Abstract:
A projected capacitive touch panel has a substrate and at least two sensing units. The sensing units form an active region as an operating zone for users. Because the active region is divided into smaller ranges, the path in which electric signals are transported becomes shorter. The electric signals can be outputted to an outer processor effectively. Additionally, when the projected capacitive touch panel of this invention is mounted on a display, the influence of the electromagnetic interference from the display can be decrease.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of the Taiwan patent application No. 100205143, filed on Mar. 23, 2011, the disclosure of which is incorporated herein in its entirety by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a capacitive touch panel, and more particularly to a projected capacitive touch panel. 
         [0004]    2. Description of Related Art 
         [0005]    With reference to U.S. patent publication No. 2010/0245285, a capacitive touch panel includes a transparent substrate, a plurality of first sensing electrode sets and second sensing electrode sets provided on the transparent substrate. Each first sensing electrode set includes a plurality of first sensing electrodes electrically coupled in series through a plurality of first wires. Each second sensing electrode set includes a plurality of second sensing electrodes. A color compensation layer having a mesh-like pattern is provided between the first sensing electrodes and the second sensing electrodes. The second wires cover part of the surface of the color compensation layer to couple the second sensing electrodes in series. 
         [0006]    To achieve the purpose of using a computer conveniently, a touch panel formed on a display takes the place of a traditional input device such as a keyboard or a mouse. 
         [0007]    A common type of touch panel is a projected capacitive touch panel. The projected capacitive touch panel mainly comprises a substrate and a sensing layer formed on a bottom surface of the substrate. The sensing layer is composed of multiple sensing wires and electrically connected to a processor via signal wires connected between the sensing layer and the processor. Because a human body will carry electric charges, when a human body touches a top surface of the substrate of the touch panel, a capacitive signal between the human body and the sensing layer changes. The capacitive signal is outputted to the processor via the signal wires. The processor will calculate the coordinates of a touch point on the touch panel touched by the person based on the capacitive signal. The processor will then change the scenes of the display accordingly. 
         [0008]    The display is composed of multiple electric components, such as a backlight module and a power module, and the arrangement of signal wires in the display is complicated. As the display is activated, the display will induce the electromagnetic interference around the touch panel. 
         [0009]    The sensing wires of the sensing layer and the signal wires formed on the touch panel may be spread widely and densely as a result of the size and arrangement of the signal wires. Therefore, the electromagnetic interference on the touch panel will be more obvious. Moreover, as the path of the sensing layer and the signal wires in which the electric signals are transported becomes longer, the wire resistance of the sensing layer and the signal wires are raised, causing more serious reduction of the electric signals. As a result, the sensitivity of the touch panel is decreased. 
       SUMMARY OF THE INVENTION 
       [0010]    An objective of the present invention is to provide a projected capacitive touch panel having a substrate and at least two sensing units. 
         [0011]    The substrate has two opposite surfaces. 
         [0012]    The at least two sensing units are formed on the surface of the substrate. The sensing units are electrically insulated from each other. Each sensing unit comprises multiple X-axis sensing wires, multiple Y-axis sensing wires and multiple driving wires. Each X-axis sensing wire intersects each Y-axis sensing wire. The driving wires are electrically connected to the X-axis sensing wires and the Y-axis sensing wires respectively. 
         [0013]    Another objective of the present invention is to provide a projected capacitive touch panel. The projected capacitive touch panel has a bottom substrate, at least two bottom sensing units, a top substrate, at least two top sensing units and an insulating-adherent layer. 
         [0014]    The bottom substrate has a top surface. 
         [0015]    The bottom sensing units are formed on the top surface of the bottom substrate, and each bottom sensing unit is insulated from each other. 
         [0016]    Each bottom sensing unit comprises multiple first axis sensing wires and multiple driving wires connected to the multiple first axis sensing wires respectively. 
         [0017]    The top substrate has a bottom surface. 
         [0018]    The top sensing units are formed on the bottom surface of the top substrate, and each top sensing unit is insulated from each other. Each top sensing unit comprises multiple second axis sensing wires and multiple driving wires connected to the multiple second axis sensing wires respectively. The multiple second axis sensing wires intersect the multiple first axis sensing wires. 
         [0019]    The insulating-adherent layer is formed between the bottom substrate and the top substrate to bind the bottom substrate to the top substrate and avoid the electric connection between the bottom substrate and the top substrate. 
         [0020]    In contrast to the description of related art, the at least two divided and insulated sensing units in this invention form an active region as a touch-sensing interface. After the dividing, the range of each sensing unit is decreased. The path in which the electric signals are transported is shortened. Therefore, the electromagnetic interference from the display is effectively improved, and the wire resistance of the sensing units is decreased, raising the sensitivity of the touch panel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  is a top view of two sensing units of a capacitive touch panel in accordance with the present invention; 
           [0022]      FIG. 2  is a top view of the projected capacitive touch panel with X-axis sensing wires and Y-axis sensing wires; 
           [0023]      FIG. 3  is a side view of a second embodiment of a capacitive touch panel in accordance with the present invention; and 
           [0024]      FIG. 4  is an exploded perspective view of a third embodiment of a capacitive touch panel in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0025]    With reference to  FIG. 1  and  FIG. 2 , a first embodiment of a projected capacitive touch panel in accordance with the present invention has a substrate  10  and at least two sensing units  20 . 
         [0026]    The substrate  10  has two opposite surfaces. The at least two sensing units  20  are formed on the same surface of the substrate  10 . The sensing units  20  are electrically insulated from each other and form an active region  200  as a touch-sensing interface. 
         [0027]    Each sensing unit  20  comprises multiple X-axis sensing wires  21 , multiple Y-axis sensing wires  22 , multiple driving wires  23  and multiple insulators  24 . Each X-axis sensing wire  21  vertically and insulatedly intersects each Y-axis sensing wire  22 . The driving wires  23  are electrically connected to the X-axis sensing wires  21  and the Y-axis sensing wires  22  respectively. The multiple X-axis sensing wires  21  and the multiple Y-axis sensing wires  22  are electrically connected to a processor via the driving wires  23 . Each X-axis sensing wire  21  is composed of multiple X-axis electrodes  210  and multiple X-axis connection bridges  211 . Each X-axis connection bridge  211  is connected between every two adjacent X-axis electrodes  210  respectively. Each Y-axis sensing wire  22  is composed of multiple Y-axis electrodes  220  and multiple Y-axis connection bridge  221 . Each Y-axis connection bridge  221  is connected between every two adjacent Y-axis electrodes  220  respectively. Each insulator  24  is formed between every intersection between the X-axis sensing wires  21  and the Y-axis sensing wires  22  to avoid the electric connection between the X-axis sensing wires  21  and the Y-axis sensing wires  22 . 
         [0028]    With reference to  FIG. 3 , in a second embodiment of the projected capacitive touch panel in accordance with the present invention, the two opposite surfaces of the substrate  10  stand for a top surface  101  and a bottom surface  102  respectively. The X-axis sensing wires  21  may be formed on the top surface  101 , and the Y-axis sensing wires  22  may be formed on the bottom surface  102 . The X-axis sensing wires  21  are not electrically connected to the Y-axis sensing wires  22 . 
         [0029]    With reference to  FIG. 4 , a third embodiment of the projected capacitive touch panel in accordance with the present invention has a bottom substrate  31 , at least two bottom sensing units  32 , a top substrate  33 , at least two top sensing units  34  and an insulating-adherent layer  35 . 
         [0030]    The bottom substrate  31  has a top surface. The bottom sensing units  32  are formed on the top surface of the bottom substrate  31 , and the bottom sensing units  32  are insulated from each other. The bottom sensing units  32  form an active region  300 . Each bottom sensing unit  32  comprises multiple first axis sensing wires  320  and multiple driving wires  321 . The driving wires  321  are electrically connected to the multiple first axis sensing wires  320  respectively. 
         [0031]    The top substrate  33  has a bottom surface. The top sensing units  34  are formed on the bottom surface of the top substrate  33 , and the top sensing units  34  are insulated from each other. Each top sensing unit  34  comprises multiple second axis sensing wires  340  and multiple driving wires  341 . The driving wires  341  are electrically connected to the multiple second axis sensing wires  340  respectively. The multiple second axis sensing wires  340  are vertically and insulatedly formed across the multiple first axis sensing wires  320 . If the axis of the first axis sensing wires  320  is X axis, the axis of the second axis sensing wires  340  will be Y axis. If the axis of the first axis sensing wires  320  is Y axis, the axis of the second axis sensing wires  340  will be X axis. 
         [0032]    The insulating-adherent layer  35  is applied between the bottom substrate  31  and the top substrate  33  to bind the bottom substrate  31  to the top substrate  33  and avoid the electric connection between the bottom substrate  31  and the top substrate  33 . 
         [0033]    With reference to  FIG. 1  and  FIG. 2  as an explanatory example, the active region  200  is composed of at least two divided sensing units  20  and the sensing units  20  are insulated from each other. Each sensing unit  20  has its own driving wires  23  electrically connected to the processor. According to the size of the whole substrate  10  and the active region  200 , because the active region  200  is divided into smaller ranges and also the sensing units  20  are formed on the smaller ranges respectively, the length of the sensing wires of the sensing units  20  is decreased. That means the path in which the electric signals are transported is shortened. Therefore, the electric signals can be effectively transported in the sensing units  20 , and the electromagnetic interference induced from the display can be effectively reduced. In addition, with the shortened path in which the electric signals are transported, the wire resistance is decreased. The transporting attenuation of the electric signals is improved. The sensitivity of the touch panel will be promoted, and the misoperations will be reduced thereof. 
         [0034]    The active region of the embodiments mentioned above is composed of two sensing units  20 . However, the active region can be composed of more sensing units  20 , according to practical demands such as the larger size of the touch panel. 
         [0035]    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 features of the invention, the disclosure is illustrative only. Changes may be made in the details, 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.