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

Abstract

The invention provides a glass cover plate and a preparation method thereof, a flexible display screen and electronic equipment. The glass cover plate comprises a first plane part, a bendable part and a second plane part which are sequentially connected, the thickness of the bendable part is smaller than that of the first plane part, the thickness of the bendable part is smaller than that of the second plane part, and the range of the difference value between the surface pressure stress CS1 of the first plane part and the surface pressure stress CS3 of the bendable part is CS1-CS3 < = 50 Mpa. The range of the difference value between the surface pressure stress CS2 of the second plane part and the surface pressure stress CS3 of the bendable part is CS2-CS3 < = 50 Mpa. The surface pressure stress difference between the first plane part and the bendable part and the surface pressure stress difference between the second plane part and the bendable part of the glass cover plate are small, so that the distortion between the first plane part and the bendable part and the distortion between the second plane part and the bendable part of the glass cover plate are small, no obvious shadow distortion phenomenon exists, and a better appearance effect is achieved.

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 display screens, ultra-thin glass (Ultra Flexible Glass) is widely used as a cover plate of flexible display screens to protect and make flexible display screens. 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 different surface compressive stresses between the bending area and the flat area, the bending area after chemical strengthening will produce serious distortion and deformation, affecting the appearance and bending performance of the ultra-thin glass. Summary of the invention

[0003] In response to the above problems, an embodiment of the present application provides a glass cover plate, in which the difference in surface compressive stress between the first plane portion and the bendable portion, and between the second plane portion and the bendable portion of the glass cover plate is small, so that the distortion deformation between the first plane portion and the bendable portion, and between the second plane portion and the bendable portion of the glass cover plate is small, so that there is no obvious light and shadow distortion phenomenon, and the appearance effect is better.

[0004] In a first aspect, an embodiment 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, the thickness of the bendable portion is less than the thickness of the first planar portion, the thickness of the bendable portion is less than the thickness of the second planar portion, the range of the difference between the surface compressive stress CS1 of the first planar portion and the surface compressive stress CS3 of the bendable portion is: CS1-CS3≤50Mpa, and the range of the difference between the surface compressive stress CS2 of the second planar portion and the surface compressive stress CS3 of the bendable portion is: CS2-CS3≤50Mpa.

[0005] According to a second aspect of the present application, there is provided a glass cover plate, the glass cover plate comprising a first plane portion, a bendable portion and a second plane portion connected in sequence, the thickness of the bendable portion being smaller than the thickness of the first plane portion, the thickness of the bendable portion being smaller than the thickness of the second plane portion, the glass cover plate being obtained by chemically strengthening a glass substrate with molten salt, the molten salt comprising potassium nitrate, sodium nitrate and lithium nitrate; along the arrangement direction of the first plane portion, the bendable portion and the second plane portion, before and after the chemical strengthening, the ratio of the expansion rate e3 of the bendable portion to the expansion rate e1 of the first plane portion is in the range of: 1.01≤e3 / e1≤1.2, and the ratio of the expansion rate e3 of the bendable portion to the expansion rate e2 of the second plane portion is in the range of: 1.01≤e3 / e2≤1.2.

[0006] A third aspect of the present application provides a method for preparing a glass cover plate, which includes:

[0007] providing a glass substrate;

[0008] A glass substrate is placed in a molten salt for chemical strengthening to obtain the glass cover plate, wherein 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, 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 aspect of the present application provides a flexible display screen, characterized in that it includes:

[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 carry the flexible display screen and to drive the flexible display screen to be folded or flattened, wherein the glass cover plate of the flexible display screen is farther 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 plane portion, a bendable portion and a second plane portion connected in sequence, the thickness of the bendable portion is less than the thickness of the first plane portion, and the thickness of the bendable portion is less than the thickness of the second plane portion, the difference between the surface compressive stress of the first plane portion and the surface compressive stress of the bendable portion is within the range of 50Mpa, and the difference between the surface compressive stress of the second plane portion and the surface compressive stress of the bendable portion is within the range of 50Mpa, so that the difference in surface compressive stress between the first plane portion and the bendable portion, and between the second plane portion and the bendable portion of the glass cover plate is small, so that the distortion deformation between the first plane portion and the bendable portion, and between the second plane portion and the bendable portion of the glass cover plate is small, so that 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 drawings required for use in the embodiments will be briefly introduced below. 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 It is a schematic diagram of the planar structure of a glass cover plate according to an embodiment of the present application.

[0019] Figure 2 The glass cover plate 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 It is a schematic flow chart of a method for preparing a glass cover plate according to an embodiment of the present application.

[0022] Figure 5 Schematic diagram of the cross-sectional structure of a glass cover plate according to an embodiment of the present application.

[0023] Figure 6 It is a structural schematic diagram of a flexible display screen according to an embodiment of the present application.

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

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

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

[0027] Fig.10 yes Figure 8 Enlarged view of dashed box I.

[0028] Description of reference numerals:

[0029] 100-glass cover, 10-first plane 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 plane portion, 52-second compressive stress layer, 100a-glass substrate, 10a-first substrate portion, 30a-thinning portion, 50a-second substrate portion, 200-flexible display screen, 210-display layer, 300-foldable electronic device, 310-foldable mechanism, 311-first carrier, 313-connecting axis, 315-second carrier, 330-processor, 350-memory, 370-camera module. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, 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", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

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

[0033] It should be noted that, for the convenience of explanation, in the embodiments of the present application, the same figure marks 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 display screens, ultra-thin glass (Ultra Flexible Glass) is widely used as a cover plate for flexible display screens to protect and make flexible display screens. 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 plane areas on both sides. After chemical strengthening, due to the different surface compressive stress (Compressed Stress, referred to as CS) and expansion rate formed between the bending area and the plane area, the bending area after chemical strengthening will produce serious distortion and deformation, so that the bending area (i.e., the thinning area) of the ultra-thin glass has light and shadow distortion, which affects the appearance and bending performance of the ultra-thin glass.

[0035] See also Figure 1 and Figure 2 The embodiment of the present application provides a glass cover 100, which 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, 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≤50Mpa, 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≤50Mpa.

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

[0037] Optionally, the material of the glass cover plate 100 may be, but is not limited to, high-aluminum glass. High-aluminum glass has good etching performance, and can better prepare the glass cover plate 100 with uneven thickness of the first plane portion 10, the second plane portion 50, and the bendable portion 30. High-aluminum glass has good anti-bending performance, and can make the prepared glass cover plate 100 have better bending performance.

[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 in the direction perpendicular to the arrangement 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 plane portion 10 is uniform, that is, the thickness of each position of the first plane portion 10 is equal. The thickness of the second plane portion 50 is uniform, that is, the thickness of each position of the second plane portion 50 is equal.

[0041] Optionally, the bendable portion 30 has an uneven thickness (ie, unequal thickness). It can be understood 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 plate 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 difference of the glass cover 100 is large, it is difficult for the surface compressive stress CS1 of the first planar portion 10 to be equal to the surface compressive stress CS3 of the bendable portion 30. 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, the light and shadow distortion phenomenon is increased, and the appearance effect of the glass cover 100 is affected.

[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 difference of the glass cover 100 is large, 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, the light and shadow distortion phenomenon is increased, and the appearance effect of the glass cover 100 is affected.

[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 embodiment of the present application includes a first plane portion 10, a bendable portion 30 and a second plane portion 50 connected in sequence. The thickness of the bendable portion 30 is smaller than the thickness of the first plane portion 10 and smaller than the thickness of the second plane portion 50. The difference between the surface compressive stress of the first plane 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 plane portion 50 and the surface compressive stress of the bendable portion 30 is within a range of 50 MPa. Therefore, the difference in surface compressive stress between the first plane portion 10 and the bendable portion 30 of the glass cover plate 100 and between the second plane portion 50 and the bendable portion 30 is small, so that the distortion deformation between the first plane portion 10 and the bendable portion 30 and between the second plane portion 50 and the bendable portion 30 of the glass cover plate 100 is small, so that there is no obvious light and shadow distortion phenomenon, and the appearance effect is better.

[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 connected in sequence, wherein the end of the first transition sub-portion 31 away from the uniform thickness sub-portion 33 is connected to the first plane portion 10, and the end of the second transition sub-portion 35 away from the uniform thickness sub-portion 33 is connected to the second plane portion 50. The thickness of the uniform thickness portion is less than the thickness of the first plane portion 10 and less than the thickness of the second plane portion 50, and the thickness of the first transition sub-portion 31 gradually decreases from the end connected to the first plane portion 10 to the end close to the uniform thickness sub-portion 33, and the thickness of the second transition sub-portion 35 gradually decreases from the end connected to the second plane portion 50 to the end close to the uniform thickness sub-portion 33.

[0048] Optionally, the range of the thickness d1 of the first planar portion 10 is: 70μm≤d1≤150μm. Specifically, the thickness of the first planar portion 10 may be, but is not limited to, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 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 screen, the supporting and protective effect of the first planar portion 10 on the flexible display screen is affected; the thickness of the first planar portion 10 increases, and has better support and flatness, but if the thickness of the first planar portion 10 is too thick, the flexible display screen is too thick, which is not conducive to the ultra-thinness of the flexible display screen.

[0049] Optionally, the range of the thickness d2 of the second planar portion 50 is: 70μm≤d2≤150μm. Specifically, the thickness of the second planar portion 50 may be, but is not limited to, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 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 screen, the supporting and protective effect of the second planar portion 50 on the flexible display screen is affected; the thickness of the second planar portion 50 is increased, and it has better support and flatness, but if the thickness of the second planar portion 50 is too thick, the flexible display screen is too thick, which is not conducive to the ultra-thinness of the flexible display screen.

[0050] Optionally, the thickness d3 of the equal thickness sub-section 33 is in the range of 20μm≤d3≤50μm. Specifically, the thickness of the equal thickness sub-section 33 may be, but is not limited to, 20μm, 30μm, 35μm, 40μm, 45μm, 50μm, etc. The thinner the thickness of the equal thickness sub-section 33, the better the bending resistance of the equal thickness sub-section 33. However, when the thickness of the equal thickness sub-section 33 is too thin, the mechanical strength of the equal thickness sub-section 33 will be reduced. When applied to a flexible display screen, the protection and support of the flexible display screen at the position of the equal thickness sub-section 33 will be reduced; if the thickness of the equal thickness sub-section 33 is too thick, the bending performance of the equal 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 equal-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 equal-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 equal-thickness sub-portion 33 is too small, it is difficult to make the glass cover plate 100 simultaneously satisfy that the bendable portion 30 has good bendability and the first planar portion 10 has good mechanical strength; if the ratio d1 / d3 of the thickness d1 of the first planar portion 10 to the thickness d3 of the equal-thickness sub-portion 33 is too large, the thickness of the equal-thickness sub-portion 33 may be too thin, reducing the mechanical strength of the equal-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 equal-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 thinness of the glass cover plate 100.

[0052] Optionally, the ratio d2 / d3 of the thickness d2 of the second planar portion 50 to the thickness d3 of the equal-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 equal-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 equal-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 equal-thickness sub-portion 33 is too large, the thickness of the equal-thickness sub-portion 33 may be too thin, thereby reducing the mechanical strength of the equal-thickness sub-portion 33. When applied to a flexible display screen, the protection and support of the flexible display screen at the position of the equal-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 thinness 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 may 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 may 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 may 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 protective and supporting effect 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 easily generated between the first planar portion 10 and the bendable portion 30, so that the glass cover 100 is prone to light and shadow distortion in 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 (such as impact strength) of the second planar portion 50 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 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, so that the glass cover 100 is 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 (such as impact strength) 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 large, the bending performance of the bendable portion 30 is reduced.

[0060] Optionally, the glass cover plate 100 is a glass cover plate 100 formed 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 in the form of ion exchange. When the glass cover plate 100 is subjected to external force, the 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 + ) to remove the sodium ions (Na + ) are replaced, potassium ions have a larger radius, and the surface layer of the glass substrate is squeezed by potassium ions, so that a compressive stress layer is formed on the surface layer of the glass substrate, thereby improving the mechanical strength of the glass cover plate 100. In addition, after chemical strengthening, the concentration of potassium ions in the glass cover plate 100 gradually decreases from the surface of the glass cover plate 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.

[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. Compared with sodium ions, lithium ions have a smaller radius, so negative expansion of the glass substrate can be achieved, and the overall expansion rate of the glass cover plate 100 can be reduced, especially in the direction perpendicular to the thickness (such as Figure 1 The expansion rate in the X direction and the Y direction in the figure 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 plate 100.

[0064] Adding sodium nitrate to the molten salt can reduce the exchange rate of potassium ions and sodium ions, thereby reducing the difference in surface stress and expansion rate between the first planar portion 10 or the second planar 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 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 embodiments of the present application, when there is a large difference in thickness between the first planar portion 10 and the second planar portion 50 and the bendable portion 30, the formula 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 lower than 1.2, thereby avoiding the distortion and light and shadow distortion of the glass cover 100 after chemical strengthening.

[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 the sodium nitrate may 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 the 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, so that the mechanical strength of the prepared glass cover plate 100 is too low. When applied to a flexible display screen, it cannot provide sufficient support and protection, and the anti-drop performance 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 prepared glass cover plate 100 along the thickness direction when the distance from the surface of the glass cover plate 100 is 3μm to 7μm will drop sharply, thereby making the protective effect of the compressive stress layer on microcracks worse, and it is 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 may 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 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 plane portion 10 or the second plane 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 small, the inhibitory effect of sodium ions on the entry of lithium ions into the glass substrate is too small, resulting in excessive content of lithium ions in the glass substrate and reduced mechanical strength. In addition, if the content of sodium nitrate is too small, the compressive stress of the prepared glass cover plate 100 in the thickness direction when the distance from the surface of the glass cover plate 100 is 3μm to 7μm will drop sharply, thereby making the protective effect of the compressive stress layer on microcracks worse, and it is 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.

[0069] Optionally, the molten salt comprises, by mass fraction, 94.5% to 97.8% potassium nitrate, 2% to 5% sodium nitrate and 0.2% to 0.5% 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 also 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 plane portion 10 includes at least two first compressive stress layers 12, and the two first compressive stress layers 12 are respectively located at two opposite ends of the first plane portion 10 along the thickness direction. The second plane portion 50 includes at least two second compressive stress layers 52, and the two second compressive stress layers 52 are respectively located at two opposite ends of the second plane portion 50 along the thickness direction. The bendable portion 30 includes at least two third compressive stress layers 32, and the two third compressive stress layers 32 are respectively located at two 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 formed by replacing the ions with a smaller radius in the glass substrate with the ions with a larger radius in the molten salt. For example, the sodium ions in the glass substrate are replaced by the 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 (such as potassium ions) in the molten salt in the glass substrate.

[0074] Optionally, 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. 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 large, the surface compressive stress difference between the first planar portion 10 and the bendable portion 30 is too large, which increases 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 is difficult to achieve in terms of technology, or only the glass cover plate 100 with similar thicknesses of 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.

[0075] Optionally, 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. 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 thickness DOL2 of the second compressive stress layer 52 differs too much from the thickness of the third compressive stress layer 32, the surface compressive stress of the second planar portion 50 and the bendable portion 30 differs too much, which increases the light and shadow distortion phenomenon of the bendable portion 30; if the thickness DOL2 of the second compressive stress layer 52 differs too little from the thickness of the third compressive stress layer 32, it is difficult to achieve in terms of technology, or only the glass cover plate 100 with similar thicknesses of the second planar portion 50 and the bendable portion 30 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 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 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 easily distorted in 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 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 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 protective and supporting effect 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 easily distorted in 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 strength) 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 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 is in the range of 1.01≤e3 / e1≤1.2. In other words, along the thickness direction perpendicular to the glass cover 100, 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 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 plane portion 10 is, the weaker the light and shadow distortion phenomenon of the glass cover plate 100 is. However, when the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e1 of the first plane 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 plane portion 10 and the bendable portion 30. In this way, it is difficult to make the glass cover plate 100 satisfy that the bendable portion 30 has good bending performance while the first plane portion 10 has good protection performance and support performance; when the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e1 of the first plane portion 10 is too large, the connection between the bendable portion 30 and the first plane portion 10 is severely twisted and deformed, 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 calculation method of the expansion rate of the second planar portion 50 and the bendable portion 30 is the same as that of the first planar portion 10, and will not be repeated here.

[0082] Optionally, along the arrangement direction of the first planar portion 10, the bendable portion 30 and the second planar portion 50, the range of the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e2 of the second planar portion 50 is: 1.01≤e3 / e2≤1.2. In other words, along the thickness direction perpendicular to the glass cover plate 100, the range of the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e2 of the second planar portion 50 is: 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 plane portion 50 is, the weaker the light and shadow distortion phenomenon of the glass cover plate 100 is. However, if the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e2 of the second plane 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 plane portion 50 and the bendable portion 30. In this way, it is difficult to make the glass cover plate 100 satisfy that the bendable portion 30 has good bending performance while the second plane portion 50 has good protection performance and support performance. If the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e2 of the second plane portion 50 is too large, the connection between the bendable portion 30 and the second plane portion 50 is severely twisted and deformed, and the light and shadow distortion phenomenon is severe.

[0084] Optionally, the difference between the expansion rate e3 of the bendable portion 30 and the expansion rate e1 of the first planar portion 10 is in the range of: (ten thousandth fraction 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 may 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 plane portion 10 is, the weaker the light and shadow distortion phenomenon of the glass cover plate 100 is. However, when the difference between the expansion rate e1 of the first plane 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 plane portion 10 and the bendable portion 30. In this way, it is difficult to make the glass cover plate 100 satisfy the requirements that the bendable portion 30 has good bending performance while the first plane portion 10 has good protection performance and support performance; when the difference between the expansion rate e1 of the first plane 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 plane portion 10 is severely twisted and deformed, and the light and shadow distortion phenomenon is severe.

[0085] Optionally, 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: Specifically, the difference between the expansion rate e3 of the bendable portion 30 and the expansion rate e2 of the second planar portion 50 may 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 plane portion 50 is, the weaker the light and shadow distortion phenomenon of the glass cover plate 100 is. However, when the difference between the expansion rate e2 of the second plane 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 plane portion 50 and the bendable portion 30. In this way, it is difficult to make the glass cover plate 100 satisfy the requirements that the bendable portion 30 has good bending performance while the second plane portion 50 has good protection performance and support performance. When the difference between the expansion rate e2 of the second plane 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 plane portion 50 is severely twisted and deformed, and the light and shadow distortion phenomenon is severe.

[0086] Optionally, the expansion rate e1 of the first plane portion 10 is in the range of Specifically, the expansion rate e1 of the first plane portion 10 may be, but is not limited to, If the expansion rate of the first planar portion 10 is too low, the difference between its expansion rate and that of the bendable portion 30 is too large, which may cause the connection between the first planar portion 10 and the bendable portion 30 to be severely distorted, 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. During chemical strengthening, the first planar portion 10 and the bendable portion 30 are strengthened in the same system, and the strengthening depth of the bendable portion 30 is also deepened, so that the expansion rate of the bendable portion 30 is relatively large, which further widens the expansion rate difference between the bendable portion 30 and the first planar portion 10, and also causes the connection between the first planar portion 10 and the bendable portion 30 to be severely distorted, 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 between its expansion rate and that of the bendable portion 30 is too large, which may cause the connection between the second planar portion 50 and the bendable portion 30 to be severely distorted, 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. During chemical strengthening, the second planar portion 50 and the bendable portion 30 are strengthened in the same system, and the strengthening depth of the bendable portion 30 is also deepened, so that the expansion rate of the bendable portion 30 is relatively large, which further widens the expansion rate difference between the bendable portion 30 and the second planar portion 50, and also causes the connection between the second planar portion 50 and the bendable portion 30 to be severely distorted, 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 plane portion 10 and the second plane portion 50, or the reinforcement depth of the first plane portion 10 and the second plane portion 50 is insufficient, reducing the mechanical strength of the first plane portion 10 and the second plane portion 50; if the expansion rate e3 of the bendable portion 30 is too high, the expansion rate difference between the first plane portion 10 and the second plane portion 50 and the bendable portion 30 is increased, exacerbating the light and shadow distortion between the first plane portion 10 and the second plane portion 50 and the bendable portion 30.

[0089] Please see again Figure 1 and Figure 2 The embodiment of the present application further provides a glass cover plate 100, the glass cover plate 100 comprises a first plane portion 10, a bendable portion 30 and a second plane portion 50 connected in sequence, the thickness of the bendable portion 30 is less than the thickness of the first plane portion 10, the thickness of the bendable portion 30 is less than the thickness of the second plane portion 50, the glass cover plate 100 is obtained by chemically strengthening a glass substrate with molten salt, the molten salt comprises potassium nitrate, sodium nitrate and lithium nitrate; along the arrangement direction of the first plane portion 10, the bendable portion 30 and the second plane 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 plane portion 10 is in the range of 1.01≤e3 / e1≤1.2, and the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e2 of the second plane portion 50 is in the 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 plane portion 10 is, the weaker the light and shadow distortion phenomenon of the glass cover plate 100 is. However, when the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e1 of the first plane 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 plane portion 10 and the bendable portion 30. In this way, it is difficult to make the glass cover plate 100 satisfy that the bendable portion 30 has good bending performance while the first plane portion 10 has good protection performance and support performance; when the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e1 of the first plane portion 10 is too large, the connection between the bendable portion 30 and the first plane portion 10 is severely twisted and deformed, 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 plane portion 50 is, the weaker the light and shadow distortion phenomenon of the glass cover plate 100 is. However, if the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e2 of the second plane 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 plane portion 50 and the bendable portion 30. In this way, it is difficult to make the glass cover plate 100 satisfy that the bendable portion 30 has good bending performance while the second plane portion 50 has good protection performance and support performance. If the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e2 of the second plane portion 50 is too large, the connection between the bendable portion 30 and the second plane portion 50 is severely twisted and deformed, 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 + ) to remove the sodium ions (Na +) are replaced, potassium ions have a larger radius, and the surface of the glass substrate is squeezed by potassium ions, so that a compressive stress layer is formed on the surface of the glass substrate, thereby improving the mechanical strength of the glass cover plate 100. In addition, after chemical strengthening, the concentration of potassium ions in the glass cover plate 100 gradually decreases from the surface of the glass cover plate 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 plate 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, and the overall expansion rate of the glass cover plate 100 is reduced, especially 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), which can better reduce the difference in expansion rate 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 plate 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 caused by the bendable portion 30. In addition, sodium ions can also inhibit the lithium ions (Li + ) replaces 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 plane portion 10, a bendable portion 30 and a second plane portion 50 connected in sequence, the thickness of the bendable portion 30 is smaller than the thickness of the first plane portion 10 and smaller than the thickness of the second plane portion 50, the glass cover plate 100 is obtained by chemically strengthening a glass substrate with molten salt, and before and after chemical strengthening, the range of the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e1 of the first plane portion 10 is: 1.01≤e3 / e1≤1.2, and the range of the ratio of the expansion rate e3 of the bendable portion 30 to the expansion rate e2 of the second plane portion 50 is: 1.01≤e3 / e2≤1.2. This indicates that before and after chemical strengthening, 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 is controlled within the range of 20%, with a smaller difference in expansion rate, so that 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 smaller, so that there is no obvious light and shadow distortion phenomenon, and the appearance effect is better.

[0094] Optionally, the difference between the expansion rate e3 of the bendable portion 30 and the expansion rate e1 of the first planar portion 10 is in the range of: And 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 may 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 plane portion 10 is, the weaker the light and shadow distortion phenomenon of the glass cover plate 100 is. However, when the difference between the expansion rate e1 of the first plane 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 plane portion 10 and the bendable portion 30. In this way, it is difficult to make the glass cover plate 100 satisfy the requirements that the bendable portion 30 has good bending performance while the first plane portion 10 has good protection performance and support performance; when the difference between the expansion rate e1 of the first plane 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 plane portion 10 is severely twisted and deformed, 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 may 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 plane portion 50 is, the weaker the light and shadow distortion phenomenon of the glass cover plate 100 is. However, when the difference between the expansion rate e2 of the second plane 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 plane portion 50 and the bendable portion 30. In this way, it is difficult to make the glass cover plate 100 satisfy the requirements that the bendable portion 30 has good bending performance while the second plane portion 50 has good protection performance and support performance. When the difference between the expansion rate e2 of the second plane 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 plane portion 50 is severely twisted and deformed, and the light and shadow distortion phenomenon is severe.

[0097] Optionally, the expansion rate e1 of the first plane portion 10 is in the range of Specifically, the expansion rate e1 of the first plane portion 10 may be, but is not limited to, If the expansion rate of the first planar portion 10 is too low, the difference between its expansion rate and that of the bendable portion 30 is too large, which may cause the connection between the first planar portion 10 and the bendable portion 30 to be severely distorted, 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. During chemical strengthening, the first planar portion 10 and the bendable portion 30 are strengthened in the same system, and the strengthening depth of the bendable portion 30 is also deepened, so that the expansion rate of the bendable portion 30 is relatively large, which further widens the expansion rate difference between the bendable portion 30 and the first planar portion 10, and also causes the connection between the first planar portion 10 and the bendable portion 30 to be severely distorted, 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 between its expansion rate and that of the bendable portion 30 is too large, which may cause the connection between the second planar portion 50 and the bendable portion 30 to be severely distorted, 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. During chemical strengthening, the second planar portion 50 and the bendable portion 30 are strengthened in the same system, and the strengthening depth of the bendable portion 30 is also deepened, so that the expansion rate of the bendable portion 30 is relatively large, which further widens the expansion rate difference between the bendable portion 30 and the second planar portion 50, and also causes the connection between the second planar portion 50 and the bendable portion 30 to be severely distorted, 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 plane portion 10 and the second plane portion 50, or the reinforcement depth of the first plane portion 10 and the second plane portion 50 is insufficient, thereby reducing the mechanical strength of the first plane portion 10 and the second plane portion 50; if the expansion rate e3 of the bendable portion 30 is too high, the expansion rate difference between the first plane portion 10 and the second plane portion 50 and the bendable portion 30 is increased, thereby exacerbating the light and shadow distortion between the first plane portion 10 and the second plane portion 50 and the bendable portion 30.

[0100] Optionally, 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.

[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 the 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, so that the mechanical strength of the prepared glass cover plate 100 is too low. When applied to a flexible display screen, it cannot provide sufficient support and protection, and the anti-drop performance 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 prepared glass cover plate 100 along the thickness direction when the distance from the surface of the glass cover plate 100 is 3μm to 7μm will drop sharply, thereby making the protective effect of the compressive stress layer on microcracks worse, and it is 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 may 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 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 plane portion 10 or the second plane 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 small, the inhibitory effect of sodium ions on the entry of lithium ions into the glass substrate is too small, resulting in excessive content of lithium ions in the glass substrate and reduced mechanical strength. In addition, if the content of sodium nitrate is too small, the compressive stress of the prepared glass cover plate 100 will drop sharply when the distance from the surface of the glass cover plate 100 is 3μm to 7μm along the thickness direction, thereby making the protective effect of the compressive stress layer on microcracks worse, and it is 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.

[0103] Optionally, the molten salt comprises, by mass fraction, 94.5% to 97.8% potassium nitrate, 2% to 5% sodium nitrate and 0.2% to 0.5% 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 difference of the glass cover 100 is large, it is difficult for the surface compressive stress CS1 of the first planar portion 10 to be equal to the surface compressive stress CS3 of the bendable portion 30. 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, the light and shadow distortion phenomenon is increased, and the appearance effect of the glass cover 100 is affected.

[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 difference of the glass cover 100 is large, 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, the light and shadow distortion phenomenon is increased, and the appearance effect of the glass cover 100 is affected.

[0107] Please see again Figure 3Optionally, the first planar portion 10 includes a first compressive stress layer 12 (abbreviated as DOL), the second planar portion 50 includes a second compressive stress layer 52, and the bendable portion 30 includes a third compressive stress layer 32, and 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: 0.1μm≤DOL1-DOL3≤0.3μm; 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: 0.1μm≤DOL2-DOL3≤0.3μm.

[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 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 thickness DOL1 of the first compressive stress layer 12 differs too much from the thickness of the third compressive stress layer 32, the surface compressive stress of the first planar portion 10 and the bendable portion 30 differs too much, increasing the light and shadow distortion phenomenon of the bendable portion 30; if the thickness DOL1 of the first compressive stress layer 12 differs too little from the thickness of the third compressive stress layer 32, it is difficult to achieve in terms of technology, or only the glass cover plate 100 with similar thicknesses of 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 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 thickness DOL2 of the second compressive stress layer 52 differs too much from the thickness of the third compressive stress layer 32, the surface compressive stress of the second planar portion 50 and the bendable portion 30 differs too much, increasing the light and shadow distortion phenomenon of the bendable portion 30; if the thickness DOL2 of the second compressive stress layer 52 differs too little from the thickness of the third compressive stress layer 32, it is difficult to achieve in terms of technology, or only the glass cover plate 100 with similar thicknesses of the second planar portion 50 and the bendable portion 30 can be used, 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 of the above embodiment, please refer to the description of the corresponding parts of 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 method described in the following embodiment of the present application. In addition, it can also be prepared by other methods. The preparation method of the embodiment of the present application is only one or more preparation methods of the glass cover plate 100 of the present application, and should not be understood as a limitation on the glass cover plate 100 provided by the embodiment of the present application.

[0113] See also Figure 4 The present embodiment also 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, if Figure 5 As shown, the glass substrate 100a includes a first substrate portion 10a, a thinning portion 30a and a second substrate portion 50a which are connected in sequence. The thickness of the thinning portion 30a is smaller than that of the first substrate portion 10a and smaller than that of the second substrate portion 50a.

[0117] S202, placing the glass substrate 100a in a molten salt for chemical strengthening to obtain the glass cover plate 100, wherein 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, 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≤50MPa, 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≤50MPa.

[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, which will not be repeated here.

[0120] The glass cover plate 100 prepared by the method for preparing the glass cover plate 100 of the embodiment of the present application includes a first plane portion 10, a bendable portion 30 and a second plane portion 50 connected in sequence, the thickness of the bendable portion 30 is less than the thickness of the first plane portion 10 and less than the thickness of the second plane portion 50, the difference between the surface compressive stress of the first plane 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 plane portion 50 and the surface compressive stress of the bendable portion 30 is within a range of 50 MPa, so that the difference in surface compressive stress between the first plane portion 10 and the bendable portion 30 of the glass cover plate 100 and between the second plane portion 50 and the bendable portion 30 is small, so that the glass cover plate 100 does not have obvious light and shadow distortion phenomenon and has a better appearance effect.

[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 on the surface of the glass substrate 100a;

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

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

[0125] 4) The tempering fixture with 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, a chemically strengthened salt is added to a molten salt furnace to melt and form a 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 molten salt furnace for chemical strengthening, and the chemical strengthening time ranges from 10 min to 30 min to obtain a 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 of potassium ions and sodium ions is too fast, and the expansion rate of each part of the glass substrate 100a is too large, so that the difference in expansion rate between the first plane portion 10 and the bendable portion 30, and between the second plane portion 50 and the bendable portion 30 increases, and the difference in compressive stress between the first plane portion 10 and the bendable portion 30, and between the second plane portion 50 and the bendable portion 30 also increases, so that the manufactured glass cover plate 100 is prone to distortion and deformation, and the light and shadow distortion phenomenon of the glass cover plate 100 is increased; when the temperature of the molten salt is too low, the strengthening depth of the glass cover plate 100 is insufficient, the mechanical properties are low, and the requirements are not met. Compared with the existing chemical strengthening, the temperature of the chemical strengthening of the present application is lower, which can better avoid the excessively fast ion replacement speed during chemical strengthening, resulting 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, thereby better avoiding the light and shadow distortion phenomenon of the manufactured glass cover 100.

[0130] Specifically, the chemical strengthening time may be, but is not limited to, 10 min, 12 min, 15 min, 18 min, 20 min, 22 min, 25 min, 28 min, 30 min, etc. When the chemical strengthening time is too long, the exchange amount of potassium ions and sodium ions is too much, the strengthening depth of the glass substrate 100 a is too deep, and the expansion rate of each part of the glass substrate 100 a is too large, so that the difference in expansion rate between the first plane portion 10 and the bendable portion 30, and between the second plane portion 50 and the bendable portion 30 increases, and the difference in compressive stress between the first plane portion 10 and the bendable portion 30, and between the second plane portion 50 and the bendable portion 30 also increases, so that the manufactured glass cover plate 100 is prone to distortion and deformation, and the light and shadow distortion phenomenon of the glass cover plate 100 is increased; 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 the requirements are not met.

[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 minutes to 5 minutes, so that the molten salt on the surface of the glass cover plate 100 drips into the furnace body, reducing the amount of molten salt taken 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 min to 6 min, specifically, it can be but not limited to 4 min, 5 min, 6 min, etc.

[0134] After chemical strengthening, the glass substrate 100a may have some micro cracks on its surface. The presence of micro cracks 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 micro cracks 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 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.

[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 the 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, so that the mechanical strength of the prepared glass cover plate 100 is too low. When applied to a flexible display screen, it cannot provide sufficient support and protection, and the anti-drop performance 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 prepared glass cover plate 100 along the thickness direction when the distance from the surface of the glass cover plate 100 is 3μm to 7μm will drop sharply, thereby making the protective effect of the compressive stress layer on microcracks worse, and it is 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 may 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 small, the sodium ions will be more likely to enter the glass substrate 100a. The inhibitory effect of lithium ions entering the glass substrate 100a is too small, so that the content of lithium ions in the glass substrate 100a is too high and the mechanical strength is reduced. In addition, if the content of sodium nitrate is too low, the compressive stress of the manufactured glass cover plate 100 along the thickness direction when the distance from the surface of the glass cover plate 100 is 3μm to 7μm will drop sharply, thereby making the protective effect of the compressive stress layer on microcracks worse, and it is difficult to play a role in preventing 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.

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

[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) A glass substrate 100a is provided; the glass substrate 100a includes a first substrate portion 10a, a thinning portion 30a and a second substrate portion 50a which are 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 minimum thickness of the thinning portion 30a is 30 μm.

[0144] 2) The glass substrate 100a 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 10a forms the first planar portion 10, the thinned portion 30a forms the bendable portion 30, and the second substrate portion 50a 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), the thickness or depth (DOL) of the compressive stress layer and the expansion rate (e) of the first plane portion 10, the second plane portion 50 and the bendable portion 30 of the glass cover plate 100 of each embodiment and the comparative example were measured respectively, and the test results are shown in Table 1. The surface compressive stress and the depth of the compressive stress layer were measured using a FSM-6000k surface stress tester, and the expansion rate was calculated using a two-dimensional length and width measurement.

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

[0148]

[0149] It can be seen from the test results of Example 1 and Comparative Example 2 that when chemical strengthening is performed, adding lithium nitrate to the molten salt can greatly reduce the expansion rate of the glass cover plate 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, so that the light and shadow distortion phenomenon caused by the distortion deformation between the bendable portion 30 and the first plane portion 10 and the bendable portion 30 and the second plane portion 50 can be better improved. From the test data of Example 1 to Example 3, Comparative Example 2 and Comparative Example 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 plate 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 large, the surface compressive stress of the obtained glass cover plate 100 is too low, the mechanical strength is too low, and it cannot meet the application requirements.

[0150] It can be seen from the test data of Example 1 and Comparative Example 1 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 a high mechanical strength, and the surface compressive stress difference and expansion rate difference between the bendable portion 30 and the first plane portion 10 and between the bendable portion 30 and the second plane 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 plane portion 10 and between the bendable portion 30 and the second plane portion 50 of the glass cover plate 100, and better improving the light and shadow distortion phenomenon caused by the distortion and deformation between the bendable portion 30 and the first plane portion 10 and between the bendable portion 30 and the second plane portion 50 of the glass cover plate 100.

[0151] It can be seen from the test data of Example 2, Example 4, Example 5, Comparative Example 4 and Comparative Example 5 that when chemical strengthening is performed, sodium nitrate is added to the molten salt, so that the chemically strengthened glass cover plate 100 has a higher surface compressive stress, thereby having a higher mechanical strength, and can reduce the expansion rate difference and surface stress difference between the bendable portion 30 and the first plane portion 10 and between the bendable portion 30 and the second plane portion 50, and can better improve the light and shadow distortion phenomenon caused by the distortion deformation between the bendable portion 30 and the first plane portion 10 and between the bendable portion 30 and the second plane portion 50 of the strengthened glass cover plate 100. It can be seen from the test results of Comparative Example 5 that when the content of sodium nitrate in the molten salt is too high, the surface compressive stress of the glass cover plate 100 will be too low, and the mechanical strength will be too low, which cannot meet the application requirements.

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

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

[0154]

[0155] It can be seen from the test results in Table 2 that when hydrofluoric acid is used for etching, the surface compressive stress of the obtained glass cover plate 100 will be reduced, but still maintained at a relatively high surface compressive stress. However, after etching away part of the compressive stress layer, the micro cracks 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 also Figure 6 The embodiment of the present application further 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 plate 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 can be understood that the flexible display screen 200 in this embodiment is only one form of the flexible display screen 200 applied to the glass cover plate 100, and should not be understood as a limitation on the flexible display screen 200 provided in this application, nor should it be understood as a limitation on the glass cover plate 100 provided in each embodiment of this application. For a detailed description of the glass cover plate 100, please refer to the description of the corresponding part of the above embodiment, which will not be repeated here.

[0161] See also Figures 7 to 9 The 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, wherein the foldable mechanism 310 is used to carry 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 may be, but is not limited to, a portable foldable electronic device 300 with a variable display screen size such as a mobile phone, a tablet computer, an e-reader, and a laptop computer. It can be understood that the foldable electronic device 300 in this embodiment is only a form of the foldable electronic device 300 applied to the flexible display screen 200, and should not be understood as a limitation on the foldable electronic device 300 provided in the present application, nor should it be understood as a limitation on the flexible display screen 200 provided in each embodiment of the present application. For a detailed description of the flexible display screen 200, please refer to the description of the corresponding part 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 Fig.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 are used 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 overlaps with the second carrier 315 and drives 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, the processor 330 includes one or more general-purpose processors, wherein the 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, etc. The processor 330 is used to execute various types of digital storage instructions, such as software or firmware programs stored in a 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 for controlling the flexible display screen 200, display content of the flexible display screen 200, and the like.

[0168] Optionally, the memory 350 may include a volatile memory, such as a random access memory (RAM); the memory 350 may also include a non-volatile memory (NVM), such as a read-only memory (ROM), a flash memory (FM), a hard disk (DOLDD) or a solid-state drive (SSD). The memory 350 may also include a combination of the above-mentioned 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, and the camera module 370 is carried by the foldable mechanism 310. The camera module 370 is electrically connected to the processor 330, and is used 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 "embodiment" and "implementation method" in this application means that the specific features, structures or characteristics described in conjunction with the embodiment 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 also 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, provided that there is no contradiction between them.

[0172] Finally, it should be noted that the above implementation modes are only used to illustrate the technical solution of the present application and are not intended to limit it. Although the present application has been described in detail with reference to the above preferred implementation modes, a person of ordinary skill in the art should understand that the technical solution of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution 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, the thickness of the bendable portion is less than the thickness of the first planar portion, 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.

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

3. The glass cover plate according to claim 1, 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.

4. The glass cover plate according to claim 3, characterized in that: 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 plate according to any one of claims 1 to 4, characterized in that: The glass cover plate is a glass cover plate formed by chemically strengthening a glass substrate with molten salt, wherein the molten salt comprises 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.

6. The glass cover plate according to claim 5, characterized in that: Along the arrangement direction of the first planar portion, the bendable portion and the second planar portion, before and after the chemical strengthening, the ratio of the expansion rate e3 of the bendable portion to the expansion rate e1 of the first planar portion is in the range of: 1.01≤e3 / e1≤1.2, and the ratio of the expansion rate e3 of the bendable portion to the expansion rate e2 of the second planar portion is in the range of: 1.01≤e3 / e2≤1.

2.

7. A glass cover plate, characterized in that: The glass cover plate includes a first plane portion, a bendable portion and a second plane portion which are connected in sequence, the thickness of the bendable portion is less than the thickness of the first plane portion, the thickness of the bendable portion is less than the thickness of the second plane portion, the glass cover plate is obtained by chemically strengthening a glass substrate with molten salt, the molten salt includes potassium nitrate, sodium nitrate and lithium nitrate; along the arrangement direction of the first plane portion, the bendable portion and the second plane 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 plane 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 plane portion is: 1.01≤e3 / e2≤1.

2.

8. The glass cover plate according to claim 7, characterized in that: 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: And 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 plate according to claim 7, characterized in that: 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 plate according to claim 9, characterized in that: 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 plate according to claim 7, characterized in that: 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 plate 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, wherein 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, 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.

14. The glass cover plate according to claim 13, characterized in that: 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.

15. The glass cover plate according to claim 13, characterized in that: 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 glass cover plate according to any one of claims 13 to 15, characterized in that: The step of placing the glass substrate in a 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 is used to carry the flexible display screen and drive the flexible display screen to be folded or flattened, wherein the glass cover plate of the flexible display screen is farther 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.

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