PURPOSE: To measure thickness highly quickly, by connecting a resistor to one of two electrodes, between which a body to be detected is inserted, in series, and detecting the waveform state of a transient current when a rectangular-wave voltage having a specified amplitude is applied.
CONSTITUTION: A rectangular-wave voltage having a specified amplitude is applied across an electrode 12 and an electrode 13, to which a resistor 15 is connected in series, from a high-frequency power source 17, when a disk 2 and the like are inserted between the electrodes 12 and 13 under this state, the capacity between the electrodes 12 and 13 is changed in correspondence with the thickness, and the value of the wave height of the transient current flowing the resistor 13 is changed. When the change in the value of the wave height is measured, the thickness of the disk and the like can be detected highly quickly without using a bridge circuit, which measures unbalanced voltages.
KUMADA AKIO
OOTOMO YOSHIROU
