| 摘要 |
<p>The invention concerns a method for discriminating in a machine processing mail items, mail items (P1, P2, P3) contained in paper envelopes and mail items contained in plastic envelopes, which consists in moving each item in front of a suction pressure element (6) so as to produce an acoustic signal resulting from the suction effect of the suction pressure element on a surface of said item, and in comparing said acoustic signal with a reference signal to detect whether the envelope of said item is made of paper or of plastic material.</p> |
