Foldable display device

Abstract

The present disclosure relates to a foldable display device. Regarding the present disclosure, stress caused by folding during the process of folding or unfolding the foldable display device is alleviated, thereby suppressing damage caused in the foldable display device.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10 - 2020 - 0180822, filed on December 22, 2020, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. Technical Field

[0003] The present disclosure relates to a foldable display device, and more particularly, to a foldable display device that reduces stress caused by multiple folds during folding and unfolding of the foldable display device. Background Art

[0004] Recently, as society has entered a full - fledged information age, the field of display devices for processing and displaying a large amount of information has rapidly developed. As display devices for monitors of computers, televisions, or cellular phones, there are organic light - emitting display (OLED) devices as self - emitting devices and liquid - crystal display (LCD) devices that require a separate light source.

[0005] The scope of application of display devices has diversified to personal digital assistants and monitors of computers and televisions, and display devices with a large display area and reduced volume and weight are being studied.

[0006] In particular, recently, flexible display devices that are manufactured to be able to display images even in a state where they are bent or folded like paper have attracted attention as next - generation display devices. Flexible display devices use plastic thin - film transistor substrates instead of glass, and thus are classified into display devices with high durability that are not easily broken, bendable display devices that bend without breaking, rollable display devices that can be rolled up, and foldable display devices that can be folded. Such flexible display devices have advantages in terms of space utilization, interior, and design, and have various application fields.

[0007] Meanwhile, flexible display devices such as foldable display devices need to be folded and unfolded, so that pattern units are formed in the folding region of the structure supporting the display panel to ensure flexibility. However, stresses of different magnitudes are partially applied to the folding region where the pattern units are formed, so that damage occurs in the part where relatively more stress is applied, which may cause damage to the display panel. Therefore, there is a problem of deterioration in the display quality of the display panel. Summary of the Invention

[0008] An object to be achieved by the present disclosure is to provide a foldable display device in which damage generated in a part where more stress is applied is suppressed.

[0009] Another object to be achieved by the present disclosure is to provide a foldable display device having improved impact resistance.

[0010] The objects of the present disclosure are not limited to the above-mentioned objects, and other objects not mentioned above can be clearly understood by those skilled in the art from the following description.

[0011] According to an aspect of the present invention, there is provided a foldable display device including a first non-foldable region, a first foldable region, a second non-foldable region, a second foldable region, and a third non-foldable region sequentially positioned along a folding direction. The foldable display device includes: a display panel; and a support substrate that supports the display panel below the display panel and includes a plurality of opening patterns provided to correspond to the first foldable region and the second foldable region, wherein the first foldable region is folded inward so that the display surface of the display panel faces inward, while the second foldable region is folded outward so that the display surface of the display panel faces outward, and the width of at least some of the plurality of opening patterns provided in the first foldable region gradually increases in the direction of the second non-foldable region, and the width of at least some of the plurality of opening patterns provided in the second foldable region gradually increases in the direction of the third non-foldable region. Accordingly, damage generated in portions of the first foldable region and the second foldable region where more stress is applied can be suppressed.

[0012] Other details of the exemplary embodiments are included in the detailed description and the drawings.

[0013] According to the present disclosure, in the case where multiple folds including an inner foldable region in which the display surface of the display panel faces inward and an outer foldable region in which the display surface of the display panel faces outward are simultaneously achieved, the width of at least some of the plurality of opening patterns provided to correspond to the inner foldable region and the outer foldable region is changed. By doing so, when stress is generated due to multiple folds, the strain increases through the plurality of opening patterns having a varying width, so that the stress generated due to multiple folds can be reduced.

[0014] In addition, according to the present disclosure, a coating is formed on the support substrate using a material having excellent strain, but the coating is formed thicker in a portion where relatively more stress is applied to improve impact resistance and reduce stress caused by folding.

[0015] The effects according to the present disclosure are not limited to the above-exemplified contents, and more various effects are included in the present specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other aspects, features, and other advantages of the present disclosure will be more clearly understood from the following detailed description in conjunction with the accompanying drawings, in which:

[0017] Figure 1 is a schematic perspective view of a foldable display device according to an exemplary embodiment of the present disclosure;

[0018] Figure 2 is a schematic side view showing a folded shape of a foldable display device according to an exemplary embodiment of the present disclosure;

[0019] Figure 3 is along Figure 1 a schematic cross-sectional view of the foldable display device taken along line I-I';

[0020] Figure 4A is a schematic cross-sectional view showing an example of a support substrate configuring a foldable display device according to an exemplary embodiment of the present disclosure;

[0021] Figure 4B is a schematic plan view showing an example of a support substrate configuring a foldable display device according to an exemplary embodiment of the present disclosure;

[0022] Figure 5A is a schematic cross-sectional view showing an example of a support substrate configuring a foldable display device according to another exemplary embodiment of the present disclosure;

[0023] Figure 5B is a schematic plan view showing an example of a support substrate configuring a foldable display device according to another exemplary embodiment of the present disclosure;

[0024] Figure 6A is a schematic cross-sectional view showing an example of a support substrate configuring a foldable display device according to still another exemplary embodiment of the present disclosure;

[0025] Figure 6B is a schematic plan view showing an example of a support substrate configuring a foldable display device according to still another exemplary embodiment of the present disclosure;

[0026] Figure 7 is a schematic cross-sectional view showing an example of a support substrate configuring a foldable display device according to still another exemplary embodiment of the present disclosure;

[0027] Figure 8 is a schematic cross-sectional view showing an example of a support substrate configuring a foldable display device according to still another exemplary embodiment of the present disclosure; and

[0028] Figure 9 is a schematic cross-sectional view showing an example of a support substrate configuring a foldable display device according to still another exemplary embodiment of the present disclosure. Detailed Implementation Modes

[0029] By referring to the exemplary implementation modes described in detail below and the accompanying drawings, the advantages and characteristics of the present disclosure and the methods for achieving the advantages and characteristics will become clear. However, the present disclosure is not limited to the exemplary implementation modes disclosed herein, but will be implemented in various forms. The exemplary implementation modes are provided only as examples so that those skilled in the art can fully understand the disclosure content and the scope of the present disclosure. Therefore, the present disclosure is only limited by the scope of the appended claims.

[0030] The shapes, sizes, ratios, angles, numbers, etc. shown in the accompanying drawings for describing the exemplary implementation modes of the present disclosure are only examples, and the present disclosure is not limited thereto. Throughout the specification, like reference numerals generally denote like elements. In addition, in the following description of the present disclosure, detailed descriptions of known related technologies may be omitted to avoid unnecessarily obscuring the subject matter of the present disclosure. Terms such as "including", "having", and "consisting of" used herein generally intend to allow the addition of other components, unless these terms are used together with the term "only". Any reference to the singular may include the plural unless otherwise explicitly stated.

[0031] Even if not explicitly stated, components are interpreted to include a normal error range.

[0032] When terms such as "on", "above", "below", and "adjacent to" are used to describe the positional relationship between two components, unless these terms are used together with "immediately" or "directly", one or more components may be located between the two components.

[0033] When an element or layer is disposed "on" another element or layer, another layer or another element may be directly disposed on the other element or between them.

[0034] Although terms such as "first", "second", etc. are used to describe various components, these components are not limited by these terms. These terms are only used to distinguish one component from another. Therefore, in the technical concept of the present disclosure, the first component mentioned below may be the second component.

[0035] Throughout the specification, like reference numerals generally denote like elements.

[0036] For ease of description, the dimensions and thicknesses of each component shown in the accompanying drawings are shown, and the present disclosure is not limited to the dimensions and thicknesses of the components shown.

[0037] The features of the various embodiments of the present disclosure may be combined or combined partially or wholly with each other, and may be interlocked and operated in various technical ways, and the embodiments may be implemented independently of each other or in relation to each other.

[0038] Hereinafter, various exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0039] Figures 1 to 3 is a view for explaining a foldable display device according to an exemplary embodiment of the present disclosure.

[0040] Figure 1 is a schematic perspective view of a foldable display device according to an exemplary embodiment of the present disclosure. Figure 2 is a schematic side view showing a folded shape of a foldable display device according to an exemplary embodiment of the present disclosure. Figure 3 is along Figure 1 a schematic cross-sectional view taken along line I-I'.

[0041] The foldable display device 100 according to an exemplary embodiment of the present disclosure includes a display panel 110, a polarizing film 120, a cover window 130, a backplane 140, and a support substrate 150.

[0042] Referring to Figure 1 and Figure 2 , the foldable display device 100 according to an exemplary embodiment of the present disclosure includes a display area DA and a non-display area NDA. The display area DA is an area where a plurality of pixels are provided to substantially display an image. The non-display area NDA surrounds the display area DA. The non-display area NDA is an area where an image is not substantially displayed and various wirings for driving the pixels and driving circuits provided in the display area DA, driving ICs, printed circuit boards, etc. are provided therein. For example, in the non-display area NDA, various driving ICs such as a gate driver IC and a data driver IC, a VSS line, etc. may be provided.

[0043] Referring to Figure 1 and Figure 2 , the foldable display device 100 according to an exemplary embodiment of the present disclosure includes a first non-folded area NFA1, a first folded area FA1, a second non-folded area NFA2, a second folded area FA2, and a third non-folded area NFA3 sequentially positioned along the folding direction (X-axis direction). The first folded area FA1 and the second folded area FA2 are areas that are folded when the foldable display device 100 is folded, and may include a part of the display area DA and a part of the non-display area NDA. In Figure 1 and Figure 2In the example, although it is described that both the first folding region FA1 and the second folding region FA2 include a part of the display region DA and a part of the non-display region NDA, it is not limited thereto, such that the non-display region NDA may be located only in a partial region outside the display region DA. Therefore, the first folding region FA1 and the second folding region FA2 may include only a part of the display region DA.

[0044] The first folding region FA1 and the second folding region FA2 are regions that are folded when the foldable display device 100 is folded, such that the first folding region FA1 and the second folding region FA2 can be folded along a specific radius of curvature with respect to the folding direction, that is, with respect to Figure 1 the X-axis direction. When the first folding region FA1 and the second folding region FA2 are respectively folded with respect to the folding direction (X-axis direction), the first folding region FA1 and the second folding region FA2 can form a part of a circle or an ellipse. At this time, the radius of curvature of each of the first folding region FA1 and the second folding region FA2 refers to the radius corresponding to the part of the circle or the ellipse formed by the first folding region FA1 and the second folding region FA2, respectively.

[0045] When the foldable display device 100 is folded, the first non-folding region NFA1, the second non-folding region NFA2, and the third non-folding region NFA3 are not folded. That is, when the foldable display device 100 is folded, the first non-folding region NFA1, the second non-folding region NFA2, and the third non-folding region NFA3 remain flat. The first non-folding region NFA1, the second non-folding region NFA2, and the third non-folding region NFA3 may include a part of the display region DA and a part of the non-display region NDA. When the first folding region FA1 and the second folding region FA2 are folded with respect to the folding direction, the first non-folding region NFA1, the second non-folding region NFA2, and the third non-folding region NFA3 overlap. The top surface of the foldable display device 100 on which an image is displayed is defined as the display surface 100a, and the bottom surface of the foldable display device 100, which is the opposite surface of the display surface, is defined as the rear surface 100b. In this case, in the first folding region FA1, an inward folding is performed such that the display surfaces 100a of the display panels face each other, and in the second folding region FA2, an outward folding is performed such that the display surfaces 100a of the display panels are exposed to the outside.

[0046] Refer to Figure 2, the first folding region FA1 is folded inward such that the display surface 100a faces inward, thereby setting the display surface 100a of the first non-folding region NFA1 and the display surface 100a of the second non-folding region NFA2 to face each other. In addition, the second folding region FA2 is folded outward such that the display surface 100a faces outward, thereby folding the rear surface 100b of the third non-folding region NFA3 and the rear surface 100b of the second non-folding region NFA2 to face each other. As Figure 2 shown, when the first folding region FA1 and the second folding region FA2 are folded, the radius of curvature of the second folding region FA2 can be greater than the radius of curvature of the first folding region FA1. By doing so, other components including a battery can be provided between the rear surface 100b of the third non-folding region NFA3 and the rear surface 100b of the second non-folding region NFA2.

[0047] Figure 3 is a schematic cross-sectional view of the foldable display device taken along the line I-I’ of Figure 1 .

[0048] Referring to Figure 3 , the foldable display device 100 according to an exemplary embodiment of the present disclosure includes a display panel 110, a polarizing film 120, a cover window 130, a backplane 140, and a support substrate 150. The display panel 110 implements an image, the polarizing film 120 polarizes light emitted from the display panel 110, the cover window 130 protects the display panel 110, and the backplane 140 supports the display panel 110. The support substrate 150 includes a plurality of opening patterns provided to correspond to the first folding region FA1 and the second folding region FA2.

[0049] At this time, for ease of description, the directions in the drawing are defined. On the premise that the display surface 100a of the foldable display device 100 faces forward, the polarizing film 120 and the cover window 130 are positioned toward the display surface 100a of the foldable display device 100. In addition, the backplane 140 and the support substrate 150 are positioned toward the rear surface 100b of the foldable display device 100. Each component is attached by means of adhesive layers 160a, 160b, and 160c.

[0050] The display panel 110 is a panel in which an image is implemented. A display element for implementing an image and a circuit unit for driving the display element can be provided in the display panel. For example, when the foldable display device 100 is an organic light emitting display device, the display element may include an organic light emitting diode. Hereinafter, for ease of description, it is assumed that the foldable display device 100 according to various exemplary embodiments of the present disclosure is a foldable display device including an organic light emitting diode, but the present disclosure is not limited thereto.

[0051] The circuit unit may include various thin film transistors, capacitors, wirings, driving ICs, etc. for driving the organic light emitting diodes. For example, the circuit unit may include various configurations such as driving thin film transistors, switching thin film transistors, storage capacitors, gate lines, data lines, gate driver ICs, and data driver ICs, but is not limited thereto.

[0052] In the display panel 110, the flexible substrate on which the driving thin film transistors and the light emitting diodes are formed is encapsulated by the encapsulation unit to achieve flexibility. The display panel 110 includes a flexible substrate having an extremely thin thickness and display elements provided on the flexible substrate.

[0053] The flexible substrate may be formed of an insulating material having flexibility. For example, it may be an insulating plastic substrate selected from polyimide, polyethersulfone, polyethylene terephthalate, and polycarbonate.

[0054] The polarizing film 120 is disposed on the display panel 110. The polarizing film 120 polarizes the light emitted from the display panel 110 at a polarization angle. The polarizing film 120 emits the light polarized at the polarization angle to the outside. The polarizing film 120 may include a function of blocking the reflection of light other than the light polarized at the polarization angle in the external light.

[0055] To protect the display panel 110 from external impacts and suppress damages such as scratches, a cover window 130 is provided above the display panel 110. The cover window 130 may be implemented by a foldable soft plastic-based cover to ensure the thin thickness and flexibility of the foldable display device 100.

[0056] In addition, a touch panel forming a touch sensor may be selectively provided between the display panel 110 and the cover window 130 as needed.

[0057] The support substrate 150 for supporting the display panel 110 is disposed on the rear surface of the display panel 110. The support substrate 150 supports the flexible substrate configuring the display panel 110 so that it does not sag, and protects the components provided on the flexible substrate from external moisture, heat, and impacts.

[0058] The support substrate 150 may be referred to as a bottom plate. The support substrate 150 may be formed of stainless steel (SUS), stainless steel (SUS) containing other metals such as nickel (Ni), or a metallic material such as iron (Fe), aluminum (Al), or magnesium (Mg). Desirably, stainless steel (SUS) may be applied to the support substrate 150. For example, stainless steel SUS has high resilience and stiffness, such that even when the thickness of the support substrate 150 is reduced, high stiffness can be maintained. Accordingly, while supporting the display panel 110, the support substrate 150 reduces the overall thickness of the foldable display device 100 to reduce the radius of curvature of the first folding region FA1 and the second folding region FA2. However, the support substrate 150 is not limited thereto and may be formed of a polymer such as polymethyl methacrylate (PMMA), polycarbonate (PC), polyvinyl alcohol (PVA), acrylonitrile-butadiene-styrene (ABS), polyethylene terephthalate (PET), silicone resin, or polyurethane (PU).

[0059] In addition, according to an exemplary embodiment of the present disclosure, a back plate 140 that supports the display panel 110 together with the support substrate 150 may be included between the display panel 110 and the support substrate 150, and may be referred to as a top plate. When the foldable display device 100 is multi-folded, the back plate 140 may keep the curvature of the display panel 110 constant and suppress creases generated on the top surface of the display panel 110. In addition, the back plate 140 is disposed between the display panel 110 and the support substrate 150 to suppress the transferring or deformation of the display surface caused by a plurality of opening patterns of the support substrate 150 that are disposed to correspond to the first folding region FA1 and the second folding region FA2.

[0060] Referring again to Figure 3 , the support substrate 150 for the foldable display device 100 according to an exemplary embodiment of the present disclosure may include a plurality of opening patterns 151 and 152 that are disposed to correspond to the first folding region FA1 and the second folding region FA2, respectively. Specifically, a plurality of first opening patterns 151 disposed in the first folding region FA1 and a plurality of second opening patterns 152 disposed in the second folding region FA2 may be included. Each of the plurality of first opening patterns 151 and the plurality of second opening patterns 152 helps the support substrate 150 to be easily folded in the first folding region FA1 and the second folding region FA2, and then to be easily restored after folding, thereby improving the folding performance of the foldable display device 100.

[0061] According to an exemplary embodiment of the present disclosure, the widths of the plurality of first opening patterns 151 and the plurality of second opening patterns 152 respectively corresponding to the first folding region FA1 and the second folding region FA2 may be equal to each other. That is, the widths of the plurality of first opening patterns 151 provided in the first folding region FA1 are equal to each other, and the widths of the plurality of second opening patterns 152 provided in the second folding region FA2 are equal to each other.

[0062] At this time, the width of the second folding region FA2 folded outward may be greater than the width of the first folding region FA1 folded inward. Referring together to Figure 2 , the first folding region FA1 is folded inward so that the display surface 100a of the foldable display device 100 is accommodated inward. In contrast, the second folding region FA2 is folded outward so that the display surface 100a of the foldable display device 100 is opened to the outside, thereby applying a relatively higher stress to the second folding region FA2 than to the first folding region FA1.

[0063] Therefore, the number of the plurality of second opening patterns 152 included in the second folding region FA2 to which a relatively higher stress will be applied is increased to be more than the number of the plurality of first opening patterns 151 included in the first folding region FA1. By doing so, the width of the second folding region FA2 is formed to be greater than the width of the first folding region FA1, so that when stress is generated due to multiple folding, the strain in the second folding region FA2 increases to easily relieve the stress.

[0064] Hereinafter, the plurality of first opening patterns and the plurality of second opening patterns formed on the support substrate according to another exemplary embodiment of the present disclosure will be described in more detail with reference to Figures 4A to 6B FIGS.

[0065] Figure 4A and Figure 4B are a schematic cross-sectional view and a plan view showing an example of a support substrate configuring a foldable display device according to another exemplary embodiment of the present disclosure.

[0066] Referring to Figure 4A and Figure 4B , the plurality of first opening patterns 151 provided in the first folding region FA1 and the plurality of second opening patterns 152 provided in the second folding region FA2 each have a rectangular shape extending longitudinally in the y-axis direction. That is, in each of the plurality of first opening patterns 151 and the plurality of second opening patterns 152, the width in the folding direction (X-axis direction) is less than the length in the direction perpendicular to the folding direction (Y-axis direction).

[0067] Referring to Figure 4B, a plurality of opening patterns 151 and 152 formed in the first folding region FA1 and the second folding region FA2 are arranged to be spaced apart from each other at the same interval s1 in the folding direction (X-axis direction). Specifically, the plurality of opening patterns 151 and 152 formed in the first folding region FA1 and the second folding region FA2 are arranged in a zigzag pattern in the folding direction (X-axis direction).

[0068] According to an exemplary embodiment of the present disclosure, the plurality of first opening patterns 151 provided in the first folding region FA1 and the plurality of second opening patterns 152 provided in the second folding region FA2 may have different sizes according to their positions in the folding regions FA1 and FA2. Specifically, the opening patterns included in the plurality of first opening patterns 151 and the plurality of second opening patterns 152 provided in the first folding region FA1 and the second folding region FA2, respectively, may have different widths w and lengths h according to their positions in the folding regions FA1 and FA2. In addition, the interval s1 between the opening patterns in the folding direction (X-axis direction) and the interval s2 between the opening patterns in the direction perpendicular to the folding direction (Y-axis direction) may be different.

[0069] According to an exemplary embodiment of the present disclosure, among the plurality of first opening patterns 151, the width of the opening pattern 151a adjacent to the first non-folding region NFA1 may be smaller than the width of the opening pattern 151b adjacent to the second non-folding region NFA2. That is, the width w of the plurality of first opening patterns 151 provided in the first folding region FA1 may gradually increase from the direction adjacent to the first non-folding region NFA1 to the direction adjacent to the second non-folding region NFA2. In addition, among the plurality of second opening patterns 152, the width of the opening pattern 152a adjacent to the second non-folding region NFA2 is smaller than the width of the opening pattern 152b adjacent to the third non-folding region NFA3. That is, the width w of the plurality of second opening patterns 152 provided in the second folding region FA2 may gradually increase from the direction adjacent to the second non-folding region NFA2 to the direction adjacent to the third non-folding region NFA3.

[0070] When a plurality of first opening patterns 151 and a plurality of second opening patterns 152 are formed on the support substrate 150, the greater the stress applied to the region due to folding in the folding direction (X-axis direction), the greater the width w of the opening pattern. By doing so, when stress is generated due to multiple folding in the first folding region FA1 and the second folding region FA2, the strain increases in the opening patterns having a relatively large width w, which reduces the concentration of stress generated due to multiple folding. Therefore, creases generated on the top surface of the display panel can be suppressed.

[0071] For example, when the widths of a plurality of opening patterns formed on a support substrate including a plurality of opening patterns for each of the folding regions FA1 and FA2 are constant, it may not be easy to relieve the stress that will be applied to the support substrate during multiple folding. Specifically, when the widths of the plurality of opening patterns are constant, during multiple folding, creases are generated on the top surface of the display panel with respect to the folding regions, causing damage in components of the display panel such as the encapsulation unit of the display panel. Therefore, there may be a problem of an increase in the defect rate of the display device.

[0072] According to an exemplary embodiment of the present disclosure, the area of the second folding region FA2 that folds outward may be larger than the area of the first folding region FA1 that folds inward. Referring together Figure 2 to, the first folding region FA1 folds inward such that the display surface 100a of the foldable display device 100 is accommodated inward. In contrast, the second folding region FA2 folds outward such that the display surface 100a of the foldable display device 100 is open to the outside, thereby applying a relatively higher stress to the second folding region FA2 than to the first folding region FA1. Therefore, the area of the second folding region FA2 is formed to be larger than the area of the first folding region FA1, and the number and width of the plurality of opening patterns are larger than those of the first folding region FA1, such that the stress in the second folding region FA2 can be more easily relieved.

[0073] Figure 5A and Figure 5B are a schematic cross-sectional view and a plan view showing an example of a support substrate configuring a foldable display device according to another exemplary embodiment of the present disclosure.

[0074] Compared with Figures 1 to 4B the support substrate 150 shown, in Figure 5A and Figure 5B the support substrate 250 shown, the first sub-region SA1 and the second sub-region SA2 are divided according to the pattern shape of the opening patterns included in each of the plurality of first opening patterns 251 and the plurality of second opening patterns 252. However, other than this, Figure 5A and Figure 5B the support substrate 250 shown is substantially the same as Figures 1 to 4B the support substrate 150 shown, and thus redundant descriptions will be omitted.

[0075] Referring to Figure 5A and Figure 5B it is possible to divide each of the first folding region FA1 and the second folding region FA2 of the support substrate 250 according to another exemplary embodiment of the present disclosure into a first sub-region SA1 and a second sub-region SA2 each having a different pattern shape.

[0076] At this time, the first sub-region SA1 and the second sub-region SA2 can be divided with respect to the folding axis. For example, the first folding region FA1 has a first folding axis, and the second folding region FA2 has a second folding axis. Accordingly, the first sub-region SA1 of the first folding region FA1 is adjacent to the first non-folding region NFA1 with respect to the first folding axis, and the second sub-region SA2 of the first folding region FA1 is adjacent to the second non-folding region NFA2 with respect to the first folding axis. In addition, the first sub-region SA1 of the second folding region FA2 having the second folding axis is adjacent to the second non-folding region NFA2 with respect to the second folding axis, and the second sub-region SA2 of the second folding region FA2 is adjacent to the third non-folding region NFA3 with respect to the second folding axis.

[0077] Specifically, when the first folding region FA1 and the second folding region FA2 respectively include the first sub-region SA1 and the second sub-region SA2, the opening patterns 251a and 252a provided in the first sub-region SA1 have the same width, while the opening patterns 251b and 252b provided in the second sub-region SA2 have a gradually increasing width. Specifically, the width of the opening pattern 251b provided in the second sub-region SA2 formed in the first folding region FA1 gradually increases in the direction where the second non-folding region NFA2 is located. In addition, the width of the opening pattern 252b provided in the second sub-region SA2 formed in the second folding region FA2 gradually increases in the direction where the third non-folding region NFA3 is located.

[0078] When the plurality of first opening patterns 251 and the plurality of second opening patterns 252 formed on the support substrate 250 are divided into the first sub-region SA1 and the second sub-region SA2 according to the shape of the opening patterns, the opening patterns 251b and 252b in the second sub-region SA2, which are subjected to greater stress due to folding, are formed to have a gradually increasing width. By doing so, when stress is generated due to folding, the strain of the opening patterns formed in the second sub-region SA2 increases, thereby easily reducing the concentration of stress caused by folding. In contrast, the opening patterns 251a and 252a in the first sub-region SA1, which are subjected to less stress due to folding, are formed to have a constant width, so that when stress is generated due to folding, the strain of the opening patterns formed in the first sub-region SA1 is maintained. Therefore, the strain in the plurality of first opening patterns 251 and the plurality of second opening patterns 252 can be adjusted so as not to increase excessively. Figure 6A and Figure 6B are a schematic cross-sectional view and a plan view showing an example of a support substrate of a foldable display device configured according to another exemplary embodiment of the present disclosure.

[0079] Figure 6A and Figure 6BFIG. is a cross-sectional view and a plan view of a support substrate 350 according to another exemplary embodiment of the present disclosure. Except for the number of the plurality of first opening patterns 351 and the plurality of second opening patterns 352, Figure 6A and Figure 6B the support substrate 350 shown is substantially the same as the support substrate 250 shown in Figure 5A and Figure 5B so redundant description will be omitted.

[0080] Referring to Figure 6A and Figure 6B , the width of the second sub-region SA2 can be greater than the width of the first sub-region SA1 with respect to the folding axis in the support substrate 350. For example, while maintaining the number of the opening patterns 351a and 352a included in the first sub-region SA1, the number of the opening patterns 351b and 352b included in the second sub-region SA2 is increased so that the width of the second sub-region SA2 can be formed to be greater than the width of the first sub-region SA1. The number of the opening patterns 351b and 352b included in the second sub-region SA2 is increased so that the area of the second sub-region SA2, where more stress is applied due to folding, is formed to be larger. Therefore, when stress is generated due to multiple folding, the strain in the second sub-region SA2 increases to relieve the stress.

[0081] Figure 7 FIG. is a schematic cross-sectional view showing an example of a support substrate of a foldable display device 400 according to another exemplary embodiment of the present disclosure. Except that a coating 470 is further included on the surface of the support substrate 150, Figure 7 the foldable display device 400 shown is substantially the same as the foldable display device 100 shown in Figures 1 to 4B so redundant description will be omitted.

[0082] Referring to Figure 7 , a foldable display device 400 according to another exemplary embodiment of the present disclosure may further include a coating 470 provided on the support substrate 150. The coating 470 can be used to supplement the stress relief function achieved by folding the support substrate 150. At this time, referring to Figure 2 together, the first folding region FA1 is folded inward to be accommodated in the display panel 110, and the second folding region FA2 is folded outward so that the display panel 110 is opened to the outside. Therefore, the second folding region FA2 folded outward needs greater impact resistance than the first folding region FA1 folded inward.

[0083] At this time, the coating 470 includes a first coating 471 formed on the support substrate 150 with a first thickness D1 and a second coating 473 formed on the first coating 471 with a second thickness D2 corresponding to the second folding region FA2.

[0084] At this time, a second coating 473 corresponding to the second folding region FA2 may be formed to cover a region opened after the second folding region FA2 is folded outward. That is, the second coating 473 may be formed not only in the second folding region FA2, but also in a part of the second non-folding region NFA2 and the third non-folding region NFA3.

[0085] To form the second coating 473, when forming the coating 470, the second coating 473 may be coated after patterning so that a region corresponding to the second folding region FA2 is formed to be thicker than a region corresponding to the first folding region FA1, or the second coating 473 may be laminated on the first coating 471 using an adhesive.

[0086] At this time, the first coating 471 and the second coating 473 may be formed of the same material or different materials. For example, when the first coating 471 and the second coating 473 are formed of the same material, stress on the strain-supporting substrate 150 due to the coating 470 during multiple folding in the first folding region FA1 and the second folding region FA2 can be easily reduced. In addition, when the first coating 471 and the second coating 473 are formed of different materials, a material with excellent durability is applied to the second coating 473 to increase the durability of the second folding region FA2, and thus stress on the supporting substrate 150 can be easily reduced.

[0087] For example, the first coating 471 and the second coating 473 may include at least any one selected from the group consisting of silicon, silicon foam, polyurethane, and polyurethane foam, but are not limited thereto.

[0088] Referring together to Figure 3 and Figure 7 , the sum of the thickness D1 of the first coating 471 and the thickness D2 of the second coating 473 located in the second folding region FA2 may be less than the sum of the thickness of the supporting substrate 150 and the thickness of the adhesive layer 160c included to bond the supporting substrate 150 to the display panel 110.

[0089] Figure 8 is a schematic cross-sectional view showing an example of a supporting substrate of a foldable display device configured according to still another exemplary embodiment of the present disclosure. Except for the shape of the coating 570, Figure 8 the foldable display device 500 shown is Figure 7 substantially the same as the foldable display device 400 shown, and thus redundant descriptions will be omitted.

[0090] Referring to Figure 8 , a supporting substrate 150 according to still another exemplary embodiment of the present disclosure may include a coating 570 on the supporting substrate 150.

[0091] The coating layer 570 includes a first coating layer 571, a second coating layer 573, and a third coating layer 575. The first coating layer 571 is formed on the support substrate 150 with a first thickness D1, and the second coating layer 573 is formed on the first coating layer 571 with a second thickness D2 corresponding to the second folding region FA2. In addition, the third coating layer 575 is formed on the first coating layer 571 with a third thickness D3 corresponding to the first folding region FA1.

[0092] At this time, the first coating layer 571 and the third coating layer 575 may be formed of the same material. Specifically, the first coating layer 571 and the third coating layer 575 are formed of the same material so that the stress of the support substrate 150 due to the strain of the coating layer 570 during multiple folding in the first folding region FA1 and the second folding region FA2 can be easily reduced. For example, the first coating layer 571 and the third coating layer 575 may include at least any one selected from the group consisting of silicon, silicon foam, polyurethane, and polyurethane foam, but are not limited thereto.

[0093] Meanwhile, the second coating layer 573 is formed of a metal layer to enhance the impact resistance in the second folding region FA2 that folds outward and suppress the generation of creases. For example, the second coating layer 573 may be formed of stainless steel (SUS), stainless steel (SUS) containing other metals such as nickel (Ni), or a metal material such as iron (Fe), aluminum (Al), or magnesium (Mg).

[0094] The second coating layer 573 formed with the second thickness D2 on the region of the first coating layer 571 corresponding to the second folding region FA2 and the third coating layer 575 formed with the third thickness D3 on the region of the first coating layer 571 corresponding to the first folding region FA1 may have the same thickness. At this time, the second coating layer 573 formed to correspond to the second folding region FA2 may be formed not only in the second folding region FA2 but also in a part of the second non-folding region NFA2 and the third non-folding region NFA3 to cover the region opened after the second folding region FA2 folds outward. In addition, in the region outside the region where the second coating layer 573 is formed on the first coating layer 571, the third coating layer 575 formed with the third thickness D3 may be formed to have the same thickness as the second coating layer 573. Therefore, no step is generated in the region where the coating layer 570 is located, so that when applying the coating layer 570, lamination with the display panel 110 can be more easily performed.

[0095] Figure 9 It is a schematic cross-sectional view showing an example of a support substrate of a foldable display device configured according to still another exemplary embodiment of the present disclosure.

[0096] Except for the shape of the plurality of opening patterns, Figure 9 the shown support substrate 650 is the same asFigures 1 to 4B The support substrate 150 shown is substantially the same, so redundant descriptions will be omitted.

[0097] Referring to Figure 9 , a support substrate 650 according to another exemplary embodiment of the present disclosure includes a plurality of first opening patterns 651 provided in a first folding region FA1 and a plurality of second opening patterns 652 provided in a second folding region FA2. At this time, the cross-sectional shape of the plurality of first opening patterns 651 has an inverted conical shape in which the width gradually increases toward the top surface of the support substrate 650. In addition, the cross-sectional shape of the plurality of second opening patterns 652 has a conical shape in which the width gradually decreases toward the top surface of the support substrate 650. Therefore, according to the exemplary embodiment of the present disclosure, when multiple folds are performed in the first folding region FA1 and the second folding region FA2, empty spaces are not formed between the opening patterns, thereby further improving the impact resistance.

[0098] Hereinafter, the effects of the present disclosure will be described in more detail with reference to exemplary embodiments and comparative embodiments. However, the following exemplary embodiments are set forth to illustrate the present disclosure, but the scope of the present disclosure is not limited thereto.

[0099] To find out the effects of the present disclosure, the widths w of the plurality of opening patterns included in the second folding region FA2 formed on the support substrate of the multi-foldable foldable display device as shown in Figure 4A and Figure 4B change as shown in Table 1 below, along with the intervals s1 between the respective opening patterns in the folding direction (X-axis direction). However, the length h of the opening patterns and the intervals s2 between the respective opening patterns in the direction perpendicular to the folding direction (Y-axis direction) remain the same. By doing so, the maximum stress (Max.Stress) and the maximum strain (Max.Strain) in the second folding region FA2 that is folded outward are measured and shown in Table 1 below.

[0100] [Table 1]

[0101]

[0102] As shown in Table 1, compared with the comparative embodiment in which the widths of the plurality of opening patterns in the second folding region FA2 remain unchanged, in the example where the widths w of the plurality of opening patterns in the second folding region FA2 gradually change from 120 μm (151a) to 160 μm (151b), it is confirmed that the maximum stress is low.

[0103] Meanwhile, it was also confirmed that the maximum strain in the exemplary embodiments of the present disclosure is relatively low. When the maximum strain is too high as in the comparative embodiment, the radius of curvature increases, so that the area of the display panel exposed to the outside in the outward folding region increases, which may reduce the impact resistance. Therefore, according to the exemplary embodiments of the present disclosure, as shown in Table 1, while reducing the maximum stress, deformation is likely to occur, and the maximum strain that does not degrade the impact resistance can be ensured.

[0104] The exemplary embodiments of the present disclosure can also be described as follows:

[0105] According to an aspect of the present disclosure, a foldable display device includes a first non-folding region, a first folding region, a second non-folding region, a second folding region, and a third non-folding region sequentially positioned along a folding direction. The foldable display device includes: a display panel; and a support substrate that supports the display panel below the display panel and includes a plurality of opening patterns provided to correspond to the first folding region and the second folding region. Among them, the first folding region is folded inward so that the display surface of the display panel faces inward, and the second folding region is folded outward so that the display surface of the display panel faces outward. At least some of the widths of the plurality of opening patterns provided in the first folding region gradually increase in the direction of the second non-folding region, and at least some of the widths of the plurality of opening patterns provided in the second folding region gradually increase in the direction of the third non-folding region.

[0106] The radius of curvature of the second folding region may be greater than the radius of curvature of the first folding region.

[0107] The plurality of opening patterns may be provided to be spaced apart from each other at a constant interval along the folding direction. Each of the first folding region and the second folding region may include a first sub-region and a second sub-region. The opening patterns provided in the first sub-region have the same width, and the width of the opening patterns provided in the second sub-region gradually increases.

[0108] The first folding region may have a first folding axis, and the second folding region may have a second folding axis. The first sub-region of the first folding region may be adjacent to the first non-folding region with respect to the first folding axis, and the second sub-region of the first folding region may be adjacent to the second non-folding region with respect to the first folding axis. The first sub-region of the second folding region may be adjacent to the second non-folding region with respect to the second folding axis, and the second sub-region of the second folding region may be adjacent to the third non-folding region with respect to the second folding axis.

[0109] The width of the second sub-region may be greater than the width of the first sub-region.

[0110] The foldable display device may further include a coating provided on the support substrate, wherein the coating includes a first coating formed on the support substrate with a first thickness and a second coating formed on the first coating with a second thickness and corresponding to the second folding region.

[0111] Each of the first coating and the second coating may include at least any one selected from the group consisting of silicon, silicon foam, polyurethane, and polyurethane foam.

[0112] The first coating and the second coating may be formed of the same material.

[0113] The foldable display device may further include a coating provided on the support substrate, wherein the coating includes a first coating formed on the support substrate with a first thickness, a second coating formed on the first coating with a second thickness and corresponding to the second folding region, and a third coating formed on the first coating with a third thickness and corresponding to the first folding region, and the second coating is a metal layer.

[0114] The second coating and the third coating may have the same thickness.

[0115] The first coating and the third coating may include at least one selected from the group consisting of silicon, silicon foam, polyurethane, and polyurethane foam, and the second coating includes at least one metal selected from the group consisting of stainless steel, nickel, iron, aluminum, and magnesium.

[0116] A plurality of opening patterns may be arranged in a zigzag pattern along the folding direction.

[0117] The width of each opening pattern in the plurality of opening patterns along the folding direction may be smaller than the length along the direction perpendicular to the folding direction.

[0118] The plurality of opening patterns may include a plurality of first opening patterns provided in the first folding region and a plurality of second opening patterns provided in the second folding region. The cross-sectional shape of the first opening pattern has an inverted conical shape in which the width gradually increases toward the top surface of the support substrate, while the cross-sectional shape of the second opening pattern has a conical shape in which the width gradually decreases toward the top surface of the support substrate.

[0119] The foldable display device may further include a backplane formed on the support substrate.

[0120] According to another aspect of the present disclosure, a foldable display device includes a first non-foldable region, a first foldable region, a second non-foldable region, a second foldable region, and a third non-foldable region sequentially positioned along a folding direction. The foldable display device includes: a display panel; and a support substrate that supports the display panel below the display panel and includes a plurality of opening patterns provided to correspond to the first foldable region and the second foldable region. Among them, the first foldable region is folded inward so that the display surface of the display panel faces inward, while the second foldable region is folded outward so that the display surface of the display panel faces outward, and the plurality of opening patterns in the first foldable region have the same width, and the plurality of opening patterns in the second foldable region have the same width.

[0121] The width of the second foldable region may be greater than the width of the first foldable region.

[0122] Although the exemplary embodiments of the present disclosure have been described in detail with reference to the accompanying drawings, the present disclosure is not limited thereto and can be implemented in many different forms without departing from the technical concept of the present disclosure. Therefore, the provision of the exemplary embodiments of the present disclosure is for illustrative purposes only and is not intended to limit the technical concept of the present disclosure. The scope of the technical concept of the present disclosure is not limited thereto. Therefore, it should be understood that the above exemplary embodiments are illustrative in all respects and do not limit the present disclosure. The protection scope of the present disclosure should be interpreted based on the appended claims, and all technical concepts within the equivalent scope thereof should be interpreted as falling within the scope of the present disclosure.

Claims

1. A foldable display device includes a first non-foldable region, a first foldable region, a second non-foldable region, a second foldable region, and a third non-foldable region sequentially positioned along a folding direction. The foldable display device comprises: a display panel; and a support substrate that supports the display panel below the display panel and includes a plurality of first opening patterns arranged to correspond to the first foldable region and a plurality of second opening patterns arranged to correspond to the second foldable region, wherein the first foldable region folds inward such that the display surface of the display panel faces inward, and the second foldable region folds outward such that the display surface of the display panel faces outward, and the width of at least some of the opening patterns among the plurality of first opening patterns provided in the first foldable region gradually increases in a direction perpendicular to the folding axis, and the width of at least some of the opening patterns among the plurality of second opening patterns provided in the second foldable region gradually increases in a direction perpendicular to the folding axis.

2. The foldable display device according to claim 1, wherein the radius of curvature of the second foldable region is greater than the radius of curvature of the first foldable region.

3. The foldable display device according to claim 1, wherein the plurality of first opening patterns and the plurality of second opening patterns are arranged to be spaced apart from each other at a constant interval along the folding direction.

4. The foldable display device according to claim 1, wherein each of the first foldable region and the second foldable region includes a first sub-region and a second sub-region. The opening patterns provided in the first sub-region have the same width, while the width of the opening patterns provided in the second sub-region gradually increases.

5. The foldable display device according to claim 4, wherein the first foldable region has a first folding axis, and the second foldable region has a second folding axis. The first sub-region of the first foldable region is adjacent to the first non-foldable region with respect to the first folding axis, and the second sub-region of the first foldable region is adjacent to the second non-foldable region with respect to the first folding axis. And the first sub-region of the second foldable region is adjacent to the second non-foldable region with respect to the second folding axis, and the second sub-region of the second foldable region is adjacent to the third non-foldable region with respect to the second folding axis.

6. The foldable display device according to claim 4, wherein the width of the second sub-region is greater than the width of the first sub-region.

7. The foldable display device according to claim 1, further comprises: a coating provided on the support substrate, wherein the coating includes a first coating formed on the support substrate with a first thickness and a second coating formed on the first coating with a second thickness and corresponding to the second foldable region.

8. The foldable display device according to claim 7, wherein each of the first coating and the second coating includes at least any one selected from the group consisting of silicon, silicon foam, polyurethane, and polyurethane foam.

9. The foldable display device according to claim 7, wherein, the first coating and the second coating are formed of the same material.

10. The foldable display device according to claim 1, further comprising: a coating disposed on the support substrate, wherein the coating includes a first coating formed on the support substrate with a first thickness, a second coating corresponding to the second folding region and formed on the first coating with a second thickness, and a third coating corresponding to the first folding region and formed on the first coating with a third thickness, and the second coating is a metal layer.

11. The foldable display device according to claim 10, wherein, the second coating and the third coating have the same thickness.

12. The foldable display device according to claim 10, wherein, the first coating and the third coating include at least one selected from the group consisting of silicon, silicon foam, polyurethane, and polyurethane foam, and the second coating includes at least one metal selected from the group consisting of stainless steel, nickel, iron, aluminum, and magnesium.

13. The foldable display device according to claim 1, wherein, the plurality of first opening patterns and the plurality of second opening patterns are arranged in a zigzag pattern along the folding direction.

14. The foldable display device according to claim 1, wherein, the width of each opening pattern in the plurality of first opening patterns and the plurality of second opening patterns along the folding direction is less than the length along the direction perpendicular to the folding direction.

15. The foldable display device according to claim 1, wherein, the cross-sectional shape of the first opening pattern has an inverted conical shape with the width gradually increasing toward the top surface of the support substrate, while the cross-sectional shape of the second opening pattern has a conical shape with the width gradually decreasing toward the top surface of the support substrate.

16. The foldable display device according to claim 1, further comprising: a backplane formed on the support substrate.

17. A foldable display device includes a first non-foldable region, a first folding region, a second non-foldable region, a second folding region, and a third non-foldable region sequentially positioned along a folding direction, the foldable display device comprising: a display panel; and a support substrate that supports the display panel below the display panel and includes a plurality of first opening patterns arranged to correspond to the first folding region and a plurality of second opening patterns arranged to correspond to the second folding region. Wherein, the first folding region is folded inward such that the display surface of the display panel faces inward, while the second folding region is folded outward such that the display surface of the display panel faces outward. A first portion of the plurality of first opening patterns in the first folding region has the same width in a direction perpendicular to the folding axis, and the width of a second portion of the plurality of first opening patterns gradually increases in the direction perpendicular to the folding axis. A first portion of the plurality of second opening patterns in the second folding region has the same width in a direction perpendicular to the folding axis, and the width of a second portion of the plurality of second opening patterns gradually increases in the direction perpendicular to the folding axis.

18. The foldable display device according to claim 17, wherein, the width of the second folding region is greater than the width of the first folding region.

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