Foldable display device

Abstract

A foldable display device is disclosed. The foldable display device may include a window. The window includes a first sub-window, a second sub-window, and an adhesive layer for coupling the first sub-window and the second sub-window to each other. The first sub-window includes a first base layer having a light transmittance of more than 90% and a first anti-fingerprint layer disposed on an upper surface of the first base layer, and the second sub-window includes a second base layer disposed on the first sub-window. A contact angle of a region of the upper surface of the first sub-window corresponding to a folding region is less than a contact angle of a region of the upper surface of the first sub-window corresponding to a peripheral region.

Description

Technical Field

[0001] The present invention relates to a foldable display device, and more particularly, to a foldable display device including a partially replaceable window. Background Art

[0002] Electronic devices such as smartphones, tablet computers, notebook computers, automotive navigation systems, and smart TVs are being developed. Each electronic device may include a display device for providing information. In addition to the display device, the electronic device also includes various display modules.

[0003] Depending on the use of the electronic device, the electronic device may have various shapes. Electronic devices including foldable display devices, bendable display devices, and curved display devices have been developed to meet the needs of users. Summary of the Invention

[0004] Technical Problem

[0005] An object of the present invention is to provide a foldable display device including a window having improved durability and easy replaceability.

[0006] Technical Solution

[0007] The foldable display device according to the present invention includes a display panel and a window disposed on the display panel and including a folding area and a peripheral area. The window includes: a first sub-window including a first base layer having a light transmittance of 90% or more and a first anti-fingerprint layer disposed on an upper surface of the first base layer; a second sub-window including a second base layer disposed on the first sub-window; and an adhesive layer configured to couple the first sub-window to the second sub-window. A contact angle of a region of the upper surface of the first sub-window corresponding to the folding area is less than a contact angle of a region of the upper surface of the first sub-window corresponding to the peripheral area.

[0008] The contact angle of the region of the upper surface of the first sub-window corresponding to the folding area may be 62° or less.

[0009] The adhesive force of the region of the upper surface of the first sub-window corresponding to the folding area to the adhesive layer may be 150 g / inch or more.

[0010] The contact angle of the region of the upper surface of the first sub-window corresponding to the peripheral area may be 112° or less.

[0011] The first base layer may include polyimide, polycarbonate, polyamide, triacetyl cellulose, or polymethyl methacrylate.

[0012] The second sub-window may include polyethylene terephthalate.

[0013] The second sub-window may further include at least one of a hard coat, a second anti-fingerprint layer, and an anti-reflection layer disposed on the upper surface of the second base layer.

[0014] The second sub-window may further include a second anti-fingerprint layer disposed on the upper surface of the second base layer, and the second anti-fingerprint layer may overlap with the folding area and the peripheral area and have a substantially uniform thickness.

[0015] The first anti-fingerprint layer may include perfluoropolyether.

[0016] The atomic percentage (at%) of fluorine in the region of the first anti-fingerprint layer corresponding to the folding area may be less than the atomic percentage (at%) of fluorine in the region of the first anti-fingerprint layer corresponding to the peripheral area.

[0017] The atomic percentage of fluorine in the region of the first anti-fingerprint layer corresponding to the folding area may be less than the atomic percentage of oxygen.

[0018] The first anti-fingerprint layer may not be provided in at least a part of the region of the upper surface of the first sub-window corresponding to the folding area.

[0019] In the region of the upper surface of the first sub-window corresponding to the folding area, the occupied area per unit area of the first anti-fingerprint layer in the region adjacent to the peripheral area may be less than the occupied area per unit area of the first anti-fingerprint layer in the region corresponding to the center of the folding area.

[0020] The foldable display device may further include a color filter disposed on the display panel.

[0021] The foldable display device may further include an input sensor disposed on the display panel.

[0022] The foldable display device according to the present invention may include a display panel and a window disposed on the display panel and including a folding area and a peripheral area. The window includes: a first sub-window including a first base layer having a light transmittance of more than 90% and a perfluoropolyether layer disposed on the upper surface of the first base layer; a second sub-window disposed on the first sub-window; and an adhesive layer configured to couple the first sub-window to the second sub-window. The adhesion of the region of the upper surface of the first sub-window corresponding to the folding area to the adhesive layer is greater than the adhesion of the region of the upper surface of the first sub-window corresponding to the peripheral area to the adhesive layer.

[0023] The adhesion of the region of the upper surface of the first sub-window corresponding to the folding area to the adhesive layer may be 150 g-force per inch or more.

[0024] The adhesion of the region of the upper surface of the first sub-window corresponding to the folding area to the adhesive layer may be 100 g-force per inch or more greater than the adhesion of the region of the upper surface of the first sub-window corresponding to the peripheral area to the adhesive layer.

[0025] The atomic percentage of fluorine in the region of the perfluoropolyether layer corresponding to the folding region may be less than the atomic percentage of fluorine in the region of the perfluoropolyether layer corresponding to the outer peripheral region.

[0026] The perfluoropolyether layer may not be provided in at least a part of the region of the upper surface of the first sub-window corresponding to the folding region.

[0027] Beneficial effects

[0028] As described above, in the unfolded state, a region of the second sub-window corresponding to a region of the outer peripheral region can be made to start separating. The second sub-window having a relatively weak coupling force can be easily delaminated together with the adhesive layer. Since the region having a relatively high coupling force is restricted to the folding region, damage to the second sub-window or the first sub-window during the delamination of the second sub-window can be prevented.

[0029] During inner folding, large shear stresses may occur in the folding region, and since the coupling force between the first sub-window and the second sub-window is relatively large in the folding region, the first sub-window and the second sub-window can remain undelaminated from each other even when a large shear stress is applied. Description of the drawings

[0030] Figures 1a to 1c is a perspective view of a display device according to an embodiment of the present invention.

[0031] Figures 2a to 2d is a cross-sectional view of a display device according to an embodiment of the present invention.

[0032] Figure 3 is a perspective view of a window according to an embodiment of the present invention.

[0033] Figure 4a is a cross-sectional view showing a state in which a window according to an embodiment of the present invention is unfolded.

[0034] Figure 4b is a cross-sectional view showing a state in which a window according to an embodiment of the present invention is inner-folded.

[0035] Figure 5a is a cross-sectional view of a first sub-window according to an embodiment of the present invention.

[0036] Figure 5b is a cross-sectional view of a second sub-window according to an embodiment of the present invention.

[0037] Figure 6a is a view showing the result of analyzing the remaining amount of the anti-fingerprint layer obtained by X-ray photoelectron spectroscopy (XPS).

[0038] Figure 6bIt is a graph showing the contact angle and adhesion force of the first sub-window according to the plasma treatment time.

[0039] Figures 7a to 7d It is a cross-sectional view showing a method for manufacturing the first sub-window according to an embodiment of the present invention.

[0040] Figure 8a and Figure 8b It is a plan view of a mask according to an embodiment of the present invention. Detailed Description

[0041] In this specification, it will also be understood that when a component (or region, layer, part) is referred to as being "on" another component, "connected to" another component, or "coupled to" another component, it can be directly disposed / connected / coupled on / to another component, or there can also be an intervening third component.

[0042] The same reference numerals throughout the specification denote the same elements. In addition, in the drawings, for clarity of illustration, the thickness, ratio, and dimensions of the components are exaggerated. The term "and / or" includes any and all combinations of one or more related elements.

[0043] It will be understood that although terms such as "first" and "second" are used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one component from other components. For example, without departing from the scope of the appended claims, a first element that is referred to as the first element in one embodiment can be referred to as the second element in another embodiment. Unless otherwise stated, terms in the singular form may include the plural form.

[0044] In addition, "below", "beneath", "above", "on", etc. are used to explain the relationship between the elements shown in the drawings. These terms can be relative concepts and can be described based on the directions shown in the drawings.

[0045] The meaning of "comprising" or "including" specifies attributes, fixed numbers, steps, operations, elements, components, or combinations thereof, but does not exclude other attributes, fixed numbers, steps, operations, elements, components, or combinations thereof.

[0046] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. In addition, terms (such as those defined in common dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and are explicitly defined herein, unless interpreted in an idealized or overly formal sense.

[0047] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0048] Figures 1a to 1c is a perspective view of a display device according to an embodiment of the present invention.

[0049] As Figures 1a to 1c shown, the display surface DD-IS is parallel to the surface defined by the first direction axis DR1 and the second direction axis DR2. The normal direction of the display surface DD-IS (i.e., the thickness direction of the display device DD) is represented as the third direction axis DR3. Based on the third direction axis DR3, the front surface (or top surface) and the back surface (or bottom surface) of each member are distinguished. Hereinafter, the first direction, the second direction, and the third direction may be the directions indicated by the first direction axis DR1, the second direction axis DR2, and the third direction axis DR3, respectively, and are represented by the same reference numerals.

[0050] As Figures 1a to 1c shown, the display surface DD-IS includes a display area DD-DA on which an image IM is displayed and a non-display area DD-NDA adjacent to the display area DD-DA. The non-display area DD-NDA may be an area on which no image IM is displayed. Figures 1a to 1c Shows an icon as an example of the image IM. For example, the display area DD-DA may have a rectangular shape. The non-display area DD-NDA may surround the display area DD-DA. However, the embodiments of the present invention are not limited thereto, and the shapes of the display area DD-DA and the non-display area DD-NDA may be modified.

[0051] As Figures 1a to 1c shown, the display device DD may include a plurality of areas defined according to the form of operation. The display device DD may include a folding area FA folded based on a folding axis FX, a first peripheral area NFA1 adjacent to the folding area FA, and a second peripheral area NFA2. The folding area FA is an area that generally forms a curvature.

[0052] As Figure 1b shown, the display device DD may be folded inward or bent inward such that the display surfaces DD-IS of the first peripheral area NFA1 and the second peripheral area NFA2 face each other. As Figure 1c shown, the display device DD may be folded outward or bent outward such that the display surface DD-IS is exposed to the outside. As Figures 1a to 1c shown, a display module that repeatedly performs folding and unfolding operations may be defined as a foldable display module.

[0053] In an embodiment of the present invention, the display device DD may include a plurality of folding areas FA. In addition, the folding area FA may be defined to correspond to an operation of a user manipulating the display device DD. For example, with Figure 1b andFigure 1c Differently, the folding region FA can be defined as parallel to the second direction axis DR2 and can be defined in the diagonal direction where the first direction axis DR1 and the second direction axis DR2 intersect each other. The folding region FA can have a variable surface area and can be determined according to the radius of curvature. In an embodiment of the present invention, the display device DD can be configured to only repeat Figure 1a and Figure 1b the operation modes shown in Figure 1a and Figure 1c or can be configured to only repeat the operation modes shown in

[0054] Although the display device DD applied to a mobile phone is shown in this embodiment, the present invention is not limited thereto. In an embodiment of the present invention, the display device DD can be applied to large electronic devices such as televisions and monitors and medium and small electronic devices such as tablet computers (PCs), navigation systems for vehicles, game consoles, and smart watches.

[0055] Figures 2a to 2d is a cross-sectional view of the display device DD according to an embodiment of the present invention. Figures 2a to 2d A cross-section defined by the second direction axis DR2 and the third direction axis DR3 is shown. It is schematically shown Figures 2a to 2d to explain the stacking relationship of the functional panels and / or functional units constituting the display device.

[0056] The display device DD according to an embodiment of the present invention can include a display panel, an input sensor, an antireflection unit, and a window. At least some of the display panel, the input sensor, the antireflection unit, and the window can be formed by a continuous process, and at least some can be coupled to each other through an adhesive member. In Figures 2a to 2d an example, a pressure-sensitive adhesive film (PSA) is shown as the adhesive member. The adhesive members described below can include ordinary adhesives or pressure-sensitive adhesives and are not particularly limited. In an embodiment of the present invention, the antireflection unit and the window can be replaced or omitted with different components.

[0057] In Figures 2a to 2d an example, the corresponding components of the input sensor, the antireflection unit, and the window that are formed by a continuous process relative to other components can be represented as "layers". Moreover, the components of the input sensor, the antireflection unit, and the window that are coupled to other components through an adhesive member can be represented as "panels". A "panel" can include a base layer that provides a base surface, for example, a synthetic film, a composite material film, a glass substrate, etc., but the base layer can be omitted in a "layer". That is, the member or unit represented as a "layer" can be disposed on the base surface provided by other members or units.

[0058] Depending on the presence / absence of the base layer, the input sensor and the antireflection unit may be referred to as an input sensing panel, an antireflection panel, an input sensing layer, or an antireflection layer. In this embodiment, all windows are shown as having a "panel" type structure applied thereto.

[0059] As Figure 2a shown, the display device DD may include a display panel DP, an input sensing layer ISL, an antireflection panel RPP, a window WP, and a protection member PF. In the display device DD, the coupling structure of the components other than the window WP may be defined as a display module.

[0060] The input sensing layer ISL may be directly disposed on the display panel DP. In this specification, "component B1 is directly disposed on component A1" means that no adhesive member is disposed between component A1 and component B1. After forming component A1, component B1 is formed on the substrate surface provided by component A1 through a continuous process. A pressure-sensitive adhesive film PSA is disposed between the antireflection panel RPP and the window WP, between the input sensing layer ISL and the antireflection panel RPP, and between the protection member PF and the display panel DP.

[0061] The display panel DP generates an image IM, and the input sensing layer ISL obtains coordinate information of an external input (e.g., a touch event). The protection member PF supports the display panel DP and protects the display panel DP from external impacts. The protection member PF may include a plastic film as a base layer. The material for forming the protection member PF is not limited to plastic resins. For example, the protection member PF may be formed of an organic / inorganic composite material. The protection member PF may include a porous organic layer and an inorganic material filled into the pores of the organic layer.

[0062] The display panel DP according to an embodiment of the present invention may be an emissive display panel, but is not particularly limited thereto. For example, the display panel DP may be an organic light-emitting display panel and a quantum dot light-emitting display panel. The light-emitting layer of the organic light-emitting display panel may include an organic light-emitting material. The emission layer of the quantum dot light-emitting display panel may include quantum dots and / or quantum rods. Hereinafter, an organic light-emitting display panel will be described as an example of the display panel DP.

[0063] The antireflection panel RPP reduces the reflectivity of natural light (or sunlight) incident from the upper side of the window WP. The antireflection panel RPP according to an embodiment of the present invention may include a retarder and a polarizer. The retarder may be a film type or a liquid crystal coated type retarder, and may include a λ / 2 retarder and / or a λ / 4 retarder. The polarizer may also be provided as a film type or a liquid crystal coated type polarizer. The film type may include an extended synthetic resin, and the liquid crystal coated type may include liquid crystals arranged in a predetermined arrangement. Each of the retarder and the polarizer may further include a protective film. The retarder itself or the polarizer itself may be defined as the base layer of the antireflection panel RPP. The protective film may be defined as the base layer of the antireflection panel RPP.

[0064] The antireflection panel RPP according to an embodiment of the present invention may include a color filter. The color filter may have a predetermined arrangement. The arrangement of the color filter may be determined according to the color of light emitted from pixels provided in the display panel DP. The antireflection panel RPP may further include a black matrix adjacent to the color filter.

[0065] The window WP according to an embodiment of the present invention includes a base layer WP-BS and a light-shielding pattern WP-BZ. The base layer WP-BS may have a multilayer structure that will be described in detail below. In an embodiment of the present invention, the light-shielding pattern WP-BZ may be omitted.

[0066] The light-shielding pattern WP-BZ partially overlaps with the base layer WP-BS. The light-shielding pattern WP-BZ may be provided on the rear surface of the base layer WP-BS to define a border area of the display device DD, that is, a non-display area DD-NDA (see FIG. 1). The light-shielding pattern WP-BZ may be a colored organic film, for example, formed in a coating manner. In Figures 2b to 2d the window WP is schematically shown without distinguishing the base layer WP-BS and the light-shielding pattern WP-BZ from each other.

[0067] Referring to Figure 2b and Figure 2c , the display device DD may include a protection member PF, a display panel DP, an antireflection panel RPP, an input sensing panel ISP, and a window WP. The stacking order of the input sensing panel ISP and the antireflection panel RPP may be changed.

[0068] As Figure 2d shown, the display device DD may include a protection member PF, a display panel DP, an input sensing layer ISL, an antireflection layer RPL, and a window WP. Most of the adhesive members may be omitted from the display device DD, and the input sensing layer ISL and the antireflection layer RPL may be formed on the substrate surface provided to the display panel DP by a continuous process. The stacking order of the input sensing layer ISL and the antireflection panel RPP may be changed.

[0069] In an embodiment of the present invention, the antireflection layer RPL may include a liquid crystal coated retarder and a liquid crystal coated polarizer. The retarder and the polarizer may include a discotic liquid crystal layer having an inclination angle in one direction. In an embodiment of the present invention, the antireflection layer RPL may include a color filter. The color filter may constitute a separate and distinct layer, but may also form part of the input sensing layer ISL. It is sufficient to dispose the color filter between the display panel DP and the window WP.

[0070] Figure 3 is a perspective view of a window according to an embodiment of the present invention. Figure 4a is a cross-sectional view showing a state in which the window according to an embodiment of the present invention is unfolded. Figure 4b is a cross-sectional view showing a state in which the window according to an embodiment of the present invention is folded inward. Figure 5a is a cross-sectional view of a first sub-window according to an embodiment of the present invention. Figure 5b is a cross-sectional view of a second sub-window according to an embodiment of the present invention. Figure 6a is a view showing the result of analyzing the remaining amount of the anti-fingerprint layer obtained by X-ray photoelectron spectroscopy (XPS). Figure 6b is a graph showing the contact angle and adhesion of the first sub-window according to the plasma treatment time. All windows WP described below can be applied to the display device DD described with reference to Figures 2a to 2d as described.

[0071] As Figure 3 shown, the window WP may include a folding region FA, a first peripheral region NFA1 adjacent to the folding region FA, and a second peripheral region NFA2. Basically, the folding region FA, the first peripheral region NFA1, and the second peripheral region NFA2 of the window WP may be the same as the folding region FA, the first peripheral region NFA1, and the second peripheral region NFA2 described with reference to Figures 1a to 1c and thus the same reference numerals are used.

[0072] As Figure 4a and Figure 4b shown, the window WP may include a first sub-window SWP1 (or inner window), a second sub-window SWP2 (or outer window) disposed on the first sub-window SWP1, and an adhesive layer ADL disposed between the first sub-window SWP1 and the second sub-window SWP2 to couple the first sub-window SWP1 to the second sub-window SWP2.

[0073] The second sub-window SWP2 may be delaminated from the first sub-window SWP1 together with the adhesive layer ADL. When a scratch or dent defect occurs in the window WP due to an external impact, the second sub-window SWP2 may be delaminated from the first sub-window SWP1 together with the adhesive layer ADL, and a new second sub-window SWP2 may be coupled to the first sub-window SWP1. That is, the second sub-window SWP2 has a function of a replaceable protective layer or a protective window.

[0074] The second sub-window SWP2 includes at least a base layer. The base layer may have a light transmittance of at least 90% or more. The second sub-window SWP2 may include a plastic film as the base layer. For example, the second sub-window SWP2 may include polyethylene terephthalate.

[0075] The second sub-window SWP2 may further include at least one of a hard coat, an anti-fingerprint layer, or an anti-reflection layer provided on the base layer. The hard coat, the anti-fingerprint layer, and the anti-reflection layer may be provided on the upper surface of the base layer of the second sub-window SWP2.

[0076] As Figure 4b shown, during the inner folding, stress concentrates in the folding area FA. The first sub-window SWP1 according to the present embodiment can be applied to the window WP to facilitate the replacement of the second sub-window SWP2 and improve the durability of the window WP. Therefore, defects due to stress generated during the inner folding can be prevented. A more detailed description will be made with reference to Figure 5a which will be described in more detail.

[0077] Referring to Figure 5a , the first sub-window SWP1 may include a base layer BL and an anti-fingerprint layer AFL provided on the upper surface of the base layer BL. The anti-fingerprint layer AFL may be formed differently according to regions.

[0078] The base layer BL may have a light transmittance of at least 90% or more. The base layer BL may include a plastic film. For example, the base layer BL may include polyimide, polycarbonate, polyamide, triacetyl cellulose, or polymethyl methacrylate. In an embodiment of the present invention, the base layer BL may include a glass substrate. The thickness of the base layer BL may be 250 μm or less.

[0079] The anti-fingerprint layer AFL controls the bonding force between the first sub-window SWP1 and the second sub-window SWP2 according to regions. The bonding force may be determined by the contact angle of the first sub-window SWP1, and the contact angle may vary according to the formation conditions of the anti-fingerprint layer AFL or the plasma treatment conditions of the anti-fingerprint layer AFL.

[0080] For ease of description, the region of the upper surface of the first sub-window SWP1 corresponding to the folding area FA and the regions of the upper surface of the first sub-window SWP1 corresponding to the peripheral areas NFA1 and NFA2 are respectively described as the folding area FA and the peripheral areas NFA1 and NFA2 of the first sub-window SWP1.

[0081] The contact angle of the folding area FA of the first sub-window SWP1 is smaller than that of each of the peripheral areas NFA1 and NFA2 of the first sub-window SWP1. This is because, depending on the folding area FA and the peripheral areas NFA1 and NFA2 of the first sub-window SWP1, the anti-fingerprint layer AFL has different conditions. Depending on the area, the anti-fingerprint layer AFL can have different film qualities, film densities, film thicknesses, occupied areas per unit area, etc. In Figure 5a an example of the anti-fingerprint layer AFL with a reduced thickness of the folding area FA is shown.

[0082] As Figure 5a shown, the anti-fingerprint layer AFL can substantially cover the peripheral areas NFA1 and NFA2. The folding area FA of the anti-fingerprint layer AFL has undergone a greater amount (e.g., time) of plasma treatment compared to each of the peripheral areas NFA1 and NFA2 of the anti-fingerprint layer AFL.

[0083] The joining force between the first sub-window SWP1 and the second sub-window SWP2 in the folding area FA that has undergone relatively deep plasma treatment is stronger than the joining force between the first sub-window SWP1 and the second sub-window SWP2 in the peripheral areas NFA1 and NFA2. The anti-fingerprint layer AFL is damaged by plasma treatment and, therefore, has a small contact angle due to a reduced atomic percentage (at%) of fluorine. The thickness of the folding area FA of the anti-fingerprint layer AFL can be reduced by plasma treatment.

[0084] In this embodiment, the anti-fingerprint layer AFL can include perfluoropolyether.

[0085] In Figure 6a the at% of fluorine is measured using XPS. The at% of each of fluorine, silicon, and oxygen is measured according to the area. According to Table 1, 4 points are measured on the peripheral areas NFA1 and NFA2, and 4 points are measured on the folding area FA.

[0086] Table 1

[0087]

[0088] Referring to Table 1, the atomic percentage (at%) of fluorine in the folding area FA is smaller than the atomic percentage of oxygen. The atomic percentage of silicon in the folding area FA increases compared to the peripheral areas NFA1 and NFA2. Referring to Figure 6b , as the plasma treatment time increases, the contact angle decreases and the joining force increases. In this embodiment, the contact angle of the folding area FA of the first sub-window SWP1 can be about 62° or less. The folding area FA of the first sub-window SWP1 is bonded to the adhesive layer ADL (see Figure 4a) The adhesion force can be above about 150 grams-force per inch (gf / inch). In this embodiment, the contact angle of each of the peripheral regions NFA1 and NFA2 of the first sub-window SWP1 can be above 112°. The contact angle of each of the peripheral regions NFA1 and NFA2 of the first sub-window SWP1 can be from 112° to 120°. The adhesion force of the folding region FA of the first sub-window SWP1 to the adhesive layer ADL (see Figure 4a ) can be about 4 gf / inch or less.

[0089] The adhesion force of the first sub-window SWP1 to the adhesive layer ADL in the region corresponding to the folding region FA can be at least 100 gf / inch or more greater than the adhesion force of the first sub-window SWP1 to the adhesive layer ADL in the region corresponding to each of the peripheral regions NFA1 and NFA2 of the first sub-window SWP1.

[0090] Reference will be made to Figure 4a describe the process of delaminating the first sub-window SWP1 from the second sub-window SWP2. As Figure 4a shown, in the unfolded state, a region corresponding to each of the peripheral regions NFA1 and NFA2 of the second sub-window SWP2 can be made to start separating. The second sub-window SWP2 having a relatively weak coupling force can be easily delaminated together with the adhesive layer ADL. As in the structure described in reference Figure 5a , since the region having a relatively large coupling force is restricted to the folding region FA, damage to the second sub-window SWP2 or the first sub-window SWP1 can be prevented during the process of delaminating the second sub-window SWP2.

[0091] As Figure 4b shown, during inner folding, large shear stresses occur in the folding region FA. Since the folding region FA has a relatively large coupling force, delamination of the first sub-window SWP1 and the second sub-window SWP2 due to the shear stress can be prevented.

[0092] As Figure 5b shown, the second sub-window SWP2 can include a base layer BL-1 and an anti-fingerprint layer AFL-1. Different from the anti-fingerprint layer AFL of the first sub-window SWP1, the anti-fingerprint layer AFL-1 of the second sub-window SWP2 can have substantially uniform conditions. The anti-fingerprint layer AFL-1 of the second sub-window SWP2 can have substantially uniform film quality, film density, film thickness, or the area occupied by the anti-fingerprint material per unit area, regardless of the region.

[0093] Figures 7a to 7d is a cross-sectional view showing a method for manufacturing a first sub-window according to an embodiment of the present invention. Figure 8a and Figure 8bIt is a plan view of mask MSK1 and MSK2 according to an embodiment of the present invention.

[0094] Referring to Figure 7a , first, a preliminary first window PWP1 formed with a preliminary anti-fingerprint layer AFL-P on a base layer BL is provided. A mask MSK1 is disposed on the preliminary first window PWP1. The mask MSK1 may include a plastic film, a polymer layer, a photoresistor, or stainless steel (SUS).

[0095] Next, the preliminary first window PWP1 is etched or plasma-treated. An etching solution EL such as a strong acid solution or a strong base solution may be used to etch the portion of the preliminary anti-fingerprint layer AFL-P exposed from the mask MSK1. A plasma gas PG such as hydrogen fluoride may be used to perform plasma treatment on the region of the preliminary anti-fingerprint layer AFL-P exposed from the mask MSK1. The preliminary anti-fingerprint layer AFL-P on the region exposed from the mask MSK1 may be partially removed or completely removed. In this embodiment, an example of completely removing the preliminary anti-fingerprint layer AFL-P is shown.

[0096] Thereafter, when the mask MSK1 is removed, a first sub-window SWP1 is formed.

[0097] Referring to Figure 7b , the above manufacturing method is substantially similar to Figure 7a 's manufacturing method. However, the planar shape of the mask MSK1 is partially different. Figure 7a Exemplarily, a mask MSK1 having an opening OP-M corresponding to a folding region FA is shown. According to this embodiment, the mask MSK1 provides a plurality of openings OP-M corresponding to the folding region FA. The planar shape of each of the plurality of openings OP-M may be the same as or different from each other.

[0098] The portion of the preliminary anti-fingerprint layer AFL-P exposed by the plurality of openings OP-M may be completely removed or partially removed. The anti-fingerprint layer AFL is not provided on at least a part of the folding region FA. The contact angle of the folding region FA of the anti-fingerprint layer AFL may be determined according to the degree of etching or plasma treatment.

[0099] Referring to Figure 8a , the plurality of openings OP-M are arranged in a predetermined rule. The region of the mask MSK1 corresponding to the folding region FA may be divided into two regions OA1 and OA2. In the second direction axis DR2, the surface area of the opening OP-M in each of the two regions OA1 and OA2 increases as the distance from the center M-C of the mask MSK1 or the distance from the folding region FA increases. As the surface area of the opening OP-M increases, the surface area of the anti-fingerprint layer AFL decreases. When using Figure 8aIn the anti-fingerprint layer AFL formed by the mask MSK1, the area adjacent to each of the peripheral regions NFA1 and NFA2 has the lowest occupied area per unit area. On the contrary, the bonding force of the area adjacent to each of the peripheral regions NFA1 and NFA2 is the largest. As described in reference Figure 4b Even when large shear stresses occur in the areas adjacent to each of the peripheral regions NFA1 and NFA2 of the folding region FA, delamination of the first sub-window SWP1 and the second sub-window SWP2 can be prevented.

[0100] Unlike Figure 7a and Figure 7b In the embodiment shown, the preliminary anti-fingerprint layer AFL-P can be patterned by etching or plasma treatment of a predetermined area without the mask MSK1.

[0101] Referring to Figure 7c First, a base layer BL is provided. A mask MSK2 is disposed on the base layer BL.

[0102] Next, an anti-fingerprint material AFM is applied on the base layer BL. The coating method can be any one of wet coating, dry coating, and inkjet coating. An anti-fingerprint layer AFL is formed except for the area where the mask MSK2 is disposed. The shape of the area where the anti-fingerprint layer AFL is not provided is determined according to the shape of the mask MSK2.

[0103] Thereafter, when the mask MSK2 is removed, the first sub-window SWP1 is formed.

[0104] Referring to Figure 7d The above manufacturing method is basically similar to Figure 7c However, a mask MSK2 with a different planar shape is used. Figure 7c An exemplary mask MSK2 corresponding to the folding region FA is shown. According to this embodiment, the mask MSK2 includes at least one opening OP-M provided to correspond to the folding region FA.

[0105] A partial area of the anti-fingerprint layer AFL can be formed on the area exposed by the opening OP-M. The anti-fingerprint layer AFL can be provided only on a part of the folding region FA.

[0106] Referring to Figure 8b, multiple mask patterns MSK-P are arranged in a predetermined rule. The region of the mask MSK2 corresponding to the folding region FA can be divided into two regions OA1 and OA2. On the second direction axis DR2, the surface area of the mask pattern MSK-P in each of the two regions OA1 and OA2 increases as the distance from the center M-C of the mask MSK2 or the distance from the folding region FA increases. As the surface area of the mask pattern MSK-P increases, the surface area of the anti-fingerprint layer AFL decreases.

[0107] In the anti-fingerprint layer AFL formed using Figure 8b the mask MSK2, the region adjacent to each of the peripheral regions NFA1 and NFA2 has the lowest occupied area per unit area. In the region of the first sub-window SWP1 corresponding to the folding region FA, the occupied area per unit area of the anti-fingerprint layer AFL in the region adjacent to each of the peripheral regions NFA1 and NFA2 is smaller than the occupied area per unit area of the anti-fingerprint layer AFL in the region corresponding to the center M-C of the folding region FA.

[0108] A method for detecting the reference Figures 7a to 7d described anti-fingerprint layer AFL is as follows. For example, the anti-fingerprint layer AFL according to the present embodiment can be detected by measuring the contact angle. In addition, according to the present embodiment, a heating type humidifier can be used to detect the anti-fingerprint layer AFL provided on the first sub-window SWP1. In addition, the XPS detection method can be used to detect the anti-fingerprint layer AFL. In addition, the transmission electron microscope (TEM) can be used to detect the anti-fingerprint layer AFL.

[0109] It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Therefore, the present invention is intended to cover modifications and variations of the present invention as long as they are within the scope of the appended claims and their equivalents.

[0110] Therefore, the technical scope of the present invention should not be limited to the content described in the detailed description of the specification, but should be determined by the claims.

[0111] Industrial Applicability

[0112] The development of a foldable display device is being initiated. A foldable display device including a window with enhanced durability and easy replacement is recognized to have industrial applicability. The life of the foldable display device can be extended by replacing only some components.

Claims

1. A foldable display device, comprising: A display panel; And A window, disposed on the display panel and including a folding area and a peripheral area, Wherein, the window includes: A first sub-window, including a first base layer with a light transmittance of 90% or more and a first anti-fingerprint layer disposed on the upper surface of the first base layer; A second sub-window, including a second base layer disposed on the first sub-window; and An adhesive layer, configured to couple the first sub-window to the second sub-window, wherein the contact angle of the area of the upper surface of the first sub-window corresponding to the folding area is smaller than the contact angle of the area of the upper surface of the first sub-window corresponding to the peripheral area.

2. The foldable display device according to claim 1, wherein, The contact angle of the area of the upper surface of the first sub-window corresponding to the folding area is 62° or less.

3. The foldable display device according to claim 2, wherein, The adhesion of the area of the upper surface of the first sub-window corresponding to the folding area to the adhesive layer is 150 gf / inch or more.

4. The foldable display device according to claim 1, wherein, The contact angle of the area of the upper surface of the first sub-window corresponding to the peripheral area is 112° or less.

5. The foldable display device according to claim 1, wherein, The first base layer includes polyimide, polycarbonate, polyamide, triacetyl cellulose, or polymethyl methacrylate.

6. The foldable display device according to claim 1, wherein, The second sub-window includes polyethylene terephthalate.

7. The foldable display device according to claim 1, wherein, The second sub-window further includes at least one of a hard coat, a second anti-fingerprint layer, and an anti-reflection layer disposed on the upper surface of the second base layer.

8. The foldable display device according to claim 1, wherein, The second sub-window further includes a second anti-fingerprint layer disposed on the upper surface of the second base layer, and The second anti-fingerprint layer overlaps with the folding area and the peripheral area and has a uniform thickness.

9. The foldable display device according to claim 1, wherein, The first anti-fingerprint layer includes perfluoropolyether.

10. The foldable display device according to claim 9, wherein, The atomic percentage of fluorine in the area of the first anti-fingerprint layer corresponding to the folding area is less than the atomic percentage of fluorine in the area of the first anti-fingerprint layer corresponding to the peripheral area.

11. The foldable display device according to claim 10, wherein, The atomic percentage of fluorine in the area of the first anti-fingerprint layer corresponding to the folding area is less than the atomic percentage of oxygen.

12. The foldable display device according to claim 1, wherein, The first anti-fingerprint layer is not disposed in at least a partial area of the area of the upper surface of the first sub-window corresponding to the folding area.

13. The foldable display device according to claim 1, wherein, In the area of the upper surface of the first sub-window corresponding to the folding area, the occupied area per unit area of the first anti-fingerprint layer in the area adjacent to the peripheral area is less than the occupied area per unit area of the first anti-fingerprint layer in the area corresponding to the center of the folding area.

14. The foldable display device according to claim 1, further comprising a color filter disposed on the display panel.

15. The foldable display device according to claim 1, further comprising an input sensor disposed on the display panel.

16. A foldable display device, comprising: A display panel; And A window, disposed on the display panel and including a folding area and a peripheral area, Wherein, the window includes: A first sub-window, including a first base layer with a light transmittance of 90% or more and a perfluoropolyether layer disposed on the upper surface of the first base layer; A second sub-window, disposed on the first sub-window; and An adhesive layer configured to couple the first sub-window to the second sub-window, wherein a contact angle of a region of an upper surface of the first sub-window corresponding to the folding region is smaller than a contact angle of a region of the upper surface of the first sub-window corresponding to the peripheral region.

17. The foldable display device according to claim 16, wherein, An adhesive force of the region of the upper surface of the first sub-window corresponding to the folding region to the adhesive layer is 150 grams-force per inch or more.

18. The foldable display device according to claim 17, wherein, The adhesive force of the region of the upper surface of the first sub-window corresponding to the folding region to the adhesive layer is more than 100 grams-force per inch greater than the adhesive force of the region of the upper surface of the first sub-window corresponding to the peripheral region to the adhesive layer.

19. The foldable display device according to claim 16, wherein, An atomic percentage of fluorine in a region of the perfluoropolyether layer corresponding to the folding region is smaller than an atomic percentage of fluorine in a region of the perfluoropolyether layer corresponding to the peripheral region.

20. The foldable display device according to claim 16, wherein, The perfluoropolyether layer is not provided in at least a partial region of the region of the upper surface of the first sub-window corresponding to the folding region.

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