Inkjet Ink Circulation Layout to Reduce Shear-Induced Aggregation
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Solution Overview
Problem
Existing inkjet printing apparatuses face issues with ink aggregation due to high shear force applied during circulation, leading to potential clogging in discharge heads and filters.
Innovation Solution
The apparatus includes a circulation pump with a larger passage diameter and a replenishment pump with a smaller passage diameter, where the replenishment pump operates at a higher speed and shorter duration, reducing shear force on the ink, and incorporates a heater and deaeration unit to adjust temperature and remove bubbles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If new ink is delivered throughout the circulation unit by operations of multiple pumps (second pump and first pump), then the ink circulation path is effectively replenished, but the ink is pressurized at least twice causing great shear force that breaks down the dispersion film of particulate dispersions leading to aggregation
Solution Approach 1:
The patent extracts the harmful function of the second pump from the ink circulation path. Instead of using a second pump to deliver new ink from the replenishment tank to the circulation unit, the system uses only the first pump for this purpose. The second pump is eliminated entirely, preventing the additional pressurization and shear force that would break down the ink dispersion film and cause particulate aggregation.
Solution Approach 2:
The patent changes the operational parameters of the first pump to optimize ink delivery. By adjusting the pump's operating conditions (such as flow rate and pressure settings), the system can deliver new ink to the circulation unit with sufficient pressure to overcome gravity and fill the circulation path, while maintaining lower shear forces that preserve the ink dispersion stability and prevent particulate aggregation.
2Productivity
If the circulation pump delivers ink from the collecting tank to the supply tank, then ink circulation is maintained, but the passage diameter affects the shear force applied to the ink
Solution Approach 1:
The patent optimizes the passage diameter of the circulation pump as a key parameter. By selecting an appropriate passage diameter that is not too small, the system reduces the velocity and shear force of ink flow through the pump, preventing breakdown of the dispersion film. At the same time, the pump is designed with sufficient pumping capacity to maintain effective ink circulation from the collecting tank to the supply tank, balancing circulation efficiency with dispersion protection.
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 configuration minimizes ink aggregation, ensures sufficient ink supply, and prevents clogging, while maintaining optimal ink quality and flow.
Implementation Method 1
The circulation pump is interposed in the connecting pipe and is configured to perform a liquid-delivery operation of delivering ink from the collecting tank to the supply tank
Implementation Method 2
The replenishment pump is interposed in the replenishment pipe and is configured to perform a liquid-delivery operation of delivering ink from the replenishment tank to the connecting pipe
Data Source
AI summary
An inkjet printing apparatus includes a discharge head configured to discharge ink, a supply tank in which ink supplied to the discharge head is stored, a collecting tank in which ink collected from the discharge head is stored, a connecting pipe connecting the supply tank and the collecting tank, a circulation pump that is interposed in the connecting pipe and is configured to deliver ink from the collecting tank to the supply tank, a replenishment tank in which ink with which the supply tank is replenished is stored, a replenishment pipe connecting the replenishment tank and the connecting pipe, and a replenishment pump that is interposed in the replenishment pipe and is configured to deliver ink from the replenishment tank to the connecting pipe. A connection point of the replenishment pipe and the connecting pipe is positioned between the circulation pump and the supply tank.