| 摘要 |
A capacitance sensor 10 comprises a slotted conductive body 11 with an electrode 29 symmetrically disposed in the slot 13 and insulated from the body 11. The sensor 10 is used to sense the thickness of a dielectric body 40 by reciprocally traversing the body in engagement therewith while energized by an oscillator 61. An adjustable reference oscillator 70 is tuned to the frequency of the first- mentioned oscillator when disengaged from the body and its frequency is adjusted during disengagement periods to re-calibrate the apparatus. Comparison of the oscillator frequencies when the first- mentioned oscillator is engaged with the body gives an indication of the body thickness. <IMAGE>
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