| 摘要 |
The device must easily allow a multiplication of the monitoring points over the width of a sheet and must offer a degree of elasticity at these points. It includes a drive roller (13) rotating in a frame and at least one carriage (14) which can move tangentially to the said roller on an individual support (15) stressed elastically, continuously, towards the said roller in a position which is determined by an adjustable fixed stop (75). The said carriage has a monitoring face (17) parallel to the axis of the roller (13) and to the direction of the movement of the carriage. Elastic means (64) return each carriage towards an upstream standby position facing the drive roller, the position of the stop (75) being such that the monitoring face (17) of the carriage is separated from the cylindrical surface of the roller (13) by a gap very slightly larger than the thickness of a single sheet (1) and, in all cases, less than the total thickness of two superposed sheets. In addition, it includes means (16) for detecting a translational movement of each carriage (14) in the downstream direction in opposition to its elastic return means, from its upstream standby position, under the effect of the driving, produced by too thick a sheet or the combination of several superposed sheets driven together themselves in the downstream direction by the roller (13). <IMAGE>
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