Liquid Ejection Head Titanium Oxide Film Structure
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Solution Overview
Problem
Ink jet recording heads face issues with air bubbles remaining inside the through-hole when liquids flow, leading to unstable liquid ejection properties and potential contamination, as well as adhesive issues that inhibit liquid supply due to hydrophilic and water-repellent film configurations.
Innovation Solution
A liquid ejection head with a laminated structure of titanium oxide films, where a hydrophilic film with a pure water contact angle of 40° or less covers the inner surfaces and a water-repellent film with a contact angle of 70° or more is patterned to expose the hydrophilic film inside the flow path and cover the hydrophilic film's vicinity around the ejection orifices, using atomic layer deposition for film formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a water repellent treatment is performed on the surface inside the through-hole, then liquid supply is improved, but air bubbles remain inside the through-hole and are difficult to discharge
Solution Approach 1:
The patent applies different surface properties to different locations: the through-hole surface is made hydrophilic (water-attracting) to enable air bubble discharge, while the ejection orifice surface is made water repellent (hydrophobic) to maintain liquid supply. This local differentiation resolves the contradiction by optimizing each surface for its specific function.
2Reliability
If a hydrophilic protective film is formed from the vicinity of the ejection orifice openings to the pressure chamber, then air bubble discharge is improved, but meniscus maintenance at the ejection orifice boundary becomes difficult
Solution Approach 1:
The patent uses local quality by forming a hydrophilic protective film only at specific locations (through-hole inner surface and liquid introduction flow path) while leaving the ejection orifice vicinity with water repellent properties. This selective application allows air bubble discharge where needed while maintaining meniscus stability at the ejection orifice.
3Reliability
If a hydrophilic protective film is formed on the surface inside the through-hole, then air bubble discharge is improved, but adhesive crawls up to the inside of the through-hole and liquid supply is inhibited
Solution Approach 1:
The patent applies hydrophilic protective film only to the through-hole inner surface and liquid introduction flow path, while maintaining water repellent properties at the ejection orifice and its vicinity. This localized application prevents adhesive intrusion into the through-hole while preserving liquid supply efficiency at the ejection orifice.
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 reduces air bubble retention, stabilizes liquid ejection, and prevents adhesive intrusion, enhancing the ejection performance and image quality by promoting meniscus formation and maintaining hydrophilicity and water repellency.
Implementation Method 1
a first titanium oxide film with a pure water contact angle of 40° or less; and a second titanium oxide film with a pure water contact angle of 70° or more, in which the first titanium oxide film covers a structure including inner walls of a flow path
Implementation Method 2
the second titanium oxide film has a portion that covers the first titanium oxide film at least either in a vicinity of an opening end of an ejection orifice or in a vicinity of an opening end of the liquid introduction flow path
Implementation Method 3
using atomic layer deposition for film formation
Data Source
AI summary
A liquid ejection head has at least a structure including an ejection orifice forming member having an ejection orifice for ejecting a liquid and a flow path communicating with the ejection orifice and a flow path forming substrate having a liquid introduction flow path communicating with the flow path and supplying the liquid, and includes: a first titanium oxide film with a pure water contact angle of 40° or less; and a second titanium oxide film with a pure water contact angle of 70° or more, wherein the first titanium oxide film covers the structure including inner walls of the flow path and the liquid introduction flow path and is exposed in the flow path and the liquid introduction flow path, and the second titanium oxide film has a portion covering the first titanium oxide film in a vicinity of an opening end.