Patent Publication Number: US-2021182523-A1

Title: Fingerprint identification structure of display

Description:
BACKGROUND OF INVENTION 
     Field of Invention 
     The present invention relates to a technical field of fingerprint identification structures, in particular to a sensitive in-screen display fingerprint recognition structure of an active matrix organic light emitting diode (AMOLED). 
     Description of Prior Art 
     At present, mobile phones with an in-screen optical fingerprint recognition function have appeared on the market, wherein light emitted by the active matrix organic light emitting diodes (AMOLEDs) is reflected by a fingerprint on a surface layer to reach a back of a screen, and then received by a fingerprint module to form a fingerprint image, thereby performing fingerprint recognition actions. The existing fingerprint identification structure also has another reflection at a bottom of a substrate of the AMOLED, wherein partial reflection occurs when an incident angle is small, while total reflection occurs when the incident angle reaches a total reflection condition, wherein the total reflection has the biggest impact, which will greatly reduce brightness of the fingerprint that the fingerprint module can receive, thus negatively affecting sensitivity of fingerprint recognition. 
     The existing fingerprint identification structure also has another reflection at a bottom of a substrate of an active matrix organic light emitting diode (AMOLED), wherein partial reflection occurs when the incident angle is small, while total reflection occurs when the incident angle reaches the total reflection condition, wherein the total reflection has the largest impact, which will greatly reduce the brightness of the fingerprint that the fingerprint module can receive, thus negatively affecting fingerprint recognition sensitivity. 
     SUMMARY OF INVENTION 
     An object of the present invention is to provide a fingerprint identification structure of a display screen, including: a fingerprint module; a substrate layer disposed on the fingerprint module, a hollow space being defined between the substrate layer and the fingerprint module, a plurality of anti-total reflection structures being arranged on a side of the substrate layer facing the fingerprint module; an organic light-emitting layer disposed on the substrate layer; and a surface layer disposed above the organic light-emitting layer. Accordingly, when each light beam passing through a conical structure is incident on a surface of the conical structure, if total reflection occurs, only partial reflection occurs on the other side, which is equivalent to changing part of the total reflected light to the partially reflected light, that is, the percentage of transmitted light is increased, so that the brightness of the light received by the fingerprint module is also increased, thereby increasing the sensitivity of the fingerprint module. 
     In some embodiments, the anti-total reflection structures are conical protruding structures. 
     In some embodiments, a transparent cathode layer is disposed on the organic light-emitting layer. 
     In some embodiments, a protective layer is disposed on the transparent cathode layer. 
     In some embodiments, a plurality of intermediate layers are disposed between the protective layer and the surface layer. 
     In some embodiments, an intermediate layer is disposed between the protective layer and the surface layer. 
     In some embodiments, the hollow space is defined by a sealant between the substrate layer and the fingerprint module. 
     In some embodiments, plurality of anti-total reflection structures are a plurality of conical protruding structures arranged in a matrix. 
     In some embodiments, each of the conical protruding structures has a conical angle α ranging from 
     
       
         
           
             
               
                 
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     where n 2  is a refractive index of the substrate layer, and n 1  is a refractive index of a medium in the hollow space. 
     An object of the present invention is to provide a display device including the fingerprint recognition structure as described above, and the fingerprint recognition structure is an optical fingerprint recognition structure. 
     The beneficial effects of the present invention are that when each light beam passing through a conical structure is incident on a surface of the conical structure, if total reflection occurs, only partial reflection occurs on the other side, which is equivalent to changing part of the total reflected light to the partially reflected light, that is, the percentage of transmitted light is increased, so that the brightness of the light received by the fingerprint module is also increased, thereby increasing the sensitivity of the fingerprint module. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a cross-sectional view showing a fingerprint identification structure of a display screen according to an embodiment of the present invention. 
         FIG. 2  is a partial cross-sectional view of a fingerprint identification structure of a display screen according to another embodiment of the present invention. 
         FIG. 3  is a schematic top view showing a conical protruding structure arranged in a matrix in a fingerprint identification structure of a display screen according to an embodiment of the present invention. 
         FIG. 4A  is a schematic diagram of an internal light path of a conical protruding structure of a fingerprint identification structure of a display screen according to an embodiment of the present invention. 
         FIG. 4B  is a schematic diagram of an internal light path of a conical protruding structure of a fingerprint identification structure of a display screen according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The following description of the various embodiments is provided to illustrate the specific embodiments of the invention. The spatially relative directional terms mentioned in the present invention, such as “upper”, “lower”, “before”, “after”, “left”, “right”, “inside”, “outside”, “side”, etc. and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures which are merely references. The spatially relative terms are intended to encompass different orientations in addition to the orientation as depicted in the figures. 
     In the present specification, like numbers refer to like elements throughout the description of the figures. 
     Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present disclosure. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. 
     Referring to  FIG. 1  to  FIG. 4B , in view of a light path, light  91  emitted by an active matrix organic light emitting diode (AMOLED) becomes a reflected light  92  by a fingerprint  94 , or sweat  95  on a surface layer  50  to reach the back of a screen and becomes transmitted light  93 , and is then received by a fingerprint module  10  to form a fingerprint image, thereby performing a fingerprint recognition operation. An object of the present invention is to provide a fingerprint identification structure of a display screen, including: a fingerprint module  10 ; a substrate layer  20  disposed on the fingerprint module  10 , a hollow space  30  defined between the substrate layer  20  and the fingerprint module  10 , a plurality of anti-total reflection structures  11  arranged on a side of the substrate layer  20  facing the fingerprint module  10 ; an organic light emitting layer  40  disposed on the substrate layer  20 ; and a surface layer  50  disposed above the organic light emitting layer  40 . Accordingly, when each light beam passing through a conical structure is incident on a surface of the conical structure, if total reflection occurs, only partial reflection occurs on the other side, which is equivalent to changing part of the total reflected light to the partially reflected light, that is, the percentage of transmitted light is increased, so that brightness of the light received by the fingerprint module  10  is also increased, thereby increasing sensitivity of the fingerprint module  10 . Another object of the present invention is to reduce the occurrence of total reflection on a bottom surface of the AMOLED substrate layer and to increase the transmitted light. 
     In some embodiments, wherein the anti-total reflection structures  11  are conical protruding structures. 
     In some embodiments, a transparent cathode layer  60  is disposed on the organic light emitting layer  40 . 
     In some embodiments, a protective layer  70  is disposed on the transparent cathode layer  60 . 
     In some embodiments, a plurality of intermediate layers  80  are disposed between the protective layer  70  and the surface layer  50 . 
     In some embodiments, an intermediate layer  80  is disposed between the protective layer  70  and the surface layer  50 . 
     In some embodiments, the hollow space  30  is defined by a sealant  12  and a frame glue  13  between the substrate layer  20  and the fingerprint module  10 . 
     In some embodiments, the plurality of anti-total reflection structures  11  are a plurality of conical protruding structures arranged in a matrix. 
     In some embodiments, each of the conical protruding structures  11  has a conical angle α, which has a range calculated with respect to the following rule: n 2  is known as a refractive index of an AMOLED substrate, and n 1  is refractivity of a medium in a hollow space (gap), and therefore, when the light in the AMOLED substrate is incident on an interface between the substrate and the medium in the hollow space (gap), a critical angle at which total reflection occurs is 
     
       
         
           
             
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     As shown in  FIG. 4A  (maximum value of α) and  FIG. 4B  (minimum value of α), two types of light paths of total reflection are shown (the arrow is the light path, and the dotted line is a perpendicular line of the interface), and the light is totally reflected at location A to reach location B. It can be obtained from  FIGS. 4A and 4B . 
     To make total reflection not to occur at location B, it should will comply with the following formula: 
     
       
         
           
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     In summary, the following formula is obtained. 
     
       
         
           
             
               
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     where n 2  is a refractive index of the substrate layer  20 , and n 1  is a refractive index of a medium in the hollow space  30 . Accordingly, when each light beam passing through a conical structure is incident on a surface of the conical structure, if total reflection occurs, only partial reflection occurs on the other side, which is equivalent to changing part of the total reflected light to the partially reflected light, that is, the percentage of transmitted light is increased, so that the brightness of the light received by the fingerprint module  10  is also increased, thereby increasing the sensitivity of the fingerprint module  10 . Another object of the present invention is to reduce the occurrence of total reflection on the bottom surface of the AMOLED substrate layer and to increase the transmitted light. 
     In addition, another object of the present invention is to provide a display device including the fingerprint identification structure as described above, and the fingerprint recognition structure is an optical fingerprint recognition structure. 
     While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.