| 摘要 |
<p>A method for analyzing the internal pressure of a closed container (12) includes inducing vibration in a surface (26) of sealed container or can (12); detecting sound resulting from sealed vibration of such container (12); deriving information representing this detected sound; and determining whether this information corresponds to predetermined spectral frequency conditions and predetermined spectral amplitude conditions. To ensure that test results are not affected by any modulating distortion present in the information, the information is tested for the presence of a modulating distortion, which if present then the information is processed to compensate for the effects of this modulating distortion, prior to being tested against the predetermined spectral conditions. Upper and lower amplitude limits which define the spectral amplitude condition, and average values from deviations therefrom may be reset periodically to allow for slow changes in manufacturing conditions by accumulating and analyzing amplitude data from a plurality of containers judged to have an acceptable internal pressure, while deriving and resetting average value and deviations therefrom.</p> |
