Cover window and foldable display device including the same

Abstract

A cover window is provided. The cover window includes a substrate layer. The cover window also includes a hard coat layer on the substrate layer. The cover window also includes a protective film disposed on the hard coat layer and including a base film and a plurality of protrusions protruding from the base film. The cover window also includes an adhesive layer disposed on surfaces of the plurality of protrusions and adhering the hard coat layer and the protective film. The protective film includes a first region and second regions disposed on both sides of the first region. The plurality of protrusions are disposed in the first region. The plurality of protrusions have a shape in which protrusions disposed on one side and protrusions disposed on the other side with respect to a center line of the first region are symmetric to each other.

Description

[0001] Cross-references to related applications

[0002] This application is a divisional application of the invention patent application with application number 202011413319.9.

[0003] This application claims priority to Korean Patent Application No. 10-2019-0177976, filed on December 30, 2019, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. Technical Field

[0004] This disclosure relates to a cover window and a foldable display device including the cover window, and more specifically, to a cover window that can be reprocessed and has excellent folding characteristics and a foldable display device including the cover window. Background Technology

[0005] Display devices used in computer monitors, TVs, mobile phones, etc. include self-emissive organic light-emitting displays (OLEDs) and liquid crystal displays (LCDs) that require a separate light source.

[0006] Such display devices are being used in an increasing number of fields, including not only computer monitors and TVs, but also personal mobile devices. Therefore, there is research on display devices that have reduced size and weight while having a wide display area.

[0007] Recently, foldable display devices, which can be freely folded and unfolded by forming light-emitting elements, circuits, etc. on a flexible substrate made of flexible materials such as plastic, have attracted attention as the next generation of display devices. Summary of the Invention

[0008] One objective of this disclosure is to provide a reworkable cover window and a foldable display device including the cover window.

[0009] Another objective of this disclosure is to provide a cover window that can be reprocessed and allows for improved folding characteristics, and a foldable display device including the cover window.

[0010] The purpose of this disclosure is not limited to the above-mentioned purposes, and other purposes not mentioned above will be clearly understood by those skilled in the art from the following description.

[0011] According to one aspect of this disclosure, a cover window is provided. The cover window includes a substrate layer. The cover window also includes a hard coating layer on the substrate layer. The cover window also includes a protective film disposed on the hard coating layer and including a base film and a plurality of protrusions projecting from the base film. The cover window also includes an adhesive layer disposed on the surfaces of the plurality of protrusions and bonding the hard coating layer and the protective film. The protective film includes a first region and a second region disposed on both sides of the first region. The plurality of protrusions are disposed in the first region. The plurality of protrusions have a shape in which the protrusions disposed on one side relative to the centerline of the first region and the protrusions disposed on the other side are symmetrical to each other.

[0012] According to another aspect of this disclosure, a foldable display device is provided. The foldable display device includes a cover window. The foldable display device also includes a display panel disposed below the cover window.

[0013] Further details of the exemplary embodiments are included in the detailed description and the accompanying drawings.

[0014] According to this disclosure, by setting multiple protrusions on the protective film of the cover window, the reprocessing of the cover window can be facilitated.

[0015] According to this disclosure, by setting different adhesive strengths for different regions of the adhesive layer used to bond the protective film covering the window, reprocessing can be facilitated while maintaining adhesive strength, thereby improving folding characteristics.

[0016] The effects of this disclosure are not limited to those listed above, and include many more effects as described in this specification. Attached Figure Description

[0017] The above and other aspects, features and advantages of this disclosure will be more clearly understood from the following detailed embodiments, taken in conjunction with the accompanying drawings, wherein:

[0018] Figure 1 This is a plan view of a cover window according to an exemplary embodiment of the present disclosure;

[0019] Figure 2 It is along Figure 1 A cross-sectional view taken from line II-II;

[0020] Figure 3 This is a cross-sectional view of a cover window according to another exemplary embodiment of the present disclosure;

[0021] Figure 4 This is a cross-sectional view of a cover window according to yet another exemplary embodiment of the present disclosure;

[0022] Figure 5 This is a cross-sectional view of a cover window according to yet another exemplary embodiment of the present disclosure;

[0023] Figure 6 This is a cross-sectional view of a foldable display device according to an exemplary embodiment of the present disclosure. Detailed Implementation

[0024] The advantages and features of this disclosure, as well as methods for achieving these advantages and features, will become apparent from the exemplary embodiments described in detail below with reference to the accompanying drawings. However, this disclosure is not limited to the exemplary embodiments disclosed herein, but can be implemented in various forms. The exemplary embodiments are provided merely as examples to enable those skilled in the art to fully understand the disclosure and scope of this disclosure. Therefore, this disclosure is limited only by the scope of the appended claims.

[0025] The shapes, dimensions, ratios, angles, quantities, etc., shown in the accompanying drawings used to describe exemplary embodiments of this disclosure are merely examples, and this disclosure is not limited thereto. Throughout the specification, similar reference numerals generally denote similar elements. Furthermore, in the following description of this disclosure, detailed descriptions of known related technologies may be omitted to avoid unnecessarily obscuring the subject matter of this disclosure. Terms such as “comprising,” “having,” and “consisting of” as used herein are generally intended to allow for the addition of additional components, unless these terms are used in conjunction with the term “only.” Unless otherwise expressly stated, any reference to the singular may include the plural.

[0026] Even without explicit explanation, components are interpreted as including the normal tolerance range.

[0027] When using terms such as “above,” “over,” “below,” and “next” to describe the positional relationship between two parts, one or more parts may be located between the two parts unless the term is used with the terms “immediately following” or “directly.”

[0028] When an element or layer is placed "on" another element or layer, the other layer or element may be directly on or between the other elements.

[0029] Although the terms "first," "second," etc., are used to describe various components, these components are not limited by these terms. These terms are only used to distinguish one component from other components. Therefore, the first component mentioned below can be a second component in the technical concept of this disclosure.

[0030] Throughout the specification, similar reference numerals generally denote similar elements.

[0031] For ease of description, the dimensions and thickness of each component shown in the accompanying drawings are illustrated, but this disclosure is not limited to the dimensions and thickness of the components shown.

[0032] Features of various embodiments of this disclosure may be partially or completely dependent on or combined with each other, and may be interlocked and operated in various technical ways, and these embodiments may be performed independently of each other or in relation to each other.

[0033] The contents of this disclosure will be described in detail below with reference to the accompanying drawings.

[0034] Figure 1 This is a plan view of a cover window according to an exemplary embodiment of the present disclosure. Figure 2 It is along Figure 1 The cross-sectional view taken from line II-II. (Reference) Figure 1 and Figure 2 The cover window 100 includes a substrate layer 110, a hard coating layer 120, a protective film 130, and an adhesive layer 140.

[0035] refer to Figure 2 The substrate layer 110 is configured to provide rigidity within the cover window 100. When the cover window 100 is used in a foldable display device, it can protect the polarizing plate, touch panel, display panel, etc., beneath the cover window 100 from external impacts, moisture, heat, etc. The substrate layer 110 can be formed of a material that is impact-resistant and light-transmitting. For example, the substrate layer 110 is a thin film formed of a plastic material, such as, but not limited to, polymethyl methacrylate (PMMA), polyimide (PI), polyethylene terephthalate (PET), polyamide (PA), etc.

[0036] To reduce cracking caused by external impacts, the substrate layer 110 can be formed of a material with a high tensile Young's modulus, i.e., a material with high hardness. With a material having a high modulus, the material may not bend but break when the foldable display device is folded. However, even with a material having a high modulus, the material can still be folded when its thickness is equal to or less than a predetermined thickness. Therefore, the substrate layer 110 can have a very small thickness. For example, the substrate layer 110 can be a thin plastic film, but is not limited to this.

[0037] refer to Figure 2 A protective film 130 is disposed on the substrate layer 110. The protective film 130 can be disposed on the outermost part of the cover window 100 and can protect the substrate layer 110 from damage by external impact.

[0038] The protective film 130 can be formed from materials such as polyethylene naphthalate (PEN), polyimide (PI), epoxy-based, or acrylic-based, but is not limited thereto. Additionally, the transparency of the protective film 130 can be 90% or greater, and the turbidity of the protective film 130 can be 1% or less. Furthermore, the protective film 130 can be additionally coated to ensure certain surface properties. For example, the protective film 130 can be additionally coated to achieve a surface hardness of 3B or greater, and a contact angle of 100 degrees for fingerprint resistance (AF) functionality. However, this disclosure is not limited thereto.

[0039] refer to Figure 1 The protective film 130 includes a first region A1 and second regions A2 disposed on both sides of the first region A1. As described later, when the cover window 100 is used in a foldable display device, the first region A1 may correspond to the folded region, and the second region A2 may correspond to the non-folded region. Additionally, the center line CL of the first region A1 can be defined as a line passing through the midpoint of the width of the first region A1 along the X-axis direction, such as... Figure 1 and Figure 2 As shown, the center line CL can correspond to the folding axis, which is the axis along which the folded region is folded. Figure 1 In the diagram, the protective film 130 is shown as including a first region A1. However, when the foldable display device with the cover window 100 includes multiple folding regions, the first region A1 can be configured as multiple.

[0040] The protective film 130 may include a base film 131 and a plurality of protrusions 132 projecting from the base film 131. The base film 131 is the upper portion of the protective film 130, and the plurality of protrusions 132 are portions projecting downward from the base film 131. The base film 131 and the plurality of protrusions 132 may be integrally formed. Each of the plurality of protrusions 132 may include a first surface S1 perpendicular to the base film 131 and a second surface S2 inclined relative to the first surface S1 and the base film 131. That is, as Figure 2 As shown, the first surface S1 extends from the base film 131 perpendicular to the base film 131, and the second surface S2 extends from the base film 131 inclined relative to the base film 131. Consequently, the second surface S2 can also be inclined relative to the first surface S1. Therefore, the cross-sectional shape of each of the plurality of protrusions 132 can be a right-angled triangle.

[0041] In some embodiments, the first surface S1 may not be perpendicular to the base film 131. In this case, the angle formed by the first surface S1 and the base film 131 may be greater than the angle formed by the second surface S2 and the base film 131. That is, the tilt angle of the first surface S1 relative to the base film 131 may be greater than the tilt angle of the second surface S2 relative to the base film 131. Therefore, in a cross-sectional view, the length of the first surface S1 may be less than the length of the second surface S2. That is, the area of ​​the first surface S1 may be less than the area of ​​the second surface S2.

[0042] Multiple protrusions 132 may be provided in the first region A1. That is, multiple protrusions 132 may be provided in the first region A1, so that when the cover window 100 is used for a foldable display device, multiple protrusions 132 may be provided in the folding region.

[0043] The plurality of protrusions 132 may have a shape in which the protrusions 132 disposed on one side relative to the center line CL of the first region A1 and the protrusions 132 disposed on the other side are symmetrical to each other. That is, as shown in the figure Figure 2 As shown, the shapes of the protrusion 132 located on the left side relative to the center line CL of the first region A1 and the protrusion 132 located on the right side can be symmetrical to each other. In this case, each of the plurality of protrusions 132 can have a shape in which the second surface S2 is closer to the center line CL than the first surface S1.

[0044] refer to Figure 2 A hard coating 120 is disposed between the substrate layer 110 and the protective film 130. The hard coating 120 is used to further ensure the excellent flexibility, abrasion resistance and surface hardness of the substrate layer 110. The hard coating 120 may be formed of an organic material such as an acrylic-based or epoxy-based material, or it may be an organic-inorganic hybrid coating in which an inorganic material is contained in an organic material, but is not limited thereto.

[0045] The surface of the hard coating 120 can have a shape corresponding to the shape of the surface of the protective film 130. That is, as... Figure 2 As shown, the hard coating 120 may include recesses in portions corresponding to the plurality of protrusions 132 of the protective film 130, and may include protrusions in portions corresponding to the spaces between the plurality of protrusions 132 of the protective film 130.

[0046] refer to Figure 2 An adhesive layer 140 is disposed between the protective film 130 and the hard coating layer 120. The adhesive layer 140 may be disposed on the surface of the protective film 130 to bond the hard coating layer 120 and the protective film 130. For example, in the first region A1, the adhesive layer 140 may be disposed on the surface of a plurality of protrusions 132 of the protective film 130 to bond the hard coating layer 120 and the protective film 130.

[0047] UV-curable resins can be used for adhesive layer 140. For example, acrylic resins can be used for adhesive layer 140, and OCR (optically transparent resin) resins that can control the adhesive strength through UV curing can also be used. Adhesive layer 140 can have an adhesive strength that allows the protective film 130 to be easily separated during the reprocessing of cover window 100, i.e., during the replacement of cover window 100.

[0048] In the case of cover windows used in foldable display devices, the cover window also needs to be foldable because the display device needs to be folded. Therefore, a cover window made of plastic is used instead of a glass cover window. However, when a foldable display device using a cover window made of plastic is used for a predetermined period of time, the cover window may crack or develop fissures. With continuous use of a cover window that has developed cracks and fissures, there is a problem that users cannot correctly identify the image displayed on the foldable display device. Therefore, reprocessing is required, i.e., replacing the cover window used in the foldable display device. However, when the adhesive strength of the adhesive layer used to bond the cover window is high, it is difficult to reprocess the protective film. When the adhesive strength of the adhesive layer is low, peeling may occur during repeated folding of the foldable display device. Therefore, a cover window that can be reprocessed and also has folding properties is needed.

[0049] Therefore, the cover window 100 according to the exemplary embodiments of the present disclosure can be used in a foldable display device and can be reprocessed after a predetermined period of use. Specifically, the protective film 130 of the cover window 100 includes a plurality of protrusions 132 in a first region A1 corresponding to the folding area of ​​the foldable display device. In addition, the plurality of protrusions 132 disposed on both sides relative to the center line CL of the first region A1 have a symmetrical shape. In this case, each of the plurality of protrusions 132 may include a first surface S1 perpendicular to the base film 131 and a second surface S2 inclined relative to the base film 131. Therefore, in the cover window 100 according to the exemplary embodiments of the present disclosure, when the foldable display device is folded, even if the adhesive strength of the adhesive layer 140 is low, the shape of the plurality of protrusions 132 of the protective film 130 can prevent shear forces, thereby preventing the protective film 130 from peeling off. Specifically, when the adhesive strength of the adhesive layer 140 is reduced to facilitate reprocessing, the protective film 130 may peel off during repeated folding. However, since the plurality of protrusions 132 of the protective film 130 include a first surface S1 extending from the base film 131 in a direction perpendicular to it, shear forces can be prevented during the folding operation. Additionally, the plurality of protrusions 132 may include a second surface S2 extending obliquely from the base film 131, and the second surface S2 may be closer to the centerline CL than the first surface S1. Therefore, when the protective film 130 is stretched during the folding operation, the second surface S2 can allow the protective film 130 to slide easily. Therefore, when the cover window 100 according to an exemplary embodiment of the present disclosure is applied to a foldable display device, it can be easily reprocessed while improving folding characteristics.

[0050] Figure 3 This is a cross-sectional view of a cover window according to another exemplary embodiment of the present disclosure. Figure 3 The coverage window 300 shown is the reference. Figure 1 and Figure 2 The difference between the described cover window 100 and the reference is only in the adhesive layer 340, and the other construction is the same. Figure 1 and Figure 2 The construction of the described overlay window 100 is basically the same. Therefore, repeated descriptions will be omitted.

[0051] refer to Figure 3 The adhesive layer 340 may include a plurality of first adhesive layers 341 and a plurality of second adhesive layers 342. The plurality of first adhesive layers 341 may be disposed on the first surface S1 of the plurality of protrusions 132, and the plurality of second adhesive layers 342 may be disposed on the second surface S2 of the plurality of protrusions 132. Furthermore, the adhesive layer 340 may also be disposed in the second region A2 of the protective film 130. Therefore, the plurality of first adhesive layers 341 and the plurality of second adhesive layers 342 can be configured to be separate from each other.

[0052] The adhesive strength of the plurality of first adhesive layers 341 can be greater than the adhesive strength of the plurality of second adhesive layers 342. The plurality of first adhesive layers 341 of adhesive layer 340 are used to bond the first surfaces S1 of the plurality of protrusions 132 to the hard coating 120, and need to perform a shear-resistant function so that the protective film 130 does not peel off during the folding operation. On the other hand, the plurality of second adhesive layers 342 of adhesive layer 340 are used to bond the second surfaces S2 of the plurality of protrusions 132 to the hard coating 120, and need to allow good sliding properties in the horizontal direction during the folding operation so that the protective film 130 can easily slide when stretched during the folding operation. Therefore, the adhesive strength of the plurality of first adhesive layers 341 can be greater than the adhesive strength of the plurality of second adhesive layers 342. For example, the adhesive strength of the plurality of first adhesive layers 341 can be 300 gf / inch, and the adhesive strength of the plurality of second adhesive layers 342 can be from 30 gf / inch to 50 gf / inch, but this disclosure is not limited thereto.

[0053] The area of ​​the portion of the first surface S1 to which the plurality of first adhesive layers 341 are bonded can be smaller than the area of ​​the first surface S1. As described above, the plurality of first adhesive layers 341 can have relatively high adhesive strength to prevent the protective film 130 from peeling off during the folding operation. Therefore, when the bonding area of ​​the plurality of first adhesive layers 341 is relatively large, it may be difficult to replace the protective film 130 when reprocessing the cover window 300. Therefore, the area of ​​the portion of the first surface S1 to which the plurality of first adhesive layers 341 are bonded can be smaller than the area of ​​the first surface S1.

[0054] In a cover window 300 according to another exemplary embodiment of the present disclosure, the various regions of the adhesive layer 340 used to bond the protective film 130 and the hard coating 120 have different adhesive strengths, thereby allowing for easy reprocessing while improving folding characteristics. Specifically, to prevent shear forces and ensure that the protective film 130 does not peel off during folding operations, the adhesive strength of the first surface S1 used to bond the plurality of protrusions 132 and the first adhesive layer 341 used to bond the hard coating 120 can be relatively large. On the other hand, to allow the protective film 130 to slide easily when stretched during folding operations, the adhesive strength of the second surface S2 used to bond the plurality of protrusions 132 and the second adhesive layer 342 used to bond the hard coating 120 can be relatively small. Therefore, when the cover window 300 according to another exemplary embodiment of the present disclosure is applied to a foldable display device, it can be easily reprocessed while improving folding characteristics. Furthermore, in another exemplary embodiment of the cover window 300 according to the present disclosure, since the area of ​​the portion of the first surface S1 to which a plurality of first adhesive layers 341 are bonded is smaller than the area of ​​the first surface S1, it can further facilitate the reprocessing process.

[0055] Meanwhile, in the reprocessing process of the cover window 300, the cover window 300 is not completely replaced; only the protective film 130 and the adhesive layer 340 are replaced. Therefore, in terms of actual products, products consisting only of the protective film 130 and the adhesive layer 340 can be configured for sale.

[0056] Figure 4 This is a cross-sectional view of a cover window according to yet another exemplary embodiment of the present disclosure. Figure 4 The shown coverage window 400 and reference Figure 3 The described cover window 300 differs only in the protective film 430, adhesive layer 440, and hard coating 420, and the other construction is the same as the reference. Figure 3 The construction of the overlay window 300 described is basically the same. Therefore, repeated descriptions will be omitted.

[0057] refer to Figure 4 Multiple protrusions 432 are disposed in the first region A1 and the second region A2. That is, when the cover window 400 is applied to the foldable display device, the multiple protrusions 432 can be configured to correspond to all folded and non-folded regions of the foldable display device.

[0058] The plurality of protrusions 432 may have a shape in which the protrusions 432 disposed on one side are symmetrical to each other with respect to the center line CL of the first region A1. Therefore, not only can the plurality of protrusions 432 disposed in the first region A1 have a cross-sectional shape symmetrical about the center line CL of the first region A1, but the plurality of protrusions 432 disposed in the second region A2 may also have a cross-sectional shape symmetrical about the center line CL of the first region A1.

[0059] The plurality of adhesive layers 440 may include a plurality of first adhesive layers 441 and a plurality of second adhesive layers 442. In this case, the plurality of first adhesive layers 441 may be disposed on the first surface S1 of the plurality of protrusions 432 disposed in the first region A1 and the second region A2, and the plurality of second adhesive layers 442 may be disposed on the second surface S2 of the plurality of protrusions 432 disposed in the first region A1 and the second region A2. Furthermore, the adhesive strength of the plurality of first adhesive layers 441 may be greater than the adhesive strength of the plurality of second adhesive layers 442.

[0060] The surface of the hard coating 420 can have a shape corresponding to the shape of the surface of the protective film 430. That is, as... Figure 4 As shown, the hard coating 420 may include recesses in portions corresponding to the plurality of protrusions 432 of the protective film 430, and the hard coating 420 may include protrusions in portions corresponding to the spaces between the plurality of protrusions 432 of the protective film 430.

[0061] In a cover window 400 according to another exemplary embodiment of the present disclosure, a plurality of protrusions 432 of the protective film 430 may be provided in the first region A1 and the second region A2. Therefore, in the cover window 400 according to another exemplary embodiment of the present disclosure, reprocessing can be easily performed while improving folding characteristics. Specifically, when the cover window 400 is applied to a foldable display device, since the plurality of protrusions 432 are also provided in the second region A2 corresponding to the non-folded region, the plurality of protrusions 432 provided in the second region can also prevent shearing forces, so that the protective film 430 will not peel off during the folding operation. Furthermore, when the protective film 430 is stretched during the folding operation, the plurality of protrusions 432 provided in the second region A2 can allow the protective film 430 to slide easily.

[0062] Figure 5 This is a cross-sectional view of a cover window according to yet another exemplary embodiment of the present disclosure. Figure 5 The coverage window 500 shown is the same as the reference. Figure 4 The described cover window 400 differs only in the protective film 530, adhesive layer 540, and hard coating 520, and the other construction is the same as the reference. Figure 4 The construction of the described overlay window 400 is basically the same. Therefore, repeated descriptions will be omitted.

[0063] refer to Figure 5 Multiple protrusions 532 are disposed in the first region A1 and the second region A2. That is, when the cover window 500 is applied to a foldable display device, the multiple protrusions 532 can be configured to correspond to all folded and non-folded regions of the foldable display device.

[0064] In this case, the tilt angle of the second surface S2 of each of the plurality of protrusions 532 relative to the base film 531 can be further reduced. Therefore, in the cross-sectional view, the height of the protrusion 532 in the direction perpendicular to the base film 531 can be less than the length of the protrusion 532 in the direction parallel to the base film 531. Therefore, as... Figure 5 As shown, the cross-sectional shape of each of the plurality of protrusions 532 can be a right-angled triangle, wherein the length of the horizontal side of the right-angled triangle is greater than the length of the vertical side. However, this disclosure is not limited thereto.

[0065] The plurality of adhesive layers 540 may include a plurality of first adhesive layers 541 and a plurality of second adhesive layers 542. In this case, the plurality of first adhesive layers 541 may be disposed on the first surface S1 of the plurality of protrusions 532 disposed in the first region A1 and the second region A2, and the plurality of second adhesive layers 542 may be disposed on the second surface S2 of the plurality of protrusions 532 disposed in the first region A1 and the second region A2. In addition, the adhesive strength of the plurality of first adhesive layers 541 may be greater than the adhesive strength of the plurality of second adhesive layers 542.

[0066] The surface of the hard coating 520 can have a shape corresponding to the shape of the surface of the protective film 530. That is, as... Figure 5 As shown, the hard coating 520 may include recesses in portions corresponding to the plurality of protrusions 532 of the protective film 530, and the hard coating 520 may include protrusions in portions corresponding to the spaces between the plurality of protrusions 532 of the protective film 530.

[0067] In a further exemplary embodiment of the cover window 500 according to the present disclosure, the various regions of the adhesive layer 540 used to bond the protective film 530 and the hard coating 520 have different levels of adhesive strength. Simultaneously, the area of ​​the first surface S1 of the plurality of protrusions 532 extending in a direction perpendicular to the base film 531 can be reduced, and the area of ​​the second surface S2 of the plurality of protrusions 532 extending obliquely relative to the base film 531 can be increased. Therefore, the area of ​​the plurality of first adhesive layers 541 disposed on the first surface S1 of the plurality of protrusions 532 can be reduced, and the area of ​​the plurality of second adhesive layers 542 disposed on the second surface S2 of the plurality of protrusions 532 can be increased. Therefore, in the cover window 500 according to another exemplary embodiment of the present disclosure, reprocessing can be easily performed while improving folding characteristics. Specifically, the adhesive strength of the first surface S1 of the plurality of protrusions 532 and the first adhesive layer 541 used to bond the hard coating 520 can be relatively high to prevent shear forces, ensuring that the protective film 530 does not peel off during the folding operation. On the other hand, the adhesive strength of the second surface S2 of the plurality of protrusions 532 and the second adhesive layer 542 of the hard coating 520 can be relatively low, so that the protective film 530 can be easily slidable when stretched during a folding operation. Furthermore, in the cover window 500 according to another exemplary embodiment of the present disclosure, the area of ​​the first surface S1 of the plurality of protrusions 532 is reduced to facilitate reprocessing. Therefore, the phenomenon that the protective film 530 is not easily separated due to the plurality of first adhesive layers 541 having relatively high adhesive strength can be minimized. Furthermore, the area of ​​the second surface S2 of the plurality of protrusions 532 is increased, so that when the protective film 530 is stretched during a folding operation, the protective film 530 can be easily slidable by the plurality of second adhesive layers 542 having relatively low adhesive strength. Therefore, when the cover window 500 according to another exemplary embodiment of the present disclosure is applied to a foldable display device, it can be easily reprocessed while improving folding characteristics.

[0068] Figure 6 This is a cross-sectional view of a foldable display device according to an exemplary embodiment of the present disclosure. Reference Figure 6 The foldable display device 1000 includes a display panel PNL and a cover window 500. For ease of description, Figure 6 It shows Figure 5 The cover window 500 shown is included in the foldable display device 1000, but this disclosure is not limited thereto. (See references) Figures 1 to 5 The overlay windows 100, 300, 400 and 500 described in accordance with the various exemplary embodiments of the present disclosure may be included in the foldable display device 1000.

[0069] refer to Figure 6 The display panel PNL is positioned below the overlay window 500. The display panel PNL is the panel that displays the image. Within the display panel PNL, light-emitting elements for displaying the image, as well as circuitry, wiring, and components for driving these elements, can be installed. The display panel PNL can be a flexible display panel PNL. For example, the display panel PNL can be a foldable display panel PNL, but it is not limited to this.

[0070] The display panel PNL includes a display area and a non-display area. Furthermore, the display panel PNL includes a folded area (FA) and a non-folded area (NFA). The areas of the display panel PNL can be classified according to whether an image is displayed, and also according to whether it is folded. A specific area of ​​the display panel PNL can be defined based on whether an image is displayed and whether it is folded. For example, a specific area of ​​the display panel PNL can be both a display area and a folded area (FA).

[0071] The display area is an area used to display images, and multiple sub-pixels can be arranged within the display area. These sub-pixels include light-emitting elements for displaying the images and circuit units for driving the light-emitting elements. The circuit units may include various thin-film transistors, storage capacitors, and lines for driving the organic light-emitting elements. For example, the circuit units may include, but are not limited to, various components such as driving thin-film transistors, switching thin-film transistors, storage capacitors, gate lines, and data lines.

[0072] A circuit unit may include various thin-film transistors, capacitors, and lines for driving electroluminescent devices. For example, a circuit unit may include, but is not limited to, various components such as driving thin-film transistors, switching thin-film transistors, storage capacitors, gate lines, and data lines.

[0073] The non-display area is the area where no image is displayed. In the non-display area, circuitry, wiring, and components for driving the light-emitting elements of the display area are installed. Driver ICs, such as gate driver ICs and data driver ICs, can be located in the non-display area.

[0074] The non-display area can be defined as the area surrounding the display area. However, the non-display area can also be defined as the area extending from the display area, or an area without any light-emitting elements, but it is not limited to these definitions.

[0075] Meanwhile, the display panel PNL can be defined as a display area and a non-display area, but it can also be defined as a folded area FA and a non-folded area NFA.

[0076] The folding region FA is the area of ​​the foldable display panel PNL, i.e., the flexible area. The folding region FA is the area that folds relative to the folding axis FX, and it can be folded with a specific radius of curvature. Since the folding region FA is the area of ​​the foldable display panel PNL, it can be defined as the folding region FA. The folding region FA includes a portion of the non-display area and a portion of the display area adjacent to the folding axis FX.

[0077] exist Figure 6 In this context, the folding axis FX is represented as being located at the center of the display panel PNL. However, the position and number of folding axes FX can vary, and the folding area FA can also vary depending on the position and number of folding axes FX. However, this disclosure is not limited thereto.

[0078] The non-folding area (NFA) is the region of the display panel (PNL) that remains flat. The non-folding area (NFA) includes a portion of the display area and a portion of the non-display area. The non-folding area (NFA) is the region where the display panel (PNL) is not folded, and can be defined as the non-folding area (NFA). The non-folding area (NFA) can be located on either side of the folding area (FA). Two non-folding area (NFA) can be configured such that the folding area (FA) is positioned between them.

[0079] The folded area FA can correspond to the first area A1 of the cover window 500. That is, the folded area FA and the first area A1 can be set to overlap each other. Furthermore, the folding axis FX can correspond to the center line CL of the first area A1. That is, the folding axis FX and the center line CL of the first area A1 can be set to overlap each other. Furthermore, the non-folded area NFA can correspond to the second area A2 of the cover window 500. That is, the non-folded area NFA and the second area A2 can be set to overlap each other.

[0080] exist Figure 6 In this illustration, the foldable display device 1000 is shown as including only the display panel PNL and the cover window 500, but it may also include various other components. For example, the foldable display device 1000 may also include a polarizing plate, a touch panel, etc., between the cover window 500 and the display panel PNL. Furthermore, the foldable display device 1000 may also include components that facilitate and assist in folding the foldable display device 1000, such as a back plate or bottom plate below the display panel PNL.

[0081] The cover window 500 of the foldable display device 1000 according to an exemplary embodiment of the present disclosure can improve folding characteristics while allowing for easy reprocessing after a predetermined period of use.

[0082] An exemplary embodiment of this disclosure can also be described as follows:

[0083] According to one aspect of this disclosure, a cover window is provided. The cover window includes a substrate layer. The cover window also includes a hard coating layer on the substrate layer. The cover window also includes a protective film disposed on the hard coating layer and including a base film and a plurality of protrusions projecting from the base film. The cover window also includes an adhesive layer disposed on the surfaces of the plurality of protrusions and bonding the hard coating layer and the protective film. The protective film includes a first region and a second region disposed on both sides of the first region. The plurality of protrusions are disposed in the first region. The plurality of protrusions have a shape in which the protrusions disposed on one side relative to the centerline of the first region and the protrusions disposed on the other side are symmetrical to each other.

[0084] Each of the plurality of protrusions may include a first surface perpendicular to the base film and a second surface inclined relative to the first surface and the base film.

[0085] The area of ​​the first surface can be smaller than the area of ​​the second surface.

[0086] In the cross-sectional view, the length of the first surface can be less than the length of the second surface.

[0087] The adhesive layer may include a first adhesive layer disposed on a first surface and a second adhesive layer disposed on a second surface. The adhesive strength of the first adhesive layer may be greater than the adhesive strength of the second adhesive layer.

[0088] The adhesive strength of the first adhesive layer can be 100 gf / inch, and the adhesive strength of the second adhesive layer can be from 30 gf / inch to 50 gf / inch.

[0089] The area of ​​the portion of the first surface with the first adhesive layer can be smaller than the area of ​​the first surface.

[0090] Each of the multiple protrusions may have a shape in which the second surface is closer to the centerline of the first region than the first surface.

[0091] Multiple protrusions can be set in the first and second regions.

[0092] The surface of the hard coating can have a shape that corresponds to the shape of the surface of the protective film.

[0093] According to another aspect of this disclosure, a foldable display device is provided. The foldable display device includes a cover window. The foldable display device also includes a display panel disposed below the cover window.

[0094] The display panel may include a folded area and non-folded areas on either side of the folded area. The first area corresponds to the folded area, and the second area corresponds to the non-folded area.

[0095] Although exemplary embodiments of the present disclosure have been described in detail with reference to the accompanying drawings, the present disclosure is not limited thereto and may be embodied in many different forms without departing from the technical concept of the present disclosure. Therefore, the exemplary embodiments of the present disclosure are provided for illustrative purposes only and are not intended to limit the technical concept of the present disclosure. The scope of the technical concept of the present disclosure is not limited thereto. Therefore, it should be understood that the above exemplary embodiments are illustrative in all respects and do not limit the present disclosure. The scope of protection of the present disclosure should be interpreted based on the following claims, and all technical concepts within the scope of their equivalents should be interpreted as falling within the scope of the present disclosure.

Claims

1. A foldable display device, comprising: Cover window; and The display panel is located below the overlay window. The coverage window includes: Substrate layer; A coating is applied to the substrate layer; A protective film, disposed on the coating and including a plurality of protrusions projecting toward the coating; and An adhesive layer is placed between the protective film and the coating. Each of the plurality of protrusions includes a first surface and a second surface. The adhesive layer comprises a first adhesive layer located on the first surface and a second adhesive layer located on the second surface. Wherein, the length of the first surface is less than the length of the second surface, and the second surface is closer to the centerline than the first surface. Wherein, the adhesive strength of the first adhesive layer is greater than the adhesive strength of the second adhesive layer.

2. The foldable display device according to claim 1, wherein, The display panel includes a display area and a non-display area, and the display panel also includes a folding area and a non-folding area. Wherein, a portion of the display panel is the display area, and the portion of the display panel is the folding area.

3. The foldable display device according to claim 2, wherein, The display area includes multiple sub-pixels, and each sub-pixel includes a light-emitting element and a circuit unit.

4. The foldable display device according to claim 3, wherein, The circuit unit includes a thin-film transistor, a storage capacitor, and a wire.

5. The foldable display device according to claim 2, wherein, The folded area is configured to fold relative to the folding axis.

6. The foldable display device according to claim 5, wherein, The folding axis is configured to be located at the center of the display panel.

7. The foldable display device according to claim 5, wherein, The folded area includes the portion of the display area adjacent to the folding axis and the portion of the non-display area adjacent to the folding axis.

8. The foldable display device according to claim 1, further comprising: A polarizing plate or touch panel located between the cover window and the display panel.

9. The foldable display device according to claim 1, further comprising: The back panel is located below the display panel.

10. The foldable display device according to claim 1, wherein, The adhesive layer comprises an acrylic resin.

11. The foldable display device according to claim 1, wherein, The adhesive layer comprises a UV-curable resin.

12. The foldable display device according to claim 1, wherein, The adhesive layer comprises an optically transparent resin (OCR).

13. The foldable display device according to any one of the preceding claims, wherein, The coating comprises organic materials.

14. The foldable display device according to claim 13, wherein, The organic material is an acrylic-based or epoxy-based material.

15. The foldable display device according to any one of claims 1-12, wherein, The coating comprises an organic-inorganic hybrid coating in which inorganic materials are contained within organic materials.

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