Inkjet Print Head Substrate Segmented Protection Layer
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Solution Overview
Problem
The existing inkjet print head substrates face a challenge in balancing the need for a thick upper protection layer to provide long life and reliability, as a thick layer makes it difficult to blow fuse elements effectively, leading to reduced reliability and potential damage from electrochemical reactions.
Innovation Solution
A substrate design featuring a first protection layer with electrical insulation properties and a second conductive protection layer, including individual sections, a common section, and connection sections that change to an insulating film via electrochemical reaction with ink, allowing for electrical separation without requiring large energy to blow fuse elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the upper protection layer is made thick to protect heating resistors from physical and chemical actions, then protection reliability is improved, but it becomes difficult to blow fuse elements effectively when short circuits occur
Solution Approach 1:
The upper protection layer is segmented into different thickness regions: a first thickness region (thicker) for protecting heating resistors from physical and chemical actions, and a second thickness region (thinner) for enabling effective fuse element blowing when short circuits occur. This segmentation allows each region to fulfill its specific function optimally.
Solution Approach 2:
Different portions of the upper protection layer are given different thicknesses to satisfy different functional requirements. The region covering heating resistors has greater thickness for protection, while the region for fuse elements has smaller thickness for easier blowing, creating local quality variation throughout the structure.
2Reliability
If the upper protection layer is made thin to enable effective fuse element blowing, then fuse element reliability is improved, but protection against physical and chemical actions is reduced
Solution Approach 1:
The upper protection layer is divided into regions with different thicknesses: thinner regions for fuse elements to ensure reliable blowing, and thicker regions for heating resistor protection. This segmentation resolves the contradiction by providing appropriate thickness in each location.
Solution Approach 2:
The protection layer exhibits local quality variation where thickness is optimized for specific functions: thinner where fuse reliability is critical and thicker where protection from physical and chemical actions is paramount.
3Reliability
If a current flows through the upper protection layer due to short circuit, then electrochemical reaction occurs between the upper protection layer and ink, but this damages the upper protection layer
Solution Approach 1:
An insulating layer is extracted and placed between the heating resistors and the upper protection layer. This insulating layer prevents current from flowing through the upper protection layer, thereby eliminating the harmful electrochemical reactions between the conductive upper protection layer and ink.
Solution Approach 2:
The insulating layer acts as an intermediary between the heating resistors and the upper protection layer, blocking the electrical current path and preventing direct electrochemical interaction between the conductive upper protection layer and the ink, thus protecting the upper protection layer from 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 configuration enhances the reliability and longevity of the inkjet print head by enabling effective separation of short circuits with reduced energy consumption and minimizing nozzle damage.
Implementation Method 1
connection sections interposed between the individual sections and the common section and connecting the individual sections and the common section, and the connection sections are disposed at positions to be in contact with ink, and include a material which changes to an electrically insulating film by an electrochemical reaction with the ink
Implementation Method 2
heating resistors near the liquid chambers wherein film boiling is caused in ink in the liquid chamber by heat generated by energizing the heating resistors
Implementation Method 3
heating resistors near the liquid chambers wherein film boiling is caused in ink in the liquid chamber by heat generated by energizing the heating resistors
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A substrate (100) for an inkjet print head (1) comprises: a base (101); a plurality of heating resistors (108) for heating ink, the heating resistors being disposed on the base and producing heat in a case where the heating resistors are energized; a first protection layer (106) disposed on the heating resistors and having insulation properties; and a second protection layer (107) disposed on the first protection layer and having conductivity. The second protection layer includes individual sections disposed to individually cover the plurality of heating resistors, a common section connecting the individual sections, and connection sections interposed between the individual sections and the common section and connecting the individual sections and the common section. The connection sections are disposed at positions to be in contact with ink, and include a material which changes to an insulating film by an electrochemical reaction with the ink.