Liquid Ejecting Head Multilayer Flow Path Rigidity
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Solution Overview
Problem
In liquid ejecting heads, the increased density of nozzles leads to thinner walls in communication flow paths, causing bending and crosstalk phenomena, which affect droplet ejection accuracy and stability, and residual bubbles in these paths hinder performance.
Innovation Solution
A liquid ejecting head design featuring a multilayer substrate with a communication flow path that includes a first portion with a narrower width, an insulating layer, and a second portion with a wider width, along with inclined portions to enhance rigidity and improve bubble discharge performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the density of nozzles is increased to improve liquid ejecting apparatus accuracy, then the nozzle density increases, but the walls partitioning communication flow paths become thinner and are likely to be bent by liquid pressure
Solution Approach 1:
The communication flow path is formed with a multilayer structure comprising a first flow path arrangement layer, an insulating layer, and a second flow path arrangement layer. This composite structure increases the rigidity of the communication flow path walls without increasing the overall thickness, allowing thinner walls to maintain sufficient structural strength while enabling higher nozzle density for improved accuracy.
2Measurement precision
If the wall between communication flow paths is made thinner to accommodate higher nozzle density, then the nozzle density increases, but a crosstalk phenomenon occurs where ejection from adjacent nozzles affects each other
Solution Approach 1:
The multilayer composite structure of the communication flow path provides enhanced wall rigidity, which isolates adjacent communication flow paths and prevents pressure waves from interfering with each other. This eliminates the crosstalk phenomenon while maintaining high nozzle density, ensuring stable and reliable liquid droplet ejection.
3Reliability
If the rigidity of the communication flow path wall is increased to suppress crosstalk, then the crosstalk phenomenon is reduced, but residual bubbles are more likely to remain in the communication flow path
Solution Approach 1:
The communication flow path includes an inclined portion with a wall surface that is inclined relative to the first direction. This curved/angled geometry facilitates bubble movement toward the nozzle by reducing dead zones and improving fluid flow dynamics. Bubbles are effectively carried along with the liquid flow and discharged through the nozzle, preventing residual bubble accumulation even in the rigid multilayer structure.
4Device complexity
If a straight hole shape communication flow path is used, then the structure is simple, but bubbles remain in the path and affect liquid droplet ejection
Solution Approach 1:
The communication flow path incorporates an inclined portion with a wall surface inclined to the first direction, replacing the conventional straight hole shape. This geometric modification improves bubble discharge by facilitating smooth liquid flow and preventing bubble entrapment, while the overall multilayer structure remains relatively simple to manufacture.
Data Source
AI summary
A liquid ejecting head includes a nozzle plate, a multilayer substrate, and a pressure chamber substrate. The multilayer substrate includes a communication flow path penetrating a first flow path arrangement layer, a insulating layer, and a second flow path arrangement layer. When a direction from the pressure chamber substrate toward the nozzle plate is defined as a first direction, and a direction intersecting the first direction is defined as a second direction, the communication flow path includes a first portion having a first width and a second portion having a second width in a first cross section along the first direction and the second direction, the first width is narrower than the second width, the first portion includes the insulating layer, and the communication flow path includes a first inclined portion having a wall surface inclined to the first direction between the first portion and the second portion.