Touch sensing system and method for driving the same

[0069]FIG. 14 is a waveform diagram showing driving signals according to the invention.

[0070]As shown in FIGS. 13 and 14, the touch screen TSP may be divided into a plurality of blocks B1 to B3. Each of the blocks B1 to B3 includes at least two Tx lines to which the driving signal is applied. FIG. 13 shows that the touch screen TSP is divided into the three blocks B1 to B3. The number of blocks divided from the touch screen TSP is not limited to three.

[0071]Because the first block B1 of the touch screen TSP is positioned closest to the touch sensing circuit 30, an RC delay of the first block B1 is less than RC delays of the second and third blocks B2 and B3. On the other hand, because the third block B3 of the touch screen TSP is positioned farthest away from the touch sensing circuit 30, the RC delay of the third block B3 is greater than the RC delays of the first and second blocks B1 and B2. The RC delay of the second block B2 is greater than the RC delay of the first block B1 and...

[0080]As shown in FIG. 19, a resistor R and a capacitor C may be connected between the output terminal of the driving signal generator and a ground level voltage source GND. The resistor R and the capacitor C remove a noise such as a ripple and stabilize an output voltage. An adder 61 and a waveform generator 62 may be connected to the output terminal of the driving signal generator. The waveform generator 62 may generate a waveform such as a sine wave, a triangle wave, and a sawtooth wave. The adder 61 adds an output of the waveform generator 62 to the voltage of the multi-step waveform applied by the driving signal generator. When the output of the waveform generator 62 is the sine wave, an output, i.e., the driving signal of the adder 61 may be generated as shown in FIG. 20. FIG. 20 is a waveform diagram showing an output waveform of the driving signal generator according to the invention. As described above, at least a portion of the driving signal according to the embodiment of...

[0082]FIG. 21 is a waveform diagram showing driving signals according to the invention. FIG. 22 is a waveform diagram showing changes in a charge amount when a width of the driving signal shown in FIG. 21 changes.

[0083]As shown in FIGS. 21 and 22, the touch screen TSP may be divided into a plurality of blocks B1 to B3 in the same way as FIG. 13. Each of the blocks B1 to B3 includes two or more Tx lines to which the driving signal is applied.

[0084]Because the touch sensing circuit 30 is closer to the first block B1 than to the other blocks B2 and B3, RC delay of the first block B1 is less than RC delays of the other blocks B2 and B3. On the other hand, because the third block B3 is farthest from the touch sensing circuit 30, the third block B3 has the largest RC delay. Thus, the RC delay of the second block B2 is greater than the RC delay of the first block B1 and is less than the RC delay of the third block B3. Such a difference between the RC delays of the blocks results in a diffe...