cover window

Abstract

Cover windows are provided. A cover window includes a folded portion and an unfolded portion, and the folded portion includes an inner surface that is compressed when folded and an outer surface that is stretched when folded, the folded portion includes a first layer adjacent to the outer surface, a second layer adjacent to the inner surface, and a third layer between the first layer and the second layer, the folded portion and the unfolded portion include at least one metal ion, a concentration of the metal ion included in the second layer is higher than a concentration of the metal ion included in the first layer, and the first layer includes a plurality of depletion regions.

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2021-0044832, filed on April 6, 2021, with the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The embodiments of this disclosure relate to a cover window, a method of manufacturing a cover window, and a display device including a cover window. Background Technology

[0004] Display devices (such as organic light-emitting displays and liquid crystal displays) include display panels manufactured by forming multiple layers and multiple elements on a substrate. Recently, flexible display panels and flexible display devices including such flexible display panels have been developed.

[0005] Based on their application or shape, flexible display devices can be classified into bendable display devices, foldable display devices, and rollable display devices. Among them, foldable display devices can unfold and fold the display panel to show images, just like a book cover.

[0006] The advantage of foldable display devices is that they can be folded into a compact and portable form, and can be unfolded to perform wide-screen functions when in use.

[0007] Cover windows used in foldable display devices comprise thin glass that is to be folded, and when an impact is applied, such as when an external object (such as a pen) falls on the thin cover window, the risk of damage or destruction of the cover window may increase. Summary of the Invention

[0008] According to one or more embodiments of this disclosure, by increasing the degree of freedom for the thickness of the cover window in a foldable display device, the elongation of the cover window is improved while the impact strength is increased.

[0009] According to an embodiment of the present disclosure, the cover window includes a folded portion and a non-folded portion, wherein the folded portion includes an inner surface that is compressed when folded and an outer surface that is stretched when folded, the folded portion includes a first layer adjacent to the outer surface, a second layer adjacent to the inner surface, and a third layer between the first layer and the second layer, the folded portion and the non-folded portion include at least one metal ion, the concentration of the metal ion included in the second layer is higher than the concentration of the metal ion included in the first layer, and the first layer includes a plurality of depletion zones.

[0010] The second layer may not include depletion regions, or it may include depletion regions with concentrations lower than those included in the first layer.

[0011] The concentration of metal ions included in the second layer can be higher than or equal to the concentration of metal ions included in the third layer.

[0012] The concentration of metal ions included in the folded portion can be the same as the concentration of metal ions included in the third layer.

[0013] Metal ions can include sodium ions (Na+) + ) and potassium ions (K + At least one of the following.

[0014] The modulus of the first layer can be lower than that of the second layer.

[0015] The modulus of the first layer can be 3% to 20% lower than that of the non-folded portion or the third layer.

[0016] The first layer may include a surface layer positioned adjacent to the surface of the first layer that is not adjacent to the third layer, and the surface layer may have Si-OH bonds.

[0017] The toughness of the first layer can be greater than that of the second or third layer.

[0018] The thickness of at least one of the first and second layers can be between 1 micrometer and 6 micrometers.

[0019] The display device according to the embodiment includes a cover window and a display panel in contact with the cover window.

[0020] The method for manufacturing a cover window according to an embodiment includes: raising the atmosphere temperature of a chamber in which an original plate for positioning the cover window is placed; positioning a cathode and an anode opposite to opposing surfaces of a portion of the original plate for the cover window, and applying a voltage for the first time; and after a period of time following the first application of voltage, forming a cover window including a non-folded portion and a folded portion corresponding to the portion while the voltage is applied by lowering the atmosphere temperature of the chamber.

[0021] The folded portion may include an inner surface that is compressed during folding and an outer surface that is stretched during folding. The folded portion may include a first layer adjacent to the outer surface, a second layer adjacent to the inner surface, and a third layer between the first and second layers. The folded and non-folded portions may include at least one metal ion. The concentration of the metal ion included in the second layer may be higher than the concentration of the metal ion included in the first layer. The first layer may include multiple depletion regions.

[0022] Multiple depletion zones can be generated during the formation of the cover window.

[0023] The second layer may not include depletion regions, or it may include depletion regions with concentrations lower than those included in the first layer.

[0024] During the formation of the cover window, metal ions can move from the first layer to the second layer.

[0025] The potential difference applied between the cathode and anode can be from 500V to 2000V.

[0026] The duration for which a potential difference is applied between the cathode and the anode can range from 10 minutes to 30 minutes.

[0027] The method may also include introducing a reactive gas, including hydrogen (H2), into the chamber.

[0028] According to one or more aspects of the embodiments, the degree of freedom of the thickness of the cover window in a foldable display device can be increased to increase impact strength while improving the elongation of the cover window. Attached Figure Description

[0029] Figure 1 This is a side view of a display device in a folded state according to an embodiment;

[0030] Figure 2 This is a schematic perspective view of a display device in an unfolded state according to an embodiment;

[0031] Figure 3 This is a side view of a display device in a folded state according to an embodiment;

[0032] Figure 4 This is a top plan view showing the cover window of the display device according to an embodiment, which shows the structure when not folded;

[0033] Figure 5 This is a side view showing the cover window of the display device according to an embodiment, which shows the structure when folded;

[0034] Figure 6 This is a view showing multiple layers divided according to the characteristics of the cross-section of the folded portion of the cover window, based on an embodiment.

[0035] Figure 7 This is a view showing a method for manufacturing a cover window according to an embodiment;

[0036] Figure 8 yes Figure 7 An enlarged view of the area “BB” shown, which conceptually illustrates the movement of ions occurring within the folded portion of the cover window;

[0037] Figure 9 It is shown in Figure 7 The manufacturing process shown includes views of multiple layers of different features in the cover window; and

[0038] Figure 10This is a flowchart of a method for manufacturing a cover window according to an embodiment.

[0039] Symbol description

[0040] 31: Cathode 32: Anode

[0041] 100: Cover window 110: First floor

[0042] 111: Surface layer; 120: Second layer

[0043] 130: Third layer; 200: Display panel

[0044] A: Non-folded part B: Folded part

[0045] DPR1, DPR2: Depletion regions IA, IB: Ions Detailed Implementation

[0046] The invention will be described more fully herein with reference to the accompanying drawings, in which some exemplary embodiments of the invention are illustrated. As those skilled in the art will recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the invention.

[0047] The accompanying drawings and descriptions are intended to be illustrative rather than restrictive. Throughout the specification, the same reference numerals denote the same elements.

[0048] Furthermore, for better understanding and ease of description, the dimensions and thicknesses of the constituent components shown in the accompanying drawings may be given arbitrarily, and the invention is not limited to the dimensions and thicknesses shown. In the drawings, the thicknesses of layers, films, panels, areas, etc., may be exaggerated for clarity.

[0049] It should be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on that other element, or there may be one or more intermediate elements. Conversely, when an element is referred to as being "directly on" another element, there are no intermediate elements. Furthermore, in the specification, the terms "on" or "above" mean located on or below a part of an object, and do not necessarily mean located on the upper side of a part of an object based on the direction of gravity.

[0050] Furthermore, unless explicitly stated otherwise, the word “comprise” and variations such as “comprises” or “comprising” will be understood to imply inclusion of the stated element, but not exclusion of any other element.

[0051] Furthermore, in this specification, the phrase "on a flat surface" means when viewing a portion of an object from above, and the phrase "in a cross section" means when viewing a cross section obtained by vertically cutting a portion of an object from the side.

[0052] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It should be further understood that terms, such as those defined in commonly used dictionaries, shall be interpreted as having a meaning consistent with their meaning in the context of the relevant field, and shall not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0053] The following description, with reference to the accompanying drawings, describes a cover window and a display device including the cover window according to an embodiment.

[0054] Figure 1 This is a side view of the display device in a folded state according to an embodiment. Figure 2 This is a schematic perspective view of a display device in its unfolded state according to an embodiment, and Figure 3 This is a side view of a display device in a folded state according to an embodiment.

[0055] refer to Figure 1 The display device according to the embodiment can be a foldable display device. For example... Figure 1 As shown, the display device according to the embodiment may include a display panel 200 and a cover window 100 disposed on the surface of the display panel 200.

[0056] refer to Figure 2 The display panel 200 may include a plurality of pixels PX capable of displaying images. The display panel 200 may be a light-emitting display panel in which the pixels PX include light-emitting elements, or a liquid crystal panel in which the pixels PX include liquid crystal capacitors.

[0057] Among the surfaces of the display panel 200, the surface on which the cover window 100 is positioned can be the display surface on which the image is displayed. Figure 2 The arrow shown indicates the direction of image display.

[0058] refer to Figure 1 According to the embodiment, the display device can be folded in the direction where the cover window 100 faces itself. That is, when the display device is folded, the display surface may not be exposed, and when the display device is unfolded, the display surface may be exposed.

[0059] refer to Figure 3According to another embodiment, the display device can be folded in the direction facing itself from the display panel 200. That is, when the display device is folded, the display surface can be exposed, and the display surface can also be exposed when the display device is unfolded.

[0060] Figure 4 This is a top plan view showing the cover window 100 of the display device according to an embodiment, illustrating its structure when folded; and Figure 5 This is a side view showing the cover window 100 of the display device according to an embodiment, which shows the structure when folded about the first direction DR1.

[0061] refer to Figure 4 The cover window 100 according to the embodiment includes a folded portion B that bends when folded and a non-folded portion A that does not bend when folded. The cover window 100 can be folded along a second direction DR2 perpendicular to the first direction DR1.

[0062] refer to Figure 4 and Figure 5 When the radius of curvature of the cover window 100 in the folded state is R, the length d of the folded part B can be πR.

[0063] In the implementation, the radius of curvature R can be approximately 1 mm to approximately 2 mm, but is not limited to this.

[0064] Since the non-folded portion A is a non-curved portion, it can also be referred to as a flat portion.

[0065] exist Figure 5 In this design, when the cover window 100 is folded, the surfaces located on the inside and facing each other are defined as the inner surface IS, and the surfaces located on the outside are defined as the outer surface OS. That is, the surface to be compressed during folding is the inner surface IS of the cover window 100, and the surface to be stretched during folding is the outer surface OS of the cover window 100.

[0066] The above description Figure 1 In the embodiment shown, when the cover window 100 is combined with the display panel 200, the image is displayed through the inner surface IS of the cover window 100, and the cover window 100 can contact the display panel 200 on its outer surface OS. That is, the inner surface IS of the cover window 100 can be a display surface, and the outer surface OS can be a non-display surface.

[0067] The above description Figure 3In the embodiment shown, when the cover window 100 is combined with the display panel 200, the image is displayed through the outer surface OS of the cover window 100, and the cover window 100 can contact the display panel 200 on its inner surface IS. That is, the outer surface OS of the cover window 100 can be a display surface, and the inner surface IS can be a non-display surface.

[0068] The cover window 100 according to an embodiment includes glass. In this embodiment, the glass included in the cover window 100 may be a silicate-type glass. Additionally, the cover window 100 may include ions of alkali metals or alkaline earth metals, such as Na, K, Li, Mg, Ca, Sr, Ba, or Al ions. Alkali metal or alkaline earth metal ions can generate non-bridging oxygen (NBO).

[0069] The folding portion B of the cover window 100 has features different from those of the non-folding portion A because, during the manufacturing process of the cover window 100, the non-folding portion A does not undergo the treatment that the folding portion B undergoes. This treatment could be thermal polarization. (Reference) Figure 6 as well as Figure 5 Describe the construction of the folded part B.

[0070] Figure 6 This is a view showing multiple layers divided according to the characteristics of the cross-section of the folded portion B of the cover window 100 according to an embodiment.

[0071] refer to Figure 5 and Figure 6 The folded portion B includes a first layer 110 and a second layer 120 with different features. A third layer 130 may be positioned between the first layer 110 and the second layer 120.

[0072] The first layer 110 forms an ion depletion layer comprising multiple pores or depletion regions DPR1 and DPR2, through which alkali metal or alkaline earth metal ions that generate NBO escape. Depletion regions DPR1 and DPR2 can be sites or cavities where at least one ion of the alkali metal and alkaline earth metal has escaped. In the following description, when referred to as an ion, it means an alkali metal or alkaline earth metal ion included in the cover window 100.

[0073] Figure 6 As an example, depletion regions DPR1 and DPR2 are shown due to two ions. The first depletion region DPR1 can be the first ion IA (e.g., sodium ion (Na+)). + The second depletion region DPR2 can be a second ion IB (e.g., potassium ion (K)) that has escaped from its ion site, and the second depletion region DPR2 can be a second ion IB (e.g., potassium ion (K)). + It has already escaped from its elusive site.

[0074] Sodium ions (Na) +) and potassium ions (K + Some items may not be retained in the first layer 110, but some may be retained in the second layer 120 and the third layer 130.

[0075] In an implementation, the thickness d1 of the first layer 110 can be from about 1 micrometer to about 6 micrometers, but is not limited thereto.

[0076] Compared to the first layer 110, the second layer 120 has a higher concentration of at least one ion. Here, concentration can refer to the number of ions per unit volume. According to an embodiment, such as... Figure 6 As shown, compared to the first layer 110, the second layer 120 can have a higher concentration of at least two ions, namely, a first ion IA and a second ion IB. The first ion IA can be, for example, sodium ions (Na+). + And the second ion IB can be, for example, a potassium ion (K). + ).

[0077] Compared to the first layer 110, the third layer 130 also has a higher concentration of at least one ion. According to an embodiment, the third layer 130 may have a higher concentration of at least two ions than the first layer 110, namely, a first ion IA and a second ion IB. The first ion IA may be, for example, sodium ions (Na+). + And the second ion IB can be, for example, a potassium ion (K). + ).

[0078] The concentration of the first ion IA in the second layer 120 can be higher than or similar to (e.g., equal to) that of other ions.

[0079] The concentration of the first ion IA in the third layer 130. Similarly, the concentration of the second ion IB in the second layer 120 can be higher than or similar to (e.g., equal to) the concentration of the second ion IB in the third layer 130. As an example, Figure 6 The diagram shows a case where the concentrations of the first ion IA and the second ion IB in the second layer 120 are higher than those in the third layer 130.

[0080] Depletion regions DPR1 and DPR2 may not exist in the third layer 130, or some depletion regions DPR1 and DPR2 may be located in portions of the third layer 130 adjacent to the first layer 110. Although the third layer 130 may include depletion regions DPR1 and DPR2, the concentrations of depletion regions DPR1 and DPR2 in the third layer 130 are lower than the concentrations of depletion regions DPR1 and DPR2 in the first layer 110.

[0081] In the second layer 120, depletion regions DPR1 and DPR2 may not exist. However, even if the second layer 120 includes depletion regions DPR1 and DPR2, the concentrations of depletion regions DPR1 and DPR2 in the second layer 120 are lower than the concentrations of depletion regions DPR1 and DPR2 in the first layer 110.

[0082] In an implementation, the thickness d2 of the second layer 120 can be from about 1 micrometer to about 6 micrometers, but is not limited thereto.

[0083] In this implementation, the thickness d3 of the cover window 100 can be greater than approximately 30 micrometers.

[0084] In this embodiment, the composition and concentration of ions and depletion regions in the non-folded portion A of the cover window 100 may be the same as or substantially the same as the composition and concentration of ions and depletion regions in the third layer 130 of the folded portion B. In this specification, "some features are the same or substantially the same" may mean a difference of less than 2%.

[0085] The first layer 110 is the layer closest to the outer surface OS of the cover window 100 and receives the maximum tensile stress due to the largest amount of deformation when the cover window 100 is folded. According to this embodiment, the first layer 110, including multiple depletion regions DPR1 and DPR2, forms a loose structure through the depletion regions DPR1 and DPR2, such that the modulus (more specifically, the tensile modulus) of the first layer 110 is lower than that of the second layer 120 and the third layer 130. Therefore, the tensile strength of the folded portion B of the cover window 100 can be significantly improved.

[0086] Therefore, it is not necessary to reduce the thickness d3 of the cover window 100 for ease of folding, and thus, the degree of freedom in the thickness of the cover window 100 can be increased. That is, since the thickness d3 of the cover window 100 can be increased without reducing the tensile strength of the cover window 100, the impact strength of the cover window 100 can be improved.

[0087] Furthermore, unlike existing technologies, there is no need to process or pattern the shape of the cover window 100 to facilitate the folding of the folding portion B. Therefore, visual recognition of the portion of the display panel 200 corresponding to the folding portion B can be prevented or substantially prevented.

[0088] In an implementation, the modulus of the first layer 110 may be, for example, about 3% to about 20% lower than the modulus of the third layer 130 or the non-folded portion A.

[0089] In an implementation, the modulus of the second layer 120 may be higher than or similar to that of the third layer 130.

[0090] Due to the influence of multiple depletion regions DPR1 and DPR2, the hardness of the first layer 110 can be lower than that of the second layer 120 and the third layer 130. In an embodiment, the hardness of the second layer 120 can be higher than or equivalent to that of the third layer 130.

[0091] refer to Figure 6 The first layer 110 may further include a surface layer 111 located adjacent to a surface of the first layer 110 that is not adjacent to the third layer 130. In embodiments, the surface layer 111 may have bonds of a different composition than the rest of the first layer 110. This can vary depending on the reactive gas used in the manufacturing process of the cover window 100, and for example, the Si-O bonds of the first layer 110 may react with a reactive gas including hydrogen (H2) to form the surface layer 111. For example, the surface layer 111 may include more Si-OH bonds than the rest of the first layer 110.

[0092] Through the surface layer 111 including Si-OH bonds, the toughness of the first layer 110 can be greater than that of the second layer 120 or the third layer 130.

[0093] In an implementation, the surface layer 111 may occupy only a portion of the surface of the first layer 110, or it may occupy the majority of the first layer 110.

[0094] Next, a method for manufacturing the cover window 100 according to an embodiment will be described.

[0095] Figure 7 This is a view illustrating a method of manufacturing the cover window 100 according to an embodiment; and Figure 8 yes Figure 7 An enlarged view of the area “BB” shown conceptually illustrates the movement of ions occurring within the folded portion B of the cover window 100. Figure 9 It is shown in Figure 7 The manufacturing method shown includes a view of multiple layers of different features in the cover window 100 after the process; and Figure 10 This is a flowchart of a method for manufacturing the cover window 100 according to an embodiment.

[0096] The manufacturing process of the cover window 100 according to this embodiment is a thermal polarization process limited to a portion of the cover window 100 (i.e., the folding portion B).

[0097] First, refer to Figure 7 Before processing, the original panel of the cover window 100 is positioned in chamber 10, and the atmosphere temperature of chamber 10 is increased to approximately 200°C to approximately 300°C. At this time, the atmosphere temperature is set to be lower than the temperature at which the glass begins to deform (i.e., the strain point (approximately 500°C to approximately 600°C)).

[0098] Under conditions of increased ambient temperature, cathode 31 and anode 32 are positioned on opposite sides of the portion corresponding to the folded portion B of the cover window 100, defined as the original plate, and a potential difference is generated by applying a voltage. At this time, cathode 31 is positioned on the inner surface IS side of the cover window 100, and anode 32 is positioned on the outer surface OS side of the cover window 100. The distance d4 between cathode 31 and cover window 100 is greater than 0 mm and can be, for example, approximately 1 mm. Similarly, the distance d5 between anode 32 and cover window 100 is greater than 0 mm and can be, for example, approximately 1 mm.

[0099] The potential difference between the cathode 31 and the anode 32 can be, for example, approximately 500V to approximately 2000V. Under conditions of increased atmospheric temperature, the time for applying voltage between the cathode 31 and the anode 32 can be, for example, approximately 10 minutes to approximately 30 minutes.

[0100] refer to Figure 8 The movement of ions IA and IB occurs within the cover window 100 located between the cathode 31 and the anode 32. Specifically, alkali metal or alkaline earth metal ions IA and IB (such as Na+) that produce non-bridging oxygen (NBO) are generated. + and K + The ions move from the anode 32 side to the cathode 31 side. Some of the ions IA and IB that have migrated toward the inner surface IS of the cover window 100 can escape into the outside air or remain on the surface of the inner surface IS. As described above, because the gap d4 between the cathode 31 and the cover window 100 is greater than 0 mm, the ions IA and IB that have moved toward the inner surface IS can easily escape into the air.

[0101] As a result, Figure 9 As shown, the concentrations of ions IA and IB are high in certain portions of the inner surface IS side of the cover window 100, resulting in the formation of a second layer 120. The concentrations of ions IA and IB in the second layer 120 are higher than or substantially equal to the concentrations of ions IA and IB in the third layer 130, which serves as an intermediate layer. Additionally, a first layer 110 is formed in certain portions of the outer surface OS side of the cover window 100. The first layer 110 is an ion-depleted layer comprising multiple depletion regions DPR1 and DPR2.

[0102] In one embodiment, the surface characteristics of the first layer 110 of the folded portion B can be altered by introducing a reactive gas into the chamber 10 while a voltage is applied between the cathode 31 and the anode 32, thus forming the surface layer 111 described above. Specifically, the Si-OH bonds in the surface layer 111 can be formed by injecting a gas (e.g., hydrogen or water vapor) that can react with the Si-O bonds inside the glass. Therefore, the toughness of the first layer 110 can be increased.

[0103] On the other hand, the degree of reduction in the modulus of the first layer 110 can vary depending on the type and concentration of the reacting gases.

[0104] Next, the temperature of chamber 10 is reduced while maintaining the potential difference between cathode 31 and anode 32. For example, the temperature can be reduced to approximately 50°C. Then, the moving ions IA and IB are fixed inside the cover window 100, and the changing characteristics of the cover window 100 can be fixed. That is, a first layer 110 and a second layer 120 of the folded portion B of the cover window 100 can be formed.

[0105] Although the modulus of the first layer 110 formed by the thermal polarization process is significantly lower than that before the process, the modulus of the second layer 120 can be maintained or slightly increased. In addition, due to the influence of multiple depletion regions DPR1 and DPR2, the hardness of the first layer 110 can be lower than that before the process, while the hardness of the second layer 120 can be increased.

[0106] like Figure 10 The sequence of these thermal polarization processes is summarized in the diagram. First, a voltage is applied between the anode and cathode while raising the temperature of the atmosphere in the chamber (S10). Then, ions in the cover window move towards the cathode (S20). Subsequently, while maintaining the voltage applied to the anode and cathode, the temperature of the chamber is lowered to fix the ion positions (S30).

[0107] Although the invention has been described in conjunction with what are now considered to be some practical embodiments, it should be understood that the invention is not limited to the disclosed embodiments. Rather, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A window cover comprising a folding portion and a non-folding portion, in, The folded portion includes an inner surface that is compressed during folding and an outer surface that is stretched during folding. The folded portion includes a first layer adjacent to the outer surface, a second layer adjacent to the inner surface, and a third layer between the first layer and the second layer. The folded portion and the unfolded portion comprise at least one metal ion. The concentration of the metal ions included in the second layer is higher than the concentration of the metal ions included in the first layer, and The first layer includes multiple depletion regions.

2. The window cover according to claim 1, wherein, The second layer does not include depletion regions, or includes depletion regions with a concentration lower than that of the plurality of depletion regions included in the first layer.

3. The window cover according to claim 2, wherein, The concentration of the metal ions included in the second layer is higher than or equal to the concentration of the metal ions included in the third layer.

4. The window cover according to claim 1, wherein, The concentration of the metal ions included in the non-folded portion is the same as the concentration of the metal ions included in the third layer.

5. The window cover according to claim 1, wherein, The metal ions include at least one of sodium ions and potassium ions.

6. The window cover according to claim 1, wherein, The modulus of the first layer is lower than that of the second layer.

7. The window cover according to claim 6, wherein, The modulus of the first layer is 3% to 20% lower than that of the non-folded portion or the third layer.

8. The window cover according to claim 1, wherein, The first layer includes a surface layer adjacent to the surface of the first layer that is not adjacent to the third layer, and The surface layer includes Si-OH bonds.

9. The window cover according to claim 8, wherein, The toughness of the first layer is greater than that of the second layer or the third layer.

10. The cover window according to claim 1, wherein, The thickness of at least one of the first layer and the second layer is between 1 micrometer and 6 micrometers.

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