Liquid Ejection Flow Path Viscous Damping
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Solution Overview
Problem
Liquid ejection apparatuses face issues with fluctuating dynamic pressure in the liquid supply flow path, leading to uneven droplet ejection volumes and inaccurate landing, which affect image quality due to pulsation in the liquid delivery mechanism.
Innovation Solution
The apparatus incorporates a flow path configuration where the angular frequency of the liquid delivery unit and the kinematic viscosity of the liquid satisfy the condition √(ω/2ν)×a > 1, ensuring stable pressure and reduced pulsation, thereby stabilizing the ejection through ejection ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a liquid delivery mechanism such as a pump is used to feed liquid, then liquid can be supplied to the ejection ports, but pulsation occurs causing fluctuation in dynamic pressure
Solution Approach 1:
The patent changes the physical parameters of the flow path by increasing its cross-sectional area (making it wider and longer). This parameter change transforms the flow characteristics, reducing the impact of pulsation from the liquid delivery mechanism and stabilizing dynamic pressure in the ejection ports.
2Reliability
If dynamic pressure fluctuates in the liquid supply flow path, then meniscus position in ejection ports fluctuates, but this leads to varied droplet ejection volumes and color unevenness
Solution Approach 1:
By modifying the flow path parameters (increasing cross-sectional area and length), the patent reduces pressure fluctuations that cause meniscus position changes. This ensures consistent droplet ejection volumes and uniform color reproduction in the printed image.
Solution Approach 2:
The patent introduces an intermediary flow path structure between the liquid delivery mechanism and the ejection ports. This intermediate flow path acts as a buffer, smoothing out pressure variations and preventing direct transmission of pulsation effects to the ejection ports.
3Reliability
If dynamic pressure fluctuates, then ejection speed varies with respect to print medium moving speed, but this deteriorates landing accuracy and image quality
Solution Approach 1:
The patent modifies flow path parameters to stabilize dynamic pressure, which directly controls ejection speed. This ensures ejection speed remains consistent with the print medium moving speed, improving droplet landing accuracy and overall image quality.
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 effectively suppresses pressure fluctuations and meniscus displacement, resulting in consistent ejection volumes and improved image quality by maintaining the stability of ink ejection.
Implementation Method 1
a relation between an angular frequency ω of the liquid delivered from the liquid delivery unit and a coefficient of kinematic viscosity ν of the liquid and an equal diameter (a) of at least a part of the flow path satisfies √(ω/2ν)×a>1
Data Source
AI summary
An object is to provide a liquid ejection apparatus that allows suppression of a fluctuation in a pressure of a liquid in a flow path caused by a liquid delivery unit, enabling the liquid to be stably ejected through an ejection port. The liquid ejection apparatus including a liquid ejection head having an ejection port through which a liquid is ejected, a flow path configured to communicate with the ejection port, and a liquid delivery unit configured to feed the liquid to the flow path. A relation between an angular frequency ω of the liquid delivered from the liquid delivery unit, a coefficient of kinematic viscosity ν of the liquid, and an equal diameter a of at least a part of a section of an extra-head flow path in a direction normal to a direction in which ink flows satisfies √(ω/2ν)×a>1.