Patent Publication Number: US-2023161380-A1

Title: Display device

Description:
This application claims priority to Korean Patent Application No. 10-2021-0164667, filed on Nov. 25, 2021, 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 
     (a) Field 
     Embodiments of the invention relate to a display device, and particularly relate to a rollable display device. 
     (b) Description of the Related Art 
     Together with a recent development of display-related technology, deformable display devices, such as foldable, rollable in a roll shape, or stretchable like a rubber band during use are being researched and developed. As the display device is modifiable in various shapes, a request of enlarging the display device in the use stage and a request of down-sizing the display for the purpose of portability may be satisfied. 
     The display device that may be transformed such as a rollable display device includes a supporter for supporting a display panel when the display panel is unfolded. 
     SUMMARY 
     Embodiments of the invention have been made in an effort to reduce a thickness of a rollable display device and improve surface quality of a display panel when the display panel is unwound and wound. 
     An embodiment of the invention provides a display device including a display panel including a first surface which displays images and a second surface opposite to the first surface, a supporter disposed on the second surface of the display panel, a roller to which a first end of the display panel and a first end of the supporter are connected and on which the display panel and the supporter are wound, a first case to which a second end of the display panel opposite to the first end of the display panel is connected, a second case which is disposed on the first case and to which an end of the roller is connected, and an elasticity member connected between the first case and the second case, where the second case and the first case at least partly overlap each other and slide. 
     In an embodiment, the first case may slide in a first direction with respect to the second case, and the elasticity member may extend in the first direction. 
     In an embodiment, the supporter may have a form bent upward or downward while the display panel and the supporter are unfolded from the roller in an unwinding state, and the supporter may be unfolded and may be wound on the roller while the display panel and the supporter are wound on the roller in a winding state. 
     In an embodiment, the display panel may be disposed further outside than the supporter while the display panel and the supporter are wound on the roller. 
     In an embodiment, the elasticity member may include an extension spring, and while the display panel and the supporter are unfolded from the roller in an unwinding state and are wound on the roller in a winding state, the extension spring may be extended. 
     In an embodiment, a length of the extension spring when the display panel and the supporter are wound may be greater than a length of the extension spring when the same are unwound. 
     In an embodiment, corresponding edges of the first case and the second case may be arranged while the display panel and the supporter are completely wound on the roller, and corresponding edges of the first case and the second case may be spaced apart from each other in the first direction while the display panel and the supporter are unfolded from the roller which is an unwinding state. 
     In an embodiment, the first case may further include a protrusion protruding from a side of the first case facing the second case, and a first end of the elasticity member may be connected to a lateral side of the protrusion and may be fixed thereto. 
     In an embodiment, the protrusion may be disposed near an edge connected to the display panel from among edges of the first case. 
     In an embodiment, a groove may be defined in the second case in a position corresponding to the protrusion, the elasticity member may be disposed in the groove, and the groove may extend in the first direction. 
     In an embodiment, the groove may include an end portion spaced apart from an opposite edge to the edge to which the supporter is connected from among edges of the second case, and a second end of the elasticity member may be connected to a lateral side of the end portion of the groove. 
     In an embodiment, at least one of the first case, the second case, and the roller may include a space therein. 
     In an embodiment, the display device may further include at least one of a battery and a circuit board disposed in an internal space. 
     In an embodiment, the display device may further include a guide rail disposed on a side of the second case facing the first case, where the guide rail may extend in a direction in which the first case slides with respect to the lower case. 
     In an embodiment, the display device may further include a fixing member for, when the display panel and the supporter are completely wound on the roller, fixing the first case on the second case. 
     Another embodiment of the invention provides a display panel including a first surface which displays images and a second surface opposite to the first surface, a supporter disposed on the second surface of the display panel, a roller to which a first end of the display panel and a first end of the supporter are connected and on which the display panel and the supporter are wound, a first case to which a second end of the display panel opposite to the first end of the display panel is connected, a second case which is disposed on the first case and to which an end of the roller is connected, and an elasticity member including a portion disposed between a first side of the first case facing the second case and a first side of the lower case facing the first case. 
     In an embodiment, the second case and the first case may at least partly overlap each other and slide in a first direction. 
     In an embodiment, the elasticity member may include an extension spring, and the extension spring may be extended while the display panel and the supporter are unfolded from the roller which is an unwinding state and are wound on the roller which is a winding state. 
     In an embodiment, a length of the extension spring when the display panel and the supporter are wound may be greater than a length of the extension spring when the display panel and the supporter are unwound. 
     Yet another embodiment of the invention provides a display panel including a first surface which displaying images and a second surface opposite to the first surface, a supporter disposed on the second surface of the display panel, a roller to which a first end of the display panel and a first end of the supporter are connected and on which the display panel and the supporter are wound, a first case to which a second end of the display panel opposite to the first end of the display panel is connected, a second case which is disposed on the first case and to which an end of the roller is connected, and an elasticity member connected between the first case and the second case, where a groove is defined in the lower case, the elasticity member is disposed in the groove, and the groove and the elasticity member extend in a same direction. 
     By the embodiments, the thickness of the rollable display device may be reduced, and the surface quality of the display panel may be improved when the display panel is unwound and wound. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other exemplary embodiments, advantages and features of this disclosure will become more apparent by describing in further detail exemplary embodiments thereof with reference to the accompanying drawings, in which: 
         FIG.  1    shows a perspective view of an embodiment of a display device when a display panel and a supporter of a display device are unwound. 
         FIG.  2    shows a perspective view of an embodiment of a display device when a display panel and a supporter of a display device are wound. 
         FIG.  3    shows a perspective view of an embodiment of a display device before a display panel of a display device is connected to an upper case. 
         FIG.  4    shows an embodiment of an elasticity member connected to an upper case and a lower case of a display device. 
         FIG.  5    shows a perspective view of an embodiment of a lower portion of an upper case of a display device. 
         FIG.  6    shows a perspective view of an embodiment of an upper portion of a lower case of a display device. 
         FIG.  7    shows a perspective view of an embodiment of a display device when a display panel and a supporter of a display device are unwound. 
         FIG.  8    shows an internal lateral view of an embodiment of a display device when a display panel and a supporter of a display device are unwound. 
         FIG.  9    shows a perspective view of an embodiment of a display device when a display panel and a supporter of a display device are wound. 
         FIG.  10    shows an internal lateral view of an embodiment of a display device when a display panel and a supporter of a display device are wound. 
         FIG.  11    to  FIG.  13    respectively shows a perspective view of an embodiment of a display device. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the invention will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the invention. 
     Parts that are irrelevant to the description will be omitted to clearly describe the invention, and the same elements will be designated by the same reference numerals throughout the specification. 
     Parts that are irrelevant to the description are omitted to clearly describe the invention, and like reference numerals designate like elements throughout the specification. The thicknesses of layers, films, panels, regions, etc., are enlarged for clarity. For ease of description, the thicknesses of some layers and areas are exaggerated. 
     It will be understood that when an element such as a layer, film, region, or substrate is also referred to as being “on” another element, it may be directly on the other element or intervening elements may also be present. In contrast, when an element is also referred to as being “directly on” another element, there are no intervening elements present. The word “on” or “above” means disposed on or below the object portion, and does not necessarily mean disposed on the upper side of the object portion based on a gravitational direction. 
     Unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. 
     The phrase “in a plan view” means viewing a target portion from the top, and the phrase “in a cross-sectional view” means viewing a cross-section formed by vertically cutting a target portion from the side. 
     It will be understood that, although the terms “first,” “second,” “third” etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, “a first element,” “component,” “region,” “layer” or “section” discussed below could be termed a second element, component, region, layer or section without departing from the teachings herein. 
     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. “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. In an embodiment, when 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, when 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). The term “about” can mean within one or more standard deviations, or within ±30%, 20%, 10%, 5% of the stated value, for example. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the invention, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     Embodiments are described herein with reference to cross section illustrations that are schematic illustrations of idealized embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. In an embodiment, a region illustrated or described as flat may, typically, have rough and/or nonlinear features. Moreover, sharp angles that are illustrated may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the claims. 
     A detailed structure of a display device in an embodiment will now be described with reference to  FIG.  1    and  FIG.  2   . 
       FIG.  1    shows a perspective view of an embodiment a display device when a display panel and a supporter of a display device are unwound, and  FIG.  2    shows a perspective view of an embodiment of a display device when a display panel and a supporter of a display device are wound. 
     Referring to  FIG.  1    and  FIG.  2   , the display device  1000  includes, as a rollable display device, a display panel  100 , at least one supporter  200 , a roller  300 , an upper case  400 , and a lower case  500 . 
     The display panel  100  and the supporter  200  may be flexible, and may be wound and unwound. That is, the display panel  100  and the supporter  200  may be wound on the roller  300  or may be unfolded (or unwound) to an outside from the roller  300 . Hereinafter, being wound on the roller  300  will also be also referred to as being rolled up thereon. 
     The display panel  100  may include a plurality of pixels for displaying images. The display panel  100  may display the images in a z direction that is an upper direction in  FIG.  1   . That is, the display panel  100  may include a display area going in the z direction and substantially extending in an xy plane. 
     The supporter  200  may be disposed on a lower portion of the display panel  100  and may support the display panel  100  at the lower portion while the display panel  100  is unfolded. 
     The supporter  200  may be disposed on the lower portion of the display panel  100  and may include at least two portions spaced apart from each other. The at least two portions of the supporter  200  spaced apart from each other may include two portions disposed on two edges of the display panel  100  facing each other in they direction. The two edges of the display panel  100  facing each other in they direction may extend in the x direction as shown in  FIG.  1   . 
     A cross-section of the supporter  200  may have a shape supporting the display panel  100 . In an embodiment, the cross-section of the supporter  200  with respect to the yz plane may have a plate shape bent upward or downward, for example.  FIG.  1    exemplifies a shape of the supporter  200  bent downward in a convex way, and without being limited thereto, it may have a shape bent upward in a convex way. A cross-section of the supporter  200  in the yz plane may substantially have a U shape but is not limited thereto. According to the cross-sectional shape of the supporter  200 , the supporter  200  may have a tension in the x direction. 
     The supporter  200  bent when the supporter  200  is wound on the roller  300  may maintain an unfolded state and may be wound on the roller  300 . 
     In an embodiment, the supporter  200  may include at least one of glass fiber reinforced plastics (“GFRP”), carbon fiber reinforced plastics (“CFRP”), aluminum, and plastic. 
     Referring to  FIG.  1    and  FIG.  2   , the display panel  100  and the supporter  200  may be unwound or wound in parallel to the x direction. 
     As shown in  FIG.  2   , when the display panel  100  displays an image in the x direction and the display panel  100  is wound, the display panel  100  may be wound on the roller  300  while disposed further outside than the supporter  200  is. That is, the roller  300  may rotate in a counterclockwise direction when the display panel  100  is wound, and the roller  300  may rotate in a clockwise direction when the display panel  100  is unwound. The rotation direction of the roller  300  is not limited thereto. 
     As shown in  FIG.  2   , while the display panel  100  is wound, the display area of the display panel  100  may not be exposed to the outside and the display panel  100  may be turned off. On the contrary, as shown in  FIG.  1   , while the display panel  100  is unwound, the display area of the display panel  100  may extend and may maintain to be flat in the xy plane. Here, the display panel  100  may be maintained to be flat by the supporter  200 . While the display panel  100  is unwound, the display panel  100  may be turned on and may display the images. 
     The roller  300  may be substantially cylindrical, and may have a cylindrical shape extending in the y direction that is perpendicular to the x direction in which the display panel  100  and the supporter  200  are wound or unwound. However, the shape of the roller  300  is not limited thereto. The roller  300  may be driven by a driving device such as a motor. According to a rotation of the roller  300 , the display panel  100  and the supporter  200  may be wound and unwound on the circumference of the roller  300 . 
     The display panel  100  and the supporter  200  may be wound on one roller  300 . Therefore, the slim display device may be realized by reducing the thickness of the display device, compared to the rollable display device for connecting the display panel  100  and the supporter  200  to respective rollers and winding or unwinding the same. 
     When the display panel  100  is disposed to the outside, a winding radius of the display panel  100  may be greater than a winding radius of the supporter  200 . Hence, when the display panel  10  and the supporter  200  are unfolded from the roller  300  and are unwound, a length of the display panel  100  in the x direction may be greater than a length of the supporter  200  in the x direction. 
     The supporter  200  and the display panel  100  overlapping each other in the z direction may not be adhered to each other in most of the region, and the supporter  200  and the display panel  100  may be slid to with respect to each other in the x direction when the supporter  200  and the display panel  100  are wound and unwound. Therefore, damage such as peeling off or cracks caused by a length deviation in the x direction when the display panel  100  and the supporter  200  are wound and unwind may be prevented. 
     The upper case  400  and the lower case  500  overlap each other in the z direction. When the display panel  100  and the supporter  200  are wound and unwound, the upper case  400  and the lower case  500  may at least partly overlap each other, may slide in the x direction, and may be opened as shown in  FIG.  1    or mostly overlap each other as shown in  FIG.  2   . 
     As shown in  FIG.  2   , while the display panel  100  and the supporter  200  are wound, edges  410  and  510 , and  420  and  520 , which correspond to each other, of the upper case  400  and the lower case  500  may be arranged to overlap each other and be stacked. As shown in  FIG.  1   , the display panel  100  and the supporter  200  are unwound, the upper case  400  further slides in the x direction that is an unwinding direction with respect to the position of the lower case  500 , and the edge  410  of the upper case  400  may become distant from the edge  510  of the lower case  500  in the x direction, and the edge  420  of the upper case  400  may become distant from the edge  520  of the lower case in the x direction. 
     A first end of the display panel  100  may be fixed to the roller  300 , and a second end of the display panel  100  opposite to the first end of the display panel  100  in the x direction may be fixed to the edge  410  of the upper case  400 . A first end of the supporter  200  may be fixed to the roller  300 , and a second end of the supporter  200  opposite to the first end of the supporter  200  in the x direction may be fixed to the edge  510  of the lower case  500 . 
     An upper case  400 , a lower case  500 , and an elasticity member of a display device in an embodiment will now be described in detail with reference to  FIG.  3    to  FIG.  6    together with  FIG.  1    and  FIG.  2   . 
       FIG.  3    shows a perspective view of an embodiment of a display device before a display panel of a display device is connected to an upper case,  FIG.  4    shows an embodiment of an elasticity member connected to an upper case and a lower case of a display device,  FIG.  5    shows a perspective view of an embodiment of a lower portion of an upper case of a display device, and  FIG.  6    shows a perspective view of an embodiment of an upper portion of a lower case of a display device. 
     Referring to  FIG.  3   , the display device may further include at least one elasticity member  600  connected between the upper case  400  and the lower case  500 . 
     In an embodiment, the elasticity member  600  may be an extension spring, for example. 
       FIG.  3    illustrates that the display device includes two elasticity members  600  in the y direction, but a number of the elasticity members  600  is not limited thereto. The respective elasticity members  600  may extend in the x direction in which the display panel  100  is wound and unwound. 
     The elasticity member  600  may include a portion disposed between a lower side of the upper case  400  and an upper side of the lower case  500 . 
     Referring to  FIG.  3   , while the display panel  100  and the supporter  200  are not connected to the upper case  400  and the lower case  500 , the elasticity member  600  may not be stretched or shrunk, that is, may be in a natural state. A distance (Ga) between the edge  410  of the upper case  400  and the corresponding edge  510  of the lower case  500  in the x direction is less than an x-direction width of the lower case  500 . 
     Referring to  FIG.  4    and  FIG.  5   , the upper case  400  may further include at least one protrusion  402  protruding in the downward z direction from the lower side  409  of the edge  410  to which the display panel  100  is connected. 
     A first end of the elasticity member  600  may be connected to a lateral side of the protrusion  402  and may be fixed thereto. 
     A number of the protrusions  402  included by the upper case  400  may be equal to a number of the elasticity members  600 . 
     Referring to  FIG.  3   ,  FIG.  4   , and  FIG.  6   , at least one groove  502  arranged with the protrusion  402  in the x direction may be defined in the lower case  500 .  FIG.  3    illustrates an embodiment in which two grooves  502  spaced apart from each other in the y direction are defined in the display device. The respective grooves  502  extend in the x direction in which the display panel  100  is wound and unwound. 
     The respective grooves  502  reaches the edge  510  of the lower case  500  but does not extend up to the opposite edge  520  of the lower case  500  and includes an end portion  504  spaced apart from the edge  520 . 
     A second end of the elasticity member  600  may be connected to a lateral side of the end portion  504  of the groove  502  of the lower case  500  and may be fixed thereto. 
     A number of the grooves  502  included by the lower case  500  may be equal to the number of the elasticity members  600 . 
     A corresponding elasticity member  600  is disposed in the groove  502 , and the respective grooves  502  provide a space in which the corresponding elasticity member  600  may extend. 
       FIG.  3    illustrates, differing from what are shown with reference to  FIG.  1    and  FIG.  2   , that the supporter  200  has a reversed U shape that is upwardly convex. 
     A space may be defined in at least one of the upper case  400  and the lower case  500  in an embodiment.  FIG.  3   ,  FIG.  4   , and  FIG.  6    illustrate that an internal space  404  is defined in the upper case  400 . A battery, a circuit board, etc., may be disposed in the internal space  404 . By this, use of the upper case  400  or the lower case  500  may increase. 
     A space may be provided in the roller  300 . A battery, a driver, etc., may be disposed in the internal space of the roller  300 . 
     An operation for the display device in an embodiment to be wound and unwound will now be described with reference to  FIG.  7    to  FIG.  10    together with the above-described drawings. 
       FIG.  7    shows a perspective view of an embodiment of a display device when a display panel and a supporter of a display device are unwound,  FIG.  8    shows an internal lateral view of an embodiment of a display device when a display panel and a supporter of a display device are unwound,  FIG.  9    shows a perspective view of an embodiment of a display device when a display panel and a supporter of a display device are wound, and  FIG.  10    shows an internal lateral view of an embodiment of a display device when a display panel and a supporter of a display device are wound. In  FIG.  8    and  FIG.  10   , the upper case  400  and the lower case  500  are omitted for convenience, and relative positions of the display panel  100 , the support part  200 , and the elastic member  600  are shown. 
     Referring to  FIG.  7    and  FIG.  8   , the second end of the display panel  100  is connected to the edge  410  of the upper case  400 , and the second end of the supporter  200  is connected to the edge  510  of the lower case  500  and is completely unwound to the outside from the roller  300 . The elasticity member  600  is further extended in the x direction than the natural state shown in  FIG.  3   . Therefore, a tension may be applied to the unwound display panel  100  to maintain a tense state, and the display panel  100  may have flat and improved surface quality without defects such as buckling when it is unwound. 
     As the elasticity member  600  is further extended than the natural state, a distance (Gb) between the edge  410  of the upper case  400  and the edge  510  of the lower case  500  in the x direction may be less than the distance (Ga) between the edge  410  of the upper case  400  and the edge  510  of the lower case  500  in the x direction shown in  FIG.  3   . 
     The elasticity member  600  may have a first length La in the x direction as shown in  FIG.  8   , and the first length La may be greater than a length of the elasticity member  600  in the x direction in the natural state shown in  FIG.  3   . 
     Referring to  FIG.  9    and  FIG.  10   , while the second end of the display panel  100  is connected to the edge  410  of the upper case  400 , and the second end of the supporter  200  is connected to the edge  510  of the lower case  500 , the display panel  100  and the supporter  200  are completely rolled up and wound on the roller  300 . The elasticity member  600  is further extended in the x direction than the same is unwound as shown in  FIG.  7    and  FIG.  8   . Therefore, a greater tension in the x direction may be applied to the display panel  100  when it is wound than when it is unwound. 
     The elasticity member  600  in the wound state further extends than the elasticity member  600  extends in the unwinding state, and the elasticity member  600  then applies a tension to the display panel  100 , so when the wound state shown in  FIG.  9    and  FIG.  10    is changed to the unwinding state shown in  FIG.  7    and  FIG.  8   , the display device  1000  may be easily unwound by an elastic restoring force of the elasticity member  600  in the x direction. 
     The elasticity member  600  may have a second length Lb in the x direction as shown in  FIG.  10   , and the second length Lb is greater than the first length La of the elasticity member  600  in the x direction in the unwinding state shown in  FIG.  8   . 
     When the unwound state shown in  FIG.  7    and  FIG.  8    is changed to the wound state shown in  FIG.  9    and  FIG.  10    and vice versa, the upper case  400  may slide and move in the x direction with respect to the lower case  500 . The elasticity member  600  may further extend and may pull the display panel  100  with a greater tension as the distance between the edge  410  of the upper case  400  and the corresponding edge  510  of the lower case  500  in the x direction is reduced. 
     In the wound state shown in  FIG.  9    and  FIG.  10   , the edge  410  of the upper case  400  and the edge  510  of the lower case  500  may be arranged in the z direction, and the distance between the edges  410  and  510  in the x direction may be 0 or may be close to 0. The opposite edge  420  of the upper case  400  and the opposite edge  520  of the lower case  500  may be arranged in the z direction, and the upper case  400  and the lower case  500  may substantially overlap each other. 
     A display device in an embodiment will now be described with reference to  FIG.  11    to  FIG.  13    together with the above-referenced drawings. 
       FIG.  11    shows a perspective view of an embodiment of a display device. 
     Referring to  FIG.  11   , the display device mostly corresponds to the above-described display device in an embodiment, and may further include at least one guide rail  550  disposed on the upper side of the lower case  500 .  FIG.  11    exemplifies that one display device includes four guide rails  550  spaced apart from each other in they direction. 
     The respective guide rails  550  extend in the direction in which the display panel  100  is wound and unwound, that is, the x direction in which the upper case  400  slides with respect to the lower case  500 . 
       FIG.  11    illustrates that one pair of guide rails  550  are disposed on respective adjacent sides of the respective grooves  502  of the lower case  500 , but the position of the guide rail  550  is not limited thereto. 
     The guide rail  550  may guide the sliding direction so that the upper case  400  may easily slide in the x direction with respect to the lower case  500 . Although not shown, a combined structure corresponding to the guide rail of the lower case  500  may be disposed on the lower side of the upper case  400 . 
       FIG.  12    shows a perspective view of an embodiment of a display device. 
     Referring to  FIG.  12   , the display device in an embodiment mostly corresponds to the above-described display device in an embodiment, and includes at least three supporters  200  spaced apart from each other in the y direction. In a like way, although not shown, the display device in an embodiment may include at least three elasticity members  600 . 
       FIG.  13    shows a perspective view of an embodiment of a display device. 
     Referring to  FIG.  13   , the display device in an embodiment mostly corresponds to the above-described display device in an embodiment, and it may further include at least one fixing member  700  for fixing the lower case  500  and the upper case  400  while they are closed when the display panel  100  and the supporter  200  are completely wound on the roller  300 .  FIG.  13    shows that a display device in an embodiment includes two fixing members  700 . 
     The fixing member  700  may be disposed on an outer edge  520  of the lower case  500 , and may fix the position of the upper case  400  with respect to the lower case  500  when the display panel  100  and the supporter  200  are wound. 
     While this invention has been described in connection with what is presently considered to be practical embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.