Foldable display device

Abstract

The foldable display device includes a display panel configured to fold about a folding axis. The display panel includes spacers arranged in a non-folding area and a folding area, and the spacers may have different sizes or densities. The dimensions of the spacers may be in the direction of the folding axis or intersect with the direction of the folding axis. The display panel also includes pixels in the display area overlapping the spacers, which help reduce peeling, cracking, defects, or pixel brightness reduction caused by folding of the display device.

Description

[0001] This application is a divisional application of application No. 201811384606.4, filed on November 20, 2018, with the title of "Foldable Display Apparatus".

[0002] Cross Reference to Related Applications

[0003] This application claims priority to Korean Patent Application No. 10-2017-0160351, filed on November 28, 2017, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0004] The present disclosure relates to a foldable display apparatus including a spacer stabilizing structure in a folding area. BACKGROUND

[0005] Image display apparatuses that implement various information on a screen become core technologies in the information communication era. Examples of the image display apparatuses include a cathode ray display panel, a liquid crystal display panel, an electrophoretic display panel, an organic light emitting display panel, etc.

[0006] As a tool for implementing a thinner, lighter, and portable image display apparatus having higher performance, an organic light emitting display panel has received a great deal of attention. The organic light emitting display panel is configured to display an image by controlling an amount of light emitted from an organic light emitting element.

[0007] The organic light emitting display panel is a self-emission display panel implemented without a discrete light source, and thus can be manufactured to be light weight and thin profile. In addition, the organic light emitting display panel can be easily implemented as a foldable display apparatus by arranging a thin film transistor and an organic light emitting layer on a foldable substrate.

[0008] The organic light emitting display panel implemented as a foldable display apparatus can be vulnerable to external impact. In particular, when the foldable display apparatus is folded, the organic light emitting layer can be peeled off and broken near a folding area due to low adhesion strength of the organic light emitting layer.

[0009] In a conventional organic light emitting display panel, a spacer is located in a non-emission area. Thus, the organic light emitting layer can be protected by suppressing peeling of the organic light emitting layer caused by external impact generated when the foldable display apparatus is folded.

[0010] However, when the foldable display apparatus is folded, the organic light emitting display panel can be applied with a folding stress by folding. If the organic light emitting display panel is continuously applied with stress by repeated folding, the spacer in the organic light emitting display panel can be broken. Thus, the broken spacer serves as a particle and can cause an undesirable dark spot in the organic light emitting layer. The dark spot in the organic light emitting layer can reduce brightness of the foldable display apparatus. SUMMARY

[0011] An object to be achieved by the disclosure is to provide a foldable display apparatus in which an organic light emitting display panel includes spacers and occurrence of a crack in the spacers can be suppressed. In an embodiment, the foldable display apparatus includes a display panel configured to be folded about a folding axis. The display panel includes a first plurality of spacers arranged in a non-folded area. In addition, the display panel includes a second plurality of spacers arranged in a folded area, wherein the second plurality of spacers has a different size from the first plurality of spacers. Each of the second plurality of spacers has a first dimension and a second dimension greater than the first dimension. The second dimension of the second plurality of spacers is in a direction of the folding axis. In some embodiments, the second dimension of each spacer of the second plurality of spacers is a largest dimension of the each spacer. In some embodiments, the first dimension of each spacer of the second plurality of spacers is a smallest dimension of the each spacer, wherein the first dimension is all intersected with the direction of the folding axis.

[0012] In another embodiment, the foldable display apparatus includes a display panel configured to be folded about a folding axis. The display panel includes a first plurality of spacers arranged in a non-folded area. In addition, the display panel includes a second plurality of spacers arranged in a folded area, wherein a first density of the first plurality of spacers is less than a second density of the second plurality of spacers.

[0013] In another embodiment, the foldable display apparatus includes a display panel configured to be folded about a folding axis. The display panel includes a first plurality of spacers arranged in a non-folded area. In addition, the display panel includes a second plurality of spacers arranged in a folded area, wherein the second plurality of spacers has a different size or density from the first plurality of spacers. The display panel further includes a plurality of pixels arranged in a display area. Each of the plurality of pixels is overlapped with at least one of the first plurality of spacers or the second plurality of spacers.

[0014] The object of the disclosure is not limited to the above-mentioned objects, and other objects not mentioned above will be clearly understood by those skilled in the art from the following description.

[0015] The above-mentioned object to be achieved by the disclosure, aspects of the disclosure, and effects of the disclosure are not essential features of the claims, and thus the scope of the claims is not limited to the disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0016] The above and other aspects, features, and other advantages of the 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 plan view of a foldable display apparatus according to an exemplary embodiment of the disclosure.

[0018] Figure 2A is a cross-sectional view taken along line IIa-IIa' of Figure 1

[0019] Figure 2B is a cross-sectional view taken along line IIb-IIb' of Figure 1

[0020] Figure 2C is a cross-sectional view taken along line IIc-IIc' of Figure 1

[0021] Figure 3 is a graph showing a folding stress applied to a foldable display apparatus according to an exemplary embodiment of the present disclosure.

[0022] Figure 4 is a plan view showing an arrangement of spacers in a foldable display apparatus according to an exemplary embodiment of the present disclosure.

[0023] Figure 5 is a cross-sectional view of the foldable display apparatus shown in Figure 4 when folded.

[0024] Figure 6 is a plan view showing an arrangement of spacers in a foldable display apparatus according to another exemplary embodiment of the present disclosure.

[0025] Figure 7 is a cross-sectional view of the foldable display apparatus shown in Figure 6 when folded.

[0026] Figure 8 is a plan view showing an arrangement of spacers in a foldable display apparatus according to yet another exemplary embodiment of the present disclosure.

[0027] Figure 9 is a plan view showing an arrangement of spacers in a foldable display apparatus according to yet another exemplary embodiment of the present disclosure.

[0028] Figure 10 is a plan view showing an arrangement of spacers in a foldable display apparatus according to yet another exemplary embodiment of the present disclosure.

[0029] Figure 11 is a plan view showing an arrangement of spacers in a foldable display apparatus according to yet another exemplary embodiment of the present disclosure.

[0030] Figure 12 is a plan view showing an arrangement of spacers in a foldable display apparatus according to yet another exemplary embodiment of the present disclosure.

[0031] Figure 13 ​​​is when folded Figure 12 A cross-sectional view of the foldable display apparatus illustrated in FIG. 1B. DETAILED DESCRIPTION

[0032] Advantages and characteristics of the present disclosure and methods of achieving the advantages and characteristics will become apparent by referring to the following detailed description of exemplary embodiments with reference to the attached drawings. Figure 1 However, the present disclosure is not limited to the exemplary embodiments disclosed herein but can be implemented in various forms. The exemplary embodiments are provided by way of example only so that those of ordinary skill in the art can completely understand and appreciate the content disclosed in the present disclosure and the scope of the present disclosure. Therefore, the present disclosure will be limited only by the scope of the claims attached hereto.

[0033] The shapes, sizes, ratios, angles, numbers, and the like shown in the drawings for describing the exemplary embodiments of the present disclosure are merely examples and the present disclosure is not limited thereto. Throughout the specification and drawings, like reference numerals generally designate like elements throughout the specification and drawings. Furthermore, detailed descriptions of known related technologies can be omitted in the following description of the present disclosure to avoid unnecessarily obscuring the subject matter of the present disclosure. The terms used herein, such as "include," "have," and "comprise," are generally intended to allow for addition of other elements, unless the context clearly indicates otherwise. Any reference to singular can include plural unless explicitly indicated otherwise.

[0034] Although not explicitly stated, components are interpreted to include ordinary error ranges.

[0035] When the terms such as "on," "above," "below," or "adjacent" are used to describe the positional relationship between two components, one or more components can be located between the above two components, unless the term is used together with the term "immediately adjacent" or "directly." When an element or layer is referred to as "on" another element or layer, it can be directly on the other element or layer, or there can be an intervening element or layer. It will be understood that when one element is referred to as being "connected to" or "coupled to" another element, it can be directly connected to or directly coupled to the other element, connected to or coupled to the other element with a further element interposed therebetween, or "connected to" or "coupled to" the other element via the further element.

[0036] Although the terms "first," "second," and the like are used to describe various components, the components are not limited by these terms. The terms are used only to distinguish one component from another component. Thus, the first component mentioned below in the technical concept of the present disclosure can be the second component.

[0037] The sizes and thicknesses of each component shown in the drawings represent those that facilitate explanation and the present disclosure is not necessarily limited to the sizes and thicknesses of each component shown.

[0038] The features of various embodiments of the present disclosure can be partially or wholly followed or combined with each other, and can interact and operate with each other in technically various ways as understood by those skilled in the art, and can be executed independently of or in association with each other.

[0039] Hereinafter, the present disclosure will be described in detail with reference to the accompanying drawings.

[0040] Figure 1 is a plan view of a foldable display device according to an exemplary embodiment of the present disclosure. For convenience of explanation, Figure 1 Various components of the foldable display device 100 are illustrated.

[0041] The organic light emitting display panel 110 is configured to display an image. In the organic light emitting display panel 110, an organic light emitting element for displaying an image, a circuit for driving the organic light emitting element, a wire, and other components can be arranged.

[0042] The organic light emitting display panel 110 includes a display area AA, a non-display area NA, a folding area FA, and a non-folding area NFA.

[0043] The display area AA is configured to display an image, and a plurality of pixels composed of organic light emitting elements are arranged in the display area AA. An organic light emitting element for displaying an image and a circuit unit for driving the organic light emitting element can be arranged in the display area AA. In the present disclosure, for convenience of explanation, the foldable display device 100 including the organic light emitting display panel 110 including the organic light emitting element is described, but the present disclosure is not limited thereto.

[0044] The circuit unit can include various thin film transistors, capacitors, and wires for driving the organic light emitting element. For example, the circuit unit can include various components such as a driving thin film transistor, a switching thin film transistor, a storage capacitor, a gate line, and a data line, but can not be limited thereto.

[0045] The non-display area NA indicates an area in which an image is not displayed, and a circuit, a wire, and other components for driving the organic light emitting element in the display area AA are arranged in the non-display area NA. In addition, various ICs such as a gate driver IC, a data driver IC, and a driving circuit can be arranged in the non-display area NA. For example, the various ICs and the driving circuit can be mounted on the non-display area NA of the organic light emitting display panel 110 by a gate-in-panel (GIP) method. As another example, the various ICs and the driving circuit can be connected to the organic light emitting display panel 110 by a tape carrier package (TCP) or a chip on film (COF) method.

[0046] The organic light-emitting display panel 110 can be defined as a display area AA and a non-display area NA, or it can be defined as a folded area FA and a non-folded area NFA.

[0047] The folding region (or folding unit) FA refers to the folding area of ​​the organic light-emitting display panel 110 when the foldable display device 100 is folded. The folding region FA may include a portion of the display area AA and a portion of the non-display area NA. In this disclosure, the folding region FA is described as including a portion of the display area AA and a portion of the non-display area NA, but it is not limited thereto. The non-display area NA may exist only in the area outside the display area AA. Therefore, in some embodiments, the folding region FA may include only a portion of the display area AA.

[0048] The folded region FA can be folded around the folding axis with a specific radius of curvature. Figures 2A-2C In the embodiments shown, the folding axis may be the X-axis. When the folding region FA is folded around the folding axis, the folding region FA may form a portion of a circle or ellipse. In this case, the radius of curvature of the folding region FA represents the radius of the circle or ellipse corresponding to that portion of the circle or ellipse formed by the folding region FA. In some embodiments, the folding axis is described as being located within the folding region FA in the X-axis direction, and the non-folding region NFA is described as extending from the folding region FA in a Y-axis direction that intersects the X-axis direction, for example, perpendicular to the folding axis. However, this disclosure is not limited thereto.

[0049] The non-folding area (or non-folding unit) NFA refers to the non-folding area of ​​the organic light-emitting display panel 110 when the foldable display device 100 is folded. That is, the non-folding area NFA represents the flat area of ​​the organic light-emitting display panel 110 when the foldable display device 100 is folded. The non-folding area NFA may include a portion of the display area AA and a portion of the non-display area NA.

[0050] The non-folding region NFA can be located on both sides of the folding region FA. That is, the non-folding region NFA can represent a region extending in the Y-axis direction based on the folding axis. In this document, the folding region FA can be defined between the non-folding regions NFA. Therefore, when the organic light-emitting display panel 110 is folded about the folding axis, the non-folding regions NFA can face each other.

[0051] In the following text, reference will be made to Figure 2A The foldable display device 100 is described in more detail.

[0052] Figure 1 It is along Figure 2B The cross-sectional view taken from line Ⅱa-Ⅱa'. Figure 1 It is alongFigure 2C a cross-sectional view taken along line IIb-IIb' of FIG. 2B. Figure 1 is a cross-sectional view taken along line IIc-IIc' of FIG. 2C. Figure 2A is a cross-sectional view taken along line IIb-IIb' of FIG. 2B. Figure 2B is a cross-sectional view taken along line IIc-IIc' of FIG. 2C, and Figure 2C and Figures 2A-2C is a cross-sectional view taken along line IIc-IIc' of FIG. 2C.

[0053] The foldable display device 100 according to an exemplary embodiment of the disclosure as shown in FIG. 1A is a top emission type foldable display device 100 in which light emitted from an organic light emitting element 130 of an organic light emitting display panel 110 is released to an upper portion of the organic light emitting display panel 110 through a cathode. However, the disclosure is not limited to the top emission type foldable display device 100, but can be applied to a bottom emission type and a dual side emission type foldable display device. Figures 2A-2C The substrate 101 is configured to support various components of the foldable display device 100. The substrate 101 can be a flexible substrate 101 formed of a plastic material having flexibility and thus can be foldable. In this document, when the substrate 101 is folded about a folding axis, the foldable display device 100 can be folded. For example, in the case where the substrate 101 is formed of polyimide (PI), a support substrate formed of glass is disposed under the substrate 101 during a manufacturing process of the substrate 101. After the manufacturing process of the substrate 101, the support substrate can be released. Further, after the support substrate is released, a back plate for supporting the substrate 101 can be disposed under the substrate 101. In addition to the plastic material, the substrate 101 applicable to the foldable display device 100 can be formed of other materials having flexibility as long as the material does not break even when the foldable display device 100 is repeatedly folded.

[0054]

[0055] The thin film transistor 120 is disposed on the substrate 101. The thin film transistor 120 includes an active layer 121 formed of polysilicon, a gate electrode 124, a source electrode 122, and a drain electrode 123. The thin film transistor 120 has a top gate structure in which the gate electrode 124 is disposed on the active layer 121. For convenience of explanation, Figures 2A-2C A driving thin film transistor among various thin film transistors that can be included in the foldable display device 100 is shown. However, other thin film transistors, for example, a switching thin film transistor, can also be included in the foldable display device 100. Further, in the disclosure, the thin film transistor 120 has been described as having a coplanar structure. However, the thin film transistor 120 can be implemented to have other structures, for example, a staggered structure. Further, in the disclosure, the thin film transistor 120 has been described as having a single gate structure. However, the thin film transistor 120 can be implemented to have a double gate structure. Figures 2A-2C ​The thin film transistor 120 is shown as being disposed on the substrate 101. However, the present disclosure is not limited thereto. A plurality of buffer layers can be disposed between the substrate 101 and the thin film transistor 120 based on the type or material of the substrate 101 and the structure and type of the thin film transistor 120.

[0056] The active layer 121 of the thin film transistor 120 is disposed on the substrate 101. The active layer 121 includes a channel region in which a channel is formed when the thin film transistor 120 is driven, and a source region and a drain region on both sides of the channel region. The channel region, the source region, and the drain region can be defined by ion doping (impurity doping).

[0057] The active layer 121 of the thin film transistor 120 can be formed of polysilicon. Accordingly, an amorphous silicon (a-Si) material is deposited on the substrate 101 and polysilicon is formed by performing one or more of a dehydrogenation process, a crystallization process, an activation process, and a hydrogenation process thereon. The active layer 121 can be formed by patterning the polysilicon. If the active layer 121 is formed of polysilicon, the thin film transistor 120 can be an LTPS thin film transistor 120 formed of low temperature polysilicon (LTPS). The polysilicon material has a high mobility. Accordingly, if the active layer 121 is formed of polysilicon, it has advantages of, for example, low power consumption and excellent reliability.

[0058] In other embodiments, the active layer 121 of the thin film transistor 120 can be formed of an oxide semiconductor material. The active layer 121 of the thin film transistor 120 can be formed of a metal oxide such as indium gallium zinc oxide (IGZO), but can not be limited thereto. The oxide semiconductor material has a higher band gap than a silicon material. Accordingly, electrons cannot pass through the band gap in an off state, and thus the off current is low.

[0059] The gate insulating layer 102 is disposed on the active layer 121. The gate insulating layer 102 can be formed as a single layer of an inorganic material such as silicon nitride (SiNx) or silicon oxide (SiOx), or a plurality of layers of silicon nitride (SiNx) or silicon oxide (SiOx). Contact holes of the source electrode 122 and the drain electrode 123 are formed in the gate insulating layer 102 for contacting the source region and the drain region of the active layer 121, respectively. For ease of explanation, Figure 2A The gate insulating layer 102 is shown as being planarized. However, the gate insulating layer 102 can be formed along the shape of a component disposed below the gate insulating layer 102.

[0060] The gate electrode 124 is disposed on the gate insulating layer 102. The gate electrode 124 is formed by forming a metal layer such as molybdenum (Mo) on the gate insulating layer 102 and then patterning the metal layer. The gate electrode 124 is disposed on the gate insulating layer 102 to overlap the channel region of the active layer 121.

[0061] An interlayer insulating layer 103 is disposed on the gate electrode 124. The interlayer insulating layer 103 can be formed as a single layer or multiple layers of inorganic materials such as silicon nitride (SiNx) or silicon oxide (SiOx). Contact holes for the source electrode 122 and the drain electrode 123 are formed in the interlayer insulating layer 103 for contacting the source region and drain region of the active layer 121, respectively. For ease of explanation, Figure 2A The interlayer insulation layer 103 is shown as a planarized layer. However, the interlayer insulation layer 103 may be formed along the shape of the component disposed below the interlayer insulation layer 103.

[0062] An active electrode 122 and a drain electrode 123 are disposed on the interlayer insulating layer 103. The source electrode 122 and the drain electrode 123 may be formed of a conductive metal material and may have a three-layer structure such as titanium (Ti), aluminum (Al), and titanium (Ti). The source electrode 122 and the drain electrode 123 may be connected to the source region and the drain region of the active layer 121, respectively, through contact holes included in the gate insulating layer 102 and the interlayer insulating layer 103.

[0063] A planarization layer (or first insulating layer) 105 is disposed on the thin-film transistor 120. Hereinafter, the planarization layer 105 can cover and protect the thin-film transistor 120. Furthermore, the planarization layer 105 can planarize the upper portion of the thin-film transistor 120, thus allowing for more reliable formation of the organic light-emitting element 130. Hereinafter, the planarization layer 105 may include contact holes for contact between the anode electrode 131 of the organic light-emitting element 130 and the thin-film transistor 120.

[0064] An organic light-emitting element 130 is disposed on the planarization layer 105. The organic light-emitting element 130 includes an anode electrode 131 formed on the planarization layer 105 and electrically connected to the drain electrode 123 of the thin-film transistor 120. Furthermore, the organic light-emitting element 130 includes an organic light-emitting layer 132 disposed on the anode electrode 131 and a cathode electrode 133 formed on the organic light-emitting layer 132. In this document, the anode electrode 131 may be formed on the planarization layer 105 and electrically connected to the thin-film transistor 120 through contact holes included in the planarization layer 105. Figure 2B In the illustrated embodiment, the foldable display device 100 is implemented as a top-emitting type. Therefore, the anode electrode 131 may include a reflective layer configured to reflect light emitted from the organic light-emitting layer 132 toward the cathode electrode 133 and a transparent conductive layer configured to provide holes to the organic light-emitting layer 132. In some embodiments, the anode electrode 131 may consist only of the transparent conductive layer, while the reflective layer may be defined as a component discrete from the anode electrode 131.

[0065] The organic light emitting layer 132 is configured to emit light of a specific color and can include one of a red organic light emitting layer, a green organic light emitting layer, a blue organic light emitting layer, and a white organic light emitting layer. If the organic light emitting layer 132 includes a white organic light emitting layer, a color filter configured to convert white light emitted from the white organic light emitting layer into light of another color can be disposed on the organic light emitting element 130. The organic light emitting layer 132 can further include various organic layers and / or inorganic layers such as a hole transport layer, a hole injection layer, an electron injection layer, and an electron transport layer.

[0066] The cathode electrode 133 can be formed of a transparent conductive material. For example, the cathode electrode 133 can be formed to include a transparent conductive oxide such as indium zinc oxide (IZO), or ytterbium (Yb).

[0067] A sealing unit 140 can be stacked on the cathode electrode 133. Herein, the sealing unit 140 can have a structure in which inorganic layers and organic layers are alternately stacked. Accordingly, the sealing unit 140 can protect the organic light emitting element 130 from moisture and / or oxygen by inhibiting the organic light emitting element 130 from being exposed to moisture and / or oxygen.

[0068] A bank (or a second insulating layer) 107 is disposed on the anode electrode 131 and the planarization layer 105. Herein, the bank 107 is located on the planarization layer 105 and can cover a portion of the periphery of the anode electrode 131 and a contact hole included in the planarization layer 105. The bank 107 is positioned adjacent to pixels disposed in the display area AA so as to separate the pixels. Accordingly, the bank 107 is considered to define each pixel area. The bank 107 can be formed of an organic material. For example, the bank 107 can be formed of a polyimide, an acrylic, or a benzocyclobutene (BCB)-based resin, but can not be limited thereto.

[0069] The spacers 150, 160, and 170 are disposed on the bank 107. An array of the spacers 150, 160, and 170 can be positioned between pixels composed of the organic light emitting element 130. Herein, the spacers 150, 160, and 170 can be positioned adjacent to the organic light emitting layer 132. The spacers 150, 160, and 170 can protect the organic light emitting layer 132 from an external impact when the foldable display apparatus 100 is folded. Accordingly, the spacers 150, 160, and 170 can inhibit the occurrence of lifting caused by low adhesion strength of the organic light emitting layer 132. Accordingly, the spacers 150, 160, and 170 can inhibit peeling of the organic light emitting layer 132.

[0070] In spacers 150, 160, and 170, spacers 160 and 170 in the folded region FA may differ from spacer 150 in at least one of the following: shape, number, position, density, and area size. For example, a first density of spacers in the non-folded region NFA may differ from a second density of spacers in the folded region FA. In some embodiments, the second density is at least twice the first density. Hereinafter, dual-function spacers 160 and 170 may be arranged in the folded region FA. Dual-function spacers 160 and 170 can improve the folding ease of the foldable display device 100 and suppress brightness degradation.

[0071] like Figure 2C As shown, the spacers 150 arranged in the non-folded region NFA may differ in structure and arrangement from the dual-function spacers 160 and 170 arranged in the folded region FA. Since the dual-function spacers 160 and 170 are closer to the folding axis of the folded region FA, at least one of their shape, number, position, density, and area size may be different.

[0072] Specifically, in the spacers 150 arranged in the non-folding region NFA, the maximum dimension of the spacers 150 extends in a direction intersecting (e.g., perpendicular to) the folding axis. For example, a rectangular spacer 150 arranged in the non-folding region NFA has a width extending in the Y-axis direction (e.g., perpendicular to the folding axis) and a length extending in the X-axis direction, wherein the width is greater than the length. In contrast, in the dual-function spacers 160 and 170 arranged in the folding region FA, the minimum dimension of the dual-function spacers 160 and 170 extends in a direction intersecting (e.g., perpendicular to) the folding axis.

[0073] In addition, such as Figure 3 and Figure 3 As shown, among the dual-function spacers 160 and 170 arranged in the folding region FA, the maximum dimensions of the dual-function spacers 160 and 170 extend in the same direction as the folding axis, such as the X-axis. In this document, the first dual-function spacer 160 and the second dual-function spacer 170 may have different lengths and / or widths. For example, the width of the first dual-function spacer 160 extending in the folding axis direction may have a smaller length than the width of the second dual-function spacer 170 extending in the folding axis direction.

[0074] In the bifunctional spacers 160 and 170, the other scale intersecting the scale with the minimum length can have the maximum length. In this case, the scale with the minimum length in the bifunctional spacers 160 and 170 is located in the direction intersecting the folding axis, for example, the short axis perpendicular to the folding axis. Furthermore, the other scales with the maximum length in the bifunctional spacers 160 and 170 are located in the direction of the folding axis, for example, the long axis parallel to or aligned with the folding axis. Therefore, the intersecting short and long axes of the bifunctional spacers 160 and 170 can intersect each other (e.g., perpendicularly). That is, the bifunctional spacers 160 and 170 arranged in the folded region FA can extend in the X-axis direction and have the maximum scale in the X-axis direction and the minimum scale in the Y-axis direction. In this document, the bifunctional spacers 160 and 170 arranged in the folded region FA need to protect the organic light-emitting layer 132 from breakage by external impact. Therefore, the width of the bifunctional spacers 160 and 170 in the Y-axis direction should be, for example, at least 2 micrometers. Furthermore, the heights of the dual-function spacers 160 and 170 should be less than the height of the package unit 140. For example, if the package unit 140 has a height of 3.5 micrometers, then the dual-function spacers 160 and 170 can have a height of 3 micrometers.

[0075] The substrate 101 is folded around the folding axis of the folding region FA and can therefore elongate in the Y-axis direction. The minimum dimensions of the dual-functional spacers 160 and 170 can be located in the elongation direction of the folded substrate 101. That is, the minor axis of the dual-functional spacers 160 and 170 can have the same direction as the elongation direction of the folded substrate 101. Therefore, the elongation of the dual-functional spacers 160 and 170 in the Y-axis direction can be reduced or minimized. In other words, when the substrate 101 is folded around the folding axis of the folding region FA, the elongation of the dual-functional spacers 160 and 170 can be reduced or minimized. Therefore, when the foldable display device 100 is folded, the folding stress applied to the dual-functional spacers 160 and 170 can be reduced or minimized.

[0076] The dual-functional spacers 160 and 170 arranged in the folded region FA and the spacer 150 arranged in the unfolded region NFA can be tapered spacers. When viewed from one side, the tapered spacers represent trapezoidal spacers, and when viewed from one side, the inverted tapered spacers represent inverted trapezoidal spacers. During the deposition process of the tapered spacers, particle generation can be reduced or minimized compared to inverted tapered spacers. Therefore, the dual-functional spacers 160 and 170 arranged in the folded region FA and the spacer 150 arranged in the unfolded region NFA can be formed as tapered spacers using the same process. That is, the dual-functional spacers 160 and 170 arranged in the folded region FA and the spacer 150 arranged in the unfolded region NFA can have the same shape.

[0077] Furthermore, the inverted trapezoidal tapered spacer has an increased area towards its top but can be thinner compared to a trapezoidal tapered spacer. When the foldable display device 100 is folded, one end of the inverted tapered spacer may break due to the folding stress applied to the spacer. Therefore, the inverted tapered spacer may generate particles due to breakage in the spacer caused by folding stress. The tapered spacer has an increased thickness towards its top end, thus reducing or minimizing breakage in the spacer caused by folding stress. Therefore, the tapered spacer can reduce or minimize particle generation. When the foldable display device 100 is viewed from one side, the dual-function spacer 160 arranged in the folding region FA can be a trapezoidal spacer. Therefore, the dual-function spacers 160 and 170 arranged in the folding region FA can be tapered spacers, thus reducing or minimizing folding stress.

[0078] The maximum base angle θ" of the dual-function spacers 160 and 170 can be greater than the maximum base angle θ′ of the spacer 150 arranged in the non-folding region NFA. In some embodiments, the upper surfaces of the dual-function spacers 160 and 170 arranged in the folding region FA can have a larger area size than the upper surface of the spacer 150 arranged in the non-folding region NFA. When the foldable display device 100 is folded, folding stress is transferred to the upper surfaces of the dual-function spacers 160 and 170. Herein, the folding stress per unit area size applied to the dual-function spacers 160 and 170 is related to the folding stress per unit area size of the dual-function spacers. The area dimensions of the upper surfaces of spacers 160 and 170 are inversely proportional. Therefore, as the area dimensions of the upper surfaces of the dual-function spacers 160 and 170 increase, folding stress can be dispersed. That is, the area dimensions of the upper surfaces of the dual-function spacers 160 and 170 arranged in the folded region FA can be set to be larger than the area dimensions of the upper surface of the spacer 150 arranged in the non-folded region NFA. Therefore, folding stress can be dispersed. In this document, if the dual-function spacers 160 and 170 have a structure capable of dispersing folding stress, their upper surfaces can have rhomboid, polygonal, rectangular, or other types of shapes.

[0079] Because the dual-function spacers 160 and 170 arranged in the folding region FA have structures that can disperse, reduce, or minimize folding stress, breakage can be suppressed when the foldable display device 100 is folded. Therefore, the ease of folding the foldable display device 100 can be improved.

[0080] Furthermore, because the occurrence of breakage in the dual-functional spacers 160 and 170 arranged in the folding region FA is suppressed, the generation of particles caused by breakage in the spacers can be reduced or minimized. Particles generated by breakage in the spacers can penetrate into the organic light-emitting layer 132 and cause a change in the height of the organic light-emitting layer 132. In addition, particles generated by breakage in the spacers may stimulate the organic light-emitting layer 132 and cause it to break. If the height of the organic light-emitting layer 132 changes or breaks, dark spots may be generated in the foldable display device 100. These dark spots can be defects in the foldable display device 100. Therefore, the dual-functional spacers 160 and 170, which suppress the occurrence of breakage by reducing folding stress, can reduce or minimize particle generation. Therefore, changes in the height of the organic light-emitting layer 132 or breakage in the organic light-emitting layer 132 caused by particles can be reduced or minimized. Therefore, the generation of dark spots can be suppressed, thereby suppressing the reduction in brightness of the foldable display device 100.

[0081] In this case, the area size of spacers 150, 160, and 170 can account for, for example, 0.25% to 1.25% of the total area size of the display area AA of the foldable display device 100. The area size of spacers 150, 160, and 170 can be determined by taking into account various factors such as pixel size, TFT arrangement, spacer arrangement, and manufacturing process.

[0082] Specifically, the area size of the spacer 150 arranged in the non-folding region NFA can account for, for example, 0.45% to 0.5% of the total area size of the non-folding region NFA. The area size of the spacers 160 and 170 arranged in the folding region FA can account for, for example, 0.45% to 1% of the total area size of the non-folding region NFA. In this document, considering the folding stress applied to the dual-function spacers 160 and 170 when the foldable display device 100 is folded, the dual-function spacers 160 and 170 arranged in the folding region FA can have a larger area size compared to the spacer 150 arranged in the non-folding region NFA.

[0083] In some embodiments, each pixel or some pixels in the foldable display device 100 may have a different size. Therefore, dual-function spacers 160 and 170 arranged adjacent to the pixels can be formed taking into account the pixel size. A pixel may include multiple sub-pixels, and each sub-pixel may correspond to at least one of the dual-function spacers 160 and 170. In this case, the size of the corresponding dual-function spacers 160 and 170 can vary according to the size of each sub-pixel. As the size of the dual-function spacers 160 and 170 decreases, adjacent pixels can be formed to have a larger size. Therefore, for example, since brightness is proportional to pixel size, the brightness of the foldable display device 100 can be increased. Therefore, the dual-function spacers 160 and 170 can be arranged in the folding region FA by increasing the density (or number) of the smaller dual-function spacers 160 and 170 in the regions of the dual-function spacers 160 and 170. That is, the density of the dual-functional spacers 160 and 170 can be increased by forming multiple smaller dual-functional spacers 160 and 170 in the same area instead of a single dual-functional spacer 160 and 170. Therefore, the folding stress applied to the dual-functional spacers 160 and 170 can be reduced or minimized, and the sub-pixels adjacent to the dual-functional spacers 160 and 170 can be formed to have a larger size. Therefore, the brightness of the foldable display device 100 can be improved.

[0084] In this document, the bifunctional spacer 160 may be formed of, for example, acrylic-based materials, polyimide, polyamide, carbon compounds, or silicone-based materials, but is not limited thereto.

[0085] Furthermore, the dual-functional spacers 160 and 170 located on the embankment 107 can be located within contact holes included in the planarization layer 105. A portion of the anode electrode 131 can be located within contact holes included in the planarization layer 105 for electrical connection with the thin-film transistor 120. When the foldable display device 100 is folded, light emitted from the organic light-emitting layer 132 may be irregularly reflected by a portion of the anode electrode 131 located in the contact holes. Therefore, the contact holes of the foldable display device 100 become visible, or dark spots may be generated in the pixels due to light interference. In this case, a portion of the dual-functional spacers 160 and 170 can overlap with the contact holes included in the planarization layer 105. Furthermore, a portion of the dual-functional spacers 160 and 170 can also overlap with a portion of the anode electrode 131 located in the contact holes. Therefore, the dual-functional spacers 160 and 170 can reduce or minimize reflections within the panel by blocking the contact holes. In this case, a single dual-functional spacer 160 and 170 can not only block the contact holes but also block another contact hole present in an adjacent pixel. That is, a single dual-function spacer 160 and 170 can block multiple contact holes.

[0086] Therefore, the visibility of the contact holes in the foldable display device 100 and the generation of dark spots caused by light interference can be reduced or minimized. Thus, the efficiency of suppressing brightness reduction in the foldable display device 100 can be improved.

[0087] In this document, the dual-function spacers 160 and 170 arranged in the folded region FA may include spacer stabilizing structures. Referring below... Figure 3 Describe the spacer's stable structure.

[0088] Figure 3 It is a graph showing the folding stress applied to a foldable display device 100 according to an exemplary embodiment of the present disclosure. Figure 3 The diagram illustrates the compressive and tensile forces applied to the layers arranged above and below the neutral surface when the foldable display device is folded. Figure 3 The X-axis in the chart represents strain (%) and the Y-axis represents the thickness of the foldable display device.

[0089] For ease of explanation, Figures 2A-2C The diagram shows a substrate L1, a thin-film transistor L2, and a packaging unit L3 laminated sequentially. Other components may be arranged between these structures.

[0090] Figures 4-7 The inward fold lines (e.g., an inward fold diagram) illustrate the folding stress applied when the foldable display device 100 is folded inward and the image display units face each other. In this case, the image display units may be located between the thin-film transistor L2 and the packaging unit L3. Furthermore, the outward fold lines (e.g., an outward fold diagram) illustrate the folding stress applied when the foldable display device 100 is folded outward and the substrate support units face each other. In this case, the substrate support units may be located under the substrate L1.

[0091] The neutral plane NP represents a virtual surface that is not subjected to stress because the compressive and tensile forces applied to the foldable display device 100 cancel each other out when the foldable display device 100 is folded. Therefore, the strain on the neutral plane NP is 0%.

[0092] When the foldable display device 100 is folded inward, the neutral plane NP of the folded diagram can be located above the thin-film transistor L2. In this case, a portion of the thin-film transistor L2 and the substrate L1 located below the thin-film transistor L2 are stretched and thus can be subjected to tensile force. Furthermore, other components and the packaging unit L3 arranged on the thin-film transistor L2 are compressed and thus can be subjected to compressive force.

[0093] Furthermore, when the foldable display device 100 is folded outward, the neutral plane NP of the folded diagram can be located on top of the thin-film transistor L2. In this case, a portion of the thin-film transistor L2 and the substrate L1 located below the thin-film transistor L2 are compressed, thus a compressive force can be applied. In addition, other components and the packaging unit L3 arranged on the thin-film transistor L2 are stretched, thus a tensile force can be applied.

[0094] When the foldable display device 100 is folded, the tensile and / or compressive forces applied to the components in the folding region FA become folding stresses. Therefore, the components arranged in the folding region FA may break. Thus, it is necessary to design the components arranged in the folding region FA to reduce or minimize the folding stresses applied to them.

[0095] Therefore, as Figure 4 As shown, the dual-function spacers 160 and 170 located in the folding region FA can have a spacer stabilization structure. In the spacer stabilization structure, the dual-function spacers 160 and 170, which have different area sizes from each other, are arranged in a direction intersecting (e.g., perpendicular to) the folding axis. Herein, the area sizes of the dual-function spacers 160 and 170 can be decreased or increased based on their distance to the folding axis of the folding region FA. In some embodiments, the area sizes of the dual-function spacers 160 and 170 can be continuously varied.

[0096] In the following text, reference will be made to Figure 6 The spacer stabilization structure of the foldable display device 100 is described in more detail.

[0097] Figure 4 and Figure 6 This is a plan view illustrating the arrangement of spacers in a foldable display device according to an exemplary embodiment of the present disclosure. Figure 5 and Figure 4 This is a plan view showing the structure and arrangement of the spacers included in the foldable display device 100 and the foldable display device 200, respectively. Figure 5 When folded Figure 7 The cross-sectional view of the foldable display device 100 shown in the figure. Figure 6 This is a cross-sectional view showing the arrangement of spacers when the foldable display device 100 is folded inward. Figure 7 When folded Figure 4 The cross-sectional view of the foldable display device 200 shown in the figure. Figure 5 This is a cross-sectional view showing the arrangement of the spacers when the foldable display device is folded outwards. Since the construction, position, and materials of other components are the same as those of other components in the foldable display device described above according to the embodiment, redundant descriptions will be omitted.

[0098] like Figure 5 and Figure 5 As shown, the foldable display device 100 can be folded inward (or folded inward) about the folding axis of the folding region FA. The direction of the folding axis in this document can refer to any dashed line in the folding region FA of the foldable display device 100 having a direction substantially perpendicular to a plane that includes any one of the radii of curvature of the folding region FA.

[0099] like Figure 7 As shown, the folding axes may overlap with some spacers, but do not necessarily have to. For example, some folding axes overlap with dual-function spacers 160 and 170, while some folding axes do not overlap with spacers. In some embodiments, the folding region FA may include, for example, multiple folding axes for inward folding, outward folding, or S-folding. The folding axes may be located in the foldable display device 100 (e.g., Figure 5 On the inner and outer surfaces (as shown in the figure) Figure 4 (as shown) or between the inner and outer surfaces, for example Figure 4 The folding shaft 500D is shown in the image.

[0100] In this configuration, the organic light-emitting layers on the thin-film transistors 120 of the foldable display device 100 can face each other. Therefore, the image display units of the foldable display device 100 can face each other. Consequently, the dual-functional spacers 160 and 170 on the thin-film transistors 120, located on a neutral plane, can be compressed and subjected to compressive force.

[0101] Furthermore, when the foldable display device 100 is folded inward, the compressive force applied to the dual-function spacers 160 and 170 can be increased based on the distance between the dual-function spacers 160 and 170 and the folding axis in the Y-axis direction. That is, the folding stress applied to the dual-function spacers 160 and 170 can increase as the distance between the dual-function spacers 160 and 170 and the folding axis in the Y-axis direction increases.

[0102] In this paper, as the area size of the individual dual-function spacers 160 and 170 increases, the folding stress to be dispersed by the individual dual-function spacers 160 and 170 can be increased. Therefore, dual-function spacers 160 and 170 arranged in areas where folding stress is applied (e.g., greater than the stress in other areas) can reduce or minimize folding stress by increasing the area size of the individual dual-function spacers 160 and 170.

[0103] When the foldable display device 100 is folded inward, the folding stress applied to the dual-function spacers 160 and 170 increases as the spacers 160 and 170 are positioned further away from the folding axis in the Y-axis direction. Therefore, in the foldable display device 100, the size of the dual-function spacer 160 is smaller than that of the dual-function spacer 170, and the dual-function spacer 170 is further away from the folding axis than the dual-function spacer 160. Thus, the folding stress can be reduced or minimized.

[0104] exist Figure 6 In the implementation of the method, the dual-function spacers 160 and 170 can be divided into a first dual-function spacer 160 and a second dual-function spacer 170.

[0105] The first dual-function spacer 160 located in the folding region FA may have a first width 161 and a second width 163 shorter than the first width 161. Furthermore, the second dual-function spacer 170 located in the folding region FA may have a third width 171 and a fourth width 173 shorter than the third width 171. In this document, the first width 161 and the third width 171 may be in the same direction as the extension direction of the folding axis (e.g., the X-axis).

[0106] Furthermore, the length of the first width 161 of the first dual-function spacer 160 is shorter than the third width 171 of the second dual-function spacer 170. Furthermore, the length of the second width 163 of the first dual-function spacer 160 is shorter than the fourth width 173 of the second dual-function spacer 170.

[0107] Therefore, the area size of the first dual-function spacer 160 in the folded region FA can be smaller than the area size of the second dual-function spacer 170. In this document, a plurality of first dual-function spacers 160 can be spaced apart from each other at a specific distance in the X-axis direction to form a first column (or row) 1160. Furthermore, a plurality of second dual-function spacers 170 can be spaced apart from each other at a specific distance in the X-axis direction to form a second column (or row) 1170.

[0108] The folded area FA also includes a third column 2160 consisting of a plurality of spacers having the same size and construction as the first dual-function spacer 160 included in the first column (or row) 1160. Furthermore, the folded area FA includes a fourth column 2170 consisting of a plurality of spacers having the same size and construction as the second dual-function spacer 170 included in the second column (or row) 1170.

[0109] The spacer stabilizing structure, consisting of the first dual-function spacer 160 and the second dual-function spacer 170, can be arranged such that the first column 1160, consisting of a plurality of first dual-function spacers 160, is adjacent to the folding axis. Furthermore, in the spacer stabilizing structure, the second column 1170, consisting of a plurality of second dual-function spacers 170, can be further away from the folding axis than the first column 1160 consisting of a plurality of first dual-function spacers 160.

[0110] In this case, in the folded area FA, the first column 1160 and the third column 2160 can be arranged adjacent to each other and between the second column 1170 and the fourth column 2170.

[0111] That is, the foldable display device 100 capable of inward folding may include a spacer stabilizing structure, wherein the area size of the dual-functional spacers 160 and 170 decreases as the dual-functional spacers 160 and 170 are positioned closer to the folding axis. Therefore, when the foldable display device 100 is folded inward, the spacer stabilizing structure can distribute folding stress, thereby reducing or minimizing the folding stress applied to the dual-functional spacers 160 and 170. Therefore, when the foldable display device 100 is folded inward, the occurrence of breakage in the dual-functional spacers 160 and 170 can be suppressed. Therefore, the folding ease of the foldable display device 100 can be improved.

[0112] Furthermore, when the foldable display device 100 is folded inward, the occurrence of breakage in the first dual-functional spacer 160 or the second dual-functional spacer 170, which are arranged as spacer stabilization structures in the folding region FA, is suppressed. Therefore, the generation of particles caused by breakage in the first dual-functional spacer 160 or the second dual-functional spacer 170 in the folding region FA can be reduced or minimized. Therefore, the height change of the organic light-emitting layer 132 or the breakage in the organic light-emitting layer 132 caused by particles can be reduced or minimized. Therefore, the generation of dark spots can be suppressed, and thus the reduction in brightness of the foldable display device 100 can be suppressed.

[0113] like Figure 7 As shown, the spacer 150 arranged in the non-folded region NFA may have a seventh width 151 and an eighth width 153 that is longer than the seventh width 151. In this case, the length of the eighth width 153 is longer than the third width 171 of the second dual-function spacer 170.

[0114] like Figure 6 and Figure 6As shown, the foldable display device 200 can be folded outward about the folding axis of the folding region FA. In this case, the back surfaces of the substrate located below the thin-film transistor 120 of the foldable display device 200 can face each other. Therefore, the substrate support units of the foldable display device 200 can face each other. Therefore, the dual-functional spacers 160 and 170 on the thin-film transistor 120 are located on the neutral plane and can be stretched and subjected to a tensile force.

[0115] Furthermore, when the foldable display device 200 is folded outward, the tensile force applied to the dual-function spacers 160 and 170 can be based on the distance relative to the folding axis in the Y-axis direction. That is, the folding stress applied to the dual-function spacers 160 and 170 can increase as the distance between the dual-function spacers 160 and 170 and the folding axis decreases.

[0116] In this paper, as the area size of individual dual-function spacers 160 and 170 increases, the folding stress to be dispersed by the dual-function spacers 160 and 170 can be increased. Therefore, dual-function spacers 160 and 170 arranged in areas where folding stress is applied (e.g., greater than the stress in other areas) can reduce or minimize folding stress by increasing the area size of individual dual-function spacers 160 and 170.

[0117] When the foldable display device 200 is folded outward, the folding stress applied to the dual-function spacers 160 and 170 increases as the dual-function spacers 160 and 170 are positioned closer to the folding axis in the Y-axis direction. Therefore, in the foldable display device 200, the size of the dual-function spacer 170 adjacent to the folding axis is larger than the size of the dual-function spacer 160, which is further away from the folding axis than the dual-function spacer 160. Thus, the folding stress can be reduced or minimized.

[0118] exist Figures 8-11 In some embodiments, the dual-function spacers 160 and 170 may include a first dual-function spacer 160 and a second dual-function spacer 170.

[0119] The first dual-function spacer 160 located in the folding region FA may have a first width 161 and a second width 163 shorter than the first width 161. Furthermore, the second dual-function spacer 170 located in the folding region FA may have a third width 171 and a fourth width 173 shorter than the third width 171. In this document, the first width 161 and the third width 171 may be in the same direction as the extension direction of the folding axis.

[0120] Furthermore, the length of the first width 161 of the first dual-function spacer 160 is shorter than the third width 171 of the second dual-function spacer 170. Additionally, the length of the second width 163 of the first dual-function spacer 160 is shorter than the fourth width 173 of the second dual-function spacer 170. Therefore, the area size of the first dual-function spacer 160 in the folded region FA can be smaller than the area size of the second dual-function spacer 170.

[0121] In this document, a plurality of first dual-function spacers 160 may be spaced apart from each other at a specific distance in the X-axis direction to form a first column (or row) 1160. In addition, a plurality of second dual-function spacers 170 may be spaced apart from each other at a specific distance in the X-axis direction to form a second column (or row) 1170.

[0122] The folded area FA also includes a third column 2160 consisting of a plurality of spacers having the same size and construction as the first dual-function spacer 160 included in the first column (or row) 1160. Furthermore, the folded area FA includes a fourth column 2170 consisting of a plurality of spacers having the same size and construction as the second dual-function spacer 170 included in the second column (or row) 1170.

[0123] The spacer stabilizing structure, consisting of the first dual-function spacer 160 and the second dual-function spacer 170, can be arranged such that a second column consisting of a plurality of second dual-function spacers 170 is adjacent to the folding axis. Furthermore, in the spacer stabilizing structure, the first column consisting of a plurality of first dual-function spacers 160 can be further away from the folding axis than the second column consisting of a plurality of second dual-function spacers 170.

[0124] In this case, in the folded area FA, the second column 1170 and the fourth column 2170 can be arranged to be adjacent to each other and between the first column 1160 and the third column 2160.

[0125] That is, the foldable display device 200 capable of outward folding may include a spacer stabilizing structure, wherein the area of ​​the dual-functional spacers 160 and 170 increases as the dual-functional spacers 160 and 170 are positioned closer to the folding axis. Therefore, when the foldable display device 200 is folded outward, the spacer stabilizing structure can distribute folding stress, thereby reducing or minimizing the folding stress applied to the dual-functional spacers 160 and 170. Therefore, when the foldable display device 200 is folded outward, the occurrence of breakage in the dual-functional spacers 160 and 170 can be suppressed. Therefore, the folding ease of the foldable display device 200 can be improved.

[0126] Furthermore, when the foldable display device 200 is folded outward, the occurrence of breakage in the first dual-functional spacer 160 or the second dual-functional spacer 170, which are arranged as spacer stabilization structures in the folding region FA, is suppressed. That is, the generation of particles caused by breakage in the first dual-functional spacer 160 or the second dual-functional spacer 170 in the folding region FA can be reduced or minimized. Therefore, the height change of the organic light-emitting layer 132 or the breakage in the organic light-emitting layer 132 caused by particles can be reduced or minimized. Therefore, the generation of dark spots can be suppressed, and thus the reduction in brightness of the foldable display device 200 can be suppressed.

[0127] like Figure 8 As shown, the spacer 150 arranged in the non-folded region NFA may have a seventh width 151 and an eighth width 153 that is longer than the seventh width 151. In this case, the length of the eighth width 153 is longer than the third width 171 of the second dual-function spacer 170.

[0128] Figure 9 This is a plan view illustrating the arrangement of spacers in a foldable display device according to other exemplary embodiments of the present disclosure. Figure 4 and Figure 10 The structure and arrangement of the spacers included in the foldable display device differ from those in other devices. Figure 11 .also, Figure 6 and Figure 8 The structure and arrangement of the spacers included in the foldable display device differ from those in other devices. Figure 4 Therefore, redundant descriptions of other identical components will be omitted.

[0129] Figure 9 The spacers 350 arranged in the non-folding region NFA of the foldable display device 300 have a different structure than those in the foldable display device 300. Figure 4 . Figure 8 The spacers 350 arranged in the non-folding region NFA of the foldable display device 400 have a different structure than those in the foldable display device 400. Figure 9 In this article, Figure 8 The spacers 350 arranged in the non-folding region NFA of the foldable display device 300 shown have a relationship with Figure 9 The spacers 350 arranged in the non-folding region NFA of the foldable display device 400 shown have the same structure. Figure 8 The structure and arrangement of the spacers in the non-folding region NFA of the foldable display devices 300 and 400 differ from those in other aspects. Figure 10 Therefore, redundant descriptions of other identical components will be omitted.

[0130] like Figure 8 and 9As shown, the spacer 350 arranged in the non-folding region NFA of the foldable display devices 300 and 400 can have the same shape as the second dual-function spacer 170 arranged in the folding region FA.

[0131] Specifically, the third width 171 of the second bifunctional spacer 170 can be equal to the seventh width 351 of the spacer 350 arranged in the non-folded region NFA. The fourth width 173 of the second bifunctional spacer 170 can be equal to the eighth width 353 of the spacer 350 arranged in the non-folded region NFA. Therefore, the spacer 350 arranged in the non-folded region NFA and the second bifunctional spacer 170 can be formed by the same process. Therefore, the process for forming the spacer 350 in the non-folded region NFA and the second bifunctional spacer 170 in the folded region FA can be simplified. Therefore, the generation of particles caused by breakage in the spacers during repeated processes can be reduced or minimized.

[0132] In addition to the multiple third dual-function spacers 180 included in the folding area FA of the foldable display device 500, Figure 10 and Figure 6 They are identical. Therefore, redundant descriptions of other identical components will be omitted.

[0133] like Figure 11 As shown, the third dual-function spacer 180 is located in the folded region FA. The third dual-function spacer 180 may have a fifth width 181 and a sixth width 183 with a length shorter than the fifth width 181. In this document, the fifth width 181 may be in the same direction as the extension direction of the folding axis.

[0134] Furthermore, the length of the fifth width 181 of the third dual-function spacer 180 is shorter than the first width 161 of the first dual-function spacer 160 arranged in the folded region FA. Furthermore, the length of the sixth width 183 of the third dual-function spacer 180 is shorter than the second width 163 of the first dual-function spacer 160 arranged in the folded region FA. Therefore, the area size of the third dual-function spacer 180 in the folded region FA can be smaller than the area size of the first dual-function spacer 160.

[0135] In this document, multiple third dual-function spacers 180 may be spaced apart from each other at a specific distance in the X-axis direction (e.g., the folding axis) to form a fifth column (or row) 1180. In the folded region FA, the fifth column 1180 may be arranged between the first column 1160 and the third column 2160. Therefore, the third column 2160 may be arranged closest to the folding axis (relative to the other columns or rows) or located on the folding axis.

[0136] Therefore, the foldable display device 500 capable of inward folding may include a spacer stabilizing structure, wherein the area size of the dual-functional spacers 160, 170, and 180 decreases as the dual-functional spacers 160, 170, and 180 are positioned closer to the folding axis. That is, the dual-functional spacers 160, 170, and 180 are arranged sequentially, wherein the area size increases as the dual-functional spacers 160, 170, and 180 are positioned further away from the folding axis in the Y-axis direction. Therefore, when the foldable display device 500 is folded inward, the dispersion of the increased folding stress in the Y-axis direction can be improved. Therefore, when the foldable display device 500 is folded inward, the spacer stabilizing structure can disperse the folding stress, thereby reducing or minimizing the folding stress applied to the dual-functional spacers 160, 170, and 180. Therefore, when the foldable display device 500 is folded inward to a smaller radius of curvature, the occurrence of breakage in the dual-functional spacers 160, 170, and 180 can be suppressed. Therefore, the folding ease of the foldable display device 500 can be improved.

[0137] and Figure 11 In comparison, Figure 12 In the folding region FA of the foldable display device 600, multiple third dual-function spacers 180 are also included. Therefore, redundant descriptions of other identical components will be omitted.

[0138] like Figure 13 As shown, the third dual-function spacer 180 is located in the folded region FA. The third dual-function spacer 180 may have a fifth width 181 and a sixth width 183 with a length shorter than the fifth width 181. In this document, the fifth width 181 may be in the same direction as the extension direction of the folding axis.

[0139] Furthermore, the length of the fifth width 181 of the third dual-function spacer 180 is shorter than the first width 161 of the first dual-function spacer 160 arranged in the folded region FA. Furthermore, the length of the sixth width 183 of the third dual-function spacer 180 is shorter than the second width 163 of the first dual-function spacer 160 arranged in the folded region FA. Therefore, the area size of the third dual-function spacer 180 in the folded region FA can be smaller than the area size of the first dual-function spacer 160.

[0140] In this document, multiple third dual-function spacers 180 can be spaced apart from each other at a specific distance in the X-axis direction (e.g., the folding axis) to form a fifth column (or row) 1180. Furthermore, multiple third dual-function spacers 180 can be spaced apart from each other at a specific distance in the X-axis direction to form a sixth column (or row) 2180. In the folded region FA, the first column 1160 and the third column 2160 can be arranged between the fifth column 1180 and the sixth column 2180. Therefore, the fifth column 1180 and the sixth column 2180 can be arranged furthest relative to the folding axis (relative to the other columns or rows).

[0141] Therefore, the foldable display device 600 capable of outward folding may include a spacer stabilizing structure, wherein the area size of the dual-functional spacers 160, 170, and 180 increases as the dual-functional spacers 160, 170, and 180 are positioned closer to the folding axis. That is, the dual-functional spacers 160, 170, and 180 are arranged sequentially, wherein the area size decreases as the dual-functional spacers 160, 170, and 180 are positioned further away from the folding axis in the Y-axis direction. Therefore, when the foldable display device 600 is outward folded, the dispersion of the increased folding stress in the Y-axis direction can be improved. Therefore, when the foldable display device 600 is outward folded, the spacer stabilizing structure can disperse the folding stress, thereby reducing or minimizing the folding stress applied to the dual-functional spacers 160, 170, and 180. Therefore, when the foldable display device 600 is outward folded to a smaller radius of curvature, the occurrence of breakage in the dual-functional spacers 160, 170, and 180 can be suppressed. Therefore, the folding ease of the foldable display device 600 can be improved.

[0142] Figure 12 This is a plan view illustrating the arrangement of spacers in a foldable display device according to another exemplary embodiment of the present disclosure. Figure 13 When folded Figure 12 The image shows a cross-sectional view of the foldable display device. Figure 12 It shows when Figure 13 The diagram shows a cross-sectional view of the arrangement of spacers when the foldable display device 700 is S-folded (e.g., folded along at least two different folding axes to form an "S" shape). In addition to the structure and arrangement of the spacers included in the foldable display device 700, Figure 4 and Figure 12 and Figure 4 same.

[0143] In addition to the first column 1160, the second column 1170, the third column 2160, and the fourth column 2170 being arranged in different ways in the folding area FA of the foldable display device 700, and also including multiple third dual-function spacers 180, Figure 12 and Figure 13They are identical. Therefore, redundant descriptions of other identical components will be omitted.

[0144] like ​ As shown, the spacer 160 in the first column 1160 and the spacer 160 in the third column 2160 of the folded area FA have the same size. Furthermore, the spacer 170 in the second column 1170 and the spacer 170 in the fourth column 2170 of the folded area FA have the same size. In this case, the first column 1160 can be arranged adjacent to the fourth column 2170. Alternatively, the first column 1160 and the fourth column 2170 can be arranged between the second column 1170 and the third column 2160. Therefore, the first column 1160 (or the third column 2160) and the second column 1170 (or the fourth column 2170), which include dual-space functional partitions with different sizes from each other, are arranged in an alternating manner relative to their dimensions.

[0145] Furthermore, a third dual-function spacer 180 is positioned within the folding region FA. The third dual-function spacer 180 may have a fifth width 181 and a sixth width 183 shorter than the fifth width 181. In this document, the fifth width 181 may be in the same direction as the extension direction of the folding axis.

[0146] Furthermore, the length of the fifth width 181 of the third dual-function spacer 180 is shorter than the first width 161 of the first dual-function spacer 160 arranged in the folded region FA. Furthermore, the length of the sixth width 183 of the third dual-function spacer 180 is shorter than the second width 163 of the first dual-function spacer 160 arranged in the folded region FA. Therefore, the area size of the third dual-function spacer 180 in the folded region FA can be smaller than the area size of the first dual-function spacer 160.

[0147] In this document, multiple third dual-function spacers 180 can form a fifth column (or row) 1180 and a sixth column (or row) 2180. In the folded region FA, a second column 1170 can be arranged between the fifth column 1180 and the first column 1160. Furthermore, a fourth column 2170 can be arranged between the sixth column 2180 and the third column 2160. Therefore, the fifth column 1180 (or sixth column 2180), the second column 1170 (or fourth column 2170), and the first column 1160 (or third column 2160), comprising dual-function spacers with different dimensions, can be arranged continuously and sequentially.

[0148] In this document, the foldable display device 700 capable of S-folding may include at least two folding axes (e.g., both in the X-axis direction). The second column 1170 and the sixth column 2180 may be arranged closest to or on one of the folding axes. Therefore, the foldable display device 700 capable of S-folding can be folded around at least two folding axes.

[0149] like ​ As shown, the foldable display device 700 can be S-folded. In this document, the foldable display device 700 can be folded inwards and outwards relative to a folding axis in the folding region FA. In this case, in the inward folding portion of the foldable display device 700, the dual-function spacers 160, 170, and 180 can be subjected to a compressive force. The compressive force can increase with increasing distance relative to the folding axis. Furthermore, in the outward folding portion of the foldable display device 700, the dual-function spacers 160, 170, and 180 can be subjected to a tensile force. The tensile force can increase with decreasing distance to the folding axis.

[0150] Therefore, when the foldable display device 700 is folded inward, the folding stress applied to the dual-function spacers 160, 170, and 180 increases as the dual-function spacers 160, 170, and 180 are positioned further away from the folding axis. Furthermore, when the foldable display device 700 is folded outward, the folding stress applied to the dual-function spacers 160, 170, and 180 increases as the dual-function spacers 160, 170, and 180 are positioned closer to the folding axis.

[0151] In this configuration, the foldable display device 700 includes a spacer stabilizing structure, wherein the area dimensions of the dual-functional spacers 160, 170, and 180 increase as they are positioned further away from the folding axis in the inward folding portion, and also increase as they are positioned closer to the folding axis in the outward folding portion. Therefore, folding stress can be reduced or minimized.

[0152] That is, the S-foldable display device 700 can include a spacer stabilizing structure, wherein the dual-functional spacers 160, 170, and 180 have different area dimensions in the inward folding portion and the outward folding portion. Therefore, folding stress can be distributed. Therefore, the folding stress applied to the dual-functional spacers 160, 170, and 180 can be reduced or minimized. Therefore, when the S-foldable display device 700 is S-folded, the occurrence of breakage in the dual-functional spacers 160, 170, and 180 can be suppressed. Therefore, the folding ease of the foldable display device 700 can be improved.

[0153] Although 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 may be implemented in many different forms without departing from the technical concept of the present disclosure. Therefore, the exemplary embodiments of the present disclosure are provided for illustrative purposes only and are not intended to limit the technical spirit of the present disclosure. The scope of the technical spirit 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 scope of protection of the present disclosure should be understood based on the appended claims, and all technical concepts within the scope of their equivalents should be understood to fall within the scope of the present disclosure.

[0154] This disclosure includes, but is not limited to, the following technical solutions:

[0155] Solution 1. A foldable display device, comprising:

[0156] A display panel configured to fold about a folding axis, the display panel comprising:

[0157] The first plurality of spacers arranged in the non-folded area; and

[0158] A second plurality of spacers are arranged in the folded area. The second plurality of spacers have different dimensions from the first plurality of spacers. Each of the second plurality of spacers has a first dimension and a second dimension larger than the first dimension. The second dimension of the second plurality of spacers is in the direction of the folding axis.

[0159] Option 2. The foldable display device according to Option 1, wherein the second dimension of each of the second plurality of spacers is the maximum dimension of each spacer.

[0160] Option 3. The foldable display device according to Option 1, wherein the first dimension of each of the second plurality of spacers is the minimum dimension of each spacer, and the first dimension intersects the direction of the folding axis.

[0161] Option 4. The foldable display device according to Option 1, wherein the display panel further includes:

[0162] A planarization layer on a flexible substrate; and

[0163] The planarization layer comprises a plurality of pixels, the planarization layer including a contact hole for each of the plurality of pixels, each contact hole overlapping a portion of a corresponding spacer in the plurality of spacers.

[0164] Option 5. The foldable display device according to Option 4, wherein the display panel is an organic light-emitting display panel and each pixel includes:

[0165] An anode, which is connected to the drain electrode of the pixel's transistor via a contact hole, wherein a corresponding spacer of the second plurality of spacers overlaps with the transistor; and

[0166] The cathode overlaps with the anode and the corresponding spacer of the second plurality of spacers.

[0167] Option 6. The foldable display device according to Option 5 further includes:

[0168] An insulating layer on the anode of the plurality of pixels, wherein the second plurality of spacers are disposed between the insulating layer and the cathode of the plurality of pixels.

[0169] Option 7. The foldable display device according to Option 6 further includes:

[0170] The encapsulation unit on the cathode of the plurality of pixels has a height greater than the height of the first plurality of spacers and the second plurality of spacers.

[0171] Option 8. The foldable display device according to Option 4, wherein each of the second plurality of spacers overlaps with a plurality of contact holes of adjacent pixels in the plurality of pixels.

[0172] Option 9. The foldable display device according to Option 1, wherein the second plurality of spacers are arranged in a plurality of columns in the direction of the folding axis, each of the plurality of columns comprising a subset of the second plurality of spacers spaced apart from each other.

[0173] Option 10. The foldable display device according to Option 9, wherein at least one of the plurality of columns overlaps with the folding axis.

[0174] Option 11. The foldable display device according to Option 9, wherein the plurality of columns include at least a first column spacer having a first area and a second column spacer having a second area greater than the first area.

[0175] Option 12. The foldable display device according to Option 11, wherein the first column spacers and the second column spacers are arranged on the side of the display panel on which a compressive force is applied in response to the folding of the foldable display device, and the folding axis is positioned closer to the first column spacers than the second column spacers.

[0176] Option 13. The foldable display device according to Option 11, wherein the first column spacers and the second column spacers are arranged on the side of the display panel on which a tensile force is applied in response to the folding of the foldable display device, and the folding axis is positioned closer to the second column spacers than the first column spacers.

[0177] Option 14. The foldable display device according to Option 11, wherein the third area of ​​the first plurality of spacers is equal to the first area or the second area.

[0178] Option 15. The foldable display device according to Option 11, wherein the plurality of columns further includes a third column spacer having a third area different from each of the first area and the second area.

[0179] Option 16. The foldable display device according to Option 1, wherein each of the first plurality of spacers has a third dimension and a fourth dimension greater than the third dimension, and the fourth dimensions of the first plurality of spacers all intersect the direction of the folding axis.

[0180] Solution 17. The foldable display device according to Solution 1, wherein the first plurality of spacers and the second plurality of spacers have a trapezoidal cross section with a gradually decreasing thickness, and the first base angle of the trapezoidal cross section of the first plurality of spacers is smaller than the second base angle of the trapezoidal cross section of the second plurality of spacers.

[0181] Option 18. The foldable display device according to Option 1, wherein the display panel is further configured to fold about a folding axis other than the folding axis.

[0182] Option 19. A foldable display device, comprising:

[0183] A display panel configured to fold about a folding axis, the display panel comprising:

[0184] The first plurality of spacers arranged in the non-folded area; and

[0185] A second plurality of spacers are arranged in the folded area, wherein the first plurality of spacers have a first density less than the second plurality of spacers.

[0186] Option 20. The foldable display device according to Option 19, wherein the second density is at least twice the first density.

[0187] Option 21. The foldable display device according to Option 19, wherein the display panel further includes:

[0188] A plurality of pixels are arranged in a display area, each of the plurality of pixels overlapping with at least one of the first plurality of spacers or the second plurality of spacers.

[0189] Option 22. The foldable display device according to Option 21, wherein the first plurality of spacers and the second plurality of spacers occupy 0.25% to 1.25% of the area of ​​the display area.

[0190] Option 23. The foldable display device according to Option 22, wherein the first plurality of spacers disposed in the non-foldable region occupy 0.45% to 0.5% of the area of ​​the non-foldable region.

[0191] Option 24. The foldable display device according to Option 22, wherein the second plurality of spacers disposed in the folded region occupy 0.45% to 1% of the area of ​​the non-folded region.

[0192] Option 25. A foldable display device, comprising:

[0193] The display panel includes:

[0194] The first plurality of spacers arranged in the non-folded area;

[0195] A second plurality of spacers are arranged in the folded area, the second plurality of spacers having

[0196] The size or density of the first plurality of spacers differs from that of the first plurality of spacers; and

[0197] A plurality of pixels are arranged in a display area, each of the plurality of pixels overlapping with at least one of the first plurality of spacers or the second plurality of spacers.

Claims

1. A foldable display device, comprising: a display area including a folding area configured to be folded about a folding direction and a non-folding area, and the display area including a plurality of pixels located in the folding area and the non-folding area, wherein the plurality of pixels include: a transistor; a planarization layer disposed on the transistor; an anode disposed on the planarization layer; a bank disposed on the anode; an element disposed on the anode and between the banks; and a spacer disposed on the bank, wherein the spacers in the folding area differ from the spacers in the non-folding area in at least one of shape, number, arrangement density, and area size, and wherein a smallest dimension of the spacers in the folding area extends in a direction intersecting the folding direction. 2.The foldable display device of claim 1, wherein the plurality of pixels further including a cathode disposed on the bank and upper and side portions of the spacer. 3.The foldable display device of claim 1, wherein, the bank further including a bank hole exposing the anode, the element including an organic light emitting layer disposed on the anode exposed by the bank hole. 4.The foldable display device of claim 3, wherein the folding direction of the folding area being a direction such that the organic light emitting layers included in each of the plurality of pixels are folded to face each other. 5.The foldable display device of claim 1, wherein the folding direction of the folding area being a direction such that image display units face each other in a case where the foldable display device is folded. 6.The foldable display device of claim 1, wherein, the folding direction of the folding area being a direction in which light is emitted. 7.The foldable display device of claim 1, wherein the bank being formed of an organic material including at least one selected from the group consisting of polyimide, acrylic, and benzocyclobutene-based resin. 8.The foldable display device of claim 2, further comprising: an encapsulation unit on the cathode, wherein the encapsulation unit has a structure in which inorganic layers and organic layers are alternately laminated. 9.The foldable display device of claim 1, wherein the spacer having a tapered shape. 10.The foldable display device of claim 1, wherein the spacers in the non-folding area are a first plurality of spacers; and the spacers in the folding area are a second plurality of spacers, wherein the second plurality of spacers have a size different from the first plurality of spacers, each of the second plurality of spacers has a first dimension and a second dimension greater than the first dimension, and the second dimensions of the second plurality of spacers are all in the folding direction. 11.The foldable display device of claim 10, wherein the first plurality of spacers and the second plurality of spacers are disposed on the same layer. 12.The foldable display device of claim 1, wherein the plurality of pixels further including a cathode disposed on the bank and the spacer. 13.A foldable display device, comprising: A display panel configured to be folded around a folding axis, the display panel comprising: a first plurality of spacers arranged in a non-folding area; and a second plurality of spacers arranged in a folding area, each of the second plurality of spacers does not overlap with a light emitting region of the light emitting element, wherein the first plurality of spacers is different from the second plurality of spacers in at least one of shape, number, arrangement density, and area size, and wherein a smallest dimension of the second plurality of spacers extends in a direction crossing the folding axis.

14. The foldable display device of claim 13, wherein the display panel further comprises at least one transistor arranged in the folding area, each of the at least one transistor is electrically connected to the light emitting element, and wherein the second plurality of spacers is arranged in the folding area and on the at least one transistor.

15. The foldable display device of claim 13, wherein the second plurality of spacers has a size different from the first plurality of spacers, each of the second plurality of spacers has a first dimension and a second dimension larger than the first dimension, the second dimension of the second plurality of spacers all are in a direction of the folding axis.

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