Foldable display device

Abstract

A foldable display device is provided. The display device includes a display panel including a folding area and a non-folding area on both sides of the folding area, a back plate disposed below the display panel, a first support layer disposed below the back plate, an opening pattern included in the first support layer, the opening pattern being arranged in a portion corresponding to the folding area, and a second support layer disposed between the first support layer and the back plate, wherein the second support layer overlaps the opening pattern, and the second support layer includes a polymer.

Description

[0001] This patent application is a divisional application of the patent application filed on December 3, 2020, with application number 202011397996.6 and invention title "Foldable Display Device".

[0002] Cross-references to related applications

[0003] This application claims priority to Korean Patent Application No. 10-2019-0163880, filed with the Korean Intellectual Property Office on December 10, 2019, the disclosure of which is incorporated herein by reference. Technical Field

[0004] This disclosure relates to a foldable display device, and more specifically, to a foldable display device with improved shock resistance. Background Technology

[0005] Recently, as society moves towards an information society, the field of display devices for processing and displaying large amounts of information has developed rapidly, and various flat panel display devices are being developed accordingly.

[0006] Specific examples of such flat panel display devices include liquid crystal displays (LCDs), field emission displays (FEDs), electroluminescent displays (ELDs), and organic light-emitting diodes (OLEDs). These flat panel display devices exhibit excellent performance in terms of thinness, light weight, and low power consumption, and are therefore rapidly replacing existing cathode ray tubes (CRTs).

[0007] At the same time, because such flat panel display devices use glass substrates to withstand the high heat generated during the manufacturing process, they have limitations in reducing weight and thickness as well as providing flexibility.

[0008] Therefore, flexible display devices, which use flexible materials such as plastics to replace existing non-flexible glass substrates and are manufactured to maintain their display performance even when bent like paper, are rapidly becoming the next generation of flat panel display devices.

[0009] Such flexible display devices can be categorized as follows: undamaged types that achieve high durability by using plastic thin-film transistor substrates instead of glass; bendable types that are not easily damaged; rollable types that can be rolled up; and foldable types that can be folded. These flexible display devices offer advantages in terms of space utilization and internal design, and can be used in a variety of application areas.

[0010] In particular, recently, foldable display devices that can be portable in the folded state and display images in the unfolded state are being actively researched in order to achieve large area in conjunction with thinness, lightness and miniaturization.

[0011] Foldable display devices can be used not only in mobile devices such as mobile phones, ultra-mobile PCs, e-books and e-newspapers, but also in a variety of applications such as TVs and monitors.

[0012] Such a foldable display device includes: a display panel for displaying images; a back panel located below the display panel to support the display panel; and a cover window located in front of the display panel to protect the display panel.

[0013] At the same time, since foldable display devices should be folded and unfolded, the back panel, cover window, and all of the display panel are configured in the form of a very thin film, and this thin film form vertically transmits most of the impact transmitted from the outside.

[0014] In other words, since the cover window and back panel are in the form of a thin film, when an impact is applied to the cover window or back panel from the outside, the impact is directly transmitted to the display panel located between the cover window and the back panel.

[0015] This, in turn, damages the display panel, thereby degrading its display quality. As mentioned above, various structures are being researched and used to reduce the resistance of public power lines. Summary of the Invention

[0016] The purpose of this disclosure is to provide a foldable display device with improved shock resistance.

[0017] Another objective of this disclosure is to provide a foldable display device that can prevent degradation of display quality.

[0018] The purpose of this disclosure is not limited to the purposes mentioned above, and other purposes not mentioned above will be clearly understood by those skilled in the art from the following description.

[0019] According to one aspect of this disclosure, the foldable display device may include a display panel comprising a folded region and non-folded regions on both sides of the folded region. A back plate may be disposed below the display panel, and a first support layer may be disposed below the back plate and have an opening pattern in the portion of the first support layer corresponding to the folded region. An impact-absorbing layer may be disposed below the first support layer. The impact-absorbing layer may include a first portion corresponding to the folded region and a second portion corresponding to the non-folded region, and the modulus of the first portion may be greater than the modulus of the second portion.

[0020] Further details of the exemplary embodiments are included in the detailed embodiments and the accompanying drawings.

[0021] In the foldable display device according to an exemplary embodiment of this disclosure, the first portion of the impact-absorbing layer corresponding to the folded area of ​​the display panel is formed of a material with a high modulus. Therefore, even when a point impact is applied to the folded area, the point impact is converted into a surface impact, making it more effective to prevent damage to the display panel or touch panel from the point impact. Thus, the impact resistance characteristics of the display device can be improved.

[0022] Since the technical problem to be solved, the means to solve the problem, and the effects described in the specification are not intended to limit the essential features of the claims, the scope of the claims is not limited by the content described in the specification. Attached Figure Description

[0023] The above and other aspects, features and advantages of this disclosure will become more clearly understood from the following detailed description taken in conjunction with the accompanying drawings:

[0024] Figure 1 This is a schematic cross-sectional view of the foldable display device disclosed herein;

[0025] Figure 2 yes Figure 1 A schematic cross-sectional view of the display panel;

[0026] Figure 3 This is a schematic cross-sectional view of a foldable display device according to an exemplary embodiment of the present disclosure;

[0027] Figure 4 These are photographs showing the ball-drop test results of a foldable display device according to an exemplary embodiment of this disclosure; and

[0028] Figure 5 This is a schematic cross-sectional view of a foldable display device according to another exemplary embodiment of the present disclosure. Detailed Implementation

[0029] By referring to the following and appendix Figure 1 The advantages and features of this disclosure, as well as methods for achieving such advantages and features, will become clear from the exemplary embodiments described in detail herein. However, this disclosure is not limited to the exemplary embodiments disclosed herein, but will be implemented in various forms. Exemplary embodiments are provided by way of example only so that those skilled in the art can fully understand the disclosure and scope of this disclosure. Therefore, this disclosure will be limited only by the scope of the appended claims.

[0030] The shapes, dimensions, ratios, angles, numbers, etc., shown in the accompanying drawings to describe exemplary embodiments of this disclosure are merely examples, and this disclosure is not limited thereto. Throughout the specification, the same reference numerals generally denote the same elements. Furthermore, in the following description of this disclosure, detailed descriptions of known related technologies may be omitted to avoid unnecessarily obscuring the subject matter of this disclosure. Terms such as “comprising,” “having,” and “including” as used herein are generally intended to allow for the addition of additional components, unless these terms are used in conjunction with the term “only.” Unless otherwise expressly stated, any reference to the singular may include the plural form.

[0031] Even if not explicitly stated, components should be interpreted as including the normal tolerance range.

[0032] When using terms such as “on top of,” “above,” “below,” and “adjacent” to describe the positional relationship between two parts, one or more parts may be located between the two parts unless these terms are used in conjunction with the terms “immediately following” or “directly.”

[0033] When an element or layer is placed "on" another element or layer, the other layer or another element may be placed directly on or between the other element.

[0034] Although the terms "first," "second," etc., are used to describe various components, these components are not limited by these terms. These terms are only used to distinguish one component from another. Therefore, in the technical concept of this disclosure, the first component mentioned below can be the second component.

[0035] Throughout the specification, the same reference numerals generally denote the same elements.

[0036] For ease of description, the dimensions and thickness of each component shown in the accompanying drawings are illustrated, and this disclosure is not limited to the dimensions and thickness of the components shown.

[0037] Features of the various embodiments of this disclosure may be partially or wholly adhered to or combined with each other, and may be interlocked and operated in technically different ways, and the embodiments may be performed independently or in association with each other.

[0038] In the following, a display device according to an exemplary embodiment of the present disclosure will be described in detail with reference to the accompanying drawings.

[0039] Figure 1 This is a schematic cross-sectional view of a foldable display device according to a first exemplary embodiment of the present disclosure. Figure 2 yes Figure 1 A schematic cross-sectional view of the display panel.

[0040] As shown, the foldable display device 100 includes: a display panel 110 for displaying images; a touch panel 120 constituting a touch sensor (not shown); a cover window 130 for protecting the display panel 110; a back plate 140 for supporting the display panel 110; a first support layer 160 disposed below the back plate 140 and having an opening pattern 161; and a second support layer 150 between the back plate 140 and the first support layer 160.

[0041] At this time, when the orientation is defined in the accompanying drawings for ease of explanation, based on the premise that the display surface of the display panel 110 faces forward, the back plate 140, the first support layer 160 and the second support layer 150 are located behind the display panel 110, and the cover window 130 is located in front of the display panel 110.

[0042] The touch panel 120 is located between the display panel 110 and the cover window 130. The various components are adhered and attached to each other by adhesives 180a, 180b, 190a, and 190b.

[0043] Here, the display panel 110 can be formed of one of a liquid crystal display (LCD), a field emission display (FED), an electroluminescent display (ELD), and an organic light-emitting diode (OLED), but it is preferred to use an OLED, which is representative of flexible display devices that can maintain their display performance even when bent like paper.

[0044] OLEDs are self-emissive devices, and because they do not require a backlight, as is used in liquid crystal displays which are non-emissive devices, they can be manufactured to be both lightweight and thin.

[0045] In addition, OLEDs offer superior viewing angles and contrast compared to LCDs, and are advantageous in terms of power consumption, low DC driving voltage, and fast response speed. Furthermore, because the internal components of OLEDs are solid-state, they are resistant to external impacts and have a wide operating temperature range.

[0046] In particular, due to the simplicity of the OLED manufacturing process, it has the advantage of reducing production costs compared to existing liquid crystal display devices.

[0047] In the display panel 110 formed by such an OLED, a substrate 101 is encapsulated by an encapsulation part 105g, on which a driving thin film transistor 102 and a light-emitting element 103 are formed.

[0048] Here, refer to Figure 2 The following will describe in detail the display panel formed by OLED (hereinafter referred to as OLED panel).

[0049] Reference Figure 2 The substrate 101 is used to support and protect the components of the foldable display device 100 disposed thereon.

[0050] Recently, flexible substrate 101 can be formed from a ductile material with flexible properties, such as plastic.

[0051] The flexible substrate 101 may be in the form of a film including one of the following: polyester-based polymer, silicone-based polymer, acrylic-based polymer, polyolefin-based polymer and copolymers thereof.

[0052] For example, the flexible substrate 101 may be formed from at least one of the following: polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polysilane, polysiloxane, polysilazane, polycarbosilane, polyacrylate, polymethacrylate, polymethyl acrylate, polymethyl methacrylate, polyethyl acrylate, polyethyl methacrylate, cyclic olefin copolymer (COC), cyclic olefin polymer (COP), polyethylene (PE), polypropylene (PP), polyimide (PI), polymethyl methacrylate (PMMA), polystyrene (PS), polyacetal (POM), polyetheretherketone (PEEK), polyester sulfone (PES), polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), polycarbonate (PC), polyvinylidene fluoride (PVDF), perfluoroalkyl polymer (PFA), styrene-acrylonitrile copolymer (SAN), and combinations thereof.

[0053] A buffer layer may also be provided on the flexible substrate 101. The buffer layer prevents moisture or other impurities from penetrating through the flexible substrate 101 from the outside and can also planarize the surface of the flexible substrate 101. The buffer layer is not necessarily a necessary component and may be omitted depending on the type of thin-film transistor 102 disposed on the flexible substrate 101.

[0054] A thin-film transistor 102 is disposed on a flexible substrate 101, and the thin-film transistor 102 may include a gate electrode 102a, a source electrode 102d, a drain electrode 102c, and a semiconductor layer 102b.

[0055] In this case, the semiconductor layer 102b can be composed of amorphous silicon or polycrystalline silicon, but is not limited to these. Polycrystalline silicon has superior mobility compared to amorphous silicon, and also has low power consumption and excellent reliability, and therefore can be used in driving thin-film transistors within a pixel.

[0056] Semiconductor layer 102b can be formed of oxide semiconductor. Oxide semiconductors have excellent mobility and uniformity characteristics. Oxide semiconductors can be formed from: quaternary metal oxides such as those based on indium tin gallium zinc oxide (InSnGaZnO); ternary metal oxides such as those based on indium gallium zinc oxide (InGaZnO), indium tin zinc oxide (InSnZnO), tin gallium zinc oxide (SnGaZnO), aluminum gallium zinc oxide (AlGaZnO), indium aluminum zinc oxide (InAlZnO), and tin aluminum zinc oxide (SnAlZnO); or materials such as those based on indium zinc oxide... Materials based on zinc oxide (InZnO), materials based on zinc tin oxide (SnZnO), materials based on zinc aluminum oxide (AlZnO), materials based on zinc magnesium oxide (ZnMgO), materials based on magnesium tin oxide (SnMgO), materials based on magnesium indium oxide (InMgO), binary metal oxides based on indium gallium oxide (InGaO), materials based on indium oxide (InO), materials based on tin oxide (SnO), and materials based on zinc oxide (ZnO). The composition ratio of the individual elements included in the oxide semiconductor is not limited.

[0057] Semiconductor layer 102b may include: a source region including p-type or n-type impurities; a drain region; and a channel region between the source region and the drain region. Semiconductor layer 102b may also include a low-concentration doped region adjacent to the channel region between the source region and the drain region.

[0058] The source and drain regions are doped with a high concentration of impurities and can be connected to the source electrode 102d and drain electrode 102c of the thin-film transistor 102, respectively.

[0059] As impurity ions, either p-type or n-type impurities can be used. P-type impurities can be one of boron (B), aluminum (Al), gallium (Ga), and indium (In), while n-type impurities can be one of phosphorus (P), arsenic (As), and antimony (Sb).

[0060] The channel region of the semiconductor layer 102b may be doped with n-type or p-type impurities according to the NMOS or PMOS thin film transistor structure, and the thin film transistors included in the foldable display device 100 according to the exemplary embodiments of the present disclosure may be NMOS or PMOS thin film transistors.

[0061] The first insulating layer 105a is an insulating layer composed of a single layer or multiple layers of silicon oxide (SiOx) or silicon nitride (SiNx), and can be configured such that the current flowing through the semiconductor layer 102b does not flow to the gate electrode 102a. In addition, silicon oxide has lower ductility than metals, but silicon oxide has better ductility than silicon nitride, and silicon oxide can be formed into a single layer or multiple layers depending on its properties.

[0062] The gate electrode 102a serves as a switch for turning the thin-film transistor 102 on or off based on an electrical signal transmitted from the outside through the gate line, and may consist of a single layer or multiple layers of a conductive metal such as copper (Cu), aluminum (Al), molybdenum (Mo), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), and neodymium (Nd) or their alloys. However, the embodiments are not limited thereto.

[0063] The source electrode 102d and drain electrode 102c are connected to the data line, enabling externally transmitted electrical signals to be transmitted from the thin-film transistor 102 to the light-emitting element 103. The source electrode 102d and drain electrode 102c may be composed of a single layer or multiple layers of conductive metals or alloys thereof, such as copper (Cu), aluminum (Al), molybdenum (Mo), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), and neodymium (Nd), but are not limited thereto.

[0064] In order to insulate the gate electrode 102a from the source electrode 102d and the drain electrode 102c, a second insulating layer 105b composed of a single layer or multiple layers of silicon oxide (SiOx) or silicon nitride (SiNx) can be disposed between the gate electrode 102a and the source electrode 102d and the drain electrode 102c.

[0065] A passivation layer formed of an inorganic insulating layer such as silicon oxide (SiOx) or silicon nitride (SiNx) can be disposed on the thin-film transistor 102.

[0066] The passivation layer prevents unnecessary electrical connections between components located above and below it, and also protects against external contamination or damage. Depending on the configuration and characteristics of the thin-film transistor 102 and the light-emitting element 103, the passivation layer may be omitted.

[0067] Depending on the location of the components constituting the thin-film transistor 102, the structure of the thin-film transistor 102 can be divided into inverted interleaved structures and coplanar structures. For example, a thin-film transistor with an inverted interleaved structure refers to a thin-film transistor having the following structure: wherein, based on the semiconductor layer, the gate electrode is positioned opposite the source electrode and the drain electrode. (As in...) Figure 2In the context, the thin-film transistor 102 with a coplanar structure refers to a thin-film transistor having the following structure: wherein, based on the semiconductor layer 102b, the gate electrode 102a is located on the same side as the source electrode 102d and the drain electrode 102c.

[0068] exist Figure 2 The present invention illustrates a thin-film transistor 102 having a coplanar structure, but the foldable display device 100 according to an exemplary embodiment of the present disclosure may also include thin-film transistors having an inverted staggered structure.

[0069] For ease of description, only the driving thin-film transistor is shown among the various thin-film transistors that may be included in the foldable display device 100. Switching thin-film transistors, capacitors, etc., may also be included in the foldable display device 100.

[0070] Furthermore, when a signal is applied from the gate line to the switching thin-film transistor, the switching thin-film transistor transmits the signal from the data line to the gate electrode of the driving thin-film transistor. The driving thin-film transistor can transmit the current transmitted through the power line to the anode 103a via the signal transmitted from the switching thin-film transistor, and control the light emission by the current transmitted to the anode 103a.

[0071] Planarization layers 105c and 105d can be disposed on the thin-film transistor 102 to protect the thin-film transistor 102, to mitigate the steps caused by the thin-film transistor 102, and to reduce the parasitic capacitance generated between the thin-film transistor 102 and the gate line, data line, and light-emitting element 103.

[0072] The planarization layers 105c and 105d may be formed from one or more of the following: acrylic resin, epoxy resin, phenolic resin, polyamide resin, polyimide resin, unsaturated polyester resin, polyphenylene resin, polyphenylene sulfide resin, and benzocyclobutene, but are not limited thereto.

[0073] A foldable display device 100 according to an exemplary embodiment of the present disclosure may include a first planarization layer 105c and a second planarization layer 105d stacked sequentially. That is, the first planarization layer 105c may be disposed on the thin-film transistor 102, and the second planarization layer 105d may be disposed on the first planarization layer 105c.

[0074] A buffer layer may be disposed on the first planarization layer 105c. The buffer layer may consist of multiple layers of silicon oxide (SiOx) to protect the components disposed on the first planarization layer 105c, and may be omitted depending on the configuration and characteristics of the thin-film transistor 102 and the light-emitting element 103.

[0075] The intermediate electrode 104 can be connected to the thin-film transistor 102 through contact holes formed in the first planarization layer 105c. The intermediate electrode 104 is stacked to connect to the thin-film transistor 102, and the data lines can also be formed as a multilayer structure.

[0076] The data line can be formed with the following structure: a lower layer is connected to an upper layer, the lower layer is formed of the same material as the source electrode 102d and the drain electrode 102c, and the upper layer is formed of the same material as the intermediate electrode 104. In other words, the data line can be implemented with two layers connected in parallel, and in this case, the line resistance of the data line can be reduced.

[0077] Meanwhile, a passivation layer formed of an inorganic insulating layer such as silicon oxide (SiOx) or silicon nitride (SiNx) can be further disposed on the first planarization layer 105c and the intermediate electrode 104. The passivation layer can be used to prevent unnecessary electrical connections between components, as well as to prevent contamination or damage from the outside, and can be omitted depending on the configuration and characteristics of the thin-film transistor 102 and the light-emitting element 103.

[0078] The light-emitting element 103 disposed on the second planarization layer 105d may include an anode 103a, a light-emitting unit 103b, and a cathode 103c.

[0079] The anode 103a can be disposed on the second planarization layer 105d.

[0080] The anode 103a is used to provide holes to the light-emitting unit 103b and is connected to the intermediate electrode 104 through a contact hole in the second planarization layer 105d, thereby being electrically connected to the thin-film transistor 102.

[0081] The anode 103a can be formed of a transparent conductive material, such as indium tin oxide (ITO), indium zinc oxide (IZO), etc., but is not limited to this.

[0082] When the foldable display device 100 is a top-emitting type display device that emits light toward the upper part on which the cathode 103c is disposed, it may also include a reflective layer such that the emitted light is reflected from the anode 103a so as to be smoothly emitted in a direction toward the upper part on which the cathode 103c is disposed.

[0083] The anode 103a can be a two-layer or a three-layer structure. In a two-layer structure, a transparent conductive layer formed of a transparent conductive material and a reflective layer are stacked sequentially. In a three-layer structure, a transparent conductive layer, a reflective layer, and a transparent conductive layer are stacked sequentially. The reflective layer can be formed of silver (Ag) or an alloy including silver.

[0084] The embankment 105e, disposed on the anode 103a and the second planarization layer 105d, can define sub-pixels by dividing the actual light-emitting area. After the photoresist is formed on the anode 103a, the embankment 105e can be formed by photolithography. Photoresist is a photosensitive resin whose solubility in a developer is altered by the action of light, and a specific pattern can be obtained by exposing and developing the photoresist. Photoresists can be classified into positive photoresists and negative photoresists. Positive photoresists increase the solubility of their exposed portion in the developer through exposure. When a positive photoresist is developed, a pattern is obtained from which the exposed portion has been removed. Negative photoresists significantly reduce the solubility of their exposed portion in the developer through exposure. When a negative photoresist is developed, a pattern is obtained from which the unexposed portion has been removed.

[0085] A fine metal mask (FMM) as a deposition mask can be used to form the light-emitting unit 103b of the light-emitting element 103.

[0086] In addition, to prevent damage that may occur due to contact with the deposition mask disposed on the dam 105e, and to maintain a constant distance between the dam 105e and the deposition mask, a spacer 105f formed of one of polyimide (which is a transparent organic material), photoacrylic acid and benzocyclobutene (BCB) may be disposed on the dam 105e.

[0087] The light-emitting unit 103b can be disposed between the anode 103a and the cathode 103c.

[0088] The light-emitting unit 103b is used for emitting light and may include at least one of a hole injection layer (HIL), a hole transport layer (HTL), a light-emitting layer, an electron transport layer (ETL), and an electron injection layer (EIL). Depending on the structure or characteristics of the foldable display device 100, some components may be omitted. Here, an electroluminescent layer and an inorganic light-emitting layer may be applied to the light-emitting layer.

[0089] A hole injection layer is disposed on the anode 103a to facilitate hole injection.

[0090] A hole transport layer is disposed on the hole injection layer to facilitate the smooth transport of holes to the light-emitting layer.

[0091] The luminescent layer is disposed on the hole transport layer and may include a material capable of emitting light of a specific color. Alternatively, phosphorescent or fluorescent materials can be used to form the luminescent material.

[0092] An electron injection layer may be further disposed on the electron transport layer. The electron injection layer is an organic layer that facilitates the injection of electrons from the cathode 103c, and may be omitted depending on the structure and characteristics of the foldable display device 100.

[0093] On the other hand, an electron blocking layer or a hole blocking layer is also provided at a position adjacent to the light-emitting layer to prevent the following phenomenon: when an electron is injected into the light-emitting layer, the electron moves from the light-emitting layer and is transmitted to the adjacent hole transport layer, or prevents the following phenomenon: when a hole is injected into the light-emitting layer, the hole moves from the light-emitting layer and is transmitted to the adjacent electron transport layer; thereby improving the luminous efficiency.

[0094] A cathode 103c is disposed on the light-emitting unit 103b and is used to provide electrons to the light-emitting unit 103b. Since the cathode 103c needs to provide electrons, it can be formed of a metallic material that is a conductive material with a low work function, such as magnesium (Mg) or silver-magnesium (Ag:Mg), and is not limited thereto.

[0095] When the foldable display device 100 is a top-emitting display device, the cathode 103c can be a transparent conductive oxide, such as indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), zinc oxide (ZnO), and tin oxide (TO).

[0096] The encapsulation portion 105g can be disposed on the light-emitting element 103 to prevent the thin-film transistor 102 and the light-emitting element 103, which are components of the foldable display device 100, from being oxidized or damaged by moisture, oxygen, or impurities introduced from the outside. The encapsulation portion 105g can be formed by stacking multiple encapsulation layers, foreign matter compensation layers, and multiple barrier films.

[0097] The encapsulation layer can be disposed on the entire surface of the upper portion of the thin-film transistor 102 and the light-emitting element 103, and can be formed of either silicon nitride (SiNx) or aluminum oxide (AlyOz) as inorganic materials. However, the implementation is not limited to this. The encapsulation layer can also be disposed on a foreign matter compensation layer disposed on the encapsulation layer.

[0098] A foreign matter compensation layer is disposed on the encapsulation layer, and organic materials such as silicon carbide oxide (SiOCz), acrylic acid (propylene), or epoxy resin can be used for the foreign matter compensation layer. However, the implementation is not limited to this. When defects occur due to cracks caused by particles or foreign matter that may be generated during the process, the defects can be compensated by covering the curve and foreign matter with the foreign matter compensation layer.

[0099] The barrier film can be disposed on the encapsulation layer and the foreign matter compensation layer, thereby allowing the foldable display device 100 to delay the penetration of oxygen and moisture from the outside. The barrier film is configured as a light-transmitting and double-sided adhesive film, and can be composed of any one of olefin-based insulating materials, acrylic-based insulating materials, and silicon-based insulating materials. Alternatively, a barrier film composed of any one of COP (cyclic olefin polymer), COC (cyclic olefin copolymer), and PC (polycarbonate) can be stacked, but is not limited thereto.

[0100] Figure 3 This is a schematic cross-sectional view of a foldable display device according to an exemplary embodiment of the present disclosure.

[0101] Figure 3 Some components and Figure 1 Some of the components described herein are essentially the same and similar, and therefore their descriptions will be omitted.

[0102] A backplate 240, a second support layer 250, a first support layer 260, and an impact-absorbing layer 270 are sequentially disposed on the rear surface of the display panel 210, and a cover window 230 is positioned in front of the display panel 210. Additionally, a touch panel 220 is located between the display panel 210 and the cover window 230. The various components are adhered and attached to each other using adhesives 280a, 280b, 290a, 290b, and 290c.

[0103] Because the substrate 101 of the display panel 210 is too thin, a back plate 240 is attached to the rear surface of the display panel 210 to support it. The back plate 240 can be formed from a metal material such as stainless steel (SUS) or a polymer such as polymethyl methacrylate (PMMA), polycarbonate (PC), polyvinyl alcohol (PVA), acrylonitrile-butadiene-styrene (ABS), polyethylene terephthalate (PET), silicone, or polyurethane (PU).

[0104] The first support layer 260 is also referred to as the bottom plate. In its portion corresponding to the folding region FA of the foldable display device 200, the first support layer 260 may include an opening pattern 261. The elastic deformation region is increased by the opening pattern 261 formed in the folding region FA, thereby allowing recovery. In some embodiments, the opening pattern 261 is an open void region (e.g., filled with air). In other embodiments, the opening pattern 261 is a void region filled with any suitable material, such that the opening pattern 261 acts as a spring, thereby increasing the elastic recovery energy and allowing a reduction in recovery time. Therefore, the folding characteristics of the foldable display device 200 can be improved. Additionally, the first support layer 260 can be used to prevent transfer caused by curing. The first support layer 260 is formed of a metallic material, such as stainless steel (SUS), but is not limited thereto. The first support layer 260 may also be formed of a polymer, such as polymethyl methacrylate (PMMA), polycarbonate (PC), polyvinyl alcohol (PVA), acrylonitrile-butadiene-styrene (ABS), polyethylene terephthalate (PET), silicone, or polyurethane (PU).

[0105] The second support layer 250 is also referred to as the top of the panel. The second support layer 250 is disposed between the back panel 240 and the first support layer 260, and can enhance the rigidity of the display panel 210. Furthermore, the second support layer 250 can be used to prevent the opening pattern 261 from being seen through the display panel. The second support layer 250 can be formed of a metallic material, such as stainless steel (SUS), aluminum (Al), or magnesium (Mg). Stainless steel (SUS) includes iron (Fe) or other metals, such as chromium (Cr) and nickel (Ni) contained in iron, but is not limited thereto. The second support layer 250 can be formed of a polymer, such as polymethyl methacrylate (PMMA), polycarbonate (PC), polyvinyl alcohol (PVA), acrylonitrile-butadiene-styrene (ABS), polyethylene terephthalate (PET), silicone, or polyurethane (PU).

[0106] As described above, since foldable display devices should be able to fold and unfold, the entire back panel, cover window, and display panel are configured as very thin films, and such thin film form vertically transmits most of the impacts transmitted from the outside.

[0107] For example, when an impact is transmitted from the outside to the cover window, the impact transmitted to the cover window is transmitted to the touch panel or display panel located below the cover window.

[0108] Therefore, the electrodes of the touch sensor in the touch panel or the components of the display panel are damaged. Therefore, the inventors have invented a new structure for a foldable display device to overcome the limitations described above.

[0109] The impact-absorbing layer 270 may be disposed below the first support layer 260. The impact-absorbing layer 270 can minimize the transmission of impacts applied from the outside to the touch panel or display panel 210. The impact-absorbing layer 270 may be formed of silicone, silicone foam, acrylic foam, polypropylene foam, polyurethane (PU), polyurethane foam, or thermoplastic polyurethane (TPU), but is not limited thereto.

[0110] Here, the shock absorption layer 270 has a thickness of 100 μm to 1000 μm. When the shock absorption layer has a thickness of less than 100 μm, the shock absorption capacity is not significant, and when the shock absorption layer has a thickness of more than 1000 μm, it may cause difficulties in folding the foldable display device.

[0111] However, the inventors have found weaknesses in the structure described above. Figure 4 It shows Figure 3 A photograph of the ball-dropping test results for the foldable display device. (See reference...) Figure 4 As can be seen, the folded area FA of the display panel 210 is damaged due to a point impact. Compared to the damage caused by a surface impact applied to the entire surface, a point impact—an impact applied to a localized area—can cause more damage to the display panel.

[0112] When a point impact is applied from the outside, in the non-folded area of ​​the first support layer without an opening pattern, the point impact is converted into a surface impact, thus effectively absorbing the impact. However, since the opening pattern exists in the folded area of ​​the first support layer to improve folding characteristics, when a point impact is applied to the upper part of the folded area, it cannot be converted into a surface impact, resulting in damage to the display panel or touch panel. Therefore, the inventors have recognized this problem and invented a new structure for the impact-absorbing layer.

[0113] Figure 5 This is a schematic cross-sectional view of a foldable display device 300 according to another embodiment of the present disclosure.

[0114] Reference Figure 5According to another exemplary embodiment of the present disclosure, a foldable display device 300 may include a display panel 310. A cover window 330 is positioned in front of the display panel 310. Additionally, a touch panel 320 is located between the display panel 310 and the cover window 330. The display panel 310 may include a folding region FA and non-folding regions NFA on both sides of the folding region FA. A back plate 340 is disposed below the display panel 310. A first support layer 360 has an opening pattern 361 in its portion corresponding to the folding region FA, and the first support layer 360 is disposed below the back plate 340. An impact-absorbing layer 370 is disposed below the first support layer 360. The impact-absorbing layer 370 includes a first portion 370-1 corresponding to the folding region FA and a second portion 370-2 corresponding to the non-folding region NFA. The impact-absorbing layer 370 may be formed of a material in which the modulus of the first portion 370-1 is higher than the modulus of the second portion 370-2. In other words, the first part 370-1 can be formed of a material with an elastic modulus greater than that of the second part 370-2. The various components are adhered and attached to each other by adhesives 380a, 380b, 390a, 390b, and 390c.

[0115] Part 370-1 may be formed from at least one of the following: silicone, silicone foam, acrylic foam, polypropylene foam, polyurethane (PU), polyurethane foam, and thermoplastic polyurethane (TPU).

[0116] The first part 370-1 has a modulus value of 1 MPa to 30 MPa and a thickness of 100 μm to 1000 μm. When the first part 370-1 has a thickness of less than 100 μm, the impact absorption capacity is not significant, and when the first part 370-1 has a thickness of more than 1000 μm, it may cause difficulties in folding the foldable display device 300.

[0117] Part 2 370-2 may be formed from at least one of the following: silicone, silicone foam, acrylic foam, polypropylene foam, polyurethane (PU), polyurethane foam, and thermoplastic polyurethane (TPU).

[0118] The second part 370-2 has a modulus value of 10 kPa to 1000 kPa and a thickness of 100 μm to 1000 μm. When the second part 370-2 has a thickness of less than 100 μm, the impact absorption capacity is not significant, and when the second part 370-2 has a thickness of more than 1000 μm, it may cause difficulties in folding the foldable display device 300.

[0119] [Table 1]

[0120]

[0121] Table 1 above shows the results of the ball drop test, indicating the height at which damage to the display panel occurs, depending on the modulus of the impact-absorbing layer 370 and the presence or absence of the opening pattern in the first support layer 360. Referring to Table 1 above, when the modulus of the first portion 370-1 with the opening pattern 361 is relatively high (4 MPa or 10 MPa), it can be determined that the height at which damage to the display panel 310 occurs when the ball falls is 10 cm or higher. However, when the modulus of the first portion 370-1 with the opening pattern 361 is relatively low (10 kPa or 20 kPa), it can be determined that damage to the display panel 310 occurs when the ball falls from a height of 2.5 cm. On the other hand, when the modulus of the second portion 370-2 without the opening pattern 361 is relatively high (4 MPa or 10 MPa), damage to the display panel 310 occurs when the ball falls from a height of 2.5 cm. However, when the modulus of the second part 370-2 without the opening pattern 361 is relatively low (10KPa or 20KPa), it is certain that damage to the display panel 310 will occur when the ball falls from a height of 15cm.

[0122] Therefore, in the foldable display device 300 according to the exemplary embodiment of this disclosure, an impact-absorbing layer 370 is provided such that the modulus of the first portion 370-1 of the impact-absorbing layer 370 corresponding to the folded region FA has a relatively large value (1 MPa to 30 MPa), and the modulus of the second portion 370-2 of the impact-absorbing layer 370 corresponding to the non-folded region NFA has a smaller value than the modulus of the first portion 370-1. Therefore, compared to a conventional foldable display device, even when an external impact is applied to the foldable display device 300, the impact is partially mitigated, thereby improving the impact resistance characteristics of the touch panel 320 or the display panel 310.

[0123] The second support layer 350 may also be included between the back plate 340 and the first support layer 360. The second support layer 350 can enhance the rigidity of the display panel 310. In addition, the second support layer 250 can be used to prevent the opening pattern 361 from being seen through the display panel 310.

[0124] The second support layer 350 may be formed of a metallic material, such as stainless steel (SUS), aluminum (Al), or magnesium (Mg). Stainless steel (SUS) includes iron (Fe) or other metals, such as chromium (Cr) and nickel (Ni) contained in iron, but is not limited thereto. The second support layer 350 may be formed of a polymer, such as polymethyl methacrylate (PMMA), polycarbonate (PC), polyvinyl alcohol (PVA), acrylonitrile-butadiene-styrene (ABS), polyethylene terephthalate (PET), silicone, or polyurethane (PU).

[0125] Meanwhile, in the description so far, a touch panel 320 has been positioned above the display panel 310 on which images are displayed in the foldable display device 300. However, the touch panel 320 can be removed.

[0126] A foldable display device 300 according to another embodiment of the present disclosure may include a display panel 310. The display panel 310 may include a folding region FA and non-folding regions NFA on both sides of the folding region FA. A first support layer 360 has an opening pattern 361 in its portion corresponding to the folding region FA, and the first support layer 360 may be located below the display panel 310. An impact-absorbing layer 370 is disposed below the first support layer 360. The impact-absorbing layer 370 includes a first portion 370-1 corresponding to the folding region FA and a second portion 370-2 corresponding to the non-folding region NFA. In the impact-absorbing layer 370, the modulus of the first portion 370-1 is greater than the modulus of the second portion 370-2, to reduce damage to the display panel 310 caused by point impacts applied to the folding region FA.

[0127] The first portion 370-1 can convert point impacts applied to the folded area FA of the display panel 310 into surface impacts to prevent shape deformation of the folded area FA. The opening pattern 361 is not formed in the first support layer 360 corresponding to the second portion 370-2. Therefore, the first support layer 360 can convert point impacts applied from the outside into surface impacts. However, since the opening pattern 361 is formed in the first support layer 360 corresponding to the first portion 370-1 to improve folding characteristics, point impacts cannot be converted into surface impacts due to the opening pattern 361. Therefore, the first portion 370-1 corresponding to the opening pattern 361 has a high modulus value to convert point impacts into surface impacts. That is, the first portion 370-1 can be formed of a material with an elastic modulus greater than that of the second portion 370-2.

[0128] Part 370-1 may be formed from at least one of the following: silicone, silicone foam, acrylic foam, polypropylene foam, polyurethane (PU), polyurethane foam, and thermoplastic polyurethane (TPU).

[0129] The first part 370-1 has a modulus value of 1 MPa to 30 MPa and a thickness of 100 μm to 1000 μm. When the first part 370-1 has a thickness of less than 100 μm, the impact absorption capacity is not significant, and when the first part 370-1 has a thickness of more than 1000 μm, it may cause difficulties in folding the foldable display device 300.

[0130] Part 2 370-2 may be formed from at least one of the following: silicone, silicone foam, acrylic foam, polypropylene foam, polyurethane (PU), polyurethane foam, and thermoplastic polyurethane (TPU).

[0131] The second part 370-2 has a modulus value of 10 kPa to 1000 kPa and a thickness of 100 μm to 1000 μm. When the second part 370-2 has a thickness of less than 100 μm, the impact absorption capacity is not significant, and when the second part 370-2 has a thickness of more than 1000 μm, it may cause difficulties in folding the foldable display device 300.

[0132] In the foldable display device 300 according to an exemplary embodiment of the present disclosure, the first portion 370-1 of the impact-absorbing layer 370 corresponding to the folded area FA of the display panel 310 is formed of a material with a high modulus. Therefore, even when a point impact is applied to the folded area FA, the point impact is converted into a surface impact, making it more effective to prevent damage to the display panel 310 or the touch panel 320 from point impacts. Thus, the impact resistance characteristics of the display device 300 can be improved.

[0133] Although exemplary embodiments of the present disclosure have been described in detail with reference to the accompanying drawings, the present disclosure is not limited thereto, and the present disclosure can be implemented in many different forms without departing from the technical concept of the present disclosure. Therefore, the exemplary embodiments of the present disclosure are provided for illustrative purposes only and are not intended to limit the technical concept of the present disclosure. The scope of the technical concept of the present disclosure is not limited thereto. Therefore, it should be understood that the above exemplary embodiments are illustrative in all respects and do not limit the present disclosure. The scope of protection of the present disclosure should be interpreted based on the appended claims, and all technical concepts within their equivalent scope should be interpreted as falling within the scope of the present disclosure.

[0134] Inventive concept

[0135] This invention provides the following inventive concept:

[0136] 1. A foldable display device, comprising:

[0137] The display panel includes a folded area and non-folded areas on both sides of the folded area;

[0138] A back panel is located below the display panel;

[0139] A first support layer is disposed below the back plate;

[0140] Includes an opening pattern in the first support layer, the opening pattern being arranged in a portion corresponding to the folded area; and

[0141] A second support layer is disposed between the first support layer and the back plate.

[0142] Wherein, the second support layer overlaps with the opening pattern, and

[0143] The second support layer comprises a polymer.

[0144] 2. The foldable display device according to inventive concept 1 further includes: an impact-absorbing layer disposed below the first support layer.

[0145] The impact-absorbing layer includes a first portion corresponding to the folded region and a second portion corresponding to the non-folded region.

[0146] The modulus of the first part is greater than that of the second part.

[0147] 3. The foldable display device according to inventive concept 1, wherein the second support layer and the first support layer are bonded to each other by an adhesive.

[0148] 4. The foldable display device according to inventive concept 1, wherein the second support layer and the back plate are bonded to each other by an adhesive.

[0149] 5. The foldable display device according to inventive concept 2, wherein the first part is formed of a material with an elastic modulus greater than that of the second part.

[0150] 6. The foldable display device according to inventive concept 2, wherein the first part and the second part comprise any one of the following materials: silicone, acrylic foam, polypropylene foam and polyurethane.

[0151] 7. The foldable display device according to inventive concept 6, wherein the silicone comprises silicone foam, and the polyurethane comprises polyurethane foam and thermoplastic polyurethane.

[0152] 8. The foldable display device according to inventive concept 1, wherein the second support layer comprises any one of stainless steel, aluminum, or magnesium containing iron and other metals.

[0153] 9. The foldable display device according to inventive concept 1, wherein the opening pattern reduces the folding stress in the folding area to prevent damage to the display panel.

[0154] 10. A foldable display device, comprising:

[0155] The display panel includes a folded area and one or more non-folded areas located adjacent to each side of the folded area;

[0156] A first support layer is disposed below the display panel;

[0157] The opening pattern is included in the first support layer and is arranged at an overlapping position corresponding to the folded area.

[0158] 11. The foldable display device according to inventive concept 10 further includes: an impact-absorbing layer disposed below the first support layer, and comprising a first portion corresponding to the folding region and a second portion corresponding to the non-folding region.

[0159] The modulus of the first part is greater than that of the second part, so as to reduce the damage to the display panel caused by point impacts applied to the folded area.

[0160] 12. The foldable display device according to inventive concept 11, wherein the first part converts the point impact applied to the folding area of ​​the display panel into a surface impact to prevent shape deformation of the folding area.

[0161] 13. The foldable display device according to inventive concept 11, wherein the second portion is not subjected to point impacts on the first support layer corresponding to the second portion.

[0162] 14. The foldable display device according to inventive concept 11, wherein the first portion is formed of a material having an elastic modulus greater than that of the second portion.

[0163] 15. The foldable display device according to inventive concept 14, wherein the first part and the second part comprise any one of the following materials: silicone, acrylic foam, polypropylene foam and polyurethane.

[0164] 16. The foldable display device according to inventive concept 15, wherein the silicone comprises silicone foam, and the polyurethane comprises polyurethane foam and thermoplastic polyurethane.

[0165] 17. The foldable display device according to inventive concept 10 further includes: a second support layer between the display panel and the first support layer.

[0166] 18. A foldable display device, comprising:

[0167] The display panel includes a folded area and non-folded areas on both sides of the folded area;

[0168] A cover window is positioned above the display panel to protect the display panel;

[0169] A touch panel is disposed between the display panel and the cover window;

[0170] A back panel is located below the display panel;

[0171] A first support layer is disposed below the back plate;

[0172] Includes an opening pattern in the first support layer, the opening pattern being arranged in a portion of the first support layer corresponding to the folded region; and

[0173] A second support layer is disposed between the back plate and the first support layer.

[0174] Wherein, the second support layer overlaps with the opening pattern, and

[0175] The second support layer comprises a polymer.

[0176] 19. The foldable display device according to inventive concept 18 further includes: an impact-absorbing layer disposed below the first support layer, and comprising a first portion corresponding to the folding region and a second portion corresponding to the non-folding region.

[0177] The modulus of the first part is greater than that of the second part.

[0178] 20. The foldable display device according to inventive concept 19, wherein the first portion is formed of a material having an elastic modulus greater than that of the second portion.

Claims

1. A foldable display device, comprising: The display panel includes a folded area and non-folded areas on both sides of the folded area; A back panel is located below the display panel; A first support layer is disposed below the back plate; The opening pattern is included in the first support layer and is arranged in the portion corresponding to the folded area; A second support layer is disposed between the first support layer and the back plate; as well as An impact-absorbing layer is disposed below the first support layer. The second support layer overlaps with the opening pattern. The second support layer comprises a polymer, and The impact-absorbing layer includes a first portion corresponding to the folded region and a second portion corresponding to the unfolded region. The modulus of the first part is greater than that of the second part. 2.The foldable display apparatus of claim 1, wherein, The second support layer and the first support layer are bonded to each other by an adhesive. 3.The foldable display apparatus of claim 1, wherein, The second support layer and the back plate are bonded together by an adhesive. 4.The foldable display apparatus of claim 1, wherein, The first part is formed of a material whose elastic modulus is greater than that of the second part. 5.The foldable display apparatus of claim 1, wherein, The first part and the second part comprise any one of the following materials: silicone, acrylic foam, polypropylene foam and polyurethane. 6.The foldable display apparatus of claim 5, wherein, The silicone includes silicone foam, and the polyurethane includes polyurethane foam and thermoplastic polyurethane. 7.The foldable display apparatus of claim 1, wherein, The second support layer comprises any one of stainless steel, aluminum, or magnesium, which contains iron and other metals. 8.The foldable display apparatus of claim 1, wherein, The opening pattern reduces the folding stress in the folded area to prevent damage to the display panel.

9. A foldable display device, comprising: An OLED panel comprising a folded region and one or more non-folded regions located adjacent to each side of the folded region; A first support layer is disposed beneath the OLED panel; The opening pattern included in the first support layer is arranged at an overlapping position corresponding to the folded area; as well as An impact-absorbing layer is disposed beneath the first support layer and includes a first portion corresponding to the folded region and a second portion corresponding to the non-folded region. The modulus of the first part is greater than that of the second part. 10.The foldable display apparatus of claim 9, wherein, The first part converts the point impact applied to the folded area of ​​the OLED panel into a surface impact to prevent deformation of the folded area. 11.The foldable display apparatus of claim 9, wherein, The second part is not subject to point impacts from the corresponding first support layer. 12.The foldable display apparatus of claim 9, wherein, The first part is made of a material with a higher elastic modulus than the second part to reduce damage to the OLED panel caused by point impacts applied to the folded area. 13.The foldable display apparatus of claim 12, wherein, The first and second portions comprise any material selected from silicone, acrylic foam, polypropylene foam, and polyurethane. 14.The foldable display apparatus of claim 13, wherein, The silicone includes silicone foam, and the polyurethane includes polyurethane foam and thermoplastic polyurethane. 15.The foldable display apparatus of claim 9, further comprising: A second support layer between the OLED panel and the first support layer.

16. A foldable display device, comprising: The display panel includes a folded area and non-folded areas located on both sides of the folded area; a cover window disposed above the display panel to protect the display panel; a touch panel disposed between the display panel and the cover window; a back plate disposed below the display panel; a first support layer disposed below the back plate; an opening pattern included in the first support layer, the opening pattern being arranged in a portion of the first support layer corresponding to the folding area; a second support layer disposed between the back plate and the first support layer; and a shock absorbing layer disposed below the first support layer and including a first portion corresponding to the folding area and a second portion corresponding to the non-folding area, wherein the second support layer overlaps the opening pattern, and the second support layer includes a polymer; and wherein a modulus of the first portion is greater than a modulus of the second portion. The first portion is made of a material having a greater modulus of elasticity than the second portion. 17.The foldable display apparatus of claim 16, wherein, ​

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