Display device

Abstract

A display device includes: a flat portion defined by a first direction and a second direction intersecting the first direction; a curved portion provided on at least one side of the flat portion and curved in a third direction perpendicular to the first direction and the second direction; a display panel provided above the flat portion and the curved portion; a cover window provided on the display panel and above the flat portion and the curved portion; and a bonding member provided between the display panel and the cover window, wherein the bonding member has a modulus that increases as temperature increases.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and all benefits arising from Korean Patent Application No. 10-2020-0064074, filed on May 28, 2020, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] An embodiment of the present invention relates to a display device. Background Art

[0004] Electronic devices that provide images to users, such as smartphones, tablet personal computers ("PCs"), digital cameras, laptop computers, navigation devices, and smart televisions, may include a display device for displaying the images.

[0005] The display device may include: a display panel for generating a screen; a cover window for covering the display panel; and a joining member for joining the display panel and the cover window together. Summary of the Invention

[0006] After the display panel and the cover window are bonded using a bonding member, bubbles may be trapped in the bonding member. The deeper the bubbles penetrate, the more likely the design of the display device will be restricted.

[0007] A feature of the present invention provides a display device composed of a display panel and a cover window joined together using a joining member in which the number of trapped bubbles is reduced.

[0008] However, the features of the present invention are not limited to the features set forth herein. The above and other features of the present invention will become more apparent to those skilled in the art to which the present invention pertains by referencing the detailed description of the present invention given below.

[0009] In an embodiment, a display device includes: a flat portion, the flat portion being defined by a first direction and a second direction intersecting the first direction; a curved portion, the curved portion being arranged on at least one side of the flat portion and being curved in a third direction perpendicular to the first direction and the second direction; a display panel, the display panel being arranged above the flat portion and the curved portion; a cover window, the cover window being arranged on the display panel and above the flat portion and the curved portion; and a joining member, the joining member being arranged between the display panel and the cover window, wherein the joining member has a modulus that increases as temperature increases.

[0010] According to another embodiment, a display device includes: a display panel; a cover window, which is arranged on the display panel and extends outward beyond the display panel; a joining member, which is arranged between the display panel and the cover window; and a printed pattern, which is arranged between the joining member and the cover window, wherein the printed pattern extends from an end of the cover window and partially overlaps with the display panel, the joining member is in direct contact with one surface and side surface of the printed pattern, and under conditions of a temperature ranging from about 60 degrees Celsius (°C) to about 80 degrees Celsius and a pressure ranging from about 6 bar to about 8 bar, the joining member has a modulus of about 800 kilopascals (kPa) to about 1000 kPa.

[0011] In an embodiment, the number of bubbles trapped in a bonding member for bonding a display panel and a cover window constituting a display device may be reduced.

[0012] The effects of the present invention are not limited to the aforementioned effects, and include various other effects in the specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The above and other embodiments, advantages and features of the present invention will become more apparent by describing in detail embodiments of the present invention with reference to the accompanying drawings, in which:

[0014] Figure 1 is a perspective view of an embodiment of a display device;

[0015] Figure 2 It is along Figure 1 A cross-sectional view taken along line II';

[0016] Figure 3 yes Figure 2 an enlarged cross-sectional view of a flat portion and a portion of a first curved portion;

[0017] Figure 4 is a graph showing changes in peel stress and shear stress according to the content of the first monomer;

[0018] Figure 5 is a graph showing changes in transition temperature according to the content of the first monomer;

[0019] Figure 6 is a schematic diagram illustrating an embodiment of a method for measuring the modulus and creep properties of an adhesive layer by a bioindenter;

[0020] Figure 7 is a graph showing the relationship between indentation depth and load;

[0021] Figure 8is a graph showing changes in indentation depth according to time before and after a maximum load holding period;

[0022] Figure 9 is a schematic diagram illustrating an embodiment of joining a cover window and a lower member of the cover window;

[0023] Figure 10 is a cross-sectional view showing an embodiment of a cover window and a lower member of the cover window being joined together;

[0024] Figure 11 yes Figure 10 an enlarged cross-sectional view of a flat portion and a portion of a first curved portion;

[0025] Figure 12 yes Figure 11 An enlarged cross-sectional view of region A;

[0026] Figure 13 is a cross-sectional view illustrating an embodiment of an autoclave process;

[0027] Figure 14 is a cross-sectional view illustrating prevention of external gas from penetrating into the second bonding member;

[0028] Figure 15 is a graph showing creep characteristics of each sample as a function of time;

[0029] Figure 16 is a graph showing stress relaxation according to time for each sample;

[0030] Figure 17 is a perspective view of another embodiment of a display device;

[0031] Figure 18 yes Figure 17 A cross-sectional view of a display device; and

[0032] Figure 19 is a perspective view of another embodiment of a display device. DETAILED DESCRIPTION

[0033] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which various embodiments are shown. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art. Like reference numerals represent like elements throughout.

[0034] It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may be present therebetween. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.

[0035] It will be understood that although the terms "first," "second," "third," etc., may be used herein to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or part from another element, component, region, layer, or part. Therefore, without departing from the teachings herein, the "first element," "component," "region," "layer," or "part" discussed below may be referred to as a second element, component, region, layer, or part.

[0036] The terms used herein are only for the purpose of describing specific embodiments and are not intended to be limiting. As used herein, unless the context clearly indicates otherwise, the singular forms "one", "a kind of" and "the" are also intended to include plural forms, including "at least one (kind) of..." "Or" means "and / or". As used herein, the term "and / or" includes any combination and all combinations of one or more related listed items. It will be further understood that when used in this specification, the terms "include" and / or "comprise" or "contain" and / or "have" illustrate the presence of stated features, regions, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, regions, wholes, steps, operations, elements, components and / or their groups.

[0037] In addition, relative terms such as "lower" or "bottom" and "upper" or "top" may be used herein to describe the relationship of one element to another element as shown in the accompanying drawings. It will be understood that relative terms are intended to cover different orientations of the device in addition to the orientation depicted in the accompanying drawings. For example, if the device in one of the accompanying drawings is turned over, the element described as being "below" the other elements will then be oriented "above" the other elements. Thus, the exemplary term "lower" can cover both "lower" and "above" orientations depending on the specific orientation of the accompanying drawings. Similarly, if the device in one of the accompanying drawings is turned over, the element described as being "below" or "beneath" the other elements will then be oriented "above" the other elements. Thus, the exemplary terms "below" or "beneath" can cover both "above" and "below" orientations.

[0038] As used herein, "about" or "approximately" is inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, taking into account the measurements in question and errors associated with the measurement of the particular quantity (i.e., limitations of the measurement system). For example, "about" can mean within one or more standard deviations, or within ±30%, ±20%, ±10%, or ±5% of the stated value.

[0039] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present disclosure belongs. It will be further understood that, unless expressly defined as such herein, terms such as those defined in general dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense.

[0040] The embodiments are described herein with reference to cross-sectional views which are schematic diagrams of idealized embodiments. As such, variations in the shapes of the illustrations due to, for example, manufacturing techniques and / or tolerances are anticipated. Therefore, the embodiments described herein should not be construed as limited to the specific shapes of the regions shown herein, but rather are intended to include deviations in shape due to, for example, manufacturing. For example, a region shown or described as flat may typically have rough and / or nonlinear features. Furthermore, sharp corners shown may be rounded. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to illustrate the precise shape of the regions, nor are they intended to limit the scope of the present claims.

[0041] Figure 1 is a perspective view of an embodiment of a display device.

[0042] Reference Figure 1 , the display device 1 may have a quadrilateral (e.g., rectangular) shape in a plan view. In an embodiment, the display device 1 may include short sides extending along the first direction DR1 and long sides extending along the second direction DR2. The angle at which the short sides extending along the first direction DR1 and the long sides extending along the second direction DR2 intersect may be a right angle or rounded with a predetermined curvature. The planar shape of the display device 1 is not limited to a quadrilateral (e.g., rectangular) and may be provided in other polygonal shapes, a circular shape, or an elliptical shape.

[0043] In an embodiment, the first direction DR1 and the second direction DR2 intersect each other in different directions. Figure 1In the perspective view of FIG, for convenience of description, the first direction DR1 may refer to the extending direction of the short side of the display device 1, and the second direction DR2 may refer to the extending direction of the long side of the display device 1. However, it should be understood that the directions mentioned in the embodiments refer to relative directions, and the embodiments are not limited to the mentioned directions.

[0044] The display device 1 may include a flat portion MR provided to be flat and a curved portion extending from at least one side of the flat portion MR. The planar shape of the flat portion MR may be similar to the planar shape of the display device 1. The flat portion MR may include short sides extending along the first direction DR1 and long sides extending along the second direction DR2.

[0045] In an embodiment, there may be multiple curved portions. For example, Figure 1 As shown in , there may be two bent portions. The bent portion may include a first bent portion SR1 extending from a first long side of the flat portion MR (a long side disposed on one side of the flat portion MR in the first direction DR1) and a second bent portion SR2 extending from a second long side of the flat portion MR (a long side disposed on the other side of the flat portion MR in the first direction DR1).

[0046] The flat portion MR may be provided on a plane. Each of the curved portions SR1 and SR2 may be bent from the flat portion MR in a third direction DR3 (hereinafter, also referred to as a thickness direction). Each of the curved portions SR1 and SR2 may be provided on a plane. Each of the curved portions SR1 and SR2 may be bent from the flat portion MR to have a curvature (or curvature angle), which may be an obtuse angle, but is not limited thereto, and may be a right angle.

[0047] In some embodiments, each of the curved portions SR1 and SR2 may not be disposed on a plane and may have a curved surface having a predetermined curvature. The predetermined curvature may be constant, but is not limited thereto, and the predetermined curvature may vary.

[0048] The display device 1 can also be defined as having a display area DA and a non-display area NA according to the screen display. The display area DA can be an area where an image is displayed, and the non-display area NA can be an area where an image is not displayed. A plurality of transistors can be provided in the display area DA. The display area DA can be provided at the central portion of the display device 1, and the non-display area NA can be provided around the display area DA. In an embodiment, for example, the non-display area NA can completely surround the display area DA. The central portion of the flat portion MR and the portions of the curved portions SR1 and SR2 adjacent to the long sides of the flat portion MR can completely overlap with the display area DA. The edge portions of the short sides of the flat portion MR and the remaining portions of the curved portions SR1 and SR2 except for the portions adjacent to the long sides of the flat portion MR can completely overlap with the non-display area NA.

[0049] Figure 2 It is along Figure 1 A cross-sectional view taken along line II'.

[0050] Reference Figure 2 The display device 1 may include a display panel PN, a polarizing layer POL, a cover window CW, and a lower cover panel CP. The display device 1 may further include: a first bonding member AM1 disposed between the display panel PN and the polarizing layer POL; a second bonding member AM2 disposed between the polarizing layer POL and the cover window CW; and a third bonding member AM3 disposed between the display panel PN and the lower cover panel CP.

[0051] The aforementioned display panel PN, polarization layer POL, cover window CW, lower cover panel CP, and bonding members AM1 to AM3 may be disposed on the entire flat portion MR and the curved portions SR1 and SR2.

[0052] The display panel PN may include a circuit driving layer arranged on a substrate. The circuit driving layer may include a circuit that drives the light-emitting layer of the pixel. The circuit driving layer may include a plurality of thin-film transistors. A light-emitting layer may be arranged on the circuit driving layer. The light-emitting layer may include an organic light-emitting layer. The light-emitting layer may emit light with various brightness levels according to a drive signal transmitted from the circuit driving layer. An encapsulation layer may be arranged on the light-emitting layer. The encapsulation layer may include an inorganic layer or a stack of inorganic and organic layers. In another embodiment, the encapsulation layer may be implemented using glass or an encapsulation film. A touch layer may be arranged on the encapsulation layer. The touch layer is a layer for identifying touch input and may serve as a touch member. The touch layer may include a plurality of sensing areas and a plurality of sensing electrodes.

[0053] The polarizing layer POL may be disposed on the display panel PN. The polarizing layer POL may be used to reduce reflection of external light. The polarizing layer POL may be bonded to the display panel PN using a first bonding member AM1. The first bonding member AM1 may be disposed between the polarizing layer POL and the display panel PN. The first bonding member AM1 may be an optically transparent bonding member. In an embodiment, for example, the first bonding member AM1 may be an optically clear adhesive (OCA) or an optically clear resin, but is not limited thereto.

[0054] A cover window CW may be disposed on the polarization layer POL. The cover window CW may be disposed on top of the display panel PN to protect the display panel PN and may allow light emitted from the display panel PN to pass through the cover window CW. The cover window CW may include a rigid material such as glass or quartz. In some embodiments, the cover window CW may include plastic.

[0055] The cover window CW may overlap with the display panel PN and may cover the entire surface of the display panel PN. The cover window CW may have a shape substantially similar to that of the display panel PN, but may have a size larger than that of the display panel PN. In an embodiment, for example, the cover window CW may protrude outwardly beyond the display panel PN along two short sides of the display device 1. Figure 2 As shown in , the cover window CW may further protrude outwardly beyond the display panel PN along the two long sides of the display device 1, and the protrusion length along the short sides may be greater than the protrusion length along the long sides. The cover window CW may have a quadrilateral (e.g., rectangular) shape including two long sides and two short sides, and the shape of the cover window CW may be the same as that of the display device 1 in a plan view.

[0056] A printed pattern IL may be further disposed on one surface (or bottom surface) of the cover window CW facing the display panel PN. The printed pattern IL may be disposed in the non-display area NA of the display device 1. The area in which the printed pattern IL is disposed may be defined as the non-display area NA of the display device 1. The printed pattern IL may extend from one end of the cover window CW to partially overlap with the display panel PN.

[0057] The second bonding member AM2 may be disposed between the cover window CW and the polarizing layer POL. The second bonding member AM2 may bond the polarizing layer POL and the cover window CW together. The second bonding member AM2 may be an optically transparent bonding member. In an embodiment, for example, the second bonding member AM2 may be an optically transparent adhesive or an optically transparent resin, but is not limited thereto.

[0058] The printed pattern IL may include: a surface in contact with one surface of the cover window CW; another surface opposite to the one surface of the printed pattern IL (a surface facing the display panel PN); and a side surface. The side surface of the printed pattern IL may include an outer surface and an inner surface. The outer surface of the printed pattern IL may be aligned with the outer surface of the cover window CW, and the inner surface of the printed pattern IL may be aligned with the boundary between the non-display area NA and the display area DA.

[0059] The second bonding member AM2 may cover the other surface and the inner side surface of the printed pattern IL. The second bonding member AM2 may directly contact the other surface and the inner side surface of the printed pattern IL.

[0060] In an embodiment, the display device 1 can be manufactured by bonding the cover window CW and the lower member of the cover window CW (polarization layer POL, display panel PN, etc.), and then performing an autoclave process on the bonded cover window CW and the lower member. That is, in an embodiment, the second bonding member AM2 of the display device 1 can be provided through a mutual bonding process and an autoclave process. It is expected that the second bonding member AM2 has different material properties in the mutual bonding process and the autoclave process. A detailed description will be given later.

[0061] The lower cover panel CP can be arranged below the display panel PN. The lower cover panel CP can be attached to the rear surface of the display panel PN in the display area DA. The lower cover panel CP includes at least one functional layer. The functional layer can be a layer that performs a heat dissipation function, an electromagnetic shielding function, a grounding function, a buffering function, a rigidity enhancement function, a support function and / or a digitization function. The functional layer can be a sheet layer, a film layer, a thin layer, a coating, a panel or a plate, etc. A functional layer can be composed of a single layer, or can be composed of a stack or coating of multiple thin films. For example, the functional layer can be a supporting member, a heat dissipation layer, an electromagnetic shielding layer, an impact absorbing layer or a digitizer, etc.

[0062] Figure 3 yes Figure 2 An enlarged cross-sectional view of a flat portion and a portion of a first curved portion.

[0063] Reference Figure 2 and Figure 3 , as mentioned above Figure 2 As described above, the printed pattern IL may be arranged on one surface (bottom surface) of the cover window CW facing the display panel PN in the non-display area NA. That is, the printed pattern IL protruding from one surface of the cover window CW in the non-display area NA may generate a height difference. The second bonding member AM2 may cover the height difference generated by the printed pattern IL protruding from one surface of the cover window CW in the non-display area NA.

[0064] In an embodiment, for example, the second bonding member AM2 may include a first sub-bonding member AM21 having a first thickness t1 located in the display area DA and a second sub-bonding member AM22 having a second thickness t2 less than the first thickness t1 located in the non-display area NA. In an embodiment, for example, the first thickness t1 may be about 25 micrometers (μm) to about 250 μm, but is not limited thereto.

[0065] The second bonding member AM2 may have an adhesive strength equal to or greater than about 2000 grams-force per inch (gf / in) with respect to glass as an adherend.

[0066] As described above, it is desirable that the second bonding member AM2 has different material properties in the mutual bonding process and the autoclave process.

[0067] First, in the process of bonding the cover window CW and its lower members (polarization layer POL, display panel PN, etc.), it may be preferred that the second bonding member AM2 has low modulus, relatively high creep characteristics, and relatively low stress relaxation value.

[0068] Figure 9 is a schematic diagram illustrating an embodiment of joining a cover window and a lower member of the cover window. Figure 10 is a cross-sectional view illustrating an embodiment of a cover window and a lower member of the cover window being coupled together. Figure 11 yes Figure 10 An enlarged cross-sectional view of a flat portion and a portion of a first curved portion. Figure 12 yes Figure 11 An enlarged cross-sectional view of region A.

[0069] Reference Figure 2 and Figure 9 In the process of bonding the cover window CW to the lower member (polarization layer POL, display panel PN, etc.), the cover window CW may have a cross section corresponding to the cross section of the display device 1 having the flat portion MR and the curved portions SR1 and SR2, while the lower member may have a straight cross section extending along the first direction DR1. Figure 9 , the cover window CW is shown moving downward in the third direction DR3, but the present invention is not limited thereto, and the lower member may also move upward toward the fixed cover window CW, or the cover window CW and the lower member may also move downward and upward, respectively, to be joined together.

[0070] The cover window CW and the lower member may be as Figure 10 and Figure 11 During the bonding process, as shown in FIG. Figure 9The lower member having the straight-line-shaped cross section extending in the first direction DR1 may be deformed to have a cross section corresponding to the shape of the cover window CW having the flat portion MR and the curved portions SR1 and SR2 .

[0071] In the process of joining the cover window CW and the lower components of the cover window CW (polarization layer POL, display panel PN, etc.), when the second joining member AM2 has a low modulus, relatively high creep characteristics and a relatively low stress relaxation value, the height difference caused by the printed pattern IL can be effectively absorbed by the second joining member AM2, thereby bringing the advantage of performing initial bonding between the cover window CW and the lower components of the cover window CW through the second joining member AM2 located at the curved portions SR1 and SR2 of the display device 1.

[0072] In the process of joining the cover window CW and the lower components of the cover window CW (polarization layer POL, display panel PN, etc.), when the second joining member AM2 has a low modulus, relatively high creep characteristics and a relatively low stress relaxation value, this can reduce the formation of bubbles during the initial bonding between the cover window CW and the lower components of the cover window CW using the second joining member AM2 located at the curved portions SR1 and SR2 of the display device 1.

[0073] The process of bonding the cover window CW and the lower member of the cover window CW (polarization layer POL, display panel PN, etc.) can be performed at room temperature under atmospheric pressure. In an embodiment, for example, the room temperature may be about 25 degrees Celsius (°C), and the atmospheric pressure may be about 1 atmosphere (atm) or about 1 bar. Under the room temperature and atmospheric pressure conditions of the process for bonding the cover window CW and the lower member of the cover window CW (polarization layer POL, display panel PN, etc.), in the second bonding member AM2, the modulus may be about 150 kilopascals (kPa) to about 210 kPa, the creep characteristics may be about 20 percent (%) to about 30%, and the stress relaxation value may be equal to or less than about 5000 kPa.

[0074] Figure 15 Graph showing creep characteristics of each sample as a function of time. Figure 16 Graph showing stress relaxation of each sample according to time.

[0075] exist Figure 15 In FIG, the horizontal axis represents time in seconds (s), and the vertical axis represents creep characteristics in %. Figure 16 , the horizontal axis represents time in seconds (s), and the vertical axis represents stress in kPa.

[0076] First, refer to Figure 15, it was confirmed that there were no bubbles in the sample having a creep characteristic of 20% to 30% within a period of time from about 400 seconds to about 600 seconds under room temperature and atmospheric pressure conditions.

[0077] In addition, refer to Figure 16 It was confirmed that, under room temperature and atmospheric pressure conditions, there were no bubbles in the stress relaxation value sample indicated by the solid line, and that the stress in the sample was approximately 15,000 kPa in the initial stage and decreased to approximately 5,000 kPa or less after approximately 20 seconds. The stress relaxation value measurement was performed in a state where a deformation rate (shear stress) of approximately 25% was applied to the sample for approximately 600 seconds.

[0078] Reference Figure 12 , some bubbles AR may be provided in the second bonded member AM2. In order to remove the bubbles AR provided during the bonding process, an autoclave process may be performed as described below.

[0079] Figure 13 is a cross-sectional view showing an embodiment of the autoclave process. Figure 3 and Figure 13 , an autoclave process may be performed on the second bonding member AM2 after a process of bonding the cover window CW with lower members (polarization layer POL, display panel PN, etc.) of the cover window CW.

[0080] The autoclave process can be performed in a chamber CH maintained at a temperature higher than room temperature and a pressure higher than atmospheric pressure. In an embodiment, for example, the autoclave process can be performed at a temperature equal to or higher than about 60°C and a pressure equal to or higher than about 6 bar. Due to the nature of the equipment, the autoclave process under the above temperature and pressure conditions can also have a temperature condition equal to or lower than about 80°C and a pressure condition equal to or lower than about 8 bar. In an embodiment, for example, the autoclave process can be performed for about 10 minutes. However, the autoclave process can be performed under various temperature, pressure, and time conditions as necessary.

[0081] The autoclave process may reduce the number of bubbles provided at the bent portions SR1 and SR2 of the display device 1 during initial bonding of bonding the cover window CW and the lower member of the cover window CW using the second bonding member AM2 .

[0082] In an embodiment, for example, the number of bubbles can be reduced in such a way that the bubbles provided in the second bonding member AM2 are contracted using a temperature higher than room temperature and a pressure higher than atmospheric pressure to increase the number of molecules, which causes the bubbles themselves to dissolve into the second bonding member AM2. However, under the conditions of high temperature and high pressure of the autoclave process, penetration of external air through the end of the second bonding member AM2 may occur. In an embodiment, for example, at a temperature higher than room temperature and a pressure higher than atmospheric pressure, the modulus of the adhesive layer is reduced to soften the adhesive layer, which promotes the penetration of external air. External air that penetrates through the end of the second bonding member AM2 during the autoclave process may form bubbles at room temperature and at atmospheric pressure after completion of the autoclave process, making it possible to visually perceive bubbles at the end of the second bonding member AM2.

[0083] Therefore, it is preferable that the second bonding member AM2 has a property in which the modulus increases with an increase in temperature and / or pressure.

[0084] It may be preferred that the second joining member AM2 has relatively high modulus and low creep characteristics during the autoclave process. Figure 14 : is a cross-sectional view showing the prevention of external air from penetrating into the second bonding member. Figure 14 As shown in , when the second bonding member AM2 has a relatively high modulus and low creep characteristics during the autoclave process, this can prevent external air OA from penetrating through the end portion of the second bonding member AM2, resulting in a reduction in the number of infiltrated bubbles and the diffusion distance of the infiltrated bubbles. In the event that infiltrated bubbles are generated, although the infiltrated bubbles diffused into the non-display area NA may not be visually perceived due to the printed pattern IL, the infiltrated bubbles diffused into the display area DA may still be visually perceived by the user.

[0085] When the second bonding member AM2 has a relatively high modulus and low creep properties during the autoclave process, this can reduce the space through which bubbles can penetrate, and even if any bubbles penetrate, the growth and distribution of the infiltrated bubbles are limited. Generally, as the radius of curvature of the curved portion decreases, bubbles are easily provided in the process of bonding the cover window CW and the lower member, which makes it desirable to increase the temperature and pressure during the autoclave process to remove the bubbles. In an embodiment, the second bonding member AM2 has a low modulus and high creep properties during the bonding process (room temperature and atmospheric pressure), thereby reducing the formation of bubbles. In addition, even if the autoclave process is performed under higher temperature and pressure conditions, the modulus of the second bonding member AM2 can be increased, thereby significantly reducing the bubbles penetrating through the end of the second bonding member AM2. This makes it possible to further reduce the radius of curvature of the curved portion and the diffusion distance of the infiltrated bubbles, which can further reduce the frame area (e.g., the non-display area NA).

[0086] In order to meet the characteristic requirements of increasing the modulus and reducing the creep characteristic as the temperature and / or pressure increase, the second bonding member AM2 may include the first monomer of the following Chemical Formula 1:

[0087]

[0088] In the autoclave process, the second joining member AM2 may have a modulus of about 800 kPa to about 1000 kPa, and a creep characteristic equal to or less than about 10%.

[0089] In addition, because the second joining member AM2 includes the first monomer to meet the characteristic requirements of increasing modulus and reducing creep characteristics with increasing temperature and / or pressure, the second joining member AM2 is excellently cured after the autoclave process without any separate post-curing process, which leads to a reduction in processing time and simplification of equipment.

[0090] Since the second bonding member AM2 is excellently cured using only the autoclave process, it is possible to maintain the adhesive property of the second bonding member AM2 at the step portion caused by the printed pattern IL and the bent portions SR1 and SR2 .

[0091] In embodiments, a stress relaxation value of the second bonding member AM2 in the autoclave process may be smaller than a stress relaxation value in a process of bonding the cover window CW with a lower member (polarization layer POL, display panel PN, etc.) of the cover window CW.

[0092] Furthermore, to prevent external air from penetrating through the end of the second bonding member AM2 during the autoclave process, a method of preventing the penetration of bubbles may be considered: reducing internal pores by increasing the crosslinking degree and / or molecular weight of the second bonding member AM2.

[0093] After the autoclave process, the second bonding member AM2 can maintain relatively high modulus and low creep characteristics at room temperature and atmospheric pressure. As a result, the adhesive characteristics of the second bonding member AM2 can be maintained at the step portion caused by the printed pattern IL and the bent portions SR1 and SR2.

[0094] In an embodiment, for example, after the autoclave process, the second bonding member AM2 may maintain a modulus of about 600 kPa to about 750 kPa and a creep property of about 12% to about 15% at room temperature and atmospheric pressure conditions.

[0095] The second bonding member AM2 may have a degree of curing or a gel content (wt %) that varies according to the content of the first monomer.

[0096] Figure 4is a graph showing changes in peel stress and shear stress according to the content of the first monomer. Figure 5 is a graph showing changes in transition temperature according to the content of the first monomer.

[0097] Reference Figures 4 and 5 Table 1 showing the gel content according to the content of the first monomer (also referred to as "DMA content") is also referred to below.

[0098] [Table 1]

[0099] DMA content (wt%) Gel content (wt%) 0 54.55±1.070 1 55.08±1.700 2 57.25±0.592 3 58.33±0.940 4 60.88±1.590

[0100] First, referring to Table 1, it can be seen that the gel content (wt%) gradually increases as the content (wt%) of the first monomer increases. The gel content (wt%) has a correlation with the degree of cure of the second bonding member AM2, and as the gel content increases, the penetration of external air through the end of the second bonding member AM2 can be reduced.

[0101] Reference Figure 4 , it can be seen that as the content of the first monomer increases, the peel stress in Newtons per 25 millimeters (N / 25mm) decreases, and the shear stress (min value or minimum value) increases. Here, the unit of shear stress is Pascal (Pa). Since it is confirmed that the shear stress increases as the content of the first monomer increases, it can be proved that the gel content (wt%) increases as the content of the first monomer increases. Specifically, it has been confirmed that when the content of the first monomer is less than about 3wt%, the shear stress tends to increase slightly to about 400, but when the content of the first monomer is equal to or greater than about 3wt%, the shear stress increases significantly, and when the content of the first monomer is about 4wt%, the shear stress reaches about 1300.

[0102] In an embodiment, the first monomer may be present in an amount of about 3 wt % to about 4 wt %. As shown in Table 1, when the first monomer is present in an amount of about 3 wt % to about 4 wt %, the gel content may be about 57.43 wt % to about 62.47 wt %.

[0103] Reference Figure 5 , it can be seen that the transition temperature (Tg in degrees Celsius (°C)) varies depending on the content of the first monomer. Figure 5 In FIG, the horizontal axis may represent temperature in degrees Celsius (° C.), and the vertical axis may represent heat flow in milliwatts per milligram (mW / mg). Figure 5As shown in , it was confirmed that as the content of the first monomer increased, the transition temperature Tg of the second bonding member AM2 increased (-35.4° C. at 0%, -33.5° C. at 2%, and -30.6° C. at 4%).

[0104] Hereinafter, a method including measuring modulus and creep characteristics by an indenter is described.

[0105] Figure 6 is a schematic diagram illustrating an embodiment of a method for measuring the modulus and creep properties of an adhesive layer by a bioindenter.

[0106] Reference Figure 6 The bioindenter includes an indenter RBL. The indenter RBL may have a sphere (ruby sphere) shape or a shape of at least a portion of the sphere. The sphere of the indenter RBL may have a diameter D of approximately 0.5 millimeters (mm), but is not limited thereto.

[0107] In an embodiment, the adhesive layer PSA as a measurement target is cut into a size of 2 centimeters (cm) × 2 cm. In the case of attaching a foreign film to the adhesive layer PSA, after removing the foreign film, the adhesive layer PSA is attached to a flat holder HDR placed on the plate PLT. Next, the indenter RBL presses the surface of the adhesive layer PSA with a maximum load of 0.5 millinewtons (mN), and the pressing is maintained for about 60 seconds. Here, the loading / unloading speed (i.e., pressing speed) of the indenter RBL can be about 1.2 millinewtons per minute (mN / min). During the pressing operation, the indentation depth is measured. The indentation test using the indenter RBL of the bioindenter can be performed at multiple points (e.g., 15 points) on the sample, and the indentation depth can be represented by the average value of multiple test results.

[0108] Figure 7 is a graph showing the relationship between indentation depth and load. Figure 8 is a graph showing changes in indentation depth according to time before and after the maximum load holding period.

[0109] exist Figure 7 and Figure 8 In FIG. 5 , h1 represents the indentation depth at the time point when the maximum load is reached, and h2 is the indentation depth at the time point when the maximum load holding period ends.

[0110] Reference Figure 7 and Figure 8As the indentation load of the indenter RBL increases, the indentation depth of the indenter RBL increases. Because the deformation rate for stress increases as the modulus of the adhesive layer decreases, the indentation depth for the indentation load increases as the modulus decreases. Due to the viscosity of the adhesive layer PSA, the indentation depth continues to increase while maintaining the maximum load on the indenter RBL. During the maximum load holding period, the indentation depth generally tends to increase as the creep characteristics increase. The rate of increase in the indentation depth during the maximum load holding period gradually decreases over time ( Figure 8 The slope in the indentation depth decreases, and even if the holding period is extended, the indentation depth can be maintained at a specific value at a predetermined time point without further increase. When the indenter RBL is unloaded, the indentation depth decreases, and the stronger the restoring force, the faster the indentation depth decreases after the indenter RBL is completely unloaded.

[0111] After measuring the indentation depth as described above, the modulus E* can be calculated by the following equation Eq. 1.

[0112]

[0113] In Eq. 1, P represents the maximum load and R represents the shape of the ball of the indenter RBL (see Figure 6 ), which is the radius of Figure 6 The indentation depth is half of the diameter D shown in FIG, and h represents the indentation depth. Here, the indentation depth means that the maximum load reaches the depth h1. In the bioindenter with a predetermined offset depth (h offset ), the indentation depth of Eq. 1 can be expressed as the maximum load depth h1 measured by the bioindenter minus the offset depth (h offset ) The value obtained by offset depth (h offset ) is the deflection perceived when the surface of the adhesive layer is indented by the van der Waals force even when the indenter RBL approaches but does not press when the bioindenter measures the indentation depth. The deflection depth (h) can be calculated by subtracting the deflection depth (h) from the indentation depth measured by the bioindenter. offset ) to calculate the actual indentation depth. In order to reduce the offset depth (h offset ), the modulus can be calculated by setting the loading slope range in the indentation depth-load diagram to 30% to 98% of the maximum load (0.06 mN to 0.196 mN).

[0114] Creep properties (C IT ) can also be calculated by Eq.2.

[0115]

[0116] The modulus and creep characteristics of the second joining member AM2 of the display device 1 can be measured in the above-described manner.

[0117] Hereinafter, the embodiments will be described in more detail through manufacturing examples and experimental examples.

[0118] Table 2 below shows the adhesive material properties of each sample. Figure 2 and Figure 3 and Table 2 for description.

[0119] [Table 2]

[0120]

[0121] <Manufacturing Example 1: Manufacturing of Display Device>

[0122] Manufacturing with Figure 2 Multiple display device samples with layered structures shown in .

[0123] <Manufacturing Example 2: Extraction of Adhesive Sample>

[0124] Samples of the second bonding member AM2 were extracted by separating the cover window CW from each display device sample. The extracted adhesives #A to #E had different material properties. The modulus and creep properties of adhesives #A to #E were measured at room temperature (approximately 25°C), at an elevated temperature (60°C), and at room temperature after recovery from the elevated temperature.

[0125] <Experimental Example 1: Measurement of Modulus and Creep Properties>

[0126] Each adhesive sample was cut to have a size of 2 cm×2 cm, and the modulus and creep characteristics of each adhesive sample were measured using an indenter evaluation method. The indenter evaluation method was performed by applying and maintaining a maximum load of 0.5 mN to each sample within 60 seconds using a spherical indenter including a ruby ​​material. The loading / unloading speed was maintained at 1.2 mN / min. The indentation depth of each point indentation was measured, and the modulus and creep characteristics were measured using the value obtained by averaging the indentation depths of each point indentation. The results are shown in FIG. Figure 16 in the curve diagram.

[0127] <Experimental Example 2: Measurement of the Number of Permeated Bubbles>

[0128] For example Figure 2 The number of bubbles that penetrated into each of the samples #A to #E was measured by microscopy. The number of bubbles that penetrated into each of the samples #A to #E was measured by microscopy. Figure 2The number of bubbles at a point 100 mm away from the end of the second bonding member AM2 is shown in FIG. Figure 16 As a result, it was confirmed that, among samples #A to #E, the number of infiltrated bubbles was 0 in sample #E having a modulus of approximately 181±1.7 kPa and a creep property of approximately 28±0.2 at room temperature and atmospheric pressure; in sample #E having a modulus of approximately 944±132 kPa and a creep property of approximately 7±1.4 during the autoclave process; and in sample #E having a modulus of approximately 765±110 kPa and a creep property of approximately 12±1.5 at room temperature and atmospheric pressure after the autoclave process.

[0129] Figure 17 is a perspective view of another embodiment of a display device. Figure 18 yes Figure 17 sectional view of a display device.

[0130] Reference Figure 17 and Figure 18 According to another embodiment, the display device 2 and Figure 1 and Figure 2 The display device 1 of the embodiment is different in that it has only the flat portion MR and does not include Figure 1 and Figure 2 The curved portions SR1 and SR2.

[0131] In more detail, the display device 2 according to another embodiment may include only the flat portion MR without including Figure 1 and Figure 2 The curved portions SR1 and SR2.

[0132] Other configurations refer to the above Figures 1 to 16 The configurations described are the same, and therefore duplicate descriptions are omitted.

[0133] Figure 19 is a perspective view of another embodiment of a display device.

[0134] Reference Figure 19 According to the display device 3 of this embodiment, Figure 1 and Figure 2 The display device 1 of the embodiment is different in that it has four curved portions.

[0135] In more detail, the display device 3 according to the present embodiment may include four curved portions.

[0136] According to this embodiment, the curved portion may further include a third curved portion SR3 extending from a first short side of the flat portion MR (a short side disposed on one side of the flat portion MR in the second direction DR2) and a fourth curved portion SR4 extending from a second short side of the flat portion MR (a short side disposed on the other side of the flat portion MR in the second direction DR2).

[0137] Each of the curved portions SR3 and SR4 may be bent from the flat portion MR in the thickness direction (third direction DR3). Each of the curved portions SR3 and SR4 may be provided on a plane. Each of the curved portions SR3 and SR4 may be bent from the flat portion MR to have a curvature (or curvature angle), which may be an obtuse angle, but is not limited thereto, and may be a right angle.

[0138] In some embodiments, each of the curved portions SR3 and SR4 may not be disposed on a plane and may have a curved surface having a predetermined curvature. The predetermined curvature may be constant, but is not limited thereto, and the predetermined curvature may vary.

[0139] According to the present embodiment, double curved portions may be provided at positions where adjacent curved portions SR1 to SR4 intersect with each other (e.g., a position where the first curved portion SR1 and the third curved portion SR3 intersect, a position where the first curved portion SR1 and the fourth curved portion SR4 intersect, a position where the second curved portion SR2 and the third curved portion SR3 intersect, and a position where the second curved portion SR2 and the fourth curved portion SR4 intersect). Figure 2 AM2 in will cover the window (see Figure 2 CW in) and overlay window (see Figure 2 In the initial stage of the lower member bonding of the CW in the double curved portion, bubbles are formed. The second bonding member according to this embodiment may have the same Figures 1 to 16 Therefore, defects of the display device can be prevented in advance.

[0140] Although the embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

1. A display device, wherein: The display device includes: a flat portion defined by a first direction and a second direction intersecting the first direction; a curved portion provided on at least one side of the flat portion and curved in a third direction perpendicular to the first direction and the second direction; a display panel disposed above the flat portion and the curved portion; a cover window disposed on the display panel and disposed above the flat portion and the curved portion; and a bonding member disposed between the display panel and the cover window, wherein the joined member has a modulus that increases with increasing temperature, and the joined member has undergone an autoclave process, in which the modulus of the joined member is within a range from 800 kPa to 1000 kPa under conditions of a temperature range from 60 degrees Celsius to 80 degrees Celsius and a pressure range from 6 bar to 8 bar, and the joined member has a creep characteristic of 10% or less, wherein, after completion of the autoclave process, at room temperature and atmospheric pressure conditions, the modulus of the joined member is within a range from 600 kPa to 750 kPa and is maintained, and the creep property of the joined member is within a range from 12% to 15%, The bonding member includes a first monomer of the following chemical formula 1: and The mass ratio of the first monomer to the total mass of the bonding member is in a range of 3 wt % to 4 wt %.

2. The display device according to claim 1, wherein In the mutual joining process before the autoclave process, the modulus of the joined member is within a range from 150 kPa to 210 kPa under the room temperature and atmospheric pressure conditions.

3. The display device according to claim 1, wherein In the mutual joining process before the autoclave process, the creep property of the joined member is within a range from 20% to 30% under the room temperature and atmospheric pressure conditions.

4. The display device according to claim 1, wherein In the mutual joining process before the autoclave process, the joined members have a stress relaxation value equal to or less than 5000 kPa under the conditions of the room temperature and the atmospheric pressure.

5. The display device according to claim 1, wherein The bonding member has a bonding strength of 2000 grams force per inch or more with respect to glass as an adherend. The display device according to claim 1 , wherein: The display device further includes: a printed pattern disposed between the joining member and the cover window, wherein the printed pattern extends from an end portion of the cover window and partially overlaps with the display panel, The bonding member is in direct contact with one surface and a side surface of the printed pattern.

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