Liquid Discharge Control for Multi-Pass Density Uniformity
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Solution Overview
Problem
In multi-pass printing, the pass-to-pass time difference leads to high-density streaks and inadequate reduction of density changes, as existing methods like uniformly decreasing ink ejection amounts are insufficient in addressing these issues.
Innovation Solution
A liquid discharge control apparatus and method that utilize multiple color conversion tables to adjust the number of scan operations based on pre-color conversion data, selecting the appropriate table to minimize density differences among printed colors, even when the number of scan operations changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-pass printing is performed with pass-to-pass time difference, then printing coverage is improved, but density change and high-density streaks occur
Solution Approach 1:
The patent divides the printing process into multiple passes with different ink ejection amounts. Specifically, odd-numbered passes use a first ink ejection amount while even-numbered passes use a second ink ejection amount, segmenting the overall printing operation to control density accumulation and prevent streaks.
Solution Approach 2:
The patent dynamically adjusts the ink ejection amount based on the pass number. The control unit changes the ink ejection amount between odd and even passes, creating a dynamic printing process that adapts to the cumulative density effects of multi-pass printing rather than using a static uniform ejection amount.
2Manufacturing precision
If ink ejection amount is uniformly decreased, then density change is partially reduced, but the reduction is insufficient and high-density streaks still occur
Solution Approach 1:
The patent applies different ink ejection amounts to different passes rather than uniformly decreasing for all passes. Odd passes use one ejection amount while even passes use another, creating localized quality variations in the printing process that prevent the formation of high-density streaks while maintaining overall density uniformity.
Solution Approach 2:
The control unit dynamically switches between different ink ejection amounts based on the pass number, creating a dynamic adjustment pattern that more effectively controls density accumulation compared to static uniform decrease methods.
3Manufacturing precision
If different ink ejection amounts are used for odd and even passes, then density uniformity is improved, but control complexity increases
Solution Approach 1:
The patent implements a periodic control pattern where the ink ejection amount alternates between odd and even passes. This periodic action simplifies the control logic compared to complex adaptive algorithms, as the control unit only needs to track pass parity (odd/even) to determine the appropriate ejection amount.
Solution Approach 2:
The patent changes the ink ejection amount parameter based on the pass number parity. By linking the ejection amount to a simple parameter (pass odd/even status), the control system achieves improved density uniformity without requiring complex multi-parameter control algorithms.
Data Source
AI summary
In order to reduce a density difference that appears when printing whose execution number of scan operations is changed is performed, a CPU acquires a plurality of color conversion LUTs; the CPU performs printing of each of normal portions of color patches using a reference LUT and performs printing of each of hitch portions of the color patches using a corresponding one of mutually different color conversion LUTs; the CPU allows a color patch having a small density difference to be input as a selection result; the CPU identifies a color conversion LUT corresponding to the selection result; and the CPU designates the color conversion LUT corresponding to the selection result as a color conversion LUT for the hitch portion.