| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a capacitance detecting circuit and a method in which the influence of external disturbance noise can be suppressed to improve the S/N ratio so that very small capacitances Cs and capacitance changes ΔCs of the capacitances Cs of sensor devices between row lines and column lines are detected with sufficient sensitivity, and a fingerprint sensor. <P>SOLUTION: In the capacitance detecting circuit, capacitances at the intersections formed by the column lines intersecting the row lines are detected as voltages. The capacitance detecting circuit includes a code generator for generating codes having orthogonality, a column-line driver driving a 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, a capacitance detector which is connected to the row line and outputs the total of currents generated in capacitances at the plurality of intersections with the column lines as a voltage signal, and a decoding computation means for obtaining the capacitances at each intersection by performing product sum computations between the measured voltages and the code for each of the column line groups. During a period for detecting the capacitances, the column-line driver drives the first column line group and the second column line group by complementary voltages according to the code or information indicating the inversion of the code. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
