| 摘要 |
<p>In printing apparatus in which a web flow path extends from a printing cylinder (12) to a machine (20) operating in synchronism with the printing cylinder to perform a non-printing operation on the web in register with the printed images, first and second mark detectors (24 and 26) are arranged in the flow path immediately after the first printing cylinder (12) and immediately before the machine performing the non-printing operation (20) respectively. As the printing cylinder (12) rotates synchronously with the cycle of operation of the non-printing machine (20), the signal from the first detector, when it sees the mark applied by the printing cylinder, is indicative of the position of the non-printing machine in its cycle of operation. The signal from the second detector (26) is indicative of the mark position after the web has travelled along the whole of the flow path to the non-printing machine. These two signals are compared and the result of the comparison is used to adjust register control means to correct for any register error between the printed image and the non-printing operation (for example cutting or folding).</p> |
