| 摘要 |
When a current charge method is used as a method of detecting capacitance, there poses a problem in which S/N is deteriorated by a dispersion in element characteristics of a cell to be detected and when a voltage charge method is used, since parasitic capacitances of column sense lines are very large and accordingly, there is needed some devise for sampling electric charge charged to the capacitance. There are arranged unit cells having detection electrodes and cell selecting switches connected between the detection electrodes and column sense lines in an array shape, electric charge is charged from detecting circuits to the detection electrodes under constant charge voltage, and thereafter, the column sense lines are imaginarily grounded to thereby detect the capacitances formed between the detection electrodes and the surface of the finger in accordance with recesses and projections of a fingerprint via the column sense lines.
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