Abstract:
A resistive touch panel includes a first substrate, a second substratem and a driving circuit. A first conductive layer is disposed on the first substrate and includes a first, a second, a third, and a fourth corners which are different from each other. A first, a second, a third, and a fourth conducting wires are electrically connected to the first, second, third, and fourth corners, respectively. The second substrate is disposed parallel to the first substrate. A second conductive layer is disposed on the second substrate and faces the first conductive layer. A fifth conducting wire is electrically connected to a first side of the second conductive layer while a sixth conducting wire is electrically connected to a second side of the second conductive layer. The driving circuit is electrically connected to the first, second, third, fourth, fifth, and sixth conducting wires.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    (a) Field of the Invention 
         [0002]    The invention relates to a driving method, particularly to a driving method for a resistive touch panel. 
         [0003]    (b) Description of the Related Art 
         [0004]    In general, a four-wire or five-wire type resistive touch panel is extensively used in various touch-control electronic products. However, confined to its established architecture, the four-wire or five-wire type resistive touch panel fails to detect a multi-touch operation. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    The invention provides a driving method for a resistive touch panel capable of accurately recognizing a single-touch operation or a multi-touch operation performed on a six-wire type resistive touch panel and accurately interpreting each gesture for the multi-touch operation. 
         [0006]    According to an embodiment of the invention, a resistive touch panel includes a first substrate, a second substrate, a first conductive layer, a second conductive layer, a first, a second, a third, a fourth, a fifth and a sixth conducting wires, and a driving circuit. The first conductive layer is disposed on the first substrate and includes a first, a second, a third, and a fourth corners that are different from each other. The first conducting wire is disposed on the first substrate and electrically connected to the first corner. The second conducting wire is disposed on the first substrate and electrically connected to the second corner. The third conducting wire is disposed on the first substrate and electrically connected to the third corner. The fourth conducting wire is disposed on the first substrate and electrically connected to the fourth corner. The second substrate is disposed parallel to the first substrate. The second conductive layer is disposed on the second substrate and faces the first conductive layer. The fifth conducting wire is electrically connected to a first side of the second conductive layer. The sixth conducting wire is electrically connected to a second side of the second conductive layer. The driving circuit is electrically connected to the first, second, third, fourth, fifth, and sixth conducting wires. 
         [0007]    Further, the invention also provides a driving method used for driving a resistive touch panel recited in the above embodiment. The driving method includes the following steps. A first voltage is supplied to the sixth conducting wire and a second voltage is supplied to the second conducting wire, where the first voltage is larger than the second voltage. When the touch panel is touched, a first-state detection voltage is outputted by the fifth conducting wire and a second-state detection voltage is outputted by the fourth conducting wire. According to the first-state detection voltage and the second-state detection voltage, a contact resistance is calculated out. It is determined whether a single-touch operation or a multi-touch operation is performed according to the contact resistance. When a multi-touch operation is performed, different multi-points on the touch panel are away from each other or close to each other according to the comparison of a current contact resistance with a previous contact resistance. Thereby, gestures performed on the resistive touch panel are recognized. 
         [0008]    Other objects and advantages of the invention can be better understood from the technical characteristics disclosed by the invention. In order to clarify the above mentioned and other objects and advantages of the invention, examples accompanying with figures are disposed and described in details in the following. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1A  shows a schematic diagram illustrating a touch panel according to an embodiment of the invention. 
           [0010]      FIG. 1B  shows a flow chart illustrating a driving method for the touch panel shown in  FIG. 1A . 
           [0011]      FIG. 2A  shows a schematic diagram illustrating a single-touch operation for the touch panel shown in  FIG. 1A . 
           [0012]      FIG. 2B  shows a schematic diagram illustrating an equivalent circuit of  FIG. 2A . 
           [0013]      FIG. 3A  shows a schematic diagram illustrating a multi-touch operation for the touch panel shown in  FIG. 1A . 
           [0014]      FIG. 3B  shows a schematic diagram illustrating an equivalent circuit of  FIG. 3A . 
           [0015]      FIG. 4A  shows a schematic diagram illustrating another multi-touch operation for the touch panel shown in  FIG. 1A . 
           [0016]      FIG. 4B  shows a schematic diagram illustrating an equivalent circuit of  FIG. 4A . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]      FIG. 1A  shows a schematic diagram illustrating a touch panel according to an embodiment of the invention. Referring to  FIG. 1A , the touch panel  100  includes a substrate  110 , a substrate  120 , and a driving circuit  130 . The touch panel  100  in this embodiment may be a resistive touch panel. On a surface of the substrate  110  facing the substrate  120 , a transparent conductive layer  112  and conducting wires W 1 , W 2 , W 3  and W 4  are disposed. As shown in  FIG. 1A , the portion on the upper left corner of the transparent conductive layer  112  is electrically connected to the conducting wire W 1 , the portion on the lower left corner is electrically connected to the conducting wire W 2 , the portion on the lower right corner is electrically connected to the conducting wire W 3 , and the portion on the upper right corner is electrically connected to the conducting wire W 4 . Thus, the portion on each corner of the transparent conductive layer  112  is electrically connected to the driving circuit  130  separately through each conducting wire W 1 , W 2 , W 3  and W 4 . That is, the transparent conductive layer  112  is substantially a rectangular conductive layer, and the four corners of the transparent conductive layer  112  are electrically connected to the driving circuit  130  through the conducting wires W 1 , W 2 , W 3  and W 4 , respectively. 
         [0018]    Besides, on the periphery of the transparent conductive layer  112 , a plurality of conductor patterns  114  are disposed on and in direct contact with the transparent conductive layer  112  to prevent an electric field on the side of the transparent conductive layer  112  from being deformed due to the resistance characteristic of the transparent conductive layer  112 . The material of the conductor patterns  114  may be metal such as silver. In this embodiment, the conductor patterns  114  (indicated by dashed lines) may include a plurality of straight line segments, bended line segments, or curved line segments. 
         [0019]    On the surface of the substrate  120  facing the substrate  110 , a transparent conductive layer  122 , a conductor stripe  124 , and a conductor stripe  126  are disposed. The conductor stripe  124  is disposed on one side of the transparent conductive layer  122  and directly in contact with the transparent conductive layer  122 . The conductor stripe  126  is formed on an opposite side of the transparent conductive layer  122  and directly in contact with the transparent conductive layer  122 . In addition, conducting wires W 5  and W 6  are connected to the conductor stripes  124  and  126 , respectively. 
         [0020]    It should be noted that the wording upper, lower, right or left mentioned in the above description is uses to illustrate an embodiment with reference to a figure for convenience, but not limit the scope of the invention. 
         [0021]    In this embodiment, the driving circuit  130  may be connected to the touch panel  100  externally or built inside the substrate  110  or the substrate  120 . In the driving circuit  130 , the driver  132  is electrically connected to the conducting wire W 1 , the driver  134  is electrically connected to the conducting wire W 2 , the driver  136  is electrically connected to the conducting wire W 3 , the driver  138  is electrically connected to the conducting wire W 4 , the detector  140  is electrically connected to the conducting wire W 4  through a switch SW 1 , the detector  142  is electrically connected to the conducting wire W 5 , the driver  144  is electrically connected to the conducting wire W 6  through a resistor R 0 , and the detector  146  is electrically connected to the conducting wire W 6  through a switch SW 2 . In this embodiment, the drivers  132 ,  134 ,  136 ,  138  and  144  may output a system voltage or a ground voltage, or they may be in a high-impedance (Hi-Z) state. The detectors  140 ,  142 , and  146  may be used to detect voltage values and have high input impedance. 
         [0022]    Please refer to  FIGS. 1A and 1B , where it is assumed that a single-touch operation is performed on the touch panel  100 . First, the drivers  136  and  138  supply the system voltage separately to the conducting wires W 3  and W 4 , and the drivers  132  and  134  supply the ground voltage separately to the conducting wires W 1  and W 2  (step S 102 ). At the time, the driver  144  is under the Hi-Z state, and the switches SW 1  and SW 2  are turned off to obtain a detection voltage on the touch point with respect to the X axis. 
         [0023]    Specifically, the voltage on the right-hand side is higher than the voltage on the left-hand side of the transparent conductive layer  112 . When a touch operation is performed, the transparent conductive layer  112  and the transparent conductive layer  122  are conducted at the touch point. Therefore, the voltage division at the touch point is transmitted to the conductor stripe  124  of the substrate  120  and finally to the detector  142  through the conducting wire W 5  (step S 104 ), where the voltage division equals a detection voltage on the X-axis. When the touch point is closer to the left-hand side of the transparent conductive layer  112 , the detection voltage on the X-axis becomes much closer to the ground voltage. Therefore, the magnitude of the detection voltage can be used to determine the position of the touch point. 
         [0024]    Then, the drivers  134  and  136  supply the system voltage to the conducting wires W 2  and W 3 , respectively, and the drivers  132  and  138  respectively supply the ground voltage to the conducting wires W 1  and W 4  (step S 106 ). At the time, the driver  144  is under the Hi-Z state and the switches SW 1  and SW 2  are off, so that the detection voltage at the touch point corresponding to the Y axis can be detected. Similarly, the detector  142  receives the detection voltage on the Y-axis (step S 108 ). 
         [0025]    Additionally, the touch panel  100  according to this embodiment may recognize different touch modes and different gestures of a user. For example, the driving circuit  130  is set under the following conditions to recognize a touch mode. The driver  144  supplies the system voltage to the conducting wire W 6 , and the driver  134  supplies the ground voltage to the conducting wire W 2  (step S 110 ). The drivers  132 ,  136 , and  138  are each under the Hi-Z state. In addition, the switches SW 1  and SW 2  are turned on. Under the circumstance, it can be recognized that whether the touch panel  100  is touched and that whether a single-touch operation or a multi-touch operation is performed. 
         [0026]    Specifically,  FIG. 2A  shows a schematic diagram illustrating a single-touch operation performed on the touch panel shown in  FIG. 1A .  FIG. 2B  shows a schematic diagram illustrating an equivalent circuit of  FIG. 2A . Referring to  FIGS. 1A and 2A , when a user touches the point C 1 , the touch point C 1  on the transparent conductive layers  112  and  122  forms a resistor R 22  (having a contact resistance), a resistor R 23  forms between the touch point C 1  and the conducting wire W 2 , and a resistor R 21  forms between the touch point C 1  and the conducting wire W 6 , where the above resistors are used to represent the impedance characteristics of the transparent conductive layers  112  and  122 . 
         [0027]    Please refer to both  FIGS. 1A and 2B , since the driver  144  is electrically connected to the conducting wire W 6  through the resistor R 0 , the resistor R 0  is serially connected to the resistors R 21 , R 22 , and R 23 . A node between the resistors R 0  and R 21  outputs a voltage Vw 6 , a node between the resistors R 21  and R 22  outputs a first-state detection voltage Vs 1 , and a node between the resistors R 22  and R 23  outputs a second-state detection voltage Vs 2 . The voltage Vw 6 , the first-state detection voltage Vs 1 , the second-state detection voltage Vs 2  are transmitted to the detectors  146 ,  142 , and  140 , respectively (step S 112 ). 
         [0028]    It is assumed that the system voltage Vcc is 3.3V, the resistor R 0  is 300Ω, the voltage Vw 6  is 2.36V, the first-state detection voltage Vs 1  is 1.97V, and the second-state detection voltage Vs 2  is 0.875V. According to the above data, the current I flowing through the conducting wire W 6  is calculated to be (3.3−2.36)/300=3.13 mA. Then, the current I and the state detection voltages Vs 1  and Vs 2  are used to calculate the contact resistance of the resistor R 22  (step S 114 ); that is, the contact resistance is (1.97−0.875)/3.13=350Ω. 
         [0029]    As described in the above, when the touch panel  100  is initialized, a user is guided to perform a single-touch operation (that is, the touch panel  100  is under a single-point touched state). Therefore, during initialization, the touch panel  100  stores the calculated contact resistance as a preset contact resistance. When the touch panel  100  is under a multi-point touched state, the current flow path under the multi-point touched state is different from that under the single-point touched state, and thus the impedance distribution is also different. The touch panel  100  compares a currently received contact resistance with the preset contact resistance to determine whether a single-touch operation or a multi-touch operation is performed (step S 116 ). 
         [0030]    Besides, an impedance threshold value can be set to clearly distinguish either a single-touch operation or a multi-touch operation is performed. The impedance threshold value can be set as a weighted contact resistance; that is, the impedance threshold value is the product of a preset contact resistance and a ratio, and the ratio is in the range of 0.3-0.8 selected according to the circuit design. 
         [0031]    When the touch panel  100  is under a single-point touched state, by the step S 102  to the step  108 , the positions of the touch points on the X-axis and Y-axis are obtained respectively according to the X-axis detection voltage and the Y-axis detection voltage (step S 118 ). This positioning process is similar to a positioning method used in a five-wire type touch panel and well known to those skilled in the art. Thus, the details will not be given hereinafter. 
         [0032]    When the touch panel  100  is under the multi-point touched state, according to this embodiment, a current contact resistance is compared with a previous contact resistance to determine whether different touch points are close to or away from each other (step S 120 ). Besides, when the touch panel  100  is not touched, the voltage acquired by the detector  146  in the driving circuit  130  is equal to the system voltage outputted by the driver  144 . Thus, when the touch panel  100  is not touched, the execution flow is in the order of steps S 102 , S 104 , S 106 , S 108  and then ends in the step S 110 . The following will describe the method to determine whether different touch points tend to be close to or away from each other. 
         [0033]      FIG. 3A  shows a schematic diagram illustrating a multi-touch operation performed on the touch panel shown in  FIG. 1A .  FIG. 3B  shows a schematic diagram illustrating an equivalent circuit of  FIG. 3A . In one embodiment, the touch panel shown in FIG  1 A may be a six-wire type resistive touch panel. Referring to  FIG. 3A , when a user touches points C 2  and C 3 , the contact points on the transparent conductive layers  112  and  122  form resistors R 32  and R 35 . Resistors R 33  and R 36  are formed between the touch points C 2  and C 3  and the conducting wire W 2 , resistors R 3   d  and R 3   c  are formed between the touch points C 2  and C 3  and the conducting wire W 4 , resistors R 3   b  and R 3   a  are formed between the touch points C 2  and C 3  and the conducting wire W 5 , resistors R 31  and R 34  are formed between the touch points C 2  and C 3  and the conducting wire W 6 , and resistors R 37  and R 38  are formed between the touch point C 2  and C 3  on the transparent conductive layers  112  and  122 , respectively. 
         [0034]    Referring to  FIG. 3B , in the step  5112 , since the touch panel  100  is touched, the voltage Vw 6 , the state detection voltage Vs 1  and the state detection voltage Vs 2  are outputted. It is assumed that the system voltage Vcc is 3.3V, the resistor R 0  is 300Ω, the voltage Vw 6  is 1.82V, the first-state detection voltage Vs 1  is 1.55V, and the second-state detection voltage Vs 2  is 0.742V. According to the above data, a current I is calculated to be (3.3−1.82)/300=4.92 mA, and then the contact resistance is (1.55−0.742)/4.92=164.2Ω. Under the multi-point touched state, the calculated contact resistance is an equivalent resistance between the conducting wires W 4  and W 5  but not an actual resistance of the resistor R 32  or R 35 . From the calculated result, the contact resistance (=164.2Ω) under the multi-point touched state is far smaller than a preset contact resistance (=350Ω), so that the touch panel  100  is recognized as a multi-touch operation being performed. 
         [0035]    Besides, under the multi-point touched state, the resistance of the resistor between different touch points varies due to the different distances between different touch points, and thus this may affect the magnitude of the contact resistance (an equivalent resistance between the conducting wires W 4  and W 5 ) and the state detection voltages Vs 1  and Vs 2 .  FIG. 4A  shows a schematic diagram illustrating another multi-touch operation performed on the touch panel shown in  FIG. 1A .  FIG. 4B  shows a schematic diagram illustrating an equivalent circuit of  FIG. 4A . Referring to  FIGS. 3A and 4A , the distribution of the resistors of  FIG. 4A  is similar to that of  FIG. 3A . Thus, the details will not be given hereinafter. The distance between the touch points C 4  and C 5  is smaller than the distance between the touch points C 2  and C 3 . In that case, referring to  FIG. 4B , the voltage Vw 6  is 1.83V, the first-state detection voltage Vs 1  is 1.54V, and the second-state detection voltage Vs 2  is 0.685V. According to the above data, a current I is calculated to be (3.3−1.83)/300=4.89 mA, and then the contact resistance is (1.55−0.685)/4.89=174.8Ω. 
         [0036]    Therefore, when different touch points become closer, the calculated contact resistance also becomes higher. Thus, under the multi-point touched state, when a current contact resistance is larger than a previous contact resistance, it means that different touch points are approaching to close to each other. On the contrary, when a current contact resistance is smaller than a previous contact resistance, it means that different touch points are moving away from each other. Thus, a gesture performed on the touch panel is recognized to conduct a corresponding operation (such as shrinking or enlarging an image). It should be noted that the voltage values and the resistance values described in the above are only examples but not used to limit the scope of the invention. 
         [0037]    In conclusion, the resistive touch panel and the driving method according to the above embodiments form an architecture of a six-wire type resistive touch panel. The detectors are used to acquire a first state detection voltage and a second state detection voltage, and then a contact resistance is calculated according to the first and the second state detection voltages. 
         [0038]    The contact resistance is used to determine whether a single-touch or a multi-touch operation is performed. Under a multi-point touched state, a current contact resistance is compared with a previous contact resistance to determine whether different touch points are approaching to close to each other or moving away from each other. Thus, the resistive touch panel is allowed to recognize a gesture of a user performed thereon and conduct a corresponding operation according to the recognized gesture. 
         [0039]    Although the present invention has been fully described by the above embodiments, the embodiments should not constitute the limitation of the scope of the invention. Various modifications or changes can be made by those who are skilled in the art without deviating from the spirit of the invention.