Inspection system for inspecting the quality of printed sheets

摘要

There is described an inspection system (10) for inspecting the quality of printed sheets which are transported by a sheet conveyor system comprising at least one sheet gripper system (3a, 3b) including a plurality of spaced-apart gripper bars (32) for holding the printed sheets by a leading edge thereof. The inspection system (10) comprises an optical quality control apparatus for carrying out inspection of a first side of the printed sheets while the printed sheets are being transported by the sheet gripper system (3b). The optical quality control apparatus includes a line camera (11) for scanning the first side of the printed sheets at an inspection location which is situated at a location proximate to a portion of the sheet gripper system (3b) where the gripper bars (32) transporting the printed sheets undergo a change of direction of displacement while the printed sheets are still being scanned by the line camera (11). The inspection system (10) further comprises a suction roller (50) that is placed in front of the optical path (B) of the line camera (11) along the path (A) of the printed sheets being transported by the sheet gripper system (3b), which suction roller (50) contacts a second side of the printed sheets opposite to the first side which is being scanned by the line camera (11), the suction roller (50) being driven at a selected circumferential speed to drive successive portions of the printed sheets being inspected by the quality control apparatus at a determined and controlled speed past the line camera (11).

主权项

1. An inspection system for inspecting the quality of printed sheets which are transported by a sheet conveyor system comprising at least one sheet gripper system including a plurality of spaced-apart gripper bars for holding the printed sheets by a leading edge thereof, said inspection system comprising an optical quality control apparatus for carrying out inspection of a first side of the printed sheets while the printed sheets are being transported by the sheet gripper system,
wherein said optical quality control apparatus includes a line camera for scanning the first side of the printed sheets, said inspection system further comprising: a suction roller that is placed in front of the optical path of the line camera along the path of the printed sheets being transported by the sheet gripper system, which suction roller contacts a second side of the printed sheets opposite to the first side which is being scanned by the line camera; and a suction box located immediately before said suction roller with respect to a direction of displacement of the printed sheets and cooperating with said second side of the printed sheets for aspirating at least a portion of the second side of the printed sheets against a substantially flat surface of the suction box before contacting the suction roller, wherein the suction roller is provided with a plurality of recesses distributed along an axis of rotation of the suction roller on a part of the circumference of the suction roller, a location of the recesses corresponding to a location of grippers of each gripper bar, and wherein a downstream end of the suction box with respect to the direction of displacement of the printed sheets is provided with a plurality of cut-outs corresponding in number and location to the grippers of each gripper bar.