Duplex Printing Shrinkage Compensation via Predictive Scaling
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Solution Overview
Problem
Existing duplex printing methods face challenges in achieving high accuracy and productivity due to unpredictable media sheet shrinkage, which leads to registration issues between front and back side images, and existing compensation methods are either inaccurate or time-consuming, degrading productivity.
Innovation Solution
A method that predicts media sheet shrinkage using process parameters and a statistical model, adjusts model parameters based on actual measurements, and iteratively optimizes predictions to improve accuracy, allowing early scaling of back side images while adapting to varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the actual amount of shrinkage is measured to ensure high accuracy in shrinkage compensation, then manufacturing precision is improved, but productivity is degraded due to the time-consuming measurement and inevitable delay before printing the back side image
Solution Approach 1:
The patent applies preliminary action by measuring the shrinkage of the front side image immediately after printing while the media sheet is still in the printer, before the sheet is ejected. This timing allows the measurement to be completed in advance of when the back side needs to be printed, eliminating the delay that would otherwise occur. The control unit processes the measurement data and determines the scaled dimensions for the back side image during this preliminary period, ensuring both high accuracy and maintained productivity.
2Productivity
If a model-based prediction approach is used to maintain productivity by enabling early scaling, then productivity is improved, but measurement precision deteriorates due to poor accuracy in estimating shrinkage based on known properties
Solution Approach 1:
The patent implements feedback by measuring the actual shrinkage of the front side image and using this measurement to adjust and refine the shrinkage model for subsequent sheets. The control unit stores the measured shrinkage data and uses it to improve the accuracy of predictions for future media sheets. This feedback mechanism allows the system to maintain high productivity through model-based prediction while continuously improving measurement precision through actual measurements, resolving the contradiction between the two objectives.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach achieves high accuracy in shrinkage compensation and maintains productivity by enabling early scaling of back side images, with the model automatically adapting to changing process parameters and media properties, leading to continuous improvement in prediction accuracy.
Implementation Method 1
the sheet will become wetted with ink, and a subsequent step of curing the ink by heating the sheet or irradiating it with UV light, for example, usually causes the sheet to shrink to some extent
Data Source
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AI summary
A duplex printing method comprising, for each duplex copy to be printed, the steps of: a) determining an amount of shrinkage of a media sheet (58) onto which a front side image has been printed; b) scaling an image to be printed on a back side of the sheet (58) with a scaling function that depends upon the determined shrinkage; and c) printing the scaled image on the back side of the sheet (58), wherein the step a) comprises the steps of: a1)predicting a shrinkage of a media sheet (58) on the basis of process parameters that characterize a process of printing the front side image and on the basis of a model that is defined by a set of model parameters and describes a dependence of the shrinkage on the process parameters (P), said process parameters including at least an amount of marking material to be applied to the front side of the sheet (58), a2) measuring (60) an actual shrinkage of the sheet; and a3)adjusting the model parameters (M, M') based on a comparison between the predicted shrinkage (S) and the measured shrinkage (A) to improve a prediction of a shrinkage for a subsequent sheet.