Touch sensing system and driving method thereof
View Patent ↗A touch sensing system comprises: a touch sensing unit which includes regions having predetermined coordinates; and a baseline updating unit for updating a baseline by reflecting sensing signals outputted from the touch sensing unit. The baseline updating unit includes a comparator for calculating difference values between the sensing signal of an n-th frame and the baseline of an n−1-th frame for each region, and for comparing the difference values with predetermined reference values. The touch sensing system further comprises an arithmetic unit for setting the baseline of the n−1-th frame as the baseline of the n-th frame for a region in which the difference values are larger than the reference values and for the region adjacent to it, and for updating the baseline of the n-th frame by a predetermined arithmetic for a remaining region.
1. A touch sensing system, comprising:
a touch sensing unit including a number of regions having a predetermined number of coordinates; and
a baseline updating unit for updating baselines by reflecting sensing signals outputted from the touch sensing unit;
wherein the baseline updating unit includes:
a comparator for calculating difference values between sensing signals of an n-th frame and baselines of an n−1-th frame for each of the regions, and for comparing the difference values with predetermined reference values; and
an arithmetic unit for setting the baselines of the n−1-th frame as baselines of the n-th frame for a region in which the difference values are larger than the reference values and a region adjacent to it, and for updating the baselines of the n-th frame by a predetermined arithmetic for a remaining region.
2. The touch sensing system according to claim 1 , wherein the arithmetic unit updates the baselines by Equation B(n)=I(n)×A+B(n−1)×(1−A), where B(n) is the baseline of n-th frame, I(n) is the sensing signal of the n-th frame, B(n−1) is the baseline of the n−1-th frame, and A is an updating coefficient.
3. The touch sensing system according to claim 1 , wherein the touch sensing unit comprises a number of sensor electrodes, and is operated in a capacitance type manner.
4. The touch sensing system according to claim 1 , further comprising a filtering unit for calculating an output signal of the n-th frame from the sensing signals of the n-th frame outputted from the touch sensing unit using Equation F(n)=I(n) W+F(n−1) ( 1 -W), where F(n) is the output signal of the n-th frame, I(n) is the sensing signal of the n-th frame, F(n−1) is an output signal of the n−1-th frame, and W is a filtering coefficient, said filtering unit outputting the calculated output signal to an output stage.
5. The touch sensing system according to claim 4 , wherein the filtering unit calculates the filtering coefficient for a region in which the difference values are larger than the reference values by Equation
W
=
I
(
n
)
-
F
(
n
-
1
)
R
,
where R is a scale factor.
6. The touch sensing system according to claim 5 , wherein the filtering coefficient W is set to a value in a range of 0≦W≦1.
7. The touch sensing system according to claim 4 , wherein the filtering unit calculates the filtering coefficient for a region adjacent to a region in which the difference values are larger than the reference values by Equation
W
=
I
(
n
)
-
F
(
n
-
1
)
cR
,
where c is an additional coefficient.
8. The touch sensing system according to claim 7 , wherein the filtering coefficient W is set to a value in a range of 0≦W≦1.
9. The touch sensing system according to claim 7 , wherein the additional coefficient is set to a value in a range of 1≦c.
10. A driving method for a touch sensing system, comprising the steps of:
(a) calculating difference values between sensing signals of an n-th frame and baselines of an n−1-th frame for each of regions of a touch sensing unit, and comparing the difference values with predetermined reference values; and
(b) setting the baseline of the n−1-th frame as a baseline of the n-th frame for a region in which the difference values are larger than the predetermined reference values and for a region adjacent to the region, and updating the baseline of the n-th frame by a predetermined arithmetic for a remaining region.
11. The driving method for the touch sensing system according to claim 10 , wherein step (b) updates the baselines in accordance with B(n)=I(n)×A+B(n−1)×(1−A), where B(n) is the baseline of the n-th frame, I(n) is the sensing signal of the n-th frame, B(n−1) is the baseline of n−1-th frame, and A is an updating coefficient.
12. The driving method for the touch sensing system according to claim 10 , wherein the touch sensing unit includes a number of sensor electrodes, and is operated in a capacitance type manner.
13. The driving method for the touch sensing system according to claim 10 , further comprising step (c) of calculating an output signal of the n-th frame from the sensing signal of the n-th frame outputted from the touch sensing unit using Equation F(n)=I(n)×W+F(n−1)×(1−W), where F(n) is the output signal of the n-th frame, I(n) is the sensing signal of the n-th frame, F(n−1) is an output signal of the n−1-th frame, and W is a filtering coefficient, and outputting the calculated output signal to an output stage.
14. The driving method for the touch sensing system according to claim 13 , wherein step (c) further comprises calculating the filtering coefficient for the region in which the difference values are larger than the reference values by Equation
W
=
I
(
n
)
-
F
(
n
-
1
)
R
,
where R is a scale factor.
15. The driving method for the touch sensing system according to claim 14 , wherein the filtering coefficient is set to a value in a range of 0≦W≦1.
16. The driving method for the touch sensing system according to claim 13 , wherein step (c) further comprises calculating the filtering coefficient for the region adjacent to the region in which the difference values are larger than the reference values by Equation
W
=
I
(
n
)
-
F
(
n
-
1
)
cR
,
where c is an additional coefficient.
17. The driving method for the touch sensing system according to claim 16 , wherein the filtering coefficient is set to a value in a range of 0≦W≦1.
18. The driving method for the touch sensing system according to claim 16 , wherein the additional coefficient is set to a value in a range of 1≦c.