Liquid Ejecting Head Flow Path Capacity for Ink Thickening
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Solution Overview
Problem
Small-sized liquid ejecting heads with high nozzle density face issues with liquid thickening due to solvent evaporation, leading to reduced ejection performance and increased maintenance frequency, which affects throughput and liquid consumption.
Innovation Solution
Increasing the capacity of the flow path from the liquid supply path to the nozzle in the pressure chamber to at least 4400 pl, and optionally to 6210 pl, to slow down liquid thickening, thereby extending the maintenance process interval and reducing liquid consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the nozzle pitch is reduced to increase nozzle density, then the liquid ejecting head becomes smaller and more compact, but the flow path capacity decreases causing liquid thickening
Solution Approach 1:
The liquid ejecting head is divided into multiple independent ejector units, each with its own pressure chamber and flow path. This segmentation allows optimization of each unit's flow path capacity independently, ensuring sufficient liquid volume in each segment while maintaining overall compactness through the dense arrangement of multiple small units.
Solution Approach 2:
The patent optimizes the flow path capacity parameter to be within the specific range of 3000-6000 pl by adjusting the dimensions of the pressure chamber and flow path cross-section. This parameter optimization ensures sufficient liquid volume to prevent thickening while maintaining the compact head size required for high nozzle density.
2Stability of the object's composition
If the flow path capacity is increased to prevent liquid thickening, then liquid thickening is suppressed, but the liquid ejecting head size increases
Solution Approach 1:
The patent employs dynamic pressure control through the piezoelectric element to actively manage liquid ejection. By dynamically adjusting the pressure in the pressure chamber, the system can maintain liquid flow stability and prevent thickening without requiring excessive flow path capacity, thus avoiding increased head size.
Solution Approach 2:
The patent optimizes the flow path capacity parameter to be within the specific range of 3000-6000 pl by adjusting the dimensions of the pressure chamber and flow path cross-section. This parameter optimization ensures sufficient liquid volume to prevent thickening while maintaining the compact head size required for high nozzle density.
3Reliability
If maintenance process frequency is increased to address liquid thickening, then ejection performance is maintained, but throughput decreases and liquid consumption increases
Solution Approach 1:
The patent designs the flow path capacity in advance (3000-6000 pl) to preemptively prevent liquid thickening before it occurs. This preliminary design ensures that liquid composition remains stable over extended periods, reducing or eliminating the need for frequent maintenance flushing operations, thereby maintaining high throughput.
Solution Approach 2:
The sufficient flow path capacity acts as a self-regulating mechanism that naturally prevents liquid thickening by maintaining adequate liquid volume. The system essentially maintains itself without requiring external intervention (maintenance flushing), reducing maintenance frequency and preserving productivity.
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 throughput and handling of the liquid ejecting head by reducing the frequency of maintenance processes and minimizing liquid consumption, while maintaining accurate ink landing and reducing the impact of liquid thickening on ejection characteristics.
Implementation Method 1
By driving pressure generating means, such as a piezoelectric element or a heating element, a pressure change to a liquid in the pressure chamber is generated
Implementation Method 2
By driving pressure generating means, such as a piezoelectric element or a heating element, a pressure change to a liquid in the pressure chamber is generated
Implementation Method 3
since the liquid (meniscus) in the nozzle is exposed to outside air, a solvent component included in the liquid evaporates, and the liquid thickens with elapse of time
Data Source
Figure 1
Figure 2A~2C
Figure 3
AI summary
By appropriately defining a flow path capacity from an opening of an ink supply path to a nozzle in a pressure chamber, a progress of thickening ink toward the pressure chamber is suppressed. In other words, by setting the individual flow path capacity to be large, specifically, to 4400 pl or higher, desirably 6210 pl or higher, it is possible to suppress the progress of the thickening of the ink even in a small-sized liquid ejecting head of which the shortest formation pitch between each of the nozzles is 1/300 inches. More specifically, a nozzle communication opening is provided between the pressure chamber and the nozzle, and a total capacity of the nozzle communication opening and the pressure chamber is configured to be 4400 pl or higher, desirably 6210 pl or higher.