THICKNESS DETECTING SENSOR

PROBLEM TO BE SOLVED: To set a wide dynamic range for detecting the thickness of a medium while accurately detecting the thickness of the medium even in cases where a dynamic range is set wide like this. SOLUTION: This thickness detecting sensor is equipped with a fixed electrode 30 and a movable electrode 40 provided opposite to each other, a plunger 2 for changing a gap between the electrodes by contacting with the medium, and a CR transmitting circuit 63 and an FV conversion circuit 64 for converting capacitance stored between the electrodes into an electric signal for medium thickness detection. With a rear end part 21 of the plunger 2 kept in contact with a gap-side electrode surface of the movable electrode 40, the movable electrode 40 is displaced in a direction away from the fixed electrode 30 correspondingly with the thickness of the medium. COPYRIGHT: (C)2005,JPO&NCIPI