Patent Publication Number: US-2012032904-A1

Title: Touch panel

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Korean Patent Application No. 10-2010-0076568, filed on Aug. 9, 2010, entitled “Touch Panel,” which is hereby incorporated by reference in its entirety into this application. 
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates generally to touch panels. 
     2. Description of the Related Art 
     In general, touch panels are attached to the surfaces of display devices, such as Liquid Crystal Displays (LCDs), Plasma Display Panels (PDPs), Organic Light Emitting Diodes (OLEDs), and Active Matrix Organic Light Emitting Diodes (AMOLEDs). Touch panels are input devices, and generate signals corresponding to contact locations when an object, such as a finger or a pen, comes into contact with them. 
     Such touch panels are utilized in a variety of fields, including the fields of small-sized portable terminals, industrial terminals, and Digital Information Devices (DIDs), and are classified into the following types: resistive-type touch panels, capacitive-type touch panels, electromagnetic-type touch panels, Surface Acoustic Wave (SAW)-type touch panels, and infrared-type touch panels. 
     Meanwhile, various types of touch panels are employed in electronic products depending on the signal amplification, the differences in resolution, the difficulties of design and manufacturing technology, optical characteristics, electrical characteristics, mechanical characteristics, anti-environmental characteristics, input characteristic, durability and economic efficiency. Recently, resistive-type touch panels and capacitive-type touch panels have been the ones most widely used. 
     Resistive-type touch panels are configured such that a transparent conductive film is formed over an entire surface of a substrate and electrode terminals are disposed on the four corners of the transparent conductive film, and, when an alternating current (AC) signal is applied to a coordinate detection transparent conductive film, they detect currents flowing across current detection resistors disposed at the four corners and then detect touch coordinates using resistance ratios between a touch point and electrode terminals. 
     In contrast, the capacitive-type touch panels are configured such that X-direction detection cells and Y-direction detection cells are arranged on a transparent substrate, and they detect touch coordinates by detecting a capacitance value using a current value which is detected between an X-direction detection cell and a Y-direction detection cell when contact is made. 
     Conventional touch panels are generally configured such that the area ratio between electrodes varies for each touch section, as was shown in Korean Unexamined Patent Publication No. 2009-11244 and Korean Unexamined Patent Publication No. 2009-50988. 
     That is, since conventional touch panels are configured such that electrodes are formed to have different sizes for respective sections, they are problematic in that large vacant spaces are formed between the electrodes, thereby increasing the overall sizes of the touch panels. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and the present invention is intended to provide a touch panel which has a small size. 
     According to the present invention, there is provided a touch panel, including a transparent substrate; and a plurality of transparent electrodes formed on one surface of the transparent substrate, each of the transparent electrodes including a touch part formed to have an identical width; and a connection part configured in a stepped form along with the touch part, and configured to connect the touch part with the transparent substrate. 
     The transparent electrodes may be formed to have different capacitance values. 
     The touch parts may be formed to have an identical thickness. 
     The touch parts may be formed to have different thicknesses. 
     The connection parts may be formed to have different widths. 
     The connection parts may be formed to have an identical thickness. 
     The connection parts may be formed to have different thicknesses. 
     The touch part and the connection part may be configured to have a T-shaped section. 
     The touch panel may further include a first wiring configured to connect ones of the transparent electrodes, arranged in each odd column or row, to each other; and a second wiring configured to connect ones of the transparent electrodes, arranged in each even column or row, to each other. 
     The first wiring and the second wiring may be disposed across spaces formed by the stepped form in which the touch part and the connection part are configured. 
     The first wiring and the second wiring may be disposed between the transparent electrodes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a sectional view of a touch panel according to a preferred embodiment of the present invention; 
         FIGS. 2 and 3  are plan views showing the wiring of the touch panel of  FIG. 1 ; 
         FIGS. 4 and 5  are sectional views showing the locations of the wirings of the touch panel of  FIG. 1 ; 
         FIGS. 6 and 7  are sectional views showing application embodiments of the touch panel of  FIG. 1 ; and 
         FIG. 8  is a sectional view of a touch panel according to another preferred embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     If in the specification, detailed descriptions of well-known functions or configurations may unnecessarily make the gist of the present invention obscure, the detailed descriptions will be omitted. 
     The terms and words used in the present specification and the accompanying claims should not be limitedly interpreted as having their common meanings or those found in dictionaries, but should be interpreted as having meanings adapted to the technical spirit of the present invention on the basis of the principle that an inventor can appropriately define the concepts of terms in order to best describe his or her invention. 
     It should be noted that the same reference numerals are used as much as possible throughout the different drawings to designate the same or similar components. 
     Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. 
       FIG. 1  is a sectional view of a touch panel  100  according to a preferred embodiment of the present invention. 
     As shown in  FIG. 1 , the touch panel  100  according to the preferred embodiment of the present invention is configured such that N transparent electrodes  104  are formed on one surface of a transparent substrate  102  and each of the transparent electrodes  104  includes a touch part  104   a  and a connection part  104   b  which are configured in a stepped form. 
     The transparent substrate  102  functions to support the transparent electrodes  104 , and may be made of, but not limited to, polyethylene terephthalate (PET), polycarbonate (PC), polymethylmethacrylate (PMMA), polyethylenenaphthalate (PEN), Polyethersulfone (PES), cyclic olefin copolymer (COC), triacetylcellulose (TAC) films, polyvinyl alcohol (PVA) films, polyimide (PI) films, polystyrene (PS), biaxial oriented polystyrene (BOPS) containing K resin, glass, or tempered glass. 
     The transparent electrodes  104  generate signals when a user makes contact so that a controller (not shown) can recognize touch coordinates. 
     The transparent electrodes  104  are made of a conductive polymer which has excellent flexibility and is applied using a simple coating process. 
     In this case, the conductive polymer may include poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS), Polyacetylene or polyphenylenevinylene. 
     Meanwhile, it is preferable to perform high-frequency processing or primer processing on one surface of the transparent substrate  102  so as to increase the activity of the surface (so as to improve adhesive power) before forming the transparent electrodes  104  on the surface of the transparent substrate  102 . 
     Each of the transparent electrodes  104  is configured to include a connection part  104   b  attached to the transparent substrate  102  and a touch part  104  formed on the connection part  104   b  to be integrated with the connection part  104   b , as shown in  FIG. 2 . 
     Here, the touch part  104   a  and the connection part  104   b  are formed to have a T-shaped section in a stepped form. 
     Furthermore, the transparent electrodes  104  each including a touch part  104   a  and a connection part  104   b  are formed to have different capacitance values (or different resistance values). 
     For this purpose, the touch parts  104   a  are formed to have the same width (that is, the same longitudinal length and vertical length), and the connection parts  104   b  integrated with the touch parts  104   a  and electrically connecting the touch parts  104   a  with the transparent substrate  102  are formed to have different widths (for example, L 1 &gt;L 2 &gt;L 3 &gt;L 4 ). 
     Furthermore, the touch parts  104   a  may be formed to have the same thickness (or the same height; t) or different thicknesses (or heights), and the connection parts  104   b  are also formed to have the same thickness (or the same height; p) or different thicknesses (or heights). 
     When the touch parts  104   a  and the connection parts  104   b  are formed to have different thicknesses, the thicknesses of the touch parts  104   a  and the connection parts  104   b  are determined such that the transparent electrodes  104  have different capacitance values (or different resistance values). 
     Meanwhile, even when the transparent electrodes  104  each including a touch part  104   a  and a connection part  104   b  are configured such that the touch parts  104   a  and the connection parts  104   b  are formed to have the same thickness, the connection parts  104   b  are formed to have different widths, so that the transparent electrodes  104  have different capacitance values (or different resistance values). 
     The transparent electrodes  104  are arranged on one surface of the transparent substrate  102  in matrix form, as shown in  FIGS. 2 and 3 . 
     Here, the transparent electrodes  104  are connected by a wiring  106   a  or  106   b  for each column or row. As shown in  FIG. 2 , transparent electrodes  104  arranged in each odd column are connected to each other by the first wiring  106   a , and transparent electrodes  104  arranged in each even column are connected to each other by the second wiring  106   b.    
     Furthermore, as shown in  FIG. 3 , transparent electrodes  104  arranged in each odd row are connected to each other by the first wiring  106   a , and transparent electrodes  104  arranged in each even row are connected to each other by the second wiring  106   b.    
     Here, the first wiring  106   a  and the second wiring  106   b  are formed to be connected to the connection parts  104   b . The first wiring  106   a  connects transparent electrodes  104 , arranged in each odd row or column, to each other, and the second wiring  106   b  connects transparent electrodes  104 , arranged in each even row or column, to each other. 
     Furthermore, the first wiring  106   a  and the second wiring  106   b  are configured not to overlap each other on the transparent substrate  102 . As shown in  FIGS. 2 and 3 , it is preferred that the branches of the first wiring  106   a  and the branches of the second wiring  106   b  be merged on opposite sides. 
     That is, if the branches of the first wiring  106   a  each of which connects transparent electrodes  104  arranged in each odd column are configured to be merged on the upper side of the transparent substrate  102 , the branches of the second wiring  106   b  each of which connects transparent electrodes  104  arranged in each even column are configured to be merged on the lower side of the transparent substrate  102 . If the branches of the first wiring  106   a  are configured to be merged on the lower side of the transparent substrate  102 , the branches of the second wiring  106   b  are configured to be merged on the upper side of the transparent substrate  102 . 
     Furthermore, if the branches of the first wiring  106   a  each of which connects transparent electrodes  104  arranged in each odd row are configured to be merged on the left side of the transparent substrate  102 , the branches of the second wiring  106   b  each of which connects transparent electrodes  104  arranged in each even row are configured to be merged on the right side of the transparent substrate  102 . If the branches of the first wiring  106   a  are configured to be merged on the right side of the transparent substrate  102 , the branches of the second wiring  106   b  are configured to be merged on the left side of the transparent substrate  102 . 
     Although it is preferred that the first wiring  106   a  and the second wiring  106   b  be formed across spaces formed by the stepped form in which the touch parts  104   a  and the connection parts  104   b  are configured, as shown in  FIG. 4 , the first wiring  106   a  and the second wiring  106   b  may be formed between the transparent electrodes  104 , as shown in  FIG. 5 . 
     Here, in order to form the first wiring  106   a  and the second wiring  106   b  across spaces A formed by the stepped form in which the touch parts  104   a  and the connection parts  104   b  are configured, the connection parts  104   b  should be formed to have the height, that is, the thickness, greater than the heights of the first wiring  106   a  and the second wiring  106   b . It is preferred that the height of the connection parts  104   b  be determined to prevent signal interference between the transparent electrodes  104  including the touch parts  104   a  and the connection parts  104   b  and the wirings  106   a  and  106   b.    
     Meanwhile, the touch panel  100  according to the embodiment of the present invention, shown in  FIG. 1 , may be used to manufacture a mutual capacitance-type touch panel  200  in which two transparent substrates  102  on one surface of each of which transparent electrodes  104  are formed are provided and the two transparent substrates  102  are combined using a bonding layer  110  so that the transparent electrodes  104  face each other, as shown in  FIG. 6 , and may be used to manufacture a resistive-type touch panel  300 , as shown in  FIG. 7 . 
     Here, the mutual capacitance-type touch panel  200  is configured such that the bonding layer  110  is applied to the entirety of the transparent electrodes  104  so that the opposite transparent electrodes  104  are insulated from each other. The resistive-type touch panel  300  is configured such that a bonding layer  110  is applied only to the edges of the transparent substrate  102  so that opposite transparent electrodes  104  come into contact with each other when a user applies pressure thereto and such that dot spacers  112  providing repulsive force are formed on transparent electrodes  104  formed on any one of the opposite transparent substrates  102  so that the transparent electrodes  104  can return to their original positions when the pressure applied by the user is removed. 
       FIG. 8  is a sectional view of a touch panel  400  according to another preferred embodiment of the present invention. 
     As shown in  FIG. 8 , the touch panel  400  according to another preferred embodiment of the present invention is configured such that transparent electrodes  104  are formed on two opposite surfaces of a transparent substrate  102  and each of the transparent electrodes  104  includes a touch part  104   a  and a connection part  104   b  which are configured in a stepped form. 
     Since the structure and characteristics of the touch panel  400  according to the preferred embodiment of the present invention are the same as those of the touch panel  100  according to the embodiment of the present invention, shown in  FIGS. 1 to 5 , except for the structure in which the transparent electrodes  104  are formed on the two surfaces of the transparent substrate  102 , a detailed description thereof is omitted here. 
     Since as described above, the touch panel according to the embodiment of the present invention is configured such that portions to be touched, that is, the touch parts  104   a , are all formed to have the same size, the touch parts  104   a  and the connection parts  104   b  are configured in a stepped form, and the wirings connecting the transparent electrode  104  are disposed across spaces formed by the stepped form, the gaps between the transparent electrodes  104  can be reduced, thereby reducing the size of the touch panels. 
     According to the present invention, since the touch portions of the transparent electrodes are all formed to have the same width but to have different capacitance values and the wirings connecting the transparent electrodes are disposed across spaces formed by the stepped form in which the touch parts and the connection parts are configured, the gaps between the transparent electrodes can be reduced, thereby reducing the size of the touch panel. 
     Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.