Patent ID: 7084645
Filing Date: 2006-08-01
Classification: G06F,G06K

Abstract:
1. A capacitance detecting circuit for detecting changes in capacitances at intersections between a plurality of column lines and a row line as voltages, comprising: code generating means for generating code having orthogonality in chronological order; column-line driving means for driving the plurality of column lines based on the code by dividing the column lines into a first column line group and a second column line group; capacitance detecting means connected to the row line, for converting a total of currents generated in capacitances at the intersections with the driven column lines into a voltage signal and outputting the converted voltage signal; and decoding computation means for determining the voltages corresponding to the capacitances at the intersections for each of the column line groups by performing product sum computation between the measured voltages and the code, wherein, in a period for detecting the capacitances, the column-line driving means drives one of the first column line group and the second column line group to shift from a first voltage to a second voltage and drives the other one of the first column line group and the second column line group to shift from the second voltage to the first voltage according to the code or information indicating the inversion of the code.