Liquid Ejection Head Unit With Lever-Ratio Pressure Control
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Solution Overview
Problem
Existing liquid ejection systems face challenges in maintaining a stable negative pressure in the ejection head due to significant pressure changes, particularly in full-line heads and when using high-viscosity liquids, leading to inconsistent liquid ejection.
Innovation Solution
A pressure control mechanism with a lever ratio greater than 1 and less than 5 is implemented, comprising a pressure chamber, a lever member, a valve element, and a biasing unit, to stabilize the pressure in the ejection head by controlling the pressure chamber through a lever mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional pressure control mechanism is used, then the structure is simple, but the pressure of the pressure chamber changes largely when a large amount of liquid is supplied or high-viscosity liquid is used
Solution Approach 1:
The lever member is designed to be movable rather than fixed, allowing it to rotate about the fulcrum in response to pressure changes. This dynamic adjustment enables the valve element to automatically modulate the opening between the pressure chamber and ejection opening section, maintaining stable negative pressure despite variations in liquid supply conditions or viscosity
Solution Approach 2:
The invention optimizes the lever ratio (distance from effort to fulcrum divided by distance from load to fulcrum) to be greater than 1 and less than 5. This specific parameter range provides sufficient mechanical advantage to counteract large pressure changes in the pressure chamber while avoiding excessive complexity, thus resolving the contradiction between structural simplicity and pressure stability
2Productivity
If a large amount of liquid is supplied to the head, then the ejection capacity is improved, but the pressure of the pressure chamber changes largely
Solution Approach 1:
The pressure control mechanism operates as a feedback system where the movable lever member responds to pressure changes in the pressure chamber by rotating about the fulcrum. This rotation adjusts the valve element position, which in turn modulates the pressure chamber pressure back toward the desired range, enabling stable operation even when large amounts of liquid are supplied for high-productivity ejection
3Reliability
If high-viscosity liquid is used, then the liquid ejection quality is improved, but the pressure of the pressure chamber changes largely at the time of supply
Solution Approach 1:
The movable lever member provides dynamic pressure compensation that automatically adjusts to the increased pressure demands of high-viscosity liquid supply. By rotating about the fulcrum in response to pressure changes, the lever mechanism modulates the valve element to maintain stable negative pressure in the pressure chamber, ensuring consistent ejection quality without excessive pressure fluctuations
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
The mechanism maintains the pressure within a predetermined range, ensuring stable liquid ejection and reducing pressure fluctuations, thereby enhancing the quality and speed of printing.
Implementation Method 1
a valve provided at one end of a lever is displaced by leverage gained from a force acting on the other end (effort) and based on a pressure inside a negative pressure chamber (pressure chamber)
Implementation Method 2
a biasing unit configured to bias the valve element in a closing direction at the load of the lever member
Data Source
AI summary
A liquid ejection apparatus includes: an ejection head; a liquid reservoir; and a pressure control mechanism controlling a pressure of liquid supplied from the liquid reservoir and supplying the ejection head with liquid, the pressure control mechanism including a pressure chamber with the ejection head, a lever member connected to the valve element at a load and connectable to a pressure receiving member for a pressure of the pressure chamber at an effort, and a biasing mechanism biasing the valve element at the load of the lever member, the pressure control mechanism controlling a pressure of the pressure chamber. In the pressure control mechanism, a lever ratio, which is a ratio of a distance between the effort and fulcrum of the lever member to a distance between the load and fulcrum of the lever member, is greater than 1 and less than 5.