Patent Publication Number: US-11656656-B2

Title: Display device

Description:
This application claims priority to Korean Patent Application No. 10-2020-0063087 filed on May 26, 2020, and all the benefits accruing therefrom under 35 U.S.C. § 119, the content of which in its entirety is herein incorporated by reference. 
     BACKGROUND 
     1. Field of the Invention 
     The disclosure relates to a display device. 
     2. Description of the Related Art 
     A display device, which is a device for displaying an image, includes a display panel such as an organic light emitting display panel including organic light emitting diodes (“OLED”) or quantum dot electroluminescence elements (“QD-EL”), or a liquid crystal display panel. 
     A mobile electronic appliance includes a display device to provide an image to a user. The proportion of mobile electronic appliances having the same or smaller volume or thickness and having a larger display screen than conventional electronic appliances has increased. Further, in order to provide a larger screen only when used, foldable display devices or bendable display devices having a structure capable of being folded and unfolded have also been developed. 
     In such display devices, a metal plate configured to be stretched at least partially in response to the folding of a display panel may be disposed on the rear surface of the display panel. 
     In order to facilitate the folding of the display device, the metal plate is provided with a connection portion corresponding to a folding area. However, the shape of a lattice pattern constituting the connection portion may be viewed on the display surface of the display device, thereby deteriorating display quality. 
     SUMMARY 
     An aspect of the disclosure is to provide a display device capable of preventing the connection portion of the metal plate from being viewed from outside the display device. 
     Another aspect of the disclosure is to provide a display device capable of improving impact resistance when the display device is folded. 
     However, aspects of the disclosure are not restricted to the one set forth herein. The above and other aspects of the disclosure will become more apparent to one of ordinary skill in the art to which the disclosure pertains by referencing the detailed description of the disclosure given below. 
     According to an embodiment of the disclosure, a display device includes a display panel including a rear surface and a front surface, where the front surface is provided with a display surface and including a folding axis extending in a first direction; a first barrier member disposed on the rear surface of the display panel and having a modulus of about 1 gigapascals (GPa) to about 300 GPa; a first coupling member disposed on a rear surface of the first barrier member; and a metal plate disposed on a rear surface of the first coupling member and including a first plate portion and a second plate portion which are arranged in a second direction crossing the first direction and a connection portion connecting the first plate portion and the second plate portion, where the first coupling member does not overlap the connection portion in a plan view. 
     In an embodiment, the first barrier member may have the modulus of about 1 GPa to about 10 GPa. 
     In an embodiment, the first barrier member may have a thickness of about 25 micrometers (μm) to about 80 μm. 
     In an embodiment, the first barrier member may include at least one selected from polyimide, polyacrylate, polymethyl methacrylate, polycarbonate, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, and a cycloolefin copolymer. 
     In an embodiment, the first barrier member may have the modulus of about 10 GPa to about 300 GPa. 
     In an embodiment, the first barrier member may have a thickness of about 10 μm to about 50 μm. 
     In an embodiment, the first barrier member may include at least one selected from steel used stainless (“SUS”), invar, aluminum, iron, chromium, carbon, nickel, silicon, manganese, and molybdenum. 
     In an embodiment, the first coupling member may include a first coupling portion overlapping the first plate portion and a second coupling portion spaced apart from the first coupling portion and overlapping the second plate portion in the plan view. 
     In an embodiment, the first coupling portion and the second coupling portion may be spaced apart from each other by a first spacing interval, and a width of the first spacing interval may be equal to or greater than a width of the connection portion in the second direction. 
     In an embodiment, the display device may further include a second coupling member disposed between the display panel and the first barrier member, where a sum of a thickness of the first coupling member and a thickness of the second coupling member may be greater than about 1 μm and equal to or less than about 80 μm. 
     In an embodiment, the thickness of the second coupling member may be about 1 μm and about 50 μm. 
     In an embodiment, the display device may further include a third coupling member disposed on a rear surface of the metal plate, a second barrier member disposed on a rear surface of the third coupling member, a fourth coupling member disposed on a rear surface of the second barrier member, and a heat dissipation member disposed on a rear surface of the fourth coupling member. 
     In an embodiment, the second barrier member may overlap the first plate portion, the second plate portion, and the connection portion in the plan view. 
     In an embodiment, the heat dissipation member may include a first heat dissipation portion overlapping the first plate portion and a second heat dissipation portion spaced apart from the first heat dissipation portion and overlapping the second plate portion in the plan view. 
     In an embodiment, a second spacing interval between the first heat dissipation portion and the second heat dissipation portion may overlap the connection portion in the plan view. 
     In an embodiment, the fourth coupling member may include a third coupling portion overlapping the first plate portion and a fourth coupling portion spaced apart from the third coupling portion and overlapping the second plate portion in the plan view, the third coupling portion and the fourth coupling portion may be spaced apart from each other by a third spacing interval, and the third spacing interval may be equal to or greater than a width of the connection portion. 
     In an embodiment, the display device may further include a fifth coupling member disposed on a rear surface of the heat dissipation member, and a cushion member disposed on a rear surface of the fifth coupling member, where the cushion member includes a first cushion portion overlapping the first plate portion and a second cushion portion spaced apart from the first cushion portion and overlapping the second plate portion in the plan view, the first cushion member and the second cushion member are spaced apart from each other by a fourth spacing interval, and the fourth spacing interval overlaps the connection portion in the plan view. 
     According to an embodiment of the disclosure, a display device includes a display panel including a rear surface and a front surface, where the front surface is provided with a display surface and including a folding axis extending in a first direction; a second coupling member disposed on the rear surface of the display panel; a first barrier member disposed on a rear surface of the second coupling member; a first coupling member disposed on a rear surface of the first barrier member; and a metal plate disposed on a rear surface of the first coupling member and including a first plate portion and a second plate portion which are arranged in a second direction crossing the first direction and a connection portion connecting the first plate portion and the second plate portion, where a sum of a thickness of the first coupling member and a thickness of the second coupling member is greater than about 1 μm and equal to or less than about 80 μm. 
     In an embodiment, the thickness of the second coupling member may be about 1 μm and about 50 μm. 
     In an embodiment, the first coupling member may not overlap the connection portion of the metal plate in a plan view. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects and features of the disclosure will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which: 
         FIG.  1    is a perspective view of a display device according to an embodiment; 
         FIG.  2    is a perspective view of the display device of  FIG.  1    in a folded state; 
         FIG.  3    is an exploded perspective view of the display device of  FIG.  1   ; 
         FIG.  4    is a cross-sectional view of the display device taken along line A-A′ in  FIG.  1   ; 
         FIG.  5    is a cross-sectional view of a display panel; 
         FIG.  6    is a cross-sectional view illustrating a portion of a display device according to an embodiment; 
         FIG.  7    is a cross-sectional view illustrating a portion of a display device according to an embodiment in a folded state; 
         FIG.  8    is a schematic cross-sectional view of a connection portion between a first coupling member and a metal plate; 
         FIG.  9    is a cross-sectional view of a display device according to another embodiment; 
         FIG.  10    is a cross-sectional view illustrating a portion of a display device according to the embodiment in  FIG.  9   ; 
         FIG.  11    is a cross-sectional view of a display device according to still another embodiment; 
         FIG.  12    is a cross-sectional view illustrating a portion of a display device according to the embodiment in  FIG.  11   ; 
         FIG.  13    is a cross-sectional view illustrating a display device sample #1 according to Manufacturing Example; 
         FIG.  14    is a cross-sectional view illustrating a display device sample #8 according to Manufacturing Example; and 
         FIG.  15    is a graph showing a height profile according to a distance from the center of a connection portion of a metal plate in each of the display device samples. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will filly convey the scope of the invention to those skilled in the art. 
     It will also be understood that when a layer is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. The same reference numbers indicate the same components throughout the specification. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms, including “at least one,” unless the content clearly indicates otherwise. “At least one” is not to be construed as limiting “a” or “an.” “Or” means “and/or.” As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof. Furthermore, relative terms, such as “lower” or “bottom” and “upper” or “top,” may be used herein to describe one element&#39;s relationship to another element as illustrated in the Figures. It will be understood that relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. For example, if the device in one of the figures is turned over, elements described as being on the “lower” side of other elements would then be oriented on “upper” sides of the other elements. The exemplary term “lower,” can therefore, encompasses both an orientation of “lower” and “upper,” depending on the particular orientation of the figure. Similarly, if the device in one of the figures is turned over, elements described as “below” or “beneath” other elements would then be oriented “above” the other elements. The exemplary terms “below” or “beneath” can, therefore, encompass both an orientation of above and below. “About” or “approximately” as used herein is inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (i.e., the limitations of the measurement system). For example, “about” can mean within one or more standard deviations, or within ±30%, 20%, 10% or 5% of the stated value. 
     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 only used to distinguish one element from another element. For instance, a first element discussed below could be termed a second element without departing from the teachings of the present invention. Similarly, the second element could also be termed the first element. 
     Each of the features of the various embodiments of the present disclosure may be combined or combined with each other, in part or in whole, and technically various interlocking and driving are possible. Each embodiment may be implemented independently of each other or may be implemented together in an association. 
     Hereinafter, embodiments of the disclosure will be described with reference to the attached drawings. 
       FIG.  1    is a perspective view of a display device according to an embodiment, and  FIG.  2    is a perspective view of the display device of  FIG.  1    in a folded state. 
     Although a display device  1  according to an embodiment will be described with reference to smart phones, the disclosure according to the invention is not limited thereto. For example, the display device  1  according to embodiments of the present specification may be applied to portable phones, tablet PCs, personal digital assistants (“PDAs”), portable multimedia players (“PMPs”), televisions, game machines, wrist-watch type electronic devices, head mount displays, monitors of personal computers, notebook computers, car navigators, car dashboards, digital cameras, camcorders, billboards, medical devices, inspection devices, various home appliances such as refrigerators and washing machines, and internet of thing devices, in addition to smart phones. 
     The first direction X, the second direction Y, and the third direction Z cross each other in different directions. The first direction X may be a length direction (i.e., vertical direction in a display screen), the second direction Y may be a width direction (i.e., horizontal direction in the display screen), and the third direction Z may be a thickness direction (i.e., a direction of a plan view). The third direction Z may include a front direction toward the upper surface of the display device  1  and a rear direction toward the lower surface of the display device  1 . Accordingly, one surface of a member disposed to face the front direction may be referred to as a front surface (i.e., upper surface), and the other surface of the member disposed to face the rear direction may be referred to as a rear surface (i.e., lower surface). However, these directions should be understood as referring to relative directions, and are not limited to the above example. 
     Referring to  FIGS.  1  and  2   , the display device  1  according to an embodiment may have a rectangular shape or a square shape in a plan view. In an embodiment, the display device  1  may have a rectangular shape where corners are straight or a substantially rectangular shape where corners are round in a plan view. The display device  1  may include two short sides extended in the first direction X and two long sides extended in the second direction Y in a plan view. However, the disclosure according to the invention is not limited thereto, and the display device  1  may have various shapes. 
     The display device  1  may include a front surface and a rear surface. The display device  1  may further include at least one side surface between the front surface and the rear surface. 
     The display device  1  includes at least one display surface DS. In an embodiment, the display surface DS may be the front surface of the display device  1 . The display surface DS may be disposed over a folding area FA and non-folding areas NFA 1  and NFA 2 , which will be described later. In some embodiments, both the front and back surfaces of the display device  1  may be the display surface DS. In some embodiments, two or more surfaces of the front, back, and side surfaces of the display device  1  may be provided as the display surfaces DS. 
     The display surface DS may include a display area DA and a non-display area NDA. 
     The display area DA displays an image or video. In a plan view, the shape of the display area DA may correspond to the shape of the display device  1 . For example, when the display device  1  has a rectangular shape in a plan view, the display area DA may also have rectangular shape. 
     The display area DA may be an area where a plurality of pixels is provided therein to display an image. The plurality of pixels may be arranged in a matrix from. Each of the plurality of pixels may have a rectangular shape, a rhombus shape, or a square shape in a plan view, but the shape thereof is not limited thereto. In another embodiment, for example, each of the plurality of pixels may have a polygonal shape, a circular shape, or an elliptic shape in addition to the rectangular shape, the rhombus shape, or the square shape in a plan view. 
     The non-display area NDA may be an area where no pixel is provided not to display an image. The non-display area NDA may be disposed around the display area DA. The non-display area NDA may be disposed to surround the display area DA as shown in  FIG.  1   , but the disclosure according to the invention is not limited thereto. In some embodiments, the display area DA may be partially surrounded by the non-display area NDA. In some embodiments, the display area DA has a rectangular shape, and the non-display area NDA may be disposed around four sides of the display area DA, but the disclosure according to the invention is not limited thereto. 
     In an embodiment, the display device  1  may be a foldable device. The display device  1  may be folded or unfolded. The “folded” includes “bent”. Specifically, in the display device  1 , a part thereof may overlap the other part thereof in a folded state, a part thereof may be bent to be inclined with respect to the other part thereof, or the entirety thereof may be flat. In an embodiment, the display device  1  may be folded such that a part thereof is inclined with respect to the other part thereof at an angle of more than 0° and less than 180°, or may be unfolded such that a part thereof is inclined with respect to the other part thereof at an angle of about 180°. 
     The display device  1  may be infolded and/or outfolded. The infolding means a state that a portion of the display surface DS of the display device  1  is folded to face another portion of the display surface DS thereof, and the outfolding means a state that a portion of the display surface DS of the display device  1  is folded so as not to face another portion of the display surface DS thereof. The outfolding may mean that a portion of the opposite surface of the display surface DS of the display device  1  is folded to face another portion of the opposite surface of the display surface DS thereof. In an embodiment, the display device  1  is infolded, but the disclosure according to the invention is not limited thereto. 
     The display device  1  may have a folded state or an unfolded state. The folded state includes a state in which the display device  1  is bent. Specifically, the folded state may be a state in which a portion of the display device  1  is bent to form an inclination with respect to another portion, and the unfolded state may be a state in which a portion of the display device  1  is disposed in parallel with another portion thereof on the same plane. Alternatively, the folded state may be a state in which the angle between a portion of the display device  1  and another portion thereof is about 0 degrees)(° or more and less than 180° and/or about more than 180° and less than 360°, and the unfolded state may be a state in which the angle between a portion of the display device  1  and the another portion thereof is about 180°. Here, a part and the another part may be non-folding areas NFA 1  and NFA 2  (to be described later), respectively. 
     The display device  1  may be divided into a folding area FA and non-folding areas NFA 1  and NFA 2 . The folding area FA is an area that is folded or bent as the display device  1  is folded. The non-folding areas NFA 1  and NFA 2  are areas that are not folded or bent even when the display device  1  is folded. The non-folding areas NFA 1  and NFA 2  may include a first non-folding area NFA 1  and a second non-folding area NFA 2 . In an embodiment, the first non-folding area NFA 1  and the second non-folding area NFA 2  are arranged in the second direction Y, and the folding area FA may be disposed between the first non-folding area NFA 1  and the second non-folding area NFA 2 . In this embodiment, one folding area FA and two non-folding areas NFA 1  and NFA 2  are defined in the display device  1 , but the disclosure according to the invention is not limited thereto. In some embodiments, a plurality of folding areas FA and non-folding areas NFA 1  and NFA 2  may be defined in the display device  1 . 
     The display device  1  may be folded or unfolded with respect to a folding axis FX. The folding axis FX may be disposed to overlap the folding area FA in the thickness direction (i.e., the third direction Z). In an embodiment, the display device  1  may be folded or unfolded with respect to the folding axis FX disposed in the first direction X, but the disclosure according to the invention is not limited thereto. The folding axis FX may include at least one rotation axis. That is, the display device  1  may be folded or unfolded to have at least one curvature center. 
     Hereinafter, the display device  1  according to an embodiment will be described in detail with reference to  FIGS.  3  to  5   . 
       FIG.  3    is an exploded perspective view of the display device of  FIG.  1   ,  FIG.  4    is a cross-sectional view of the display device taken along line A-A′ in  FIG.  1   , and  FIG.  5    is a cross-sectional view of a display panel. 
     Referring to  FIGS.  1  to  5   , a display module  10  may be disposed on the front surface of a metal plate  200 . The front surface of the display module  10  may correspond to the front surface of the display device  1 . 
     The display module  10  has flexibility. The display module  10  may be disposed over the first non-folding area NFA 1 , the folding area FA, and the second non-folding area NFA 2 , and may be folded with respect to the folding axis FX. 
     Referring to  FIG.  4   , the display module  10  may include a display panel  100 , a front laminate structure  300  and a rear laminate structure  400 . 
     The display module  10  may include a display panel  100 , a front laminate structure  300  disposed on the front surface of the display panel  100 , and a rear laminate structure  400  disposed on the rear surface of the display panel  100 . The front may be a direction in which the display panel  100  displays a screen, and the rear may be a direction opposite to the front. 
     The display panel  100  is a panel for displaying an video or an image, and examples thereof may include self-light emitting display panels such as an organic light emitting display panel (“OLED”), an inorganic light emitting display panel (inorganic “EL”), a quantum dot light emitting display panel (“QED”), a micro LED display panel (micro-“LED”), a nano LED display panel (nano-LED), a plasma display panel (“PDP”), a field emission display panel (“FED”), and a cathode ray display panel (“CRT”); and light-receiving display panels such as liquid crystal display panel (“LCD”) and an electrophoretic display panel (“EPD”). Hereinafter, an organic light emitting display panel will be described as an example of the display panel  100 , and unless otherwise specified, the organic light emitting display panel applied to the embodiment will be simply referred to as the display panel  100 . However, embodiments according to the invention are not limited to the organic light emitting display panel, and other display panels listed above or known in the art may be applied within the scope of sharing the technical idea. 
     The display panel  100  may further include a touch member. The touch member may be provided as a panel or film separate from the display panel  100  and attached to the display panel  100 , pr may also be provided in the form of a touch layer inside the display panel  100 . In the following embodiments, a case where the touch member is provided inside the display panel  100  and included in the display panel  100  is illustrated, but is not limited thereto. 
     Referring to  FIGS.  4  and  5   , the display panel  100  includes a substrate SUB, a circuit driving layer DRL on the substrate SUB, a light emitting layer EML on the circuit driving layer DRL, an encapsulation layer ENL on the light emitting layer EML, and a touch layer TSL on the encapsulation layer ENL. 
     The substrate SUB may be a flexible substrate including a flexible polymer material such as polyimide. Accordingly, the display panel  100  may be warped, bent, folded, or rolled. In some embodiments, the substrate SUB may include a plurality of sub-substrates overlapping in the thickness direction (i.e., the third direction Z) with a barrier layer interposed therebetween. In this case, each of the sub-substrates may be a flexible substrate. 
     The circuit driving layer DRL may be disposed on the substrate SUB. The circuit driving layer DRL may include a circuit for driving the light emitting layer EML of a pixel. The circuit driving layer DRL may include a plurality of thin film transistors. 
     The light emitting layer EML may be disposed on the circuit driving layer DRL. The light emitting layer EML may include an organic light emitting layer. The light emitting layer EML may emit light with various luminance according to a driving signal transmitted from the circuit driving layer DRL. 
     The encapsulation layer ENL may be disposed on the light emitting layer EML. 
     The encapsulation layer ENL may include an inorganic layer or a laminated layer of an inorganic layer and an organic layer. 
     The touch layer TSL may be disposed on the encapsulation layer ENL. The touch layer TSL, which is a layer for recognizing a touch input, may function as a touch member. The touch layer TSL may include a plurality of sensing areas and a plurality of sensing electrodes. 
     Referring to  FIG.  4    again, the front laminate structure  300  is disposed on the entire surface of the display panel  100 . The front laminate structure  300  may include a polarization member  330 , a cover window  320 , and a cover window protection layer  310 , which are sequentially laminated in a direction away from the front surface of the display panel  100 . 
     The polarization member  330  polarizes light. The polarization member  330  may serve to reduce the reflection of external light. In an embodiment, the polarization member  330  may be a polarization film. The polarization film may include a polarization layer and a protective substrate sandwiching the polarization layer from the top and bottom thereof. The polarization layer may include polyvinyl alcohol. The polarization layer may be stretched in one direction. The stretching direction of the polarization layer may be an absorption axis, and the direction perpendicular thereto may be a transmission axis. The protective substrate may be disposed on one surface and the other surface of the polarizing layer. The protective substrate may include or be made of a cellulose resin such as triacetyl cellulose, a polyester resin, or the like, but the material thereof according to the invention is not limited thereto. 
     The cover window  320  may be disposed in front of the polarization member  330 . The cover window  320  serves to protect the display panel  100 . The cover window  320  may include or be made of a transparent material. The cover window  320  may be made of, for example, glass or plastic. 
     When the cover window  320  includes glass, the glass may be ultra-thin glass (“UTG”) or thin glass. When the glass is formed as an ultra-thin film or a thin film, it has flexible properties, and may thus be warped, bent, folded, or rolled. The thickness of the glass may be, for example, in the range of about 10 micrometers (μm) to about 300 μm, and specifically, glass having a thickness of about 30 μm to about 80 μm or to about 50 μM may be applied. The glass of the cover window  320  may include soda lime glass, alkali alumino silicate glass, borosilicate glass, or lithium alumina silicate glass. The glass of the cover window  320  may include chemically reinforced or thermally reinforced glass to have strong strength. The chemical reinforcement may be achieved through an ion exchange treatment process in an alkali salt. The ion exchange treatment process may be performed two or more times. 
     When the cover window  320  includes plastic, it may be more advantageous to exhibit flexible properties such as folding. Examples of the plastic applicable to the cover window  320  may include, but are not limited to, polyimide, polyacrylate, polymethylmethacrylate (“PMMA”), polycarbonate (“PC”), polyethylenenaphthalate (“PEN”), polyvinylidene chloride, polyvinylidene difluoride (“PVDF”), polystyrene, ethylene-vinyl alcohol copolymers, polyethersulfone (“PES”), polyetherimide (“PEI”), polyphenylene sulfide (“PPS”), polyallylate, tri-acetyl cellulose (“TAC”), and cellulose acetate propionate (“CAP”). The plastic cover window  320  may include or be formed of one or more of the plastic materials listed above. 
     The cover window protection layer  310  may be disposed in the front (i.e., the top) of the cover window  320 . The cover window protection layer  310  may perform at least one function of scattering prevention, shock absorption, imprint prevention, fingerprint prevention, and anti-glare of the cover window  320 . The cover window protection layer  310  may include or be formed of a transparent polymer film. The transparent polymer film may include at least one of polyethylene terephthalate (“PET”), polyethylene naphthalate (PEN), polyether sulfone (PES), polyimide (“PI”), polyarylate (“PAR”), polycarbonate (“PC”), polymethylmethacrylate (PMMA), or a cycloolefin copolymer (“COC”). 
     The front laminate structure  300  may include front coupling members  351 ,  352 , and  353  coupling adjacent laminated members. For example, a first front coupling member  351  may be disposed between the cover window  320  and the cover window protection layer  310  to couple the cover window  320  and the cover window protection layer  310 , a second front coupling member  352  may be disposed between the cover window  320  and the polarization member  330  to couple the cover window  320  and the polarization member  330 , and a third front coupling member  353  may be disposed between the polarization member  330  and the display panel  100  to couple the polarization member  330  and the display panel  100 . That is, the front coupling members  351 ,  352 , and  353  are members for attaching layers onto one surface (i.e., front surface) of the display panel  100 . Here, the first front coupling member  351  may be a protection layer coupling member for attaching the cover window protection layer  310 , the second front coupling member  352  may be a window coupling member for attaching the cover window  320 , and the third front coupling member  353  may be a polarization unit coupling member for attaching the polarization member  330 . The front coupling members  351 ,  352 , and  353  may all be optically transparent. 
     The rear laminate structure  400  is disposed below the display panel  100 . The rear laminate structure  400  may include a polymer film layer  410  disposed below the display panel  100 . 
     The polymer film layer  410  may include a polymer. The polymer film layer  410  may include, for example, polyimide (PI), polyethylene terephthalate (PET), polycarbonate (PC), polyethylene (“PE”), polypropylene (“PP”), polysulfone (“PSF”), polymethylmethacrylate (PMMA), triacetyl cellulose (“TAC”), or a cycloolefin polymer (“COP”). The polymer film layer  410  may include a function layer on at least one surface thereof. The function layer may include, for example, a light absorbing layer. The light absorbing layer may include a light absorbing material such as a black pigment or dye. The light absorbing layer may be formed on a polymer film by coating or printing using black ink. 
     The rear laminate structure  400  may include a rear coupling member  451  for coupling adjacent laminated members. For example, the rear coupling member  451  may be disposed between the display panel  100  and the polymer film layer  410  to couple the display panel  100  and the polymer film layer  410 . 
     A first barrier member  420  and a metal plate  200  may be disposed below the display module  10 . 
     In an embodiment, the first barrier member  420  may be disposed below the polymer film layer  410 . The first barrier member  420  may prevent foreign matter from being introduced into the display module  10  from the outside. The first barrier member  420  may include or be made of a stretchable material having a variable length according to folding and unfold operations of the display device  1 . A detailed configuration of the first barrier member  420  will be described later. 
     Referring to  FIGS.  1  to  4   , the display device  1  according to an embodiment may include a metal plate  200  disposed below the display module  10 . 
     The metal plate  200  may be disposed on the rear surface of the first barrier member  420 . The metal plate  200  may be disposed to overlap the first non-folding area NFA 1 , the folding area FA, and the second non-folding area NFA 2 . The metal plate  200  has flexibility, and may be folded with respect to the folding axis FX. The metal plate  200  may be configured to be stretchable at least partially by including a pattern defining a plurality of openings. 
     The metal plate  200  may have a rectangular shape that is long in the second direction Y and short in the first direction X in a plan view, but the shape thereof is not limited thereto. In an embodiment, the metal plate  200  may include front and rear surfaces parallel to a plane defined by crossing the first direction X and the second direction Y, and side surfaces extending in the third direction Z between the front and back surfaces. 
     The metal plate  200  may have a larger size than the display module  10 . In some embodiments, the length of the metal plate  200  in the first direction X and the length of the metal plate  200  in the second direction Y may be larger than those of the display module  10 , respectively. The metal plate  200  may have a thin thickness of about 0.1 millimeters (mm) to 0.2 mm in the third direction Z. 
     The metal plate  200  may include stainless steel. The stainless steel may include at least one of iron, chromium, carbon, nickel, silicon, manganese, molybdenum, or alloys thereof. In an embodiment, the metal plate  200  may include or be made of austenitic stainless steel. 
     In an embodiment, the metal plate  200  may include a first plate portion  210 , a second plate portion  220 , and a connection portion  230 . 
     The first plate portion  210  and the second plate portion  220  are arranged in the second direction Y. The first plate portion  210  and the second plate portion  220  may be symmetrically arranged with respect to the folding axis FX or the folding area FA. In an embodiment, the first plate portion  210  may be disposed to overlap the first non-folding area NFA 1 , and the second plate portion  220  may be disposed to overlap the second non-folding area NFA 2 . Accordingly, the first plate portion  210  and the second plate portion  220  may maintain flatness regardless of folding of the display device  1 . Each of the first plate portion  210  and the second plate portion  220  may have a rectangular shape on a plane, but the shape thereof is not limited thereto. In an embodiment, when the display device  1  is folded, the first plate portion  210  and the second plate portion  220  may be portions that maintain a length or size without being stretched compared those in the unfolded state. 
     The connection portion  230  may be disposed between the first plate portion  210  and the second plate portion  220 . The connection portion  230  may be disposed in the folding area FA. The connection portion  230  may be disposed to overlap the folding axis FX in the thickness direction and extends in the first direction X. The connection portion  230  has flexibility. The connection portion  230  may be stretched or compressed by folding or unfolding of the metal plate  200 . The connection portion  230  may have higher elasticity than the first plate portion  210  and/or the second plate portion  220 . The connection portion  230  may reduce tensile or compressive stress caused by bending of the metal plate  200 . The connection portion  230  may include a pattern defining a plurality of openings. 
     The first barrier member  420  and the metal plate  200 , described above, may be coupled through the second coupling member  520  and the first coupling member  510 , respectively, so as to be coupled to the rear of the display module  10 . 
     Specifically, the second coupling member  520  may be disposed between the polymer film layer  410  and the first barrier member  420  to couple the polymer film layer  410  and the first barrier member  420 . Further, the first coupling member  510  may be disposed between the first barrier member  420  and the metal plate  200  to couple the first barrier member  420  and the metal plate  200 . 
     Hereinafter, the first barrier member  420  and the metal plate  200  will be described in more detail with reference to  FIGS.  6  and  7   . 
       FIG.  6    is a cross-sectional view illustrating a portion of a display device according to an embodiment,  FIG.  7    is a cross-sectional view illustrating a portion of a display device according to an embodiment in a folded state, and  FIG.  8    is a schematic cross-sectional view of a connection portion between a first coupling member and a metal plate. In order to illustrate a relationship between the first barrier member  420  and the metal plate  200 , in  FIGS.  6  and  7   , only the polymer film layer  410 , the second coupling member  520 , the first barrier member  420 , the first coupling member  510 , and the metal plate  200  of the display device  1  will be illustrated and described. 
     Referring to  FIG.  6   , the display device  1  according to an embodiment may include a polymer film layer  410 , a second coupling member  520  disposed on the rear surface (i.e., lower surface) of the polymer film layer  410 , a first barrier member  420  disposed on the rear surface of the second coupling member  520 , a first coupling member  510  disposed on the rear surface of the first barrier member  420 , and a metal plate  200  disposed on the rear surface of the first coupling member  510 . 
     In an embodiment, the first barrier member  420  may have a large modulus so as not to be deformed by the shape of a lattice pattern of the connection portion  230  of the metal plate  200 . For example, the first barrier member  420  may include or be made of a material having a modulus of about 1 gigapascals (GPa) or more. Specifically, the first barrier member  420  may have a modulus ranging from about 1 GPa to about 300 GPa. 
     In an embodiment, the first barrier member  420  may include a polymer material having elastic or plastic properties. The first barrier member  420  may include, for example, at least one selected from polyimide (PI), polyacrylate (“PA”), polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether sulfone (PES), polyarylate (PAR), and a cycloolefin copolymer (COC). 
     When the first barrier member  420  includes a polymer material, the first barrier member  420  may have a modulus ranging from about 1 GPa to about 10 GPa. Preferably, the first barrier member  420  may have a modulus ranging from about 3 GPa to about 7 GPa. 
     As shown in  FIG.  7   , in a state where the display device  1  is folded, the connection portion  230  of the metal plate  200  may contact the first barrier member  420  to apply a force pressing the first barrier member  420 . At this time, when high heat is applied, the shape of the lattice pattern of the connection portion  230  may remain in the first barrier member  420  pressed by the connection portion  230  to be recognized by the user. 
     In an embodiment, the modulus of the first barrier member  420  is made large in the range of about 1 GPa to about 10 GPa, so that the lattice pattern of the connection portion  230  of the metal plate  200  may not remain. Further, the thickness of the first barrier member  420  may be at least about 25 μm or more, and preferably in the range of about 25 μm to about 80 μm, so that the shape of the lattice pattern of the connection portion  230  may not remain. 
     In another embodiment, the first barrier member  420  may include a metal. The first barrier member  420  may include, for example, at least one selected from steel used stainless (SUS), invar, aluminum, iron, chromium, carbon, nickel, silicon, manganese, and molybdenum. 
     When the first barrier member  420  includes metal, the first barrier member  420  may have a modulus ranging from about 10 GPa to about 300 GPa. Preferably, the first barrier member  420  may have a modulus ranging from about 30 GPa to about 200 GPa. 
     In this embodiment, the modulus of the first barrier member  420  is made large in the range of about 10 GPa to about 300 GPa, so that the lattice pattern of the connection portion  230  of the metal plate  200  may not remain. Further, the thickness of the first barrier member  420  including a metal may be at least about 10 μm or more, and preferably in the range of about 10 μm to about 50 μm, so that the shape of the lattice pattern of the connection portion  230  may not remain. 
     In an embodiment, in order to prevent the lattice pattern of the connection portion  230  of the metal plate  200  from being viewed by the user, the first barrier member  420  may include a material that exhibits a black color, or black coating may be additionally performed on the upper or lower surface of the first barrier member  420 . 
     Referring to  FIG.  6   , the second coupling member  520  may be disposed between the first barrier member  420  and the polymer film layer  410  to couple the first barrier member  420  and the polymer film layer  410 . Further, the first coupling member  510  may be disposed between the first barrier member  420  and the metal plate  200  to couple the first barrier member  420  and the metal plate  200 . 
     The second coupling member  520  may be disposed on the entire rear surface of the polymer film layer  410 , and may be disposed on the entire front surface of the first barrier member  420 . The second coupling member  520  may be a pressure sensitive adhesive (“PSA”) layer, but is not limited thereto, and any material may be applied as long as it has adhesion or adhesive properties. 
     The first coupling member  510  may be disposed on the rear surface of the first barrier member  420 . The first coupling member  510  may include a first coupling portion  512  and a second coupling portion  514  spaced apart from each other. The first coupling member  510  may be disposed to overlap the first non-folding area NFA 1  and the second non-folding area NFA 2 , respectively. 
     The first coupling portion  512  and the second coupling portion  514  are arranged in the second direction Y. The first coupling portion  512  and the second coupling portion  514  may be symmetrically arranged with respect to the folding area FA. In an embodiment, the first coupling portion  512  may be disposed to overlap the first non-folding area NFA 1 , and the second coupling portion  514  may be disposed to overlap the second non-folding area NFA 2  in a plan view. Further, the first coupling portion  512  may be disposed to overlap the first plate portion  210  of the metal plate  200 , and the second coupling portion  514  may be disposed to overlap the second plate portion  220  of the metal plate  200 . 
     A first spacing interval SW 1 , through which the first coupling portion  512  and the second coupling portion  514  are spaced apart from each other, may be defined between the first coupling portion  512  and the second coupling portion  514 . The first spacing interval SW 1  is an empty space. The first spacing interval SW 1  may be mainly defined in the folding area FA. The first spacing interval SW 1  may be defined to extend in the first direction X. 
     In an embodiment, the first spacing interval SW 1  defined in the first coupling member  510  may overlap the connection portion  230  of the metal plate  200  in a plan view. 
     As shown in  FIG.  8   , in a case that the first coupling member  510  overlaps the connection portion  230  of the metal plate  200 , a phenomenon in which the first coupling member  510  is pinched in the connection portion  230  of the metal plate  200  occurs. Specifically, when the folding and unfolding of the display device  1  are repeated under high-temperature and high-humidity conditions, the first coupling member  510  may be pinched between the lattice patterns of the connection portion  230 . Thus, a bending deformation in which the display module  10  sags downward in the unfolded state of the display device  1  may occur, and thus the shape of the lattice pattern may be visually recognized. 
     In an embodiment, the first spacing interval SW 1  in the first coupling member  510  may be defined to overlap the connection portion  230  of the metal plate  200 , thereby preventing the shape of the lattice pattern of the connection portion  230  of the metal plate  200  from being visually recognized. For this purpose, it is preferable that the first spacing interval SW 1  in the first coupling member  510  is equal to or larger than the width MW of the connection portion  230  of the metal plate  200 . 
     Referring to  FIG.  6    again, in order to improve the impact resistance characteristics of the display device  1  in an embodiment, each of the first coupling member  510  and the second coupling member  520  may have a predetermined thickness range. 
     Specifically, the thickness T 2  of the second coupling member  520  may be about 1 μm to about 50 μm. The second coupling member  520  may have an optimal thickness T 2  for coupling the polymer film layer  410  and the first barrier member  420 . In this case, the sum T 1 +T 2  of the thickness T 1  of the first coupling member  510  and the thickness T 2  of the second coupling member  520  may be greater than about 1 μm and equal to or less than about 80 μm or less. As the thickness T 1  of the first coupling member  510  and the thickness T 2  of the second coupling member  520  increase, impact resistance characteristics may gradually deteriorate, and thus, preferably, the thickness T 1  of the first coupling member  510  and the thickness T 2  of the second coupling member  520  may not exceed about 80 μm. The thickness T 1  of the first coupling member  510  is not limited as long as it satisfies the above conditions, but, preferably, the thickness T 1  may be about 25 μm or less in order to prevent the sagging of the first coupling member  510 . 
       FIG.  9    is a cross-sectional view of a display device according to another embodiment, and  FIG.  10    is a cross-sectional view illustrating a portion of the display device according to the embodiment in  FIG.  9   . In  FIG.  10   , a first coupling member  510 , a metal plate  200 , a second barrier member  250 , and a heat dissipation member  600  are illustrated and described. 
     Referring to  FIGS.  9  and  10   , the display device  1  according to the present embodiment may include a first barrier member  420  and a metal plate  200 . In particular, the present embodiment is different from the embodiment described with reference to  FIGS.  4  and  6  to  8    in that the second barrier member  250  is further disposed below the metal plate  200 , and other components are substantially the same or similar to each other. Therefore, a redundant description will be omitted, and differences will be mainly described. 
     Referring to  FIG.  9   , the second barrier member  250  may be disposed on the rear surface of the metal plate  200 . The second barrier member  250  may prevent foreign matter from entering the display module  10  from the outside. The second barrier member  250  may include or be made of a stretchable material having a variable length according to folding and unfolding operations of the display device  1 . 
     In an embodiment, the second barrier member  250  may have a small modulus so as to respond to the folding and unfolding operations of the display device  1 . For example, the second barrier member  250  may include or be made of a material having a modulus of less than about 1 GPa. In an embodiment, the second barrier member  250  may include a polymer material having hyper elastic properties. The second barrier member  250  may include, for example, thermoplastic polyurethane (“TPU”) having elasticity. The second barrier member  250  may have a thickness ranging from about 1 μm to about 20 μm. 
     A third coupling member  530  is disposed between the metal plate  200  and the second barrier member  250  to couple the metal plate  200  and the second barrier member  250 . 
     The third coupling member  530  may be disposed to overlap the first plate portion  210 , the second plate portion  220 , and the connection portion  230  of the metal plate  200 . In particular, the third coupling member  530  may overlap the connection portion  230  in a plan view to prevent foreign matter from entering the display module  10 . 
     A heat dissipation member  600  may be disposed on the rear surface of the third coupling member  530 . More specifically, the heat dissipation member  600  may be disposed on a rear surface of a fourth coupling member  540  (to be described later). The heat dissipation member  600  serves to diffuse heat generated from the display panel  100  or other components of the display device  1 . In some embodiments, the heat dissipation member  600  may include a first heat dissipation layer including graphite or carbon nanotubes, and a second heat dissipation layer formed of a metal thin film including copper, nickel, ferrite, or silver, which may block electromagnetic waves and have excellent thermal conductivity. 
     The heat dissipation member  600  may be disposed to overlap the first non-folding area NFA 1 , the folding area FA, and the second non-folding area NFA 2 . The heat dissipation member  600  may have a rectangular shape that is long in the second direction Y and short in the first direction X in a plan view, but the shape thereof is not limited thereto. The heat dissipation member  600  may have a smaller size than each of the display module  10  and the metal plate  200 . In some embodiments, the length of the heat dissipation member  600  in the first direction X and the length of the heat dissipation member  600  in the second direction Y may be smaller than those of each of the display module  10  and the metal plate  200 , respectively. 
     In an embodiment, the heat dissipation member  600  may include a first heat dissipation portion  610  and a second heat dissipation portion  620  spaced apart from each other. 
     The first heat dissipation portion  610  and the second heat dissipation portion  620  are arranged in the second direction Y. The first heat dissipation portion  610  and the second heat dissipation portion  620  may be symmetrically arranged with respect to the folding area FA. In an embodiment, the first heat dissipation portion  610  may be disposed to overlap the first non-folding area NFA 1 , and the second heat dissipation portion  620  may be disposed to overlap the second non-folding area NFA 2 . Further, the first heat dissipation portion  610  may be disposed to overlap the first plate portion  210  of the metal plate  200 , and the second heat dissipation portion  620  may be disposed to overlap the second plate portion  220  of the metal plate  200  in a plan view. 
     A second spacing interval SW 2 , through which the first heat dissipation portion  610  and the second heat dissipation portion  620  are spaced apart from each other, may be defined between the first heat dissipation portion  610  and the second heat dissipation portion  620 . The second spacing interval SW 2  may be defined in the folding area FA, and may be defined to overlap the connection portion  230  of the metal plate  200  in a plan view. The second spacing interval SW 2  is an empty space. Due to the second spacing interval SW 2 , the first heat dissipation portion  610  and the second heat dissipation portion  620  may maintain flatness regardless of folding of the display device  1  in the folded state of the display device  1 . In an embodiment, even when the display device  1  is folded, the first heat dissipation portion  610  and the second heat dissipation portion  620  may be portions that maintain a length or a size without stretching. In an embodiment, the second spacing interval SW 2  may be smaller than the width MW of the connection portion  230  of the metal plate  200 . 
     A fourth coupling member  540  may be disposed between the heat dissipation member  600  and the second barrier member  250 . 
     The fourth coupling member  540  may be disposed on the rear surface of the second barrier member  250 . The fourth coupling member  540  may include a third coupling portion  542  and a fourth coupling portion  544  spaced apart from each other. The fourth coupling member  540  may be disposed to overlap the first non-folding area NFA 1  and the second non-folding area NFA 2  in a plan view. 
     The third coupling portion  542  and the fourth coupling portion  544  are arranged in the second direction Y. The third coupling portion  542  and the fourth coupling portion  544  may be symmetrically arranged with respect to the folding area FA. In an embodiment, the third coupling portion  542  may be disposed to overlap the first non-folding area NFA 1 , and the fourth coupling portion  544  may be disposed to overlap the second non-folding area NFA 2 . Further, the third coupling portion  542  may be disposed to overlap the first plate portion  210  of the metal plate  200 , and the fourth coupling portion  544  may be disposed to overlap the second plate portion  220 . 
     A third spacing interval SW 3 , through which the third coupling portion  542  and the fourth coupling portion  544  are spaced apart from each other, may be defined between the third coupling portion  542  and the fourth coupling portion  544 . The third spacing interval SW 3  may be mainly defined in the folding area FA. The third spacing interval SW 3  is an empty space. The third spacing interval SW 3  may be defined to extend in the first direction X. 
     In an embodiment, the third spacing interval SW 3  of the fourth coupling member  540  may overlap the connection portion  230  of the metal plate  200  in a plan view. Further, the third spacing interval SW 3  in the fourth coupling member  540  may overlap the second spacing interval SW 2  of the heat dissipation member  600 . The third spacing interval SW 3  in the fourth coupling member  540  may be larger than the second spacing interval SW 2  of the heat dissipation member  600 . That is, the folding operation of the display device  1  may be facilitated by preventing the heat dissipation member  600  from being attached to the fourth coupling member  540  in the folding area FA. 
       FIG.  11    is a cross-sectional view of a display device according to still another embodiment, and  FIG.  12    is a cross-sectional view illustrating a portion of a display device according to the embodiment of  FIG.  11   . In  FIG.  12   , a first coupling member  510 , a metal plate  200 , a second barrier member  250 , a heat dissipation member  600 , and a cushion member  700  are illustrated and described. 
     Referring to  FIGS.  11  and  12   , the display device  1  according to the present embodiment may include a first barrier member  420 , a metal plate  200 , a second barrier member  250 , and a heat dissipation member  600 . In particular, the present embodiment is different from the embodiment described with reference to  FIGS.  4  and  6  to  10    in that the cushion member  700  is further disposed below the heat dissipation member  600 , and function holes PH 1  and PH 2  are arranged in the display device  1 , and other components are substantially the same or similar to each other. Therefore, a redundant description will be omitted, and differences will be mainly described. 
     Referring to  FIGS.  11  and  12   , the cushion member  700  may be further disposed below the heat dissipation member  600 . The cushion member  700  may absorb external impacts to prevent the display panel  100  from being damaged. The cushion member  700  may be a single layer or a plurality of laminated layers. The cushion member  700  may include or be made of, for example, a material having elasticity such as polyurethane or polyethylene resin. In an embodiment, the cushion member  700  may include or be made of a foam material similar to a sponge. 
     In an embodiment, the cushion member  700  may be disposed to overlap the first non-folding area NFA 1 , the folding area FA, and the second non-folding area NFA 2 . The cushion member  700  may have a rectangular shape that is long in the second direction Y and short in the first direction X in a plan view, but the shape thereof is not limited thereto. The cushion member  700  may have a smaller size than each of the display module  10  and the metal plate  200 . In some embodiments, the length of the cushion member  700  in the first direction X and the length of the cushion member  700  in the second direction Y may be smaller than those of each of the display module  10  and the metal plate  200 , respectively. Further, the cushion member  700  may have substantially the same size as the aforementioned heat dissipation member  600 . 
     In an embodiment, the cushion member  700  may include a first cushion portion  710  and a second cushion portion  720  spaced apart from each other. 
     The first cushion portion  710  and the second cushion portion  720  are arranged in the second direction Y. The first cushion portion  710  and the second cushion portion  720  may be symmetrically arranged with respect to the folding area FA. In an embodiment, the first cushion portion  710  may be disposed to overlap the first non-folding area NFA 1 , and the second cushion portion  720  may be disposed to overlap the second non-folding area NFA 2  in a plan view. Further, the first cushion portion  710  may be disposed to overlap the first plate portion  210  of the metal plate  200 , and the second cushion portion  720  may be disposed to overlap the second plate portion  220 . 
     A fourth spacing interval SW 4 , through which the first cushion portion  710  and the second cushion portion  720  are separated from each other, may be defined between the first cushion portion  710  and the second cushion portion  720 . The fourth spacing interval SW 4  may be defined in the folding area FA, and may be defined to overlap the connection portion  230  of the metal plate  200 . The fourth spacing interval SW 4  is an empty space. Due to the fourth spacing interval SW 4 , the first cushion portion  710  and the second cushion portion  720  may maintain flatness regardless of folding of the display device  1  even in the folded state of the display device  1 . In an embodiment, even when the display device  1  is folded, the first cushion portion  710  and the second cushion portion  720  may be portions that maintain a length or a size without stretching. In an embodiment, the fourth spacing interval SW 4  may be smaller than the width MW of the connection portion  230  of the metal plate  200 . The fourth spacing interval SW 4  of the cushion member  700  may overlap the second spacing interval SW 2  of the heat dissipation member  600 , and may have substantially the same width as the second spacing interval SW 2  of the heat dissipation member  600 . 
     A fifth coupling member  550  may be disposed between the cushion member  700  and the heat dissipation member  600 . 
     The fifth coupling member  550  may be disposed on the rear surface of the heat dissipation member  600 . The fifth coupling member  550  may include a fifth coupling portion  552  and a sixth coupling portion  554  spaced apart from each other. The fifth coupling member  550  may be disposed to overlap the first non-folding area NFA 1  and the second non-folding area NFA 2 . 
     The fifth coupling portion  552  and the sixth coupling portion  554  are arranged in the second direction Y. The fifth coupling portion  552  and the sixth coupling portion  554  may be symmetrically arranged with respect to the folding area FA. In an embodiment, the fifth coupling portion  552  may be disposed to overlap the first non-folding area NFA 1 , and the sixth coupling portion  554  may be disposed to overlap the second non-folding area NFA 2 . Further, the fifth coupling portion  552  may be disposed to overlap the first plate portion  210  of the metal plate  200 , and the sixth coupling portion  554  may be disposed to overlap the second plate portion  220 . 
     A fifth spacing interval SW 5 , through which the fifth coupling portion  552  and the sixth coupling portion  554  are spaced apart from each other, may be defined between the fifth coupling portion  552  and the sixth coupling portion  554 . The fifth spacing interval SW 5  may be defined in the folding area FA. The fifth spacing interval SW 5  may be defined to extend in the first direction X. The fifth spacing interval SW 5  is an empty space. 
     In an embodiment, the fifth spacing interval SW 5  in the fifth coupling member  550  may overlap the connection portion  230  of the metal plate  200 . Further, the fifth spacing interval SW 5  of the fifth coupling member  550  may overlap the second spacing interval SW 2  of the heat dissipation member  600 , and may overlap the fourth spacing interval SW 4  of the cushion member  700  in a plan view. Further, the fifth spacing interval SW 5  in the fifth coupling member  550  may be substantially the same as the second spacing interval SW 2  of the heat dissipation member  600  and the fourth spacing interval SW 4  of the cushion member  700 . 
     Referring to  FIG.  11   , the display device  1  may further include a plurality of function holes PH 1  and PH 2 . 
     The plurality of function holes PH 1  and PH 2  may be defined to overlap the first non-folding area NFA 1  or the second non-folding area NFA 2 . In an embodiment, the plurality of function holes PH 1  and PH 2  may be defined in the second non-folding area NFA 2 , and may penetrate predetermined structures in the third direction Z. 
     An infrared sensor or a motion sensor may be disposed in the first function hole PH 1 , and a camera may be disposed in the second function hole PH 2 . The first function hole PH 1  may penetrate the first barrier member  420 , the metal plate  200 , the second barrier member  250 , the heat dissipation member  600 , and the cushion member  700 . In an embodiment, the first function hole PH 1  may penetrate the second coupling member  520 , the first barrier member  420 , the first coupling member  510 , the metal plate  200 , the third coupling member  530 , the second barrier member  250 , the fourth coupling member  540 , the heat dissipation member  600 , the fifth coupling member  550 , and the cushion member  700 . 
     The second function hole PH 2  may penetrate other laminate structures except for the cover window  320  and the cover window protection layer  310 . In an embodiment, the second function hole PH 2  may penetrate the second front coupling member  352 , the polarization member  330 , the third front coupling member  353 , the display panel  100 , the first rear coupling member  451 , the polymer film layer  410 , the second coupling member  520 , the first barrier member  420 , the first coupling member  510 , the metal plate  200 , the third coupling member  530 , the second barrier member  250 , the fourth coupling member  540 , the heat dissipation member  600 , the fifth coupling member  550 , and the cushion member  700 . 
     In the display devices according to the aforementioned embodiments, the cushion member may be disposed on the rear surface (i.e., lower surface) of the metal plate, thereby improving impact resistance characteristics. Further, the first barrier member having a large modulus may be disposed, thereby preventing the shape of the lattice pattern of the connection portion of the metal plate from being visually recognized. Further, the thicknesses of the first coupling member and the second coupling member respectively disposed over and under the first barrier member may be set in a predetermined range, thereby improving impact resistance characteristics. Further, the first coupling member disposed between the first barrier member and the metal plate may be formed not to overlap the connection portion of the metal plate, thereby preventing the display module from sagging in an area overlapping the connection portion of the metal plate. 
     Hereinafter, the impact resistance characteristics and pattern visibility characteristics of the display devices according to the aforementioned embodiments will be described through Manufacturing Examples and Experimental Examples. 
       FIG.  13    is a cross-sectional view illustrating a display device sample #1 according to Manufacturing Example. 
     Manufacturing Example 1: Manufacturing of Display Device Sample 
     The display device shown in  FIG.  13    was manufactured as display device sample #1. Specifically, a display device in which a cover window protection layer  310 , a first front coupling member  351 , a cover window  320 , a second front coupling member  352 , a polarization member  330 , a third front coupling member  353 , a display panel  100 , a first rear coupling member  451 , a polymer film layer  410 , a second coupling member  520 , a first barrier member  420 , a cushion member  700 , a first coupling member  510 , a metal plate  200 , a third coupling member  530 , a second barrier member  250 , a fourth coupling member  540 , a first heat dissipation member  640 , a fifth coupling member  550 , and a second heat dissipation member  650  are sequentially laminated was manufactured. 
     The display device shown in  FIG.  11    was manufactured as display device sample #2. Since the display device of  FIG.  11    has been described above, a description thereof is omitted. In this case, the display device sample #2 was manufactured such that the sum of the thickness of the first coupling member  510  and the thickness of the second coupling member  520  was about 110 μm. 
     Display device sample #3 was manufactured in the same manner as in the display device sample #2 except that the sum of the thickness of the first coupling member  510  and the thickness of the second coupling member  520  was about 80 μm. 
     Display device sample #4 was manufactured in the same manner as in the display device sample #2 except that the sum of the thickness of the first coupling member  510  and the thickness of the second coupling member  520  was about 65 μm. 
     Display device sample #5 was manufactured in the same manner as in the display device sample #2 except that the sum of the thickness of the first coupling member  510  and the thickness of the second coupling member  520  was about 50 μm. 
     Display device sample #6 was manufactured in the same manner as in the display device sample #2 except that the sum of the thickness of the first coupling member  510  and the thickness of the second coupling member  520  was about 35 μm. 
     Display device sample #7 was manufactured in the same manner as in the display device sample #2 except that the sum of the thickness of the first coupling member  510  and the thickness of the second coupling member  520  was about 25 μm. 
     Experimental Example 1: Measurement of Impact Resistance Characteristics 
     A pencil drop test was performed on each of the display device samples #1 to #7 to measure impact resistance characteristics. Results thereof are given in Table 1 below. In Table 1, the effect of improving impact resistance is based on an increase in pencil drop height with respect to the display device sample #1. 
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Sample# 
                 #1 
                 #2 
                 #3 
                 #4 
                 #5 
                 #6 
                 #7 
               
               
                   
               
             
            
               
                 Pencil drop height 
                 — 
                 — 
                 1 cm 
                 2 cm 
                 3 cm 
                 4 cm 
                 5 cm 
               
               
                   
               
            
           
         
       
     
     Referring to Table 1 above, with respect to the display device sample #1 in which the cushion member  700  is disposed on the metal plate  200 , pencil drop heights were increased in samples #3 to #7 in each which the cushion member  700  is disposed under the metal plate  200 . In particular, in the display device sample #2 in which the sum of the thicknesses of the first coupling member  510  and the thickness of the second coupling member  520  is about 110 μm, the pencil drop height was not changed, but in the display device samples #3 to #7 in each which the sum of the thicknesses of the first coupling member  510  and the thickness of the second coupling member  520  is about 80 μm, about 65 μm, about 50 μm, about 35 μm, and about 25 μm, respectively, the pencil drop height was increased as the sum of the thicknesses of the first coupling member  510  and the thickness of the second coupling member  520  was decreased. 
     Consequently, in the display device  1  according to an embodiment, the sum of the thicknesses of the first coupling member  510  and the thickness of the second coupling member  520  is in a range of about 25 μm to about 80 μm, and thus it may be seen that impact resistance characteristics are improved. 
       FIG.  14    is a cross-sectional view illustrating a display device sample #8 according to Manufacturing Example. 
     Manufacturing Example 2: Manufacturing of Display Device Sample 
     The display device shown in  FIG.  14    was manufactured as display device sample #8. Specifically, a display device in which a cover window protection layer  310 , a first front coupling member  351 , a cover window  320 , a second front coupling member  352 , a polarization member  330 , a third front coupling member  353 , a display panel  100 , a first rear coupling member  451 , a polymer film layer  410 , a second coupling member  520 , a first barrier member  420 , a first coupling member  510 , a second barrier member  250 , a third coupling member  530 , a metal plate  200 , a fourth coupling member  540 , a heat dissipation member  600 , a fifth coupling member  550 , and a cushion member  700  are sequentially laminated was manufactured. In this case, the display device was manufactured such that the thickness of each of the second coupling member  520  and the first barrier member  420  disposed on the metal plate  200  is about 25 μm and the thickness of each of the first coupling member  510 , the second barrier member  250 , and the third coupling member  530  is about 8 μm. 
     The display device shown in  FIG.  11    was manufactured as display device sample #9. Since the display device of  FIG.  11    has been described above, a description thereof is omitted. In this case, the display device sample #9 was manufactured such that the thickness of each of the second coupling member  520  and the first barrier member  420  is about 25 μm and the thickness of the first coupling member  510  is about 8 μm. Further, the display device sample #9 was manufactured such that the first barrier member  420  has a modulus of about 4.5 GPa and includes polyimide. 
     Display device sample #10 was manufactured in the same manner as in the display device sample #9 except that the modulus of the barrier member  420  was about 10 GPa. 
     Display device sample #11 was manufactured in the same manner as in the display device sample #9 except that the thickness of the barrier member  420  was 3 about 5 μm. 
     Display device sample #12 was manufactured in the same manner as in the display device sample #9 except that the thickness of the first coupling member  510  was about 16 μm. 
     Experimental Example 2: Measurement of Lattice Pattern Visibility 
     Each of the display device samples #8 to #12 was stored under conditions of a temperature 60 degrees Celsius (° C.) and a humidity of 93 percentages (%) for 24 hours in a folded state, and then a height profile was measured from the center of the connection portion of the metal plate to the edge thereof using a 3D profile meter. Results thereof are shown in  FIG.  15   .  FIG.  15    is a graph showing a height profile according to a distance from the center of the connection portion of the metal plate in each of the display device samples. 
     Referring to  FIG.  15   , in the display device sample #8 in which the first and second barrier members  420  and  250  are disposed on the metal plate  200 , the step between the low point and high point of the height profile of the display device in an area overlapping the connection portion  230  of the metal plate  200  was about 1 μm or more. That is, the shape of the lattice pattern of the connection portion  230  of the metal plate  200  causes the deformation of the display module disposed on the metal plate  200 , and thus the display module is uneven. Accordingly, when the step between the low point and high point in the folding area FA overlapping the connection portion  230  of the metal plate  200  is about 1 μm or more, the step may be visually recognized by the user. 
     Further, even in the display device sample #9 in which only the first barrier member  420  is disposed on the metal plate  200 , the step between the low point and high point of the height profile of the display device in an area overlapping the connection portion  230  of the metal plate  200  was also about 1 μm or more, the shape of the lattice pattern was visually recognized to some degree. 
     On the other hand, in the same structure as the display device sample #9, in the display device sample #10 in which the modulus of the first barrier member  420  was increased to about 10 GPa, the display device sample #11 in which the thickness of the first barrier member  420  was increased to about 35 μm, and the display device sample #12 in which the thickness of the first coupling member  510  was increased to about 16 μm, the step between the low point and high point of the height profile of the display device in an area overlapping the connection portion  230  of the metal plate  200  was about 0.5 μm or less. That is, the step according to the deformation of the display module due to the shape of the lattice pattern of the connection portion was not visually recognized by the user. 
     Consequently, when the thickness and modulus of the first barrier member  420  are increased and the thickness of the first coupling member  510  is increased, the step according to the deformation of the display module due to the shape of the lattice pattern of the connection portion may be decreased to prevent the step from being visually recognized by the user. 
     According to a display device of embodiments, a cushion member may be disposed on a metal plate, thereby preventing impact resistance. 
     Further, according to a display device of embodiments, a first barrier member having a large modulus may be disposed, thereby preventing the lattice pattern shape of a connection portion of the metal plate from being viewed. 
     Further, according to a display device of embodiments, the thickness of each of a first coupling member and a second coupling member disposed on and under the first barrier member may be set in a predetermined range, thereby improving impact resistance. 
     Further, according to a display device of embodiments, the first coupling member disposed between the first barrier member and the metal plate may be formed not to overlap the connection portion of the metal plate, thereby preventing a display module from sagging in an area overlapping the connection portion of the metal plate. 
     Although the preferred embodiments of the disclosure have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. 
     In concluding the detailed description, those skilled in the art will appreciate that many variations and modifications can be made to the preferred embodiments without substantially departing from the principles of the present invention. Therefore, the disclosed preferred embodiments of the invention are used in a generic and descriptive sense only and not for purposes of limitation.