Inkjet Printing Duty Control for Bronzing Suppression
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Solution Overview
Problem
Inkjet printers using pigment ink face the challenge of bronzing phenomenon, which degrades image quality due to discoloration from reflected light, and existing solutions like lamination or overcoating with yellow ink affect color reproducibility and increase costs or complexity.
Innovation Solution
An image processing method that converts input image data into ink color data for achromatic inks with varying resin densities, adjusting printing duties for multiple scans to minimize bronzing while maintaining color reproducibility, using a combination of first and second achromatic inks with different densities to manage pigment and resin distribution on the printing medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lamination with transparent film is performed to suppress bronzing phenomenon, then bronzing is reduced, but apparatus cost and process complexity increase
Solution Approach 1:
The patent extracts the protective function from a separate lamination process and integrates it into the printing process itself by using a clear coat ink that forms a protective layer during normal printing operations, eliminating the need for additional lamination equipment
Solution Approach 2:
The patent introduces a clear coat ink as an intermediary substance between the pigment ink and the printing medium surface, which acts as a protective layer to suppress bronzing without requiring mechanical lamination equipment
2Object-affected harmful factors
If overcoating with yellow ink is performed to suppress bronzing, then bronzing is reduced, but color reproducibility deteriorates
Solution Approach 1:
The patent changes the parameter of ink color from yellow (which causes color shift) to clear/transparent (which does not affect color), while maintaining the protective function against bronzing through the clear coat's optical properties
Solution Approach 2:
The patent uses a clear coat ink that is transparent rather than yellow, fundamentally changing the color parameter from one that interferes with color reproduction (yellow) to one that preserves it (transparent), while still achieving bronzing suppression
3Object-affected harmful factors
If clear coat ink is applied in all scanning passes, then bronzing is suppressed, but productivity decreases due to increased printing passes
Solution Approach 1:
The patent segments the clear coat application into specific scanning passes rather than applying it uniformly across all passes, dividing the printing process into passes that require clear coat and passes that do not, thereby optimizing both protection and efficiency
Solution Approach 2:
The patent applies clear coat ink partially rather than excessively in all passes, using it only where and when needed to suppress bronzing without unnecessarily increasing the total number of printing passes
Data Source
AI summary
An image processing method includes the steps of converting input image data to ink color data corresponding to each amount of a plurality of colors of achromatic inks used for printing, and generating printing data for first, second and third achromatic inks based on the ink color data. The printing data is used for printing by causing a printing head to scan a common image area in a printing medium a plurality of times, the printing head ejecting the plurality of colors of inks. The converting step converts the input image data to ink color data for the first, second and third achromatic inks so that the first achromatic ink is used with respect to a value of the input image data indicating achromatic color, and the generating step generates the printing data for the first, second and third achromatic inks so as to (a) make a printing duty for the first achromatic ink during first half of the plurality of scans higher than a printing duty for the first achromatic ink during the latter half of the plurality of scans, and (b) make printing duties for the second and third achromatic inks during the latter half of the scans higher than in the first half of the scans.