Liquid Ejection Head Asymmetric Port Offset for Cavitation Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ink jet printing apparatuses face issues with cavitation on heating resistor elements, which reduces their service life and requires increased space for bubble generation chambers, limiting the density of ejection ports and resulting in a larger liquid ejection head.
Innovation Solution
A liquid ejection head design where the center of the ejection port is shifted at least L/7 towards the liquid supply port from the center of the heating resistor element, with a ratio of ejection portion length to bubble generation chamber length of l/h ≤ 2, allowing bubbles to disappear without contacting the atmosphere and reducing the load on the heating resistor element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the center of the ejection port is offset from the center of the heating resistor element to prevent cavitation, then the service life of the heating resistor element is improved, but the space required for bubble generation chambers increases
Solution Approach 1:
The patent applies asymmetry by offsetting the ejection port center from the heating resistor element center in the ink supply direction. This asymmetric arrangement causes bubbles to collapse away from the heating resistor element, preventing cavitation damage while maintaining a compact chamber design. The offset distance is specifically set to at least L/7 where L is the heating resistor element length in the ink supply direction.
Solution Approach 2:
The patent changes the offset direction from the conventional perpendicular direction to the ink supply direction. This dimensional change allows bubble collapse to occur in the ink supply direction away from the heating resistor element, preventing cavitation while maintaining compact chamber geometry and enabling high-density ejection port arrangement.
2Reliability
If the bubble break position is offset from the heating resistor element in a direction perpendicular to ink supply, then cavitation on the heating resistor element is reduced, but ejection ports cannot be arranged with high density
Solution Approach 1:
The patent uses asymmetry by positioning the ejection port center offset from the heating resistor element center along the ink supply direction. This asymmetric configuration ensures bubbles break away from the heating resistor element, providing cavitation protection while maintaining sufficient space for high-density ejection port arrangement.
Solution Approach 2:
The patent shifts the bubble break position control from the perpendicular direction to the ink supply direction. This dimensional change allows effective cavitation protection while preserving space in the perpendicular direction for arranging ejection ports with high density, thus improving productivity.
3Object-affected harmful factors
If the space for bubble generation chambers is increased to provide offset bubble break position, then cavitation effects are reduced, but the size of the liquid ejection head increases
Solution Approach 1:
The patent applies asymmetry by offsetting the ejection port center from the heating resistor element center in the ink supply direction by at least L/7. This asymmetric arrangement directs bubble collapse away from the heating resistor element, reducing cavitation effects while maintaining a compact ejection head size.
Solution Approach 2:
The patent changes the offset direction to the ink supply direction, which allows effective cavitation reduction without increasing the overall head size in the perpendicular direction. This dimensional change enables compact head design while protecting against cavitation damage.
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 design enhances the durability of the liquid ejection head by reducing cavitation effects, enabling high-resolution printing with a compact head and lower manufacturing costs.
Implementation Method 1
when the heating resistor element is driven and heats the liquid, a bubble is generated in the liquid retained in the bubble generation chamber
Implementation Method 2
bubbles are generated on the heating resistor elements, and thereby ink is ejected... cavitation occurs when bubbles generated on the heating resistor elements have become smaller and disappeared
Implementation Method 3
a bubble is generated in the liquid retained in the bubble generation chamber, and forces the liquid to be ejected, and thereafter, the bubble becomes smaller and disappears
Data Source
AI summary
A liquid ejection head in which the adverse effect of a heating resistor element due to cavitation is reduced and a printing apparatus employing this liquid ejection head are provided. When a length of a heating resistor element in a direction in which ink is to be supplied is defined by L, the center of an ejection port is shifted, at a distance equal to or longer than L/7 toward a location of an ink supply port, from the center of the heating resistor element, viewed in a direction in which ink is to be ejected. When a length of the ejection portion in the direction in which ink is to be ejected is defined as l and a length of a bubble generation chamber in the direction in which the liquid is to be ejected is defined as h, l/h is equal to or less than 2.