Abstract:
An electronic device able to identify fingerprints ultrasonically includes a substrate, a fingerprint identification structure, and an adhesive layer. The fingerprint identification structure includes a thin film transistor (TFT) substrate and a flexible printed circuit (FPC). The FPC includes a first portion and a second portion. The first portion is located on a surface of the TFT substrate facing away from the substrate. The second portion is extended from an end of the first portion to be electrically connected to a surface of the TFT substrate facing the substrate. The second portion is separated from the adhesive layer. A space is defined between the second portion and the substrate. The adhesive layer is susceptible to deformation and decomposition from environmental conditions.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to Chinese Patent Application No. 201610588031.2 filed on Jul. 25, 2016, the contents of which are incorporated by reference herein. 
       FIELD 
       [0002]    The subject matter herein generally relates to data security. 
       BACKGROUND 
       [0003]    As shown in  FIG. 8 , an electronic device with fingerprint identification function  200  can include a substrate  201 , an adhesive layer  202 , and a fingerprint identification structure  203 . The adhesive layer  202  joins the substrate  201  and the fingerprint identification structure  203  together. The fingerprint identification structure  203  includes a thin film transistor (TFT) substrate  204 , a transmitting layer  205 , a receiving layer  206 , and a flexible printed circuit (FPC)  207 . The transmitting layer  205  and the receiving layer  206  are each located on one of the two opposite surfaces of the TFT substrate  204 . The FPC  207  is attached to a side of the transmitting layer  205  facing away from the receiving layer  206 . An end of the FPC  207  is bent to connect a bottom surface of the TFT substrate  204  and is located adjacent to the receiving layer  206 . The receiving layer  206  and the FPC  207  are positioned on and pasted on a same surface of the adhesive layer  202 . The adhesive layer  202  is susceptible to deformation and decomposition from environmental conditions (e.g. variations in external temperature) and age. Due to a tendency of the adhesive layer  202  to shrink, the FPC  207  is often unintentionally detached from the TFT substrate  204 . A better structure of the electronic device with a fingerprint identification apparatus  200  is needed. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0004]    Implementations of the present technology will now be described, by way of example only, with reference to the attached figures. 
           [0005]      FIG. 1  is cross-sectional view of a first exemplary embodiment of an electronic device with fingerprint identification function, the electronic device comprises a thin film transistor (TFT) substrate. 
           [0006]      FIG. 2  is a plan view of the TFT substrate of  FIG. 1 . 
           [0007]      FIG. 3  is a cross-sectional view of a second exemplary embodiment of an electronic device with fingerprint identification function, the electronic device comprises a TFT substrate. 
           [0008]      FIG. 4  is a plan view of the TFT substrate of  FIG. 3 . 
           [0009]      FIG. 5  is a cross-sectional view of a third exemplary embodiment of an electronic device with fingerprint identification function, the electronic device comprises a TFT substrate. 
           [0010]      FIG. 6  is a plan view of the TFT substrate of  FIG. 5 . 
           [0011]      FIG. 7  is a cross-sectional view of a fourth exemplary embodiment of an electronic device with fingerprint identification function, the electronic device comprises a TFT substrate. 
           [0012]      FIG. 8  is a cross-sectional view of an electronic device of related art with fingerprint identification function. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail so as not to obscure the related relevant feature being described. The drawings are not necessarily to scale and the proportions of certain parts may be exaggerated to better illustrate details and features. The description is not to be considered as limiting the scope of the embodiments described herein. 
         [0014]    The term “substantially” is defined to be essentially conforming to the particular dimension, shape, or other feature that the term modifies, such that the component need not be exact. For example, “substantially cylindrical” means that the object resembles a cylinder, but can have one or more deviations from a true cylinder. The term “comprising” means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in a so-described combination, group, series, and the like. 
         [0015]    The present disclosure is described in relation to an electronic device with fingerprint identification function. 
         [0016]      FIG. 1  illustrates an exemplary embodiment of an electronic device  100  with fingerprint identification function. In at least one exemplary embodiment, the electronic device  100  can be for example a mobile phone, a watch, or a tablet with a fingerprint identification function. The electronic device  100  includes a substrate  10 , a fingerprint identification structure  20 , and an adhesive layer  30  between the substrate  10  and the fingerprint identification structure  20 . The adhesive layer  30  joins the substrate  10  and the fingerprint identification structure  20  together. 
         [0017]    The substrate  10  is substantially rectangular. In at least one exemplary embodiment, the substrate  10  is made of glass. The substrate  10  can prevent dust from entering into the electronic device  100 . In other embodiments, the substrate  10  can be made of one or more of the following materials, or equivalents thereof; metal or compounds thereof (for example, aluminum, magnesium alloy, and aluminum oxide), plastic film (for example, polymethyl methacrylate, polyethersulfone resin, and polyethylene terephthalate), plastic film sapphire, or compounds thereof. The substrate  10  can be a cover of an electronic device or a cover or part of a cover facing a home key of an electronic device. 
         [0018]    The fingerprint identification structure  20  includes a thin film transistor (TFT) substrate  21 , a transmitting layer  23 , a receiving layer  25 , and a flexible printed circuit (FPC)  27 . The TFT substrate  21  provides a specified voltage in controlling the transmitting layer  23  to generate ultrasonic signals. In at least one exemplary embodiment, the TFT substrate  21  includes a plurality of TFTs arranged in a matrix, and can form a portion of the display panel of the electronic device  100 . The receiving layer  25  converts the ultrasonic signals reflected by an object into electrical signals. The TFT substrate  21  includes a first surface  211  and a second surface  213  opposite to and facing away from the first surface  211 . The second surface  213  defines a first region  2131  and a second region  2133 . As shown in  FIG. 2 , an area of the first region  2131  is larger than the second region  2133 . The transmitting layer  23  is located on the first surface  211 . The receiving layer  25  is located on the second surface  213 , and covers the first region  2131 . An edge of the receiving layer  25  is aligned with an edge of the first region  2131  adjacent to the second region  2133 . The FPC  27  is located on the transmitting layer  23 , and is bent to connect to the second region  2133  by extending along the side of the transmitting layer  23  and the side of the TFT substrate  21 . The FPC  27  includes a first portion  271 , a second portion  273 , and a connection portion  275 . The first portion  271  is located on a surface of the transmitting layer  23  facing away from the TFT substrate  21 . The second portion  273  extends from an end of the first portion  271  to the second region  2133 , and covers the side of the transmitting layer  23  and the side of the TFT substrate  21 . The second portion  273  is spaced at a distance from the substrate  10  and the adhesive layer  30 . The connection portion  275  is positioned to attach the second region  2133  with the second portion  273 , and establishes an electrical connection between the second portion  273  and the TFT substrate  21 . The second portion  273  above the substrate  10  extends towards the adhesive layer  30  to be adjacent to and spaced apart from the adhesive layer  30 . In at least one exemplary embodiment, the connection portion  275  can be metal pins, and such metal pins can connect with the TFT substrate  21  by an anisotropic conductive film (not shown). 
         [0019]    The adhesive layer  30  is located between the receiving layer  25  and the substrate  10 . The adhesive layer  30  is positioned on and pasted to a surface of the receiving layer  25  opposite to and facing away from the second surface  213 . The adhesive layer  30  is further positioned on and pasted to a surface of the substrate  10 . Thus, the adhesive layer  30  joins the receiving layer  25  and the substrate  10  together. In at least one exemplary embodiment, the adhesive layer  30  is made of polymer material or equivalents thereof, such as acrylic, epoxy, and silicone. 
         [0020]    In the structure of the electronic device  100 , the second portion  273  is spaced apart from the substrate  10  and the adhesive layer  30 . Thus, deformation due to shrinkage of the adhesive layer  30  does not affect an electronic connection between the FPC  27  and the TFT substrate  21 . Therefore, an electric connection stability of the electronic device  100  is improved. 
         [0021]      FIG. 3  illustrates a second exemplary embodiment of the electronic device  300 . The electronic device  300  according to the second exemplary embodiment is similar to the electronic device  100 . The electronic device  300  includes a substrate  40 , a fingerprint identification structure  50 , and an adhesive layer  60  between the substrate  40  and the fingerprint identification structure  50 . The adhesive layer  60  joins the substrate  40  and the fingerprint identification structure  50  together. The differences between the electronic device  300  and the electronic device  100  will now be described. 
         [0022]    The substrate  40  is substantially rectangular. In at least one exemplary embodiment, the substrate  40  is made of glass. The substrate  40  can prevent dust from entering into the electronic device  300 . In other embodiments, the substrate  10  can be made of the same materials as those used in electronic device  100 . The substrate  40  can be functionally the same as that used in electronic device  100 . 
         [0023]    The fingerprint identification structure  50  includes a thin film transistor (TFT) substrate  51 , a transmitting layer  53 , a receiving layer  55 , and a flexible printed circuit (FPC)  57 . The TFT substrate  51  provides a specified voltage for controlling the transmitting layer  53  to generate ultrasonic signals. In at least one exemplary embodiment, the TFT substrate  51  includes a plurality of TFTs. The TFTs are arranged in a matrix. The receiving layer  55  converts the ultrasonic signals reflected by an object into electrical signals. The TFT substrate  51  includes a first surface  511  facing away from the TFT substrate  51  and a second surface  513  opposite to and facing away from the first surface  511 . The second surface  513  defines a first region  5131  and a second region  5133 . As shown in  FIG. 4 , an area of the first region  5131  is larger than the second region  5133 . The transmitting layer  53  is located on the first surface  511 . The receiving layer  55  is located on the second surface  513  and covers the first region  5131 . An edge of the receiving layer  55  is aligned with an edge of the first region  5131  adjacent to the second region  5133 . The FPC  57  is located on the transmitting layer  53 , and is bent to connect to the second region  5133  by extending along the side of the transmitting layer  53  and the side of the TFT substrate  51 . The FPC  57  includes a first portion  571 , a second portion  573 , and a connection portion  575 . The first portion  571  is located on a surface of the transmitting layer  53  facing away from the TFT substrate  51 . The second portion  573  extends from an end of the first portion  571  to the second region  5133 , and covers the side of the transmitting layer  53  and the side of the TFT substrate  51 . The second portion  573  is spaced at a distance from the substrate  40  and the adhesive layer  30 . A space  576  is defined between the second portion  573  and the substrate  40 . The connection portion  575  establishes an electrical connection between the second portion  573  and the TFT substrate  51 . In at least one exemplary embodiment, the connection portion  575  can comprise metal pins, and the connection portion  575  can connect with the TFT substrate  51  by an anisotropic conductive film (not shown). 
         [0024]    The adhesive layer  60  is located between the receiving layer  55  and the substrate  40 . In at least one exemplary embodiment, the adhesive layer  60  is made of polymer material or equivalents thereof such as acrylic, epoxy, and silicone. 
         [0025]    The adhesive layer  60  includes a first adhesive portion  61  and a second adhesive portion  63 . The adhesive portion  61  is pasted to a surface of the receiving layer  55  opposite to and facing away from the second surface  513 . The adhesive layer  60  is further positioned on and pasted to a surface of the substrate  40 . Thus, the adhesive portion  61  joins the receiving layer  55  and the substrate  40  together. The second adhesive portion  63  is received in the space  576 . The second adhesive portion  63  is located on the second portion  575 . The second adhesive portion  63  covers a bottom surface of the second portion  575  facing the substrate  40 , and protects against ingress of water to a surface of the second portion  573  facing the substrate  40 . The second adhesive portion  63  is spaced apart from the substrate  40 . The space  576  being defined by the surface of the substrate  40 , the surface of the second portion  573  facing the substrate  40 , and an edge of the second adhesive portion  63 . A hardness of the first adhesive portion  61  is equal to a hardness of the second adhesive portion  63 . A thickness of the second adhesive portion  63  is less than a distance between the second portion  575  and the substrate  40 . The thickness of the second adhesive portion  63  is more than 80% of the distance between the second portion  575  and the substrate  40 . In at least one exemplary embodiment, the thickness of the first adhesive portion  61  is larger than a thickness of the second adhesive portion  63 . In other embodiments, a thickness of the first adhesive portion  61  is equal to a thickness of the second adhesive portion  63 . 
         [0026]    In the structure of the electronic device  300 , the second adhesive portion  63  is spaced apart from the substrate  40 . Thus movement or forces caused by deformation of the second adhesive portion  63  are reduced. Separation of the FPC  57  from the TFT substrate  51  is thus prevented. The second portion  573  is spaced apart from the first adhesive portion  61 , and any forces generated by the first adhesive portion  61  have no effect on the FPC  57 . Therefore, an electric connection stability of the electronic device  300  is improved. 
         [0027]      FIG. 5  illustrates a third exemplary embodiment of the electronic device  400 . The electronic device  400  according to the third exemplary embodiment is similar to the electronic device  300 . The electronic device  400  includes a substrate  70 , a fingerprint identification structure  80 , and an adhesive layer  90  between the substrate  70  and the fingerprint identification structure  80 . The adhesive layer  90  joins the substrate  70  and the fingerprint identification structure  50  together. Differences between the electronic device  400  and the electronic device  300  will now be described. 
         [0028]    The substrate  70  is substantially rectangular. In at least one exemplary embodiment, the substrate  70  is made of glass. The substrate  70  can prevent dust from entering into the electronic device  400 . In other embodiments, the substrate  10  can be made of the same materials used in electronic device  300 . The substrate  40  can be as previously described. 
         [0029]    The fingerprint identification structure  80  includes a thin film transistor (TFT) substrate  81 , a transmitting layer  83 , a receiving layer  85 , and a flexible printed circuit (FPC)  87 . TFT substrate  81  provides a specified voltage for controlling the transmitting layer  83  to generate ultrasonic signals. In at least one exemplary embodiment, the TFT substrate  81  includes a plurality of TFTs arranged in a matrix. The receiving layer  85  converts the ultrasonic signals reflected by an object into electrical signals. The TFT substrate  81  includes a first surface  811  facing away from the TFT substrate  81  and a second surface  813  opposite to and facing away from the first surface  811 . The second surface  813  defines a first region  8131  and a second region  8133 . As shown in  FIG. 6 , an area of the first region  8131  is larger than the second region  8133 . The transmitting layer  83  is located on the first surface  811 . The receiving layer  85  is located on the second surface  813 , and covers the first region  2131 . An edge of the receiving layer  55  is aligned with an edge of the first region  8131  adjacent to the second region  8133 . The FPC  87  is located on the transmitting layer  83  and is bent to connect to the second region  8133  by extending along the side of the transmitting layer  83  and the side of the TFT substrate  81 . The FPC  87  includes a first portion  871 , a second portion  873 , and a connection portion  875 . The first portion  871  is located on a surface of the transmitting layer  83  facing away from the TFT substrate  81 . The second portion  873  extends from an end of the first portion  871  to the second region  8133 , and covers the side of the transmitting layer  83  and the side of the TFT substrate  81 . The second portion  873  is spaced at a distance from the substrate  70 . A space  876  is defined between the second portion  873  and the substrate  70 . The connection portion  875  establishes an electrical connection between the second portion  873  and the TFT substrate  81 . In at least one exemplary embodiment, the connection portion  875  can be metal pins, and the connection portion  875  can connect with the TFT substrate  81  by an anisotropic conductive film (not shown). 
         [0030]    The adhesive layer  90  is located between the receiving layer  85  and the substrate  70 . In at least one exemplary embodiment, the adhesive layer  90  is made of polymer material or equivalents thereof such as acrylic, epoxy, and silicone. 
         [0031]    The adhesive layer  90  includes a first adhesive portion  91  and a second adhesive portion  93 . The adhesive portion  91  is positioned on and pasted to a surface of the receiving layer  85  opposite to and facing away from the second surface  813 . The adhesive portion  91  is further positioned on and pasted to a surface of the substrate  70 . Thus, the adhesive portion  91  joins the receiving layer  85  and the substrate  70  together. The second adhesive portion  93  is received in the space  876 . The second adhesive portion  93  is located between the second portion  873  and the substrate  70 . The second adhesive portion  93  covers a surface of the second portion  873  facing the substrate  70 . The second adhesive portion  93  joins the second portion  873  and the substrate  70  together. The space  876  is defined by the surface of the substrate  40 , the surface of the second portion  873  facing the substrate  70 , and an edge of the second adhesive portion  93 . A thickness of the second adhesive portion  93  is equal to a distance between the second portion  873  and the substrate  70 . A hardness of the second adhesive portion  93  is less than a hardness of the first adhesive portion  91 . In at least one exemplary embodiment, the hardness of the second adhesive portion  93  is less than 60 shore according to ASTMD2240 standard. 
         [0032]    In the structure of the electronic device  400 , the second adhesive portion  93  is spaced apart from the first adhesive portion  91 , thus movements or forces generated by the deforming of the second adhesive portion  93  is reduced, preventing the separation of FPC  87  from TFT substrate  81 . The second portion  873  is spaced apart from the first adhesive portion  91 , and force generated by the first adhesive portion  91  has no effect on the FPC  87 . Therefore, an electric connection stability of the electronic device  400  is improved. 
         [0033]      FIG. 7  illustrates a fourth exemplary embodiment of the electronic device  500 . The electronic device  500  according to the fourth exemplary embodiment is similar to the electronic device  300 . The electronic device  500  includes a substrate  501 , a fingerprint identification structure  502 , and an adhesive layer  507  between the substrate  501  and the fingerprint identification structure  502 . The adhesive layer  507  joins the substrate  501  and the fingerprint identification structure  502  together. The differences between the electronic device  500  and the electronic device  300  will now be described. 
         [0034]    The substrate  501  is substantially rectangular. In at least one exemplary embodiment, the substrate  501  is made of glass. The substrate  501  can prevent dust from entering into the electronic device  500 . In other embodiments, the substrate  10  can be as previously described. The substrate  501  can be as previously described. 
         [0035]    The fingerprint identification structure  502  includes a thin film transistor (TFT) substrate  503 , a transmitting layer  521 , a receiving layer  522 , and a flexible printed circuit (FPC)  504 . TFT substrate  503  provides a specified voltage for controlling the transmitting layer  521  to generate ultrasonic signals. In at least one exemplary embodiment, the TFT substrate  501  includes a plurality of TFTs arranged in a matrix. The receiving layer  522  converts the ultrasonic signals reflected by an object into electrical signals. The transmitting layer  521  is located on a surface of the TFT substrate  503  facing away from the substrate  501 . The receiving layer  522  is located on a surface of the TFT substrate  503  facing away from the substrate  501 . The FPC  504  is located on the transmitting layer  521  and is bent to connect to a surface of the TFT substrate  503  adjacent to the substrate  501  by extending along the side of the transmitting layer  521  and the side of the TFT substrate  503 . The FPC  504  includes a first portion  523 , a second portion  505 , and a connection portion  524 . The first portion  523  is located on a surface of the transmitting layer  521  facing away from the TFT substrate  503 . The second portion  505  extends from an end of the first portion  523  to the TFT substrate  503 , and covers the side of the transmitting layer  521  and the side of the TFT substrate  503 . The second portion  505  is spaced apart from the substrate  501 , and is electrically connected to the TFT substrate  503 . 
         [0036]    The adhesive layer  507  includes a first adhesive portion  508  and a second adhesive portion  509 . The adhesive portion  508  is positioned on and pasted to a surface of the receiving layer  522  facing away from the TFT substrate  503 . The adhesive portion  508  is further positioned on and pasted to a surface of the substrate  501 . Thus, the adhesive portion  508  joins the receiving layer  522  and the substrate  501  together. The second adhesive portion  509  is received in the space  506 . The second adhesive portion  509  is positioned on and pasted to the second portion  505  and is spaced apart from the substrate  501 . The second adhesive portion  509  covers a surface of the second portion  505  facing the substrate  70 . The second adhesive portion  509  joins the second portion  505  and the substrate  501  together. A thickness of the second adhesive portion  509  is equal to a distance between the second portion  505  and the substrate  501 . A hardness of the second adhesive portion  509  is less than a hardness of the first adhesive portion  508 . In at least one exemplary embodiment, the hardness of the second adhesive portion  509  is less than 60 shore according to ASTMD2240 standard. 
         [0037]    In the structure of the electronic device  500 , the second adhesive portion  509  is spaced apart from the substrate  501 . Thus movement or forces generated by the deforming of the second adhesive portion  509  is reduced, preventing separation of the FPC  504  from the TFT substrate  503 . The second portion  505  is spaced apart from the first adhesive portion  508 , and forces generated by the first adhesive portion  508  have no effect on the FPC  503 . Therefore, an electric connection stability of the electronic device  500  is improved. 
         [0038]    While various exemplary and preferred embodiments have been described, the disclosure is not limited thereto. On the contrary, various modifications and similar arrangements (as would be apparent to those skilled in the art) are intended to also be covered. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.