KR102621128B1 - Optical cleared adhesive and foldable display device including the same - Google Patents

Abstract

A foldable display device according to an embodiment of the present specification includes a display panel that displays an image, a cover window located on top of the display panel, and a back plate located below the cover window. It includes a first adhesive layer interposed between the display panel and the cover window, and the first adhesive layer has a shape in which a first area having a first modulus and a second area having a second modulus smaller than the first modulus are patterned. The first region of the first adhesive layer has a shape in which the width of the portion adjacent to the display panel and the cover window is greater than the width of the central portion. Through this, when the foldable display device is folded, the slip characteristics of each layer are improved and the interfacial adhesion is increased, thereby improving the durability of the foldable display device.

Description

Optical adhesive layer for a foldable display device and a foldable display device including the same {Optical cleared adhesive and foldable display device including the same}

This specification relates to a foldable display device, and more specifically, to an adhesive layer for a foldable display device with improved durability and a foldable display device including the same.

In recent years, as society has entered a full-fledged information age, the display field, which processes and displays large amounts of information, has developed rapidly, and various flat display devices have been developed in response to this. Be in the spotlight.

Specific examples of such flat display devices include Liquid Crystal Display device (LCD), Plasma Display Panel device (PDP), Field Emission Display device (FED), and electroluminescent display. Examples include electroluminescence display devices (ELD) and organic light emitting diodes (OLED). These flat display devices show excellent performance in terms of thinness, weight, and low power consumption, compared to the existing cathode ray tube (Cathode Ray Tube). : CRT) is rapidly being replaced.

Meanwhile, these flat display devices use a glass substrate to withstand the high heat generated during the manufacturing process, so there are limitations in providing lightness, thinness, and flexibility.

Therefore, flexible display devices, which are manufactured using flexible materials such as plastic instead of existing inflexible glass substrates and can maintain display performance even when bent like paper, are rapidly emerging as the next generation flat display devices.

Flexible display devices use plastic thin-film transistor substrates rather than glass, and can be used as highly durable unbreakable devices, bendable devices that can be bent without breaking, rollable devices that can be rolled up, and foldable folder devices. It can be divided into foldable, etc. These flexible display devices have advantages in space utilization, interior design, and design, and can have various application fields.

In particular, in recent years, research on foldable display devices that are portable in a folded state and display images in an unfolded state has been actively conducted in order to achieve ultra-thinness, lightness, and miniaturization as well as large area.

Foldable display devices can be applied to various fields such as TVs and monitors, as well as mobile devices such as mobile phones, ultra mobile PCs, e-books, and electronic newspapers.

These foldable display devices largely include a display panel for displaying images, a back plate located at the bottom of the display panel to support the display panel, and a cover window located in front of the display panel to protect the display panel. Includes (cover window).

Here, an optical adhesive layer is interposed between the display panel and the cover window, and the display panel and the back plate, so that the display panel, the cover window, and the back plate are integrated and modularized.

At this time, the optical adhesive layer applied to the foldable display device is formed of OCA (Optical Cleared Adhesive). If this optical adhesive layer has a low modulus, the slip (slip) of each layer occurs during folding and unfolding of the foldable display device. Although the slip characteristics are good, the recovery characteristics of the foldable display device are insufficient, causing plastic deformation of the foldable display device as shown in FIG. 1A.

Plastic deformation of the foldable display device limits folding and unfolding, causes appearance defects, and ultimately deteriorates the display quality of the display panel.

In addition, if the optical adhesive layer has a high modulus, it imposes restrictions on the folding and unfolding of the foldable display device and increases the bending stress, which can cause thin film layer peeling, such as lifting of the cover window, as shown in FIG. 1B. causes the phenomenon.

This ultimately causes damage to the display panel.

In order to solve the above problems, the inventors of the present invention invented an optical adhesive with a new structure to provide a foldable display device with improved durability and no limitations in folding and unfolding.

Through this, it is possible to prevent the display quality of the display panel from deteriorating and also prevent damage to the display panel.

The tasks of this specification are not limited to the tasks mentioned above, and other tasks not mentioned will be clearly understood by those skilled in the art from the description below.

In order to achieve the purpose as described above, the foldable display device according to an embodiment of the present invention includes a display panel for displaying an image, a cover window on the upper part of the display panel, and a back plate on the lower part of the cover window. . It includes a first adhesive layer interposed between the display panel and the cover window, and the first adhesive layer has a shape in which a first area having a first modulus and a second area having a second modulus smaller than the first modulus are patterned. The first region of the first adhesive layer has a shape in which the width of the portion adjacent to the display panel and the cover window is greater than the width of the central portion.

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

According to the present invention, an adhesive layer is disposed between the cover window and the display panel, and between the display panel and the back plate, and integrates and modulates the cover window, the display panel, and the back plate into a first region and a first region having a high modulus. By forming the second region with a lower modulus, the durability of the adhesive layer itself is improved.

Through this, the durability of the foldable display device itself is improved, which has the effect of preventing plastic deformation of the foldable display device.

Therefore, it is possible to prevent limitations in folding and unfolding the foldable display device, and also prevent appearance defects from occurring, thereby preventing problems such as damage to the display panel or deterioration of display quality. There is a possible effect.

The effects according to the present invention are not limited to the contents exemplified above, and further various effects are included in the present specification.

Figure 1a is a photograph showing the plastic deformation problem of the backplate.
Figure 1b is a photograph showing the lifting phenomenon of the cover window.
Figure 2 is a schematic diagram schematically showing a foldable display device according to an embodiment of the present invention.
FIG. 3 is a cross-sectional view schematically showing the display panel of FIG. 2.
4A to 4B are plan views schematically showing an adhesive layer according to another embodiment of the present invention.
Figure 5 is a plan view schematically showing an adhesive layer according to another embodiment of the present invention.
Figure 6 is a plan view schematically showing an adhesive layer according to another embodiment of the present invention.
7A to 7B are schematic diagrams schematically showing the manufacturing process of an adhesive layer according to an embodiment of the present invention.

The advantages and features of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and will be implemented in various different forms. The present embodiments only serve to ensure that the disclosure of the present invention is complete and that common knowledge in the technical field to which the present invention pertains is not limited. It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims.

The shapes, sizes, proportions, angles, numbers, etc. disclosed in the drawings for explaining embodiments of the present invention are illustrative, and the present invention is not limited to the matters shown. Like reference numerals refer to like elements throughout the specification. Additionally, in describing the present invention, if it is determined that a detailed description of related known technologies may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. When 'includes', 'has', 'consists of', etc. mentioned in this specification are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, the plural is included unless specifically stated otherwise.

When interpreting a component, it is interpreted to include the margin of error even if there is no separate explicit description.

In the case of a description of a positional relationship, for example, if the positional relationship of two parts is described as 'on top', 'on the top', 'on the bottom', 'next to', etc., 'immediately' Alternatively, there may be one or more other parts placed between the two parts, unless 'directly' is used.

When an element or layer is referred to as “on” another element or layer, it includes instances where the other layer or other element is directly on top of or interposed between the other elements.

Although first, second, etc. are used to describe various elements, these elements are not limited by these terms. These terms are merely used to distinguish one component from another. Accordingly, the first component mentioned below may also be the second component within the technical spirit of the present invention.

Like reference numerals refer to like elements throughout the specification.

The size and thickness of each component shown in the drawings are shown for convenience of explanation, and the present invention is not necessarily limited to the size and thickness of the components shown.

Each feature of the various embodiments of the present invention can be partially or fully combined or combined with each other, and as can be fully understood by those skilled in the art, various technical interconnections and operations are possible, and each embodiment may be implemented independently of each other. It may be possible to conduct them together due to a related relationship.

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the attached drawings.

FIG. 2 is a schematic diagram schematically showing a foldable display device according to an embodiment of the present invention, and FIG. 3 is a cross-sectional view schematically showing the display panel of FIG. 2.

As shown, the foldable display device 100 largely includes a display panel 110 for displaying an image, a back plate 120 that supports the display panel 110, and a back plate 120 that protects the display panel 110. It includes a cover window 130 for this purpose.

A functional layer (not shown) may be included between the display panel 110 and the cover window 130. The functional layer may include, for example, a polarizer, a phase retardation plate, or a touch panel.

At this time, if the direction in the drawing is defined for convenience of explanation, the back plate 120 is located on the back of the display panel 110 under the premise that the display surface of the display panel 110 faces forward, and the display panel 110 ) is located in front of the cover window 130.

Here, the display panel 110 includes a liquid crystal display device (LCD), a plasma display device (PDP), a field emission display device (FED), and an electroluminescent display device ( It can be made of either Electroluminescence Display device (ELD) or Organic Light Emitting Diodes (OLED). However, it is preferable that OLED, a representative example of flexible and foldable display devices that can maintain display performance even when bent like paper, is used as the display panel 110.

OLED is a self-luminous device and does not require the backlight used in liquid crystal displays, which are non-light emitting devices, so it can be lightweight and thin.

In addition, it has an excellent viewing angle and contrast ratio compared to liquid crystal displays, is advantageous in terms of power consumption, can be driven at low direct current voltage, has a fast response speed, is strong against external shocks because the internal components are solid, and has a wide operating temperature range. It has advantages.

In particular, because the manufacturing process is simple, it has the advantage of significantly reducing production costs compared to existing liquid crystal display devices.

In the display panel 110 made of such OLED, a substrate 101 on which a driving thin film transistor (DTr) and a light emitting diode (E) are formed is encapsulated by a protective film 102.

Here, we will take a closer look at the display panel 110 (hereinafter referred to as OLED panel) made of OLED with reference to FIG. 3.

A semiconductor layer 104 is formed in the pixel area P on the substrate 101. The semiconductor layer 104 is made of silicon, and its central portion is composed of an active region 104a forming a channel, and source and drain regions 104b and 104c doped with a high concentration of impurities on both sides of the active region 104a. However, the present invention is not limited thereto, and the semiconductor layer 104 may be made of an oxide semiconductor.

A gate insulating film 105 is formed on the semiconductor layer 104.

A gate electrode 107 corresponding to the active area 104a of the semiconductor layer 104 and a gate wiring extending in one direction may be formed on the gate insulating film 105.

Additionally, a first interlayer insulating film 106a is formed on the entire upper surface of the gate electrode 107 and the gate wiring. At this time, the first interlayer insulating film 106a and the gate insulating film 105 below the first interlayer insulating film 106a are first and second semiconductors that expose the source and drain regions 104b and 104c located on both sides of the active region 104a, respectively. A layer contact hole (109) is provided.

Next, on the top of the first interlayer insulating film 106a including the first and second semiconductor layer contact holes 109, source and drain regions 104b are spaced apart from each other and exposed through the first and second semiconductor layer contact holes 109. , 104c) and source and drain electrodes 108a and 108b are formed, respectively.

And, a second electrode having a drain contact hole 112 exposing the drain electrode 108b on the source and drain electrodes 108a and 108b and the first interlayer insulating film 106a exposed between the source and drain electrodes 108a and 108b. 2. An interlayer insulating film 106b is formed.

At this time, the semiconductor layer 104 including the source and drain electrodes (108a, 108b), the source and drain regions (104b, 104c) in contact with the source and drain electrodes (108a, 108b), and the semiconductor layer (104) formed on the upper part of the semiconductor layer (104). The gate electrode 107 forms a driving thin film transistor (DTr).

Meanwhile, although not shown in the drawing, a data wire (not shown) is formed by crossing the gate wire (not shown) to define the pixel area (P). Additionally, the switching thin film transistor (not shown) has the same structure as the driving thin film transistor (DTr) and is connected to the driving thin film transistor (DTr).

In FIG. 3, the switching thin film transistor (not shown) and the driving thin film transistor (DTr) are configured such that the semiconductor layer 104 is made of a polysilicon semiconductor layer and the gate electrode 107 is disposed on the semiconductor layer 104. Although it is shown as a co-planar type, it is not limited to this and is made of amorphous silicon of pure and impurities, and is formed as a bottom gate type in which the gate electrode 107 is disposed below the semiconductor layer 104. It could be.

In addition, a first electrode 111 forming an anode as a component of the light emitting diode E is formed on the second interlayer insulating film 106b in an area where an image is displayed. For example, the first electrode 111 may be made of a material with a relatively high work function value.

The first electrode 111 is electrically connected to the drain electrode 108b of the driving thin film transistor (DTr) through a contact hole. When the OLED display panel 110 is a top emission type, the first electrode 111 may be defined as including a transparent conductive material and an opaque conductive material with high reflectance. For example, the first electrode 241 is made of transparent conductive oxide (TCO) such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO), and silver (Ag), aluminum (Al), and gold (Au). ), molybdenum (Mo), tungsten (W), chromium (Cr), or alloys thereof.

Referring to FIG. 3, the first electrode 111 is formed for each pixel area (P), and a bank (bank: 119) is located between the first electrodes 111 formed for each pixel area (P).

The bank 119 is formed in the remaining area excluding the light emitting area. Accordingly, the bank 119 has a bank hole that exposes the first electrode 111 corresponding to the light emitting area. The bank 119 may be made of an inorganic insulating material such as silicon nitride (SiNx) or silicon oxide (SiOx), or an organic insulating material such as BCB, acrylic resin, or imide resin.

That is, the first electrode 111 is formed in a structure where the bank 119 serves as a boundary for each pixel area (P) and the first electrode 111 is separated for each pixel area (P).

And the organic light-emitting layer 113 is formed on the first electrode 111.

Here, the organic light-emitting layer 113 may be composed of a single layer made of a light-emitting material, and in order to increase light-emitting efficiency, a hole injection layer, a hole transport layer, an emitting material layer, and an electron layer may be formed. It may be composed of multiple layers of an electron transport layer and an electron injection layer.

This organic light emitting layer 113 expresses the colors of red (R), green (G), and blue (B). In a general method, red (R), green (G), and blue are displayed for each pixel area (P). (B) Separate organic materials (113a, 113b, 113c) that emit color are patterned and used.

In addition, a second electrode 115 forming a cathode is formed on the entire surface of the organic light emitting layer 113.

At this time, the second electrode 115 includes a translucent metal film formed by depositing a thin metal material with a low work function. At this time, the second electrode 115 may have a two-layer structure in which a transparent conductive material is thickly deposited on a translucent metal film.

Accordingly, the light emitted from the organic emission layer 113 is driven in a top emission manner to be emitted toward the second electrode 115.

Alternatively, the second electrode 115 may be made of an opaque metal film, and the light emitted from the organic emission layer 113 may be driven in a bottom emission manner to be emitted toward the first electrode 111.

When a predetermined voltage is applied to the first electrode 111 and the second electrode 115 according to the selected color signal, the OLED panel 110 generates holes injected from the first electrode 111 and the second electrode 115. Electrons provided from are transported to the organic light-emitting layer 113 to form exciton, and when the exciton transitions from the excited state to the ground state, light is generated and emitted in the form of visible light.

At this time, the emitted light passes through the transparent second electrode 115 or the first electrode 111 and goes out, so the OLED panel 110 implements an arbitrary image.

A protective film 102 in the form of a thin film is formed on the driving thin film transistor (DTr) and the light emitting diode (E), and the OLED panel 101 is encapsulated through the protective film 102. The protective film 102 may include at least two inorganic layers 102a to prevent external oxygen and moisture from penetrating into the OLED panel 110. At this time, it is preferable that an organic layer (102b) is interposed between the two inorganic layers (102a) to supplement the impact resistance of the inorganic layer (102a).

Meanwhile, the substrate 101 may be made of thin polyimide to have flexible properties. Since the substrate 101 made of such thin polyimide is not suitable for the formation process of components such as thin film transistors (DTr), the thin film transistor (DTr) is formed by attaching the substrate made of polyimide to a carrier substrate such as a glass substrate. The formation process of the same components is carried out. Thereafter, the OLED panel 110 can be manufactured by separating the carrier substrate and the substrate made of polyimide.

The function plate (not shown) on the top of the OLED panel 110 may include a touch panel. The OLED panel 110 and the touch panel may be bonded to each other through an adhesive layer (not shown) of the touch panel.

Here, although not shown, the touch panel includes a first touch film (not shown) on which a first touch electrode (not shown) is formed and a second touch film (not shown) on which a second touch electrode (not shown) is formed, spaced apart from each other and facing each other. It can be arranged to do so.

The first touch electrode (not shown) is deposited on the entire surface of the first touch film (not shown), and the first touch electrode (not shown) is made of indium-tin-oxide (ITO) or indium-zinc-oxide, which are transparent conductive materials. (IZO).

And, on the second touch film (not shown) facing the first touch film (not shown), the second touch electrode (not shown) is formed in the form of a bar spaced at a certain distance, and is made of aluminum (Al) or aluminum. It is made of metal materials such as alloy (AlNd), magnesium (Mg), gold (Au), and silver (Ag).

The first and second touch electrodes (not shown) form a touch sensor (not shown).

Therefore, when a certain point is touched on the first touch film (not shown) with a predetermined input means such as a finger or a pen, the first touch electrode (not shown) formed on the first touch film (not shown) and the first touch electrode (not shown) are connected to the first touch film (not shown). 2 The second touch electrodes (not shown) formed on the touch film (not shown) are mutually energized, and after reading the voltage value changed by the resistance value of the position, the control device can find the position coordinates according to the change in potential difference. . However, the above-described touch panel is an example, and is not limited thereto, and various types of touch panels may be used.

A cover window 130 is located at the top of the display panel 110.

The cover window 130 protects the display panel 110 from external shock and transmits light emitted from the display panel 110 so that the image displayed on the display panel 110 is visible from the outside.

This cover window 130 is made of polymethylmethacrylate (PMMA), polycarbonate (PC), cycloolefin polymer (COP), and polyethylene terephthalate (polyethylene), which have impact resistance and light transparency. It may be a film type made of organic materials such as terephthalate (PET), PI (polyimide), or PA (polyaramid), or it may be made of inorganic materials such as thin glass or sapphire.

Since the display panel 110 is too thin, the back plate 120 is attached to the back of the display panel 110 to support the display panel 110, and is made of a metal material such as stainless steel (SUS) or polymenyl methacrylate. (polymethyl methacrylate, PMMA), polycarbonate (PC), polyvinylalcohol (PVA), acrylonitrile-butadiene-styrene (ABS), polyethylene terephthalate , PET).

The display panel 110 is integrally modularized through the cover window 130 and the back plate 120, and in front of the display panel 110 where the image is displayed, there is a cover window (that can protect the display panel 110). 130) is attached through the first adhesive layer 140, and a backplate 120 for supporting the display panel 110 is attached to the back of the display panel 110 through the second adhesive layer 150.

Here, the first and second adhesive layers 140 and 150 are made of OCA (Optical Cleared Adhesive). Let's look at the first adhesive layer 140 of the foldable display device 100 according to an embodiment of the present invention in detail. .

The first adhesive layer 140 may include a first region 140a having a first modulus and a second region 140b having a second modulus smaller than the first modulus. For example, the modulus of the first region 140a may be 10 ⁶ to 10 ⁷ Pa, and the modulus of the second region 140b may be 10 ³ to 10 ⁵ Pa.

The first area 140a of the first adhesive layer 140 may have a width of a portion adjacent to the display panel and the cover window and a width of the center thereof. That is, the width of the portion adjacent to the display panel 110 and the cover window 130 of the first region 140a of the first adhesive layer 140 may be greater than the width of the central portion.

The first region 140a of the first adhesive layer 140 may have stronger adhesive force than the second region 140b.

That is, the first adhesive layer 140 is patterned with a first region 140a having a high modulus and strong adhesive strength, and a second region 140b having a low modulus and weak adhesive strength compared to the first region 140b. (140a) has a shape in which the width of the portion adjacent to the display panel 110 and the cover window 130 is larger than the width of other portions.

If, unlike the foldable display device according to this embodiment, the cover window 130 and the display panel are bonded with the first adhesive layer 140, which is not patterned, and the first adhesive layer has a low modulus, the foldable display device Although the adhesive layer does not limit folding and unfolding, the recovery characteristics of the foldable display device are insufficient, causing plastic deformation of the foldable display device. Additionally, when the foldable display device is repeatedly folded and unfolded, the adhesive strength between the display panel and the cover window and/or the display panel and the backplate may deteriorate, resulting in delamination.

On the other hand, if the first adhesive layer has a high modulus, the folding and unfolding of the foldable display device is limited, and the folding characteristics of the foldable display device can be rapidly deteriorated by causing folding stress. There is no outside.

However, in the case of the foldable display device according to the present embodiment, as described above, the first adhesive layer 140 has a first region 140a having a high modulus and a second region 140b having a lower modulus than the first region 140a. ), and the first area 140a may have a shape in which the width of the portion adjacent to the display panel 110 and the cover window 130 is greater than the width of the central portion.

The wider the high modulus area, the higher the interfacial adhesion between the first adhesive layer 140 and the display panel 110 and the first adhesive layer 140 and the cover window 130. As the interfacial adhesion increases, reliability against peeling due to folding stress that occurs during folding can be improved. In addition, the low modulus area at the center of the first adhesive layer 140 increases, and the adhesion between the display panel 110 and the cover window 130 at the top and bottom of the first adhesive layer 140 and the first adhesive layer 140 decreases. It can get higher. In addition, slip occurs in each layer during folding, and in this case, slip characteristics can be improved due to the low modulus region. That is, in general, the lower the modulus, the higher the slip characteristics, but since it is disadvantageous in terms of interfacial adhesion, as in the present embodiment, a first region 140a with a high modulus and a second region with a lower modulus than the first region are used. (140b), and the width of the first area 140a decreases from the area adjacent to the display panel 110 and the cover window 130 toward the center, thereby optimizing slip characteristics and interfacial adhesion. You can.

The display panel 110 and a back plate 120 for supporting the display panel 110 are attached through the second adhesive layer 150. Here, the second adhesive layer 150 includes a first area 150a having a first modulus like the first adhesive layer 140 and a second area 150b having a second modulus smaller than the first modulus. The second adhesive layer 150 may have the same structure and material as the first adhesive layer 140.

4A to 4B are plan views schematically showing the first adhesive layer 140 according to another embodiment of the present invention, and FIG. 5 is a plan view schematically showing the first adhesive layer 140 according to another embodiment of the present invention. . And Figure 6 is a plan view schematically showing the first adhesive layer 140 according to another embodiment of the present invention.

The shape of the first region 140a of the first adhesive layer 140 will be described with reference to FIGS. 4A to 6 .

The first region 140a of the first adhesive layer 140 may be patterned in various shapes, such as islands spaced apart from each other as shown in FIGS. 4A and 4B. For example, the island shape may be circular or polygonal. Additionally, as shown in FIG. 5, the first region 140a of the first adhesive layer 140 may be patterned in a stripe shape. The stripe shape may be formed in a vertical or horizontal direction, and may also be patterned in a shape that intersects each other. Referring to FIG. 6, the first area 140a may be patterned into a shape including both an island shape and a stripe shape.

Figures 7a and 7b are schematic diagrams schematically showing the manufacturing process of the first adhesive layer 140 according to an embodiment of the present invention.

As shown in FIG. 7A, the first adhesive layer 140 is divided into a first region 140a and a second region 140b and is manufactured to enable UV irradiation to the portion corresponding to the first region 140a. After placing the mask 190 adjacent to the first surface 141 of the first adhesive layer 140, UV is irradiated using the UV irradiation device 290.

At this time, the first adhesive layer 140 may be made of acrylate-based, epoxy-based, polyimide-based, vinyl-based, etc., and is preferably made of OCA (Optical Cleared Adhesive).

In particular, the first adhesive layer 140 contains an initiator such as Iracure #184 or Iracure #819 that reacts to UV, and when UV is irradiated, the first area 141a increases the density of the first adhesive layer 140 itself by UV curing. As it improves, it hardens.

At this time, the distance between the first adhesive layer 140 and the mask 190, the UV irradiation angle, and the UV irradiation time can be adjusted to form a width that decreases from the portion adjacent to the surface of the first region 140a toward the center. there is. After curing is completed to the center, as shown in FIG. 7b, the second side 142, which is opposite to the first side 141 of the first adhesive layer 140, is positioned adjacent to the mask 190 and then the mask ( 190), the UV irradiation angle, and the UV irradiation time can be adjusted to form a pattern whose width decreases from the surface of the first surface 141 and the second surface 142 toward the center.

That is, the first adhesive layer 140 according to an embodiment of the present invention has both the first region 140a and the second region 140b made of the same material, but the first region 140a and the second region 140b are Depending on this, only the modulus and adhesive properties change.

Through this, even though the first area 140a and the second area 140b have different modulus and adhesive properties, visibility due to the material characteristics of the first area 140a and the second area 140b does not occur.

A foldable display device according to various embodiments of the present invention can be described as follows.

A foldable display device according to an embodiment of the present invention includes a display panel and a cover window 130 on top of the display panel. The lower portion of the display panel 110 includes a back plate 120, and a first adhesive layer 140 is interposed between the display panel 110 and the cover window 130. The first adhesive layer 140 may include a first region 140a having a first modulus and a second region 140b having a second modulus smaller than the first modulus. For example, the modulus of the first area 141a may be 10 ⁶ to 10 ⁷ Pa, and the modulus of the second area 141b may be 10 ³ to 10 ⁵ Pa.

At this time, the width of the portion adjacent to the display panel 110 and the cover window 130 and the width of the center of the first region 140a of the first adhesive layer 140 may be different from each other. That is, the width of the portion adjacent to the display panel and the cover window of the first area 140a may be larger than the width of the center portion. And the first area 140a may have stronger adhesive force than the second area 140b.

A second adhesive layer 150 may be further included between the display panel 110 and the back plate 120, and the second adhesive layer may be made of the same material and have the same shape as the first adhesive layer.

The first area 140a may have an island pattern. For example, the island pattern can be circular or polygonal. Additionally, the first region 140a of the adhesive layer 140 may have a stripe pattern and may include both an island pattern and a stripe pattern.

Additionally, a functional layer may be further included between the display panel 110 and the cover window 130, and the functional layer may include a polarizer, a phase retardation plate, or a touch panel.

The adhesive layer 140 according to an embodiment of the present invention includes a first region 140a having a first modulus and a second region 140b having a second modulus smaller than the first modulus at the periphery of the first region. , the first area 140a and the second area 140b may be made of the same material. The first region may have a different width in the portion adjacent to the upper and lower surfaces and in a central portion. That is, the width of the portion adjacent to the upper and lower surfaces of the first region may be larger than that of other portions.

Although embodiments of the present specification have been described in detail with reference to the accompanying drawings, the present specification is not necessarily limited to these embodiments, and various modifications may be made without departing from the technical spirit thereof. Accordingly, the embodiments disclosed in this specification are not intended to limit the technical idea of the present invention, but rather to explain it, and the scope of the technical idea of the present invention is not limited by these embodiments. Each feature of the various embodiments of the present invention can be partially or entirely combined or combined with each other, and can be technically linked and driven in various ways by those skilled in the art, and each embodiment can be performed independently of each other or together in a related relationship. It may be implemented. The scope of protection of the present invention should be interpreted in accordance with the claims below, and all technical ideas within the equivalent scope should be construed as being included in the scope of rights of the present invention.

110: display panel
120: back plate
130: Cover window
140: first adhesive layer
140a: first area
140b: second area

Claims (15)

display panel;
a cover window located on top of the display panel;
a back plate located below the display panel;
a first adhesive layer interposed between the display panel and the cover window;
The first adhesive layer includes a first region having a first modulus and a second region having a second modulus smaller than the first modulus,
A foldable display device in which the width of the first area becomes smaller from the portion adjacent to the display panel toward the center, and the width of the first area becomes smaller from the portion adjacent to the cover window toward the center.
delete delete According to claim 1,
A foldable display device in which the adhesive force of the first area is greater than that of the second area.
According to claim 1,
The modulus of the first area is 10 ⁶ to 10 ⁷ Pa, and the modulus of the second area is 10 ³ to 10 ⁵ Pa.
According to claim 1,
Further comprising a second adhesive layer between the display panel and the back plate,
The second adhesive layer is a foldable display device having the same material and shape as the first adhesive layer.
In any one of paragraphs 1, 4 and 5
The first area is a foldable display device in an island pattern.
According to clause 7,
A foldable display device in which the island pattern is circular or polygonal.
According to any one of paragraphs 1, 4, and 5,
A foldable display device in which the first area is a stripe pattern.
According to any one of paragraphs 1, 4, and 5,
The first area is a foldable display device including both an island pattern and a stripe pattern.
According to claim 1,
A foldable display device further comprising a functional layer between the display panel and the cover window.
According to claim 11,
The functional layer is a foldable display device including a polarizer, a phase retardation plate, or a touch panel.
a first region having a first modulus; and
A second region having a second modulus smaller than the first modulus is included at the periphery of the first region,
The first area and the second area are different areas in a single layer,
The width of the first region becomes smaller from the upper surface of the upper limb adhesive layer to the center, and becomes smaller from the lower surface of the adhesive layer to the center,
The first region and the second region are made of the same material.
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