KR20220095171A - Foldable display device - Google Patents

Abstract

The present invention relates to a foldable display device having a dual function spacer in a folding region. The foldable display device of the present invention comprises: a substrate having a folding region and a non-folding region having a folding axis; a bank layer covering a part of the periphery of an electrode electrically connected to a thin film transistor positioned on the substrate; a first spacer located on the bank layer, having a first width and a second width longer than the length of the first width, and positioned in the non-folding region; and a second spacer positioned in the folding region on the bank layer, having a third width having a longer length in the direction in which the second width extends to intersect with the extending direction and a fourth width shorter than the length of the third width, and having suppressed cracks. The present invention can improve foldability of the foldable display device.

Description

Foldable display device {FOLDABLE DISPLAY DEVICE}

The present invention relates to a foldable display having a dual function spacer in a folding area.

The video display device that realizes various information on the screen is a core technology in the information and communication era. Cathode Ray Display Panel, Liquid Crystal Display Panel, Electrophoretic Display Panel, organic and an organic light emitting display panel.

In particular, in order to realize a thinner, lighter, portable and high-performance image display device, an organic light emitting display panel that displays an image by controlling the amount of light emitted by an organic light emitting device is in the spotlight.

The organic light emitting display panel is a self-emission type display panel, and since it is implemented without a separate light source device, it can be manufactured in a light and thin shape. In addition, the organic light emitting display panel is easily implemented as a foldable display device by disposing a thin film transistor and an organic light emitting layer on a foldable substrate.

An organic light emitting display panel implemented as a foldable display device may be vulnerable to external impact. In particular, when the foldable display device is folded, the organic light emitting layer may be damaged due to peeling of the organic light emitting layer in the vicinity of the folding area due to weak adhesiveness.

Accordingly, in the organic light emitting display panel, the organic light emitting layer may be protected by locating the spacer in the non-emissive area to prevent the organic light emitting layer from being peeled from an external impact caused by the folding of the foldable display.

In this case, when the foldable display device is folded, folding stress (or stress) may be applied to the organic light emitting display panel by folding. If stress is continuously applied due to repeated folding, the spacer included in the organic light emitting display panel may be damaged. Accordingly, the damaged spacer becomes a foreign material, which may cause dark spots in the organic light emitting layer. Dark spots in the organic emission layer may decrease luminance of the foldable display.

Accordingly, the inventors of the present invention recognized the need to minimize the folding stress applied to the spacer in order to implement a foldable display device. Accordingly, the inventors of the present invention have devised a new structure in which the organic light emitting diode display panel of the foldable display includes the spacer while suppressing the breakage of the spacer.

The problems of the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

A foldable display device according to an embodiment of the present invention includes a substrate having a folding area having a folding axis and a non-folding area, a bank layer covering an outer part of an electrode electrically connected to a thin film transistor positioned on the substrate, and a bank It is positioned on the layer and has a second width that is longer than the first width and the length of the first width, is positioned in the folding region on the first spacer and the bank layer positioned in the non-folding region, wherein the second width is and a crack-suppressed second spacer having a third width longer than the third width and a fourth width shorter than the third width to intersect the extending direction.

The second spacers are arranged in a stretch-minimizing arrangement so that the substrate is folded with respect to the folding axis.

The stretch-minimizing arrangement structure is such that the fourth width of the second spacer is perpendicular to the folding axis so that elongation of the second spacer is minimized in the longitudinal direction of the fourth width.

The elongation-minimizing arrangement structure is such that the third width is parallel to the folding axis so that elongation of the second spacer is minimized in the longitudinal direction of the third width.

The length of the third width of the second spacer is the same as the length of the second width, and the length of the fourth width of the second spacer is the same as the length of the first width.

The length of the third width of the second spacer is longer than the length of the first width and shorter than the length of the second width, the length of the fourth width of the second spacer is longer than the length of the first width, and the length of the third width shorter than the length of

A display device according to another embodiment of the present invention includes a substrate including a folding region and a non-folding region, a thin film transistor positioned on the substrate, a first insulating layer covering the thin film transistor and having a contact hole, and a first insulating layer An electrode positioned on the layer and electrically connected to the thin film transistor through a contact hole, a second insulating layer positioned on the first insulating layer and covering a portion of the electrode and the contact hole. The organic light emitting layer positioned on the electrode and the second insulating layer in the folding region include a double-function spacer that improves folding easiness and suppresses reduction in luminance.

The dual function of the dual function spacer is implemented by having a structure in which folding stress is minimized so that damage of the dual function spacer is suppressed.

The structure in which the folding stress is minimized is configured such that the length of a specific width of the dual function spacer is shorter than the length of the remaining widths in the same direction as the direction in which the substrate is stretched.

The dual function spacer is configured to have the longest length of another width perpendicular to a specific width.

The dual function spacer has the same shape as the spacer disposed in the non-folding area.

The dual function spacer has a trapezoidal shape when the foldable display device is viewed from one side.

The size of the largest base angle of the dual function spacer is larger than the size of the largest base angle of the spacer disposed in the non-folding area.

The dual function spacer has a structure in which internal reflection of the panel is minimized, thereby improving the efficiency of suppressing luminance decrease.

The structure in which the internal reflection of the panel is minimized is a structure in which a portion of the dual function spacer is positioned on the contact hole to overlap and shield.

According to the present invention, when the foldable display device is folded, damage can be suppressed by including the dual function spacer in the folding area to minimize the folding stress.

According to the present invention, foldability of the foldable display device can be improved by providing the double function spacer in the folding area.

According to the present invention, a decrease in luminance of the foldable display device due to foreign matter may be suppressed by providing the double-function spacer in the folding area.

Effects according to the embodiments of the present invention are not limited by the contents exemplified above, and more various effects are included in the present specification.

1 is a plan view of a foldable display device according to an exemplary embodiment.
FIG. 2A is a cross-sectional view taken along line IIa-IIa' of FIG. 1 .
FIG. 2B is a cross-sectional view taken along IIb-IIb' of FIG. 1 .
3 is a plan view illustrating an arrangement of spacers of a foldable display device according to an exemplary embodiment.
4 is a plan view illustrating an arrangement of spacers of a foldable display device according to another exemplary embodiment of the present invention.
5 is a plan view illustrating the arrangement of spacers of a foldable display according to another exemplary embodiment of the present invention.

Advantages and features of the present specification, and a method for achieving them, will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention belongs It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims.

The shapes, sizes, proportions, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of the present specification are exemplary, and thus the present specification is not limited to the illustrated matters. Like reference numerals refer to like elements throughout. In addition, in describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. When 'including', 'having', 'consisting', etc. mentioned in this specification are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, cases including the plural are included unless otherwise explicitly stated. In interpreting the components, it is construed as including an error range even if there is no separate explicit description.

In the case of a description of the positional relationship, for example, when the positional relationship of two parts is described as 'on', 'on', 'on', 'beside', etc., 'right' Alternatively, one or more other parts may be positioned between two parts unless 'directly' is used. Reference to a device or layer “on” another device or layer includes any intervening layer or other device directly on or in the middle of the other device or layer. When it is described that a component is “connected”, “coupled” or “connected” to another component, the component may be directly connected or connected to the other component, but other components may be interposed between each component. It should be understood that each component may be “interposed” or “connected”, “coupled” or “connected” through another component.

Although first, second, etc. are used to describe various elements, these elements are not limited by these terms. These terms are only used to distinguish one component from another. Accordingly, the first component mentioned below may be the second component within the spirit of the present invention.

Like reference numerals refer to like elements throughout.

The size and thickness of each component shown in the drawings are illustrated for convenience of description, and the present invention is not necessarily limited to the size and thickness of the illustrated component.

Each feature of the various embodiments of the present invention can be partially or wholly combined or combined with each other, technically various interlocking and driving are possible, and each of the embodiments may be independently implemented with respect to each other or implemented together in a related relationship. may be

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 is a plan view of a foldable display device according to an exemplary embodiment. In FIG. 1 , only the organic light emitting display panel 110 is illustrated among various components of the foldable display 100 for convenience of explanation.

The organic light emitting display panel 110 is a panel on which an image is realized, and an organic light emitting device for realizing an image and a circuit, wiring, and components for driving the organic light emitting device may be disposed.

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.

The display area AA is an area for displaying an image, in which a plurality of pixels made of organic light emitting devices are arranged. An organic light emitting device for displaying an image and a circuit unit for driving the organic light emitting device may be disposed in the display area AA. In the present invention, for convenience of description, it is assumed that the foldable display 100 including the organic light emitting display panel 110 including the organic light emitting element is used, but the present invention is not limited thereto.

The circuit unit may include various thin film transistors, capacitors, and wires for driving the organic light emitting diode. For example, the circuit unit may 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 is not limited thereto.

The non-display area NA is an area in which an image is not displayed, and is an area in which circuits, wirings, and components for driving the organic light emitting device of the display area AA are disposed. Various ICs and driving circuits such as a gate driver IC and a data driver IC may be disposed in the non-display area NA. For example, various ICs and driving circuits are mounted on the non-display area NA of the organic light emitting display panel 110 as a gate in panel (GIP), or include a tape carrier package (TCP) or a chip on film (COF). In this way, it may be connected to the organic light emitting display panel 110 .

Meanwhile, the organic light emitting display panel 110 may be defined as a display area AA and a non-display area NA, but may also be defined as a folding area FA and a non-folding area FA.

The folding area (or folding area) FA is an area in which the organic light emitting display panel 110 is folded when the foldable display 100 is folded, and includes a portion of the display area AA and a non-display area. (NA) may be included. The present invention is described by exemplifying that the folding area FA includes a portion of the display area AA and a portion of the non-display area NA, but is not limited thereto, and only a portion outside of the display area AA is not included. There may be a display area NA. Accordingly, the folding area FA may include only a part of the display area AA.

The folding area FA may be folded according to a specific radius of curvature based on a folding axis (or a folding axis). Specifically, the folding axis may be the X axis. When the folding area FA is folded based on the folding axis, the folding area FA may form a part of a circle or an ellipse. In this case, the radius of curvature of the folding area FA means a radius of a circle or an ellipse corresponding to a part of a circle or an ellipse formed by the folding area FA. In the present invention, it is described as an example that a folding axis in the X-axis direction is positioned in the folding area FA, and the non-folding area NFA extends from the folding area FA in the Y-axis direction and is perpendicular to the folding axis. This is not limited thereto.

The non-folding area (or non-folding area) NFA is an area in which the organic light emitting diode display panel 110 is not folded when the foldable display 100 is folded. That is, the non-folding area NFA is an area in which the organic light emitting display panel 110 maintains a planar state when the foldable display 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.

The non-folding area NFA may be an extended area located on both sides of the folding area FA. That is, the non-folding area NFA may be an area extending in the Y-axis direction with respect to the folding axis. In this case, the folding area FA may be defined between the non-folding areas NFA. Accordingly, when the organic light emitting display panel 110 is folded based on the folding axis, the non-folding areas NFA may face each other.

Hereinafter, for a more detailed description of the foldable display device 100 , it will be described with reference to FIGS. 2A to 2B together.

FIG. 2A is a cross-sectional view taken along line IIa-IIa' of FIG. 1 . FIG. 2B is a cross-sectional view taken along IIb-IIb' of FIG. 1 . 2A is a cross-sectional view of the foldable display in the Y-axis direction, and FIG. 2B is a cross-sectional view of the foldable display in the X-axis direction.

In the foldable display 100 according to an embodiment of the present invention shown in FIGS. 2A and 2B , the light emitted from the organic light emitting diode 130 of the organic light emitting display panel 110 passes through a cathode. It is a top-emission type foldable display device 100 that is emitted to an upper portion of the light emitting display panel 110 . However, the present invention is not limited to the top emission type foldable display device 100, and may be applied to the bottom-emission type and dual side-emission foldable display devices. .

The substrate 101 supports various components of the foldable display 100 . Since the substrate 101 may be made of a plastic material having flexibility, it is a foldable and flexible substrate 101 . In this case, when the substrate 101 is folded based on the folding axis, the foldable display 100 may be folded. For example, when the substrate 101 is made of polyimide (PI), the manufacturing process proceeds in a situation where a support substrate made of glass is disposed under the substrate 101, and after the manufacturing process is completed, the support substrate is released ( can be released). Also, after the supporting substrate is released, a back plate for supporting the substrate 101 may be disposed under the substrate 101 . The substrate 101 that can be applied to the foldable display 100 may be made of not only a plastic material but also other materials having flexibility as long as the foldable display 100 is not damaged even when the foldable display 100 is repeatedly folded. can

The thin film transistor 120 is disposed on the substrate 101 . The thin film transistor 120 includes an active layer 121 made of polysilicon, a gate electrode 124 , a source electrode 122 , and a drain electrode 123 . The thin film transistor 120 is a thin film transistor 120 having a top gate structure in which a gate electrode 124 is disposed on the active layer 121 . 2A and 2B show only the driving thin film transistor among various thin film transistors that may be included in the foldable display device 100 for convenience of explanation. can be included in In addition, although the thin film transistor 120 has been described as having a coplanar structure in this specification, the thin film transistor 120 may be implemented in other structures such as a staggered structure. In addition, although the thin film transistor 120 is disposed on the substrate 101 in FIG. 2 , the present invention is not limited thereto, and based on the type and material of the substrate 101 , the structure and type of the thin film transistor 120 , etc. A multi-buffer layer may be disposed between the substrate 101 and the thin film transistor 120 .

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 may be defined by ion doping (impurity doping).

The active layer 121 of the thin film transistor 120 may be made of polysilicon. Accordingly, polysilicon is formed by depositing an amorphous silicon (a-Si) material on the substrate 101 and performing a dehydrogenation process, a crystallization process, an activation process, and a hydrogenation process, and patterning the polysilicon to form an active layer (121) may be formed. When the active layer 121 is made of polysilicon, the thin film transistor 120 may be an LTPS thin film transistor 120 using low temperature poly-silicon (LTPS). Since the polysilicon material has high mobility, when the active layer 121 is made of polysilicon, energy consumption is low and reliability is excellent.

Also, the active layer 121 of the thin film transistor 120 may be made of an oxide semiconductor material. The active layer 121 of the thin film transistor 120 may be made of a metal oxide, for example, may be made of a metal oxide such as IGZO, but is not limited thereto. Since the oxide semiconductor material has a larger bandgap compared to the silicon material, electrons cannot cross the bandgap in the off state, and thus the off-current is low.

A gate insulating layer 102 is disposed on the active layer 121 . The gate insulating layer 102 may be formed of a single layer of inorganic silicon nitride (SiNx) or silicon oxide (SiOx) or a multilayer of silicon nitride (SiNx) or silicon oxide (SiOx). The gate insulating layer 102 has a contact hole through which the source electrode 122 and the drain electrode 123 respectively contact the source region and the drain region of the active layer 121 , respectively. In FIG. 2 , the gate insulating layer 102 is illustrated as being planarized for convenience of explanation, but the gate insulating layer 102 may be formed along the shapes of the components disposed thereunder.

A gate electrode 124 is disposed on the gate insulating layer 102 . A metal layer such as molybdenum (Mo) is formed on the gate insulating layer 102 and the metal layer is patterned to form a gate electrode 124 . The gate electrode 124 is disposed on the gate insulating layer 102 to overlap the channel region of the active layer 121 .

An interlayer insulating layer 103 is disposed on the gate electrode 124 . The interlayer insulating layer 103 may be formed of a single layer of inorganic silicon nitride (SiNx) or silicon oxide (SiOx) or a multilayer of silicon nitride (SiNx) or silicon oxide (SiOx). In the interlayer insulating layer 103 , the source electrode 122 and the drain electrode 123 each have a contact hole for contacting the source region and the drain region of the active layer 121 , respectively. In FIGS. 2A and 2B , the interlayer insulating layer 103 is illustrated as being planarized for convenience of explanation, but the interlayer insulating layer 103 may be formed along the shapes of the components disposed thereunder.

A source 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, for example, may have a three-layer structure of titanium (Ti)/aluminum (Al)/titanium (Ti). Each of the source electrode 122 and the drain electrode 123 may be connected to a source region and a drain region of the active layer 121 through a contact hole provided in the gate insulating layer 102 and the interlayer insulating layer 103 , respectively.

A planarization layer (or a first insulating layer) 105 is disposed on the thin film transistor 120 . In this case, the planarization layer 105 may cover and protect the thin film transistor 120 . In addition, the planarization layer 105 planarizes the upper portion of the thin film transistor 120 , so that the organic light emitting diode 130 can be formed more reliably. In this case, the planarization layer 105 may include a contact hole through which the anode 131 of the organic light emitting diode 130 is connected to the thin film transistor 120 .

The organic light emitting diode 130 is disposed on the planarization layer 105 . The organic light emitting diode 130 is formed on the planarization layer 105 and is electrically connected to the source electrode 122 of the thin film transistor 120 by an anode electrode 131 , and an organic light emitting layer 122 disposed on the anode electrode 131 . ) and a cathode electrode 133 formed on the organic emission layer 132 . In this case, the anode electrode 131 may be positioned on the planarization layer 105 and may be electrically connected to the thin film transistor 120 through a contact hole provided in the planarization layer 105 . Since the foldable display 100 is implemented in a top emission method, the anode electrode 131 provides a reflective layer for reflecting the light emitted from the organic emission layer 132 toward the cathode 133 and holes in the organic emission layer 132 . It may include a transparent conductive layer for supply. However, it may be defined that the anode electrode 131 includes only a transparent conductive layer and the reflective layer is a separate component from the anode electrode 131 .

The organic emission layer 132 is an organic layer for emitting light of a specific color, and may include one of a red organic emission layer, a green organic emission layer, a blue organic emission layer, and a white organic emission layer. If the organic light emitting layer 132 includes a white organic light emitting layer, a color filter for converting white light from the white organic light emitting layer into light of a different color may be disposed on the organic light emitting device 130 . In addition, the organic emission layer 132 may further include various organic and/or inorganic layers such as a hole transport layer, a hole injection layer, an electron injection layer, an electron transport layer, and the like.

The cathode 133 may be made of a transparent conductive material, and may include, for example, a transparent conductive oxide such as IZO or ytterbium (Yb).

An encapsulation unit 140 may be stacked on the cathode 133 . In this case, the encapsulation unit 140 may have a structure in which inorganic layers and organic layers are alternately stacked. Accordingly, the encapsulation unit 140 prevents the organic light emitting device 130 vulnerable to moisture and/or oxygen from being exposed to moisture and/or oxygen, so that the organic light emitting device 130 may be protected.

A bank (or a second insulating layer) 107 is disposed on the anode electrode 131 and the planarization layer 105 . In this case, the bank 107 is positioned on the planarization layer 105 , and may cover an outer portion of the anode electrode 131 and a contact hole provided in the planarization layer 105 . Since the bank 107 is positioned adjacent to each pixel disposed in the display area AA to distinguish each pixel, it can be said that the bank 107 defines each pixel area. The bank 107 may be made of an organic material. For example, the bank 107 may be made of polyimide, acryl, or benzocyclobutene (BCB)-based resin, but is not limited thereto.

A plurality of spacers 150 and 160 are disposed on the bank 107 . An array of spacers 150 and 160 may be positioned between pixels formed of the organic light emitting diode 130 . In this case, the spacers 150 and 160 may be positioned adjacent to the organic emission layer 132 . The spacers 150 and 160 may protect the organic light emitting layer 132 from external impact when the foldable display 100 is folded. Accordingly, the spacers 150 and 160 may prevent lifting due to the weak adhesive force of the organic light emitting layer 132 . Accordingly, the spacers 150 and 160 may prevent the organic emission layer 132 from being peeled off.

Among the spacers 150 and 160 , at least some of the spacers 160 in the folding area FA may have a different structure from at least some of the spacers 150 in the non-folding area NFA. In this case, the dual function spacer 160 may be disposed in the folding area FA. The double-function spacer 160 may improve folding easiness of the foldable display 100 and suppress a decrease in luminance.

As shown in FIG. 2A , when the foldable display 100 is folded, the substrate 101 may be folded with a specific radius of curvature. At this time, at least one characteristic among the shape, number, location, density, and area occupied by the double-function spacer 160 disposed in the folding area FA is the specific characteristic of the flexible substrate 101 in the folding area FA. It may be determined according to a folding radius of curvature.

In detail, the structure and arrangement of the spacer 150 disposed in the non-folding area NFA and the dual function spacer 160 disposed in the folding area FA may be different.

At least some of the spacers 150 disposed in the non-folding area NFA may be configured such that a length of a specific width of the spacer 150 extending in a direction perpendicular to the folding axis is longest than the length of the remaining widths. That is, at least some of the spacers 150 disposed in the non-folding area NFA may extend in the Y-axis direction, and a length of a width in the Y-axis direction may be longer than a length of the remaining widths.

At least some of the dual function spacers 160 disposed in the folding area FA may be configured such that the length of a specific width of the dual function spacer 160 extending in a direction perpendicular to the folding axis is shorter than the length of the remaining widths. can

In addition, as shown in FIG. 2B , at least some of the dual function spacers 160 disposed in the folding area FA are the same as the direction in which the folding axis extends. The lengths of different widths may be configured to be longest. That is, at least some of the dual function spacers 160 disposed in the folding area FA may extend or be arranged along the folding axis direction (X-axis direction).

Accordingly, the dual function spacer 160 may be configured to have the longest length of another width that intersects the shortest configured specific width. In this case, the shortest specific width of the dual function spacer 160 may be referred to as a short axis, and the longest specific width of the dual function spacer 160 may be referred to as a long axis. Accordingly, the intersecting long axis and the short axis of the dual function spacer 160 may be perpendicular to each other. That is, at least some of the dual function spacers 160 disposed in the folding area FA extend in the X-axis direction, have the longest width in the X-axis direction, and have the shortest width in the Y-axis direction. have. In this case, the dual function spacer 160 disposed in the folding area FA should protect the organic light emitting layer 132 without collapsing due to an external impact. Therefore, the length of the width in the Y-axis direction of the dual function spacer 160 should be, for example, at least 2 μm. Also, the height of the dual function spacer 160 should not be greater than the height of the encapsulation unit 140 . For example, when the height of the encapsulation unit 140 is 3.5 μm, the height of the dual function spacer 160 may be 3 μm or less.

The flexible substrate 101 may be folded (or folded) with a specific radius of curvature based on the folding axis of the folding area FA. In this case, the flexible substrate 101 may be stretched in the Y-axis direction. In this case, at least some of the dual function spacers 160 disposed in the folding area FA may have the shortest specific width. The specific width of the dual function spacer 160 is the same width as the direction in which the flexible substrate 101 is folded and stretched. That is, the short axis of the dual function spacer 160 may extend in the same direction as the direction in which the flexible substrate 101 is stretched when the substrate 101 is folded with a specific radius of curvature. Accordingly, the elongation of the dual function spacer 160 in the Y-axis direction may be minimized. That is, when the flexible substrate 101 is folded based on the folding axis in the folding area FA, the elongation of the dual function spacer may be minimized. Accordingly, when the foldable display 100 is folded, the folding stress applied to the dual function spacer 160 may be minimized.

The double-function spacer 160 disposed in the folding area FA and the spacer 150 disposed in the non-folding area NFA may be positively tapered spacers. The forward taper spacer refers to a spacer having a trapezoidal shape when viewed from one side, and the reverse taper spacer refers to a spacer having a reverse trapezoidal shape when viewed from one side. In the forward tapered spacer, particles generated during the spacer deposition process may be minimized compared to the reverse tapered spacer. Accordingly, the double-function spacer 160 disposed in the folding area FA and the spacer 150 disposed in the non-folding area NFA may be formed as a positively tapered spacer in the same process. That is, the dual function spacer 160 disposed in the folding area FA and the spacer 150 disposed in the non-folding area NFA may have the same shape.

In addition, the inverted trapezoidal inverted taper spacer has an area that increases toward the top of the trapezoidal inverted taper spacer, but the thickness of the spacer may be reduced. When the foldable display device 100 is folded, an end of the reverse tapered spacer may be damaged by folding stress applied to the spacer. Accordingly, the reverse tapered spacer may generate foreign substances due to breakage of the spacer due to folding stress. Since the thickness of the tip of the normal tapered spacer increases toward the top, damage to the spacer due to folding stress can be minimized. Therefore, the normal taper spacer can minimize foreign matter. The dual function spacer 160 disposed in the folding area FA may be a spacer having a trapezoidal shape when the foldable display 100 is viewed from one side. Accordingly, the dual function spacer 160 disposed in the folding area FA is a positively tapered spacer, and folding stress may be minimized.

The size of the largest base angle '' of the dual function spacer 160 may be larger than the size of the largest base angle ' of the spacer 150 disposed in the non-folding area NFA. In this case, the area of the upper surface of the dual function spacer 160 disposed in the folding area FA may be larger than the area of the upper surface of the spacer 150 disposed in the non-folding area NFA. When the foldable display 100 is folded, folding stress is transferred to the upper surface of the dual function spacer 160 . In this case, the folding stress that the dual function spacer 160 receives per unit area is inversely proportional to the area of the upper surface of the dual function spacer 160 . Accordingly, as the area of the upper surface of the dual function spacer 160 increases, the folding stress may be dispersed. That is, the area of the upper surface of the dual function spacer 160 disposed in the folding area FA is made wider than the area of the upper surface of the spacer 150 disposed in the non-folding area NFA, so that the folding stress is not distributed. can In this case, if the dual function spacer 160 has a structure capable of distributing folding stress, the shape of the upper surface may be not only a rectangle, but also a rhombus shape and a polygonal shape.

Accordingly, the dual function spacer 160 disposed in the folding area FA may have a structure that distributes folding stress or minimizes folding stress, so that when the foldable display 100 is folded, damage may be suppressed. have. Accordingly, foldability of the foldable display 100 may be improved.

In addition, since damage to the double-function spacer 160 disposed in the folding area FA is suppressed, it is possible to minimize particles generated due to breakage of the spacer. Foreign substances generated due to the breakage of the spacer may penetrate into the organic emission layer 132 and change the height of the organic emission layer 132 . In addition, a foreign material generated due to the breakage of the spacer may apply a stimulus to the organic light emitting layer 132 and damage the organic light emitting layer 132 . When the height of the organic emission layer 132 is changed or the organic emission layer 132 is damaged, dark spots may be generated in the foldable display 100 . The dark spot may be a defect of the foldable display 100 . Accordingly, the double-function spacer 160 in which damage due to reduction in folding stress is suppressed can minimize foreign substances. Accordingly, a change in the height of the organic light emitting layer 132 or damage to the organic light emitting layer 132 due to a foreign material can be minimized, and thus a decrease in luminance of the foldable display 100 can be suppressed by suppressing the occurrence of dark spots.

In this case, the area occupied by the spacers 150 and 160 in the display area AA of the foldable display 100 may be, for example, 0.25% to 1.25% of the total area of the display area AA. The area occupied by the spacers 150 and 160 may be determined in consideration of various factors such as the size of a pixel, arrangement of TFTs, arrangement and process of spacers, and the like.

Specifically, an area occupied by the spacer 150 disposed in the non-folding area NFA may be, for example, 0.45% to 0.5% of the total area of the display area AA. An area occupied by the dual function spacer 160 disposed in the folding area FA may be, for example, 0.45 to 1% or less of the total area of the display area AA. That is, the total area occupied by the dual function spacer 160 disposed in the folding area FA does not exceed twice the total area occupied by the spacer 150 disposed in the non-folding area NFA. In this case, the area occupied by the dual function spacer 160 disposed in the folding area FA from the total area of the display area AA is the folding stress that the dual function spacer 160 receives when the foldable display device 100 is folded. Considering this, the spacer 150 disposed in the non-folding area NFA may occupy a larger area than the area occupied by the spacer 150 .

In this case, the size of each pixel of the foldable display 100 may be different. Accordingly, the dual function spacer 160 disposed adjacent to the pixel may be formed in consideration of the size of the pixel. A pixel may be composed of a plurality of sub-pixels, and at least one dual function spacer 160 may correspond to each sub-pixel. In this case, as the size of the double-function spacer 160 is smaller, the adjacent sub-pixels may be formed to be relatively larger, so that the luminance of the foldable display 100 may be improved. Accordingly, the dual function spacer 160 may be disposed by increasing the density (or the number) of the dual function spacer 160 having a small size in the area where the dual function spacer 160 is disposed in the folding area FA. That is, rather than forming one dual-function spacer 160 in the same area, a plurality of relatively small dual-function spacers 160 may be formed to increase the density of the dual-function spacer 160 . Accordingly, the folding stress applied to the dual function spacer 160 may be minimized, and the size of a sub-pixel adjacent to the dual function spacer 160 may be formed to be relatively larger. Accordingly, the luminance of the foldable display 100 may be improved.

In this case, the dual function spacer 160 may be formed of, for example, an acryl-based material, a polyimide, a polyamide, a carbon compound, or a silicon-based material, but is limited thereto. not.

In addition, the dual function spacer 160 positioned on the bank 107 may be positioned on the contact hole provided in the planarization layer 105 . A portion of the anode electrode 131 may be positioned in the contact hole provided with the planarization layer 105 to be electrically connected to the thin film transistor 120 . When the foldable display 100 is folded, light emitted from the organic emission layer 132 may be diffused by a portion of the anode electrode 131 positioned inside the contact hole. Accordingly, the contact hole ( 100 ) of the foldable display may be visually recognized, or a dark spot may be generated in the pixel due to light interference. In this case, a portion of the dual function spacer 160 may overlap the contact hole provided in the planarization layer 105 . Also, a portion of the dual function spacer 160 may overlap a portion of the anode electrode 131 positioned in the contact hole. Accordingly, the dual function spacer 160 may shield the contact hole to minimize internal reflection of the panel. In this case, one dual function spacer 160 may shield not only one contact hole but also a contact hole in a neighboring pixel. That is, one dual function spacer 160 may shield a plurality of contact holes.

Accordingly, the contact hole of the foldable display 100 can be visually recognized or the occurrence of dark spots due to light interference can be minimized, thereby improving the efficiency of suppressing a decrease in luminance of the foldable display 100 .

3 to 5 are plan views illustrating the arrangement of spacers of a foldable display device according to an exemplary embodiment of the present invention. 3 to 5 are plan views schematically illustrating only the structure and arrangement of spacers included in the foldable display device. Accordingly, since the configuration, positions, materials, etc. of other components are the same as those of the foldable display according to the present invention, a redundant description thereof will be omitted.

In addition, hereinafter, for convenience of description, the spacers positioned in the non-folding area NFA are referred to as first spacers 150 and 350 , and the double-function spacers 160 and 260 positioned in the folding area FA are referred to as second spacers. It will be referred to as spacers 160 and 260 .

As shown in FIG. 3 , spacers 150 and 160 may be positioned on the bank layer 107 .

The first spacer 150 positioned in the non-folding area NFA may have a first width 151 and a second width 153 that is longer than a length of the first width.

The second spacer 160 positioned in the folding area FA may have a third width 161 and a fourth width 163 shorter than a length of the third width 161 . In this case, the direction in which the third width 161 of the second spacer 160 extends may intersect the direction in which the second width 153 of the first spacer 150 extends. That is, the second spacer 160 may have a longer third width 161 , which is a width that intersects the extending direction of the second width 153 of the first spacer 150 . In this case, the extending direction of the second width 153 and the extending direction of the third width 161 may be orthogonal to each other.

Since the substrate 101 is folded based on the folding axis in the folding area FA, it may be stretched in the Y-axis direction. In this case, since the fourth width 163 of the second spacer 160 is arranged in the Y-axis direction, the second spacer 160 may extend in the fourth width 163 direction. At this time, the second spacer 160 has a third width so that elongation in the direction of the fourth width 163 is minimized, the fourth width 163 is orthogonal to the folding axis, and elongation is minimized in the direction of the third width 161 . (161) is a structure parallel to the folding axis. In this case, the length of the fourth width 163 constituting the second spacer 160 is shorter than the length of the third width 161 . Accordingly, elongation of the second spacer 160 in the direction of the fourth width 163 when the substrate 101 is folded may be minimized. That is, the second spacers 160 are arranged in an elongation-minimized arrangement structure in which elongation is minimized when the substrate 101 is folded with respect to the folding axis, so that the folding stress applied to the second spacers 160 can be minimized. Accordingly, breakage of the second spacer 160 disposed in the folding area FA may be suppressed, so that the foldable display 100 may be easily folded.

In addition, since damage to the second spacer 160 disposed in the folding area FA is suppressed, foreign matter generated due to the breakage of the second spacer 160 may be minimized. Accordingly, a change in the height of the organic light emitting layer 132 or damage of the organic light emitting layer 132 due to foreign substances can be minimized, thereby suppressing the occurrence of dark spots, thereby suppressing a decrease in luminance of the foldable display 100 .

In this case, the first spacer 150 disposed in the non-folding area NFA and the second spacer 160 disposed in the folding area FA may have the same shape. Specifically, the length of the third width 161 of the second spacer 160 may be the same as the length of the second width 153 of the first spacer 150 . The length of the fourth width 163 of the second spacer 160 may be the same as the length of the first width 151 of the first spacer 150 . Accordingly, the first spacer 150 and the second spacer 160 may be formed in the same process. Accordingly, since the process of forming the first spacer 150 and the second spacer 160 can be simplified, it is possible to minimize the foreign matter generated by the breakage of the spacer due to the repetition of the process.

In FIG. 4 , only the structure of the second spacer is different from that of FIG. 3 , and since the remaining structures are the same, a redundant description will be omitted.

4 , the second spacer 260 positioned in the folding area FA may have a third width 261 and a fourth width 263 shorter than the third width. . In this case, the length of the third width 261 of the second spacer 260 may be longer than the length of the first width 151 of the first spacer, and may be shorter than the length of the second width 153 . In addition, the length of the fourth width 263 of the second spacer 260 is longer than the length of the first width 151 of the first spacer 150 , and the length of the third width 261 of the second spacer 160 . could be shorter. That is, the third width 261 and the fourth width 263 of the second spacer 260 may be longer than the first width 151 of the first spacer 150 . Accordingly, the area of the upper surface of the second spacer 260 may be larger than the area of the upper surface of the first spacer 150 . When the foldable display 100 is folded, folding stress is transferred to the upper surface of the second spacer 260 . In this case, as the area of the upper surface of the second spacer 260 increases, the folding stress may be dispersed. Accordingly, since damage to the second spacer 260 disposed in the folding area FA may be suppressed, the foldable display device 100 may be easily folded.

FIG. 5 is different from FIG. 4 only in the structure of the first spacer, and since the remaining structures are the same, a redundant description thereof will be omitted.

5 , the first spacer 350 disposed in the non-folding area NFA may have the same shape as the second spacer 260 disposed in the folding area FA in FIG. 4 . Specifically, the length of the second width 353 of the first spacer 350 may be the same as the length of the third width 261 of the second spacer 260 . The length of the first width 351 of the first spacer 350 may be the same as the length of the fourth width 263 of the second spacer 260 . Accordingly, the first spacer 350 and the second spacer 260 may be formed in the same process. Accordingly, since the process of forming the first spacer 350 and the second spacer 260 can be simplified, it is possible to minimize foreign matter generated due to spacer breakage due to the repetition of the process.

In addition, by configuring the area of the upper surface of the second spacer 260 to be wide, folding stress may be dispersed. Accordingly, since damage to the second spacer 260 disposed in the folding area FA may be suppressed, the foldable display 100 may be easily folded.

The features of the embodiments described above may be described as follows.

The present invention relates to a foldable flexible substrate; an array of pixels comprising light emitting devices on the flexible substrate; and an array of spacers positioned between the pixels, wherein first spacers in a folding area among the spacers are second spacers in a non-folding area. Provided is a display device in which at least one characteristic among 2 spacers and their shape, number, position, density, and area occupied is different.

Among the first spacers, at least one of shape, number, location, density, and area occupied by the first spacers may be different as they get closer to the folding axis of the folding region.

Each of the pixels may include a plurality of sub-pixels, and one first spacer may correspond to each sub-pixel, and the size of the corresponding first spacer may be different according to the size of each sub-pixel.

When the folding region is inward folding, sizes of first spacers adjacent to the folding axis may be smaller than sizes of first spacers farther from the folding axis.

In the case of outward folding of the fold region, sizes of first spacers adjacent to the fold axis may be larger than sizes of first spacers far from the fold axis.

In addition, the features of the embodiments described above may be described as follows.

The present invention relates to a foldable flexible substrate; an array of pixels comprising light emitting devices on the flexible substrate; and an array of spacers positioned between the pixels, wherein at least some of the first spacers in a folding area among the spacers are non-folding areas ) and a display device having a structure different from that of at least some of the second spacers.

At least one characteristic among the shape, number, position, density, and area occupied by the first spacers may be determined according to a specific folding radius of curvature of the flexible substrate in the folding area.

At least some of the first spacers may extend or be arranged along a folding axis direction.

The total area and density occupied by the first spacers do not exceed twice the total area and density occupied by the second spacers.

Each of the pixels is composed of a plurality of sub-pixels, and one first spacer corresponds to each sub-pixel, and each of the first spacers has a size of 2 μm or more and a height of 3 μm or less.

Although the embodiments of the present invention have been described in more detail with reference to the accompanying drawings, the present invention is not necessarily limited to these embodiments, and various modifications may be made within the scope without departing from the spirit of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The protection scope of the present invention should be construed by the claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

100: foldable display device
110: organic light emitting display panel
120: thin film transistor
130: organic light emitting device
140: encapsulation unit
150, 350: spacer (or first spacer)
160, 260: dual function spacer (or second spacer)

Claims (10)

a substrate including a display area in which a plurality of pixels are arranged to display an image;
a plurality of thin film transistors disposed in each of the plurality of pixels on the substrate;
a planarization layer disposed on the plurality of thin film transistors;
a plurality of organic light emitting devices disposed on the planarization layer and including an anode connected to the thin film transistor through a contact hole formed in the planarization layer, an organic light emitting layer disposed on the anode, and a cathode formed on the organic light emitting layer;
a bank located on the planarization layer and covering a portion of an outer portion of the anode and the contact hole formed in the planarization layer; and
and a spacer disposed between the plurality of pixels on the bank. According to claim 1,
The substrate is
a non-display area disposed outside the display area;
folding area, which is the area with the folding axis; and
It further includes a non-folding area located on both sides of the folding area and extending from the folding area,
The non-folding area includes a first non-folding area in which a part of the display area and a part of the non-display area are disposed, and a second non-folding area in which another part of the display area and another part of the non-display area are disposed. which is a foldable display device. 3. The method of claim 2,
an area of a portion of the display area disposed in the first non-folding area is the same as an area of a portion of the display area disposed in the second non-folding area;
and an area of a portion of the non-display area disposed in the first non-folding area and an area of a portion of the non-display area disposed in the second non-folding area are different from each other. 3. The method of claim 2,
Further comprising an encapsulant disposed on the cathode,
When the foldable display device is folded, the encapsulation unit disposed in the first non-folding area and the encapsulation unit disposed in the second non-folding area are disposed to face each other. According to claim 1,
and the cathode is disposed to cover side surfaces and top surfaces of the bank and side surfaces and top surfaces of the spacers. According to claim 1,
The bank includes a hole exposing the anode,
and the organic light emitting layer is disposed in the hole. According to claim 1,
and a width of the spacer disposed on the bank is smaller than a width of the bank. 3. The method of claim 2,
The spacer is
a first spacer positioned on the bank and having a first width and a second width that is longer than a length of the first width, the first spacer positioned in the non-folding area; and
a breakage ( crack) comprising a suppressed second spacer,
The second spacers are arranged in an elongation-minimizing arrangement so that the substrate is folded with respect to the folding axis;
The stretch-minimizing arrangement includes a structure in which the fourth width of the second spacer is orthogonal to the folding axis so that elongation of the second spacer is minimized in a longitudinal direction of the fourth width. 3. The method of claim 2,
It is located on the bank in the folding area, further comprising a double-function spacer that enables the improvement of folding ease and suppression of reduction in luminance,
The double-function spacer has a trapezoidal shape when viewed from one side of the foldable display. According to claim 1,
and a capacitor disposed to drive the organic light emitting diode in the display area.

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