Inkjet Printing With Preliminary Ink for High-Density Dot Uniformity
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Solution Overview
Problem
Inkjet printing apparatuses using UV ink face issues with nozzle variability and defects, leading to uneven printing quality, particularly in high-density areas, which conventional density and nozzle-defect corrections fail to adequately address.
Innovation Solution
The apparatus employs a two-stage ink ejection process where a second ink is applied before a first ink, increasing the wet spreading range of the first ink to enhance dot size and improve print quality in areas with defective nozzles or high-density printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional density uniformity correction and nozzle-defect correction are applied, then printing quality is improved to some extent, but the wet spreading range of ink remains insufficient in high-density areas, leading to inadequate dot size and poor print quality
Solution Approach 1:
The patent applies preliminary action by ejecting a first ink (clearance ink) before the main color ink to prepare the printing medium surface. This preliminary ink ejection modifies the surface properties to enable subsequent inks to spread more effectively, solving the problem of insufficient wet spreading range in high-density areas without requiring changes to the main printing process parameters.
Solution Approach 2:
The first ink acts as an intermediary substance between the printing medium and the subsequent color inks. By introducing this intermediate layer, the patent facilitates improved ink spreading and dot formation, particularly in high-density printing areas where direct ink ejection would otherwise produce insufficient dot size and poor quality.
2Manufacturing precision
If multiple correction processes (density uniformity correction and nozzle-defect correction) are performed, then printing uniformity is improved, but the complexity of the printing process increases
Solution Approach 1:
The patent merges multiple correction functions into a single integrated process by combining density uniformity correction, nozzle-defect correction, and wet spreading range enhancement into one unified printing operation. The first ink ejection is coordinated with subsequent color ink ejections in a single pass, eliminating the need for separate correction passes and reducing overall process complexity while maintaining high printing uniformity.
3Reliability
If ink is ejected from adjacent nozzles to compensate for defective nozzles, then dot missing is prevented, but the dot size becomes insufficient in high-density areas, resulting in poor print quality
Solution Approach 1:
The patent applies parameter changes by modifying the printing conditions in the correction area through preliminary ink ejection. The first ink alters the local printing parameters (surface wetness, ink receptivity) to enable subsequent color inks from adjacent nozzles to form adequate dot sizes even when compensating for defective nozzles. This resolves the contradiction by changing the physical state of the printing medium rather than relying solely on increased ink ejection volume.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively enhances print quality by ensuring sufficient ink coverage and uniformity, particularly in areas where single-color high-density printing is performed, addressing the limitations of conventional corrections.
Implementation Method 1
a wet spreading range of the first ink on the printing medium is larger when the first ink is ejected onto the second ink that is ejected onto the printing medium than when the first ink is directly ejected onto the printing medium
Data Source
AI summary
First, a correction area, which is a part of area where a second ink (typically, white ink) is to be ejected among the area on base material, is determined. Next, density data is corrected so that the second ink is ejected onto the correction area. Thereafter, actual printing on the base material is started. Then, the second ink is ejected onto the correction area, and a first ink (typically, color ink) is ejected onto the second ink that has been ejected onto the base material in the correction area.