Liquid Ejecting Head Bubble Discharge via One-Way Valves
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Solution Overview
Problem
Existing liquid ejecting head units face challenges in efficiently discharging bubbles from the manifold to the outside, leading to pressure loss and defective ink ejection, as bubbles can flow back into the pressure chamber and increase ink consumption.
Innovation Solution
Incorporating one-way valves in the bubble return flow paths to prevent backflow and using gas-permeable films to guide bubbles out of the manifold, allowing for efficient discharge of bubbles to the outside.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bubbles are stored in the bubble storage portion of the manifold, then the entry of bubbles into the pressure chamber is suppressed, but the bubbles cannot be discharged to the outside efficiently
Solution Approach 1:
The patent extracts the bubble discharge function from the storage function by providing a separate discharge path (bubble discharge port) distinct from the ink supply path. This allows bubbles to be removed from the manifold system independently while maintaining the storage function, resolving the contradiction between suppressing bubbles in the pressure chamber and enabling bubble discharge to the outside.
Solution Approach 2:
The patent introduces a gas permeable member as an intermediary between the bubble storage portion and the discharge path. This intermediary component allows selective passage of gas (bubbles) while preventing liquid (ink) from escaping, enabling efficient bubble discharge while maintaining ink containment in the manifold.
2Ease of operation
If negative pressure is applied from the nozzle opening side to draw bubbles out, then bubbles can be discharged from the manifold, but ink consumption increases
Solution Approach 1:
The gas permeable member acts as a selective intermediary that allows gas molecules to pass through while blocking liquid ink. This enables bubble discharge through the permeable member without the accompanying loss of ink that would occur with negative pressure drawing, thus resolving the contradiction between bubble discharge capability and ink consumption.
Solution Approach 2:
The patent utilizes porous or gas-permeable materials that have selective permeability properties - allowing gas molecules to pass through the material structure while preventing larger liquid molecules from passing. This material property enables bubble removal without ink loss, resolving the contradiction between discharge capability and substance loss.
3Reliability
If bubbles flow back into the pressure chamber from the manifold, then pressure loss occurs and ejection becomes defective, but preventing backflow increases system complexity
Solution Approach 1:
The patent extracts the bubble removal function by providing a dedicated discharge path separate from the main ink flow path. This separate extraction of the bubble discharge function prevents bubbles from flowing back into the pressure chamber while maintaining a relatively simple overall system structure, resolving the contradiction between ejection quality and system complexity.
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 solution effectively reduces bubble-related pressure loss and ink consumption by ensuring bubbles are discharged outside the manifold, improving ink ejection reliability and reducing the amount of ink used during the filling process.
Implementation Method 1
a bubble return flow path that communicates with the manifold and discharges bubbles inside the manifold to the outside, and a one-way valve that is provided in the bubble return flow path
Implementation Method 2
causing the bubbles to permeate the gas permeable portion and to be discharged to the outside
Data Source
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AI summary
A liquid ejecting head unit includes a drive unit for ejecting a liquid inside a pressure chamber from a nozzle opening which communicates with the pressure chamber, a common liquid chamber which communicates with a plurality of the pressure chambers, a bubble return flow path for communicating with the common liquid chamber and discharging bubbles inside the common liquid chamber, a confluence point which communicates with a plurality of the bubble return flow paths, a collective return flow path for communicating with the confluence point and discharging the bubbles inside the plurality of bubble return flow paths, and a one-way valve which is provided part way down the bubble return flow path.