KR102164592B1 - Foldable display device - Google Patents

Abstract

An exemplary embodiment of the present invention includes a flexible display panel, and a cover window disposed outside the flexible display panel, wherein the cover window is formed to have a first hardness and at least partially overlaps a first flat area and a second A horizontal portion connecting the first vertical portion and the second vertical portion, and the first vertical portion and the second vertical portion between the planar regions, and the end of the first vertical portion is connected to the end of the second planar region And an end end of the second vertical portion is connected to an end end of the first flat region, and includes a folded region formed with a second hardness lower than the first hardness. The foldable display device according to an exemplary embodiment of the present invention has an effect that the cover window can have a high surface hardness in a flat area, while the cover window has good foldability in the folded area and the folded area is not visually recognized.

Description

Foldable display device {FOLDABLE DISPLAY DEVICE}

The present invention relates to a foldable display device capable of being unfolded and folded.

The foldable display device uses a flexible display panel that can bend. The foldable display device is easy to carry when folded and can realize a large screen when unfolded, so it can be applied not only to mobile devices such as mobile phones, ultra mobile PCs, e-books, and electronic newspapers, but also to televisions and monitors. I can.

The foldable display device includes a cover window at the top of the stack, and the cover window protects the flexible display panel. Due to the characteristics of the foldable display device, the cover window must be able to be folded to a set level and must have a surface hardness level that can protect the lower flexible display panel.

An object of the present invention is to provide a foldable display device in which a cover window has good foldability and a surface hardness that safely protects a flexible display panel.

In order to solve this problem, according to an embodiment of the present invention, a flexible display panel and a cover window disposed outside the flexible display panel are included, and the cover window is formed to have a first hardness and at least a portion overlaps. And a horizontal portion connecting the first vertical portion and the second vertical portion, and the first vertical portion and the second vertical portion between the first and second planar regions, and an end of the first vertical portion is the A foldable display device including a folded area connected to an end of a second flat area, an end of the second vertical part connected to an end of the first flat area, and formed with a second hardness lower than the first hardness Provides.

The planar region is polyethylene naphthalate (PEN), polymethyl methacrylate (PMMA), polyurethane (PU), polyethylene terephthalate (PET), polyimide (PI). , Polycarbonate (PC, polycarbonate) may include any one or more materials.

The folded region may be formed of acrylic resin or silicone.

The folded area may be formed in the form of a film bonding the first planar area and the second planar area between the overlapping portions of the first and second planar areas.

The cover window may further include a coating layer formed on an outer surface of the flat area and the folded area.

The coating layer may include at least one of a hard layer that increases the hardness of the cover window, an antireflection layer that reduces the surface reflectance of the cover window, and an anti-fingerprint layer that decreases the surface energy of the cover window.

The hard layer may include an acrylic resin or a material in which silica nanoparticles are mixed with an acrylic resin.

The antireflection layer may be formed of an organic thin film or an inorganic thin film.

The anti-fingerprint layer may include a fluorine-based or silicon-based material.

The cover window may further include a lower coating layer formed on the flat area and the inner surface of the folded area.

The flexible panel may include an organic light emitting diode.

As described above, the foldable display device according to the exemplary embodiment of the present invention has an effect that the cover window can have high surface hardness in the flat area, while the cover window has good foldability in the folded area and the folded area is not visually recognized. have.

1 is a perspective view of a foldable display device according to an embodiment of the present invention.
2 is a partial cross-sectional view of the foldable display device taken along line II-II of FIG. 1.
3 is a perspective view of the cover window of FIG. 2 in an unfolded state.
4 is a perspective view of the cover window of FIG. 3 in a folded state.
5 is a cross-sectional view of a foldable display device according to another exemplary embodiment of the present invention, in which a cover window is opened.
6 is a cross-sectional view of the cover window of FIG. 5 in a folded state.
7 is a layout diagram illustrating a pixel structure of the flexible display panel shown in FIG. 2.
8 is a cross-sectional view of the flexible display panel taken along line XX of FIG. 7.

Embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art may easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

In the drawings, the thicknesses are enlarged to clearly express various layers and regions. The same reference numerals are assigned to similar parts throughout the specification. When a part of a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the case where the other part is "directly above", but also the case where there is another part in between. Conversely, when one part is "right above" another part, it means that there is no other part in the middle.

Then, a foldable display device according to an exemplary embodiment of the present invention will be described in detail below.

First, a foldable display device according to an embodiment of the present invention will be described in detail.

1 is a perspective view of a foldable display device according to an exemplary embodiment of the present invention, and FIG. 2 is a partial cross-sectional view of the foldable display device taken along line II-II of FIG. 1. Referring to FIGS. 1 and 2, the foldable display device 100 according to an exemplary embodiment of the present invention overlaps the flexible display panel 10 and the flexible display panel 10 and overlaps the flexible display panel 10 from an external impact. ) And a cover window 20 to protect it.

The flexible display panel 10 includes a flexible film such as a plastic film, and displays an image by disposing an organic light emitting diode and a pixel circuit on the flexible film. The detailed structure of the flexible display panel 10 will be described later. A touch panel 30 sensing a user's touch motion may be positioned between the flexible display panel 10 and the cover window 20.

The flexible display panel 10 and the cover window 20 may be fixed to the support 40. The support body 40 may be composed of a first support part 41 and a second support part 42 and a hinge part 43 connecting them. The support body 40 is unfolded or folded around the hinge portion 43, and according to the operation of the support body 40, the flexible display panel 10 and the cover window 20 are also unfolded around the hinge portion 43 Folded.

The cover window 20 is located outside the side where the image is displayed on the flexible display panel 10, and is made of a transparent hard material, so that the image of the flexible display panel 10 is transmitted as it is and is flexible from external impact. The display panel 10 is protected.

The cover window 20 may be formed in a single layer structure or a multilayer structure of a polymer material, plastic material, or glass material. In FIG. 2, a cover window 20 having a single layer structure is illustrated as an example.

Then, a cover window of the foldable display device according to an exemplary embodiment will be described in detail with reference to FIGS. 3 and 4.

3 is a perspective view of the cover window of FIG. 2 in an expanded state, and FIG. 4 is a perspective view of the cover window of FIG. 3 in a folded state. 3 and 4, the cover window 20 is formed with a second hardness lower than the first hardness between the first flat area 22 and the second flat area 23 on both sides formed with a first hardness. And a folded area 21 that becomes.

Therefore, the flat areas 22 and 23 on both sides form a rigid area having a higher hardness than the folded area 21, and the folded area 21 has a higher foldability than the flat areas 22 and 23. To form a soft area.

The planar regions 22 and 23 are disposed on both sides of the cover window 20 in the first direction.

The flat areas 22 and 23, which occupy most of the area of the cover window 20, provide high surface hardness to the cover window 20 when the flexible display panel 10 is unfolded, and the folded area 21 is flexible. Good foldability is provided to the cover window 20 when the display panel 10 is folded.

The planar regions 22 and 23 and the folded region 21 may be physically coupled by a thermocompression method. When heat and pressure are applied to the folded region 21, the folded region 21 may be coupled to the flat regions 22 and 23.

In addition, the planar regions 22 and 23 and the folded region 21 may be chemically combined by a compression method. When heat is applied to the folded region 21, the folded region 21 may be coupled to the flat regions 22 and 23.

The folded region 21 is set to have a first width W1 between the planar regions 22 and 23 and is formed to be elongated in a second direction crossing the first direction.

The folded region 21 has two vertical portions consisting of a first vertical portion and a second vertical portion, and a horizontal portion connecting the first vertical portion and the second vertical portion, and one end of the first vertical portion is a second flat area It is connected to the end of (23), and the end of the second vertical part is connected to the end of the first plane area.

The connecting angle of each vertical portion and the horizontal portion may be a right angle, may be formed at an angle other than a right angle, and the connecting portion of each vertical portion and the horizontal portion may have a round shape.

The folded region 21 is formed thinly in the form of a film between the two plane regions 22 and 23 of the folded portion of the first and second flat regions 22 and 23 overlap, By taking the form of bonding the first flat area 22 and the second flat area 23 to each other, it may not be visually recognized to the outside of the display device compared to forming the entire folded portion of the flat area as a soft area.

On the other hand, the planar regions 22 and 23 are also formed of a plastic-based material because there is a part that folds together with the fold region 21. Polyethylene naphthalate (PEN), polymethyl methacrylate (PMMA) methacrylate), polyurethane (PU, polyurethane), polyethylene terephthalate (PET), polyimide (PI), polycarbonate (PC, polycarbonate), and the like.

The folded region 21 may be formed of an organic material, an acrylic resin, or silicone that exhibits physical properties of a soft material having good foldability. Such an organic material, acrylic resin, or silicone may have adhesiveness and form the folded region 21 and may be physically bonded to the planar regions 22 and 23 formed of a plastic-based material.

Hereinafter, a cover window of a foldable display device according to another embodiment of the present invention will be described in detail.

5 is a cross-sectional view of a foldable display device according to another exemplary embodiment of the present invention in a state in which a cover window is unfolded, and FIG. 6 is a cross-sectional view of a state in which the cover window of FIG. 5 is folded. 5 and 6, the cover window 220 further includes a functional coating layer 230 and a lower coating layer 240 in the structure of the cover window 20 according to an embodiment of the present invention described above.

The functional coating layer 230 is formed on the outer surfaces of the planar regions 22 and 23 and the folded region 21 to impart related functionality to the cover window 220. For example, the functional coating layer 230 may be formed of at least one of a hard layer 231, an antireflection layer 232, and an anti-fingerprint layer 233. For convenience, FIG. 5 illustrates a functional coating layer 230 including a hard layer 231, an antireflection layer 232, and an anti-fingerprint layer 233.

The hard layer 231 is coated on the outer surface of the cover window 20 of the first embodiment, that is, the flat areas 22 and 23 and the folded area 21 to increase the hardness of the cover window 220. For example, the hard layer 231 may be formed by mixing an acrylic resin or an acrylic resin with nanoparticles. Nanoparticles may be formed of silica.

The antireflection layer 232 is coated on the hard layer 231 to lower the surface reflectivity of the cover window 220. For example, the antireflection layer 232 may be formed of an organic thin film or an inorganic thin film.

The anti-fingerprint layer 233 is oil-repellent or water-repellent coated on the anti-reflection layer 232 to lower the surface energy of the cover window 220. For example, the anti-fingerprint layer 233 may be formed of fluorine-based or silicon-based.

The lower coating layer 240 is coated on the inner surface of the cover window 20, that is, under the flat areas 22 and 23 and the folded area 21 according to an exemplary embodiment to increase the hardness of the cover window 220. For example, the lower coating layer 240 may be formed by mixing an acrylic resin or an acrylic resin with nanoparticles. Nanoparticles can be formed of silica

The hard layer 231 and the lower coating layer 240 formed on the outer surface of the cover window 20 may prevent materials that may be included in the folded region 21 from leaking out.

Hereinafter, an example of the flexible display panel 10 on which the cover windows 20 and 220 according to the exemplary embodiment described above are disposed will be described.

7 is a layout diagram illustrating a pixel structure of the flexible display panel shown in FIG. 2, and FIG. 8 is a cross-sectional view of the flexible display panel taken along line X-X of FIG. 7. The flexible display panel 10 is not limited to the structure described below, and may be formed of an organic light emitting display device or a flexible liquid crystal display device having another structure.

Referring to FIGS. 7 and 8, the flexible display panel 10 includes a pixel circuit DC and an organic light emitting diode OLED formed for each pixel. The pixel circuit DC basically includes a switching thin film transistor 50, a driving thin film transistor 60, and a capacitor 70. In addition, the flexible display panel 10 includes a gate line 81 disposed along one direction, a data line 82 and a common power line 83 insulatedly crossing the gate line 81.

Here, one pixel may be defined as a boundary between the gate line 81, the data line 82, and the common power line 83, but is not limited thereto. A pixel refers to a basic unit for displaying an image, and the flexible display panel 10 displays an image through a plurality of pixels.

7 shows an active driving type flexible display panel 10 of a 2Tr-1Cap structure including two thin film transistors 50 and 60 and one capacitor 70 in one pixel, but the flexible display panel The structure of (10) is not limited to the illustrated example. The flexible display panel 10 may include three or more thin film transistors and two or more capacitors, and separate wirings may be further formed to have various structures.

The organic light emitting diode OLED includes a pixel electrode 91, an organic emission layer 92, and a common electrode 93. One of the pixel electrode 91 and the common electrode 93 is a hole injection electrode, and the other is an electron injection electrode. When electrons and holes are injected from the pixel electrode 91 and the common electrode 93 to the organic light emitting layer 92, and excitons in which the holes and electrons are combined fall from the excited state to the ground state, light is emitted.

The pixel electrode 91 may be formed of a metal having high reflectivity, and the common electrode 93 may be formed of a transparent conductive film. In this case, light from the organic emission layer 92 is reflected by the pixel electrode 91, passes through the common electrode 93 and the encapsulation substrate 12 and is emitted to the outside. In FIG. 8, reference numeral 11 denotes a flexible substrate.

The capacitor 70 includes a pair of capacitor electrodes 71 and 72 disposed with an interlayer insulating film 85 that is a dielectric material therebetween. The storage capacity is determined by the electric charge stored in the capacitor 70 and the voltage between the two capacitor electrodes 71 and 72.

The switching thin film transistor 50 includes a switching semiconductor layer 51, a switching gate electrode 52, a switching source electrode 53, and a switching drain electrode 54. The driving thin film transistor 60 includes a driving semiconductor layer 61, a driving gate electrode 62, a driving source electrode 63, and a driving drain electrode 64.

The switching thin film transistor 50 is used as a switching element for selecting a pixel to emit light. The switching gate electrode 52 is connected to the gate line 81. The switching source electrode 53 is connected to the data line 82 and the switching drain electrode 54 is connected to any one capacitor electrode 71.

The driving thin film transistor 60 applies driving power to the pixel electrode 91 to emit light from the organic emission layer 92 of the selected pixel. The driving gate electrode 62 is connected to the capacitor electrode 71 connected to the switching drain electrode 54. The driving source electrode 63 and the other capacitor electrode 72 are connected to the common power line 83. The driving drain electrode 64 is connected to the pixel electrode 91 of the organic light emitting diode OLED through a contact hole.

The switching thin film transistor 50 is operated by a gate voltage applied to the gate line 81 to transfer the data voltage applied to the data line 82 to the driving thin film transistor 60. A voltage corresponding to the difference between the common voltage applied from the common power line 83 to the driving thin film transistor 60 and the data voltage transferred from the switching thin film transistor 50 is stored in the capacitor 70 and stored in the capacitor 70. A current corresponding to the stored voltage flows to the organic light emitting diode OLED through the driving thin film transistor 60, and the organic light emitting layer 92 emits light.

As described above, in the foldable display device according to the exemplary embodiment of the present invention, the cover window can have a high surface hardness in the flat area while having good foldability in the folded area and the outside folded area is not visually recognized. There is.

Although the preferred 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 by those skilled in the art using the basic concept of the present invention defined in the following claims are also present. It belongs to the scope of rights of

10: flexible display panel 20, 220: cover window
21: folded area 22, 23: flat area
30: touch panel 40: support
41, 42: first, second support 43: hinge
100: foldable display device 230: functional coating layer
231: hard layer 232: anti-reflection layer
233: anti-fingerprint layer 240: lower coating layer

Claims (11)

A flexible display panel, and
And a cover window disposed outside the flexible display panel,
The cover window
A first plane region and a second plane region formed with a first hardness and at least partially overlapping each other,
In a portion where the first flat area and the second flat area overlap, formed in the form of a film that is disposed between the first flat area and the second flat area to bond the first flat area and the second flat area And a folded region formed with a second hardness lower than the first hardness,
The film shape has a first vertical portion, a second vertical portion facing the first vertical portion, and a pair of horizontal portions connecting them at both ends of the first vertical portion and the second vertical portion, and the first The vertical part is exposed in one plane perpendicular to the thickness direction of the cover window, the second vertical part is exposed in the other plane facing the one plane, and the pair of horizontal parts connect the one plane and the other A foldable display that is exposed to the connecting side. In claim 1,
Each of the first and second planar regions is polyethylene naphthalate (PEN), polymethyl methacrylate (PMMA), polyurethane (PU), polyethylene terephthalate (PET, polyethyleneterephthalate). ), polyimide (PI), and polycarbonate (PC, polycarbonate). In claim 1,
The foldable display device is formed of an acrylic resin or silicone. delete In claim 1,
The cover window further includes a coating layer formed on an outer surface of the first flat area, the second flat area, and the folded area. In clause 5,
The coating layer is a hard layer that increases the hardness of the cover window,
An antireflection layer for lowering the surface reflectance of the cover window, and
A foldable display device comprising at least one of an anti-fingerprint layer for lowering surface energy of the cover window. In paragraph 6,
The hard layer is a foldable display including an acrylic resin or a material obtained by mixing silica nanoparticles with an acrylic resin. In paragraph 6,
The antireflection layer is a foldable display device formed of an organic thin film or an inorganic thin film. In paragraph 6,
The anti-fingerprint layer is a foldable display device including a fluorine-based or silicon-based material. In paragraph 6,
The cover window further includes a lower coating layer formed on the flat area and the inner surface of the folded area. In claim 1,
The flexible display panel is a foldable display device including an organic light emitting diode.

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