Pressure Control Unit Liquid Retention Reduction
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Solution Overview
Problem
In liquid ejection heads, cleaning liquid can remain in the gap between the pressure receiving plate and the flexible member, leading to increased humidity and potential substrate corrosion during packaging.
Innovation Solution
A pressure control unit with an internal flow passage extending between the pressure receiving plate and the flexible member, designed to reduce liquid retention by forming recesses or protrusions on the pressure receiving plate that minimize contact with the flexible member, allowing for efficient discharge of cleaning liquid during drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressure receiving plate is placed on the inner surface of the flexible member to control pressure, then pressure control function is improved, but cleaning liquid remains in the gap between them causing humidity increase and substrate corrosion
Solution Approach 1:
The patent extracts the harmful cleaning liquid from the gap between the pressure receiving plate and flexible member by introducing a discharge flow passage. This passage allows the cleaning liquid to be actively removed during the drying process, preventing it from remaining in the boundary portion and causing substrate corrosion while preserving the pressure control function.
Solution Approach 2:
The patent introduces an intermediary discharge flow passage that mediates between the gap where cleaning liquid accumulates and the external environment. This intermediary structure enables controlled removal of the harmful liquid without disrupting the pressure receiving plate's contact with the flexible member, thus maintaining pressure control while eliminating corrosion risk.
2Manufacturing precision
If the pressure receiving plate contacts the flexible member to open/close the flow inlet, then valve control precision is improved, but cleaning liquid retention in the boundary gap increases
Solution Approach 1:
The patent segments the boundary portion between the pressure receiving plate and flexible member by introducing a discharge flow passage. This segmentation creates a dedicated liquid discharge path that separates the valve control function from the liquid retention problem, allowing precise valve control to be maintained while enabling effective removal of cleaning liquid through the separate discharge channel.
Data Source
AI summary
To reduce the amount of a liquid that remains in a boundary portion between a pressure receiving plate and a flexible member. Provides is a pressure control unit including a pressure chamber configured, at least a part of a wall forming the pressure chamber being formed of a flexible member; a flow inlet; a flow outlet; a pressure receiving plate, which is provided on an inner surface of the flexible member, and is to be displaced toward an inner side and an outer side of the pressure chamber; a valve member configured to open and close the flow inlet in accordance with the displacement of the pressure receiving plate; and an internal flow passage, which extends in a boundary portion between the pressure receiving plate and the flexible member along the inner surface of the flexible member, and is opened on a side surface of the pressure receiving plate.