CAPACITANCE DETECTOR, METHOD OF DETECTING CAPACITANCE, AND FINGERPRINT SENSOR

摘要

PROBLEM TO BE SOLVED: To provide a capacitance detector and a method for detecting capacitance, which can surely detect minute capacitances without using a reference capacitance that causes a measurement error, and a fingerprint sensor.

SOLUTION: An area sensor part 1 has a matrix of a plurality of column lines and a plurality of row lines and generates minute capacitances near intersections of the lines. A capacitance detection circuit 4a detects the capacitance of the area sensor part 1. A column-line driver part 41 outputs to the column lines a first voltage and then a second voltage. A switched capacitor circuit 42 outputs a third voltage corresponding to the charging of the capacitance when the first voltage is applied to the column lines, outputs a fourth voltage corresponding to the charging of the capacitance when the second voltage is applied to the column lines. An arithmetic control circuit 47 calculates the difference between the third voltage and the fourth voltage for the capacitance at each of the intersections.

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