Patent ID: 7015705

Claim:
A capacitance detection apparatus, comprising: a first open/close switch provided between both ends of a standard capacitor, one end of the standard capacitor being connected to a first voltage source; a second open/close switch provided between one end of a first capacitor to be measured and the other end of the standard capacitor, the other end of the first capacitor to be measured being connected to a second voltage source or free space; a third open/close switch provided between both ends of the first capacitor to be measured; a voltage measurement means for measuring voltage of the other end of the standard capacitor; a switch control means for performing a first switching control performing a first switching operation to open the first open/close switch after closing thereof, performing a second switching operation to open the second open/close switch after closing thereof, and a third switching operation to close the third open/close switch after closing thereof, wherein the second and third switching operations are repeatedly performed after the first switching operation; a counting means for counting the number of repetition of the second switching operation; and a judging means for judging a change of the capacitance of the first capacitor to be measured according to the number of repetition of the second switching operation, which is the number counted by the counting means during the voltage of the other end of the standard capacitor measured by the voltage measurement means being changed from an initial voltage after the first switching operation by a predetermined magnitude.