Touch panel controller, touch sensor system, and electronic device

1. A touch panel controller comprising:

a first signal value map generation unit that outputs a first signal value map which indicates a distribution of signal values in a touch panel in which plural signal values are formed in a matrix at intersections of m sense lines and n drive lines (both of m and n are integers that are equal to or greater than three); and

a touch recognition unit that detects an input on the touch panel based on the signal values,

wherein the touch panel controller further includes a second signal value map generation unit that

configures an area that is a broader range than a range where changes in the signal values due to an input operation on the touch panel occur on the first signal value map, and

provides a second signal value map which is generated by performing correction calculation which cancels changes in the signal values due to external factors which are different from the input operation on the touch panel in the area to the touch recognition unit,

the area is expressed as a rectangle,

a direction in which the sense lines are arranged is set as an up-down direction,

a direction in which the drive lines are arranged is set as a left-right direction,

the second signal value map generation unit performs the correction calculation by using

an average value Cm of the signal values in the area,

an up-down inclination α that indicates a change amount of the signal value in the up-down direction in the area, and

a left-right inclination β that indicates a change amount of the signal value in the left-right direction in the area.

2. The touch panel controller according to claim 1 ,

wherein the first signal value map is expressed by a matrix C with m rows and n columns,

the second signal value map generation unit includes an area configuration unit, an average value calculation unit, an inclination calculation unit, and a correction calculation unit,

the area configuration unit configures the area by a rectangle that has four points (X−L, Y−D), (X−L, Y+U), (X+R, Y−D), and (X+R, Y+U) as vertices (each of L, R, U, and D is an integer that is equal to or greater than one) with respect to a point (X, Y) on the first signal value map which corresponds to a component C[X][Y] in the Xth row and Yth column of the matrix C (1<X<m and 1<Y<n),

the average value calculation unit calculates (i) an average value Cm of all components, (ii) an average value Cu of components of Ku rows from the highest row in a row direction, (iii) an average value Cd of components of Kd rows from the lowest row in the row direction, (iv) an average value CI of components of KI columns from the leftmost column in a column direction, and (v) an average value Cr of components of Kr columns from the rightmost column in the column direction of a matrix C 1 with (L+R+1) rows and (D+U+1) columns that expresses a distribution of the signal values in the area (each of Ku, Kd, KI, and Kr is an integer that is equal to or greater than one),

the inclination calculation unit calculates an up-down inclination α and a left-right inclination β by

α=( Cu−Cd )/{( U −( Ku− 1))+( D −( Kd− 1))}and

β=( Cl−Cr )/{( L −( Kl −1))+( R −( Kr −1))}, and

the correction calculation unit calculates a matrix C 2 that expresses the second signal value map by

C 2 [i][j]=C 1 [i][j]−Cm+j×α+i×β

(where −L≦i≦R and −U≦j≦D).

3. The touch panel controller according to claim 2 ,

wherein the second signal value map generation unit further includes a difference calculation unit, and

the difference calculation unit provides a difference matrix that is generated by applying difference calculation to the matrix C which expresses the first signal value map to the area configuration unit.

4. A touch sensor system comprising:

the touch panel controller according to claim 1 ; and

a touch panel in which plural signal values are distributed in a matrix.

5. An electronic device comprising the touch sensor system according to claim 4 .