Flexible display device metal support, method of manufacturing the same, and flexible display device

Abstract

To provide a flexible display device metal support capable of improving bending resistance of a bending portion of a flexible display device, a method of manufacturing the same, and a flexible display device.SOLUTION: A flexible display device metal support 10 is provided, comprising a first layer 20 having a first surface 20a and a second surface 20b, and a second layer 30 bonded to the second surface 20b of the first layer 20. The second layer 30 has at least first holes 31 open toward a side opposite a joint surface with the first layer 20.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to a metal support for a flexible display device, a method for manufacturing the same, and a flexible display device. [Background technology]

[0002] In recent years, foldable display devices have become known for use in, for example, smartphones, tablets, etc. As such display devices, there are flexible display devices that have a bendable portion in a portion thereof (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-86462 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for a smaller shape of the bent portion when a flexible display device is folded. In other words, there is a demand for a smaller radius of curvature of the bent portion. However, when the shape of the bent portion is made smaller, it becomes difficult to maintain the strength of the bent portion.

[0005] The present disclosure provides a metal support for a flexible display device, which is capable of improving the bending resistance of a bent portion of the flexible display device, a manufacturing method thereof, and a flexible display device. [Means for solving the problem]

[0006] The embodiments of the present disclosure relate to the following [1] to

[12] .

[0007] [1] A metal support for a flexible display device, comprising: a first layer having a first surface and a second surface; and a second layer bonded onto the second surface of the first layer, the second layer having at least a first hole that opens toward the opposite side to the bonding surface with the first layer.

[0008] [2] The metal support for a flexible display device according to [1], wherein the first layer has no holes.

[0009] [3] The metal support for a flexible display device according to [1] or [2], wherein the first hole is a through hole.

[0010] [4] The metal support for a flexible display device according to [1] or [3], wherein the first layer has a second hole.

[0011] [5] The metal support for a flexible display device described in [4], wherein the second hole opens toward at least the second surface side, and the second layer is housed within the second hole.

[0012] [6] The metal support for a flexible display device according to [4], wherein the second hole overlaps with the first hole in a planar view.

[0013] [7] The metal support for a flexible display device described in any one of [1] to [6], further comprising a third layer bonded onto the first surface of the first layer.

[0014] [8] The metal support for a flexible display device according to [7], wherein the third layer has a third hole.

[0015] [9] The metal support for a flexible display device according to [7] or [8], wherein the first layer has a fourth hole, and the third layer is housed within the fourth hole.

[0016]

[10] The metal support for a flexible display device according to any one of [1] to [6], further comprising a third layer bonded to the second layer.

[0017]

[11] A flexible display device comprising: a display member; and a metal support for a flexible display device according to any one of [1] to

[10] that supports the display member.

[0018]

[12] A method for manufacturing a metal support for a flexible display device, comprising the steps of: preparing a second layer having a first hole; preparing a first layer having a first surface and a second surface; and bonding the second layer onto the second surface of the first layer so that the first hole opens at least toward the opposite surface to the bonding surface with the first layer. Effect of the Invention

[0019] According to the present disclosure, it is possible to improve the bending resistance of the bending portion of a flexible display device. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a perspective view showing a flexible display device according to an embodiment. [Diagram 2] FIG. 2 is a plan view showing a flexible display device according to an embodiment. [Diagram 3] FIG. 3 is a cross-sectional view (cross-sectional view taken along line III-III in FIG. 2) showing the flexible display device (in an unfolded state) according to the embodiment. [Figure 4] FIG. 4 is a cross-sectional view showing a flexible display device (in a folded state) according to an embodiment. [Diagram 5] FIG. 5 is a plan view showing a metal support for a flexible display device according to an embodiment. [Figure 6] FIG. 6 is a cross-sectional view showing a metal support for a flexible display device according to an embodiment (a cross-sectional view taken along line VI-VI in FIG. 5). [Figure 7] FIG. 7 is a partially enlarged cross-sectional view showing a metal support for a flexible display device according to an embodiment (a cross-sectional view taken along line VII-VII in FIG. 5). [Figure 8] FIG. 8 is a plan view showing a metal support for a flexible display device according to a modified example. [Figure 9] 9(a) to 9(f) are cross-sectional views illustrating a method for manufacturing a metal support for a flexible display device according to an embodiment. [Figure 10] FIG. 10 is a cross-sectional view showing a metal support for a flexible display device according to a first modified example. [Figure 11] FIG. 11 is a cross-sectional view showing a metal support for a flexible display device according to a second modified example. [Figure 12] FIG. 12 is a cross-sectional view showing a metal support for a flexible display device according to a third modified example. [Figure 13] FIG. 13 is a cross-sectional view showing a metal support for a flexible display device according to a fourth modified example. [Figure 14] FIG. 14 is a cross-sectional view showing a metal support for a flexible display device according to a fifth modified example. [Figure 15] FIG. 15 is a cross-sectional view showing a metal support for a flexible display device according to a sixth modified example. [Figure 16] FIG. 16 is a cross-sectional view showing a metal support for a flexible display device according to a seventh modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] An embodiment of the present disclosure will be described with reference to Figures 1 to 8. In the following figures, the same parts are denoted by the same reference numerals, and some detailed description may be omitted.

[0022] In this specification, the first direction D1 refers to a direction located on a plane parallel to the main surface of the metal support 10 for a flexible display device or the flexible display device 70 and perpendicular to the folding center line FL. The second direction D2 refers to a direction located on a plane parallel to the main surface of the metal support 10 for a flexible display device or the flexible display device 70 and parallel to the folding center line FL. The first direction D1 and the second direction D2 may be parallel to each side of the metal support 10 for a flexible display device or the flexible display device 70. The first direction D1 and the second direction D2 are orthogonal to each other. The third direction D3 refers to a direction perpendicular to both the first direction D1 and the second direction D2 and parallel to the thickness direction of the metal support 10 for a flexible display device or the flexible display device 70.

[0023] (Configuration of metal support for flexible display device) First, an outline of a flexible display device according to the present embodiment will be described with reference to Figures 1 to 4. Figures 1 to 4 are diagrams showing a flexible display device according to the present embodiment.

[0024] The flexible display device 70 shown in FIG. 1 and FIG. 2 may be, for example, an organic electroluminescence (EL) display device. The flexible display device 70 is flexible and has a foldable structure. That is, the flexible display device 70 can be in a folded state (see FIG. 4) in a folded state and in an unfolded state (see FIG. 2 and FIG. 3) in an unfolded state. The folded state is a state in which the flexible display device 70 is folded around a folding center line FL. In the folded state, the display members 71 are folded in a direction in which the outer surfaces of the display members 71 approach each other. However, this is not limited to this, and the display members 71 may be folded in a direction in which the outer surfaces of the housings 78 approach each other. The unfolded state is a state in which the flexible display device 70 is opened without being folded. In the unfolded state, the entire surface of the display member 71 is substantially located on the same plane. Such a flexible display device 70 may be a thin electronic device having a portion for displaying an image. Such an electronic device may be, for example, a mobile terminal device such as a smartphone or a tablet.

[0025] 3, the flexible display device 70 includes a display member 71 and a metal support 10 for a flexible display device (hereinafter, simply referred to as the metal support 10) that supports the display member 71. A buffer layer 76 such as a cushion sheet is provided between the display member 71 and the metal support 10. A heat dissipation layer 77 is disposed on the surface of the metal support 10 opposite to the display member 71. Furthermore, the display member 71, the buffer layer 76, the metal support 10, and the heat dissipation layer 77 are supported by a housing 78.

[0026] The display member 71 has a supporting substrate 72, a thin film transistor (TFT) 73, an organic EL element 74, and a sealing resin 75. The thin film transistor 73 is disposed on the supporting substrate 72. The organic EL element 74 is disposed on the thin film transistor 73. The sealing resin 75 is disposed on the organic EL element 74.

[0027] The support base material 72 supports the entire display member 71 and may be a flexible film. The support base material 72 may be made of a synthetic resin material such as polyethylene terephthalate. The thin film transistor 73 drives the organic EL element 74 and controls the voltage applied to the electrode of the organic EL element 74. The organic EL element 74 displays an image or the like by emitting light by itself. The organic EL element 74 is electrically connected to the thin film transistor 73. The organic EL element 74 may be called a light-emitting portion. The organic EL element 74 may have a reflective electrode, an organic light-emitting layer, and a transparent electrode, which are not shown. The sealing resin 75 seals the organic EL element 74 and protects the organic EL element 74. The display member 71 is not limited to an organic EL display device. For example, the display member 71 may be another display device having a function of emitting light by itself. The display member 71 may be a micro LED display device including a micro LED element (light emitter).

[0028] The buffer layer 76 is a layer that relieves stress applied to the display member 71 when the flexible display device 70 is bent. The buffer layer 76 may be a layer of a resin material having elasticity, such as silicone resin, polyurethane resin, or epoxy resin. The metal support 10 is a member that increases the bending strength when the flexible display device 70 is bent. The configuration of the metal support 10 will be described later.

[0029] The heat dissipation layer 77 is a layer for dissipating heat from the display member 71 to the outside. The heat dissipation layer 77 may be a metal layer such as copper or nickel. The heat dissipation layer 77 may also be a plating layer produced by electrolytic plating. The housing 78 houses and protects the display member 71, the buffer layer 76, the metal support 10, and the heat dissipation layer 77. The housing 78 has a structure that allows it to be folded about a folding center line FL.

[0030] The flexible display device 70 has a bent region BA and a non-bent region NA. The bent region BA is a region that is physically deformed when the flexible display device 70 is in a bent state (see FIG. 4). The bending center line FL is located at approximately the center of the bent region BA. The non-bent region NA is a region that is not substantially deformed when the flexible display device 70 is in a bent state (see FIG. 4). In the first direction D1, the non-bent region NA is located on both sides of the bent region BA. The lengths of the two non-bent regions NA along the first direction D1 may be approximately the same. Not limited to this, the lengths of the two non-bent regions NA along the first direction D1 may be different from each other. The bent region BA is located at the center of the flexible display device 70 in the first direction D1. Not limited to this, the bent region BA may be located at a position other than the center of the flexible display device 70 in the first direction D1.

[0031] (Configuration of metal support for flexible display device) Next, an outline of the metal support for a flexible display device according to the present embodiment will be described with reference to Figures 5 to 7. Figures 5 to 7 are diagrams showing the metal support for a flexible display device according to the present embodiment.

[0032] As shown in FIGS. 5 to 7, the metal support 10 includes a first layer 20 and a second layer 30. The metal support 10 is a laminate of two layers. The first layer 20 has a first surface 20a and a second surface 20b. The first surface 20a faces the display member 71 of the flexible display device 70. The second surface 20b faces the heat dissipation layer 77 of the flexible display device 70. The first surface 20a and the second surface 20b are parallel to a plane formed by the first direction D1 axis and the second direction D2 axis, respectively. The second layer 30 is bonded onto the second surface 20b of the first layer 20. The second layer 30 has a first hole 31 penetrating the second layer 30 in the thickness direction.

[0033] The metal support 10 includes a bending region BA and a non-bending region NA. The bending region BA is a region that physically deforms when the flexible display device 70 is in a bent state (see FIG. 4). The folding center line FL is located approximately at the center of the bending region BA. The non-bending region NA is a region that does not substantially deform when the flexible display device 70 is in a bent state (see FIG. 4). The bending region BA and the non-bending region NA respectively correspond to the bending region BA and the non-bending region NA of the flexible display device 70 described above.

[0034] The first layer 20 may be a member that enhances the bending strength when the flexible display device 70 is folded. The first layer 20 holds the second layer 30. The first layer 20 does not have a hole. The first layer 20 has a rectangular shape in a plan view. This rectangle has a pair of long sides parallel to the first direction D1 and a pair of short sides parallel to the second direction D2. However, this is not limited to this, and a pair of short sides may be parallel to the first direction D1 and a pair of long sides parallel to the second direction D2. Each corner of the rectangle may be rounded. The first layer 20 may be a square, polygon, or circle in a plan view. The planar shape of the first layer 20 may correspond to the planar shape of the flexible display device 70. The planar shape of the first layer 20 may be the same as the planar shape of the flexible display device 70. Alternatively, the planar shape of the first layer 20 may be smaller than the planar shape of the flexible display device 70.

[0035] The first layer 20 has a flexible, bendable thin plate shape. In this specification, "flexible" means "capable of being bent to a radius of curvature of at least 5.0 mm or less, preferably 3.0 mm or less."

[0036] The length L1 of the first layer 20 along the first direction D1 may be 100 mm or more, or may be 200 mm or more. The length L1 of the first layer 20 along the first direction D1 may be 500 mm or less, or may be 400 mm or less. The length L2 of the first layer 20 along the second direction D2 may be 50 mm or more, or may be 150 mm or more. The length L2 of the first layer 20 along the second direction D2 may be 400 mm or less, or may be 350 mm or less.

[0037] The thickness T1 of the first layer 20 may be 30 μm or more, or may be 35 μm or more. By setting the thickness T1 of the first layer 20 to 30 μm or more, the bending strength of the first layer 20 can be maintained. The thickness T1 of the first layer 20 may be 50 μm or less, or may be 40 μm or less. By setting the thickness T1 of the first layer 20 to 50 μm or less, the flexible display device 70 incorporating the metal support 10 can be prevented from becoming excessively thick. When the first layer 20 is made of a carbon fiber composite material, the thickness T1 of the first layer 20 may be 10 μm or more, or may be 15 μm or more. When the first layer 20 is made of a carbon fiber composite material, the thickness T1 of the first layer 20 may be 50 μm or less, or may be 40 μm or less.

[0038] The main material of the first layer 20 may be a metal material. When the main material of the first layer 20 is a metal material, the metal material may be an iron-based alloy such as stainless steel, copper, a copper alloy, titanium, a titanium-based alloy, magnesium, or a magnesium-based alloy. When stainless steel is used as the main metal material of the first layer 20, the first layer 20 has good spring properties, so that the first layer 20 is easily bent. The main material of the first layer 20 may be a carbon fiber composite material (CFRP) or a resin material. The resin material may be polyimide (PI). In this specification, the term "main material" refers to a material contained in a certain member in an amount of more than 50 mass%, preferably more than 80 mass%.

[0039] The second layer 30 has a first surface 30a and a second surface 30b. The first surface 30a faces the display member 71 of the flexible display device 70. The first surface 30a may be referred to as a third surface. The second surface 30b faces the heat dissipation layer 77 of the flexible display device 70. The second surface 30b may be referred to as a fourth surface. The first surface 30a and the second surface 30b are each parallel to a plane formed by the first direction D1 axis and the second direction D2 axis.

[0040] The second layer 30 is bonded to the first layer 20. Specifically, a first surface 30a of the second layer 30 is bonded to a second surface 20b of the first layer 20. The second layer 30 may be bonded directly to the first layer 20, or may be bonded to the first layer 20 via another layer. The second layer 30 may be bonded to the first layer 20 by, for example, a diffusion bonding method, a brazing bonding method, an adhesive bonding method, an ultrasonic bonding method, or a laser welding method.

[0041] The second layer 30 may increase the strength of the metal support 10. The second layer 30 has a shape of a flexible and bendable thin plate. The second layer 30 may be provided on the entire second surface 20b of the first layer 20. The shape of the outer periphery of the second layer 30 may be the same as the shape of the outer periphery of the first layer 20. The length of the second layer 30 along the first direction D1 may be the same as the length L1 of the first layer 20 along the first direction D1. The length of the second layer 30 along the second direction D2 may be the same as the length L2 of the first layer 20 along the second direction D2.

[0042] The thickness T2 of the second layer 30 may be 30 μm or more, or may be 35 μm or more. By setting the thickness T2 of the second layer 30 to 30 μm or more, the bending strength of the second layer 30 can be maintained. The thickness T2 of the second layer 30 may be 50 μm or less, or may be 40 μm or less. By setting the thickness T2 of the second layer 30 to 50 μm or less, the flexible display device 70 incorporating the metal support 10 can be prevented from becoming excessively thick. When the second layer 30 is made of a carbon fiber composite material, the thickness T2 of the second layer 30 may be 10 μm or more, or may be 15 μm or more. When the second layer 30 is made of a carbon fiber composite material, the thickness T2 of the second layer 30 may be 50 μm or less, or may be 40 μm or less.

[0043] The main material of the second layer 30 may be a metal material. When the main material of the second layer 30 is a metal material, the metal material may be an iron-based alloy such as stainless steel, copper, a copper alloy, titanium, a titanium-based alloy, magnesium, or a magnesium-based alloy. When stainless steel is used as the main metal material of the second layer 30, the second layer 30 has good spring properties, so that the second layer 30 is easy to bend. The main material of the second layer 30 may be a carbon fiber composite material (CFRP) or a resin material. The resin material may be polyimide (PI). The main material of the second layer 30 may be the same as or different from the main material of the first layer 20.

[0044] The second layer 30 has a plurality of first holes 31. The plurality of first holes 31 are provided in the bending region BA. The plurality of first holes 31 may be formed in a line shape. The plurality of first holes 31 may be arranged parallel to each other. The planar shapes of the plurality of first holes 31 may be the same as each other or may be different from each other. Each of the first holes 31 extends linearly along the second direction D2. Each of the first holes 31 may be rectangular in a planar view. Not limited to this, each of the first holes 31 may have, for example, a polygonal shape or a circular shape in a planar view. Each of the first holes 31 may have a rectangular shape with rounded corners in a planar view. Each of the first holes 31 may be present only in a part of the second layer 30 in the second direction D2.

[0045] Each of the first holes 31 is open to both the first surface 30a and the second surface 30b. That is, each of the first holes 31 is a through hole penetrating the second layer 30 in the thickness direction. Since the first holes 31 are through holes, when the metal support 10 is folded, the radius of curvature of the bending region BA can be made smaller, and bending resistance can be improved. In addition, the weight of the metal support 10 can be reduced. In this specification, the term "hole" is a concept including both a non-through hole and a through hole. However, each of the first holes 31 may be open at least toward the opposite side of the first surface 30a, which is the bonding surface with the first layer 20. That is, each of the first holes 31 may be open at least toward the second surface 30b.

[0046] The length L3 of each first hole 31 along the first direction D1 may be 50 μm or more, or may be 100 μm or more. The length L3 of each first hole 31 along the first direction D1 may be 1000 μm or less, or may be 500 μm or less. The length L4 of each first hole 31 along the second direction D2 may be 200 μm or more, or may be 400 μm or more. The length L4 of each first hole 31 along the second direction D2 may be 2000 μm or less, or may be 1000 μm or less. The lengths L3 and L4 each refer to the distance on the second surface 30b. The depth d1 of the first hole 31, which is a through hole, is equal to the thickness T2 of the second layer 30.

[0047] The second layer 30 has a plurality of first banks 32 in the bending region BA. Each of the first banks 32 extends linearly along the second direction D2. The first banks 32 are arranged at intervals in the first direction D1. A first hole 31 is formed between each of the first banks 32. That is, the first holes 31 and the first banks 32 are alternately formed along the first direction D1. In this case, since the first holes 31 and the first banks 32 are alternately arranged, it is possible to reduce stress concentration at a specific point in the bending region BA when the flexible display device 70 is folded.

[0048] The first banks 32 are arranged parallel to each other. The shapes of the first banks 32 may be the same or different from each other. Each of the first banks 32 may be rectangular in plan view. Not limited to this, each of the first banks 32 may have a shape surrounding the periphery of the first hole 31 in plan view. Each of the first banks 32 may extend over the entire second direction D2 of the second layer 30, or may exist only in a part of the second direction D2 of the second layer 30. Each of the first banks 32 is not thinned from either the first surface 30a side or the second surface 30b side. The thickness of each of the first banks 32 is the same as the thickness T2 of the second layer 30.

[0049] The length L5 of each first bank portion 32 along the first direction D1 may be 50 μm or more, or may be 100 μm or more. The length L5 of each first bank portion 32 along the first direction D1 may be 400 μm or less, or may be 200 μm or less. The length L5 refers to the distance on the second surface 30b. The length L6 of each first bank portion 32 along the second direction D2 may be the same as the length L4 of each first hole 31 along the second direction D2.

[0050] The total thickness T0 of the metal support 10 may be 50 μm or more, or may be 75 μm or more. By making the total thickness T0 of the metal support 10 50 μm or more, the rigidity of the metal support 10 can be maintained. The total thickness T0 of the metal support 10 may be 150 μm or less, or may be 125 μm or less. By making the total thickness T0 of the metal support 10 150 μm or less, it is possible to prevent the metal support 10 from becoming excessively heavy.

[0051] FIG. 8 is a plan view showing a modified example of the metal support 10. As shown in FIG. 8, the multiple first holes 31 may be arranged alternately (staggered). Each first hole 31 has a substantially rectangular shape in a plan view. Not limited to this, each first hole 31 may have, for example, a polygonal shape or a circular shape in a plan view. Each first hole 31 may have a rectangular shape with rounded corners in a plan view. The multiple first holes 31 include the first holes 31 in the first row R1 and the first holes 31 in the second row R2. The first holes 31 in the first row R1 are arranged at intervals from each other along the second direction D2. The first holes 31 in the second row R2 are arranged at intervals from each other along the second direction D2. The first holes 31 in the first row R1 and the first holes 31 in the second row R2 are arranged to be shifted from each other in the second direction D2. According to this modification, since the multiple first holes 31 are staggered, it is possible to prevent stress from concentrating at specific locations around the first holes 31 when the flexible display device 70 is folded.

[0052] (Method of manufacturing a metal support for a flexible display device) Next, a method for manufacturing the metal support 10 shown in FIGS. 5 and 6 will be described with reference to FIGS. 9(a)-(f).

[0053] First, as shown in Fig. 9(a), a second layer 30A having a first surface 30a and a second surface 30b is prepared. The second layer 30A is in an unprocessed state before holes are formed.

[0054] Next, as shown in FIG. 9(b), a first protective layer 51 and a second protective layer 52 are provided on the second layer 30A. Specifically, the first protective layer 51 having a first protective layer opening 51a is provided on the first surface 30a of the second layer 30A, and the second protective layer 52 having a second protective layer opening 52a is provided on the second surface 30b of the second layer 30A. The first protective layer 51 and the second protective layer 52 may each be a resist layer. At this time, a photosensitive resist is first applied to the entire first surface 30a and the entire second surface 30b of the second layer 30A, and then dried. Then, the photosensitive resist on the first surface 30a and the second surface 30b of the second layer 30A is exposed through a photomask, and developed. As a result, the first protective layer 51 having the first protective layer opening 51a is formed on the first surface 30a of the second layer 30A. A second protective layer 52 having a second protective layer opening 52a is formed on the second surface 30b of the second layer 30A. The planar shapes of the first protective layer opening 51a and the second protective layer opening 52a correspond to the planar shapes of the first holes 31. The planar shapes of the first protective layer opening 51a and the second protective layer opening 52a may be the same as or different from each other.

[0055] Next, as shown in FIG. 9(c), the second layer 30A is etched with an etchant using the first protective layer 51 and the second protective layer 52 as a corrosion-resistant film. The etchant can be appropriately selected depending on the material of the second layer 30A. For example, when stainless steel is used as the second layer 30A, a mixture of hydrochloric acid and ferric chloride as a main component, or a mixture of nitric acid and ferric chloride may be used as the etchant. The etchant may be sprayed onto the second layer 30A for etching. As a result, a first hole 31 penetrating the second layer 30A is formed in the second layer 30A.

[0056] 9(d), the first protective layer 51 on the first surface 30a of the second layer 30A and the second protective layer 52 on the second surface 30b are peeled off and removed. In this manner, the second layer 30 having a plurality of first holes 31 is obtained. The first holes 31 may be formed by pressing or laser processing.

[0057] 9(e), a first layer 20 having a first surface 20a and a second surface 20b is prepared. The first layer 20 has no holes formed therein.

[0058] Next, as shown in FIG. 9(f), the second layer 30 is bonded to the first layer 20. At this time, the first hole 31 is opened toward at least the second surface 30b located on the opposite side of the bonding surface with the first layer 20. Specifically, the first surface 30a of the second layer 30 is bonded onto the second surface 20b of the first layer 20. In this case, the first layer 20 and the second layer 30 may be bonded to each other by a diffusion bonding method. When the diffusion bonding method is used, the second layer 30 is pressure-bonded to the first layer 20 at a temperature close to the melting point. This allows metal atoms located near the contact surfaces of the first layer 20 and the second layer 30 to diffuse into each other, and the first layer 20 and the second layer 30 can be bonded to each other. When the diffusion bonding method is used, the total thickness T0 of the metal support 10 can be suppressed. The second layer 30 may be bonded to the first layer 20 by, for example, brazing, adhesive, ultrasonic bonding, or laser welding.

[0059] In this manner, the metal support 10 shown in FIGS. 5 and 6 is obtained.

[0060] According to the present embodiment, the metal support 10 includes a first layer 20 and a second layer 30, and the second layer 30 has a first hole 31. This makes it possible to improve the bendability of the bending region BA of the flexible display device 70 when the metal support 10 is incorporated into the flexible display device 70. As a result, the shape of the bending region BA can be made smaller when the flexible display device 70 is folded, and bending resistance can be improved. In other words, the radius of curvature of the bending region BA can be made smaller.

[0061] Furthermore, according to the present embodiment, by joining the second layer 30 to the first layer 20, it is possible to improve the bending resistance of the metal support 10. Furthermore, since the thickness T1 of the first layer 20 and the thickness T2 of the second layer 30 can each be thin individually, the first layer 20 and the second layer 30 can each be easily processed.

[0062] According to this embodiment, the first layer 20 does not have a hole. In this case, it is not necessary to consider the workability of the first layer 20, and various materials can be selected for the first layer 20. For example, by selecting a light material for the first layer 20, the weight of the entire metal support 10 can be reduced. In addition, a material having a high affinity for the buffer layer 76 or an adhesive layer for attaching the metal support 10 to the buffer layer 76 can be selected as the material for the first layer 20. The adhesive layer may be a transparent adhesive layer such as an OCA (Optical Clear Adhesive) layer.

[0063] Furthermore, according to the present embodiment, the first layer 20 does not have holes. In this case, there are no irregularities on the surface of the metal support 10 facing the display member 71 of the flexible display device 70. This makes it possible to prevent the irregularities caused by the holes in the metal support 10 from affecting the display member 71. This makes it possible to improve the flatness of the flexible display device 70.

[0064] Furthermore, according to this embodiment, since the second layer 30 has the first holes 31, the weight of the metal support 10 can be reduced.

[0065] According to this embodiment, the first holes 31 are formed in the second layer 30 in advance, and then the second layer 30 is joined to the first layer 20. This allows the second layer 30 to be processed before it is laminated, so that various materials can be selected as the material for the second layer 30. For example, it is possible to use materials other than the combination of materials that can be selectively etched as the materials for the first layer 20 and the second layer 30. Furthermore, since the second layer 30 can be processed before it is laminated, it is easy to process the second layer 30.

[0066] According to this embodiment, the first holes 31 may be etched in the second layer 30 in advance, and then the second layer 30 may be diffusion bonded to the first layer 20. As a result, even if the interface between the first layer 20 and the second layer 30 is alloyed due to heat during diffusion bonding, the alloyed portion does not affect the etching.

[0067] (Modification) Next, various modified examples of this embodiment will be described with reference to Figs. 9 to 16. Figs. 9 to 16 are diagrams showing modified examples of this embodiment. In Figs. 9 to 16, the same parts as those in the embodiment shown in Figs. 1 to 8 are given the same reference numerals, and detailed description is omitted. In the embodiment shown in Figs. 1 to 8 and each modified example shown in Figs. 10 to 16, unless otherwise specified, the first layers may have substantially the same configuration, the second layers may have substantially the same configuration, and the third layers may have substantially the same configuration. For example, the first layer of each modified example may be made of the same material as the first layer of the embodiment shown in Figs. 1 to 8. The second layer of each modified example may be made of the same material as the second layer of the embodiment shown in Figs. 1 to 8.

[0068] (First Modification) As shown in FIG. 10, the first layer 20 may have a second hole 21, and the second layer 30 may be accommodated in the second hole 21. The planar shape of the second layer 30 is smaller than that of the first layer 20. The length L7 of the second layer 30 along the first direction D1 may be 5 mm or more, or 10 mm or more. The length L7 of the second layer 30 along the first direction D1 may be 30 mm or less, or 25 mm or less. The length of the second layer 30 along the second direction D2 may be the same as the length L2 of the first layer 20 along the second direction D2, or may be shorter than L2. The thickness T2 of the second layer 30 is thinner than the thickness T1 of the first layer 20. The thickness T1 of the first layer 20 may be 50 μm or more, or 75 μm or more. The thickness T1 of the first layer 20 may be 150 μm or less, or 125 μm or less.

[0069] The main material of the first layer 20 may be a metal material, a carbon fiber composite material (CFRP), or a resin material. The main material of the second layer 30 may be a metal material, a carbon fiber composite material (CFRP), or a resin material. The resin material may be polyimide (PI). It is preferable to use a material having a lower density than the main material of the second layer 30 as the main material of the first layer 20. For example, it is preferable to use carbon fiber composite material (CFRP), polyimide (PI), titanium, titanium-based alloy, magnesium, magnesium-based alloy, or the like as the main material of the first layer 20, and to use an iron-based alloy such as stainless steel, copper, copper alloy, or the like as the main material of the second layer 30.

[0070] The second hole 21 is formed in the second surface 20b of the first layer 20. The second hole 21 is a non-through hole that does not penetrate the first layer 20 in the thickness direction. The second hole 21 may be open at least toward the second surface 20b. A part or all of the second hole 21 is present in the curved region BA. A part of the second hole 21 may be present in the non-bending region NA, or may not be present. The planar shape of the outer periphery of the second hole 21 may be the same as the planar shape of the outer periphery of the second layer 30. The second hole 21 may be formed in a rectangular shape in a planar view. The second hole 21 may have, for example, a polygonal shape or a circular shape in a planar view. The second hole 21 may have a rectangular shape with rounded corners in a planar view. Only one second hole 21 may be present in the first layer 20, or multiple second holes 21 may be present.

[0071] The length L8 of the second hole 21 along the first direction D1 may be equal to the length L7 of the second layer 30 along the first direction D1, or may be longer than L7. The length of the second hole 21 along the second direction D2 may be equal to the length L2 of the first layer 20 along the second direction D2, or may be shorter than L2. The depth d2 of the second hole 21 may be equal to the thickness T2 of the second layer 30, or may be deeper than the thickness T2 of the second layer 30. The depth d2 of the second hole 21 may be 30% or more, or 40% or more, of the thickness T1 of the first layer 20. The depth d2 of the second hole 21 may be 90% or less, or 80% or less, of the thickness T1 of the first layer 20. The second hole 21 may be formed by half etching. In this specification, "half etching" refers to etching the material to be etched halfway in the thickness direction. The thickness of the material to be etched after half-etching is, for example, 30% to 90%, preferably 40% to 80%, of the thickness of the material to be etched before half-etching. The second holes 21 may be formed by pressing or laser processing.

[0072] According to this modification, the first layer 20 can be disposed over the entirety or most of the non-bending region NA. As a result, by selecting a material with low density or high rigidity as the material for the first layer 20, the weight or rigidity of the metal support 10 as a whole can be reduced.

[0073] (Second Modification) As shown in FIG. 11, the first layer 20 has a plurality of second holes 21, and each of the second holes 21 may overlap the corresponding first holes 31 in a plan view. All of the second holes 21 may overlap the corresponding first holes 31, or only some of the second holes 21 may overlap the first holes 31. The plurality of second holes 21 are provided in the bending region BA. Each of the second holes 21 is a through hole penetrating the first layer 20 in the thickness direction. The planar shape of each of the second holes 21 may be the same as or different from the planar shape of each of the first holes 31. The second holes 21 may be formed by etching, or may be formed by pressing or laser processing.

[0074] According to this modification, the first layer 20 has a plurality of second holes 21, thereby making it possible to reduce the overall weight of the metal support 10. Furthermore, the first layer 20 has a plurality of second holes 21, thereby making it possible to enhance the flexibility of the bending region BA of the metal support 10. As a result, when the metal support 10 is incorporated into a flexible display device 70, the radius of curvature of the bending region BA can be made smaller when the flexible display device 70 is folded, thereby improving bending resistance.

[0075] (Third Modification) As shown in FIG. 12, the metal support 10 may include a third layer 40 bonded onto the first surface 20a of the first layer 20. In this case, the metal support 10 is made of a three-layer laminate. The third layer 40 is located on the opposite side of the second layer 30 with respect to the first layer 20. The third layer 40 may be bonded to the first layer 20 by a diffusion bonding method, a brazing bonding method, an adhesive bonding method, an ultrasonic bonding method, or a laser welding method. The third layer 40 may be provided on the entire first surface 20a of the first layer 20, or may be provided on a part of the first surface 20a of the first layer 20. The thickness T3 of the third layer 40 may be 30 μm or more, or may be 35 μm or more. The thickness T3 of the third layer 40 may be 50 μm or less, or may be 40 μm or less. The thickness T3 of the third layer 40 may be the same as or different from the thickness T1 of the first layer 20.

[0076] The main material of the third layer 40 may be a metal material. When the main material of the third layer 40 is a metal material, the metal material may be an iron-based alloy such as stainless steel, copper, a copper alloy, titanium, a titanium-based alloy, magnesium, or a magnesium-based alloy. The main material of the third layer 40 may be a carbon fiber composite material (CFRP) or a resin material. The resin material may be polyimide (PI). The main material of the third layer 40 may be the same as or different from the main material of the first layer 20. The other configurations may be the same as those of the second modified example (FIG. 11).

[0077] According to this modification, the third layer 40 is joined onto the first surface 20a of the first layer 20. By evenly sandwiching the first layer 20 between the second layer 30 and the third layer 40 in this manner, it is possible to prevent warping of the metal support 10 before it is incorporated into the flexible display device 70.

[0078] (Fourth Modification) As shown in FIG. 13, the metal support 10 may include a third layer 40 bonded onto the first surface 20a of the first layer 20. The third layer 40 has a plurality of third holes 41. Each of the third holes 41 may or may not overlap with the first hole 31 in a plan view. The plurality of third holes 41 are provided in the bending region BA. Each of the third holes 41 is a through hole penetrating the third layer 40 in the thickness direction. The planar shape of each of the third holes 41 may be the same as or different from the planar shape of each of the first holes 31. The third holes 41 may be formed by etching, or may be formed by pressing or laser processing.

[0079] According to this modification, the third layer 40 is bonded onto the first surface 20a of the first layer 20. In this way, by evenly sandwiching the first layer 20 between the second layer 30 and the third layer 40, it is possible to suppress the occurrence of warping in the metal support 10. In addition, the third layer 40 has a third hole 41. This not only makes it easier to bend the metal support 10 so that the third layer 40 side is on the inside, but also makes it easier to bend the metal support 10 so that the second layer 30 is on the inside. In addition, the presence of the third hole 41 in the bending region BA can improve the adhesion between the third layer 40 and the adhesive layer for attaching the metal support 10 to the buffer layer 76. This makes it possible to suppress the metal support 10 and the buffer layer 76 from peeling off from each other.

[0080] (Fifth Modification) As shown in FIG. 14, the first layer 20 may have a second hole 21, and the second layer 30 may be accommodated in the second hole 21. The first layer 20 may have a fourth hole 22, and the third layer 40 may be accommodated in the fourth hole 22. The third layer 40 has a plurality of third holes 41. The planar shapes of the second layer 30 and the third layer 40 are each smaller than the planar shape of the first layer 20. The planar shape of the third layer 40 may be the same as or different from the planar shape of the second layer 30. The length L9 of the third layer 40 along the first direction D1 may be 5 mm or more, or may be 10 mm or more. The length L9 of the third layer 40 along the first direction D1 may be 30 mm or less, or may be 25 mm or less. The length of the third layer 40 along the second direction D2 may be the same as the length L2 of the first layer 20 along the second direction D2, or may be shorter than L2. The thickness T3 of the third layer 40 is thinner than the thickness T1 of the first layer 20. The thickness T3 of the third layer 40 may be 15% or more and 45% or less of the thickness T1 of the first layer 20. The thickness T2 of the second layer 30 may be 15% or more and 45% or less of the thickness T1 of the first layer 20. The thickness T3 of the third layer 40 may be the same as or different from the thickness T2 of the second layer 30.

[0081] The fourth hole 22 is formed in the first surface 20a of the first layer 20. The fourth hole 22 is a non-through hole that does not penetrate the first layer 20 in the thickness direction. A part or all of the fourth hole 22 exists in the bending region BA. A part of the fourth hole 22 may exist in the non-bending region NA, or may not exist. The planar shape of the outer periphery of the fourth hole 22 may be the same as the planar shape of the outer periphery of the third layer 40. The fourth hole 22 may be formed in a rectangular shape in a planar view. The fourth hole 22 may have, for example, a polygonal shape or a circular shape in a planar view. The fourth hole 22 may have a rectangular shape with rounded corners in a planar view. Only one fourth hole 22 may exist in the first layer 20, or multiple fourth holes 22 may exist. The planar shape of the fourth hole 22 may be the same as or different from the planar shape of the second hole 21. The fourth hole 22 may overlap the second hole 21 in a planar view, or may be shifted from the second hole 21.

[0082] The length L10 of the fourth hole 22 along the first direction D1 may be equal to the length L9 of the third layer 40 along the first direction D1, or may be longer than L9. The length of the fourth hole 22 along the second direction D2 may be equal to the length L2 of the first layer 20 along the second direction D2, or may be shorter than L2. The depth d3 of the fourth hole 22 may be equal to the thickness T3 of the third layer 40, or may be deeper than the thickness T3 of the third layer 40. The depth d3 of the fourth hole 22 may be 15% or more of the thickness T1 of the first layer 20, or may be 20% or more. The depth d3 of the fourth hole 22 may be 45% or less of the thickness T1 of the first layer 20, or may be 40% or less. The depth d3 of the fourth hole 22 may be equal to the depth d2 of the second hole 21, or may be different. The fourth hole 22 may be formed by half etching. The fourth hole 22 may be formed by press working or laser processing. The other configurations may be the same as those in the first modified example (FIG. 10).

[0083] According to this modification, the second layer 30 is accommodated in the second hole 21, and the third layer 40 is accommodated in the fourth hole 22. In this way, by sandwiching the first layer 20 between the second layer 30 and the third layer 40, it is possible to suppress the occurrence of warping in the metal support 10. In addition, the third layer 40 has a third hole 41. This not only makes it easier to fold the metal support 10 so that the third layer 40 side is on the inside, but also makes it easier to fold the metal support 10 so that the second layer 30 is on the inside. In addition, the presence of the third hole 41 in the bending region BA can improve the adhesion between the third layer 40 and the adhesive layer that bonds the metal support 10 to the display member 71. This makes it possible to suppress the metal support 10 and the display member 71 from peeling off from each other. Furthermore, according to this modification, the first layer 20 can be arranged in the entirety or most of the non-bending region NA. As a result, by selecting a material with low density or high rigidity as the material for the first layer 20, the metal support 10 can be made lighter or more rigid as a whole.

[0084] (Sixth Modification) As shown in FIG. 15, the metal support 10 may include a third layer 40 bonded onto the first surface 20a of the first layer 20. The third layer 40 has a plurality of third holes 41. The first layer 20 has a plurality of second holes 21. The first holes 31, the second holes 21, and the third holes 41 may or may not overlap each other in a plan view. The second holes 21 are provided in the bending region BA. The second holes 21 are through holes that penetrate the first layer 20 in the thickness direction. The third holes 41 are provided in the bending region BA. The third holes 41 are through holes that penetrate the third layer 40 in the thickness direction. The planar shapes of the first holes 31, the second holes 21, and the third holes 41 may be the same as or different from each other. Other configurations may be the same as those of the fourth modified example (FIG. 13).

[0085] According to this modification, the third layer 40 is bonded onto the first surface 20a of the first layer 20. In this way, by evenly sandwiching the first layer 20 between the second layer 30 and the third layer 40, it is possible to suppress the occurrence of warping in the metal support 10. In addition, the third layer 40 has a third hole 41. This not only makes it easier to fold the metal support 10 so that the third layer 40 side is on the inside, but also makes it easier to fold the metal support 10 so that the second layer 30 is on the inside. In addition, the presence of the third hole 41 in the bending region BA can improve the adhesion between the third layer 40 and the adhesive layer that bonds the metal support 10 to the display member 71. This can suppress the metal support 10 and the display member 71 from peeling off from each other. In addition, the first layer 20 has a plurality of second holes 21, so that the flexibility of the bending region BA of the metal support 10 can be increased. Furthermore, the weight of the metal support 10 can be further reduced.

[0086] (Seventh Modification) As shown in FIG. 16, the metal support 10 may include a third layer 40 bonded onto the second surface 30b of the second layer 30. The third layer 40 is located on the opposite side of the first layer 20 with respect to the second layer 30. The third layer 40 may be bonded to the second layer 30 by a diffusion bonding method, a brazing bonding method, an adhesive bonding method, an ultrasonic bonding method, or a laser welding method. The third layer 40 may be provided on the entire second surface 30b of the second layer 30, or may be provided on a part of the second surface 30b of the second layer 30. The third layer 40 has a plurality of third holes 41. Each of the third holes 41 may or may not overlap with the first hole 31 in a plan view. The plurality of third holes 41 are provided in the bending region BA. Each of the third holes 41 is a through hole penetrating the third layer 40 in the thickness direction. The other configurations may be the same as those of the fourth modified example (FIG. 13).

[0087] According to this modification, the thickness T2 of the second layer 30 and the thickness T3 of the third layer 40 can each be made thin individually, which makes it easier to process each of the second layer 30 and the third layer 40.

[0088] It is also possible to combine the multiple components disclosed in the above embodiments and modifications as necessary. Alternatively, some components may be deleted from all the components shown in the above embodiments and modifications. [Explanation of symbols]

[0089] 10 Metallic support for flexible display devices 20 1st layer 20a Page 1 20b 2nd side 21 2nd hole 30 2nd layer 30a 1st page 30b 2nd side 31 First Hole 32 First bank 40 3rd layer 70 Flexible display device

Claims

1. In a metal support for a flexible display device, A first layer having a first surface and a second surface, The first layer comprises a second layer bonded to the second surface of the first layer, The second layer has a first hole that opens at least toward the opposite side of the bonding surface with the first layer, A metal support for a flexible display device, wherein the main material of the first layer is not metal.

2. A metal support for a flexible display device, A first layer having a first surface and a second surface, A second layer bonded to the second surface of the first layer, A third layer is bonded to the first surface of the first layer, The second layer has a first hole that opens at least toward the opposite side of the bonding surface with the first layer, A metal support for a flexible display device, wherein the main material of the first and second layers is metal, and the main material of the third layer is not metal.

3. A metal support for a flexible display device, A first layer having a first surface and a second surface, A second layer bonded to the second surface of the first layer, A third layer bonded to the first surface of the first layer, The second layer has a first hole that opens at least toward the opposite side of the bonding surface with the first layer, A metal support for a flexible display device, wherein the main material of the first layer and the third layer is metal, and the main material of the second layer is not metal.

4. A metal support for a flexible display device, A first layer having a first surface and a second surface, A second layer bonded to the second surface of the first layer, A third layer bonded to the first surface of the first layer, The second layer has a first hole that opens at least toward the opposite side of the bonding surface with the first layer, A metal support for a flexible display device, wherein the main materials of the first layer, the second layer, and the third layer are the same as those of the other.

5. The first layer is a metal support for a flexible display device according to any one of claims 1 to 4, wherein the first layer does not have holes.

6. The metal support for a flexible display device according to any one of claims 1 to 4, wherein the first hole is a through hole.

7. The first layer has a second hole, the metal support for a flexible display device according to any one of claims 1 to 4.

8. The metal support for a flexible display device according to claim 7, wherein the second hole opens at least toward the second surface side, and the second layer is housed within the second hole.

9. The metal support for a flexible display device according to claim 7, wherein the second hole overlaps with the first hole in a plan view.

10. The metal support for a flexible display device according to claim 1, further comprising a third layer bonded to the first surface of the first layer.

11. The metal support for a flexible display device according to claim 2, 3, 4, or 10, wherein the third layer has a third hole.

12. The metal support for a flexible display device according to claim 2, 3, 4, or 10, wherein the first layer has a fourth hole, the fourth hole opens at least toward the first surface side, and the third layer is housed within the fourth hole.

13. The metal support for a flexible display device according to claim 1, further comprising a third layer bonded to the second layer.

14. Display component and A flexible display device comprising a metal support for a flexible display device according to any one of claims 1 to 4, which supports the display member.

15. In a method for manufacturing a metal support for a flexible display device, A step of preparing a second layer having a first hole, A step of preparing a first layer having a first surface and a second surface, The process includes the step of joining the second layer to the second surface of the first layer such that the first hole opens at least toward the opposite side of the bonding surface with the first layer, A method for manufacturing a metal support for a flexible display device, wherein the steps of preparing the second layer and preparing the first layer are each steps prior to the joining step.

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