Conveyor mechanism and a method for adjusting a conveyor mechanism

A suction belt conveyor mechanism for conveying a plurality of sheets along a transport path in a printing system, wherein the conveyor mechanism comprises:

• a movable endless suction belt member comprising perforations for communicating an under-pressure to an outer surface of the endless suction belt member on which the sheets are supported, wherein the under-pressure holds the sheets in a fixed position on the endless suction belt member as the endless suction belt member is moved to convey the sheets along the transport path;
• a drive mechanism comprising a first roller and a second roller, which rollers support and drive a movement of the endless suction belt member to convey the sheets along the transport path;
• and
• an adjustment system configured to detect and correct skewing of the endless suction belt member as the endless suction belt member conveys the sheets along the transport path, the adjustment system comprising:
• at least one marker provided on or in the endless suction belt member;
• a sensor arrangement for detecting each marker at at least two discrete positions spaced apart from one another by a predefined distance along a length of the transport path, wherein the sensor arrangement comprises:
• a first sensor device provided at a first position for detecting each marker;
• and
• a second sensor device provided at a second position for detecting each marker,
• wherein the first position and the second position are spaced apart from one another by the predefined distance in a transport direction of the transport path;
• and
• a processor for processing data provided by the sensor arrangement to determine the skewing of the endless suction belt member,
• wherein the first roller and the second roller of the drive mechanism are mounted on a movable conveyor frame, and
• wherein the adjustment system comprises a frame shifting device, the frame shifting device comprising at least one actuator for moving the moveable conveyor frame relative to a fixed framework, such that the endless suction belt member is moved to correct the detected skewing,
• wherein the at least one marker comprises a plurality of markers which are spaced apart along a length of the endless suction belt member, wherein each marker is fixed with respect to the endless suction belt member, and wherein each marker comprises its own characteristic form and/or each adjoining pair of said plurality of markers are spaced apart from one another along the length of the endless suction belt member at a unique spacing, such that each marker is uniquely identifiable by the sensor arrangement.