Patent ID: 7185981
Filing Date: 2007-03-06
Classification: B41J

Abstract:
1. A duplex printing method comprising: providing a printing apparatus that comprises: means for transporting a media sheet along a first media path for printing on a first side of the media sheet; a print zone along said first media path: and a duplex module configured to change the orientation of the media sheet from a first orientation to a second orientation suitable for printing on a second side of the media sheet, the entrance to the duplex module being located along said first media path and upstream of the print zone; printing swaths of ink dots on a top portion of the first side of the media sheet in the print zone, at least one swath containing black ink dots; advancing the media sheet in a forward direction during printing; calculating black ink density for each swath containing black ink dots; determining the highest black ink density; stopping the advancing movement of the media sheet after the last swath has been printed on the first side, whereby the trailing edge of the stopped media sheet has not bypassed the entrance to the duplex module; detecting that the trailing edge of the stopped media sheet has not bypassed the entrance to the duplex module; moving the media sheet in the forward direction for a minimum distance to enable the trailing edge to enter the duplex module; allowing the first side to dry for a drying period, the drying period being based on the highest black ink density; moving the dried media sheet in a reverse direction from the print zone to the duplex module to change the orientation of the media sheet from the first orientation to a second orientation suitable for printing on a second side of the media sheet; and re-introducing the media sheet into the print zone for printing on the second side.