Touch panel controller and electronic device
A touch panel controller of the invention is provided with a driving unit which drives drive lines and causes a linear sum signal based on charges accumulated in respective electrostatic capacitances to be output from a sense line, and a correction processing unit which corrects influence on a change in the electrostatic capacitances by a parasitic capacitance which exists in the sense line. Thereby, it is possible to provide the touch panel controller and an electronic device capable of performing estimation of an electrostatic capacitance value more correctly by correcting the influence of the parasitic capacitance which exists in the sense line.
1. A touch panel controller which obtains, with a change in K electrostatic capacitances which are respectively formed between a sense line and K drive lines (K is an integer of 2 or more) when an object to be detected touches a touch panel having the electrostatic capacitances, a touched position of the object to be detected: comprising
a driving unit which drives the drive lines and causes a linear sum signal based on charges accumulated in the respective electrostatic capacitances to be output from the sense line; and
a correction unit which corrects influence on the linear sum signal by a parasitic capacitance which exists in the sense line,
the driving unit driving the K drive lines in parallel by K code sequences having a sequence length of N (N is an integer), which correspond to the K drive lines, and causing N linear sum signals to be output from the sense line,
the touch panel controller further comprising:
an inner product computation unit which estimates values of the K electrostatic capacitances by computation of inner products of the N linear sum signals output from the sense line and the K code sequences having the sequence length of N,
the correction unit adding a value, which is obtained by adding weight to a signal based on a value obtained by adding the N linear sum signals, to the values of the K electrostatic capacitances estimated by the inner product computation unit to thereby correct the values of the electrostatic capacitances.
2. The touch panel controller according to claim 1 , wherein
the touch panel further has different K electrostatic capacitances which are respectively formed between a different sense line and the K drive lines,
a different parasitic capacitance exists in the different sense line, and
a value of the parasitic capacitance is different from a value of the different parasitic capacitance.
3. The touch panel controller according to claim 1 , wherein the value of the parasitic capacitance changes according to a touch of the object to be detected to the touch panel.
4. An electronic device comprising
the touch panel controller according to claim 1 and the touch panel which is controlled by the touch panel controller.