Abstract:
A touch display device including a display, a touch panel and a transparent shielding layer is provided. The touch panel is disposed on the display, and includes a substrate and touch sensors positioned thereon. The transparent shielding layer is set between the display and the touch sensors of the touch panel, and includes an edge region and a central region wherein the impedance of the edge region is less than or equal to that of the central region.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of application Ser. No. 12/981,637, filed on Dec. 30, 2010. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates in general to a display device, and more particularly to a touch display device inhibiting electrostatic discharge. 
         [0004]    2. Description of the Related Art 
         [0005]    Touch panels have been widely applied to consumer electronics, such as communication handsets, notebooks, PDAs, digital cameras, etc. 
         [0006]    For a touch panel that is operated through a finger or touch pen, a problem of electrostatic interference or external noise would probably arise so that operating signals of other internal electronic components of the product would be influenced directly or indirectly. For example, in a liquid crystal display device having a touch panel, electrostatic discharge would get into the liquid crystal panel through a common electrode (Vcom) of the liquid crystal display device. That would damage a driving IC of the display device at worst and thus degrade the display quality. In addition, noise influencing the touch panel would be easily generated due to the common electrode of the liquid crystal display device driven by an alternating current. Thus, the touch panel would have false actions and a user cannot operate the device accurately. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    Embodiments of the present invention may provide a touch display device including a display device, a touch panel, and a transparent shielding layer. The touch panel is disposed on the display device. The touch panel includes a substrate and a touch sensor. The touch sensor is disposed on the substrate. The transparent shielding layer is disposed between the display device and the touch sensor. The transparent shielding layer includes an edge region and a central region. An impedance of the edge region is less than or equal to an impedance of the central region. 
         [0008]    In embodiments of the present invention, the touch display device may further include a low-impedance layer disposed in the edge region of the transparent shielding layer and grounded to the transparent shielding layer. 
         [0009]    The above and other aspects of the invention will become better understood with regard to the following detailed description of the preferred but non-limiting embodiment(s). The following description is made with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  shows a touch display device inhibiting electrostatic discharge according the embodiment of the present invention. 
           [0011]      FIG. 2  shows a touch display device in  FIG. 1  that further includes a transparent cover plate. 
           [0012]      FIG. 3  shows a variation of the touch display device in  FIG. 2 . 
           [0013]      FIG. 4  shows the touch sensor of the touch panel. 
           [0014]      FIG. 5A ,  FIG. 5B ,  FIG. 5C ,  FIG. 6A , and  FIG. 6B  show the different embodiments of the touch panel with single substrate. 
           [0015]      FIG. 7A  and  FIG. 7B  show the different embodiments of the touch panels with two substrates. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    In the present embodiment, a touch display device inhibiting electrostatic discharge is provided. The touch display device includes a touch panel and a display device parallel to each other. A transparent shielding layer is disposed between the touch panel and the display device, and a low-impedance layer is disposed at an edge region of the transparent shielding layer. The transparent shielding layer and the low-impedance layer are grounded in common so as to inhibit the noise and the electrostatic discharge. 
         [0017]      FIG. 1  shows a touch display device inhibiting electrostatic discharge according the embodiment of the present invention. Referring to  FIG. 1 , the touch display device  1  includes a touch panel  10 , an active array substrate  12 , a transparent shielding layer  14  and a low-impedance layer  16 . The active array substrate  12  is disposed parallel to the touch panel  10 . In this embodiment, the active array substrate  12  is a thin film transistor array substrate, and the touch panel  10  is a capacitive touch panel with a substrate and a touch sensor disposed thereon. The detailed structure will be described as the following. 
         [0018]    The transparent shielding layer  14  is disposed between the active array substrate  12  and the touch panel  10 . The transparent shielding layer  14  can be made of the same material as that of a sensing electrode (not shown in  FIG. 1 ) of the touch panel  10 , for example, ITO or other transparent conductive materials such as CTO, AZO, IZO, ZnO, SnO or a combination thereof. The transparent shielding layer  14  and the low-impedance layer  16  are grounded in common. The low-impedance layer  16  is disposed at an edge region of the transparent shielding layer, and between the transparent shielding layer  14  and the active array substrate  12 . The low-impedance layer  16  may be made of metal to form a metal ring surrounding the transparent shielding layer  14 . 
         [0019]    If only the ITO transparent shielding layer  14  is disposed, it would lead to a reduced shielding effect due to its high impedance. However, in the embodiment, the metallic low-impedance layer  16  disposed at the edge region of the transparent shielding layer  14  is common grounded with the transparent shielding layer  14  to improve the shielding effect. In other embodiments, the same effect can be achieved by using a transparent shielding layer  14  having an edge region with lower impedance and a central region with higher impedance. 
         [0020]    The touch display device  1  further includes a planar layer  18  covering the transparent shielding layer  14  and the low-impedance layer  16  to provide a disposition surface for other layers. 
         [0021]    The touch display device  1  can be a monochrome liquid crystal display or a color liquid crystal display. Preferably, the touch display device  1  further includes a color filter layer  20  and a liquid crystal layer  22 . The color filter layer  20  can be disposed between the touch panel  10  and the active array substrate  12 . The liquid crystal layer  22  may be disposed between the active array substrate  12  and the color filter layer  20 . In the present embodiment, the color filter layer  20  is disposed between the touch panel  10  and the transparent shielding layer  14 , and the liquid crystal layer  22  is disposed between the planar layer  18  and the active array substrate  12 . In addition, the color filter layer  20  is directly integrated with the touch panel  10  for reducing a whole thickness of the structure. 
         [0022]    The touch display device  1  further includes a common electrode  24  disposed under the planar layer  18  and connected to the active array substrate  12 . The transparent shielding layer  14  and the low-impedance layer  16  are disposed above the common electrode  24  to prevent electrostatic discharge generated on the touch panel  10  and external noise from entering the active array substrate  12  through the common electrode  24 . Therefore, electrical signals in a driving IC (not shown) or the active array substrate  12  would not be interfered by the electrostatic discharge or external noise. In addition, the touch display device  1  further includes two polarizing sheets  26  and  28 . The polarizing sheet  26  is adhered to a top surface of the touch panel  10 , and the polarizing sheet  28  is adhered to a bottom surface of the active array substrate  12 . 
         [0023]      FIG. 2  shows a touch display device of  FIG. 1  further including a transparent cover plate. As shown in  FIG. 2 , the transparent cover plate  11  is disposed between the polarizing sheet  26  and the color filter layer  20 . The transparent cover plate  11  is made of, for example, a material with high strength, scratch resistant and transmittance, such as glass, polyacrylate, engineering plastic, etc. 
         [0024]    The structure shown in  FIG. 2  may be varied based on demand for device arrangement and manufacturing process.  FIG. 3  shows a variation of the touch display device of  FIG. 2 . As shown in  FIG. 3 , the planar layer  18  is disposed under a bottom surface of the touch panel  10 . The low-impedance layer  16  and the transparent shielding layer  14  are disposed under a bottom surface of the planar layer  18 . The color filter layer  20  and the common electrode  24  are sequentially disposed under a bottom surface of the transparent shielding layer  14 . In this embodiment, the arrangement of the liquid crystal layer  22 , the active array substrate  12  and the polarizing sheet  28  are the same as that in  FIG. 2 . The transparent shielding layer  14  and the low-impedance layer  16  are still disposed between the common electrode  24  and the touch sensor of the touch panel  10  to inhibit the noise and the electrostatic discharge. 
         [0025]    The touch panel  10  of the present embodiment will be described in detail with regard to the following description. The touch panel  10  of the present embodiment may have a single substrate or two substrates. The following description is made with reference to the accompanying drawings. 
         [0026]      FIG. 4  shows the touch sensor of the touch panel. The touch sensor includes a plurality of first sensing electrodes  110  and a plurality second sensing electrodes  120 . The first sensing electrodes  110  are parallel to each other and evenly spaced. In addition, the first sensing electrodes  110  are extended along a first direction, such as a Y direction in  FIG. 4 . The second sensing electrodes  120  are parallel to each other and evenly spaced. In addition, the second sensing electrodes  120  are extended along a second direction perpendicular to the first direction, such as an X direction in  FIG. 4 . Each of the first sensing electrodes  110  includes a plurality of first electrode regions  112 . Each of the second sensing electrodes  120  includes a plurality of second electrode regions  122 . The first electrode region  112  and the second electrode region  122  may have any shape such as square, rectangle, rhombus, triangle, polygon, circle, ellipsoid, etc. In this embodiment, the electrode region has a rhombus shape. 
         [0027]    As shown in  FIG. 4 , the first electrode regions  112  and the second electrode regions  122  are arranged in stagger so as to define X and Y coordinates of the positions. As the first sensing electrodes  110  and the second sensing electrodes  120  are disposed on the single substrate, as shown in  FIG. 1  and  FIG. 3 , an insulating material may be disposed at a intersection point C of the first sensing electrode  110  and the second sensing electrode  120  to prevent short circuit between the first sensing electrode  110  and the second sensing electrode  120 . In another embodiment shown in  FIG. 2 , the first sensing electrode  110  and the second sensing electrode  120  are disposed on two substrates respectively. This kind of design does not concern short circuit at the intersection point C. Various structures of the touch panel  10  will be described in the following description. 
         [0028]    Various structures of the touch panel  10  at the intersection point C in  FIG. 4  are described in the following description.  FIG. 5A  shows a touch panel having a single substrate of the first kind. The first sensing electrode  110  and the second sensing electrode  120  are disposed on the same substrates  130 . As shown in  FIG. 5A , the first sensing electrode  110  is covered by an insulating layer  116 . The second electrode regions  122  adjacent to opposite sides of the first sensing electrode  110  are connected to each other by a conducting wire  124  on the insulating layer  116 . The second electrode regions  122  and the conducting wire  124  form a bridge island structure. Therefore, all of the second electrode regions  122  of the second sensing electrodes  120  are connected to each other, and short circuit problem is prevented by the insulating layer  116 . 
         [0029]    Moreover, the second electrode region  122  may be connected to an external circuit board, such as a flexible printed circuit (FPC)  128 , by a conducting wire  126 . The conducting wires  124 ,  126  are a metal or a transparent conducting material, such as ITO. The first sensing electrode  110 , the second sensing electrode  120  and the conducting wires  124 ,  126  are covered by a protecting layer  118 . The transparent shielding layer  14  that provides protecting function of electrostatic discharge is disposed under the bottom surface of the substrate  130  far away from the first sensing electrode  110  and the second sensing electrode  120 . The color filter layer  20  shown in  FIG. 1  is disposed between the substrate  130  and the transparent shielding layer  14 , or integrally formed on the substrate  130 . The low-impedance layer  16 , the planar layer  18 , the common electrode  24 , the liquid crystal layer  22  and the active array substrate  12  and so on are disposed under the transparent shielding layer  14 . 
         [0030]      FIGS. 5B and 5C  show touch panels having a single substrate of the second kind and the third kind, respectively. The first sensing electrode  110  and the second sensing electrode  120  are covered by the insulating layer  116  having a plurality of contact holes  116   a.  A part of a surface of the second electrode region  122  is exposed by the contact hole  116   a.  The conducting wire  124  is extended into the contact hole  116   a  and connected to the second electrode region  122 . The contact hole  116   a  is partially filled with the conducting wire  124 , as shown in  FIG. 5B , or is wholly filled with the conducting wire  124 , as shown in  FIG. 5C . The first sensing electrode  110 , the second sensing electrode  120 , the conducting wire  124  and so on are covered by the protecting layer  118 . 
         [0031]      FIG. 6A  and  FIG. 6B  show touch panels having a single substrate of the forth kind and the fifth kind, respectively. As shown in  FIG. 6A , the conducting wire  124  is directly disposed on the substrate  130 . In addition, a part of the conducting wire  124  is covered by the insulating layer  116 . The first sensing electrode  110  is disposed on the insulating layer  116  thereby being separated from the conducting wire  124 . A part of the insulating layer  116  is covered by the second sensing electrode  120 . The second electrode region  122  of the second sensing electrode  120  is connected to a part of the conducting wire  124  not covered by the insulating layer  116 . Therefore, all of the second electrode regions  122  of the second sensing electrodes  120  are connected to each other. The first sensing electrode  110 , the second sensing electrode  120 , etc., are covered by the protecting layer  118 . 
         [0032]    As shown in  FIG. 6B , the conducting wire  124  and the substrate  130  are covered by the insulating layer  116  with the contact hole  116   a.  A part of a surface of the conducting wire  124  is exposed by the contact hole  116   a.  The second electrode regions  122  adjacent to opposite sides of the first sensing electrode  110  are extended into the contact hole  116   a  and connected to the conducting wire  124 . Therefore, all of the second electrode regions  122  of the second sensing electrodes  120  are connected to each other. 
         [0033]    A touch panel  10  having two substrates is described as the following.  FIG. 7A  and  FIG. 7B  show touch panels having two substrates of the first kind and the second kind, respectively. The touch panel  10  has a first substrate  210  and a second substrate  220  parallel to each other. The first sensing electrode  110  is disposed on the first substrate  210 . The second sensing electrode  120  is disposed on the second substrate  220 . As shown in  FIG. 7A , the first sensing electrode  110  and the second sensing electrode  120  face to opposite directions whereby the first sensing electrode  110  faces the second sensing electrode  120 . The transparent shielding layer  14  is disposed adjacent to an external surface of the first substrate  210  (or the second substrate  220 ). The touch panel  10  further includes a spacer  230  for separating the first substrate  210  and the second substrate  220  in a distance. The first substrate  210  and the second substrate  220  may be adhered to each other by coating an optical adhesive  240  between the first substrate  210  and the second substrate  220 . 
         [0034]    As shown in  FIG. 7B , the first sensing electrode  110  and the second sensing electrode  120  are disposed facing to the same direction wherein the first sensing electrode  110  is disposed under a bottom surface of the first substrate  210 , and the second sensing electrode  120  is disposed under a bottom surface of the second substrate  220 . In addition, the first sensing electrode  110  is covered and protected by the whole insulating layer  250 . The transparent shielding layer  14  and the first sensing electrode  110  may be disposed on the same side of the first substrate  210 , and separated from each other by the insulating layer  250 . 
         [0035]    The touch panel  10  illustrated in  FIGS. 5A-7B  can be applied to the touch display device  1  of  FIG. 1 , or other touch electronic devices that be operated by touching, such as communication handsets, personal digital assistants, navigation apparatus, etc., for solving electrostatic discharge problems. In particular, the common grounded transparent shielding layer and the low-impedance layer disposed in the touch display device can inhibit the noise and the electrostatic discharge. Therefore, a false action due to interference of an electrical signal in the touch panel and the display device can be avoided. 
         [0036]    While the invention has been described by way of example and in terms of preferred embodiment(s), it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.