Patent Publication Number: US-2009225051-A1

Title: Touch panel

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of P.R.C. patent application serial no. 200810083181.3, filed on Mar. 4, 2008. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of specification. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to a touch panel, in particular, to a touch panel capable of being operated in multiple touch sensing modes. 
     2. Description of Related Art 
     Generally, touch panels can be categorized into resistive touch panels and capacitive touch panels according to the structures and driving methods thereof. Regarding a resistive touch panel, a user has to directly press the resistive touch panel so that a part of an upper conductive layer inside the resistive touch panel can be bent and electrically connected with a lower conductive layer to generate a corresponding signal. Thus, the user may operate a touch panel with various media, such as a fingertip or a plastic pen etc. However, the upper conductive layer is always being pressed and bent so that it is easily cracked and may result in touch sensing failure. 
     Regarding a capacitive touch panel, a capacitance change is generated when a user touches the capacitive touch panel, and the capacitive touch panel implements the touch sensing through the capacitance change. Thus, the capacitive touch panel can sense a user&#39;s touch without actually pressing the capacitive touch panel, so that the damages of the capacitive touch panel due to being pressed over and over would be restrained. However, a capacitive touch panel cannot be operated with a gloved finger or an insulative medium. Besides, the capacitive touch panel may sense incorrectly if a water drop or a conductive particle falls on the capacitive touch panel. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to a touch panel, wherein the touch panel integrates both of a resistive touch sensing design and a capacitive touch sensing design such that the aforementioned disadvantages can be overcome. 
     One embodiment of present invention provides a touch panel having a first substrate, a second substrate opposite to the first substrate, a first conductive layer, a second conductive layer, first electrode patterns, second electrode patterns, spacers, first conductive wires and second conductive wires. The first electrode patterns are formed on the first conductive layer and arranged near the periphery of the first conductive layer. The first electrode patterns are electrically connected to the first conductive layer. The second electrode patterns are formed on the second conductive layer and arranged near the periphery of the second conductive layer. The second electrode patterns are electrically connected to the second conductive layer. The touch panel further includes a plurality of first conductive wires and a plurality of second conductive wires. The first conductive wires electrically connect to the first electrode patterns and the second conductive wires electrically connect to the second electrode patterns. The first conductive wires may be located at the corners or the sides of the first conductive layer when the first conductive layer is in a rectangular shape. The second conductive wires may be located at the corners of the second conductive layer when the second conductive layer is in a rectangular shape. The touch panel can be selectively operated in a surface capacitive touch sensing mode or in a 5-wire resistive touch sensing mode by a driving circuit (not shown). 
     According to an embodiment of the present invention, the first electrode patterns are independent to each other and arranged near the periphery of the first conductive layer all together. Substantially, the first electrode patterns include at least a straight line segment and at least a crooked line segment. 
     According to an embodiment of the present invention, the second electrode patterns are independent to each other and arranged near the periphery of the second conductive layer all together. Substantially, the second electrode patterns include at least a straight line segment and at least a crooked line segment. 
     According to an embodiment of the present invention, a material of the first conductive layer and the second conductive layer comprises a transparent conductive material, for example, indium tin oxide (ITO) or indium zinc oxide (IZO). 
     In a touch panel provided by the embodiments of the present invention, a plurality of electrode patterns is respectively disposed at the edges of a first conductive layer and a second conductive layer, and these electrode patterns are independent to each other. Specific electric fields can be formed in the first conductive layer and the second conductive layer respectively through these electrode patterns. Thus, the touch panel in the present invention can be operated in at least a surface capacitive touch sensing mode and a 5-wire resistive touch sensing mode. Foregoing two touch sensing modes can be switched and accordingly the disadvantages thereof can be compensated for. Thereby, a touch panel in the present invention will not mis-sense a conductive particle dropped thereon or be damaged in the conductive layer by a frequently bent. 
    
    
     
       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 embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
         FIG. 1A  and  FIG. 1B  are respectively an explosion diagram and a cross-sectional view of a touch panel according to an embodiment of the present invention. 
         FIG. 2A  and  FIG. 2B  are diagrams respectively illustrating an equivalent circuit diagram of the touch panel being operated in a surface capacitive touch sensing mode according to an embodiment of the present invention. 
         FIG. 3A  and  FIG. 3B  are diagrams illustrating a touch panel being operated in a resistive touch sensing mode according to an embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
     The characteristics and functions of a touch panel provided by the present invention will be described below with reference to embodiments of the present invention and accompanying drawings. 
       FIG. 1A  and  FIG. 1B  are respectively an explosion diagram and a cross-sectional view of a touch panel according to an embodiment of the present invention. Referring to  FIG. 1A  and  FIG. 1B , the touch panel  100  has a first substrate  10 , a second substrate  20 , a first conductive layer  110  formed on the first substrate  10 , a second conductive layer  120  formed on the second substrate  20 , a plurality of first electrode patterns  112 , and a plurality of second electrode patterns  122 . In the present embodiment, the first conductive layer  110  and the second conductive layer  120  may respectively be in a rectangular shape. The first electrode patterns  112  are formed on the first conductive layer  110  and approximately arranged near the periphery of the first conductive layer  110 . The second electrode patterns  122  are formed on the second conductive layer  110  and approximately arranged near the periphery of the second conductive layer  120 . Namely, the first electrode patterns  112  and the second electrode patterns  122  respectively form a rectangular frame approximately. It should be mentioned that in the present embodiment, each of the first electrode patterns  112  and each of the second electrode patterns  122  are independent to each other. 
     The first conductive layer  110 , the second conductive layer  120 , the first electrode patterns  112 , and the second electrode patterns  122  are fabricated through related semiconductor processes such as thin film deposition. The touch panel  100  is usually attached to a display panel so as to provide a convenient operation thereof. To further improve the optical characteristics of the touch panel  100 , the first conductive layer  110  and the second conductive layer  120  may be fabricated with a transparent conductive material, such as indium tin oxide (ITO), indium zinc oxide (IZO), or other suitable materials. While fabricating the first conductive layer  110  and the second conductive layer  120 , the process conditions can be adjusted appropriately to allow the first conductive layer  110  and the second conductive layer  120  to have certain resistances so that the touch panel  100  can work properly. In short, the first conductive layer  110  and the second conductive layer  120  are electrically conductive, but the conductivity of the first conductive layer  110  and the second conductive layer  120  is worse than that of the first electrode patterns  112  and the second electrode patterns  122 . In addition, a plurality of spacers  30  is disposed between the first substrate  10  and the second substrate  20  so as to separate the first conductive layer  110  from the second conductive layer  120 . 
     In the present embodiment, the first electrode patterns  112  are independent to each other, and each of the first electrode patterns  112  may be a straight line segment or a crooked line segment. The dash line segments shown in  FIG. 1A  are only illustrated schematically. Actually, the first electrode patterns  112  may be in many different shapes, such as Z shape, I shape, L shape, and staircase shape etc. Besides, the first electrode patterns  112  may be arranged in multiple rows and the first electrode patterns  112  in the rows may be staggered arranged. In other words, the first electrode patterns  112  which surround the first conductive layer  110  may completely enclose a part of the first conductive layer  110 . In addition, the second electrode patterns  122  may also be straight line segments or crooked line segments which are independent to each other. In the present embodiment, the first electrode patterns  112  and the second electrode patterns  122  may be disposed in the same way but may have the same or different shapes. As well, the second electrode patterns  122  which surround the second conductive layer  120  may also be arranged into multiple rows and the second electrode patterns  122  in each row may also be arranged in a staggered way so as to completely enclose a part of the second conductive layer  120 . The present invention is not restricted to the abovementioned, and the electrode patterns ( 112  and  122 ) can be disposed in any way such that an even electric field can be generated in the first conductive layer  110  and the second conductive layer  120  respectively. 
     Under the condition that the first electrode patterns  112  and the second electrode patterns  122  are all independent to each other and respectively located near the periphery of the first conductive layers  110  and the second conductive layer  120 , the touch panel  100  can be operated in at least two touch sensing modes. These two touch sensing modes may include a surface capacitive touch sensing mode and a 5-wire resistive touch sensing mode, and which will be described below with examples. However, the present invention is not limited to foregoing two modes, and any other touch sensing mode which can be applied to foregoing design of electrode patterns can be applied to the touch panel  100 . 
       FIG. 2A  and  FIG. 2B  are diagrams respectively illustrating an equivalent circuit diagram of the touch panel being operated in the surface capacitive touch sensing mode according to an embodiment of the present invention, wherein only some elements, such as the first conductive layer, are illustrated. Referring to both  FIG. 1A  and  FIG. 2A , the touch panel  100  further includes a plurality of first conductive wires  112 A˜ 112 D. The first conductive wires  112 A˜ 112 D are disposed at the sides of the first conductive layer  110  and are electrically connected to the first electrode patterns  112 . In the present embodiment, when the touch panel  100  is operated in the surface capacitive touch sensing mode, a voltage, such as alternating current voltage, is supplied from the first conductive wires  112 A˜ 112 D to the first electrode patterns  112  by using a controller chip (not shown) of the touch panel  100 . The wiring layout between the first electrode patterns  112  helps to form a uniform electric field in the first conductive layer  110 . When a user touches the position A with a finger or other conductive object, the uniform electric field is disturbed and accordingly a specific current is generated. Herein, a specific relationship between the distance between the position A and the first conductive wires  112 A˜ 112 D and the specific current is presented. Accordingly, the controller chip can calculate the position touched by the user according to the current received by the first conductive wires  112 A˜ 112 D. 
     In addition, the first conductive wires  112 A˜ 112 D may also be located elsewhere than at the sides of the first conductive layer  110 . Referring to  FIG. 1A  and  FIG. 2B , the first conductive wires  112 A˜ 112 D may be located at the corners of the first conductive layer  110  and electrically connected to the first electrode patterns  112 . Similarly, when a voltage is supplied to the first conductive wires  112 A˜ 112 D, a uniform electric field is produced by the first electrode patterns  112  in the first conductive layer  110 . When the user touches the position A with a conductive object, a specific relationship is presented between the current received by the first conductive wires  112 A˜ 112 D and the distance between the position A and the first conductive wires  112 A˜ 112 D. Thereby, the touch panel can be operated in the surface capacitive touch sensing mode even when the first conductive wires  112 A˜ 112 D are disposed at the corners of the first conductive layer  110 . 
     Actually, a convenient operation interface can be provided by integrating the touch panel  100  with a display panel (not shown). If the first conductive layer  110  is closer to the user after the display panel is attached to the touch panel  100 , the first conductive layer  110  can be used for performing surface capacitive touch sensing. Here the second electrode patterns  122  may be connected to a ground voltage in order to prevent the signals of the touch panel  100  and the display panel from disturbing each other, namely, the second conductive layer  120  is used as a shield conductive layer when the touch panel is selectively operated in a surface capacitive touch sensing mode. Specifically, which conductive layer (the conductive layer  110  or the conductive layer  120 ) is used for performing surface capacitive touch sensing is not limited in the present invention. 
     However, just like the conventional capacitive touch panel, the touch panel  100  may sense an incorrect signal when water or a conductive particle drops on the touch panel  100  when it is operated in the surface capacitive touch sensing mode. To avoid such incorrect sensing, the touch panel  100  in the present invention can also work in another touch sensing mode, namely, the 5-wire resistive touch sensing mode. 
       FIG. 3A  and  FIG. 3B  are diagrams illustrating a touch panel being operated in a 5-wire resistive touch sensing mode according to an embodiment of the present invention. Referring to  FIG. 3A , the touch panel  100  further includes a plurality of first conductive wires  112 A˜ 112 D and a plurality of second conductive wires  122 A˜ 122 D. The first conductive wires  112 A˜ 112 D may be located at the corners or the sides of the first conductive layer  110 . Herein the first conductive wires  112 A˜ 112 D being located at the corners of the first conductive layer  110  will be taken as an example. The second conductive wires  122 A˜ 122 D are, for example, located at the corners of the second conductive layer  120 . Besides, the first conductive wires  112 A˜ 112 D are electrically connected to the first electrode patterns  112 , and the second conductive wires  122 A˜ 122 D are electrically connected to the second electrode patterns  122 . The 5-wire resistive touch sensing performed by the touch panel  100  when a user touches the touch panel  100  can be divided into two phases approximately. During the first phase, a voltage V 1  is supplied to the second conductive wires  122 A and  122 B, and another voltage V 2  is supplied to the second conductive wires  122 C and  122 D, wherein the voltage V 1  is different from the voltage V 2 , and under the voltages V 1  and V 2 , an electric field in the second conductive layer  120  is produced along the direction of the arrow  200  by the disposition of the second electrode patterns  122 . Under the affection of this electric field, different voltages are presented at different positions in the second conductive layer  120  along the direction of the arrow  200 . 
     For example, if the voltage V 1  is different from the voltage V 2 , the second electrode patterns  122  produce a uniform electric field in the second conductive layer  120 , and the voltage V A  at the position A is related to the distances d 1  and d 2 . Thus, if the first conductive layer  110  and the second conductive layer  120  are connected at the position A because of the pressing of a user, one of the first conductive wires  112 A˜ 112 D of the touch panel  100  detects the voltage value V A  and accordingly the coordinates of the positions A touched by the user along the direction of the arrow  200  can be calculated in a driving chip (not shown). 
     Referring to  FIG. 3B , during the second phase, a voltage V 3  is supplied to the second conductive wires  122 A and  122 D, and a voltage V 4  is supplied to the second conductive wires  122 B and  122 C, wherein the voltage V 3  is different from the voltage V 4 . Substantially, the voltage V 3  may be equal to the voltage V 1 , and the voltage V 4  may be equal to the voltage V 2 , or the voltage V 3  may be equal to the voltage V 2 , and the voltage V 4  may be equal to the voltage V 1 . Thus, an electric field along the direction of the arrow  300  is produced in the first conductive layer  110 , and the voltage value V A  at the position A is related to the distances L 1  and L 2 . Here if the position A is touched and accordingly the first conductive layer  110  and the second conductive layer  120  are contacted, one of the first conductive wires  112 A˜ 112 D detects the voltage value V A  and accordingly the coordinates of the position A touched by the user along the direction of the arrow  300  can be obtained. After foregoing two phases are completed, the location of the position A touched by the user can be accurately positioned, and the instruction input by the user can then be carried out. In other words, when the touch panel  100  is operated in the 5-wire resistive touch sensing mode, the voltages supplied to the second conductive wires  122 A˜ 122 D have to be switched so that electric fields in different directions can be produced and accordingly the position touched by the user can be accurately sensed. 
     As described above, in the present embodiment, the second conductive layer  120  is used as a signal input layer and the first conductive layer  110  is used as a signal sensing layer. However, the present invention is not limited thereto, and the first conductive layer  110  may also be used as the signal input layer, and the second conductive layer  120  may also be used as the signal sensing layer. In other words, the voltages supplied to the second conductive wires  122 A˜ 122 D may also be supplied to the first conductive wires  112 A˜ 112 D, and one of the second conductive wires  122 A˜ 122 D may be used for touch sensing. Since the first conductive wires  112 A˜ 112 D and the second conductive wires  122 A˜ 122 D are respectively located at the corners of the conductive layers  110  and  120 , the power lines caused by the first conductive wires  112 A˜ 112 D and the second conductive wires  122 A˜ 122 D enclose the entire conductive layers  110  and  120 . Hence, any position in the first conductive layer  110  and the second conductive layer  120  touched can be sensed. However, the present invention is not limited to foregoing example, and in another embodiment of the present invention, the conductive wires may also be disposed at the sides of the conductive layer which is used as the signal sensing layer with affecting the functions of the touch panel  100 . 
     Generally speaking, when the touch panel  100  is operated in the 5-wire resistive touch sensing mode, the touch panel  100  will not sense incorrectly even when there is water or conductive particle drops thereon. In other words, if there is conductive particle falling on the touch panel  100 , the touch panel  100  can be switched to the 5-wire resistive touch sensing mode so that incorrect touch sensing can be avoided. In addition, the signal sensing layer is used only for sensing, so that any defect or small crack thereon will not affect the value or state of the sensed signal. Namely, the touch sensing function of the touch panel  100  is not affected even when the conductive layer in the touch panel  100  which is served as the signal sensing layer has some small cracks. Thereby, the touch panel  100  provided by the present invention has longer lifespan. 
     Since the touch panel  100  can be operated in the surface capacitive touch sensing mode or the 5-wire resistive touch sensing mode, a user can use a conductive object or a non-conductive object to operate the touch panel  100 . If the user uses a finger to operate the touch panel, the touch panel  100  works in the surface capacitive touch sensing mode, and if the user uses a gloved finger or a plastic pen to operate the touch panel, the touch panel  100  can then be switched to being operated in the 5-wire resistive touch sensing mode. If the user uses a finger to operate the touch panel  100 , the touch panel  100  may also be switched to the 5-wire resistive touch sensing mode so as to avoid incorrect sensing caused by conductive object contamination. Actually, the timing for switching the touch sensing mode of the touch panel  100  is not restricted in the present invention, and the touch sensing mode of the touch panel  100  can be selected and switched according to different application environments or the habit of different users. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.