Abstract:
A touch display device and a formation method thereof are provided. The touch display device includes a touch panel disposed on a first surface of a substrate of a display panel. A color filter layer is disposed on a second surface of the substrate. The touch panel includes a plurality of first and second conductive patterns arranged by two directions that are perpendicular to each other. A patterned isolation layer, having a first portion and a second portion, is formed over the first surface of the substrate, wherein the first portion is disposed at the intersection of the first and the second conductive patterns, and the second portion is disposed between the first and the second conductive patterns. The first portion has a height that is lower than a height of the second portion.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This Application claims priority of Taiwan Patent Application No. 100135463, filed on Sep. 30, 2011, the entirety of which is incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a touch display device, and in particular relates to reduced scratches during a dual-side process of a capacitive touch display device. 
     2. Description of the Related Art 
     Currently, there are two types of capacitive touch panels. One type of capacitive touch panel is an add-on touch panel, wherein the capacitive touch panel is disposed on the outside of a display panel. The add-on touch panel is formed from two glass substrates. One glass substrate is used for forming capacitive touch sensors thereon. Another glass substrate is used as a cover lens for protecting the capacitive touch sensors. Thus, a total thickness of a touch display device is increased due to the add-on touch panel. 
     Another type of capacitive touch panel is an on-color filter (CF) type touch panel. The on-CF typed touch panel has capacitive touch sensors formed on a backside of a color filter substrate of a display panel and then a glass substrate is used as a cover lens for protecting the capacitive touch sensor. Although one glass substrate is omitted in the on-CF type touch panel, the formed capacitive touch sensors on the backside of the color filter substrate are easy scratched in subsequent processes by a dual-side process of the color filter substrate. 
     Therefore, a touch panel which can overcome the above problems, by reducing a total thickness of a touch display device and reducing scratches of the capacitive touch sensors during the dual-side process of the color filter substrate at the same time is desired. 
     BRIEF SUMMARY OF THE INVENTION 
     According to an illustrative embodiment, a touch display device is provided. The touch display device comprises a display panel including a first substrate, having a first surface and an opposite second surface, and a color filter layer disposed on the second surface of the first substrate. The touch display device further comprises a touch panel disposed on the first surface of the first substrate. The touch panel comprises a plurality of first conductive patterns arranged along a first direction and disposed on the first surface of the first substrate. A plurality of second conductive patterns is arranged along a second direction perpendicular to the first direction and disposed on the first surface of the first substrate. A patterned isolation layer has a first portion and a second portion, wherein the first portion is disposed at an intersection of the first conductive patterns and the second conductive patterns, the second portion is disposed between the first conductive patterns and the second conductive patterns, and the first portion has a height that is lower than a height of the second portion. 
     According to an illustrative embodiment, a method of forming a touch display device is provided. The method comprises providing a first substrate, having a first surface and an opposite second surface, and forming a touch panel on the first surface of the first substrate. The steps of forming the touch panel comprise forming a plurality of first conductive patterns on the first surface of the first substrate, arranged along a first direction. A plurality of second conductive patterns is formed on the first surface of the first substrate, arranged along a second direction perpendicular to the first direction. An isolation layer is coated over the first surface of the first substrate. Then, a half-tone mask is provided for performing an exposure and a development process to the isolation layer to form a patterned isolation layer, wherein the patterned isolation layer includes a first portion and a second portion, the first portion is formed at an intersection of the first conductive patterns and the second conductive patterns, the second portion is formed between the first conductive patterns and the second conductive patterns, and the first portion has a height that is lower than a height of the second portion. 
     A detailed description is given in the following embodiments with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
         FIG. 1  shows an illustrative cross section of a touch display device according to an embodiment of the invention; 
         FIG. 2  shows an illustrative top view of a portion of a touch panel according to an embodiment of the invention; 
         FIG. 3A  shows an illustrative cross section of a touch panel along the cross section line  3 - 3 ′ of  FIG. 2  according to an embodiment of the invention; 
         FIG. 3B  shows an illustrative cross section of a touch panel along the cross section line  3 - 3 ′ of  FIG. 2  according to another embodiment of the invention; 
         FIG. 4  shows an illustrative top view of a portion of a touch panel according to another embodiment of the invention; 
         FIG. 5A  shows an illustrative cross section of a touch panel along the cross section line  5 - 5 ′ of  FIG. 4  according to an embodiment of the invention; 
         FIG. 5B  shows an illustrative cross section of a touch panel along the cross section line  5 - 5 ′ of  FIG. 4  according to another embodiment of the invention; 
         FIGS. 6A-6D  show illustrative cross sections of intermediate processes of forming the touch panel of  FIG. 5A  according to an embodiment of the invention; 
         FIGS. 7A-7D  show illustrative cross sections of intermediate processes of forming the touch panel of  FIG. 5B  according to an embodiment of the invention; 
         FIG. 8  shows an illustrative top view of a portion of a capacitive touch panel known by the inventors; and 
         FIG. 9  shows an illustrative cross section of a capacitive touch panel along the cross section line  9 - 9 ′ of  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. 
     In embodiments of the invention, projective type capacitive touch display devices are provided. The touch display device includes a capacitive touch panel firstly formed on a backside of an upper substrate of a display panel. A color filter layer or other element is formed on a front side of the upper substrate of the display panel and then the fabrication of the display panel is completed. In the embodiments of the invention, a structure design of a capacitive touch panel is used in the touch display devices to prevent the touch panel from scratching during a dual-side process of the upper substrate of the display panel. According to the embodiments, one glass substrate is omitted from the touch display device and a total thickness of the touch display device is decreased. Moreover, the fabrication yield of the touch display device is improved. 
     Firstly, referring to  FIGS. 8 and 9 ,  FIG. 8  shows a top view of a portion of a capacitive touch panel  208  which is known by the inventors. The capacitive touch panel  208  has a plurality of sensing electrodes  210 X arranged along an X direction and a plurality of sensing electrodes  210 Y arranged along a Y direction. In which, the sensing electrodes  210 X are directly connected with each other and the sensing electrodes  210 Y are electrically connected by a metal bridge structure  212 . In order to prevent a short from occurring at the intersection of the sensing electrodes  210 X and the sensing electrodes  210 Y, an isolation structure  214  is disposed between the metal bridge structure  212  and a connective part of the sensing electrodes  210 X. 
       FIG. 9  shows a cross section of the capacitive touch panel  208  along the cross section line  9 - 9 ′ of  FIG. 8 . The touch panel  208  is formed on a surface  100 A of a substrate  100 . The isolation structure  214  is disposed between the metal bridge structure  212  and the connective part of the sensing electrodes  210 X. Therefore, after a protective layer  220  is formed to cover the sensing electrodes  210 X and the sensing electrodes  210 Y, the touch panel  208  has a height at the location of the isolation structure  214  that is higher than the heights at other positions. Thus, when a color filter layer  203  is formed on another surface  100 B of the substrate  100 , a protrusive portion P of the touch panel  208  is easily scratched or damaged which causes the touch panel  208  to malfunction. 
     Accordingly, in the embodiment of the invention, an improved structure design of the touch panel of the projective type capacitive touch display device is provided to reduce scratches on the touch panel during the dual-side process of the upper substrate of the display panel. 
     Referring to  FIG. 1 , a cross section of a touch display device  200  according to an embodiment of the invention is shown. The touch display device  200  includes a touch panel  108  disposed on a surface  100 A of an upper substrate  100  of a display panel. A color filter layer  103  or other element layer is formed on another surface  100 B of the upper substrate  100 . The display panel further includes a lower substrate  102  disposed opposite to the upper substrate  100 . Further, a display element  104  is sandwiched between the upper substrate  100  and the lower substrate  102 . Moreover, a cover lens  106 , for example a glass substrate or a plastic substrate, may be disposed on the outside of the touch panel  108  to prevent the fingers of a user or a touch pen  202  to scratch the touch panel  108 . 
       FIG. 2  shows a top view of a portion of the touch panel  108  according to an embodiment of the invention. The touch panel  108  includes a plurality of conductive patterns  110 X arranged along an X direction and a plurality of conductive patterns  110 Y arranged along a Y direction for use as sensing electrodes. The conductive patterns  110 X are connected with each other to form a row and the conductive patterns  110 Y are also connected with each other to form a column. An isolation structure  114  is disposed at the intersection of the conductive patterns  110 X and the conductive patterns  110 Y. The isolation structure  114  is also disposed between the conductive patterns  110 X and the conductive patterns  110 Y to prevent a short from occurring at the intersection of the conductive patterns  110 X and the conductive patterns  110 Y. The materials of the conductive patterns  110 X and the conductive patterns  110 Y are transparent conductive materials, for example indium tin oxide (ITO). The shapes of the conductive patterns  110 X and the conductive patterns  110 Y may be a rhombus or other shapes. 
     According to an embodiment of the invention, a dummy transparent conductive pattern  110 D is disposed between the conductive pattern  110 X and the conductive pattern  110 Y. The material of the dummy transparent conductive pattern  110 D is for example indium tin oxide (ITO). The dummy transparent conductive pattern  110 D, the conductive pattern  110 X and the conductive pattern  110 Y are electrically isolated from each other. Moreover, a dummy isolation structure  116  is disposed between the conductive patterns  110 X and the conductive patterns  110 Y. The dummy isolation structure  116  may be disposed under or over the dummy transparent conductive pattern  110 D. The dummy isolation structure  116  has a height that is higher than a height of the isolation structure  114 , such that a portion of the conductive pattern  110 X over the isolation structure  114  is not scratched. In an embodiment, the materials of the isolation structure  114  and the dummy isolation structure  116  are insulating photosensitive materials, for example a photo resist. The shapes of the isolation structure  114  and the dummy isolation structure  116  may be an island, and a size of the isolation structure  114  is slightly larger than the size of the dummy isolation structure  116 . 
       FIG. 3A  shows a cross section of the touch panel  108  along the cross section line  3 - 3 ′ of  FIG. 2  according to an embodiment of the invention. As shown in  FIG. 3A , the conductive patterns  110 X, the conductive patterns  110 Y and the dummy transparent conductive patterns  110 D are disposed on the surface  100 A of the substrate  100 . The isolation structure  114  is disposed at the intersection of the conductive patterns  110 X and the conductive patterns  110 Y for electrically isolating a connection portion of the conductive patterns  110 X from a connection portion of the conductive patterns  110 Y. The dummy isolation structure  116  is disposed over the dummy transparent conductive patterns  110 D. A height H 1  of the isolation structure  114  is lower than a height H 2  of the dummy isolation structure  116 . In an embodiment, the height H 1  is below about 50% that of the height H 2 . 
     The surface  100 A of the substrate  100  is completely covered with a protective layer  120 . The material of the protective layer  120  is for example acrylic resin, silicon nitride, silicon oxide or silicon oxynitride. As shown in  FIG. 3A , a height H 3  of a portion of the protective layer  120  over the dummy isolation structure  116  is higher than a height H 4  of a portion of the protective layer  120  over the isolation structure  114 . In an embodiment, a difference between the height H 3  and the height H 4  is about 200 nm. Therefore, scratches occurring at the intersection of the conductive patterns  110 X and the conductive patterns  110 Y are effectively reduced by the structure design of the touch panel  108  of the embodiment. 
       FIG. 3B  shows a cross section of the touch panel  108  along the cross section line  3 - 3 ′ of  FIG. 2  according to another embodiment of the invention. The difference between the touch panel  108  of  FIG. 3B  and the touch panel  108  of  FIG. 3A  is the dummy isolation structure  116  directly disposed on the surface  100 A of the substrate  100  and the dummy transparent conductive patterns  110 D disposed over the dummy isolation structure  116 . Similarly, a height of the isolation structure  114  is lower than a height of the dummy isolation structure  116 . Moreover, a height of a portion of the protective layer  120  over the dummy isolation structure  116  is higher than a height of a portion of the protective layer  120  over the isolation structure  114 . Therefore, scratches occurring at the intersection of the conductive patterns  110 X and the conductive patterns  110 Y are also effectively reduced by the structure design of the touch panel  108  of  FIG. 3B . 
     In another embodiment, no dummy transparent conductive pattern  110 D is disposed between the conductive patterns  110 X and the conductive patterns  110 Y. Only the dummy isolation structure  116  is formed on the surface  100 A of the substrate  100  and between the conductive patterns  110 X and the conductive patterns  110 Y. 
       FIG. 4  shows a top view of a portion of a touch panel  108  according to an embodiment of the invention. The touch panel  108  includes a plurality of conductive patterns  110 X arranged along an X direction for use as sensing electrodes. The conductive patterns  110 X are directly connected with each other to form a row. The touch panel  108  further includes a plurality of conductive patterns  110 Y arranged along a Y direction for use as sensing electrodes. The conductive patterns  110 Y are separated from each other and electrically connected with each other by a bridge structure  112  to form a column. Moreover, an isolation structure  114  is disposed between the bridge structure  112  and a connection portion of the conductive patterns  110 X to prevent a short from occurring at the intersection of the conductive patterns  110 X and the conductive patterns  110 Y. The materials of the conductive patterns  110 X and the conductive patterns  110 Y are transparent conductive materials, for example indium tin oxide (ITO). The shapes of the conductive patterns  110 X and the conductive patterns  110 Y may be a rhombus or other shapes. The material of the bridge structure  112  may be a transparent conductive material or a metal material. The transparent conductive material is for example indium tin oxide (ITO). 
     According to an embodiment of the invention, a dummy transparent conductive pattern  110 D is disposed between the conductive pattern  110 X and the conductive pattern  110 Y. The material of the dummy transparent conductive pattern  110 D is for example indium tin oxide (ITO). The dummy transparent conductive pattern  110 D, the conductive pattern  110 X and the conductive pattern  110 Y are electrically isolated from each other. Moreover, a dummy isolation structure  116  is disposed between the conductive patterns  110 X and the conductive patterns  110 Y. The dummy isolation structure  116  can be disposed under or over the dummy transparent conductive pattern  110 D. The dummy isolation structure  116  has a height that is higher than a height of the isolation structure  114  over the bridge structure  112 , such that it can effectively prevent scratches from occurring at the location of the bridge structure  112 . In an embodiment, the materials of the isolation structure  114  and the dummy isolation structure  116  are insulating photosensitive materials, for example a photo resist. The shapes of the isolation structure  114  and the dummy isolation structure  116  may be an island, and a size of the isolation structure  114  is the same as or different from a size of the dummy isolation structure  116 . 
       FIG. 5A  shows a cross section of the touch panel  108  along the cross section line  5 - 5 ′ of  FIG. 4  according to an embodiment of the invention. As shown in  FIG. 5A , the bridge structure  112 , the conductive patterns  110 X, the conductive patterns  110 Y and the dummy transparent conductive patterns  110 D are disposed on the surface  100 A of the substrate  100 . The conductive patterns  110 Y are electrically connected with each other by the bridge structure  112 . The isolation structure  114  is disposed on the bridge structure  112  for electrically isolating the connection portion of the conductive patterns  110 X from the bridge structure  112 . The dummy isolation structure  116  is disposed over the dummy transparent conductive patterns  110 D. A height H 5  of the isolation structure  114  is lower than a height H 2  of the dummy isolation structure  116 . In an embodiment, the height H 5  is about 50% that of the height H 2 . 
     The surface  100 A of the substrate  100  is completely covered with a protective layer  120 . The material of the protective layer  120  is for example acrylic resin, silicon nitride, silicon oxide or silicon oxynitride. As shown in  FIG. 5A , a height H 3  of a portion of the protective layer  120  over the dummy isolation structure  116  is higher than a height H 4  of a portion of the protective layer  120  over the isolation structure  114 . In an embodiment, a difference between the height H 3  and the height H 4  is about 200 nm. Therefore, scratches occurring at the location of the bridge structure  112  are effectively reduced by the structure design of the touch panel  108  of the embodiment. 
       FIG. 5B  shows a cross section of the touch panel  108  along the cross section line  5 - 5 ′ of  FIG. 4  according to another embodiment of the invention. The difference between the touch panel  108  of  FIG. 5B  and the touch panel  108  of  FIG. 5A  is the dummy isolation structure  116  directly disposed on the surface  100 A of the substrate  100  and the dummy transparent conductive patterns  110 D disposed over the dummy isolation structure  116 . Similarly, a height of the isolation structure  114  is lower than a height of the dummy isolation structure  116 . Moreover, a height of a portion of the protective layer  120  over the dummy isolation structure  116  is higher than a height of a portion of the protective layer  120  over the isolation structure  114 . Therefore, scratches occurring at the location of the bridge structure  112  are effectively reduced by the structure design of the touch panel  108  of  FIG. 5B . 
     In another embodiment, no dummy transparent conductive pattern  110 D is disposed between the conductive patterns  110 X and the conductive patterns  110 Y. Only the dummy isolation structure  116  is formed on the surface  100 A of the substrate  100  and between the conductive patterns  110 X and the conductive patterns  110 Y. 
       FIGS. 6A-6D  show cross sections of intermediate processes of forming the touch panel  108  of  FIG. 5A  according to an embodiment of the invention. 
     Referring to  FIG. 6A , firstly, a substrate  100  is provided. The substrate  100  is an upper substrate of a display panel, for example a color filter substrate. A transparent conductive layer or a metal layer is deposited on a surface  100 A of the substrate  100 . Then, the transparent conductive layer or the metal layer is patterned by a photolithography and etching process to form the bridge structure  112 . Next, a transparent conductive layer is deposited on the surface  100 A of the substrate  100 . Then, the transparent conductive layer is patterned by a photolithography and etching process to form the conductive patterns  110 Y and the dummy transparent conductive patterns  110 D. The conductive patterns  110 Y are used for Y-direction sensing electrodes of the touch panel  108 . 
     Referring to  FIG. 6B , the surface  100 A of the substrate  100  is completely coated with an isolation layer. Then, a halftone mask  130  is provided above the isolation layer. The halftone mask  130  may be a gray photo mask, a halftone photo mask or a photo mask with slits. The halftone mask  130  has a transparent pattern  130 C, a translucent pattern  130 A and an opaque pattern  130 B. A patterned isolation layer is formed by using the halftone mask  130  to perform an exposure and a development process to the isolation layer. The patterned isolation layer includes the isolation structure  114  formed on the bridge structure  112  and the dummy isolation structure  116  formed on the dummy transparent conductive patterns  110 D. The isolation structure  114  is corresponded to the translucent pattern  130 A, the dummy isolation structure  116  is corresponded to the opaque pattern  130 B and a portion of the isolation layer corresponding to the transparent pattern  130 C is completely removed. Because the halftone mask  130  is used to perform the exposure and the development process to the isolation layer, the isolation structure  114  and the dummy isolation structure  116  are formed at the same time. Moreover, a height of the isolation structure  114  is lower than a height of the dummy isolation structure  116 . 
     Referring to  FIG. 6C , a transparent conductive layer is deposited on the surface  100 A of the substrate  100 . Then, the transparent conductive layer is patterned by a photolithography and etching process to form the conductive patterns  110 X. The conductive patterns  110 X are used for X-direction sensing electrodes of the touch panel  108 . 
     Referring to  FIG. 6D , the surface  100 A of the substrate  100  is completely coated with the protective layer  120  to complete the touch panel  108  as shown in  FIG. 5A . A height of the isolation structure  114  disposed on the bridge structure  112  is lower than a height of the dummy isolation structure  116 . Therefore, after forming the protective layer  120 , a height of a portion of the protective layer  120  over the isolation structure  114  is also lower than a height of a portion of the protective layer  120  over the dummy isolation structure  116 . When a color filter layer  103  or other element layer is formed on another surface  100 B of the substrate  100 , the structure design of the touch panel  108  can effectively prevent or reduce the portion of the touch panel  108  at the location of the bridge structure  112  from scratching. Thus, it can prevent the touch panel  108  from failing. 
     Then, as shown in  FIG. 1 , a substrate  102 , for example a thin-film transistor (TFT) array substrate, is provided opposite to the surface  100 B of the substrate  100 . Further, a display element  104 , for example a liquid crystal layer, is sandwiched between the substrate  100  and the substrate  102  to form the display panel. Moreover, a cover lens  106 , for example a glass substrate or a plastic substrate, may be formed on the outside of the touch panel  108  to complete the fabrication of a touch display device  200 . 
       FIGS. 7A-7D  show cross sections of intermediate processes of forming the touch panel  108  of  FIG. 5B  according to an embodiment of the invention. 
     Referring to  FIG. 7A , firstly, a substrate  100  is provided. The substrate  100  is an upper substrate of a display panel, for example a color filter substrate. A transparent conductive layer or a metal layer is deposited on a surface  100 A of the substrate  100 . Then, the transparent conductive layer or the metal layer is patterned by a photolithography and etching process to form the bridge structure  112 . 
     Referring to  FIG. 7B , the surface  100 A of the substrate  100  is completely coated with an isolation layer. Then, a halftone mask  130  is provided above the isolation layer. The halftone mask  130  may be a gray photo mask, a halftone photo mask or a photo mask with slits. The halftone mask  130  has a transparent pattern  130 C, a translucent pattern  130 A and an opaque pattern  130 B. A patterned isolation layer is formed by using the halftone mask  130  to perform an exposure and a development process to the isolation layer. The patterned isolation layer includes the isolation structure  114  formed on the bridge structure  112  and the dummy isolation structure  116  formed on the surface  100 A of the substrate  100 . As shown in  FIG. 4 , the dummy isolation structure  116  is disposed between the conductive patterns  110 X and the conductive patterns  110 Y. The isolation structure  114  is corresponded to the translucent pattern  130 A and the dummy isolation structure  116  is corresponded to the opaque pattern  130 B. Because the halftone mask  130  is used to perform the exposure and the development process to the isolation layer, the isolation structure  114  and the dummy isolation structure  116  are formed at the same time. Moreover, a height of the isolation structure  114  is lower than a height of the dummy isolation structure  116 . 
     Referring to  FIG. 7C , a transparent conductive layer is deposited on the surface  100 A of the substrate  100 . Then, the transparent conductive layer is patterned by a photolithography and etching process to form the conductive patterns  110 Y, the conductive patterns  110 X and the dummy transparent conductive patterns  110 D at the same time. The conductive patterns  110 Y are separated from each other and electrically connected by the bridge structure  112 . The conductive patterns  110 Y are used for Y-direction sensing electrodes of the touch panel  108 . The conductive patterns  110 X are directly connected with each other, which are used for X-direction sensing electrodes of the touch panel  108 . The dummy transparent conductive pattern  110 D is formed on the dummy isolation structure  116  and disposed between the conductive pattern  110 X and the conductive pattern  110 Y as shown in  FIG. 4 . The dummy transparent conductive pattern  110 D is also isolated from conductive pattern  110 X and the conductive pattern  110 Y. 
     Referring to  FIG. 7D , the surface  100 A of the substrate  100  is completely coated with the protective layer  120  to complete the touch panel  108  as shown in  FIG. 5B . A height of the isolation structure  114  disposed on the bridge structure  112  is lower than a height of the dummy isolation structure  116 . Therefore, after forming the conductive patterns  110 Y, the conductive patterns  110 X, the dummy transparent conductive patterns  110 D and the protective layer  120 , a height of a portion of the protective layer  120  at the location of the bridge structure  112  is also lower than a height of a portion of the protective layer  120  over the dummy isolation structure  116 . When a color filter layer  103  or other element layer is formed on another surface  100 B of the substrate  100 , the structure design of the touch panel  108  can effectively prevent or reduce the portion of the touch panel  108  at the location of the bridge structure  112  from scratching or crushing. Thus, it can prevent the touch panel  108  from failing. 
     Then, as shown in  FIG. 1 , a substrate  102 , for example a thin-film transistor (TFT) array substrate, is provided opposite to the surface  100 B of the substrate  100 . Furthermore, a display element  104 , for example a liquid crystal layer, is sandwiched between the substrate  100  and the substrate  102  to form the display panel. Moreover, a cover lens  106 , for example a glass substrate or a plastic substrate, may be formed on the outside of the touch panel  108  to complete the fabrication of a touch display device  200 . 
     In summary, the touch display devices of the embodiments are fabricated by forming a touch panel on a backside of an upper substrate of a display panel. Therefore, one glass substrate is omitted from the touch display device and a total thickness of the touch display device is decreased. Moreover, in the embodiments of the invention, a structure design of a dummy isolation structure is used in the touch panel to make a highest portion of the touch panel to be located on the dummy isolation structure. Thus, when a dual-side process is performed on the upper substrate of the display panel, the structure design of the dummy isolation structure can effectively prevent or reduce the intersection of two-direction sensing electrodes of the touch panel from scratching or crushing. Further, it can prevent the touch panels from failing and enhance the fabrication yield of the touch display devices. 
     While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.