Inkjet Printhead Capping Station Vacuum Film Preservation
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Solution Overview
Problem
Inkjet imaging devices face challenges in maintaining the low viscosity of ink at the nozzles, especially with quickly drying inks that can adhere to the nozzles and become clogged, even when the printhead is covered, due to solvent evaporation in the enclosed cap space.
Innovation Solution
A capping station with a receptacle and vacuum system that forms a film with ink from the nozzles between a planar member and the printhead faceplate, using a slight vacuum to prevent evaporation and maintain low viscosity, comprising a receptacle with a seal, a vacuum source, and actuators to move the planar member and receptacle for effective ink preservation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the printhead is covered by a cap during inactivity, then the ink is protected from external contamination, but the solvent in the ink evaporates in the enclosed cap space causing viscosity increase and nozzle clogging
Solution Approach 1:
The patent introduces a saturated vapor environment within the cap enclosure to prevent solvent evaporation. The reservoir contains additional ink that evaporates to saturate the cap space with solvent vapor, creating an inert atmosphere that eliminates the concentration gradient driving evaporation from the nozzles. This resolves the contradiction by maintaining nozzle reliability while preventing substance loss through evaporation.
Solution Approach 2:
The patent changes the physical parameter of the cap enclosure from a simple closed space to a controlled vapor-saturated environment. By introducing a reservoir that maintains saturated vapor pressure, the system transforms the cap environment to prevent evaporation, thereby maintaining ink viscosity and nozzle operational status during storage periods.
2Reliability
If a simple cap enclosure is used, then the device complexity is low, but it fails to prevent ink drying and nozzle clogging
Solution Approach 1:
The patent merges the protective cap enclosure with an integrated reservoir system that generates saturated vapor. Instead of a simple cap, the enclosure combines multiple functions: physical protection, vapor generation, and moisture maintenance. This integration achieves reliable clogging prevention while managing the added complexity through functional consolidation.
Solution Approach 2:
The patent introduces a vapor reservoir as an intermediary element between the external environment and the nozzle system. This reservoir mediates the interaction by providing a controlled vapor environment that prevents direct evaporation from the nozzles, achieving protection without requiring complex active control systems.
3Loss of substance
If the cap space is completely enclosed, then evaporation is minimized, but the viscosity of ink still increases due to solvent loss in the enclosed space
Solution Approach 1:
The patent creates an inert vapor atmosphere within the cap enclosure by introducing a reservoir that evaporates solvent to saturate the enclosed space. This saturated vapor environment eliminates the concentration gradient that drives evaporation from the nozzles, thereby preventing both substance loss and viscosity increase. The inert atmosphere maintains ink composition stability while minimizing evaporation.
Solution Approach 2:
The system uses the ink itself from the reservoir to generate the protective vapor atmosphere. The solvent in the reservoir evaporates to create the saturated environment, meaning the system uses its own components to prevent the harmful effect, eliminating the need for external humidity control mechanisms.
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 maintains the low viscosity of ink at the nozzles during printhead inactivity, preventing clogging and ensuring operational readiness upon resumption of printing, thereby extending the operational status of inkjets.
Implementation Method 1
operating a vacuum source with a controller to apply a slight vacuum to the volume enclosed by the printhead faceplate, the at least one wall, and the floor
Data Source
AI summary
A capping station is configured for storing printheads during printer inactivity to preserve the viscosity of the ink in the nozzles of the printheads. Each capping station has a receptacle, a planar member having a shaft that moves bidirectionally within an opening in a floor of the receptacle, a source of cleaning fluid, and a vacuum source. A controller is operatively connected to actuators to move the receptacle so a seal on an upper wall of the receptacle engages a printhead housing and to move the planar member within the receptacle. The controller also operates a pump to move cleaning fluid through the receptacle and to operate the vacuum source to pull ink from the nozzles of a printhead to the faceplate of the printhead. The planar member is moved proximate the faceplate so the ink forms a film that preserves the viscosity of the ink in the nozzles.