Patent ID: 8594555

Claim:
A duplex printing system for printing on a first side and a second side of a sheet of media in a first pass and a second pass, respectively, the system comprising: a registration system comprising: an edge sensor to detect a first end of the sheet of media in the first pass; a registration marking unit that deposits at least two registration markers on a second side of the sheet in the first pass; a marker sensor that detects at least two of the at least two registration markers in the second pass; and a registration nip for positioning the sheet of media, wherein the first side of the sheet of media for printing is registered in a first pass in response to detection of the first end of the sheet, wherein the second side of the sheet for printing in a second pass is registered in response to detection of at least two of the at least two registration markers deposited proximate to a second end of the sheet, the at least two registration markers facilitating detection of the sheet in proximity to a point of registration, and wherein the marker sensor detects the position of the at least two registration markers to detect a skew in the sheet of media prior to second side printing and the registration nip deskews the sheet of media; a printing station having an image marking unit to print a first image on the first side of the sheet in the first pass and to print a second image on the second side of the sheet in the second pass; and a duplex return to transport the sheet to the registration system after printing in the first pass to facilitate printing in the second pass.