Abstract:
The present disclosure provides a detection method for a touch panel. The touch panel comprises a plurality of a first sensing electrode and a plurality of a second sensing electrode. The detection method comprises sensing a total self-capacitance of the first sensing electrodes, a plurality of self-capacitance of the second electrodes and a plurality of mutual capacitance when an object touches the touch panel; obtaining a plurality of self-capacitance of the first sensing electrodes according to the total self-capacitance of the first sensing electrodes, the self-capacitances of the second electrodes and the mutual capacitances and calculating coordinates of an object on the touch panel according to the self-capacitances of the first sensing electrodes.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a sensing method and related touch panel, and more particularly to a sensing method of integrating a self-capacitance and a mutual-capacitance for a touch panel. 
         [0003]    2. Description of the Prior Art 
         [0004]    Touch screen devices provide an instinct and simple operation for a user so they have been widely used in all kind of consuming electronic products. General speaking, a touch screen device is composed of a transparent touch panel and a display device. By attaching the touch panel onto the display device, a touch function and display function can be carried out. Among various touch application, a capacitive touch panel has become the most popular. 
         [0005]    The operation principle of the capacitive touch panel is that Indium tin oxide (ITO) electrodes on the touch panel generate a capacitance change due to the touch of a human finger or an object, which can be converted into readable coordinates for an operation system. The detailed operation of the capacitive touch panel can be referenced by U.S. Pat. No. 4,087,625 and US patent US 2010/0309167A1, which discloses a single layer ITO structure (triangle single-layer self-capacitance) to achieve single touch design. 
         [0006]    Please refer to  FIG. 1A , which is a triangle single layer self-capacitance touch panel  10 . In  FIG. 1A , the slashed blocks represent multiple sensing lines while the solid lines outside of the slashed blocks connect to a sensing chip. The main drawback of  FIG. 1A  is that the touch function can only work with a single finger plus a gesture because two or more fingers are not distinguishable at the fork part of the triangle shape. Please refer to  FIG. 1B . When two fingers touch the touch panel on the same triangle channel, it is not able to distinguish one finger or two finger touch. In this situation, self-capacitance sensing method does not meet the requirement for multi-touch while reporting. 
         [0007]    On the other hand, a single layer mutual capacitance is disclosed in the prior. For the single layer mutual capacitance, the coordinates cannot be retrieved by a touch on a single basic unit but a touch on two or more basic units will do the trick. The mutual capacitance may require more channels than the self-capacitance in the same size does. Please refer to  FIG. 1C , which illustrates that the mutual capacitance adopts the same approach of proactively scanning for LCD. When a certain line on Y axis is scanned, the capacitance changes on all X axis are simultaneously sensed. The capacitance change on each intersection of X axis and Y axis can be obtained by scanning in an order. In this situation, the ghost points caused by the self-capacitance no longer exist. In theory, the number of coordinates is reported, depending on the number of the intersections of X axis and Y axis. Since the multi-touch consumes the system resource, more multi-touch points may need a faster control chip and have higher power consumption. 
       SUMMARY OF THE INVENTION 
       [0008]    It&#39;s therefore an objective of the present invention to provide a sensing method for a touch panel. 
         [0009]    The present invention discloses a sensing method for a touch panel. The touch panel includes a plurality of first sensing electrodes and a plurality of second sensing electrodes. The first sensing electrodes and the second sensing electrodes forma plurality of sensing areas. The sensing method comprises sensing a total self-capacitance of the first sensing electrodes, a plurality of self-capacitances of the second electrodes and a plurality of mutual-capacitances of the sensing areas when an object touches the touch panel, wherein the first sensing electrodes are coupled to a common node while the second sensing electrodes are coupled to different nodes; obtaining a plurality of self-capacitances of the first sensing electrodes according to the total self-capacitance of the first sensing electrodes, the self-capacitances of the second electrodes and the mutual-capacitances of the sensing areas; and calculating coordinates of the object on the touch panel according to the self-capacitances of the first sensing electrodes. 
         [0010]    The present invention further discloses a touch panel. The touch panel comprises a plurality of first sensing electrodes, a plurality of second sensing electrodes and a calculation unit. The first sensing electrodes are coupled to a common node, for detecting a total self-capacitance of the first sensing electrodes when an object touches the touch panel. Each first sensing electrode comprises at least one first convex part and at least one first concave part. The second sensing electrodes are couple to a plurality of nodes, for forming a plurality of sensing area with the first sensing electrodes and sensing a plurality of self-capacitance of the second sensing electrodes when the object touches the touch panel. Each second electrode comprises at least one second convex part and at least one second concave part. The calculation unit is used for obtaining a plurality of self-capacitances of the first electrodes according to the total self-capacitance of the first sensing electrodes, the self-capacitances of the second electrodes and a plurality of mutual-capacitances of the sensing area and calculating coordinates of the object on the touch panel according to the self-capacitances of the first sensing electrodes. 
         [0011]    These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1A  is a triangle single layer self-capacitance touch panel in the prior art. 
           [0013]      FIG. 1B  illustrates that four channels inside a touch chip generate a signal corresponding to a capacitance change. 
           [0014]      FIG. 1C  illustrates that the mutual capacitance adopts the LCD device proactive scanning approach. 
           [0015]      FIG. 2  is a schematic diagram of an exemplary sensing process. 
           [0016]      FIG. 3  is an exemplary pattern of a touch panel. 
           [0017]      FIG. 4  is an exemplary pattern of a touch panel. 
           [0018]      FIG. 5  is an exemplary pattern of a touch panel. 
           [0019]      FIG. 6  is an exemplary pattern of a touch panel. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    Please refer to  FIG. 2 , which is a schematic diagram of an exemplary sensing process  20 . The sensing process  20  is used in a touch panel for detecting the coordinates of an object on the touch panel. The touch panel includes multiple sensing electrodes X 1 , X 2 , . . . , Xn and multiple sensing electrodes Y 1 , Y 2 , . . . , Yn, which form multiple sensing areas A 1 , A 2 , . . . , An. The sensing process  20  includes the following steps: 
         [0021]    Step  200 : Start. 
         [0022]    Step  202 : Sense a total self-capacitance SC_total of the sensing electrodes X 1 , X 2 , . . . , Xn, individual self-capacitances sc_y 1 , sc_y 2 , . . . , sc_yn of the sensing electrodes Y 1 , Y 2 , . . . , Yn, and the mutual-capacitances mc_ 1 , mc_ 2 , . . . , mc_n of the sensing areas A 1 , A 2  , . . . , An of the touch panel, wherein the sensing electrodes X 1 , X 2  , . . . , Xn are connected to a common node. 
         [0023]    Step  204 : Obtain individual self-capacitance sc_x 1 , sc_x 2 , . . . , sc_xn according to the total self-capacitance SC_total, the individual self-capacitances sc_y 1 , sc_y 2 , . . . , sc_yn and the mutual-capacitances mc_ 1 , mc_ 2 , . . . , mc_n. 
         [0024]    Step  206 : Calculate the coordinates of the object on the touch panel according to the individual self-capacitances sc_x 1 , sc_x 2 , . . . , sc_xn. 
         [0025]    Step  208 : End. 
         [0026]    According to the process  20 , the touch panel generates the capacitance change when the object (e.g. a finger or a stylus) touches the touch panel. The total self-capacitance SC_total of the sensing electrodes X 1 , X 2 , . . . , Xn, the individual self-capacitances sc_y 1 , sc_y 2 , . . . , sc_y 3  of the sensing electrodes Y 1 , Y 2 , . . . , Yn, and the mutual-capacitances of the sensing areas A 1 , A 2 , . . . , An can be sensed through the sensing electrodes X 1 , X 2 , . . . , Xn and the sensing electrodes Y 1 , Y 2 , . . . , Yn and further the individual self-capacitances sc_x 1 , sc_x 2 , . . . , sc_xn can be calculated and obtained. According to the individual self-capacitances sc_x 1 , sc_x 2 , . . . , sc_xn, the example of the present disclosure can calculates the coordinates of the object on the touch panel. Please note that the way of calculating the coordinates of the object on the touch panel according to the self-capacitances sc_xl, sc_x 2 , . . . , sc_xn is well known by those in the art, and thus omitted herein. Briefly, the example of the present disclosure first senses the mutual-capacitances mc_ 1 , mc_ 2 , . . . , mc_n of the sensing areas A 1 , A 2 , . . . , An to roughly estimate which sensing area the object might be at. Given the total self-capacitance SC_total and the mutual capacitance of the certain sensing area, the self-capacitance of each sensing electrode in that sensing area can be calculated, and further the accurate coordinates can be obtained. In this situation, the example of the present disclosure can solve the problem that the single layer self-capacitance structure is not able to distinguish more than two fingers and achieve a better accuracy with less channels. 
         [0027]    In addition, the sensing electrodes Y 1 , Y 2 , . . . , Yn are coupled to different nodes. Namely, each of the sensing electrodes Y 1 , Y 2 , . . . , Yn is independent. Each of the sensing electrodes X 1 , X 2 , . . . , Xn includes one or more first convex parts and one or more first concave parts while each of the sensing electrodes Y 1 , Y 2 , . . . , Yn includes one or more second convex parts and one or more second concave parts. To form the sensing areas A 1 , A 2 , . . . , An, the one or more first convex parts of each of the sensing electrodes X 1 , X 2 , . . . , Xn are embedded into the one or more second concave parts of each of the sensing electrodes Y 1 , Y 2 , . . . , Yn and the one or more second convex parts of each of the sensing electrodes Y 1 , Y 2 , . . . , Yn are embedded into the one or more first concave parts of each of the sensing electrodes X 1 , X 2 , . . . , Xn. Preferably, the shape of the one or more first convex parts, first concave parts, second convex parts, and second concave parts is a triangle, but not limited herein. In this situation, each of the sensing areas A 1 , A 2 , . . . , An is a triangle single layer self-capacitance unit. 
         [0028]    On the other hand, the sensing electrodes X 1 , X 2 , . . . , Xn could be multiple sensing lines and the sensing electrodes Y 1 , Y 2 , . . . , Yn could be multiple driving lines. Or the sensing electrodes X 1 , X 2 , . . . , Xn could be multiple driving lines and the sensing electrodes Y 1 , Y 2 , . . . , Yn could be multiple sensing lines. Thus, the sensing electrodes X 1 , X 2 , . . . , Xn and the sensing electrodes Y 1 , Y 2 , . . . , Yn form a single layer mutual-capacitance unit. To put it simple, the example of the present disclosure integrates the sensing method of the single layer self-capacitance and the sensing method of the single layer mutual-capacitance. Since the sensing electrodes X 1 , X 2 , . . . , Xn are connected to a common node, the total self-capacitance is equal to the summation of the individual self-capacitances sc_x 1 , sc_x 2 , . . . , sc_xn of the sensing electrodes X 1 , X 2 , . . . , Xn. 
         [0029]    Further, the self-capacitance of any of the sensing areas A 1 , A 2 , . . . , An is equal to the summation of self-capacitances of all sensing electrodes in that sensing area. For example, A self-capacitance sc_a 1  of the sensing area A 1  is equal to the summation of self-capacitances of the sensing electrodes X 1  and Y 1 . Therefore, An equation can be obtained: sc_a 1 =sc_x+sc_y 1 , wherein sc_y 1  is given. For the same token, the individual self-capacitances sc_a 1 , sc_a 2 , . . . , sc_an of the sensing areas A 1 , A 2 , . . . , An can be obtained. 
         [0030]    Moreover, the ratio of the mutual-capacitance (e.g. the mutual-capacitance mc_ 1 ) of one sensing area, for example the sensing area A 1 , and the mutual-capacitance (e.g. the mutual-capacitance mc_ 2 ) of another sensing area, for example the sensing area A 2 , is equal to a ratio of the self-capacitance (e.g. sc_a 1 ) of the sensing area A 1  and the self-capacitance (e.g. sc_a 2 ) of the sensing area A 2 . Namely, (mc_ 1 /mc_ 2 )=(sc_a 1 /sc_a 2 ). Since sc_a 1 =sc_x 1 +sc_y 1  and sc_a 2 =sc_x 2 +sc_y 2 , (sc_a 1 /sc a 2 )can be re-written as (sc_x 1 +sc_y 1 )/(sc_x 2 +sc_y 2 ). Given the self-capacitance sc y 1  of the sensing electrode Y 1  and the self-capacitance sc_y 2  of the sensing electrode Y 2 , the individual self-capacitances sc_x 1  and sc_x 2  of the sensing electrodes X 1  and X 2  can be derived from the equations above. By the same token, All self-capacitances sc_x 1 , sc_x 2 , . . . , sc_xn of the sensing electrodes X 1 , X 2 , . . . , Xn can be obtained. 
         [0031]    Please refer to  FIG. 3 , which is an exemplary pattern  30  of a touch panel. The pattern  30  includes sensing electrodes X 11 , X 12 , X 13 , . . . , X 54  and sensing electrodes Y 11 , Y 12 , Y 13 , . . . , Y 54 . For simplicity, the sensing electrodes X 11 , X 12 , X 13  and X 14  in the first column are taken as an example. The sensing electrodes X 11 , X 12 , X 13 , X 14  and the sensing electrodes Y 11 , Y 12 , Y 13 , Y 14  form sensing areas A 1 , A 2 , A 3 , A 4 . The sensing electrodes X 11 , X 12 , X 13 , X 14  are connected to a common node while the sensing electrodes Y 11 , Y 12 , Y 13 , Y 14  are connected to different nodes, independently. When an object touches the touch panel, A total self-capacitance SC_total of the sensing electrodes X 11 , X 12 , X 13 , X 14 , the individual self-capacitances sc_y 11 , sc_y 12 , sc_y 13 , sc_y 14  of the sensing electrodes Y 11 , Y 12 , Y 13 , Y 14  and the mutual-capacitances mc_ 1 , mc_ 2 , mc_ 3 , mc_ 4  of the sensing areas A 1 , A 2 , A 3 , A 4  are sensed. Thus, equations (1), (2), (3), (4), (5) are derived: 
         [0000]        SC _total= sc   —   x 11+sc —   x 12+ sc   —   x 13+ sc   —   x 14  (1)
 
         [0000]      ( mc   — 1/ mc   — 2)=(sc —   x 11+ sc   —   y 11)/( sc   —   x 12+ sc   —   y 12)  (2)
 
         [0000]      ( mc   — 2/ mc   — 3)=(sc —   x 12+ sc   —   y 12)/( sc   —   x 13+ sc   —   y 13)  (3)
 
         [0000]      ( mc   — 3/ mc   — 4)=(sc —   x 13+ sc   —   y 13)/( sc   —   x 14+ sc   —   y 14)  (4)
 
         [0000]      ( mc   — 1/ mc   — 4)=(sc —   x 11+ sc   —   y 11)/( sc   —   x 14+ sc   —   y 14)  (5)
 
         [0032]    Through a system of the equations (1), (2), (3), (4), (5), the self-capacitances sc_x 11 , sc_x 12 , sc_x 13 , sc_x 14  of the sensing electrodes X 11 , X 12 , X 13 , X 14  can be obtained. Then, the coordinates of the object on the touch panel can be calculated according to the individual self-capacitances sc_x 11 , sc_x 12 , sc_x 13 , sc_x 14  of the sensing electrodes X 11 , X 12 , X 13 , X 14 . 
         [0033]    Please refer to  FIG. 4 , which is an exemplary pattern  40  of a touch panel. The pattern  40  includes the sensing electrodes X 11 , X 12 , X 13 , . . . , X 54  and the sensing electrodes Y 11 , Y 12 , Y 13 , . . . , Y 54 . For simplicity, the sensing electrodes X 11 , X 12 , X 13 , X 14  and the sensing Y 11 , Y 12 , Y 13 , Y 14  are taken as an example. The sensing electrodes X 11 , X 12 , X 13 , X 14  and the sensing electrodes Y 11 , Y 12 , Y 13 , Y 14  form the sensing areas A 1 , A 2 , A 3 , A 4 . The sensing electrodes X 11 , X 12  are connected to a common node, and the sensing electrodes X 13 , X 14  are connected to another common node. The sensing electrodes Y 11 , Y 12 , Y 13 , Y 14  are connected to different nodes independently. For simplicity, only the sensing areas A 1 , A 2  are taken as an example. When an object touches the touch panel, A total self-capacitance SC_total, individual self-capacitances sc_y 11 , sc_y 12  of the sensing electrodes Y 11 , Y 12 , the mutual-capacitances mc_ 1 , mc_ 2  of the sensing areas A 1 , A 2  can be obtained. Thus, equations (1′), (2′) can be derived: 
         [0000]        SC _total= sc   —   x 11+ sc   —   x 12  (1′)
 
         [0000]      ( mc   — 1/ mc   — 2)=( sc   —   x 11+ sc   —   y 11)/( sc   —   x 12+ sc   —   y 12)  (2′)
 
         [0034]    Through a system of equations (1′), (2′) above, the individual self-capacitances sc_x 11 , sc_x 12  of the sensing electrodes X 11 , X 12  can be obtained. Then, the individual self-capacitances sc_x 13 , sc_x 14  can be obtained by the same token. The coordinates of the object on the touch panel can be calculated according the individual self-capacitances sc_x 11 , sc_x 12 , sc_x 13 , sc_x 14 . 
         [0035]    Please note that the main purpose of the present disclosure is to obtain the individual self-capacitances sc_x 11 , sc_x 12 , sc_x 13 , sc_x 14  of the sensing electrodes X 11 , X 12 , X 13 , X 14  according to the total self-capacitance, the self-capacitances sc_y 11 , sc_y 12 , sc_y 13 , sc_y 14  and the mutual-capacitances mc_ 1 , mc_ 2 , mc_ 3 , mc_ 4 , and further calculate the coordinates of the object according to the individual self-capacitances sc_x 11 , sc_x 12 , sc_x 13 , sc_x 14  of the sensing electrodes X 11 , X 12 , X 13 , X 14 . Therefore, A pattern of the touch panel is not limited to the patterns  30  and  40 , and the number of the electrodes in the patterns  30  and  40  is not limited herein. 
         [0036]    Please refer to  FIG. 5 , which is an exemplary pattern  50  of a touch panel. The pattern  50  includes sensing electrodes X 1 , X 2  and sensing electrodes Y 1 , Y 2 . The sensing electrodes X 1 , X 2  and the sensing electrodes Y 1 , Y 2  form sensing areas A 1 , A 2 . The sensing electrodes X 1 , X 2  are connected to a common node and the sensing electrodes Y 1 , Y 2  are connected to different nodes, independently. The way of calculating the individual self-capacitances sc_x 1 , sc_x 2  can be found above, and thus omitted herein. 
         [0037]    Please refer to  FIG. 6 , which is an exemplary pattern  60  of a touch panel. The pattern  60  includes sensing electrodes X 1 , X 2  and sensing electrodes Y 1 , Y 2 . The sensing electrodes X 1 , X 2  and the sensing electrodes Y 1 , Y 2  form sensing areas A 1 , A 2 . The sensing electrodes X 1 , X 2  are connected to a common node and to the electrodes X 3 ˜Xn. The sensing electrodes Y 1 , Y 2  are connected to different nodes, independently. The way of calculating the individual self-capacitances sc_xl, sc_x 2  can be found above, and thus omitted herein. 
         [0038]    To sum up, the examples of the present disclosure integrate the sensing method of the single layer self-capacitance and the sensing method of the single layer mutual-capacitance so the drawbacks of the single layer self-capacitance and the single layer mutual-capacitance are compensated. Compared to the single layer self-capacitance sensing, the present disclosure achieves the multi-touch with the least channel. Compared to the mutual-capacitance sensing, the present disclosure have a better accuracy in the condition of the same channel number. 
         [0039]    Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.