Liquid Ejecting Head Opening Arrangement for Flow Stability
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Solution Overview
Problem
In liquid ejecting heads, the thickening of liquid near ejection orifices due to evaporation or solid components leads to increased viscosity, causing ejection speed variations and potential image formation issues, with existing solutions like forcibly flowing thickened liquid through pressure chambers resulting in flow rate and temperature distribution variations.
Innovation Solution
A liquid ejecting head design featuring an equal number of first and second openings along the ejection orifice line, with these openings positioned at both ends, to maintain bonding strength and reduce temperature distribution differences across the element substrate, thereby stabilizing the flow of liquid and preventing image unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a plurality of openings and communication orifices are provided to suppress liquid thickening, then liquid flow stability is improved, but device complexity increases
Solution Approach 1:
The supply flow passage is divided into multiple segments with separate communication orifices, allowing independent control of liquid flow to different pressure chambers. This segmentation enables suppression of liquid thickening in each segment while maintaining overall system reliability without requiring excessive complexity.
Solution Approach 2:
The openings serve multiple functions: they supply liquid to pressure chambers, enable circulation to prevent thickening, and maintain pressure balance. This multi-functionality reduces the need for separate components, thereby improving liquid flow stability without proportionally increasing device complexity.
2Temperature
If openings are positioned at both ends of ejection orifice line, then temperature distribution is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The openings are strategically positioned at both ends of the ejection orifice line in an asymmetric arrangement that optimizes temperature distribution. This positioning creates balanced thermal zones without requiring extremely tight manufacturing tolerances, as the end-positioned openings naturally anchor the temperature profile.
Solution Approach 2:
By placing openings at both ends of the ejection orifice line, the design creates equipotential zones for temperature distribution, ensuring that thermal conditions are balanced across the device. This reduces temperature gradients without demanding excessive manufacturing precision.
3Reliability
If liquid is forcibly flowed through pressure chambers, then liquid thickening is suppressed, but flow rate variations occur
Solution Approach 1:
The system dynamically adjusts liquid flow through multiple communication orifices connected to different pressure chambers, allowing each chamber to receive liquid at optimal flow rates. This dynamic flow distribution suppresses liquid thickening while maintaining consistent ejection speeds across all orifices.
Solution Approach 2:
The circulation system provides feedback control for liquid flow, where liquid that has passed through pressure chambers is returned and re-supplied through the multiple openings. This feedback mechanism maintains stable flow rates by continuously replenishing liquid and preventing thickening without causing flow rate variations.
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 design effectively suppresses liquid thickening near ejection orifices, maintains bonding strength, and reduces temperature differences, resulting in high-quality, uniform image formation by ensuring consistent liquid flow and reduced image unevenness.
Implementation Method 1
a plurality of pressure chambers that communicates with the plurality of ejection orifices, respectively
Implementation Method 2
as a volatilization component in the liquid evaporates from an ejection orifice, the liquid in the vicinity of the ejection orifice is concentrated and the viscosity of the liquid increases
Data Source
AI summary
A liquid ejecting head includes, on an element substrate, an ejection orifice line formed of a plurality of ejection orifices, a plurality of pressure chambers that communicates with the ejection orifices, respectively, a first flow passage and a second flow passage that extend along the ejection orifice line and communicate with the plurality of pressure chambers, respectively, and a plurality of first openings that communicates with the first flow passage and a plurality of second openings that communicates with the second flow passage. The number of the first openings and the number of the second openings are equal to each other and even numbers. Out of the plurality of first openings and the plurality of second openings, openings positioned at both ends in an ejection orifice line direction are either the first openings or the second openings.