Patent Publication Number: US-2015084903-A1

Title: Touch display device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to touch display device. Specifically speaking, to a touch display device which is put together by a plurality of touch pads. 
     2. Description of the Prior Art 
     Nowadays, personal digital assistants (PDA), mobile phones, notebook computers, tablet PCs and other portable electronic products are wildly used in modern life. 
     Since these electronic products need to be thinner and lighter, the traditional input devices, such as keyboards or mice have to be replaced with other input devices. In addition, the needs for tablet PCs has greatly increased, hence the touch panel technology has become one of the key components in electronic products. 
     As the demands of the large-size touch pad have increased, the process for forming the large-size touch pad requires higher costs. Therefore, a method to reduce the cost of large-size touch pad is an important research objective. 
     SUMMARY OF THE INVENTION 
     The present invention provides a touch display device comprises four touch pads, the four touch pads forming a large-size touch pad, wherein each touch pad includes a substrate, an electrode pattern disposed on the substrate, the electrode pattern having a first edge and a second edge which is adjacent to the first edge, a periphery region defined on the substrate, and disposed surrounding the first edge and the second edge of the electrode pattern, a plurality of traces disposed within the periphery region, and a display device disposed on the large-size touch pad. 
     The touch display device of the present invention is formed from four smaller touch pads. Therefore, the manufacturing cost can be reduced since the total cost for forming four smaller touch pads respectively is lower than forming a large-size touch pad directly. In addition, in the present invention, the traces of each touch pad are not arranged between every two adjacent electrode patterns, so the active region of the touch display device will not be shrunk or influenced caused by the traces. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view diagram showing a conventional touch display device which is put together by a plurality of touch pads. 
         FIG. 2  is a top view diagram showing the touch display device of the present invention which is put together by a plurality of touch pads. 
         FIG. 3  is the 3D schematic diagram showing the touch display device of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     To provide a better understanding of the present invention to users skilled in the technology of the present invention, preferred embodiments are detailed as follows. The preferred embodiments of the present invention are illustrated in the accompanying drawings with numbered elements to clarify the contents and effects to be achieved. 
     Please note that the figures are only for illustration and the figures may not be to scale. The scale may be further modified according to different design considerations. When referring to the words “up” or “down” that describe the relationship between components in the text, it is well known in the art and should be clearly understood that these words refer to relative positions that can be inverted to obtain a similar structure, and these structures should therefore not be precluded from the scope of the claims in the present invention. 
       FIG. 1  is a top view diagram showing a conventional touch display device which is put together by a plurality of touch pads. As shown in  FIG. 1 , in conventional process, in order to reduce the cost, preferably, a plurality of smaller-size touch pads  10  are provided, and afterwards, these smaller-size touch pads  10  are put together into one large-size touch pad. Each smaller-size touch pad  10  comprises a substrate  12 , an electrode pattern  14  and a plurality of traces  16  disposed on the substrate  12 . After the smaller-size touch pads  10  are put together into a large-size touch pad  10 ′, a display device (not shown) is then covered on the large-size touch pad  10 ′, so as to complete the large-size touch display device. 
     Compared with the method of forming the large-size touch pad directly, the method mentioned above can effectively decrease the manufacturing cost. In other words, the total cost for forming four touch pads and then joining the four touch pads into one large-size touch pad is lower the cost for forming one large-size touch pad directly. However, in conventional process, the trace  16  of each touch pads  10  is usually arranged surrounding the electrode pattern  14  (usually, the traces will arranged along three or more different edges of the electrode pattern), therefore, the trace  16  will usually be disposed within the “putting together region” (which means the region that between every two adjacent electrode patterns after the smaller-size touch pads are put together into one large-size touch pad), and thereby forming some “non-active regions” A. The non-active regions A are accumulated by traces, and do not have touching functions, thereby decreasing the area of the active region of the touch display device. 
     An important feature of the present invention is that the traces of each touch pad are extended from only two different directions of the electrode pattern, and the traces will avoid being disposed within the “putting together region”. More precisely,  FIG. 2  is a top view diagram showing the touch display device of the present invention. As shown in  FIG. 2 , a large-size touch pad  100  is formed from four touch pads: a first touch pad  21 , a second touch pad  22 , a third touch pad  23  and a fourth touch pad  24 . The first touch pad  21  and the third touch pad  23  are arranged diagonally; and the second touch pad  22  and the fourth touch pad  24  are arranged diagonally. Each of the first touch pad  21  to the fourth touch pad  24  comprises a substrate  32 , an electrode pattern  34  and a plurality of traces  36  disposed on the substrate  32 . The electrode pattern  34  is made of transparent conductive materials, such as indium tin oxide (ITO), and includes a plurality of electrodes arranged along two different directions and crossed to each other. The traces  36  are usually made of materials with high conductivity (such as metals). The methods for forming the electrode pattern  34  and for forming the traces  36  are well known to persons of ordinary skills in the art and the details will not be described here. 
     It is noteworthy that in this embodiment, the first touch pad  21  has four different edges: a first edge  211 , a second edge  212 , a third edge  213  and a fourth edge  214 . Similarly, the second touch pad  22  has four different edges: a first edge  221 , a second edge  222 , a third edge  223  and a fourth edge  224 . The third touch pad  23  has four different edges: a first edge  231 , a second edge  232 , a third edge  233  and a fourth edge  234 . The fourth touch pad  24  has four different edges: a first edge  241 , a second edge  242 , a third edge  243  and a fourth edge  244 . It is noteworthy that in each touch pad, the first edge is adjacent to the second edge. The substrate  32  of each touch pad (including the first touch pad  21  to the fourth touch pad  24 ) has a periphery region B defined thereon, and the traces  36  are only disposed within the periphery region B. The periphery region B is only disposed surrounding the first edge and the second edge of each touch pad (including the first touch pad  21  to the fourth touch pad  24 ), but not disposed surrounding the third edge and the fourth edge of each touch pad. Taking the first touch pad  21  as an example, the traces  36  are only disposed on the substrate  32  surrounding the first edge  211  and the second edge  212 . On the other hand, since the periphery region B does not exist on the place surrounding the third edge  213  and the fourth edge  214 , the third edge  213  and the fourth edge  214  are closer to the edges of the substrate  32 , and the edges of the substrate  32  that are closer to the third edge  213  and the fourth edge  214  can be defined as the “putting together edge” of the first pad  21 , which means the putting together edge of one touch pad will directly contact the putting together edge of another touch pad after the large-size touch pad is formed. Similarly, the second touch pad  22 , the third touch pad  23 , and the fourth touch pad  24  also have the periphery region B defined on the substrates  32  respectively. And the traces  36  of the second touch pad  22 , the third touch pad  23 , and the fourth touch pad  24  are disposed within their periphery region B too. The edges that are closer to the third edge and the fourth edge can be defined as the putting together edges. In addition, each touch pad may selectively further comprise a shielding line  38  disposed on the substrate  32 , surrounding the electrode  34  and the traces  36  of each touch pad, to shield the noise of each touch pad. 
     The feature of the present invention is that one putting together edge of one touch pad will directly contact one putting together edge of another touch pad after the large-size touch pad is put together. And the traces  36  will not be disposed between every two adjacent electrode patterns  34  after the large-size touch pad is put together. As shown in  FIG. 2 , the third edge  213  of the first touch pad  21  is put together with the third edge  223  of the second touch pad  22 , and the fourth edge  214  of the first touch pad  21  is put together with the fourth edge  244  of the fourth touch pad  24 . The third edge  233  of the third touch  23  pad is put together with the third edge  243  of the fourth touch pad  24 , and the fourth edge  234  of the third touch pad  23  is put together with the fourth edge  224  of the second touch pad  22 . Therefore, after the large-size touch pad is put together, the periphery regions B are only disposed out of and surrounding the formed electrode pattern, but not disposed between every two adjacent electrode patterns. In this way, the non-active region will not be formed between the electrode patterns after the large-size touch pad is formed, thereby increasing the active region of the touch display device. 
     Besides, in the present invention, the structure of the first touch pad  21  is essentially the same as the structure of the third touch pad  23 , and the structure of the second touch pad  22  is essentially the same as the structure of the fourth touch pad  24 . In addition, the structure of the first touch pad  21  is essentially the same as the mirrored structure of the second touch pad  22 . In other words, in the present invention, the first touch pad  21  to the fourth touch pad  24  only comprise two different arrangement patterns of the electrode patterns and traces (the arrangement pattern mentioned here means the arrangement of the electrode pattern and the traces), and the one of the arrangement pattern is same as the mirrored structure of another arrangement pattern. However, in another embodiment of the present invention, there is only one arrangement pattern that is used. More precisely, a same photomask is used to form four same touch pads, and afterwards, two of these touch pads are overturned. Therefore, the mirrored structure of the arrangement pattern can be easily obtained. Therefore, in actual manufacturing process, the four touch pads can be formed through only one photomask, and then two of the touch pads are overturned, so as to put together the four touch pads into one large-size touch pad. Compared with the method of forming two different arrangement patterns with two different photomasks respectively, this method only use one photomask to form four touch pads, thereby simplifying the manufacturing process. 
     Please refer to  FIG. 3 ,  FIG. 3  is the 3D schematic diagram showing the touch display device of the present invention. After the first touch pad  21  to the fourth touch pad  24  are put together and to form the large-size touch pad  100 , a display device  40  is then covered on the large-size touch pad  100 , such as a liquid crystal display (LCD), but not limited thereto. In the present invention, the display device  40  is preferably a whole piece structure, and it can provide better display performance, but in another embodiment of the present invention, the display device  40  can also be formed from (put together by) a plurality of smaller-size display devices, and this should be included in the scope of the present invention. In addition, as shown in  FIG. 3 , after the first touch pad  21  to the fourth touch pad  24  are put together and to form the large-size touch pad  100 , parts of the electrode patterns and parts of the traces (such as the electrode patterns and the traces of the first touch pad  21  and the third touch pad  23 ) are disposed on one-side surface of the substrate  32 , and parts of the electrode patterns and parts of the traces (such as the electrode patterns and the traces of the second touch pad  22  and the fourth touch pad  24 ) are disposed on another-side surface of the substrate  32 . The present invention has some advantages such as having simple structure, having lower cost and decreasing the difficulties of the manufacturing process. 
     In summary, the touch display device of the present invention is formed from four smaller touch pads. Therefore, the manufacturing cost can be reduced since the total cost for forming four smaller touch pads respectively is lower than forming a large-size touch pad directly. In addition, in the present invention, the traces of each touch pad are not arranged between two adjacent electrode patterns, so the active region of the touch display device will not be shrunk or influenced caused by the traces. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.