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