Ink Ejection Control via Humidity Feedback and Preliminary Purge
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Solution Overview
Problem
Existing liquid ejection apparatuses face challenges in maintaining optimal ink viscosity and density in nozzles, leading to image quality deterioration and unstable ink ejection due to excessive humidification, which requires precise control of humidity levels.
Innovation Solution
A liquid ejection apparatus that supplies humid air into the ejection space to maintain appropriate ink viscosity and density, performing preliminary ejections to discharge low-density ink and adjust the ejection amount based on humidity differences and elapsed time, while efficiently managing the sealed and unsealed states of the ejection space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high humidity air is supplied to humidify the ink in nozzles, then the ink viscosity is reduced and ejection stability is improved, but the ink density decreases and image quality deteriorates
Solution Approach 1:
The system performs preliminary ejection of ink before actual recording to remove excessively humidified low-density ink from the nozzles. This preliminary action ensures that only ink with appropriate density and viscosity remains in the nozzles for subsequent recording, thereby resolving the contradiction between ejection stability and image quality.
Solution Approach 2:
The system measures the density of ink in the nozzles using a density measurement unit and provides feedback to the control unit. Based on this feedback, the control unit adjusts the humid air supply amount and performs preliminary ejection only when necessary, preventing both excessive humidification and unnecessary ink waste, thus maintaining both ejection stability and image quality.
2Stability of the object's composition
If humid air supply is increased to prevent ink thickening, then ink viscosity is maintained, but ink density decreases and more ink is wasted
Solution Approach 1:
The density measurement unit continuously monitors ink density in the nozzles and provides feedback to the control unit. The control unit adjusts the humid air supply amount based on actual density measurements, supplying humid air only when and to the extent that ink thickening occurs. This prevents unnecessary humidification and associated ink waste while maintaining ink viscosity stability.
Solution Approach 2:
The system performs preliminary ejection before recording to discharge low-density ink that has been excessively humidified. This preliminary action removes wasted ink before it affects recording quality, and the control unit optimizes the timing and amount of preliminary ejection based on density feedback, thereby reducing overall ink consumption.
3Manufacturing precision
If preliminary ejection is performed to remove low density ink, then appropriate density ink is achieved, but ink consumption increases
Solution Approach 1:
The control unit decides whether to perform preliminary ejection based on density feedback from the measurement unit. Preliminary ejection is executed only when the measured ink density is below the appropriate threshold, and the ejection amount is optimized based on the degree of density deviation. This feedback-based selective preliminary ejection achieves precise ink density control while minimizing unnecessary ink waste.
4Reliability
If accurate humidity adjustment is implemented to optimize ink properties, then ejection stability and image quality are improved, but control complexity increases
Solution Approach 1:
The system uses a density measurement unit to directly measure ink density in the nozzles and provides feedback to the control unit. This simple density-based feedback mechanism replaces complex humidity sensing and adjustment systems, enabling the controller to make straightforward decisions about humid air supply and preliminary ejection timing, thereby achieving reliable ink ejection without excessive control complexity.
Solution Approach 2:
Instead of directly controlling and measuring humidity parameters which would require complex sensors and control mechanisms, the system measures ink density as a proxy parameter that reflects the combined effect of humidity on ink properties. This parameter change from direct humidity control to density-based indirect control simplifies the control system while maintaining effective ink property optimization.
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 allows for reliable ejection of ink with appropriate density and viscosity without excessive thickening, reducing unnecessary ink consumption and maintaining image quality by accurately managing ink humidity and ejection amounts.
Implementation Method 1
the humid air supplied into the ejection space such that the liquid in the ejection openings is excessively humidified
Data Source
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AI summary
A liquid ejection apparatus, including: a liquid-ejection head (10) having a plurality of ejection openings (14a) and configured to eject liquid through the ejection openings to record an image on a recording medium; a sealing mechanism (40 (41,42,43),8a) configured to selectively establish (i) a sealed state in which an ejection space (S1) in which the ejection openings are open is sealed from an outside and (ii) an unsealed state in which the ejection space is not sealed from the outside; a humid-air supply mechanism (50) configured to supply a humid air into the ejection space; and a controller (1p) configured to control the sealing mechanism, the humid-air supply mechanism, and the liquid-ejection head, wherein, during the sealed state of the ejection space established by the sealing mechanism, the controller controls the humid-air supply mechanism to supply the humid air into the ejection space such that one of a density and a viscosity of the liquid to be ejected from the ejection openings becomes less than a predetermined appropriate value, and then controls the liquid-ejection head such that the liquid having an amount equal to or larger than a set amount is preliminarily ejected through the ejection openings as a preliminary ejection prior to the ejection of the liquid onto the recording medium for recording the image on the recording medium.