Driving method for touch panel and touch control system

A driving method for touch panel includes providing a plurality of driving signals with a first voltage level to a plurality of sensing electrodes of a touch panel; receiving a plurality of sensing signals corresponding to the plurality of driving signals with the first voltage level from the plurality of sensing electrodes of the touch panel; obtaining a second voltage level according to the plurality of sensing signals, the second voltage level being different from the first voltage level; and providing a plurality of driving signals with the second voltage level to the plurality of sensing electrodes of the touch panel.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a driving method for touch panel and a touch control system, and more particularly, to a driving method for touch panel and a touch control system capable of improving detection accuracy and reducing power consumption.

2. Description of the Prior Art

As related techniques keep improving, portable electronic products, such as a mobile phone comprises a touch panel utilized as an input interface. Generally, the touch panel can be a capacitive touch panel or a resistive touch panel. During operation of the capacitive touch panel, capacitance values on the touch panel are changed when a finger or a conductive object approaches or touches the touch panel. When a change of the capacitance value is detected, a touch position of a touch point can be determined, and an operation corresponding to the touch point is further performed. When a touch object on the touch panel is different, the change of capacitance value of the touch panel corresponding to the touch object is different accordingly. However, in the prior art, a voltage level of a driving signal of the touch panel is fixed. When a voltage level of the driving signal of the touch panel is higher, power consumption of the touch panel is increased; and when the voltage level of the driving signal of the touch panel is lower, the touch point of the touch panel may not be correctly detected due to insufficient voltage, so as to reduce detection accuracy of the touch panel.

SUMMARY OF THE INVENTION

The present invention provides a driving method for touch panel, comprising providing a plurality of driving signals with a first voltage level to a plurality of sensing electrodes of a touch panel; receiving a plurality of sensing signals corresponding to the plurality of driving signals with the first voltage level from the plurality of sensing electrodes of the touch panel; obtaining a second voltage level according to the plurality of sensing signals, the second voltage level being different from the first voltage level; and providing a plurality of driving signals with the second voltage level to the plurality of sensing electrodes of the touch panel.

The present invention further provides a touch control system, comprising a touch panel, a driving voltage supplying unit, and a processing unit. The touch panel comprises a plurality of sensing electrodes. The driving voltage supplying unit is for providing a plurality of driving signals with a first voltage level to the plurality of sensing electrodes of the touch panel in a predetermined state. The processing unit is for receiving a plurality of sensing signals corresponding to the plurality of driving signals with the first voltage level from the plurality of sensing electrodes of the touch panel, obtaining a second voltage level according to the plurality of sensing signals, and controlling the driving voltage supplying unit to provide a plurality of driving signals with the second voltage level to the plurality of sensing electrodes of the touch panel. Wherein, the second voltage level is different from the first voltage level.

In contrast to the prior art, the driving method for touch panel and the touch control system of the present invention can selectively provide driving signals with different voltage levels to the touch panel according to characteristics of a touch object. When the touch panel is more sensitive to the touch object, the voltage level of the driving signal can be decreased in order to reduce the power consumption of the touch control system. When the touch panel is less sensitive to the touch object, the voltage level of the driving signal is increased in order to improve the detection accuracy of the touch control system.

DETAILED DESCRIPTION

Please refer toFIG. 1.FIG. 1is a diagram showing a first embodiment of a touch control system of the present invention. As shown inFIG. 1, the touch control system100of the present invention comprises a touch panel110, a driving voltage supplying unit120, and a processing unit130. The touch panel110comprises a plurality of first sensing electrodes S1arranged along a first direction and a plurality of second sensing electrodes S2arranged along a second direction. The driving voltage supplying unit120is for providing a plurality of driving signals TX to the plurality of first sensing electrodes S1of the touch panel110respectively. The processing unit130is for receiving a plurality of sensing signals RX corresponding to the plurality of driving signals TX from the plurality of second sensing electrodes S2of the touch panel110, and controlling a voltage level of the driving signals TX provided by the driving voltage supplying unit120according to the plurality of sensing signals RX.

For example, when the touch control system100is in a predetermined state (such as in an initial state), the driving voltage supplying unit120provides the plurality of driving signals TX with a first voltage level to the first sensing electrodes S1of the touch panel110. The plurality of driving signals TX with the first voltage level can ensure the touch control system100to accurately detect a touch point of any kind of a touch object (such as a finger or a touch pen) on the touch panel110. When the processing unit130receives the plurality of sensing signals RX corresponding to the plurality of driving signals TX from the second sensing electrodes S2of the touch panel110, the processing unit130determines the touch point according to a touch threshold value TH of the touch panel110and the plurality of sensing signals RX. Please refer toFIG. 2, and refer toFIG. 1as well.FIG. 2is a diagram showing a waveform of the sensing signal of the touch point of the touch control system inFIG. 1. As shown inFIG. 2, the sensing signal RX corresponds to a change of a capacitance value of the touch panel110. Since the touch control system100inFIG. 1is a mutual capacitance touch control system, the capacitance value of the touch point is lower than others. When the sensing signal RX is dropped to a value lower than the touch threshold value TH, the processing unit130determines a position corresponding to the dropped sensing signal RX is the touch point.

When a difference between a relative minimum value of the sensing signal RX and the touch threshold value TH is greater than a predetermined value, it means that the touch panel110is more sensitive to the touch object. Therefore, the processing unit130can obtain a second voltage level, which is lower than the first voltage level, according to the difference between the relative minimum value of the sensing signal RX and the touch threshold value TH, and the processing unit130then controls the driving voltage supplying unit120to provide the plurality of driving signals TX with the second voltage level to the first sensing electrodes S1of the touch panel110for performing touch sensing operation. Thereby, power consumption of the touch control system100can be reduced.

When the difference between the relative minimum value of the sensing signal RX and the touch threshold value TH is less than the predetermined value, it means that the touch panel110is less sensitive to the touch object. The touch panel110may not correctly detect the touch point of the touch object. Therefore, the processing unit130can obtain a second voltage level, which is higher than the first voltage level, according to the difference between the relative minimum value of the sensing signal RX and the touch threshold value TH, and the processing unit130then controls the driving voltage supplying unit120to provide the plurality of driving signals TX with the second voltage level to the first sensing electrodes S1of the touch panel110for performing touch sensing operation. Thereby, detection accuracy of the touch control system100can be improved.

On the other hand, the processing unit130can also obtain the second voltage level according to a touched area of the touch point. For example, when a size of the touched area of the touch point is larger, it means that the touch object is possible to be a finger, and the touch panel110is more sensitive to the finger. Therefore, the processing unit130can obtain the second voltage level, which is lower than the first voltage level, according to the touched area of the touch point, and the processing unit130then controls the driving voltage supplying unit120to provide the plurality of driving signals TX with the second voltage level to the first sensing electrodes S1of the touch panel110for performing touch sensing operation. Thereby, the power consumption of the touch control system100can be reduced.

When the size of the touched area of the touch point is smaller, it means that the touch object is possible to be a touch pen, and the touch panel110is less sensitive to the touch pen. Therefore, the processing unit130can obtain the second voltage level, which is higher than the first voltage level, according to the touch area of the touch point, and the processing unit130then controls the driving voltage supplying unit120to provide the plurality of driving signals TX with the second voltage level to the first sensing electrodes S1of the touch panel110for performing touch sensing operation. Thereby, the detection accuracy of the touch control system100can be improved.

In addition, the touch control system100of the present invention can further comprise a memory140for storing a lookup table. The processing unit130can obtain a corresponding second voltage level directly in the lookup table according to the sensing signal RX.

Please refer toFIG. 3.FIG. 3is a diagram showing a second embodiment of the touch control system of the present invention. As shown inFIG. 3, the touch control system200of the present invention comprises a touch panel210, a driving voltage supplying unit220, and a processing unit230. Different from the first embodiment inFIG. 1, the touch control system200inFIG. 3is a self-capacitance touch control system. Therefore, the driving voltage supplying unit220sequentially provides the plurality of driving signals TX to the first sensing electrodes S1and second sensing electrodes S2, and the processing unit230then receives the plurality of sensing signals RX from the first electrodes S1and the second sensing electrodes S2.

Similarly, when the touch control system200is in a predetermined state (such as in an initial state), the driving voltage supplying unit220sequentially provides the plurality of driving signals TX with the first voltage level to the first sensing electrodes S1and the second sensing electrodes S2of the touch panel210. The plurality of driving signals TX with the first voltage level can ensure the touch control system200to accurately detect a touch point of any kind of a touch object (such as a finger or a touch pen) on the touch panel210. When the processing unit230receives the plurality of sensing signals RX corresponding to the plurality of driving signals TX from the first sensing electrodes S1and the second sensing electrodes S2of the touch panel210, the processing unit230determines the touch point according to a touch threshold value TH of the touch panel210and the plurality of sensing signals RX. Please refer toFIG. 4, and refer toFIG. 3as well.FIG. 4is a diagram showing a waveform of a sensing signal of a touch point of the touch control system inFIG. 3. As shown inFIG. 4, the sensing signal RX corresponds to a change of a capacitance value of the touch panel210. Since the touch control system200inFIG. 3is a self-capacitance touch control system, the capacitance value of the touch point is higher than others. When the sensing signal RX is risen to a value higher than the touch threshold value TH, the processing unit230determines a position corresponding to the risen sensing signal RX is the touch point.

When a difference between a relative maximum value of the sensing signal RX and the touch threshold value TH is greater than a predetermined value, it means that the touch panel210is more sensitive to the touch object. Therefore, the processing unit230can obtain a second voltage level, which is lower than the first voltage level, according to the difference between the relative maximum value of the sensing signal RX and the touch threshold value TH, and the processing unit230then controls the driving voltage supplying unit220to provide the plurality of driving signals TX with the second voltage level to the first sensing electrodes S1and the second sensing electrodes S2of the touch panel210for performing touch sensing operation. Thereby, the power consumption of the touch control system200can be reduced.

When the difference between a relative maximum value of the sensing signal RX and the touch threshold value TH is less than the predetermined value, it means that the touch panel210is less sensitive to the touch object. The touch panel210may not correctly detect the touch point of the touch object. Therefore, the processing unit230can obtain the second voltage level, which is higher than the first voltage level, according to the difference between the relative maximum value of the sensing signal RX and the touch threshold value TH, and the processing unit230then controls the driving voltage supplying unit220to provide the plurality of driving signals TX with the second voltage level to the first sensing electrodes S1and the second sensing electrodes S2of the touch panel210for performing touch sensing operation. Thereby, the detection accuracy of the touch control system200can be improved.

Similarly, the processing unit230can also obtain the second voltage level according to a size of touched area of the touch point. The way that of obtaining the second voltage level according to the touched area of the touch point is identical to that in the first embodiment, thus, no illustration is further provided. In addition, the touch control system200of the present invention can also comprise a memory240for storing a lookup table. The processing unit230can obtain a corresponding second voltage level directly in the lookup table according to the sensing signal RX.

In the above embodiment, the sensing signal RX corresponds to the change of the capacitance value of the touch panel. However, the sensing signal RX also can correspond to a change of a voltage value of the touch panel, or any other type of signal.

On the other hand, the processing unit130,230can adjust the touch threshold value TH of the touch panel. For example, as shown inFIG. 2andFIG. 4, the processing unit130,230can obtain a noise range according to the plurality of received sensing signals RX. The processing unit130,230can further adjust the touch threshold value of the touch panel according to a difference between the touch threshold value TH and the noise range. When the difference between the touch threshold value TH and the noise range is greater than a predetermined value, the processing unit130,230can adjust the touch threshold value TH to be slightly closer to the noise range, so that the voltage level of the driving signals TX can be further lowered in order to reduce the power consumption of the touch control system.

Please refer toFIG. 5.FIG. 5is a flowchart500showing a driving method for touch panel of the present invention. The flowchart of the driving method for touch panel of the present invention comprises the following steps:

Step510: Provide a plurality of driving signals with a first voltage level to a plurality of sensing electrodes of a touch panel;

Step520: Receive a plurality of sensing signals corresponding to the plurality of driving signals with the first voltage level from the plurality of sensing electrodes of the touch panel;

Step530: Obtain a second voltage level according to the plurality of sensing signals, the second voltage level being different from the first voltage level; and

Step540: Provide a plurality of driving signals with the second voltage level to the plurality of sensing electrodes of the touch panel.

Please refer toFIG. 6.FIG. 6is a flowchart600showing another driving method for touch panel of the present invention. The flowchart of another driving method for touch panel of the present invention comprises the following steps:

Step610: Provide a plurality of driving signals with a first voltage level to a plurality of sensing electrodes of a touch panel;

Step620: Receive a plurality of sensing signals corresponding to the plurality of driving signals with the first voltage level from the plurality of sensing electrodes of the touch panel;

Step630: Adjust a touch threshold value of the touch panel according to a noise range of the plurality of sensing signals;

Step640: Obtain a second voltage level according to the plurality of sensing signals and the adjusted touch threshold value of the touch panel, the second voltage level being different from the first voltage level; and

Step650: Provide a plurality of driving signals with the second voltage level to the sensing electrodes of the touch panel.

In contrast to the prior art, the driving method for touch panel and the touch control system of the present invention can selectively provide driving signals with different voltage levels to the touch panel according to characteristics of a touch object. When the touch panel is more sensitive to the touch object, the voltage level of the driving signal can be decreased in order to reduce the power consumption of the touch control system. When the touch panel is less sensitive to the touch object, the voltage level of the driving signal is increased in order to improve the detection accuracy of the touch control system.