Inkjet Printing Apparatus Ink Circulation Control
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Solution Overview
Problem
Inkjet printing apparatuses face issues with defective ejection and wasteful ink consumption due to ink thickening in the print head's circulation path, which cannot be fully resolved by preliminary ejection operations alone, leading to inefficient printing and ink usage.
Innovation Solution
The apparatus employs a circulation system with a negative pressure control unit and a circulation pump to maintain optimal ink flow rates, preventing ink thickening by continuously circulating ink and recovering thickened ink back into the main tank, while calculating evaporation rates and pigment density to manage ink consumption effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ink is circulated continuously in the print head, then fresh ink is supplied to ejection ports and moisture evaporation is suppressed, but ink in the circulation path thickens gradually and preliminary ejection becomes insufficient
Solution Approach 1:
The patent extracts thickened ink from the circulation path using a suction port that draws thickened ink back to the ink supply unit, separating the problematic thickened ink from the circulation loop to prevent further degradation
Solution Approach 2:
Thickened ink is discarded from the circulation path and recovered at the ink supply unit where it can be replaced with fresh ink, preventing accumulation of thickened ink that would otherwise require preliminary ejection to resolve
2Reliability
If cleaning operation is performed uniformly regardless of ink thickening degree, then ejection reliability is maintained, but ink is consumed wastefully when thickening has not advanced
Solution Approach 1:
The system implements feedback by detecting the degree of ink thickening in the circulation path and using this information to control when cleaning operations are performed, ensuring cleaning is applied only when necessary rather than uniformly
Solution Approach 2:
The cleaning operation transitions from a static uniform approach to a dynamic conditional approach, where the cleaning intensity and frequency are adjusted based on the real-time degree of ink thickening detected in the circulation path
3Reliability
If preliminary ejection is performed to suppress ink thickening, then defective ejection is reduced, but it cannot completely recover ejection state when circulation path thickening has advanced
Solution Approach 1:
Thickened ink is extracted from the circulation path through the suction port and removed from the system, eliminating the root cause of ejection defects rather than merely attempting to recover ejection state after thickening occurs
Solution Approach 2:
The system performs preliminary cleaning by suctioning thickened ink back to the supply unit before defective ejection occurs, preventing the problem rather than just recovering from it
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 suppresses defective ejections and wasteful ink consumption by maintaining ink quality and flow, ensuring high-quality printing with reduced ink usage.
Implementation Method 1
ink is circulated along an ink channel in the print head
Implementation Method 2
performs printing by ejecting an ink from an ejection port
Implementation Method 3
moisture in the ink evaporates from the ejection port included in the print head
Data Source
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AI summary
An inkjet printing apparatus (1000) and its control method which can suppress defective ejection and wasteful ink consumption are provided. For that purpose, pigment density Nx of the ink in a circulation path is calculated, and the ink in the circulation path is discharged on the basis of the pigment density Nx.