Patent Publication Number: US-2022225519-A1

Title: Display apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is claims priority benefit of Japanese Patent Application No. JP 2021-002600 filed in the Japan Patent Office on Jan. 12, 2021. The above-referenced application is hereby incorporated by reference in its entirety. 
     BACKGROUND 
     The present disclosure relates to a display apparatus, and particularly, to a display apparatus including a display panel that has flexibility. 
     In related art, a display apparatus including a display panel that has flexibility is known. Examples of this type of display apparatus include a display apparatus disclosed in Japanese Patent No. 6698920. The display apparatus includes a display panel that has flexibility, a circuit board that drives the display panel, a flexible film that connects the display panel and the circuit board, a back cover layered on the display panel, and a core to which the circuit board and the back cover are fixed, the core being configured to roll up the display panel and other parts. 
     SUMMARY 
     If the elasticity of a part of the back cover overlapping the flexible film is similar to the elasticity of a part overlapping the display panel, the display panel and other parts can easily be rolled up. However, there is a problem that the quality is reduced by a contact failure or other failure caused by the pull of the flexible film when the display panel and other parts are rolled up. There is also a problem that it becomes difficult to roll up the display panel and other parts if the part of the back cover overlapping the flexible film is prevented from being curved. 
     The present disclosure has been made in view of the problems above, and it is desirable to provide a display apparatus that can suppress a reduction in quality while preventing a display panel from becoming difficult to roll up. 
     According to an embodiment of the present disclosure, there is provided a display apparatus including a display panel that has flexibility, a drive board that drives the display panel, a flexible board that connects the display panel and the drive board and that has flexibility, a core to which the drive board is fixed, the core being configured to roll up the display panel and the flexible board, and a connection member including a plate-shaped member layered on the display panel, the plate-shaped member connecting the display panel and the core, the plate-shaped member being rolled up around the core along with the display panel and the flexible board. The plate-shaped member includes a first part overlapping the display panel and curved in a state in which the display panel is rolled up around the core and a second part overlapping the flexible board and curved in a state in which the flexible board is rolled up around the core. In a roll-up direction of the plate-shaped member, an elongation rate of the second part is smaller than an elongation rate of the first part. 
     According to the embodiment of the present disclosure, the display apparatus that can suppress reduction in quality while preventing the display panel from becoming difficult to roll up can be provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  are perspective views illustrating a display apparatus according to a first embodiment in different states; 
         FIGS. 2A and 2B  are cross-sectional views illustrating the display apparatus in the respective states illustrated in  FIGS. 1A and 1B ; 
         FIG. 3  is a cross-sectional view illustrating part of a display panel and other parts of the display apparatus of  FIGS. 1A and 1B ; 
         FIGS. 4A and 4B  depict a cross section of the display apparatus of  FIG. 1A  and a connection member; 
         FIGS. 5A and 5B  depict a part surrounded by a dashed line C and a part surrounded by a dashed line D in  FIG. 4B ; 
         FIGS. 6A and 6B  depict an example of a connection member used in an experiment for obtaining an elongation rate; 
         FIGS. 7A and 7B  depict results of the experiment for obtaining the elongation rate, using the connection member of  FIGS. 6A and 6B ; 
         FIG. 8  depicts examples of a material of a protection member; 
         FIGS. 9A and 9B  depict a cross section of a display apparatus and a connection member according to a second embodiment; 
         FIGS. 10A and 10B  depict another example of the connection member used in an experiment for obtaining an elongation rate; 
         FIGS. 11A and 11B  depict results of the experiment for obtaining the elongation rate, using the connection member of  FIGS. 10A and 10B ; 
         FIG. 12  is a cross-sectional view illustrating a display apparatus according to a third embodiment; and 
         FIGS. 13A and 13B  depict a cross section of a display apparatus and a connection member according to a fourth embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of a display apparatus according to the present disclosure will now be described with reference to the drawings. Note that each of the embodiments described below illustrates a specific example of the present disclosure. Therefore, values, constituent elements, and arrangement positions and the connection modes of the constituent elements described in the following embodiments are examples and are not intended to limit the present disclosure. Thus, the constituent elements not described in the independent claim among the constituent elements in the following embodiments are described as optional constituent elements. 
     In the drawings, substantially the same constituent elements are provided with the same symbols. The drawings are schematic diagrams and may not represent exact ratios of sizes of the components. 
     In the following description, a first direction is a direction indicated by an X-axis in  FIGS. 1A to 6B, 9A to 10B , and  12  to  13 B. A second direction is a direction indicated by a Y-axis in  FIGS. 1A to 6B, 9A to 10B, and 12 to 13B . A third direction is a direction indicated by a Z-axis in  FIGS. 1A to 6B, 9A to 10B, and 12 to 13B . The first direction, the second direction, and the third direction are directions orthogonal to each other. 
     First Embodiment 
     A display apparatus  10  according to a first embodiment will be described with reference to  FIGS. 1A to 8 . 
       FIGS. 1A and 1B  are perspective views illustrating the display apparatus  10  according to the first embodiment in different states.  FIG. 1A  illustrates a state in which a display panel  12  and other parts are drawn out, and  FIG. 1B  illustrates a state in which the display panel  12  and other parts are rolled up.  FIGS. 2A and 2B  are cross-sectional views illustrating the display apparatus  10  in the respective states illustrated in  FIGS. 1A and 1B .  FIG. 2A  illustrates a cross section along a line IIa-IIa in  FIG. 1A , and  FIG. 2B  illustrates a cross section along a line IIb-IIb in  FIG. 1B .  FIG. 3  is a cross-sectional view illustrating part of the display panel  12  and other parts of the display apparatus  10  of  FIGS. 1A and 1B .  FIGS. 4A and 4B  depict a cross section of the display apparatus  10  of  FIG. 1A  and a connection member  20 .  FIG. 4A  illustrates the cross section of the display apparatus  10 , and  FIG. 4B  illustrates the connection member  20 .  FIGS. 5A and 5B  depict a part surrounded by a dashed line C and a part surrounded by a dashed line D in  FIG. 4B .  FIG. 5A  illustrates the part surrounded by the dashed line C in  FIG. 4B , and  FIG. 5B  illustrates the part surrounded by the dashed line D in  FIG. 4B . Note that, in  FIGS. 2A and 2B  and  FIG. 4A , a plurality of first through holes  42 , a plurality of second through holes  44 , and other details are not illustrated in order to prevent complication of the drawings. This similarly applies to  FIG. 9A ,  FIG. 12 , and  FIG. 13A . 
     As illustrated in  FIGS. 1A to 5B , the display apparatus  10  is an apparatus that displays an image and other information, and the display apparatus  10  includes the display panel  12 , a drive board  14 , a flexible board  16 , an optical adhesive sheet (optical clear adhesive or OCA)  18 , the connection member  20 , a protection member  22 , a core  24 , a pantograph unit  26 , and a motor  28 . The display apparatus  10  is a rollable display apparatus that can roll up the display panel  12 , the flexible board  16 , the optical adhesive sheet  18 , the connection member  20 , and the protection member  22  and that can draw out the rolled display panel  12  and other parts. The display apparatus  10  is used in, for example, a tablet terminal, a digital television, digital signage, a smartphone, or a wearable terminal. 
     The display panel  12  is a panel that displays an image, and has flexibility. The display panel  12  is what is generally called a flexible display. The display panel  12  has a rectangular shape with the first direction as a transverse direction and the second direction as a longitudinal direction and has a plate shape with the third direction as a thickness direction in the state in which the display panel  12  is drawn out from the core  24 . The display panel  12  displays an image toward one side in the third direction (positive side in the Z-axis direction). The display panel  12  includes a cover window  30 , an optical adhesive sheet  32 , a circularly polarizing plate  34 , an optical adhesive sheet  36 , and an organic light emitting diode (OLED) panel  38 . The cover window  30 , the optical adhesive sheet  32 , the circularly polarizing plate  34 , the optical adhesive sheet  36 , and the OLED panel  38  are layered in this order in the thickness direction of the display panel  12 . The thickness direction of the display panel  12  coincides with the thickness direction of the optical adhesive sheet  18 , the thickness direction of a plate-shaped member  40 , and the thickness direction of the protection member  22 . The cover window  30  is attached to the circularly polarizing plate  34  through the optical adhesive sheet  32 , and the circularly polarizing plate  34  is attached to the OLED panel  38  through the optical adhesive sheet  36 . The OLED panel  38  includes, for example, layers of a thin film transistor (TFT), an OLED including organic electro-luminescence (EL) elements, and thin film encapsulation (TFE). 
     The drive board  14  is a circuit board that drives the display panel  12  and is electrically connected to the display panel  12  through the flexible board  16 . The drive board  14  includes a circuit that drives the display panel  12 . The drive board  14  is provided in front of the display panel  12  in a roll-up direction and is fixed to a main body  52  of the core  24  inside the main body  52 . The roll-up direction is a direction in which the display panel  12 , the flexible board  16 , the optical adhesive sheet  18 , the connection member  20 , and the protection member  22  move when the core  24  rolls up the display panel  12 , the flexible board  16 , the optical adhesive sheet  18 , the connection member  20 , and the protection member  22 . The drive board  14  is, for example, a printed circuit board (PCB). 
     The flexible board  16  is a circuit board that electrically connects the display panel  12  and the drive board  14 , and has flexibility. The flexible board  16  is connected to the display panel  12  and the drive board  14  and connects the display panel  12  and the drive board  14 . That is, the flexible board  16  links the display panel  12  and the drive board  14  through the flexible board  16  to prevent the display panel  12  and the drive board  14  from being separated from each other. The flexible board  16  is connected to a front end of the OLED panel  38  in the roll-up direction and protrudes forward in the roll-up direction with respect to the OLED panel  38 . The flexible board  16  includes a part not overlapping the display panel  12  as viewed from the third direction in the state in which the flexible board  16  is drawn out from the core  24 . A front end of the flexible board  16  in the roll-up direction is connected to the drive board  14 . Note that the flexible board  16  may not be directly connected to the display panel  12  and the drive board  14 , and the flexible board  16  may be indirectly connected to the display panel  12  and the drive board  14  through, for example, another member. The flexible board  16  is, for example, a chip on film (COF). 
     The optical adhesive sheet  18  is pasted to a main surface of the display panel  12  on the connection member  20  side and is layered on the display panel  12 . The optical adhesive sheet  18  is pasted to the entire main surface of the display panel  12 . Examples of an adhesive that can be used for the optical adhesive sheet  18  include acrylic, silicone, epoxy, and rubber adhesives. 
     The connection member  20  includes the plate-shaped member  40 , the plurality of first through holes  42 , and the plurality of second through holes  44 . 
     The plate-shaped member  40  is layered on the display panel  12  through the optical adhesive sheet  18  and attached to the display panel  12  through the optical adhesive sheet  18 . The plate-shaped member  40  is attached to a back surface of the display panel  12 . The plate-shaped member  40  protrudes forward with respect to the display panel  12  in the roll-up direction. A front end of the plate-shaped member  40  in the roll-up direction is fixed to a peripheral surface of the core  24 , and the plate-shaped member  40  connects the display panel  12  and the core  24 . That is, the plate-shaped member  40  links the display panel  12  and the core  24  through the plate-shaped member  40  to prevent the display panel  12  and the core  24  from being separated from each other. A back end of the plate-shaped member  40  in the roll-up direction is fixed to a first support member  56  of the pantograph unit  26 . The plate-shaped member  40  has flexibility and is rolled up around the core  24  along with the display panel  12 , the flexible board  16 , the optical adhesive sheet  18 , and the protection member  22 . Rigidity of the plate-shaped member  40  is higher than rigidity of the display panel  12  and the flexible board  16 , and the plate-shaped member  40  is a reinforcing member that maintains flatness of the display panel  12  in the state in which the display panel  12  is drawn out from the core  24 . The plate-shaped member  40  has a rectangular shape with the first direction as the transverse direction and the second direction as the longitudinal direction and has a plate shape with the third direction as the thickness direction in the state in which the plate-shaped member  40  is drawn out from the core  24 . Note that the shape of the plate-shaped member  40  is not limited to the rectangular shape with the first direction as the transverse direction and the second direction as the longitudinal direction in the state in which the plate-shaped member  40  is drawn out from the core  24 . For example, the plate-shaped member  40  may have a rectangular shape with the first direction as the longitudinal direction and the second direction as the transverse direction. The plate-shaped member  40  may not have a rectangular shape, and for example, the plate-shaped member  40  may have a square shape, another polygonal shape, a circular shape, or an elliptical shape. The plate-shaped member  40  is formed from, for example, metal with a large elastic region, such as steel use stainless (SUS)  301 . The plate-shaped member  40  includes a first part  46  and a second part  48 . 
     The first part  46  overlaps the display panel  12  in the thickness direction of the plate-shaped member  40 . The first part  46  is layered on the display panel  12  through the optical adhesive sheet  18  and attached to the display panel  12  through the optical adhesive sheet  18 . The first part  46  has a rectangular shape with the first direction as the transverse direction and the second direction as the longitudinal direction as viewed from the third direction in the state in which the first part  46  is drawn out from the core  24 , and the first part  46  overlaps the display panel  12 . Note that the shape of the first part  46  is not limited to the rectangular shape with the first direction as the transverse direction and the second direction as the longitudinal direction in the state in which the first part  46  is drawn out from the core  24 . The first part  46  may have, for example, a rectangular shape with the first direction as the longitudinal direction and the second direction as the transverse direction. The first part  46  is curved in the state in which the display panel  12  is rolled up around the core  24 . That is, the plate-shaped member  40  is rolled up around the core  24  in the state in which the first part  46  is curved. 
     The second part  48  overlaps the flexible board  16  in the thickness direction of the plate-shaped member  40 . The second part  48  is spaced apart from the flexible board  16 . The second part  48  has a rectangular shape with the first direction as the longitudinal direction and the second direction as the transverse direction as viewed from the third direction in the state in which the second part  48  is drawn out from the core  24 , and the second part  48  overlaps the flexible board  16 . The second part  48  is curved in the state in which the flexible board  16  is rolled up around the core  24 . That is, the plate-shaped member  40  is rolled up around the core  24  in the state in which the second part  48  is curved. 
     The second part  48  is positioned in front of the first part  46  in the roll-up direction and is adjacent to the first part  46 . A boundary  50  between the first part  46  and the second part  48  extends in an orthogonal direction orthogonal to the thickness direction of the plate-shaped member  40  and orthogonal to the roll-up direction, and the boundary  50  overlaps the display panel  12  in the thickness direction of the plate-shaped member  40 . The orthogonal direction is a direction coinciding with the first direction. Part of the second part  48 , specifically, a back end of the second part  48  in the roll-up direction, overlaps the display panel  12  and is attached to the display panel  12  through the optical adhesive sheet  18 . The boundary  50  is, for example, intermediate positions between the first through holes  42  and the second through holes  44  adjacent to each other in the roll-up direction. 
     An elongation rate of the second part  48  in the roll-up direction is smaller than an elongation rate of the first part  46 . The elongation rate of the second part  48  in the roll-up direction is (elongated dimension of second part  48  in roll-up direction)/(dimension of second part  48  in roll-up direction), and the elongation rate of the first part  46  in the roll-up direction is (elongated dimension of first part  46  in roll-up direction)/(dimension of first part  46  in roll-up direction). The dimension of the second part  48  in the roll-up direction is, for example, a dimension from a front end of the second through holes  44  in a front row to a back end of the second through holes  44  in a last row in the roll-up direction. The dimension of the first part  46  in the roll-up direction is a dimension from a front end of the first through holes  42  in a front row to a back end of the first through holes  42  in a last row in the roll-up direction. 
     The plurality of first through holes  42  are provided in a staggered pattern in the first part  46 . More specifically, the plurality of first through holes  42  include a plurality of first hole rows each including one or more first through holes  42  lined up in the orthogonal direction. The plurality of first hole rows are lined up in the roll-up direction, and the first through holes  42  in the first hole rows adjacent to each other in the roll-up direction among the plurality of first hole rows are adjacent to each other and shifted from each other in the orthogonal direction. The plurality of first through holes  42  are lined up at equal intervals in the orthogonal direction and are lined up at equal intervals in the roll-up direction. In the first embodiment, the plurality of first through holes  42  are provided in a staggered pattern from the front end to the back end of the first part  46  in the roll-up direction. Each of the plurality of first through holes  42  is a long hole going through the plate-shaped member  40  in the thickness direction of the plate-shaped member  40  and extending in the orthogonal direction, and each of the plurality of first through holes  42  has an oval shape. Note that each of the plurality of first through holes  42  may not have an oval shape and may have, for example, a rectangular shape. The plurality of first through holes  42  are formed by, for example, wet etching. 
     L1&gt;S1 is satisfied where L1 represents a dimension of each of the plurality of first through holes  42  in the orthogonal direction and S1 represents a dimension between two first through holes  42  adjacent to each other in the orthogonal direction among the plurality of first through holes  42 . S1 is a dimension of the part not provided with the first through holes  42 , between two first through holes  42  adjacent to each other in the orthogonal direction among the plurality of first through holes  42 . In the first embodiment, L1/S1=3/0.1 is satisfied. 
     W1&gt;T1 is satisfied where W1 represents a dimension of each of the plurality of first through holes  42  in the roll-up direction and T1 represents a dimension between two first through holes  42  adjacent to each other in the roll-up direction among the plurality of first through holes  42 . T1 is a dimension of the part not provided with the first through holes  42 , between two first through holes  42  adjacent to each other in the roll-up direction among the plurality of first through holes  42 . 
     The plurality of second through holes  44  are provided in a staggered pattern in the second part  48 . More specifically, the plurality of second through holes  44  include a plurality of second hole rows each including one or more second through holes  44  lined up in the orthogonal direction. The plurality of second hole rows are lined up in the roll-up direction, and the second through holes  44  in the second hole rows adjacent to each other in the roll-up direction among the plurality of second hole rows are adjacent to each other and shifted from each other in the orthogonal direction. The plurality of second through holes  44  are lined up at equal intervals in the orthogonal direction and are lined up at equal intervals in the roll-up direction. In the first embodiment, the plurality of second through holes  44  are provided in a staggered pattern from the front end to the back end of the second part  48  in the roll-up direction. Each of the plurality of second through holes  44  is a long hole going through the plate-shaped member  40  in the thickness direction of the plate-shaped member  40  and extending in the orthogonal direction, and each of the plurality of second through holes  44  has an oval shape. Note that each of the plurality of second through holes  44  may not have an oval shape and may have, for example, a rectangular shape. The plurality of second through holes  44  are formed by, for example, wet etching. 
     L2&gt;S2 is satisfied where L2 represents a dimension of each of the plurality of second through holes  44  in the orthogonal direction and S2 represents a dimension between two second through holes  44  adjacent to each other in the orthogonal direction among the plurality of second through holes  44 . S2 is a dimension of the part not provided with the second through holes  44 , between two second through holes  44  adjacent to each other in the orthogonal direction among the plurality of second through holes  44 . In the first embodiment, L2/S2=1/0.1 is satisfied, and (L1/S1)&gt;(L2/S2) is satisfied. In addition, L2&lt;L1 is satisfied, and S2=S1 is satisfied. 
     W2&gt;T2 is satisfied where W2 represents a dimension of each of the plurality of second through holes  44  in the roll-up direction and T2 represents a dimension between two second through holes  44  adjacent to each other in the roll-up direction among the plurality of second through holes  44 . T2 is a dimension of the part not provided with the second through holes  44 , between two second through holes  44  adjacent to each other in the roll-up direction among the plurality of second through holes  44 . In the first embodiment, W1=W2 is satisfied, and T1=T2 is satisfied. 
     As described above, the plurality of first through holes  42  are provided in the first part  46 , and the plurality of second through holes  44  are provided in the second part  48 . As a result, the elongation rate of the second part  48  in the roll-up direction is smaller than the elongation rate of the first part  46 . Note that the configuration of the plurality of first through holes  42  and second through holes  44  is not limited to the configuration described above, and it is only necessary that the elongation rate of the second part  48  in the roll-up direction be smaller than the elongation rate of the first part  46 . 
     The first part  46  may be provided with, for example, a plurality of recessed portions in place of the plurality of first through holes  42 , and the second part  48  may be provided with, for example, a plurality of recessed portions in place of the plurality of second through holes  44 , to thereby make the elongation rate of the second part  48  in the roll-up direction smaller than the elongation rate of the first part  46 . Instead of providing the plurality of first through holes  42  in the first part  46  and providing the plurality of second through holes  44  in the second part  48 , different materials may be used for the first part  46  and the second part  48 , to thereby make the elongation rate of the second part  48  in the roll-up direction smaller than the elongation rate of the first part  46 . 
     The protection member  22  is a back surface cover that suppresses damage or other failure of a surface of the display panel  12  when the display panel  12  and other parts are rolled up, and the protection member  22  is layered on the connection member  20 . The protection member  22  is adhesive and is attached to a main surface of the connection member  20  on an opposite side with respect to the display panel  12 . The protection member  22  has a rectangular shape with the first direction as the transverse direction and the second direction as the longitudinal direction and has a plate shape with the third direction as the thickness direction as viewed from the third direction in the state in which the protection member  22  is drawn out from the core  24 . The protection member  22  overlaps the display panel  12 . The protection member  22  is formed from, for example, urethane or silicone. Note that the protection member  22  may not be adhesive and may be attached to the connection member  20  through an adhesive or other materials. 
     The core  24  is a roller to which the drive board  14  and the plate-shaped member  40  are fixed, the roller being configured to roll up the display panel  12 , the flexible board  16 , the optical adhesive sheet  18 , the connection member  20 , and the protection member  22 . Specifically, the core  24  is a member around which the display panel  12 , the flexible board  16 , the optical adhesive sheet  18 , the connection member  20 , and the protection member  22  are rolled up when they are to be rolled up. The core  24  includes the main body  52  and a through portion  54 . The main body  52  has a substantially cylindrical shape with the first direction as its axial direction, and the front end of the plate-shaped member  40  in the roll-up direction is fixed to a peripheral surface of the main body  52 . The through portion  54  goes through the main body  52  in a radial direction of the main body  52  and extends in the axial direction of the main body  52 . The flexible board  16  is inserted into the through portion  54 . 
     The pantograph unit  26  includes the first support member  56 , a second support member  58 , a first arm portion  60 , and a second arm portion  62 . The first support member  56  sandwiches the back end of the plate-shaped member  40  and a back end of the protection member  22  in the roll-up direction and is attached to the back end of the plate-shaped member  40  and the back end of the protection member  22  in the roll-up direction. The second support member  58  is fixed to a member (not illustrated) that supports the core  24  in such a manner that the core  24  can be rotated. The first arm portion  60  and the second arm portion  62  connect the first support member  56  and the second support member  58  and apply a force in directions in which the first support member  56  and the second support member  58  separate from each other. 
     The motor  28  rotates the core  24 . As the motor  28  is rotated in one direction, the core  24  is rotated in one direction about an axial center O. The first support member  56  moves in a direction away from the second support member  58 , and the display panel  12  and other parts are drawn out from the core  24  (see an arrow E1 in  FIGS. 1A and 2A ). As the motor  28  is rotated in the other direction, the core  24  is rotated in the other direction about the axial center O. The first support member  56  moves in a direction toward the second support member  58 , and the display panel  12  and other parts are rolled up (see an arrow E2 in  FIGS. 1B and 2B ). 
       FIGS. 6A and 6B  depict an example of a connection member  64  used in an experiment for obtaining the elongation rate.  FIG. 6A  illustrates the entire connection member  64 , and  FIG. 6B  illustrates a part surrounded by a dashed line in FIG.  6 A.  FIGS. 7A and 7B  depict results of the experiment for obtaining the elongation rate, using the connection member  64  of  FIGS. 6A and 6B . Note that, in  FIG. 6A , through holes  72  are not illustrated in order to prevent complication of the drawing. 
     As illustrated in  FIGS. 6A and 6B , the connection member  64  has a dimension of 245 [mm] in the roll-up direction, a dimension of 321.9 [mm] in the orthogonal direction, and a dimension of 0.2 [mm] in the thickness direction of the connection member  64 , and the connection member  64  is formed from SUS 301. Through holes are not formed in a part  66  with a length of 9.2 [mm] toward a back end from a front end of the connection member  64  in the roll-up direction. Through holes are not formed in a part  68  with a length of 10.3 [mm] toward the front end from the back end of the connection member  64  in the roll-up direction. A plurality of through holes  72  are provided in a staggered pattern in a part  70  between the part  66  and the part  68 . A dimension of each of the plurality of through holes  72  in the roll-up direction is 0.2 [mm], and a dimension between two through holes  72  adjacent to each other in the roll-up direction among the plurality of through holes  72  is 0.1 [mm]. 
     As illustrated in  FIGS. 6A to 7B , in the case of L=1 [mm] and S=0.1 [mm], L representing a dimension of each of the plurality of through holes  72  in the orthogonal direction, S representing a dimension between two through holes  72  adjacent to each other in the orthogonal direction among the plurality of through holes  72 , the elongation rate of the connection member  64  in the roll-up direction is 0 [%] when loads of 0 [g], 200 [g], 600 [g], and 1000 [g] are applied to the connection member  64  in the roll-up direction. That is, the connection member  64  is curved but is not elongated in the roll-up direction in this case. 
     In the case of L=2 [mm] and S=0.1 [mm], the elongation rate of the connection member  64  in the roll-up direction is 0 [%] when a load of 0 [g] is applied to the connection member  64  in the roll-up direction, and the elongation rate of the connection member  64  in the roll-up direction is 0.2 [%] when a load of 200 [g] is applied. In this case, the elongation rate of the connection member  64  in the roll-up direction is 0.7 [%] when a load of 600 [g] is applied to the connection member  64  in the roll-up direction, and the elongation rate of the connection member  64  in the roll-up direction is 1.1 [%] when a load of 1000 [g] is applied. 
     In the case of L=3 [mm] and S=0.1 [mm], the elongation rate of the connection member  64  in the roll-up direction is 0 [%] when a load of 0 [g] is applied to the connection member  64  in the roll-up direction, and the elongation rate of the connection member  64  in the roll-up direction is 0.9 [%] when a load of 200 [g] is applied. In this case, the elongation rate of the connection member  64  in the roll-up direction is 2.7 [%] when a load of 600 [g] is applied to the connection member  64  in the roll-up direction, and the elongation rate of the connection member  64  in the roll-up direction is 4.4 [%] when a load of 1000 [g] is applied. 
     In the case of L=4 [mm] and S=0.1 [mm], the elongation rate of the connection member  64  in the roll-up direction is 0 [%] when a load of 0 [g] is applied to the connection member  64  in the roll-up direction, and the elongation rate of the connection member  64  in the roll-up direction is 2.7 [%] when a load of 200 [g] is applied. In this case, the elongation rate of the connection member  64  in the roll-up direction is 8.0 [%] when a load of 600 [g] is applied to the connection member  64  in the roll-up direction, and the elongation rate of the connection member  64  in the roll-up direction is 13.3 [%] when a load of 1000 [g] is applied. 
     In this way, the larger the L with respect to S, that is, the larger the L/S, the larger the elongation rate in the roll-up direction, and the connection member  64  can easily be elongated in the roll-up direction. L1/S1=3/0.1 is satisfied, and L2/S2=1/0.1 is satisfied in the connection member  20  described above. Therefore, it can be recognized that the elongation rate of the second part  48  in the roll-up direction is smaller than the elongation rate of the first part  46 . 
       FIG. 8  depicts examples of a material of the protection member  22 . 
     As illustrated in  FIG. 8 , the protection member  22  with a thickness of 500 [μm] formed by using urethane foam has a tensile strength of 0.74 [MPa], a tensile elongation of 350 [%], and a heat resistance of 80 [° C.]. 
     The protection member  22  with a thickness of 700 [μm] formed by using silicone foam has a tensile strength of 0.32 [MPa], a tensile elongation of 70 [%], and a heat resistance of 180 [° C.]. 
     The protection member  22  with a thickness of 500 [μm] formed by using a urethane foam film support has a tensile strength of 224 [MPa] in a transverse direction (TD) and 188 [MPa] in a machine direction (MD), a tensile elongation of 100 [%] in TD and 134 [%] in MD, and a heat resistance of 80 [° C.]. 
     The protection member  22  with a thickness of 300 [μm] formed by using nylon 66 has a tensile strength of 244 [MPa] in TD and 236 [MPa] in MD, a tensile elongation of 30 [%] in TD and 27 [%] in MD, and a heat resistance of 150 [° C.]. 
     The protection member  22  with a thickness of 500 [μm] formed by using Kevlar has a tensile strength of 3400 [MPa], a tensile elongation of 3.3 [%], and a heat resistance of 250 [° C.]. 
     The display apparatus  10  has been described. 
     The display apparatus  10  according to the first embodiment includes the display panel  12  that has flexibility, the drive board  14  that drives the display panel  12 , the flexible board  16  that connects the display panel  12  and the drive board  14  and that has flexibility, the core  24  to which the drive board  14  is fixed, the core  24  being configured to roll up the display panel  12  and the flexible board  16 , and the connection member  20  including the plate-shaped member  40  layered on the display panel  12 , the plate-shaped member  40  connecting the display panel  12  and the core  24 , the plate-shaped member  40  being rolled up around the core  24  along with the display panel  12  and the flexible board  16 . The plate-shaped member  40  includes the first part  46  overlapping the display panel  12  and curved in the state in which the display panel  12  is rolled up around the core  24  and the second part  48  overlapping the flexible board  16  and curved in the state in which the flexible board  16  is rolled up around the core  24 , and the elongation rate of the second part  48  in the roll-up direction of the plate-shaped member  40  is smaller than the elongation rate of the first part  46 . 
     According to this configuration, in the plate-shaped member  40  connecting the display panel  12  and the core  24 , the elongation rate of the second part  48  in the roll-up direction overlapping the flexible board  16  is smaller than the elongation rate in the roll-up direction of the first part  46  overlapping the display panel  12 . Therefore, when the core  24  rolls up the display panel  12  and other parts, the first part  46  can easily be elongated to easily roll up the display panel  12 , and the second part  48  can suppress the pull of the flexible board  16 . This can suppress occurrence of a contact failure or other failures caused by the pull of the flexible board  16  and can suppress reduction in quality. As described, this can suppress the reduction in quality while preventing the display panel  12  from becoming difficult to roll up. 
     The second part  48  is attached to the display panel  12  in the display apparatus  10  according to the first embodiment. 
     According to this configuration, when the core  24  rolls up the display panel  12  and other parts, the second part  48  can suppress the pull of the display panel  12 , and the pull of the flexible board  16  connected to the display panel  12  can be suppressed. This can further suppress the occurrence of a contact failure or other failures caused by the pull of the flexible board  16  and can further suppress the reduction in quality. 
     In the display apparatus  10  according to the first embodiment, the connection member  20  includes the plurality of first through holes  42  provided in a staggered pattern in the first part  46  and the plurality of second through holes  44  provided in a staggered pattern in the second part  48 , and (L1/S1)&gt;(L2/S2) is satisfied, where L1 represents the dimension of each of the plurality of first through holes  42  in the orthogonal direction orthogonal to the thickness direction of the plate-shaped member  40  and orthogonal to the roll-up direction, S1 represents the dimension between two first through holes  42  adjacent to each other in the orthogonal direction among the plurality of first through holes  42 , L2 represents the dimension of each of the plurality of second through holes  44  in the orthogonal direction, and S2 represents the dimension between two second through holes  44  adjacent to each other in the orthogonal direction among the plurality of second through holes  44 . 
     Therefore, the larger the L/S, the larger the elongation rate in the roll-up direction according to the experiment results described above. Thus, (L1/S1)&gt;(L2/S2) can be satisfied to make the elongation rate of the second part  48  in the roll-up direction smaller than the elongation rate of the first part  46 . This can suppress the occurrence of a contact failure or other failures caused by the pull of the flexible board  16  and can suppress the reduction in quality. 
     In the display apparatus  10  according to the first embodiment, (L1/S1)=(3/0.1) is satisfied, and (L2/S2)=(1/0.1) is satisfied. 
     Therefore, (L1/S1)=(3/0.1) can be satisfied to properly extend the first part  46  in the roll-up direction, and (L2/S2)=(1/0.1) can be satisfied to prevent the second part  48  from elongating in the roll-up direction according to the experiment results described above. This can further prevent the display panel  12  from becoming difficult to roll up and can further suppress the reduction in quality. 
     Second Embodiment 
     A display apparatus  10   a  according to a second embodiment will be described with reference to  FIGS. 9A to 11B . The display apparatus  10   a  is mainly different from the display apparatus  10  in that a first part  46   a  includes a structure in which third parts  74  provided with the plurality of first through holes  42  in a staggered pattern and fourth parts  76  not provided with the plurality of first through holes  42  are alternately arranged in the roll-up direction. Differences from the display apparatus  10  will mainly be described. 
       FIGS. 9A and 9B  depict a cross section of the display apparatus  10   a  and a connection member  20   a  according to the second embodiment.  FIG. 9A  illustrates the cross section of the display apparatus  10   a , and  FIG. 9B  illustrates the connection member  20   a.    
     As illustrated in  FIGS. 9A and 9B , the display apparatus  10   a  is mainly different from the display apparatus  10  in that the display apparatus  10   a  includes the connection member  20   a  in place of the connection member  20 , and the connection member  20   a  includes a plate-shaped member  40   a  in place of the plate-shaped member  40 . 
     The plate-shaped member  40   a  includes the first part  46   a  and the second part  48 . The first part  46   a  includes a plurality of third parts  74  provided with the plurality of first through holes  42  and includes a plurality of fourth parts  76  not provided with the plurality of first through holes  42 . The third parts  74  and the fourth parts  76  are alternately arranged in the roll-up direction. The third parts  74  are each provided with the plurality of first through holes  42  in a staggered pattern. 
     A&lt;B is satisfied where A represents a dimension of each third part  74  in the roll-up direction and B represents a dimension of each fourth part  76  in the roll-up direction. In the second embodiment, (A/B)=(0.8/1) is satisfied. The dimension of the third part  74  in the roll-up direction is, for example, a dimension from a front end of the first through holes  42  in a front row to a back end of the first through holes  42  in a last row in the roll-up direction among the plurality of first through holes  42  provided in the third part  74 . The dimension of the fourth part  76  in the roll-up direction is, for example, a dimension from a back end of the first through holes  42  in a last row among the plurality of first through holes  42  provided in the third part  74  adjacent to and on the front side of the fourth part  76  to a front end of the first through holes  42  in a front row among the plurality of first through holes  42  provided in the third part  74  adjacent to and on the back side of the fourth part  76 . Alternatively, the dimension of the fourth part  76  in the roll-up direction is, for example, a dimension from a back end of the second through holes  44  in a last row among the plurality of second through holes  44  provided in the second part  48  adjacent to and on the front side of the fourth part  76  to the front end of the first through holes  42  in the front row among the plurality of first through holes  42  provided in the third part  74  adjacent to and on the back side of the fourth part  76 . 
     Note that, for example, A≥B may be satisfied instead of A&lt;B. T1 (see  FIG. 5A )&lt;B may be satisfied, and W1 (see  FIG. 5A )&lt;B may be satisfied. 
     (1−(A+B)×n/2×n×R)≤0.2 is satisfied where R represents a radius of the main body  52 , n represents a pi, and n represents the number of sets per cycle in the state in which the plate-shaped member  40   a  is rolled up around the core  24 , each set including one third part  74  and one fourth part  76  adjacent to the third part  74 . 
       FIGS. 10A and 10B  depict another example of the connection member, denoted by  78 , used in an experiment for obtaining the elongation rate.  FIGS. 11A and 11B  depict results of the experiment for obtaining the elongation rate, using the connection member  78  of  FIGS. 10A and 10B . Note that, in FIG.  10 A, through holes  84  are not illustrated in order to prevent complication of the drawing. 
     As illustrated in  FIGS. 10A and 10B , the connection member  78  has a dimension of 245 [mm] in the roll-up direction, a dimension of 321.9 [mm] in the orthogonal direction, and a dimension of 0.2 [mm] in the thickness direction of the connection member  78 , and the connection member  78  is formed from SUS 301. Through holes are not formed in a part  80  with a length of 9.2 [mm] toward a back end from a front end of the connection member  78  in the roll-up direction. Through holes are not formed in a part  82  with a length of 10.3 [mm] toward the front end from the back end of the connection member  78  in the roll-up direction. Parts  86  provided with a plurality of through holes  84  in a staggered pattern and parts  88  not provided with through holes are alternately arranged between the part  80  and the part  82 . A dimension of each of the plurality of through holes  84  in the orthogonal direction is 0.5 [mm], and a dimension between two through holes  84  adjacent to each other in the orthogonal direction among the plurality of through holes  84  is 0.1 [mm]. A dimension of each of the plurality of through holes  84  in the roll-up direction is 0.2 [mm], and a dimension between two through holes  84  adjacent to each other in the roll-up direction among the plurality of through holes  84  is 0.1 [mm]. 
     As illustrated in  FIGS. 10A to 11B , in the case of A=1.4 [mm] and B=5 [mm], the elongation rate of the connection member  78  in the roll-up direction is 0 [%] when a load of 0 [g] is applied to the connection member  78  in the roll-up direction, and the elongation rate of the connection member  78  in the roll-up direction is 0.4 [%] when a load of 200 [g] is applied. In this case, the elongation rate of the connection member  78  in the roll-up direction is 1.3 [%] when a load of 600 [g] is applied to the connection member  78  in the roll-up direction, and the elongation rate of the connection member  78  in the roll-up direction is 2.2 [%] when a load of 1000 [g] is applied. 
     In the case of A=1.4 [mm] and B=2 [mm], the elongation rate of the connection member  78  in the roll-up direction is 0 [%] when a load of 0 [g] is applied to the connection member  78  in the roll-up direction, and the elongation rate of the connection member  78  in the roll-up direction is 2.7 [%] when a load of 200 [g] is applied. In this case, the elongation rate of the connection member  78  in the roll-up direction is 5.3 [%] when a load of 600 [g] is applied to the connection member  78  in the roll-up direction, and the elongation rate of the connection member  78  in the roll-up direction is 7.5 [%] when a load of 1000 [g] is applied. 
     In the case of A=0.8 [mm] and B=2 [mm], the elongation rate of the connection member  78  in the roll-up direction is 0 [%] when a load of 0 [g] is applied to the connection member  78  in the roll-up direction, and the elongation rate of the connection member  78  in the roll-up direction is 1.8 [%] when a load of 200 [g] is applied. In this case, the elongation rate of the connection member  78  in the roll-up direction is 4.0 [%] when a load of 600 [g] is applied to the connection member  78  in the roll-up direction, and the elongation rate of the connection member  78  in the roll-up direction is 5.3 [%] when a load of 1000 [g] is applied. 
     In the case of A=0.8 [mm] and B=1 [mm], the elongation rate of the connection member  78  in the roll-up direction is 0 [%] when a load of 0 [g] is applied to the connection member  78  in the roll-up direction, and the elongation rate of the connection member  78  in the roll-up direction is 1.6 [%] when a load of 200 [g] is applied. In this case, the elongation rate of the connection member  78  in the roll-up direction is 4.0 [%] when a load of 600 [g] is applied to the connection member  78  in the roll-up direction, and the elongation rate of the connection member  78  in the roll-up direction is 6.0 [%] when a load of 1000 [g] is applied. 
     In the connection member  20   a  described above, (A/B)=(0.8/1) is satisfied, and therefore, the first part  46   a  can properly be extended in the roll-up direction. While the plate thickness of the plate-shaped member  40   a  for securing a required strength, workability of the plurality of first through holes  42 , and other properties are limited, a high elongation rate and rigidity in a lateral direction (suppression of torsion) can be secured, so that periods of the third part  74  and the fourth part  76  are unlikely to be reflected as roughness on the surface of the display panel  12 . A contact area between the connection member  20   a  and the display panel  12  can also be increased, so that the connection member  20   a  and the display panel  12  are unlikely to be peeled off. 
     The display apparatus  10   a  has been described. 
     In the display apparatus  10   a  according to the second embodiment, the first part  46   a  includes the plurality of third parts  74  provided with the plurality of first through holes  42  and includes the plurality of fourth parts  76  not provided with the plurality of first through holes  42 . the third parts  74  and the fourth parts  76  are alternately arranged in the roll-up direction. A&lt;B is satisfied where A represents the dimension of each third part  74  in the roll-up direction and B represents the dimension of each fourth part  76  in the roll-up direction. 
     According to this configuration, the fourth parts  76  can be provided to increase the contact area between the connection member  20   a  and the display panel  12 , and an adhesive strength can be increased. This can prevent the connection member  20   a  from coming off from the display panel  12  and can suppress the reduction in quality. 
     In the display apparatus  10   a  according to the second embodiment, (A/B)=(0.8/1) is satisfied. 
     Therefore, (A/B)=(0.8/1) can be satisfied to properly extend the first part  46   a  in the roll-up direction according to the experiment results described above. 
     In the display apparatus  10   a  according to the second embodiment, (1−(A+B)×n/2×n×R)≤0.2 is satisfied where R represents the radius of the core  24 , n represents the pi, and n represents the number of sets per cycle in the state in which the plate-shaped member  40   a  is rolled up around the core  24 , each set including one third part  74  and one fourth part  76 . 
     This can increase the contact area between the connection member  20   a  and the display panel  12  to increase the adhesive strength while preventing the display panel  12  from becoming difficult to roll up. 
     Third Embodiment 
     A display apparatus  10   b  according to a third embodiment will be described with reference to  FIG. 12 . The display apparatus  10   b  is mainly different from the display apparatus  10  in that a main body  52   b  of a core  24   b  includes a step portion  90 . Differences from the display apparatus  10  will mainly be described. 
       FIG. 12  is a cross-sectional view illustrating the display apparatus  10   b  according to the third embodiment. 
     As illustrated in  FIG. 12 , the display apparatus  10   b  is mainly different from the display apparatus  10  in that the display apparatus  10   b  includes the core  24   b  in place of the core  24 . 
     The core  24   b  includes the main body  52   b  and a through portion  54   b . The main body  52   b  has a substantially cylindrical shape with the first direction as its axial direction and includes the step portion  90  recessed inward on a peripheral surface of the main body  52   b . A dimension (depth) of the step portion  90  in a radial direction of the main body  52   b  is a dimension equivalent to the sum of a dimension of the plate-shaped member  40  in the thickness direction and a dimension of the protection member  22  in the thickness direction. 
     The plate-shaped member  40  is fixed to the step portion  90 . The plate-shaped member  40  and the protection member  22  are fixed to the step portion  90  such that they do not stick out from the step portion  90  in the radial direction of the main body  52   b.    
     The display apparatus  10   b  has been described. 
     In the display apparatus  10   b  according to the third embodiment, the core  24   b  includes the step portion  90  recessed inward on the peripheral surface of the core  24   b , and the plate-shaped member  40  is fixed to the step portion  90 . 
     This can prevent the plate-shaped member  40  fixed to the core  24   b  from protruding outside the core  24   b  in the radial direction of the core  24   b . Therefore, this can further prevent the display panel  12  from becoming difficult to roll up. Damage of the display panel  12  can be suppressed, and the reduction in quality can be suppressed. 
     Fourth Embodiment 
     A display apparatus  10   c  according to a fourth embodiment will be described with reference to  FIGS. 13A and 13B . The display apparatus  10   c  is mainly different from the display apparatus  10  in that a connection member  20   c  is fixed to a main body  52   c  of a core  24   c  inside the main body  52   c . Differences from the display apparatus  10  will mainly be described. 
       FIGS. 13A and 13B  depict a cross section of the display apparatus  10   c  and the connection member  20   c  according to the fourth embodiment.  FIG. 13A  illustrates the cross section of the display apparatus  10   c , and  FIG. 13B  illustrates the connection member  20   c.    
     As illustrated in  FIGS. 13A and 13B , the display apparatus  10   c  is mainly different from the display apparatus  10  in that the display apparatus  10   c  includes the connection member  20   c  in place of the connection member  20  and includes the core  24   c  in place of the core  24 , and the connection member  20   c  includes a plate-shaped member  40   c  in place of the plate-shaped member  40 . 
     The core  24   c  includes the main body  52   c  and a through portion  54   c . The main body  52   c  has a substantially cylindrical shape with the first direction as its axial direction, and the through portion  54   c  goes through the main body  52   c  in a radial direction of the main body  52   c  and extends in the axial direction of the main body  52   c.    
     The plate-shaped member  40   c  includes a fifth part  92  protruding toward the inside of the main body  52   c  from a front end of the second part  48  in the roll-up direction. The fifth part  92  and the flexible board  16  are inserted into the through portion  54   c . The fifth part  92  and the drive board  14  are layered on top of each other and fixed to the main body  52   c  inside the main body  52   c.    
     The display apparatus  10   c  has been described. 
     In the display apparatus  10   c  according to the fourth embodiment, the core  24   c  includes the cylindrical main body  52   c  and the through portion  54   c  going through the main body  52   c  in the radial direction of the main body  52   c , the flexible board  16  and the plate-shaped member  40   c  are inserted into the through portion  54   c , and the drive board  14  and the plate-shaped member  40   c  are layered on top of each other and fixed to the main body  52   c  inside the main body  52   c.    
     Therefore, the plate-shaped member  40   c  does not have to be fixed to a peripheral surface of the main body  52   c , and this can further prevent the display panel  12  from becoming difficult to roll up. 
     OTHER EMBODIMENTS, ETC. 
     While the display apparatus according to the present disclosure has been described based on the embodiments, the present disclosure is not limited to the embodiments. Modifications obtained by modifying the embodiments in various ways conceived by those skilled in the art without departing from the scope of the present disclosure and various devices incorporating the display panel according to the present disclosure are also included in the present disclosure. 
     The display apparatus according to the present disclosure can be used in a digital television, digital signage, a smartphone, a tablet terminal, a wearable terminal, and other devices. 
     The present disclosure contains subject matter related to that disclosed in Japanese Priority Patent Application JP 2021-002600 filed in the Japan Patent Office on Jan. 12, 2021, the entire content of which is hereby incorporated by reference.