CIJ Wash Valve Layout for Ink-Solvent Interface Control
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Solution Overview
Problem
Existing CIJ printers face issues with ink and solvent contamination during shutdown and startup sequences, leading to potential printer malfunction due to solvent viscosity changes and ink dripping from nozzles, which affect drop formation and synchronization.
Innovation Solution
The implementation of a CIJ printer with a solvent feed line, ink feed line junction, anti-mixing loop, and controlled valve operations to separate and remove solvent and ink flows, ensuring solvent purity and preventing contamination during shutdown and startup sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solvent flows through the ink feed line during shutdown to clean the drop generator, then the drop generator is cleaned effectively, but ink and solvent contaminate each other at the junction, causing viscosity changes and potential malfunction
Solution Approach 1:
The ink feed line is divided into two separate flow paths by introducing a wash valve. One path allows ink to flow normally to the drop generator, while the other path allows solvent to flow through the ink feed line for cleaning without mixing with the ink path. This segmentation prevents contamination while maintaining cleaning effectiveness.
Solution Approach 2:
The wash valve acts as an intermediary component that controls the flow direction of solvent through the ink feed line. By using this intermediary valve, the system can introduce solvent for cleaning purposes without causing direct mixing between ink and solvent streams, thus preventing contamination while achieving the cleaning function.
2Ease of operation
If the interface between ink and solvent is not managed during shutdown, then valve operations are simplified, but solvent viscosity changes occur and ink may drip from nozzles, affecting drop formation and synchronization
Solution Approach 1:
The wash valve is opened before the ink feed valve is closed during shutdown. This preliminary action ensures that solvent flows through the ink feed line first, establishing a clean solvent front before ink flow stops. This sequence prevents ink from remaining at the junction, thereby preventing dripping and maintaining drop formation precision without complicating valve operations.
3Reliability
If solvent is used to clean the ink system during shutdown, then ink residue is removed effectively, but solvent may be jetted from the nozzle during cleaning, causing waste and potential damage
Solution Approach 1:
The wash valve extracts the cleaning function from the normal ink feed path by creating a separate solvent flow path through the ink feed line. This allows solvent to flow through the system for cleaning without being jetted from the nozzle, as the valve configuration directs solvent flow away from the nozzle while still achieving cleaning of the ink system components.
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
Ensures solvent purity in the ink feed line, preventing printer malfunction by maintaining solvent viscosity and preventing ink dripping, thus ensuring reliable drop formation and synchronization during operation.
Implementation Method 1
a source of negative pressure, a wash valve operable to connect the ink feed line to the source of negative pressure
Implementation Method 2
A vacuum source used to draw ink through a gutter line of the drop generator is used to draw solvent out of the drop generator into a bleed line
Data Source
AI summary
A continuous inkjet printer 2 has a drop generator 16, an ink source 7, an ink feed line 17 delivering ink from the ink source 7 to the drop generator 16, a solvent source 8, a solvent feed line 35 delivering solvent from the solvent source 8 to the drop generator 16, a flush valve 37 controlling a flow of solvent through the solvent feed line 35, a source of negative pressure 24, a wash valve 40 connecting the ink feed line 17 to the source of negative pressure 24, and a controller controlling the valves 37, 40, the solvent feed line 35 and the ink feed line 17 forming a junction where ink and solvent meet at an interface, and the controller, when shutting down the printer 2, controls the wash valve 40 and flush valve 37 to draw solvent into the ink feed line 17 from the solvent feed line 35 to draw the interface along the ink feed line 17 away from the drop generator 16.