Capacitance sensor

A capacitance sensor comprising:

• a first capacitor and a second capacitor connected in series to a power supply;
• a first switch connected between two terminals of the first capacitor;
• a second switch connected between the first capacitor and the second capacitor;
• a third switch connected between two terminals of the second capacitor;
• a switch control unit configured to perform a first switching process that turns on the first switch and then repeatedly perform a second switching process that complementarily switches off and on the second switch and the third switch while turning off the first switch;
• an obtaining unit configured to calculate, as a sensor output value, a number of times the second switching process is repeated until a magnitude relationship reverses between an intermediate potential between the first and second capacitors and a reference potential that has been set in advance;
• a calculation unit configured to calculate a sensor output corrected value, the sensor output corrected value being obtained by correcting the sensor output value such that a resolution becomes uniform;
• and
• a determination unit configured to determine whether a detection target exists from a magnitude relationship between a sensor output difference value and a determination threshold value that has been set in advance, the sensor output difference value being a difference between a current one of the sensor output corrected value and a reference sensor output value that is based on a previous one of the sensor output corrected value.