| 摘要 |
PROBLEM TO BE SOLVED: To provide an apparatus and method for detecting change in a capacitance value capable of detecting variations of the capacitance value between a sensor capacitive element and a reference capacitive element with high precision by excluding the effect of a parasitic capacitive element of a capacitive sensor to regulate fluctuations in the capacitance value. SOLUTION: For the capacitive sensor having the sensor capacitive element and the reference capacitive element and keeping one terminal connected to fixed electric potential as a common terminal, a reading voltage is applied to the other terminal of each capacitive element to accumulate electric charges, and the electric charges are extracted from the other terminal. The extracted electric charges are converted into a voltage signal by a voltage conversion section, and its difference signal is amplified by the difference signal amplifier section. The reading voltage is regulated by a voltage regulating section according to need. In the reading voltage, a voltage level is commonly regulated to regulate a dynamic range, while the voltage level is individually regulated to regulate a capacitive offset. COPYRIGHT: (C)2007,JPO&INPIT
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