| 摘要 |
PROBLEM TO BE SOLVED: To provide a capacitance detecting circuit, its detection method, and a fingerprint sensor, which detect a valueΔCs of a minute change in a capacitance value Cs at an intersection of a column line and a row line intersecting each other with sufficient sensitivity, by reducing the influence of disturbance noises and raising a signal to noise ratio. SOLUTION: This capacitance detecting circuit is a circuit for detecting the capacitance of each intersection between a plurality of column lines and row lines which intersect as a voltage value, and is provided with: a code generating unit for generating a code having orthogonality in time sequence; a column line group selection unit for dividing the plurality of column lines into groups of column lines of a predetermined number of column lines and selecting a group of column lines being an object to be measured; a column line drive unit for driving a plurality of column lines in response to the code for each group of column lines to be selected; a capacitance measuring unit which outputs as a measured voltage a total sum of current values corresponding to the capacitance values of the intersections between row lines and the driven column lines; and a decoding processing unit for performing operation for a sum of products of the measured voltage and the code, for each group of column lines and finding a voltage value corresponding to the capacitance of each intersection. COPYRIGHT: (C)2005,JPO&NCIPI
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