Patent Publication Number: US-2022232711-A1

Title: Display apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is claims priority benefit of Japanese Patent Application No. JP 2021-008245 filed in the Japan Patent Office on Jan. 21, 2021. The above-referenced application is hereby incorporated by reference in its entirety. 
     BACKGROUND 
     The present disclosure relates to a display apparatus. 
     In the past, an active-matrix display apparatus with light emitting element such as organic electro-luminescence (EL) element has been in practical use. There is a known technique in which a flexible display panel with flexible board is adopted in the display apparatus (for example, see Japanese Patent Laid-Open No. 2019-45855 (hereinafter, referred to as Patent Document 1)). The display apparatus described in Patent Document 1 includes cylindrical back bars on the back surface of the flexible display panel and side caps connecting the back bars. The back bars are intended to protect the display panel. 
     SUMMARY 
     In the display apparatus described in Patent Document 1, a fold or a curl remains on the display panel when the display panel is bent or rolled up. Therefore, large tension may need to be applied to the display panel to secure the flatness of the display panel when an image is displayed on the display panel. As a result, the tension may possibly damage the inside of the display panel. For example, an inorganic material film (such as a sealing film and a cathode electrode film) formed inside of the display panel may be cracked. A display failure may occur in the display apparatus when such a crack is generated. Although the toughness of the back bars and the side caps can be increased in the display apparatus described in Patent Document 1 to suppress the generation of the crack, the configuration of the back surface becomes complicated. 
     A protection member such as silicon foam can be provided on the back surface of the display panel to simplify the configuration of the back surface of the display panel. However, it is difficult to secure the toughness by using such a protection member, and the damage of the display panel may not sufficiently be suppressed. 
     The present disclosure has been made to solve the problems, and it is desirable to provide a display apparatus with a simplified configuration that can suppress damage of a flexible display panel. 
     According to an example of the present disclosure, there is provided a display apparatus including a display panel that is flexible, the display panel including a display surface and a back surface on a back side of the display surface, and a protection sheet attached to the back surface of the display panel and formed from woven fabric. 
     According to the example of the present disclosure, the display apparatus with a simplified configuration that can suppress damage of the flexible display panel can be provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a first perspective view illustrating a display apparatus according to a first embodiment; 
         FIG. 1B  is a second perspective view illustrating the display apparatus according to the first embodiment; 
         FIG. 2A  is a first cross-sectional view illustrating the display apparatus according to the first embodiment; 
         FIG. 2B  is a second cross-sectional view illustrating the display apparatus according to the first embodiment; 
         FIG. 3  is a schematic plan view illustrating a configuration of a display panel and a protection sheet according to the first embodiment; 
         FIG. 4  is a schematic cross-sectional view illustrating the configuration of the display panel and the protection sheet according to the first embodiment; 
         FIG. 5  is a schematic diagram illustrating a configuration of fibers contained in the protection sheet according to the first embodiment; 
         FIG. 6  is a schematic cross-sectional view illustrating a state in which the display panel and the protection sheet according to the first embodiment are rolled up; 
         FIG. 7  is a schematic plan view illustrating a display panel, a plate-shaped member, and a protection sheet of a display apparatus according to a second embodiment; and 
         FIG. 8  is a schematic cross-sectional view illustrating the display panel, the plate-shaped member, and the protection sheet of the display apparatus according to the second embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of 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, shapes, materials, constituent elements, arrangement positions and connection modes of the constituent elements, processes, and orders of the processes illustrated in the following embodiments are examples and are not intended to limit the present disclosure. Therefore, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims representing the highest level concept of the present disclosure are described as any constituent elements. 
     Further, the drawings are schematic diagrams, and the drawings may not strictly be illustrated. Therefore, for example, the reduced scales may not necessarily coincide in the drawings. Note that, in the drawings, the same reference signs are provided to substantially the same components, and the duplicate description will be omitted or simplified. 
     First Embodiment 
     A display apparatus according to a first embodiment will be described. 
     [1-1. Overall Configuration of Display Apparatus] 
     An overall configuration of the display apparatus according to the present embodiment will be described with reference to  FIGS. 1A and 1B .  FIGS. 1A and 1B  are first and second perspective views, respectively, illustrating a display apparatus  10  according to the present embodiment.  FIG. 1A  illustrates the display apparatus  10  in a state in which a flexible display panel  12  included in the display apparatus  10  is extended.  FIG. 1B  illustrates the display apparatus  10  in a state in which the flexible display panel  12  is rolled up.  FIGS. 2A and 2B  are first and second cross-sectional views, respectively, illustrating the display apparatus  10  according to the present embodiment.  FIG. 2A  illustrates a cross section along a line IIA-IIA in  FIG. 1 , and  FIG. 2B  illustrates a cross section along a line IIB-IIB in  FIG. 1B . 
     As illustrated in  FIGS. 2A and 2B , the display apparatus  10  according to the present embodiment includes the display panel  12  and a protection sheet  30 . In the present embodiment, the display apparatus  10  further includes an adhesive member  20 , a drive board  14 , a flexible board  16 , a core  24 , and a pantograph unit  26 . As illustrated in  FIGS. 1A and 1B , the display apparatus  10  further includes 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 adhesive member  20 , and the protection sheet  30  and that can draw out the rolled display panel  12  and other components. 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  illustrated in  FIGS. 2A and 2B  includes a display surface  12   a  for displaying an image and a back surface  12   b  on the back side of the display surface  12   a , and the display panel  12  is a flexible panel (in other words, the display panel  12  has flexibility). The display panel  12  is what is called a flexible display panel. The display panel  12  has a rectangular shape with a first direction (that is, Y-axis direction) as the transverse direction and a second direction (that is, X-axis direction) as the longitudinal direction in a state in which the display panel  12  is drawn out from the core  24  as illustrated in  FIG. 2A . With a third direction (that is, Z-axis direction) of the display panel  12  as the thickness direction, the display panel  12  displays an image toward one side in the third direction (that is, positive side in the Z-axis direction). The display panel  12  includes, for example, an organic light emitting diode (OLED) panel and other panels. The thickness direction of the display panel  12  coincides with the thickness direction of the protection sheet  30 . 
     The protection sheet  30  illustrated in  FIGS. 1A to 2B  is a sheet-shaped member attached to the back surface  12   b  of the display panel  12  and formed from woven fabric. The details of the protection sheet  30  will be described later. 
     The adhesive member  20  illustrated in  FIGS. 2A and 2B  is a member that is arranged between the display panel  12  and the protection sheet  30  and that bonds the display panel  12  and the protection sheet  30 . Although the adhesive member  20  is in direct contact with the display panel  12  and the protection sheet  30  in the present embodiment, the adhesive member  20  may be in indirect contact with the display panel  12  and the protection sheet  30 . For example, another member may be placed between the adhesive member  20  and the display panel  12 . The adhesive member  20  may be arranged on the entire back surface  12   b  of the display panel  12  or may be arranged on only part of the back surface  12   b . For example, the adhesive member  20  may be arranged on only the periphery of the back surface  12   b  of the display panel  12 . The adhesive member  20  is not particularly limited as long as the member can bond the display panel  12  and the protection sheet  30 . In the present embodiment, the adhesive member  20  is a double-sided tape with a thickness of 125 μm. 
     The drive board  14  illustrated in  FIGS. 2A and 2B  is a circuit board that drives the display panel  12 , and the drive board  14  is electrically connected to the display panel  12  through the flexible board  16 . 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  and other components move when the core  24  rolls up the display panel  12  and the other components. The drive board  14  is, for example, a printed circuit board (PCB). 
     The flexible board  16  illustrated in  FIGS. 2A and 2B  is a flexible circuit board that electrically connects the display panel  12  and the drive board  14 . The flexible board  16  is connected to the display panel  12  and the drive board  14 , and the flexible board  16  puts together the display panel  12  and the drive board  14 . That is, the display panel  12  and the drive board  14  are linked through the flexible board  16 . The flexible board  16  includes a part not overlapping the display panel  12  as viewed from the third direction in a state in which the flexible board  16  is drawn out from the core  24 . The 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 . 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 core  24  illustrated in  FIGS. 1A to 2B  is a roller to which the drive board  14  and the protection sheet  30  are fixed, the roller being configured to roll up the display panel  12  and the protection sheet  30 . Specifically, the core  24  is a member around which the display panel  12  and the protection sheet  30  are rolled when the display panel  12  and the protection sheet  30  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 second direction as the axial direction, and the front end of the protection sheet  30  in the roll-up direction is fixed to the peripheral surface of the main body  52 . The through portion  54  penetrates the main body  52  in the 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  illustrated in  FIGS. 1A to 2B  includes a 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 protection sheet  30  in the roll-up direction and is attached to the back end of the protection sheet  30  in the roll-up direction. The second support member  58  is fixed to a member (not illustrated) that supports the core  24  in 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 force in directions in which the first support member  56  and the second support member  58  separate from each other. 
     The motor  28  illustrated in  FIGS. 1A and 1B  rotates the core  24 . The motor  28  is rotated in one direction to rotate the core  24  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 components are drawn out from the core  24  (see an arrow E 1  in  FIGS. 1A and 2A ). The motor  28  is rotated in the other direction to rotate the core  24  in the other direction about the axial center  0 . The first support member  56  moves in a direction toward the second support member  58 , and the display panel  12  and other components are rolled up (see an arrow E 2  of  FIGS. 1B and 2B ). 
     [1-2. Configuration of Display Panel and Protection Sheet] 
     Next, the display panel  12  and the protection sheet  30  will be described in detail with reference to  FIGS. 3 and 4 .  FIG. 3  is a schematic plan view illustrating a configuration of the display panel  12  and the protection sheet  30  according to the present embodiment.  FIG. 3  illustrates a plan view of the display surface  12   a  of the display panel  12 .  FIG. 4  is a schematic cross-sectional view illustrating the configuration of the display panel  12  and the protection sheet  30  according to the present embodiment.  FIG. 4  illustrates a cross section along a line IV-IV in  FIG. 3 . Note that the adhesive member  20  is also illustrated in  FIG. 4 . 
     The protection sheet  30  is attached to the back surface  12   b  of the display panel  12 , and this suppresses damage of the display surface  12   a  and the back surface  12   b  caused by contact between the display surface  12   a  and the back surface  12   b  of the display panel  12  when the display panel  12  and other components are rolled up. The protection sheet  30  is formed from woven fabric, and this can suppress the amount of elongation with respect to the tension in the state in which the protection sheet  30  is extended as illustrated in  FIGS. 1A and 2A . In addition, the protection sheet  30  is formed from woven fabric, and the protection sheet  30  can be properly elongated to suppress application of excessive compressive stress to the display panel  12  when the display panel  12  and the protection sheet  30  are rolled up around the core  24 . Moreover, the protection sheet  30  is formed from woven fabric, and a curl is unlikely to remain when the protection sheet  30  is rolled up around the core  24 . The display panel  12  can maintain a high degree of flatness in the state in which the display panel  12  is drawn out from the core  24  as illustrated in  FIG. 2A . Therefore, the attachment of the protection sheet  30  to the display panel  12  can suppress application of excessive tension to the display panel  12  when tension is applied to the protection sheet  30 . This can suppress damage of the display panel  12 . Note that, although the protection sheet  30  is directly attached to the back surface  12   b  of the display panel  12  through the adhesive member  20  in the present embodiment, the protection sheet  30  may be indirectly attached to the back surface  12   b . For example, another member may be placed between the protection sheet  30  and the display panel  12 . 
     The material of the protection sheet  30  is not particularly limited as long as the material is woven fabric. The woven fabric for forming the protection sheet  30  may contain, for example, synthetic fibers (that is, chemical fibers). This can provide woven fabric formed from fibers with desirable characteristics. Examples of the synthetic fibers that can be used include nylon fibers, aramid fibers, poly-p-phenylenebenzobisoxazole (PBO) fibers, and polyester fibers. Particularly, the nylon fibers, the aramid fibers, the PBO fibers, or other fibers can be used to obtain woven fabric with excellent strength, heat resistance, and cold resistance. Further, the nylon fibers, the polyester fibers, or other fibers can be used to obtained woven fabric at low cost. In the present embodiment, the woven fabric for forming the protection sheet  30  contains nylon fibers. The thickness of the woven fabric for forming the protection sheet  30  is not particularly limited. In the present embodiment, the thickness of the woven fabric for forming the protection sheet  30  is 300 μm. 
     Next, a configuration of the woven fabric for forming the protection sheet  30  according to the present embodiment will be described with reference to  FIG. 5 .  FIG. 5  is a schematic diagram illustrating a configuration of fibers contained in the protection sheet  30  according to the present embodiment.  FIG. 5  is an enlarged view of the inside of a dotted frame in  FIG. 3 . A plurality of oblique lines illustrated in  FIG. 5  represent fibers contained in the protection sheet  30 . 
     As illustrated in  FIG. 3 , the display surface  12   a  of the display panel  12  has a rectangular shape. In the present embodiment, angles between longitudinal directions F 1  and F 2  of the fibers contained in the protection sheet  30  and edges of the display surface  12   a  extending in the X-axis direction and the Y-axis direction are equal to or greater than 30° but equal to or smaller than 60° as illustrated in  FIG. 5 . In such a way, the longitudinal directions F 1  and F 2  of the fibers contained in the protection sheet  30  are directions obliquely crossing the edges of the display surface  12   a , and the protection sheet  30  can thus easily be elongated in directions parallel to the edges of the display surface  12   a . For example, the protection sheet  30  can easily be elongated in the Y-axis direction when the display panel  12  is rolled up. As a result, the force of compressing the display panel  12  in the Y-axis direction decreases, and this can reduce the damage of the display panel  12 . The edges of the protection sheet  30  are often cut along the directions parallel to the edges of the display surface  12   a , and the configuration can prevent the longitudinal directions F 1  and F 2  of the fibers at the edges of the protection sheet  30  from becoming parallel to the edges. This can suppress loosening of the fibers at the edges of the protection sheet  30  formed from woven fabric. The angles between the longitudinal directions F 1  and F 2  of the fibers contained in the protection sheet  30  and the edges of the display surface  12   a  extending in the X-axis direction and the Y-axis direction may be equal to or greater than 40° but equal to or smaller than 50°. As a result, the protection sheet  30  can easily be elongated in the direction of either one of the edges of the display surface  12   a  extending in the X-axis direction and the Y-axis direction. This can further suppress loosening of the fibers at the edges of the protection sheet  30 . In the present embodiment, the angles between the longitudinal directions F 1  and F 2  of the fibers contained in the protection sheet  30  and the edges of the display surface  12   a  are 45°. 
     As illustrated in  FIG. 4 , ends of the protection sheet  30  are bent from the back surface  12   b  side to the display surface  12   a  side of the display panel  12 . In other words, the protection sheet  30  includes bent portions  31  arranged on the display surface  12   a  of the display panel  12 . In the present embodiment, the ends of the protection sheet  30  in the X-axis direction are bent to form the bent portions  31 . Note that the regions provided with the bent portions  31  in the display surface  12   a  are regions in which images positioned at the ends of the display surface  12   a  are not displayed. The effect of the bent portions  31  of the protection sheet  30  will be described with reference to  FIG. 6 .  FIG. 6  is a schematic cross-sectional view illustrating the state in which the display panel  12  and the protection sheet  30  according to the present embodiment are rolled up.  FIG. 6  illustrates a cross section parallel to the X-axis direction and the Z-axis direction (that is, thickness direction) of the display panel  12  and the protection sheet  30  in the state in which the display panel  12  and the protection sheet  30  are rolled up (see  FIGS. 1B and 2B ). 
     As illustrated in  FIG. 6 , because the protection sheet  30  according to the present embodiment includes the bent portions  31 , a space is formed between the center of the display surface  12   a  of the display panel  12  in the X-axis direction and the protection sheet  30  placed above the display surface  12   a . This can reduce the contact between the center of the display surface  12   a  in the X-axis direction and the protection sheet  30  even in the state in which the display panel  12  is rolled up. Therefore, the damage of the display surface  12   a  can be reduced. 
     The curvature of the part of the protection sheet  30  on the back surface  12   b  side of the display panel  12  and the curvature of the bent portions  31  are different in the state in which the protection sheet  30  is rolled up, and the amounts of elongation are different. Therefore, the ends of the protection sheet  30  in the X-axis direction may be deflected when the amount of elongation of the protection sheet  30  is uniform. The protection sheet  30  is formed from woven fabric, and it is thus difficult to vary the amount of elongation at each position in the direction parallel to the longitudinal direction of the fibers when the strength of the fibers contained in the woven fabric is high. In the present embodiment, the angles between the longitudinal directions of the fibers contained in the protection sheet  30  and the edges of the display surface  12   a  are equal to or greater than 30° but equal to or smaller than 60°, and therefore, the amount of elongation can be different at each position of the protection sheet  30  in the X-axis direction (that is, direction equal to or greater than 30° but equal to or smaller than 60° with respect to the longitudinal direction of the fibers). This can reduce the deflection at the ends of the protection sheet  30  in the X-axis direction. 
     As described above, the display apparatus  10  according to the present embodiment has a simplified configuration in which the protection sheet  30  is just attached to the display panel  12 , and this can suppress the damage of the flexible display panel  12 . Further, the display apparatus  10  according to the present embodiment has a simplified configuration, and therefore, the weight can be reduced, and the increase in the size of the pantograph unit  26 , the motor  28 , and other components can be suppressed even when the screen is enlarged. 
     Second Embodiment 
     A display apparatus according to a second embodiment will be described. The display apparatus according to the present embodiment is different from the display apparatus  10  according to the first embodiment in that the display apparatus further includes a plate-shaped member between the display panel  12  and the protection sheet  30 . Hereinafter, the configuration of the display apparatus according to the present embodiment that is different from the configuration of the display apparatus  10  according to the first embodiment will mainly be described with reference to  FIGS. 7 and 8 . 
       FIGS. 7 and 8  are a schematic plan view and a schematic cross-sectional view, respectively, illustrating the display panel  12 , a plate-shaped member  40 , and the protection sheet  30  of the display apparatus according to the present embodiment.  FIG. 8  illustrates a cross section along a line VIII-VIII in  FIG. 7 . As illustrated in  FIGS. 7 and 8 , the configuration of the display apparatus according to the present embodiment is similar to the configuration of the display apparatus  10  according to the first embodiment except that the display apparatus includes the plate-shaped member  40 . 
     The plate-shaped member  40  is a member in a plate shape (or a sheet shape) arranged between the display panel  12  and the protection sheet  30 . The configuration of the plate-shaped member  40  is not particularly limited as long as the plate-shaped member  40  is flexible. In the present embodiment, the plate-shaped member  40  is formed from stainless steel. More specifically, the plate-shaped member  40  is a flexible stainless sheet with a thickness of 200 μm. To increase the flexibility of the plate-shaped member  40 , for example, one or more slits or one or more through holes may be formed on the plate-shaped member  40 . Note that an adhesive member that bonds the plate-shaped member  40  and the display panel  12  may be arranged between the plate-shaped member  40  and the display panel  12 . 
     An effect similar to the effect of the display apparatus  10  according to the first embodiment can also be obtained in the display apparatus according to the present embodiment. The display apparatus according to the present embodiment includes the plate-shaped member  40 , and the back surface  12   b  of the display panel  12  can thus be protected. This can suppress the damage of the display panel  12 . The rigidity of the plate-shaped member  40  may be higher than the rigidity of the display panel. In this way, the plate-shaped member  40  can more surely protect the display panel  12 . 
     Modifications, Etc 
     Although the display apparatus according to each embodiment of the present disclosure has been described, the present disclosure is not limited to the individual embodiments. Various modifications of the embodiments conceived by those skilled in the art and modes constructed by combining constituent elements in different embodiments may also be included in the range of one or a plurality of modes of the present disclosure without departing from the scope of the present disclosure. 
     For example, although the display apparatus is rollable in each of the abovementioned embodiments, the display apparatus according to the present disclosure is not limited to the rollable display apparatus. For example, the display apparatus according to the present disclosure may be a bendable display apparatus or a slide display apparatus with variable bending position. Note that the display apparatus may be bent either inward (that is, the display apparatus is bent such that the display surface  12   a  of the display panel  12  is positioned inside) or outward (that is, the display apparatus is bent such that the display surface  12   a  of the display panel  12  is positioned outside). 
     Although the display panel  12  includes the OLED panel in each of the abovementioned embodiments, the display panel  12  is not limited to the panel including the OLED panel. The display panel  12  may be, for example, a quantum dot display panel with quantum dots. 
     Although the protection sheet  30  includes the bent portions  31  in each of the abovementioned embodiments, the protection sheet  30  may not necessarily include the bent portions  31 . 
     Although the angles between the longitudinal directions of the fibers contained in the woven fabric for forming the protection sheet  30  and the edges of the display surface  12   a  are equal to or greater than 30° but equal to or smaller than 60° in each of the abovementioned embodiments, the angles between the longitudinal directions and the edges of the display surface  12   a  may be smaller than 30° or greater than 60°. 
     Although the shape of the display surface  12   a  of the display panel  12  is a rectangle in each of the abovementioned embodiments, the shape of the display surface  12   a  is not limited to the rectangle. The shape of the display surface  12   a  may be, for example, a circle. 
     The present disclosure can widely be used as a display apparatus in various video display apparatuses such as a personal digital assistant, a personal computer, and a television receiver.