Contact detection device

A contact detection device (10, 60) comprising:

• an electrostatic sensor (7) comprising at least one detection electrode (22, 23) and detecting contact of a conductor;
• an AC power supply (11) applying at least one AC voltage to the detection electrode;
• a quadrature demodulator (12) extracting at least a quadrature component in a case where an impedance of the electrostatic sensor is represented by an in-phase component and the quadrature component, using a signal outputted from the detection electrode upon applying the AC voltage to the detection electrode;
• and
• a measuring instrument (30) detecting whether the conductor is in contact with the electrostatic sensor based on the quadrature component extracted by the quadrature demodulator, wherein
• the AC power supply switches between a first AC voltage of a first frequency and a second AC voltage of a second frequency different from the first frequency to apply the first AC voltage and the second AC voltage to the detection electrode, and
• the measuring instrument comprises:
• a storage part (34, 64) storing an alternative quadrature component (QA) corresponding to a state in which the conductor is in contact with the electrostatic sensor;
• a quadrature component comparison part (31) comparing between a first quadrature component (Q1) extracted by the quadrature demodulator upon applying the first AC voltage to the detection electrode, and a second quadrature component (Q2) extracted by the quadrature demodulator upon applying the second AC voltage to the detection electrode;
• and
• a contact determination part (33) that detects contact of the conductor with the electrostatic sensor based on the first quadrature component in a case where the first quadrature component and the second quadrature component fall within a range of a predetermined first quadrature error (ΔQE1), and detects contact of the conductor with the electrostatic sensor based on the alternative quadrature component stored in the storage part in a case where the first quadrature component and the second quadrature component fall outside the range of the first quadrature error.