Patent Application
20220377921
This application claims priority to Korean Patent Application No. 10-2021-0066230 filed on May 24, 2021, and all the benefits accruing therefrom under 35 U.S.C. § 119, the entire contents of which are incorporated herein by reference.
The present disclosure relates to a cover window, a method for manufacturing (or providing) the cover window, and a display device including the cover window.
A display device such as an organic light emitting diode (OLED) display, a liquid crystal display (LCD), and the like includes a display panel that is manufactured by forming a plurality of layers and elements on a substrate. A flexible display panel and a flexible display device including the same have been developed.
The flexible display device may be classified into a bendable display device, a foldable display device, a rollable display device, a stretchable display device, and the like according to a use or form thereof. Among these, the foldable display devices can be folded and unfolded like a book.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.
A cover window is disposed on a top of a display panel. When an external impact is applied to the cover window, such as when an external object such as a pen falls on the cover window, the cover window may be destroyed or the impact from the external impact may propagate to the display panel, causing damage to the display panel. In particular, when sharpness of the tip of the pen increases for touch precision, the impact amount increases, and thus the risk of cracks in the cover window or datnage to the display panel may be increased.
Embodiments of the present disclosure provide a thin cover window of a display device while improving the impact characteristic of the cover window used in the display device.
An embodiment of a cover window includes a first film, an adhesive layer below the first film, and a second film below the adhesive layer. The second film includes a base substrate and a pattern layer which is on the base substrate and includes a plurality of protrusions. The pattern layer includes a plurality of protrusions that become narrower in a direction towards the first film, a modulus of the base substrate is about 500 megapascals (MPa) to about 1.5 gigapascals (GPa) when a modulus of the pattern layer is about 5 MPa to about 20 MPa, or the modulus of the base substrate is about 3.5 GPa or more when the modulus of the pattern layer is about 30 MPa to about 50 MPa.
The first film may include a protection film defining a top surface of the cover window.
The pattern layer may include at least one of an actyl-based, urethane-based, and silicone-based polymer resin.
The base substrate may include at least one of an amide-based, ester-based, ether-based, and carbonate-based polymer material.
The base substrate may include at least one of a terephthalate-based, imide-based, and aramid-based polymer material.
The protrusion may include a high point farthest from the base substrate and a low point closest to the base substrate, and the low point may contact a top surface of the base substrate.
The protrusion may include a high point farthest from the base substrate and a low point closest to the base substrate, and the low point may be distanced from a top surface of the base substrate rather than contacting the top surface of the base substrate.
The protrusion may include a high point farthest from the base substrate and a low point closest to the base substrate, and the high point is a flat surface at a boundary with the adhesive layer.
The cover window may further include a filling layer in a space defined between the plurality of protrusions, where the filling layer may include a same material as the adhesive laver.
The protrusion may be in a shape of a prism or microlens.
An embodiment of a display device includes a display panel and a cover window which is on the display panel. The cover window includes a first film, an adhesive layer below the first film, and a second film below the adhesive layer. The second film includes a base substrate, and a pattern layer which is on the base substrate and includes a plurality of protrusions. The pattern layer includes a plurality of protrusions that become narrower in a direction away from the display panel.
The first film may include a protection film defining a top surface of the cover window.
The protrusion may include a high point farthest from the base substrate and a low point closest to the base substrate, and the low point may contact a top surface of the base substrate.
The protrusion may include a high point farthest from the base substrate and a low point closest to the base substrate, and the low point may be distanced from a top surface of the base substrate rather than contacting the top surface of the base substrate.
The protrusion may include a high point farthest from the base substrate and a low point closest to the base substrate, and the high point may define a fiat surface at a boundary with the adhesive layer.
The display device may further include a filling layer in a space between the plurality of protrusions, where the filling layer may include a same material as the adhesive layer.
A modulus of the base substrate may be about 500 MPa to about 1.5 GPa when a modulus of the pattern layer may be about 5 MPa to about 20 MPa.
The base substrate may include at least one of an amide-based, ester-based, ether-based, and carbonate-based polymer material, and the pattern layer may include at least one of acryl-based, urethane-based, and silicone-based polymer resin.
The base substrate may include at least one of a terephthalate-based, imide-based, and aramid-based polymer material, and the pattern layer may include at least one of an acryl-based, urethane-based, and silicone-based polymer resin.
A method of providing a cover window includes providing a coating layer by providing a polymer resin to a base substrate of the cover window, the base substrate having a modulus, providing a pattern layer of the cover window including a plurality of protrusions arranged along the base substrate, by patterning the coating layer, the pattern layer including each protrusion among the plurality of protrusions having a modulus and a width, and the widths of the protrusions decreasing in a direction away from the base substrate, providing an adhesive layer facing the base substrate with the plurality of protrusions of the pattern layer therebetween and providing a protection film of the cover window which faces the plurality of protrusions of the pattern layer with the adhesive layer therebetween. Within the cover window the modulus of the base substrate is about 500 MPa to about 1.5 GPa when the modulus of the pattern layer is about 5 MPa to about 20 MPa, or the modulus of the base substrate is about 3.5 GPa or more when modulus of the pattern layer is about 30 MPa to about 50 MPa.
According to one or more embodiment, a small thickness of a cover window of a display device may be maintained while improving the impact characteristic of the cover window used in the display device.
The above and other advantages and features of this disclosure will become more apparent by describing in further detail embodiments thereof with reference to the accompanying drawings, in which:
The invention will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways.
The drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification. As used herein, a reference number may indicate a singular element or a plurality of the element. For example, a reference number labeling a singular form of an element within the drawing figures may be used to reference a plurality of the singular element within the text of specifi cation
In addition, since the size and thickness of each configuration shown in the drawings are arbitrarily indicated for better understanding and ease of description, the invention is not necessarily limited to the drawings. In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. In addition, in the drawings, the thickness of some layers and regions is exaggerated for better understanding and ease of description.
It will be understood that when an element such as a layer, film, region, or substrate is referred to as being related to another element such as being “on” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being related to another element such as being “directly on” another element, there are no intervening elements present. Further, throughout the specification, the word “on” a target element will be understood to mean positioned above or below the target element, and will not necessarily be understood to mean positioned “at an upper side” based on an opposite to gravity direction.
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 sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, “a first element,” “component,” “region,” “layer” or “section” discussed below could be termed a second element, component, region, layer or section without departing from the teachings herein.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, “a”, “an,” “the,” and “at least one” do not denote a limitation of quantity, and are intended to include both the singular and plural, unless the context clearly indicates otherwise. For example, “an element” has the same meaning as “at least one element,” unless the context clearly indicates otherwise. “At least one” is not to be construed as limiting “a” or “an.” “Or” means “and/or,” As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. In addition, unless explicitly described to the contrary, the word “comprise”, and variations such as “comprises” or “comprising”, will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.
Furthermore, relative terms, such as “lower” or “bottom” and “upper” or “top,” may be used herein to describe one element's relationship to another element as illustrated in the Figures. It will be understood that 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 term “lower,” can therefore, encompasses 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 terms “below” or “beneath” can, therefore, encompass both an orientation of above and below.
“About” or “approximately” as used herein 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, considering the measurement in question and the error associated with measurement of the particular quantity (i.e., the 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.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is 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 unless expressly so defined herein.
Embodiments are described herein with reference to cross section 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 should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as flat may, typically, have rough and/or nonlinear features. Moreover, sharp angles that are illustrated may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the present claims.
Further, throughout the specification, the phrase “on a plane” means viewing a target portion from the top, and the phrase “on a cross-section” means viewing a cross-section formed by vertically cutting a target portion from the side.
In addition, when “connected to” in the entire specification, this does not only mean that two or more constituent elements are directly connected, but also means that two or more constituent elements are indirectly connected, physically connected, and electrically connected through other constituent elements, or being referred to by different names depending on the position or function, while being integral.
Hereinafter, an embodiment of a cover window 100 and a display device which includes the cover window 100 will be described with the accompanying drawings.
Referring to
Referring to
Referring to
Referring to
Among surfaces of the display panel 200, a surface on which the cover window 100 is disposed may be a display surface at which the image is displayed. The arrow direction shown in
The display device and various components and layers thereof may be disposed in a plane defined by a second direction and a third direction crossing each other and crossing the first direction DR1. A thickness direction of the display device and various components and layers thereof may be taken along the first direction DR1.
Referring to
The cover window 100 including the plurality of films and the at least one adhesive layer may have optical clearance (e.g., may be light transmissive, optically clear, etc.).
The plurality of films may include a first film 110 which is a protective film disposed at the topmost of the display device, a second film 130 which is a pattern film disposed below the first film 110 for improving an impact resistance characteristic, and a third film 150 disposed below the second film 130. The first film 110, the second film 130 and the third film 150 may be in order toward the display panel 200.
A first adhesive layer 120 disposed between the first film 110 and the second film 130, a second adhesive layer 140 disposed between the second film 130 and the third film 150, and a third adhesive layer 160 disposed below the third film 150, respectively adhere two neighboring films or layers to each other.
The adhesive layers 120, 140, and 160 may include a pressure sensitive adhesive (PAS). The adhesive layers 120, 140, and 160 may include, for example, a polymer resin such as an acryl-based material, a silicon-based material, rubber, polyurethane, vinyl acetate, an epoxy resin, and styrene-butadiene-styrene (SBS). The second adhesive layer 140 may include an optically clear resin (OCA).
The first film 110 may include at least one of polyethylene terephthalate (PET), poly(butylene terephthalate) (PBT), polycarbonate (PC), polyethylene naphthalate (PEN), polystyrene (PS), poly methylinethacrylate (PMMA), polyvinylchloride (PVC), polyethersulfone (PES), polypropylene (PP), polyamide (PA), modified polyphenylene ether (m-PPO), polyoxymethylene (POM), polysulfone (PSU), polyphenylene sulfide (PPS), polyimide (PI), polyethyleneimine (PEI), polyether ether ketone (PEEK), polyamide imide (PAI), polyarylate (PAR), thermoplastic polyurethane (TPU), and the like.
Like the first film 110, the third film 150 or another one of the first film 110 disposed below the third film 150 may include at least one of various resins. That is, a stacked structure may include each of the first film 110, the second film 130 and the third film 150, and the cover window 100 may include a plurality of the stacked structures, without being limited thereto.
In an embodiment of the cover window 100, the third film 150 and additional films which are below the third film 150 may be omitted.
The second film 130 is a film for impact resistance improvement.
Referring to
According to the physical shape of the base substrate 131 and the pattern layer 132, the base substrate 131 has a substantially flat top surface, and the pattern layer 132 may have a plurality of protrusions 32 (also called protruding portions) that become narrower in the first direction DR1, which is the direction away from the display panel 200.
The protrusion 32 may have various shapes such as, for example, a prism shape and a microlens shape, A width of the protrusion 32 may be taken in a direction along the base substrate 131. A width of the protrusion 32 may decrease in a direction away from the display panel 200.
The protrusion 32 may include a high point HP farthest from the base substrate 131 and a low point LP closest to the base substrate 131. When the protrusion 32 is in the form of a prism, the high point HP may be in the form of a vertex.
As shown in
Referring to
In addition, the impact transmitted from the top is delayed within the second film 130 including the base substrate 131 and the pattern layer 132 having different materials from each other, and thus the impact can be mitigated from being transmitted to other places.
A pitch PT and a height Hf of the protrusion 32 of the pattern layer 132 may be properly set to reduce or effectively prevent damage to the second film 130 due to a stress applied therein and reduce or effectively prevent deterioration of flexural performance when the display device is being folded to define a curvature radius thereof. In an embodiment, for example, when a curvature radius of the display device is about 1 millimeter when the display device is folded, the pitch PT of a plurality of protrusions 32 may be about 20 micrometers to about 50 micrometers, and the height HT of the protrusions 32 may be about 10 micrometers to about 25 micrometers. The height HT may be taken along the first direction DR1, from the high point HP to a reference plane such as the top surface of the base substrate 131.
The thickness of the base substrate 131 (e.g., along the first direction DR1) may be, for example, about 20 micrometers to about 60 micrometers, but is not limited thereto.
As physical properties of the base substrate 131 and the pattern layer 132, the physical properties of the base substrate 131 and the pattern layer 132, particularly the modulus, improve the impact characteristic that absorbs and disperses impact from the outside.
Specifically, the modulus of the base substrate 131 may be about 500 megapascals (MPa) to about 1.5 gigapascals (GPa), and, in this case, the modulus of the pattern layer 132 may be about 5 MPa to about 20 MPa.
When the modulus of the base substrate 131 is about 3.5 GPa or more, the modulus of the pattern layer 132 may be about 30 MPa to about 50 MPa.
In order to improve the impact resistance characteristic and reduce or effectively prevent damage to the second film 130, when the modulus of the base substrate 131 increases, the modulus of the pattern layer 132 may also increase.
The modulus of the pattern layer 132 may be less than 100 MPa. When the modulus of the pattern layer 132 is 100 MPa or more, the impact may propagate toward the base substrate 131 and the display panel 200 regardless of the modulus of the base substrate 131.
The base substrate 131 and the pattern layer 132 include different materials for the above-mentioned modulus characteristic, and may each include a variety of materials.
In an embodiment, for example, the base substrate 131 having a modulus between about 500 MPa to about 1.5 GPa may include at least one of an amide-based, ester-based, ether-based, and carbonate-based polymer material. That is, the base substrate 131 may include a polymer material including amide, ester, ether or carbon. In an embodiment, for example, the base substrate 131 having a modulus of about 3.5 GPa or more may include at least one of a terephthalate-based, imide-based, and aramid-based polymer material. That is, the base substrate 131 may include a polymer material including terephthalate, imide, or aramid.
The pattern layer 132 may include, for example, at least one of an acryl-based, urethane-based, and silicone-based polymer resin. That is, the pattern layer 132 may include a polymer resin including acryl, urethane or silicone.
A difference in refractive index between the base substrate 131 and the pattern layer 132 may be less than 0.04. In an embodiment, for example, the refractive index of the base substrate 131 may be about 1.49, and the refractive index of the pattern layer 132 may be about 1.495, but is not limited thereto. By reducing the refractive index difference between the base substrate 131 and the pattern layer 132, it is possible to reduce or effectively prevent visual recognition of the protrusion 32 of the pattern layer 132 from outside the cover window 100 and/or the display device.
The impact resistance characteristic of embodiments of the cover window 100 that includes the second film 130 will be described with reference to
Referring to
The table of
Referring to
The graph of
In the graph of
As such, according to one or more embodiment, the impact characteristic of a cover window 100 can be improved while maintaining a minimal thickness of the second film 130 without having to increase a thickness of the second film 130 to improve the impact characteristic of the cover window 100, and accordingly, the flexibility of the cover window 100 can be improved.
An embodiment of a method of manufacturing (or providing) the second film 130 will be described with reference to
Referring to the above-described
Referring to
As previously described, after providing a second film 130, a first adhesive layer 120 in the form of a film is disposed on a pattern layer 132 of the second film 130, and pressure is applied to the stacked structure including the first adhesive layer 120 and the second film 130. Under force of the pressure, a protrusion 32 of the pattern layer 132 may maintain the shape as shown in
Referring to
Referring to
Referring to
Each protrusion 32a may contain a high point HP farthest from a base substrate 131 and a low point LP closest to the base substrate 131. Since the protrusion 32a is in the form of a microlens, the high point HP may be rounded rather than sharp.
As shown in
Referring to
In addition, the impact transmitted from the top of the cover window 100 and/or the display device including the same is delayed within the second film 130a formed of the base substrate 131 and the pattern layer 132a having different materials from each other, such that that transmission of the impact to other places within the cover window 100 and/or the display device including the same can be mitigated.
Within the display device which is folded, the pitch PT and height HT of the protrusion 32a of the pattern layer 132a can he appropriately set to reduce or effectively prevent damage to the second film 130a by the stress and not to deteriorate the flexibility of the cover window 100 and/or the display device including the same. In an embodiment, for example, in the display device which is folded and has the curvature radius of about 1 millimeter, the pitch PT of the plurality of protrusions 32a may be about 20 micrometers to about 50 micrometers, and the height HT of the protrusions 32a may be about 10 micrometers to about 25 micrometers.
After the providing of a second film 130a through one or more embodiment of a method of providing the second film 130 described above, a first adhesive layer 120 in the form of a film is disposed on a pattern layer 132a of the second film 130a. As shown in
Further, referring to
While this invention has been described in connection with what is presently considered to be practical embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2021-0066230 | May 2021 | KR | national |
