Ink Discharge Complementing Method for Printing Apparatus
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Solution Overview
Problem
Existing printing techniques require cumbersome control methods to manage ink discharge defects in nozzles, leading to white streaks in images due to clogged ink, and there is a need for a simpler method to handle defective nozzles.
Innovation Solution
A method that involves acquiring gradation data, converting it using specific rules for normal and surrounding nozzles, performing shading correction, and generating halftone discharge control data to adjust ink discharge from surrounding nozzles, allowing for a more natural image print without directly increasing ink from surrounding nozzles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of ink discharged from surrounding nozzles is increased to compensate for defective nozzles, then the white streak defect is reduced, but the control complexity increases due to the need for multiple conversion tables for different image densities
Solution Approach 1:
The patent extracts the defective nozzle's function by redirecting its discharge load to surrounding nozzles. The conversion table specifically adds the defective nozzle's gradation values to surrounding nozzles' data, effectively transferring the discharge responsibility without requiring complex multi-table systems for different density levels.
Solution Approach 2:
The patent merges the defective nozzle's discharge requirements with surrounding nozzles by combining their gradation values in a single conversion table. This consolidation allows the system to handle defective nozzles using one unified table rather than multiple density-specific tables, reducing control complexity while maintaining image quality.
2Reliability
If multiple conversion tables are prepared for different image densities to properly adjust surrounding nozzle discharge, then image quality is maintained, but the operation becomes cumbersome and time-consuming
Solution Approach 1:
The patent creates a universal conversion table that handles all image density levels simultaneously. This single table is designed to work for both light and dark images by incorporating the defective nozzle's gradation values across all density ranges, eliminating the need to switch between multiple density-specific tables and reducing processing time.
Solution Approach 2:
The conversion table is prepared in advance with pre-calculated gradation value adjustments that account for various image densities. By performing the compensation calculations beforehand and storing them in a single comprehensive table, the system avoids real-time complex calculations during actual printing, thus reducing processing time while maintaining quality.
3Device complexity
If gradation values are converted before halftone processing to compensate for defective nozzles, then the control process is simplified, but the ink discharge amount variation across nozzles increases
Solution Approach 1:
The patent applies local quality adjustment by converting gradation values specifically for nozzles adjacent to defective ones, while leaving other nozzles unchanged. The conversion table selectively modifies only the necessary nozzle gradation values based on their proximity to defective nozzles, simplifying control for affected areas without unnecessarily altering the discharge characteristics of all nozzles in the system.
Data Source
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AI summary
The conversion of the dot percentages using the first conversion table Td1 and the second conversion table Td2 is performed for the gradation data Dh by the defective nozzle corrector 95. Here, the first conversion table Td1 converts the dot percentages of the pixels Px corresponding to the normal nozzles Nn having no discharge defect by the first rate Rd1 lower than 100 %, and the second conversion table Td2 converts the dot percentages of the pixels Px corresponding to the surrounding nozzles Na located around the defective nozzle Nd by the second rate Rd2 higher than the first rate Rd1. Then, the shading correction is performed for the defect complemented gradation data Dc obtained by converting the dot percentages in this way by the shading corrector 96.