Foldable display device

Abstract

To provide a foldable display device having a structure capable of covering bubbles which may be generated in a folding area.SOLUTION: A foldable display device includes: a display panel including a display area and a non-display area configured to surround the display area, the display panel including a folding area defined in the display area and the non-display area, and non-folding areas disposed at both sides of the folding area; a cover window disposed on the display panel so as to be smaller than the display panel; and a bonding layer disposed between the cover window and the display panel and configured to be brought into contact with a bottom surface of the cover window. An end of the bonding layer, in the folding area, protrudes beyond an end of the bonding layer disposed in the non-folding areas toward a folding axis. Therefore, even though bubbles are generated due to repeated folding operations, the bubbles are not visually recognized from the outside.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a foldable display, and more particularly to a foldable display with improved reliability. [Background technology]

[0002] As society has recently entered a full-fledged information age, the field of display devices that process and display large amounts of information has been developing rapidly. Display devices used in computer monitors, televisions, mobile phones, etc. include organic light emitting displays (OLEDs) that emit light themselves and liquid crystal displays (LCDs) that require a separate light source.

[0003] Display devices are now used in a wide variety of applications, including computer monitors, televisions, and even personal portable devices. Research is currently being conducted into display devices that have a large display area while being reduced in volume and weight.

[0004] In particular, flexible display devices that can display images even when bent or folded like paper have been drawing attention as the next generation of display devices. Flexible display devices use plastic thin film transistor substrates instead of glass and can be classified into unbreakable types that are highly durable, bendable types that can be bent without breaking, rollable types that can be rolled into a circle, and foldable types that can be folded. Flexible display devices have advantages in terms of space utilization, interior design, and design, and can be used in a variety of fields. Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a foldable display device having a structure capable of hiding air bubbles even if the air bubbles are generated in a folding area.

[0006] Another problem to be solved by the embodiments of the present specification is to provide a foldable display device with improved folding reliability.

[0007] The object of the present invention is not limited to the above-mentioned objects, and other objects not mentioned herein will be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, a foldable display device according to an embodiment of the present specification includes a display panel including a display area and a non-display area surrounding the display area, a folding area defined in the display area and the non-display area, and non-folding areas on both sides of the folding area, a cover window disposed on the display panel to have a size smaller than the display panel, and an adhesive layer disposed between the cover window and the display panel and in contact with a lower surface of the cover window, and an end of the adhesive layer in the folding area may be disposed to protrude in a folding direction compared to an end of the adhesive layer disposed in the non-folding area. Therefore, even if air bubbles are generated due to repeated folding operations in a folding reliability test, they cannot be visually recognized from the outside, thereby reducing the defect rate.

[0009] Other specific details of the embodiments are included in the detailed description and drawings. Effect of the Invention

[0010] According to an embodiment of the present specification, in the folding region of the display device, an end of the adhesive layer disposed under the cover window is aligned with an end of the cover window, thereby preventing air bubbles generated in the folding region from being visible on the entire surface.

[0011] According to the embodiments of the present disclosure, the reliability of the display device can be improved.

[0012] The effects of the embodiments of the present specification are not limited to those exemplified above, and various other effects are included within the present specification. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a plan view of a foldable display device according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a plan view showing the arrangement of components of a foldable display device according to an embodiment of the present disclosure. [Diagram 3] FIG. 3 is a cross-sectional view taken along line III-III' in FIG. [Figure 4] FIG. 11 is a plan view showing the arrangement of components of a foldable display device according to another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The advantages and features of the present specification, and the methods for achieving them, will become apparent from the following detailed description of the embodiments in conjunction with the accompanying drawings. However, the present specification is not limited to the embodiments disclosed below, and may be embodied in various different forms, but the embodiments are provided to complete the disclosure of the present specification and to fully convey the scope of the invention to those skilled in the art to which the present specification pertains.

[0015] The shapes, areas, ratios, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of this specification are illustrative only and are not limited to the matters shown in the drawings of this specification. The same reference symbols refer to the same components throughout the specification. In addition, in explaining the present invention, if it is determined that a detailed description of related prior art may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. When "comprises," "has," "is," etc. are used in the present invention, other parts may be added unless "only" is used. When a component is expressed in the singular, it includes a plural unless otherwise explicitly stated.

[0016] When interpreting elements, they are interpreted as including a margin of error even if there is no other explicit description.

[0017] When describing a positional relationship, for example when the positional relationship between two parts is described as "on," "at the top," "below," "to the side," etc., one or more other parts may be located between the two parts, unless "immediately" or "directly" is used.

[0018] When an element or layer is referred to as "on" another element or layer, it includes either being directly on the other element, or having other layers or elements interposed therebetween.

[0019] In addition, although the terms "first", "second", etc. are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another. Therefore, the first component referred to below may also be the second component within the technical concept of the present invention.

[0020] Like reference numbers refer to like elements throughout the specification.

[0021] The area and thickness of each component shown in the drawings are shown for convenience of explanation, and the present invention is not necessarily limited to the area and thickness of the components shown in the drawings.

[0022] The features of the various embodiments of this specification may be combined or combined with each other, either partially or in whole, and various technical interlocking and driving mechanisms may be possible, and each embodiment may be implemented independently of each other or may be implemented together in a linked relationship.

[0023] Various embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings.

[0024] FIG. 1 is a plan view of a foldable display device according to an embodiment of the present disclosure.

[0025] 1, a foldable display device 100 according to an embodiment of the present specification may include a display panel for displaying an image, and may include a display area DA and a non-display area NDA, which are defined depending on whether an image is displayed or not.

[0026] The display area DA may be an area in which a plurality of pixels are arranged and an image is substantially displayed. In the display area DA, a plurality of pixels including a light-emitting area for displaying an image, and a thin film transistor, a capacitor, and the like for driving the pixels may be arranged. One pixel may include a plurality of sub-pixels SP. The sub-pixel SP is the smallest unit constituting the display area DA, and each sub-pixel SP may be configured to emit light of a specific wavelength band. For example, each sub-pixel SP may be configured to emit red, green, blue, or white light.

[0027] The non-display area NDA may be disposed to surround the display area DA. The non-display area NDA is an area where an image is not actually displayed, and may include various wirings, driving ICs, printed circuit boards, etc. for driving pixels and driving circuits disposed in the display area DA. For example, various ICs such as gate driver ICs and data driver ICs, VSS wiring, etc. may be disposed in the non-display area NDA.

[0028] The display panel of the foldable display device 100 according to the embodiment of the present specification may include a folding area FA defined depending on whether folding is possible and non-folding areas NFA1 and NFA2 on both sides of the folding area. For example, the foldable display device 100 may include a first non-folding area NFA1, a folding area FA, and a second non-folding area NFA2 arranged in sequence along a vertical direction of a folding axis F, i.e., a Y-axis direction.

[0029] The folding area FA is an area that is folded when folding the foldable display device 100, and may include a part of the display area DA and a part of the non-display area NDA. The folding area FA may be folded with a specific radius of curvature based on a perpendicular direction of a folding axis F of the folding area, for example, the Y-axis direction in FIG. 1. When the folding area FA is folded based on a direction perpendicular to the folding axis F, a part of a circle or an ellipse may be formed in the folding area FA. The radius of curvature of the folding area FA may mean a radius corresponding to a part of a circle or an ellipse formed by the folding area FA.

[0030] The first non-folding area NFA1 and the second non-folding area NFA2 may be areas that are not folded when folding the foldable display device 100. For example, the first non-folding area NFA1 and the second non-folding area NFA2 may be areas that maintain a planar state when folding the foldable display device 100. The first non-folding area NFA1 and the second non-folding area NFA2 may each include a part of the display area DA and a part of the non-display area NDA. When the folding area FA is folded based on the folding direction, the first non-folding area NFA1 and the second non-folding area NFA2 may overlap each other.

[0031] The detailed configuration of the foldable display device 100 according to an embodiment of the present specification will be considered below.

[0032] Fig. 2 is a plan view showing the arrangement of components of a foldable display device according to an embodiment of the present disclosure. Fig. 3 is a cross-sectional view taken along line III-III' in Fig. 2. For ease of explanation, Fig. 2 shows only the first protective film 110, the third adhesive layer 145, the cover window 140, the display panel 160, and the bottom plate 190 among various components of the foldable display device 100.

[0033] Referring to Figures 2 and 3, a foldable display device 100 according to an embodiment of the present specification may include a first protective film 110, a first adhesive layer 115, a second protective film 120, a second adhesive layer 125, a black matrix layer 130, a cover window 140, a third adhesive layer 145, a polarizing plate 150, a fourth adhesive layer 155, a display panel 160, a fifth adhesive layer 165, a base plate 170, a sixth adhesive layer 175, a top plate 180, a seventh adhesive layer 185 and a bottom plate 190.

[0034] The first protective film 110 is disposed on the entire surface of the foldable display device 100 and can protect the cover window 140 and the display panel 160 from external impact. The first protective film 110 can include a first hard coating layer 111 and a protective layer 112. The first hard coating layer 111 coats the protective layer 112, and the protective layer 112 can be made of a soft plastic for folding. For example, the first protective film 110 has a thin thickness, for example, a thickness of 5 μm or less, and can effectively relieve folding stress applied when the foldable display device 100 is folded. A first adhesive layer 115 is disposed on the lower surface of the first protective film 110.

[0035] The first adhesive layer 115 may be disposed between the first protective film 110 and the second protective film 120, and may adhere the first protective film 110 and the second protective film 120. The first adhesive layer 115 may be disposed in accordance with the length of the first protective film 110. For example, the first adhesive layer 115 may be disposed for the same length as the length of the first protective film 110. The first adhesive layer 115 may be made of a transparent adhesive material and may be a thermosetting or natural curing adhesive. For example, the first adhesive layer 115 may be made of, but is not limited to, an OCA (Optical Clear Adhesive), a PSA (Pressure Sensitive Adhesive), or the like.

[0036] The second protective film 120 is disposed under the first protective film 110 and can protect the cover window 140 and the display panel 160. The second protective film 120 can be larger than the first protective film 110.

[0037] The second protective film 120 may include a second hard coating layer 121 and a shatterproof layer 122. The second hard coating layer 121 may be disposed on the upper surface of the lower shatterproof layer 122 and coat the shatterproof layer 122. The shatterproof layer 122 has a cushioning effect to prevent the first protective film 110 and the second protective film 120 from being damaged by an external impact, and may prevent fragments from scattering even if damage occurs. The shatterproof layer 122 may be configured to include polyurethane or a silicone-based resin. A second adhesive layer 125 and a black matrix layer 130 may be disposed on the lower surface of the second protective film 120.

[0038] The second adhesive layer 125 is disposed between the second protective film 120 and the cover window 140, and can adhere the second protective film 120 and the cover window 140. The second adhesive layer 125 is made of a transparent adhesive material and can be a thermosetting or natural curing adhesive. For example, the second adhesive layer 125 can be made of, but is not limited to, an OCA (Optical Clear Adhesive), a PSA (Pressure Sensitive Adhesive), etc.

[0039] The black matrix layer BM130 may be disposed on the lower surface of the second protective film 120 in correspondence with the non-display area NDA. The black matrix layer 130 may include a light absorbing material, for example, a light absorbing metal, carbon black, black resin, etc. As a result, components such as wiring disposed in the non-display area NDA may not be visible from the outside. In addition, the black matrix layer 130 serves to prevent light leakage from the side of the foldable display device 100.

[0040] The cover window 140 protects the display panel 160 from external impacts and scratches. The cover window 140 may be made of a transparent material that is highly resistant to impacts and scratches. The cover window 140 also protects the display panel 160 from moisture penetrating from the outside.

[0041] The cover window 140 may be made of a foldable soft plastic series to provide a thin and flexible display device 100. For example, the cover window 140 may be a film made of a polymer such as polyimide, polyamide-imide, polyethyleneterephthalate, polymethylmethacrylate, polypropylene glycol, or polycarbonate.

[0042] The cover window 140 may be disposed to be smaller than the second protective film 120 in consideration of an attachment tolerance between the first protective film 110 and the second protective film 120. For example, an end of the cover window 140 may be located more inward than an end of the second protective film 120. A third adhesive layer 145 may be disposed on the lower surface of the cover window 140.

[0043] The third adhesive layer 145 is disposed between the cover window 140 and the polarizer 150 to adhere the cover window 140 and the polarizer 150. The third adhesive layer 135 is made of a transparent adhesive material and may be a thermosetting or natural curing adhesive. For example, the third adhesive layer 135 may be made of, but is not limited to, OCA (Optical Clear Adhesive).

[0044] The third adhesive layer 145 may be disposed with different lengths in the folding region FA and the non-folding region NFA. For example, as shown in Fig. 2, the third adhesive layer 145 may be disposed to be enlarged in the folding region FA compared to the non-folding region NFA. For example, an end of the third adhesive layer 145 in the folding region FA may be disposed to protrude beyond an end of the third adhesive layer 145 in the non-folding region NFA.

[0045] The third adhesive layer 145 may be disposed to have a longer length in the folding region FA than in the non-folding region NFA. For example, as shown in FIG. 2, an end of the third adhesive layer 145 in the folding region FA may coincide with an end of the cover window 140, and an end of the third adhesive layer 145 in the non-folding region NFA may be located inside the end of the cover window 140 in the folding direction.

[0046] The polarizing plate 150 may be provided in the display panel 160 to enhance optical characteristics. The polarizing plate 150 may be, but is not limited to, a polarizing film, a polarizing layer, and the like. The polarizing plate 150 selectively transmits light and reduces reflection of external light incident on the display panel 160. For example, the display panel 160 is provided with various metal materials that are applied to semiconductor devices, wiring, light emitting devices, and the like. External light incident on the display panel 160 may be reflected by the metal materials of the display panel 160, and such reflection of external light may reduce visibility of the display panel 160. However, by providing the polarizing plate 150, the outdoor visibility of the foldable display device 100 may be improved by reflection of external light.

[0047] The polarizing plate 150 may be larger than the cover window 140. For example, an end of the polarizing plate 150 may be located outside an end of the cover window 140. The polarizing plate 150 may be omitted depending on the embodiment of the foldable display device 100. A fourth adhesive layer 155 is disposed on the lower surface of the polarizing plate 150.

[0048] The fourth adhesive layer 155 may be disposed between the polarizer 150 and the display panel 160 to adhere the polarizer 150 to the display panel 160. The fourth adhesive layer 155 may be disposed in accordance with the size of the polarizer 150. For example, an end of the fourth adhesive layer 155 may coincide with an end of the polarizer 150.

[0049] The fourth adhesive layer 155 may be made of a transparent adhesive material, and may be a thermosetting or natural curing adhesive, for example, an OCA (Optical Clear Adhesive), a PSA (Pressure Sensitive Adhesive), or the like, but is not limited thereto.

[0050] The display panel 160 is a panel on which an image is realized, and may include light emitting elements for realizing an image and a circuit unit for driving the light emitting elements. For example, when the display panel 160 is an organic light emitting display panel, the light emitting elements may be organic light emitting elements. The circuit unit may include various thin film transistors, capacitors, wiring, driving ICs, etc. for driving the light emitting elements. For example, the circuit unit may include various configurations such as, but is not limited to, a driving thin film transistor, a switching thin film transistor, a storage capacitor, a gate wiring, a data wiring, a gate driver IC, and a data driver IC.

[0051] The display panel 160 is a flexible substrate on which driving thin film transistors and light emitting elements are formed, sealed by a sealing part, and may include a flexible substrate with a very thin thickness to realize flexibility, and light emitting elements arranged on the flexible substrate.

[0052] The flexible substrate may be made of an insulating material having flexibility, for example, an insulating plastic substrate selected from polyimide, polyethersulfone, polyethylene terephthalate, and polycarbonate. Since the plastic substrate has a relatively weak barrier property against moisture and oxygen, the flexible substrate may have a structure in which a plastic film and an inorganic film are laminated to compensate for this. For example, the flexible substrate may include, but is not limited to, a multi-layer structure in which a first plastic film, an inorganic film, and a second plastic film are laminated in order.

[0053] A driving thin film transistor for driving the light emitting element may be disposed on the flexible substrate. The driving thin film transistor may be disposed in each of the plurality of pixel regions. For example, the driving thin film transistor may include a gate electrode, an active layer, a source electrode, and a drain electrode. For example, the driving thin film transistor may further include a gate insulating layer for insulating the gate electrode from the active layer, and may further include an interlayer insulating layer for insulating the gate electrode from the source electrode and the drain electrode. A planarization layer may be disposed on the driving thin film transistor to planarize an upper surface. A light emitting element may be disposed on the planarization layer, and the light emitting element may be an organic light emitting element. In the organic light emitting element, holes injected from the anode and electrons injected from the cathode are combined in the organic light emitting layer to emit light. Images may be displayed using the light emitted in this manner.

[0054] Although a flexible substrate has excellent folding characteristics, it is thin and has lower rigidity than a glass substrate or a metal substrate, so that it may be difficult to maintain a constant shape when folded, which may cause sagging. In order to support the flexible substrate and improve impact resistance, a base plate 170, a top plate 180, and a bottom plate 190 may be disposed under the display panel 160. A fifth adhesive layer 165 may be disposed on the lower surface of the display panel 160.

[0055] The fifth adhesive layer 165 is disposed between the display panel 160 and the base plate 170, and can adhere the display panel 160 to the base plate 170. The fifth adhesive layer 165 is made of a transparent adhesive material and can be a thermosetting or natural curing adhesive. For example, the fifth adhesive layer 165 can be made of, but is not limited to, an OCA (Optical Clear Adhesive), a PSA (Pressure Sensitive Adhesive), etc.

[0056] The base plate 170 may be disposed under the display panel 160. The base plate 170 may be disposed between the display panel 160 and the top plate 180, and a plurality of hole patterns H may be provided in the bottom plate 190 to prevent the display screen from being transferred or distorted. The base plate 170 may be made of a polymer such as polyimide (PI), polymethylmethacrylate (PDMA), polycarbonate (PC), polyvinylalcohol (PVA), acrylonitrile-butadiene-styrene (ABS), polyethylene terephthalate (PET), silicone, or polyurethane (PU). The base plate 170 may be attached to the top plate 180 by a sixth adhesive layer 175.

[0057] The sixth adhesive layer 175 is disposed between the base plate 170 and the top plate 180, and can adhere the base plate 170 and the top plate 180. The sixth adhesive layer 175 is made of a material having adhesive properties and can be a thermosetting or natural curing adhesive. For example, the sixth adhesive layer 175 can be made of, but is not limited to, an OCA (Optical Clear Adhesive), a PSA (Pressure Sensitive Adhesive), or the like.

[0058] The top plate 180 is disposed under the base plate 170 and can enhance the rigidity of the display panel 160. The top plate 180 can prevent a phenomenon in which a plurality of hole patterns H formed in a bottom plate 190 disposed under the top plate 180 are viewed through the display panel 160.

[0059] The top plate 180 may be made of an amorphous metal. An amorphous metal refers to a material that is solidified in a state where atoms are arranged in an amorphous manner, like glass or liquid, and is formed when crystal growth is prevented when a metal raw material is rapidly cooled. Amorphous metals are generally superior to crystalline metals having regular atomic arrangements in terms of corrosion resistance and elasticity. For example, the top plate 180 may include any one of the amorphous metals selected from the group consisting of nickel, iron, cobalt, palladium, silicone, magnesium, zirconium, titanium, calcium, copper, platinum, gold, and combinations thereof. The top plate 180 may be attached to the bottom plate 190 by a seventh adhesive layer 185.

[0060] The seventh adhesive layer 185 is disposed between the top plate 180 and the bottom plate 190 to attach the top plate 180 and the bottom plate 190. The seventh adhesive layer 185 may be disposed so as not to overlap the plurality of hole patterns H of the bottom plate 190, since the bottom plate 190 has a plurality of hole patterns H for elastic deformation due to folding. The seventh adhesive layer 185 is made of a material having adhesive properties and may be a thermosetting or natural curing adhesive. For example, the seventh adhesive layer 185 may be made of, but is not limited to, an OCA (Optical Clear Adhesive), a PSA (Pressure Sensitive Adhesive), or the like.

[0061] The bottom plate 190 may be disposed under the top plate 180. The bottom plate 190 may be made of a metal material such as stainless steel (SUS), stainless steel (SUS) containing a metal such as nickel (Ni), iron (Fe), aluminum (Al) series, or magnesium (Mg). The bottom plate 190 may be made of stainless steel (SUS), but is not limited thereto. For example, stainless steel (SUS) has a high restoring force and rigidity, and can maintain high rigidity even if the thickness of the bottom plate 190 is reduced. For example, the bottom plate 190 may be made of a polymer such as polymethylmethacrylate (PDMA), polycarbonate (PC), polyvinylalcohol (PVA), acrylonitrile-butadiene-styrene (ABS), polyethylene terephthalate (PET), silicone, or polyurethane (PU). The bottom plate 190 supports the display panel 160 and at the same time reduces the overall thickness of the foldable display device 100 and the radius of curvature of the folding area FA.

[0062] A plurality of hole patterns H for reducing stress caused by folding of the foldable display device 100 may be arranged on the bottom plate 190. The plurality of hole patterns H may be arranged corresponding to the folding area FA of the foldable display device 100. In FIG. 3, the plurality of hole patterns H are shown to correspond to the display area DA, but are not limited thereto, and may be formed corresponding to the folding area FA, and may be formed in a part of the display area DA, or the entire surface or a part of the display area DA and the non-display area NDA in the folding area FA.

[0063] In a typical foldable display device, a cover window having a size smaller than that of the second protective film is attached in consideration of attachment tolerance during the process of attaching a first protective film, a second protective film, a cover window, a polarizing plate, and a display panel, and a third adhesive layer is arranged so that the third adhesive layer attached to the lower surface of the cover window has a length shorter than that of the cover window.

[0064] Since the third adhesive layer 145 is arranged to have a length shorter than the length of the cover window 140, when the folding operation is repeated for a folding test of the foldable display device, microscopic bubbles are generated in the third adhesive layer due to folding stress, and the size of the microscopic bubbles increases due to the repeated folding operation, causing them to come off the black matrix 130 layer and become visible from the outside.

[0065] The inventors of the present specification have recognized the above-mentioned problems and conducted various studies and experiments to reduce the visibility of bubbles in the adhesive layer generated in the folding region of the display device. Through various studies and tests, they have invented a display device that can reduce the visibility of bubbles in the adhesive layer generated in the folding region and improve reliability, which will be described below.

[0066] In the foldable display device 100 according to an embodiment of the present specification, the third adhesive layer 145 is disposed to coincide with an end of the cover window 140 only in the folding area FA, and in the non-folding area NFA, the end of the third adhesive layer 145 may be disposed to be located inside the cover window 140 in consideration of an attachment tolerance. As a result, the foldable display device 100 according to an embodiment of the present specification may improve folding reliability by preventing air bubbles in the adhesive layer generated in the folding area FA from being visible from the outside.

[0067] Fig. 4 is a plan view showing the arrangement of components of a foldable display device according to another embodiment of the present specification. Fig. 4 illustrates only a protective film 110, a cover window 140, an adhesive layer 445, a display panel 160, and a bottom plate 190 in order to explain the features of another embodiment of the present specification. The foldable display device 400 of Fig. 4 differs from the foldable display device 100 of Fig. 2 only in the cover window 140 and the adhesive layer 445 that adheres the polarizing plate, and other configurations are substantially the same, so duplicated explanations will be omitted.

[0068] Referring to FIG. 4, a foldable display device 400 according to another embodiment of the present specification may include a first protective film 110, a cover window 140 arranged at the bottom of the first protective film 110, an adhesive layer 445 arranged on the bottom surface of the cover window 140, a display panel 160 arranged at the bottom of the cover window 140, and a bottom plate 190 arranged at the bottom of the display panel 160.

[0069] The adhesive layer 445 is disposed on the lower surface of the cover window 140 and can adhere the cover window 140 to the polarizing plate 150. The adhesive layer 445 is made of a transparent adhesive material and can be a thermosetting or natural curing adhesive. For example, the adhesive layer 445 can be made of, but is not limited to, an OCA (Optical Clear Adhesive), a PSA (Pressure Sensitive Adhesive), etc.

[0070] The adhesive layer 445 may be disposed with different lengths in the folding region FA and the non-folding region NFA, for example, the adhesive layer 445 may be disposed with a longer extended length in the folding region FA than in the non-folding region NFA.

[0071] In the folding region FA, the adhesive layer 445 may be arranged to be expanded compared to the non-folding region NFA, and may be arranged to have a length that gradually becomes shorter as it approaches the non-folding region NFA around the folding axis F. For example, in the folding region FA, the adhesive layer 445 may be arranged such that an end of the adhesive layer 445 coincides with an end of the cover window 140 since the folding axis F receives the maximum folding stress, and the end of the adhesive layer 445 may be arranged to be gradually positioned more inward than the end of the cover window 140 as it approaches the non-folding region NFA. For example, in the folding region FA, the adhesive layer 445 arranged in the region that coincides with the folding axis F may have the longest length, and the length of the adhesive layer 445 arranged in the folding region FA closest to the non-folding region NFA may be the shortest in the folding region FA.

[0072] In another embodiment of the present specification, the foldable display device 400 has adhesive layers 445 arranged on the underside of the cover window 140 in the folding area FA and the non-folding area NFA, and in the folding area FA, the adhesive layer 445 at the folding axis F is arranged to coincide with the end of the cover window 140, and the end of the adhesive layer 445 is gradually positioned further inward from the end of the cover window 140 as it approaches the non-folding area NFA, thereby preventing air bubbles generated due to folding stress from being visible from the outside and improving the efficiency of the attachment tolerance.

[0073] A foldable display device according to an embodiment of the present disclosure can be described as follows.

[0074] A foldable display device according to an embodiment of the present specification may include a display panel including a display area and a non-display area surrounding the display area, and including a folding area defined in the display area and the non-display area and non-folding areas on both sides of the folding area; a cover window arranged on the display panel to have a size smaller than the display panel; and an adhesive layer arranged between the cover window and the display panel and in contact with a lower surface of the cover window, and in the folding area, an end of the adhesive layer may be arranged to protrude in the folding direction compared to an end of the adhesive layer arranged in the non-folding area.

[0075] According to some embodiments of the present specification, in the folding region, the end of the adhesive layer may coincide with the end of the cover window, and in the non-folding region, the end of the adhesive layer may be located inside the cover window relative to the end of the cover window.

[0076] According to some embodiments herein, in the folding region, the region where the end of the adhesive layer coincides with the end of the cover window may be the region corresponding to the folding axis.

[0077] According to some embodiments of the present disclosure, an end of the adhesive layer disposed in the folding region closest to the non-folding region may be disposed outside the cover window relative to an end of the adhesive layer disposed in the non-folding region, and may be disposed inside the cover window relative to an end of the adhesive layer disposed in the region corresponding to the folding axis.

[0078] According to some embodiments of the present specification, in the folding region, an end of an adhesive layer between the adhesive layer arranged closest to the non-folding region and the adhesive layer arranged corresponding to the folding axis may be arranged so as to gradually become closer to the inside of the cover window between the end of the adhesive layer arranged closest to the non-folding region and the end of the adhesive layer arranged corresponding to the folding axis.

[0079] According to some embodiments herein, the adhesive layer can be an Optical Clear Adhesive (OCA).

[0080] According to some embodiments of the present specification, the display device may further include a protective film disposed on the cover window, and a black matrix layer disposed on the lower surface of the protective film corresponding to the non-display area, and an end of the adhesive layer in the folding area may be disposed overlapping the black matrix layer.

[0081] According to some embodiments of the present specification, the protective film may include a first protective film disposed on the cover window and covering the entire surface, and a second protective film disposed between the first protective film and the cover window and including a shatterproof layer.

[0082] According to some embodiments herein, the second protective film may have a size larger than the cover window.

[0083] According to some embodiments of the present specification, the display device further includes a bottom plate arranged under the display panel to support the display panel, and the bottom plate may have a plurality of hole patterns arranged thereon to reduce folding stress.

[0084] According to some embodiments of the present disclosure, the display device may further include a polarizer disposed between the adhesive layer and the display panel, and the adhesive layer may bond the cover window and the polarizer.

[0085] According to some embodiments of the present specification, a display device includes a display panel including a folding area in which a folding axis is located and non-folding areas on both sides of the folding area, a cover window arranged on the display panel, and an adhesive layer arranged between the cover window and the display panel and in contact with a lower surface of the cover window, and in the folding axis direction, the length of the adhesive layer arranged in the folding area can be greater than the length of the adhesive layer arranged in the non-folding area.

[0086] According to some embodiments of the present disclosure, a display device includes a display panel including a first non-folding area, a second non-folding area, and a folding area disposed between the first non-folding area and the second non-folding area, a cover window disposed on the display panel and having a size smaller than the display panel, and an adhesive layer disposed between the cover window and the display panel and including a first folding stress reduction portion, wherein the first folding stress reduction portion extends from a side edge of a peripheral portion of the adhesive layer in the folding area, and at least a portion of the first folding stress reduction portion is disposed flush with an edge of the cover window disposed in the folding area, and wherein the adhesive layer can have a size smaller than the cover window in the first non-folding area and the second non-folding area.

[0087] According to some embodiments herein, the first folding stress reducer may be rectangular or circular in shape.

[0088] According to some embodiments of the present disclosure, the display device may further include a protective film disposed on the cover window, and a black matrix disposed under the protective film.

[0089] According to some embodiments herein, the first folded stress reducing portion of the adhesive layer may overlap the black matrix.

[0090] According to some embodiments of the present specification, the protective film may include a first protective film disposed on top of the cover window, and a second protective film disposed between the first protective film and the cover window and including a shatterproof layer.

[0091] According to some embodiments herein, the second protective film may have a size larger than the cover window.

[0092] According to some embodiments of the present disclosure, the display device may further include a second folding stress reduction portion provided on a bottom plate disposed under the display panel, and a plurality of holes may be formed in the second folding stress reduction portion.

[0093] Although the embodiments of the present specification have been described in more detail with reference to the accompanying drawings, the present specification is not necessarily limited to such embodiments, and various modifications can be made within the scope of the technical idea of ​​the present specification. Therefore, the embodiments disclosed in the present specification are for illustration purposes, not for limiting the technical idea of ​​the present invention, and the scope of the technical idea of ​​the present specification is not limited by such embodiments. Therefore, it should be understood that the embodiments described above are illustrative and not restrictive in all respects. The scope of protection of the present specification should be interpreted according to the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present specification.

Claims

1. a display panel including a display area and a non-display area surrounding the display area, the display area including a folding area defined in the display area and the non-display area, and a non-folding area on both sides of the folding area; a cover window disposed on the display panel so as to have a size smaller than that of the display panel; an adhesive layer disposed between the cover window and the display panel and in contact with a lower surface of the cover window; A foldable display device, wherein in the folding region, an end of the adhesive layer is positioned to protrude in the folding direction compared to an end of the adhesive layer positioned in the non-folding region.

2. In the folding region, an end of the adhesive layer coincides with an end of the cover window; The foldable display device according to claim 1 , wherein in the non-folding region, an end of the adhesive layer is located more inward than an end of the cover window.

3. The foldable display device according to claim 2 , wherein in the folding region, a region where an end of the adhesive layer coincides with an end of the cover window corresponds to a folding axis.

4. 4. The foldable display device of claim 3, wherein an end of the adhesive layer disposed in the folding region closest to the non-folding region is disposed more outwardly of the cover window than an end of the adhesive layer disposed in the non-folding region, and an end of the adhesive layer disposed in the region corresponding to the folding axis is disposed so as to be closest to the non-folding region and to coincide with an end of the cover window.

5. 5. The foldable display device of claim 4, wherein in the folding region, an end of an adhesive layer between the adhesive layer closest to the non-folding region and the adhesive layer corresponding to the folding axis is arranged so as to gradually approach the inside of the cover window between the end of the adhesive layer closest to the non-folding region and the end of the adhesive layer corresponding to the folding axis.

6. The foldable display device according to claim 5 , wherein the adhesive layer is an optical clear adhesive (OCA).

7. a protective film disposed on the cover window; The foldable display device of claim 1 , further comprising: a black matrix layer disposed on the lower surface of the protective film corresponding to the non-display area.

8. The foldable display device according to claim 7 , wherein an end of the adhesive layer in the folding region is disposed so as to overlap the black matrix layer.

9. The protective film is a first protective film disposed on the cover window and forming a front surface; The foldable display device according to claim 7 , further comprising: a second protective film disposed between the first protective film and the cover window, the second protective film including a shatterproof layer.

10. The foldable display device according to claim 9 , wherein the second protective film is larger than the cover window.

11. a bottom plate disposed under the display panel to support the display panel; The foldable display device according to claim 1 , wherein the bottom plate is arranged with a plurality of hole patterns for reducing folding stress.

12. The display device further includes a polarizing plate disposed between the adhesive layer and the display panel. The foldable display device of claim 1 , wherein the adhesive layer bonds the cover window and the polarizer.

13. a display panel including a folding area in which a folding axis is disposed and non-folding areas on both sides of the folding area; a cover window disposed on the display panel; an adhesive layer disposed between the cover window and the display panel and in contact with a lower surface of the cover window; A foldable display device, wherein in the direction of the folding axis, the length of the adhesive layer disposed in the folding region is greater than the length of the adhesive layer disposed in the non-folding region.

14. a display panel including a first non-folding area, a second non-folding area, and a folding area disposed between the first non-folding area and the second non-folding area; a cover window disposed on the display panel and having a size smaller than the display panel; an adhesive layer disposed between the cover window and the display panel, the adhesive layer including a first folding stress reducing portion; the first folding stress relief portion extends from a side edge of the periphery of the adhesive layer in the folding region; At least a portion of the first folding stress reducing portion is disposed flush with an edge of the cover window disposed in the folding region; A foldable display device, wherein in the first non-folding region and the second non-folding region, the adhesive layer has a size smaller than the cover window.

15. The foldable display device according to claim 14 , wherein the first folding stress reducing portion is in the shape of a rectangle or a partial circle.

16. a protective film disposed on the cover window; The foldable display device of claim 14 , further comprising a black matrix disposed under the protective film.

17. The foldable display device of claim 16 , wherein the first folding stress reducing portion of the adhesive layer overlaps the black matrix.

18. The protective film is a first protective film disposed on an upper portion of the cover window; The foldable display device of claim 17 , further comprising a second protective film disposed between the first protective film and the cover window, the second protective film including a shatterproof layer.

19. The foldable display device according to claim 18 , wherein the second protective film has a size larger than the cover window.

20. The display panel further includes a second folding stress reducing portion provided on a bottom plate disposed under the display panel, The foldable display device of claim 14 , wherein the second folding stress reducing portion has a plurality of holes formed therein.

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