Liquid Ejection Head Slit Flow Paths for Accurate Resistance
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Solution Overview
Problem
Existing liquid ejection heads, such as inkjet heads, face challenges in maintaining consistent fluid resistance across pressure chambers, leading to variations in ejection performance due to differences in fluid resistance between upstream and downstream regions, which affects the accuracy and speed of ink ejection.
Innovation Solution
The design incorporates flow path substrates with specific dimensions, where the longitudinal direction of the flow path cross section is three times or more than the short side direction, enhancing the accuracy of fluid resistance by optimizing the shape and structure of the flow paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the flow path cross-sectional area is increased, then refilling speed improves, but meniscus vibration increases and ejection accuracy deteriorates
Solution Approach 1:
The flow path is designed with non-uniform cross-sectional area along its length. The cross-sectional area varies from the upstream end to the downstream end, creating different flow resistance characteristics in different sections. This allows the flow path to provide both sufficient refilling speed and controlled meniscus vibration through localized area optimization.
Solution Approach 2:
The invention changes the geometric parameter of the flow path cross-sectional area along its length. By making the cross-sectional area vary rather than remain constant, the flow resistance is optimized to balance refilling speed and ejection accuracy. The specific variation pattern (decreasing or increasing area) is selected based on the desired performance characteristics.
2Productivity
If fluid resistance varies between upstream and downstream, then pressure chamber negative pressure varies, but ejection performance consistency deteriorates
Solution Approach 1:
Different sections of the flow path are designed with different cross-sectional areas to create a progressive resistance distribution. This local variation in flow path geometry ensures that pressure is distributed more uniformly across all pressure chambers, improving ejection performance consistency while maintaining high ejection speed.
Solution Approach 2:
The flow path design extends the resistance control into the spatial dimension by varying the cross-sectional area along the flow path length. This dimensional approach to resistance distribution allows for fine-tuned pressure equalization across multiple pressure chambers, achieving both high productivity and reliability.
3Measurement precision
If the flow path cross-sectional area is decreased, then meniscus vibration is reduced, but refilling speed decreases
Solution Approach 1:
The flow path incorporates sections with different cross-sectional areas optimized for different functions. Upstream sections may have larger areas for rapid refilling, while downstream sections near the nozzle have smaller areas for vibration control. This localized optimization resolves the contradiction between refilling speed and ejection accuracy.
Solution Approach 2:
The flow path design creates a dynamic resistance profile along its length rather than a static uniform resistance. The varying cross-sectional area allows the flow path to adaptively balance refilling and ejection requirements at different locations, achieving both high speed and precision through spatially distributed resistance characteristics.
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 improves the consistency of fluid resistance, preventing variations in ejection performance among nozzles and ensuring high-speed followability and accurate ink ejection.
Implementation Method 1
a pressure chamber facing a vibration plate is deformed by deforming the vibration plate using an actuator formed of a piezoelectric body such as lead zirconate titanate (PZT)
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Provided are a liquid ejection head and a liquid ejection apparatus capable of improving accuracy of fluid resistance. According to one embodiment, the liquid ejection head includes a plurality of flow path substrates. The plurality of flow path substrates are each formed with an opening for forming a flow path and are stacked in a stacking direction. At least one of the flow path substrates includes a slit. A flow path formed by the slit has a flow path cross section in which a dimension in a longitudinal direction orthogonal to an extending direction of the slit and the stacking direction is three times or more a dimension in a short side direction along the stacking direction of the flow path substrates.