Printing Apparatus Ink Position Correction via Quadratic Curve Fitting
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Solution Overview
Problem
Conventional printing apparatuses with a reduced number of edge sensors suffer from low accuracy in correcting ink positions, leading to poor print quality due to skewing or meandering of elongate printing media during transport.
Innovation Solution
A printing apparatus with a detecting unit of at least three detectors arranged along the width direction of the printing medium, a variation history acquirer to derive function approximate curves, and a predicted position calculator using Yule-Walker's equation to calculate and correct ink positions with high accuracy, allowing for precise positioning without additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the number of edge sensors is reduced, then the apparatus cost decreases, but the accuracy of inking positions obtained through linear interpolation deteriorates
Solution Approach 1:
The patent changes the mathematical model from linear interpolation to quadratic curve fitting, transforming the parameters used for position calculation. This allows accurate prediction of web paper edge positions using only three sensors, resolving the contradiction between reduced sensor quantity and maintained positioning accuracy.
Solution Approach 2:
The patent replaces the mechanical approach of using multiple physical sensors with a computational approach using quadratic curve fitting algorithms. This substitution allows the system to achieve the same measurement precision with fewer physical components, directly addressing the contradiction.
2Device complexity
If linear interpolation is used with reduced sensors, then the apparatus construction is simplified, but print quality deteriorates due to inaccurate position correction
Solution Approach 1:
The patent transforms the position calculation method from simple linear interpolation to quadratic curve fitting, changing the mathematical parameters used for prediction. This enables accurate print position correction even with simplified sensor arrangement, resolving the contradiction between construction simplicity and print quality.
Solution Approach 2:
The patent implements a feedback mechanism where the quadratic curve model continuously predicts web paper edge positions based on sensor data, and this predicted information is fed back to adjust print head positioning. This feedback loop maintains high print quality despite reduced sensor complexity.
Data Source
AI summary
A printing apparatus for printing on an elongate printing medium includes the following elements: a transport mechanism for transporting the printing medium; a printing unit including a plurality of print heads arranged at intervals in a transport direction; a detecting unit including at least three detectors arranged as spaced from one another for detecting positions in a width direction of the printing medium; a variation history acquirer for deriving, for each detection cycle, a function approximate curve based on positions of the same location in the transport direction of the printing medium detected by the respective detectors, and acquiring from each function approximate curve, and as a variation history, a deviation amount in the width direction in each of the printing positions; a predicted position calculator for calculating, from the variation history, a predicted position in the width direction for each of the printing position; and a printing controller for printing while correcting the position based on the predicted position.