Capacitance change detection device

摘要

A capacitance change detection device includes a sensor electrode, and an electrode capacitance measurement device for measuring capacitance of the sensor electrode on the basis of a correlation value based on a reference capacitance at every first predetermined time. A detection signal is generated when a current measurement value of capacitance is changed by equal to or greater predetermined threshold value than a measurement value obtained a second predetermined time before the current measurement value is measured. The capacitance change detection device further includes a sensitivity compensation capacitance for generating capacitance variations equivalent to specific variations of capacitance of the sensor electrode, and being switched between a connected state and a disconnected state. The threshold value is determined as a difference between measurement values of capacitance of the sensor electrode measured at the connected state and at the disconnected state. The threshold value is renewed at every third predetermined time.