Patent ID: 7583086

Claim:
A potential sensor comprising: first and second detection electrodes disposed in a line and adjacent each other on a plane of a substrate opposed to a potential-measured object a potential of which is to be measured; and a movable shutter positioned between the detection electrodes and the potential-measured object with gaps thereto, both ends of the movable shutter being supported by a supporting member, wherein said movable shutter is configured to assume a first state and a second state, the first detection electrode being entirely exposed and the second detection electrode being entirely masked when the movable shutter assumes the first state, and the first detection electrode being entirely masked and the second detection electrode being entirely exposed when the movable shutter assumes the second state, and wherein the movable shutter is comprised of a first shutter vibrating with a first phase and a second shutter vibrating with a second phase, the first and second phase being opposite phases to each other.