Noncontact voltage measurement apparatus

A noncontact voltage measurement apparatus for measuring, without being electrically directly connected to a conductive measurement target, an alternating voltage applied to the measurement target, the noncontact voltage measurement apparatus comprising:

• a base having a first substrate and a second substrate opposing the first substrate with a space interposed therebetween;
• a sensing electrode disposed on the first substrate, a first voltage corresponding to the alternating voltage of the measurement target being applied to the sensing electrode;
• a feedback electrode disposed on the second substrate so as to oppose the sensing electrode, a second voltage being applied to the feedback electrode, the second voltage being an alternating voltage;
• an elastic conductive movable body movably supported between the sensing electrode and the feedback electrode by the base, the movable body being displaced toward the sensing electrode or the feedback electrode in accordance with a first Coulomb force generated between the movable body and the sensing electrode and a second Coulomb force generated between the movable body and the feedback electrode, an elastic force of the movable body causing the movable body to return to a predetermined neutral position;
• a pair of displacement detection units that detect a displacement of the movable body with respect to the predetermined neutral position, the pair of displacement detection units including:
• a first detection unit including:
• a first magnet disposed on a first surface of the movable body facing the sensing electrode;
• and
• a first magnetic detection unit disposed on the first substrate, the first magnetic detection unit detecting a first magnetic field formed by the first magnet so as to output a first detection result;
• and
• a second detection unit including:
• a second magnet disposed on a second surface of the movable body facing the feedback electrode;
• and
• a second magnetic detection unit disposed on the second substrate, the second magnetic detection unit detecting a second magnetic field formed by the second magnet so as to output a second detection result;
• a voltage applying unit that applies the second voltage to the feedback electrode;
• and
• a control unit that controls the second voltage output from the voltage applying unit such that a difference between the first and second detection results approaches a predetermined reference value indicating the neutral position of the movable body.