Foldable display device

Abstract

A foldable display device is disclosed, comprising: a display panel configured to display an image, a cover window above the display panel, a back plate below the display panel, and a first guide, a second guide, and a third guide supporting the back plate, wherein the back plate has an Omega letter-shaped cross section in an inward folding operation about a folding axis, the display surface of the display panel being hidden inside in the inward folding operation, wherein the second guide contacts one of the Omega letter-shaped side surfaces to support the back plate in the inward folding operation, and wherein the third guide contacts the lower surface of the Omega letter-shaped structure to support the back plate in the inward folding operation.

Description

[0001] This application is a divisional application of patent application No. 202211455007.3, filed on November 21, 2022, entitled "Foldable Display Device".

[0002] Cross-reference to related applications

[0003] This application claims priority to Korean Patent Application No. 10-2021-0161540, filed on November 22, 2021, the entire contents of which are incorporated herein by reference. Technical Field

[0004] This disclosure relates to foldable display devices, and more specifically, to foldable display devices that perform bi-directional folding. Background Technology

[0005] As information-driven societies advance, the demand for display devices for displaying images has increased in various forms. In the field of display devices, the relatively large cathode ray tube (CRT) has been rapidly replaced by flat panel display (FPD) devices, which are thinner, lighter, and consume less power, and are suitable for relatively larger sizes. FPD devices include liquid crystal display (LCD) devices, plasma display panels (PDP), organic light-emitting diode (OLED) display devices, and field emission display (FED) devices.

[0006] Furthermore, flexible display devices, which can be freely folded and unfolded by forming transistors and wires on flexible substrates, have become the subject of next-generation display devices.

[0007] Flexible display devices can be categorized into foldable display devices, bendable display devices, and rollable display devices.

[0008] Furthermore, foldable display devices can be either inward-folding (where the display surface is hidden inside when folded) or outward-folding (where the display surface is exposed on the outside when folded). Typically, foldable display devices can have a unidirectional folding type, which stably performs only one of the inward or outward folding motions.

[0009] Therefore, bidirectional foldable display devices have been researched and developed, which selectively perform inward and outward folding within the same folding area. In the bidirectional type, the accuracy of reproducing the folded shape is reduced because the inward and outward folding are performed in opposite directions.

[0010] For example, due to the deformation of the inward fold having an omega shape, an abnormal fold shape of the outward fold can be observed, or due to the deformation of the outward fold, an abnormal omega shape of the inward fold can be observed. Summary of the Invention

[0011] Therefore, this disclosure relates to foldable display devices that substantially eliminate one or more problems caused by the limitations and disadvantages of the prior art.

[0012] Furthermore, this disclosure provides a bidirectional foldable display device in which multiple holes are formed in the top of the back panel and at least one groove is formed in the bottom of the back panel, thereby minimizing the transmission of deformation caused by folding stress to the display panel and improving the accuracy of reproducing the folded shape.

[0013] Furthermore, this disclosure provides a foldable display device in which a precise inward-folding Omega shape is obtained and stress on the folding shoulder area is minimized by adjusting the width of the hole area, the inward folding area and the outward folding area of ​​the back plate.

[0014] Additional features and advantages of this disclosure will be set forth in the description which follows, and will become apparent in part from that description, or may be learned by practice of this disclosure. These and other advantages of this disclosure will be realized and obtained through the written description and the structures particularly pointed out in the claims herein and the accompanying drawings.

[0015] To achieve these and other advantages and for the purposes of this disclosure, as embodied and broadly described herein, a foldable display device includes: a display panel configured to display an image; a cover window above the display panel; and a back panel below the display panel, the back panel including a top panel having a plurality of holes, a bottom panel having at least one recess corresponding to the plurality of holes, and an adhesive layer joining the top panel and the bottom panel.

[0016] In another aspect, a foldable display device includes: a display panel configured to display an image; a top plate below the display panel, the top plate including a plurality of holes; and a bottom plate below the top plate, the bottom plate including at least one groove corresponding to the plurality of holes, wherein the top plate and the bottom plate have an omega-shaped cross section in an inward folding operation about a folding axis, in which the display surface of the display panel is hidden inside, and wherein the top plate and the bottom plate have a U-shaped cross section in an outward folding operation about a folding axis, in which the display surface of the display panel is exposed to the outside.

[0017] On the other hand, a foldable display device includes: a display panel configured to display an image, and a back panel below the display panel. The back panel includes: a top panel having a plurality of holes disposed in a hole region; a bottom panel having a plurality of grooves disposed in a recess region; and an adhesive layer that bonds the top panel and the bottom panel, wherein the foldable display device performs bidirectional folding about a folding axis.

[0018] It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory, and are intended to provide further explanation of the claimed disclosure. Attached Figure Description

[0019] The accompanying drawings are included to provide a further understanding of this disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate various aspects of this disclosure and, together with the specification, serve to illustrate the principles of this disclosure.

[0020] In the attached diagram:

[0021] Figure 1 This is a plan view illustrating a foldable display device according to a first embodiment of the present disclosure;

[0022] Figure 2 It is along Figure 1 A cross-sectional view taken from line II-II;

[0023] Figure 3A and Figure 3B These are cross-sectional views showing the inward folding operation and the outward folding operation of the foldable display device according to the first embodiment of the present disclosure, respectively.

[0024] Figure 4 This is a plan view showing the top of the back panel of a foldable display device according to a first embodiment of the present disclosure;

[0025] Figures 5 to 7 These are plan views showing the top of the back panel of the foldable display device according to the second to fourth embodiments of the present disclosure;

[0026] Figure 8 It is a graph showing the strain of the cover window of the hole area width of the back panel of the foldable display device according to the first embodiment of the present disclosure.

[0027] Figure 9 This is a table showing the Omega shape formed by the width of the perforated area of ​​the back panel of the foldable display device according to the first embodiment of this disclosure;

[0028] Figure 10 This is a cross-sectional view showing a foldable display device according to a fifth embodiment of the present disclosure; and

[0029] Figure 11 This is a cross-sectional view showing a foldable display device according to a sixth embodiment of the present disclosure. Detailed Implementation

[0030] Reference will now be made in detail to various aspects of this disclosure, examples of which are illustrated in the accompanying drawings. In the following description, detailed descriptions of well-known functions or configurations relevant to this document will be omitted where such obscuration unnecessarily obscures the essential points of the inventive concept. The described progression of processing steps and / or operations is exemplary; however, the order of steps and / or operations is not limited to the order described herein, except that they must occur in a specific order, and may be varied as is known in the art. Throughout the document, the same reference numerals denote the same elements. The names of the various elements used in the following description are chosen solely for convenience of writing the specification and may therefore differ from the names used in actual products.

[0031] The advantages and features of this disclosure and its implementation methods will be illustrated by the following exemplary embodiments described with reference to the accompanying drawings. However, this disclosure may be implemented in different forms and should not be construed as limited to the exemplary aspects set forth herein. Rather, these exemplary aspects are provided so that this disclosure may be sufficiently thorough and complete to assist those skilled in the art in fully understanding its scope. Furthermore, this disclosure is limited only by the scope of the claims.

[0032] The shapes, dimensions, scales, angles, and quantities disclosed in the accompanying drawings used to describe various aspects of this disclosure are merely examples. Therefore, this disclosure is not limited to the details shown. Throughout the text, the same reference numerals refer to the same elements. In the following description, detailed descriptions of known functions or configurations may be omitted where such omission would unnecessarily obscure the focus of this disclosure. Where the terms “comprising,” “having,” and “including” are used as described in this specification, another component may be added unless further restrictive terms such as “only” are used. Singular terms may include plural forms unless otherwise indicated.

[0033] When interpreting components, even if the error or tolerance range is not explicitly described, the component is interpreted as including such an error or tolerance range. When describing positional relationships, when the positional relationship between two parts is described as, for example, "on," "above," "below," and "adjacent," one or more other parts may be arranged between these two parts unless more restrictive terms such as "only" or "directly" are used.

[0034] When describing temporal relationships, when the temporal order is described as, for example, “after,” “following,” “next,” and “before,” discontinuous situations may be included unless more restrictive terms such as “immediately after,” “immediately,” or “directly” are used.

[0035] It will be understood that although the terms “first,” “second,” etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of this disclosure, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0036] In describing the elements of this disclosure, terms such as “first,” “second,” “A,” “B,” “(a),” and “(b)” may be used. These terms are used only to distinguish one element from another, and the nature, order, sequence, or number of the respective elements should not be defined by these terms. Furthermore, when an element or layer is described as “connected,” “coupled,” or “attached” to another element or layer, unless otherwise specified, the element or layer may be directly connected or attached to other elements or layers, or indirectly connected or attached to other elements or layers, wherein one or more intervening elements or layers are “disposed” between these elements and layers.

[0037] The term "at least one" should be understood to include any one and all combinations of one or more items listed in connection with the terms. For example, "at least one of the first, second and third items" means all combinations of items derived from two or more of the first, second and third items, as well as the first, second or third item.

[0038] In the descriptions of various aspects, when a structure is described as being "above" or "below" or "under" another structure, the description should be interpreted to include cases where these structures are in contact with each other and cases where a third structure is disposed therebetween. The dimensions and thicknesses of each element shown in the accompanying drawings are given merely for ease of description, and the aspects of this disclosure are not limited thereto.

[0039] The various aspects of this disclosure may be coupled or combined with each other, either partially or in whole, and may interoperate with each other and be technically driven, as will be fully understood by those skilled in the art. The aspects of this disclosure may be implemented independently of each other or may be implemented together in an interdependent relationship.

[0040] Reference will now be made in detail to this disclosure, examples of which are shown in the accompanying drawings.

[0041] Figure 1 This is a plan view illustrating a foldable display device according to a first embodiment of the present disclosure. Figure 2 It is along Figure 1 The cross-sectional view taken from line II-II.

[0042] exist Figure 1 and Figure 2 In the first embodiment of the present disclosure, the foldable display device 110 includes a display panel 120, a cover window 130, and a back panel 140.

[0043] The foldable display device 110 selectively performs an inward folding operation relative to the folding axis FX and an outward folding operation relative to the folding axis FX. In the inward folding operation, the display surface of the display panel 120 is hidden inside, and in the outward folding operation, the display surface of the display panel 120 is exposed to the outside.

[0044] The foldable display device 110 includes an inner folding region IFA, which is a curved portion for an inward folding operation; an outer folding region OFA, which is a curved portion for an outward folding operation; and a non-folding region NFA, which is a non-curved portion for both the inward and outward folding operations and is disposed outside the outer folding region OFA.

[0045] For example, the second width w2 of the inner folded region IFA along the direction perpendicular to the folding axis FX can be smaller than the third width w3 of the outer folded region OFA along the direction perpendicular to the folding axis FX (w2 < w3).

[0046] The display panel 120 uses multiple pixels to display images and includes gate lines, data lines, thin-film transistors, and capacitors.

[0047] The display panel 120 includes a display area DA for displaying images and a non-display area NDA surrounding the display area DA.

[0048] For example, display panel 120 may include an organic light-emitting diode panel or a liquid crystal panel.

[0049] When the display panel 120 is an organic light-emitting diode (OLED) panel, each pixel may include a switching thin-film transistor (TFT), a driving TFT, a storage capacitor, and an OLED. When the display panel 120 is a liquid crystal panel (LCD), each pixel may include a thin-film transistor (TFT), a storage capacitor, and a liquid crystal capacitor.

[0050] Cover window 130 is disposed on display panel 120 and protects display panel 120 from external impact, external moisture and external heat. Cover window 130 may include glass or plastic, such as polymethyl methacrylate (PMMA), polyimide (PI) and polyethylene terephthalate (PET).

[0051] Although not shown, a transparent adhesive layer and a polarizing layer may be disposed between the display panel 120 and the cover window 130.

[0052] The back panel 140 supports the display panel 120 and protects the display panel 120 from external impacts, external moisture and external heat. The back panel 140 includes a top panel 142, an adhesive layer 144 and a bottom panel 146 disposed sequentially below the display panel 120.

[0053] The top 142 of the board increases the flexibility of the entire back panel 140. The first thickness t1 of the top 142 of the board can be less than the third thickness t3 of the bottom 146 of the board.

[0054] The top of the plate 142 includes a plurality of holes 142a symmetrically arranged in the hole region HA relative to the folding axis FX. The hole region HA can form an inner folding region IFA, which has relatively weaker stiffness than the non-folding region NFA due to the plurality of holes 142a and bends during the inner folding operation.

[0055] Therefore, by adjusting the first width w1 of the hole region HA, the inner folding region IFA can have an omega (Ω) shape during the inner folding operation, and can make ( Figure 3A The stress in the folded shoulder region FSA is minimized, which is part of the maximum tensile force.

[0056] The first width w1 of the hole region HA along the direction perpendicular to the folding axis FX can be smaller than the second width w2 of the inner fold region IFA along the direction perpendicular to the folding axis FX (w1 < w2).

[0057] For example, the first thickness t1 of the top 142 of the plate can be in the range of about 10 μm to about 100 μm (preferably in the range of about 10 μm to about 30 μm).

[0058] When the first thickness t1 of the top 142 of the board is greater than about 100 μm, the folding stress increases, and multiple holes 142a become identifiable from the front of the display panel 120. When the first thickness t1 of the top 142 of the board is less than about 10 μm, the constraint on the deformation of the inward folding area IFA decreases.

[0059] For example, the top of the plate 142 may include stainless steel, amorphous metal, amorphous silicon, Invar, laminates thereof, alloys thereof, and coatings thereof.

[0060] Stainless steel is formed by alloying iron (Fe) with chromium (Cr) and nickel (Ni) to improve the corrosion resistance of iron (Fe). Stainless steel can selectively include nickel (Ni) depending on its type, and the elasticity of stainless steel can be adjusted according to the composition ratio of chromium (Cr).

[0061] Stainless steel can be divided into ferritic stainless steel (iron-chromium group) and austenitic stainless steel (iron-nickel-chromium group).

[0062] Amorphous metals are formed by the condensation of amorphously arranged metal atoms, similar to glass or a liquid. When a metallic material is rapidly cooled, crystal growth is inhibited, resulting in the formation of amorphous metals. Amorphous metals can possess superior corrosion resistance and elasticity compared to crystalline metals.

[0063] Amorphous silicon exhibits irregularities similar to those of amorphous metals. Amorphous silicon can also possess superior elasticity compared to amorphous metals.

[0064] Invar is an alloy of iron (Fe) and nickel (Ni) and possesses excellent corrosion resistance and tensile strength. Depending on whether it contains chromium (Cr), Invar can be compared to stainless steel.

[0065] Stainless steel and Invar can possess excellent rigidity, while amorphous metals and amorphous silicon can possess excellent elasticity. The internal bonding degree and rigidity can be controlled by adjusting the composition ratio of the metal alloy or the cooling rate.

[0066] Adhesive layer 144 bonds the top 142 and the bottom 146 of the board. For example, adhesive layer 144 may include a curable resin such as epoxy resin, silicone resin, polyester resin, polyurethane resin, and phenolic resin.

[0067] For example, the second thickness t2 of the adhesive layer 144 can be in the range of about 5 μm to about 100 μm, preferably in the range of about 15 μm to about 50 μm.

[0068] When the second thickness t2 of the adhesive layer 144 is greater than about 100 μm, the stress on the top of the board 142 is not reduced under reliability conditions. When the second thickness t2 of the adhesive layer 144 is less than about 5 μm, the adhesion between the top of the board 142 and the bottom of the board 146 is reduced and may deteriorate, such as separation due to folding stress.

[0069] The bottom of the plate 146 includes at least one groove 146a symmetrically disposed in the grooved region GA with respect to the folding axis FX. Due to the at least one groove 146a, the grooved region GA can have relatively weak stiffness compared to the non-folded region NFA, and can form an outward folded region OFA that bends during outward folding operations.

[0070] Therefore, the boundary between the non-folded region NFA and the outward folded region OFA can be suppressed during the outward folding operation by adjusting the fourth width w4 of the groove region GA, and the back plate 140 can be made more flexible during the outward folding operation by adjusting the fourth thickness t4 of the bottom plate 146 of the central portion of the groove region GA.

[0071] The fourth width w4 of the groove region GA along the direction perpendicular to the folding axis FX can be equal to or greater than the third width w3 of the outer folding region OFA along the direction perpendicular to the folding axis FX, and can be equal to or less than 1.2 times the third width w3 of the outer folding region OFA. The boundary of at least one groove region GA, starting from groove 146a, can be set in the non-folded region NFA.

[0072] When the fourth width w4 of the groove region GA is less than the third width w3 of the outer folded region OFA, the boundary between the non-folded region NFA and the outer folded region OFA may be identified. When the fourth width w4 of the groove region GA is greater than 1.2 times the third width w3 of the outer folded region OFA, the impact resistance and reliability may deteriorate.

[0073] For example, the third thickness t3 of the bottom 146 of the plate can be in the range of about 10 μm to about 200 μm, preferably in the range of about 50 μm to about 120 μm.

[0074] When the third thickness t3 of the bottom plate 146 is greater than approximately 200 μm, the thickness of the foldable display device 110 increases. When the third thickness t3 of the bottom plate 146 is less than approximately 10 μm, the boundary between the outwardly folded area OFA and the non-folded area NFA may be identified.

[0075] The fourth thickness t4 (the minimum thickness of the bottom plate 146) at the central portion of the groove region GA can be equal to or less than the fifth thickness t5 (t4 ≤ t5), which is equal to the maximum depth of at least one groove 146a in the central portion of the groove region GA.

[0076] When the fourth thickness t4 is greater than the fifth thickness t5, the boundary between the folded region OFA and the non-folded region NFA may be identified due to the stress of the outward folding operation.

[0077] The bottom plate 146 may include a material with a relatively high modulus of elasticity. For example, the bottom plate 146 may include a material with the same family as the top plate 142 but a different alloy composition ratio.

[0078] The inward and outward folding operations of the foldable display device 110 will now be described with reference to the accompanying drawings.

[0079] Figure 3A and Figure 3B These are cross-sectional views showing the inward folding operation and the outward folding operation of the foldable display device according to the first embodiment of this disclosure.

[0080] exist Figure 3A and Figure 3BIn the first embodiment of the present disclosure, the foldable display device 110 includes a display panel 120, a cover window 130, a back plate 140, a housing 150, and first, second, and third guides 152, 154, and 156.

[0081] The first, second, and third guides 152, 154, and 156 are disposed between the back plate 140 and the housing 150, and support the back plate 140 during inward and outward folding operations.

[0082] exist Figure 3A During the inward folding operation in which the display surface of the display panel 120 is hidden inside, the inward folding area IFA of the back panel 140 has an omega (Ω) shaped cross section due to the multiple holes 142a on the top 142 of the back panel 140. Therefore, the cover window 130 and the display panel 120 have an omega shaped cross section.

[0083] The folding stress has a maximum value in the folding shoulder region FSA at the boundary between the inner folding region IFA where the back plate 140 deforms and the non-folding region NFA where the back plate 140 does not deform.

[0084] Two second guides 154 slide from two first guides 152 respectively and contact the two omega-shaped side surfaces of the inner folded area IFA of the back panel 140 to support the back panel 140.

[0085] The third guide 156 contacts the inner surface of the housing 150 and the omega-shaped lower surface of the inward folding area IFA of the back plate 140 to support the back plate 140.

[0086] exist Figure 3B During the outward folding operation where the display surface of the display panel 120 is exposed to the outside, the outward folding area OFA of the back panel 140 has a U-shaped cross-section due to at least one groove 146a on the bottom 146 of the back panel 140. Therefore, the cover window 130 and the display panel 120 have a U-shaped cross-section.

[0087] The two second guides 154 slide to the two first guides 152 respectively and separate from the back plate 140.

[0088] The third guide 156 separates from the inner surface of the housing 150 and contacts the U-shaped outward folded area OFA of the back plate 140 to support the back plate 140.

[0089] The following description will refer to the accompanying drawings to illustrate the plurality of holes 142a on the top 142 of the back panel 140 of the foldable display device 110.

[0090] Figure 4 This is a plan view showing the top of the back panel of a foldable display device according to a first embodiment of the present disclosure.

[0091] exist Figure 4 In the first embodiment of the foldable display device 110 according to the present disclosure, the top 142 of the back panel 140 includes a plurality of holes 142a disposed in the hole region HA.

[0092] Multiple holes 142a provide flexibility to the top of the plate 142 during the folding operation, allowing the top of the plate 142 to be flexibly bent. The multiple holes 142a absorb the compressive and tensile stresses of the folding operation, allowing the top of the plate 142 to easily return to its original shape.

[0093] Each of the plurality of holes 142a comprises a rectangular shape. The plurality of holes 142a are separated from each other and arranged in a matrix. Holes 142a in adjacent rows are arranged to partially overlap each other, and holes 142a in adjacent columns are arranged to be separated from each other.

[0094] The first distance d1, which is the width of the short side of the rectangle of each hole 142a, can be equal to or less than the second distance d2 (d1 ≤ d2), where the second distance d2 is the spacing between the long sides of the rectangles of two adjacent holes 142a. The third distance d3, which is the width of the long side of the rectangle of each hole 142a, can be greater than the fourth distance d4 (d3 > d4), where the fourth distance d4 is the spacing between the short sides of the rectangles of two adjacent holes 142a.

[0095] For example, each of the first and second distances d1 and d2 can be in the range of about 20 μm to about 500 μm, preferably in the range of about 50 μm to about 300 μm, and each of the third and fourth distances d3 and d4 can be in the range of about 0.1 mm to about 10 mm, preferably in the range of about 0.5 mm to about 7 mm.

[0096] When one of the first and second distances d1 and d2 is less than about 20 μm or greater than about 500 μm, and one of the third and fourth distances d3 and d4 is less than about 0.1 mm or greater than about 10 mm, the flexibility of the hole region HA at the top of the panel 142 decreases. Therefore, under reliability conditions, the folding characteristics may deteriorate or the display panel 120 may deform.

[0097] Although the long side of the rectangular shape of each hole 142a is parallel to Figure 4 In another embodiment, the long side of the rectangular shape of each hole 142a can be set in a direction perpendicular to the folding axis FX.

[0098] In another embodiment, the multiple holes can have various shapes and be arranged in various ways.

[0099] Figures 5 to 7 These are plan views showing the top of the back panel of the foldable display device according to the second to fourth embodiments of this disclosure. Descriptions of parts identical to those in the first embodiment will be omitted.

[0100] exist Figure 5 In the second embodiment of the present disclosure, the top 242 of the back panel of the foldable display device includes a plurality of holes 242a in the hole region HA.

[0101] Each of the plurality of holes 242a can be a rectangular shape with rounded corners or an elliptical shape with a minor axis of constant length.

[0102] The arrangement shape of the plurality of holes 242a in the second embodiment and the relationship between the first to fourth distances can be the same as in the first embodiment.

[0103] exist Figure 6 In the third embodiment of the foldable display device according to the present disclosure, the top 342 of the back panel includes a plurality of holes 342a in the hole region HA.

[0104] Each of the plurality of holes 342a may have a rhomboid shape, and the plurality of holes 342a are arranged in a matrix to be separated from each other. Holes 342a in adjacent rows are arranged to be separated from each other, and holes 342a in adjacent columns are arranged to be separated from each other.

[0105] Although the major axis of the rhomboid shape of each hole 342a is set to be parallel to Figure 6 The orientation of the folding axis FX is specified, but in another embodiment, the long axis of the rhomboid shape of each hole 342a can be set in a direction perpendicular to the folding axis FX.

[0106] exist Figure 7 In the fourth embodiment of the present disclosure, the top 442 of the back panel of the foldable display device includes a plurality of holes 442a in the hole region HA.

[0107] Each of the plurality of holes 442a may have a rectangular shape, and the plurality of holes 442a are arranged in a matrix to be separated from each other. Holes 442a in adjacent rows are arranged to overlap each other, and holes 442a in adjacent columns are arranged to be separated from each other.

[0108] Each of the second distance d2, which is the spacing between the long sides of the rectangular shapes of two adjacent holes 442a, and the fourth distance d4, which is the spacing between the short sides of the rectangular shapes of two adjacent holes 442a, can decrease from the edge portion to the center portion of the hole region HA in a direction perpendicular to the folding axis FX. Furthermore, each of the first distance d1, which is the width of the short side of the rectangular shape of each hole 442a, and the third distance d3, which is the width of the long side of the rectangular shape of each hole 442a, can increase from the edge portion to the center portion of the hole region HA in a direction perpendicular to the folding axis FX.

[0109] Multiple holes 442a can be configured such that the stiffness of the top of the plate 442 decreases from the edge portion to the central portion of the hole region HA in a direction perpendicular to the folding axis FX.

[0110] In the first to fourth embodiments, by adjusting the width of the hole area, the stress in the folded shoulder area was reduced and an Omega shape was obtained.

[0111] Figure 8 This is a graph showing the strain of the cover window relative to the width of the hole area on the back panel of the foldable display device according to a first embodiment of the present disclosure. Figure 9 It is a table in the shape of an omega based on the width of the hole area on the back panel of the foldable display device according to the first embodiment of this disclosure.

[0112] exist Figure 8 and Figure 9 In the reference sample, there is a backplate without multiple holes, and samples A, B, C, D, E, and F have a first width w1 of hole region HA of about 1.1 mm, about 2.9 mm, about 4.3 mm, about 5.9 mm, about 9.89 mm, and about 15.89 mm, respectively.

[0113] For the reference sample and samples A, B, C, D, E, and F, an inward folding operation is performed with the radius of curvature of the inner folded region IFA ranging from 1R (1 mm) to 3R (3 mm), and an outward folding operation is performed with the radius of curvature of the outer folded region OFA ranging from 3R (3 mm) to 5R (5 mm). During the inward folding operation, the coverage window 130 of the reference sample and samples A, B, C, D, E, and F has a non-zero strain in the inner folded region IFA, a zero strain in the non-folded region NFA, and a negative strain with the maximum absolute value at the folding axis FX.

[0114] In addition, the reference sample and samples A, B, C, D, E, and F have tensile strains of approximately 0.1%, approximately 0.04%, approximately 0%, approximately 0%, approximately 0%, approximately 0%, approximately 0.05%, and approximately 0.07%, respectively.

[0115] During the inward folding operation, the strain of the reference sample and samples A, B, C, D, E, and F decreases from the folding axis FX to the edge of the inward folding region IFA.

[0116] Although the folding stress is concentrated on the folding shoulder region FSA in the reference sample and samples A, E, and F, the folding stress is not concentrated on the folding shoulder region FSA in samples B, C, and D, thus being minimized.

[0117] The folded shoulder region FSA of the coverage window 130 of the reference sample and samples A, B, C, D, E, and F have tensile strains of approximately 0.1%, approximately 0.04%, approximately 0%, approximately 0%, approximately 0%, approximately 0%, approximately 0.05%, and approximately 0.07%, respectively.

[0118] The transparent adhesive layers of the reference sample and samples A, B, C, D, E, and F have maximum strains of approximately 133%, approximately 113%, approximately 112%, approximately 112%, approximately 113%, approximately 117%, and approximately 119%, respectively.

[0119] During the inward folding operation, the reference sample did not acquire an omega shape, samples A, E, and F did not acquire a normal omega shape, while samples B, C, and D acquired a normal omega shape.

[0120] Therefore, in the foldable display device 110 according to the first embodiment of the present disclosure, taking into account errors, the first width w1 of the hole region HA of the top 142 of the back panel 140 can be in the range of about 2.5 mm to about 6.5 mm.

[0121] When the first width w1 of the hole region HA of the top 142 of the back plate 140 is in the range of about 2.5 mm to about 6.5 mm, during the inward folding operation, it is possible to fold without the first, second, and third guides 152, 154, and 156. Figure 3A The Omega shape can be obtained in the case of (in the middle). When the first width w1 of the hole area HA of the top plate 142 of the back plate 140 is greater than about 6.5 mm, the Omega shape can be obtained during the inward folding operation by using the first, second and third guides 152, 154 and 156.

[0122] In the foldable display device 110 according to the first to fourth embodiments of this disclosure, a plurality of holes 142a are provided in the hole region HA of the top 142 of the back plate 140, and at least one groove 146a is provided in the groove region GA of the bottom 146 of the back plate 140. Therefore, the transmission of deformation caused by folding stress to the cover window 130 and the display panel 120 can be minimized, and the accuracy of the reproduction of the original shape is improved.

[0123] Furthermore, the stress in the folding shoulder area FSA is minimized by adjusting the width of the hole region HA in the top 142 of the back plate 140. Therefore, a normal Omega shape is achieved during the inward folding operation.

[0124] In another embodiment, the resin layer for absorbing impact can be disposed in a groove at the bottom of the plate.

[0125] Figure 10 This is a cross-sectional view showing a foldable display device according to a fifth embodiment of the present disclosure. Descriptions of parts identical to those in the first embodiment will be omitted.

[0126] exist Figure 10 In the present disclosure, the foldable display device 510 according to the fifth embodiment includes a display panel 520, a cover window 530, a back plate 540, and a resin layer 548.

[0127] The back panel 540 supports the display panel 520 and protects the display panel 520 from external impacts, external moisture, and external heat. The back panel 540 includes a top panel 542, an adhesive layer 544, and a bottom panel 546 disposed sequentially below the display panel 520.

[0128] The top of the plate 542 includes a plurality of holes 542a symmetrically arranged relative to the folding axis FX in the hole region HA. The hole region HA can form an inner folding region IFA, which has relatively weaker stiffness than the non-folding region NFA due to the plurality of holes 542a and bends during the inner folding operation.

[0129] The bottom of the plate 546 includes at least one groove 546a symmetrically disposed in the grooved region GA with respect to the folding axis FX. Due to the at least one groove 546a, the grooved region GA can have relatively weak stiffness compared to the non-folded region NFA, and can form an outward folded region OFA that bends during the outward folding operation.

[0130] The bottom plate 546 may include a material with a relatively high modulus of elasticity. For example, the bottom plate 546 may include a material with the same family but a different alloy composition ratio as the top plate 542.

[0131] A resin layer 548 is disposed in at least one groove 546a in the bottom of the panel 546. The resin layer 548 comprises a soft resin and absorbs external impacts to protect the display panel 520 and the back panel 540.

[0132] In the foldable display device 510 according to the fifth embodiment of this disclosure, a plurality of holes 542a are provided in the hole region HA of the top 542 of the back plate 540, and at least one groove 546a is provided in the groove region GA of the bottom 546 of the back plate 540. Therefore, the transmission of deformation caused by folding stress to the cover window 530 and the display panel 520 is minimized, and the accuracy of reproducing the original shape is improved.

[0133] Furthermore, the stress in the folding shoulder area FSA is minimized by adjusting the width of the hole region HA in the top 542 of the back plate 540. Therefore, a normal Omega shape is achieved during the inward folding operation.

[0134] Furthermore, since the resin layer 548 of the soft resin is disposed in at least one groove 546a on the bottom of the board 546, the display panel 520 and the back panel 540 are protected from external impacts.

[0135] In another embodiment, multiple grooves may be formed in the bottom of the plate.

[0136] Figure 11 This is a cross-sectional view showing a foldable display device according to a sixth embodiment of the present disclosure. Descriptions of parts identical to those in the first embodiment will be omitted.

[0137] exist Figure 11 In the sixth embodiment of the present disclosure, the foldable display device 610 includes a display panel 620, a cover window 630, a back plate 640, and a resin layer 648.

[0138] The back panel 640 supports the display panel 620 and protects the display panel 620 from external impacts, external moisture and external heat. The back panel 640 includes a top panel 642, an adhesive layer 644 and a bottom panel 646 disposed sequentially below the display panel 620.

[0139] The top of the plate 642 includes a plurality of holes 642a symmetrically arranged in the hole region HA relative to the folding axis FX. The hole region HA can form an inner folding region IFA, which has relatively weaker stiffness than the non-folding region NFA due to the plurality of holes 642a and bends during the inner folding operation.

[0140] The bottom of the plate 646 includes a plurality of grooves 646a symmetrically arranged in the grooved region GA with respect to the folding axis FX. Due to the plurality of grooves 646a, the grooved region GA can have relatively weaker stiffness compared to the non-folded region NFA, and can form an outward folded region OFA that bends during outward folding operations.

[0141] Multiple grooves 646a may have the same depth, which is equal to the fifth thickness t5 mentioned above.

[0142] The plurality of grooves 646a on the bottom of the plate 646 may have a shape corresponding to the plurality of holes 642a on the top of the plate 642.

[0143] For example, each of the plurality of grooves 646a on the bottom of the plate 646 may have one of the following shapes: a rectangular shape, a rectangular shape with rounded corners, or an elliptical or rhomboid shape with a minor axis of constant length. The spacing between the grooves 626a may decrease from the edge portion to the center portion of the groove region GA, and the width of the grooves 626a may increase from the edge portion to the center portion of the groove region GA.

[0144] The bottom plate 646 may include a material with a relatively high modulus of elasticity. For example, the bottom plate 646 may include a material with the same family as the top plate 642 but a different alloy composition ratio.

[0145] In the foldable display device 610 according to the sixth embodiment of this disclosure, a plurality of holes 642a are provided in the hole region HA of the top plate 642 of the back plate 640, and a plurality of grooves 646a are provided in the groove region GA of the bottom plate 646 of the back plate 640. Therefore, the transmission of deformation caused by folding stress to the cover window 630 and the display panel 620 is minimized, and the accuracy of reproducing the original shape is improved.

[0146] Furthermore, the stress in the folding shoulder area FSA is minimized by adjusting the width of the hole region HA in the top 642 of the back plate 640. Therefore, a normal Omega shape is achieved during the inward folding operation.

[0147] Therefore, in the foldable display devices according to the first to sixth embodiments of the present disclosure, since multiple holes are provided in the top of the back panel and at least one groove is provided in the bottom of the back panel, the transmission of deformation caused by folding stress to the display panel is minimized, the accuracy of reproducing the original shape is improved, and bidirectional folding is achieved.

[0148] Furthermore, by adjusting the widths of the perforated area, the inward folding area, and the outward folding area of ​​the back panel, a normal Omega shape is achieved during the inward folding operation, and stress in the folding shoulder area is minimized.

[0149] In addition, this disclosure also includes the following implementation methods.

[0150] Implementation Method 1. A foldable display device, comprising:

[0151] A display panel configured to display images;

[0152] The overlay window above the display panel; and

[0153] The back panel below the display panel includes a top panel with multiple holes, a bottom panel with at least one groove corresponding to the multiple holes, and an adhesive layer that joins the top panel and the bottom panel.

[0154] Embodiment 2. The device according to Embodiment 1, wherein the back plate includes a hole region corresponding to the plurality of holes, an inner folding region, an outer folding region, a non-folding region outside the outer folding region, and a groove region corresponding to the at least one groove, wherein the inner folding region is a bent portion of an inner folding operation with respect to the folding axis, and the outer folding region is a bent portion of an outer folding operation opposite to the inner folding operation.

[0155] Embodiment 3. The device according to Embodiment 2, wherein the hole region, the inner fold region, the outer fold region, and the groove region each have a first width, a second width, a third width, and a fourth width along a direction perpendicular to the folding axis.

[0156] Wherein, the second width is greater than the first width and less than the third width, and

[0157] The fourth width is equal to or greater than the third width, and equal to or less than 1.2 times the third width.

[0158] Embodiment 4. The device according to Embodiment 3, wherein the first width is in the range of 2.5 mm to 6.5 mm.

[0159] Embodiment 5. The device according to Embodiment 1, wherein the first thickness of the top of the plate is in the range of 10 μm to 100 μm.

[0160] The second thickness of the adhesive layer is in the range of 5 μm to 100 μm.

[0161] The third thickness at the bottom of the plate is in the range of 10 μm to 200 μm, and

[0162] The fourth thickness is equal to or less than the fifth thickness, the fourth thickness being the minimum thickness of the bottom of the plate caused by the at least one groove, and the fifth thickness being equal to the maximum depth of the at least one groove.

[0163] Embodiment 6. The device according to Embodiment 1, wherein each of the plurality of holes has one of the following shapes: a rectangular shape, a rectangular shape with rounded corners, an elliptical shape with a minor axis of constant length, or a rhombus shape.

[0164] Embodiment 7. The device according to Embodiment 2, wherein the spacing between two adjacent holes in the plurality of holes decreases from the edge portion to the center portion of the hole region in a direction parallel to the folding axis in a direction perpendicular to the folding axis, and

[0165] The spacing between two adjacent holes in the plurality of holes, along a direction perpendicular to the folding axis, decreases from the edge portion to the center portion of the hole region in a direction perpendicular to the folding axis.

[0166] The width of the plurality of holes increases from the edge portion to the center portion of the hole region in a direction perpendicular to the folding axis.

[0167] Embodiment 8. The device according to Embodiment 1 further includes a resin layer in the at least one groove.

[0168] Embodiment 9. The device according to Embodiment 1, wherein the bottom of the plate has a plurality of grooves of the same depth.

[0169] Implementation Method 10. A foldable display device, comprising:

[0170] A display panel configured to display images;

[0171] The top of the panel below the display panel, the top of the panel including a plurality of holes; and

[0172] The bottom of the plate, below the top of the plate, includes at least one groove corresponding to the plurality of holes.

[0173] The top and bottom of the plate have omega-shaped cross-sections during an inward folding operation about the folding axis, in which the display surface of the display panel is hidden inside.

[0174] The top and bottom of the plate have U-shaped cross sections during the outward folding operation with respect to the folding axis, during which the display surface of the display panel is exposed to the outside.

[0175] Embodiment 11. The device according to Embodiment 10, wherein the hole region corresponding to the plurality of holes has a first width in a direction perpendicular to the folding axis.

[0176] The inward folding region, which is the curved portion of the inward folding operation, has a second width along a direction perpendicular to the folding axis.

[0177] The outward folding region, which is the curved portion of the outward folding operation, has a third width along a direction perpendicular to the folding axis.

[0178] The groove region corresponding to the at least one groove has a fourth width along a direction perpendicular to the folding axis.

[0179] Wherein, the second width is greater than the first width and less than the third width, and

[0180] The fourth width is equal to or greater than the third width, and equal to or less than 1.2 times the third width.

[0181] Implementation Method 12. A foldable display device, comprising:

[0182] A display panel configured to display images; and

[0183] The back panel below the display panel includes:

[0184] The top of the plate has a plurality of holes disposed in the hole area;

[0185] The bottom of the plate has a plurality of grooves disposed in the groove area; and

[0186] An adhesive layer that bonds the top and bottom of the board.

[0187] The foldable display device performs bidirectional folding about the folding axis.

[0188] Embodiment 13. The device according to Embodiment 12, wherein each of the plurality of grooves has one of the following shapes: a rectangular shape, a rectangular shape with rounded corners, an elliptical shape with a minor axis of constant length, or a rhombus shape.

[0189] Embodiment 14. The device according to Embodiment 12, wherein the spacing between two adjacent grooves in the plurality of grooves decreases from the edge portion to the center portion of the groove region in a direction perpendicular to the folding axis, and

[0190] The width of the groove along the direction perpendicular to the folding axis increases from the edge portion to the center portion of the groove region along the direction perpendicular to the folding axis.

[0191] It will be apparent to those skilled in the art that various modifications and variations can be made to this disclosure without departing from its spirit or scope. Therefore, this disclosure is intended to cover such modifications and variations as long as they fall within the scope of the appended claims and their equivalents.

Claims

1. A foldable display device, comprising: A display panel configured to display images; The overlay window above the display panel; The back panel below the display panel; as well as The first guide, the second guide, and the third guide support the back plate. The back panel has an Omega-shaped cross-section during an inward folding operation about the folding axis, in which the display surface of the display panel is hidden inside. During the inward folding operation, the second guide contacts one of the side surfaces of the Omega letter shape to support the back panel. During the inward folding operation, the third guide contacts the lower surface of the Omega letter shape to support the back panel.

2. The foldable display device according to claim 1, wherein, The back panel includes a top plate having multiple through holes, a bottom plate having at least one groove corresponding to the multiple through holes, and an adhesive layer that joins the top plate and the bottom plate, wherein the bottom plate is not penetrated by the at least one groove.

3. The foldable display device according to claim 2, wherein, The back plate also includes a hole area corresponding to the plurality of through holes, an inner folding area, and an outer folding area, wherein the inner folding area is the curved portion of the inner folding operation with respect to the folding axis, and the outer folding area is the curved portion of the outer folding operation opposite to the inner folding operation. Wherein, the hole region, the inner fold region, and the outer fold region each have a first width, a second width, and a third width along a direction perpendicular to the folding axis, and Wherein, the second width is greater than the first width and less than the third width.

4. The foldable display device according to claim 3, wherein, The back plate also includes a non-folded area outside the outer folded area and a groove area corresponding to the at least one groove.

5. The foldable display device according to claim 4, wherein, The groove region has a fourth width along a direction perpendicular to the folding axis, and The fourth width is equal to or greater than the third width, and equal to or less than 1.2 times the third width.

6. The foldable display device according to claim 5, wherein, The first width is in the range of 2.5 mm to 6.5 mm.

7. The foldable display device according to claim 3, wherein, The first thickness at the top of the plate is in the range of 10 μm to 100 μm. The second thickness of the adhesive layer is in the range of 5 μm to 100 μm. The third thickness at the bottom of the plate is in the range of 10 μm to 200 μm, and The fourth thickness is equal to or less than the fifth thickness, the fourth thickness being the minimum thickness of the bottom of the plate caused by the at least one groove, and the fifth thickness being equal to the maximum depth of the at least one groove.

8. The foldable display device according to claim 3, wherein, Each of the plurality of through holes has one of the following shapes: rectangular, rectangular with rounded corners, elliptical with a minor axis of constant length, or rhomboid.

9. The foldable display device according to claim 4, wherein, The spacing between two adjacent through holes in the plurality of through holes decreases from the edge portion to the center portion of the hole region in a direction parallel to the folding axis in a direction perpendicular to the folding axis. The spacing between two adjacent through holes in the plurality of through holes, along a direction perpendicular to the folding axis, decreases from the edge portion to the center portion of the hole region in a direction perpendicular to the folding axis. The width of the plurality of through holes increases from the edge portion to the center portion of the hole region in a direction parallel to the folding axis, and in a direction perpendicular to the folding axis. The width of the plurality of through holes increases from the edge portion to the center portion of the hole region in a direction perpendicular to the folding axis.

10. The foldable display device according to claim 3, further comprising a resin layer in the at least one groove.

11. The foldable display device according to claim 3, wherein, The bottom of the plate has multiple grooves of the same depth.

12. The foldable display device according to claim 1, in, During the inward folding operation, the second guide slides from the first guide and contacts the two side surfaces of the Omega letter shape to support the back panel.

13. A foldable display device, comprising: A display panel configured to display images; The overlay window above the display panel; The back panel below the display panel; as well as The first guide, the second guide, and the third guide support the back plate. The back plate has a U-shaped cross-section during the outward folding operation about the folding axis, during which the display surface of the display panel is exposed to the outside. During the outward folding operation, the second guide slides to the first guide and separates from the back panel. During the outward folding operation, the third guide contacts the U-shape to support the back plate.

Images