| 摘要 |
PURPOSE:To enable the non-contact thickness signal with high accuracy to be formed, by a method wherein the differential signal is obtained by respectively connecting 2 pieces of condensers made dielectric film to exist commonly between with oscillators. CONSTITUTION:The main electrode EM of a dielectric film X and the subelectrode ES having the area of 1/n thereof are arranged aparting from the film X by a fixed distance (y) from the electrode EM, and capacitances are respectively formed between an earth electrode EG and respective electrodes EM and ES. The frequency signal having the linear relation as to the thickness of measured object can be obtained by connecting those 2 sets of capacitances respectively with the oscillations OSC1 and OSC2 and by taking out the difference of the output frequency of both oscillators. |
