Touchscreen device and method of sensing touch
There are provided a touchscreen device and a method of sensing a touch. The touchscreen device includes: a panel unit including a plurality of first electrodes and a plurality of second electrodes; a driving circuit unit simultaneously applying driving signals to M first electrodes among the first electrodes, where M is a natural number equal to or greater than two; a sensing circuit unit detecting capacitance generated in intersections between the first electrodes and the second electrodes so as to output sensing signals; and an operation unit determining whether a touch has occurred, based on the sensing signals.
1. A touchscreen device, comprising:
a panel unit including a plurality of first electrodes and a plurality of second electrodes;
a driving circuit unit simultaneously applying driving signals to M first electrodes among the first electrodes, where M is a natural number equal to or greater than two;
a sensing circuit unit detecting capacitance generated in intersections between the first electrodes and the second electrodes so as to output sensing signals; and
an operation unit determining whether a touch has occurred, based on the sensing signals,
wherein the driving circuit unit generates the driving signals according to an M by N matrix, where N is a natural number equal to or greater than two,
wherein elements in first to (fix(M/2)+1) rows of a first column are 1s, and elements in (fix(M/2)+2) to M th rows of the first column are −1s, and
wherein elements in second to N th columns of first to M th rows are created according to at least one of a pseudo noise (PN) code and a Walsh code, where fix(M/2) is a function that rounds down M/2to the nearest integer by truncating any fractional portion of M/2.
2. The touchscreen device of claim 1 , wherein N=M+1 is met.
3. The touchscreen device of claim 1 , wherein the elements in the second to N th columns of the first row of the matrix are created according to a PN code, and the elements in the second to N th columns of the second to M th rows of the matrix are created by shifting the elements in the second to N th columns of the first row of the matrix by one bit for every row.
4. The touchscreen device of claim 1 , wherein the elements in the second to N th columns of the first to M th rows of the matrix are equal to elements of a Hadamard matrix created according to a Walsh code.
5. The touchscreen device of claim 1 , wherein the driving circuit unit simultaneously applies driving signals generated according to M rows of the matrix to M first electrodes among the first electrodes.
6. The touchscreen device of claim 1 , wherein the driving circuit unit applies driving signals generated according to N columns of the matrix at each of N timings.
7. The touchscreen device of claim 1 , wherein the sensing circuit unit outputs the sensing signals by
Sk=Σ t=1 m Ct,k*Dt
where Sk denotes a sensing signal, Ct,k denotes capacitance generated in intersections between first electrodes Xt and second electrodes Yk, and Dt denotes a driving signal applied to first electrodes Xt.
8. The touchscreen device of claim 1 , wherein the operation unit determines whether a touch has occurred, based on correlation values calculated by performing a correlation operation on the sensing signals acquired during a single period of the driving signals and the matrix.
9. The touchscreen device of claim 8 , wherein the operation unit corrects a cross correlation values existing in the correlation values by multiplying the sensing signals acquired during a single period of the driving signals by a column vector.
10. The touchscreen device of claim 9 , wherein the column vector includes a first column vector and a second column vector of (M+1) rows, wherein all of elements in the first column vector are 1, an element in a first row of the second column vector is −1, and elements in the rest of rows of the second column vector are 1.
11. The touchscreen device of claim 10 , wherein the operation unit calculates a first correction value by multiplying sensing signals obtained during a single period of the driving signals by the first column vector and calculates a second correction value by multiplying the sensing signals obtained during a single period of the driving signals by the second column vector.
12. The touchscreen device of claim 11 , wherein the operation unit corrects the cross correlation values existing in the correlation values according to first and second correction values.
13. The touchscreen device of claim 1 , wherein the driving circuit unit applies positive driving voltage when the elements in the matrix are 1 and generates negative driving voltage when the elements in the matrix are −1.
14. A method of sensing a touch, comprising:
simultaneously applying driving signals to M first electrodes among the first electrodes, where M is a natural number equal to or greater than two;
obtaining sensing signals by detecting capacitance generated in intersections between the first electrodes and second electrodes; and
determining whether a touch has occurred by calculating correlation values between the sensing signals and the driving signals,
wherein the applying of the driving signals includes applying the driving signals generated according to an M by N matrix, where N is a natural number equal to or greater than two,
wherein elements in first to (fix(M/2)+1) rows of a first column are 1s, and elements in (fix(M/2)+2) to M th rows of the first column are −1s, and
wherein elements in second to N th columns of first to M th rows are created according to at least one of a PN code and a Walsh code, where fix(M/2) is a function that rounds down M/2 to the nearest integer by truncating any fractional portion of M/2.
15. The method of claim 14 , wherein N=M+1 is met.
16. The method of claim 14 , wherein the elements in the second to N th columns of the first row of the matrix are created according to a PN code, and the elements in the second to N th columns of the second to M th rows of the matrix are created by shifting the elements in the second to N th columns of the first row of the matrix by one bit for every row.
17. The method of claim 14 , wherein the elements in the second to N th columns of the first to M th rows of the matrix are equal to elements of a Hadamard matrix created according to a Walsh code.
18. The method of claim 14 , wherein the applying of the driving signals includes simultaneously applying driving signals generated according to M rows of the matrix to M first electrodes among the first electrodes.
19. The method of claim 14 , wherein the applying of the driving signals includes applying driving signals generated according to N columns of the matrix at each of N timings.
20. The method of claim 14 , wherein the obtaining of the sensing signals includes obtaining the sensing signals by
Sk=Σ t=1 m Ct,k*Dt
where Sk denotes a sensing signal, Ct,k denotes capacitance generated in intersections between first electrodes Xt and second electrodes Yk, and Dt denotes a driving signal applied to first electrodes Xt.
21. The method of claim 14 , wherein the determining whether a touch has occurred includes determining whether a touch has occurred, based on correlation values calculated by performing a correlation operation on the sensing signals acquired during a single period of the driving signals and the matrix.
22. The method of claim 21 , wherein the determining whether a touch has occurred includes correcting a cross correlation values existing in the correlation values by multiplying the sensing signals acquired during a single period of the driving signals by a column vector.
23. The method of claim 22 , wherein the column vector includes a first column vector and a second column vector of (M+1) rows, wherein all of elements in the first column vector are 1, and an element in a first row of the second column vector is −1 and elements in the rest of rows of the second column vector are 1.
24. The method of claim 23 , wherein the determining whether a touch has occurred includes calculating a first correction value by multiplying sensing signals obtained during a single period of the driving signals by the first column vector and calculating a second correction value by multiplying the sensing signals obtained during a single period of the driving signals by the second column vector.
25. The method of claim 24 , wherein the determining whether a touch has occurred includes correcting the cross correlation values existing in the correlation values according to first and second correction values.
26. The method of claim 14 , wherein the applying of the driving signals includes applying positive driving voltage when the elements in the matrix are 1 and generating negative driving voltage when the elements in the matrix are −1.