Inkjet Print Head Back Pressure via Hydrostatic Reservoir Design
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Solution Overview
Problem
Inkjet printing devices with through-flow print heads face issues of fluid leakage and waste due to loss of back pressure when operation is interrupted, leading to substantial fluid loss and increased disposal costs, especially when pressures in subtanks are not actively monitored and controlled.
Innovation Solution
A drop-on-demand inkjet printing device with a fluid circulation system comprising a main reservoir, supply buffer tank, and return manifold, where the main reservoir is connected to the supply buffer tank via a pump, establishing back pressure through hydrostatic pressure adjustments, and a lockable drain conduit to prevent fluid leakage during operation interruptions, eliminating the need for active pressure control and additional components like control valves or pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If active pressure control is implemented in subtanks to prevent fluid leakage, then fluid loss is reduced, but device complexity and cost increase due to additional control valves and pumps
Solution Approach 1:
The system uses the print head itself to generate and maintain the required back pressure through its internal flow resistance, eliminating the need for external active pressure control systems. The through-flow design creates a pressure differential that naturally prevents fluid leakage during interruptions without requiring additional control valves or pumps.
Solution Approach 2:
The invention extracts the pressure control function from the subtank system and relocates it to the print head assembly. By designing the print head with inherent flow resistance characteristics, the back pressure is generated locally where needed rather than being imposed from the reservoir side, simplifying the overall system architecture.
2Loss of substance
If active pressure monitoring and control systems are added to subtanks, then fluid leakage is prevented, but manufacturing cost increases
Solution Approach 1:
The print head's internal geometry and flow characteristics automatically generate the necessary back pressure to prevent leakage. This self-regulating mechanism eliminates expensive pressure sensors, control valves, and pump systems that would otherwise be required to monitor and maintain pressure in the subtanks.
Solution Approach 2:
The invention replaces expensive active pressure control components with a passive, geometry-based pressure generation system. The through-flow print head design uses simple structural features rather than complex mechanical or electronic components, reducing manufacturing costs while maintaining effectiveness.
3Productivity
If through-flow print head design is used to maintain back pressure, then fluid circulation is improved, but fluid leakage occurs during operation interruptions due to pressure loss
Solution Approach 1:
The system dynamically adapts to operational states by using the print head's flow resistance to maintain back pressure during active printing, while naturally preventing over-pressurization during interruptions. The through-flow design allows continuous circulation during operation but creates a pressure barrier that stops leakage when printing stops, without requiring separate control mechanisms for different states.
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
The solution effectively reduces fluid waste and maintains operational back pressure without active pressure control, ensuring efficient fluid circulation and minimizing fluid loss during interruptions, thus reducing disposal costs and simplifying device restarts.
Implementation Method 1
the main reservoir and the supply buffer tank are arranged in height with respect to the one or more nozzles such that during operation a back pressure is established at the one or more nozzles and fluid flows from the supply buffer tank through the through-flow print head to the return manifold
Implementation Method 2
The supply buffer tank is provided with at least one lockable additional conduit connecting the supply buffer tank to the main reservoir
Data Source
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AI summary
Drop-on-demand inkjet printing device (10) comprising a through-flow print head (20) having nozzles (22) and a fluid circulation system comprising a main reservoir (30), a supply buffer tank (38), a return manifold (64), wherein the main reservoir (30) is connected to the supply buffer tank (38) wherein the supply buffer tank (38) is in fluid communication with the nozzles (22) print head (20) the nozzles (22) being in fluid communication with the return manifold (38) wherein the return manifold (64) is connected to the main reservoir (30) and both are arranged in height with respect to the nozzles (22), wherein the supply buffer tank (38) is provided with a lockable conduit (56) connecting the supply buffer tank (38) to the main reservoir (30).