Sheet Registration for Duplex Printing on Non-Rectangular Media

Solution Overview

Problem

Existing sheet registration methods fail to adequately align front and back side images on non-rectangular sheets, particularly trapezoid-shaped sheets, leading to misalignment issues in the final printed product.

Innovation Solution

A method involving determining the relative orientations of three edges of a sheet during a first pass, aligning one edge with a predetermined direction, printing a first image, flipping the sheet for a second pass, and aligning the same edge for printing a second image, while adjusting the start of printing based on known edge orientations to correct for deviations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single edge is detected for sheet registration, then the registration process is simple, but misalignment between front and back side images occurs

Engineering Contradiction:

Improveregistration process complexityVSAvoidimage alignment precision

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The sheet edge detection is segmented into multiple independent detection points along the edge. Instead of detecting a single edge point, the system detects multiple points (at least three) distributed along the sheet edge, allowing calculation of the edge's orientation and position. This segmentation enables precise determination of the sheet's geometric parameters while maintaining a relatively simple detection mechanism.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system performs preliminary detection and calculation of sheet edge orientations and positions before the actual printing process. By detecting multiple edge points and calculating the sheet's geometric parameters in advance, the system prepares correction data that is applied during printing to ensure accurate alignment of front and back side images.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If sheet registration is performed without considering edge orientations, then processing is faster, but misalignment occurs on non-rectangular sheets

Engineering Contradiction:

Improvesheet processing speedVSAvoidimage alignment precision

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The system performs preliminary detection and calculation of sheet edge orientations and positions before the actual printing process. By detecting multiple edge points and calculating the sheet's geometric parameters in advance, the system prepares correction data that is applied during printing to ensure accurate alignment of front and back side images.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from multiple edge point detections to continuously monitor and correct sheet positioning. The detected edge orientations and positions provide feedback that is used to calculate and apply real-time corrections during the printing process, ensuring accurate image alignment while maintaining processing speed.

Inventive Principle:

Principle #23Feedback

3Ease of operation

If the same edge alignment method is used for both front and back side printing, then the process is consistent, but rotational misalignment occurs on trapezoid-shaped sheets

Engineering Contradiction:

Improveprinting process consistencyVSAvoidimage rotational alignment

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The system performs preliminary detection and calculation of sheet edge orientations and positions before the actual printing process. By detecting multiple edge points and calculating the sheet's geometric parameters in advance, the system prepares correction data that is applied during printing to ensure accurate alignment of front and back side images.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts printing parameters based on detected sheet geometry. By calculating the orientations of multiple edges and determining the sheet's specific geometric characteristics, the system modifies printing parameters such as image positioning and orientation to compensate for non-rectangular sheet shapes, ensuring accurate alignment while maintaining process consistency.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12522458B2Sheet registration device for non-rectangular sheets

Publication Date: 2026.01.13 CANON PRODN PRINTING HLDG BV

AI summary

When duplex printing non-rectangular sheets of printable media, the sheets require proper registration to prevent misalignment of front and back images. This is ensured by: determining relative orientations of three different edges of a sheet being transported towards print station on a first pass; registering the sheet on the first pass by aligning one of the edges with respect to a predetermined alignment direction; printing a first image on a first side of the registered sheet; flipping the sheet on a second pass; registering the flipped sheet by aligning one of the edges with respect to a predetermined alignment direction; and printing a second image on a second side of the registered, flipped sheet aligned with the first image based on the determined relative orientations.