| 摘要 |
PROBLEM TO BE SOLVED: To improve measurement precision, shorten measurement time, and reduce a manufacturing cost by providing a sensor electrode where a sensing surface is formed in ring and a shield electrode arranged along its perimeter. SOLUTION: A thickness sensor 2 comprises a sensor electrode 11 where a sensing surface is formed in ring and a shield electrode 12a arranged along the outer perimeter of the sensor electrode 11. In measuring thickness, the thickness sensor 2 is so arranged that the sensor electrode 11 and shield electrode 12a face, for example, a base electrode, with an object to be measured provided between the thickness sensor 2 and the base electrode. Here, even with a dispersion in thickness among parts of the object, the electrostatic capacity between the sensor electrode 11 and the base electrode is measured as a total electrostatic capacity containing effect from dispersion in thickness of the object, resulting in the same value at all times. Thus, the total electrostatic capacity is accurately measured at a single measurement, automatically averaging the dispersion in thickness.
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