Patent ID: 7098675

Claim:
A capacitance change detection device comprising: a sensor electrode at which capacitance varies; an electrode capacitance measurement means fix measuring capacitance of the sensor electrode on the basis of a correlation value based on a predetermined reference capacitance at every first predetermined time, wherein a detection signal is generated when a current measurement value of capacitance of the sensor electrode measured by the electrode capacitance measurement means is changed equal to or greater than a predetermined threshold value in comparison to a measurement value obtained a second predetermined Lime before a timing that the current measurement value is measured; a predetermined sensitivity compensation capacitance for generating capacitance variations equivalent to a specific variations of capacitance of the sensor electrode generated by existence of a specific object at capacitance of the sensor electrode, wherein the sensitivity compensation capacitance is configured to he switched between a connected state at which the sensitivity compensation capacitance is connected to the sensor electrode and a disconnected state at which the sensitivity compensation capacitance is disconnected from the sensor electrode, and wherein the threshold value is determined as a difference between a measurement value of capacitance of the sensor electrode measured by the electrode capacitance measurement means at the connected state and a measurement value of capacitance of the sensor electrode measured by the electrode capacitance measurement means at the disconnected state, and the threshold value is configured to he renewed at every third predetermined time.