Patent Publication Number: US-2023162626-A1

Title: Display device

Description:
TECHNICAL FIELD 
     The present disclosure relates to a display device. 
     BACKGROUND ART 
     As the information society develops, the demand for display devices is also increasing in various forms. In response to this, various display devices such as Liquid Crystal Display Device (LCD), Plasma Display Panel (PDP), Electroluminescent Display (ELD), and Vacuum Fluorescent Display (VFD) have been researched and used in recent years. 
     Among them, a display device using an organic light emitting diode (OLED) has superior luminance characteristics and viewing angle characteristics compared to a liquid crystal display device, and can be implemented in an ultra-thin shape as it does not require a backlight unit. 
     In addition, a flexible display panel can be bent or wound on a roller. By using the flexible display panel, it is possible to implement a display device that is roll out from a roller or wound on a roller. A lot of research has been done on a structure for winding or unwinding a flexible display panel on/from a roller. 
     DISCLOSURE 
     Technical Problem 
     An object of the present disclosure is to solve the above and other problems. 
     Another object of the present disclosure may be to secure structural rigidity to prevent sagging of a display device. 
     Another object of the present disclosure may be to secure structural rigidity to prevent torsion of a display device. 
     Another object of the present disclosure may be to provide a driving mechanism for a display device. 
     Another object of the present disclosure may be to provide a rotation stabilization structure of a display device. 
     Technical Solution 
     According to an aspect of the present disclosure for achieving the above object, there is provided a display device including: a flexible display panel; a panel roller which extends long, and around which the display panel is wound, or from which the display panel is unwound; a first frame located adjacent to one end of the panel roller; a second frame which is located adjacent to the other end of the panel roller, and faces the first frame with respect to the panel roller; a bearing which is coupled to one end of the panel roller, and fixed to the first frame; a disk wheel which is adjacent to the other end of the panel roller, crosses a rotation shaft of the panel roller, and is coupled to the panel roller; a first stable roller in contact with the disc wheel; and a second stable roller in contact with the disk wheel. 
     Advantageous Effects 
     The effect of the display device according to the present disclosure will be described as follows. 
     According to at least one of embodiments of the present disclosure, structural rigidity for preventing the display device from sagging may be secured. 
     According to at least one of embodiments of the present disclosure, structural rigidity for preventing torsion of the display device may be secured. 
     According to at least one of embodiments of the present disclosure, a driving mechanism of the display device may be provided. 
     According to at least one of the embodiments of the present disclosure, a rotation stabilization structure of a display device may be provided. 
     Further scope of applicability of the present disclosure will become apparent from the following detailed description. However, it should be understood that the detailed description and specific embodiments such as preferred embodiments of the present disclosure are given by way of example only, since various changes and modifications within the spirit and scope of the present disclosure may be clearly understood by those skilled in the art. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIGS.  1  to  42    are diagrams illustrating examples of a display device according to embodiments of the present disclosure. 
     
    
    
     MODE FOR INVENTION 
     Description will now be given in detail according to exemplary embodiments disclosed herein, with reference to the accompanying drawings. For the sake of brief description with reference to the drawings, the same or equivalent components may be denoted by the same reference numbers, and description thereof will not be repeated. 
     In general, suffixes such as “module” and “unit” may be used to refer to elements or components. Use of such suffixes herein is merely intended to facilitate description of the specification, and the suffixes do not have any special meaning or function. 
     In the present disclosure, that which is well known to one of ordinary skill in the relevant art has generally been omitted for the sake of brevity. The accompanying drawings are used to assist in easy understanding of various technical features and it should be understood that the embodiments presented herein are not limited by the accompanying drawings. As such, the present disclosure should be construed to extend to any alterations, equivalents and substitutes in addition to those which are particularly set out in the accompanying drawings. 
     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. 
     It will be understood that when an element is referred to as being “connected with” another element, there may be intervening elements present. In contrast, it will be understood that when an element is referred to as being “directly connected with” another element, there are no intervening elements present. 
     A singular representation may include a plural representation unless context clearly indicates otherwise. 
     In the following description, even if the embodiment is described with reference to specific drawings, if necessary, reference numerals not appearing in the specific drawings may be referred to, and reference numerals not appearing in the specific drawings are used in a case where the above reference numerals appear in the other figures. 
     Referring to  FIG.  1   , a display device  10  may include a display unit  20  and a housing  30 . The housing  30  may have an internal space. At least a portion of the display unit  20  may be located inside the housing  30 . At least a portion of the display unit  20  may be located outside the housing  30 . The display unit  20  may display a screen. 
     A direction parallel to the length direction of the housing  30  may be referred to as a first direction DR1, a left direction, or a right direction. A direction in which the display unit  20  displays a screen may be referred to as a front side direction, or a forward direction. A direction opposite to the direction in which the display unit  20  displays a screen may be referred to as a -z axis, a rear side direction, or a rearward direction. A direction parallel to a height direction of the display device  10  may be referred to as a second direction DR2, an upper direction, or a lower direction. 
     A third direction DR3 may be a direction perpendicular to the first direction DR1 and/or the second direction DR2. The first direction DR1 and the second direction DR2 may be collectively referred to as a horizontal direction. In addition, the third direction DR3 may be referred to as a vertical direction. The left-right direction LR may be parallel to the first direction DR1, and the up-down direction UD may be parallel to the second direction DR2. 
     Referring to  FIG.  2   , the entire display unit  20  may be located inside the housing  30 . At least a portion of the display unit  20  may be located outside the housing  30 . The extent to which the display unit  20  is exposed to the outside of the housing  30  may be adjusted as necessary. 
     Referring to  FIG.  3   , the display unit  20  may include a display panel  21  and a plate  23 . The display panel  21  may be flexible. For example, the display panel  21  may be an organic light emitting display (OLED). 
     The display panel  21  may have a front surface for displaying an image. The display panel  21  may have a rear surface opposite to the front surface. The front surface of the display panel  21  may be covered with a light-transmitting material. For example, the light-transmitting material may be a synthetic resin or a film. 
     The plate  23  may be coupled, fastened, or attached to the rear surface of the display panel  21 . The plate  23  may include a metal material. The plate  23  may be referred to as a module cover  23 , a cover  23 , a display panel cover  23 , a panel cover  23 , or an apron  23 . 
     Referring to  FIG.  4   , the plate  23  may include a plurality of segments  23   c . A magnet  24  may be located inside a recess  26  of the segment  23   c . The recess  26  may be located on a surface of the segment  23   c  facing the display panel  21 . The recess  26  may be located in the front surface of each segment  23   c . Since the magnet  24  is received inside the recess  26 , the magnet  24  may not protrude out of the segment  23   c . The display panel  21  may be flat without being crumpled even when it comes into contact with the segment  23   c . 
     Referring to  FIG.  5   , a bead  27  may be formed on the upper surface of the segment  23   b . The bead  27  may have a shape recessed to the inside of the segment  23   b . For example, the bead  27  may be formed by pressing the segment  23   b . A plurality of beads  27  may be formed in the segment  23   b . The plurality of beads  27  may be spaced apart from each other. The bead  27  may improve the rigidity of the segment  23   b . The bead  27  may prevent the shape of the segment  23   b  from being deformed from an external impact. The segment  23   b  may be fixed to the rearward direction of the display panel  21  by an adhesive member  22 . For example, the adhesive member  22  may be a double-sided tape. 
     Referring to  FIG.  6   , a source PCB  21   b  may be located in the lower side of the module cover  23 . When the source PCB  21   b  is rolled down or rolled up, its position may change with the movement of the module cover  23 . A FFC cable  21   a  may be located in the center of the module cover  23  based on a first direction. The FFC cable  21   a  may be located in opposite ends of the module cover  23  based on the first direction. 
     Referring to  FIG.  7   , the segment  23   d  may include a recess portion  28  recessed to the inside of the segment  23   d . The recess portion  28  may form a space between the display panel  21  and the module cover  23 . The FFC cable  21   a  may be accommodated in the space formed by the recess portion  28 . In addition, the recess portion  28  may improve the rigidity of the segment  23   d . The bead  27  may be located on the segment  23   d  excluding a portion where the recess portion  28  is located. The position of the recess portion  28  may not overlap with the position of the bead  27  to prevent the segment  23   d  from weakening. 
     Referring to  FIG.  8   , in the segment  23   e , a penetrating portion  29  may be located in a central portion of the segment  23   e  based on the first direction. The penetrating portion  29  may penetrate the central portion of the segment  23   e  in the second direction. That is, the penetrating portion  29  may be a hole located in the segment  23   e . The penetrating portion  29  may be a portion in which the FFC cable  21   a  is located. Since the penetrating portion  29  is formed in the segment  23   e , the thickness of the segment  23   e  can be reduced in comparison with a case where the FFC cable  21   a  is located in the recess portion  28  (refer to  FIG.  7   ). The bead  27  may be located in the segment  23   e  excluding a portion where the penetrating portion  29  is located. The position of the penetrating portion  29  may not overlap the position of the bead  27  in order to prevent the segment  23   e  from weakening. 
     Referring to  FIG.  9   , a top case  60  may cover the display panel  21  and the module cover  23  as well as the source PCB  21   b  and an upper bar  50 . One surface of the upper bar  50  may be coupled to the rear surface of the module cover  23 , and the other surface may be coupled to the source PCB  21   b . The upper bar  50  may be fixed to the module cover  23  to support the source PCB  21   b . 
     The lower end of the FFC cable  21   a  may be connected to a timing controller board  41  (refer to  FIG.  10   ) inside a panel roller  40  (refer to  FIG.  10   ). The FFC cable  21   a  may be wound around or unwound from the panel roller  40  together with the display unit  20 . 
     A portion of the FFC cable  21   a  may be located between the display panel  21  and the module cover  23 . A portion of the FFC cable  21   a  located between the display panel  21  and the module cover  23  may be referred to as a first portion  21   a   1 . The first portion  21   a   1  may be located in the recess portion  28  formed by the plurality of segments  23   d . Alternatively, the first portion  21   a   1  may be received in the recess portion  28  formed by the plurality of segments  23   d . 
     A portion of the FFC cable  21   a  may penetrate the segment  23   f . A portion of the FFC cable  21   a  that penetrates the segment  23   f  may be referred to as a second portion  21   a   2 . The segment  23   f  may include a first hole  23   fh   1  formed on the front surface and a second hole  23   fh   2  formed on the rear surface. The first hole  23   fh   1  and the second hole  23   fh   2  may be interconnected to form one hole  23   fh . The hole  23   fh  may penetrate the segment  23   f  in a third direction. The second portion  21   a   2  may pass through the hole  23   fh . The hole  23   fh  may be referred to as a connection hole  23   fh . 
     An upper end of the FFC cable  21   a  may be electrically connected to the source PCB  21   b . A portion of the FFC cable  21   a  may be located on the rear surface of the module cover  23 . A portion of the FFC cable  21   a  located on the rear surface of the module cover  23  may be referred to as a third portion  21   a   3 . The third portion  21   a   3  may be electrically connected to the source PCB  21   b . 
     The third portion  21   a   3  may be covered by the top case  60 . Accordingly, the third portion  21   a   3  may not be exposed to the outside. 
     Referring to  FIG.  10   , the FFC cable  21   a  may be connected to the timing controller board  41  mounted on the panel roller  40 . A through hole  42  may be formed in the panel roller  40 , and the FFC cable  21   a  may be connected to the timing controller board  41  through the through hole  42 . 
     The through hole  42  may be located in one side of the panel roller  40  and may penetrate the outer circumferential portion of the panel roller  40 . The FFC cable  21   a  may be connected to one side of the timing controller board  41  through the through hole  42 . 
     Even if the FFC cable  21   a  is located on the outer perimeter of the panel roller  40 , the connection to the timing controller board  41  may be maintained due to the through hole  42 . Accordingly, the FFC cable  21   a  may not be twisted by rotating together with the panel roller  40 . 
     A portion of the FFC cable  21   a  may be wound around the panel roller  40 . A portion of the FFC cable  21   a  wound around the panel roller  40  may be referred to as a fourth portion  23   a   4 . The fourth portion  23   a   4  may be in contact with the outer circumferential surface of the panel roller  40 . 
     A portion of the FFC cable  21   a  may pass through the through hole  42 . A portion of the FFC cable  21   a  passing through the through hole  42  may be referred to as a fifth portion  23   a   5 . 
     A lower end of the FFC cable  21   a  may be electrically connected to the timing controller board  41 . A portion of the FFC cable  21   a  may be located inside the panel roller  40 . A portion of the FFC cable  21   a  located inside the panel roller  40  may be referred to as a sixth portion  23   a   6 . The sixth portion  23   a   6  may be electrically connected to the timing controller board  41 . 
     Referring to  FIG.  11   , the display panel  21  may be connected to the roller  40 . The display panel  21  may be wound around or unwound from the roller  40 . The display panel  21  may be electrically connected to the plurality of source PCBs  21   b . The plurality of source PCBs  21   b  may be spaced apart from each other. 
     A source chip on film (COF)  21   m  may connect the display panel  21  and the source PCB  21   b . The source COF  21   m  may be located in the lower side of the display panel  21 . The roller  40  may include a first part  43  and a second part  44 . The first part  43  and the second part  44  may be fastened by a screw. The timing controller board  41  may be mounted inside the roller  40 . 
     The source PCB  21   b  may be electrically connected to the timing controller board  41 . The timing controller board  41  may transmit digital video data and a timing control signal to the source PCB  21   b . 
     A cable  21   p  may electrically connect the source PCB  21   b  and the timing controller board  41 . For example, the cable  21   p  may be a flexible flat cable (FFC). The cable  21   p  may pass through the hole  21   n . The hole  21   n  may be formed in a seating portion  45  or the first part  43 . The cable  21   p  may be located between the display panel  21  and the second part  44 . 
     The seating portion  45  may be formed in the outer perimeter of the first part  43 . The seating portion  45  may be formed by stepping a portion of the outer perimeter of the first part  43 . The seating portion  45  may form a space B. When the display unit  20  is wound around the panel roller  40 , the source PCB  21   b  may be received in the seating portion  45 . Since the source PCB  21   b  is received in the seating portion  45 , it may not be bent or crooked, and durability may be improved. 
     Referring to  FIGS.  12  and  13   , a pipe  110  may extend long in the left-right direction. There may be a plurality of pipes  110 . The plurality of pipes  110  may include a first pipe  111 , a second pipe  112 , and a third pipe  113 . The plurality of pipes  110  may be parallel to each other. For example, the pipe  110  may be a hollow cylinder. As another example, the pipe  110  may be a cylindrical bar. 
     The pipe  110  may be coupled to a frame  120 ,  130  while being inserted into the frame  120 ,  130 . The frame  120 ,  130  may include a first frame  120  and a second frame  130 . The first frame  120  may be located adjacent to one end of the pipes  110 , and the second frame  130  may be located adjacent to the other end of the pipes  110 . The first frame  120  may face the second frame  130 . 
     For example, the frame  120 ,  130  may be a rectangular plate. The first pipe  111  may be inserted into the frames  120  and  130  while being adjacent to a first corner C1 of the first frame  120  and the second frame  130 . The second pipe  112  may be inserted into the frames  120  and  130  while being adjacent to a second corner C2 of the first frame  120  and the second frame  130 . The third pipe  113  may be inserted into the frames  120  and  130  while being adjacent to a third corner C3 of the first frame  120  and the second frame  130 . 
     A central opening  123  may be formed in a plate  121  of the first frame  120 . The central opening  123  may be a circle formed by penetrating the plate  121  of the first frame  120 . The first pipe  111 , the second pipe  112 , and the third pipe  113  may be disposed while forming a triangle with respect to the central opening  123 . 
     Referring to  FIG.  13   , couplers  122 ,  124 ,  126 ,  132 ,  134 , and  136  may be formed in the plates  121  and  131 . The first frame  120  may include a  11  coupler  122 , a  12  coupler  124 , and a  13  coupler  126  formed in the plate  121 . The second frame  130  may include a  21  coupler  132 , a  22  coupler  134 , and a  23  coupler  136  formed in the plate  131 . The first pipe  111  may be inserted into the  11  coupler  122  and the  21  coupler  132 . The second pipe  112  may be inserted into the  12  coupler  124  and the  22  coupler  134 . The third pipe  113  may be inserted into the  13  coupler  126  and the  23  coupler  136 . 
     Referring to  FIGS.  14  and  15   , the coupler  136  may have a cylindrical shape formed by penetrating the plate  131 . The coupler  136  may be fixed to the plate  131 , and may be formed with the plate  131  as one body. The coupler  136  may have an outer side  1361  and an inner side  1362  with respect to the plate  131 . A distance D2 of the outer side  1361  may be smaller than a distance D1 of the inner side  1362 . A fastening hole  136   h  may be formed in the inner side  1362 . The pipe  113  may be fixed to the frame  130  while the screw is fastened to the fastening hole  136   h . 
     A first neck  1131  may form an engraved ring on the outer surface of the pipe  113  while being recessed to the inner side of the pipe  113  while being adjacent to the outer side  1361  of the coupler  136 . A second neck  1132  may be adjacent to a distal end of the pipe  113 , but may be spaced apart from the distal end of the pipe  113  and recessed to the inner side of the pipe  113  to form an engraved ring on the outer surface of the pipe  113 . The pipe  113  may be firmly fixed to the frame  130  while a coupling ring CR 3  is fastened to the first neck  1131 . For example, the coupling ring CR 3  may be an E-ring. 
     Referring to  FIGS.  16  to  19   , the display unit  20  wound around the panel roller  40  may be inserted between the first pipe  111 , the second pipe  112 , the third pipe  113 , the first frame  120 , and/or the second frame  130 . The panel roller  40  may be disposed in parallel with the first pipe  111 , the second pipe  112 , or the third pipe  113 . 
     The guide roller  140  may be coupled to the frames  120  and  130  while the panel roller  40  and the display unit  20  are located between the pipes  110  and the frames  120  and  130 . The guide roller  140  may include a shaft  142 , a roller  141 , and a fixing plate  143 . 
     A support portion  137  may be formed on the plate  131 . The support portion  137  may support the shaft  142  of the guide roller  140 . The shaft  142  may be fixed to the support portion  137 , and the roller  140  can rotate on the shaft  142 . The support portion  137  may be formed in the inner side of the plate  131 . 
     The support portion  137  may include a body  1371 , a shaft groove  1372 , and a plate-in groove  1373 . The body  1371  may have a cylindrical shape protruding from the inner surface of the plate  131 . The shaft groove  1372  may be recessed to the inner side of the body  1371  from the outer circumferential surface of the body  1371 . The plate-in groove  1373  may be recessed to the inside of the body  1371  from the outer circumferential surface of the body  1371  between the shaft groove  1372  and the plate  131 . A groove width W2 of the plate-in groove  1373  may be larger than a groove width W1 of the shaft groove  1372 . 
     In other words, the shaft groove  1372  may have a groove width W1 corresponding to the diameter of the shaft  142 , and the plate-in groove  1373  may have a groove width W2 corresponding to the diameter of the fixing plate  143 . The shaft  142  of the guide roller  140  may be inserted into the shaft groove  1372  of the support portion  137 , and the fixing plate  143  of the guide roller may be inserted into the plate-in groove  1373  of the support portion  137  while the guide roller  140  is supported by the support portion  137 . 
     The fixing plate  143  may be fixed to the frame  130  by a fastening member (e.g. a screw) fastened to the fastening holes  137   h  penetrating the frame  130 . Referring to  FIG.  21   , the shaft  142  may be inserted into and fixed to the frame  120 . 
     Referring to  FIG.  20   , a distance L12 between the first pipe  111  and the second pipe  112  may be larger than a distance L23 between the second pipe  112  and the third pipe  113 . A distance L12 between the first pipe  111  and the second pipe  112  may be larger than a distance L34 between the third pipe  113  and the guide roller  140 . A distance L12 between the first pipe  111  and the second pipe  112  may be larger than a distance L41 between the first pipe  111  and the guide roller  140 . 
     A distance L23 between the second pipe  112  and the third pipe  113  may be larger than a distance L41 between the first pipe  111  and the guide roller  140 . A distance L23 between the second pipe  112  and the third pipe  113  may be larger than a distance L34 between the third pipe  113  and the guide roller  140 . A distance L34 between the third pipe  113  and the guide roller  140  may be larger than a distance L41 between the guide roller  140  and the first pipe  111 . 
     Accordingly, the torsional rigidity of the display device as well as the sagging rigidity can be improved. 
     Referring to  FIGS.  21  to  24   , one end of the panel roller  40  may be located adjacent to the central opening  123  of the first frame  120 . The rotation shaft of the panel roller  40  may be aligned with the center of the central opening  123  of the first frame  120 . A bearing  450  may be mounted in the central opening  123  of the first frame  120 . For example, the bearing  450  may be a ring bearing  450 . 
     One end of the panel roller  40  may be inserted or press-fitted into the bearing  450 . The other end of the panel roller  40  may be rotatably coupled to the second frame  130 . The panel roller  40  may include a rotation shaft  46 , and the rotation shaft  46  may penetrate the first frame  130  and be installed in the second frame  130 . The rotating shaft  46  may be connected to a lever  47 , and the panel roller  40  may be manually rotated through the lever  47 . 
     The coupler  136  may have a cylindrical shape formed by penetrating the plate  131 . The coupler  136  may be fixed to the plate  131 , and may be formed with the plate  131  as one body. The coupler  136  may have an outer side  1361  and an inner side  1362  with respect to the plate  131 . The distance D2 of the outer side  1361  may be smaller than the distance D1 of the inner side  1362 . For example, the distance D1 of the inner side  1362  may be 5 times or more of the distance D2 of the outer side  1361 . 
     The pipes  112  and  113  may be press-fitted to the outer sides  1341  and  1361  by penetrating inner sides  1342  and  1362  of the couplers  134  and  136 . The pipes  112  and  113  may not penetrate the couplers  134  and  136 . The outer sides  3141  and  1361  of the couplers  134  and  136  may cover the distal end of the pipes  112  and  113 . A first fastening hole  136   h   1  and a second fastening hole  136   h   2  may be formed in the inner side  1362 . As the screws are fastened to the first fastening hole  136   h   1  and the second fastening hole  136   h   2 , the pipe  113  may be firmly fixed to the frame  130 . 
     Referring to  FIGS.  25  to  27   , a disk wheel  210  may include an inner circle  211 , an inclination portion  213 , an outer circle  215 , and a rim  217 . The inner circle  211  may have a disk shape having an opening at a center. Holes h1 may be formed adjacent to the opening. The outer circle  215  may be referred to as a first outer circle  215 . 
     The inclination portion  213  may extend while expanding from an edge of the outer perimeter of the inner circle  211  in a radial direction. The inclination portion  213  may have an inclination with respect to the inner circle  211  in a ring shape. The outer circle  215  may extend from an edge of the outer perimeter of the inclination portion  213 . The rim  217  may be formed on one surface of the outer circle  215  along the outer perimeter of the outer circle  215 . Holes  h   2  may be formed in the outer circle  215  while being adjacent to the boundary between the inclination portion  213  and the outer circle  215 . 
     Referring to  FIGS.  28  and  29   , the disk wheel  210  may be coupled to the panel roller  40 . The disk wheel  210  may be coupled to one end of the panel roller  40 . The disk wheel  210  may be coupled to the side surface of the panel roller  40  by a fastening member penetrating the holes h1. The distance D1 between one end of the module cover  23  wound around the panel roller  40  and the inner circle  211  may be smaller than the distance D2 between one end of the module cover  23  wound around the panel roller  40  and the outer circle  215 . 
     Referring to  FIGS.  30  and  31   , the disk wheel  210  may further include a guide wheel  210 G. The guide wheel  210 G may face the outer circle  215  with respect to the inner circle  211 . The guide wheel  210 G may include an inclination portion  212 , a middle part  214 , and a guide portion  216 . The middle part  214  may be referred to as a second outer circle  214 . 
     The inclination portion  212  may face the inclination portion  213  with respect to the inner circle  211 . The inclination portion  212  may extend while expanding from an edge of the outer perimeter of the inner circle  211  in a radial direction. The inclination portion  212  may have an inclination with respect to the inner circle  211 . The thickness d2 of the inclination portion  211  may be larger than the thickness d1 of the inclination portion  213 . 
     The middle part  214  may have a disk shape extending from the edge of the outer perimeter of the inclination portion  212 . The middle part  214  may be located in parallel with the outer circle  215 . The thickness T1 of the outer circle  215  may be larger than the thickness T2 of the middle part  214 . For example, the thickness T1 of the outer circle  215  may be two times or more of the thickness T2 of the middle part  214 . The distance L1 between the outer circumferential surface of the inner circle  211  and the outer circumferential surface of the outer circle  215  may be smaller than the distance L2 between the outer circumferential surface of the middle part  214  and the outer circumferential surface of the inner circle  211 . Accordingly, the middle part  214  can protect the module cover  23  (refer to  FIG.  32   ) wound around the panel roller  40 . 
     The guide portion  216  may include a first guide portion  216   a  and a second guide portion  216   b . The first guide portion  216   a  may extend from the outer circumferential surface of the middle part  214  while converging inward in the radial direction. When the inclination of the inclination portion  212  is a positive inclination, the inclination of the first guide portion  216   a  may be a negative inclination. The second guide portion  216   b  may extend from the outer circumferential surface of the first guide portion  216   a  while converging inward in the radial direction. When the inclination of the inclination portion  212  is a positive inclination, the inclination of the second guide portion  216   b  may be a negative inclination. With respect to the radial direction, the inclination of the second guide portion  216   b  may be smaller than the inclination of the first guide portion  216   a . Accordingly, when the module cover  23  is wound around the panel roller  40 , a guide wheel  210 G may guide the module cover  23  step by step. 
     Referring to  FIG.  32   , while the module cover  23  is wound around the panel roller  40 , the module cover  23  may be stacked on the outer circumferential surface of the panel roller  40 . As the module cover  23  is stacked on the panel roller  40 , the side surfaces of the module cover  23  may not be evenly aligned. 
     If the module cover  23  is wound around the panel roller  40  without being evenly aligned, the display panel  21  (refer to  FIG.  4   ) may be wound around the panel roller  40  while being twisted or crumpled. In this case, the display panel  21  may be damaged. 
     When the module cover  23  is wound around the panel roller  40 , the side surface of the module cover  23  may be guided to a proper position by the guide portion  216  of the guide wheel  210 G. When the module cover  23  is stacked while being wound around the panel roller  40  several times, the side surface of the module cover  23  may be aligned by the guide portion  216  of the guide wheel  210 G. 
     The side surface of the module cover  23  is primarily guided by the first guide portion  216   a , and is secondarily guided by the second guide portion  216   b  so that the module cover  23  is wound around the panel roller  40 . Accordingly, the display panel  21  may be prevented from being wound around the panel roller  40  while being twisted or crumpled. 
     Referring to  FIGS.  33  and  34   , a brake  219  may be located while being adjacent to the disc wheel  210 . The brake  219  may reduce the rotation speed of the disk wheel  210  or stop the rotation of the disk wheel  210 . 
     The brake  219  may hold the outer circle  215  and/or the rim  217  of the disc wheel  210 . Accordingly, the rotation of the panel roller  40  can be controlled by reducing the rotation speed of the panel roller  40 . 
     Referring to  FIG.  35   , a driving gear  220  may be coupled to the disk wheel  210 . For example, the driving gear  220  may be a ring-shaped inner ring gear. The outer diameter of the driving gear  220  may be substantially equal to or slightly larger than the inner diameter of the rim  217 . The driving gear  220  may be inserted or press-fitted to the rim  217 . The driving gear  220  may be referred to as a third gear  220 . 
     Holes  h   3  may be sequentially formed on the side surface of the driving gear  220  along the circumferential direction of the driving gear  220 . The holes  h   3  of the driving gear  220  may correspond to the holes  h   2  (refer to  FIG.  28   ) of the disk wheel  210 . The fastening member may penetrate the holes  h   3 , so that the driving gear  220  may be fixed to the disk wheel  210 . The rotation of the driving gear  220  may be the same as the rotation of the disk wheel  210 . 
     Referring to  FIGS.  36  and  37   , an intermediate gear  230  may mesh with the driving gear  220 . The intermediate gear  230  may include an outer gear  231  and an inner gear  232 . The diameter of the outer gear  231  may be larger than the diameter of the inner gear  232 . The outer gear  231  may have the same rotation shaft as the inner gear  232 . The inner gear  232  may mesh with gear teeth in the inner side of the driving gear  220 . 
     A motor gear  240  may be fixed to the rotation shaft of the motor  270 . The motor gear  240  may mesh with the outer gear  231  of the intermediate gear  230 . The intermediate gear  230  may be referred to as a second gear  230 , and the motor gear  240  may be referred to as a first gear  240 . 
     As the rotation shaft of the motor  270  rotates, the motor gear  240  may rotate. The outer gear  231  of the intermediate gear  230  may be rotated by meshing with the motor gear  240 . The inner gear  232  of the intermediate gear  230  that rotates together with the outer gear  231  of the intermediate gear  230  may rotate the driving gear  220 . Accordingly, the motor  270  may provide a rotational force to the panel roller  40 . 
     Referring to  FIGS.  38  and  39   , a rotation indicator  250  may be coupled to the motor gear  240 . The motor gear  240  may include a gear tooth  241  and a gear shaft  242 . The rotation indicator  250  may be fitted to the gear shaft  242 . 
     The rotation indicator  250  may have a disk shape. The rotation indicator  250  may have a plurality of protrusions on the outer circumferential surface. The plurality of protrusions may be sequentially disposed along the circumferential direction on the outer circumferential surface of the rotation indicator  250 . 
     A sensor  260  may be located adjacent to the rotation indicator  250 . For example, the sensor  260  may be a photosensor. The sensor  260  may detect the rotation of the rotation indicator  250 . The sensor  260  may be fixed to the inner surface of the frame  130 . A sensor fixing rib  130 R may protrude from the inner surface of the frame  130 . The sensor  260  may be fixed to the sensor fixing rib  130 R. The sensor  260  and/or the rotation indicator  250  may be located in the inner side of the driving gear  220 . 
     Referring to  FIG.  40   , one end of the panel roller  40  may be located adjacent to the central opening  123  of the first frame  120 . The rotation shaft of the panel roller  40  may be aligned with the center of the central opening  123  of the first frame  120 . 
     The bearing  450  may be coupled to the central opening  123  of the first frame  120 . For example, the bearing  450  may be a ring bearing  450 . The bearing  450  may be inserted or press-fitted into the central opening  123  of the first frame  120 . One end of the panel roller  40  may be inserted or press-fitted into the bearing  450 . 
     A rim  48  may be formed in one end of the panel roller  40 . For example, the rim  48  may have a ring-shape as a whole. The diameter of the rim  48  may be smaller than the diameter of the panel roller  40 . Ribs  49  may be sequentially formed along the circumferential direction on the outer circumferential surface of the rim  48 . The ribs  49  allow the rim  48  to be press-fitted into the bearing  450 . 
     Referring to  FIG.  41   , the driving gear  220  may be coupled to the disk wheel  210 . For example, the driving gear  220  may be a ring-shaped inner ring gear. The driving gear  220  may be referred to as a third gear  220 . The driving gear  220  may rotate together with the disk wheel  210 . 
     The intermediate gear  230  may mesh with the driving gear  220 . The intermediate gear  230  may include an outer gear  231  (refer to  FIG.  36   ) and an inner gear  232  (refer to  FIG.  36   ). The diameter of the outer gear  231  may be larger than the diameter of the inner gear  232 . The outer gear  231  may have the same rotation shaft as the inner gear  232 . The inner gear  232  may mesh with gear teeth on the inner side of the driving gear  220 . 
     The motor gear  240  (refer to  FIG.  37   ) may be fixed to the rotation shaft of the motor  270 . The motor gear  240  may mesh with the intermediate gear  230 . The intermediate gear  230  may be referred to as a second gear  230 , and the motor gear  240  may be referred to as a first gear  240 . The motor  270  may provide rotational force to the panel roller  40 . 
     A stable roller  280  may be installed in the pipe  110 . The stable roller  280  may rotate in the pipe  110 . There may be a plurality of stable rollers  280 . The pipes  110  may be inserted into the stable rollers  280 . A first stable roller  281  may rotate in the first pipe  111 , and may come into contact with the driving gear  220  and/or the disk wheel  210 . A second stable roller  282  may rotate in the second pipe  112 , and may come into contact with the driving gear  220  and/or the disk wheel  210 . A third stable roller  283  may rotate in the third pipe  113 , and may come into contact with the driving gear  220  and/or the disk wheel  210 . 
     The stable roller  280  may include a rotating body  280   a  and a buffer member  280   b . The pipe  110  may be inserted into the rotating body  280   a . At this time, the rotating body  280   a  may be provided with a bearing (not shown) to continuously rotate in the pipe  110 . The diameter of the first rotating body  281   a  may be larger than the diameter of the second rotating body  282   a  and/or the third rotating body  283   a . 
     The buffer member  280   b  may cover the outer circumferential surface of the rotating body  280   a . For example, the buffer member  280   b  may be a ring-shaped urethane. The diameter of a first buffer member  281   b  may be larger than the diameter of a second buffer member  282   b  and/or a third buffer member  283   b . The width T1 of the first buffer member  281   b  may be larger than the width T2 of the second buffer member  282   b  and/or the width T3 of the third buffer member  283   b . 
     The buffer members  280   b  may be in close contact with the outer circumferential surface of the driving gear  220  and/or the outer circumferential surface of the disk wheel  210 . Accordingly, vibration that may occur while the panel roller  40  rotates can be prevented. 
     Referring to  FIG.  42   , a first distance R1 from the rotation center of the panel roller  40  to the rotation center of the first stable roller  281  may be larger than a second distance R2 from the rotation center of the panel roller  40  to the rotation center of the second stable roller  282  and/or a third distance R3 to the rotation center of the third stable roller  283 . The second distance R2 may be substantially equal to the third distance R3. 
     Accordingly, the module cover  23  and the first pipe  111  can be prevented from interfering due to the sagging of the module cover  23  as the module cover  23  is unwound from the panel roller  40  and passes between the guide roller  140  and the first stable roller  281 . In addition, the convenience of assembly can be improved in the process of inserting the panel roller  40  into between the pipes  111 ,  112 ,  113  and/or the stable rollers  281 ,  282 ,  283 . 
     According to an aspect of the present disclosure, provided is a display device including: a flexible display panel; a panel roller which extends long, and around which the display panel is wound, or from which the display panel is unwound; a first frame located adjacent to one end of the panel roller; a second frame which is located adjacent to the other end of the panel roller, and faces the first frame with respect to the panel roller; a bearing which is coupled to one end of the panel roller, and fixed to the first frame; a disk wheel which is adjacent to the other end of the panel roller, crosses a rotation shaft of the panel roller, and is coupled to the panel roller; a first stable roller in contact with the disc wheel; and a second stable roller in contact with the disk wheel. 
     In addition, according to another aspect of the present disclosure, the display device further includes: a first pipe which extends long in a length direction of the panel roller, is located adjacent to the panel roller, and is coupled to the first frame and the second frame; and a second pipe which extends long in the length direction of the panel roller, is located adjacent to the panel roller, faces the first pipe with respect to the panel roller, and is coupled to the first frame and the second frame, wherein the first stable roller is rotatably coupled to the first pipe, and the second stable roller is rotatably coupled to the second pipe. 
     In addition, according to another aspect of the present disclosure, the display device further includes: a third pipe which extends long in the length direction of the panel roller, is located adjacent to the panel roller, faces the first pipe and the second pipe with respect to the panel roller, and is coupled to the first frame and the second frame; and a third stable roller which is coupled to the third pipe, and in contact with the disk wheel. 
     In addition, according to another aspect of the present disclosure, a diameter of the first stable roller is larger than a diameter of the second stable roller or the third stable roller. 
     In addition, according to another aspect of the present disclosure, the display device further includes: a motor mounted on the second frame; a driving gear coupled to the disc wheel; and an intermediate gear which meshes with the driving gear, and receives a rotational force from the motor. 
     In addition, according to another aspect of the present disclosure, the first stable roller, the second stable roller, and the third stable roller are in contact with an outer circumferential surface of the driving gear. 
     In addition, according to another aspect of the present disclosure, the display device further includes: a rim formed in one end of the panel roller; and a plurality of ribs sequentially disposed along a circumferential direction of the rim on an outer circumferential surface of the rim, wherein the rim is press-fitted to the bearing. 
     In addition, according to another aspect of the present disclosure, a width of the first stable roller is larger than a width of the second stable roller or the third stable roller. 
     In addition, according to another aspect of the present disclosure, a first distance from a rotation center of the panel roller to a rotation center of the first stable roller is larger than a second distance from the rotation center of the panel roller to a rotation center of the second stable roller, or a third distance from the rotation center of the panel roller to a rotation center of the third stable roller. 
     In addition, according to another aspect of the present disclosure, the first stable roller, the second stable roller, and the third stable roller are disposed in a triangle with respect to the panel roller. 
     In addition, according to another aspect of the present disclosure, the display device further includes: a module cover which extends long in a length direction of the panel roller, and has a plurality of segments sequentially arranged in an up-down direction of the display panel on a rear surface of the display panel, wherein the display panel and the module cover are wound around or unwound from the panel roller. 
     In addition, according to another aspect of the present disclosure, the display panel descends while being unwound from the panel roller, and ascends while being wound around the panel roller. 
     Certain embodiments or other embodiments of the invention described above are not mutually exclusive or distinct from each other. Any or all elements of the embodiments of the invention described above may be combined or combined with each other in configuration or function. 
     For example, a configuration “A” described in one embodiment of the invention and the drawings and a configuration “B” described in another embodiment of the invention and the drawings may be combined with each other. Namely, although the combination between the configurations is not directly described, the combination is possible except in the case where it is described that the combination is impossible. 
     Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.