Display device, method of manufacturing display device, and electronic device

Abstract

A display device, a method of manufacturing the same, and an electronic device are disclosed. The display device includes a display panel configured to display an image and including a folding area configured to be folded about a folding axis and a non-folding area adjacent to the folding area; and a window on the display panel and configured to be folded along the display panel, in which the window includes a plurality of layers sequentially stacked in a stacking direction, and the plurality of layers of the window all extend across all of the non-folding area and the folding area, and a side surface of at least one layer among the plurality of layers is located at a first height range from the reference surface in the non-folding region and at a second height range from the reference surface in the folding region, the second height range being smaller than the first height range.

Description

[0001] This application is a divisional application of an invention patent application with an application date of April 9, 2020, application number 202010272192.7, and invention name “Display device and method for manufacturing display device”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0044318, filed on Apr. 16, 2019, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0004] Embodiments of the present disclosure relate to display devices (such as foldable display devices) and methods of manufacturing display devices. Background Art

[0005] Electronic devices such as smart phones, tablet computers, notebook computers, and smart TVs have been developed. Such electronic devices include a display device for providing information, and include various electronic modules other than the display device.

[0006] Recently, a display device including a flexible display member and configured to be foldable or rollable is being developed. Compared with a flat display device, a flexible display device can be folded, rolled, or bent like paper. A flexible display device that can be converted into various shapes is easy to carry and improves user convenience. Summary of the invention

[0007] Embodiments of the present disclosure provide a foldable display device with improved reliability. Embodiments of the present disclosure also provide a method of manufacturing the foldable display device.

[0008] An embodiment of the inventive concept provides a display device, comprising: a display panel, the display panel is configured to display an image and includes a folding area configured to be folded around a folding axis and a non-folding area adjacent to the folding area; and a window, the window is located on the display panel and configured to be folded along the display panel, wherein the window includes a plurality of layers stacked sequentially in a stacking direction, and the plurality of layers of the window all extend across all the non-folding areas and the folding areas, and a side surface of at least one layer among the plurality of layers is located at a first height range from a reference surface in the non-folding area, and is located at a second height range from the reference surface in the folding area, and the second height range is smaller than the first height range.

[0009] A side surface of at least one layer among the plurality of layers may have a surface roughness higher in a non-folding region than in a folding region.

[0010] The plurality of layers of the window may include: a base layer; a window function layer located on the base layer; and a window protection layer covering the window function layer, and wherein the base layer, the window function layer and the window protection layer are sequentially stacked.

[0011] The respective side surfaces of the plurality of layers may include a side surface of the base layer, a side surface of the window function layer, and a side surface of the window protection layer.

[0012] The display device may further include: a functional layer located between the display panel and the window.

[0013] The side surface of the functional layer may have a surface roughness higher in the non-folding region than in the folding region.

[0014] The display device may further include: a protective film located on the rear surface of the display panel. The display panel is a flexible display panel.

[0015] An embodiment of the inventive concept provides a method for manufacturing a display device, the display device comprising: a display panel, the display panel being configured to display an image and comprising a folding area configured to be folded around a folding axis and a non-folding area adjacent to the folding area; and a window, the window being located on the display panel and configured to be folded along the display panel, the method comprising: preparing a preliminary display module comprising an effective area and an invalid area distinguished from each other relative to a cutting line; forming a first side surface portion of the window in the non-folding area, the first side surface portion having a first surface roughness; and forming a second side surface portion of the window in the folding area, the second side surface portion having a second surface roughness smaller than the first surface roughness, wherein the window comprises a plurality of layers stacked sequentially in a stacking direction, and the plurality of layers of the window all extend across all the non-folding areas and the folding areas.

[0016] Forming a first side surface portion of the window may include: performing a first laser treatment along a first cutting line located in the non-folding area to separate a first portion of the invalid area from the effective area; and forming a second side surface portion of the window may include: performing a second laser treatment along a second cutting line located in the folding area to separate a second portion of the invalid area from the effective area.

[0017] The performing of the second laser process may include irradiating a second laser beam having lower energy than that of a first laser beam used in the first laser process.

[0018] Performing the first laser process may include repeatedly irradiating the first laser beam N times, wherein performing the second laser process may include repeatedly irradiating the second laser beam M times, M having a value in a range of 3N to 3.5N.

[0019] Performing the first laser process may include irradiating a first laser beam at a first speed, and wherein performing the second laser process may include irradiating a second laser beam at a second speed faster than the first speed.

[0020] Performing the first laser process may include irradiating a first laser beam on the rear surface of the preliminary display module along the first cutting line, and wherein performing the second laser process may include irradiating a second laser beam on the rear surface of the preliminary display module along the second cutting line.

[0021] An embodiment of the inventive concept provides an electronic device, comprising: a display panel, the display panel being configured to display an image and comprising a folding area configured to be folded around a folding axis and a non-folding area adjacent to the folding area; and a window, the window being located on the display panel and being configured to be folded along the display panel, wherein the window comprises a plurality of layers stacked sequentially in a stacking direction, and the plurality of layers of the window all extend across all the non-folding areas and the folding areas, and a side surface of at least one layer among the plurality of layers is located at a first height range from a reference surface in the non-folding area, and is located at a second height range from the reference surface in the folding area, the second height range being smaller than the first height range.

[0022] An embodiment of the inventive concept provides a display device comprising a display panel and a window, wherein the display panel is used to display an image and comprises a folding area configured to be folded around a folding axis and a non-folding area adjacent to the folding area, and the window is located on the display panel, comprises a flexible material, and is configured to be folded along the display panel, wherein a first side surface portion of the window arranged in the non-folding area has a first surface roughness, and a second side surface portion of the window arranged in the folding area has a second surface roughness smaller than the first surface roughness.

[0023] The window may include a plurality of layers sequentially stacked in a stacking direction, wherein a side surface of each of the plurality of layers has a surface roughness higher in a non-folding region than in a folding region.

[0024] The side surface of at least one layer among the multiple layers may be located at a first height range from a reference surface substantially parallel to the stacking direction in the non-folding area, and may be located at a second height range from the reference surface in the folding area, the second height range being smaller than the first height range.

[0025] The window may include a base layer, a window function layer on the base layer, and a window protection layer covering the window function layer, wherein the base layer, the window function layer, and the window protection layer are sequentially stacked.

[0026] Each of the first and second side surface portions of the window may include a side surface of the base layer, a side surface of the window function layer, and a side surface of the window protection layer.

[0027] The display device may further include a functional layer between the display panel and the window.

[0028] A first side surface of the functional layer disposed in the non-folding region may have a third surface roughness, and a second side surface of the functional layer disposed in the folding region may have a fourth surface roughness smaller than the third surface roughness.

[0029] The display device may further include a protective film on a rear surface of the display panel.

[0030] The display panel may be a flexible display panel.

[0031] An embodiment of the inventive concept provides a method for manufacturing a display device, wherein the display device includes a display panel and a window, wherein the display panel is used to display an image and includes a folding area configured to be folded around a folding axis and a non-folding area adjacent to the folding area, the window is located on the display panel, includes a flexible material, and is configured to be folded along the display panel, the method including: preparing a preliminary display module including an effective area and an ineffective area distinguished from each other relative to a cutting line; performing a first laser treatment along a first cutting line located in the non-folding area of ​​the cutting line to separate a first portion of the ineffective area from the effective area; and performing a second laser treatment along a second cutting line located in the folding area of ​​the cutting line to separate a second portion of the ineffective area from the effective area.

[0032] The performing of the second laser process may include irradiating a second laser beam having lower energy than that of a first laser beam used in the first laser process.

[0033] Performing the first laser process may include repeatedly irradiating the first laser beam N times, and performing the second laser process may include repeatedly irradiating the second laser beam M times, M having a value in a range of about 3N to about 3.5N.

[0034] Performing the first laser process may include irradiating the first laser beam at a first speed, and performing the second laser process may include irradiating the second laser beam at a second speed faster than the first speed.

[0035] Performing the first laser process may include irradiating a first laser beam on the rear surface of the preliminary display module along the first cutting line, and performing the second laser process may include irradiating a second laser beam on the rear surface of the preliminary display module along the second cutting line.

[0036] A first side surface portion of the window disposed in the non-folding region may have a first surface roughness, and a second side surface portion of the window disposed in the folding region may have a second surface roughness smaller than the first surface roughness.

[0037] The window may include a plurality of layers sequentially stacked in a stacking direction, wherein a side surface of each of the plurality of layers has a surface roughness higher in a non-folding region than in a folding region.

[0038] The side surface of at least one layer among the multiple layers may be located at a first height range from a reference surface substantially parallel to the stacking direction in the non-folding area, and may be located at a second height range from the reference surface in the folding area, the second height range being smaller than the first height range.

[0039] The window may include a base layer, a window functional layer located on the base layer, and a window protective layer covering the window functional layer.

[0040] Each of the first and second side surface portions of the window may include a side surface of the base layer, a side surface of the window function layer, and a side surface of the window protection layer.

[0041] The display device may further include a functional layer located between the display panel and the window, a first side surface of the functional layer arranged in the non-folding area may have a third surface roughness, and a second side surface of the functional layer arranged in the folding area may have a fourth surface roughness smaller than the third surface roughness.

[0042] In summary, in contrast to the laser processing for the cutting lines located in the non-folding area, the laser processing for the cutting lines located in the folding area may be performed using a low-energy laser beam during the laser processing of cutting the preliminary display module.

[0043] Therefore, stress applied to the side surface of the folding area and damage that may be caused to the side surface of the folding area during the cutting process can be reduced or eliminated. As a result, defects in the folding area can be reduced, and the product reliability of the foldable display device can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The above and other aspects of the present disclosure will become apparent by reference to the following detailed description when considered in conjunction with the accompanying drawings, in which:

[0045] Figure 1 is a perspective view showing a display device according to one embodiment of the present disclosure;

[0046] Figure 2A It is shown Figure 1 A perspective view of a state in which the display device shown in FIG. 1 is folded inwardly (folded inwardly) around a first folding axis;

[0047] Figure 2B It is shown Figure 1 A perspective view of a state in which the display device shown in FIG. 1 is folded outward (folded outward) around a first folding axis;

[0048] Figure 3AIt is shown Figure 1 A perspective view of a state in which the display device shown in FIG. 1 is folded inwardly (folded inwardly) around a second folding axis;

[0049] Figure 3B It is shown Figure 1 A perspective view of a state in which the display device shown in FIG. 1 is folded outward (folded outward) around a second folding axis;

[0050] Figure 4 is an exploded perspective view showing a display module according to one embodiment of the present disclosure;

[0051] Figure 5 It is shown Figure 4 A plan view of the display module shown in ;

[0052] Fig. 6A is along Figure 5 The line II' shown in FIG. 1 is taken to show a cross-sectional view of the unfolded area;

[0053] Figure 6B is along Figure 5 The line II-II' shown in FIG. 1 is taken to show a cross-sectional view of the folding area;

[0054] Fig. 7A It is through shooting Fig. 6A A scanning electron microscope (SEM) image obtained from a side surface of a window located in a non-folded area;

[0055] Figure 7B It is through shooting Figure 6B SEM image obtained from the side surface of the window located in the folding area;

[0056] Fig. 8A is a graph showing a change in height of each layer of the window in the non-folding region relative to a reference surface;

[0057] Figure 8B is a graph showing the variation of the height of each layer of the window in the folding region relative to a reference surface;

[0058] Fig. 9A It is through shooting Fig. 6A The SEM image obtained by the side surface of the functional layer located in the non-folding area shown in FIG.

[0059] Fig. 9B It is through shooting Figure 6B An SEM image obtained by looking at the side surface of the functional layer located in the folding area shown in FIG.

[0060] Fig.10 is along Figure 5 A cross-sectional view taken along line III-III' shown;

[0061] Fig.11 is an exploded perspective view showing a display device according to one embodiment of the present disclosure;

[0062] Fig.12 is along Fig.11 A cross-sectional view taken along line IV-IV' shown in FIG.

[0063] FIG. 13A to FIG. 13C is a plan view showing a method of manufacturing a display panel according to an embodiment of the present disclosure;

[0064] Fig.14A and Fig. 14B is a process diagram showing a first laser process; and

[0065] Fig.15A and Fig. 15B 2 is a process diagram showing the second laser processing. DETAILED DESCRIPTION

[0066] By referring to the detailed description and the accompanying drawings of the embodiments, the features of the inventive concept and the methods for realizing it can be more easily understood. Hereinafter, the embodiments will be described in more detail with reference to the accompanying drawings. However, the described embodiments can be implemented in various forms and should not be interpreted as being limited only to the embodiments shown in this article. On the contrary, these embodiments are provided as examples so that this disclosure will be thorough and complete, and the aspects and features of the inventive concept will be fully conveyed to those skilled in the art. Accordingly, processes, elements and techniques that are not necessary for a person of ordinary skill in the art to fully understand the aspects and features of the inventive concept may not be described.

[0067] Unless otherwise specified, the same reference numerals indicate the same elements throughout the drawings and written description, and therefore their description will not be repeated. In addition, in order to make the description clear, parts that are not related to the description of the embodiment may not be shown. In the accompanying drawings, the relative sizes of elements, layers and regions may be exaggerated for clarity.

[0068] Various embodiments are described herein with reference to cross-sectional views that are schematic illustrations of embodiments and / or intermediate structures. Thus, variations in the shapes of the illustrations resulting from, for example, manufacturing techniques and / or tolerances are contemplated. In addition, for the purpose of describing embodiments according to the concepts of the present disclosure, the specific structural or functional descriptions disclosed herein are merely illustrative. Therefore, the embodiments disclosed herein should not be construed as being limited to the specific illustrated regional shapes, but rather include deviations in shape resulting from, for example, manufacturing.

[0069] For example, an implanted region shown as a rectangle will typically have rounded or curved features and / or an implant concentration gradient at its edges, rather than a binary change from an implanted region to a non-implanted region. Similarly, a buried region formed by implantation may generate some implantation in the region between the buried region and the surface for implantation. Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to illustrate the actual shape of the region of the device and are not intended to be limiting. Additionally, it will be appreciated by those of ordinary skill in the art that the described embodiments may be modified in a variety of different ways without departing from the spirit and scope of the present disclosure.

[0070] In the detailed description, for the purpose of explanation, numerous specific details are set forth to provide a thorough understanding of the various embodiments. However, it is apparent that the various embodiments may be practiced without these specific details or with one or more equivalent arrangements. In other examples, well-known structures and devices are shown in block diagram form to avoid unnecessary confusion of the various embodiments.

[0071] It should 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 used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, the first element, component, region, layer or part discussed below may be referred to as a second element, component, region, layer or part without departing from the spirit and scope of the present disclosure.

[0072] Spatially relative terms such as "beneath", "below", "lower", "under", "above", "upper", etc. may be used herein for convenience of explanation to describe the relationship of one element or feature to another element or feature as shown in the figures. It should be understood that in addition to the orientation shown in the drawings, spatially relative terms are intended to also include different orientations of the device in use or operation. For example, if the device in the figure is turned over, the elements described as being "below" or "beneath" or "under" other elements or features will subsequently be oriented to be "above" other elements or features. Therefore, the exemplary term "below" may include both the orientations of above and below. The device can be oriented in other ways (e.g., rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein should be interpreted accordingly. Similarly, when the first portion is described as being disposed “on” the second portion, this indicates that the first portion is disposed at the upper side or lower side of the second portion, without being limited to the upper side thereof based on the gravity direction.

[0073] It should be understood that when an element, layer, region or component is referred to as being "on", "connected to" or "coupled to" another element, layer, region or component, the element, layer, region or component may be directly on, directly connected to or coupled to another element, layer, region or component, or one or more intermediate elements, layers, regions or components may be present. However, "direct connection / direct coupling" refers to a component that is directly connected or coupled to another component without intermediate components. At the same time, other expressions describing the relationship between components such as "between", "immediately adjacent" or "adjacent" and "directly adjacent" may be similarly interpreted. In addition, it should also be understood that when an element or layer is referred to as being "between" two elements or layers, the element or layer may be the only element or layer between the two elements or layers, or one or more intermediate elements or layers may also be present.

[0074] For the purposes of this disclosure, expressions such as "at least one" following a list of elements modify the entire list of elements rather than the individual elements in the list. For example, "at least one of X, Y, and Z" and "at least one selected from the cluster consisting of X, Y, and Z" may be interpreted as any combination of only X, only Y, only Z, or two or more of X, Y, and Z, such as XYZ, XYY, YZ, and ZZ. Throughout the specification, similar reference numerals indicate similar elements. As used herein, the term "and / or" includes any and all combinations of one or more of the relevant listed items.

[0075] In an example, the first direction, the second direction and / or the third direction are not limited to the three axes of the rectangular coordinate system and can be interpreted in a broad sense. For example, the first direction, the second direction and the third direction can be perpendicular to each other, or can represent different directions that are not perpendicular to each other.

[0076] The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the present disclosure. Unless otherwise clearly indicated in the context, the singular forms "a" and "an" as used herein are also intended to include plural forms. It should also be understood that when the terms "comprise", "comprising", "have", "having", "include" and "including" are used in this specification, the existence of the stated features, integers, steps, operations, elements and / or parts is indicated, but the existence or addition of one or more other features, integers, steps, operations, elements, parts and / or their clusters is not excluded. As used herein, the term "and / or" includes any and all combinations of one or more of the relevant listed items.

[0077] As used herein, the words "substantially," "about," "approximately," and similar words are used as words of approximation rather than words of degree, and are intended to take into account the inherent deviations in measured or calculated values ​​that one of ordinary skill in the art will recognize. Taking into account the errors associated with the measurements and the measurement of a particular quantity (i.e., the limitations of the measurement system), "about" or "approximately" as used herein include the values ​​and means within the acceptable deviation range of the particular value determined by one of ordinary skill in the art. For example, "about" may mean within one or more standard deviations, or within ±30%, 20%, 10%, 5% of the stated value. In addition, when describing embodiments of the present disclosure, the use of "may" refers to "one or more embodiments of the present disclosure."

[0078] When a specific embodiment can be implemented in different ways, the specific process order can be performed differently from the described order. For example, two processes described in succession can be performed substantially simultaneously or in the reverse order of the described order.

[0079] In addition, any numerical range disclosed and / or listed herein is intended to include all sub-ranges of the same numerical precision included in the listed range. For example, the range of "1.0 to 10.0" is intended to include all sub-ranges between the minimum value of 1.0 listed and the maximum value of 10.0 listed (and including the minimum value of 1.0 listed and the maximum value of 10.0 listed), that is, all sub-ranges with a minimum value greater than or equal to 1.0 and a maximum value less than or equal to 10.0, for example, 2.4 to 7.6. Any maximum numerical limit listed herein is intended to include all lower numerical limits included therein, and any minimum numerical limit listed in this specification is intended to include all greater numerical limits included therein. Therefore, the applicant reserves the right to modify this specification (including claims) to explicitly list any sub-ranges included in the scope explicitly listed herein.

[0080] The electronic or electrical devices and / or any other related devices or components according to the embodiments of the present disclosure described herein may be implemented using any suitable hardware, firmware (e.g., an application specific integrated circuit), software, or a combination of software, firmware, and hardware. For example, the various components of these devices may be formed on an integrated circuit (IC) chip or on separate IC chips. In addition, the various components of these devices may be implemented on a flexible printed circuit film, a tape carrier package (TCP), a printed circuit board (PCB), or formed on a substrate.

[0081] In addition, the various components of these devices may be processes or threads that run on one or more processors in one or more computing devices to execute computer program instructions and interact with other system components to perform the various functions described herein. Computer program instructions are stored in a memory that can be implemented in a computing device using a standard storage device (e.g., a random access memory (RAM)). Computer program instructions may also be stored in other non-transitory computer-readable media (e.g., such as a CD-ROM, a flash drive, etc.). Moreover, those skilled in the art should recognize that the functions of various computing devices may be combined or integrated into a single computing device, or the functions of a particular computing device may be distributed on one or more other computing devices without departing from the spirit and scope of the embodiments of the present disclosure.

[0082] Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as those commonly understood by those skilled in the art to which the inventive concept belongs. It should also be understood that, unless explicitly defined as such herein, terms such as those defined in commonly used dictionaries should be interpreted as having the same meaning as they have in the context of the relevant technology and / or specification, and should not be interpreted in an idealized or overly formal sense.

[0083] Figure 1 is a perspective view showing a display device DD according to one embodiment of the present disclosure.

[0084] Reference Figure 1 , the display device DD has a rectangular shape having short sides in a first direction DR1 and long sides in a second direction DR2 intersecting the first direction DR1. However, the shape of the display device DD should not be limited to the rectangular shape, and in other embodiments, the display device DD may have various shapes.

[0085] The display device DD may be a foldable electronic device. For example, the display device DD according to the present embodiment may be folded around folding axes FX1 and FX2 that may extend in predetermined directions, respectively. Hereinafter, a state in which the display device DD is folded around the folding axes FX1 and FX2 is referred to as a "folded state", and a state in which the display device DD is not folded is referred to as a "non-folded state".

[0086] The folding axes FX1 and FX2 may extend in the first direction DR1 or the second direction DR2, respectively. In the present embodiment, the folding axis extending in the second direction DR2 is referred to as the "first folding axis FX1", and the folding axis extending in the first direction DR1 is referred to as the "second folding axis FX2". In other embodiments, the display device DD may include only one of the first folding axis FX1 and the second folding axis FX2. The display device DD may be folded around one of the first folding axis FX1 and the second folding axis FX2.

[0087] The display device DD according to the present embodiment can be applied to large electronic goods such as televisions and / or monitors, and can be applied to small and / or medium-sized electronic goods such as mobile phones, tablet computers, car navigation units, and / or game units. However, these are only examples, and thus the display device DD can be applied to other electronic goods as long as they do not deviate from the concept of the present disclosure.

[0088] like Figure 1 As shown in FIG. 1 , the display device DD may display an image IM on a display surface IS substantially parallel to each of the first direction DR1 and the second direction DR2, the image IM being displayed toward a third direction DR3. The display surface IS displaying the image IM may correspond to a front surface of the display device DD.

[0089] The display surface IS of the display device DD may be divided into a plurality of regions. The display surface IS of the display device DD may include a display area DA and a non-display area NDA defined therein.

[0090] The display area DA may be an area where the image IM is displayed, and the user may recognize the image IM through the display area DA. The display area DA may have a quadrilateral shape. The non-display area NDA may surround the display area DA. Accordingly, the display area DA may have a shape defined by the non-display area NDA. However, this is only an example, and the non-display area NDA may be located adjacent to only one side of the display area DA, or may be completely omitted. The display device DD according to the present embodiment may include various embodiments and should not be limited to a specific embodiment.

[0091] In the present embodiment, the non-display area NDA is an area adjacent to the display area DA, and the image IM is not displayed in the non-display area NDA. In addition, the display device DD has a frame area defined by the non-display area NDA.

[0092] The non-display area NDA may surround the display area DA, however, this is only an example. The non-display area NDA may be located adjacent to only a portion of an edge of the display area DA, and should not be limited to a specific embodiment.

[0093] The display device DD according to the present embodiment can sense a user input TC (or "external input") applied thereto from the outside. The user input TC includes various forms of external inputs, such as a part of the user's body, light, heat, or pressure. In the present embodiment, the user input TC is shown as a user's hand applied to the front surface, however, this is only an example. As described above, the user input TC may be provided in various forms, and the display device DD may sense the user input TC applied to the side surface or the rear surface of the display device DD according to the structure of the display device DD, however, they should not be limited to a specific embodiment.

[0094] The display device DD may activate the display surface IS to display the image IM while sensing the external input TC. In the present embodiment, the area for sensing the external input TC may be defined in the display area DA where the image IM is displayed. However, this is only an example, and the area for sensing the external input TC may be defined in the non-display area NDA, or may be defined over the entire display surface IS.

[0095] Figure 2A It is shown Figure 1 , which is a perspective view of a state in which the display device DD shown in FIG. 1 is folded inwardly (folded inwardly) around a first folding axis FX1, and Figure 2B It is shown Figure 1 0 is a perspective view of a state in which the display device DD is folded outward (folded outward) about a first folding axis FX1.

[0096] Reference Figure 1 and Figure 2AThe display device DD may be a foldable display device. The display device DD may be foldable around a first folding axis FX1 extending in a corresponding direction (eg, a predetermined direction).

[0097] The display device DD may include a plurality of regions defined therein according to its operation mode. The region may include at least one of the folding region FA and the non-folding regions NFA1 and NFA2. The folding region FA may be defined between the two non-folding regions NFA1 and NFA2.

[0098] As an example, the non-folding areas NFA1 and NFA2 may include a first non-folding area NFA1 located adjacent to one side of the folding area FA in the first direction DR1 and a second non-folding area NFA2 located adjacent to the other side of the folding area FA in the first direction DR1.

[0099] The display device DD can be folded inward (inward folding) or folded outward (outward folding). In this embodiment, "inward folding" means a state where the display surface IS is folded inward to allow a part thereof to face another part thereof, and "outward folding" means a state where the rear surface of the display device DD is folded inward to allow a part thereof to face another part thereof.

[0100] The folding area FA is folded around the first folding axis FX1 to form a curvature. The first folding axis FX1 may extend in the second direction DR2 (eg, in the long axis direction of the display device DD).

[0101] Figure 2A The display device DD shown in FIG. 1 can be folded inward (inwardly folded) to allow the display surface IS of the first non-folding area NFA1 to face the display surface IS of the second non-folding area NFA2.

[0102] Reference Figure 2B The display device DD may be folded outward around the first folding axis FX1 (outward folding). When the display device DD is folded outward, the display surface IS may be exposed to the outside.

[0103] Both the inward folding operation and the outward folding operation may occur in one display device DD. However, in the present disclosure, the display device DD may be folded to be in only one of the inward folding state and the outward folding state.

[0104] Figure 3A It is shown Figure 1 , which is a perspective view of a state in which the display device DD shown in FIG. 1 is folded inwardly (folded inwardly) around the second folding axis FX2, and Figure 3B It is shown Figure 1 0 is a perspective view of a state in which the display device DD is folded outward (folded outward) about the second folding axis FX2.

[0105] Reference Figure 3A and Figure 3B , the display device DD may be folded inward or outward about the second folding axis FX2. The second folding axis FX2 may extend in the first direction DR1 (eg, in the short axis direction of the display device DD).

[0106] The display device DD may include a plurality of areas defined therein according to its operation mode. The area may include at least one of the folding area FA2 and the non-folding areas NFA3 and NFA4. The folding area FA2 may be defined between the two non-folding areas NFA3 and NFA4.

[0107] As an example, the non-folding areas NFA3 and NFA4 may include a third non-folding area NFA3 located adjacent to one side of the folding area FA2 in the second direction DR2 and a fourth non-folding area NFA4 located adjacent to the other side of the folding area FA2 in the second direction DR2.

[0108] One display device DD may include a first folding axis FX1 and a second folding axis FX2 and may be folded on a major axis or a minor axis. However, in other embodiments, the display device DD may include only one of the first folding axis FX1 and the second folding axis FX2.

[0109] In the present embodiment, one folding area FA is defined in the display device DD, however, the present disclosure should not be limited thereto or thereby. According to another embodiment of the present disclosure, a plurality of folding areas may be defined in the display device DD.

[0110] Figure 4 is an exploded perspective view showing a display module DM according to one embodiment of the present disclosure, and Figure 5 It is shown Figure 4 A plan view of the display module DM is shown in FIG.

[0111] Reference Figure 4 and Figure 5 According to the present embodiment, the display module DM may include a display panel DP and a window WM located on the display panel DP. The display module DM may form a display device DD (see Figure 1 ) and, for example, the display module DM may provide a display surface IS (refer to Figure 1 ).

[0112] The display panel DP may be a flexible display panel. Accordingly, the display panel DP may be folded or unfolded relative to the first folding axis FX1. As an example, the display panel DP may be an organic light emitting display panel, but is not limited thereto.

[0113] The upper surface of the window WM defines the display surface IS of the display device DD. The window WM may be optically transparent. Therefore, the user may easily notice the image generated by the display panel DP through the window WM.

[0114] The window WM may include a flexible material. Therefore, the window WM may be folded or unfolded around the first folding axis FX1. That is, when the shape of the display panel DP is deformed, the shape of the window WM may be deformed.

[0115] The window WM transmits an image from the display panel DP and also serves as a buffer against external impacts to prevent the display panel DP from being damaged or malfunctioning due to the external impacts. The external impacts refer to external forces represented by pressure or stress, which may otherwise cause defects in the display panel DP. The window WM can prevent defects in the display panel DP by mitigating bending deformation, compression deformation, and / or tensile deformation of the display panel DP caused by point impacts and / or surface impacts.

[0116] One or more functional layers FC may be located between the display panel DP and the window WM. As an example, the functional layer FC may be an anti-reflection layer that blocks reflection of external light. The anti-reflection layer may reduce or prevent visibility of components included in the display panel DP (e.g., visible from the outside due to external light incident through the front surface of the display device DD). The anti-reflection layer may include a polarizing film and / or a delay film. The number of delay films and the delay length (λ / 4 or λ / 2) of the delay film may be determined according to the working principle of the anti-reflection layer.

[0117] Functional layer FC may also include sensing user input TC (refer to Figure 1 ) of the display panel DP. The input sensing layer is formed separately from the display panel DP and is coupled to the display panel DP through an adhesive layer. In some embodiments, the input sensing unit may be integrally provided with the display panel DP through at least one continuous process. That is, the input sensing unit may be directly located on the thin film encapsulation layer of the display panel DP. Here, the expression "directly located" means that the input sensing unit is located on the display panel DP without using a separate adhesive member.

[0118] The window WM and the functional layer FC may be attached to each other through a first adhesive layer AL1. The display panel DP and the functional layer FC may be attached to each other through a second adhesive layer AL2.

[0119] The first adhesive layer AL1 and the second adhesive layer AL2 may be optically transparent. The first adhesive layer AL1 and the second adhesive layer AL2 may each be an adhesive layer manufactured by coating a liquid adhesive material and by curing the liquid adhesive material, or may be an adhesive sheet manufactured separately. For example, the first adhesive layer AL1 and the second adhesive layer AL2 may each be a pressure sensitive adhesive (PSA), an optically clear adhesive (OCA), or an optically clear resin (OCR).

[0120] The protective film PF may be located on the rear surface of the display panel DP. The protective film PF may include a polymer material. The protective film PF absorbs impact applied thereto from the outside, thereby protecting the display panel DP from the impact. The protective film PF may be attached to the rear surface of the display panel DP through a third adhesive layer AL3.

[0121] Figure 4 The protective film PF is shown on the rear surface of the display panel DP. However, the present disclosure should not be limited thereto or thereby. For example, the display module DM may further include an upper protective film between the display panel DP and the functional layer FC.

[0122] The material for forming the protection film PF should not be limited to plastic resins, and may include an organic / inorganic composite material. The protection film PF may include a porous organic layer and an inorganic material filled in the pores of the organic layer.

[0123] Reference Figure 5 , the display module DM may further include a flexible printed circuit board FCB connected to the display panel DP and a driving chip D-IC mounted on the flexible printed circuit board FCB. The flexible printed circuit board FCB may be connected to a main circuit board MCB. Components such as a control chip, a plurality of passive components, and a plurality of active components may be mounted on the main circuit board MCB. The main circuit board MCB may be a flexible film such as the flexible printed circuit board FCB.

[0124] In this embodiment, a chip on film (COF) structure in which a driver chip D-IC is mounted on a flexible printed circuit board FCB is shown. In the COF structure, the display module DM may include two circuit boards (e.g., a flexible printed circuit board FCB and a main circuit board MCB). However, the present disclosure should not be limited thereto or thereby. For example, the display module DM may have a chip on panel (COP) structure in which a driver chip D-IC is mounted on a display panel DP.

[0125] Fig. 6A is along Figure 5 The cross-sectional view of the non-folding area NFA1 is shown by taking the line II' shown in FIG. Figure 6B is along Figure 5 1 is taken along the line II-II' shown in FIG. 1 to show a cross-sectional view of the folding area FA.

[0126] Reference Fig. 6A and Figure 6B The window WM may include a base layer WBS, a window function layer WFC and a window protection layer WPF. The base layer WBS, the window function layer WFC and the window protection layer WPF may be arranged in a third direction DR3 (refer to Figure 1 ) are stacked sequentially.

[0127] The base layer WBS may include a transparent insulating material. The base layer WBS may have flexibility, but the present disclosure should not be limited thereto or thereby. That is, the base layer WBS may include a material that can be bent by adjusting its thickness, even if the material is generally rigid.

[0128] As an example, the base layer WBS may include at least one of polyimide (PI), polyamide-imide (PAI), polyetheretherketone (PEEK), polyetherimide (PEI), and thin-film glass. However, this is only an example, and the material for the base layer WBS should not be limited thereto or thereby.

[0129] The window function layer WFC may be located on the base layer WBS. For example, the window function layer WFC may include at least one of an anti-fingerprint layer, an anti-reflection layer, an anti-glare layer, and a hard coating layer. The window function layer WFC may be located on the upper surface (e.g., the surface facing the user) of the base layer WBS. The hard coating layer of the window function layer WFC protects the base layer WBS from external impacts. The hard coating layer may have a higher indentation hardness than the base layer WBS. Accordingly, the hard coating layer may include at least one of a polyurethane-based resin, an epoxy-based resin, an acrylic-based resin, and an acrylate-based resin.

[0130] The window protection layer WPF is located on the window functional layer WFC. The window protection layer WPF improves the impact resistance of the window WM and prevents the window WM from being broken when the window WM is damaged. In particular, when the window functional layer WFC includes a hard coating layer, the window protection layer WPF absorbs external impacts to protect the hard coating layer from external impacts, and thus can improve the impact resistance of the hard coating layer.

[0131] The window protection layer WPF may include at least one selected from polyurethane-based resins, epoxy-based resins, polyester-based resins, polyether-based resins, acrylate-based resins, acrylonitrile-butadiene-styrene (ABS) resins, and rubber. As an example, the window protection layer WPF may include at least one of phenylene, polyethylene terephthalate (PET), polyimide (PI), polyamide (PAI), polyethylene naphthalate (PEN), and polycarbonate (PC).

[0132] An adhesive layer may also be located between the window protection layer WPF and the window functional layer WFC.

[0133] The first side surface portion WSP1 of the window WM is arranged in the first non-folding area NFA1 and the second non-folding area NFA2, and has a first surface roughness in the first non-folding area NFA1 and the second non-folding area NFA2. The second side surface portion WSP2 of the window WM is arranged in the folding area FA, and has a second surface roughness in the folding area FA. The second surface roughness is less than / less than the first surface roughness (for example, less rough than it). The first surface roughness is defined by the average value of the height or distance from the reference surface RS parallel to the third direction DR3 to the first side surface portion WSP1 of the window WM in the first non-folding area NFA1 and the second non-folding area NFA2. The second surface roughness is defined by the average value of the height or distance from the reference surface RS to the second side surface portion WSP2 of the window WM in the folding area FA.

[0134] Each of the first side surface portion WSP1 and the second side surface portion WSP2 of the window WM may include the side surface WS1 or WS4 of the base layer WBS, the side surface WS2 or WS5 of the window functional layer WFC, and the side surface WS3 or WS6 of the window protection layer WPF. In the case where the adhesive layer is located between the window functional layer WFC and the window protection layer WPF, each of the first side surface portion WSP1 and the second side surface portion WSP2 of the window WM may also include the side surface of the adhesive layer.

[0135] In this case, the first surface roughness of the first side surface portion WSP1 of the window WM may be defined as a value obtained by averaging the heights of the side surface WS1 of the base layer WBS, the side surface WS2 of the window functional layer WFC, and the side surface WS3 of the window protection layer WPF relative to the reference surface RS in the first non-folding area NFA1 and the second non-folding area NFA2. The second surface roughness of the second side surface portion WSP2 of the window WM may be defined as a value obtained by averaging the heights of the side surface WS4 of the base layer WBS, the side surface WS5 of the window functional layer WFC, and the side surface WS6 of the window protection layer WPF in the folding area FA relative to the reference surface RS.

[0136] According to the present embodiment, the first side surface portion WSP1 of the window WM may have a surface roughness relatively greater than that of the second side surface portion WSP2 of the window WM. Since the laser processing is performed along the cutting line, surface modification may occur on the first side surface portion WSP1 and the second side surface portion WSP2 of the window WM to complete the display module DM. In this case, the fact that the second surface roughness of the second side surface portion WSP2 of the window WM is less than the first surface roughness of the first side surface portion WSP1 of the window WM may mean that the surface modification of the second side surface portion WSP2 of the window WM occurs less than the surface modification of the first side surface portion WSP1 of the window WM.

[0137] The fact that the second surface roughness of the second side surface portion WSP2 of the window WM is relatively small and surface modification occurs less in the folding area FA may mean that the stress applied to the second side surface portion WSP2 of the window WM in the folding area FA during laser processing and the damage to the second side surface portion WSP2 of the window WM are small. As described above, since the stress and damage applied to the folding area FA are reduced or minimized in the manufacturing process, defects such as cracks can be reduced or prevented from occurring in the folding area FA despite repeated folding operations of the completed display device DD.

[0138] Fig. 7A It is through shooting Fig. 6A A scanning electron microscope (SEM) image of the side surface of the window WM located in the non-folding area NFA1 is obtained, and Figure 7B It is through shooting Figure 6B SEM image obtained from the side surface of the window WM located in the folding area FA.

[0139] Reference Fig. 7A and Figure 7B , the first side surface portion WSP1 in the non-folding areas NFA1 and NFA2 of the window WM has a surface roughness greater than the surface roughness of the second side surface portion WSP2 in the folding area FA of the window WM. That is, although relatively large and irregular concave-convex portions are formed on the first side surface portion WSP1 of the window WM located in the non-folding areas NFA1 and NFA2, relatively small and irregular concave-convex portions are formed on the second side surface portion WSP2 of the window WM located in the folding area FA.

[0140] like Fig. 7A As shown in , large and small black spots are visually observed on the side surface WS3 of the window protection layer WPF located in the non-folding areas NFA1 and NFA2. In this case, the black spots may be portions that are recessed from the side surface WS3 of the window protection layer WPF. The relatively bright portions around the black spots may be portions that are convexly protruded. That is, when the side surface WS3 of the window protection layer WPF located in the non-folding areas NFA1 and NFA2 is observed as a whole, the number and size of the black spots are large, and there is a significant difference in contrast depending on the position.

[0141] Reference Figure 7B, there is no significant difference in contrast depending on the position on the side surface WS6 of the window protection layer WPF located in the folding area FA, and the black spot is almost invisible. Accordingly, it is found that the side surface WS3 of the window protection layer WPF located in the non-folding areas NFA1 and NFA2 has a surface roughness higher than the surface roughness of the side surface WS6 of the window protection layer WPF located in the folding area FA. In other words, the side surface WS6 in the folding area FA of the window protection layer WPF is smoother than the side surface WS3 in the non-folding areas NFA1 and NFA2 of the window protection layer WPF.

[0142] In addition, the size of the area indicated by the dark color on the side surface WS1 of the base layer WBS in the non-folding areas NFA1 and NFA2 is larger than the size of the area indicated by the dark color on the window protection layer WPF. That is, a concave-convex portion larger than the concave-convex portion of the window protection layer WPF is formed on the side surface WS1 of the base layer WBS in the non-folding areas NFA1 and NFA2. The surface roughness of the side surface WS1 in the non-folding areas NFA1 and NFA2 of the base layer WBS may be greater than the surface roughness of the side surface WS3 in the non-folding areas NFA1 and NFA2 of the window protection layer WPF.

[0143] Reference Figure 7B , fine black spots are observed on the side surface WS4 of the base layer WBS located in the folding area FA. That is, a concavo-convex portion smaller than the concavo-convex portion on the side surface WS1 of the base layer WBS located in the non-folding areas NFA1 and NFA2 is formed on the side surface WS4 of the base layer WBS in the folding area FA. The surface roughness of the side surface WS4 of the base layer WBS located in the folding area FA may be smaller than the surface roughness of the side surface WS1 of the base layer WBS located in the non-folding areas NFA1 and NFA2.

[0144] Therefore, although a relatively large surface deformation in the first direction DR1 occurs in the side surface of each layer of the window WM in the non-folding areas NFA1 and NFA2, a relatively small surface deformation in the first direction DR1 occurs in the folding area FA. That is, the stress and damage applied to the second side surface portion WSP2 of the window WM located in the folding area FA during the manufacturing process of the display module DM may be smaller than that in the display module DM (refer to FIG. Figure 4 ) during the manufacturing process of FIG. 1 and FIG. 2 , stress and damage applied to the first side surface portion WSP1 of the window WM located in the non-folding areas NFA1 and NFA2.

[0145] Fig. 8A is a graph showing changes in the height of each layer of the window WM in the non-folding areas NFA1 and NFA2 relative to the reference surface RS, and Figure 8Bis a graph showing the change in height of each layer of the window WM in the folding area FA relative to the reference surface RS. Fig. 8A and Figure 8B , the horizontal axis represents the position, and the vertical axis represents the height relative to the reference surface RS.

[0146] Reference Fig. 6A , Figure 6B , Fig. 8A and Figure 8B , when the height of the reference surface RS is zero (0), the side surface of each layer of the window WM may be located at a different height / distance from the reference surface RS depending on the location. Fig. 8A and Figure 8B In the embodiment, the first position range PR1 may be defined as a region where the window protection layer WPF is located, and the second position range PR2 may be defined as a region where the base layer WBS is located.

[0147] The side surface WS3 of the window protection layer WPF may be located at a first height range HR1 from the reference surface RS in the non-folding areas NFA1 and NFA2. The side surface WS6 of the window protection layer WPF may be located at a second height range HR2 from the reference surface RS in the folding area FA. The second height range HR2 may have a width smaller than that of the first height range HR1. That is, the change in the height of the side surface WS6 of the window protection layer WPF is smaller in the folding area FA than in the non-folding areas NFA1 and NFA2.

[0148] The side surface WS1 of the base layer WBS may be located at a third height range HR3 from the reference surface RS in the non-folding areas NFA1 and NFA2. The side surface WS4 of the base layer WBS may be located at a fourth height range HR4 from the reference surface RS in the folding area FA. The fourth height range HR4 may have a width smaller than that of the third height range HR3. That is, the variation in the height of the side surface WS4 of the base layer WBS is smaller in the folding area FA than in the non-folding areas NFA1 and NFA2.

[0149] In addition, when the surface roughness in the third direction DR3 of the first side surface portion WSP1 and the second side surface portion WSP2 of the window WM is represented by a root mean square (Rq), the surface roughness Rq of the first side surface portion WSP1 of the window WM in the non-folding areas NFA1 and NFA2 may be approximately 293 μm, and the surface roughness Rq of the second side surface portion WSP2 of the window WM in the folding area FA may be approximately 208 μm.

[0150] That is, although a relatively large surface deformation in the third direction DR3 occurs in the first side surface portion WSP1 of the window WM, a relatively small surface deformation in the third direction DR3 occurs in the second side surface portion WSP2 of the window WM. In other words, the stress and damage applied to the second side surface portion WSP2 of the window WM located in the folding area FA in the manufacturing process of the display module DM may be smaller than that in the display module DM (refer to FIG. Figure 4 ) in the manufacturing process of the window WM, and the stress and damage applied to the first side surface portion WSP1 of the window WM located in the non-folding areas NFA1 and NFA2.

[0151] Fig. 9A It is through shooting Fig. 6A The SEM image obtained by the side surface of the functional layer FC located in the non-folding area NFA1 shown in FIG. Fig. 9B It is through shooting Figure 6B . SEM image obtained from the side surface of the functional layer FC located in the folding area FA shown in FIG.

[0152] Reference Fig. 9A and Fig. 9B , the first side surface FS1 of the functional layer FC located in the non-folding areas NFA1 and NFA2 has a surface roughness greater than the surface roughness of the second side surface FS2 of the functional layer FC located in the folding area FA. That is, although relatively large wavy concavo-convex portions are formed on the first side surface FS1 of the functional layer FC located in the non-folding areas NFA1 and NFA2, relatively small wavy and irregular concavo-convex portions are formed on the second side surface FS2 of the functional layer FC located in the folding area FA.

[0153] That is, the first side surface FS1 of the functional layer FC located in the non-folding areas NFA1 and NFA2 has a surface roughness greater than a surface roughness of the second side surface FS2 of the functional layer FC located in the folding area FA.

[0154] Therefore, although a large surface deformation in the first direction DR1 occurs on the first side surface FS1 of the functional layer FC, a small surface deformation in the first direction DR1 occurs on the second side surface FS2 of the functional layer FC. That is, the stress and damage applied to the second side surface FS2 of the functional layer FC in the folding area FA during the manufacturing process of the display module DM may be smaller than the stress and damage applied to the first side surface FS1 of the functional layer FC in the non-folding areas NFA1 and NFA2 during the manufacturing process of the display module DM (refer to Figure 4 ).

[0155] Fig.10 is along Figure 5The cross-sectional view is taken along line III-III'.

[0156] Reference Figure 5 and Fig.10 , the display module DM may include a flexible display panel DP. The display panel DP may include a bending area (e.g., a circuit board bending area) BA and a non-bending area NBA. The non-bending area NBA may include a display area DA and a non-display area NDA of the display module DM. The bending area BA may correspond to a portion of the display panel DP and may be bent. The folding area FA and the first and second non-folding areas NFA1 and NFA2 of the display module DM may be included in the non-bending area NBA.

[0157] The bending area BA may include a curvature area CA, wherein the display panel DP may have a curvature (e.g., a predetermined curvature) in a bent state, and has a facing area FCA facing the non-bending area NBA in a bent state. The curvature area CA is defined as being adjacent to the non-bending area NBA and being substantially curved. The facing area FCA is defined as being adjacent to the curvature area CA and not forming a curvature (e.g., being substantially uncurved). The facing area FCA faces the non-bending area NBA and is spaced apart from the non-bending area NBA. The flexible printed circuit board FCB is connected to the facing area FCA of the display panel DP.

[0158] The protective film PF is located corresponding to the non-bending area NBA and the facing area FCA, and is not located in the curvature area CA. The bending opening OPP may be defined by the protective film PF to correspond to the curvature area CA. When the protective film PF is removed from the curvature area CA, stress occurring in the curvature area CA during the bending process of the display panel DP may be reduced. When the bending opening OPP is defined in the protective film PF, as an example, the third adhesive layer AL3 corresponding to the bending opening OPP may be removed.

[0159] According to another embodiment, the protection film PF includes a groove defined therein or thereby in a region corresponding to the curvature area CA. That is, instead of being completely omitted, the protection film PF may be formed thinner in the curvature area CA than in other areas (eg, the non-bending area NBA and the facing area FCA).

[0160] Fig.11 is an exploded perspective view showing a display device DD according to one embodiment of the present disclosure, and Fig.12 is along Fig.11 A cross-sectional view taken along line IV-IV' shown in FIG.

[0161] Reference Fig.11 and Fig.12The display device DD includes a display module DM and a cover plate CVP. The display module DM includes a display panel DP for displaying an image and a window WM located on the display panel DP. The display module DM has Figure 4 and Figure 5 The display module DM shown in FIG. 1 has substantially the same structure, and thus the details thereof will be omitted.

[0162] The cover panel CVP is located below the display module DM. The cover panel CVP is coupled to the rear surface of the display module DM. The cover panel CVP supports the rear surface of the display module DM. The cover panel CVP has a structure in which layers are stacked in the third direction DR3.

[0163] As an example, the cover plate CVP may include a support plate SP and a fourth adhesive layer AL4. The support plate SP may be located on the rear surface of the display module DM. The support plate SP may be a metal plate. The support plate SP may be a stainless steel plate. The support plate SP may have a strength greater than that of the display module DM.

[0164] The support plate SP may include a first support plate SP1 supporting the first non-folding area NFA1 of the display module DM and a second support plate SP2 supporting the second non-folding area NFA2. The first support plate SP1 and the second support plate SP2 may have a plate shape.

[0165] The first support plate SP1 and the second support plate SP2 may be spaced apart from each other in the first direction DR1. The first support plate SP1 and the second support plate SP2 may be spaced apart from each other at the folding area FA. The first support plate SP1 may overlap a portion of the folding area FA, and the second support plate SP2 may overlap a portion of the folding area FA. That is, the distance between the first support plate SP1 and the second support plate SP2 in the first direction DR1 may be smaller than the width of the folding area FA.

[0166] The fourth adhesive layer AL4 includes a first sub-adhesive layer AL4-1 and a second sub-adhesive layer AL4-2. The first sub-adhesive layer AL4-1 overlaps the first non-folding area NFA1, and the second sub-adhesive layer AL4-2 overlaps the second non-folding area NFA2. The first sub-adhesive layer AL4-1 and the second sub-adhesive layer AL4-2 are positioned to be spaced apart from each other in the first direction DR1. The first sub-adhesive layer AL4-1 and the second sub-adhesive layer AL4-2 are positioned to be spaced apart from each other in the folding area FA. The first sub-adhesive layer AL4-1 is located between the first support plate SP1 and the display module DM, and the second sub-adhesive layer AL4-2 is located between the second support plate SP2 and the display module DM.

[0167] The cover plate CVP further includes a buffer film BF and a fifth adhesive layer AL5. The buffer film BF is located between the fourth adhesive layer AL4 and the display module DM. The buffer film BF may include a polymer material. The buffer film BF may be a layer that absorbs external impact applied thereto from the outside.

[0168] Fig.11 and Fig.12 A structure in which the buffer film BF includes one layer is shown, however, the present disclosure should not be limited thereto or thereby. The buffer film BF may include a plurality of layers, and the positions thereof should not be limited thereto or thereby.

[0169] The support plate SP may be fixed to the buffer film BF by the fourth adhesive layer AL4. The support plate SP may be attached to the rear surface of the buffer film BF by the fourth adhesive layer AL4. The buffer film BF may be formed on the entirety of the folding area FA and the first non-folding area NFA1 and the second non-folding area NFA2. The first support plate SP1 may be attached to the rear surface of the buffer film BF by the first sub-adhesive layer AL4-1, and the second support plate SP2 may be attached to the rear surface of the buffer film BF by the second sub-adhesive layer AL4-2.

[0170] The fifth adhesive layer AL5 is located between the buffer film BF and the display module DM to attach the buffer film BF to the rear surface of the display module DM.

[0171] The fourth adhesive layer AL4 and the fifth adhesive layer AL5 may be optically transparent. The fourth adhesive layer AL4 and the fifth adhesive layer AL5 may be adhesive layers manufactured by coating a liquid adhesive material and curing the liquid adhesive material, or may be adhesive sheets manufactured separately. For example, the fourth adhesive layer AL4 and the fifth adhesive layer AL5 may be a pressure sensitive adhesive (PSA), an optically clear adhesive (OCA), or an optically clear resin (OCR).

[0172] Fig.10 , Fig.11 and Fig.12 As a representative example, a support plate SP including two support plates SP1 and SP2 is shown. However, the number of support plates should not be limited to two. When the number of first folding axes FX1 increases, the support plate SP may include a plurality of support plates separated from each other relative to the first folding axis FX1. The first support plate SP1 and the second support plate SP2 may be located corresponding to the non-bending area NBA.

[0173] When the curvature area CA of the display module DM is bent, the facing area FCA faces the non-bending area NBA, and the flexible printed circuit board FCB and the main circuit board MCB connected to the facing area FCA are located parallel to the non-bending area NBA of the display panel DP. The first support plate SP1 and the second support plate SP2 may be located overlapping the non-bending area NBA. In addition, after the display module DM is bent, the flexible printed circuit board FCB and the main circuit board MCB may be placed on the rear surface of the second support plate SP2.

[0174] The display device DD may further include an adhesive layer to attach the flexible printed circuit board FCB and the main circuit board MCB to the second support plate SP2. Accordingly, the flexible printed circuit board FCB and the main circuit board MCB may be fixed to the rear surface of the second support plate SP2.

[0175] FIG. 13A to FIG. 13C is a plan view illustrating a method of manufacturing a display panel according to an embodiment of the present disclosure. Fig.14A and Fig. 14B is a process diagram showing a first laser process, and Fig.15A and Fig. 15B is a process diagram showing the second laser processing. For example, Fig.14A Shown along Fig.13A A cross-sectional view taken along the line V-V' shown in FIG. Fig.15A Shown along Fig. 13B A cross-sectional view taken along line VI-VI' shown in FIG.

[0176] Reference Fig.13A , a preliminary display module P-DM including an active area AA and an inactive area NAA distinguished from each other with respect to a cutting line CL is prepared. When a cutting process is performed along the cutting line CL, a preliminary display module P-DM including only the active area AA may be manufactured. The cutting line CL may include a first cutting line CL1 located in the first non-folding area NFA1 and the second non-folding area NFA2 and a second cutting line CL2 located in the folding area FA.

[0177] Reference FIG. 13A to FIG. 14A , performing a first laser process along a first cutting line CL1 located in the first non-folding area NFA1 and the second non-folding area NFA2. The first laser process is performed using a first laser device LD1. The first laser process may include arranging the first laser device LD1 above or below the rear surface of the preliminary display module P-DM and irradiating a laser beam onto the first cutting line CL1 located in the first non-folding area NFA1 and the second non-folding area NFA2. The rear surface of the preliminary display module P-DM may be defined as being opposite to the display surface IS (refer to FIG. 1 ) of the display module DM. Figure 1 )'s front surface opposite to the surface.

[0178] Accordingly, a portion of the inactive area NAA adjacent to the first non-folding area NFA1 and the second non-folding area NFA2 may be removed by the first laser treatment. In this case, the removed portion may be defined as a first portion of the inactive area NAA. Fig. 14B As shown in FIG. 1 , after the first laser process, a side surface DM_S1 of the display module DM may be formed in the first non-folding area NFA1 and the second non-folding area NFA2 .

[0179] Reference FIG. 13B to FIG. 15A , along the second cutting line CL2 located in the folding area FA (see Fig.13A ) performs a second laser treatment. After the first laser treatment, the invalid area NAA remains in the preliminary display module P-DM adjacent to the folding area FA. The remaining invalid area R-NAA may be defined as a second portion of the invalid area NAA.

[0180] The second laser process may be performed using the second laser device LD2. The second laser process may include arranging the second laser device LD2 above or below the rear surface of the preliminary display module P-DM and irradiating a laser beam onto the second cutting line CL2 located in the folding area FA.

[0181] Therefore, the remaining ineffective area R-NAA located adjacent to the folding area FA may be removed by the second laser treatment. Fig. 15B As shown in FIG. 1 , the side surface DM_S2 of the display module DM may be formed in the folding area FA.

[0182] Therefore, if Fig. 13C As shown in FIG. 1 , the preliminary display module P-DM may be cut into the shape of a display module DM employed in an actual display device DD through a first laser process and a second laser process.

[0183] The first laser treatment may be defined as high-energy laser treatment, and the second laser treatment may be defined as low-energy laser treatment. That is, the second laser treatment may be performed by irradiating a laser beam having lower energy than that used in the first laser treatment.

[0184] The first laser treatment may include a process of repeatedly irradiating a laser beam N times. The second laser treatment may include a process of repeatedly irradiating a laser beam M times. In this case, the value of M may be in the range of about 3N to about 3.5N. That is, the number of laser irradiations in the second laser treatment may be greater than the number of laser irradiations in the first laser treatment (e.g., about 3 times to about 3.5 times).

[0185] In some embodiments, the first laser device LD1 irradiates the laser beam at a first speed in the first laser process, and the second laser device LD2 irradiates the laser beam at a second speed in the second laser process. The first speed may be different from the second speed. The second speed may be faster than the first speed.

[0186] In the present embodiment, different laser devices LD1 and LD2 are used in the first laser processing and the second laser processing. However, the present disclosure should not be limited thereto or thereby. That is, in other embodiments, the first laser processing and the second laser processing may be performed by the same laser device, and in this case, the energy of the laser beam used in the first laser processing may be set to be different from the energy of the laser beam used in the second laser processing.

[0187] As described above, when the preliminary display module P-DM is cut using laser processing, high energy is used to cut the preliminary display module P-DM in the non-folding areas NFA1 and NFA2, and low energy is used to cut the preliminary display module P-DM in the folding area FA. Accordingly, stress applied to the side surface DM_S2 of the folding area FA during the cutting process and damage caused to the side surface DM_S2 of the folding area FA can be reduced. Therefore, defects such as cracks caused by stress and damage applied to the side surface DM_S2 due to repeated folding operations can be reduced. As a result, the product reliability of the foldable display device can be improved.

[0188] Although the embodiments of the present disclosure have been described, it should be understood that the present disclosure should not be limited to these embodiments, and that various changes and modifications may be made by those skilled in the art within the spirit and scope of the present disclosure as defined in the appended claims. Therefore, the disclosed subject matter should not be limited to any single embodiment described herein, and the scope of the inventive concept should be determined according to the appended claims and their functional equivalents to be included therein.

Claims

1. A display device, comprising: a display panel configured to display an image and comprising a folding region configured to be folded about a folding axis and a non-folding region adjacent to the folding region; as well as a window, the window being located on the display panel and being configured to be folded along the display panel, wherein the window comprises a plurality of layers stacked sequentially in a stacking direction, and the plurality of layers of the window all extend across all of the non-folding regions and the folding regions, and A side surface of at least one layer among the plurality of layers is located at a first height range from a reference surface in the non-folding region, and is located at a second height range from the reference surface in the folding region, the second height range being smaller than the first height range.

2. The display device according to claim 1, wherein: The side surface of the at least one layer among the plurality of layers has a surface roughness higher in the non-folding region than in the folding region.

3. The display device according to claim 1, wherein: The plurality of layers of the window include: Base layer; a window function layer, the window function layer being located on the base layer; and a window protection layer, the window protection layer covers the window functional layer, and Wherein, the base layer, the window functional layer and the window protection layer are stacked sequentially.

4. The display device according to claim 3, wherein: Respective side surfaces of the plurality of layers include a side surface of the base layer, a side surface of the window function layer, and a side surface of the window protection layer.

5. The display device according to claim 1, further comprising: A functional layer is located between the display panel and the window.

6. The display device according to claim 5, wherein: The side surface of the functional layer has a surface roughness higher in the unfolded region than in the folded region.

7. The display device according to claim 1, further comprising: A protective film is located on the rear surface of the display panel.

8. The display device according to claim 1, wherein: The display panel is a flexible display panel.

9. A method for manufacturing a display device, the display device comprising: a display panel configured to display an image and comprising a folding region configured to be folded about a folding axis and a non-folding region adjacent to the folding region; as well as a window, the window being located on the display panel and being configured to be folded along the display panel, The method comprises: preparing a preliminary display module including an active area and an inactive area distinguished from each other with respect to a cutting line; forming a first side surface portion of the window in the non-folding region, the first side surface portion having a first surface roughness; and forming a second side surface portion of the window in the folding region, the second side surface portion having a second surface roughness smaller than the first surface roughness, The window comprises a plurality of layers stacked sequentially in a stacking direction, and the plurality of layers of the window all extend across all of the non-folding regions and the folding regions.

10. The method of claim 9, wherein: Forming the first side surface portion of the window includes: performing a first laser process along a first cutting line of the cutting line located in the non-folding area to separate a first portion of the ineffective area from the effective area; and Forming the second side surface portion of the window includes performing a second laser process along a second cutting line of the cutting line located in the folding region to separate a second portion of the ineffective region from the effective region.

11. The method of claim 10, wherein: Performing the second laser treatment includes: A second laser beam having lower energy than the first laser beam used in the first laser processing is irradiated.

12. The method of claim 11, wherein: Performing the first laser processing includes: Repeat irradiating the first laser beam N times, Wherein, performing the second laser processing comprises: Repeat irradiating the second laser beam M times, M has a value in the range of 3N to 3.5N.

13. The method of claim 11, wherein: Performing the first laser processing includes: irradiating the first laser beam at a first speed, and Wherein, performing the second laser processing comprises: The second laser beam is irradiated at a second speed faster than the first speed.

14. The method of claim 10, wherein: Performing the first laser processing includes: irradiating a first laser beam on the rear surface of the preliminary display module along the first cutting line, and Wherein, performing the second laser processing comprises: A second laser beam is irradiated on the rear surface of the preliminary display module along the second cutting line.

15. An electronic device comprising: a display panel configured to display an image and comprising a folding region configured to be folded about a folding axis and a non-folding region adjacent to the folding region; as well as a window, the window being located on the display panel and being configured to be folded along the display panel, wherein the window comprises a plurality of layers stacked sequentially in a stacking direction, and the plurality of layers of the window all extend across all of the non-folding regions and the folding regions, and A side surface of at least one layer among the plurality of layers is located at a first height range from a reference surface in the non-folding region, and is located at a second height range from the reference surface in the folding region, the second height range being smaller than the first height range.

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