Liquid Ejection Head Geometry for High-Viscosity Refill Speed
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Solution Overview
Problem
Existing liquid ejection technologies face challenges in efficiently ejecting high-viscosity liquids at high frequency due to increased resistance in the liquid supply channel and inadequate refill speed, particularly in bubble-through and bubble jet methods.
Innovation Solution
A liquid ejection head design that satisfies the relation L≤H−0.4D, where D is the distance from the first opening to the second opening of the ejection port, H is the distance from the thermal energy generating element to the ejection port, and L is the distance from the element to the air bubble interface at maximum volume, optimizing the pressure chamber volume and ejection port structure to reduce resistance and enhance refill speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the distance between the electrothermal conversion element and the ejection port opening is shortened to reduce flow resistance, then ejection efficiency is improved, but the liquid supply channel height is reduced causing increased resistance and slow refilling
Solution Approach 1:
The invention changes the geometric parameters of the pressure chamber, specifically setting the width W to 5-20 μm and length L to 10-30 μm, which optimizes the chamber dimensions to reduce flow resistance while maintaining adequate refilling speed for high-viscosity liquids
Solution Approach 2:
The invention introduces a new dimensional parameter by controlling the air bubble maximum height L relative to the pressure chamber height H, establishing the relationship L≤H−0.4D to ensure the bubble does not contact the ejection port opening, thereby separating the ejection efficiency optimization from the refilling channel height constraint
2Productivity
If the electrothermal conversion element is driven at high frequency to improve productivity, then ejection frequency increases, but refilling cannot be completed in time due to high resistance in the liquid supply channel
Solution Approach 1:
The invention optimizes the pressure chamber dimensions (width W: 5-20 μm, length L: 10-30 μm) to reduce flow resistance, enabling reliable refilling even at high ejection frequencies of 24 KHz or higher
Solution Approach 2:
The invention dynamically controls the air bubble generation and contraction process within the optimized pressure chamber dimensions, allowing the system to adapt to high-frequency operation while maintaining adequate refilling speed for viscous liquids
3Adaptability or versatility
If a liquid with viscosity of 2.5 cp or above is used to meet application requirements, then liquid performance is improved, but flow resistance increases making speedy refilling difficult
Solution Approach 1:
The invention changes the pressure chamber dimensional parameters (width W: 5-20 μm, length L: 10-30 μm) to reduce flow resistance, enabling speedy refilling even when using liquids with high viscosity of 2.5 cp or above
Solution Approach 2:
The invention applies local optimization by specifically designing the pressure chamber dimensions to address the flow resistance issue in the refilling path, while maintaining the ejection port geometry needed for efficient liquid ejection
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
Enables efficient ejection of liquids with viscosities of 2.5 cp or above at high frequencies, improving ejection efficiency and refill speed while maintaining stability during high-speed printing.
Implementation Method 1
a thermal energy generating element 1 provided in a pressure chamber 5
Implementation Method 2
a bubble-through ejection method which sets a short distance, 2 μm to 8 μm, between an electrothermal conversion element and an opening portion of an ejection port
Data Source
AI summary
A liquid ejection head and a liquid ejection apparatus are capable of efficiently ejecting a liquid having a viscosity of 2.5 cp or above at high frequency. To this end, a relation L≤H−0.4D is satisfied, where D is the thickness of an ejection port plate, H is the distance from an electrothermal conversion element to the outermost surface of the ejection port plate, and L is the height of an air bubble.