Printhead Assembly MEK-Resistant Sealing and Venting
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Solution Overview
Problem
Current thermal inkjet printheads are unable to withstand the aggressive nature of MEK-based inks and fail to maintain a seal during shipping, leading to potential ink leakage.
Innovation Solution
A printhead assembly designed with a housing and ink reservoir system using materials compatible with MEK-based inks, featuring a filter and gasket for sealing and a tortuous vent path to prevent ink leakage, which includes a polypropylene and polyethylene-based ink reservoir and a stainless steel spring for maintaining back pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermal inkjet printhead materials are used with MEK-based inks, then the printhead structure is simple and cost-effective, but the printhead cannot withstand the aggressive nature of MEK and fails to maintain sealing
Solution Approach 1:
The patent employs composite material construction for the printhead assembly, combining MEK-resistant materials (such as polypropylene, polyethylene, or fluorinated polymers) for the ink reservoir and housing with traditional printhead components. This composite approach enables the printhead to withstand aggressive MEK-based inks while maintaining structural integrity and sealing performance during shipping and operation.
2Reliability
If the printhead is completely sealed to prevent leakage during shipping, then leakage prevention is improved, but air entry during normal operation may be prevented
Solution Approach 1:
The patent incorporates a removable cap or seal mechanism that is applied in advance during assembly to provide complete sealing for shipping. Before operation, the cap is removed to restore normal ink flow. This preliminary sealing action ensures leakage prevention during transport while allowing easy restoration of functionality for printing operations.
Solution Approach 2:
The printhead design transitions from a static sealed state during shipping to a dynamic operational state where the seal is selectively removed or opened. This dynamic approach allows the system to maintain complete sealing when needed for transport while enabling ink flow during printing operations, resolving the contradiction between leakage prevention and operational ease.
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 seals the printhead during shipping and prevents ink leakage, ensuring reliable operation with MEK-based inks and reducing evaporative losses, while maintaining humidity and preventing air entry.
Implementation Method 1
a gasket sealing the interface between the ink reservoir and the ink cartridge body
Implementation Method 2
The printhead assembly can also include a filter within an ink passageway leading from the ink reservoir to the nozzles, for isolating any contaminants or debris from the ejectors and nozzles
Implementation Method 3
a stainless steel spring for maintaining back pressure
Implementation Method 4
a tortuous vent path to prevent ink leakage
Data Source
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AI summary
A printhead assembly including an ink cartridge body made of a material selected from the group of materials consisting of: nylon, polyethersulfone, polypropylene, polyethylene, polyoxymethylene and other materials that are compatible with ketone, acetate and alcohol based inks, an ink reservoir disposed within the ink cartridge body and adapted to receive and contain ink, and a printhead chip provided on the ink cartridge body and in fluid communication with the ink reservoir so as to receive ink from the ink reservoir for ejection of the ink onto a print medium.