Canon Production Printing Holding B.v.

Johan P Smits

Sjirk H Koekebakker

Mark Rietbergen

Joseph A Schulkes

A sheet printer includes a sheet conveyor assembly including a first conveyor with a first holding device configured for exerting a holding force on a sheet proportional to a coverage of the sheet on the first conveyor and a second conveyor upstream of the first conveyor including a second holding device configured for holding and releasing the sheet, a print head assembly positioned over the first conveyor, a detector assembly for sensing the transport of the first conveyor, a controller storing on its memory a sheet media catalogue and configured to control a release timing of the second holding device for releasing the sheet partially engaged by the first conveyor based on a media type parameter selected from the media catalogue and to control the print head assembly to commence printing the sheet based on transport information from the detector assembly.

Sheet conveyor assembly for a printer with media type dependent transfer

The invention relates to a print system comprising at least two page-wide arrays of ink jet print heads, positioned in a frame over a conveyor belt for transporting a substrate underneath the arrays, three sensors for reading markers on the conveyor belt and a control unit that is configured to derive control signals from encoder signals of the three sensors. Two sensors are directly connected to the frame and a third sensor is connected to one of the said two sensors by an element with virtually no thermal expansion, extending in transport direction. The control signals, comprising signals for controlling a transport speed of the conveyor belt and line pulses for the at least two print heads, are derived in such a way that an amount of thermal expansion of the frame is determined and an absolute print resolution is maintained.

Print head frame structure and control

A sheet transport system for moving a sheet in a transport direction while adjusting a position of the sheet in a lateral direction normal to the transport direction to a target position, includes first and second pinch roller sets spaced apart from one another in the transport direction, each pinch roller set including two pairs of pinch rollers spaced apart from one another in the lateral direction, each pair forming a nip for pinching and driving the sheet with an individually controllable speed; a detection system for detecting a position of the sheet in the lateral direction while the sheet is pinched by the first pinch roller set; and a control system configured for carrying out the following actions: by controlling the speeds of the pinch rollers of the first pinch roller set before the sheet has reached the second pinch roller set, rotating the sheet by a first rotation angle for adjusting a given reference point on a leading part of the sheet to its target position; and when the sheet has left the first pinch roller set and while the reference point travels along a path segment that is symmetric with respect to the second pinch roller set, rotating, by controlling the speeds of the pinch rollers of the second pinch roller set, the sheet by a second rotation angle for aligning a leading edge of the sheet in the lateral direction.

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Venlo, Netherlands

Johan P Smits