Patent Publication Number: US-2022238850-A1

Title: Display panels and display devices

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation to international patent application PCT/CN2021/081832, filed on Mar. 19, 2021, which claims priority to Chinese Patent Application No. 202010365099.0, filed on Apr. 30, 2020, the contents of both applications are hereby incorporated by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to the field of display technology. 
     BACKGROUND 
     Requirements for various properties of display modules are growing with scientific and technological progress and continuous advancement of the information age. Luminance uniformity of a display module is very important. However, non-uniformity of luminance or “mura” may occur in a local area of the images displayed by the display module. Mura refers to dark spots and the like caused by the non-uniform luminance on the display module. 
     SUMMARY 
     The present disclosure relates to the field of display technology as it relates to display panels and display devices. 
     In view of this, there is a need to provide a display panel and a display device. 
     A display panel includes a display module, at least one color layer, and a light absorption layer. The display module has a display face and a non-display face opposite to the display face. The at least one color layer is disposed at a side of the display module away from the display face. The light absorption layer is disposed at a side of the at least one color layer away from the display module. A first through hole is defined in the light absorption layer. A second through hole is defined in the at least one color layer. The second through hole is located corresponding to and in communication with the first through hole. The first through hole and the second through hole are located corresponding to an external functional module. 
     A display device includes the above-described display panel. 
     In the related art, the light absorption layer defines a first through hole located corresponding to the external functional module, and no light absorption material is located corresponding to the external functional module. As a result, the difference between quantities of light respectively reflected from the region of the first through hole and the other region of the light absorption layer back to the display module may be relatively large, and the images displayed by the display module may be brighter in the region corresponding to the first through hole. In contrast, in the present disclosure, due to the arrangement of the color layer, the light emitted by the display module and the light entered into the display module from the outside can firstly arrive at the color layer and be reflected back to the display module by the color layer before the light arrives at the light absorption layer and is adsorbed by the light absorption layer. Therefore, light can be reflected back to the display module from both the region corresponding to the first through hole and the region corresponding to the outside of the first through hole, thereby reducing the light output difference of the display module between the region corresponding to the first through hole and the other region, and thus reducing the mura problem on the display panel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded sectional view of a display panel according to an embodiment of the present disclosure. 
         FIG. 2  is a schematic sectional view of a partial structure of a composite layer of the display panel according to an embodiment of the present disclosure. 
         FIG. 3  is a schematic sectional view of a partial structure of the composite layer of the display panel according to another embodiment of the present disclosure. 
         FIG. 4  is a schematic sectional view of a partial structure of the composite layer of the display panel according to another embodiment of the present disclosure. 
         FIG. 5  is a schematic sectional view of a partial structure of the composite layer of the display panel according to another embodiment of the present disclosure. 
         FIG. 6  is a schematic sectional view of a partial structure of the composite layer of the display panel according to another embodiment of the present disclosure. 
         FIG. 7  is a schematic sectional view of a partial structure of the composite layer of the display panel according to another embodiment of the present disclosure. 
         FIG. 8  is a schematic sectional view of a partial structure of the composite layer of the display panel according to another embodiment of the present disclosure. 
         FIG. 9  is a schematic sectional view of a partial structure of the composite layer of the display panel according to another embodiment of the present disclosure. 
         FIG. 10  is a schematic sectional view of a partial structure of the composite layer of the display panel according to another embodiment of the present disclosure. 
         FIG. 11  is an exploded sectional view of the display panel according to another embodiment of the present disclosure. 
         FIG. 12  is an exploded sectional view of a display device according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure is thoroughly described with reference to the relevant accompanying drawings. The accompanying drawings show embodiments of the present disclosure. However, the present disclosure may be implemented in various forms, and are not limited to the embodiments described herein. Rather, the embodiments described herein are intended to make the present disclosure more clearly and thoroughly understood. 
     Mura is easy to occur in the images displayed by a display module, which causes a poor user experience. 
     The user&#39;s requirement for the screen-to-body ratio is increasing with the rapid development of electronic equipment. Full-screen display technology receives more and more attention in the industry. To realize the full-screen display, an under-screen fingerprint technology comes into being, which accomplishes a fingerprint identification and screen-unlocking process by using a fingerprint identification sensor disposed under the display module. In electronic equipment such as a display device, a composite layer is set underneath the display module for heat dissipation, electromagnetic shielding, and external force buffering of the display module and for preventing unwanted light leakage of the display device. To install the optical fingerprint identification sensor, a through hole is required to be provided in the composite layer, and the optical fingerprint identification sensor is disposed in the through hole. 
     The composite layer includes a light absorption layer for absorbing light entered from the side where the display module is located to prevent unwanted light leakage of the display device. The light to be absorbed includes the light emitted by the display module and the light incident from the outside. However, since the through hole is defined in the composite layer, which divides the composite layer into a hole region and a hole-free region, the light arrived at the hole-free region of the composite layer will be absorbed by the light absorption layer, whereas the light arrived at the hole region of the composite layer will be reflected back to the display module and emits outside because no light absorption material is disposed in the hole region of the composite layer. As a result, the light output difference between the regions of the display module respectively aligned with the hole region and the hole-free region of the composite layer will be relatively large, which causes the non-uniformity of luminance, or the mura problem, in the images displayed by the display module. For example, the images will be brighter in the region corresponding to the through hole defined in the composite layer. 
     The embodiments of the present disclosure provide a display panel and a display device to solve the above problem.  FIG. 1  is an exploded sectional view of a display panel  100  according to an embodiment of the present disclosure. 
     Referring to  FIG. 1 , the display panel  100  includes a display module  10 . The display module  10  has a display face  11  and a non-display face  12  opposite to each other in a first direction. The first direction is a thickness direction of the display panel  100 , which is the up-down direction in  FIG. 1 . The display module  10  may be a flexible display module. The flexible display module may be an organic light-emitting display module such as a flexible organic light-emitting diode (OLED) display module, or other bendable flexible display module, such as a Micro LED flexible display module or a quantum dot flexible display module, which is not specifically limited herein. 
     In an embodiment, the display panel  100  includes the display module  10  and a composite layer  30 . The composite layer  30  includes a light absorption layer  32  and at least one color layer  33 . The at least one color layer  33  is disposed between the light absorption layer  32  and the display module  10 . A through hole  31  is defined in and extends through the composite layer  30  in the first direction. The through hole  31  is located corresponding to an external functional module such as an optical fingerprint identification sensor. When the user&#39;s finger is put onto the display module  10 , the optical fingerprint identification sensor acquires a fingerprint image based on the specular reflection principle. The fingerprint image is converted into digital data by a digital signal processor. Then, the digital data is compared with digital data of the fingerprint, recorded in a fingerprint database by a microcontroller, in order to accomplish the fingerprint identification. In the composite layer  30 , the region provided with through hole  31  is defined as a hole region, while the region provided with no through hole  31  is defined as a hole-free region. Through hole  31  includes a first through hole  321  defined in the light absorption layer  32  and a second through hole  331  defined in the at least one color layer  33 . The second through hole  331  is located corresponding to (for example, aligned with), and in communication with, the first through hole  321 . In this way, the light emitted by the display module  10 , or the light entered into the display module  10  from the outside, may firstly arrive at the at least one color layer  33  and be reflected back to the display module  10  by the at least one color layer  33  before the light arrives at the light absorption layer  32  and is adsorbed by the light absorption layer  32 , as shown in  FIG. 1  with the dotted lines having arrows and indicating the path of the light. Therefore, due to the presence of the color layer  33 , light may be reflected back to the display module  10  both in the region of the display module  10  aligned with the hole region of the composite layer  30  and in the region of the display module  10  aligned with the hole-free region of the composite layer  30 , thereby reducing the light output difference between the regions of the display module  10  respectively aligned with the hole region and the hole-free region of the composite layer  30  and reducing the mura problem on the display panel. 
     The size and shape of through hole  31  is not limited as long as a projection of the through hole  31  on the display module  10  is at least partially overlapped with a projection of the functional module on the display module  10 . For example, the through hole  31  can have a cross-sectional shape of circular, oval, or rhombus. A cross-sectional size of the through hole  31  can be larger than a cross-sectional size of the functional module. Alternatively, the cross-sectional size of the through hole  31  may be smaller than a cross-sectional size of a part of the functional module. Alternatively, the cross-sectional size of the through hole  31  may be equal to the cross-sectional size of the functional module. When the cross-sectional size of the through hole  31  is smaller than the cross-sectional size of a part of the functional module, the part of the functional module can be disposed outside the through hole  31 , and the remaining part of the functional module may be disposed in the through hole  31 . 
     A cross-sectional size of the first through hole  321  can be equal to a cross-sectional size of the second through hole  331 , so that the projections of the first through hole  321  and the second through hole  331  on the display module  10  coincide with each other, and all of the light incident into the through hole  31  can be incident into the functional module. 
     In another embodiment, the cross-sectional sizes of the first through hole  321  and the second through hole  331  may be different, and the projection of one of the first through hole  321  and the second through hole  331  on the display module  10  fall within the projection of the other one of the first through hole  321  and the second through hole  331  on the display module  10 , so that the incident light cannot be blocked. 
     In an embodiment, the light absorption layer  32  is made of a black foam, which is a foamed plastic material having resilience, so that the light absorption layer  32  can not only absorb light, but also provide the buffer function when an external force is exerted onto the display module  10 . 
     In another embodiment, the light absorption layer  32  may be made of other materials such as a dark ink. The material of the light absorption layer  32  is not limited as long as the light absorption layer  32  can absorb light and does not interfere the normal working of the display panel  100 . 
     In an embodiment, a reflectivity of the at least one color layer  33  is larger than or equal to 50%, so that more light can be reflected back to the display module  10 , and the intensities of the reflected light received by the regions of the display module  10  respectively aligned with the hole region and the hole-free region of the composite layer  30  can tend to be identical, thereby reducing the light output difference between the regions of the display module  10  respectively aligned with the hole region and the hole-free region of the composite layer  30  and reducing the mura problem on the display panel. The term “reflectivity” used herein refers to a ratio of quantity of light reflected by a surface of an object to quantity of light received by the surface of the object. It should be understood that the at least one color layer  33  is not necessary to be a portion of the composite layer  30 . 
     In some other embodiments, the display panel  100  may further include a support layer  20  disposed between the composite layer  30  and the display module  10  to support and protect the display module  10 . The support layer  20  can include a first substrate  21  which can be made of, for example, polyethylene terephthalate (PET, also called polyethylene glycol terephthalate, which is a thermoplastic polyester and is a polycondensate of terephthalic acid and ethylene glycol or formed from a saturated polyester). The at least one color layer  33  is included in the support layer  20 . That is, the at least one color layer  33  is a portion of the support layer  20  in this embodiment. In this case, the second through hole  331  is not required to be provided in the at least one color layer  33 . 
     It should be noted that when the at least one color layer  33  is a portion of the support layer  20  and no through hole is provided in the at least one color layer  33 , in order to ensure the normal working of the optical fingerprint sensor, the at least one color layer  33  has a light transmittance which allows a part of light to pass therethrough, but does not reflect all of light back to the display module  10 . The light transmittance of the at least one color layer  33  from the side facing the display module  10  to the side facing the light absorption layer  32  can be larger than or equal to 60%. The term “light transmittance” used herein indicates the ability of light to pass through an object and refers to a percentage of a flux of light passed through an object (such as a transparent object or a semi-transparent object) in the total flux of incident light. 
     It should be understood that in some embodiments, the at least one color layer  33  is a portion of the composite layer  30 . In some embodiments, the at least one color layer  33  is a portion of the support layer  20 . In other embodiments, the at least one color layer  33  can be a layer separated from the composite layer  30  and the support layer  20 . This is not specifically limited herein. In the case that the at least one color layer  33  is a layer separated from the composite layer  30  and the support layer  20 , the second through hole  331  can be defined in the at least one color layer  33 , or a light transmittance of the region of the at least one color layer  33  located corresponding to (for example, aligned with) the functional module region is larger than or equal to 60%, as appropriate. 
     The composite layer  30  can further include an adhesive layer  40  to bond the layers of the composite layer  30  together. A material of the adhesive layer  40  can be, for example, double faced adhesive material, liquid adhesive material, etc. 
     In an embodiment, the at least one color layer  33  includes at least two color layers to enhance the reflection effect. The at least one color layer  33  can include at least two color layers stacked with each other. It should be noted that when the at least one color layer  33  includes at least two color layers stacked with each other, the least two color layers can be directly stacked with each other, or indirectly stacked with each other via other layer structure(s). For example, when the at least one color layer  33  includes a first color layer and a second color layer stacked with each other, the first color layer and the second color layer can be directly stacked with each other, or an additional layer can be disposed between the first color layer and the second color layer so that the first color layer and the second color layer are indirectly stacked with each other via the additional layer. When the at least one color layer  33  includes a first color layer, a second color layer, and a third color layer stacked with each other, the first color layer, the second color layer, and the third color layer can be directly stacked with each other, or an additional layer can be disposed between the first color layer and the second color layer and/or between the second color layer and the third color layer so that the first color layer, the second color layer, and the third color layer are indirectly stacked with each other via the additional layer(s). 
       FIG. 2  is a schematic sectional view of a partial structure of a composite layer of a display panel according to another embodiment of the present disclosure.  FIG. 3  is a schematic sectional view of a partial structure of a composite layer of a display panel according to yet another embodiment of the present disclosure.  FIG. 4  is a schematic sectional view of a partial structure of a composite layer of a display panel according to yet another embodiment of the present disclosure. 
     Referring to  FIG. 2 , the composite layer  30  can further include a second substrate  34  which is transparent and can be made of, for example, PET. The at least one color layer  33  is stacked with the second substrate  34 . A third through hole  341  is defined in the second substrate  34 . The third through hole  341  is located corresponding to (for example, aligned with) and in communication with the first through hole  321  and the second through hole  331 . The third through hole  341  is located corresponding to the external functional module. The at least one color layer  33  can be formed on the second substrate  34  by a printing or coating method. In this case, the second substrate  34  is used as a base for arranging the at least one color layer  33 , which facilitates the formation of the least one color layer  33 . It should be understood that in some other embodiments, the composite layer  30  can be provided with no second substrate  34 , and the at least one color layer  33  can be directly formed on the light absorption layer  32  by a printing or coating method. This is not specifically limited herein. 
     In an embodiment, the at least one color layer  33  can include at least two color layers stacked with each other. The at least two color layers can be respectively disposed at two opposite sides of the second substrate  34  in the first direction. Alternatively, the at least two color layers can be disposed at one side of the second substrate  34  in the first direction. This is not specifically limited herein. 
     The at least one color layer  33  can include an orange layer  332 , a white layer  333 , a gray layer  334 , or any combination thereof. It should be understood that the at least one color layer  33  can include a color layer with another color in some other embodiments. This is not specifically limited herein. 
     In an embodiment, the at least one color layer  33  includes an orange layer  332  disposed at a side of the second substrate  34  facing the light absorption layer  32 , as shown in  FIG. 2, 3 , or  4 . The at least one color layer  33  can include one orange layer  332  or at least two orange layers  332 . Referring to  FIG. 3 , the at least one color layer  33  including five orange layers  332  stacked with each other is shown. It should be understood that the number of the orange layers  332  is not limited in the present disclosure. 
       FIG. 5  is a schematic sectional view of a partial structure of a composite layer of a display panel according to another embodiment of the present disclosure.  FIG. 6  is a schematic sectional view of a partial structure of a composite layer of a display panel according to yet another embodiment of the present disclosure. 
     Referring to  FIG. 5 , in this embodiment, the at least one color layer  33  includes orange layers  332  disposed at a side of the second substrate  34  facing away from the light absorption layer  32 . The at least one color layer  33  includes at least two orange layers  332  stacked with each other to ensure the relatively high intensity of the light reflected by the at least one color layer  33 . 
     Referring to  FIG. 6 , in this embodiment, the at least one color layer  33  further includes a white layer  333  disposed between the orange layer  332  and the second substrate  34 , so that the incident light passing through the orange layer  332  can be reflected back to the display module  10  by the white layer  333 , thereby reducing the light output difference between the regions of the display module  10  respectively aligned with the hole region and the hole-free region of the composite layer  30  and reducing the mura problem on the display panel. 
       FIG. 7  is a schematic sectional view of a partial structure of a composite layer of a display panel according to yet another embodiment of the present disclosure. 
     Referring to  FIG. 7 , in this embodiment, the at least one color layer  33  includes orange layers  332 . The second substrate  34  is provided with the orange layers  332  at two opposite sides of the second substrate  34  in the first direction. The numbers of the orange layers  332  disposed at two opposite sides of the second substrate  34  can be equal to each other, for example, can be one, two, or more. 
     In an embodiment, two orange layers  332  are disposed at each of the two opposite sides of the second substrate  34 , so that not only can the relatively high intensity of the light reflected by the at least one color layer  33  be ensured, but the thickness of the display panel can be relatively small. 
     Referring to  FIGS. 4 to 6 , the at least one color layer  33  can further include a white layer  333  disposed between the orange layers  332  and the light absorption layer  32 , so that the light passing through the orange layer  332  can be reflected back to the display module  10  by the white layer  333 , thereby ensuring the reflection effect of the at least one color layer  33 . The at least one color layer  33  can include one white layer  333 . 
       FIG. 8  is a schematic sectional view of a partial structure of a composite layer of a display panel according to yet another embodiment of the present disclosure. Referring to  FIG. 8 , the at least one color layer  33  can include a gray layer  334 . The gray layer  334  can be disposed at a side of the second substrate  34  facing the light absorption layer  32 , a side of the second substrate  34  facing away from the light absorption layer  32 , or each of the two sides of the second substrate  34 . 
     In an embodiment, the gray layer  334  has a blackness of 50% of the blackness of pure black. In this way, a part of the incident light can be reflected back to the display module  10  by the gray layer  334  to reduce the mura problem when the display panel emits light. At the same time, another part of the incident light can be absorbed by the gray layer  334 , to avoid the situation where the brightness of the hole-free region of the display panel is larger than that of the hole region of the display panel caused by too much reflected light. 
     It should be understood that the above-described orange layer  332 , gray layer  334 , and white layer  333  can be arbitrarily combined. A thickness of the at least one color layer  33  can be smaller than or equal to 10 μm. 
     Referring back to  FIG. 2 , in an embodiment, the at least one layer  33  may be not sufficient to reflect all incident light back to the display module. In view of this, the composite layer  30  can further include a metal layer  35 . A fourth through hole  351  can be defined in the metal layer  35 . The fourth through hole  351  can be located corresponding to (for example, aligned with) and in communication with the first through hole  321  and the second through hole  331 . The fourth through hole  351 , the third through hole  341 , the second through hole  331 , and the first through hole  321  can collectively form the through hole  31  in the composite layer  30 . The metal layer  35  can be disposed between the light absorption layer  32  and the at least one color layer  33 . As such, the part of incident light passing through the at least one color layer  33  can be reflected back to the at least one color layer  33  and thus back to the display module  10  by the metal layer  35 , thus ensuring the reflection effect. Moreover, the metal layer  35  can enhance the strength of the display panel to prevent the break of the display panel. In an embodiment, the least one color layer  33  includes a plurality of orange layers  332  printed or coated on the side of the second substrate  34  facing the light absorption layer  32 . The metal layer  35  is coated or deposited on a side of the plurality of orange layers  332  facing the light absorption layer  32 . The metal layer  35  can be made of copper foil or other metal materials, which is not specifically limited herein. 
       FIG. 9  is a schematic sectional view of a partial structure of a composite layer of a display panel according to another embodiment of the present disclosure.  FIG. 10  is a schematic sectional view of a partial structure of a composite layer of a display panel according to yet another embodiment of the present disclosure. The composite layer  30  can be disposed without the second substrate  34 . The composite layer  30  can be formed directly without being attached to the second substrate  34 . Referring to  FIG. 9 , the at least one color layer  33  can be one orange layer  332 . Referring to  FIG. 10 , the at least one color layer  33  can be one gray layer  334 . 
     Referring back to  FIG. 1 , in some embodiments, the composite layer  30  further includes a heat dissipation layer  36  disposed at a side of the light absorption layer  32  facing away from the display module  10  and configured to dissipate the heat from the display panel  100 . The heat dissipation layer  36  can be a copper foil layer or can be made of other materials, which is not specifically limited herein. 
       FIG. 11  is an exploded sectional view of another embodiment of the display panel according to the present disclosure. Referring to  FIG. 11 , the display panel  100  can further include a scattering layer  22  disposed between the display module  10  and the at least one color layer  33 . In this embodiment, the light reflected by the at least one color layer  33  will deviate from the original reflection path when the light passes through the scattering layer  22 . The light path is shown with dashed lines in  FIG. 11 . The light respectively reflected by the hole-free region and hole region of the composite layer  30  will both deviate from the original reflection path due to the scattering effect, when the light passes through the scattering layer  22 . Therefore, the quantities of light respectively reflected from the hole region and the hole-free region of the composite layer  30  to the display module  10  can tend to be identical, thereby reducing the difference between the quantities of light reflected back to the regions of the display module  10  respectively aligned with the first through hole  321  and the outside the first through hole  321 , and thus further reducing the mura problem. 
     It should be noted that the scattering layer  22  can be an integral layer, so that the light reflected from both the hole region and hole-free region of the composite layer  30  can be scattered by the scattering layer  22 . That is, no hole is defined in the scattering layer  22 . The scattering layer  22  can be a portion of the support layer  20  and can be directly formed on the first substrate  21  of the support layer  20 . 
     In an embodiment, the scattering layer  22  is formed at a side of the first substrate  21  facing the composite layer  30 . It should be understood that the scattering layer  22  can be formed at a side of the first substrate  21  facing the display module  10  in another embodiment. This is not specifically limited herein. 
     In an embodiment, the scattering layer  22  includes scattering particles dispersed therein. The scattering particles can be selected from the group including organosilicon particles, polyethylene particles, acrylic resin particles, nano-barium sulfate particles, silicon dioxide particles, calcium carbonate particles, or any combination thereof. It should be understood that the scattering particles can be selected from particles made of other materials, which is not specifically limited herein. 
     Referring to  FIG. 12 , a display device  1000  is further provided in the present disclosure. The display device  1000  can include the above-described display panel  100 . The display device  1000  can be applied to the fields such as mobile terminal, bioelectronics, electronic skin, wearable apparatus, vehicle-mounted apparatus, IoT apparatus, and artificial intelligence apparatus. For example, the display device  1000  can be a mobile phone, a tablet, a palmtop, an iPod, a smart watch, or other digital devices. 
     The display device  1000  can further include a cover plate  200  disposed at a side of the display module  10  where the display face  11  is located. The cover plate  200  can have a first region  201  and a second region  202  adjacent to the first region  201 . The second region  202  can be provided at least one side of the first region  201 . In some embodiment, the first region  201  is a flat region, and the second region  202  can be a curved region (e.g., a curved groove region). There is a smooth transition between the first region  201  and the second region  202 , so that a curved surface display effect can be achieved. The through hole  31  defined in the composite layer  30  can be aligned with the first region  201  of the cover plate  200 , so that the optical fingerprint identification sensor is aligned with the first region  201  of the cover plate  200 , and the unlocking function using the fingerprint can be achieved in the flat region of the cover plate  200 . It should be understood that the through hole  31  can instead be aligned with the second region  202  of the cover plate  200 , so that the optical fingerprint identification sensor is aligned with the second region  202  of the cover plate  200 , and the unlocking function using the fingerprint can be achieved in the curved region of the cover plate  200 . 
     The cover plate  200  can be attached to the display module  10  of the display panel  100  via an adhesive layer such as an OCA adhesive layer, a TPU adhesive layer, or other adhesive layers, an electrostatic attachment, or other means, which is not specifically limited herein. 
     The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features are described in the embodiments. However, as long as there is no contradiction in the combination of these technical features, the combinations should be considered within the scope of the present disclosure. 
     The above-described embodiments are only several implementations of the present disclosure, and the descriptions are relatively specific and detailed, but the above-described embodiments should not be construed as limiting the scope of the present disclosure. It should be understood by those of ordinary skill in the art that various modifications and improvements can be made without departing from the concept of the present disclosure, and all fall within the protection scope of the present disclosure. Therefore, the patent protection of the present disclosure shall be defined by the appended claims.