Flexible display device

Abstract

A flexible display device includes: a display panel configured to display an image; and a support substrate disposed under the display panel and configured to support the display panel. The support substrate includes a plurality of rigid portions extending in a first direction and spaced apart from each other in a second direction perpendicular to the first direction. The support substrate further includes an elastic portion disposed between the plurality of rigid portions. Each of the plurality of rigid portions includes a first side surface and a second side surface. At least one of the first side surface and the second side surface is at least partially curved and includes a first protrusion, a second protrusion, and a recess between the first protrusion and the second protrusion.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10 - 2023 - 0196623, filed with the Korean Intellectual Property Office on December 29, 2023, the disclosure of which is incorporated herein by reference. Technical field

[0003] The present disclosure relates to a display device, and more particularly, to a flexible display device including a plurality of rigid portions and elastic portions. Background art

[0004] Recently, as society develops towards an information society, the field of display devices for visually expressing electronic information signals is rapidly evolving. Accordingly, various display devices having excellent properties such as a thin profile, light weight, and low power consumption have been developed. Examples of display devices include liquid crystal display (LCD) devices, plasma display panel (PDP) devices, field emission display (FED) devices, organic light - emitting display (OLED) devices, and the like.

[0005] Recently, flexible display devices that can display images even when bent, rolled up, or folded have received attention as next - generation display devices. Compared to conventional non - flexible displays, such display panels present unique challenges. For example, bending a display can damage the display's electrical components and have a negative impact on its durability. In addition, due to the stress and strain associated with bending or folding a display, the layers of the display laminate are more likely to separate or break. These problems are more likely to occur in display applications involving multiple repeated folding cycles. Therefore, it is advantageous to have a flexible display that can overcome the above - mentioned and other deficiencies of current solutions. Summary of the invention

[0006] Flexible display devices can be classified into display devices that are not easily broken and have high durability and bendable display devices that can be bent without breaking. In addition, flexible display devices can be classified into rollable display devices that can be rolled up and foldable display devices that can be folded. In addition, flexible display devices can be classified into stretchable display devices that can be stretched and contracted in a specific direction and changed into various shapes. Flexible display devices have good space usability, interiority, and designability, and can be applied to various application fields. A flexible substrate is used as a display panel of the flexible display device. In order to suppress the sagging of the display panel and protect the display panel from foreign substances and impacts from the outside, a support substrate, such as a backplane, can be provided under the display panel.

[0007] In one or more embodiments of the present disclosure, a flexible display device is provided that can effectively disperse the load concentrated on the display panel to improve durability.

[0008] In one or more embodiments of the present disclosure, a stretchable display device is provided that can be bent or stretched without damaging the display panel.

[0009] In one or more embodiments of the present disclosure, a foldable display device is provided that can be folded along one axial direction without damaging the display panel.

[0010] The flexible display device according to an embodiment of the present disclosure includes: a display panel configured to display an image; and a support substrate disposed under the display panel to support the display panel, and including a plurality of rigid portions extending in a first direction and spaced apart from each other in a second direction perpendicular to the first direction, and an elastic portion provided to fill between the plurality of rigid portions. On a plane defined by the first direction and the second direction, two side surfaces of each of the plurality of rigid portions include curved portions having a plurality of protrusions and at least one recess repetitively provided in the first direction.

[0011] According to the present disclosure, the rigidity of the display panel can be enhanced, and the load concentrated on the display panel can be effectively dispersed.

[0012] According to the present disclosure, flexible driving is possible, and sufficient rigidity for supporting the display panel can be achieved and attained.

[0013] According to the present disclosure, when the display device is tensioned, cracks hardly occur. Thus, the display device can be bent or stretched without being damaged.

[0014] Embodiments of the present disclosure are not limited to the above-mentioned embodiments, and other embodiments not mentioned above can be clearly understood by those skilled in the art according to the following description and with reference to the accompanying drawings.

[0015] The benefits and effects according to the present disclosure are not limited to those illustrated above, and the embodiments in this specification achieve more various effects, benefits, and advantages. 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 taken in conjunction with the accompanying drawings, in which:

[0017] Figure 1 is a perspective view schematically showing a flexible display device according to an embodiment of the present disclosure;

[0018] Figure 2 is an enlarged plan view of Region I of the flexible display device according to an embodiment of the present disclosure; Figure 1

[0019] Figure 3 is a cross-sectional view taken along line A-A' of Figure 2 ;

[0020] Figure 4A is a plan view of the support substrate of the flexible display device according to an embodiment of the present disclosure;

[0021] Figure 4B is a cross-sectional view taken along line B-B' of Figure 4A ;

[0022] Figure 4C is a cross-sectional view taken along line C-C' of Figure 4A ;

[0023] Figure 5 is a plan view of the support substrate of the flexible display device according to an embodiment of the present disclosure;

[0024] Figure 6 is a plan view of the support substrate of the flexible display device according to an embodiment of the present disclosure;

[0025] Figure 7 is a plan view of the support substrate of the flexible display device according to an embodiment of the present disclosure;

[0026] Figure 8 is a plan view of the support substrate of the flexible display device according to an embodiment of the present disclosure;

[0027] Figure 9 is a schematic plan view of the flexible display device according to an embodiment of the present disclosure;

[0028] Figure 10 is a cross-sectional view taken along line D-D' of Figure 9 ;

[0029] Figure 11 is a plan view of the support substrate in Region II of Figure 9 according to an embodiment of the present disclosure;

[0030] Figure 12 is a plan view of the support substrate in Region II of Figure 9 according to an embodiment of the present disclosure;

[0031] Figure 13 shows Figure 4A the results of a 5% elongation test simulation of the support substrate shown in ​

[0032] Figure 14 shows Figure 7 the result of a 5% elongation test simulation of the support substrate shown;

[0033] Figure 15A is a plan view of a support substrate according to a comparative example;

[0034] Figure 15B shows the result of a 25% elongation test simulation of the support substrate of this comparative example;

[0035] Figure 15C shows Figure 4A the result of a 25% elongation test simulation of the support substrate shown;

[0036] Figure 15D shows Figure 8 the result of a 25% elongation test simulation of the support substrate shown;

[0037] Figure 16A shows Figure 11 the result of a 5% elongation test simulation of the support substrate shown; and

[0038] Figure 16B shows Figure 12 the result of a 5% elongation test simulation of the support substrate shown. DETAILED DESCRIPTION

[0039] Advantages and features of the present disclosure, and methods for achieving these advantages and features, will be apparent by referring to the embodiments described in detail below together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed herein, but will be implemented in various forms. The embodiments are provided by way of example only, so that those skilled in the art can fully understand the disclosure of the present disclosure and the scope of the present disclosure.

[0040] The shapes, sizes, ratios, angles, numbers, etc. shown in the drawings for describing the embodiments of the present disclosure are merely examples, and the present disclosure is not limited thereto. Throughout the specification, the same reference numerals generally denote the same 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 are generally intended to allow the addition of other components, unless these terms are used together with the term "only". References to the singular generally include the plural unless otherwise expressly stated.

[0041] Even if not explicitly stated, components are interpreted as including a normal error range.

[0042] When terms such as "on," "above," "below," and "adjacent to" are used to describe the positional relationship between two components, one or more components may be positioned between the two components, unless these terms are used together with the terms "immediately" or "directly."

[0043] When an element or layer is disposed "on" another element or layer, the element or layer may be directly on the other element or layer, or there may be other elements or layers interposed therebetween.

[0044] 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 other components. Thus, the first component to be mentioned below may be the second component in the technical concept of the present disclosure.

[0045] Throughout the specification, the same reference numerals generally denote the same elements.

[0046] For convenience of description, the dimensions and thicknesses of each component shown in the drawings are illustrated, and the present disclosure is not limited to the dimensions and thicknesses of the components shown.

[0047] The features of the various embodiments of the present disclosure may be partially or completely attached to or combined with each other, and may be interlocked and operated in various ways technically, and these embodiments may be executed independently or in association with each other.

[0048] Hereinafter, a flexible display device according to one or more embodiments of the present disclosure will be described in detail with reference to the drawings.

[0049] Figure 1 is a schematic perspective view of a flexible display device 100 according to an embodiment of the present disclosure. Figure 2 is a view showing an enlarged plan view of region I of the flexible display device according to an embodiment of the present disclosure Figure 1 of.

[0050] Referring to Figure 1 and Figure 2 , the flexible display device 100 may be a stretchable display device that is stretched or folded along a second direction D2, which means that the dimension (i.e., length or width) along the second direction D2 is greater than the dimension (i.e., length or width) along a first direction D1. The flexible display device 100 may include a display panel 10, a support substrate 110 disposed under the display panel 10, a chip on film (COF) 130, and a printed circuit board 140, and the display panel 10 includes a base substrate 120, a separate substrate 121, and connection lines 150.

[0051] For ease of description, the flexible display device 100 of the present disclosure has been described as a stretchable display device or a foldable display device. However, these are merely examples of flexible display devices and do not limit the types of flexible devices of the present disclosure. The concepts discussed herein can be equivalently applied to any other type of display device, or even other devices beyond the context of display devices.

[0052] The display panel 10 includes a base substrate 120, a separate substrate 121, and connection lines 150.

[0053] The base substrate 120 is used to support and protect various components of the flexible display device 100. The base substrate 120 is a stretchable substrate and can be made of an insulating material that can be bent or stretched. For example, the base substrate 120 can be made of a silicone rubber such as polydimethylsiloxane (PDMS), or an elastomer such as polyurethane (PU). Thus, the base substrate 120 can be flexible, but is not limited thereto.

[0054] The base substrate 120, as a stretchable substrate, can reversibly expand and contract. The base substrate 120 can have a modulus of elasticity of several MPa to several hundred MPa and a tensile fracture rate of 100% or more. The base substrate 120 can have a thickness of 10 μm to 1 mm, but is not limited thereto.

[0055] The base substrate 120 can have a display area AA and a non-display area NA surrounding the display area AA, which also correspond to the display area AA and the non-display area NA of the display panel 10.

[0056] The display area AA is an area where an image is displayed on the flexible display device 100, and display elements and various driving elements for driving the display elements can be provided in the display area AA. The display area AA includes a plurality of pixels, and the plurality of pixels include Figure 2 a plurality of sub-pixels SP_1 best shown in. The plurality of pixels are provided in the display area AA and include a plurality of display elements. Each of the plurality of sub-pixels SP_1 can be connected to various lines. For example, even if not explicitly shown in the figure, each of the plurality of sub-pixels SP_1 can also be connected to various lines, such as gate lines, data lines, high-potential power lines, low-potential power lines, and reference voltage lines.

[0057] The non-display area NA is an area provided adjacent to and surrounding the display area AA. The non-display area NA is an area where no image is displayed, and lines and circuits can be provided in the non-display area NA. For example, a plurality of pads can be provided in the non-display area NA, and these pads can be respectively connected to the plurality of sub-pixels SP_1 in the display area AA.

[0058] A plurality of individual substrates 121 may be disposed on a base substrate 120. The plurality of individual substrates 121 are rigid substrates, which may be spaced apart from each other on the base substrate 120. The plurality of individual substrates 121 may have relatively higher rigidity than the base substrate 120. That is, the base substrate 120 may be more ductile than the plurality of individual substrates 121, and the plurality of individual substrates 121 may be more rigid than the base substrate 120. The individual substrate 121 provides a relatively rigid base or support for the pixels and sub-pixels SP-1. Therefore, the bending or stretching of the display device 100 is mainly achieved by the relatively plastic base substrate 120, particularly by the region of the base substrate 120 located between the individual substrates 121. Under similar loads, the individual substrates 121 will not deform or will deform less than the base substrate 120 to protect the sub-pixels SP-1 and avoid damage to them due to bending or stretching.

[0059] The individual substrate 121 may be made of a flexible plastic material. For example, the plurality of individual substrates 121 may be made of polyimide (PI), polyacrylate, or polyacetate, etc. However, the material of the individual substrate 121 is not limited thereto.

[0060] The plurality of individual substrates 121 may have a higher modulus than the base substrate 120. The modulus is the elastic modulus representing the ratio of the stress applied to the substrate to the deformation of the substrate caused by the stress. When the modulus is relatively high, the rigidity may be relatively high. Therefore, the plurality of individual substrates 121 may be a plurality of rigid substrates that are more rigid than the base substrate 120. The modulus of the plurality of individual substrates 121 may be 1000 times that of the base substrate 120, but is not limited thereto.

[0061] The connection lines 150 may be disposed between the plurality of individual substrates 121 and connected to the base substrate 120 of the plurality of individual substrates 121.

[0062] The connection lines 150 may be disposed between the disks disposed on the plurality of individual substrates 121 and may electrically connect the disks. Other details of the connection lines 150 will be described below.

[0063] The support substrate 110 is disposed under the display panel 10 to support the display panel 10. Other details of the support substrate 110 will be described below.

[0064] The COF 130 is a film having various components or integrated circuits formed on a stretchable base film 131. The COF 130 is configured to supply signals to a plurality of sub-pixels SP-1 in the display area AA. The COF 130 can be bonded to a plurality of disks provided in the non-display area NA of the base substrate 120 and / or the display panel 10, and can supply a power voltage, a data voltage, a gate voltage, etc. to the plurality of sub-pixels SP-1 in the display area AA through the disks. The COF 130 includes a base film 131 and a driver IC 132. In addition, the COF 130 can include various other components.

[0065] The base film 131 is a layer that supports the driver IC 132 of the COF 130. The base film 131 can be made of an insulating material. For example, the base film 131 can be made of a flexible insulating material, which includes the materials described herein or other materials.

[0066] The driver IC 132 is configured to process data for displaying an image and drive signals for processing the data. Figure 1 The installation of the driver IC 132 in the type of the COF 130 is shown, but the present disclosure is not limited thereto. The driver IC 132 can be installed by a Chip On Glass (COG) method, a Tape Carrier Package (TCP) method, or the like.

[0067] Controllers such as IC chips and circuits can be installed on the printed circuit board 140. Although not shown in the figure, a memory, a processor, etc. can also be installed on the printed circuit board 140. The printed circuit board 140 sends signals for driving display elements from the controller to the display elements.

[0068] The printed circuit board 140 is connected to the COF 130, and thus can be electrically connected to the plurality of sub-pixels SP-1 on the plurality of individual substrates 121.

[0069] Hereinafter, with continued reference to Figure 1 and Figure 2 will refer to Figure 3 The flexible display device 100 according to one or more embodiments of the present disclosure will be described in more detail.

[0070] Figure 3 is a cross-sectional view taken along line A-A' in the stretchable display device 100 shown in the indication Figure 2 which provides more details of the structure of one sub-pixel among the plurality of sub-pixels SP-1.

[0071] Specifically, for ease of description, Figure 3Shows a part of the cross-sectional structure of one of the red sub-pixel, green sub-pixel, and blue sub-pixel. The structure of the other sub-pixels SP-1 may be similar, unless otherwise stated.

[0072] Referring to Figure 3 and continuing to refer to Figure 1 and Figure 2 A buffer layer 161 is provided on a plurality of individual substrates 121. That is, the buffer layer 161 may be provided only in the area overlapping with the plurality of individual substrates 121. The buffer layer 161 may be made of an inorganic insulating material such as silicon nitride (SiNx), silicon oxide (SiOx), and silicon oxynitride (SiON). Therefore, when the flexible display device 100 is stretched, the buffer layer 161 may be more easily damaged, such as cracked. Therefore, the buffer layer 161 is patterned into the shape of the plurality of individual substrates 121 and is not provided between the plurality of individual substrates 121. Therefore, the buffer layer 161 may be provided only on the plurality of individual substrates 121. In some embodiments, due to a change in the composition or properties of the buffer layer 161, a buffer layer 161 is provided between the substrates 121. The same applies to any other layer that is only located on the individual substrate 121 described below.

[0073] A thin-film transistor TFT including a gate electrode GE, an active layer ACT, a source electrode SE, and a drain electrode DE is provided on the buffer layer 161. Herein, the gate insulating layer 162 and the interlayer insulating layer 163 are patterned and provided only in the area overlapping with the plurality of individual substrates 121. Similar to the buffer layer 161, the gate insulating layer 162 and the interlayer insulating layer 163 may also be made of an inorganic insulating material. Therefore, when the flexible display device 100 is stretched, the gate insulating layer 162 and the interlayer insulating layer 163 may also be easily damaged, such as cracked. Therefore, the gate insulating layer 162 and the interlayer insulating layer 163 are patterned into the shape of the plurality of individual substrates 121 and are not provided between the plurality of individual substrates 121. Therefore, the gate insulating layer 162 and the interlayer insulating layer 163 may be provided only on the plurality of individual substrates 121.

[0074] A gate pad 171 is provided on the gate insulating layer 162. The gate pad 171 is used to send a gate signal to a plurality of sub-pixels. The gate pad 171 may be made of the same material as the gate electrode GE, but is not limited thereto.

[0075] An outer coating 164 may be provided on the thin-film transistor TFT, and the outer coating 164 may be provided only on the plurality of individual substrates 121. The outer coating 164 may include contact holes for electrically connecting the thin-film transistor TFT to the anode AND, contact holes for electrically connecting the data pad 173 to the source electrode SE, and contact holes for electrically connecting the connection pad 172 to the gate pad 171.

[0076] The data disk 173, the connection disk 172, and the organic light-emitting diode OLED may be disposed on the outer coating 164.

[0077] The data disk 173 may transmit data signals from the second connection line 152 serving as a data line to a plurality of sub-pixels. The data disk 173 is connected to the source electrode SE of the thin film transistor TFT through a contact hole formed in the outer coating 164.

[0078] The connection disk 172 may transmit a gate signal from the first connection line 151 serving as a gate line to a plurality of sub-pixels SP_1. The connection disk 172 is connected to the gate disk 171 through contact holes formed in the outer coating 164 and the interlayer insulating layer 163, and transmits the gate signal to the gate disk 171.

[0079] The organic light-emitting diode OLED is disposed corresponding to each of the plurality of sub-pixels.

[0080] For ease of description, Figure 3 not all components of the sub-pixel SP-1 are shown. The organic light-emitting diode OLED may include an anode AND, a hole injection layer HIL, a hole transport layer HTL, an emission layer EML, an electron transport layer ETL, an electron injection layer EIL, and a cathode CTD.

[0081] The anode AND is used to provide holes to the emission layer EML and is made of a conductive material having a high work function. The anode AND may be a transparent conductive layer made of a transparent conductive oxide (TCO). For example, the anode AND may be made of one or more selected from transparent conductive oxides, such as indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), tin oxide (SnO2), zinc oxide (ZnO), indium copper oxide (ICO), and aluminum: zinc oxide (Al:ZnO; AZO). However, the present disclosure is not limited thereto.

[0082] The hole injection layer HIL for injecting holes provided from the anode AND into the emission layer EML is disposed on the anode AND. The hole injection layer HIL is made of a material for improving the interface characteristics between the anode AND and the hole transport layer HTL and enabling holes to be smoothly injected into the emission layer EML.

[0083] For example, the hole injection layer HIL can be made of one or more compounds selected from a group including: poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), dipyrazino[2,3-f:2′3′-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile (HAT-CN), phthalocyanine (CuPc), N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-2,2′-dimethylbenzidine (NPD), etc., but not limited thereto.

[0084] A hole transport layer HTL for smoothly transferring holes from the hole injection layer HIL to the emission layer EML can be disposed on the hole injection layer HIL.

[0085] For example, the hole transport layer HTL can be selected from the group including the following: N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (TPD), NPD, MTDATA, 1,3-bis(N-carbazolyl)benzene (mCP), CuPC, TCTA, tris(trifluorovinyl ether)-tris(4-carbazol-9-yl-phenyl)amine (TFV-TCTA), tris[4-(diethylamino)phenyl]amine, N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluorene-2-amine, tris-p-tolylamine, N-[1,1′-biphenyl]-4-yl-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-amine, 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP), and 1,1-bis(4-(N,N′-bis(p-tolyl)amino)phenyl)cyclohexane (TAPC), but not limited thereto.

[0086] If necessary, the hole injection layer HIL or the hole transport layer HTL can be omitted.

[0087] The emission layer EML is disposed on the hole transport layer HTL. The emission layer EML emits light through the recombination of electrons and holes. The emission layer EML includes a polymer host and a phosphorescent dopant. The polymer host transfers energy to the phosphorescent dopant to improve the luminescence efficiency and color purity. In addition, the polymer host increases the density of electrons and holes in the emission layer EML to promote the recombination of excitons. Therefore, the luminescence efficiency can be improved.

[0088] The bank 165 includes contact holes for connecting the second connection line 152 serving as a data line and the data disk 173, and contact holes for connecting the first connection line 151 serving as a gate line and the connection disk 172.

[0089] The cathode CTD can be patterned to overlap with a plurality of individual substrates 121 respectively. That is, the cathode CTD may not be disposed between the plurality of individual substrates 121, but only in the area overlapping with the plurality of individual substrates 121.

[0090] The cathode CTD is made of a metallic material. Thus, if the cathode CTD is even disposed between the plurality of individual substrates 121, the cathode CTD may be damaged when the flexible display device 100 is stretched and contracted. Therefore, the cathode CTD can be disposed corresponding to each of the individual substrates 121 on a plane. In addition, the cathode CTD disposed in the area overlapping with the plurality of individual substrates 121 may have an area that does not overlap with the area where the connection line 150 is disposed. In addition, the cathode CTD is patterned to correspond to the plurality of individual substrates 121. Therefore, each of the cathode CTDs disposed on the plurality of individual substrates 121 can be independently supplied with low-potential power through the connection line 150.

[0091] In the flexible display device 100, various lines made of a metallic material, such as gate lines, data lines, high-potential power lines, and reference voltage lines, are only disposed on the plurality of individual substrates 121. That is, in the flexible display device 100 according to an embodiment of the present disclosure, various lines made of a metallic material can be only disposed on the plurality of individual substrates 121 without contacting the base substrate 120. Therefore, the various lines can be patterned to correspond to the plurality of individual substrates 121 and can be disposed discontinuously.

[0092] The connection line 150 is disposed between two adjacent individual substrates 121 to connect the discontinuous lines. The pads on two adjacent individual substrates 121 can be connected through the connection line 150. That is, the connection line 150 electrically connects the pads on two adjacent individual substrates 121.

[0093] The connection line 150 includes a first connection line 151 and a second connection line 152.

[0094] The first connection line 151 can be used as a gate line and can be electrically connected to the gate pads 171 on two individual substrates 121 adjacent to each other in the second direction through contact holes formed in the bank 165. Therefore, the gate pads 171 on the plurality of individual substrates 121 can be connected through the first connection line 151 used as a gate line, and a gate signal can be sent.

[0095] The second connection line 152 can be used as a data line and can electrically connect data disks 173 on two separate substrates 121 adjacent to each other in a first direction through contact holes formed in the bank 165. Accordingly, the data disks 173 on the plurality of separate substrates 121 can be connected through the plurality of second connection lines 152 used as data lines, and a data signal can be transmitted.

[0096] For ease of description, the LEDs of the stretchable display device according to an exemplary embodiment of the present disclosure have been shown and described as OLEDs. However, the present disclosure is not limited thereto. That is, micro LEDs can be used as the LEDs of the stretchable display device according to an embodiment of the present disclosure, and so on.

[0097] Figure 4A is a plan view of a support substrate 110 of a flexible display device 100 according to an embodiment of the present disclosure, Figure 4B is along Figure 4A a cross-sectional view of the support substrate 110 taken along line B-B′, and Figure 4C is along Figure 4A a cross-sectional view of the support substrate 110 taken along line C-C′.

[0098] For ease of description, the support substrate 110 will be described as a component of the flexible display device 100. However, the support substrate 110 is not limited to being a component of the flexible display device 100. That is, the following detailed description of the support substrate 110 can be equally applicable to any flexible display device described herein or other flexible display devices according to various embodiments of the present disclosure without particular limitation. The support substrate 110 can also be applied to other types of displays.

[0099] The support substrate 110 can be a composite material including a plurality of rigid portions 112 made of a rigid material and an elastic portion 111 made of an elastic material. Accordingly, during the flexible driving of the flexible display device 100, the support substrate 110 can be bent together with the display panel 10 to support the display panel 10 and enhance the rigidity of the display panel 10. Unless otherwise defined, the term "rigid" means that the elongation rate of a material in any axis is less than 10% before plastic deformation. The term "flexible" means that the elongation rate of a material in any axis is greater than 10% before plastic deformation.

[0100] The elastic portion 111 may correspond to a base material (matrix) in the material of the support substrate 110 made of a composite material. In an embodiment, the elastic portion 111 is one or a combination of any of the materials described herein. The elastic portion 111 may be arranged to fill between the plurality of rigid portions 112, and the elastic portion 111 may be arranged to surround the plurality of rigid portions 112. That is, the plurality of rigid portions 112 may be inserted into the elastic portion 111. Specifically, the elastic portion 111 may be arranged to surround the side surfaces 112S of the plurality of rigid portions 112. The elastic portion 111 may be arranged to expose a part of the upper surface 112U and the lower surface 112L of the rigid portion 112. For example, in one embodiment, the elastic portion 111 and the rigid portion 112 may have similar thicknesses such that the portions 111, 112 are flat or coplanar with each other. Thus, the elastic portion 111 is disposed on and covers the side surface 112S of the rigid portion 112, while the upper surface and the lower surface 112U, 112L of the rigid portion 112 are exposed. In such an embodiment, the upper surface and the lower surface 112U, 112L may be the outermost top and bottom surfaces or end surfaces of the rigid portion. Alternatively, the elastic portion 111 may be arranged to cover a part of the upper surface 112U and the lower surface 112L of the rigid portion 112, or may be arranged to cover all the surfaces 112S, 112U, 112L of the rigid portion 112. Thus, the rigid portion 112 may be inserted into the elastic portion 111 and thus surrounded by the elastic portion 111. Therefore, the elastic portion 111 can be used to fix the positions of the plurality of rigid portions 112.

[0101] The elastic portion 111 may be flexible. Thus, when the flexible display device 100 is stretched, the elastic portion 111 can support the display panel 10 when the support substrate 110 and the display panel 10 are stretched together.

[0102] The elastic portion 111 may be made of an elastic material. For example, the elastic portion 111 may be made of an elastomeric material such as silicone or rubber. Thus, the elastic modulus of the elastomeric material may be from 10 MPa to 1400 MPa. However, the material of the elastic portion 111 may vary according to the characteristics required for the product and is not limited thereto.

[0103] The plurality of rigid portions 112 may be made of a rigid material. The plurality of rigid portions 112 may correspond to core-shaped reinforcing materials among the materials of the support substrate 110 made of a composite material. Relative to the elastic portion 111, the rigid portion 112 may have a relatively high elastic modulus and a low coefficient of thermal expansion CTE. Thus, the rigid portion 112 can increase the elastic restoring force of the support substrate 110 to improve the durability of the support substrate 110. In addition, the rigid portion 112 can improve the resistance of the support substrate 110 to physical and thermal deformations.

[0104] The rigid portion 112 can be made of a highly elastic and rigid material, which can be any one of polymers such as Vero-Black, composite materials, metals, alloys, oxide ceramics, nitride ceramics, and carbide ceramics. Therefore, the elastic modulus of the highly elastic and rigid material can be from 1 GPa to 1000 GPa. However, the material of the rigid portion 112 can vary according to the characteristics required for the product and is not limited thereto.

[0105] Referring Figures 4A to 4C , the support substrate 110 is disposed under the display panel 10 to support the display panel 10. In addition, the support substrate 110 includes a plurality of rigid portions 112 extending along a first direction D1 and spaced apart from each other in a second direction D2 perpendicular to the first direction D1, and an elastic portion 111 disposed to fill between the plurality of rigid portions 112. Further, on the plane defined by the first direction D1 and the second direction D2, as Figure 4A shown, two side surfaces 112S of each of the plurality of rigid portions 112 include curved portions having a plurality of protrusions 112a and at least one recess 112b repeatedly provided along the first direction D1. Therefore, the rigidity of the display panel 10 can be enhanced, and the load concentrated on the display panel 10 can also be effectively dispersed. Therefore, flexible driving is possible, and sufficient rigidity for supporting the display panel 10 can be ensured. In addition, when the display device 100 is stretched, almost no cracks occur, which means that, compared with a display without the support substrate 110, depending on the stretching load, the incorporation of the support substrate 110 significantly reduces or even eliminates the possibility of fracture. Therefore, the display device 100 can be bent or stretched without being damaged. Therefore, it is preferable that the flexible display device 100 includes the support substrate 110.

[0106] Two side surfaces 112S of each of the plurality of rigid portions 112 can be symmetrical to each other, which means that the protrusions 112a and at least one recess 112b are generally aligned or corresponding to each other on both sides 112S of the rigid portion 112.

[0107] Each of the plurality of protrusions 112a may have a curved shape with a curvature. For example, each of the plurality of protrusions 112a may have a circular or oval shape, or be at least partially circular or oval. Each rigid portion 112 may be disposed in a continuous row of alternating protrusions 112a and recesses 112b extending in a first direction D1. Thus, the rigid portions 112 are formed as one or more circles or ovals connected to each other, for example, along the first direction D1. In addition, one or more circles or ovals may partially overlap each other and thus may extend along the first direction D1. However, the present disclosure is not limited thereto. Since both side surfaces 112S of each protrusion 112a have a curved shape, the possibility of cracks occurring when the display device is elongated in a second direction D2 can be reduced, and durability can be improved.

[0108] The protrusion 112a included in the side surface 112S of one rigid portion among the plurality of rigid portions 112 may be arranged to be adjacent to the protrusion 112a of another rigid portion 112 adjacent to the one rigid portion 112 in the second direction D2. Specifically, the rigid portions 112 extending in the first direction D1 may have the same shape, and the rigid portions 112 having the same shape may be repeatedly arranged at regular intervals in the second direction D2. In other words, in some embodiments, the protrusion 112a of each rigid portion 112 is aligned or corresponds to the protrusion 112a of the subsequent rigid portion 112 in the second direction D2. Thus, the stretchability of the flexible display device 100 can be improved, and the rigidity for supporting the display panel 10 can be further enhanced, and the flexibility of the display device 100 is not overly restricted or affected due to the elastic portion.

[0109] Figure 5 is a plan view of a support substrate 110-1 of a flexible display device according to an embodiment of the present disclosure. Except for the shape of the rigid portion 112-1, Figure 5 the support substrate 110-1 shown Figure 4A is substantially the same as the support substrate 110 shown

[0110] Refer to Figure 5, the support substrate 110-1 of the display device according to an embodiment of the present disclosure may include a plurality of rigid portions 112-1 repeatedly provided at regular intervals in the second direction D2. In addition, elastic portions 111-1 may be provided between the plurality of rigid portions 112-1. Each of the plurality of rigid portions 112-1 may extend in the first direction D1. In addition, each of the plurality of rigid portions 112-1 may include a plurality of protrusions 112a-1 and a plurality of recesses 112b-1. The plurality of protrusions 112a-1 and the plurality of recesses 112b-1 may be alternately provided in each of the plurality of rigid portions 112-1. For example, each of the plurality of rigid portions 112-1 may be formed as a plurality of circles that extend in contact with each other in the first direction D1 without overlapping. In other words, in Figure 4A , the rigid portion 112 includes a plurality of continuous and interconnected circular regions of rigid material. These circular regions overlap each other such that each circular region has only a partial circular shape, and the interface between the continuous circular regions is a continuous material portion having adjacent circular regions of rigid material. In Figure 5 , the circular regions do not overlap, which means that each circular region is a complete circle, and the interface between the circular regions in the rigid portion 112 is located at the boundary of the continuous or adjacent circular regions. Therefore, the rigid portions 112 may be joined to each other at the circumference or outer periphery of the complete circles of the rigid material in Figure 5 and may be discontinuous in some aspects.

[0111] Figure 6 is a plan view of the support substrate 210 of the flexible display device according to an embodiment of the present disclosure. Except for the shape of the rigid portion 212, Figure 6 the support substrate 210 shown is substantially the same as Figure 4A the support substrate 110 shown. Therefore, redundant description thereof will be omitted.

[0112] Referring to Figure 6 , the protrusion 212a included in the side surface 212S of one of the rigid portions included in the plurality of rigid portions 212 may be provided to be adjacent to the recess 212b included in the side surface of another rigid portion 212 adjacent to the one rigid portion 212 in the second direction D2. That is, the protrusion 212a of the rigid portion 212 provided on the first row or in the first row extending in the first direction D1 may be provided to be offset from the protrusion 212a of another rigid portion 212 on the second row adjacent or consecutive thereto in the second direction D2. Therefore, the durability of the flexible display device 100 against elongation can be further improved.

[0113] Hereinafter, for convenience of description, reference will be made to Figure 4A and Figure 6Describe the distance relationship between components. However, the following description is not limited to Figure 4A and Figure 6 the embodiments shown, but can equally apply to all embodiments of the present disclosure.

[0114] Referring to Figure 4A and Figure 6 , Figure 4A the support substrate 110 of may include a distance d1 in the second direction D2 between a protrusion 112a in a side surface 112S of one of the plurality of rigid portions 112 and a protrusion 112a of another adjacent or successive rigid portion 112. Figure 6 the support substrate 210 of may include a distance d1' between a protrusion 212a included in a side surface 212S of one of the plurality of rigid portions 212 and a protrusion 212a of another rigid portion 212 adjacent or successive along the second direction D2. The distance d1 or d1' may be 15 μm to 200 μm. For example, the distance d1 or d1' may be 15 μm to 150 μm, or may be 15 μm to 100 μm. Accordingly, the durability of the flexible display device 100 against elongation can be improved, and the rigidity can be further enhanced. When the distance d1 or d1' is less than the above range, the durability against elongation is reduced, and when the distance d1 or d1' is greater than the above range, the rigidity for supporting the display panel of the flexible display device 100 is reduced. In other words, the distances d1, d1' within the above range correspond to the desired characteristics of the flexible display device 100, such as sufficient support and rigidity for the display panel 10 without unduly restricting flexibility. Embodiments may also include support substrates where the distances d1, d1' are outside these ranges, particularly those where the material composition or properties of the support substrate and / or the rigid portions are adjusted to achieve the desired balance of rigidity and flexibility.

[0115] Referring to Figure 4A , based on a center line CL in the first direction D1 at the center of each of the plurality of rigid portions 112, a distance d2 between a protrusion 112a in a side surface 112S of a first rigid portion among the plurality of rigid portions 112 and a protrusion 112a in a side surface 112S facing the side surface 112S with respect to the center line CL may be 2 mm to 4 mm. For example, the distance d2 may be 2 mm to 3 mm. In other words, d2 is a measure of the maximum width of the rigid portion 112 in the second direction D2 and corresponds to the region where the curved side surface 112S of the protrusion 112a extends farthest from both sides of the vertical center line CL passing through each rigid portion 112. Accordingly, when the distance d2 is within such a range, the durability of the flexible display device 100 against stretching can be improved, and the rigidity can be further enhanced.

[0116] In addition, the distance d3 between a recess 112b included in the side surface 112S of one of the plurality of rigid portions 112 and another recess 112b adjacent to or continuous with the recess 112b in the first direction D1 in the same side surface 112S may be from 1.5 mm to 3 mm. For example, the distance d3 may be from 1.5 mm to 2 mm. In other words, d3 is a measure of the maximum height of each curved or circular region along the first direction D1 between consecutive recesses 112b in the first direction D1. Therefore, when the distance d3 is within such a range, the durability of the flexible display device 100 against stretching can be improved, and the rigidity can be further enhanced. Similar to the distances d1 and d1' as described above, the distances d2 and d3 may also be outside these ranges in other embodiments, and the structure or composition of the support substrate 110 and / or the rigid portions 112 may be appropriately modified as needed. For example, the distance d3 may be from 1.5 mm to 2 mm.

[0117] Figure 7 is a plan view of a support substrate 310 of a flexible display device according to an embodiment of the present disclosure. Except for the shape of the rigid portions 312, Figure 7 the support substrate 310 shown Figure 4A is substantially the same as the support substrate 110 shown. Therefore, redundant description thereof will be omitted.

[0118] Referring to Figure 7 , the support substrate 310 may include a plurality of rigid portions 312, the plurality of rigid portions including a plurality of sub-rigid portions 312-1 that are repeatedly provided, discontinuous, and spaced apart from each other in a first direction D1 and a second direction D2. Here, two side surfaces 312S of the sub-rigid portion 312-1 may include two protrusions 312a and a recess 312b between the two protrusions 312a. For example, the sub-rigid portion 312-1 may be formed like two circles joined to each other in the first direction D1 like a snowman, but is not limited thereto. In other words, the two circles may partially overlap at their interfaces such that each circle is a partial circle and is joined to an adjacent circle at the interface between the circles in a continuous structure to form a snowman or an "8" shape. Since the sub-protrusions 312-1 are spaced apart from each other in the first direction D1 and the second direction D2, when the flexible display device 100 including the sub-protrusions 312 elongates in the first direction D1 and the second direction D2, it hardly breaks or gets damaged. That is, the durability of the flexible display device 100 against elongation in the first direction D1 can be further improved. In Figure 7In [the structure], each sub-rigid part 312-1 is aligned with other sub-rigid parts 312-1 in repeated rows and columns in a first direction D1 and a second direction D2 to form a matrix, and the spacing therebetween in both directions D1 and D2 is constant. In some embodiments, the spacing between the sub-rigid parts 312-1 may be different in either or both of the directions D1 and D2, and the sub-rigid parts 312-1 may be offset from other sub-rigid parts 312-1 in consecutive rows and / or columns or in any other rows and / or columns. In other words, the sub-rigid parts 312-1 may also be arranged in a selected configuration different from Figure 7 that shown.

[0119] Figure 8 is a plan view of a support substrate 410 of a flexible display device according to an embodiment of the present disclosure. Except for the shape of the rigid part 412, Figure 8 the support substrate 410 shown is Figure 4A substantially the same as the support substrate 110 shown. Thus, redundant description thereof will be omitted.

[0120] Referring to Figure 8 , a plurality of protrusions may be alternately provided in each rigid part 412 along the first direction D1, and may include a first protrusion 412a and a second protrusion 412a' that are different from each other in at least one characteristic, such as different in size or curvature, etc. For example, the first protrusion 412a and the second protrusion 412a' may be alternately provided along the first direction D1. Since the first protrusion 412a and the second protrusion 412a' are different from each other in size and / or curvature and are alternately provided along the first direction D1, the flexible display device 100 including the first protrusion 412a and the second protrusion 412a' may have higher stretchability. Thus, the durability against elongation can be further improved. In one embodiment, the first protrusion 412a is smaller than the second protrusion 412a', and each rigid part 412 includes a repeating pattern of first and second protrusions 412a, 412a' that are alternately arranged in the first direction D1. Other variations may be envisioned, such as at least different patterns. For example, each rigid part 412 may include a repeating pattern of two or more first protrusions 412a followed by a second protrusion 412a', or a repeating pattern of one first protrusion 412a followed by two or more second protrusions 412a'. The pattern of each rigid part 412 may also include a selected order of the first and second protrusions 412a, 412a', which may be the same as or different from those of other rigid parts 412. In addition, other protrusions having different sizes and curvatures in each rigid part 412 or only selected rigid parts 412 are envisioned.

[0121] As can be clearly seen from the above, the present disclosure places no particular restrictions on the shape or arrangement of the rigid portions. For example, the rigid portions may each have the same configuration or may have different configurations. The protrusions of the rigid portions may be aligned or offset, and may be spaced apart from each other and from the successive rigid portions by a selected distance. In each case, different radii of curvature and dimensions can be envisaged. The protrusions or regions of the rigid material may overlap or may be joined at their outer perimeters, or may be discontinuous. Although Figures 4A to 8 variations of circular or partially circular regions of the rigid portions are shown, any other shape is envisaged herein. In some non-limiting examples, the rigid portions may have a straight shape and may or may not have protrusions and recesses in either direction D1, D2, may have a curved shape and may or may not have protrusions or recesses in either direction D1, D2, may have a serrated shape or a local thickening (step up) or a local thinning (step down) in either direction D1, D2, or the protrusions may be oval, triangular, trapezoidal, rhomboidal, rectangular, square, parallelogram, polygon of any selected number of sides, cloverleaf, cross-shaped, semi-circular or partially circular, rhomboidal, kite-shaped, elliptical, crescent-shaped or an irregular shape not belonging to one of the above categories, etc. As will be further explained below, circular or oval shapes in the rigid portions are generally preferred because they exhibit the best performance in stress tests, however the present disclosure is not limited thereto.

[0122] Figure 9 is a schematic plan view of a flexible display device 500 according to an embodiment of the present disclosure, and Figure 10 is a cross-sectional view taken along the Figure 9 line D-D'.

[0123] Referring to Figure 9 and Figure 10 , the flexible display device 500 may be a foldable display device. The flexible display device 500 may include a support substrate 510, a display panel 520, and a cover window 530.

[0124] In describing the Figure 9 and Figure 10 illustrated flexible display device 500, all of the above descriptions regarding the support substrate with reference to Figures 4A to 8 and the following descriptions may equally apply to the support substrate 510.

[0125] The display panel 520 includes a display area DA and a non-display area NDA. In addition, the display panel 520 includes a folding area FA and non-folding areas NFA1 and NFA2. The display panel 520 can be divided into the display area DA and the non-display area NDA depending on whether an image can be displayed or based on the areas of the display panel 520 where an image is displayed or not displayed. In addition, the display panel 520 can be divided into the folding area FA and the non-folding areas NFA1 and NFA2 depending on whether it can be folded or where it can be folded. Therefore, a part of the display panel 520 can be used as the display area DA and the folding area FA, and another part of the display panel 520 can be used as the non-display area NDA and the non-folding area NFA, or any combination thereof.

[0126] The display panel 520 includes a foldable folding area FA and non-folding areas NFA1 and NFA2 other than the folding area FA. The folding area FA is the area that folds when the flexible display device 500 is folded, and is folded according to specific radii of curvature with respect to folding axes FL1 and FL2. For example, the folding axes FL1 and FL2 of the folding area FA can be defined in the first direction D1, and the non-folding areas NFA1 and NFA2 can extend from the folding area FA in a second direction D2 perpendicular to the folding axes FL1 and FL2. When the folding area FA is folded with respect to the folding axes FL1 and FL2, the folding area FA can form a part of a circle or an ellipse. Here, the radius of curvature of the folding area FA can refer to the radius of the circle or ellipse formed by the folding area FA.

[0127] The non-folding areas NFA1 and NFA2 are the areas that do not fold when the flexible display device 500 is folded. That is, when the flexible display device 500 is folded, the non-folding areas NFA1 and NFA2 remain flat. The non-folding areas NFA1 and NFA2 can be located on both sides of the folding area FA. That is, the non-folding areas NFA1 and NFA2 can extend in the second direction D2 with respect to the folding axes FL1 and FL2. Here, the folding area FA can be defined between the non-folding areas NFA1 and NFA2. In addition, when the flexible display device 500 is folded with respect to the folding axes FL1 and FL2, the non-folding areas NFA1 and NFA2 can overlap each other or face each other.

[0128] The support substrate 510 is disposed under the display panel 520. Thus, like the display panel 520, the support substrate 510 may include a folding region FA and non-folding regions NFA1 and NFA2 other than the folding region FA. In the folding region FA, folding axes FL1 and FL2 are defined in the first direction D1 and the folding region FA is foldable. The folding region FA may be composed of a plurality of rigid portions 512 extending in the first direction D1 and spaced apart from each other in a second direction D2 perpendicular to the first direction D1, and elastic portions 511 provided to fill between the plurality of rigid portions 512. In addition, the non-folding regions NFA1 and NFA2 may be composed only of the rigid portions 512. Thus, in the folding region FA where the display panel 520 can be extended, durability against extension or bending and rigidity for supporting the display panel can be ensured. In addition, in the non-folding regions NFA1 and NFA2 where the display panel 520 does not deform, excellent rigidity for supporting the display panel 520 can be ensured. In other words, in some embodiments, the display device described herein cannot be stretched or bent over the entire display or the effective area of the display, but has a specific folding region FA, referring to Figures 4A to 8 The rigid portions surrounded by the elastic portions described in detail may be included in the folding region FA, while the non-folding region NF only includes rigid materials.

[0129] Figure 11 and Figure 12 is Figure 9 A plan view of an embodiment of the support substrate in region II of. Except for the regions where the rigid portions 512 are formed and disposed, Figure 10 the support substrate 510 shown in Figure 11 and the support substrate 610 shown in Figure 4A are substantially the same as the support substrate 110 shown in

[0130] Referring to Figure 11 and Figure 12 , only the rigid portions 512 or 612 (i.e., without flexible portions) may be provided in the non-folding region NF1 of the support substrate 510 or 610 of the flexible display device 500. In addition, a plurality of rigid portions 512 or 612 extending in the first direction D1 and elastic portions 511 or 611 provided to fill the plurality of rigid portions 512 or 612 may be provided in the folding region FA. Here, the details of the plurality of rigid portions 512 or 612 and the elastic portions 511 or 611 provided in the folding region FA may be the same as those described above.

[0131] Referring to Figure 11, the elastic portion 511 may be disposed in the folding region FA adjacent to the folding axis FL1, which is the boundary surface between the folding region FA and the non-folding region NF1. In other words, the elastic portion 511 is located at the interface between the non-folding regions NFA1, NFA2 and the folding region FA.

[0132] Referring to Figure 12 , a rigid portion including a curved portion having a plurality of protrusions 612a and at least one recess 612b repeatedly arranged in the first direction D1 may be disposed on the side surface facing the folding region FA with respect to the folding axis FL1, which is the boundary surface between the folding region FA and the non-folding region NF1. Accordingly, the contact area at the boundary surface of the folding axis FL1 is increased. Accordingly, the occurrence of cracks or damages caused by the tension applied to the boundary surface during the folding of the folding region FA can be suppressed. In addition, the durability at the boundary surface can be improved. In other words, a part of the rigid portion 612 may be disposed on the folding axis FL1 (and the folding axis FL2), where the protrusions 612a extend inwardly toward the folding region FA and away from the non-folding regions NFA1, NFA2, which is different from Figure 11 where the flexible portion 511 is located at the folding axis FL1 (and the folding axis FL2) in

[0133] Hereinafter, referring to Figures 13 to 16B the results of the elongation rate test simulation of each support substrate according to the comparative example and the embodiment will be described. Figure 13 , Figure 14 , Figure 15B and Figure 16B show regions of different deformation stresses in color. In the color map, a gradient or spectrum is provided to show different levels of stress. The gradient starts at the bottom, and blue represents the low deformation stress region. The top or upper end of the gradient and / or spectrum is red, which represents the high deformation stress region. The colors between blue and red represent intermediate stresses, where blue, cyan, and green represent low to medium stresses, and green, yellow, and orange represent medium to high stresses. "Low" and "high" deformation stresses can also be represented by numbers, such as the numbers shown in the gradient, to identify different colors and the corresponding deformation stresses. The unit of measurement of the gradient can be the standard dimension of stress measurement, such as newtons per square meter (N / m2), pounds per square inch (lb / in2), or others.

[0134] Figure 13 shows Figure 4A the results of the 5% elongation rate test simulation of the support substrate 110 shown in

[0135] Referring toFigure 13 , it can be seen that even though the plurality of elastic portions 111 disposed between the plurality of rigid portions 112 cause elongation and contraction when the shown support substrate 110 elongates at a strain of 5%, the deformation stress applied to the entire support substrate 110 is also low because, in terms of stress level, most regions are blue or green while only a small number of regions are close to yellow and / or orange. Figure 4A The figure shows the result of a 5% elongation test simulation of the shown support substrate 310.

[0136] Figure 14 shows Figure 7 the result of a 5% elongation test simulation of the shown support substrate 310.

[0137] Referring to Figure 14 , it can be seen that even though the plurality of elastic portions 311 disposed between the plurality of rigid portions 312 cause elongation and contraction when the shown support substrate 310 elongates at a strain of 5%, the deformation stress applied to the entire support substrate 310 may also be low. Although the stress pattern of the substrate 310 is different from Figure 7 that shown, both stress patterns generally exhibit mostly low-stress characteristics. The elastic portions 311 exhibit higher stress as expected because these portions deform during the 5% strain test while the rigid portions 312 do not deform. Even the elastic portions 311 include a color pattern mainly of colors at the lower end of the stress spectrum. Figure 13 Moreover,

[0138] the shown support substrate 310 may include at least one gap or space between the plurality of rigid portions 312 along the first direction D1. The at least one gap or space is filled with an elastic material 311. Thus, it can be seen that in the at least one gap, the deformation stress applied when elongation and contraction occur is further reduced. Therefore, it can be seen that the deformation stress applied to the entire support substrate 310 during elongation and contraction is further reduced. Figure 7

[0139] Figure 15A Figure 15B is a plan view of a support substrate 710 according to a comparative example, and Figure 15B shows the result of a 25% elongation test simulation of the support substrate 710 of the comparative example.

[0140] Referring to Figure 15A , the support substrate 710 of the comparative example includes a plurality of rigid portions 712 arranged at regular intervals in the second direction D2 and a plurality of elastic portions 711 disposed between the plurality of rigid portions 712. Here, the plurality of rigid portions 712 may extend linearly in the first direction D1. That is, both side surfaces of each of the plurality of rigid portions 712 may be straight.

[0141] Referring to Figure 15B, the support substrate 710 of the comparative example includes a plurality of rigid portions 712 extending linearly in the first direction D1. Therefore, when the support substrate 710 is elongated with a strain of 25%, the deformation stress applied to the plurality of elastic portions 711 is high, as shown by the substantially darker shading. In addition, it can be seen that the average deformation stress applied to the entire support substrate 710 is as high as 99.6%.

[0142] Figure 15C Shows Figure 4A The results of the 25% elongation test simulation of the support substrate 110 shown, and Figure 15D Shows Figure 8 The results of the 25% elongation test simulation of the support substrate 410 shown.

[0143] Referring to Figure 15C , it can be seen that when Figure 4A The support substrate 110 shown is elongated with a strain of 25%, the deformation stress applied to the entire support substrate 110 is lower compared to the support substrate 710 of the comparative example, as shown by the lighter shading of the elastic portion 111 of the substrate.

[0144] Referring to Figure 15D , it can be seen that when Figure 8 The support substrate 410 shown is elongated with a strain of 25%, the deformation stress applied to the entire support substrate 410 is lower compared to the support substrate 710 of the comparative example. In Figure 15C And Figure 15D , the difference in deformation stress is obvious compared to the comparative example because Figure 15C And Figure 15D The substrates 110, 410 in are mostly green at the elastic portions with some isolated yellow and / or orange areas, instead of being completely high-stress or red as in Figure 15B . Overall, these images show that the concept of the present disclosure greatly reduces the deformation stress.

[0145] Therefore, it can be seen that if the side surface of each of the plurality of rigid portions has a curved shape and there is an elastic material therebetween, the deformation stress applied to the entire support substrate during elongation and contraction will be reduced.

[0146] In addition, based on Figure 4A The results of the 25% elongation test simulation of the support substrate 110 shown and Figure 8 The results of the 25% elongation test simulation of the support substrate 410 shown, the average deformation stress applied to the entire support substrates 110 and 410 is calculated. According to the results of the 25% elongation test simulation, the average deformation stress applied to Figure 4A The entire support substrate 110 shown is 23.2%, and the average deformation stress applied to Figure 8The average deformation stress of the entire support substrate 410 shown is 19.8%. Therefore, it can be seen that if the side surfaces of each of the plurality of rigid portions 412 include protrusions 412a and 412a' having different curvatures from each other, the deformation stress applied to the entire support substrate 410 including the protrusions 412a and 412a' is further reduced, and the embodiments of the present disclosure greatly reduce the stress of the entire substrate as compared with the comparative example.

[0147] Figure 16A shows Figure 11 the results of a 5% elongation test simulation of the support substrate 510 shown, and Figure 16B shows Figure 12 the results of a 5% elongation test simulation of the support substrate 610 shown.

[0148] Referring to Figure 16A and Figure 16B , it can be seen that when Figure 11 the support substrate 510 shown and Figure 12 the support substrate 610 shown are each elongated at a strain of 5%, the deformation stress applied to the entire support substrates 510 and 610 is lower than that of the comparative example, but may be higher in some regions according to other examples of the present disclosure discussed herein.

[0149] Furthermore, based on Figure 11 the results of a 5% elongation test simulation of the support substrate 510 shown and Figure 12 the support substrate 610 shown, the average deformation stress applied to the entire support substrates 510 and 610 is calculated. According to the results of the 5% elongation test simulation, the average deformation stress applied to Figure 11 the entire support substrate 510 shown is 10.9%, and the average deformation stress applied to Figure 12 the entire support substrate 610 shown is 9.1%. Therefore, it can be seen that if the rigid portion 612 is provided in the folding region FA adjacent to the folding axis FL1, the deformation stress applied to the entire support substrate 610 is further reduced. Figure 16A and Figure 16B mainly illustrate that adding the rigid portion 612 along the folding axis FL1 further reduces the stress as compared with the embodiment of removing the rigid portion 612 at the folding axis FL1, or in other words, illustrate that providing the rigid portion 612 along the folding axis FL1 is beneficial.

[0150] Through the above, the embodiments of the present disclosure can also be described or summarized as follows:

[0151] According to one aspect of the present disclosure, a flexible display device is provided. The flexible display device includes: a display panel configured to display an image; and a support substrate disposed under the display panel to support the display panel, and including a plurality of rigid portions extending in a first direction and spaced apart from each other in a second direction perpendicular to the first direction, and elastic portions provided to fill between the plurality of rigid portions, wherein, on a plane defined by the first direction and the second direction, two side surfaces of each of the plurality of rigid portions include curved portions having a plurality of protrusions and at least one recess repetitively provided in the first direction.

[0152] Each of the plurality of protrusions may have a circular or elliptical curvature.

[0153] The plurality of protrusions may be alternately provided in the first direction and include a first protrusion and a second protrusion having different curvatures from each other.

[0154] Two side surfaces of each of the plurality of rigid portions may be symmetric with each other.

[0155] Each of the plurality of rigid portions may include a plurality of sub-rigid portions repetitively provided in the first direction and spaced apart from each other.

[0156] Two side surfaces of the sub-rigid portion may include two protrusions and a recess between the two protrusions.

[0157] Protrusions included in a side surface of one of the plurality of rigid portions may be provided adjacent to protrusions of another rigid portion adjacent to the one rigid portion in the second direction.

[0158] The plurality of rigid portions may have the same shape and be repetitively provided at regular intervals in the second direction.

[0159] Protrusions included in a side surface of one of the plurality of rigid portions may be provided adjacent to a recess included in a side surface of another rigid portion adjacent to the one rigid portion in the second direction.

[0160] The distance between protrusions included in a side surface of one of the plurality of rigid portions and protrusions of another rigid portion adjacent to the one rigid portion in the second direction may be 15 μm to 200 μm.

[0161] Based on a central axis in the first direction at the center of each of the plurality of rigid portions, the distance between protrusions included in a side surface of one of the plurality of rigid portions and protrusions included in the other side surface facing the side surface with respect to the central axis may be 2 mm to 4 mm.

[0162] The distance between a recess included in a side surface of one of the plurality of rigid parts and another recess adjacent to the recess in the first direction in the same side surface may be 1.5 mm to 3 mm.

[0163] The plurality of rigid parts may be made of a highly elastic and rigid material, which includes any one of the following: a polymer including Vero - Black, a composite material, a metal, an alloy, an oxide ceramic, a nitride ceramic, and a carbide ceramic.

[0164] The elastic modulus of the highly elastic and rigid material may be 1 GPa to 1000 GPa.

[0165] The elastic part may be made of an elastomeric material including silicone resin or rubber.

[0166] The elastic modulus of the elastomeric material may be 10 MPa to 1400 MPa.

[0167] The flexible display device may be a stretchable display device elongated in the second direction. And the display panel includes: a base substrate; a plurality of individual substrates on which a plurality of pixels are defined and which are spaced apart from each other; and connection lines that electrically connect pads provided on adjacent individual substrates among the plurality of individual substrates.

[0168] The flexible display device may be a foldable display device. And the support substrate may further include: a folding region in which a folding axis is defined in the first direction and which is foldable; and a non - folding region that does not include the folding region. The folding region may be composed of a plurality of rigid parts extending in the first direction and spaced apart from each other in a second direction perpendicular to the first direction, and elastic parts provided to fill between the plurality of rigid parts, and the non - folding region may be composed only of rigid parts.

[0169] The rigid part including a bent portion may be provided on a side surface facing the folding region at a boundary surface between the folding region and the non - folding region, and the bent portion has a plurality of protrusions and at least one recess repeatedly provided in the first direction.

[0170] In one embodiment, the flexible display device includes: a display panel; a support substrate provided on the display panel, the support substrate extending in a first direction and a second direction perpendicular to the first direction, the support substrate including a plurality of rigid parts extending in the first direction and spaced apart from each other in the second direction, and elastic parts provided between the plurality of rigid parts, wherein at least one of the plurality of rigid parts includes a plurality of protrusions and recesses.

[0171] In one embodiment, each of the plurality of rigid portions includes a plurality of protrusions and recesses, wherein the plurality of protrusions of each of the plurality of rigid portions are aligned with each other in a second direction.

[0172] In one embodiment, each of the plurality of rigid portions includes a plurality of protrusions and recesses, wherein the first of the plurality of protrusions of the first of the plurality of rigid portions is aligned with a recess of the second of the plurality of rigid portions in a second direction.

[0173] In one embodiment, the plurality of rigid portions include a plurality of sub-portions spaced apart from each other in a first direction.

[0174] In one embodiment, the plurality of rigid portions are continuous in a first direction.

[0175] In one embodiment, the plurality of protrusions include a first protrusion and a second protrusion having a curvature or size different from that of the first protrusion.

[0176] In one embodiment, a flexible display device includes: a display panel; a support substrate disposed on the display panel, the support substrate including a plurality of rigid portions, each of the plurality of rigid portions including a first protrusion, a second protrusion, and a recess between the first protrusion and the second protrusion, and an elastic portion disposed between the plurality of rigid portions.

[0177] In one embodiment, the size of the first protrusion is different from the size of the second protrusion.

[0178] In one embodiment, the first protrusion and the second protrusion are continuous as one body.

[0179] In one embodiment, the plurality of rigid portions are spaced apart from each other in a first direction and a second direction of the support substrate, wherein the second direction is perpendicular to the first direction.

[0180] In one embodiment, the flexible display device further includes a gap between the plurality of rigid portions, wherein the elastic portion fills the space between the plurality of rigid portions.

[0181] Although 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 embodiments of the present disclosure are provided for illustrative purposes only and are 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 embodiments are illustrative in all aspects and do not limit the present disclosure. The scope of the present disclosure should be construed as including all the technical concepts described herein and their equivalent scope. The scope of the claims is not limited by the present disclosure.

[0182] The various embodiments described above can be combined to provide other embodiments. If necessary, aspects of the embodiments can be modified to adopt the concepts of various patents, applications, and publications to provide other embodiments.

[0183] In view of the foregoing detailed description, the above and other changes can be made to the embodiments. Generally, in the claims, the terms used should not be construed as limiting the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include the entire scope of all possible embodiments and equivalents of these claims. Thus, the claims are not limited by the present disclosure.

Claims

1. A flexible display device, comprising: a display panel configured to display an image; as well as a supporting substrate disposed under the display panel and configured to support the display panel, the supporting substrate comprising a plurality of rigid portions extending in a first direction and spaced apart from each other in a second direction perpendicular to the first direction, the supporting substrate further comprising an elastic portion disposed between the plurality of rigid portions, wherein each of the plurality of rigid parts comprises a first side surface and a second side surface, and At least one of the first side surface and the second side surface is at least partially curved and includes a first protrusion, a second protrusion, and a recess between the first protrusion and the second protrusion.

2. The flexible display device according to claim 1, wherein: The second protrusion has a different curvature from the first protrusion, The first protrusion and the second protrusion are two protrusions among a plurality of protrusions repeatedly and alternately arranged in the first direction along each of the plurality of rigid portions.

3. The flexible display device according to claim 1, wherein: The first side surface and the second side surface of each of the plurality of rigid portions are symmetrical to each other.

4. The flexible display device according to claim 1, wherein: Each of the plurality of rigid portions includes a plurality of sub-rigid portions that are repeatedly arranged along the first direction and spaced apart from each other.

5. The flexible display device according to claim 4, wherein: Each of the plurality of sub-rigid portions includes a first side surface and a second side surface, and at least one of the first side surface and the second side surface includes a first protrusion and a second protrusion separated by the recess; and Wherein, the support substrate further includes at least one gap between the plurality of rigid parts in the first direction.

6. The flexible display device according to claim 1, wherein: The plurality of rigid portions include a first rigid portion and a second rigid portion continuing from the first rigid portion in the second direction, and The first protrusion included in at least one of the first side surface and the second side surface of the first rigid part is disposed adjacent to the first protrusion included in at least one of the first side surface and the second side surface of the second rigid part.

7. The flexible display device according to claim 6, wherein: Each of the plurality of rigid portions has the same shape and is repeatedly arranged at the same intervals along the second direction.

8. The flexible display device according to claim 1, wherein: The plurality of rigid portions include a first rigid portion and a second rigid portion continuing from the first rigid portion in the second direction, and The first protrusion included in at least one of the first side surface and the second side surface of the first rigid portion is disposed adjacent to the recess included in at least one of the first side surface and the second side surface of the second rigid portion.

9. The flexible display device according to claim 1, wherein: A distance between a first protrusion of a first rigid portion among the plurality of rigid portions and a first protrusion of a second rigid portion among the plurality of rigid portions adjacent to the first rigid portion in the second direction is 15 μm to 200 μm, or Wherein, the width of the first protrusion or the second protrusion is 2 mm to 4 mm, or Wherein, the height of the first protrusion or the second protrusion is 1.5 mm to 3 mm.

10. The flexible display device according to claim 1, wherein: One of the plurality of rigid portions is disposed at a folding axis of the support substrate, wherein the first and second protrusions of the one of the plurality of rigid portions face the folding region of the support substrate.

11. A flexible display device, comprising: Display panel; and A supporting substrate, wherein the supporting substrate is disposed on the display panel, the supporting substrate extends along a first direction and a second direction perpendicular to the first direction, and the supporting substrate comprises: a plurality of rigid portions extending along the first direction and spaced apart from each other along the second direction, and An elastic portion disposed between the plurality of rigid portions, Wherein, at least one of the plurality of rigid parts comprises a plurality of protrusions and recesses.

12. The flexible display device according to claim 11, wherein: Each of the plurality of rigid portions comprises a plurality of protrusions and recesses, and Wherein, the plurality of protrusions of each of the plurality of rigid parts are aligned with each other along the second direction.

13. The flexible display device according to claim 11, wherein: Each of the plurality of rigid portions comprises a plurality of protrusions and recesses, and The first protrusion of the plurality of protrusions of the first rigid part of the plurality of rigid parts is aligned with the recess of the second rigid part of the plurality of rigid parts along the second direction.

14. The flexible display device according to claim 11, wherein: The plurality of rigid portions are continuous in the first direction.

15. The flexible display device according to claim 11, wherein: The plurality of protrusions include a first protrusion and a second protrusion having a different curvature or size from the first protrusion.

16. A flexible display device, comprising: Display panel; and A supporting substrate, wherein the supporting substrate is disposed on the display panel, and the supporting substrate comprises: a plurality of rigid portions, each of the plurality of rigid portions comprising a first protrusion, a second protrusion, and a recess between the first protrusion and the second protrusion; and An elastic portion is disposed between the plurality of rigid portions.

17. The flexible display device according to claim 16, wherein: The size of the first protrusion is different from the size of the second protrusion.

18. The flexible display device according to claim 16, wherein: The first protrusion and the second protrusion are continuous and integrated.

19. The flexible display device according to claim 16, wherein: The plurality of rigid portions are spaced apart from each other along a first direction and a second direction of the support substrate, and The second direction is perpendicular to the first direction.

20. The flexible display device according to claim 16, further comprising: The spaces between the plurality of rigid portions are provided, wherein the elastic portion fills the spaces between the plurality of rigid portions.

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