Display device comprising a joining member

Abstract

Disclosed is a display device including: a display panel; a polarizing member overlapping the display panel; a cover window overlapping the polarizing member; and a window bonding member provided between the polarizing member and the cover window, wherein a penetration depth of the window bonding member measured by an indentation tester is equal to or less than approximately 13 µm.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2019-0171831, filed on December 20, 2019, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to display devices, and more particularly, to display devices including coupling members. Background Technology

[0004] Display devices are output devices used to present information in a visual form; for example, display devices can provide images to users. Electronic devices that use display devices include smartphones, tablet PCs, digital cameras, laptops, navigation devices, and smart TVs (TVs).

[0005] Recently, curved display devices with at least one curved edge have been developed. Displaying images on the curved edge of a curved display device allows viewers to see a wider screen. The curved edge itself is also aesthetically pleasing.

[0006] A curved display device may include a window engagement member that attaches a polarizing member on the display panel to a cover window. However, the modulus of the window engagement member in the flat region of the curved display device may differ from its modulus in the curved region of the curved display device. Summary of the Invention

[0007] According to an exemplary embodiment of the present invention, a display device includes: a display panel; a polarizing member overlapping the display panel; a cover window overlapping the polarizing member; and a window bonding member disposed between the polarizing member and the cover window, wherein the penetration depth of the window bonding member, as measured by an indentation tester, is equal to or less than approximately 13 μm.

[0008] Penetration depth can be measured by an indentation tester by pressing the indenter against the window joint member, holding the indenter under a predetermined load for a predetermined period of time, and then unloading the indenter.

[0009] The pressure head can have at least a partial spherical shape.

[0010] The modulus of the window joint component can be equal to or greater than approximately 0.61 MPa, and the creep characteristics of the window joint component can be in the range of 30% to approximately 70%.

[0011] The window bonding member can be a thin film with a thickness of 0.05 mm to 1 mm, and the modulus and creep characteristics of the window bonding member can be measured from the thin film.

[0012] The modulus and creep characteristics of the window bonding member can be measured by using an indenter tester from the window bonding member separated from the display device.

[0013] The display device can include a flat area, a first curved area on a first side of the flat area, and a second curved area on a second side of the flat area, the display device can further include a light-shielding pattern disposed directly on a surface of the cover window facing the window bonding member, and the light-shielding pattern can be disposed in the first curved area and the second curved area.

[0014] The window bonding member can include a first portion disposed in the flat area and a second portion disposed in the first curved area and the second curved area, and a penetration depth of the first portion measured by the indenter tester can be less than a penetration depth of each of the second portions measured by the indenter tester.

[0015] The modulus of the first portion can be greater than the modulus of each of the second portions, and the creep characteristics of the first portion can be less than the creep characteristics of each of the second portions.

[0016] The window bonding member can be ultraviolet (UV) cured.

[0017] The window bonding member can be disposed between the polarizing member and the cover window, and then be UV cured.

[0018] According to another exemplary embodiment of the present application, a display device includes a flat area, a first curved area on a first side of the flat area, and a second curved area on a second side of the flat area, wherein the display device further includes a display panel, a polarizing member overlapping the display panel, a cover window overlapping the polarizing member, and a window bonding member disposed between the polarizing member and the cover window, and wherein a modulus of the window bonding member is equal to or greater than approximately 0.61 MPa.

[0019] The window bonding member can include a first portion disposed in the flat area and a second portion disposed in the first curved area and the second curved area, and the modulus of the first portion can be greater than the modulus of each of the second portions.

[0020] The creep characteristics of the window bonding member can be in a range of 30% to approximately 70%, and the creep characteristics of the first portion can be less than the creep characteristics of each of the second portions.

[0021] A penetration depth of the window bonding member measured by the indenter tester can be equal to or less than 13 µm, and the penetration depth of the first portion can be less than the penetration depth of each of the second portions.

[0022] The window bonding member can be a thin film having a thickness of 0.05 mm to 1 mm, and the modulus of the window bonding member and the creep property of the window bonding member can be measured from the thin film.

[0023] The modulus of the window bonding member and the creep property of the window bonding member can be measured from the window bonding member separated from the display apparatus by using an indenter tester.

[0024] According to still another exemplary embodiment of the present application, a display apparatus includes a flat area, a first curved area located on a first side of the flat area, and a second curved area located on a second side of the flat area, wherein the display apparatus further includes a display panel, a polarizing member disposed on the display panel, a cover window disposed on the polarizing member, and a window bonding member disposed between the polarizing member and the cover window, wherein the window bonding member includes a first portion disposed in the flat area and a second portion disposed in the first curved area and the second curved area, and wherein a modulus of the first portion is equal to or greater than approximately 0.61 MPa and a modulus of each of the second portions is equal to or greater than approximately 0.61 MPa.

[0025] A creep property of the first portion is in a range of 30% to approximately 70% and a creep deformation property of each of the second portions is in a range of 30% to approximately 70%, and the creep property of the first portion is less than the creep property of each of the second portions.

[0026] A penetration depth of the first portion can be equal to or less than approximately 13 µm and a penetration depth of each of the second portions can be equal to or less than approximately 13 µm, wherein the penetration depth of the first portion and the penetration depth of each of the second portions are measured by an indenter tester, and the penetration depth of the first portion can be less than the penetration depth of each of the second portions. BRIEF DESCRIPTION OF DRAWINGS

[0027] The above and other features of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:

[0028] Figure 1 is a perspective view of a display apparatus according to an exemplary embodiment of the present application.

[0029] Figure 2 is a cross-sectional view taken along line II-II’ of Figure 1 .

[0030] Figure 3 is an enlarged cross-sectional view of area A of Figure 2 .

[0031] Figure 4is a perspective view showing ultraviolet curing of a window bonding member of a display device according to an example embodiment of the present application.

[0032] Figure 5 is a cross-sectional view showing ultraviolet curing of a window bonding member of a display device according to an example embodiment of the present application.

[0033] Figure 6 is a schematic view showing measurement of physical properties of a window bonding member by a bio-indenter according to an example embodiment of the present application.

[0034] Figure 7 is a table showing measurement conditions of a bio-indenter according to an example embodiment of the present application.

[0035] Figure 8 and Figure 9 is a cross-sectional view showing penetration depth of a first portion of a window bonding member measured by a bio-indenter.

[0036] Figure 10 is a graph showing a relationship between penetration depth and load.

[0037] Figure 11 is a graph showing change in penetration depth with time before and after a maximum load holding time.

[0038] Figure 12 is a cross-sectional view showing penetration depth of a second portion of a window bonding member measured by a bio-indenter.

[0039] Figure 13 is a perspective view of a display device according to another example embodiment of the present application.

[0040] Figure 14 is a cross-sectional view taken along line XIV-XIV’ of Figure 13 is a perspective view of a display device according to another example embodiment of the present application. DETAILED DESCRIPTION

[0041] The specific configurations and functional descriptions of the example embodiments of the present application disclosed herein are for the purpose of illustration. The present application can be implemented in many different forms and, therefore, the present application is not limited to the embodiments disclosed herein.

[0042] It should be understood that when an element is referred to as being “associated with” another element, such as when an element is referred to as being “coupled to” or “connected to” another element, it can be directly coupled or connected to the other element, or intervening elements can be present therebetween. Other expressions describing the relationship between elements, such as “between,” “directly between,” “adjacent to,” or “directly adjacent to,” can be interpreted in a similar manner.

[0043] Throughout the specification, like drawing numbers can refer to like or similar parts throughout the description.

[0044] As used herein, "a," "an," "the," and "at least one" are intended to include both singular and plural referents unless the context clearly dictates otherwise.

[0045] In addition, relative terms such as "lower" or "bottom" and "upper" or "top" can be used herein to describe one element's or feature's relationship to another element or feature as illustrated in the figures. These relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures. For example, if the device in one of the figures is turned over, elements described as being on the "lower" side of other elements would then be oriented on "upper" sides of the other elements. The exemplary term "lower" can therefore encompass both an orientation of lower and upper, depending on the particular orientation of the figure. Similarly, if the device in one of the figures is turned over, elements described as "below" or "beneath" other elements would then be oriented "above" the other elements. The exemplary terms "below" or "beneath" can therefore encompass both an orientation of above and below, depending on the particular orientation of the figure.

[0046] "About" or "approximately" as used herein can include the recited value and can mean within an acceptable range of deviation for a particular value as determined by one of ordinary skill in the art to which the measurement relates, e.g., limitations of a measurement system. For example, "about" can mean within one or more standard deviations of the recited value, or within ± 30%, ± 20%, ± 10%, or ± 5%.

[0047] Exemplary embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and / or tolerances, are to be expected. Thus, embodiments described herein are not to be construed as being limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result from, for example, manufacturing. For example, a region illustrated or described as flat can have rough and / or non-linear features. Moreover, sharp angles that are illustrated can be rounded. Thus, the regions illustrated in the figures are schematic

[0048] Exemplary embodiments of the present application will hereinafter be described with reference to the accompanying drawings.

[0049] Figure 1 is a perspective view of a display device according to an exemplary embodiment of the present application. Figure 2 is a cross-sectional view taken along line II-II' of Figure 1 Figure 3 is​Figure 2 An enlarged sectional view of region A.

[0050] refer to Figures 1 to 3 The display device 1 according to an exemplary embodiment of the present invention includes a cover window 100, a polarizing member 200, a display panel 300, and a bottom cover 900.

[0051] As used herein, the terms "above," "top," and "upper surface" refer to the side of the display panel 300 on which the cover window 100 is located in the z-axis direction, and the terms "below," "bottom," and "lower surface" refer to the opposite side of the display panel 300 on which the bottom cover 900 is located in the z-axis direction. As used herein, the terms "left side," "right side," "upper side," and "lower side" indicate relative positions when the display panel 300 is viewed from above. For example, "left side" may refer to the opposite side indicated by an arrow in the x-axis direction, "right side" may refer to the side indicated by an arrow in the x-axis direction, "upper side" may refer to the side indicated by an arrow in the y-axis direction, and "lower side" may refer to the opposite side indicated by an arrow in the y-axis direction.

[0052] When viewed from above, display device 1 can have a rectangular shape. For example, as shown... Figure 1 As shown, when viewed from above, the display device 1 can have a rectangular shape, having a short side in a first direction (x-axis direction) and a long side in a second direction (y-axis direction). Each of the corners where the short side in the first direction (x-axis direction) meets the long side in the second direction (y-axis direction) can be rounded with a predetermined curvature or can be a right angle. When viewed from above, the shape of the display device 1 is not limited to a rectangular shape, but can have another polygonal shape, a circular shape, or an elliptical shape.

[0053] Display device 1 may include a flat first region and second regions extending from the left and right sides of the first region. The second regions may be flat or curved. When the second regions are flat, the angle formed by each of the second regions and the first region may be an obtuse angle. When the second regions are curved surfaces, they may have a constant curvature or a varying curvature. In display device 1 according to this embodiment, the first region may be a flat region FA, and the second regions may be curved regions CA1 and CA2 extending from the left and right sides of the first region and buckling in the thickness direction (z-axis direction). For example, the curved regions CA1 and CA2 may buckle downwards. The first curved region CA1 may be located on one side (left side) of the flat region FA in the first direction (x-axis direction), and the second curved region CA2 may be located on the other side (right side) of the flat region FA in the first direction (x-axis direction).

[0054] Although Figure 1The second area extends from the left and right sides of the first area, respectively, but this is merely illustrative. For example, the second area can extend from only one of the right and left sides of the first area.

[0055] Alternatively, the second area can extend from at least one of the upper and lower sides and the left and right sides of the first area. This will be described in greater detail below. In the following description, the second area is provided at the left and right sides of the display device 1, respectively. Figure 13 This will be described in greater detail below. In the following description, the second area is provided at the left and right sides of the display device 1, respectively.

[0056] The cover window 100 can be provided on the polarizing member 200 and the display panel 300 to cover the polarizing member 200 and the display panel 300. Accordingly, the cover window 100 can protect the upper surfaces of the polarizing member 200 and the display panel 300. As shown in FIG. 1, the cover window 100 can be attached to the polarizing member 200 by a window bonding member 410. Figure 2

[0057] The cover window 100 can include a transmissive area DA100 corresponding to the display panel 300 and a non-transmissive area NDA100 corresponding to other areas other than the display panel 300. The transmissive area DA100 can be a display area, and the non-transmissive area NDA100 can be a non-display area. The cover window 100 can be provided in the flat area FA and the curved areas CA1 and CA2. The transmissive area DA100 can be provided in a portion of the flat area FA and a portion of the curved areas CA1 and CA2. The non-transmissive area NDA100 can be opaque. Alternatively, the non-transmissive area NDA100 can be a decorative layer having a pattern that can be displayed to a user when no image is displayed. For example, a company logo such as "SAMSUNG" or various letters can be patterned in the non-transmissive area NDA100. Holes HH for exposing a front camera, a front speaker, an infrared sensor, an iris recognition sensor, an ultrasonic sensor, an illuminance sensor, etc. can be formed in the non-transmissive area NDA100. However, some or all of the front camera, the front speaker, the infrared sensor, the iris recognition sensor, the ultrasonic sensor, and the illuminance sensor can be incorporated into the display panel 300. In this case, some or all of the holes HH can be removed. In the curved areas CA1 and CA2, the light-shielding pattern 110 can be provided on the surface of the cover window 100 and face the polarizing member 200 and the display panel 300. In the curved areas CA1 and CA2, the light-shielding pattern 110 can not be provided on the entire surface of the cover window 100. For example, the light-shielding pattern 110 can be provided from the end of the cover window 100 in the curved areas CA1 and CA2 and extend to near the boundary between the curved areas CA1 and CA2 and the flat area FA.

[0058] ​The cover window 100 can be made of glass, sapphire, and / or plastic. The cover window 100 can be rigid or flexible.

[0059] The polarizing member 200 and the display panel 300 can be disposed in the flat area FA and the curved areas CA1 and CA2. The cover window 100 can be disposed on the outer side of the polarizing member 200 and the display panel 300 to completely cover the polarizing member 200 and the display panel 300.

[0060] The window bonding member 410 can be disposed in a portion of the curved areas CA1 and CA2 and the flat area FA.

[0061] The window bonding member 410 can be indented inward from the cover window 100 and the polarizing member 200. In other words, the window bonding member 410 can expose a surface of the polarizing member 200 facing the cover window 100 in the curved areas CA1 and CA2. For example, as shown in FIG. 1B, the window bonding member 410 can expose a surface of the polarizing member 200 facing the cover window 100 in the curved areas CA1 and CA2. Figure 2 A space can be formed between the polarizing member 200 and the light-shielding pattern 110, as shown in FIG. 1B. However, it should be understood that the present application is not limited thereto. In the curved areas CA1 and CA2, the window bonding member 410 can not expose a surface of the polarizing member 200 facing the cover window 100, but can completely cover a surface of the polarizing member 200 facing the cover window 100. The window bonding member 410 can be optically transparent.

[0062] The display panel 300 displays an image and can include a self-emissive display panel such as an organic light-emitting display panel (OLED), an inorganic light-emitting display panel (inorganic EL), a quantum dot light-emitting display panel (QED), a micro LED display panel (micro LED), a nano LED display panel (nano LED), a plasma display panel (PDP), a field emission display panel (FED), and a cathode ray display panel (CRT), and a light-receiving display panel such as a liquid crystal display panel (LCD) and an electrophoretic display panel (EPD). In the following description, the OLED will be described as an example of the display panel 300, and the OLED will be simply referred to as the display panel 300, unless specifically otherwise stated. However, it should be understood that the present application is not limited to the OLED, and any other display panel listed above or other display panel not listed above can be employed in connection with the present application.

[0063] The display panel 300 can further include a touch member. The touch member can be a panel or a film to be attached on the display panel 300, which is separate from the display panel 300, or can be a touch layer inside the display panel 300. Although the touch member is disposed inside the display panel 300 to be included in the display panel 300 in the following description, it should be understood that the present application is not limited thereto.

[0064] The display panel 300 may include a substrate, a circuit driving layer on the substrate, a light-emitting layer on the circuit driving layer, an encapsulation layer on the light-emitting layer, and a touch layer on the encapsulation layer.

[0065] The substrate can be a flexible substrate comprising a flexible polymer material (such as polyimide). Therefore, the display panel 300 can be bent, buckled, folded, or rolled. In some exemplary embodiments of the invention, the substrate may include a plurality of sub-substrates overlapping in the thickness direction, with a barrier layer between the plurality of sub-substrates. In this case, each of the sub-substrates may be a flexible substrate.

[0066] The circuit driving layer can be disposed on the substrate. The circuit driving layer may include circuitry for driving the light-emitting layer of the pixels. The circuit driving layer may include multiple thin-film transistors.

[0067] The light-emitting layer can be disposed on the circuit driving layer. The light-emitting layer may include an organic light-emitting layer. The light-emitting layer can emit light at different brightness levels according to the driving signal sent from the circuit driving layer.

[0068] The encapsulation layer can be disposed on the light-emitting layer. The encapsulation layer may include an inorganic layer, or a stack of inorganic and organic layers.

[0069] The touch layer can be disposed on the encapsulation layer. The touch layer can sense touch input and perform the functions of the touch components. The touch layer may include multiple sensing areas and sensing electrodes.

[0070] The polarizing member 200 polarizes light passing through it. The polarizing member 200 can reduce the reflection of external light. In an exemplary embodiment of the invention, the polarizing member 200 may be a polarizing film. The polarizing film may include a protective substrate and a polarizing layer sandwiched between the protective substrate. The polarizing layer may include a polyvinyl alcohol film. The polarizing layer may be stretched in a specific direction. The direction in which the polarizing layer is stretched may be the absorption axis, while the direction perpendicular to the absorption axis may be the transmission axis. The protective substrate may be disposed on one side and the other side of the polarizing layer, respectively. The protective substrate may be made of, but is not limited to, cellulose resin (triacetyl cellulose), polyester resin, etc.

[0071] like Figure 2 As shown, a polarization bonding member 420 may be further provided between the polarization member 200 and the display panel 300. The polarization bonding member 420 can connect the polarization member 200 to the display panel 300. The polarization bonding member 420 can be optically transparent, like the window bonding member 410. The polarization bonding member 420 can directly contact the polarization member 200 and the display panel 300.

[0072] The window joining member 410 according to this embodiment may include a first portion 411 disposed in the flat region FA and a second portion 415 disposed in the curved regions CA1 and CA2. The second portion 415 of the window joining member 410 may overlap with the light-shielding pattern 110 described above.

[0073] Window bonding member 410 and polarization bonding member 420 may each include an adhesive material. Each of bonding members 410 and 420 may include a pressure-sensitive adhesive layer.

[0074] The bonding members 410 and / or 420 may include an optically transparent adhesive layer or an optically transparent resin.

[0075] like Figure 3 As shown, the second portion 415 of the window joining member 410 may partially overlap with the light-shielding pattern 110. The portion of the second portion 415 that does not overlap with the light-shielding pattern 110 may have a first thickness t1, while the portion of the second portion 415 that overlaps with the light-shielding pattern 110 may have a second thickness t2. The first thickness t1 may be greater than the second thickness t2. The first portion 411 may have a thickness equal to the first thickness t1 of the second portion 415 and may be disposed in the flat region FA.

[0076] The first thickness t1 of the window bonding member 410 may be approximately 1 mm or less. According to an exemplary embodiment of the invention, the first thickness t1 of the window bonding member 410 may be approximately 0.05 to 1 mm. While the lower limit of the thickness of the window bonding member 410 is not particularly limited, it may be approximately 10 μm or greater to obtain minimum adhesive force, and more specifically, approximately 50 μm or greater.

[0077] The window bonding member 410 may include a single adhesive layer or may include multiple adhesive layers stacked on top of each other, and may include adhesive layers, such as double-sided tape, located on each side of the substrate.

[0078] In some exemplary embodiments of the present invention, the window bonding member 410 may include a silicone-based adhesive. The silicone-based adhesive may include a siloxane resin. For example, the silicone-based adhesive may include a silicone compound containing a polyorganosiloxane compound. The silicone compound may include crosslinkable functional groups, such as vinyl groups. The silicone-based adhesive may also include an MQ resin having a three-dimensional molecular structure, which is in the form of a three-dimensional network including monofunctional and tetrafunctional siloxane units. The silicone-based adhesive may also include additives, which include at least one of borane compounds and borate ester (salt) compounds.

[0079] In some exemplary embodiments of the present disclosure, the window joint member 410 can include an acrylic adhesive. The acrylic adhesive can include an acrylic polymer. The acrylic polymer is a polymerized acrylic monomer, and can be a main material of the acrylic polymer. The acrylic monomer can include ethyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, n-nonyl acrylate, isononyl acrylate, n-decyl acrylate, isodecyl acrylate, n-dodecyl acrylate, n-tridecyl acrylate, n-tetradecyl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, 6-hydroxyhexyl acrylate, 8-hydroxyoctyl acrylate, 10-hydroxydecyl acrylate, 12-hydroxylauryl acrylate, methyl [4-(hydroxymethyl)cyclohexyl] acrylate, or the like. In addition to the acrylic polymer, the acrylic adhesive can include an azo initiator (such as 2,2'-azo-bis-isobutyronitrile), a filler (such as silica and zirconia), a crosslinking agent, and an antistatic agent (such as PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrene sulfonate)).

[0080] In some exemplary embodiments of the present disclosure, the window joint member 410 can include a crystalline polymer and a rubber-based polymer. The crystalline polymer can be polypropylene, syndiotactic polystyrene, polyamide, polycaprolactone, polycarbonate-diol, polyethylene terephthalate (PET), polyphenylene sulfide, polybutylene terephthalate (PBT), polyarylate (PAR), poly(DPAA), polyetherimide (PEI), polyacetal, polyoxymethylene (POM), or the like.

[0081] The rubber-based polymer can be polybutadiene, polyisoprene, polychloroprene, polyisobutylene, cellulose acetate, polyvinyl acetate, or a copolymer thereof. The weight ratio of the crystalline polymer and the rubber polymer can be in the range of 1:0.3 to 1:1.5. In addition, the window joint member 410 can further include a urethane polymer, an ester polymer, and / or a (meth)acrylate polymer, and can further include a coupling agent (such as a silane coupling agent, a titanate coupling agent, and a chromium coupling agent), an adhesion promoter (such as a rosin resin, a rosin ester resin, a terpene phenol resin, and a terpene resin), an anti-yellowing agent, an antioxidant, or the like.

[0082] The constituent material and the constituent ingredient of the window joint member 410 are not limited to those described above, and any other adhesive material of a constituent material or a constituent ingredient can be applied.

[0083] After the window joining member 410 is disposed between the polarizing member 200 and the cover window 100, the window joining member 410 can be cured by an ultraviolet (UV) curing process. The modulus of the window joining member 410 can be increased after it is cured by UV, while the creep characteristics and penetration depth of the window joining member 410 can be reduced after it is cured by UV.

[0084] The modulus of the window joint member 410 can be approximately 0.61 MPa or greater. Furthermore, the creep characteristic of the window joint member 410 can be approximately 70% or less. Additionally, the penetration depth of the window joint member 410 can be approximately 13 μm or less.

[0085] Figure 4 This is a perspective view showing the ultraviolet curing of a window bonding member of a display device according to an exemplary embodiment of the present invention. Figure 5 This is a cross-sectional view showing the ultraviolet curing of a window bonding member of a display device according to an exemplary embodiment of the present invention.

[0086] refer to Figure 4 and Figure 5 In the display device 1 according to an exemplary embodiment of the present invention, a window bonding member 410 may be disposed on a polarizing member 200, a cover window 100 may be disposed on the window bonding member 410, and then an ultraviolet (UV) curing process may be performed. As described above, the physical properties of the window bonding member 410 may be changed after the UV curing process.

[0087] The UV curing process can be performed by a UV curing device 800 that irradiates the window joint member 410 with ultraviolet light (UV1).

[0088] like Figure 4 As shown, the ultraviolet curing apparatus 800 can irradiate the display device 1 with ultraviolet UV1 while moving in the second direction (y-axis direction). The ultraviolet curing apparatus 800 can also irradiate the window bonding member 410 of the display device 1 with ultraviolet UV1 while moving from the lower short side to the upper short side of the display device 1.

[0089] The cumulative amount of ultraviolet UV1 irradiated onto the display device 1 from the ultraviolet curing device 800 can be approximately 1,000 mJ / cm². 2 Up to 8,000 mJ / cm 2 Within the range of [specific range]. According to an exemplary embodiment of the present invention, the cumulative amount of ultraviolet light UV1 can be approximately 2,000 mJ / cm². 2 Up to 8,000 mJ / cm 2 Within the range.

[0090] The speed of the ultraviolet curing device 800 can be in the range of approximately 10 mm / s to 50 mm / s. The ultraviolet curing device 800 can irradiate the ultraviolet rays UV1 onto the window bonding member 410 of the display apparatus 1 while moving from the lower short side to the upper short side of the display apparatus 1 at a speed in the above range.

[0091] However, it should be understood that the present application is not limited thereto. The ultraviolet curing device 800 can irradiate the ultraviolet rays UV1 onto the display apparatus 1 while moving in the first direction (x-axis direction). In other words, the ultraviolet curing device 800 can irradiate the ultraviolet rays UV1 onto the display apparatus 1 while moving from the left long side to the right long side of the display apparatus 1 or otherwise.

[0092] The ultraviolet curing device 800 can irradiate the ultraviolet rays UV1 toward the upper side of the display apparatus 1. The angle formed by the path of the irradiated ultraviolet rays UV1 and the flat area FA of the display apparatus 1 can be substantially a right angle. The ultraviolet rays UV1 irradiated into the flat area FA pass through the cover window 100 and can then be incident on the window bonding member 410. The ultraviolet rays UV1 irradiated into the portions of the curved areas CA1 and CA2 where the light-shielding pattern 110 is not provided can pass through the cover window 100 and can then be incident on the window bonding member 410. On the other hand, the ultraviolet rays UV1 irradiated into the portions of the curved areas CA1 and CA2 where the light-shielding pattern 110 is provided can pass through the cover window 100 and the light-shielding pattern 110 and can then be incident on the window bonding member 410. As shown in FIG. 6, the ultraviolet rays UV1 irradiated into the portions of the curved areas CA1 and CA2 where the light-shielding pattern 110 is provided are reflected or absorbed by the light-shielding pattern 110 and thus the amount of light irradiated onto the window bonding member 410 can be reduced compared to the amount of the ultraviolet rays UV1 irradiated into the portions of the curved areas CA1 and CA2 where the light-shielding pattern 110 is not provided or the flat area FA. As a result, the second portion 415 of the window bonding member 410 provided in the portions of the curved areas CA1 and CA2 where the light-shielding pattern 110 is provided can have a modulus smaller than the modulus of the first portion 411 and the modulus of the second portion 415 provided in the portions of the curved areas CA1 and CA2 where the light-shielding pattern 110 is not provided. Figure 5

[0093] Further, the second portion 415 is more flexed in the thickness direction (z-axis direction) than the first portion 411. In this case, the amount of the ultraviolet rays UV1 irradiated onto the second portion 415 from the ultraviolet curing device 800 can be smaller than the amount of the ultraviolet rays UV1 irradiated onto the first portion 411. Thus, the modulus of the second portion 415 of the window bonding member 410 can be smaller than the modulus of the first portion 411 of the window bonding member 410.

[0094] ​If the modulus of the second portion 415 of the window bonding member 410 is less than a normal reference value, the coupling force between the cover window 100 and the second portion 415 of the window bonding member 410 in the bending regions CA1 and CA2 can be weakened, and thus, the cover window 100 and the second portion 415 can be separated from each other in the bending regions CA1 and CA2. In addition, a bubble can be generated in the second portion 415 of the window bonding member 410.

[0095] In this regard, in the display device 1 according to the exemplary embodiment of the present application, the modulus of the second portion 415 of the window bonding member 410 can be approximately 0.61 MPa or more. In other words, the cumulative amount of the ultraviolet UV1 and / or the speed of the ultraviolet curing device 800 can be reduced so that the modulus of the second portion 415 of the window bonding member 410 is approximately 0.61 MPa or more. To make the modulus of the second portion 415 of the window bonding member 410 approximately 0.61 MPa or more, when the thickness of the window bonding member 410 as a thin film is in the range of approximately 0.05 mm to 1 mm, the cumulative amount of the ultraviolet UV1 can be in the range of approximately 1,000 mJ / cm2to 8,000 mJ / cm2, and the speed of the ultraviolet curing device 800 can be in the range of approximately 10 mm / s to 50 mm / s. 2 2

[0096] The modulus of the window bonding member 410 can be measured after the window bonding member 410 is included in the display device 1 and then removed. The modulus of such a thin adhesive layer can be measured by a nanoindenter tester such as a bioindenter (available from Anton Paar GmbH) or a nanoindenter. In other words, the modulus of the thin adhesive layer can be measured according to a stylus evaluation method.

[0097] In general, a rheometer for measuring the modulus of an adhesive material cannot be used for an adhesive layer having a thickness of 500 µm or less. The modulus can be measured from a bulk adhesive material or a stack of multiple adhesive layers having a thickness greater than 500 µm or 700 µm. However, the modulus measured from the bulk adhesive material or the stack of multiple adhesive layers can be different from the modulus of the thin adhesive layer actually applied to the display device 1. In particular, the modulus of the adhesive material can change during a heat treatment process for laminating multiple layers to form a stacked structure of the display device 1. In doing so, the modulus can change according to different process variables. Therefore, it can not be possible to derive the modulus of the bonding member applied in the display device 1 only by using the modulus measured from the bulk adhesive material. Thus, the actual modulus required for the display device 1 can not be accurately determined.

[0098] ​​In contrast, a nanoindenter can be used to measure the modulus of a thin film of 500 μm or less, or even a thin film of 1 μm. Accordingly, the modulus of the window bonding member 410 can be precisely measured by reverse engineering by measuring the modulus from the thin film or by exposing or separating the window bonding member 410 from the display apparatus 1. For example, each window bonding member 410 can be extracted by using liquid nitrogen to separate the layer, and the modulus of the extracted window bonding member 410 can be measured using a nanoindenter. By controlling the actual modulus of the window bonding member 410 based on the modulus thus measured, the adhesive properties of the window bonding member 410 of the display apparatus 1 can be precisely managed. The adhesive properties can be controlled by preventing separation between the cover window 100 and the polarizing member 200 and adjusting the restoring force and the peeling force. For example, if the measured modulus exceeds the above-described proper range, it can be determined that the window bonding member 410 is defective. In this case, the good adhesive properties of the normal product can be maintained. Furthermore, by deriving the modulus required to manufacture each window bonding member 410 based on the measured modulus and adjusting it accordingly, the percentage of defective products can be further reduced. The adhesive properties of the adhesive material can be controlled by process variables during the manufacturing process, such as the type, ratio, heat treatment temperature, or UV exposure of the material, etc.

[0099] The creep property, which is one of the adhesive properties, is generally proportional to the viscosity. The creep property of the window bonding member 410 can be in the range of 30% to 70%.

[0100] The creep property of the second portion 415 of the window bonding member 410 can be greater than the creep property of the first portion 411 of the window bonding member 410. Even if the creep properties of the first portion 411 and the second portion 415 are different from each other, the creep properties of the first portion 411 and the second portion 415 can be in the range of 30% to 70%.

[0101] The creep property can also be measured by a nanoindenter. The creep property of a thin film or the window bonding member 410 applied to the display apparatus 1 and then separated from the display apparatus 1 can be in the above-described range of 30% to 70%.

[0102] Hereinafter, a method of measuring the modulus and the creep property by a biological indenter will be described.

[0103] Figure 6 is a schematic diagram illustrating a method of measuring the modulus and the creep property of an adhesive layer by a biological indenter according to an exemplary embodiment of the present application. Figure 7 is a table illustrating the measurement conditions of a biological indenter according to an exemplary embodiment of the present application.

[0104] Reference Figure 6 and Figure 7The biological indenter includes an indenter RBL. The indenter RBL can be in the shape of a sphere (a ruby sphere) or can include at least a portion of a sphere. The diameter (D) of the indenter RBL having a spherical shape can be, but is not limited to, 1 mm.

[0105] In the example embodiment of the present application, the adhesive layer 411 (the first portion 411 of the window joint member 410) is cut into a size of 2 cm x 2 cm as a sample. When a release film is attached to the adhesive layer 411, the release film is removed, and then the adhesive layer 411 is attached to a flat holder HDR. Subsequently, the flat holder HDR is placed on a plate PLT. Subsequently, the indenter RBL is pressed against the surface of the adhesive layer 411 with a force having a maximum load of 0.5 mN and is held for 120 seconds. The loading / unloading rate (e.g., the pressing rate) of the indenter RBL can be 3.0 mN / min. The penetration depth during such pressurization is measured. The indentation test is performed at a plurality of points (e.g., 15 points) on a single sample by the indenter RBL of the biological indenter. The penetration depth can be expressed as an average value of the results of a plurality of tests.

[0106] Figure 7 The table in Table 1 lists items and corresponding measurement conditions. For example, the instrument can be an Anton Paar UNHT-BIO, the tip of the instrument can be a ruby sphere having a radius of 500 pm, the load of the instrument can be 0.5 mN, the loading / unloading rate of the instrument can be 3 mN / min, the holding time of the instrument can be 120 seconds, the Poisson’s ratio of the instrument can be 0.3, and the Kelvin-Voigt model element count of the instrument can be 2.

[0107] Figure 8 and Figure 9 is a sectional view showing the penetration depth of the first portion of the window joint member measured by the biological indenter. Figure 10 is a graph showing the relationship between the penetration depth and the load. Figure 11 is a graph showing the change in the penetration depth with time before and after the maximum load holding time. Figure 12 is a sectional view showing the penetration depth of the second portion of the window joint member measured by the biological indenter.

[0108] Referring to Figures 8 to 11 The penetration depth of the indenter RBL increases with the indentation load of the indenter RBL. The smaller the modulus of the adhesive layer, the more it deforms due to stress. Therefore, in Figure 10In the graph, for a given indentation load, the penetration depth increases as the modulus decreases. When the indenter RBL is held at the maximum load, the penetration depth continues to increase due to the viscosity of the adhesive layer 411. During the maximum load holding time, the greater the creep characteristics, the greater the penetration depth. During the maximum load holding time, the rate of increase in penetration depth gradually decreases with time (e.g., Figure 11 (The slope decreases in the curve). The penetration depth may not increase beyond a certain time point, and if maintained for a long time, it can remain at a certain value. The penetration depth decreases when the indenter RBL is unloaded. The greater the restoring force, the smaller the penetration depth after the indenter RBL is unloaded.

[0109] According to an exemplary embodiment of the present invention, the penetration depth of the first portion 411 of the window joining member 410 of the display device 1 ( Figure 9 The depth h2 at which the maximum load is maintained can be approximately 13 μm or less. Figure 12 The depth h3 at which the maximum load is maintained can be less than the penetration depth of the first portion 411 of the window joint member 410. In other words, the depth h2 can be deeper than the depth h3. Even if the penetration depths of the first portion 411 and the second portion 415 are different from each other, the penetration depths of the first portion 411 and the second portion 415 can be equal to or less than approximately 13 μm. Figure 8 In this context, h1 can refer to the penetration depth formed under a load less than the maximum load.

[0110] Once the penetration depth is measured as described above, the modulus E* can be calculated using the following Equation 1:

[0111] [Equation 1]

[0112]

[0113] Where P represents the maximum load, R represents the radius of the indenter RBL, and h represents the penetration depth. The penetration depth is represented by the depth h3 under the maximum load. Incidentally, when the bio-indenter has a predetermined offset depth h... 偏移 At that time, the penetration depth of Equation 1 can be expressed as the depth h3 measured by the bio-pressure head under maximum load minus the offset depth h. 偏移 Offset depth h 偏移 This refers to the distance at the surface of the adhesive layer 411 that is identified as penetrated, even when the bio-indenter measures the penetration depth and the indenter RBL is close to the adhesive layer 411, due to the van der Waals force. Therefore, the penetration depth can be calculated by subtracting the offset depth h from the penetration depth measured by the bio-indenter. 偏移 To calculate the actual penetration depth. To reduce the impact of the offset depth h... 偏移The measurement error caused thereby can be calculated by specifying the load slope in the penetration depth-load graph in a range from 30% to 98% of the maximum load (0.15 to 0.49 mN) to calculate the modulus. A more precise modulus E can be derived from the modulus E* by the following equation 2:

[0114] [Equation 2]

[0115]

[0116] wherein V denotes the Poisson's ratio, which represents the ratio between the lateral strain and the longitudinal strain when a material is stretched in the direction of the tensile force under the action of the tensile force, i.e. V = -e' / e, wherein e' is the lateral strain and e is the longitudinal strain. Usually, the lateral strain and the longitudinal strain have different signs, so that the Poisson's ratio has a positive value.

[0117] Furthermore, the creep property (C IT ) can be calculated by the following equation 3:

[0118] [Equation 3]

[0119]

[0120] In this way, each window joint member 410 of the display apparatus 1 can have an appropriate penetration depth, and from this a modulus and a creep property are derived. Thus, the adhesive properties of the window joint members 410 of the display apparatus 1 can be precisely controlled, such as preventing separation between the cover window 100 and the polarizing member 200, and adjusting the restoring force and the peeling force.

[0121] Hereinafter, other exemplary embodiments of the present application will be described. In the following description, the same or similar elements can be designated by the same or similar reference numerals, and thus, a redundant description thereof will be omitted or be simplified.

[0122] Figure 13 is a perspective view of a display apparatus according to another exemplary embodiment of the present application. Figure 14 is a cross-sectional view taken along the line XIV-XIV' of Figure 13 .

[0123] Referring to Figure 13 and Figure 14 , the display apparatus 2 according to the present embodiment differs from the display apparatus 1 of Figure 1 and Figure 2 in that it further includes a third curved area CA3 and a fourth curved area CA4.

[0124] More specifically, the display apparatus 2 according to the present embodiment can further include a third curved area CA3 and a fourth curved area CA4.

[0125] The third curved area CA3 can be located on the upper short side of the display device 2, and the fourth curved area CA4 can be located on the lower short side of the display device 2.

[0126] The curved areas CA3 and CA4 can extend from the upper side and the lower side of the flat area FA of the display device 2, respectively. The curved areas CA3 and CA4 can be curved surfaces. However, it should be understood that the present application is not limited thereto. The curved areas CA3 and CA4 can be flat surfaces. When the curved areas CA3 and CA4 are flat, the angle between the flat area FA and the curved areas CA3 and CA4 can be an obtuse angle. When the curved areas CA3 and CA4 are curved surfaces, the curved areas CA3 and CA4 can have a constant curvature or a varying curvature.

[0127] The cover window 100 can be disposed in the flat area FA and the curved areas CA1, CA2, CA3, and CA4.

[0128] The window bonding member 410_1 can be disposed in portions of the curved areas CA1, CA2, CA3, and CA4 and the flat area FA.

[0129] The window bonding member 410_1 can be indented inward from the cover window 100 and the polarizing member 200. In other words, the window bonding member 410_1 can expose the surface of the polarizing member 200 facing the cover window 100 in the curved areas CA3 and CA4. However, it should be understood that the present application is not limited thereto. In the curved areas CA3 and CA4, the window bonding member 410_1 can not expose the surface of the polarizing member 200 facing the cover window 100, but can completely cover the surface of the polarizing member 200 facing the cover window 100. The window bonding member 410_1 can be optically transparent.

[0130] The window bonding member 410_1 according to the present embodiment can include a first portion 411 disposed in the flat area FA and a second portion 415_1 disposed in the curved areas CA1, CA2, CA3, and CA4.

[0131] The physical properties of the second portion 415_1 of the window bonding member 410_1 can be substantially the same as the physical properties of the second portion 415 of the window bonding member 410 described above with reference to Figure 2 The physical properties of the second portion 415_1 of the window bonding member 410_1 can be substantially the same as the physical properties of the second portion 415 of the window bonding member 410 described above with reference to

[0132] According to the exemplary embodiments of the present application, it is possible to prevent the cover window from being separated from the polarizing member due to a weak coupling force of the window bonding member in the curved areas, and to suppress bubbles in the window bonding member.

[0133] While exemplary embodiments of the present application have been described with reference to the attached figures, it will be understood by those skilled in the art that various changes in form and details can be made therein without departing from the technical idea or scope of the application.

Claims

1. A display device comprising: a display panel; a polarizing member overlapping the display panel; a cover window overlapping the polarizing member; and a window bonding member disposed between the polarizing member and the cover window, wherein a penetration depth of the window bonding member measured by an indenter tester is equal to or less than 13 µm, wherein the display device includes a flat area, a first curved area on a first side of the flat area, and a second curved area on a second side of the flat area, wherein the window bonding member includes a first portion disposed in the flat area and a second portion disposed in the first curved area and the second curved area, wherein a modulus of each of the second portions of the window bonding member is equal to or greater than 0.61 MPa, wherein the modulus of each of the second portions of the window bonding member is measured by using the indenter tester, wherein a tip of the indenter tester is a ruby ball having a radius of 500 µm, a load of the indenter tester is 0.5 mN, a loading / unloading rate of the indenter tester is 3 mN / min, a holding time of the indenter tester is 120 seconds, a Poisson’s ratio of the indenter tester is 0.3, and a number of Kelvin-Voigt model elements of the indenter tester is 2, wherein the display device further includes a light-shielding pattern disposed directly on a surface of the cover window facing the window bonding member, wherein the light-shielding pattern is disposed in the first curved area and the second curved area, wherein the window bonding member exposes a surface of the polarizing member in the first curved area and the second curved area facing the light-shielding pattern and a surface of the light-shielding pattern in the first curved area and the second curved area facing the polarizing member, in each of the first curved area and the second curved area, there is a space directly between the exposed surface of the polarizing member and the exposed surface of the light-shielding pattern. The penetration depth is measured by the indenter tester by pressing an indenter against the window bonding member, holding the indenter at a load of 0.5 mN for 120 seconds, and then unloading the indenter.

2. The display device of claim 1, wherein, The creep property of the window bonding member is in a range of 30% to 70%.

3. The display device of claim 1, wherein, The window bonding member is a thin film having a thickness of 0.05 mm to 1 mm, and wherein the modulus and the creep property of the window bonding member are measured from the thin film.

4. The display device of claim 3, wherein, The modulus and the creep property of the window bonding member are measured from the window bonding member separated from the display device by using the indenter tester.

5. The display device of claim 3, wherein, 6.The display device of claim 1, a penetration depth of the first portion measured by the indenter tester is less than a penetration depth of each of the second portions measured by the indenter tester. wherein a modulus of the first portion is greater than the modulus of each of the second portions, and a creep property of the first portion is less than the creep property of each of the second portions.

7. The display device of claim 6, wherein, ​ 8. The display device of claim 3, wherein, The window bonding member is ultraviolet-cured.

9. The display device of claim 8, wherein, The window bonding member is disposed between the polarizing member and the cover window, and then is ultraviolet-cured.

10. A display device comprising a flat area, a first curved area on a first side of the flat area, and a second curved area on a second side of the flat area, wherein, The display device further comprises: a display panel; a polarizing member overlapping the display panel; a cover window overlapping the polarizing member; and a window bonding member disposed between the polarizing member and the cover window, and comprising a first portion disposed in the flat area and a second portion disposed in the first curved area and the second curved area, and wherein a modulus of each of the second portions of the window bonding member is equal to or greater than 0.61 MPa, wherein the modulus of each of the second portions of the window bonding member is measured by using an indenter tester, wherein a tip of the indenter tester is a ruby ball having a radius of 500 pm, a load of the indenter tester is 0.5 mN, a loading / unloading rate of the indenter tester is 3 mN / min, a holding time of the indenter tester is 120 seconds, a Poisson's ratio of the indenter tester is 0.3, and a number of Kelvin-Voigt model elements of the indenter tester is 2, wherein the display device further comprises a light-shielding pattern disposed directly on a surface of the cover window facing the window bonding member, wherein the light-shielding pattern is disposed in the first curved area and the second curved area, wherein the window bonding member exposes a surface of the polarizing member in the first curved area and the second curved area facing the light-shielding pattern and a surface of the light-shielding pattern in the first curved area and the second curved area facing the polarizing member, in each of the first curved area and the second curved area, there is a space directly between the exposed surface of the polarizing member and the exposed surface of the light-shielding pattern.

11. The display device of claim 10, wherein, A modulus of the first portion is greater than the modulus of each of the second portions.

12. The display device of claim 11, wherein, A creep property of the window bonding member is in a range of 30% to 70%, and a creep property of the first portion is less than the creep property of each of the second portions.

13. The display device of claim 12, wherein, A penetration depth of the window bonding member measured by the indenter tester is equal to or less than 13 pm, and wherein a penetration depth of the first portion is less than a penetration depth of each of the second portions.

14. The display device of claim 13, wherein, The window bonding member is a thin film having a thickness of 0.05 mm to 1 mm, and wherein the modulus of the window bonding member and the creep property of the window bonding member are measured from the thin film.

15. The display device of claim 13, wherein, The modulus of the window bonding member and the creep property of the window bonding member are measured from the window bonding member separated from the display device by using the indenter tester.

16. A display device comprising a flat area, a first curved area on a first side of the flat area, and a second curved area on a second side of the flat area, wherein The display device further includes: a display panel; a polarizing member disposed on the display panel; a cover window disposed on the polarizing member; and a window bonding member disposed between the polarizing member and the cover window, wherein the window bonding member includes a first portion disposed in the flat area and a second portion disposed in the first curved area and the second curved area, and wherein a modulus of the first portion is equal to or greater than 0.61 MPa and a modulus of each of the second portions is equal to or greater than 0.61 MPa, wherein the modulus of each of the second portions of the window bonding member is measured by using an indentation tester, wherein a tip of the indentation tester is a ruby ball having a radius of 500 µm, a load of the indentation tester is 0.5 mN, a loading / unloading rate of the indentation tester is 3 mN / min, a holding time of the indentation tester is 120 seconds, a Poisson’s ratio of the indentation tester is 0.3, and a number of Kelvin- Voigt model elements of the indentation tester is 2, wherein the display device further includes a light-shielding pattern disposed directly on a surface of the cover window facing the window bonding member, wherein the light-shielding pattern is disposed in the first curved area and the second curved area, wherein the window bonding member exposes a surface of the polarizing member in the first curved area and the second curved area facing the light-shielding pattern and a surface of the light-shielding pattern in the first curved area and the second curved area facing the polarizing member, in each of the first curved area and the second curved area, there is a space directly between the exposed surface of the polarizing member and the exposed surface of the light-shielding pattern.

17. The display device of claim 16, wherein, A creep property of the first portion is in a range of 30% to 70% and a creep property of each of the second portions is in a range of 30% to 70%, and wherein the creep property of the first portion is less than the creep property of each of the second portions.

18. The display device of claim 17, wherein, A penetration depth of the first portion is equal to or less than 13 µm and a penetration depth of each of the second portions is equal to or less than 13 µm, wherein the penetration depth of the first portion and the penetration depth of each of the second portions are measured by the indentation tester, and the penetration depth of the first portion is less than the penetration depth of each of the second portions.

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