Apparatus for and method of producing proof prints

摘要

An apparatus for producing proof prints on which the correctness of page impositions can be checked comprises a stand configured to receive a roll of paper. A first printer and a second printer are provided for printing pages on the front side and the rear side, respectively, of a paper web fed from the paper roll. An optical sensor is arranged between the first printer and the second printer. The optical sensor is configured to detect the position of an alignment mark which has been printed by the first printer on the front side of the paper. A control unit modifies the spatial relationship between the rear side of the paper and what is printed on the rear side of the paper depending on the detected position of the alignment mark. This can be accomplished either by electronically modifying the second pages as such, or by mechanically modifying the paper position with respect to a printing head contained in the second printer.

主权项

1. An apparatus for producing proof prints on a print medium having a front side and a rear side for which correctness of page impositions can be checked, comprising:
a) a stand configured to receive a roll of print medium, b) a first printer for printing pages on a front side of the print medium fed from the roll of the print medium, c) a second printer for printing pages on a rear side of the print medium, d) a first optical sensor arranged immediately outside of a print medium exit of the first printer, and configured to detect a code stripe printed by the first printer on the front side of the print medium and encoding an absolute Y position of the print medium along a feed direction of the print medium, e) a second optical sensor arranged between the first optical sensor and a print medium entrance of the second printer, and also configured to detect the code stripe, and f) a control unit configured to halt at least the second printer at least if the first optical sensor detects that a feed velocity of the print medium at the print medium exit of the first printer decreases abruptly, and to control the second printer such that the second printer prints the pages on the rear side of the print medium at a correct Y position of the print medium.