Flow Path Substrate Inclined Walls Bubble Management
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Solution Overview
Problem
In liquid ejecting heads, gas bubbles can reside on the boundary between thick and thin wall portions of the flow path formation substrate, leading to unstable liquid supply to pressure chambers, which affects discharging performance.
Innovation Solution
The flow path formation substrate features a thick wall portion with a first inclined portion that directs gas bubbles to the end sides of individual communication paths, preventing them from residing on the boundary and ensuring stable liquid supply, while also including a second inclined portion to reduce liquid flow interference and asymmetric center lines to rectify flow variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a boundary portion is formed between thick wall portion and thin wall portion of the flow path formation substrate, then structural support is provided, but gas bubbles may reside on the boundary portion causing unstable liquid supply
Solution Approach 1:
The boundary portion is configured with an inclined surface instead of a sharp corner, creating a curved transition between thick and thin wall portions. This curved geometry prevents gas bubbles from accumulating at the boundary, while the inclined surface guides bubbles toward the liquid introduction port, thereby maintaining both structural support and reliable liquid supply.
2Productivity
If the flow path area is reduced at the individual communication path side, then liquid flow control is improved, but gas bubble accumulation risk increases at the boundary portion
Solution Approach 1:
The inclined surface at the boundary portion creates a curved flow path that directs gas bubbles away from the reduced area region toward the liquid introduction port. This curved geometry ensures that while the flow path area is reduced for better liquid control, gas bubbles are naturally guided to the wider area near the introduction port where they can be effectively removed.
3Productivity
If the flow path formation substrate has varying wall thickness, then flow path area control is achieved, but manufacturing complexity increases
Solution Approach 1:
The wall thickness of the flow path formation substrate is varied continuously along the flow path direction, with the thickness gradually changing from the liquid introduction port side to the individual communication path side. This gradual parameter change achieves precise flow path area control while avoiding abrupt transitions that would complicate manufacturing, as the continuous variation can be achieved through standard molding or machining processes.
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 configuration enhances the stability of ink discharging performance by preventing gas bubbles from obstructing the flow, improving the emission of bubbles and maintaining consistent ink supply to pressure chambers, thereby improving overall liquid discharging efficiency.
Implementation Method 1
Gas bubbles mixed in the liquid may reside on a middle portion of the boundary portion
Implementation Method 2
a liquid introduction port that introduces liquid into the common liquid chamber, and individual communication paths that individually provide communication between the individual pressure chambers and the common liquid chamber
Data Source
AI summary
A liquid ejecting head includes a pressure chamber formation substrate provided with pressure chambers that are disposed side by side and that communicate with nozzles that discharge a liquid, a nozzle plate provided with the nozzles, and a flow path formation substrate provided between the pressure chamber formation substrate and the nozzle plate. The flow path formation substrate has a plurality of individual communication paths that supply the liquid to the pressure chambers disposed side by side, a common liquid chamber that communicates with the pressure chambers, a liquid introduction port that introduces the liquid into the common liquid chamber, and a flow path of the liquid from the liquid introduction port toward the individual communication paths. The flow path formation substrate has a thick wall portion and a thin wall portion that are located at a pressure chamber formation substrate side of the common liquid chamber and that have a relatively large substrate thickness and a relatively small substrate thickness, respectively. The thick wall portion causes area of a cross-section of the flow path taken along a thickness direction of the flow path formation substrate to be smaller at an individual communication path side than at a liquid introduction port side. The thick wall portion includes a first inclined portion that, in a plan view from the nozzle plate side, is inclined from the liquid introduction port side toward at least one end side of two end sides of the plurality of individual communication paths in a side-by-side direction in which the pressure chambers are provided side by side and along which the individual communication paths are provided.