Printhead Priming via Pressure Vent Cycle
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Solution Overview
Problem
Inkjet printers face issues with air entering the printhead assembly during ink reservoir depletion and refilling, which impedes ink flow and requires effective management to minimize adverse effects on printing.
Innovation Solution
A pressure/vent cycle technique is implemented, using a suitable pressure source to pressurize the ink supply container, pushing ink into the printhead assembly and then venting to draw froth back into the container, with a pressure difference of at least 25 inches of water to ensure complete ink filling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If ink is supplied from a discrete ink supply reservoir separate from the printhead assembly, then the ink supply system can be modular and refillable, but air may enter the printhead assembly when the reservoir is replaced or refilled, impeding ink flow
Solution Approach 1:
The patent extracts and removes air from the printhead assembly using a pump system that actively抽s air out through dedicated air removal passages, separating the air removal function from the ink supply function to prevent air from impeding ink flow
Solution Approach 2:
The patent introduces an intermediary pump system that mediates between the ink supply reservoir and the printhead assembly, controlling fluid flow and actively managing air removal to prevent air from entering the printhead during reservoir replacement or refilling operations
2Productivity
If pressure is applied to push ink into the printhead assembly, then ink filling is accelerated, but froth may be generated and trapped in the printhead assembly
Solution Approach 1:
The patent employs periodic pressure cycling where pressure is applied in pulses to push ink into the printhead assembly, followed by pressure release periods that allow froth to rise and be removed through air removal passages, repeating this cycle until the printhead is properly filled
Solution Approach 2:
The patent converts the harmful effect of froth generation during pressure-driven ink filling into a beneficial process by designing air removal passages that allow the froth to rise and be actively pumped out, transforming the froth from a problem into an indication that the printhead is being filled
3Reliability
If air is removed from the printhead assembly using a pump, then ink flow is improved, but the device complexity increases
Solution Approach 1:
The patent designs the pump system to perform multiple functions: it not only removes air from the printhead assembly but also can supply ink to the printhead and manage fluid levels in the reservoir, reducing the need for separate dedicated components for each function
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 method effectively removes froth from the printhead assembly, allowing for complete ink filling and ensuring uninterrupted printing operations by maintaining a sufficient pressure differential to pull froth into the ink reservoir.
Implementation Method 1
a suitable pressure source is operatively connected to a liquid supply container to pressurize the container to push liquid from the container through a liquid port into the printhead assembly
Implementation Method 2
The pressurized container is then vented under conditions sufficient to draw froth from the printhead assembly through the liquid port into the container
Data Source
AI summary
In one example, a liquid dispensing device includes a printhead assembly having a liquid port through which liquid may move between a removable liquid container and the printhead assembly and an air port through which air may flow to and from the container. A pressure source is operatively connected to the air port to pressurize the container to push liquid from the container through the liquid port into the printhead assembly. A vent is operatively connected to the air port to vent the pressurized container to draw froth from the printhead assembly through the liquid port into the container. In another example, a method for priming a printhead assembly includes pushing liquid from a container into the printhead assembly through a liquid port and then pulling froth from the printhead assembly into the container through the liquid port.