Patent Publication Number: US-2009231301-A1

Title: Touch panel and manufacturing method thereof

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This Non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 097108595 filed in Taiwan, Republic of China on Mar. 12, 2008, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present invention relates to a touch panel and a manufacturing method thereof. 
     2. Related Art 
     Recently, the touch panel has been widely applied to many kinds of electronic products, such as the mobile communication device, digital camera, MP3 player, PDA, GPS hand-held PC or ultra mobile PC (UMPC). Since the electronic products have been minimized, it is also a critical issue to decrease the area of the touch panel. 
       FIG. 1  shows a conventional touch screen  1 , and  FIG. 2  is a sectional view showing a part of the touch screen  1 . The touch panel  1  includes a substrate  11 , a resistive layer  12 , a conductive circuit layer  13 , a plurality of signal terminals  14 , a protective layer  15  and a plurality of signal lines  17 . The substrate  11  has a touch area T 1  and a peripheral area P 1  disposed around the touch area T 1 . The resistive layer  12  is disposed in the touch area T 1  and the peripheral area P 1  of the substrate  11 . The conductive circuit layer  13  and the signal terminals  14  are disposed in the peripheral area P 1  and electrically connected to the resistive layer  12 . The signal terminals  14  are located at the corners of the resistive layer  12 . The protective layer  15  covers the conductive circuit layer  13  and the signal terminals  14  for protection. One end of each signal line  17  is electrically connected to corresponding one of the signal terminals  14 , and the other end of each signal line  17  is electrically connected to a flat cable  18 . 
     The operation principle of the touch panel  1  will be described hereinafter. When the conductive circuit layer  13  is charged, the entire resistive layer  12  has an electric field with the distribution of the equipotential lines. If a user presses a position of the resistive layer  12 , the electric field of the resistive layer  12  changes and the signal terminals  14  located at the four corners will generate signals according to the variations. Then, the generated signals are transmitted to the backend through the signal lines  17  and the flat cable  18 , so that the pressed position can be obtained after the further process of the backend. 
     As mentioned above, the signal lines  17 , which are used for signal transmission, must be isolated with the conductive circuit layer  13  and the resistive layer  12 . The conventional methods for isolating the signal lines  17  will be described herein below. In the first method, the signal lines  17  are formed out of the scope of the resistive layer  12  such that it will increase the size of the entire touch panel  1 . The second method is to separate the signal lines  17  from the conductive circuit layer  13  and the resistive layer  12  by laser cutting such that it will complicate the manufacturing processes and require the additional cost of the cutting apparatus. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, it is an object of the present invention to provide a touch panel and manufacturing method thereof that can reduce the size thereof without additional process and apparatus so as to achieve the goals of minimization and low cost. 
     To achieve the above, the present invention discloses a touch panel includes a substrate, a resistive layer, a plurality of signal terminals, a conductive circuit layer, an insulation layer and a plurality of signal lines. The substrate has a touch area and a peripheral area. The signal terminals are disposed in the peripheral area and electrically connected to the resistive layer. The conductive circuit layer is disposed in the peripheral area and electrically connected to the resistive layer. The insulation layer is disposed on the signal terminals and the conductive circuit layer. The signal lines are disposed on the insulation layer and connected to the signal terminals, respectively. 
     In addition, the present invention further discloses a manufacturing method of a touch panel. The manufacturing method includes the following steps of: forming a resistive layer on a substrate, which has a touch area and a peripheral area; forming a conductive circuit layer in the peripheral area to be electrically connected to the resistive layer; forming a plurality of signal terminals in the peripheral area to be electrically connected to the resistive layer; forming an insulation layer on the conductive circuit layer and the signal terminals; and forming a plurality of signal lines on the insulation layer to be electrically connected to the signal terminals, respectively. 
     As mentioned above, in the touch panel and manufacturing method thereof of the present invention, the insulation layer is formed on the signal terminals and the conductive circuit layer, and then the signal lines are formed on the insulation layer. Thus, signal lines can be insulated from the conductive circuit layer and the resistive layer through the insulation layer. In addition, the elements of the touch panel are stacked vertically, so that the size of the tough panel can be reduced so as to achieve the goal of minimization. Moreover, the conventional cutting process as well as the cutting apparatus is not needed in the present invention, so the manufacturing cost can be decreased. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the subsequent detailed description and accompanying drawings, which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is a schematic illustration showing a conventional touch panel; 
         FIG. 2  is a sectional view showing a part of the conventional touch panel; 
         FIGS. 3A to 3C  are schematic illustrations showing various aspects of a touch panel according to a first embodiment of the present invention; 
         FIGS. 4A to 4B  are schematic illustrations showing various aspects of a touch panel according to a second embodiment of the present invention; and 
         FIGS. 5A to 5B  are schematic illustrations showing various aspects of a touch panel according to a third embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements. 
     First Embodiment 
       FIG. 3A  shows a touch panel  2  according to a first embodiment of the present invention. The touch panel  2  includes a substrate  21 , a resistive layer  22 , a conductive circuit layer  23 , a plurality of signal terminals  24 , an insulation layer  29  and a plurality of signal lines  27 . 
     The substrate  21  has a touch area T 2  and a peripheral area P 2  disposed around the touch area T 2 . In the embodiment, the substrate  21  can be, for example but not limited to, a glass substrate or a plastic substrate. The resistive layer  22  is formed to cover the touch area T 2  and the peripheral area P 2  of the substrate  21 . The material of the resistive layer  22  can be conductive metal oxide, such as indium tin oxide (ITO), indium zinc oxide (IZO), aluminum-doped zinc oxide (AZO), zinc gallium oxide (GZO) or zinc oxide (ZnO). 
     The conductive circuit layer  23  and the signal terminals  24  are formed in the peripheral area P 2  and electrically connected to the resistive layer  22 . The conductive circuit layer  23  includes discontinuous electrodes. The signal terminals  24  are corner electrodes for applying voltage to and receiving current from the touch panel  2 . The conductive circuit layer  23  and the signal terminals  24  are formed at the same time. In the embodiment, the resistive layer  22  covers the conductive circuit layer  23  and the signal terminals  24 . The conductive circuit layer  23  and the signal terminals  24  can be formed on the substrate  21  by coating, printing, adhering or deposition. The material of the conductive circuit layer  23  and the signal terminals  24  can be, for example, copper or silver glue. 
     The insulation layer  29  is formed on the signal terminals  24  and the conductive circuit layer  23  in the peripheral area P 2 , and is disposed on the resistive layer  22 . The signal lines  27  are formed on the insulation layer  29  by screen printing, and electrically connected to the signal terminals  24 , respectively. In the embodiment, the signal terminals  24  are exposed out of the insulation layer  29 , so that the signal lines  27  can be electrically connected to the signal terminals  24 . 
     In addition, the touch panel  2  further includes a protective layer  26  and a flat cable  28 . The protective layer  26  is disposed on the signal lines  27  and the insulation layer  29 . In the embodiment, the protective layer  26  can be a composite layer and is made of, for example, epoxy or silicon. The protective layer  29  can protect the conductive circuit layer  23  and the signal terminals  24 . The signal lines  27  are electrically connected to the flat cable  28  for transmitting signals to a backend for further signal processing. 
       FIG. 3B  shows another variation of the touch panel according to the first embodiment. As shown in  FIG. 3B , an insulation layer  29 A of the touch panel  2 A has a stepped shape, so that the signal lines  27  can be electrically connected to the signal terminals  24 , respectively. 
       FIG. 3C  shows further another variation of the touch panel according to the first embodiment. As shown in  FIG. 3C , the signal lines  27 B pass through vias H of the insulation layer  29 B so as to electrically be connected to the signal terminals  24 , respectively. Herein, the vias H can be formed by etching. 
     Second Embodiment 
     With reference to  FIG. 4A , a touch panel  3  according to a second embodiment of the present invention includes a substrate  31 , a resistive layer  32 , a conductive circuit layer  33 , a plurality of signal terminals  34 , a dielectric layer  35 , an insulation layer  39 , a plurality of signal lines  37  and a protective layer  36 .  FIG. 4A  shows only one signal terminal  34  and one signal line  37 . To be noted, the dielectric layer  35  is formed on the resistive layer  32 . In the embodiment, the dielectric layer  35  can include at least one hardening layer and/or at least one anti-reflective layer. For example, the hardening layer is formed first, and then the anti-reflective layer is formed so as to finish the formation of the dielectric layer  35 . Alternatively, the anti-reflective layer is formed first, and then the hardening layer is formed thereon so as to finish the formation of the dielectric layer  35 . Herein, a material of the anti-reflective layer includes silicon oxide (SiO), silicon nitride (SiN) or silicon nitrogen oxide (SiON). The connection between the signal lines  37  and the signal terminals  34  is similar to that of the signal lines  27  and the signal terminals  24  described in the first embodiment. 
       FIG. 4B  shows another variation of the touch panel according to the second embodiment. As shown in  FIG. 4B , a dielectric layer  35 A of the touch panel  3 A is mostly disposed on the touch area T 3  of the resistive layer  32 . 
     Third Embodiment 
     With reference to  FIG. 5A , a touch panel  4  according to a third embodiment of the present invention includes a substrate  41 , a resistive layer  42 , a conductive circuit layer  43 , a plurality of signal terminals  44 , a dielectric layer  45 , an insulation layer  49 , a plurality of signal lines  47  and a protective layer  46 .  FIG. 5A  shows only one signal terminal  44  and one signal line  47 . In this embodiment, the resistive layer  42  is formed on the substrate  41 . The conductive circuit layer  43  and the signal terminals  44  are formed on the resistive layer  42 . The dielectric layer  45  is formed on the conductive circuit layer  43 , the signal terminals  44  and the exposed resistive layer  42 . The insulation layer  49  is formed on the dielectric layer  45  in the periphery area P 4 . The signal lines  47  are formed on the insulation layer  49 . The protective layer  46  covers the signal lines  47 . The connection between the signal lines  47  and the signal terminals  44  is similar to that of the signal lines  27  and the signal terminals  24  described in the first embodiment. 
       FIG. 5B  shows another variation of the touch panel according to the third embodiment. As shown in  FIG. 5B , a dielectric layer  45 A of the touch panel  4 A is mostly disposed on the touch area T 4  of the resistive layer  42 . 
     In summary, in the touch panel and manufacturing method thereof of the present invention, the insulation layer is formed on the signal terminals and the conductive circuit layer, and then the signal lines are formed on the insulation layer. Thus, signal lines can be insulated with the conductive circuit layer and the resistive layer through the insulation layer. In addition, the elements of the touch panel are stacked vertically, so that the size of the tough panel can be reduced so as to achieve minimization. Moreover, the conventional cutting process as well as the cutting apparatus is not needed in the present invention, so the manufacturing cost can be decreased. 
     Although the present invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to persons skilled in the art. It is, therefore, contemplated that the appended claims will cover all modifications that fall within the true scope of the present invention.