Patent Publication Number: US-2023152864-A1

Title: Display panel, method for manufacturing the same and display device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims a priority to Chinese Patent Application No. 202010111984.6 filed in China on Feb. 24, 2020, which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to the technical field of display, in particular to a display panel, a method for manufacturing the display panel and a display device. 
     BACKGROUND 
     Along with the development of display technology, users have increasing high demands for a display effect of a display screen, and such technologies as full-screen, narrow-bezel and foldable have become development trends of a flexible display panel. Currently, pad bending is a best solution to achieve a display product with an extremely narrow lower bezel. 
     SUMMARY 
     A display panel is provided, including a display region and a bezel region surrounding the display region. The display region includes at least one first bending region extending in a first direction, and the bezel region includes a second bending region extending in a second direction crossing the first direction, at least one position where an extension line of the at least one first bending region crosses an extension line of the second bending region forms at least one overlapping region, and the display panel further includes a hollowed-out structure formed in the at least one overlapping region and penetrating a display surface and a non-display surface of the display panel. 
     Further, each hollowed-out structure includes a groove structure recessed in a direction from a first edge of the display panel to the overlapping region, the bezel region includes a lower bezel region, the second bending region is arranged at the lower bezel region, and the first edge is an edge toward the lower bezel region and extending in the second direction. 
     Further, each hollowed-out structure includes an opening structure penetrating the display surface and the non-display surface of the display panel. 
     Further, the bezel region includes: a fan-out region connected to the display region, and at least two bonding circuit regions connected to a side of the fan-out region away from the display region. The second bending region is arranged in the fan-out region, the fan-out region includes at least two fan-out sub-regions respectively corresponding to the at least two bonding circuit regions, and the hollowed-out structure is arranged between every two adjacent bonding circuit regions. 
     Further, the at least two bonding circuit regions are bent to the non-display surface of the display panel through the second bending region. 
     Further, a first curvature radius of a bending structure bent and formed by the display panel through the first bending region is R1, a second curvature radius of a bending structure bent and formed by the bezel region through the second bending region is R2, and a half of a side length or a radius of a circumscribed circle of an orthogonal projection of the opening structure in a direction perpendicular to a base substrate is greater than max(R1, R2). 
     Further, the display panel further includes a base substrate including a cutting protection region surrounding the hollowed-out structure, and no wire being arranged in the cutting protection region. 
     Further, a wire is arranged in the fan-out region, and a region between the wire and the hollowed-out structure forms the cutting protection region. 
     Further, the hollowed-out structure includes a linear edge, and a minimum spacing between the linear edge and the wire arranged in a fan-out sub-region closest to the linear edge is greater than or equal to 170 μm, and/or, the hollowed-out structure includes an arc-shaped edge, and a minimum spacing between the arc-shaped edge and the wire arranged in a fan-out sub-region closest to the arc-shaped edge is greater than or equal to 250 μm, and/or, the hollowed-out structure includes a corner-like edge, and a minimum spacing between an vertex on the corner-like edge and the wire arranged in a fan-out sub-region closest to the vertex is greater than or equal to 300 μm. 
     Further, the hollowed-out structure includes an upper edge toward the display region, the second bending region includes an upper boundary toward the display region, and the upper edge of the hollowed-out structure is located between a bending center line of the second bending region and the upper boundary of the second bending region. 
     Further, a first width of the second bending region in the first direction is a, a second width between the upper edge of the hollowed-out structure and the upper boundary of the second bending region in the first direction is h1, and a relationship between the second width h1 and the first width a meets: 0&lt;h1≤a/3. 
     Further, the display panel includes multiple first bending regions, multiple positions where extension lines of the multiple first bending regions cross the extension line of the second bending region form multiple overlapping regions respectively, and the hollowed-out structure is arranged in each overlapping region. 
     Further, the display panel further includes a back-surface protection film arranged on a side where the non-display surface is located, and a hollowed-out pattern corresponding to the hollowed-out structure and arranged at a position corresponding to the hollowed-out structure is arranged in the back-surface protection film. 
     A display device is further provided, including the above-mentioned display panel. 
     A method for manufacturing the above-mentioned display panel is further provided, including: forming at least one first bending region and a second bending region on the display panel; and forming a hollowed-out structure in at least one overlapping region formed in at least one position where an extension line of at least one first bending region crosses an extension line of the second bending region. 
     Further, the forming the hollowed-out structure in at least one overlapping region formed in at least one position where an extension line of at least one first bending region crosses the extension line of the second bending region includes: forming the hollowed-out structure through laser cutting. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a structural view showing a flexible foldable display panel in the related art; 
         FIG.  2    is a front view of a display panel according to one embodiment of the present disclosure; 
         FIG.  3    is a cross-sectional view of the display panel in  FIG.  2    along line D-D; 
         FIG.  4    is another front view of the display panel according to one embodiment of the present disclosure; 
         FIG.  5    is yet another front view of the display panel according to one embodiment of the present disclosure; 
         FIG.  6    is still yet another front view of the display panel according to one embodiment of the present disclosure; and 
         FIG.  7    is still yet another front view of the display panel according to one embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In order to make the objects, the technical solutions and the advantages of the present disclosure more apparent, the present disclosure will be described hereinafter in a clear and complete manner in conjunction with the drawings and embodiments. Obviously, the following embodiments merely relate to a part of, rather than all of, the embodiments of the present disclosure, and based on these embodiments, a person skilled in the art may, without any creative effort, obtain the other embodiments, which also fall within the scope of the present disclosure. 
     Unless otherwise defined, any technical or scientific term used herein shall have the common meaning understood by a person of ordinary skills. Such words as “first” and “second” used in the specification and claims are merely used to differentiate different components rather than to represent any order, number or importance. Similarly, such words as “one” or “one of” are merely used to represent the existence of at least one member, rather than to limit the number thereof. Such words as “include” or “including” intends to indicate that an element or object before the word contains an element or object or equivalents thereof listed after the word, without excluding any other element or object. Such words as “connect/connected to” or “couple/coupled to” may include electrical connection, direct or indirect, rather than to be limited to physical or mechanical connection. Such words as “on”, “under”, “left” and “right” are merely used to represent relative position relationship, and when an absolute position of the object is changed, the relative position relationship will be changed too. 
     Before the detailed description on the display panel and the display device of the embodiments of the present disclosure, it is necessary to describe the related art as follows. 
     As shown in  FIG.  1   , in the related art, a flexible foldable display panel includes a display region AA and a bezel region surrounding the display region AA, and the display region AA includes a bending region for realizing foldable display of a display screen. The bezel region includes: a fan-out region A 2 , a bonding circuit region A 3  and a bezel bending region A 4 , the fan-out region A 2  is located at a lower end of the display region AA, and the bonding circuit region A 3  is located at a lower end of the fan-out region A 2  and configured to provide with a driving integrated chip (IC) chip and a bonding circuit. 
     In order to obtain a narrower lower bezel, a bending region (i.e., a pad bending region) is further provided in a lower bezel region, and the lower bezel region is bent towards a side of the flexible foldable display screen where a non-display surface is located through the bending region, so that the fan-out region and the bonding circuit region in the lower bezel region are located on the side where the non-display surface is located, thereby reducing the lower bezel of the flexible display screen. 
     Generally, in a medium-large-size and high-resolution flexible display panel (such as a laptop, a tablet computer and a vehicle-mounted display screen), there are at least two bonding circuit regions A 3 , and the bezel bending region A 4 , i.e., the pad bending region, is mainly arranged in the fan-out region A 2  between the bonding circuit region A 3  and the display region AA. 
     However, when an extension line of the bending region in the display screen crosses (for example, is perpendicular to) an extension line of the fan-out region, there is an overlapping region (also referred to as a bending overlapping region) between the bending region in the display region of the flexible foldable display screen and the bending region of the lower bezel region. The bending overlapping region is folded twice in a foldable display, so as to greatly increase the bending stress in the bending overlapping region in practical applications, increase the risk of breakage of a wire, and reduce the reliability of the flexible foldable display screen. 
     As shown in  FIG.  1   , the flexible foldable display panel includes a bending region A 5  in the display region, and an extension line of the bending region A 5  extends in a Y direction, and the bending region A 5  is foldable inward/outward at both sides of a center of a screen. The bezel bending region is configured to bend towards the side of the flexible display screen where the non-display surface is located, so that the bonding circuit region is located at the side where the non-display surface is located, thereby to reduce the lower bezel of the flexible display screen. That is, the bonding circuit region A 3  is bent to the back of the screen, so as to obtain a narrower lower bezel. There is an overlapping region (as shown in a dotted circle in  FIG.  1   ) where the extension line of the bending region A 5  crosses an extension line of the bezel bending region A 4 , and a bending overlapping region A 6  is formed. The bending overlapping region A 6  is folded twice in the foldable display, which will greatly increase the bending stress in the bending overlapping region A 6  in practical applications, increase the risk of breaking the wire inside the bezel bending region A 4 , and reduce the reliability of the flexible foldable display screen. 
     In view of the above technical problem, a display panel and a display device are provided in the embodiments of the present disclosure, so as to reduce the bending stress in the overlapping region of the foldable display panel and improve the reliability of the display panel. 
     As shown in  FIG.  2   , a display panel is provided, including a display region AA and a bezel region surrounding the display region AA. The display region AA includes at least one first bending region A 5  extending along a first direction Y, the bezel region includes a second bending region A 4  extending in a second direction X crossing the first direction Y, at least one position where an extension line of the at least one first bending region A 5  crosses an extension line of the second bending region A 4  forms at least one overlapping region, and the display panel further includes a hollowed-out structure  100  formed in the at least one overlapping region and penetrating a display surface and a non-display surface of the display panel. 
     In the above-mentioned solution, the at least one overlapping region formed in the at least one position where the extension line of the at least one first bending region A 5  crosses the extension line of the second bending region A 4  is designed as the hollowed-out structure  100 , so as to prevent the overlapping region from being folded twice or more, and reduce the bending stress in the overlapping region, thereby to improve the reliability of the display panel. 
     The display panel of the embodiments of the present disclosure is described in more details below. 
     In an illustrative embodiment, as shown in  FIG.  2   , each hollowed-out structure  100  includes a groove structure recessed in a direction from a first edge of the display panel to the overlapping region, the bezel region includes a lower bezel region, the second bending region is arranged at the lower bezel region, and the first edge is an edge toward the lower bezel region and extending in the second direction. 
     In the above-mentioned solution, the position where the extension line of the at least one first bending region A 5  in the display region AA crosses the extension line of the second bending region A 4  in the bezel region is cut, for example, through laser cutting, so as form the groove structure used as the hollowed-out structure  100 . An orthogonal projection of the groove structure in a direction perpendicular to a base substrate may be trapezoidal-shaped, triangular-shaped, rectangular-shaped, ∩-shaped, semicircular-shaped, etc. As shown in  FIG.  1   , illustratively, the orthogonal projection of the groove structure in the direction perpendicular to the base substrate is trapezoidal-shaped. Considering the bending stress when the display panel is folded in practical applications, the groove structure is designed to be trapezoidal-shaped, so as to reduce the bending stress in the overlapping region in a better manner. 
     In another illustrative embodiment, as shown in  FIGS.  6  and  7   , the hollowed-out structure  100  includes an opening structure penetrating the display surface and non-display surface of the display panel. That is to say, the hollowed-out structure  100  may also be formed in an opening manner, as shown in  FIGS.  6  and  7   , a specific shape of the opening structure is not limited, and the orthogonal projection of the opening structure in the direction perpendicular to the base substrate may be circular-shaped, square-shaped, trapezoidal-shaped, triangular-shaped, rectangular-shaped, or any special-shaped structure having a boundary which is formed by changing a boundary of above-mentioned shape into arc-shaped, etc. 
     In addition, it should be appreciated that a first curvature radius of a bending structure bent and formed by the display panel through the first bending region A 5  is R1, a second curvature radius of a bending structure bent and formed by the bezel region through the second bending region A 4  is R2, and a half of a side length or a radius of a circumscribed circle of an orthogonal projection of the opening structure in the direction perpendicular to the base substrate is greater than max(R1, R2). 
     For example, when the orthogonal projection of the opening structure in the direction perpendicular to the base substrate is circular-shaped, the circumscribed circle is a circle in orthogonal projection, and a radius of the opening structure is greater than max(R1, R2). When the orthogonal projection of the opening structure in the direction perpendicular to the base substrate is square-shaped, a half of a side length thereof is greater than max(R1, R2). When the orthogonal projection of the opening structure in the direction perpendicular to the base substrate is triangular-shaped, square-shaped, trapezoidal-shaped, etc. a radius of a circumscribed circle thereof is greater than max(R1, R2). 
     In some embodiments, the side length or the radius of the circumscribed circle of the orthogonal projection of the opening structure in the direction perpendicular to the base substrate may not be too large, and the following cutting protection region may be ensured to be sufficiently large, so as to reduce the adverse effects of debris and thermal effects during laser cutting on a metal wire. 
     In an exemplary embodiment, as shown in  FIG.  2   , the bezel region includes a lower bezel region A 1 , the second bending region A 4  is located at the lower bezel region A 1 , the lower bezel region A 1  includes: a fan-out region A 2  connected to the display region AA, and at least two bonding circuit regions A 3  connected to a side of the fan-out region A 2  away from the display region AA The second bending region A 4  is arranged in the fan-out region A 2 , the fan-out region includes at least two fan-out sub-regions respectively corresponding to the at least two bonding circuit regions A 3 , and the hollowed-out structure  100  is located between two adjacent bonding circuit regions A 3 . 
     The at least two bonding circuit regions are bent to the non-display surface of the display panel through the second bending region. 
     When the hollowed-out structure  100  is arranged between two adjacent bonding circuit regions A 3 , and the at least two bonding circuit regions may be bent to the non-display surface of the display panel separately, so as to improve the bending effect of each bonding circuit region. 
     In addition, a wire in the fan-out region A 2  are arranged in such a manner as to avoid the hollowed-out structure  100 , so as to prevent the wire from being adversely affected when the hollowed-out structure  100  is formed, for example, through laser cutting. 
     Further, in the embodiment, illustratively, as shown in  FIG.  2   , the display panel  10  includes a base substrate including a cutting protection region surrounding the hollowed-out structure  100 , and no wire is arranged in the cutting protection region. 
     In the above-mentioned solution, the cutting protection region may be arranged on an edge side of the fan-out region in the bezel region toward the groove or opening structure, so as to reduce the adverse effects of the debris and thermal effects during laser cutting on the metal wire and improve the product yield. 
     In addition, the wire is arranged in the fan-out region A 2 , and a region between the wire and the hollowed-out structure  100  forms the cutting protection region. In the above-mentioned solution, when the wire is arranged, there is a certain spacing between the wire and a cutting line of the groove or opening structure, so as to further prevent the wire from being cut and damaged thereby to avoid the breakage of wire. 
     For the hollowed-out structure  100  of different shapes, optional value ranges of the spacing between the wire and the groove structure are provided below, so as to prevent the metal wire from being cut and damaged during laser cutting and avoid a heat-affected zone during laser cutting. When the hollowed-out structure  100  includes a linear edge, a minimum spacing between the linear edge and the wire arranged in the fan-out sub-region closest to the linear edge is greater than or equal to 170 μm. When the hollowed-out structure  100  includes an arc-shaped edge, a minimum spacing between the arc-shaped edge and the wire arranged in the fan-out sub-region closest to the arc-shaped edge is greater than or equal to 250 μm. When the hollowed-out structure  100  includes a corner-like edge, a minimum spacing between a vertex on the corner-like edge and the wire arranged in the fan-out sub-region closest to the vertex is greater than or equal to 300 μm. 
     For example, the orthogonal projection of the hollowed-out structure  100  in the direction perpendicular to the base substrate is trapezoidal-shaped as shown in  FIG.  2   , and the minimum spacing between an edge T 1  of the trapezoid and the wire arranged in the fan-out sub-region closest to the edge T 1  is greater than or equal to 170 μm. 
     When the hollowed-out structure  100  includes the arc-shaped edge, the minimum spacing between any point on the arc-shaped edge and the wire arranged in the fan-out sub-region closest to the point is greater than or equal to 250 μm. 
     In some embodiments, the corner-like edge is a structure formed through two edges of the hollowed-out structure crossing each other. For example, the orthogonal projection of the hollowed-out structure  100  in the direction perpendicular to the base substrate is trapezoidal-shaped shown in  FIG.  2   , and a structure formed through the edge T 1  crossing an edge T 3  of a trapezoid is the corner-like edge. 
     When the hollowed-out structure  100  includes the corner-like edge, the minimum spacing between the vertex on the corner-like edge and the wire arranged in the fan-out sub-region closest to the vertex is greater than or equal to 300 μm. 
     It should be appreciated that a spacing between the wire and the hollowed-out structure  100  may be rationally designed according to practical applications, and the above is merely an exemplary embodiment and it is not particularly defined herein. 
     Further, in the embodiment, illustratively, as shown in  FIG.  2   , the hollowed-out structure  100  includes an upper edge toward the display region AA, the second bending region A 4  includes an upper boundary toward the display region AA; and the upper edge of the hollowed-out structure  100  is located between a bending center line of the second bending region A 4  and the upper boundary of the second bending region A 4 . 
     In the above-mentioned scheme,  FIG.  3    is a schematic diagram of a cross-sectional lamination structure of the fan-out region. As shown in  FIG.  3   , the fan-out region A 2  includes, from bottom to top, a metal layer (a metal wire, etc.), an organic protection layer  101 , an inorganic layer  102  and a polyimide (PI) layer  103 , the inorganic layer  102  above the PI layer  103  in the second bending region A 4  is etched and removed through exposure to form a trenched structure, and the second bending region A 4  (as shown in  FIGS.  2  and  3   ) is formed by filling such an organic material as PI in the trenched structure, so as to mitigate and reduce the local stress in the second bending region A 4  during bending. A laser cutting line c 1  of the groove structure between two adjacent bonding circuit regions in the lower bezel region A 1  in an X direction is in a region H 1  above the center line c 2  of the second bending region A 4  (a PI filling region). 
     Specifically, a first width of the second bending region A 4  in the first direction Y is a, a second width between the upper edge of the hollowed-out structure  100  and the upper boundary of the second bending region A 4  in the first direction Y is h1, and a relationship between the second width h1 and the first width a meets: 0&lt;h1≤a/3. 
     Further, in some embodiments, the display panel includes multiple first bending regions A 5 . Multiple positions where extension lines of the multiple first bending regions cross the extension line of the second bending region form multiple overlapping regions respectively, and the hollowed-out structure is arranged in each overlapping region. 
     In the above-mentioned solution, for a foldable display panel having a larger size or a higher resolution and a narrow lower bezel, in a case where the first bending region A 5  is formed at only a position between two adjacent bonding circuit regions A 3  on both sides of the center line of the display panel respectively, then the groove structure or the opening structure is only formed between the two adjacent bonding circuit regions A 3  on both sides of the center line of the display panel respectively through cutting, and the hollowed-out structure may not be arranged between other adjacent bonding circuit regions A 3 , as shown in  FIG.  5   . Alternatively, in a case where the first bending region A 5  is formed between every two adjacent bonding circuit regions A 3 , the groove structure or the opening structure is formed between every two adjacent bonding circuit regions A 3  through cutting, as shown in  FIG.  4   . For a display panel which needs to be bent more than once, for example, a Z-shaped flexible foldable display panel (as shown in  FIG.  4   ), the groove structure or the opening structure may be formed between every two adjacent bonding circuit regions A 3 , so as to prevent the overlapping region of the display panel from being folded twice or more, thereby to improve the reliability of the display panel. 
     In addition, in an illustrative embodiment, the display panel further includes a back-surface protection film arranged on a side where the non-display surface is located, and a hollowed-out pattern, such as a protection film groove structure, corresponding to the hollowed-out structure  100  and arranged at a position corresponding to the hollowed-out structure  100  is arranged in the back-surface protection film. Optionally, an orthogonal projection of the protection film groove structure onto the flexible display screen is entirely within an orthogonal projection of the protection film onto the flexible display screen. 
     In the above-mentioned solution, the hollowed-out pattern is arranged in the back-surface protection film on the non-display surface of the display panel and arranged at the position corresponding to the hollowed-out structure  100 , and a size of the hollowed-out pattern of the back-surface protection film is slightly less than or equal to a size of the hollowed-out structure  100  of the display panel, so as to prevent the back-surface protection film from being folded more than once in a region corresponding to the orthogonal projection of the overlapping region of the display panel. 
     In addition, a method for manufacturing the above-mentioned display panel is further provided in the embodiments of the present disclosure, including the following steps. 
     Step S 1 , forming at least one first bending region and a second bending region on the display panel. 
     Step S 2 , forming a hollowed-out structure in at least one overlapping region formed in at least one position where an extension line of at least one first bending region crosses an extension line of the second bending region. 
     Illustratively, the forming the hollowed-out structure in at least one overlapping region formed in at least one position where an extension line of at least one first bending region crosses the extension line of the second bending region includes: forming the hollowed-out structure through laser cutting. 
     It should be appreciated that, in practical applications, the hollowed-out structure may be formed in other manners and is not limited to through laser cutting. 
     In addition, a display device including the above-mentioned display panel is further provided in the embodiments of the present disclosure. 
     Some descriptions will be given as follows. 
     (1) The drawings merely relate to structures involved in the embodiments of the present disclosure, and the other structures may refer to those known in the art. 
     (2) For clarification, in the drawings for describing the embodiments of the present disclosure, a thickness of a layer or region is zoomed out or in, i.e., these drawings are not provided in accordance with an actual scale. It should be appreciated that, in the case that such an element as layer, film, region or substrate is arranged “on” or “under” another element, it may be directly arranged “on” or “under” the other element, or an intermediate element may be arranged therebetween. 
     (3) In the case of no conflict, the embodiments of the present disclosure and the features therein may be combined to acquire new embodiments. 
     The above embodiments are merely for illustrative purposes, but shall not be construed as limiting the scope of the present disclosure. The scope of the present disclosure shall be subject to the scope defined by the appended claims.