Patent Publication Number: US-2023154360-A1

Title: Display panel and flexible display device

Description:
BACKGROUND OF INVENTION 
     Field of Invention 
     The present disclosure relates to the field of display technology, and more particularly, to a display panel and a flexible display device. 
     Description of Prior Art 
     With the rapid development of display technology, both display quality and function of display panels have made a breakthrough. 
     The flexible display device has been widely applied to various fields due to its excellent flexibility and bendability. Compared with traditional screens, the advantages of flexible screens are more obvious. For a flexible display device, to achieve its flexible folding function, the screen itself must have better bending ability and flat performance. Moreover, in order to ensure the folding performance of the entire device, the folding performance of other components matching the screen should also be good. However, conventional flexible display device generally comprises a plurality of supporting backplanes and adhesive layers, making the thickness thicker. The flexible display device with great thickness is not only inconvenient to carry, but also adversely affects the bending of the flexible device. When folding or bending, the dislocation of the glue layers between each of the film layers of the screen is not consistent with the dislocation of each of the film layers, and the tearing problem between the glue layer and the film layer is likely to occur, which may damage the screen and affect the display effect. Moreover, due to the great thickness of the flexible display device, the rigidity and strength of some film layers are too high. When the device is bent to form a water drop-shaped structure, the stress concentrated at the transition point of the water drop is not conducive to enhance the overall performance of the flexible display device. 
     Therefore, it is necessary to provide solutions to the problems in the conventional technology. 
     Technical Problem 
     In summary, the conventional flexible display device with great thickness is inconvenient to carry and use. Moreover, when the device is bent or folded, the layers between each of the film layers are easily torn, and the screen is damaged. Further, the high rigidity and strength of each film layer of the device are not conducive to enhance the overall performance of the flexible display device. 
     SUMMARY OF INVENTION 
     Technical Solution 
     In order to solve the problems described above, the present disclosure provides a display panel and a flexible display device to solve the problems of the conventional flexible display device, which is thick, not portable and not easily used. Moreover, the present disclosure solves the tearing problem of the layers between each of the film layers, and the damage problem of the screen when the device is bent or folded. Moreover, the present disclosure solves the problem that is not conducive to the enhancement of the overall performance of flexible display device due to the higher rigidity and strength of each film layer of the device. 
     To solve the technical problems described above, the technical solutions provided by the embodiments of the present disclosure are shown as follows. 
     According to one aspect of the embodiment of the present disclosure, the present disclosure provides a display panel, comprising:
     a substrate;   a first adhesive layer disposed on the substrate;   a display layer disposed on the first adhesive layer;   wherein the display layer comprises an array layer and a light-emitting device layer disposed on the array layer, the substrate is directly adhered to the array layer through the first adhesive layer, the substrate is used to support the display layer, and the substrate comprises a plurality of grid structures arranged discontinuously; and   wherein two lateral sides of the substrate comprise a plurality of openings arranged at equal intervals, and each of the plurality of the grid structures is filled with an elastic material.   

     According to one embodiment of the present disclosure, the substrate comprises at least one of a bending area, a straight area, and a connection area, and the bending area is connected to the straight area through the connection area. The substrate further comprises a first grid structure and a second grid structure. The first grid structure is disposed on the bending area of the substrate, and the second grid structure is disposed on connection area of the substrate. 
     According to one embodiment of the present disclosure, a shape of the first grid structure is the same as a shape of the second grid structure. 
     According to one embodiment of the present disclosure, a radial length of the first grid structure is greater than a radial length of the second grid structure. 
     According to one embodiment of the present disclosure, a shape of each of the plurality of grid structures comprises a strip shape, a circular shape, an elliptical shape, or a wave shape. The plurality of grid structures are arranged in an array manner. 
     According to the second aspect of the embodiment of the present disclosure, the present disclosure provides a display panel, comprising:
     a substrate;   a first adhesive layer disposed on the substrate;   a display layer disposed on the first adhesive layer;   wherein, the display layer comprises an array layer and a light-emitting device layer disposed on the array layer. The substrate is directly adhered to the array layer through the first adhesive layer. The substrate is used to support the display layer. The substrate comprises a plurality of grid structures discontinuously arranged.   

     According to one embodiment of the present disclosure, the substrate comprises at least one of a bending area, a straight area, and a connection area, and the bending area is connected to the straight area through the connection area. 
     According to one embodiment of the present disclosure, the substrate further comprises a first grid structure and a second grid structure. The first grid structure is disposed on the bending area of the substrate, and the second grid structure is disposed on connection area of the substrate. 
     According to one embodiment of the present disclosure, a shape of the first grid structure is the same as a shape of the second grid structure. 
     According to one embodiment of the present disclosure, a density of the first grid structure is greater than a density of the second grid structure. 
     According to one embodiment of the present disclosure, a radial length of the first grid structure is greater than a radial length of the second grid structure. 
     According to one embodiment of the present disclosure, a density of the plurality of the grid structures in the connection area gradually decreases along the bending area toward the straight area. 
     According to one embodiment of the present disclosure, each of the plurality of the grid structures penetrates the substrate. 
     According to one embodiment of the present disclosure, two lateral sides of the substrate comprise a plurality of openings arranged at equal intervals. 
     According to one embodiment of the present disclosure, a shape of each of the plurality of grid structures comprises a strip shape, a circular shape, an elliptical shape, or a wave shape. The plurality of grid structures are arranged in an array manner. 
     According to one embodiment of the present disclosure, at least one edge of the grid structure in the length direction is an arc shape. 
     According to one embodiment of the present disclosure, the display layer further comprises a touch layer and a polarizer. The touch layer is disposed on the light-emitting device layer, and the polarizer is disposed on the touch layer. 
     According to one embodiment of the present disclosure, the display panel further comprises an elastic layer. The elastic layer is disposed in the same layer as the substrate, and the elastic layer fills each of the plurality of grid structures. 
     According to one embodiment of the present disclosure, a material of the elastic layer comprises silicone resin, metal material or amorphous material. 
     According to the third aspect of the embodiment of the present disclosure, the present disclosure further provides a flexible display device, comprising:
     a substrate, wherein the substrate comprises at least one of a bending area, a straight area, and a connection area, and the bending area is connected to the straight area through the connection area;   a first adhesive layer disposed on the substrate;   a display layer disposed on the first adhesive layer; and   a protective layer disposed on the display layer;   wherein the display layer comprises an array layer and a light-emitting device layer disposed on the array layer. The substrate is directly adhered to the array layer through the first adhesive layer. The bending area and the connection area of the substrate comprise a plurality of grid structures discontinuously arranged. When bending, the grid structures corresponding to the bending area and the connecting area are deformed to bend the flexible display device.   

     Beneficial Effect 
     In summary, the beneficial effect of the embodiments of the present disclosure are shown as follows. 
     The present disclosure provides a display panel and a flexible display device. The substrate of the display panel in the embodiments of the present disclosure is arranged into a bending area, a straight area, and a connection area. Moreover, a plurality of discontinuous grid structures are disposed on the substrate corresponding to the bending area and the connection area. When the display panel is bent or folded, the grid structures may be stretched or compressed due to the grid structures disposed on the bending area and the connection area, so that the panel is completely advanced. Furthermore, the display panel of the embodiments of the present disclosure does not require a backplane layer and a pressure-sensitive adhesive layer, resulting in a light and thin overall structure of the panel. The panel may be easily and conveniently carried when bent and provides excellent overall performance. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a schematic view of each layer of the display panel according to one embodiment of the present disclosure. 
         FIG.  2    is a schematic plan view of the substrate according to one embodiment of the present disclosure. 
         FIG.  3 A  is a schematic bending view of the display panel according to one embodiment of the present disclosure. 
         FIG.  3 B  is a schematic view of the substrate according to one embodiment of the present disclosure. 
         FIG.  4    is a schematic view of the grid structures in the bending area of the substrate according to one embodiment of the present disclosure. 
         FIG.  5    is a schematic view of the first grid structure according to one embodiment of the present disclosure. 
         FIG.  6    is a schematic view of the grid structures in the connection area of the substrate according to one embodiment of the present disclosure. 
         FIG.  7    is a schematic diagram of the grid structures in the connection area of the substrate in another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The descriptions of the following embodiments refer to the attached drawings and illustrate specific embodiments that can be implemented by the present disclosure. 
     The flexible display device may be bent or folded during use to achieve the requirements of diverse function of the flexible display device. The bending or folding performance of the flexible display device is related to various factors, such as the thickness of the display device. The conventional flexible display device is generally thick. When the device is folded or bent, the dislocations between the film layers are not consistent, resulting in many problems, which are not conducive to enhance the overall performance of the display device. 
     In an embodiment of the present disclosure, a display panel and a flexible display device are provided. 
     As shown in  FIG.  1   ,  FIG.  1    is a schematic diagram of each layer of the display panel according to one embodiment of the present disclosure. The display panel comprises a substrate  100 , a first adhesive layer  101 , a display layer  102 , a second adhesive layer  103 , and a protective layer  104 . The first adhesive layer  101  is disposed on the substrate  100 , the display layer  102  is disposed on the substrate  100 , the display layer  102  is adhered to the substrate  100  through the first adhesive layer  101 , and the second adhesive layer  103  is disposed on the display layer  102 . The protective layer  104  is disposed on the display layer  102 , and the protective layer  104  is adhered to the display layer  102  through the second adhesive layer  103 . 
     Specifically, the first adhesive layer  101  and the second adhesive layer  102  may be adhesive layers commonly used in manufacturing the display panels, such as optically clear adhesives (OCA), and the capacitive type OCA or resistive type OCA may be selected according to various requirements of different display panels. 
     After curing and stabilizing the OCA, both the substrate  100  and the display layer  102  are tightly adhered to the first adhesive layer  101 , and the display layer  102  and the protective layer  104  are tightly adhered to the second adhesive layer  103 . When the display panel bends or folds, the first adhesive layer  101  and the second adhesive layer  103  are shifted consistently with other film layers to ensure desirable bending or folding performance of the panel, and effectively prevent the adhesive layer from being misaligned and torn. The materials of the first adhesive layer  101  and the second adhesive layer  103  may be the same. 
     The display layer  102  is a normal display function layer of the display panel. When preparing the display layer  102 , the display layer  102  may be disposed according to a conventional manufacturing process and a conventional film layer. The display layer  102  provides a display screen of the screen and ensures the normal light-emitting display of the panel. 
     Specifically, the display layer  102  comprises an array layer and a light-emitting device layer. The light emitting device layer is disposed on the array layer. In the embodiment of the present disclosure, the array layer of the display layer  102  is directly formed on the substrate  100 , and the array layer is directly adhered to the substrate  100  through the first adhesive layer  101 . That is, no any other film layer, such as a backplane layer, is disposed between the substrate  100  and the array layer. The display layer  102  is directly supported by the substrate  100 , thereby reducing the film structure of the flexible display device and making the flexible display device lighter and thinner. Moreover, the substrate  100  may be a supporting layer, which is used to support the display layer  102  and other film layers thereon. 
     Further, the light-emitting device layer further comprises film layer structures, such as an anode layer, a light-emitting layer, and a cathode layer. These film layer structures may be disposed on the array layer according to the process of a conventional display panel, which is not described in detail any more. 
     The display layer  102  may further comprise a touch layer and a polarizer. The touch layer is disposed on the light-emitting device layer, and the polarizer is disposed on the touch layer, to achieve the display and touch functions of the display panel. 
     Further, the substrate  100  disclosed in the embodiment of the present disclosure is directly adhered to the display layer  102  through the first adhesive layer  101 . The backplane layer and the pressure-sensitive adhesive layer adhered to the backplane layer are no longer disposed. Therefore, the overall thickness of the display panel is effectively reduced, allowing the display panel to become thinner, and the bending performance is improved when the device is bent or folded. 
     The display panel in the embodiment of the present disclosure removes the backplane layer and the pressure-sensitive adhesive layer. When bending, the influence of the backplane layer and the pressure-sensitive adhesive layer on the panel is correspondingly reduced, and the tearing problem of the film layers is effectively improved. 
     As shown in  FIG.  2   ,  FIG.  2    is a schematic plan view of the substrate according to one embodiment of the present disclosure. In order to reduce the thickness of the display panel, enhance the bending or folding performance of the panel, and meanwhile enhance the overall performance of the panel, the substrate  100  of the embodiment of the present disclosure comprises a straight area  201 , a connection area  202 , and a bending are  203 . The straight area  201  is connected to the bending area  203  through the connection area  202 . The substrate  100  may comprise a plurality of different areas described above. 
     Since the substrate  100  is generally a steel plate or a hard material, when the panel is bent or folded, the preferred bending state of the bending portion is a water drop shape or a water drop-like shape. Under this state, the stress level and bending performance of the bending portion of the panel are good. Therefore, when the structure of each film layer and the structure of the substrate of the panel is designed, it is ensured that the shape of the bending portion forms a drop shape or a water drop-like shape after bending. 
     Specifically, the substrate  100  of the embodiment of the present disclosure bends as the display panel bends. The connection area  202  and the bending area  203  are bent. The connection area  202  mainly has a transitional function. After bending, the connection area  202  and the bending area  203  form a water drop shape, and the stress concentrated in the connection area  202  is obvious, especially the stress near the bending area  203  is greatest. 
     In the embodiment of the present disclosure, the connection areas  202  are symmetrically distributed with respect to the bending areas  203 , and are connected to two lateral sides of the straight area  201 . 
     In order to ensure the bending effect, the substrate  100  of the embodiment of the present disclosure comprises a plurality of grid structures arranged discontinuously. A first grid structure is disposed on the bending area  203 , and a second grid structure is disposed on the connection area  202 . The grid structures make the bending of the substrate easier and enhance the flexibility of the substrate. 
     As shown in  FIG.  3 A ,  FIG.  3 A  is a schematic bending view of the display panel according to one embodiment of the present disclosure. The display panel  300  comprises a substrate  301  and other film layers connected to the substrate  301 . The structures of the other film layers are shown in  FIG.  1    and would not be described in detail herein. After bending, the straight area  302  of the substrate  301  remains straight, the bending area  304  is deformed the most, and the connection area  303  is deformed to a certain extent. Meanwhile, when the bending area  304  and the connecting area  303  form a water drop shape or a water drop-like shape, the bending effect of the display panel  300  is the best. 
     Specifically, the shape of the first grid structure and the shape of the second grid structure may be the same or different. In the embodiments of the present disclosure, the first grid structure and the second grid structure with the same shape are used as an example for description. 
     As shown in  FIG.  3 B ,  FIG.  3 B  is a schematic view of the substrate according to one embodiment of the present disclosure. The substrate  30  comprises a straight area  31 , a connection area  32 , and a bending area  33 . The straight area  31  is connected to the bending area  33  through the connection area  32 , and a first grid structure  35  is disposed on the bending area  33 , and a second grid structure  34  is disposed on the connection area  32 . No any grid structure is disposed on the substrate  100  corresponding to the straight area  31 . The shape and disposed manner of the first grid structure  35  and the second grid structure  35  may be the same or different, and specifically, are disposed according to actual products. When the substrate  100  is bent, the deformation area mainly occurs in the connection area  32  and the bending area  33 . The first grid structure  35  and the second grid structure  34  in the area are deformed. For example, the grid structure is elongated or compressed, so that the substrate  100  is more easily bent. 
     As shown in  FIG.  4   ,  FIG.  4    is a schematic view of the grid structures in the bending area of the substrate according to one embodiment of the present disclosure. A plurality of the first grids  401  are discontinuously formed on the hollow substrate  400 . The plurality of the first grids  401  may be arranged in a regular array. For example, the length and width of the substrate in the bending area are disposed at equal intervals. The shape, structure and size of each of the first grids  401  may be disposed to be the same or different. In the present embodiment, in order to simplify the manufacturing process, each of the first grids  401  is disposed the same. 
     Meanwhile, in order to enhance the bending performance of the substrate  400 , when the first grid  401  is hollowed out, the length direction of the first grid  401  is parallel to the bending direction. 
     When the bending area is bent, since the first grid  401  is disposed on the bending area of the substrate  400 , little physical connection material is disposed between the grids, thereby increasing the flexibility of the substrate  400 . When the force applied the substrate  400  is the same as the force applied to a conventional substrate, the substrate  400  may be bent easily, and the bending degree of the substrate  400  is great. For example, when the stretching area  403  is subjected to a bending stretching stress, the grid structures in the stretching area  403  may be deformed in both of the length or width directions, and adjacent grids are connected by the substrate  400 . As the first grid is dense, little physical material is disposed between the connected grids, and it is easier to bend and deform without breaking. Thereby, the bending performance of the substrate  400  is enhanced, and the bending or folding performance of the display panel is enhanced. 
     Specifically, for two rows of first grids  401  adjacent to each other on the substrate  400 , the openings  402  are further disposed on both lateral sides of the substrate  400 . The opening  402  is part of the first grid  401 . The distance between adjacent openings  402  is the same, and the openings  402  make the substrate  400  more flexible. 
     The width of the opening  402  may be the same as the width of the first grid  401  or greater than the width of the first grid  401 . 
     As shown in  FIG.  5   ,  FIG.  5    is a schematic view of the first grid structure according to one embodiment of the present disclosure. The first grid  401  comprises a first area  500  and a second area  501 , the length of the first area  500  is greater than the length of the second area  501 , and the length direction of the first area  500  is close to or parallel to the bending direction of the substrate. The second area  501  may be symmetrically disposed along the first area  500 . Moreover, in the second area  501 , the edge of the second area  501  is configured in an arc shape, such as a circular arc. When stretching, the edge with an arc shape easily deforms in the stretching direction, thereby enhancing the bending performance of the display panel. 
     Further, the first grid  401  may also be configured in a strip shape, a circular shape, an elliptical shape, or a wave shape. When the substrate is bent, the shape described above deforms with the bending of the panel, thereby increasing the bending performance of the substrate. 
     As shown in  FIG.  6   ,  FIG.  6    is a schematic view of the grid structures in the connection area of the substrate according to one embodiment of the present disclosure. The substrate  600  is a substrate in the connection area. The substrate  600  comprises a plurality of second grids  601  and a plurality of second openings  602 . The second grids  601  are disposed discontinuously on the substrate  600 , the second openings  602  are defined by both lateral sides of the substrate  600 , and the second openings  602  are defined at equal intervals. The second grids  601  may be arranged on the substrate  600  in an array. The shape, structure and size of each of the second grids  601  may be the same or different. In the embodiment of the present disclosure, each of the second grids  601  with the same shape is used as an example for description. 
     With reference to the first grid structure in the bending area in  FIG.  4   , the shape of the first grid  401  and the shape of the second grid  601  may be the same, and the specific arrangement of the second grid  601  may be the same as the specific arrangement of the first grid  401 . Since the deformation of the substrate in the connection area is smaller than the deformation of the substrate in the bending area, the length of the second grid  601  may be smaller than the length of the first grid  401  in the length direction. Moreover, the density of the first grid  401  is greater than the density of the second grid  601 . 
     Further, as shown in  FIG.  7   ,  FIG.  7    is a schematic diagram of a grid structure in a substrate connection area according to yet another embodiment of the present disclosure. In the embodiment of the present disclosure, the density of the second grid  701  in different areas of the substrate  700  is different. Since the closer to the bending area, the greater deformation as bending. When the second grid  701  is disposed, the density of the grid gradually decreases from the bending area to the straight area, to effectively comply with the bending of the display panel. 
     Preferably, in the embodiment of the present disclosure, the grid structure may further be filled with an elastic material to form an elastic layer in the entire grid area. When the grid is deformed and restored to its original shape, the elastic layer may allow the grid to restore quickly, thereby enhancing the recovery performance of bending of the display panel. Since the elastic layer is disposed within the grid, the formed elastic layer is in the same layer structure as the substrate. The material of the elastic layer may comprise silicone resin, metal material, or amorphous material. Further, when the elastic layer is disposed, the elastic layer may also be disposed on the entire surface of the substrate and the elastic layer fills the grid area to form an elastic layer on the surface of the substrate. When the substrate is restored after bending, the elastic layer allows the substrate easier to be restored. 
     Moreover, the embodiment of the present disclosure also provides a flexible display device. The flexible display device comprises the display panel of the embodiment of the present disclosure. The film layers of the flexible display device of the embodiment of the present disclosure are reduced, and the thickness of the flexible display device is thinner. When the flexible display device is bent or folded, the flexible display device exhibits desirable overall performance. 
     The display panel and the flexible display device provided by the embodiments of the present disclosure have been described in detail above. The descriptions of the above embodiments are only used to help understand the technical solutions and core concept of the present disclosure. A person ordinarily skilled in the art should understand that the technical solutions described in the foregoing embodiments may be modified, and these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present disclosure.