Inkjet Printer Head Dot Density Control for Edge Color Shift
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Solution Overview
Problem
Inkjet printers face issues with ink droplet landing positions shifting, leading to unintended colors appearing at the edges of printed images due to variations in ink droplet discharge, which affects printing quality, especially when printing images with contrasting lightness levels.
Innovation Solution
A printing apparatus and method that adjust ink discharge control by modifying the number of dots per unit area in boundary regions between images of different lightness levels, using specific ink discharge control to reduce the number of dots or increase dot size to prevent color shifts and maintain image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ink droplets are discharged to form dots at image edges, then printing coverage is achieved, but landing position shifts cause unintended colors to appear
Solution Approach 1:
The patent applies different dot formation strategies to different regions: at image edges, it uses fewer dots or larger dots with adjusted lightness, while in normal regions it maintains standard dot density. This local differentiation prevents color shifts at edges without compromising overall image quality.
Solution Approach 2:
The patent changes physical parameters of ink dots at image edges by adjusting either the number of dots (reducing dot count) or the dot size (increasing dot diameter), and modifies ink lightness to compensate. These parameter changes address landing position shifts while maintaining visual fidelity.
2Manufacturing precision
If dot density is increased to improve image quality, then printing resolution is enhanced, but landing position shifts become more problematic at boundaries
Solution Approach 1:
The patent implements region-specific dot formation control where boundary regions receive specialized treatment with adjusted dot density and size, while normal regions maintain high dot density for resolution. This ensures both high overall resolution and reliable boundary accuracy.
3Manufacturing precision
If ink discharge is controlled to reduce dots per unit area, then color shift is prevented, but image density may be reduced
Solution Approach 1:
The patent compensates for reduced dot density by adjusting ink lightness parameters and selecting appropriate dot sizes. This maintains color accuracy and visual density despite using fewer dots, preventing both color shifts and image thinning.
Data Source
AI summary
A printing apparatus includes a head that discharges ink droplets, and a control unit that performs discharge control of the head. When printing a boundary region formed by an end portion of a first image and an end portion of a second image that is lighter than the first image, in discharge control of a specific ink, among a plurality of inks for printing the end portion of the first image, that exhibits lightness, when forming the end portion of the first image, lower than lightness of the end portion of the second image by a predetermined value or more, the control unit performs specific ink discharge control to cause a number of dots per unit area constituting the end portion of the first image to be smaller than a number of dots per unit area constituting a normal portion, of the first image, that is adjacent to the end portion of the first image.