| 摘要 |
The oppts. inspects the internal pressure of a hermitically sealed container such as a can. The appts. measures the degree of unevenness of the surface of an elastic cover(a1) of each can(a). The unevenness is produced by the internal pressure. The distance from a fixed position, exterior to the can, to the cover surface is measured on the basis of the change in inductance. Coils(8) in a bridge cct.(9) are used in points which are the center & peripheral portions of the cover. A value is derived from the difference between a mean value of the two measured values at the peripheral portion & at the center of the cover.
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