Abstract:
A touch panel is characterized in that one side of a top panel protrudes beyond a side of a bottom panel, signals of sensing areas or conductive layer on the top panel for sensing capacitive variation or voltage variation are transmitted to a bottom surface of the protruded side, signals of sensing areas or conductive layer on the bottom panel for sensing capacitive variation or voltage variation are transmitted to a bottom surface of the top panel through conductive adhesives and to the bottom surface of the protruded side, and the top panel has a flexible PCB formed on the bottom surface of the protruded side to receive those signals. As the flexible PCB is not sandwiched between the top and bottom panels, all layers of the touch panel can be uniformly and tightly bonded and touch insensitivity caused by air penetration into the touch panel can be prevented.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a touch panel, and more particularly to a touch panel with a relatively higher yield and a uniform thickness. 
         [0003]    2. Description of the Related Art 
         [0004]    Touch panels can be classified as capacitive touch panels, resistive touch panels, surface acoustic touch panels, infrared touch panels and the like in terms of touch panel technologies. Among them, the capacitive touch panels and the resistive touch panels take the leading position in market share. The technologies behind the capactive touch panels and the resistive touch panels determine the location of a touched point based on capactive and voltage variation generated at the touched point. Structurally, both touch panels commonly have an upper substrate and a lower substrate. The surfaces of the upper substrate and the lower substrate that face each other have an indium tin oxide (ITO) layer respectively formed on the surfaces to sense the capactive or voltage variation. To output the variation signals, each of the ITO layers is connected with one wire or multiple wires. One end of each of the wires extends to one of the two sides respectively located on the upper substrate and the lower substrate and facing each other. A flexible printed circuit board (PCB) is sandwiched between the upper substrate and the lower substrate and is connected with the ends of the wires to receive signals transmitted through the wires. 
         [0005]    However, as the flexible PCB intervenes between the upper substrate and the lower substrate of the conventional touch panels, a thickness of the position where the flexible PCB is inserted between the upper substrate and the lower substrate inevitably increases, thereby causing a non-uniform thickness of the conventional touch panels. Such non-uniform thickness gives rise to adverse effect on the aesthetic appeal of the touch panels&#39; appearance. Besides, gaps are easily formed at the portion of the touch panel at which the flexible PCB is located. Once air penetrates into the touch panels through the gaps, the operational sensitivity of the touch panel is reduced. Hence, the conventional touch panels are further structurally restricted. 
       SUMMARY OF THE INVENTION 
       [0006]    An objective of the present invention is to provide a touch panel having a flexible PCB not mounted between a top panel and a bottom panel to secure a uniform thickness and airtight performance of the touch panel. 
         [0007]    To achieve the foregoing objective, the touch panel has a bottom panel, an anisotropic conductive film, an insulating layer, a top panel and a flexible PCB. 
         [0008]    The bottom panel has an EMI shielding layer, multiple lower sensing areas, multiple first lower ports, multiple second lower ports and multiple lower wires. 
         [0009]    The EMI shielding layer is formed on a bottom surface of the bottom panel. The lower sensing areas are formed on a top surface of the bottom panel and are parallelly aligned in a first direction. Each of the lower sensing areas has multiple lower sensing units serially connected. Each of the first lower ports is formed on an edge of one of the outermost lower sensing units in the first direction. The second lower ports are collectively formed on a bordering portion of a side of the top surface of the bottom panel. A count of the second lower ports corresponds to that of the first lower ports. The lower wires are respectively connected between the first lower ports and the second lower ports. 
         [0010]    The anisotropic conductive film is formed on the top surface of the bottom panel and covered on the second lower ports. 
         [0011]    The insulating layer is formed on the top surface of the bottom panel. 
         [0012]    The top panel is formed on the anisotropic conductive film and the insulating layer, is larger than the lower panel and has a protruded side, multiple upper sensing areas, multiple first upper ports, multiple second upper ports, multiple transfer ports and multiple lower wires. 
         [0013]    The protruded side protrudes beyond the side of the bottom panel having the second lower ports thereon. The upper sensing areas are formed on a bottom surface of the top panel, are parallelly aligned in a second direction that is perpendicular to the first direction, and each of the upper sensing areas has multiple upper sensing units serially connected. Each of the first upper port is formed on an edge of one of the outermost upper sensing units in the second direction. The second upper ports are formed on the bottom surface of the top panel and extend to a bottom surface of the protruded side. A count of the second upper ports corresponds to that of the first upper ports. The transfer ports are formed on the bottom surface of the top panel and extend to the bottom surface of the protruded side. A count of the transfer ports corresponds to that of the second lower ports. One end of each of the transfer ports is located directly above a corresponding second lower port. The lower wires are respectively connected between the first upper ports and the second upper ports. 
         [0014]    The flexible PCB is formed on the bottom surface of the top panel, is located on an edge of the bottom surface of the protruded side, and is electrically connected with second upper ports and the transfer ports. 
         [0015]    In the aforementioned touch panel, signals of each of the lower sensing areas on the lower panel are transmitted to a corresponding second lower port through a corresponding lower wire. The anisotropic conductive adhesives respectively formed between the second lower ports and the transfer ports on the bottom surface of the top panel allow current flowing only in one direction. Each of the second lower ports is electrically connected with a corresponding transfer port formed above it through the anisotropic conductive adhesive. As a result, signals from the lower sensing areas can respectively be further transmitted to the transfer ports and then to the flexible PCB. 
         [0016]    Alternatively, the touch panel has a bottom panel, a lower conductive layer, a separation layer, an insulating layer, an upper conductive layer and a flexible PCB. 
         [0017]    The lower conductive layer is formed on a top surface of the bottom panel, and has at least one lower electrode. One end of each lower electrode extends to one side of the lower conductive layer. 
         [0018]    The separation layer is formed on a top surface of the lower conductive layer. 
         [0019]    The insulating layer is formed on a top surface of the lower conductive layer, surrounds a border of the separation layer, is covered on the lower electrodes, and has multiple conductive adhesives formed on locations of the insulating layer to respectively correspond to and contact with the lower electrodes. 
         [0020]    The upper conductive layer is formed on top surfaces of the separation layer and the insulating layer, is larger than the lower panel, and has a protruded side, at least one upper electrode and multiple transfer ports. The protruded side protrudes beyond the side of the lower panel having the at least one lower electrode. The at least one upper electrode is formed on a bottom surface of the upper conductive layer and extends alongside three sides of the bottom surface of the upper conductive layer. A contact end of each of the at least one upper electrode extends to an edge of the protruded side. The transfer ports are formed on a bottom surface of the edge of the protruded side. A count of the transfer ports corresponds to that of the lower electrodes, and each of the transfer ports is contacted with one of the conductive adhesives on the insulating layer. 
         [0021]    The top panel is formed on a top surface of the upper conductive layer. 
         [0022]    The flexible PCB is formed on the bottom surface of the upper conductive layer and on the edge of the protruded side, and is electrically connected with the transfer ports and the contact end of each of the at least one upper electrode. 
         [0023]    In the alternative touch panel, signals of the lower conductive layer on the bottom panel are respectively transmitted to the conductive adhesives through the lower electrodes, and to the flexible PCB after being transmitted to the transfer ports on the bottom surface of the upper conductive layer. 
         [0024]    In sum, as the flexible PCB is mounted on the bottom surface of the top panel and not sandwiched between the top panel and the bottom panel, a uniform thickness of the touch panel can be maintained to increase aesthetic appeal of the touch panel. Additionally, all layers of the touch panel are tightly bonded and the airtight performance prevents air from penetrating into the touch panel to effectively avoid touch sensitivity reduction caused by air penetration into gaps between the flexible PCB and the top panel and/or the bottom panel. 
         [0025]    Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  is an exploded perspective view of an embodiment of a touch panel in accordance with the present invention; 
           [0027]      FIG. 2  is a side view in partial section of the touch panel in  FIG. 1 ; 
           [0028]      FIG. 3  is another side view in partial section of the touch panel in  FIG. 1 ; 
           [0029]      FIG. 4  is an exploded perspective view of another embodiment of a touch panel in accordance with the present invention; and 
           [0030]      FIG. 5  is a side view in partial section of the touch panel in  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    The present invention can be applied to either a capacitive touch panel or a resistive touch panel. With reference to  FIGS. 1 to 3 , a capacitive touch panel has a bottom panel  10 , an anisotropic conductive film  21 , an insulating layer  22 , a top panel  30  and a flexible PCB  40 . 
         [0032]    The bottom panel  10  has an EMI (electromagnetic interference) shielding layer  11 , multiple lower sensing areas  12 , multiple first lower ports  122 , multiple second lower ports  13  and multiple lower wires  14 . The EMI shielding layer  11  is formed on a bottom surface of the bottom panel  10  and is composed of ITO. The lower sensing areas  12  are formed on a top surface of the bottom panel  10 , parallelly align in a first direction, and each of the lower sensing areas  12  has multiple lower sensing units  121  serially connected and composed of ITO. Each of the first lower ports  122  is formed on an edge of one of the outermost lower sensing units  121  in the first direction, and is formed by a conductive material. The second lower ports  13  are collectively formed on a bordering portion of a side of the top surface of the bottom panel  10 , are composed of conductive material, and the count of the second lower ports  13  corresponds to that of the first lower ports  122 . The lower wires  14  are formed on the top surface of the bottom panel and are respectively connected between the first lower ports  122  and the second lower ports  13  and may be conductive silver wires. 
         [0033]    The anisotropic conductive film  21  is formed on the top surface of the bottom panel  10  and is covered on the second lower ports  13 . To lower the difficulty in alignment, the anisotropic conductive film  21  can be sufficiently large to cover the second lower ports  13  but cover no lower sensing unit  121 . 
         [0034]    The insulating layer  22  is transparent and is formed on the top surface of the bottom panel  10 . 
         [0035]    The top panel  30  is transparent, is formed on the anisotropic conductive film  21  and the insulating layer  22 , and has multiple upper sensing areas  31 , multiple first upper ports  312 , multiple second upper ports  32 , multiple transfer ports  33  and multiple upper wires. The top panel  30  is larger than the lower panel  10  and has a protruded side protruding beyond the side of the bottom panel  10  having the second lower ports  13  thereon. 
         [0036]    The upper sensing areas  31  are formed on a bottom surface of the top panel  30 , parallelly align in a second direction that is perpendicular to the first direction, and each of the upper sensing areas  31  has multiple upper sensing units  311  serially connected, corresponding to a portion unfilled by the lower sensing units  121  of the lower panel  10 , and composed of ITO. Each of the first upper port  312  is formed on an edge of one of the outermost upper sensing units  311  in the second direction, and is formed by a conductive material. The second upper ports  32  and the transfer ports  33  are collectively formed on the bottom surface of the top panel  30  and extend to a bottom surface of the protruded side of the top panel  30 , and are composed of conductive material. The count of the second upper ports  32  corresponds to that of the first upper ports  312 . The count of the transfer ports  33  corresponds to that of the second lower ports  13 . The upper wires  34  are formed on the bottom surface of the top panel  30 , are respectively connected between the first upper ports  312  and the second upper ports  32 , and may be conductive silver wires. One end of each of the transfer ports  33  corresponds to and is electrically connected with a corresponding second lower port  13 . 
         [0037]    A flexible PCB  40  is mounted on the bottom surface of the protruded side of the top panel  30 , and is electrically connected with second upper ports  32  and the transfer ports  33 . 
         [0038]    In the foregoing capacitive touch panel, signals of each of the upper sensing areas  31  are transmitted to a corresponding second upper port  32  through a corresponding upper wire  34  and are further transmitted to the flexible PCB  40 . Signals of each of the lower sensing areas are transmitted to a corresponding second lower port  13  through a corresponding lower wire  14 . For sake of the characteristic of the anisotropic conductive film  21  allowing current to flow in only one direction, each of the second lower ports  13  is electrically connected with a corresponding transfer port  33  formed directly above it through the anisotropic conductive film  21 . Hence, signals of each of the lower sensing area  12  are further transmitted to a corresponding transfer port  33  through the anisotropic conductive film  21  and then to the flexible PCB  40 . 
         [0039]    With reference to  FIGS. 4 and 5 , a resistive touch panel has a bottom panel  50 , a lower conductive layer  51 , a separation layer  61 , an insulating layer  62 , an upper conductive layer  71 , a top panel  70  and a flexible PCB  80 . 
         [0040]    The bottom panel  50  is transparent. The lower conductive layer  51  is transparent, is formed on a top surface of the bottom panel  50 , is composed of ITO, and has at least one lower electrode  511 . The count of the lower electrode  511  is chosen based on operation requirement. Given five-wire touch panel as an example, four lower electrodes  511  are formed on the lower conductive layer  51 . The lower electrodes  511  may be silver electrodes. One end of each of the lower electrodes  511  extends to one side of the lower conductive layer  51 . 
         [0041]    The separation layer  61  and the insulating layer  62  are formed on the top surface of the lower conductive layer  51 . The insulating layer  62  surrounds a boundary of the separation layer  61  and is covered on the lower electrodes  511 . The insulating layer  62  has multiple conductive adhesives  621  formed on locations of the insulating layer  62  to respectively correspond to and contact with the lower electrodes  511 . The conductive adhesives  621  may be anisotropic conductive adhesives. 
         [0042]    The upper conductive layer  71  is transparent, is formed on top surfaces of the separation layer  61  and the insulating layer  62 , and is composed of ITO. The upper conductive layer  71  is larger than the lower panel  50 . The upper conductive layer  71  has a protruded side, at least one upper electrode  711  and multiple transfer ports  712 . The protruded side protrudes beyond the side of the bottom panel  50  having the at least one lower electrode  511 . The at least one upper electrode  711  is formed on a bottom surface of the upper conductive layer  71  and extends alongside three sides of the bottom surface of the upper conductive layer  71 . Given the same  5 -wire touch panel, an upper electrode  7111  is formed on the bottom surface of the upper conductive layer  71 . A contact end of the upper electrode  711  extends to a bottom surface of the protruded side of the upper conductive layer  71 . The upper conductive layer  71  further has multiple transfer ports  712  formed on the bottom surface of the protruded side. The count of the transfer ports  712  corresponds to that of the lower electrodes  511 . Each of the transfer ports  712  is contacted with one of the conductive adhesives  621  on the insulating layer  62 . 
         [0043]    The top panel  70  is transparent and is formed on a top surface of the upper conductive layer  71 . The flexible PCB  80  is formed on the bottom surface of the upper conductive layer  71  and on the bottom surface of the protruded side, and is electrically connected with the transfer ports  712  and the contact end of the upper electrode  711 . 
         [0044]    In the foregoing resistive touch panel, signals of the upper conductive layer  71  on the top panel  70  are directly transmitted to the flexible PCB  80  through the upper electrode  711 . Signals of the lower conductive layer  51  on the bottom panel  50  are respectively transmitted to the conductive adhesives  621  through the lower electrodes  511 , and then are transmitted to the flexible PCB  80  after being transmitted to the transfer ports  712  on the bottom surface of the upper conductive layer  71 . 
         [0045]    In the touch panels of the present invention, all transfer ports  33 ,  712  and the second upper ports  32  or the contact end of the upper electrode  711  are collectively formed on the bottom surface of the top panel  30 ,  70 , terminals of the flexible PCB  40 ,  80  can be easily aligned with the transfer ports  33 ,  712  and the second upper ports  32  or the contact end of the upper electrode  711  respectively. Besides, as the flexible PCB  40 ,  80  is formed on the bottom surface of the top panel  30 ,  70  and not between the top panel  30 ,  70  and the bottom panel  10 ,  50 , the uniform thickness of the touch panel enhances the aesthetic appeal of the appearance of the touch panel. Meanwhile, all layers of the touch panels of the present invention are tightly bonded and have a good airtight effect, thereby effectively solving the drawback of the touch sensitivity reduction resulting from air penetration into gaps between the flexible PCB and the top surface and/or the bottom panels. 
         [0046]    Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only. Changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.