Liquid Ejecting Head Cavities with Hydrophobic Porous Coating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Liquid ejecting heads, such as ink jet recording heads, face challenges in maintaining favorable ejection properties over time due to ink evaporation, which increases viscosity and affects ejection performance.
Innovation Solution
The design includes nozzles, pressure generation chambers, a manifold substrate, a piezoelectric element housing unit, and cavities that are fluidly connected to the atmosphere through specific channels to control pressure fluctuations and prevent evaporation, maintaining a humid environment within the cavities to reduce ink viscosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the cavity is open to the air to keep pressure constant, then pressure stability is improved, but ink evaporation increases causing viscosity rise
Solution Approach 1:
A hydrophobic porous coating is applied to the cavity surface to act as an intermediary layer. This coating allows pressure equalization while blocking ink evaporation by creating a barrier that prevents vapor transmission, thus resolving the contradiction between pressure stability and evaporation prevention
Solution Approach 2:
The hydrophobic porous coating creates an inert environment within the cavity by preventing air-ink interaction. The coating's water-repellent properties establish a protective atmosphere that eliminates evaporation while maintaining pressure equilibrium with the external environment
2Loss of substance
If channel resistance is increased to prevent evaporation, then evaporation is reduced, but pressure equalization capability deteriorates
Solution Approach 1:
A hydrophobic porous coating is applied to the cavity surface, creating a material structure with controlled porosity. The porous structure allows gas permeability for pressure equalization while the hydrophobic properties block liquid and vapor transmission, preventing evaporation without compromising pressure regulation
Solution Approach 2:
The surface properties of the cavity are modified by applying a hydrophobic coating, changing parameters such as surface energy and wettability. This parameter change enables the cavity to simultaneously achieve evaporation prevention and pressure equalization without increasing structural complexity
3Reliability
If ink viscosity is increased to improve ejection properties, then ejection performance is improved, but evaporation resistance deteriorates
Solution Approach 1:
The evaporation prevention function is extracted from the ink formulation and transferred to the cavity surface coating. This allows the ink to maintain optimized viscosity for ejection while the hydrophobic porous coating independently provides evaporation protection, decoupling the two previously conflicting requirements
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 prevents ink evaporation, maintaining stable ejection properties over a long period and ensuring consistent printing performance.
Implementation Method 1
A piezoelectric element forces ink out of the nozzles by causing the pressure within the pressure generation chambers to change
Implementation Method 2
a vibrating element for absorbing pressure changes in the liquid within the manifolds
Implementation Method 3
there are thus situations where the water content within the ink evaporates from the cavity and causes a rise in the viscosity of the ink
Data Source
AI summary
A liquid ejecting head includes nozzles for ejecting liquid; pressure generation chambers, each in fluid communication with one of the nozzles; and a manifold substrate with manifolds disposed therein. Each manifold supplies liquid to at least one of the pressure generation chambers. The liquid ejecting head also includes a head case with a piezoelectric element housing unit. Piezoelectric elements, for changing pressure of liquid within the pressure generation chambers, are provided in the piezoelectric element housing unit. The liquid ejecting head also includes a vibrating element for absorbing pressure changes in the liquid within the manifolds, cavities provided on the vibrating element at positions that correspond to positions of the manifolds, and an atmosphere exposure channel that fluidly connects one of the cavities to the atmosphere. At least one other one of the cavities is in fluid communication with the atmosphere exposure channel via the first cavity.