embodiment, please refer to the description of the corresponding parts in the above embodiment and will not be repeated here.

[0112] The glass cover plate 100 of the embodiment of the present application can be prepared by the methods described in the following embodiments of the present application. In addition, it can also be prepared by other methods. The preparation methods of the embodiments of the present application are merely one or more preparation methods of the glass cover plate 100 of the present application and should not be understood as limiting the glass cover plate 100 provided by the embodiments of the present application.

[0113] See Figure 4 The present embodiment further provides a method for preparing a glass cover plate 100, which includes:

[0114] S201, providing a glass substrate;

[0115] Optionally, the glass substrate may be, but is not limited to, high-aluminum glass.

[0116] Alternatively, as Figure 5 As shown, the glass substrate 100a includes a first substrate portion 10a, a thinned portion 30a, and a second substrate portion 50a connected in sequence. The thickness of the thinned portion 30a is smaller than that of the first substrate portion 10a and smaller than that of the second substrate portion 50a.

[0117] S202: The glass substrate 100a is placed in a molten salt for chemical strengthening to obtain the glass cover plate 100. The glass cover plate 100 includes a first planar portion 10, a bendable portion 30, and a second planar portion 50 connected in sequence. The thickness of the bendable portion 30 is less than the thickness of the first planar portion 10, and the thickness of the bendable portion 30 is less than the thickness of the second planar portion 50. The difference between the surface compressive stress CS1 of the first planar portion 10 and the surface compressive stress CS3 of the bendable portion 30 is in the range of CS1-CS3≤50 MPa. The difference between the surface compressive stress CS2 of the second planar portion 50 and the surface compressive stress CS3 of the bendable portion 30 is in the range of CS2-CS3≤50 MPa.

[0118] Optionally, the glass substrate 100 a is placed in molten salt for chemical strengthening, so that the first substrate portion 10 a forms the first planar portion 10 , the thinned portion 30 a forms the bendable portion 30 , and the second substrate portion 50 a forms the second planar portion 50 .

[0119] For detailed description of the first planar portion 10 , the bendable portion 30 , the second planar portion 50 and other features that are the same as those in the above embodiment, please refer to the above embodiment and will not be repeated here.

[0120] The glass cover plate 100 manufactured by the manufacturing method of the glass cover plate 100 according to the embodiment of the present application includes a first planar portion 10, a bendable portion 30, and a second planar portion 50 connected in sequence. The thickness of the bendable portion 30 is smaller than the thickness of the first planar portion 10 and smaller than the thickness of the second planar portion 50. The difference between the surface compressive stress of the first planar portion 10 and the surface compressive stress of the bendable portion 30 is within a range of 50 MPa, and the difference between the surface compressive stress of the second planar portion 50 and the surface compressive stress of the bendable portion 30 is also within a range of 50 MPa. As a result, the difference in surface compressive stress between the first planar portion 10 and the bendable portion 30, and between the second planar portion 50 and the bendable portion 30 of the glass cover plate 100 is small, so that the glass cover plate 100 does not have obvious light and shadow distortion and has a better appearance.

[0121] Optionally, providing the glass substrate 100a includes:

[0122] 1) Cleaning the glass substrate 100a in a weak alkaline solution (such as sodium carbonate) to remove grease from the surface of the glass substrate 100a;

[0123] 2) Wash with water to remove contaminants on the glass surface;

[0124] 3) placing the cleaned glass substrate 100a into a dedicated tempering fixture; and

[0125] 4) The tempering fixture containing the glass substrate 100a is placed on a rack of a tempering furnace and then placed in a preheating furnace for preheating.

[0126] Optionally, the preheating temperature may be 330° C. to 360° C., and the preheating temperature may be, but is not limited to, 330° C., 340° C., 350° C., 360° C., etc. The preheating time may be 20 min to 40 min, and specifically, the preheating time may be, but is not limited to, 20 min, 25 min, 30 min, 35 min, 40 min, etc.

[0127] Optionally, placing the glass substrate 100 a in a molten salt for chemical strengthening to obtain the glass cover plate 100 includes: immersing the glass substrate 100 a in a molten salt with a temperature T in the range of 360° C. ≤ T ≤ 380° C. for chemical strengthening to obtain the glass cover plate 100 .

[0128] Optionally, chemically strengthened salt is added to a salt melting furnace to melt and form molten salt, and the temperature T of the molten salt is set in the range of 360°C ≤ T ≤ 380°C. The glass substrate 100a is immersed in the molten salt in the melting furnace for chemical strengthening, and the chemical strengthening time ranges from 10 minutes to 30 minutes to obtain the glass cover plate 100.

[0129] Specifically, the temperature of the molten salt may be, but is not limited to, 360° C., 363° C., 365° C., 368° C., 370° C., 373° C., 375° C., 378° C., 380° C., etc. When the temperature of the molten salt is too high, the exchange rate between potassium ions and sodium ions is too fast, and the expansion rate of each portion of the glass substrate 100 a is too large, resulting in an increase in the difference in expansion rate between the first planar portion 10 and the bendable portion 30, and between the second planar portion 50 and the bendable portion 30. This also increases the difference in compressive stress between the first planar portion 10 and the bendable portion 30, and between the second planar portion 50 and the bendable portion 30, making the manufactured glass cover plate 100 susceptible to distortion and increasing the light and shadow distortion phenomenon of the glass cover plate 100. If the temperature of the molten salt is too low, the strengthening depth of the glass cover plate 100 is insufficient, resulting in low mechanical properties and failing to meet the requirements. Compared to conventional chemical strengthening, the chemical strengthening process of the present application uses a lower temperature. This can better prevent excessively rapid ion replacement during chemical strengthening, which could result in excessively large differences in expansion rates between the first planar portion 10 and the bendable portion 30, and between the second planar portion 50 and the bendable portion 30. This can also better prevent light and shadow distortion in the resulting glass cover 100.

[0130] Specifically, the chemical strengthening time can be, but is not limited to, 10 minutes, 12 minutes, 15 minutes, 18 minutes, 20 minutes, 22 minutes, 25 minutes, 28 minutes, 30 minutes, etc. If the chemical strengthening time is too long, the exchange amount of potassium ions and sodium ions is excessive, the strengthening depth of the glass substrate 100a is too deep, and the expansion rate of each part of the glass substrate 100a is too large, resulting in an increase in the expansion rate difference between the first planar portion 10 and the bendable portion 30, and between the second planar portion 50 and the bendable portion 30. The difference in compressive stress between the first planar portion 10 and the bendable portion 30, and between the second planar portion 50 and the bendable portion 30 also increases, making the manufactured glass cover plate 100 prone to distortion and deformation, and increasing the light and shadow distortion phenomenon of the glass cover plate 100. If the chemical strengthening time is too short, the strengthening depth of the glass cover plate 100 is insufficient, the mechanical properties are low, and it does not meet the requirements.

[0131] Optionally, after chemical strengthening, the method further includes: 1) opening the furnace body of the molten salt furnace, hanging the glass cover plate 100 on the furnace body, and letting it stand for 2 to 5 minutes to allow the molten salt on the surface of the glass cover plate 100 to drip into the furnace body, thereby reducing the amount of molten salt carried away by the strengthened glass cover plate 100 and improving the life of the molten salt; taking out the cover plate, cooling it from 350°C to 100°C in 2 hours (DOL), and then taking it out of the furnace; and immersing the cooled glass cover plate 100 in water and ultrasonically cleaning it to dissolve the molten salt on the surface of the glass cover plate 100.

[0132] In some embodiments, after chemical strengthening, the method further includes: etching the glass cover plate 100 in a hydrofluoric acid aqueous solution to etch away a portion of the compressive stress layer on the surface of the glass cover plate 100 .

[0133] Optionally, the mass concentration of the hydrofluoric acid aqueous solution is 2% to 4%, specifically, it can be but not limited to 2%, 2.5%, 3%, 3.5%, 4%, etc. Optionally, the etching time is 4 minutes to 6 minutes, specifically, it can be but not limited to 4 minutes, 5 minutes, 6 minutes, etc.

[0134] After chemical strengthening, the glass substrate 100a may have some microcracks on its surface. The presence of microcracks greatly reduces the mechanical strength of the glass cover plate 100. After etching away part of the compressive stress layer on the surface of the glass cover plate 100, the microcracks on the surface of the glass cover plate 100 can be passivated, thereby improving the surface strength of the glass cover plate 100.

[0135] Optionally, the molten salt includes potassium nitrate, sodium nitrate and lithium nitrate; in the molten salt, the range of the ratio of the mass fraction w1 of the potassium nitrate to the mass fraction w2 of the sodium nitrate is: 19≤w1 / w2≤49; the range of the ratio of the mass fraction w2 of the sodium nitrate to the mass fraction w3 of the lithium nitrate is: 4≤w2 / w3≤25.

[0136] Specifically, the ratio of the mass fraction w1 of potassium nitrate to the mass fraction w2 of sodium nitrate can be, but is not limited to, 19, 20, 22, 25, 28, 30, 32, 35, 38, 40, 43, 45, 47, 49, etc. The ratio of the mass fraction w1 of potassium nitrate to the mass fraction w2 of sodium nitrate is too small, indicating that the content of potassium nitrate in the molten salt is too little and the content of sodium nitrate is too much, which will excessively reduce the exchange rate of potassium ions and sodium ions, thereby making the mechanical strength of the obtained glass cover plate 100 too low. When applied to a flexible display screen, it cannot provide sufficient support and protection, and the drop resistance is also greatly reduced; the ratio of the mass fraction w1 of potassium nitrate to the mass fraction w2 of sodium nitrate is too large, indicating that the content of potassium nitrate in the molten salt is too much and the content of sodium nitrate is too little, then the compressive stress of the obtained glass cover plate 100 at a distance of 3 μm to 7 μm from the surface of the glass cover plate 100 along the thickness direction will drop sharply, thereby making the protective effect of the compressive stress layer on microcracks worse, making it difficult to prevent the spread of microcracks. When microcracks exist in the glass cover plate 100, the mechanical properties of the glass cover plate 100 are greatly reduced.

[0137] Specifically, the ratio of the mass fraction w2 of the sodium nitrate to the mass fraction w3 of the lithium nitrate can be, but is not limited to, 4, 5, 8, 10, 12, 14, 16, 18, 20, 22, 24, 25, etc. If the ratio of the mass fraction w2 of the sodium nitrate to the mass fraction w3 of the lithium nitrate is too large, the amount of lithium ions entering the glass substrate 100a will be excessively suppressed, thereby increasing the expansion rate of the glass cover plate 100 in a direction perpendicular to the thickness (such as the X direction or the Y direction) and increasing the difference in expansion rate between the first planar portion 10 or the second planar portion 50 and the bendable portion 30, making the light and shadow distortion phenomenon of the glass cover plate 100 more serious; if the ratio of the mass fraction w2 of the sodium nitrate to the mass fraction w3 of the lithium nitrate is too small, the sodium ions will not be able to enter the glass substrate 100a. If the inhibition of lithium ions entering the glass substrate 100 a is too weak, the lithium ion content in the glass substrate 100 a will be excessive, resulting in reduced mechanical strength. Furthermore, if the sodium nitrate content is too low, the compressive stress of the manufactured glass cover plate 100 will drop sharply along the thickness direction at a distance of 3 μm to 7 μm from the surface of the glass cover plate 100 . This will weaken the compressive stress layer's protective effect against microcracks, making it difficult to prevent the microcracks from spreading. When microcracks exist in the glass cover plate 100 , the mechanical properties of the glass cover plate 100 are greatly reduced.

[0138] Optionally, the molten salt comprises, by mass fraction, 94.5% to 97.8% of potassium nitrate, 2% to 5% of sodium nitrate, and 0.2% to 0.5% of lithium nitrate.

[0139] For detailed description of the features that are the same between this embodiment and the above embodiment, please refer to the above embodiment, which will not be repeated here.

[0140] The glass cover plate 100 provided in the embodiment of the present application is further described below through specific examples.

[0141] Examples 1 to 5, Comparative Examples 1 and 5

[0142] The glass cover plate 100 of this embodiment is prepared by the following steps:

[0143] 1) Providing a glass substrate 100a; the glass substrate 100a includes a first substrate portion 10a, a thinned portion 30a, and a second substrate portion 50a connected in sequence. The first substrate portion 10a has a thickness of 100 μm, the second substrate portion 50a has a thickness of 100 μm, and the thinned portion 30a has a minimum thickness of 30 μm.

[0144] 2) The glass substrate 100 a is immersed in a molten salt at a temperature of 370° C. for chemical strengthening for 15 minutes to obtain a glass cover plate 100 , wherein the first substrate portion 10 a forms the first planar portion 10 , the thinned portion 30 a forms the bendable portion 30 , and the second substrate portion 50 a forms the second planar portion 50 .

[0145] The components and proportions of the molten salt in each embodiment and comparative example are shown in Table 1 below.

[0146] The surface compressive stress (CS), thickness or depth of the compressive stress layer (DOL), and expansion ratio (e) of the first planar portion 10, second planar portion 50, and bendable portion 30 of the glass cover 100 of each embodiment and comparative example were measured. The test results are shown in Table 1 below. The surface compressive stress and the depth of the compressive stress layer were measured using an FSM-6000k surface stress tester, and the expansion ratio was calculated using a two-dimensional length and width measurement.

[0147] Table 1 Performance parameters of each embodiment and comparative example

[0148]

[0149] From the test results of Example 1 and Comparative Example 2, it can be seen that when chemical strengthening is performed, adding lithium nitrate to the molten salt can greatly reduce the expansion rate of the glass cover 100, and can reduce the expansion rate difference between the bendable portion 30 and the first plane portion 10 and the bendable portion 30 and the second plane portion 50, thereby better improving the light and shadow distortion phenomenon caused by the distortion between the bendable portion 30 and the first plane portion 10 and the bendable portion 30 and the second plane portion 50. From the test data of Examples 1 to 3, Comparative Examples 2 and 3, it can be seen that when chemical strengthening is performed, when the content of sodium nitrate in the molten salt remains unchanged, the content of lithium nitrate increases, and the content of potassium nitrate decreases, the expansion rate of the obtained glass cover 100 decreases, and the surface compressive stress and the thickness of the compressive stress layer gradually decrease. From the test results of Comparative Example 3, it can be seen that when chemical strengthening is performed, when the content of lithium nitrate in the molten salt is too high, the surface compressive stress of the obtained glass cover 100 is too low, the mechanical strength is too low, and it cannot meet the application requirements.

[0150] The test data of Example 1 and Comparative Example 1 show that, when chemical strengthening is performed, sodium nitrate and lithium nitrate are added to the molten salt. Although the surface compressive stress of the strengthened glass cover plate 100 is reduced, it still has a high surface compressive stress, thereby having high mechanical strength. In addition, the surface compressive stress difference and expansion rate difference between the bendable portion 30 and the first planar portion 10 and between the bendable portion 30 and the second planar portion 50 of the glass cover plate 100 are also greatly reduced, thereby better avoiding deformation and distortion between the bendable portion 30 and the first planar portion 10 and between the bendable portion 30 and the second planar portion 50 of the glass cover plate 100, and better improving the light and shadow distortion caused by the distortion between the bendable portion 30 and the first planar portion 10 and between the bendable portion 30 and the second planar portion 50 of the glass cover plate 100.

[0151] The test data from Examples 2, 4, 5, Comparative Examples 4, and 5 show that adding sodium nitrate to the molten salt during chemical strengthening can result in a higher surface compressive stress in the chemically strengthened glass cover plate 100, thereby providing higher mechanical strength. Furthermore, the differences in expansion rates and surface stress between the bendable portion 30 and the first planar portion 10, and between the bendable portion 30 and the second planar portion 50, can be reduced, thereby further improving the light and shadow distortion caused by distortion between the bendable portion 30 and the first planar portion 10, and between the bendable portion 30 and the second planar portion 50, of the strengthened glass cover plate 100. The test results from Comparative Example 5 show that when the sodium nitrate content in the molten salt is too high, the surface compressive stress of the glass cover plate 100 is too low, and the mechanical strength is too low, failing to meet application requirements.

[0152] The glass cover plate 100 obtained in Example 1 and Comparative Example 1 was etched with 3% hydrofluoric acid for 5 minutes to partially remove the compressive stress layer on the surface of the glass cover plate 100. The surface compressive stress (CS), thickness or depth of the compressive stress layer (DOL), and expansion coefficient (e) of the first planar portion 10, second planar portion 50, and bendable portion 30 of the thinned glass cover plate 100 were measured. The test results are shown in Table 2 below.

[0153] Table 2 Performance parameters of Example 1 and Comparative Example 1

[0154]

[0155] The test results in Table 2 show that when hydrofluoric acid is used for etching, the surface compressive stress of the obtained glass cover plate 100 is reduced, but still maintains a relatively high surface compressive stress. However, after etching away part of the compressive stress layer, microcracks on the surface of the glass cover plate 100 can be passivated, thereby improving the mechanical strength of the glass cover plate 100.

[0156] See Figure 6 The embodiment of the present application also provides a flexible display screen 200, which includes: a display layer 210 and the glass cover plate 100 described in the embodiment of the present application, wherein the glass cover plate 100 and the display layer 210 are stacked to protect the display layer 210.

[0157] Optionally, the display layer 210 may be, but is not limited to, an organic display layer 210 , such as an active matrix organic light emitting diode (AMOLED).

[0158] Optionally, the display layer 210 may be bonded to the glass cover 100 by using an adhesive with high light transmittance such as optical adhesive (OCA adhesive).

[0159] For a detailed description of the glass cover 100 , please refer to the description of the corresponding part of the above embodiment, which will not be repeated here.

[0160] It is understood that the flexible display 200 in this embodiment is merely one form of a flexible display 200 applied to the glass cover 100 and should not be construed as limiting the flexible display 200 provided in this application, nor should it be construed as limiting the glass cover 100 provided in each embodiment of this application. For a detailed description of the glass cover 100, please refer to the corresponding description of the above embodiment, which will not be repeated here.

[0161] See Figures 7 to 9 , an embodiment of the present application also provides a foldable electronic device 300, which includes: the flexible display screen 200 described in the embodiment of the present application, a foldable mechanism 310 and a processor 330, the foldable mechanism 310 is used to support the flexible display screen 200 and to drive the flexible display screen 200 to fold or flatten, wherein the glass cover plate 100 of the flexible display screen 200 is farther away from the foldable mechanism 310 than the display layer 210; the processor 330 is electrically connected to the flexible display screen 200, and is used to control the display screen to display.

[0162] The foldable electronic device 300 of the embodiment of the present application can be, but is not limited to, a portable foldable electronic device 300 with a variable display screen size, such as a mobile phone, tablet computer, e-reader, or laptop computer. It is understood that the foldable electronic device 300 in this embodiment is merely one form of foldable electronic device 300 applied to the flexible display screen 200 and should not be construed as limiting the foldable electronic device 300 provided in this application, nor should it be construed as limiting the flexible display screen 200 provided in each embodiment of this application. For a detailed description of the flexible display screen 200, please refer to the corresponding description of the above embodiment, which will not be repeated here.

[0163] For a detailed description of the flexible display screen 200 , the glass cover plate 100 , etc., please refer to the description of the corresponding parts of the above embodiments, which will not be repeated here.

[0164] Please also see Figure 10In some embodiments, the foldable mechanism 310 includes a first carrier 311, a connecting shaft 313, and a second carrier 315 that are movably connected in sequence; the first carrier 311, the connecting shaft 313, and the second carrier 315 cooperate to support the flexible display screen 200 and drive the flexible display screen 200 to fold or unfold; the foldable mechanism 310 has a flattened state and a folded state. When the foldable mechanism 310 is in the flattened state, the first carrier 311, the connecting member, and the second carrier 315 form a planar structure; when the foldable mechanism 310 is in the folded state, the first carrier 311 and the second carrier 315 overlap, and drive the flexible display screen 200 to fold.

[0165] It can be understood that when the orthographic projection of the surface of the foldable mechanism 310 of the flexible display screen 200 facing the flexible display screen 200 falls within the range of the surface of the foldable mechanism 310 facing the flexible display screen 200 .

[0166] Optionally, processor 330 includes one or more general-purpose processors, where a general-purpose processor can be any type of device capable of processing electronic instructions, including a central processing unit (CPU), a microprocessor, a microcontroller, a main processor, a controller, and an ASIC. Processor 330 is used to execute various types of digitally stored instructions, such as software or firmware programs stored in memory, which enables the computing device to provide a wide variety of services.

[0167] Optionally, the foldable electronic device 300 of the present application further includes a memory 350. The memory 350 is electrically connected to the processor 330 and is used to store program codes required for the processor 330 to run, program codes required to control the flexible display 200, display content of the flexible display 200, etc.

[0168] Optionally, the memory 350 may include volatile memory, such as random access memory (RAM); the memory 350 may also include non-volatile memory (NVM), such as read-only memory (ROM), flash memory (FM), hard disk drive (DOLDD), or solid-state drive (SSD). The memory 350 may also include a combination of the above types of memory.

[0169] In some embodiments, the foldable electronic device 300 of the embodiment of the present application further includes a camera module 370, which is carried by the foldable mechanism 310. The camera module 370 is electrically connected to the processor 330 and is configured to take pictures under the control of the processor 330.

[0170] Optionally, the camera module 370 may be a rear camera module 370 or a front camera module 370. This application does not make any specific limitation.

[0171] Mentioning "embodiments" and "implementation methods" in this application means that the specific features, structures or characteristics described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrases in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments. In addition, it should be understood that the features, structures or characteristics described in the various embodiments of the present application can be arbitrarily combined to form another embodiment that does not deviate from the spirit and scope of the technical solution of the present application, unless there is a contradiction between them.

[0172] Finally, it should be noted that the above implementation modes are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the above preferred implementation modes, ordinary technicians in this field should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A glass cover plate, characterized in that: include: A first planar portion, a bendable portion, and a second planar portion are sequentially connected, wherein the thickness of the bendable portion is less than the thickness of the first planar portion, and the thickness of the bendable portion is less than the thickness of the second planar portion. The difference between the surface compressive stress CS1 of the first planar portion and the surface compressive stress CS3 of the bendable portion is in the range of: CS1-CS3≤50Mpa, and the difference between the surface compressive stress CS2 of the second planar portion and the surface compressive stress CS3 of the bendable portion is in the range of: CS2-CS3≤50Mpa. The glass cover plate is a glass cover plate obtained by chemically strengthening a glass substrate with molten salt, and the molten salt includes potassium nitrate, sodium nitrate, and lithium nitrate. In the molten salt, the ratio of the mass fraction w1 of the potassium nitrate to the mass fraction w2 of the sodium nitrate is in the range of: 19≤w1 / w2≤49; the ratio of the mass fraction w2 of the sodium nitrate to the mass fraction w3 of the lithium nitrate is in the range of: 4≤w2 / w3≤25.

2. The glass cover according to claim 1, wherein: The surface compressive stress CS1 of the first planar portion is in the range of 470 MPa≤CS1≤550 MPa, the surface compressive stress CS2 of the second planar portion is in the range of 470 MPa≤CS2≤550 MPa, and the surface compressive stress CS3 of the bendable portion is in the range of 450 MPa≤CS3≤530 MPa.

3. The glass cover according to claim 1, wherein: The first planar portion includes a first compressive stress layer, the second planar portion includes a second compressive stress layer, and the bendable portion includes a third compressive stress layer. The difference between the thickness DOL1 of the first compressive stress layer and the thickness DOL3 of the third compressive stress layer is in the range of: 0.1 μm ≤ DOL1 - DOL3 ≤ 0.3 μm; the difference between the thickness DOL2 of the second compressive stress layer and the thickness DOL3 of the third compressive stress layer is in the range of: 0.1 μm ≤ DOL2 - DOL3 ≤ 0.3 μm.

4. The glass cover according to claim 3, wherein: The thickness DOL1 of the first compressive stress layer is in the range of 5 μm≤DOL1≤7 μm; the thickness DOL2 of the second compressive stress layer is in the range of 5 μm≤DOL2≤7 μm; the thickness DOL3 of the third compressive stress layer is in the range of 5 μm≤DOL3≤7 μm.

5. The glass cover according to any one of claims 1 to 4, characterized in that: The glass cover plate satisfies at least one of the following conditions: The bendable portion includes a first transition sub-portion, a constant thickness sub-portion, and a second transition sub-portion connected in sequence, wherein the end of the first transition sub-portion facing away from the constant thickness sub-portion is connected to the first planar portion, and the end of the second transition sub-portion facing away from the constant thickness sub-portion is connected to the second planar portion; the thickness of the constant thickness sub-portion is less than the thickness of the first planar portion and less than the thickness of the second planar portion, and the thickness of the first transition sub-portion gradually decreases from the end connected to the first planar portion toward the end close to the constant thickness sub-portion, and the thickness of the second transition sub-portion gradually decreases from the end connected to the second planar portion toward the end close to the constant thickness sub-portion; The ratio d1 / d3 of the thickness d1 of the first planar portion to the thickness d3 of the equal-thickness sub-portion is in the range of: 1.4≤d1 / d3≤5; The ratio d2 / d3 of the thickness d2 of the second planar portion to the thickness d3 of the equal-thickness sub-portion is in the range of: 1.4≤d2 / d3≤5; The expansion rate e1 of the first plane portion before and after the chemical strengthening is in the range of The expansion rate e2 of the second plane portion before and after the chemical strengthening is in the range of as well as The expansion rate e3 of the bendable portion before and after the chemical strengthening is in the range of 6. The glass cover according to claim 5, wherein: Along the arrangement direction of the first planar portion, the bendable portion and the second planar portion, before and after the chemical strengthening, the range of the ratio of the expansion rate e3 of the bendable portion to the expansion rate e1 of the first planar portion is: 1.01≤e3 / e1≤1.2, and the range of the ratio of the expansion rate e3 of the bendable portion to the expansion rate e2 of the second planar portion is: 1.01≤e3 / e2≤1.

2.

7. A glass cover plate, characterized in that: The glass cover plate includes a first planar portion, a bendable portion, and a second planar portion connected in sequence. The thickness of the bendable portion is smaller than that of the first planar portion, and the thickness of the bendable portion is smaller than that of the second planar portion. The glass cover plate is obtained by chemically strengthening a glass substrate with a molten salt, and the molten salt includes potassium nitrate, sodium nitrate, and lithium nitrate. Before and after the chemical strengthening, along the arrangement direction of the first planar portion, the bendable portion, and the second planar portion, a ratio of an expansion coefficient e3 of the bendable portion to an expansion coefficient e1 of the first planar portion is in the range of 1.01≤e3 / e1≤1.2, and a ratio of an expansion coefficient e3 of the bendable portion to an expansion coefficient e2 of the second planar portion is in the range of 1.01≤e3 / e2≤1.

2.

8. The glass cover according to claim 7, wherein: The difference between the expansion rate e3 of the bendable portion and the expansion rate e1 of the first planar portion is in the range of: The difference between the expansion rate e3 of the bendable portion and the expansion rate e2 of the second planar portion is in the range of:

9. The glass cover according to claim 7, wherein: In the molten salt, the ratio of the mass fraction w1 of the potassium nitrate to the mass fraction w2 of the sodium nitrate is in the range of 19≤w1 / w2≤49; the ratio of the mass fraction w2 of the sodium nitrate to the mass fraction w3 of the lithium nitrate is in the range of 4≤w2 / w3≤25.

10. The glass cover according to claim 9, wherein: The molten salt comprises, by mass fraction, 94.5% to 97.8% of potassium nitrate, 2% to 5% of sodium nitrate, and 0.2% to 0.5% of lithium nitrate.

11. The glass cover according to claim 7, wherein: The difference between the surface compressive stress CS1 of the first planar portion and the surface compressive stress CS3 of the bendable portion is in the range of CS1-CS3≤50MPa, and the difference between the surface compressive stress CS2 of the second planar portion and the surface compressive stress CS3 of the bendable portion is in the range of CS2-CS3≤50MPa.

12. The glass cover according to any one of claims 7 to 11, characterized in that: The first planar portion includes a first compressive stress layer, the second planar portion includes a second compressive stress layer, and the bendable portion includes a third compressive stress layer. The difference between the thickness DOL1 of the first compressive stress layer and the thickness DOL3 of the third compressive stress layer is in the range of: 0.1 μm ≤ DOL1 - DOL3 ≤ 0.3 μm; the difference between the thickness DOL2 of the second compressive stress layer and the thickness DOL3 of the third compressive stress layer is in the range of: 0.1 μm ≤ DOL2 - DOL3 ≤ 0.3 μm.

13. A method for preparing a glass cover plate, characterized in that: include: providing a glass substrate; A glass substrate is placed in a molten salt for chemical strengthening to obtain the glass cover plate. The glass cover plate includes a first planar portion, a bendable portion, and a second planar portion connected in sequence. The bendable portion is thinner than the first planar portion, and the bendable portion is thinner than the second planar portion. The difference between a surface compressive stress CS1 of the first planar portion and a surface compressive stress CS3 of the bendable portion is in the range of CS1-CS3≤50 MPa, and the difference between a surface compressive stress CS2 of the second planar portion and a surface compressive stress CS3 of the bendable portion is in the range of CS2-CS3≤50 MPa. The molten salt includes potassium nitrate, sodium nitrate, and lithium nitrate. In the molten salt, the ratio of the mass fraction w1 of the potassium nitrate to the mass fraction w2 of the sodium nitrate is in the range of 19≤w1 / w2≤49; and the ratio of the mass fraction w2 of the sodium nitrate to the mass fraction w3 of the lithium nitrate is in the range of 4≤w2 / w3≤25.

14. The method for preparing a glass cover plate according to claim 13, wherein: After chemical strengthening, the preparation method further comprises: etching the glass cover plate in a hydrofluoric acid aqueous solution.

15. The method for preparing a glass cover plate according to claim 13, wherein: The molten salt comprises, by mass fraction, 94.5% to 97.8% of potassium nitrate, 2% to 5% of sodium nitrate, and 0.2% to 0.5% of lithium nitrate.

16. The method for preparing a glass cover plate according to any one of claims 13 to 15, wherein: Placing the glass substrate in molten salt for chemical strengthening to obtain the glass cover plate comprises: The glass substrate is immersed in a molten salt with a temperature T ranging from 360° C. to 380° C. for chemical strengthening to obtain the glass cover plate.

17. A flexible display screen, characterized in that: include: Display layer; as well as The glass cover plate according to any one of claims 1 to 12, wherein the glass cover plate is stacked with the display layer to protect the display layer.

18. A foldable electronic device, characterized in that: include: The flexible display screen according to claim 17; a foldable mechanism, the foldable mechanism being used to support the flexible display screen and to drive the flexible display screen to fold or flatten, wherein the glass cover plate of the flexible display screen is further away from the foldable mechanism than the display layer of the flexible display screen; as well as A processor is electrically connected to the flexible display screen and is used to control the display screen to display.

Images