Sheet registration for a printmaking device using trail edge sensors

A method for reducing process direction errors of a sheet in a registration device comprising:

• moving a first side of the sheet along a feed path in a process direction to the registration device, the sheet having a first edge, a second edge, and a first side edge and a second side edge therebetween, wherein said first edge is approximately parallel to said second edge;
• measuring a first skew error of said first side of the sheet;
• correcting said first skew error;
• measuring a first arrival time of said first edge of the sheet at a first fixed reference to determine a first process direction position of the sheet, wherein said first edge is the trail edge of the sheet;
• correcting said first process direction position by adjusting the sheet;
• and
• delivering said first side of the adjusted sheet to a first registration datum at a first predefined delivery time.

A system for reducing process direction errors of a sheet in a registration device comprising:

• a feed path configured to move the sheet in a process direction, the sheet having a first edge, a second edge, and a first side edge and a second side edge therebetween, wherein said first edge is approximately parallel to said second edge;
• a first pair of edge sensors being configured to measure and correct a first skew of the sheet, wherein said first pair of edge sensors measure said first skew of one of the following edges of the sheet:
• said first edge, said second edge, said first side edge, and said second side edge;
• at least one point sensor, said at least one point sensor being configured to measure a first arrival time of said first edge of the sheet at a first fixed reference to determine a first process direction position of the sheet,
• a registration controller, said registration controller being configured to correct skew errors and a process direction position of the sheet;
• and
• at least one pair of registration nips along the feed path and operatively connected to said registration controller;
• wherein said feed path moves the sheet in a process direction and said registration controller registers a first side of the sheet by:
• measuring a first skew error of the sheet at one of the following edges of the sheet:
• said first edge, said second edge, said first side edge, and said second side edge using said first pair of edge sensors;
• correcting said first skew error by adjusting the sheet using said registration controller;
• measuring a first arrival time of said first edge of the sheet at a first fixed reference to determine a first process direction position of the sheet using said at least one point sensor, wherein said first edge is the trail edge of the sheet;
• correcting said first process direction position by adjusting the sheet using said registration controller;
• and
• delivering said first side of the adjusted sheet to a first registration datum at a first predefined delivery time.