Abstract:
A touch panel scanning method includes transmitting a first driving signal into a first signal line of a side of a touch panel in a power saving mode; receiving a first sensing signal from a second signal line of the side of the touch panel; and determining if the first sensing signal satisfying a predetermined rule so as to control the touch panel to perform a corresponding operation; wherein the first sensing signal relates to a mutual capacitance between the first signal line and the second signal line.

Description:
BACKGROUND OF THE DISCLOSURE 
       [0001]    1. Field of the Disclosure 
         [0002]    The present application relates to a scanning method for touch panel, and more particularly, a scanning method in a power-saving mode for touch panel. 
         [0003]    2. Technical Background 
         [0004]    Touch panels can reduce necessary hardware and space for input/output (I/O) devices, and allow users to interact with electronic devices more intuitively and conveniently, therefore touch panels have been widely used in electronic devices such as smart phones, laptop computers and tablet computers. For users&#39; expectation for longer standby time, a portable devices such as a smart phone or a tablet computer is expected to have good power saving performance. A touch panel can be set into an operational mode or a power-saving mode according to the prior art so as to decrease power consumption. In the operational mode, a touch panel should be able to detect accurate touch control and display with high luminance; and in a power-saving mode (e.g. a sleep mode) triggered by staying idle for a predetermined idle period or a manual control, the touch panel stands by with low power consumption without entering the operational mode until a touch event occurs, that is, the touch panel receives a touch control. 
         [0005]    To keep a touch panel able to detect the occurrence of touch event, a touch panel keeps executing scanning and reading rather than being completely turned off in a power-saving mode.  FIG. 1  illustrates driving signal lines  1101  to  110   m  and sensing signal lines  1201  to  120   n  of a touch panel  100  in a power-saving mode according to the prior art. In the power-saving mode, driving signals D 1  to Dm are sent through the driving signal lines  1101  to  110   m  respectively from top to bottom sequentially to perform scanning, and a system receives sensing signals S 1  to Sn through the sensing signal lines  1201  to  120   n  respectively to perform reading. For example, when a touch event occurs at the intersection of the driving signal line  1105  and the sensing signal line  1029  in the power-saving mode, after the driving signal D 5  is sent, the voltage value of the sensing signal S 9  is correspondingly changed due to the change of the inductive capacitance caused by the touch event at the intersection, the system is able to detect the occurrence of the touch event by detecting the change of the sensing signal S 9  with considering the time of sending the driving signal D 5  and then wakes up the touch panel  100  accordingly to set the touch panel  100  in the operational mode. The location of a touch event can be accurately located in the power-saving mode by means of the aforementioned prior art, but the effect of power saving is not ideal because the scanning needs to be performed for a large number of sensing signals to be received for checking all intersections. Taking the touch panel  100  in  FIG. 1  for example, when the touch panel  100  is in the power-saving mode without being awakened, the driving signals D 1  to Dm should be sent sequentially in a frame period, and the sensing signals S 1  to Sn should be received in the frame period, therefore (m×n) times of reading of scans are performed to check if any touch event occurs around the (m×n) intersections. Since all the (m×n) intersections are checked in each frame period, sending and reading so many driving signals and sensing signals in each frame period lead the power consumption in the power-saving mode not to be reduced well. 
       SUMMARY OF THE DISCLOSURE 
       [0006]    An embodiment of the present application discloses a touch panel scanning method, comprising sending a first driving signal via a first signal line of a first side of a touch panel when the touch panel is in a power-saving mode; receiving a first sensing signal via a second signal line of the first side of the touch panel when sending the first driving signal; and controlling the touch panel to execute an corresponding action according to whether the first sensing signal complies with a predetermined rule; wherein the first sensing signal is related to an inductive capacitor between the first signal line and the second signal line. 
         [0007]    Another embodiment of the present application discloses a touch panel scanning method, comprising sending a set of driving signals via a first set of signal lines of a first side of a touch panel when the touch panel is in a power-saving mode; receiving a set of sensing signals via a second set of signal lines of the first side of the touch panel when sending the set of driving signals; and controlling the touch panel to execute a corresponding action according to whether the set of sensing signals complies with a predetermined rule; wherein the set of sensing signals is related to a set of inductive capacitors between the first set of signal lines and the second set of signal lines. 
         [0008]    These and other objectives of the present application 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 
         [0009]      FIG. 1  illustrates driving signal lines and sensing signal lines of a touch panel in a power-saving mode according to the prior art. 
           [0010]      FIG. 2  illustrates a touch panel according to an embodiment of the present disclosure. 
           [0011]      FIG. 3  illustrates an equivalent RC circuit of the touch panel of  FIG. 2  in a power-saving mode without occurring any touch event according to an embodiment of the present disclosure. 
           [0012]      FIG. 4  illustrates an equivalent RC circuit of the touch panel of  FIG. 2  in a power-saving mode when occurring a touch event according to an embodiment of the present disclosure. 
           [0013]      FIG. 5  illustrates the sending of driving signals and the receiving of sensing signals of a touch panel according to the first embodiment of the present disclosure. 
           [0014]      FIG. 6  illustrates a flow chart of a scanning method according to the first embodiment of the present disclosure. 
           [0015]      FIG. 7  illustrates the sending of driving signals and the receiving of sensing signals on a touch panel according to the second embodiment of the present disclosure. 
           [0016]      FIG. 8  illustrates a flow chart of a scanning method according to the second embodiment of the present disclosure. 
           [0017]      FIG. 9  illustrates the sending of driving signals and the receiving of sensing signals of a touch panel according to the third embodiment of the present disclosure. 
           [0018]      FIG. 10  illustrates a flow chart of a scanning method according to the second embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]      FIG. 2  illustrates a touch panel  200  according to an embodiment of the present disclosure. The touch panel  200  includes m signal lines  2101  to  210   m , each having their own signal line capacitance. For example, the signal line  201   x  has a signal line capacitance C x  and a signal line resistance R x , the signal line  201   x+ 1 has a signal line capacitance C x+1,  a signal line mutual capacitance C m  exists between the signal lines  201   x  and  201   x+ 1, and a capacitance C d-s  generated between two adjacent signal lines exists between the signal line  201   x  and a signal line  220   y  of two different directions. 
         [0020]      FIG. 3  illustrates an equivalent RC circuit of the touch panel  200  in a power-saving mode without occurring any touch event according to an embodiment of the present disclosure.  FIG. 4  illustrates an equivalent RC circuit of the touch panel  200  in a power-saving mode when occurring a touch event according to an embodiment of the present disclosure. According to  FIG. 3 , when the touch panel  200  is in the power-saving mode without occurring any touch events, a driving voltage source Dr sends a driving signal with a driving voltage value V drv ′ a corresponding sensing signal is received through the signal line  201   x+ 1, and the sensing signal has an untouched voltage value V no-touch  which may be calculated with the following equation (a). 
         [0000]        V   no-touch   =V   drv   ′×C   m /( C   m   +C   x+1   +C   d-s )  (a)
 
         [0021]    According to  FIG. 4 , when a touch event occurs on the touch panel  200  in the power-saving mode, taking a finger touching the touch panel  200  for example, the finger may have a finger parasitic capacitance C finger  and the sensing signal on at the signal line  210   x+ 1 may have a touched voltage value V touch  which may be calculated with the following equation (b). 
         [0000]        V   touch   =V   drv ′×( C   m   −ΔC   m )/( C   x+1   +C   m   −ΔC   m   +C   finger   +C   d-s )  (b)
 
         [0022]    The variation ΔC m  is a variation of the signal line mutual capacitance C m  after the touch event occurs. By comparing  FIGS. 3 and 4 , a variation of the mutual capacitance between signal lines is generated after a touch event such as a finger or a stylus touching the touch panel  200 . According to the equation (b), when the variation of a mutual capacitance is greater than a predetermined value, and a finger parasitic capacitance on a finger makes a sensing signal have the touched voltage value V touch , a touch event is accordingly determined. 
         [0023]    According to mentioned equations (a) and (b), when a driving signal is sent through a signal line, if a touch event triggered by a finger or a stylus, the voltage value of a sensing signal sensed from adjacent signal lines may vary accordingly so that a touch event on a touch panel in a power-saving mode can be detected. Different from the touch panel  100  of the prior art shown in  FIG. 1 , for the touch panel  200  shown in  FIG. 2 , although the sensing signals are also received after the driving signals are sent so as to determine if any touch event occurs in the power-saving mode, the sending of the driving signal and the receiving of the sensing signal are in the same dimension (e.g. in the horizontal direction, sending and receiving of signals at the left side) on the touch panel  200  instead of being in two different dimensions such as sending the driving signals at the left side (in the horizontal direction) and receiving the sensing signals at the bottom side (in the vertical direction). The horizontal and the vertical directions are allowed to be defined according to application. 
       The First Embodiment 
       [0024]      FIG. 5  illustrates the sending of driving signals and the receiving of sensing signals of a touch panel  500  according to the first embodiment of the present disclosure. According to  FIG. 5 , the driving signals may be sent, and the sensing signals may be received both at the left side (or the right side) of the touch panel  500  through the six signal lines  5101  to  5106 . In the touch panel  500 , the sending of the driving signals and the receiving of the sensing signals are both at (but not limited to) the left side. The sending of the driving signals and the receiving of the sensing signals should be at the same side according to the first embodiment of the present disclosure.  FIG. 6  illustrates a flow chart of a scanning method according to the first embodiment of the present disclosure. The scanning method includes the following steps: 
         [0025]    Step  601 : When the touch panel  500  is in the power-saving mode, send the driving signal D 51  through the signal line  5101  of the touch panel  500 ; 
         [0026]    Step  602 : When sending the driving signal D 51 , receive the sensing signal S 51  through the signal line  5102  of the touch panel  500 ; 
         [0027]    Step  603 : Determine whether a touch event occurs according to the sensing signal S 51 ? If yes, enter step  690 ; if no, enter step  604 ; 
         [0028]    Step  604 : Send the driving signal D 52  through the signal line  5103  of the touch panel  500 ; 
         [0029]    Step  605 : When sending the driving signal D 52 , receive the sensing S 52  through the signal line  5104 ; 
         [0030]    Step  606 : Determine whether a touch event occurs according to sensing signal S 52 ? If yes, enter step  690 ; if no, enter step  607 ; 
         [0031]    Step  607 : Send the driving signal D 53  through the signal line  5105  of the touch panel  500 ; 
         [0032]    Step  608 : When sending the driving signal D 53 , receive the sensing S 53  through the signal line  5106 ; 
         [0033]    Step  609 : Determine whether a touch event occurs according to sensing signal S 53 ? If yes, enter step  690 ; if no, enter step  695 ; 
         [0034]    Step  690 : A touch event is detected; control the touch panel  500  to quit the power-saving mode for entering an operational mode; 
         [0035]    Step  695 : No touch event is detected in the frame period, keep the touch panel  500  in the power-saving mode. 
         [0036]    According to the first embodiment of the present disclosure, the determination of the occurrence of the touch event in steps  603 ,  606  and  609  is performed according to the method explained in  FIGS. 2 to 4  described above, that is to detect whether a touch event occurs around the signal lines through which the driving signals are sent according to the variation of the sensing signals. The touch panel  500  shown in  FIG. 5  has only six signal lines, but the number of signal lines is not limited to six according to the embodiment of the present disclosure. In the scanning method disclosed by the first embodiment, the driving signals are sent through the odd number of signal lines sequentially from top to bottom, and the sensing signals are received through the even number of the signal lines. Hence, when the number of the signal line of the horizontal direction is m, the number of times of the receiving of the sensing signal is only m/2. For example, there are six signal lines in the touch panel  500  of  FIG. 5 , so it is necessary to receive the sensing signals three times. Therefore, it requires only m/2 times of reading of scans to detect whether a touch event occurs in one frame period. The signal lines of another direction (e.g. the vertical direction) is unnecessary to be considered. Comparing with the method related to the touch panel  100  of the prior art shown in  FIG. 1 , the number of the driving signal lines of the touch panel  100  of the horizontal direction is also m, but the n sensing signal lines of the vertical direction should be considered in order to perform m×n times of reading of scans for detecting touch events. Hence, the number of times of the reading of scans may be reduced to be merely (m/2)/(m×n) times, that is (½n) times, of the prior art by using the method according to the first embodiment of the present disclosure. 
       The Second Embodiment 
       [0037]      FIG. 7  illustrates the sending of driving signals and the receiving of sensing signals in a touch panel  700  according to the second embodiment of the present disclosure. According to  FIG. 7 , the driving signals may be sent, and the sensing signals may be received at the left side (or the right side) of the touch panel  700  through the six signal lines  7101  to  7106 . In the touch panel  700 , the sending of the driving signals and the receiving of the sensing signals are both at (but not limited to) the left side. The sending of the driving signals and the receiving of the sensing signals should be at the same side according to the second embodiment of the present disclosure. 
         [0038]      FIG. 8  illustrates a flow chart of a scanning method according to the second embodiment of the present disclosure. The scanning method includes the following steps: 
         [0039]    Step  801 : When the touch panel  700  is in the power-saving mode, send the driving signal D 71  through the signal line  7102  of the touch panel  700 ; 
         [0040]    Step  802 : When sending the driving signal D 71 , receive the sensing signal S 711  through the signal line  7101  and receive the sensing signal S 712  through the signal line  7103 ; 
         [0041]    Step  803 : Determine whether a touch event occurs according to the sensing signals S 711  and S 712 ? If yes, enter step  890 ; if no, enter step  804 ; 
         [0042]    Step  804 : Send the driving signal D 72  through the signal line  7105  of the touch panel  700 ; 
         [0043]    Step  805 : When sending the driving signal D 72 , receive the sensing signal S 721  through the signal line  7104  and receive the sensing signal S 722  through the signal line  7106 ; 
         [0044]    Step  806 : Determine whether a touch event occurs according to the sensing signals S 721  and S 722 ? If yes, enter step  890 ; if no, enter step  895 ; 
         [0045]    Step  890 : A touch event is detected; control the touch panel  700  to quit the power-saving mode for entering an operational mode; 
         [0046]    Step  895 : No touch event is detected in the frame period, keep the touch panel  700  in the power-saving mode. 
         [0047]    According to the embodiment of the present disclosure, the determination of the occurrence of the touch event in steps  803  and  806  is performed according to the method described in  FIGS. 2 to 4  above, that is to detect whether a touch event occurs around the signal lines through which the driving signals are sent according to the variation of the sensing signals. The touch panel  700  shown in  FIG. 7  has only six signal lines, but the number of signal lines is not limited to six according to the embodiment of the present disclosure. In the scanning method disclosed by the second embodiment of the present disclosure, the signal lines are grouped into a plurality of groups each having three signal lines from the top to the bottom, a driving signal is sent through the second signal line of the three signal lines of a group, then two sensing signals are received through the first and the third signal lines of the group so as to determine whether a touch event occurs by detecting if the sensing signals change corresponding to the change of an inductive capacitance caused by a touch event. When a touch event occurs, the inductive capacitance between the first and the second signal lines and the inductive capacitance between the second and the third signal lines changes accordingly so as to make the sensing signals change, and the touch event can be detected. Hence, when there are m signal lines in the horizontal direction, the number of times of receiving the sensing signals would be only (m/3). Taking the touch panel  700  having six signal lines for example, the number of times of receiving the sensing signals is 6/3, that is two. This means that only (m/3) times of reading of scans is required to determine whether a touch event occurs in one frame period in the power-saving mode. Moreover, the signal lines of another direction such as the vertical direction are not necessary to be concerned. However, when using the method of the touch panel  100  of the prior art, (m×n) times of reading of scans are required. Hence, comparing with method of the prior art described in  FIG. 1 , the required number of times of reading of scans may be reduced to (m/3)/(m×n) times, that is (⅓n) times, by using the method according to the second embodiment of the present disclosure. 
         [0048]    According to another embodiment, it is allowed to group the signal lines into multiple groups each having multiple signal lines, the driving signals are sent through each of the signal lines of a group in a specific sequence, and the other signal lines of the group (except for the signal line used to send the driving signal) are used to receive the sensing signals corresponding to the inductive capacitances and the change of the inductive capacitances among the mentioned signal line for sending the driving signal and the other signal lines for receiving the sensing signals. Please refer to the following third embodiment. 
       The Third Embodiment 
       [0049]      FIG. 9  illustrates the sending of driving signals and the receiving of sensing signals in a touch panel  900  according to the third embodiment of the present disclosure. According to  FIG. 9 , the driving signals may be sent, and the sensing signals may be received at the left side (or the right side) of the touch panel  900  through the six signal lines  9101  to  9106 . In the touch panel  900 , the sending of the driving signals and the receiving of the sensing signals are both at (but not limited to) the left side. The sending of the driving signals and the receiving of the sensing signals should be at the same side according to the third embodiment of the present disclosure. 
         [0050]      FIG. 10  illustrates a flow chart of a scanning method according to the third embodiment of the present disclosure. The scanning method includes the following steps: 
         [0051]    Step  1001 : When the touch panel  900  is in the power-saving mode, send the driving signals D 911  and D 912  through the signal lines  9101  and  9103  of the touch panel  900 ; 
         [0052]    Step  1002 : When sending the driving signals D 911  and D 912 , receive the sensing signal S 91  through the signal line  9102 ; 
         [0053]    Step  1003 : Determine whether a touch event occurs according to the sensing signals S 91 ? If yes, enter step  1090 ; if no, enter step  1004 ; 
         [0054]    Step  1004 : Send the driving signals D 921  and D 922  through the signal lines  9102  and  9104  of the touch panel  900 ; 
         [0055]    Step  1005 : When sending the driving signals D 921  and D 922 , receive the sensing signal S 92  through the signal line  9103 ; 
         [0056]    Step  1006 : Determine whether a touch event occurs according to the sensing signals S 92 ? If yes, enter step  1090 ; if no, enter step  1007 ; 
         [0057]    Step  1007 : Send the driving signals D 931  and D 932  through the signal lines  9103  and  9105  of the touch panel  900 ; 
         [0058]    Step  1008 : When sending the driving signals D 931  and D 932 , receive the sensing signal S 93  through the signal line  9104 ; 
         [0059]    Step  1009 : Determine whether a touch event occurs according to the sensing signals S 93 ? If yes, enter step  1090 ; if no, enter step  1010 ; 
         [0060]    Step  1010 : Send the driving signals D 941  and D 942  through the signal lines  9104  and  9106  of the touch panel  900 ; 
         [0061]    Step  1011 : When sending the driving signals D 941  and D 942 , receive the sensing signal S 94  through the signal line  9105 ; 
         [0062]    Step  1012 : Determine whether a touch event occurs according to the sensing signals S 94 ? If yes, enter step  1090 ; if no, enter step  1095 ; 
         [0063]    Step  1090 : A touch event is detected; control the touch panel  900  to quit the power-saving mode for entering an operational mode; 
         [0064]    Step  1095 : No touch event is detected in the frame period, keep the touch panel  900  in the power-saving mode. 
         [0065]    According to the embodiment of the present disclosure, the determination of the occurrence of the touch event in steps  1003 ,  1006 ,  1009  and  1012  is performed according to the method described in  FIGS. 2 to 4  above, that is to detect whether a touch event occurs around the signal lines through which the driving signals are sent according to the variation of the sensing signals. The touch panel  900  shown in  FIG. 9  has only six signal lines, but the number of signal lines is not limited to six according to the embodiment of the present disclosure. In the scanning method disclosed by the third embodiment of the present disclosure, the signal lines are grouped into a plurality of groups each having three signal lines from the top to the bottom, two driving signals are sent through the first and third signal lines of the three signal lines of a group, and a sensing signal is received through the second signal line of the group so as to determine whether a touch event occurs by detecting if the sensing signal changes corresponding to the change of an inductive capacitance caused by a touch event. According to  FIG. 9 , the first two signal lines (e.g. the signal lines  9102  and  9103 ) of the three signal lines (e.g. the signal lines  9102 ,  9103  and  9104 ) of a group are the last two signal lines (e.g. the signal lines  9102  and  9103 ) of the three signal lines (e.g. the signal lines  9101 ,  9102  and  9103 ) of the previous group. Hence, when there are m signal lines in the horizontal direction, the number of times of receiving the sensing signals would be only (m−2). Taking the touch panel  900  having six signal lines for example, the number of times of receiving the sensing signals is (6−2), that is four. This means that merely (m−2) times of reading of scans is required to determine whether a touch event occurs in one frame period in the power-saving mode without considering the signal lines of another direction (e.g. the vertical direction). When m is a larger number such as 200 or a number greater than 1000, (m−2) may be close to m, so the required number of reading of scans may be seen as m. Comparing with the method disclosed in  FIG. 1  which requires (m×n) times of reading of scans, the required number of times of reading of scans may be reduced to (m)/(m×n) times, that is (1/n) times, by using the method disclosed by the third embodiment of the present disclosure. 
       CONCLUSION 
       [0066]    Taking a touch panel with m signal lines in the horizontal direction, n signal lines in the vertical direction and (m×n) intersections for example, when using the scanning method in the power-saving mode according to an embodiment of the present disclosure, a touch event may be merely located at the signal lines through which the driving signals are sent rather than being located at an accurate intersection of the (m×n) intersections, because the (m×n) intersections are not checked one by one sequentially in the method disclosed by the present disclosure. This is the trade-off of the method disclosed by the present disclosure. However, when in the power-saving mode, the detection of a touch event is only for the touch panel to be awakened to quit the power-saving mode and enter the operational mode when a touch event occurs, so it is unnecessary to locate a touch event accurately. 
         [0067]    In summary, when a touch panel has m signal lines in the horizontal direction and n signal lines in the vertical direction, by using the scanning method for the touch panel in the power-saving mode disclosed by the present disclosure, the number of times of reading of scans (i.e. the times of receiving the sensing signals) can be reduced to (½n), (⅓n) or (1/n) times if comparing with the required number of times of reading of scans according to the method of the prior art. For example, when n is 200, the required number of times of reading of scans may be 1/400, 1/600 or 1/200 times the required number of times of reading of scans in the prior art. Because only one side instead of two sides of signal lines are used to send or receive signals in the power-saving mode, power consumption may be therefore reduced around 50%, and the required time and the power consumption for scanning and sending/receiving signals may be further greatly reduced for the required number of times of reading of scans is greatly decreased (e.g. merely 1/600 times of the prior art). Hence, the scanning time and the power consumption for detecting whether any touch event occurs in the power-saving mode may be reduced considerably by using the scanning method for the touch panel in the power-saving mode according to the embodiment of the present disclosure. 
         [0068]    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 disclosure. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.