Patent Publication Number: US-2015077648-A1

Title: Touch panel

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwan application Ser. No. 102133954, filed on Sep. 18, 2013. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
     BACKGROUND OF THE INVENTION 
     1. [Field of the Invention] 
     The invention relates to a touch panel and particularly relates to a touch panel with a decoration pattern. 
     2. [Description of Related Art] 
     With the rapid development of electronic technology, many information products have changed their input devices from traditional keyboards or mice to touch apparatuses. Therefore, touch panels have been widely used. Currently, the development of many mobile electronic products trends to the use of touch display panels, that is, technology of integrating the touch panel with the display panel. 
     Generally speaking, multiple wires are disposed at the periphery of the touch panel to transmit sensing signals generated from the user&#39;s operations of the touch panel. To keep the wires from being seen by the user, a decoration pattern is usually disposed on the touch panel at a position corresponding to the layout of the wires for covering the wires and embellishing the appearance of the touch panel. 
     The decoration pattern has a specific thickness. Thus, when disposing the decoration pattern on the substrate of the touch panel, the decoration pattern protrudes from the substrate surface to form a height difference. Such a height difference may easily cause disconnection of the wires in the subsequent fabricating processes of the touch sensing element, which results in low yield rate. In addition, the height difference also causes difficulty in bonding other films or layers to the substrate. 
     SUMMARY OF THE INVENTION 
     The invention provides a touch panel formed with a covering layer for disposing a touch sensing element on a flattened surface, and thus has a favorable fabrication yield rate. 
     The invention provides a touch panel that includes a substrate, a decoration pattern, a covering layer, and a touch sensing element. The substrate has a first region and a second region. The decoration pattern is disposed on the first region of the substrate and has a first thickness. The covering layer includes a first portion that covers the second region of the substrate and a second portion that covers the decoration pattern. The second portion has a second thickness. The first portion has a third thickness. The second thickness is less than the third thickness. The touch sensing element is disposed on the covering layer and the decoration pattern. 
     In an embodiment of the invention, the third thickness is equal to a total of the first thickness and the second thickness. 
     In an embodiment of the invention, a material of the covering layer includes an insulating material. 
     In an embodiment of the invention, the insulating material includes a thermosetting resin or a UV-curable resin. 
     In an embodiment of the invention, the touch panel further includes an adhesive layer. The adhesive layer is adhered between the covering layer and the touch sensing element, wherein the touch sensing element includes a base and a touch sensing electrode layer, and the base is disposed between the adhesive layer and the touch sensing electrode layer. 
     In an embodiment of the invention, the touch sensing element includes a touch sensing electrode layer disposed directly on the covering layer. 
     Based on the above, according to the invention, the covering layer is disposed to moderate the effect caused by the height difference between the decoration pattern and the substrate. The covering layer moderates the height difference at the substrate surface to form a flattened surface, which facilitates fabrication and configuration of the touch sensing element and improves the fabrication yield rate of the touch panel. 
     To make the aforementioned and other features and advantages of the invention more comprehensible, several embodiments accompanied with drawings are described in detail as follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
         FIG. 1  is a cross-sectional view of a touch panel according to an embodiment of the invention. 
         FIG. 2  is a cross-sectional view of a touch panel according to another embodiment of the invention. 
         FIG. 3  is a cross-sectional view of a touch panel according to further another embodiment of the invention. 
         FIG. 4  is a cross-sectional view of a touch panel according to still another embodiment of the invention. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
       FIG. 1  is a cross-sectional view of a touch panel according to an embodiment of the invention. With reference to  FIG. 1 , a touch panel  100   a  includes a substrate  102 , a decoration pattern  110 , a covering layer  120   a,  and a touch sensing element  130   a . The substrate  102  has a first region  102   a  and a second region  102   b.  Here, the first region  102   a  and the second region  102   b  are two regions adjacent to each other. The first region  102   a  can be deemed as a region disposed at a periphery of the second region  102   b.  That is, the first region  102   a  can surround the second region  102   b.  Therefore,  FIG. 1  illustrates that the first region  102   a  is disposed at two opposite sides of the second region  102   b;  however, it should be noted that the invention is not limited thereto. 
     In some other embodiments, the first region  102   a  may be disposed at only one side of the second region  102   b.    
     The decoration pattern  110  is disposed on the first region  102   a  of the substrate  102  and has a first thickness d 1 . The decoration pattern  110  is disposed for decoration, so as to generate a desired visual effect. That is to say, a region where the decoration pattern  110  is located is a non-translucent region of the touch panel  100   a,  for example. Because the decoration pattern  110  has a function of shielding/blocking light, peripheral wirings of the touch panel  100   a  or components that should not be seen by the user may be disposed in the region where the decoration pattern  110  is located. Accordingly, the decoration pattern  110  can cover the peripheral wirings and partial components disposed in the first region  102   a  when the substrate  102  is located between the users and the decoration pattern  110  to provide a favorable appearance. 
     Furthermore, the decoration pattern  110  may have a specific design, so that the decoration pattern  110  can not only provide the shielding function but also embellish the appearance of the touch panel  100 . The decoration pattern  110  is an organic photoresist layer, an ink layer, or other suitable decoration material layers, for example. For instance, the decoration pattern  110  may be a white resin layer, a black resin layer, or other colored resin layers. Or, the decoration pattern  110  may be a black ink layer, a white ink layer, or other colored ink layers. Or, the decoration pattern  110  may be formed using other materials having light-shielding properties, such as a metal material. 
     The covering layer  120   a  includes a first portion  122  and a second portion  124 , and the second portion  124  covers a side surface  110   s  of the decoration pattern  110 . In other words, the covering layer  120   a  is a layered material that continuously extends from the second region  102   b  to the first region  102   a.  The first portion  122  covers the second region  102   b  of the substrate  102  and has a third thickness d 3 . The second portion  124  covers the decoration pattern  110  and has a second thickness d 2 . The second thickness d 2  is less than the third thickness d 3 . In other words, the first portion  122  that covers the second region  102   b  of the substrate  102  is thicker, and the second portion  124  that covers the decoration pattern  110  is thinner. In an exemplary embodiment, a total of the first thickness d 1  of the decoration pattern  110  and the second thickness d 2  of the first portion  122  is equal to the third thickness d 3  of the second portion  124 . Therefore, the covering layer  120   a  has a flattened surface. In other words, a protruding structure resulting from disposing the decoration pattern  110  on the substrate  102  is covered by the covering layer  120   a  after the covering layer  120   a  with the second thickness d 2  and the third thickness d 3  is fabricated, and therefore, the flattened surface is obtained. 
     For example, a material of the covering layer  120   a  is an insulating material, such as a thermosetting resin or a UV-curable resin. In an exemplary embodiment, preferably the covering layer  120   a  is formed using a high-transmittance material. In this embodiment, the covering layer  120   a  may be formed by a lamination process. Thus, the covering layer  120   a  has further thinner thickness when comparing to the thickness of the covering layer formed using another process such as a coating process. 
     The touch sensing element  130   a  is disposed on the covering layer  120   a.  The touch sensing element  130   a  includes a touch sensing electrode layer  132 . The touch sensing electrode layer  132  is disposed directly on the covering layer  120   a,  for example. Because the covering layer  120   a  facilitates the device having the flattened surface, when the touch sensing element  130   a  is directly formed on the covering layer  120   a,  problems, such as disconnection of wires, do not occur on the touch sensing electrode layer  132  easily, and therefore the fabrication yield rate is favorable. That is to say, the touch panel  100   a  of this embodiment has favorable fabrication yield rate and processability. Therefore, problems, such as defective fabrication of the touch sensing element  130   a  resulting from a height difference at boundaries of the decoration pattern  110 , do not easily occur. In addition, this disclosure is not intended to limit a sensing type of the touch sensing element  130   a  of the invention, which may be a mutual-capacitive touch sensing element or a self-capacitive touch sensing element. The touch sensing electrode layer  132  may be formed using a transparent conductive material; however, it should be noted that the invention is not limited thereto. In some other embodiments, the touch sensing electrode layer  132  may be formed using a metal grid or a touch electrode structure of other forms. 
     In addition, the touch panel  100   a  may be a component substrate of a display or a substrate independent of a display. For instance, the touch panel  100   a  may be a color filter substrate or an active device array substrate integrated with a touch function, or the touch panel  100   a  may be a cover lens integrated with a touch function that is disposed on an independent display panel; however, it should be noted that the invention is not limited thereto. 
       FIG. 2  is a cross-sectional view of a touch panel according to another embodiment of the invention. A touch panel  100   b  of  FIG. 2  is similar to the touch panel  100   a  of  FIG. 1 . Therefore, in the embodiment of  FIG. 2 , the same reference numerals are used to refer to identical components, and technical contents thereof can be found in the descriptions of the above embodiments. A difference therebetween is explained below. 
     With reference to  FIG. 2 , a touch sensing element  130   b  of the touch panel  100   b  is for example adhered onto the covering layer  120   a  via an adhesive layer  140 . That is, the adhesive layer  140  is adhered between the covering layer  120   a  and the touch sensing element  130   b.  More specifically, the touch sensing element  130   b  includes a touch sensing electrode layer  132  and a base  134 , wherein the base  134  is disposed between the adhesive layer  140  and the touch sensing electrode layer  132 . The base  134  includes a glass or a thin film substrate. In this embodiment, the base  134  is a thin film substrate, and a material thereof is polyethylene terephthalate (PET), for example. In other words, a method of fabricating the touch panel  100   b  includes: first, fabricating the touch sensing electrode layer  132  on the base  134  to form the touch sensing element  130   b;  and then adhering the touch sensing element  130   b  onto the covering layer  120   a  via the adhesive layer  140 . 
     In this embodiment, because the covering layer  120   a  facilitates the device to have the flattened surface, the thickness of the adhesive layer  140  coated on the covering layer  120   a  does not require to compensate the height difference and can be very thin. Therefore, the overall thickness of the touch panel  100   b  is not increased significantly by the adhesive layer  140 . Furthermore, if the decoration pattern  110  is a bright-colored decoration pattern (e.g. white), the decoration pattern  110  needs to be thicker to provide a sufficient optical density so as to shield the peripheral wirings. In such a case, the conventional technique requires use of a thicker adhesive layer to compensate the height difference between the decoration pattern  110  and the substrate  102 , so as to adhere the touch sensing element  130   b,  and the thickness thereof is 150 μm, for example. By contrast, the touch panel  100   b  of this embodiment is provided with the covering layer  120   a.  Thus, the thickness of the adhesive layer  140  can be reduced to about 50 μm, which helps to reduce the overall thickness of the touch panel  100   b.    
     Moreover, when the thin film substrate  134  of the touch sensing element  130   b  is adhered to the covering layer  120   a,  the adhering surfaces are flattened. Consequently, bubbles do not occur easily at the adhering interface, and the thin film substrate  134  does not bend for conforming to the height difference. Accordingly, the touch panel  100   b  is good in fabrication yield rate. 
       FIG. 3  is a cross-sectional view of a touch panel according to another embodiment of the invention. A touch panel  100   c  of  FIG. 3  is similar to the touch panel  100   a  of  FIG. 1 . Therefore, in the embodiment of  FIG. 3 , the same reference numerals are used to refer to identical components, and technical contents thereof can be found in the descriptions of the above embodiments. A difference therebetween is explained below. 
     With reference to  FIG. 3 , a substrate  102  of the touch panel  100   c  has a first region  102   a  and a second region  102   b.  The decoration pattern  110  is disposed on the first region  102   a  and has a fourth thickness d 4 . The decoration pattern  110  has a side surface  110   s,  for example. Descriptions regarding the material of the decoration pattern  110  can be found in the above embodiments and thus will not be repeated hereinafter. 
     The covering layer  120   b  covers the second region  102   b  of the substrate  102  and has a fifth thickness d 5 . The covering layer  120   b  covers the side surface  110   s  of the decoration pattern  110 , wherein the fifth thickness d 5  is not less than the fourth thickness d 4 . In this embodiment, the fifth thickness d 5  is approximately equal to the fourth thickness d 4 . Therefore, the covering layer  120   b  and the decoration pattern  110  have the same thickness, and top surfaces thereof are substantially flush with each other. In other words, the top surfaces of the covering layer  120   b  and the decoration pattern  110  together form a flattened surface. Regarding the material of the covering layer  120   b,  please refer to the descriptions of the covering layer  120   a  in the above embodiments, which will not be repeated hereinafter. 
     In this embodiment, the touch sensing element  130   a  is disposed on the covering layer  120   b  and the decoration pattern  110 . Because the covering layer  120   b  and the decoration pattern  110  form the flattened surface, problems, such as disconnection of wires or improper adhesion, do not easily occur during the fabrication of the touch sensing electrode layer  132  of the touch sensing element  130   a.  Thus, the touch panel  100   d  has a good fabrication yield rate. 
       FIG. 4  is a cross-sectional view of a touch panel according to another embodiment of the invention. A touch panel  100   d  of  FIG. 4  is similar to the touch panel  100   b  of  FIG. 2 . Therefore, in the embodiment of  FIG. 4 , the same reference numerals are used to refer to identical components, and technical contents thereof can be found in the descriptions of the above embodiments. A difference therebetween is explained below. 
     With reference to  FIG. 4 , the substrate  102  of the touch panel  100   d  includes a first region  102   a  and a second region  102   b.  The decoration pattern  110  is disposed on the first region  102   a  and has a fourth thickness d 4 . The decoration pattern  110  has a side surface  110   s,  for example. Descriptions regarding the material of the decoration pattern  110  can be found in the above embodiments and thus will not be repeated hereinafter. 
     In this embodiment, a covering layer  120   c  has a main body portion  126  and an extension portion  128 . The main body portion  126  covers the second region  102   b  of the substrate  102  and has a fifth thickness d 5 . The main body portion  126  extends from the second region  102   b  toward the first region  102   a,  such that the extension portion  128  covers the side surface  110   s  of the decoration pattern  110 , wherein the fifth thickness d 5  is not less than the fourth thickness d 4 . In this embodiment, the fifth thickness d 5  is slightly greater than the fourth thickness d 4 . Moreover, the extension portion  128  extends from the main body portion  126  toward the decoration pattern  110 , and a thickness thereof gradually decreases so that the extension portion  128  has a tapered edge. In other words, the extension portion  128  covers a partial region of the top surface of the decoration pattern  110 . 
     In this embodiment, the main body portion  126  has a flattened top surface while the extension portion  128  has the tapered edge with gradually decreasing thickness. Therefore, there is no obvious height difference between the main body portion  126  and the decoration pattern  110 . When the touch sensing element  130   b  is disposed on the covering layer  120   c  and the decoration pattern  110 , problems, such as disconnection of wires, do not easily occur during the fabrication of the touch sensing electrode layer  132  of the touch sensing element  130   a.  Thus, the touch panel  100   d  has good fabrication yield rate. 
     To conclude the above, in the invention, the covering layer is disposed to reduce the height difference between the decoration pattern and the substrate. Moreover, the covering layer has the flattened surface to facilitate fabrication of the touch sensing element and prevent the problem of disconnection of wires. In addition, when the touch sensing element is adhered to the covering layer by an adhering method, generation of bubbles is reduced. Accordingly, the fabrication yield rate of the touch panel is significantly improved.