Control of non-linear and non-holonomic sheet registration devices

In xerographic printers, one important quality metric to customers is the image to paper registration. This metric measures how well the image is positioned on the paper on the finished print, relative to its intended position. In the media path the sheet registration device, located immediately upstream from the image transfer section, is responsible for aligning the sheet with the image. In modern, high-speed printers these devices are most often mechatronic devices utilizing sophisticated sensors and active feedback control. This paper gives an overview of registration goals and constraints, several existing technologies, and control approaches. The differential drive registration nip and current state of the art control approach are explained in detail.