| 摘要 |
A device for identifying registration marks includes two reading heads 30 and 31 connected by an amplifier 32 to an analyzing device 33 which processes the information read on the web 2 running over an engraved cylinder 38. An angular encoder 37 of the cylinder calculates the angular position of the engraved cylinder 38 while it rotates, and transmits it to the analyzing device 33, which memorises the received information from cycle to cycle of the cylinder 38. Said device 33 also sends out a signal 36 in order to control the idler roller 41 creating a positive or negative elongation of the web 2 between two points 47, 48 on it. The change in length, thus achieved, allows the identification of the registering marks, by comparing the different registering mark reading results before and after the change in length. <IMAGE> |
