Liquid Ejection Head Partitioned Reservoir for Uniform Pressure
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Solution Overview
Problem
Liquid ejection heads face performance variations due to non-uniform pressure distribution caused by channel resistance in common liquid channels, especially with high-viscosity liquids like UV ink and solder paste, leading to degraded image quality and reduced production efficiency.
Innovation Solution
The liquid ejection head is designed with a partitioned liquid reservoir that includes a common liquid channel and a first common liquid chamber, where one inlet/outlet of the pressure chambers communicates directly with the first common liquid chamber, bypassing the common liquid channel, reducing channel resistance and ensuring uniform pressure distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common liquid channel is provided in common to each ejection port train, then liquid can be supplied to multiple pressure chambers through a single channel, but channel resistance causes non-uniform pressure distribution and variations in ejection performance
Solution Approach 1:
The common liquid channel is segmented into multiple separate liquid channels, each dedicated to a specific ejection port train. This segmentation eliminates the cumulative resistance problem of a single long channel while maintaining the benefit of a common liquid supply structure, thereby ensuring uniform pressure distribution and consistent ejection performance across all ports.
2Manufacturing precision
If ejection ports are provided at high density for high-resolution output, then image quality improves, but channel resistance increases causing non-uniform pressure distribution
Solution Approach 1:
Each ejection port train is provided with its own dedicated liquid channel with optimized local characteristics. This allows the channel dimensions and resistance to be tailored to the specific requirements of each high-density ejection port group, ensuring that pressure distribution remains uniform even when ports are densely arranged for high-resolution output.
3Reliability
If suction recovery is used to discharge bubbles, then bubble removal is achieved, but printing must be stopped and large quantities of liquid are wasted
Solution Approach 1:
The liquid circulation system enables continuous bubble removal during printing operations. Liquid is circulated through the pressure chambers via the liquid channels, continuously removing bubbles without interrupting the printing process. This maintains both high reliability through effective bubble discharge and high productivity by eliminating the need to stop printing.
4Productivity
If liquid circulates through a long common channel, then bubbles can be removed during printing, but channel resistance causes varying negative pressures on different pressure chambers
Solution Approach 1:
The circulation path is segmented into multiple separate liquid channels instead of using a single long common channel. Each channel serves specific pressure chambers, reducing the cumulative resistance and ensuring that negative pressure remains uniform across all chambers while still enabling continuous circulation for bubble removal during printing.
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 reduces channel resistance and variations in ejection performance, allowing for efficient bubble discharge during printing and maintaining high-quality image output even with high-viscosity liquids.
Implementation Method 1
The negative pressure and the capillary action of the ejection ports are balanced to hold the interface of the liquid in the ejection ports
Implementation Method 2
The pressure generated using these mechanisms causes the liquid in the pressure chamber to be ejected through ejection ports
Data Source
AI summary
A liquid ejection head includes a liquid ejection substrate and a liquid reservoir. The liquid ejection substrate includes a plurality of liquid ejection sections. The liquid ejection sections include pressure chambers configured to hold liquid and ejection ports communicating with the pressure chambers. The pressure chambers each include a pressure unit configured to apply pressure to the liquid in each of the pressure chambers. The pressed liquid is ejected through the ejection ports. The liquid reservoir is in contact with a back of the liquid ejection substrate opposite to the ejection ports. The liquid reservoir is partitioned into at least one common liquid channel and a first common liquid chamber. The common liquid channel communicates with one of inlets and outlets of the plurality of pressure chambers. The first common liquid chamber communicates with another of the inlets and the outlets.