KR102603295B1 - Display device - Google Patents

Abstract

A display device according to an embodiment includes a display panel, a stress relief layer located on the display panel and including a liquid or a flexible sheet, an adhesive layer surrounding the stress relief layer and located on an edge of the display panel, and the stress relief layer. It includes a relief layer and a cover window located on the adhesive layer.

Description

Display device {DISPLAY DEVICE}

This disclosure relates to a display device.

The display device includes a display panel that displays an image, and a transparent cover window that covers the display surface of the display panel. In general, the cover window functions to protect the display panel from external impacts and scratches applied during use.

Meanwhile, flexible display devices that are easily deformable have been developed recently. Flexible display devices can be classified into bendable display devices, foldable display devices, rollable display devices, stretchable display devices, etc. depending on their purpose or form.

When such a flexible display device includes a cover window to protect the display panel, a structure that is resistant to external shock and can secure flexibility is required.

The problem to be solved by the present invention is to provide a display device that has excellent impact resistance and excellent flexibility by including a stress relief layer.

A display device according to an embodiment includes a display panel, a stress relief layer located on the display panel and including a liquid or a flexible sheet, an adhesive layer surrounding the stress relief layer and located on an edge of the display panel, and It may include a stress relief layer and a cover window located on the adhesive layer.

The liquid may include at least one of distilled water and liquid crystal.

The flexible sheet is made of phenylene, polyethyleneterephthalate (PET), polyimide (PI), polyethylene naphthalate (PEN), polycarbonate (PC), and thin glass (thin film). glass).

The thickness of the adhesive layer may be in the range of 10㎛ to 50㎛.

The thickness of the stress relief layer may be in the range of 10㎛ to 50㎛.

The thickness of the stress relief layer and the adhesive layer may be the same.

The cover window may be made of thin glass having a Young's modulus of 40 GPa to 60 GPa.

The stress relief layer may be in direct contact with the cover window and the display panel.

The display panel, the stress relief layer, the adhesive layer, and the cover window may be wound around a roller located below the display panel.

The display device may further include a polarizer at at least one of the interior of the display panel, between the display panel and the stress relief layer, and between the stress relief layer and the cover window.

The polarizer may be a sheet-type or coated-type polarizer.

Meanwhile, among the plurality of surfaces of the display panel, the display panel may further include a protective film positioned on a surface opposite to the surface on which the stress relief layer is positioned.

The protective film may be composed of at least one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene sulfide (PES), and polyethylene (PE).

According to embodiments, by including a stress relief layer, a display device having a structure that is resistant to external shock and has excellent flexibility can be implemented.

1 is a cross-sectional view of a display device according to an embodiment of the present disclosure.
FIG. 2 schematically shows a state in which a portion of the display device according to FIG. 1 is wound around a roller.
3 is a cross-sectional view of a display device according to another embodiment of the present disclosure.
Figure 4 shows the structure of a display device manufactured according to Comparative Example 1.
Figure 5 shows the stress distribution measurement results of the display device manufactured according to Example 1 and Comparative Example 1.
Figure 6 shows the results of a pen-drop test of the display device manufactured according to Example 1 and Comparative Example 1.
Figure 7 shows the results of a ball-drop test of the display device manufactured according to Example 1 and Comparative Example 1.

Hereinafter, with reference to the attached drawings, various embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. The invention may be implemented in many different forms and is not limited to the embodiments described herein.

In order to clearly explain the present invention, parts that are not relevant to the description are omitted, and identical or similar components are assigned the same reference numerals throughout the specification.

In addition, the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of explanation, so the present invention is not necessarily limited to what is shown. In the drawing, the thickness is enlarged to clearly express various layers and regions. And in the drawings, for convenience of explanation, the thicknesses of some layers and regions are exaggerated.

Additionally, when a part of a layer, membrane, region, plate, etc. is said to be “on” or “on” another part, this includes not only cases where it is “directly above” another part, but also cases where there is another part in between. . Conversely, when a part is said to be “right on top” of another part, it means that there is no other part in between. In addition, being “on” or “on” a reference part means being located above or below the reference part, and does not necessarily mean being located “above” or “on” the direction opposite to gravity. .

In addition, throughout the specification, when a part "includes" a certain element, this means that it may further include other elements rather than excluding other elements, unless specifically disclosed to the contrary.

In addition, throughout the specification, when referring to “on a plane,” this means when the target portion is viewed from above, and when referring to “in cross section,” this means when a cross section of the target portion is cut vertically and viewed from the side.

1 is a cross-sectional view of a display device according to an embodiment of the present disclosure.

Referring to FIG. 1 , a display device 1000 according to an embodiment of the present disclosure includes a display panel 100, a stress relief layer 200, an adhesive layer 300, and a cover window 400.

The display panel 100 includes a plurality of pixels and displays an image. Examples of the display panel 100 according to the present embodiment may include various types such as a liquid crystal display panel, a plasma display panel, and a light emitting display panel, but the present embodiment is not limited thereto, and various types of the display panel 100 may be used in this embodiment. It can be applied to examples.

The display panel 100 may include, for example, a substrate 11, a display element layer 12 located on the substrate 11, and a thin film encapsulation layer 14 located on the display element layer 12. You can.

The substrate 11 is a transparent substrate, and may be made of a flexible film containing, for example, polyimide (PI), polyamide (PA), polyethylene terephthalate (PET), etc. there is.

The display device layer 12 is formed on the substrate 11, and has a device area where an active device such as a thin film transistor (TFT) is formed and a light emitting layer containing an organic material and/or an inorganic material. Includes area. The device area and the light emitting area may be located separately or may be located overlapping.

A thin film encapsulation layer 14 may be positioned on the display device layer 12 to cover and protect the substrate 11 and the display device layer 12. The thin film encapsulation layer 14 can protect the display device layer 12 by preventing oxygen and moisture from entering from the outside.

A stress relief layer 200 and an adhesive layer 300 are located on the display panel 100.

The stress relief layer 200 is located on one side of the display panel 100, and the adhesive layer 300 surrounds the stress relief layer 200 and is located on the edge of the display panel 100.

At this time, the stress relief layer 200 includes liquid or a flexible sheet.

The liquid may, for example, consist of at least one of distilled water and liquid crystal. When the stress relief layer 200 is composed of at least one of distilled water and liquid crystal, both impact resistance and flexibility of the display device 1000 can be secured. In particular, when the stress relief layer 200 is made of liquid crystal, there is an advantage that the transmittance of light emitted from the display panel 100 can also be adjusted.

Flexible sheets include, for example, phenylene, polyethyleneterephthalate (PET), polyimide (PI), polyethylene naphthalate (PEN), polycarbonate (PC), It may be composed of at least one of thin glass. When the stress relief layer 200 is constructed using such a flexible sheet, when stress is applied between the display panel 100 and the cover window 400, it is absorbed, thereby increasing the flexibility of the display device 1000 through stress distribution. It can be improved.

If necessary, the stress distribution effect can be further improved by coating the surface of the flexible sheet with oil or the like to reduce friction.

The thickness of the stress relief layer 200 may range from approximately 10 μm to 50 μm. When the thickness of the stress relief layer 200 is 10 μm or more, the stress applied between the display panel 100 and the cover window 400 can be easily distributed, thereby further improving the flexibility of the display device 1000. In addition, when the thickness of the stress relief layer 200 is 50㎛ or less, excessive shear strain is applied to the adhesive layer 300 to prevent the display panel 100 and the cover window 400 from separating. there is.

Meanwhile, the adhesive layer 300 serves to attach the display panel 100 and the cover window 400, which will be described later.

The thickness of the adhesive layer 300 may range from approximately 10 μm to 50 μm. When the thickness of the adhesive layer 300 satisfies the above range, when implementing a rollable display device using the display device 1000 according to the present disclosure, the display panel 100 and the cover are maintained even if the winding and unwinding process is repeated. The window 400 can be prevented from being separated.

Additionally, the adhesive layer 350 may be formed of, for example, pressure-sensitive adhesive (PSA).

At this time, the stress relief layer 200 and the adhesive layer 300 may be formed to have the same thickness, but are not limited thereto.

A cover window 400 is located on the stress relief layer 200 and the adhesive layer 300.

The cover window 400 serves to protect the display panel 100 from external shock. The cover window 400 may be made of thin glass having a Young's modulus of 40 GPa to 60 GPa. When the Young's modulus value satisfies the above range, the display panel 100 located below the cover window 400 can be very effectively protected from external shock.

In the present disclosure, the stress relief layer 200 is not attached to the display panel 100 and the cover window 400. Accordingly, the stress relieving layer 200 is positioned in the inner area surrounded by the adhesive layer 300, that is, in the area where the display panel 100 and the cover window 400 overlap, in direct contact with them. As the stress relief layer 200 is positioned in direct contact with the display panel 100 and the cover window 400, the display panel 100 and the cover window 400 interact with each other during the process of winding and unwinding the display device according to the present disclosure. The stress that can be applied to can be minimized.

In general, in the case of a display device including a cover window, an adhesive layer is formed on the entire surface of the display panel, and the display panel and the cover window are attached through the adhesive layer. If a rollable display device is implemented using a display device with this structure, the adhesive area is large, so the stress applied to the display panel and cover window increases during the process of winding and unwinding the display device, causing cracks to occur in the cover window. There was a problem with the display panel and cover window being separated.

In order to improve this, a method of forming a cover window using a more flexible material was also proposed, but in this case, the impact resistance of the display device was reduced and there was a problem in that the display device was easily damaged by external shock.

However, as in the present disclosure, a separate adhesive is not used in the inner space of the adhesive layer 300 located on the edge of the display panel 100, that is, the area where the display panel 100 and the cover window 400 overlap. A display device having a structure in which the stress relief layer 200 containing liquid or a flexible sheet is placed in direct contact with the display panel 100 and the cover window 400 ensures both excellent impact resistance and flexibility as described above. Because this is possible, a rollable display device can be easily implemented.

As described above, when using the display device of the present disclosure, a rollable display device with excellent durability even when repeatedly rolled and unfolded can be implemented.

FIG. 2 schematically shows a state in which a part of the display device according to FIG. 1 is wound around a roller. Referring to FIG. 2, the display panel 100, the stress relief layer 200, the adhesive layer (not shown), and the cover window 400 may be wound around the roller 450 located below the display panel 100. .

The roller 450 may have a cylindrical shape extending long in a second direction (Y-axis direction) that intersects the first direction (X-axis direction), and the curvature of the roller 450 can be changed as needed.

The roller 450 can rotate counterclockwise or clockwise. When the roller 450 rotates counterclockwise, the display device may be wound around the roller 450 in a first direction (X-axis direction). When the roller 450 rotates clockwise, the display device may be unfolded from the roller 450 in the first direction (X-axis direction).

Meanwhile, the display device according to the present disclosure may further include an anti-reflection film (not shown) to secure a viewing angle and improve visibility.

The anti-reflection film may be located at least one of the inside of the display panel 100, between the display panel 100 and the stress relief layer 200, and between the stress relief layer 200 and the cover window 400.

At this time, when the anti-reflection film is located inside the display panel 100, for example, between the display element layer and the thin film encapsulation layer, it may be of a coating type.

Additionally, when the anti-reflection film is located either between the display panel 100 and the stress relief layer 200 or between the stress relief layer 200 and the cover window 400, it may be in the form of a sheet.

3 is a cross-sectional view of a display device according to another embodiment of the present disclosure.

Referring to FIG. 3 , the display device 1000 according to this embodiment may further include a protective film 500 located on one side of the display panel 100.

More specifically, the protective film 500 is intended to protect the lower surface of the display panel 100 and may be located on the opposite side of the display panel 100 from where the stress relief layer 200 is located. The protective film 500 is attached to the display panel 100 via the adhesive layer 350. The adhesive layer 350 may be formed of, for example, pressure-sensitive adhesive (PSA).

The protective film 500 may include at least one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene sulfide (PES), and polyethylene (PE). .

The other embodiment shown in FIG. 3 is substantially the same as the one embodiment shown in FIG. 1 except that a protective film is attached through an adhesive layer, so repeated descriptions will be omitted.

The present disclosure will be examined in detail through examples below.

Example One

A 25㎛ thick phenylene sheet was placed on one side of the light emitting display panel, and a 25㎛ thick adhesive layer was formed on the edge of the light emitting display panel to surround the phenylene sheet. Next, a cover window made of thin glass with a thickness of 50 μm is placed on the phenylene sheet and the adhesive layer, and the cover window is attached to the light-emitting display panel using the adhesive layer to form a display device having the structure shown in FIG. 1. was manufactured.

Comparative example One

A display device having the structure shown in FIG. 4 is manufactured by forming an adhesive layer 30 with a thickness of 25 μm on one side of the light emitting display panel 10 and then attaching a cover window made of thin glass 40 with a thickness of 50 μm. did.

Experiment example 1 - Rolling test

A rolling test was conducted by wrapping and unwinding the display devices according to Example 1 and Comparative Example 1 on a device equipped with a roller with a curvature of 10 mm once.

The results are shown in Table 1 below.

division Whether there are cracks in the cover window Example 1 No cracks even after rolling 200,000 times Comparative Example 1 Cracks occur after rolling 1000 times

Referring to Table 1, cracks did not occur in the cover window of the display device according to Example 1 even after rolling 200,000 times, but cracks occurred in the display device according to Comparative Example 1 after rolling 1000 times. Accordingly, it can be seen that the rolling characteristics of the display device having the same structure as an embodiment of the present disclosure are very excellent.

Experiment example 2 - Strain distribution measurement

The display devices according to Example 1 and Comparative Example 1 were wound twice around a roller with a curvature of 15 mm, and then the strain values received by the display panel were measured at predetermined intervals along the length of the display device.

The results are shown in Figure 5.

Referring to FIG. 5, the display device according to Example 1 has no significant difference in strain value no matter where the display device is measured from any position on the panel, so even when the display device is wound around a roller, the stress applied to the display panel is distributed, thereby providing flexibility. I was able to confirm that this was excellent.

On the other hand, the display device according to Comparative Example 1 has a strain value in the center area of the panel that is significantly higher than that in the edge area, so when the display device is wound around a roller, stress is concentrated on the display panel rolled up inside, so the flexibility is very poor compared to Example 1. could be confirmed.

Experiment example 3 - Ball - drop (ball-drop) test

An impact force measurement sensor was placed at the bottom of the display device according to Example 1 and Comparative Example 1, and then a ball weighing 5.5 g was dropped. The results of measuring the maximum impact force at different heights are shown in Figure 6.

Experiment example 4 - Pen- drop (pen-drop) test

After placing the impact force measurement sensor on the lower part of the display device according to Example 1 and Comparative Example 1, a pen weighing 5.8 g was dropped. The results of measuring the maximum impact force at different heights are shown in Figure 7.

6 and 7, the display device according to Example 1 including a stress relief layer made of a phenylene sheet is compared with the display device according to Comparative Example 1 in which the display panel and the cover window are attached using an adhesive layer. It can be seen that the maximum impact force measured has a low value.

This is believed to be because the stress relief layer absorbs shock. That is, it can be confirmed that the display device according to an embodiment of the present disclosure including a stress relief layer has excellent impact resistance.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims are also possible. It falls within the scope of rights.

100: display panel
200: Stress relief layer
300: Adhesive layer
400: cover window
500: protective film

Claims (13)

display panel;
a stress relief layer located on the display panel and including a liquid or flexible sheet;
an adhesive layer surrounding the stress relief layer and located on an edge of the display panel; and
a cover window located on the stress relief layer and the adhesive layer;
Including,
The liquid includes at least one of distilled water and liquid crystal,
The flexible sheet is made of phenylene, polyethyleneterephthalate (PET), polyimide (PI), polyethylene naphthalate (PEN), polycarbonate (PC), and thin glass (thin film). A display device including at least one of glass. delete delete According to paragraph 1,
A display device wherein the thickness of the adhesive layer is in the range of 10㎛ to 50㎛. According to paragraph 1,
A display device wherein the stress relief layer has a thickness in the range of 10㎛ to 50㎛. According to paragraph 1,
The display device wherein the stress relief layer and the adhesive layer have the same thickness. According to paragraph 1,
The cover window is a display device made of thin glass having a Young's modulus of 40 GPa to 60 GPa. According to paragraph 1,
The display device wherein the stress relief layer is in direct contact with the cover window and the display panel. According to paragraph 1,
The display panel, the stress relief layer, the adhesive layer, and the cover window are wound around a roller located below the display panel. According to paragraph 1,
The display device further includes an anti-reflection film located at least one of an interior of the display panel, between the display panel and the stress relief layer, and between the stress relief layer and the cover window. According to clause 10,
The display device wherein the anti-reflection film is a sheet-type or coating-type anti-reflection film. According to paragraph 1,
The display device further includes a protective film positioned on a surface of the display panel opposite to the surface on which the stress relief layer is located. According to clause 12,
A display device wherein the protective film is composed of at least one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene sulfide (PES), and polyethylene (PE).

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