Abstract:
The disclosure discloses a touch panel with parallel electrodes. The parallel electrodes mainly include a pair of parallel electrodes in x-axis and a pair of parallel electrodes in y-axis, further forming a ring structure by means of a series connection of eight corner resistances. The ring structure is the improvement of the electrode design, and is formed on the conductive layer of touch panel with a chain of series resistances. The voltage support of the conductive layer of the ring structure is provided by the corner electrodes on the conductive layer for touch detection.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 97150841 filed in Taiwan, R.O.C. on Dec. 26, 2008, the entire contents of which are hereby incorporated by reference. 
       BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The disclosure generally relates to a touch panel, more particularly, the disclosure relates to a touch panel with parallel electrodes. 
         [0004]    2. Description of the Related Art 
         [0005]    Nowadays, the most popular touch panels sold in the market are generally classifiable as resistive-type and capacitive-type touch panels. The resistive-type can also be classified into 4-wire resistive-type, 5-wire resistive-type, 6-wire resistive-type, 7-wire resistive-type and 9-wire resistive-type. The capacitive-type can be classified into surface capacitive touch screen (SCT) and projective capacitive touch screen (PCT) which also designated digital-touch technology. The resistive-type and the surface capacitive touch screen (SCT) are generally designated analog-touch technology. 
         [0006]    In recent years, the most popular analog-touch technology has generally used an input controlled by a 4-point voltage supply, as mentioned in U.S. Pat. No. 3,798,370A, U.S. Pat. No. 4,371746A, U.S. Pat. No. 4,661,655A, U.S. Pat. No. 4,731,508A, U.S. Pat. No. 4,797,514A, U.S. Pat. No. 4,822,957A, U.S. Pat. No. 4,933,660A, U.S. Pat. No. 5,804,773A, U.S. Pat. No. 5,815,141A, U.S. Pat. No. 6,396,484B1, U.S. Pat. No. 6,630,929B1, U.S. Pat. No. 7,148,881B2, U.S. Pat. No. 7,265,686B2, U.S. Pat. No. 7,307,626B2 etc. For touch detection, they usually control the input source by inputting the controlled voltage in four corners. 
         [0007]    For example, the operating principal of surface capacitive touch screen is as follows: A uniform electrical field is formed on the ITO layer. The capacitive charge effect results from the panel being touch by the fingers. The capacitance-coupled effect between the transparent electrodes and fingers causes current variation in the panel. Thus, the controlled devices can calculate the position of contact by means of measuring the current magnitude of four electrodes in four corners. 
         [0008]    Please refer to  FIG. 1 , which shows a schematic diagram of a five-wire touch panel  10  of the related art. By using the electrode wires, the voltage controlled unit (un-sketched) located outside the touch panel connects the four electrodes, A, B, C and D of conductive layer  11  to the electrode plates, PA, PB, PC and PD. Moreover, the PE is connected to the touch layer (un-sketched). The conductive layer enclosed by the chains of series resistances, CAR-YU, CAR-YD, CAR-XR and CAR-XL around conductive layer  11 , is the effective touch area. The four electrodes, A, B, C and D generate a uniformly distributed electrical field which is used for position detecting of resistive-type and the surface capacitive touch screens (SCT) by means of by the chains of series resistances, CAR-YU, CAR-YD, CAR-XR and CAR-XL around conductive layer  11 , and the voltage of voltage controlled unit. 
         [0009]    Please refer to  FIG. 2  and  FIG. 3 , which show the schematic diagrams of a controlled mode of detecting voltage in the y-axis, and detecting voltage in the y-axis, of the touch panel. Now refer to  FIG. 2 , which is a schematic diagram of a controlled mode of detecting a voltage in the y-axis of the touch panel. As the voltage controlled unit inputs voltages to the electrode plates (where PA=+5V, PB=0V, PC=0V and PD=+5V), an electrical field is generated within chains of series resistances, CAR-YU, CAR-YD, CAR-XR and CAR-XL around conductive layer  11 , as shown in  FIG. 2 , where the dash-line is the equipotential line and the solid-line indicates the direction of the current. The touched position in y-axis can be detected, as an object is contacting the touch panel. Now refer to  FIG. 3 , which is a schematic diagram of a controlled mode of detecting voltage in the x-axis of the touch panel. As the voltage controlled unit inputs voltages to the electrode plates (where PA=+5V, PB=+5V, PC=0V and PD=0V), an electrical field is generated within chains of series resistances, CAR-YU, CAR-YD, CAR-XR and CAR-XL around conductive layer  11  as shown in  FIG. 3 , where the dash-line is the equipotential line and the solid-line indicates the direction of the current. The touched position in x-axis can be detected, as an object is contacting the touch panel. 
         [0010]    However, touch panel technology has matured considerably over the last two or  10  three decades, with the increasing development of technology. Therefore, the latest trend in touch panel technology is economic, for example, the reduction of frame size, low power consumption or the request of uniformity of electrical field distribution in the frame, especially in the corners. Consequently, every touch panel factory and store of continues to develop their technology further, as a result of competition. 
       SUMMARY 
       [0011]    It is an objective of the disclosure to provide a touch panel with parallel electrodes that possesses the advantage of low power consumption, and the improvement of electrical field uniformity near the edges. 
         [0012]    To achieve the above objectives, the disclosure provides a touch panel with  20  parallel electrodes, includes a substrate, a conductive layer formed on the substrate (the conductive layer including an internal contact area and an edge resistance around the internal contact area), a plurality of corner electrodes, connected to the corner of the edge resistance, a pair of parallel electrodes in x-axis, connected to a voltage controlled unit and isolated from the edge resistance, formed out of both sides in x-axis direction of the edge resistance of the conductive layer, a pair of parallel electrodes in y-axis, connected to the voltage controlled unit and isolated from the edge resistance, formed out of both sides in y-axis direction of the edge resistance of the conductive layer, and a plurality of corner resistances, each of the plurality of corner resistances including two terminals, one terminal connected either to parallel electrode in x-axis or the parallel electrode in y-axis, and the other connected to one terminal of the plurality of corner electrodes. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    All the objects, advantages, and novel features of the disclosure will become more apparent from the following detailed descriptions when taken in conjunction with the accompanying drawings: 
           [0014]      FIG. 1  is a schematic diagram of a five-wire touch panel  10  of the related art; 
           [0015]      FIG. 2  is a schematic diagram of a controlled mode of detecting voltage in the y-axis of the touch panel of prior art; 
           [0016]      FIG. 3  is a schematic diagram of a controlled mode of detecting voltage in the x-axis of the touch panel of prior art; 
           [0017]      FIG. 4  is a schematic diagram of a touch panel with parallel electrodes  100  of the disclosure; 
           [0018]      FIG. 5  is a schematic diagram of a controlled mode of detecting voltage in the y-axis of the touch panel of the disclosure; 
           [0019]      FIG. 6  is a schematic diagram of a controlled mode of detecting voltage in the x-axis of the touch panel of the disclosure; and 
           [0020]      FIG. 7  is a specific embodiment of fabrication of resistance, R 1 , in the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Although the disclosure has been explained in relation to several preferred embodiments, the accompanying drawings and the following detailed descriptions are the preferred embodiment of the disclosure. It is to be understood that the following disclosed descriptions will be examples of the disclosure, and will not limit the disclosure to the drawings and the special embodiment. 
         [0022]    To understand the spirit of the disclosure, please refer to  FIG. 4 , which shows a schematic diagram of a touch panel with parallel electrodes  100 . Compared to the conventional four-corner electrodes, the touch panel with two pairs of parallel electrodes is designed as a touch panel with two pairs of parallel electrodes. The two pairs of parallel electrodes formed on the conductive layer  110  are YU-0 and YD-0 in y-axis and XR-0 and XL-0 in x-axis, respectively. The parallel electrodes in the disclosure can be applied to resistive-type touch panels, or satisfy the requirement of equal potential in capacitive-type touch panels. 
         [0023]    Moreover, each parallel electrode in y-axis and in x-axis possesses two terminals, and all terminals of the parallel electrodes in y-axis, YU-0 and YD-0, are connected in series to the resistances, R 1 . Similarly, all of terminals of the parallel electrodes in x-axis, XR-0 and XL-0, are also connected in series to the resistances, R 1 . Therefore, the others terminals of resistances R 1 , connected in series to YU-0, YD-0, XR-0 and XL-0 are connected to each other and form four nodes, N 1 , N 2 , N 3  and N 4 , respectively. These four nodes are constructed of the four electrodes of the conductive layer  110 , namely the voltage inputs of four chains of series resistances, CAR-YU, CARYD, CAR-XR, and CAR-XL. 
         [0024]    The parallel electrodes in y-axis, YU-0 and YD-0, and the parallel electrodes in x-axis, XR-0 and XL-0, are connected respectively to four electrode plates, YU-1, YD-1, XR-1 and XL-1, by using the conductive wires, where the parallel electrodes and the conductive wires can be chosen from silver conductive wires or other metals such as molybdenum/aluminum/molybdenum metal layers, chromium conductive wires or other metals with better electric conductivity. Silver conductive wires which are fabricated by silver paste above 500° are preferred for the reasons of frame-width reduction by narrowing the wires effectively, low resistivity (low power consumption), and better linear support of the touched are an edge. 
         [0025]    Since the resistance of each of the four conductive wires is identical and close to zero, the voltage drops between the four electrode plates (YU-1, YD-1, XR-1 and XL-1), and the parallel electrodes YU-0, YD-0, XR-0 and XL-0 (which are connected by using four silver conductive wires), are nearly zero. Furthermore, the voltage drops of two terminals of the parallel electrodes, i.e. the parts connected to resistances, R 1 , are equivalent to the voltage provided by four electrode plates, YU-1, YD-1, XR-1 and XL-1. This is because the parallel electrodes are fabricated from silver conductive wires. The voltage drops of four nodes, N 1 , N 2 , N 3  and N 4 , are not ignored because of the resistances, R 1 . The range of the voltage drops depends on the total resistance value (effective resistance value), of resistance R 1 , and the chain of series resistances CAR-YU, CAR-YD, CAR-XR, CAR-XL. That is, the value of resistance R 1 , can be determined firstly and designed for according to the practical demands of power consumption. For example, the resistance values of chain of series resistances CAR-YU, CAR-YD, CAR-XR and CAR-XL, are 2 k˜5 kΩ, and the resistances R 1  are designed to be 2 k˜5 kΩ. This means that the resistance values of R 1  can be designed according to the resistance values of a chain of series resistances and the practical demands of power consumption. 
         [0026]    The controlled method of the parallel electrodes according to the disclosure is interpreted in the following manner. Please refer to  FIG. 5  and  FIG. 6 , which show the controlled mode of detecting voltage in y-axis and in x-axis, respectively. In particular,  FIG. 5  shows the controlled mode of detecting voltage in y-axis. Moreover, the electrical field distribution of the chain of series resistances CAR-YU, CAR-YD, CAR-XR and CAR-X, in the conductive layer  110  is displayed as the voltage controlled unit input voltages to the electrode plates with YU-1=+5V, YD-1=0V, XR-1 and XL-1 both connected in a floating manner. Moreover, the voltage-equipotential line of the chain of series resistances CAR-YU is 4.25V and the voltage-equipotential line of the chain of series resistances CAR-YD is 0.75V in the example shown in  FIG. 5 , where the voltage of 0.75V results from resistance R 1 . The dash-line is the equipotential line and the solid-line indicates the current direction. The touched position in y-axis can be detected as an object is contacting the touch panel. 
         [0027]    The operating voltage can be set from 1.5V to 15V. 
         [0028]    Please refer to  FIG. 6 , which shows the controlled mode of detecting voltage in y-axis, moreover the electrical field distribution of the chain of series resistances CAR-YU, CAR-YD, CAR-XR and CAR-X in the conductive layer  110  is displayed as the voltage controlled unit input voltages to the electrode plates with YU-1=+5V, YD-1=0V, XR-1 and XL-1 are both connected in a floating manner. Moreover, the voltage-equipotential line of the chain of series resistances, CAR-YU, is 4.25V and the voltage-equipotential line of the chain of series resistances, CAR-YD, is 0.75V in the example shown in  FIG. 5 , wherein, the voltage of 0.75V is resulted from resistance, R 1 . The dash-line is the equipotential line and the solid-line indicates the current direction. The touched position in y-axis can be detected as an object is contacting the touch panel. 
         [0029]    Using the descriptions mentioned above, the input methods of electrodes in four corners in the disclosure can be varied by using the parallel electrodes. Furthermore, the control methods of the voltage controlled unit can be tuned with the input, at the same time. This type of structure also improves the non-uniformity of the electrical field in the corner. In addition, it decreases the operating power consumption because of the reduction of the voltage distributed in the conductive layer (touch area). 
         [0030]    Please refer to  FIG. 6 , which shows the specific embodiment of fabrication of resistance R 1 , in the disclosure. The resistance R 1  can be fabricated by means of a L-shaped electrode and formed by the gaps between L-shaped electrode and parallel electrodes YU-0, YD-0, XR-0 and XL-0. That is, the gaps between L-shaped electrode and parallel electrodes constitute the conductive layer, which can be resistance R 1 . The resistance value can be calculated by the width, length and electric conductivity of the conductive layer. The fundamental formula is R=ρL/A, where R is the resistance value, ρ is the electric conductivity, A is the cross section area, and L is the length. 
         [0031]    Furthermore, the L-shaped electrode also can be fabricated in the same manner with parallel electrodes, that is, using the same material and process. For example, it may be formed on the conductive layer by means of screen printing, using unleaded silver paste at a high temperature. The L-shaped electrode welded on the transparent conductive layer with silver paste at a temperature above 500° results in an extremely small resistance value between the conductor interfaces (near to zero). Aside from the benefits of high temperature tolerance and environmental resistance, the crystallization of silver conductive wires and conductive layer at a high temperature can also enhance product chemical resistance, reliability, and lifetime. The material for the L-shaped electrode can also be chosen among from molybdenum/aluminum/molybdenum metal layers, chromium or other metals with better electric conductivity. 
         [0032]    Although the embodiment has been explained in relation to its preferred embodiment, this explanation is not used to limit the embodiment. It is to be understood that many other possible modifications and variations can be made by those skilled in the art, without departing from the spirit and scope of the embodiment as claimed hereafter.