KR102392468B1 - Foldable display device - Google Patents

Abstract

The present specification discloses a foldable display device. The foldable display includes: a display panel having two or more flat areas and a folding area between the flat areas; and a support member having a multilayer structure disposed on one surface of the display panel and supporting the display panel, wherein the support member has an opening pattern in an area corresponding to the folded area.

Description

Foldable display device {FOLDABLE DISPLAY DEVICE}

This specification relates to a foldable display device.

A video display device that implements various information on a screen is a key technology in the information and communication era, and is developing in the direction of thinner, lighter, more portable and high-performance. Accordingly, an organic light emitting display device that displays an image by controlling the amount of light emitted from the organic light emitting diode is in the spotlight.

The organic light emitting device is a self-luminous device using a thin light emitting layer between electrodes, and has an advantage that it can be thinned. A typical organic light emitting display device has a structure in which a pixel driving circuit and an organic light emitting device are formed on a substrate, and an image is displayed while light emitted from the organic light emitting device passes through a substrate or a barrier layer.

Since the organic light emitting display device is implemented without a separate light source device, it is easy to be implemented as a flexible, bendable, or foldable display device. In this case, a flexible material such as plastic or metal foil is used as a substrate of the organic light emitting display device. In addition, in the flexible or foldable display device, a plurality of thin film layers are generally stacked on a substrate.

For example, a foldable display may consist of several functional films and a series of adhesive layers for lamination thereof. A foldable display device needs to be quickly restored to its original state after being folded and unfolded due to its characteristics. However, the materials currently used have limitations in complete restoration, and the restoration performance is further deteriorated under high temperature/high humidity environments. Accordingly, in order to improve the usability of the foldable display device, material or structural improvement has been requested to secure flexibility and stability.

An object of the present specification is to propose a foldable display device and a folding structure used therein. The tasks of the present specification are not limited to the tasks mentioned above, and other tasks not mentioned will be clearly understood by those skilled in the art from the following description.

According to an embodiment of the present specification, a foldable display is provided. The foldable display includes: a display panel having two or more flat areas and a folding area between the flat areas; and a support member having a multilayer structure disposed on one surface of the display panel and supporting the display panel, wherein the support member has an opening pattern in an area corresponding to the folded area. .

The support member may include: a first metal layer under the display panel; and a second metal layer under the first metal layer and having an opening pattern in a region corresponding to the folded region, wherein the first metal layer has no opening pattern in a region corresponding to the folded region. .

The second metal layer may be thicker than the first metal layer.

The support member may further include a third metal layer under the second metal layer and having an opening pattern in a region corresponding to the folded region.

The third metal layer may be thicker than the second metal layer.

The third metal layer may have an opening pattern wider than that of the second metal layer.

The first metal layer may reduce screen non-uniformity due to an opening pattern in the second metal layer or the third metal layer.

The opening pattern may be a slit extending in a direction parallel to the folding axis.

The opening pattern may have at least one shape selected from among a rectangle, a rhombus, an ellipse, and a rectangle with rounded corners.

At least a portion of the opening pattern may be filled with silicon.

An adhesive layer between the display panel and the support member may be further included.

The second metal layer or the third metal layer may also have an opening pattern in a region corresponding to the flat region.

Details of other embodiments are included in the detailed description and drawings.

Embodiments of the present specification may provide a support structure suitable for dynamic behavior of the foldable display device. Furthermore, embodiments of the present specification may provide an adhesive member that enhances the folding characteristics and restoring force of the foldable display device. Furthermore, the foldable display device may improve screen non-uniformity in the folded area. Effects according to the embodiments of the present specification are not limited by the contents exemplified above, and more various effects are included in the present specification.

1 illustrates an exemplary foldable display.
2 is a cross-sectional view illustrating a part of a display panel included in the display device of the present specification.
3A and 3B are diagrams for explaining a foldable display device according to an embodiment of the present specification.
4A to 4C are cross-sectional views illustrating a foldable display device according to an exemplary embodiment of the present specification.
5A to 5D are views for explaining the shape of the opening pattern applied to the support member according to the embodiment of the present specification.
6A to 6D are views for explaining an arrangement of an opening pattern applied to a support member according to an embodiment of the present specification.

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.

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. Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 illustrates an exemplary foldable display.

The foldable display device 1000 may include at least one active area. For example, the foldable display may have a plurality of display areas divided into left and right (or up and down) based on a folding line. An array of pixels is formed in the display area. One or more inactive areas may be disposed around the display area. That is, the non-display area may be adjacent to one or more side surfaces of the display area. In FIG. 1 , the non-display area surrounds a rectangular display area. However, the shape of the display area and the shape/arrangement of the non-display area adjacent to the display area are not limited to the example illustrated in FIG. 1 . The display area and the non-display area may have a shape suitable for designing an electronic device on which the display device 1000 is mounted. Exemplary shapes of the display area are pentagonal, hexagonal, circular, oval, and the like.

Each pixel in the display area may be associated with a pixel circuit. The pixel circuit may include one or more switching transistors and one or more driving transistors on a backplane. Each pixel circuit may be electrically connected to a gate line and a data line to communicate with one or more driving circuits such as a gate driver and a data driver located in the non-display area.

As shown in FIG. 1 , the driving circuit may be implemented as a thin film transistor (TFT) in the non-display area. Such a driving circuit may be referred to as a gate-in-panel (GIP). In addition, some components such as data driver IC are mounted on a separate printed circuit board, and circuit films such as FPCB (flexible printed circuit board), COF (chip-on-film), TCP (tape-carrier-package), etc. It can be combined with a connection interface (pad/bump, pin, etc.) disposed in the non-display area by using the .

The foldable display 1000 may include various additional elements for generating various signals or driving pixels in the display area. Additional elements for driving the pixel may include an inverter circuit, a multiplexer, an electrostatic discharge circuit, and the like. The display device 1000 may also include additional elements related to functions other than driving pixels. For example, the display device 1000 may include additional elements that provide a touch sensing function, a user authentication function (eg, fingerprint recognition), a multi-level pressure sensing function, a tactile feedback function, and the like. The above-mentioned additional elements may be located in the non-display area and/or in an external circuit connected to the connection interface.

Various parts of the display device 1000 may be bent along the curved line FL. The curved line FL may extend horizontally (eg, in the X direction of FIG. 1 ), vertically (eg, in the Y direction of FIG. 1 ), or diagonally. Based on the design, it can be bent in any combination of horizontal, vertical and diagonal directions.

As mentioned, one or more edges of the display device 1000 may be bent to move away from a central portion 1000 - 1 along the curved line FL. Although the curved line FL is illustrated to be positioned close to the edge of the display device 1000 , the curved line FL extends across the central portion 1000 - 1 or the display device 1000 . may extend diagonally at one or more corners of

In some embodiments, the curved portion 1000 - 2 of the foldable display 100 may include a display area capable of displaying an image. Such a display area is hereinafter referred to as an auxiliary display area. That is, the curved line FL may be disposed in the display area such that at least some pixels of the display area are included in the curved portion 1000 - 2 .

2 is a cross-sectional view illustrating a part of a display panel included in the display device of the present specification.

The display device `1000 may include a display panel 100 displaying an image and various mechanical parts (frame, case, etc.) A foldable display device and its display panel will be described.

In the organic light emitting display panel 100 , thin film transistors 102 , 104 , 106 and 108 , organic light emitting devices 112 , 114 , 116 and various functional layers are positioned on a base layer 101 .

The base layer 101 supports various components of the organic light emitting display panel 100 . The base layer 101 may be formed of a transparent insulating material, for example, an insulating material such as glass or plastic. When the base layer 101 is made of plastic, it may be referred to as a plastic film or a plastic substrate. For example, the base layer 101 may be in the form of a film including one selected from the group consisting of a polyimide-based polymer, a polyester-based polymer, a silicone-based polymer, an acrylic polymer, a polyolefin-based polymer, and a copolymer thereof. Among these materials, polyimide is widely used as a plastic substrate because it can be applied to high-temperature processes and can be coated. The substrate (array substrate) is also referred to as a concept including a device and a functional layer formed on the base layer 101, for example, a switching TFT, a driving TFT connected to the switching TFT, an organic light emitting element connected to the driving TFT, a protective film, etc. do.

A buffer layer may be positioned on the base layer 101 . The buffer layer is a functional layer for protecting a thin film transistor (TFT) from impurities such as alkali ions leaking from the base layer 101 or the underlying layers. The buffer layer may be formed of silicon oxide (SiOx), silicon nitride (SiNx), or a multilayer thereof.

A thin film transistor is placed on the base layer 101 or the buffer layer. The thin film transistor may have a form in which the semiconductor layer 102 , the gate insulating layer 103 , the gate electrode 104 , the interlayer insulating layer 105 , and the source and drain electrodes 106 and 108 are sequentially disposed. The semiconductor layer 102 is located on the base layer 101 or the buffer layer. The semiconductor layer 102 may be made of polysilicon (p-Si), and in this case, a predetermined region may be doped with an impurity. In addition, the semiconductor layer 102 may be made of amorphous silicon (a-Si) or various organic semiconductor materials such as pentacene. Furthermore, the semiconductor layer 102 may be made of oxide. The gate insulating layer 103 may be formed of an insulating inorganic material such as silicon oxide (SiOx) or silicon nitride (SiNx), or may be formed of an insulating organic material or the like. The gate electrode 104 may be formed of various conductive materials, for example, magnesium (Mg), aluminum (Al), nickel (Ni), chromium (Cr), molybdenum (Mo), tungsten (W), gold (Au), or an alloy thereof. and the like.

The interlayer insulating layer 105 may be formed of an insulating material such as silicon oxide (SiOx) or silicon nitride (SiNx), and may also be formed of an insulating organic material. By selectively removing the interlayer insulating layer 105 and the gate insulating layer 103 , a contact hole through which the source and drain regions are exposed may be formed.

The source and drain electrodes 106 and 108 are formed on the interlayer insulating film 105 in the form of a single layer or a multi-layered electrode material.

A planarization layer 107 may be disposed on the thin film transistor. The planarization layer 107 protects the thin film transistor and planarizes the top thereof. The planarization layer 107 may be configured in various forms, and may be formed of an organic insulating film such as BCB (Benzocyclobutene) or Acryl, or an inorganic insulating film such as a silicon nitride film (SiNx) or a silicon oxide film (SiOx), Various modifications are possible, such as being formed in a single layer or may be configured in double or multiple layers.

The organic light emitting device may have a form in which the first electrode 112 , the organic light emitting layer 114 , and the second electrode 116 are sequentially disposed. That is, the organic light emitting diode includes a first electrode 112 formed on the planarization layer 107 , an organic light emitting layer 114 located on the first electrode 112 , and a second electrode ( 116) can be configured.

The first electrode 112 is electrically connected to the drain electrode 108 of the driving TFT through a contact hole. When the organic light emitting display panel 100 is a top emission type, the first electrode 112 may be made of an opaque conductive material having high reflectance. For example, the first electrode 112 may be formed of silver (Ag), aluminum (Al), gold (Au), molybdenum (Mo), tungsten (W), chromium (Cr), or an alloy thereof. .

The bank 110 is formed in the remaining area except for the light emitting area. Accordingly, the bank 110 has a bank hole exposing the first electrode 112 corresponding to the emission region. The bank 110 may be made of an inorganic insulating material such as a silicon nitride film (SiNx) or a silicon oxide film (SiOx), or an organic insulating material such as BCB, an acrylic resin, or an imide resin.

An organic light emitting layer 114 is located on the first electrode 112 exposed by the bank 110 . The organic light emitting layer 114 may include an emission layer, an electron injection layer, an electron transport layer, a hole transport layer, a hole injection layer, and the like. The organic light emitting layer may have a structure of a single light emitting layer that emits one light, or a structure of a plurality of light emitting layers that emit white light.

The second electrode 116 is positioned on the organic light emitting layer 114 . When the organic light emitting display panel 100 is a top emission type, the second electrode 116 is a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). By being formed of a material, light generated from the organic light emitting layer 114 is emitted to the upper portion of the second electrode 116 .

A protective layer 118 and an encapsulation layer 120 are disposed on the second electrode 116 . The protective layer 118 and the encapsulation layer 120 prevent the penetration of oxygen and moisture from the outside in order to prevent oxidation of the light emitting material and the electrode material. When the organic light emitting diode is exposed to moisture or oxygen, a pixel shrinkage phenomenon in which the light emitting area is reduced may occur or a dark spot may occur in the light emitting area. The passivation layer and/or the encapsulation layer may be formed of an inorganic film made of glass, metal, aluminum oxide (AlOx), or a silicon (Si)-based material, or an organic film and an inorganic film are alternately formed. It may have a laminated structure. The inorganic film serves to block the penetration of moisture or oxygen, and the organic film serves to planarize the surface of the inorganic film. The reason for forming the encapsulation layer as a multi-layered thin film layer is to make the movement path of moisture or oxygen longer and more complicated than that of a single layer, making it difficult to penetrate moisture/oxygen to the organic light emitting device.

In the organic light emitting display panel 100 , a touch panel 150 for sensing a user's touch input may be formed on the encapsulation layer 120 . If necessary, an independent layer provided with touch sensing electrodes and/or other components related to touch input sensing may be provided inside the display panel 100 . The touch sensing electrode (eg, touch driving/sensing electrode) is made of indium tin oxide, a carbon-based material such as graphene, carbon nanotubes, a conductive polymer, a hybrid material made of a mixture of various conductive/non-conductive materials, etc. It may be formed of a transparent conductive material. In addition, a metal mesh, for example, an aluminum mesh, a silver mesh, etc. may be used as the touch sensing electrode.

The cover layer 180 may be used to protect an upper portion of the display panel 100 . The cover layer 140 may be a cover glass. A polarization layer for controlling display characteristics (eg, external light reflection, color accuracy, luminance, etc.) may be located on one surface of the cover layer 180 , and in one embodiment, as shown in FIG. 4B , on the lower surface of the cover layer 180 . A polarization layer 170 may be coated.

In order to increase strength and/or rigidity in a specific portion of the foldable display 1000 , one or more reinforcing films may be provided under the base layer 101 . The reinforcing film is attached to a surface (second surface) opposite to the surface (first surface) on which the organic light emitting device is located among both surfaces of the base layer 101 . The reinforcing film may include polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyethylene ether phthalate, polycarbonate, polyarylate, polyetherimide ( polyether imide), polyether sulfonate, polyimide, polyacrylate, and other suitable polymer combinations. Another material that can be used to form the reinforcing film may be thin glass, a multilayer polymer, a polymer film including a polymer material in combination with nanoparticles or microparticles, and the like.

3A and 3B are diagrams for explaining a foldable display device according to an embodiment of the present specification.

The foldable display device may be composed of a plurality of thin film layers and an adhesive bonding them, and due to material properties and limitations, flatness when folded, repeatedly folded, and/or stored in a folded state for a long time. maintenance is important.

The foldable display device may include two or more flat areas A-1 and A-2 and a folded area F between the flat areas A-1 and A-2 as shown in FIG. 3A. and can be folded as shown in FIG. 3B . The flat areas A-1 and A-2 are substantially flat areas (portions) having a very small curvature compared to the folded area F, and may include a display area, and, if necessary, include a non-display area and a non-display area; In Fig. 3a, only two flat areas are shown, but the actual product may consist of two or more flat areas. Folding area (center bezel) Since the width of is correlated with the folding radius, it can be determined based on this, and it is preferable to design in consideration of the encapsulation margin. The folded region F may be understood as the sum of the actual folded portion and the encapsulation margin.

The pixel matrix in the second flat area A-2 may continuously extend from the first flat area A-1. Alternatively, in FIG. 3A , the first flat area and the second flat area may be separated from each other with a folded area therebetween. Some components of the first flat region and the second flat region may be electrically connected via one or more leads that run across the fold region. The pixels of the first flat area A-1 and the pixels of the second flat area A-2 may be driven by a driving circuit (eg, a gate driver, a data driver, etc.) as if they are in the same matrix. In this case, the pixel of the first flat area A-1 and the pixel of the second flat area A-2 may be operated by the same driving circuits. For example, the N-th row pixel of the first flat area A-1 and the N-th row pixel of the second flat area A-2 may be provided to receive a gate signal from the same gate driver. Depending on the embodiment, the pixel of the second flat area A-2 may be driven separately from the pixel of the first flat area A-1. That is, the pixels of the second flat area A-2 may be recognized by the driving circuit as an independent matrix separated from the pixel matrix of the flat area. In this case, the pixels of the second flat area A-2 may receive signals from one or more separate drive circuits different from the drive circuits that supply signals to the pixels of the first flat area A-1. . Meanwhile, regardless of the shape, the second flat area A - 2 may function as a secondary display area of the foldable display panel 100 . In addition, the size ratio in particular of the 1st flat area|region A-1 to the 2nd flat area|region A-2 is not restrict|limited.

In the foldable display 1000 that is folded (or bent) as shown in FIG. 3B , it is important that the support member 300 is designed so that excessive compressive or tensile force is not applied to the display panel 100 . In addition, the shape and material of the support member 300 are also very important in order to maintain flatness and/or to quickly restore the shape of the foldable display 1000 . Although FIG. 3B shows an inward foldable display device, the same importance is also applied to an outward foldable display device that is folded in the opposite direction.

4A to 4C are cross-sectional views illustrating a foldable display device according to an exemplary embodiment of the present specification.

The foldable display 1000 may have a structure in which the display panel 100 and the support member 300 are bonded to each other as shown in FIG. 4A . The foldable display 1000 includes two or more flat areas and a folded area F between the flat areas, and the foldable area F has a structure with improved foldability and restoring force. may include The display panel 100 has a structure in which an organic light emitting device layer (TFT/OLED), a touch panel 150, a polarization layer 170, a cover layer 180, etc. are stacked on a flexible base layer 101 as shown in FIG. 2 . and the support member 300 may be further positioned under the display panel 100 . An adhesive layer and/or the reinforcing film may be further positioned between the display panel 100 and the supporting member.

Since the fold area F is most affected by bending stress, various stress reduction structures may be applied to the display panel 100 on the fold area. To this end, some of the components in the flat area may not exist in at least a portion of the folded area F. For example, an organic light emitting diode (eg, a pixel circuit and an organic light emitting diode) may not be disposed in the folded region F. In addition, only a minimum number of layers may be disposed in the folding area F. For example, in the folded region F, only a base layer, an organic layer on the base layer, and a cover layer on the organic layer may be disposed. Also, in the folded region F, a patterned inorganic layer may be further disposed between the base layer and the organic layer. The inorganic layer may be a buffer layer. The patterning may be implemented through a series of etching processes. The pattern may be in the form of a stripe parallel to a folding axis, and a pitch thereof may be designed in consideration of a folding curvature.

The support member 300 is located on one surface (lower surface) of the display panel 100 . For example, as shown in FIG. 4B , the support member 300 may surround the outer surface of the display panel 100 from the rear in the screen display direction. The support member 300 serves to support the display panel 100 . Accordingly, the support member 300 has greater stiffness than the display panel.

When the folding and unfolding operation of the foldable display 1000 is repeated, plastic deformation may occur in the support member 300 , thereby limiting folding/unfolding of the foldable display 10 . This plastic deformation problem can be reduced by reducing the thickness of the support member 300, but when the thickness of the support member 300 is reduced, the elastic restoring energy also decreases, a trade-off that takes a long time to restore the shape ( trade-offs) may appear.

Accordingly, the inventors have devised a support member that is thin and has sufficient rigidity to support the display panel and has excellent restoring force after deformation. The support member 300 according to the exemplary embodiment of the present specification designed as described above may be a multi-layer structure composed of two or more metal layers.

As shown in FIG. 4B , the support member 300 may include two or more metal layers having high stiffness and/or Young's modulus to have high restoring force. The metal layers 310 , 320 , 330 , and 340 have a folded region F between the flat regions in the same manner as the region division of the foldable display 1000 . Also, at least one of the metal layers 310 , 320 , 330 , and 340 may have opening patterns 321 , 331 , and 341 in the folded region F . Furthermore, the support member 300 may include a structure capable of preventing image quality deterioration due to the opening patterns 321 , 331 , and 341 .

All of the metal layers 310 , 320 , 330 , and 340 included in the support member 300 may be of the same type (material), or different types of metal layers depending on the embodiment. All of the metal layers 310 , 320 , 330 , and 340 may have a yield stress of 1 GPa or more.

When an object receives a force from the outside, strain and stress increase in proportion to the force until a certain point, whereas when the force is removed, the strain and stress decrease linearly and return to the original shape before deformation. However, if the magnitude of the force exceeds a certain value, even if the force is removed, the object cannot be restored to its initial shape and maintains a certain degree of permanent deformation. And from this point on, the strain and stress no longer maintain a linear relationship, and at the same time exhibit a sharp strain and finally reach failure. The yield stress refers to a stress value that is a criterion for distinguishing such a distinct object behavior. That is, below the yield stress, the strain and stress maintain a linear relationship, and when the force is removed, no permanent deformation remains. However, at a force greater than the yield stress, the strain and stress exhibit a marked non-linear relationship, and even if the force is removed, the object exhibits permanent deformation.

In the support member 300 having four layers as shown in FIGS. 4B and 4C , the first metal layer 310 , the second metal layer 320 , and the third metal are sequentially from the metal layer close to the display panel 100 . The layer 330 is referred to as a fourth metal layer 340 . In the example of FIGS. 4B and 4C , the second metal layer 320 , the third metal layer 330 , and the fourth metal layer 340 include opening patterns 321 , 331 , 341 in the folded region F . .

The opening patterns 321 , 331 , and 341 included in the second to fourth metal layers 320 , 330 , and 340 reduce stress when the support member 300 is folded. The shape and arrangement of the opening pattern in each metal layer will be described in more detail with reference to FIGS. 5 to 6 . The opening patterns 321 , 331 , and 341 may be slits having various shapes, such as a rectangle, a rhombus, and an ellipse, and the widths w2 , w3 , and w4 may become wider toward the bottom. (w2<w3<w4) That is, the metal layer further away from the display panel has a wider opening pattern.

At least one metal layer included in the support member 300 has no opening pattern. In FIGS. 4B and 4C , there is no opening pattern in the first metal layer 310 . The reason why the support member 300 includes the metal layer having no opening pattern is to make the brightness of the display panel uniform. As a result of the test, when the foldable display device was unfolded, unevenness of brightness such as unevenness appeared in the folded area. It was also confirmed that the above-described non-uniformity could be prevented by placing a metal layer without an opening pattern between the display panel 100 and the metal layer having the opening pattern. Accordingly, in the support member 300 according to the exemplary embodiment of the present specification, one or more metal layers 310 having no opening pattern are disposed closest to the display panel 100 . That is, at least one metal layer without an opening pattern is positioned between the display panel 100 and the metal layer having the opening pattern.

Meanwhile, the metal layers 310 , 320 , 330 , and 340 included in the support member 300 may have different thicknesses, and the thicknesses t1 , t2 , t3 , and t4 may become thicker toward the bottom. . (t1 < t2 < t3 < t4) That is, the metal layer further away from the display panel 100 may be thicker. In the illustrated FIG. 4B , the thickness t1 of the first metal layer 310 is the thinnest, and the thickness t4 of the fourth metal layer 340 is the thickest.

The opening pattern is formed in the folded region (F). However, according to an embodiment, the opening pattern may also be provided outside the folded area, that is, in the flat area.

At least a portion of the opening patterns 321 , 331 , and 341 may be filled with any one or more of polyurethane (PU), thermoplastic polyurethane (TPU), polyacrylate, rubber, and silicon (Si).

5A to 5D are views for explaining the shape of the opening pattern applied to the support member according to the embodiment of the present specification.

The opening pattern is provided to improve folding and restoration characteristics of the metal layer constituting the support member. The opening pattern is formed in the folded region (F). However, according to an embodiment, the opening pattern may also be provided outside the folded area, that is, in the flat area.

5A to 5D show only the second metal layer 320 and the opening pattern 321 therein for convenience of explanation, but the opening pattern 321 includes the third metal layer 330 and the fourth metal layer 340 . ) can also be applied. Also, although the folded region F is illustrated as being positioned at a specific portion of the metal layer 320 in FIGS. 5A to 5D , the position of the folded region F is not limited thereto. In addition, two or more folding regions F may be defined.

As shown in FIG. 5A , the opening pattern 321a may have a rectangular shape. In this case, the opening pattern 321a may extend in a direction parallel to the fold line (fold axis). That is, a long axis of the opening pattern 321a may be parallel to a fold line (fold axis) and a direction. The rectangular shape may have a specific length L1 and may be spaced apart from each other by a specific distance D1 on the same line.

Also, as shown in FIGS. 5B and 5C , each of the opening patterns 321b may have a rhombus shape. In this case, the opening patterns 321b and 321c may extend in a direction parallel to a fold line (fold axis). That is, the long axis of the opening patterns 321b and 321c may be parallel to the fold line (fold axis) and the direction. The rhombus (diamond) shape may have specific lengths L2 and L3 and may be spaced apart from each other by specific distances D2 and D3 on the same line. Meanwhile, the rhombus shapes arranged in the same column may be placed in parallel with the rhombus shapes arranged in an adjacent column (FIG. 5B) or may be displaced (FIG. 5C).

As shown in FIG. 5D , the opening pattern 321d may have an elliptical shape having a constant minor axis length, or a shape in which semicircles are coupled to both ends of a rectangle. In this case, the opening pattern 321d may have a shape extending in a direction parallel to the fold line (folding axis). That is, the long axis of the opening pattern 321d may be parallel to the fold line (fold axis) and the direction. The ellipse (or rectangular shape with rounded corners) may have a specific length L4 and may be spaced apart from each other by a specific distance D4 on the same line.

5A to 5D , the opening patterns 321a , 321b , 321c , and 321d are exemplified in a rectangular shape, a rhombus shape, or an elliptical shape, but the shape of the opening pattern is not limited thereto. For example, the opening pattern may have other shapes such as a circle, an ellipse, a square, a trapezoid, and the like. Also, only one opening pattern shape may be provided in one metal layer. In other words, opening patterns of various shapes may be provided in one metal layer.

6A to 6D are views for explaining an arrangement of an opening pattern applied to a support member according to an embodiment of the present specification.

6A to 6D show only the second metal layer 320 and the opening pattern 321 therein from among the metal layers included in the support member for convenience of explanation, but the opening pattern 321 is a third metal layer ( 330) and the fourth metal layer 340 may also be applied. Also, although the folded region F is illustrated as being positioned at a specific portion of the metal layer 320 in FIGS. 6A to 6D , the location of the folded region F is not limited thereto.

As shown in FIGS. 6A and 6B , a folded region F is defined in the metal layer 320 , and the folded region F may be divided into a central portion CN and edge portions ED1 and ED2 . In this case, the opening patterns 321 formed in the folded region F have the same size and have different distances therebetween. (pitch variable)

The folded area F is divided into a central portion CN, a first edge portion ED1, and a second edge portion ED2, and the opening pattern 321 is first spaced apart from the first edge portion ED1 in the folding direction. It has a distance d1, has a second separation distance d2 from the central portion CN, and has a third separation distance d3 greater than the second separation distance and smaller than the first separation distance from the second edge portion ED2. That is, the separation distance of the opening pattern 321 may decrease from the edge of the folded region F toward the center. Stress may be concentrated at the point where the curvature of the foldable display starts (ie, the first edge portion ED1 ), and thus the display panel may be damaged. In the support member of the present specification, the folded region F of the metal layer 320 is ), the radius of curvature at the folding start point may be increased and stress concentration may be alleviated by adjusting the distance between the opening patterns 321 formed in the .

As shown in FIGS. 6C and 6D , a folded region F is defined in the metal layer 320 , and the folded region F may be divided into a central portion CN and edge portions ED1 and ED2 . In this case, the opening patterns 321 formed in the folded region F are arranged at the same distance and have different sizes. (size variable)

The folded region F is divided into a central portion CN, a first edge portion ED1 , and a second edge portion ED2 , and the opening pattern 321 has a first width at the first edge portion ED1 in the folding direction. (w1), a second width w2 at the central portion CN, and a third width w3 greater than the first width and smaller than the second width at the second edge portion ED2. That is, the size (width) of the opening pattern 321 may gradually increase from the edge of the folded region F toward the center. In the support member of the present specification, the size of the opening pattern 321 formed in the folding region F of the metal layer 320 is adjusted, so that the radius of curvature at the folding start point is increased and stress concentration is relieved. Accordingly, damage to the display panel is minimized or prevented.

The arrangement change and size change of the opening patterns illustrated in FIGS. 6A and 6B and 6C and 6D may be applied together in one metal layer.

Although the embodiments of the present specification have been described in detail with reference to the accompanying drawings, the present specification is not necessarily limited to these embodiments, and various modifications may be made without departing from the technical spirit thereof. Therefore, the embodiments disclosed in the present specification are for explanation rather than limiting the technical spirit of the present invention, and the scope of the technical spirit of the present invention is not limited by these embodiments. Each feature of the various embodiments of the present invention may be partially or wholly combined or combined with each other, and may be technically variously linked and operated by those skilled in the art, and each embodiment may be implemented independently of each other or together in a related relationship. may be carried out. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

Claims (12)

a display panel having two or more flat areas and a folding area between the flat areas; and
a support member positioned on one surface of the display panel and having a multilayer structure for supporting the display panel;
The support member has a multi-layer structure composed of two or more metal layers,
The support member has an opening pattern in an area corresponding to the folded area. According to claim 1,
The support member is
a first metal layer under the display panel; and
a second metal layer under the first metal layer and having an opening pattern in a region corresponding to the folded region;
The foldable display device in which the first metal layer has no opening pattern in an area corresponding to the fold area. 3. The method of claim 2,
The second metal layer is thicker than the first metal layer. 3. The method of claim 2,
The support member is
and a third metal layer under the second metal layer and having an opening pattern in an area corresponding to the folded area. 5. The method of claim 4,
The third metal layer is thicker than the second metal layer. 5. The method of claim 4,
The third metal layer has an opening pattern wider than that of the second metal layer. 5. The method of claim 4,
The first metal layer may reduce a screen non-uniformity caused by an opening pattern in the second metal layer or the third metal layer. According to claim 1,
The opening pattern is a slit having a shape extending in a direction parallel to the folding axis. 9. The method of claim 8,
The opening pattern has a shape of at least one of a rectangle, a rhombus, an ellipse, and a rectangle with rounded corners. According to claim 1,
At least a portion of the opening pattern is filled with silicon. According to claim 1,
The foldable display device further comprising an adhesive layer between the display panel and the support member. 5. The method of claim 4,
The second metal layer or the third metal layer has an opening pattern in an area corresponding to the flat area as well.

Images