KR102588088B1 - Foldable display device - Google Patents

Abstract

The present invention relates to a foldable display device, and particularly to a foldable display device with improved impact resistance.
A feature of the present invention is that the modulus value of each component is alternately positioned between high and low, so that even if shock is applied from the outside, transmission to the touch panel or OLED panel can be minimized, and the shock is absorbed by the back of the back plate. By further positioning the film, damage to the touch panel or OLED panel due to external impact can be more effectively prevented.

Description

Foldable display device

The present invention relates to a foldable display device, and particularly to a foldable display device with improved impact resistance.

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).

Meanwhile, since a foldable display device must be capable of folding and unfolding, the display panel, the back plate, and the cover window are all made of a very thin film. The thin film form transmits most of the external impact vertically.

In other words, when an impact is applied to the cover window or back plate from the outside, the cover window and back plate are made of a thin film, so the impact applied from the outside is directly transmitted to the display panel located between the cover window and the back plate. .

This ultimately causes damage to the display panel and deteriorates the display quality of the display panel.

The present invention is intended to solve the above problems, and its first purpose is to provide a foldable display device with improved impact resistance.

Through this, the second purpose is to prevent the display quality from deteriorating.

In order to achieve the object as described above, the present invention includes a display panel on which an image is displayed, a cover window located in front of the display panel, a back plate located behind the display panel, and a lower part of the back plate. It includes a shock-absorbing film located in, wherein the shock-absorbing film includes a first and a second shock-absorbing layer, and the second shock-absorbing layer includes a soft layer corresponding to the folded area and a hard layer corresponding to the non-folded area. In addition, the first shock absorption layer and the soft layer provide a foldable display device in which the modulus value is lower than that of the hard layer.

At this time, the first shock-absorbing layer is made of a foam material, and the soft layer of the second shock-absorbing layer is made of polyurethane (PU), thermoplastic polyurethane (TPU), silicon (Si), It is made of one selected from polydimethylacrylamide (PDMA), and the hard layer is a metal material such as stainless steel (SUS), polymethyl methacrylate (PMMA), or polycarbonate (PC). , polyvinylalcohol (PVA), acrylonitrile-butadiene-styrene (ABS), and polyethylene terephthalate (PET), and the first shock absorbing layer is 100%. It has a thickness of ~300um, the soft layer has a thickness of 100~500um, and the hard layer has a thickness of 0.1~1mm.

In addition, the first shock absorbing layer has a modulus value of 10 ³ to 10 ⁴ Pa, and the soft layer of the second shock absorbing layer has a modulus value of 10 ³ to 10 ⁴ Pa, and the hard The layer has a modulus value of 5 to 8 GPa.

Here, a first optical adhesive layer is located between the cover window and the display panel, and a second optical adhesive layer is located between the display panel and the backplate, and the first and second optical adhesive layers are 10 ³ to 10 ⁴ It has a modulus value of Pa, and a third optical adhesive layer is located between the shock-absorbing film and the back plate, and the third optical adhesive layer has a modulus value of 10 ³ to 10 ⁴ Pa.

In addition, the first optical adhesive layer has a lower modulus value than the cover window and the display panel, and the second optical adhesive layer has a lower modulus value than the display panel and the backplate, A touch panel is positioned between the cover window and the display panel, and the first optical adhesive layer has a lower modulus value than the cover window and the touch panel.

In addition, the third optical adhesive layer has a lower modulus value than the backplate, and the first shock absorption layer and the second shock absorption layer are attached to each other through a fourth optical adhesive layer.

As described in detail above, according to the present invention, the modulus values of each component of the foldable display device are alternately positioned between high and low, thereby minimizing the transmission to the touch panel or OLED panel even when shock is applied from the outside. However, by placing the shock absorbing film on the back of the back plate, it is possible to more efficiently prevent damage to the touch panel or OLED panel from external shock.

1 is a schematic diagram schematically showing a foldable display device according to a first embodiment of the present invention.
Figure 2 is a cross-sectional view schematically showing the display panel of Figure 1.
Figure 3 is a schematic diagram schematically showing a foldable display device according to a second embodiment of the present invention.
Figure 4 is a ball-drop test graph of a foldable display device according to a second embodiment of the present invention.

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

FIG. 1 is a schematic diagram schematically showing a foldable display device according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view schematically showing the display panel of FIG. 1.

As shown, the foldable display device 100 largely includes a display panel 110 for displaying an image, a touch panel 120 forming a touch sensor (not shown), and a backplate supporting the display panel 110. (back plate: 130) and includes a cover window (cover window: 140) to protect the display panel (110).

At this time, if the direction in the drawing is defined for convenience of explanation, the back plate 130 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 140.

And, the touch panel 120 is located between the display panel 110 and the cover window 140.

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 an Electroluminescence Display device (ELD) or Organic Light Emitting Diodes (OLED). It is better to use OLED, a representative flexible display device that can maintain display performance even when bent like paper. desirable.

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 displays.

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.

In the first embodiment, the display panel 110 and the touch panel 120 are configured separately as an example, but in other embodiments, touch electrodes for touch detection are formed on the display panel so that the display panel functions as a touch panel. By doing so, the touch panel can be omitted.

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. 2.

A semiconductor layer 104 is formed in the pixel area (P) on the substrate 101. The semiconductor layer 104 is made of silicon, the central part of which is an active area 104a forming a channel, and the active area 104a on both sides of the active area 104a is highly concentrated. It consists of source and drain regions 104b and 104c doped with impurities.

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

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

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 area ( 104a) First and second semiconductor layer contact holes 109 are provided to expose source and drain regions 104b and 104c located on both sides, respectively.

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 ( Source and drain electrodes 108a and 108b are formed in contact with 104b and 104c, respectively.

And, a second interlayer having a drain contact hole 112 exposing the drain electrode 108b to the top of 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, a semiconductor layer 104 including source and drain electrodes 108a and 108b and source and drain regions 104b and 104c in contact with these electrodes 108a and 108b, and a 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 wire (not shown) is formed that intersects 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 addition, the switching thin film transistor (not shown) and the driving thin film transistor (DTr) are shown in the drawing as an example of a co-planar type in which the semiconductor layer 104 is made of a polysilicon semiconductor layer, and as a modified example thereof, a pure transistor is used. And it may be formed as a bottom gate type made of amorphous silicon with impurities.

In addition, in the area where the image is actually displayed above the second interlayer insulating film 106b, for example, a second interlayer insulating film 106b is made of a material with a relatively high work function value and is a component of the light emitting diode E that forms an anode. 1 Electrode 111 is formed.

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

This 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).

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 has a double-layer structure and 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 light emitting layer 113 is driven in a top emission type that is 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 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 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 excitons, and when these excitons transition 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 is used by stacking at least two inorganic protective films (102a) to prevent external oxygen and moisture from penetrating into the OLED panel 110. At this time, between the two inorganic protective films (102a) It is preferable that an organic protective film (102b) is interposed to supplement the impact resistance of the inorganic protective film (102a).

Meanwhile, the substrate 101 may be made of thin polyimide to have flexible properties, but the substrate 101 made of such thin polyimide is not suitable for the formation process of components such as thin film transistors (DTr). Therefore, the formation process of components such as thin film transistors (DTr) is performed with a substrate made of polyimide attached to a carrier substrate such as a glass substrate. Thereafter, the OLED panel 110 can be obtained by separating the carrier substrate and the substrate made of polyimide.

The touch panel 120 is located on top of the OLED panel 110, and the OLED panel 110 and the touch panel 120 are bonded to each other through an adhesive layer (not shown) of the touch panel 110.

Here, although not shown in detail, the touch panel 120 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. They are spaced apart and face each other.

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. .

The OLED panel 110 joined with the touch panel 120 is integrated into a module through the cover window 140 and the back plate 130, and the touch panel 120 is located in front of the OLED panel 110 where the image is displayed. and a cover window 140 capable of protecting the OLED panel 110 is attached through the first optical adhesive layer 150, and a back plate ( 130) is attached through the second optical adhesive layer 160.

Here, the first and second optical adhesive layers 150 and 160 are formed of OCA (Optical Cleared Adhesive), and the first and second optical adhesive layers 150 and 160 are formed to have a thickness of about 100 to about 300 μm. desirable.

If the first and second optical adhesive layers 150 and 160 have a thickness of about 100 um or less, the adhesive strength is weak, making it difficult to modularize the cover window 140, back plate 130, touch panel 120, and OLED panel 110. This is difficult, and if the first and second optical adhesive layers 150 and 160 have a thickness of about 300 um or more, it may cause a problem in that the folding of the foldable display device 100 becomes difficult.

The cover window 140 protects the OLED panel 110 and the touch panel 120 from external shock and transmits the light emitted from the OLED panel 110 so that the image displayed on the OLED panel 110 can be viewed from the outside. do.

This cover window 140 is made of polymethylmethacrylate (PMMA), polycarbonate (PC), cycloolefin polymer (COP), and polyethylene terephthalate (polyethylene), which have impact resistance and light transparency. It may be made of any one of terephthalate, PET), PI (Polyimide), and PA (Polyaramid).

Since the substrate 101 of the OLED panel 110 is too thin, the backplate 130 is attached to the back of the OLED panel 110 to support the OLED panel 110, and is made of 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 terephthalate (polyethylene terephthalate, PET).

Here, the characteristic configuration of the first embodiment of the present invention is that the first and second optical adhesive layers 150 and 160 are larger than the cover window 140, the touch panel 120, the OLED panel 110, and the back plate 130. It is characterized by having a small modulus value. In other words, the first and second optical adhesive layers 150 and 160 have lower stiffness than the cover window 140, the touch panel 120, the OLED panel 110, and the back plate 130.

For example, the cover window 140, the touch panel 120, and the OLED panel 110 have a modulus value of about 5 to 8 GPa, and the backplate 130 has a modulus value of about 8 to 10 GPa. The first and second optical adhesive layers 150 and 160 may have a modulus value lower than 10 ³ to 10 ⁴ Pa.

Through this, the foldable display device 100 according to the first embodiment of the present invention has the overall modulus values of each component alternately positioned between high and low.

That is, the cover window 140, the touch panel 120, the OLED panel 110, and the backplate 130, which are large components of the foldable display device 100, have a high modulus value, so the cover window 140 The first optical adhesive layer 150 between the and the touch panel 120 has a lower modulus value than the cover window 140 and the touch panel 120, and is located between the OLED panel 110 and the backplate 130. The second optical adhesive layer 160 also has a lower modulus value than the OLED panel 110 and the backplate 130.

In this way, by alternating the modulus values of each component of the foldable display device 100 to high and low, even if an impact is applied from the outside, the impact applied from the outside is transmitted to the cover of the foldable display device 100. It is minimized and transmitted to the touch panel 120 or OLED panel 110 located inside the window 140 and the back plate 130.

Accordingly, damage to the touch panel 120 or the OLED panel 110 due to external impact can be minimized.

This is due to the transmission characteristics of shock, and thin films such as the foldable display device 100 transmit shock mostly vertically rather than absorbing it (transmitting it horizontally). For example, shock is transmitted to the cover window 140 from the outside. When delivered, the impact transmitted to the cover window 140 is transmitted to the touch panel 120 or OLED panel 110 located at the bottom of the cover window 140.

Accordingly, damage to electrodes (not shown) of the touch sensor (not shown) of the touch panel 120 or elements of the OLED panel 110 is caused.

However, when the modulus value of each component of the foldable display device 100 is configured to alternate between high and low as in the first embodiment of the present invention, even if an impact is applied from the outside, the shock has a high modulus value and As it passes through low-level components, it is partially alleviated, making it possible to minimize transmission to the touch panel 120 or OLED panel 110.

In particular, the foldable display device 100 according to the first embodiment of the present invention alternates high and low modulus values of each component, that is, the first and second optical adhesive layers 150. , 160) and the cover window 140, touch panel 120, OLED panel 110, and back plate 130, the greater the difference between the modulus values, the more the touch panel 120 or OLED panel is damaged by shock applied from the outside. Damage of (110) can be further minimized.

[Table 1]

[Table 1] above is a table showing the results of a ball-drop test according to changes in the modulus value of the optical adhesive layers 150 and 160.

Prior to explanation, the ball drop test involves combining the upper and lower sets on the top and bottom of the foldable display device, respectively, and then dropping the ball while changing the height from the top of the foldable display device combined with the upper and lower sets. It is a test to check for damage to a foldable display device by lifting it up, and it can be interpreted that the higher the height at which damage begins, the better the foldable display device can withstand external shocks.

At this time, the lower set includes a folded region (FR in FIG. 3) and a non-folded region (NFR in FIG. 3). In the folded region (FR), the lower set contacts the foldable display device, and in the non-folded region (NFR) In , the lower set is spaced apart from the foldable display device to form a gap. For example, the gap between the lower set of the non-folded region (NFR) and the foldable display device may be about 1 mm.

In Table 1, Sample A represents the results of a ball drop test in the folded area (FR in FIG. 3) of a foldable display device in which the optical adhesive layers 150 and 160 have a modulus value of 2.2 * 10 ⁵ Pa, and Sample B represents the results of the ball drop test. It shows the results of a ball drop test in the folded area (FR in FIG. 3) of a foldable display device in which the optical adhesive layers 150 and 160 have a modulus value of 1.3 * 10 ³ Pa.

Here, the cover window 140, the touch panel 120, and the OLED panel 110 have a modulus value of about 5 to 8 GPa, and the backplate 130 has a modulus value of about 8 to 10 GPa.

Referring to [Table 1] above, Sample A shows that when the optical adhesive layers 150 and 160 have a modulus value of about 10 ⁵ Pa, the touch panel 120 or Damage to the OLED panel 110 begins to occur, but when the optical adhesive layers 150 and 160 have a modulus value of about 10 ³ Pa, the touch panel 120 is damaged when a ball is dropped from about 10 cm in a ball drop test. ) or it can be seen that damage to the OLED panel 110 is starting to occur.

Therefore, it can be confirmed that whether the touch panel 120 or the OLED panel 110 is damaged due to an external impact depends on the modulus value of the optical adhesive layers 150 and 160, and in particular, the optical adhesive layers 150 and 160 The modulus value of is formed to be about 10 ³ Pa, so that the moduli of the first and second optical adhesive layers 150 and 160, the cover window 140, the touch panel 120, the OLED panel 110, and the back plate 130 If the values are significantly different, the transmission of shock from the outside to the touch panel 120 or OLED panel 110 can be minimized compared to the case where the modulus value of the optical adhesive layers 150 and 160 is about 10 ⁵ Pa. You can check what you can.

Figure 3 is a schematic diagram schematically showing a foldable display device according to a second embodiment of the present invention.

Meanwhile, in order to avoid redundant description, the same parts that play the same role as in the description of the first embodiment described above will be assigned the same reference numerals, and only the characteristic contents to be described in the second embodiment will be examined.

As shown, the foldable display device 100 largely includes a display panel 110 for displaying an image, a touch panel 120 forming a touch sensor (not shown), and a backplate supporting the display panel 110. (back plate: 130) and includes a cover window (cover window: 140) to protect the display panel (110).

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 an Electroluminescence Display device (ELD) or Organic Light Emitting Diodes (OLED). It is better to use OLED, a representative flexible display device that can maintain display performance even when bent like paper. desirable.

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.

The display panel 110 (hereinafter referred to as OLED panel) made of such an OLED has a substrate (101 in FIG. 2) on which a driving thin-film transistor (DTr in FIG. 2) and a light emitting diode (E in FIG. 2) are formed and a protective film (in FIG. 2). It is encapsulated by 102).

In the second embodiment, the display panel 110 and the touch panel 120 are configured separately as an example, but in other embodiments, touch electrodes for touch detection are formed on the display panel so that the display panel functions as a touch panel. By doing so, the touch panel can be omitted.

Meanwhile, the substrate (101 in FIG. 2) may be made of thin polyimide to have flexible properties. The substrate (101 in FIG. 2) made of such thin polyimide can be used as a thin film transistor (DTr in FIG. 2). Since it is not suitable for the forming process of components, the forming process of components such as thin film transistors (DTr in FIG. 2) is performed with a substrate made of polyimide attached to a carrier substrate such as a glass substrate. Thereafter, the OLED panel 110 can be obtained by separating the carrier substrate and the substrate made of polyimide.

The touch panel 120 is located on the top of the OLED panel 110, and the OLED panel 110 and the touch panel 120 are bonded to each other through an adhesive layer (not shown) of the touch panel 120.

The touch panel 120 is made up of a first touch film (not shown) on which the first touch electrode 120 is formed and a second touch film (not shown) on which the second touch electrode (not shown) is formed, spaced apart from each other and facing each other.

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

The OLED panel 110 joined with the touch panel 120 is integrated into a module through the cover window 140 and the back plate 130, and the touch panel 120 is located in front of the OLED panel 110 where the image is displayed. and a cover window 140 capable of protecting the OLED panel 110 is attached through the first optical adhesive layer 150, and a back plate ( 130) is attached through the second optical adhesive layer 160.

Here, the first and second optical adhesive layers 150 and 160 are formed of OCA (Optical Cleared Adhesive), and the first and second optical adhesive layers 150 and 160 are formed to have a thickness of about 100 to about 300 μm. desirable.

If the first and second optical adhesive layers 150 and 160 have a thickness of about 100 um or less, the adhesive strength is weak, making it difficult to modularize the cover window 140, back plate 130, touch panel 120, and OLED panel 110. This is difficult, and if the first and second optical adhesive layers 150 and 160 have a thickness of about 300 um or more, it may cause a problem in that the folding of the foldable display device 100 becomes difficult.

The cover window 140 protects the OLED panel 110 and the touch panel 120 from external shock and transmits the light emitted from the OLED panel 110 so that the image displayed on the OLED panel 110 can be viewed from the outside. do.

This cover window 140 is made of polymethylmethacrylate (PMMA), polycarbonate (PC), cycloolefin polymer (COP), and polyethylene terephthalate (polyethylene), which have impact resistance and light transparency. It may be made of any one of terephthalate, PET), PI (Polyimide), and PA (Polyaramid).

Since the substrate (101 in FIG. 2) of the OLED panel 110 is too thin, the backplate 130 is attached to the back of the OLED panel 110 to support the OLED panel 110, and is made of stainless steel (SUS). Metallic materials or polymethyl methacrylate (PMMA), polycarbonate (PC), polyvinylalcohol (PVA), acrylonitrile-butadiene-styrene (ABS) ), and may be made of polymers such as polyethylene terephthalate (PET).

Here, the first and second optical adhesive layers 150 and 160 are characterized by having a smaller modulus value than the cover window 140, the touch panel 120, the OLED panel 110, and the back plate 130. do. In other words, the first and second optical adhesive layers 150 and 160 have lower stiffness than the cover window 140, the touch panel 120, the OLED panel 110, and the back plate 130.

For example, the cover window 140, the touch panel 120, and the OLED panel 110 have a modulus value of about 5 to 8 GPa, and the backplate 130 has a modulus value of about 8 to 10 GPa. The first and second optical adhesive layers 150 and 160 may have a modulus value lower than 10 ³ to 10 ⁴ Pa.

Through this, the foldable display device 100 according to the second embodiment of the present invention has the overall modulus values of each component alternately positioned between high and low.

That is, the cover window 140, the touch panel 120, the OLED panel 110, and the backplate 130, which are large components of the foldable display device 100, have a high modulus value, so the cover window 140 The first optical adhesive layer 150 between the and the touch panel 120 has a lower modulus value than the cover window 140 and the touch panel 120, and is located between the OLED panel 110 and the backplate 130. The second optical adhesive layer 160 also has a lower modulus value than the OLED panel 110 and the backplate 130.

In this way, by alternating the modulus values of each component of the foldable display device 100 to high and low, even if an impact is applied from the outside, the impact applied from the outside is transmitted to the cover of the foldable display device 100. It is minimized and transmitted to the touch panel 120 or OLED panel 110 located inside the window 140 and the back plate 130.

Accordingly, damage to the touch panel 120 or the OLED panel 110 due to external impact can be minimized.

This is due to the transmission characteristics of shock, and thin films such as the foldable display device 100 transmit shock mostly vertically rather than absorbing it (transmitting it horizontally). For example, shock is transmitted to the cover window 140 from the outside. When delivered, the impact transmitted to the cover window 140 is transmitted to the touch panel 120 or OLED panel 110 located at the bottom of the cover window 140.

Accordingly, damage to electrodes (not shown) of the touch sensor (not shown) of the touch panel 120 or elements of the OLED panel 110 is caused.

However, when the modulus value of each component of the foldable display device 100 is configured to alternate between high and low as in the second embodiment of the present invention, even if an impact is applied from the outside, the impact causes the modulus value to be high and As it passes through lower components, it is partially alleviated, making it possible to minimize transmission to the touch panel 120 or OLED panel 110.

In particular, the foldable display device 100 according to the second embodiment of the present invention is characterized in that the shock absorbing film 170 is further positioned on the rear side of the back plate 130.

At this time, the shock-absorbing film 170 is attached to the back of the back plate 130 through the third optical adhesive layer 180. At this time, the third optical adhesive layer 180 is also attached to the cover window 140, the touch panel 120, and It has a lower modulus value than the OLED panel 110 and the backplate 130. For example, the cover window 140, the touch panel 120, and the OLED panel 110 have a modulus value of about 5 to 8 GPa, The backplate 130 has a modulus value of about 8 to 10 GPa, and in this case, the third optical adhesive layer 180 may have a modulus value lower than 10 ³ to 10 ⁴ Pa.

This is to place a component with a low modulus value below the backplate 130 with a high modulus value, thereby preventing shock applied from the outside from being transmitted to the touch panel 120 or the OLED panel 110. It can be minimized.

Here, the third optical adhesive layer 180 is also formed of OCA (Optical Cleared Adhesive), and is preferably formed to have a thickness of about 100 to about 300 μm.

The shock-absorbing film 170 includes first and second shock-absorbing layers 171 and 173. The first shock-absorbing layer 171 is made of a foam material, and the second shock-absorbing layer 173 has a folded area. It is divided into a (FR) and a non-folded region (NFR), and has a double structure in which the soft layer (173a) is located in correspondence with the folded region (FR), and the hard layer (173b) is located in response to the non-folded region (NFR). .

At this time, the soft layer 173a may be positioned only to correspond to the folded region FR, or may be positioned to surround the hard layer 173b in the non-folded region NFR.

Here, the soft layer 173a may be made of any one of polyurethane (PU), thermoplastic polyurethane (TPU), silicon (Si), and polydimethylacrylamide (PDMA), and the hard layer ( 173b) is a metal material such as stainless steel (SUS), polymethyl methacrylate (PMMA), polycarbonate (PC), polyvinyl alcohol (PVA), acrylonitrile-butadiene- It may be made of polymers such as styrene (acrylonitirle-butadiene-styrene, ABS) and polyethylene terephthalate (PET).

In this shock-absorbing film 170, layers having different modulus values are mixed by the hard layer 173b of the first shock-absorbing layer 171 and the second shock-absorbing layer 173, that is, the first shock absorbing layer 173 The absorption layer 171 has a lower modulus value than the cover window 140, the touch panel 120, the OLED panel 110, and the back plate 130, and the soft layer 173a of the second shock absorption layer 173 covers the Although it has a lower modulus value than the window 140, the touch panel 120, the OLED panel 110, and the back plate 130, the hard layer 173b of the second shock absorbing layer 173 has a lower modulus value than the cover window 140 and the touch panel 140. It has a modulus value similar to that of the panel 120, OLED panel 110, and backplate 130.

For example, the cover window 140, the touch panel 120, and the OLED panel 110 have a modulus value of about 5 to 8 GPa, and the backplate 130 has a modulus value of about 8 to 10 GPa. The soft layer 173a of the first shock absorption layer 171 and the second shock absorption layer 173 may have a modulus value lower than 10 ³ to 10 ⁴ Pa.

And the hard layer 173b of the second shock absorption layer 173 has a modulus value of about 5 to 8 GPa.

Accordingly, this shock-absorbing film 170 is divided into a first shock-absorbing layer 171 and a second shock-absorbing layer (hard layer, 173b), so that it has a structure in which high modulus values and low modulus values are mixed. , This creates a structure that can more stably alleviate shocks from the outside.

That is, if the shock-absorbing film 170 is formed to have only a low modulus value, the film itself will be severely deformed and will not function as the shock-absorbing film 170, and if it is formed to have only a high modulus value, it will be resistant to shocks applied from the outside. are all transmitted to the touch panel 120 or OLED panel 110, which may cause damage to the touch panel 120 or OLED panel 110.

These first and second shock absorption layers 171 and 173 are attached to each other through a fourth optical adhesive layer 175.

The fourth optical adhesive layer 175 is formed of OCA (Optical Cleared Adhesive), and is preferably formed to have a thickness of about 100 to about 300 μm.

And, the fourth optical adhesive layer 175 may have any modulus value.

The fourth optical adhesive layer 175 actually functions as a component of the shock absorbing film 170 rather than as a component of the foldable display device 100, so that the modulus value of the foldable display device 100 is high and low. This is because it has nothing to do with the configuration of alternating positions.

In particular, the first shock absorption layer 171 located above the fourth optical adhesive layer 175 and the third optical adhesive layer 180 located above the first shock absorption layer 171 have a lower modulus value than the back plate 130. Therefore, even if the fourth optical adhesive layer 175 has a high modulus, it acts as a layer with a low modulus value due to the first shock absorption layer 171 and the third optical adhesive layer 180.

Accordingly, the fourth optical adhesive layer 175 may have a low modulus value or a high modulus value.

Here, the first shock-absorbing layer 171 has a thickness of about 100 to about 300um. When the first shock-absorbing layer 171 has a thickness of about 100um or less, the shock-absorbing power is minimal, and the first shock-absorbing layer 171 has a thickness of about 100um or less. If it has a thickness of about 300 um or more, it may cause a problem in that the foldable display device 100 becomes difficult to fold.

In addition, the second shock absorption layer 173 has a total thickness of about 0.1 to about 1 mm. In the non-folded region (NFR), the soft layer 173a has a thickness of 0 to about 0.9 mm, and the hard layer 173b has a thickness of about 0.9 mm. It is desirable to form it to have a thickness of 0.1 to about 1 mm.

When the thickness of the second shock absorption layer 173 is about 0.1 mm or less, the shock absorption power is minimal, and when the thickness of the second shock absorption layer 173 is about 1 mm or more, the folding of the foldable display device 100 becomes difficult. can cause

In addition, when the thickness of the hard layer 173b of the second shock absorbing layer 173 is about 0.1 mm or less, the effect as the hard layer 173b is minimal, and currently, the process is used to form the hard layer 173b of about 0.1 mm or less. However, if the thickness of the hard layer 173b is about 1 mm or more, it may cause a problem in that the folding of the foldable display device 100 becomes difficult.

The foldable display device 100 according to the second embodiment of the present invention described above has the modulus values of each component alternately positioned between high and low, so that even when an impact is applied from the outside, compared to a typical foldable display device, the foldable display device 100 As the impact passes through components with high and low modulus values, it is partially alleviated, minimizing the transmission of external impact to the touch panel 120 or OLED panel 100, while also minimizing the impact to the back of the back plate 130. By further positioning the absorbent film 170, damage to the touch panel 120 or OLED panel 110 due to external impact can be more effectively prevented.

[Table 2]

[Table 2] above is a table showing the results of a ball-drop test depending on the presence or absence of the shock-absorbing film 170 according to the modulus value of the backplate 130.

Prior to explanation, Sample A is a general folder that has a modulus value of about 2.2 * 10 ⁵ Pa of the first and second optical adhesive layers (150, 160) as shown in [Table 1] above and does not include a shock absorbing film. It shows the results of the ball drop test in the folded area (FR) of the display device.

Sample C has a modulus value of about 1.3 * 10 ³ Pa for the first and second optical adhesive layers (150, 160) in the general foldable display device of Sample A, and is the same as the first and second optical adhesive layers (150, 160). It is a configuration in which only the first shock absorbing layer 171 is further positioned below the third optical adhesive layer 180 having a modulus value, and Sample D is a shock absorbing layer 173 further including a second shock absorbing layer 173 in the foldable display device of Sample C. It shows the results of a ball drop test in the folded region (FR) of the foldable display device 100 where the absorbent film 170 is located.

The second shock absorption layer 173 of Sample D has a thickness of about 300 μm for the soft layer 173a and about 300 μm for the hard layer 173b in the non-folded region (NFR).

And, looking at the data of the modulus value of the back plate 130 ranging from 0 to about 1 GPa, the conditions of Sample A and Sample C (the modulus value of the optical adhesive layers 150 and 160 and the presence or absence of the first shock absorbing layer 171 and It can be seen that the ball drop test results are consistent even though the thicknesses of the first shock absorption layer 171 are different. This shows that it is desirable to form the backplate 130 to have a modulus value of about 4 to about 7 GPa or more. You can.

At this time, when the modulus value of the backplate 130 is about 10 GPa or more, it becomes very difficult to fold and unfold the foldable display device 100 including the backplate 130, so the backplate 130 It is desirable to have a modulus value of about 10 GPa or less.

In addition, when the thickness of the first shock absorption layer 171 is less than about 100um, the shock absorption power is minimal, and when it is more than about 300um, it becomes difficult to fold the foldable display device 100, so the thickness of the first shock absorption layer 171 It is desirable to form it to have a thickness of about 100 to about 300 um.

That is, referring to Sample C in [Table 2] above, when the thickness of the first shock absorbing layer 171 is 0.05t, when the ball is dropped from a height of about 5cm, the touch panel 120 or OLED panel It can be seen that damage to (110) begins to occur, but when the thickness of the first shock absorbing layer (171) is 0.10t to 0.30t, when the ball is dropped from a height of about 10cm, the touch panel (120) or It can be seen that damage to the OLED panel 110 is starting to occur.

Through this, it can be seen that it is desirable to form the first shock absorption layer 171 to have a thickness of about 100 to about 300 μm. Based on this information, referring to [Table 2] above, Sample A is the touch panel 120 or OLED panel when the ball is dropped from a height of about 5 cm, regardless of the modulus value of the back plate 130. (110) begins to break, but in Sample D, the first to third optical adhesive layers (150, 160, 180) have a modulus value of about 10 ³ Pa, and the back plate has a modulus value of about 4 GPa or more and about 10 GPa or less. It has a shock-absorbing film 170 such that high and low modulus values of each component are alternately positioned alternately with each other, and includes first and second shock-absorbing layers 171 and 173 on the back of the back plate 130. By further positioning, it can be confirmed that damage to the touch panel 120 or OLED panel 110 begins only when the ball is dropped from a height of about 15 cm to about 20 cm. In other words, it can be confirmed that the ball drop test results of the foldable display device according to the second embodiment of the present invention are more than twice as different as those of Sample A, a general foldable display device.

Through this, the foldable display device 100 according to the second embodiment of the present invention has the modulus value of each component alternately positioned between high and low, so that shock is applied from the outside compared to a typical foldable display device. Even if the impact is partially alleviated as it passes through components with high and low modulus values, it is possible to minimize the transmission of external impact to the touch panel 120 or OLED panel 100, while also minimizing the impact to the back of the back plate 130. By positioning the shock-absorbing film 170 including the first and second shock-absorbing layers 171 and 173, even when shock is applied from the outside compared to a typical foldable display device, some of the shock is alleviated, so that the touch panel 120 or It can be confirmed that transmission to the OLED panel 110 can be minimized.

In particular, in Sample C, in which only the first shock absorbing layer 171 is located, damage to the touch panel 120 or OLED panel 110 begins when the ball is dropped from a height of about 10 cm, whereas the first and second impacts In Sample D, which includes both the absorption layers 171 and 173, it can be confirmed that damage to the touch panel 120 or OLED panel 110 begins when the ball is dropped from a height of about 15 cm to about 20 cm. .

Through this, compared to the configuration in which only the first shock absorbing layer 171 is located, the second shock absorbing layer including the first shock absorbing layer 171, the hard layer 173b, and the soft layer 173a as in the second embodiment of the present invention. It can be seen that the configuration including all of the absorbing layers 173 can minimize damage to the touch panel 120 or OLED panel 110 due to external impact.

This will be examined in more detail with reference to Figure 4 below.

Figure 4 is a ball-drop test graph of a foldable display device according to a second embodiment of the present invention.

Prior to explanation, in the graph of FIG. 4, the vertical axis represents the height from which the ball was dropped, and on the horizontal axis, Sample A is a general foldable display device that does not include a shock-absorbing film and contains optical adhesive layers (150 in FIG. 1, 160) has a modulus value of approximately 2.2 * 10 ⁵ Pa.

Sample D is a foldable display device (100 in FIG. 3) according to the second embodiment of the present invention, and includes first and second shock absorption layers (171 and 173 in FIG. 3), and first to third shock absorption layers (100 in FIG. 3) according to the second embodiment of the present invention. The optical adhesive layers (150, 160, and 180 in FIG. 3) each have a modulus value of about 1.3 * 10 ³ Pa. At this time, the thickness of the soft layer (173a in FIG. 3) and the hard layer (173b in FIG. 3) of the second shock absorption layer (173 in FIG. 3) are each about 300 um in the non-folded area.

And Sample E is composed of only the second shock absorbing layer (173 in FIG. 3) among the shock absorbing films (170 in FIG. 3), and the first to third optical adhesive layers (150, 160, and 180 in FIG. 3) are each about It has a modulus value of 1.3 * 10 ³ Pa.

That is, Sample D and Sample E are the results of a ball-drop test of a foldable display device depending on the presence or absence of the first shock absorption layer (171 in FIG. 3).

Meanwhile, on the graph, the folded area (FR) is an area that is folded so that a curvature is formed when the foldable display device (100 in FIG. 3) is folded, and the foldable display device (100 in FIG. 3) is on both sides of the folded area (FR). It is divided into a non-folded region (NFR), which maintains a flat state even when folded.

Each bar is displayed by dropping a ball in a random area of the folded area (FR) and non-folded area (NFR), and then using a touch panel (120 in FIG. 3) or an OLED panel depending on the height of the ball. This means that damage (110 in FIG. 3) has occurred.

That is, in Sample A on the graph, the bar in the folded area (FR) is a foldable display device (100 in FIG. 1) when a ball is dropped into a random area of the folded area (FR) from a height of about 5 cm. This means that damage has begun in a part of the non-folded area (NFR). If a ball is dropped from a height of about 20 cm into a random area of the non-folded area (NFR), the foldable display device ( This means that damage began in part 100) of FIG. 1.

Referring to the graph in FIG. 4, when a ball is dropped from a height of about 5 cm in the folded region (FR) of Sample A, damage to the touch panel (120 in FIG. 1) or OLED panel (110 in FIG. 1) occurs. However, in Sample D, it can be confirmed that damage to the touch panel (120 in FIG. 1) or OLED panel (110 in FIG. 1) begins when the ball is dropped from a height of about 15 cm in the folded region (FR). You can.

In addition, in Sample A, when the ball is dropped from a height of about 20 cm in the non-folded region (NFR), damage to the touch panel (120 in FIG. 1) or OLED panel (110 in FIG. 1) begins to occur, but in Sample D In , it can be seen that damage to the touch panel (120 in FIG. 1) or OLED panel (110 in FIG. 1) begins to occur when a ball is dropped from a height of about 30 cm in the non-folded region (NFR).

That is, the foldable display device (100 in FIG. 3) according to the second embodiment of the present invention has the modulus value of each component alternately positioned between high and low, and the first and second By positioning the shock-absorbing film (170 in FIG. 3) containing the shock-absorbing layer (171 and 173 in FIG. 3), transfer to the touch panel (120 in FIG. 1) or OLED panel (110 in FIG. 1) can be minimized. You can confirm that it exists.

In particular, comparing Sample D and Sample E in the graph of FIG. 4, when only the second shock absorbing layer (173 in FIG. 3) of Sample E is provided, when a ball is dropped from a height of about 10 cm in the folded region (FR) Damage to the touch panel (120 in FIG. 1) or OLED panel (110 in FIG. 1) begins to occur, and in the non-folded region (NFR), when a ball is dropped from a height of about 25 cm, the touch panel (120 in FIG. 1) ) or damage to the OLED panel (110 in Figure 1) begins to occur.

Accordingly, it can be confirmed that Sample D according to the second embodiment of the present invention can minimize transmission to the touch panel (120 in FIG. 1) or OLED panel (110 in FIG. 1) compared to Sample E.

That is, in the data of Sample C and Sample D in [Table 2] above, compared to the configuration in which only the first shock absorbing layer (171 in FIG. 3) is located, the first and second shock absorbing layers according to the second embodiment of the present invention It can be seen that the configuration including both (171 and 173 in FIG. 3) can further minimize the transmission to the touch panel (120 in FIG. 1) or OLED panel (110 in FIG. 1), and the graph in FIG. 4 In the data of Sample D and Sample E, compared to the configuration in which only the second shock absorbing layer (173 in FIG. 3) is located, the first and second shock absorbing layers (171 and 173 in FIG. 3) according to the second embodiment of the present invention. It can be seen that a configuration including all can further minimize transmission to the touch panel (120 in FIG. 1) or OLED panel (110 in FIG. 1).

In addition, even if the backplate 130 with a low modulus value is used, it is possible to prevent the touch panel 120 or the OLED panel 110 from being damaged by external impact compared to the existing case, so the backplate 130 ) can reduce the process cost due to the manufacturing cost.

[Table 3]

[Table 3] above shows the results of a ball-drop test according to the change in modulus value of the first to third optical adhesive layers (150, 160, 180) and the presence or absence of the shock-absorbing film (170). It's a table.

Prior to explanation, Sample F represents the results of a ball drop test according to the change in modulus values of the first and second optical adhesive layers 150 and 160 of a foldable display device that does not include the shock absorbing film 170, and Sample D In addition to the first and second optical adhesive layers 150 and 160, a third optical adhesive layer 180 is additionally disposed on the back of the back plate 130 according to the second embodiment of the present invention to form a first shock absorption layer of about 200um. A foldable display device in which a shock absorbing film 170 including (171) and a second shock absorbing layer 173 having a total thickness of about 600 μm of the soft layer 173a and hard layer 173b each having a thickness of about 300 μm is located. It represents (100).

Here, the cover window 140, the touch panel 120, and the OLED panel 110 have a modulus value of about 5 to about 8 GPa, and the backplate 130 has a modulus value of about 8 to about 10 GPa.

Referring to [Table 3] above, in the general foldable display device of Sample F, the first optical adhesive layer 150 between the cover window 140 and the touch panel 120, the OLED panel 110, and the backplate ( 130), it can be confirmed that even when the second optical adhesive layer 160 is made to have a low modulus value of about 10 ³ Pa, it becomes more resistant to shock from the outside.

In other words, if the optical adhesive layer of a typical foldable display device has a modulus value of about 10 ⁵ Pa, damage to the touch panel 120 or OLED panel 110 begins to occur when the ball is dropped from about 5 cm above in the ball drop test. However, if the optical adhesive layers (150, 160, 180) have a modulus value of about 10 ³ Pa, the touch panel 120 or OLED panel 110 may be damaged when a ball is dropped from about 10 cm in a ball drop test. You can see the damage starting to occur.

Therefore, it can be confirmed that damage to the touch panel 120 or the OLED panel 110 varies due to impact applied from the outside depending on the modulus values of the optical adhesive layers 150, 160, and 180, and in particular, the optical adhesive layers 150, When the modulus value of the optical adhesive layer (160, 180) is formed to be about 10 ³ Pa, shock from the outside is less likely to affect the touch panel 120 or the OLED panel compared to the case where the modulus value of the optical adhesive layer (150, 160, 180) is about 10 ⁵ Pa. It can be seen that the transmission to (110) can be further minimized.

In addition, referring to Sample D, the modulus value of the optical adhesive layer (150, 160, 180) is lowered, and a shock absorbing film ( 170), it can be seen that the ball drop test results are about 3 to 4 times more different than those of a typical foldable display device.

That is, by alternating the modulus values of each component of the foldable display device 100 to high and low, the touch panel 120 or OLED panel ( 110), and by further positioning the shock-absorbing film 170 on the back of the back plate 130, damage to the touch panel 120 or OLED panel 110 can be prevented due to shock applied from the outside. It can be confirmed that this occurrence can be prevented more efficiently.

As described above, the foldable display device 100 according to the second embodiment of the present invention has the modulus value of each component alternately positioned between high and low, so that the touch panel 120 can be maintained even when an impact is applied from the outside. ) or the OLED panel 110 can be minimized, and by further positioning the shock absorbing film 170 on the back of the back plate 130, shock applied from the outside can damage the touch panel 120 or the OLED panel. Damage of (110) can be prevented more efficiently.

Meanwhile, in the description so far, it has been explained and shown that in the foldable display device 100, the touch panel 120 is located above the display panel 110 where an image is displayed, but the touch panel can be deleted.

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

100: Foldable display device
110: Display panel (OLED panel)
120: Touch panel
130: backplate
140: Cover window
150, 160, 180, 173: 1st to 4th optical adhesive layers
170: shock absorbing film (171: first shock absorbing layer, 173: second shock absorbing layer (173a: soft layer, 173b: hard layer))

Claims (12)

a display panel on which an image is displayed;
a cover window located in front of the display panel;
a back plate located behind the display panel;
Shock-absorbing film located at the bottom of the back plate
Includes,
The shock-absorbing film includes first and second shock-absorbing layers,
The second shock absorbing layer includes a soft layer corresponding to a folded area and a hard layer corresponding to a non-folded area, and the first shock absorbing layer and the soft layer have a lower modulus value than the hard layer.
According to claim 1,
The first shock-absorbing layer is made of a foam material, and the soft layer of the second shock-absorbing layer is made of polyurethane (PU), thermoplastic polyurethane (TPU), silicone (Si), and polydimethyl. It is made of one selected from acrylamide (polydimethylacrylamide, PDMA), and the hard layer is made of a metal material such as stainless steel (SUS), polymethyl methacrylate (PMMA), polycarbonate (PC), or poly. A foldable display device made of one selected from polyvinylalcohol (PVA), acrylonitrile-butadiene-styrene (ABS), and polyethylene terephthalate (PET).
According to claim 1,
The first shock absorption layer has a thickness of 100 to 300 μm, the soft layer has a thickness of 0 to 0.9 mm, and the hard layer has a thickness of 0.1 to 1 mm. According to claim 1,
The first shock absorption layer is a foldable display device having a modulus value of 10 ³ to 10 ⁴ Pa.
According to claim 1,
The soft layer of the second shock absorption layer has a modulus value of 10 ³ to 10 ⁴ Pa, and the hard layer has a modulus value of 5 to 8 GPa.
According to claim 1,
A first optical adhesive layer is positioned between the cover window and the display panel,
A second optical adhesive layer is located between the display panel and the back plate,
The first and second optical adhesive layers have a modulus value of 10 ³ to 10 ⁴ Pa.
According to claim 6,
A third optical adhesive layer is positioned between the shock absorption film and the back plate, and the third optical adhesive layer has a modulus value of 10 ³ to 10 ⁴ Pa.
According to claim 1,
A first optical adhesive layer is positioned between the cover window and the display panel,
A second optical adhesive layer is located between the display panel and the back plate,
The first optical adhesive layer has a lower modulus value than the cover window and the display panel,
A foldable display device in which the second optical adhesive layer has a lower modulus value than the display panel and the backplate.
According to claim 8,
A touch panel is located between the cover window and the display panel,
A foldable display device in which the first optical adhesive layer has a lower modulus value than the cover window and the touch panel.
According to claim 8,
A third optical adhesive layer is located between the shock absorbing film and the back plate,
A foldable display device in which the third optical adhesive layer has a lower modulus value than the backplate.
According to claim 1,
A foldable display device in which the first shock absorption layer and the second shock absorption layer are attached to each other through a fourth optical adhesive layer. According to claim 1,
The hard layer is a foldable display device made of a metal material.

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