KR102409701B1 - Foldable display device - Google Patents

Abstract

The present invention relates to a foldable display, and more particularly, to a foldable display with improved durability.
A feature of the present invention is that the cover window, the OLED panel, and the back plate are laminated to have a concave curved shape with respect to the front, and the side surfaces of the cover window, the display panel and the back plate and the back surface of the back plate are laminated from the upper surface of both edges of the cover window. Positioning the elastic band so that it wraps.
In this way, stresses are compensated for in the fold region of the foldable display device over a second time, thereby further minimizing the accumulation of stresses in the fold region of the foldable display device.
Accordingly, durability of the foldable display device is improved, and plastic deformation of the foldable display device can be prevented from occurring, and restrictions in folding and unfolding of the foldable display device can be prevented. , it can also prevent appearance defects from occurring.
In addition, it is possible to prevent the display quality of the OLED panel 110 from being deteriorated.

Description

Foldable display device {Foldable display device}

The present invention relates to a foldable display, and more particularly, to a foldable display with improved durability.

In recent years, as society enters the information age in earnest, the field of display that processes and displays a large amount of information has developed rapidly, and in response to this, various various flat display devices have been developed. Be in the spotlight.

Specific examples of such a flat panel display device include a liquid crystal display device (LCD), a plasma display panel device (PDP), a field emission display device (FED), and an electroluminescence display. Electroluminescence Display device (ELD), organic light emitting diodes (OLED), etc. are mentioned. These flat panel display devices show excellent performance of thinness, light weight, and low power consumption, and thus the conventional cathode ray tube (CRT). : CRT) is rapidly being replaced.

On the other hand, since such a flat panel display device uses a glass substrate to withstand high heat generated during the manufacturing process, there is a limit in imparting light weight, thinness and flexibility.

Therefore, a flexible display device manufactured to maintain display performance even when bent like paper by using a flexible material such as plastic instead of the existing inflexible glass substrate is rapidly emerging as a next-generation flat panel display device.

The flexible display uses a plastic thin film transistor substrate rather than glass, so it is highly durable, unbreakable, bendable, bendable, rollable, and foldable. It can be classified as a foldable display device, and such a flexible display device has advantages of space utilization, interior design, and design, and can have various application fields.

In particular, recently, research on a foldable display device that can be carried in a folded state and display an image in an unfolded state has been actively conducted in order to realize a large area with ultra-thin, lightweight, and miniaturization.

The foldable display device may be applied to various fields such as a TV and a monitor, as well as a mobile device such as a mobile phone, an ultra mobile PC, an e-book, and an electronic newspaper.

Such a foldable display includes a display panel for realizing a large image, a back plate positioned below the display panel to support the display panel, and a cover window positioned in front of the display panel to protect the display panel. (cover window).

On the other hand, since the foldable display device must be foldable and unfoldable, both the back plate and the cover window, including the display panel, are made in the form of a very thin film. stress) and tensile stress are accumulated.

Stresses accumulated in the folded region remain accumulated in the folded region even when the foldable display device is unfolded, causing plastic deformation of the foldable display device itself, as shown in FIGS. 1A and 1B .

This imposes restrictions on folding and unfolding of the foldable display device, causing poor appearance, and eventually lowering the display quality of the display panel.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a first object of the present invention is to provide a foldable display device having no limitation in folding and unfolding and having improved durability.

Through this, it is a second object to prevent the display quality of the display panel from being deteriorated.

In order to achieve the object as described above, the present invention is a foldable including an elastic band attached to and fixed to the upper surface of both edges of a cover window, and an elastic band surrounding the cover window, the display panel, the side surfaces of the back plate, and the rear surface of the back plate. A display device is provided.

Through the present invention, stresses in the folded area of the foldable display are compensated for two times, so that the accumulation of stresses in the folded area of the foldable display can be further minimized, so that the durability of the foldable display is itself , it is possible to prevent plastic deformation of the foldable display device from occurring.

In addition, it is possible to prevent restrictions in folding and unfolding of the foldable display device, and also to prevent appearance defects.

As described above, according to the present invention, the cover window, the OLED panel, and the back plate are laminated to have a concave curved shape with respect to the front, and the side surfaces of the cover window, the display panel and the back plate are formed from the upper surface of both edges of the cover window. By locating the elastic band so as to cover the back surface of the foldable display device, stresses in the folded region of the foldable display are compensated for the second time, thereby minimizing the accumulation of stresses in the folded region of the foldable display. .

Through this, the durability of the foldable display device is improved, and it is possible to prevent plastic deformation of the foldable display device from occurring. Also, it is possible to prevent the occurrence of restrictions in folding and unfolding of the foldable display device. There is an effect that can prevent, and also has an effect of preventing the occurrence of appearance defects.

1A to 1B are views showing a plastic deformation problem of a back plate.
2 is a schematic diagram schematically illustrating a foldable display device according to an embodiment of the present invention;
3 is a cross-sectional view schematically illustrating the display panel of FIG. 2 ;
4A to 4D are cross-sectional views schematically illustrating a part of a manufacturing process of a foldable display device according to an embodiment of the present invention;
5 is a diagram schematically illustrating a folded state of a foldable display device;
6A to 6D are simulation results of measuring plastic deformation of a foldable display device.
7A to 7C are perspective views schematically showing the configuration of various elastic bands according to an embodiment of the present invention.

The present invention provides a display panel on which an image is implemented; a cover window positioned in front of the display panel; a back plate positioned at the rear of the display panel; Provided is a foldable display including elastic bands attached to and fixed to upper surfaces of both edges of the cover window, the elastic bands surrounding the cover window, the display panel, side surfaces of the back plate, and a rear surface of the back plate.

In this case, the original length of the elastic band is the length of the rear surface of the back plate, the sum of the thicknesses of the cover window, the display panel, and the side surfaces of the back plate, and the upper surface of the cover window at both ends of the elastic band. Corresponding to the length to be fixed to, the elastic band is not fixed to the side surface of the cover window, the side surface of the OLED panel, and the side and rear surfaces of the back plate.

In this case, the width of the elastic band is equal to the length of the side surfaces of the cover window, the OLED panel, and the back plate, and the width of the elastic band is compared to the length of the side surfaces of the cover window, the OLED panel, and the back plate. narrow.

In addition, the elastic band is provided in plurality, and the elastic band is stretched by a primary elastic force to both edges of the display panel having a concavely curved shape, the cover window and the back plate in the longitudinal direction to generate a force. In addition, the display panel, the cover window, and the back plate have a flat state.

In this case, when the display panel, the cover window, and the back plate are folded through the folded region, the elastic band is applied to the second elastic force at both edges of the display panel, the cover window, and the back plate in the longitudinal direction. A set frame is positioned on the rear surface of the back plate, the set frame is provided with a fixing part capable of maintaining the folding of the foldable display device, and the fixing force of the fixing part is the secondary elastic force larger than

And, it has an elastic modulus of 1 to 50 MPa of the elastic band.

In addition, the present invention comprises the steps of sequentially positioning a back plate, an OLED panel, and a cover window on a jig whose one surface is concave toward the front; Lamination is performed by applying pressure to the cover window, the OLED panel, and the cover window through a jig ball from the top of the cover window, and the cover window and the OLED panel are separated from the front in which the image is realized. modularizing the back plate to have a concavely curved shape; The cover window, the OLED panel, and the back plate having the concavely curved shape are attached to and fixed to the upper surfaces of both edges of the cover window, the side surfaces of the cover window, the display panel, and the back plate and the attaching an elastic band surrounding the back surface of the back plate; The display panel having the concavely curved shape is stretched to both edges in the longitudinal direction of the cover window and the back plate by the primary elastic force of the elastic band to apply a force, the display panel and the cover window and forming the back plate to be flat.

Here, when the display panel, the cover window, and the back plate are folded, the elastic band is stretched to both edges of the display panel, the cover window and the back plate in the longitudinal direction by a secondary elastic force. will be applied

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

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

As shown, the foldable display 100 protects the display panel 110 for realizing a large image, a back plate 120 supporting the display panel 110 , and the display panel 110 . Includes a cover window (cover window: 130) for the.

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

Here, the display panel 110 includes a liquid crystal display device (LCD), a plasma display panel device (PDP), a field emission display device (FED), an electroluminescence display device ( Electroluminescence Display device: ELD) and Organic Light Emitting Diodes (OLED) can be made, and it is better to use OLED, which is a representative of a flexible display device that can maintain display performance even when bent like paper. desirable.

OLED is a self-luminous device, and since it does not require a backlight used in a liquid crystal display, which is a non-light-emitting device, it can be lightweight and thin.

In addition, the viewing angle and contrast ratio are superior to those of the liquid crystal display device, and it is advantageous in terms of power consumption, direct current low voltage driving is possible, the response speed is fast, and the internal component is solid, so it is strong against external impact, and the temperature range is wide. It has advantages.

In particular, since the manufacturing process is simple, there is an advantage in that the production cost can be greatly reduced compared to the conventional liquid crystal display device.

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

Here, with reference to FIG. 3, the display panel 110 (hereinafter referred to as an OLED panel) made of OLED will be described in detail.

A semiconductor layer 104 is formed in the pixel region P on the substrate 101. The semiconductor layer 104 is made of silicon, and the central portion thereof is an active region 104a constituting a channel and a high concentration on both sides of the active region 104a. It is composed of source and drain regions 104b and 104c doped with impurities.

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

On the upper portion of the gate insulating layer 105 , a gate electrode 107 corresponding to the active region 104a of the semiconductor layer 104 and a gate wiring extending in one direction (not shown) are formed.

In addition, a first interlayer insulating film 106a is formed on the entire upper surface of the gate electrode 107 and the gate wiring (not shown). At this time, the first interlayer insulating film 106a and the gate insulating film 105 below it are formed in the active region ( 104a) and first and second semiconductor layer contact holes 109 exposing the source and drain regions 104b and 104c located on both side surfaces, respectively.

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

A second interlayer having a drain contact hole 112 exposing the drain electrode 108b over the source and drain electrodes 108a and 108b and the first interlayer insulating film 106a exposed between the two electrodes 108a and 108b. An insulating film 106b is formed.

At this time, the semiconductor layer 104 including the source and drain electrodes 108a and 108b and the source and drain regions 104b and 104c in contact with the electrodes 108a and 108b, and the gate insulating film formed on the semiconductor layer 104 . 105 and the gate electrode 107 form a driving thin film transistor DTr.

Meanwhile, although not shown in the drawing, a data line (not shown) that crosses the gate line (not shown) and defines the pixel region P is formed. In addition, 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 addition, as for the switching thin film transistor (not shown) and the driving thin film transistor (DTr), the co-planar type in which the semiconductor layer 104 is made of a polysilicon semiconductor layer is shown as an example, and as a modification thereof, pure and a bottom gate type made of impurity amorphous silicon.

In addition, in the region for displaying an image substantially above the second interlayer insulating film 106b, for example, a material having a relatively high work function value is used as a component constituting the light emitting diode E and forms an anode. One electrode 111 is formed.

The first electrode 111 is connected to the drain electrode 108b of the driving thin film transistor DTr,

The first electrode 111 is formed for each pixel region P, and a bank 119 is positioned between the first electrodes 111 formed for each pixel region P.

That is, the first electrode 111 is formed in a structure in which each pixel area P is separated by using the bank 119 as a boundary for each pixel area P. As shown in FIG.

In addition, an organic light emitting layer 113 is formed on the first electrode 111 .

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

The 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 for each pixel area (P). (B) Separate organic materials 113a, 113b, and 113c that emit color are patterned and used.

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

In this case, the second electrode 115 has a double-layer structure and includes a translucent metal film formed by thinly depositing a metal material having a low work function. In this case, 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 light emitting layer 113 is driven in a top emission type that is emitted toward the second electrode 115 .

Alternatively, since the second electrode 115 is made of an opaque metal film, the light emitted from the organic light emitting layer 113 may be driven in a bottom emission type that is 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 includes holes injected from the first electrode 111 and the second electrode 115 . Electrons provided from the electrons are transported to the organic light emitting layer 113 to form excitons, and when these excitons are transitioned from an excited state to a ground state, light is generated and emitted in the form of visible light.

At this time, since the emitted light passes through the transparent second electrode 115 or the first electrode 111 to the outside, the OLED panel 110 realizes 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 is used by laminating at least two inorganic protective films 102a in order to prevent external oxygen and moisture from penetrating into the OLED panel 110, in this case, between the two inorganic protective films 102a. Preferably, an organic protective film 102b for supplementing the impact resistance of the inorganic protective film 102a is interposed.

On the other hand, the substrate 101 may be made of thin polyimide to have flexible properties. The substrate 101 made of such thin polyimide is not suitable for the process of forming components such as thin film transistors (DTr). Therefore, in a state where a substrate made of polyimide is attached to a carrier substrate such as a glass substrate, a process of forming a component such as a thin film transistor (DTr) is performed. Thereafter, by separating the carrier substrate and the substrate made of polyimide, the OLED panel 110 can be obtained.

This OLED panel 110 is integrally modularized through the cover window 130 and the back plate 120, and a cover window that can protect the OLED panel 110 in front of the OLED panel 110 on which an image is realized. 130 is attached through the first optical adhesive layer 140 , and a back plate 120 for supporting the OLED panel 110 is attached to the rear surface of the OLED panel 110 through the second optical adhesive layer 150 . do.

Here, the first and second optical adhesive layers 140 and 150 are formed of OCA (Optical Cleared Adhesive).

The cover window 130 protects the OLED panel 110 from external impact, and transmits the light emitted from the OLED panel 110 so that the image displayed on the OLED panel 110 is viewed from the outside.

The cover window 130 has impact resistance and light transmittance, including polymethylmethacrylate (PMMA), polycarbonate (PC), cycloolefin polymer (COP), polyethylene terephthalate (polyethylene). terephthalate, PET), PI (Polyimide), and PA (Polyaramid).

Since the substrate 101 of the OLED panel 110 is too thin, the back plate 120 is attached to the back surface of the OLED panel 110 to support the OLED panel 110. A metal material such as stainless steel (SUS) or Polymethyl methacrylate (PMMA), polycarbonate (PC), polyvinylalcohol (PVA), acrylonitrile-butadiene-styrene (ABS), polyethylene It may be made of a polymer such as polyethylene terephthalate (PET).

Here, in the foldable display device 100 according to the embodiment of the present invention, in the process of modularizing the cover window 130 , the back plate 120 , and the OLED panel 110 , the image of the OLED panel 110 is displayed. It has a concave curved shape based on the implemented front.

In addition, an elastomer band 200 is positioned outside the foldable display device 100 , and both ends of the elastic band 200 are connected to both edges perpendicular to the longitudinal direction of the foldable display device 100 . Accordingly, a constant force is applied to the outside in the longitudinal direction of the foldable display 100 having a concavely bent shape.

Through this, when the foldable display 100 according to an embodiment of the present invention is folded, stresses accumulated in the folded region forming a curved surface are compensated, and thus stresses can be prevented from accumulating in the folded region.

Accordingly, durability of the foldable display device 100 is improved, and plastic deformation of the foldable display device 100 can be prevented from occurring. Therefore, it is possible to prevent the occurrence of restrictions and also to prevent appearance defects.

In addition, it is possible to prevent the display quality of the OLED panel 110 from being deteriorated.

This will be described in more detail with reference to FIGS. 4 to 5 .

4A to 4D are cross-sectional views schematically illustrating a part of a manufacturing process of a foldable display device according to an embodiment of the present invention, and FIG. 5 is a diagram schematically illustrating a folded state of the foldable display device.

As shown, the foldable display device (100 in FIG. 2 ) including a cover window 130 , an OLED panel 110 , and a back plate 120 is a cover window 130 in front of the OLED panel 110 . After positioning the back plate 120 on the back side of the OLED panel 110, the first and second optical adhesives (Fig. 2) between the cover window 130, the OLED panel 110, and the back plate 120, respectively. 140, 150) is applied and then laminated to form an integral module.

Here, in the process of laminating the cover window 130, the OLED panel 110, and the back plate 120, the cover window 130, the OLED panel 110, and the back plate 120 are placed on a jig (jig: 310). After positioning in the jig ball (jig ball: 320) through the cover window 130, the OLED panel 110, and the back plate 120 are laminated while applying a constant pressure, at this time the jig 310 is the cover window 130 ), the OLED panel 110 , and the back plate 120 are positioned on one surface to be concave toward the front.

Accordingly, as shown in FIG. 4A, the back plate 120, the second optical adhesive (150 in FIG. 2), the OLED panel 110, and the first optical adhesive (FIG. 140) of 2) and the cover window 130 are sequentially positioned, and then, while applying pressure through the jig ball 320 from the top of the cover window 130, lamination is performed as shown in FIG. 4B.

After that, as shown in FIG. 4c, when the jig 310 and the jig ball 320 are removed, the cover window 130, the OLED panel 110, and the back plate 120 are integrally modularized, and the OLED panel 110. It has a concave curved shape based on the front in which the image of is realized.

Next, as shown in FIG. 4D , an elastic band 200 formed of a high elastic rubber band or a rubber band is attached to the outside of the foldable display device 100 in FIG. 2 having a concave bending shape.

Both ends of the elastic band 200 are attached and fixed to a portion of the upper surface of both edges perpendicular to the longitudinal direction of the cover window 130 , and the side surfaces of the cover window 130 and the OLED panel 110 and the back plate 120 . It is formed to cover the rear surface of the back plate 120 and the back plate 120 .

The elastic band 200 is attached and fixed only to the upper surface of both edges of the cover window 130 , and is not attached and fixed to the OLED panel 110 and the back plate 120 , so the elastic band 200 is a foldable display. As the device ( 100 in FIG. 2 ) is folded and unfolded, the length is stretched and contracted.

The length of the elastic band 200 in its original state is the sum of the length in the longitudinal direction of the back plate 120 and the thickness of the side surfaces of the cover window 130 and the OLED panel 110 and the back plate 120, and the elastic body. It is preferable to make it correspond to the length for being fixed to a part of the upper surface of the cover window 130 of both ends of the band 200.

In addition, the elastic band 200 preferably has an elastic modulus of 1 to 50 MPa, and the elastic modulus can be freely set within the above range according to the width and thickness of the elastic band 200 .

When the elastic modulus value of the elastic band 200 is less than 1 MPa, the elastic band 200 is easily stretched and the force pulling the cover window 130 does not act. Conversely, when the elastic modulus value is greater than 50 MPa, the elastic band Since the elastic force of 200 is very strong, when the foldable display device ( 100 in FIG. 2 ) is folded, a large force by the elastic band 200 is required. That is, when the elastic modulus is large, the folding and unfolding of the foldable display device ( 100 in FIG. 2 ) are restricted.

By attaching and fixing the elastic band 200 having these characteristics to only the upper surfaces of both edges of the cover window 130, the modularized cover window 130 and the OLED panel 110 and the back plate 120 to have a concave bending shape. ) receives a force outward in the longitudinal direction by the elastic force of the elastic band 200 to maintain a flat, flat state.

At this time, the cover window 130 of the concavely curved shape, the OLED panel 110, and the back plate 120 are the cover window 130 of the foldable display device (100 in FIG. 2) by the force of the elastic band 200. A tensile stress is applied to the furnace, and a compressive stress is applied to the back plate 120 to maintain a flat state.

Therefore, when the foldable display device (100 in FIG. 2) is folded and compressive stress is applied to the cover window 130, the compressive stress applied to the cover window 130 is concavely bent due to the cover window 130. Compensation is primarily made with the tensile stress acting on the will achieve

In this way, it is possible to minimize the accumulation of stresses in the folded region of the foldable display device ( 100 of FIG. 2 ).

In addition, in the foldable display device ( 100 in FIG. 2 ) according to the embodiment of the present invention, the stresses in the folded region are compensated for secondary stresses by the elastic band 200 itself, through which the foldable display device ( 100 in FIG. 2 ) ) to minimize the accumulation of stresses in the folded region.

That is, when the foldable display device ( 100 in FIG. 2 ) is folded as shown in FIG. 5 , the rear longitudinal direction of the back plate 120 , the cover window 130 , the OLED panel 110 , and the back plate 120 . ) of the elastic band 200 corresponding to the length of the sum of the thicknesses of the sides and the length for being fixed to a portion of the upper surface of the cover window 130 at both ends of the elastic band 200, the elastic band 200 itself by the elastic force It will remain in a stretched state.

That is, when the foldable display device ( 100 in FIG. 2 ) is unfolded, the elastic band 200 maintains a tensioned state by the primary elastic force. By applying a force to the outside in the longitudinal direction of the cover window 130, the OLED panel 110, and the back plate 120 of the concave bending shape with restoring force, the foldable display device (100 in FIG. 2) is flat and flat. status will be maintained.

In the process of maintaining a flat state by the elastic band 200 in the cover window 130 and the back plate 120, which were integrated in a concave bending shape, tensile stress and compressive stress transmitted by the elastic band 200, respectively, are In this case, when the foldable display device ( 100 in FIG. 2 ) is folded, the compressive stress applied to the cover window 130 is compensated primarily through the tensile stress due to the concave bending shape of the cover window 130 . In addition, the tensile stress applied to the back plate 120 is primarily compensated for through the compressive stress due to the concave bending shape of the back plate 120 . Accordingly, it is possible to minimize the accumulation of stresses in the folded region of the foldable display device ( 100 of FIG. 2 ).

And, when the foldable display device (100 in FIG. 2) is folded, the elastic band 200 is located at the outermost part of the foldable display device (100 in FIG. 2), so that the secondary elastic force is larger than the primary elastic force. It is stretched by an elastic force. Accordingly, the elastic band 200 generates a restoring force to restore it to its original state due to the secondary elastic force. The restoring force of the elastic band 200 acts toward the center from both ends connected to both edges of the cover window 130 . Thus, the restoring force of the elastic band 200 connected to both edges of the cover window 130 acts to the outside of the foldable display device (100 in FIG. 2) and is transmitted to the cover window 130, and the cover window ( The restoring force of the elastic band 200 transferred to 130 acts opposite to the compressive stress accumulated in the folding area of the cover window 130, so that the compressive stress in the folding area of the cover window 130 is compensated secondarily. do.

In addition, since the restoring force of the elastic band 200 acts from both ends toward the center, the restoring force of the elastic band 200 corresponding to the folded region of the foldable display device ( 100 in FIG. 2 ) is the back plate 120 . Since it acts opposite to the tensile stress accumulated in the folded region, the tensile stress in the folded region of the back plate 120 is compensated secondarily.

Accordingly, when the foldable display device 100 in FIG. 2 is folded according to an embodiment of the present invention, stresses are compensated for in the folded region over the second time, so that the foldable display device 100 in FIG. 2 is folded into the folded region. The accumulation of stresses is further minimized.

Through this, the durability of the foldable display device ( 100 in FIG. 2 ) is improved, and plastic deformation of the foldable display device ( 100 in FIG. 2 ) can be prevented from occurring, and also, the foldable display device ( It is possible to prevent a limitation in folding and unfolding of 100) of FIG. 2 , and also to prevent an appearance defect from occurring. In addition, it is possible to prevent the display quality of the OLED panel 110 from being deteriorated.

6A to 6D are simulation results of measuring plastic deformation of a foldable display device.

Prior to the description, the plastic deformation measurement of the foldable display device ( 100 in FIG. 2 ) was measured after performing the folding and unfolding tests of the foldable display device ( 100 in FIG. 2 ) of 100 to 10000.

6A is a simulation result of measuring plastic deformation of a general foldable display device, and it can be confirmed that plastic deformation has occurred in a typical foldable display device corresponding to a folded region, which is the central portion.

Here, the waviness value for the plastic deformation of the general foldable display of FIG. 6A is 0.32 mm, where the waviness value is between the concave part having the lowest height from the convex part protruding the highest from the measurement surface. It is the average value of the amplitude measurements.

It can be seen that the plastic deformation generated in such a general foldable display is visually displayed with reference to FIG. 6B .

On the other hand, it can be seen that the foldable display device 100 in FIG. 2 according to the embodiment of the present invention of FIG. 6C has less plastic deformation than the general foldable display device of FIG. 6A .

This can be confirmed more clearly through the surface waveform value. The surface waveform value for plastic deformation of the foldable display device 100 in FIG. 2 according to the embodiment of the present invention of FIG. 6C is 0.29 mm, which is 0.3mm lower than the display device.

Also, referring to FIG. 6D , it can be seen that the plastic deformation generated in the foldable display device 100 ( 100 in FIG. 2 ) according to the embodiment of the present invention is visually insignificant compared to that of FIG. 6A .

This is because the foldable display device ( 100 in FIG. 2 ) according to an embodiment of the present invention compensates for stresses in the folded area of the foldable display device ( 100 in FIG. 2 ) over the second time, and thus the foldable display device ( FIG. 2 ) It means that the accumulation of stresses in the fold region of 100) was more minimized.

Accordingly, the durability of the foldable display device ( 100 in FIG. 2 ) is improved, and plastic deformation of the foldable display device ( 100 in FIG. 2 ) can be prevented from occurring. 2 of 100), it is possible to prevent restrictions in folding and unfolding, and also to prevent appearance defects.

In addition, it is possible to prevent the display quality of the OLED panel 110 from being deteriorated.

7A to 7C are perspective views schematically illustrating the configuration of various elastic bands according to an embodiment of the present invention.

As shown, when the cover window 130, the OLED panel 110, and the back plate 120 are integrally modularized through the first and second optical adhesives (140, 150 in FIG. 1), the back plate 120 The elastic band 200 is positioned on the rear surface of the

Both ends of the elastic band 200 are attached to and fixed to the upper surfaces of both edges in the longitudinal direction of the cover window 130. At this time, as shown in FIG. 7a, the elastic band 200 is a cover window 130 and an OLED panel (110) and is formed to have the same width as the length of the side perpendicular to the longitudinal direction of the back plate 120, the cover window 130, the OLED panel 110, and the side of the back plate 120 and the back plate 120 ) may be formed to cover all of the rear surface.

In addition, as shown in FIG. 7B , the width of the elastic band 200 may be formed smaller than the length of the side surface perpendicular to the longitudinal direction of the cover window 130 , the OLED panel 110 , and the back plate 120 . have.

In addition, as shown in FIG. 7c , a plurality of elastic bands 200 formed smaller than the length of the side surface perpendicular to the longitudinal direction of the cover window 130 , the OLED panel 110 and the back plate 120 may be provided. may be

As described above, in the foldable display 100 according to the embodiment of the present invention, the cover window 130 , the OLED panel 110 , and the back plate 120 are laminated to have a concave curved shape with respect to the front. , By positioning the elastic band 200 from the upper surface of both edges of the cover window 130 to surround the side surfaces of the cover window 130 and the OLED panel 110 and the back plate 120 and the rear surface of the back plate 120, By compensating the stresses in the fold area of the foldable display device 100 over a second time, it is possible to further minimize the accumulation of stresses in the fold area of the foldable display device 100 .

Accordingly, the durability of the foldable display device 100 is improved, and plastic deformation of the foldable display device 100 can be prevented from occurring, and also when the foldable display device 100 is folded and unfolded. Therefore, it is possible to prevent the occurrence of restrictions and also to prevent appearance defects.

In addition, it is possible to prevent the display quality of the OLED panel 110 from being deteriorated.

On the other hand, in the foldable display device 100 according to the embodiment of the present invention including the elastic band 200 , a set frame (not shown) may be assembled and fastened to the outside of the back plate 120 , such a set frame It is possible to control the elastic force of the elastic band 200 through (not shown).

That is, the set frame (not shown) is configured so that the foldable display device 100 can be easily unfolded and folded. In particular, when the foldable display device 100 is folded, the set frame (not shown) is the foldable display device 100 . ) to include a fixing part (not shown) such as a fastening hook so as to stably maintain the folding.

At this time, in the foldable display device 100 according to the embodiment of the present invention, when the foldable display device 100 is folded, the restoring force due to the secondary elastic force of the elastic band 200 is the cover window 130 and the back plate ( While secondary compensating for the accumulation of stresses in the folded region of the 120 , the restoring force itself is greatly formed, so that the force may be applied to both sides in the longitudinal direction of the foldable display 100 .

Accordingly, undesired unfolding of the foldable display 100 may occur. In this case, the force applied to both sides in the longitudinal direction of the foldable display 100 is applied to the back plate 120 of the foldable display 100 . The foldable display device 100 by the fixing part (not shown) of the set frame (not shown) provided outside of Through this, unfolding by the elastic band 200 of the foldable display device 100 can be prevented from occurring.

The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

100: foldable display device
110: display panel (OLED panel)
120: back plate
130: cover window
140, 150: first and second optical adhesives
200: elastic band

Claims (13)

a display panel on which an image is implemented;
a cover window positioned in front of the display panel;
a back plate positioned at the rear of the display panel;
An elastic band attached to and fixed to the upper surface of both edges of the cover window, the elastic band surrounding the side surfaces of the cover window, the display panel, and the back plate and the rear surface of the back plate
including,
The elastic band is stretched by a primary elastic force to both edges in the longitudinal direction of the display panel having a concavely curved shape, and the cover window and the back plate, so as to apply a force to the display panel, the cover window and The back plate has a flat state.
foldable display.
The method of claim 1,
The length of the elastic band in its original state is the length of the rear longitudinal direction of the back plate, the sum of the thicknesses of the cover window, the display panel, and the side surfaces of the back plate, and both ends of the elastic band are fixed to the upper surface of the cover window. A foldable display device corresponding to the length to become.
The method of claim 1,
The elastic band is not fixed to a side surface of the cover window, a side surface of the display panel, and a side surface and a rear surface of the back plate.
The method of claim 1,
A width of the elastic band is the same as lengths of side surfaces of the cover window, the display panel, and the back plate.
The method of claim 1,
A width of the elastic band is narrower than lengths of side surfaces of the cover window, the display panel, and the back plate.
6. The method of claim 5,
The foldable display device is provided with a plurality of elastic bands.
delete The method of claim 1,
When the display panel, the cover window, and the back plate are folded through the folded region, the elastic band is stretched to both edges of the display panel, the cover window and the back plate in the longitudinal direction by a secondary elastic force. A foldable display that becomes and applies force.
9. The method of claim 8,
A set frame is positioned on the rear surface of the back plate, and the set frame is provided with a fixing part capable of maintaining the folding of the foldable display device, and the fixing force of the fixing part is greater than the secondary elastic force of the foldable display device. .
The method of claim 1,
A foldable display having an elastic modulus of 1 to 50 MPa of the elastic band.
Sequentially positioning a back plate, an OLED panel, and a cover window on a jig whose one surface is concave toward the front;
By applying pressure to the cover window, the OLED panel, and the cover window through a jig ball from the top of the cover window, lamination is performed, and the cover window and the OLED panel are formed with reference to the front in which the image is realized. modularizing the back plate to have a concavely curved shape;
The cover window, the OLED panel, and the back plate having the concave curved shape are attached and fixed to the upper surfaces of both edges of the cover window, and the side surfaces of the cover window, the OLED panel, and the back plate and the attaching an elastic band surrounding the back surface of the back plate;
The OLED panel having the concavely curved shape, the cover window and the back plate are stretched by the primary elastic force of the elastic band to both edges in the longitudinal direction to apply a force, the OLED panel and the cover window and forming the back plate to be flat.
A method of manufacturing a foldable display comprising a.
12. The method of claim 11,
When the OLED panel, the cover window, and the back plate are folded, the elastic band is stretched to both edges in the longitudinal direction of the OLED panel, the cover window and the back plate by a secondary elastic force to apply a force. A method of manufacturing a foldable display device.
9. The method of claim 8,
The secondary elastic force of the elastic band is greater than the primary elastic force of the elastic band
foldable display.

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