Patent ID: 8174271

Claim:
A capacitance change measuring circuit for a capacitive sensor device comprising: an electrode drive section line-sequentially applying an input pulse signal with a given period to a plurality of columns of first electrode patterns in the capacitive sensor device; a peak hold circuit storing a peak level of a detection signal, which is extracted from each of a plurality of columns of second electrode patterns crossing the first electrode patterns in other layer, into a capacitive element as a corresponding potential; a current source initializing the potential of the capacitive element within one period of the input pulse signal; a comparator comparing the potential held in the capacitive element with a reference value; and a plurality of determination sections each determining whether or not an input operation using a human body or an object having electric characteristics equal to those of the human body is executed, based on a timing information and a reference timing information, the timing information representing a timing when the potential held in the capacitive element crosses the reference value.