Patent ID: 7752009

Claim:
A method of checking the height Hi of a mail item on the fly relative to at least one dimensional threshold SH defining a change in postage, each mail item having longitudinal peripheral edges of length Di and transverse peripheral edges of height Hi; said method comprising: causing the mail items to advance at a constant speed V along a reference surface so that each mail item is in contact with said reference surface over at least a portion of one of its longitudinal edges; detecting the presence of a mail item relative to a given point of the reference surface firstly at a first distance d 1 close to the reference surface and measured perpendicularly thereto, and secondly at a second distance d 2 further away from the reference surface, measured perpendicularly thereto, and corresponding to said dimensional threshold SH; detecting first and second times of presence t 1 , t 2 for which the same mail item is present at said first and second distances d 1 , d 2 relative to the reference surface; comparing the ratio t 2 /t 1 between the second and first times of presence at the second distance d 2 and at the first distance d 1 with a value equal to (1ε), where ε represents a correction coefficient of less than 1 that depends on the tolerances for detection of the presence of a mail item; and considering that the height H of a mail item is greater than the dimensional threshold SH if, and only if, the relationship t 2 /t 1 >1−ε is true.