KR101950472B1 - Flexible display apparatus and the method of manufacturing the same - Google Patents

Abstract

The present invention relates to a first film having a first surface and a second surface opposed to each other and having a first groove on the first surface, the first film having a first rigidity; A third film disposed on the second side; A fourth film disposed to face the third film; A light emitting display interposed between the third film and the fourth film, the light emitting display being sealed by the third film and the fourth film; And a second film disposed on the fourth film so as to face the first film and having a second stiffness smaller than the first stiffness.

Description

TECHNICAL FIELD [0001] The present invention relates to a flexible display apparatus and a method of manufacturing the same,

The present invention relates to a flexible display device and a method of manufacturing the same.

The display device means a device for displaying a video signal. Such display devices include all devices that display image signals input from the outside, including televisions, computer monitors, PDAs, and smart devices that have recently increased in demand.

A high-definition flat panel display module such as an organic light emitting display panel, a liquid crystal display panel, a plasma display panel, an electrophoretic display panel, or the like is used for the display device.

In recent years, a flexible display device which can be made lighter and thinner and which can be folded or folded to improve portability has been developed. The flexible display device can be implemented using a flexible substrate such as plastic instead of a glass substrate.

However, since the flexible board is not fixed in shape and is flexible, it is difficult to precisely form various elements and wirings provided in the display apparatus.

In addition, since excessive stress is applied to the display device due to stress above the breaking strength or repetitive bending, the life of the display device is shortened, Damage occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and other problems, and to reduce the stress generated in the bending portion of the flexible display device when the flexible display device is folded or bent.

According to an aspect of the present invention, there is provided a film comprising: a first film having a first surface and a second surface opposed to each other and having a first groove on the first surface, the first film having a first rigidity; A third film disposed on the second side; A fourth film disposed to face the third film; A light emitting display interposed between the third film and the fourth film, the light emitting display being sealed by the third film and the fourth film; And a second film disposed on the fourth film so as to face the first film and having a second stiffness smaller than the first stiffness.

When a force for bending the flexible display device is applied to the flexible display device, a neutral portion where compression and tensile stress are not generated by the force is disposed, and the light emitting display portion may be located at the neutral portion.

The flexible display device may further include a bending portion provided to be foldable, and the first groove may be located in the bending portion.

The first grooves may be plural.

The first groove may have a V-shape.

The depth (h ₁ ) of the first groove may satisfy the following expression.

<Expression>

0 < h ₁ &lt; t ₁

Here, t ₁ represents the thickness of the first film.

The first film may be divided into a first region and a second region by the first groove and at least a part of the third film may be exposed in a region corresponding to the first groove.

And an elastic member disposed to be embedded in the first groove.

The second film may have a third surface adjacent to the fourth film, a fourth surface opposite to the third surface, and a second groove on the fourth surface.

The third film has flexibility, and the fourth film may be composed of a thin film having an inorganic film or an inorganic film and an organic film.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: forming a third film on a supporting substrate; Forming a light emitting display portion on the third film; Forming a fourth film on the light emitting display portion; Forming a second film having a second rigidity on the fourth film; Separating the support substrate from the third film; And a first surface of the third film opposite to the surface on which the light emitting display portion is formed, a second surface adjacent to the third film and a first surface opposed to the second surface and having a first groove, And attaching a first film having a first stiffness greater than the rigidity to the flexible film.

Wherein when a force for bending the flexible display device is applied to the flexible display device, a neutral portion that does not generate compression or tensile stress by the force is disposed, and the step of forming the light- And forming the light emitting display unit.

Wherein the step of attaching the first film includes a step of attaching the first film having the first groove so that the first groove is located in a bending portion provided in the flexible display device so that the flexible display device can be folded, And attaching.

The first grooves may be plural.

The first groove may have a V-shape.

The depth (h ₁ ) of the first groove may satisfy the following expression.

<Expression>

0 < h ₁ &lt; t ₁

Here, t ₁ represents the thickness of the first protective layer.

The first film may be divided into a first region and a second region by the first groove and at least a part of the third film may be exposed in a region corresponding to the first groove.

The method may further include forming an elastic member in the first groove.

The second film may have a third surface adjacent to the fourth film, a fourth surface opposite to the third surface, and a second groove on the fourth surface.

The third film has flexibility, and the fourth film may be composed of a thin film having an inorganic film or an inorganic film and an organic film.

In the flexible display device according to the embodiments of the present invention as described above,

By positioning the groove in the bending portion of the flexible display device, it is possible to reduce the stress caused by folding or bending.

Further, by attaching a separate film to the display panel portion, the durability can be improved.

In addition, by disposing the light emitting display part in a neutral part, it is possible to prevent damage to elements provided in the light emitting display part due to folding or bending.

1 is a cross-sectional view schematically showing a flexible display device according to an embodiment of the present invention.
2 is a cross-sectional view schematically showing one pixel region of a display panel portion of the flexible display device of FIG.
3 and 4 are perspective views schematically showing a folded shape of the flexible display device of FIG.
5 to 8 are sectional views sequentially illustrating a manufacturing method of the flexible display device of FIG.
9 is a cross-sectional view schematically showing a flexible display device according to another embodiment of the present invention.
10 and 11 are perspective views schematically showing a folded shape of the flexible display device of FIG.
12 is a cross-sectional view schematically showing a flexible display device according to still another embodiment of the present invention.
Figs. 13 and 14 are perspective views schematically showing the folded shape of the flexible display device of Fig.
15 is a cross-sectional view schematically showing a flexible display device according to still another embodiment of the present invention.

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

1 is a cross-sectional view schematically showing a flexible display device 1 according to an embodiment of the present invention. Fig. 2 is a cross- Fig.

1, a flexible display device 1 according to an embodiment has a first surface 101 and a second surface 102 opposed to each other and includes a first groove 110 on a first surface 101, A third film 210 disposed on the second surface 102, a fourth film 230 disposed to face the third film 210, and a third film 210 disposed on the second surface 102. The first film 100 has a first rigidity, And a display panel unit 200 including a light emitting display unit 220 interposed between the third film 210 and the fourth film 230 and sealed by the third film 210 and the fourth film 230. [ And a second film 300 disposed on the fourth film 230 so as to face the first film and having a second stiffness smaller than the first stiffness.

The first film 100 and the second film 300 may be made of plastic, and the second film 300 is flexible. At this time, the first film 100 may be made of a material having a higher rigidity than the second film 300. The first film 100 may have a certain degree of flexibility, but is relatively stiff in comparison with the second film 300.

At this time, the durability of the flexible display device 1 can be improved and the display panel unit 200 can be prevented from being damaged by configuring the first film 100 with a material having a relatively high rigidity.

Although the first film 100 and the second film 300 are made of plastic in the present embodiment, the present invention is not limited thereto, and the first film 100 and the second film 300 It can be composed of various materials.

The flexible display device 1 can be bent such that the first film 100 having a relatively high rigidity, that is, a low flexibility, is disposed inside, and the second film 300 has tensile stress And the first film 100 is subjected to compressive stress.

The flexible display device 1 can be bent repeatedly by an external force and the display panel portion 200 may be damaged if stress exceeding the breaking strength is applied to the display panel portion 200. [ In order to reduce the stress generated in the flexible display device 1, the first film 100 has a first groove 110 on the first side 101 thereof.

In order to eliminate or reduce the compressive stress exerted on the first film 100, the first groove 110 is formed in the banding portion of the flexible display device 1 (Figs. 3 and 4, B) Lt; / RTI &gt; area.

The display panel unit 200 is disposed between the first film 100 and the second film 300.

2, the display panel unit 200 includes a flexible third film 210 disposed on the second surface 102 of the first film 100, a light emitting element 210 disposed on the third film 210, And a fourth film 230 disposed on the display unit 220 and the light emitting display unit 220 so as to face the third film 210 and sealing the light emitting display unit 220. The third film 210, The barrier layer 240 and the device / wiring layer 250 may be further disposed between the light emitting display part 220 and the light emitting display part 220. [

The third film 210 may be composed of a plastic such as polyethylene ether phthalate, polyethylene naphthalate, polycarbonate, polyarylate, polyetherimide, polyether sulfone and polyimide. However, the present invention is not limited thereto, and the third film 210 may be composed of various flexible materials.

A barrier film 240 may be disposed on the third film 210. The barrier film 240 prevents external foreign substances such as moisture and oxygen from penetrating the third film 210 to penetrate the thin film transistor TFT and / or the light emitting display unit 220 and the like.

A device / wiring layer 250 may be disposed on the barrier layer 240. The device / wiring layer 250 may include a driving thin film transistor (TFT), a switching thin film transistor (not shown) A capacitor, and wirings (not shown) connected to the thin film transistor or the capacitor.

The driving thin film transistor TFT includes an active layer 251, a gate electrode 253, and source and drain electrodes 255a and 255b.

A light emitting display portion 220 is disposed on the device / wiring layer 250. The light emitting display 220 includes a pixel electrode 221, an organic light emitting layer 222 disposed on the pixel electrode 221, and a counter electrode 223 formed on the organic light emitting layer 222.

In this embodiment, the pixel electrode 221 is an anode and the counter electrode 223 is a cathode. However, the present invention is not limited to this, and the pixel electrode 221 may be a cathode and the counter electrode 223 may be an anode in accordance with the driving method of the flexible display device 1. [ Holes and electrons are injected into the organic light emitting layer 222 from the pixel electrode 221 and the counter electrode 223, respectively. The excitons formed by the injected holes and electrons fall from the excited state to the ground state and emit light.

The pixel electrode 221 is electrically connected to a driving thin film transistor (TFT) formed on the device / wiring layer 250.

The present invention is not limited to this structure, and the light emitting display 220 may include a light emitting diode (LED) A structure in which the pixel electrode 221 of the pixel electrode 221 is formed on the same layer as the active layer 251 of the thin film transistor TFT or the structure in which the pixel electrode 221 is formed on the same layer as the gate electrode 253, A structure formed on the same layer as the source and drain electrodes 255a and 255b, and the like.

Although the gate electrode 253 is disposed on the active layer 251 in the present embodiment, the present invention is not limited thereto, and the gate electrode 253 may be disposed under the active layer 251 It is possible.

The pixel electrode 221 included in the light emitting display unit 220 of the present embodiment may be a reflective electrode and may be a reflective electrode formed of Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, And a transparent or semi-transparent electrode layer formed on the reflective film.

The transparent or semi-transparent electrode layer may be formed of indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium oxide (In ₂ O ₃ ) At least one selected from the group consisting of indium gallium oxide (IGO) and aluminum zinc oxide (AZO).

The counter electrode 223 disposed to face the pixel electrode 221 may be a transparent or translucent electrode and may have a work function including Li, Ca, LiF / Ca, LiF / Al, Al, Ag, Mg, May be formed of a small metal thin film. Further, an auxiliary electrode layer or a bus electrode can be further formed on the metal thin film using a transparent electrode forming material such as ITO, IZO, ZnO, or In ₂ O ₃ .

Therefore, the counter electrode 223 can transmit the light emitted from the organic light emitting layer 222. [

The organic light emitting layer 222 may be disposed between the pixel electrode 221 and the counter electrode 223 and the organic light emitting layer 222 may be a low molecular organic material or a polymer organic material.

A hole transport layer (HTL), a hole injection layer (HIL), and an electron transport layer (ETL) are formed between the pixel electrode 221 and the counter electrode 223 in addition to the organic emission layer 222. [ And an electron injection layer (EIL) may be selectively disposed.

The light emitted from the organic light emitting layer 222 may be a front light emitting type that is directly or reflected by the pixel electrode 221 constituted of a reflective electrode and is emitted toward the opposite electrode 223 side.

However, the flexible display device 1 of the present invention is not limited to the front emission type, and may be a back emission type in which light emitted from the organic emission layer 222 is emitted toward the third film 210 side. In this case, the pixel electrode 221 may be a transparent or semitransparent electrode, and the counter electrode 223 may be a reflective electrode.

Also, the flexible display device 1 may be a double-sided light-emitting type that emits light in both front and back directions.

A fourth film 230 may be disposed on the counter electrode 223. The fourth film 230 may be composed of an inorganic film formed in multiple layers, or a thin film including an inorganic film and an organic film. The fourth film 230 functions to prevent external moisture, oxygen, and the like from penetrating the light emitting display unit 220.

The flexible display device 1 of the present embodiment includes a display panel portion 200 including a flexible third film 210 and a fourth film 230 composed of a thin film, By including the first film 100 and the second flexible film 300, flexibility and thinness can be easily realized.

When an external force for bending the flexible display device 1 is applied to the flexible display device 1 of the present embodiment, tensile stress is applied to the second film 300 disposed outside the bending portion B, Compressive stress is applied to the first film 100 disposed inside the bending portion B.

At this time, there is a neutral part between the first film 100 and the second film 300 where no tensile stress or compressive stress is generated. When the light emitting display part 220 is disposed in the neutral part, the stress applied to the light emitting display part 220 can be minimized to prevent damage due to bending.

A first groove 110 is formed on the first surface 101 of the first film 100 to remove or reduce the compressive stress applied to the first film 100. The first groove 110 may be located in the region where the bending portion B, that is, the stress is maximized, when the flexible display device 1 is bent.

In this embodiment, the first groove 110 may have a V-shape. The width L ₁ and the depth h ₁ of the V-shaped first groove 110 may have various values depending on the required degree of bending.

At this time, the depth h ₁ of the first groove 110 may satisfy 0 <h ₁ ≤ t ₁ . Here, t ₁ represents the thickness of the first film 100.

In the present embodiment, the first groove 110 is illustrated as one case, but the present invention is not limited thereto, and the first groove 110 may be plural.

The second film 300 has a third surface 301 adjacent to the display panel unit 200 and a fourth surface 302 opposite to the third surface 301. The second film 300 has a third surface 301 adjacent to the display panel unit 200, 2 groove (not shown).

The first groove 110 and the second groove (not shown) may or may not be arranged to correspond to each other. The description of the first groove 110 can be similarly applied to the second groove (not shown), so that the description of the second groove (not shown) will be omitted.

In this embodiment, the first film 100 having a relatively high rigidity is disposed in a lower portion of the display panel unit 200, that is, in the direction of the third film 210, and the second flexible film 300, The first film 100 and the second film 300 may be disposed opposite to each other in the upper portion of the panel unit 200, that is, in the direction of the fourth film 230.

At this time, the first film 100 and / or the second film 300 disposed in a direction in which light is emitted may include a polarizing film.

The light emitting display unit 220 of the display panel unit 200 included in the flexible display device 1 of the present embodiment includes the organic light emitting layer 222. The present invention is not limited to this, 200 may include a liquid crystal display element, a plasma display element, or an electrophoretic display element.

Figs. 3 and 4 are perspective views schematically showing the folded shape of the flexible display device 1 of Fig.

3, the first film 100 includes a first region 120 and a second region 130, and the flexible display device 1 includes a first region 120 of the first film 100 And the second region 130 are substantially perpendicular to each other.

The width L ₁ of the first groove 110 is substantially equal to the width L ₁ of the first film 100. In this case, twice the thickness (t _1), that is, L ₁ = 2t can be _{1, the} depth (h ₁₎ is the same as the thickness (t ₁₎ of the first film 100, that may be h ₁ = t ₁ .

With the above configuration, the first film 100 may not be subjected to compressive stress even if the flexible display device 1 is folded as shown in Fig.

4, the first film 100 includes a first region 120 and a second region 130, and the flexible display device 1 includes a first region 120 of the first film 100 And the second region 130 are substantially horizontally folded.

In this case, the width L1 of the first groove 110 formed in the first film 100 may be larger than twice the thickness t1 of the first film 100, 1 &lt; / RTI &gt;

At this time, although the first film 100 can receive a certain amount of compressive stress depending on the value of the width L1, the magnitude of the compressive stress remarkably decreases as compared with the case where the first groove 110 is absent.

5 to 8 are sectional views sequentially showing the manufacturing method of the flexible display device 1 of Fig.

5, a display panel unit (not shown) including a flexible third film 210, a light emitting display unit 220, and a fourth film 230 sealing the light emitting display unit 220 is formed on a support substrate 400 200 are formed.

The supporting substrate 400 may be made of glass. It is difficult to precisely form the thin film transistor (TFT), the light emitting display portion 220, and the like on the third film 210 because the flexible third film 210 made of plastic or the like can be deformed by heat.

Therefore, after the third film 210 is attached on the supporting substrate 400, it is preferable to carry out a subsequent process.

The light emitting display portion 220 is formed by sequentially forming pixel electrodes (Figs. 2 and 221), organic light emitting layers (Figs. 2 and 222) and counter electrodes (Figs. 2 and 223) sequentially on the flexible third film 210 The fourth film 230 is formed so as to cover the light emitting display portion 220.

The fourth film 230 may be composed of a multilayered inorganic film or a thin film composed of an inorganic film and an organic film.

Referring to FIG. 6, a second film 300 having a second rigidity is attached on the fourth film 230.

The second film 300 may be formed of a flexible film such as plastic and a fourth film 230 and a second film 300 may be interposed between the fourth film 230 and the second film 300 An adhesive layer (not shown) for adhering can be disposed.

Referring to FIG. 7, the supporting substrate 400 is separated from the third film 210.

The supporting substrate 400 may be separated from the third film 210 by a conventional method such as etching.

8, a second surface 102 adjacent to the third film 210 and a second surface 102 adjacent to the second surface 102 are formed on the surface opposite to the surface on which the light emitting display portion 220 of the third film 210 is disposed. (100) having a first stiffness greater than the second stiffness and having a first surface (101) facing the first surface (110) and having a first groove (110).

At this time, an adhesive layer (not shown) for attaching the first film 100 and the third film 210 may be disposed between the first film 100 and the third film 210.

9 is a cross-sectional view schematically showing a flexible display device 2 according to another embodiment of the present invention.

Referring to Fig. 9, the flexible display device 2 according to the present embodiment has the same configuration as the flexible display device 1 of Fig. 1 except for the difference in the configuration of the first film 100 ' .

The first film 100 'has a first groove 110' and is divided into a first region 120 'and a second region 130' by the first groove 110 ' And a part of the third film 210 is exposed in a region corresponding to the groove 110 '.

At this time, the width L ₂ and the depth h ₂ of the first groove 110 'provided in the first film 100' may have various values depending on the required degree of bending.

Figs. 10 and 11 are perspective views schematically showing the folded shape of the flexible display device 2 of Fig.

Referring to FIG. 10, the first film 100 'is divided into a first region 120' and a second region 130 ', and the flexible display device 2 is divided into a first region 100' And a bending portion B 'folded such that the first region 120' and the second region 130 'are substantially perpendicular to each other.

At this time, the first groove 110 'of the first film 100' is positioned in the bending portion B ', and a void space surrounded by the first region 120' and the second region 130 'exists .

The width L ₂ of the first groove 110 'provided in the first film 100' may be approximately twice the thickness t ₂ of the first film 100 ', that is, L ₂ = 2t ₂ , And the depth h ₂ may be the same as the thickness t ₂ of the first film 100 ', that is, h ₂ = t ₂ .

With the above configuration, the first film 100 'may not be subjected to compressive stress even if the flexible display device 2 is folded as shown in Fig.

Referring to FIG. 11, the first film 100 'is divided into a first region 120' and a second region 130 ', and the flexible display device 2 is divided into a first region 100' And a bending portion B 'folded such that the first region 120' and the second region 130 'are substantially horizontal.

At this time, the first groove 110 'of the first film 100' is positioned in the bending portion B ', and a void space surrounded by the first region 120' and the second region 130 'exists .

The first film 100 'may undergo some compressive stress depending on the width L ₂ and depth h ₂ of the first groove 110', but the first groove 110 ' The magnitude of the compressive stress is remarkably reduced as compared with the case where there is no stress.

12 is a cross-sectional view schematically showing a flexible display device 3 according to still another embodiment of the present invention.

12, the flexible display device 3 of this embodiment is the same as the flexible display device 2 of FIG. 12 except that the first groove 110 'provided in the first film 100' The elastic member 500 is disposed so as to be embedded in the elastic member 500.

The elastic member 500 is made of a material having a greater flexibility than the first film 100 ', and when the flexible display device 3 is folded, the bending portion (Figs. 13 and 14, B' The compressive stress can be reduced by forming the first groove 110 'in the region where the stress becomes maximum and disposing the elastic member 500 in the first groove 110'.

In addition, since the elastic member 500 is embedded in the first groove 110 ', the display panel unit 200 is not exposed to the outside.

Figs. 13 and 14 are perspective views schematically showing the folded shape of the flexible display device 3 of Fig.

Referring to FIG. 13, the first film 100 'is divided into a first region 120' and a second region 130 ', and the flexible display device 2 is divided into a first region 100' And a bending portion B 'folded such that the first region 120' and the second region 130 'are substantially perpendicular to each other.

At this time, the first groove 110 'of the first film 100' is positioned in the bending portion B ', and in the region surrounded by the first region 120' and the second region 130 ' (500).

Referring to FIG. 14, the first film 100 'is divided into a first region 120' and a second region 130 ', and the flexible display device 2 is divided into a first region 100' And a bending portion B 'folded such that the first region 120' and the second region 130 'are substantially horizontal.

At this time, the first groove 110 'of the first film 100' is positioned in the bending portion B ', and in the region surrounded by the first region 120' and the second region 130 ' (500).

Accordingly, the flexible display device 3 of the present embodiment is configured such that the flexible member 500 having a large flexibility is disposed in the first groove 110 'provided in the first film 100' Is folded as shown in Figs. 13 and 14, the stress applied to the first film 100 'can be reduced.

15 is a cross-sectional view schematically showing a flexible display device 4 according to still another embodiment of the present invention.

15, the flexible display device 4 according to the present embodiment is the same as the flexible display device 1 shown in Fig. 1 except that the first film 100 "has two first grooves &lt; RTI ID = Quot; 110 ") are disposed.

The first groove 110 "has a constant width L ₃ and a height h ₃ at which the height h ₃ may be less than the thickness t ₃ of the first film 100" , But the present invention is not limited thereto.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, It will be understood that various modifications and equivalent embodiments may be possible. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

1, 2, 3, 4: Flexible display device 100, 100 ', 100 "
101: first side 102: second side
110, 110 ', 110'': first grooves 120, 120': first regions
130, 130 ': second region 200: display panel section
210: Third film 220: Light emitting display
221: pixel electrode 222: organic light emitting layer
223: counter electrode 230: fourth film
240: barrier film 250: element / wiring layer
300: second film 301: third side
302: fourth surface 400: supporting substrate
500: elastic member

Claims (14)

A first film having a first groove and having a first region and a second region separated by the first groove;
A third film disposed on the first film;
An adhesive layer disposed between the first film and the third film; And
A light emitting display disposed on the third film; Lt; / RTI &gt;
Wherein the width of the first groove is at least twice the thickness of the first film,
And one surface of the third film at a position corresponding to the first groove is exposed. The method according to claim 1,
And the third film comprises a plastic material. 3. The method of claim 2,
And the third film comprises polyimide. The method according to claim 1,
And a fourth film disposed on the light emitting display portion. 5. The method of claim 4,
Wherein the fourth film is a thin film including an inorganic film and an organic film. 5. The method of claim 4,
The light emitting display portion is sealed between the third film and the fourth film,
Wherein the light emitting display portion includes a pixel electrode positioned on the third film, an organic light emitting layer positioned on the pixel electrode, and an opposing electrode located on the organic light emitting layer. 5. The method of claim 4,
And a second film disposed on the fourth film. 8. The method of claim 7,
Wherein the first film has a first stiffness and the second film has a second stiffness that is smaller than the first stiffness. The method according to claim 1,
And an elastic member embedded in the first groove. The method according to claim 1,
And the first groove is a plurality of flexible display devices. The method according to claim 1,
Wherein the first groove has a V-shape. The method according to claim 1,
Wherein the flexible display device includes a foldable foldable portion, and the first groove is located in the folded portion. The method according to claim 1,
Wherein the flexible display device includes a neutral portion that does not generate compression and tensile stress due to the force when a force for bending the flexible display device is applied to the flexible display device, Wherein the flexible display device is a flexible display device. A first film having a first groove and having a first region and a second region separated by the first groove, the first film comprising a plastic material;
A third film disposed on the first film;
An adhesive layer disposed between the first film and the third film;
A light emitting display disposed on the third film;
A fourth film disposed on the light emitting display portion; And
And a second film disposed on the fourth film,
Wherein the second film is thicker than at least one of the third film and the fourth film.

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