Display device

Abstract

The present disclosure relates to a display device including: a cover window; a display module disposed below the cover window and including a display area, a non-display area, and a bending area between the display area and the non-display area, the non-display area bending in a direction opposite to the cover window; a first cover layer corresponding to the bending area and disposed on the display module; and a second cover layer covering the side surface of the display module and the first cover layer and connecting the first cover layer and the cover window.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Korean Patent Application No. 10-2023-0117522 filed in Korea on September 5, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to a display device, and more particularly, to a display device capable of preventing cracks from occurring in a bending region due to stress concentration. Background Art

[0004] There is an increasing demand for flat display devices that occupy a small area. Among the flat display devices, the technology of organic light emitting display devices including organic light emitting diodes (OLEDs) is rapidly developing.

[0005] OLED includes a cathode as an electron injection electrode, an anode as a hole injection electrode, and an organic light-emitting layer disposed between the cathode and the anode and including a host and a dopant. When electrons from the cathode and holes from the anode enter the organic light-emitting layer, the electrons and holes combine to generate excitons, and the excitons are transformed from an excited state to a ground state. Thus, light is emitted from the OLED. OLED can be formed on a flexible transparent substrate, for example, a plastic substrate, and can be driven by a low voltage, for example, 10V. In addition, OLED has low power consumption and high color purity.

[0006] Recently, flexible display devices have been introduced. For example, in order to reduce the frame area, the display device can be bendable with respect to a bending area, which may be an area between a display area and a non-display area.

[0007] However, in the flexible display device, there is a problem that stress caused by a bending operation causes damage to the signal line in the bending area. Summary of the invention

[0008] Accordingly, embodiments of the present disclosure are directed to a display device that substantially obviates one or more problems associated with limitations and disadvantages of the related art.

[0009] An object of the present disclosure is to provide a display device capable of preventing cracks from occurring in a bending region due to stress concentration.

[0010] Additional features and aspects will be described in the following description, and in part will be apparent from the description, or may be learned by practicing the disclosed concepts provided herein. Other features and aspects of the disclosed concepts may be realized and obtained by structures specifically pointed out in the written description, derived content, its claims, and the accompanying drawings.

[0011] To achieve these advantages and other advantages according to the purposes of an embodiment of the present disclosure, as described herein, one aspect of the present disclosure is a display device, comprising: a cover window; a display module, the display module being disposed below the cover window and comprising a display area, a non-display area, and a curved area between the display area and the non-display area, the non-display area being curved in a direction opposite to the cover window; a first covering layer, the first covering layer corresponding to the curved area and being disposed on the display module; and a second covering layer, the second covering layer covering a side surface of the display module and the first covering layer and connecting the first covering layer with the cover window.

[0012] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the inventive concepts as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiments of the disclosure and together with the description serve to explain the principle of the disclosure.

[0014] Figure 1 is a schematic cross-sectional view of a display device according to an embodiment of the present disclosure.

[0015] Figure 2 is a schematic circuit diagram of an organic light emitting display device disclosed in the present invention.

[0016] Figure 3 is a schematic cross-sectional view of an organic light emitting display panel according to an embodiment of the present disclosure.

[0017] Figure 4 is a photograph showing a peeling problem occurring at the interface between the first cover layer and the second cover layer.

[0018] Figure 5 is a photograph showing that there is no peeling problem at the interface between the first cover layer and the second cover layer. DETAILED DESCRIPTION

[0019] Reference will now be made in detail to aspects of the present disclosure, examples of which may be illustrated in the accompanying drawings. In the following description, when a detailed description of a known function or configuration related to this document is determined to be unnecessary to obscure the gist of the inventive concept, its detailed description will be omitted. The described process steps and / or operations are examples; however, the order of the steps and / or operations is not limited to that set forth herein, and can be changed as known in the art, except for the steps and / or operations that must occur in a particular order. The same reference numerals represent the same elements throughout the application. The names of the various elements used in the following description are selected only for the convenience of writing the specification and may therefore be different from the names used in the actual product.

[0020] The advantages and features of the present disclosure and methods for achieving them will become apparent with reference to the aspects described in detail below in conjunction with the accompanying drawings. However, the present disclosure is not limited to the aspects disclosed below, but can be implemented in various different forms, and only these aspects make the disclosure of the present disclosure complete. The present disclosure is provided to fully inform those skilled in the art of the scope of the present disclosure.

[0021] The shapes, sizes, ratios, angles, quantities, etc. disclosed in the drawings used to explain aspects of the present disclosure are illustrative, and the present disclosure is not limited to the matters shown. The same figure numerals refer to the same elements throughout the specification. In addition, when describing the present disclosure, if it is determined that the detailed description of the relevant known technology unnecessarily obscures the subject matter of the present disclosure, its detailed description may be omitted. When "including", "having", "consisting of...", etc. are used in this specification, other parts may be added unless "only" is used. When a component is expressed in the singular, it includes the case of having a plural number unless otherwise specifically described.

[0022] When explaining an element, the element is interpreted as including an error or tolerance range although such error or tolerance range is not explicitly described.

[0023] When describing a positional relationship, for example, when the positional relationship between two parts is described as such as "on", "above", "below", "adjacent", one or more other parts may be disposed between the two parts, unless more restrictive terms such as "only" or "directly" are used.

[0024] When describing a temporal relationship, for example, when a time order is described as "after", "subsequently", "next", "before", discontinuities may be included unless more restrictive terms such as "only", "immediately" or "directly" are used.

[0025] It should be understood that although the terms "first", "second", etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, a first element may be referred to as a second element, and, similarly, a second element may be referred to as a first element, without departing from the scope of the present disclosure.

[0026] The features of various aspects of the present disclosure may be combined or combined with each other in part or in whole, and may be interoperated and driven technically in different ways as those skilled in the art can fully understand. The aspects of the present disclosure may be implemented independently of each other, or may be implemented together in a mutually dependent relationship.

[0027] Reference will now be made in detail to some examples and preferred embodiments that are illustrated in the accompanying drawings.

[0028] Figure 1 is a schematic cross-sectional view of a display device according to an embodiment of the present disclosure.

[0029] like Figure 1 As shown, the display device 100 includes: a display module 110 ; a cover window 160 disposed on or above the display module 110 ; a first cover layer 130 corresponding to the bending area BA; and a second cover layer 140 covering the first cover layer 130 .

[0030] The cover window 160 is disposed above the image display surface of the display module 110 and protects the display module 110 .

[0031] The cover window 160 may be formed of transparent plastic or glass. For example, the cover window 160 may be formed of one of polyethylene terephthalate (PET), polycarbonate (PC), polyethersulfone (PES), polyethylene naphthalate (PEN), and tempered glass.

[0032] The display module 110 is located under the cover window 160. The display module 110 includes a display area DA, a non-display area NDA at an outer side of the display area DA, and a bending area BA between the display area DA and the non-display area NDA.

[0033] At least one side of the display module 110 is bendable relative to the bending area BA in a direction opposite to the cover window 160. For example, one side of the display module 110 may be bent so that the non-display area NDA may be disposed below the display area DA. Thus, the frame area of ​​the display device 100 may be reduced.

[0034] The display module 110 includes a substrate 210 and a pixel array layer 270, and the pixel array layer 270 includes an organic light emitting diode D. That is, the display module 110 may include an organic light emitting display panel 120. Figure 2and Figure 3 The organic light emitting display panel 120 will be described in more detail.

[0035] Figure 2 is a schematic circuit diagram of an organic light emitting display device disclosed in the present invention.

[0036] like Figure 2 As shown, the organic light emitting display panel includes a gate line GL, a data line DL, a power line PL, a switching thin film transistor TFT Ts, a driving TFT Td, a storage capacitor Cst, and an OLED D. The gate line GL and the data line DL cross each other to define a pixel region P. The pixel region P may include a red pixel region, a green pixel region, and a blue pixel region. The pixel region P may further include a white pixel region.

[0037] The switching TFT Ts is connected to the gate line GL and the data line DL, and the driving TFT Td and the storage capacitor Cst are connected to the switching TFT Ts and the power line PL. The OLED D is connected to the driving TFT Td.

[0038] In the organic light emitting display panel, when the switching TFT Ts is turned on by a gate signal applied through the gate line GL, a data signal from the data line DL is applied to the gate electrode of the driving TFT Td and the electrode of the storage capacitor Cst.

[0039] When the driving TFT Td is turned on by the data signal, current is supplied from the power line PL to the OLED D. Therefore, the OLED D emits light. In this case, when the driving TFT Td is turned on, the level of the current applied from the power line PL to the OLED D is determined so that the OLED D can generate grayscale.

[0040] The storage capacitor Cst serves to maintain the voltage of the gate electrode of the driving TFT Td when the switching TFT Ts is turned off. Therefore, even if the switching TFT Ts is turned off, the level of the current applied from the power line PL to the OLED D is maintained until the next frame.

[0041] Therefore, the organic light emitting display panel displays a desired image.

[0042] Figure 3 is a schematic cross-sectional view of an organic light emitting display panel according to an embodiment of the present disclosure.

[0043] like Figure 3 As shown, the organic light emitting display panel 120 includes a substrate 210, a TFT Tr, a planarization layer 250, and an OLED D. The TFT Tr is disposed over the substrate 210, and the planarization layer 250 is disposed over the TFT Tr. The OLED D is disposed on or over the planarization layer 250 and is connected to the TFT Tr.

[0044] The substrate 210 may be a glass substrate or a flexible substrate. For example, the substrate 210 may be one of a polyimide (PI) substrate, a polyethersulfone (PES) substrate, a polyethylene naphthalate (PEN) substrate, a polyethylene terephthalate (PET) substrate, and a polycarbonate (PC) substrate.

[0045] A buffer layer 220 is formed on the substrate, and a TFT Tr is formed on the buffer layer 220. The buffer layer 220 may be formed of an inorganic insulating material, such as silicon oxide or silicon nitride. The buffer layer 220 may be omitted, and the TFT Tr may be formed on the substrate 210 to contact the substrate 210.

[0046] A semiconductor layer 222 is formed on the buffer layer 220. The semiconductor layer 222 may include an oxide semiconductor material or polysilicon.

[0047] When the semiconductor layer 222 includes an oxide semiconductor material, a light shielding pattern (not shown) may be formed below the semiconductor layer 222. Light emitted to the semiconductor layer 222 is shielded or blocked by the light shielding pattern, so that thermal degradation of the semiconductor layer 222 can be prevented. On the other hand, when the semiconductor layer 222 includes polysilicon, impurities may be doped into both sides of the semiconductor layer 222.

[0048] A gate insulating layer 224 is formed on the semiconductor layer 222. The gate insulating layer 224 may be formed of an inorganic insulating material such as silicon oxide or silicon nitride.

[0049] The gate 230 formed of a conductive material (eg, metal) is formed on the gate insulating layer 224 to correspond to the center of the semiconductor layer 222. Figure 3 In the embodiment, the gate insulating layer 224 is formed on the entire surface of the substrate 210. Alternatively, the gate insulating layer 224 may be patterned to have the same shape as the gate 230.

[0050] An interlayer insulating layer 232 formed of an insulating material is formed on the gate electrode 230. The interlayer insulating layer 232 may be formed of an inorganic insulating material such as silicon oxide or silicon nitride, or an organic insulating material such as benzocyclobutene or photo-acryl.

[0051] The interlayer insulating layer 232 includes a first contact hole 234 and a second contact hole 236 exposing both sides of the semiconductor layer 222. The first contact hole 234 and the second contact hole 236 are located at both sides of the gate 230 and are spaced apart from the gate 230.

[0052] The first contact hole 234 and the second contact hole 236 are formed through the gate insulating layer 224. Alternatively, when the gate insulating layer 224 is patterned to have the same shape as the gate 230, the first contact hole 234 and the second contact hole 236 are formed through only the interlayer insulating layer 232.

[0053] A source electrode 240 and a drain electrode 242 formed of a conductive material (eg, metal) are formed on the interlayer insulating layer 232 .

[0054] The source electrode 240 and the drain electrode 242 are spaced apart from each other with respect to the gate electrode 230 and contact both sides of the semiconductor layer 222 through the first contact hole 234 and the second contact hole 236 , respectively.

[0055] The semiconductor layer 222, the gate electrode 230, the source electrode 240, and the drain electrode 242 constitute a TFT Tr. The TFT Tr is used as a driving element. That is, the TFT Tr is ( Figure 2 ) driving TFT Td.

[0056] In the TFT Tr, the gate electrode 230, the source electrode 240, and the drain electrode 242 are located above the semiconductor layer 222. That is, the TFT Tr has a coplanar structure.

[0057] Alternatively, in the TFT Tr, the gate electrode may be located below the semiconductor layer, and the source electrode and the drain electrode may be located above the semiconductor layer, so that the TFT Tr may have an inverted staggered structure. In this example, the semiconductor layer may include amorphous silicon.

[0058] Although not shown, the gate line and the data line cross each other to define a pixel region, and a switching TFT is formed to be connected to the gate line and the data line. The switching TFT is connected to the TFT Tr as a driving element. In addition, a power supply line that can be formed to be parallel to and spaced apart from one of the gate line and the data line and a storage capacitor for maintaining a voltage of the gate of the TFT Tr in one frame may be further formed.

[0059] The planarization layer 250 is formed on the entire surface of the substrate 210 to cover the source electrode 240 and the drain electrode 242. The planarization layer 250 provides a flat top surface and has a drain contact hole 252 exposing the drain electrode 242 of the TFT Tr.

[0060] The OLED D is disposed on the planarization layer 250 and includes: a first electrode 260 connected to the drain electrode 242 of the TFT Tr; a light emitting layer 262; and a second electrode 264. The light emitting layer 262 and the second electrode 264 are sequentially stacked on the first electrode 260. The OLED D is disposed in each of the red pixel region, the green pixel region, and the blue pixel region and emits red light, green light, and blue light, respectively.

[0061] The first electrode 260 is formed in each pixel region, respectively. The first electrode 260 may be an anode and may be formed of a conductive material having a relatively high work function, such as a transparent conductive oxide (TCO). For example, the first electrode 260 may be formed of indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), tin oxide (SnO), zinc oxide (ZnO), indium copper oxide (ICO), or aluminum zinc oxide (Al:ZnO, AZO).

[0062] When the organic light-emitting display panel 120 of the present disclosure operates in a bottom emission type, the first electrode 260 may have a single-layer structure of a transparent conductive oxide layer of a transparent conductive oxide. Alternatively, when the organic light-emitting display panel 120 of the present disclosure operates in a top emission type, the first electrode 260 may further include a reflective layer to have a double-layer structure or a triple-layer structure. For example, the reflective layer may be formed of silver (Ag) or an aluminum-palladium-copper (APC: aluminum-palladium-copper) alloy. In a top emission type OLED, the first electrode 260 may have a double-layer structure of Ag / ITO or APC / ITO or a triple-layer structure of ITO / Ag / ITO or ITO / APC / ITO.

[0063] Furthermore, a bank layer 266 is formed on the planarization layer 250 to cover the edge of the first electrode 260. That is, the bank layer 266 is disposed at the boundaries of the red pixel region RP, the green pixel region GP, ​​and the blue pixel region BP and exposes the center of the first electrode 260 in the pixel region.

[0064] The organic light emitting layer 262 is formed on the first electrode 260. The organic light emitting layer 262 may have a single-layer structure of a light emitting material layer (EML) including a light emitting material. The EML may include red EML, green EML, and blue EML corresponding to the red pixel region RP, the green pixel region GP, ​​and the blue pixel region BP, respectively.

[0065] The organic light emitting layer 262 may further include at least one of a hole injection layer (HIL), a hole transport layer (HTL), an electron blocking layer (EBL), a hole blocking layer (HBL), an electron transport layer (ETL), and an electron injection layer (EIL) to have a multi-layer structure. In addition, two or more organic light emitting layers may be disposed to be spaced apart from each other so that the OLED D may have a tandem structure.

[0066] The second electrode 264 is formed above the substrate 210 in which the organic light emitting layer 262 is formed. The second electrode 264 covers the entire surface of the display area and can be formed of a conductive material having a relatively low work function to serve as a cathode. For example, the second electrode 264 can be formed of a highly reflective material such as aluminum (Al), magnesium (Mg), calcium (Ca), silver (Ag), their alloys, or a combination thereof. In the top-emission type organic light emitting display panel 120, the second electrode 264 can be thin and transparent (or translucent).

[0067] Reference Figure 1 , the display module 110 may further include an encapsulation layer (e.g., an encapsulation film) 150 on the pixel array layer 270. The penetration of moisture into the pixel array layer 270 may be blocked or prevented by the encapsulation layer 150. The encapsulation layer 150 may be directly formed on the second electrode 264. For example, the encapsulation layer 150 may have a stacked structure including a first inorganic insulating layer, an organic insulating layer, and a second inorganic insulating layer, but is not limited thereto.

[0068] The display module 110 may further include a touch electrode layer 152 on the encapsulation layer 150. For example, the touch electrode layer 152 may include a plurality of touch electrodes and a plurality of sensing electrodes.

[0069] The display module 110 may further include an anti-reflection layer 154 disposed on the touch electrode layer 152. Reflection of ambient light may be prevented or minimized by the anti-reflection layer 154. For example, the anti-reflection layer 154 may be a circular polarization layer. The anti-reflection layer 154 may be attached to the touch electrode layer 152 using an adhesive layer (not shown).

[0070] The display module 110 may further include a first back plate 156 and a second back plate 158. The first back plate 156 corresponds to the display area DA and is disposed at the back of the substrate 210. The second back plate 158 corresponds to the non-display area NDA and is disposed at the back of the substrate 210. The substrate 210 in the display area DA may be supported by the first back plate 156, and the substrate 210 in the non-display area NDA may be supported by the second back plate 158. For example, the substrate 210 may be a flexible substrate, and the substrate 210 in the display area DA and the non-display area may be supported by the first back plate 156 and the second back plate 158, respectively, so as to be flat.

[0071] The display module 110 may further include a printed circuit board attached to the non-display area NDA.

[0072] exist Figure 3In the embodiment of the present invention, the OLED D is disposed in each of the red pixel region RP, the green pixel region GP, ​​and the blue pixel region BP and emits red light, green light, and blue light in the red pixel region RP, the green pixel region GP, ​​and the blue pixel region BP. Alternatively, the OLED D may emit white light in each of the red pixel region RP, the green pixel region GP, ​​and the blue pixel region BP. In this case, the display module 110 may further include a color filter layer on the OLED D. The color filter layer may include a red color filter, a green color filter, and a blue color filter corresponding to the red pixel region RP, the green pixel region GP, ​​and the blue pixel region BP, respectively. For example, the color filter layer may be formed on the encapsulation layer 150.

[0073] The display device 100 may further include a transparent adhesive layer 170 between the display module 110 and the cover window 160. The transparent adhesive layer 170 may be formed of a pressure sensitive adhesive (PAS) material, an optically clear adhesive (OCA) material, or an optically clear resin (OCR) material.

[0074] The first cover layer 130 is formed on the substrate 210 and corresponds to the bending area BA of the display module 110 .

[0075] Although not shown, in the non-display area NDA, a pad portion may be provided on the substrate 210, and a connection line for connecting the pixel array layer 270 with the pad portion may extend from the pixel array layer 270 to the pad portion through the bending area BA. In this case, the first cover layer 130 may be provided to cover the connection line.

[0076] When the display device 100 is bent so that the bending area BA of the substrate 210 is a curved shape having a predetermined radius of curvature, the connection line may exist in a neutral plane based on the first cover layer 130. That is, when the bending area BA of the substrate 210 is bent with a predetermined radius of curvature, a neutral plane where the tensile force and the compressive force become 0 (zero) exists between the substrate 210 and the first cover layer 130. When the bending area BA of the substrate 210 is bent into a curved shape, since the connection line exists on the neutral plane between the first cover layer 130 and the substrate 210, the bending stress may be reduced and the display device 100 may be bent without being damaged. The first cover layer 130 may be referred to as a micro cover layer.

[0077] The second cover layer 140 covers the side of the display module 110 and the first cover layer 130 and may be attached to the back of the cover window 160. The second cover layer 140 connects the first cover layer 130 and the cover window 160. In other words, the first cover layer 130 and the cover window 160 are fixed by the second cover layer 140.

[0078] <First Embodiment>

[0079] <First Covering Layer>

[0080] The first capping layer 130 includes a monomer, an oligomer, a first photoinitiator, and a second photoinitiator.

[0081] The monomer may be an acrylate compound, and the acrylate compound is at least one selected from n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, and isobornyl methacrylate. For example, the monomer may be isobornyl acrylate represented by Formula 1.

[0082] [Formula 1]

[0083]

[0084] The oligomer may include at least one of the compound represented by Formula 2-1 (isophorone diisocyanate) and the compound represented by Formula 2-2 (2-hydroxyethyl acrylate).

[0085] [Formula 2-1]

[0086]

[0087] [Formula 2-2]

[0088]

[0089] The first photoinitiator may absorb ultraviolet (UV) rays having a wavelength ranging from about 250 nm to 350 nm.

[0090] [Formula 3]

[0091]

[0092] The second photoinitiator may absorb ultraviolet light having a wavelength ranging from about 270 nm to 430 nm.

[0093] [Formula 4]

[0094]

[0095] The weight % of the first photoinitiator may be equal to or greater than that of the second photoinitiator. For example, in the first cover layer 130, the first photoinitiator may have 1 wt% to 5 wt%, and the second photoinitiator may have 1 wt% to 2.5 wt%.

[0096] The monomer may be included in the first cover layer 130 at 1500 to 1800 weight percent, and the oligomer may be included in the first cover layer 130 at 1000 to 1200 weight percent relative to the first photoinitiator. The weight percent of the monomer may be greater than that of the oligomer.

[0097] The first capping layer 130 may further include a third photoinitiator represented by Formula 5.

[0098] [Formula 5]

[0099]

[0100] The photoinitiator may be included in the first cover layer 130 at 20 to 30 weight percent relative to the first photoinitiator.

[0101] The first capping layer 130 may further include a silane coupling agent. The silane coupling agent may be a compound represented by Formula 6 ((trimethoxysilyl)propyl ester).

[0102] [Formula 6]

[0103]

[0104] The silane coupling agent may be included in the first capping layer 130 at 50 to 100 weight percent relative to the first photoinitiator.

[0105] The first cover layer 130 may further include a catalyst. The catalyst may include at least one of a compound represented by Formula 7-1 (camphor terpene) and a compound represented by Formula 7-2 (1,7,7-trimethyltricyclo[2.2.1.02,6]heptane).

[0106] [Formula 7-1]

[0107]

[0108] [Formula 7-2]

[0109]

[0110] The catalyst may be included in the first capping layer 130 at 40 to 60 weight percent relative to the first photoinitiator.

[0111] In one aspect of the present disclosure, the first covering layer 130 may include: 40 wt% to 55 wt% of a monomer, the monomer is a compound of Formula 1; 35 wt% to 45 wt% of an oligomer, the oligomer includes compounds of Formulas 2-1 and 2-2; 1 wt% to 5 wt% of a first photoinitiator, the first photoinitiator is a compound of Formula 3; 1 wt% to 2.5 wt% of a second photoinitiator, the second photoinitiator is a compound of Formula 4; 0.25 wt% to 1 wt% of a third photoinitiator, the third photoinitiator is a compound of Formula 5; 1 wt% to 2.5 wt% of a silane coupling agent, the silane coupling agent is a compound of Formula 6; and 0.5 wt% to 2 wt% of a catalyst, the catalyst includes compounds of Formulas 7-1 and 7-2. In this case, the compound of Formula 2-1 and the compound of Formula 2-2 may have the same weight %, and the compound of Formula 7-1 and the compound of Formula 7-2 may have the same weight %.

[0112] The first cover layer 130 may be formed by coating a composition including the above materials and curing the composition with UV rays having a wavelength ranging from 340 nm to 370 nm.

[0113] <Second Covering Layer>

[0114] The second capping layer 140 includes a monomer, a photoinitiator, and a catalyst.

[0115] The monomer may be an alicyclic epoxy compound. For example, the monomer may be a compound represented by Formula 8 (3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate).

[0116] [Formula 8]

[0117]

[0118] The photoinitiator may absorb UV rays having a wavelength ranging from about 400 nm to 500 nm.

[0119] [Formula 9]

[0120]

[0121] The catalyst may include at least one of trimethylamine and 2-phenylisopropanol.

[0122] For example, the monomer may be included at 3000 to 6000 weight percent, and the catalyst may be included at 10 to 100 weight percent, relative to the photoinitiator.

[0123] The second capping layer 140 may further include at least one of the compound of Formula 10-1 (polypropylene glycol) and the compound of Formula 10-2 (methyl methacrylate).

[0124] [Formula 10-1]

[0125]

[0126] [Formula 10-2]

[0127]

[0128] In formula 10-1, n is an integer from 1 to 100.

[0129] Each of the compounds of Formula 10-1 and Formula 10-2 may be included at 1000 to 6000 weight percent with respect to the photoinitiator.

[0130] The second capping layer 140 may further include a silane coupling agent. The silane coupling agent may be a compound represented by Formula 11 (trimethoxy[2-(oxiranylmethoxy)propyl]silane).

[0131] [Formula 11]

[0132]

[0133] In one aspect of the present disclosure, the second covering layer 140 may include: 30 wt% to 60 wt% of a monomer, the monomer being a compound of Formula 8; 1 wt% to 5 wt% of a photoinitiator, the photoinitiator being a compound of Formula 9; 0.1 wt% to 1 wt% of a catalyst, the catalyst including trimethylamine and 2-phenylisopropanol; 10 wt% to 30 wt% of a compound of Formula 10-1; 10 wt% to 30 wt% of a compound of Formula 10-2; and 1 wt% to 5 wt% of a silane coupling agent of Formula 11. In this case, trimethylamine and 2-phenylisopropanol may have the same weight %.

[0134] The second cover layer 140 may be formed by coating a composition including the above materials and curing the composition with UV rays having a wavelength ranging from 400 nm to 450 nm.

[0135] In the display device 100, at least one side of the substrate 210 is bent so that the bezel area can be minimized, and damage to the bending area BA due to the bending operation can be prevented or minimized by the first cover layer 130. In addition, the first cover layer 130 can be protected by the second cover layer 140, and the cover window 160 and the display module 110 can be firmly attached by the second cover layer 140.

[0136] On the other hand, in the display device 100 , there may be a problem that an uncured region of the second cover layer 140 is generated at the interface between the first cover layer 130 and the second cover layer 140 .

[0137] That is, the first cover layer 130 is cured by irradiating UV rays having a wavelength range of 340 nm to 370 nm, and the first cover layer 130 includes a first photoinitiator that absorbs UV rays having a wavelength range of about 250 nm to 350 nm and a second photoinitiator that absorbs UV rays having a wavelength range of about 270 nm to 430 nm. After the first cover layer 130 is cured, the second cover layer 140 is cured by irradiating UV rays having a wavelength range of 400 nm to 450 nm. In this case, the UV rays for curing the second cover layer 140 may be absorbed by the second photoinitiator in the first cover layer 130, so that a portion of the second cover layer 140 at the interface between the first cover layer 130 and the second cover layer 140 may not be completely cured. As a result, a peeling problem of the second cover layer 140 ( Figure 4 ).

[0138] <Second Embodiment>

[0139] <First Covering Layer>

[0140] The first capping layer 130 includes monomers, oligomers, photoinitiators, and cationic surfactants.

[0141] The monomer may be an acrylate compound, which is at least one selected from n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, and isobornyl methacrylate. For example, the monomer may be isobornyl acrylate represented by Formula 1.

[0142] The oligomer may include at least one of the compound represented by Formula 2-1 (isophorone diisocyanate) and the compound represented by Formula 2-2 (2-hydroxyethyl acrylate).

[0143] The photoinitiator may absorb ultraviolet (UV) rays having a wavelength ranging from about 300 nm to 380 nm.

[0144] [Formula 12]

[0145]

[0146] The cationic surfactant may be a compound represented by Formula 13 (dodecyl acrylate).

[0147] [Formula 13]

[0148]

[0149] The monomer may be included in the first cover layer 130 at 1500 to 1800 weight percent relative to the photoinitiator, and the oligomer may be included in the first cover layer 130 at 1000 to 1200 weight percent. The weight percent of the monomer may be greater than the weight percent of the oligomer. The cationic surfactant may be included in the first cover layer 130 at 5 to 100 weight percent relative to the photoinitiator.

[0150] The first capping layer 130 may further include an auxiliary photoinitiator represented by Formula 5. The auxiliary photoinitiator may be included in an amount of 5 to 20 weight percent with respect to the photoinitiator.

[0151] The first capping layer 130 may further include a silane coupling agent. The silane coupling agent may be a compound ((trimethoxysilyl)propyl ester) represented by Formula 6. The silane coupling agent may be included in an amount of 50 to 100 weight percent relative to the photoinitiator.

[0152] The first cover layer 130 may further include a catalyst. The catalyst may include at least one of the compound represented by Formula 7-1 (camphor terpene) and the compound represented by Formula 7-2 (1,7,7-trimethyltricyclo[2.2.1.02,6]heptane). The catalyst may be included in an amount of 40 to 60 weight percent relative to the photoinitiator.

[0153] In one aspect of the present disclosure, the first covering layer 130 may include: 40 wt% to 55 wt% of a monomer, the monomer is a compound of Formula 1; 35 wt% to 45 wt% of an oligomer, the oligomer includes compounds of Formulas 2-1 and 2-2; 5 wt% to 10 wt% of a photoinitiator, the photoinitiator is a compound of Formula 12; 0.25 wt% to 5 wt% of a cationic surfactant, the cationic surfactant is a compound of Formula 13; 0.25 wt% to 1 wt% of an auxiliary photoinitiator, the auxiliary photoinitiator is a compound of Formula 5; 1 wt% to 2.5 wt% of a silane coupling agent, the silane coupling agent is a compound of Formula 6; and 0.5 wt% to 2 wt% of a catalyst, the catalyst includes compounds of Formulas 7-1 and 7-2. In this case, the compound of Formula 2-1 and the compound of Formula 2-2 may have the same weight %, and the compound of Formula 7-1 and the compound of Formula 7-2 may have the same weight %.

[0154] The first cover layer 130 may be formed by coating a composition including the above materials and curing the composition with UV rays having a wavelength ranging from 340 nm to 370 nm.

[0155] <Second Covering Layer>

[0156] The second capping layer 140 includes a monomer, a photoinitiator, and a catalyst.

[0157] The monomer may be an alicyclic epoxy compound. For example, the monomer may be a compound represented by Formula 8 (3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate).

[0158] The photoinitiator may absorb UV rays having a wavelength range of about 400 nm to 500 nm. The photoinitiator may be represented by Formula 9. The absorption wavelength range of the photoinitiator included in the second cover layer 140 does not overlap with the absorption wavelength range of the photoinitiator included in the first cover layer 130. That is, the photoinitiator (e.g., the first photoinitiator) included in the first cover layer 130 has a first absorption wavelength range, for example, 300 nm to 500 nm, and the photoinitiator (e.g., the second photoinitiator) included in the second cover layer 140 has a second absorption wavelength range larger than the first absorption wavelength range, for example, 400 nm to 500 nm.

[0159] The catalyst may include at least one of trimethylamine and 2-phenylisopropanol.

[0160] For example, the monomer may be included at 3000 to 6000 weight percent, and the catalyst may be included at 10 to 100 weight percent, relative to the photoinitiator.

[0161] The second capping layer 140 may further include at least one of the compound of Formula 10-1 (polypropylene glycol) and the compound of Formula 10-2 (methyl methacrylate).

[0162] Each of the compounds of Formula 10-1 and Formula 10-2 may be included at 1000 to 6000 weight percent with respect to the photoinitiator.

[0163] The second capping layer 140 may further include a silane coupling agent. The silane coupling agent may be a compound represented by Formula 11 (trimethoxy[2-(oxiranylmethoxy)propyl]silane).

[0164] In one aspect of the present disclosure, the second covering layer 140 may include: 30 wt% to 60 wt% of a monomer, the monomer being a compound of Formula 8; 1 wt% to 5 wt% of a photoinitiator, the photoinitiator being a compound of Formula 9; 0.1 wt% to 1 wt% of a catalyst, the catalyst including trimethylamine and 2-phenylisopropanol; 10 wt% to 30 wt% of a compound of Formula 10-1; 10 wt% to 30 wt% of a compound of Formula 10-2; and 1 wt% to 5 wt% of a silane coupling agent of Formula 11. In this case, trimethylamine and 2-phenylisopropanol may have the same weight %.

[0165] The second cover layer 140 may be formed by coating a composition including the above materials and curing the composition with UV rays having a wavelength ranging from 400 nm to 450 nm.

[0166] Since the photoinitiator in the first cover layer 130 has an absorption wavelength range of 300 nm to 380 nm, UV irradiated for curing the second cover layer 140 is not absorbed by the photoinitiator in the first cover layer 130 , so that the second cover layer 140 may be sufficiently or completely cured.

[0167] The compatibility of the photoinitiator of the first covering layer 130 is poor. The first covering layer 130 includes a cationic surfactant to improve the compatibility.

[0168] In addition, the lower portion of the second cover layer 140, that is, a portion of the second cover layer 140 adjacent to the first cover layer 130, is thermally cured by the catalyst used as a thermal curing agent. Therefore, the second cover layer 140 is completely cured, and the peeling problem of the second cover layer 140 in the bending area BA is prevented or minimized ( Figure 5 ).

[0169] On the other hand, when an anionic surfactant is used to improve the compatibility of the photoinitiator, the cation of the epoxy compound used for thermal curing may react with the anion of the surfactant. As a result, the efficiency of the thermal curing reaction may be reduced. However, in the display device 100 of the present disclosure, since the first cover layer 130 includes the cationic surfactant, the thermal curing reaction in the second cover layer 140 can be effectively performed.

[0170] In the display device 100, at least one side of the substrate 210 is bent so that the bezel area can be minimized, and damage to the bending area BA due to the bending operation can be prevented or minimized by the first cover layer 130. In addition, the first cover layer 130 can be protected by the second cover layer 140, and the cover window 160 and the display module 110 can be firmly attached by the second cover layer 140.

[0171] In addition, since the first cover layer 130 includes a photoinitiator having an absorption wavelength range different from that of the photoinitiator in the second cover layer 140, and a cationic surfactant, UV curing and thermal curing in the second cover layer 140 can be sufficiently performed. Therefore, the peeling problem of the second cover layer 140 can be prevented or minimized.

[0172] It will be apparent to those skilled in the art that various modifications and variations can be made to the present disclosure without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is intended to cover modifications and variations of the present disclosure as long as they fall within the scope of the appended claims and their equivalents.

Claims

1. A display device, comprising: Cover windows; a display module, the display module being disposed below the cover window and comprising a display area, a non-display area, and a curved area between the display area and the non-display area, wherein the non-display area is curved in a direction opposite to the cover window; a first covering layer, the first covering layer corresponding to the bending area and disposed on the display module; as well as A second covering layer, wherein the second covering layer covers the side surface of the display module and the first covering layer and connects the first covering layer and the cover window.

2. The display device according to claim 1, wherein: The first covering layer includes a first monomer, an oligomer, a first photoinitiator, and a cationic surfactant.

3. The display device according to claim 2, wherein: The cationic surfactant is lauryl acrylate.

4. The display device according to claim 2, wherein: The first monomer includes at least one selected from the group consisting of n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, and isobornyl methacrylate.

5. The display device according to claim 2, wherein: The first covering layer further includes an auxiliary photoinitiator represented by Formula 5: [Formula 5] 6. The display device according to claim 2, wherein: The first covering layer further includes a silane coupling agent represented by Formula 6: [Formula 6] 7. The display device according to claim 2, wherein: The first covering layer further includes a catalyst including at least one of a compound represented by Formula 7-1 and a second compound represented by Formula 7-2: [Formula 7-1] [Formula 7-2] 8. The display device according to claim 2, wherein: The second covering layer includes a second monomer, a second photoinitiator and a catalyst.

9. The display device according to claim 8, wherein: The second monomer is an alicyclic epoxy compound.

10. The display device according to claim 8, wherein: The first photoinitiator has a first absorption wavelength range, and the second photoinitiator has a second absorption wavelength range, and Wherein, the second absorption wavelength range is greater than the first absorption wavelength range.

11. The display device according to claim 10, wherein: The first photoinitiator is a compound represented by Formula 12, and the second photoinitiator is a compound represented by Formula 9: [Formula 12] [Formula 9] 12. The display device according to claim 8, wherein: The catalyst includes at least one of trimethylamine and 2-phenylisopropanol.

13. The display device according to claim 8, wherein: The second covering layer further includes at least one of a compound represented by Formula 10-1 and a compound represented by Formula 10-2: [Formula 10-1] [Formula 10-2] and In formula 10-1, n is an integer from 1 to 100.

14. The display device according to claim 8, wherein: The second covering layer further includes a silane coupling agent represented by Formula 11: [Formula 11] 15. The display device according to claim 1, wherein: The display module comprises: a substrate, the substrate being disposed below the cover window; and An organic light emitting diode is located between the cover window and the substrate.

16. The display device according to claim 15, further comprising: a transparent adhesive layer, wherein the transparent adhesive layer is located between the display module and the cover window; as well as A polarizing plate is located between the organic light emitting diode and the transparent adhesive layer.

17. The display device according to claim 16, wherein: The display module further includes a touch electrode layer located between the polarizing plate and the organic light emitting diode.

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