Patent ID: 7245131

Claim:
A capacitance detection apparatus for detecting an approach of an object on the basis of a change of capacitance, comprising: a detection electrode for detecting the change of the capacitance by approaching the object; a calculating circuit for calculating a value associated with the change of the capacitance detected by the detection electrode; a judging circuit for judging whether the value calculated by the calculating circuit is a normal value which is calculated after a predetermined period of time lapse from a start time of the capacitance detection apparatus or an initial value which is calculated before the predetermined period of time lapse from the start time of the capacitance detection apparatus; an initial reference value-determining circuit for determining an initial reference value for the value judged by the judging circuit as the initial value; a difference calculating circuit for calculating a difference between the value judged by the judging circuit as the normal value and a value calculated at a time earlier than a time when the value judged by the judging circuit as the normal value is calculated by the predetermined period of time or longer, or a difference between the value judged by the judging circuit as the initial value and the initial reference value determined by the initial reference value-determining circuit; and a determining circuit for determining whether or not the object is approaching by comparing the difference calculated by the difference calculating circuit with a predetermined threshold value.