Abstract:
A touch signal transmission circuit and an LCD using the same include an upper substrate and a plurality of first and second electrodes mounted at an inner side of the upper substrate. The first and second electrodes are arranged along a first direction and a second direction respectively, being electrically insulated with each other. Where the first and second electrodes are interlaced with each other defines touch0sensitive sections. When the user&#39;s finger touches the surface of the upper substrate, the touch-sensitive sections are touched for control or activation of the LCD. In light of this structure, the whole LCD is thinned and lightened.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to control structure of a liquid crystal display (LCD), and more particularly, to a touch signal transmission circuit and an LCD using the same. 
         [0003]    2. Description of the Related Art 
         [0004]    A touch-sensitive device, like a touch panel, functioning by sensing the locations that a user&#39;s finger or an object touches a panel and then transmitting signals for control or activation is the most user-friendly input device, such that it is applied to a variety of electronic products. The known touch panel principally includes resistive-type, capacitor-type, and electromagnetic-type. Among them, the resistive-type touch panel is currently the majority, but it fails to do multiple touches to have limited control. It also needs pressure for touch sensation, such that specific parts of the touch panel are subject to damage because they have to stand repeated stress for a long time. In light of this, the multi-touch capacitive-type touch panel that does not have to stand overmuch stress is more and more popular in the market. 
         [0005]    However, even though the capacitive-type touch panel is dominant in the market, it is attached to the LCD to thicken and weight the whole panel, such that it is possible to deteriorate the optical display effect, e.g. the remittance lowers or the reflectivity rises. As for the electronic products that are developed more and more compact, there is still some space for improvement of such drawback. 
       SUMMARY OF THE INVENTION 
       [0006]    The primary objective of the present invention is to provide an LCD, whose thickness and weight can be effectively reduced on the whole. 
         [0007]    The foregoing objective of the present invention is attained by the LCD composed of an upper substrate, a touch signal transmission circuit, a lower substrate, and a touch-sensitive integrated circuit (IC). The touch signal transmission circuit is formed at an inner side of the upper substrate, having a plurality of first electrodes and a plurality of second electrodes. The first and second electrodes are arranged along a first direction and a second direction respectively, being electrically insulated with each other. The touch signal transmission circuit includes at least one first bonding pad electrically connected with the first electrodes; and at least one second bonding pad electrically connected with the second electrodes. The lower substrate is attached to a bottom side of the upper substrate, having a plurality of lead wires. Each of the lead wires has two ends, one of which is electrically connected with the first and second bonding pads and the other is electrically connected with the touch-sensitive IC. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is an exploded view of a first preferred embodiment of the present invention. 
           [0009]      FIG. 2  is a perspective view of the first preferred embodiment of the present invention. 
           [0010]      FIG. 3  is a sectional view of  FIG. 2 . 
           [0011]      FIG. 4  is a perspective view of a part of the preferred embodiment of the present invention, illustrating the relationship between a touch signal transmission circuit and masking elements. 
           [0012]      FIG. 5  is similar to  FIG. 2 , illustrating that a touch-sensitive IC is mounted to a flexible printed circuit board (PCB). 
           [0013]      FIG. 6  an exploded view of a second preferred embodiment of the present invention, illustrating that two electrodes share one same bonding pad. 
           [0014]      FIG. 7  is a perspective view of a part of the second preferred embodiment of the present invention, illustrating that the electrodes are embedded into corresponding masking elements in a predetermined interval and each of the electrodes is electrically connected with one bonding pad. 
           [0015]      FIG. 8  is similar to  FIG. 7 , illustrating that two electrodes share one bonding pad. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0016]    Referring to  FIGS. 1-3 , an LCD  1  in accordance with a preferred embodiment of the present invention is composed of an upper substrate  10 , a touch signal transmission circuit  20 , a lower substrate  26 , a conductive layer  32 , a conductive layer  32 , and a touch-sensitive IC  34 . The following description does not mention the manufacturing process but the structure and features only. 
         [0017]    The upper substrate  10  includes a transparent main body  12  and a color filter  14  located at an inner side  12   a  of the transparent main body  12 . The color filter  14  is composed of a black matrix (BM) and a plurality of red, green, blue filter units  14   a ,  14   b , and  14   c . The BM is made of black resin, having a plurality of first masking elements  16  arranged along a first direction D 1 ; and a plurality of second masking elements  18  arranged along a second direction D 2 . The first direction D 1  and the second direction D 2  are vertically interlaced with each other. The first and second masking elements  16  and  18  define a plurality of zones, in which the red, green, and blue filter units  14   a ,  14   b , and  14   c  are arranged in sequence. 
         [0018]    Referring to  FIG. 4  in view of  FIG. 1  again, the touch signal transmission circuit  20  includes a plurality of first and second electrodes  21  and  22  and a plurality of first and second bonding pads  23  and  24 . The first electrodes  21  are arranged along the first direction D 1  and encased by the first masking elements  16  respectively. Each of the first electrodes  21  is electrically connected with the first bonding pad  23  located close to one lateral edge of the transparent main body  12 . The second electrodes  22  are arranged along the second direction D 2  and encased by the second masking elements  18  respectively. Each of the second electrodes  22  is electrically connected with the second bonding pad  24  located close to one lateral edge of the transparent main body  12 . It is to be noted that the second electrodes  22  are prepared after the first masking elements  16  are prepared, such that the second electrodes  22  are not electrically connected with the first electrodes  21  but stacked on the first electrodes  21  by electric insulation. Where the first and second electrodes  21  and  22  overlap each other become touch-sensitive sections of the present invention. Because the electrode is a very delicate element, there are only a few electrodes shown in the drawings to facilitate illustration and drafting the drawings. 
         [0019]    The lower substrate  26  includes a transparent main body  27  and a plurality of film transistors  28 . The transparent main body  27  is larger than the aforementioned transparent main body  12 . The film transistors  28  are arranged on array on a surface of the transparent main body  27 . The lower substrate  26  is attached to a bottom side of the upper substrate by a main seal  29 . Where the main seal  29  is disposed is involved with the corresponding touch-sensitive sections. The transparent main body  27  of the lower substrate  26  includes a plurality of lead wires  30  located at a periphery of the main seal  29 . Each of the lead wires has a first contact point  30   a  and a second contact point  30   b  at respective two ends thereof. 
         [0020]    The conductive layer  32  is located between the upper and lower substrates  10  and  26  for electrical connection of the first and second bonding pads  23  and  24  with the first contact points  30   a  of the corresponding lead wires  30 . In this embodiment, the conductive layer  32  is an anisotropic conductive film (ACF); alternatively, it can also be inexpensive conductive particles. 
         [0021]    The touch-sensitive IC  34  is directly connected to the transparent main body  27  of the lower substrate  26  and electrically connected with the second contact points  30   b  of the lead wires  30 . The touch-sensitive IC  34  is adapted for receiving signals of sensing specific locations as transmitted in the touch-sensitive sections for activation or control of the LCD  1 . The touch-sensitive IC  34  can also be electrically connected to a flexible PCB  35  as shown in  FIG. 5 , and then the flexible PCB  35  is electrically connected with the second contact points  30   b  of the lead wires  30  of the lower substrate  26 . 
         [0022]    As known from the above, the primary feature of the present invention lies in that the touch signal transmission circuit  20  for touch sensation is directly prepared at the inner side  12   a  of the existent upper substrate  10  of the LCD  1 , and meanwhile, the first and second electrodes  21  and  22  are electrically insulated with each other. Therefore, when the user&#39;s finger touches the surface of the upper substrate  10 , the capacitive effect generated at where the user&#39;s finger touches is decoded for variation of the capacitance, further locating where the user&#39;s finger touches. Besides, the touch signal transmission circuit  20  is directly prepared inside the LCD  1 , such that the LCD can be effectively thinned and lightened to meet the requirement that the electronic products are getting more and more compact. 
         [0023]      FIG. 6  shows a second preferred embodiment of the present invention which is similar to but different from the first embodiment by the corresponding relationship between the first electrodes  21 ′ and the first bonding pads  23 ′ and the corresponding relationship between the second electrodes  22 ′ and the second bonding pads  24 ′ of the touch signal transmission circuit  20 ′ of the second embodiment, i.e. each two electrodes share one bonding pad. Alternatively, the corresponding relationship between the electrodes and the bonding pads is subject to change as it depends on the actual requirement and such change thereof does not incur imperfect touch sensation because the electrodes are densely arranged and the area that the user&#39;s finger touches is larger, thus sensing the specific locations correctly. 
         [0024]    In addition, the first embodiment can have alternative structure as recited below. As shown in  FIG. 7 , not each of the masking elements  36  is embedded with one electrode  38  therein but the electrodes  38  are embedded into the corresponding masking elements  36  in a predetermined interval. Each of the electrodes  38  is also electrically connected with one bonding pad  40 . In this way, the expense of the material that the electrode is made of can be properly reduced without deterioration of the touch-sensitive effect. Further to the structure shown in  FIG. 7 , the second embodiment can also have alternative structure; referring to  FIG. 8 , each two electrodes share one bonding pad  40 . 
         [0025]    In the above structure of the LCD, the color filter is disposed on the upper substrate and then coordinates with the common substrate of the film transistor on array. The present invention is also applicable to the LCD under the process of the color filter on array (COA), i.e. the color filter is no longer installed in the upper substrate of the LCD having the touch signal transmission circuit therein. 
         [0026]    Although the present invention has been described with respect to specific preferred embodiments thereof, it is no way limited to the details of the illustrated structures but changes and modifications may be made within the scope of the appended claims.