| 摘要 |
Sheet feed to a printing machine 5 is controlled by monitoring a sheet fed to a registration line 3 of the machine and evaluating the monitoring signals at two different evaluating times per machine cycle. On detection of a correct sheet at the first evaluating time, evaluation at the second evaluating time is withheld and the sheet is released to enter the printing press. If, however, a skewed sheet is detected at the first evaluating time the sheet conveying is interrupted for one cycle and evaluation at the second evaluating time is withheld. Thereafter, on detection of a correct sheet at the first evaluating time of the succeeding cycle, evaluation at second evaluating time is withheld and the sheet is released to enter the machine, or on detection of a skewed sheet at the first evaluating time of the succeeding cycle the sheet conveying is stopped. If no sheet is detected at the first evaluating time, evaluation is carried out at the second evaluating time and, on detection of a correct or skewed sheet, the sheet conveying is interrupted for one cycle and evaluation is carried out at the first evaluating time of the succeeding cycle. If a skewed or lacking sheet is detected in any subsequent cycle, any such sheet is prevented from entering the machine and sheet conveying is stopped. <IMAGE> |
