Ink Recirculation via Dual Negative Pressure Tanks
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Solution Overview
Problem
Existing ink recirculation systems in printing apparatuses are limited in their ability to handle special ink formulations like ceramic inks or those with heavy particulate components, leading to unstable ink flow and potential separation of emulsion phases, and are not compatible with all print heads, resulting in suboptimal print quality and material usage.
Innovation Solution
A recirculating unit with two containers maintained under distinct negative pressures allows for controlled ink flow and pressure differences, preventing positive pressure on the ink and reducing pressure fluctuations, enabling stable ink recirculation and compatibility with various print heads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a positive pressure is applied to one tank to generate slow ink flow, then the ink flow speed can be controlled, but the meniscus stability in nozzles deteriorates and ink leakage occurs
Solution Approach 1:
The patent inverts the conventional pressure approach by applying negative pressure (vacuum) to both tanks instead of positive pressure. Tank 1 is maintained at a first negative pressure and tank 2 at a second negative pressure, creating a pressure difference that drives ink flow without compromising meniscus stability. This inversion resolves the contradiction by achieving controlled flow while maintaining reliability.
Solution Approach 2:
The patent changes the pressure parameters from positive to negative values in both tanks. By controlling the magnitude of negative pressures independently in each tank, the system achieves precise flow rate control while maintaining meniscus integrity. The pressure difference between tanks determines flow speed, while the absolute negative pressure levels maintain meniscus stability.
2Stability of the object's composition
If a large pressure difference is set between two tanks to ensure stable flow, then ink flow stability improves, but the system becomes more sensitive to print head displacement fluctuations
Solution Approach 1:
By using negative pressure in both tanks instead of a large positive pressure difference, the system achieves flow stability while reducing sensitivity to displacement fluctuations. The inverted pressure approach creates a more robust system that adapts better to print head movements.
Solution Approach 2:
The negative pressure system provides a cushioning effect that absorbs pressure fluctuations caused by print head displacement. The vacuum environment in both tanks creates a buffer that mitigates the impact of rapid accelerations and decelerations, reducing flow rate variations.
3Adaptability or versatility
If traditional recirculation system is used, then most print materials can be handled, but special ink formulations like ceramic inks or heavy particulate inks cause flow instability and phase separation
Solution Approach 1:
The patent applies negative pressure to both tanks, creating a vacuum recirculation system that handles special ink formulations stable. This inverted approach prevents the phase separation and flow instability issues encountered with traditional positive pressure systems when using ceramic inks or inks with heavy particulate components.
Solution Approach 2:
By changing from positive to negative pressure parameters, the system becomes compatible with a broader range of print materials including special formulations. The negative pressure environment maintains the stability of emulsion phases and prevents sedimentation of particulate components.
4Productivity
If two tanks are maintained at atmospheric and negative pressure respectively, then ink recirculation can be achieved, but the pressure setting becomes critical and difficult to control for slow flow rates
Solution Approach 1:
The patent inverts the pressure configuration by applying negative pressure to both tanks instead of one atmospheric and one negative pressure tank. This makes pressure setting and control much easier, as both pressures can be independently regulated in the negative range, eliminating the critical setting issues of the traditional approach.
Solution Approach 2:
By changing both tank pressures to negative values, the system gains improved controllability. The pressure difference can be precisely adjusted by controlling the vacuum levels in each tank, making it easier to achieve and maintain slow, stable flow rates for special ink formulations.
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 solution ensures stable ink flow and improved print quality by allowing precise control of ink recirculation, enabling the use of diverse print materials and heads, including those that previously experienced issues with ink leakage and separation, while maintaining meniscus stability within nozzles.
Implementation Method 1
a first recirculating device to generate a first stream of said print material from said first container toward said print head and said second container... pressure being applied to the ink in each tank in such a way to generate a pressure difference which drives the ink flow from one tank to the other
Implementation Method 2
The flow of ink along the nozzles generates by a sort of Venturi effect a depression which acts on a ink meniscus which bounds up in the nozzles due to the surface tension of the ink
Implementation Method 3
a depression which acts on a ink meniscus which bounds up in the nozzles due to the surface tension of the ink
Data Source
Figure 1
AI summary
Printing apparatus on a (not shown) print support comprising: - A print head (13) to print on said print support a print material; - A feed device (11) to feed said print material to said print head (13), and - A recirculating unit (15) to generate a recirculation of said print material through said print head (13), said recirculating unit (15) in its turn comprising: a. A first container (14) of said print material (11) placed upstream of said print head (13); b. A second container (18) of said print material, placed downstream of said print head (13); c. A first recirculating sub-unit (16) to generate a first flow of said print material from said first container (14) to said print head (13) and said second container (18); d. A second recirculating sub-unit (17) to transfer said print material from said second container (18) to said first container (14), characterized in that said first container (14) and second container (18) are both maintained under two distinct negative pressures.