Liquid Ejection Head Shielding for Electrode Corrosion Control
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Solution Overview
Problem
The increase in heat generation and resistance of electrodes in liquid ejection heads, particularly due to the interaction with temperature control fluids, leads to potential corrosion and driver IC failures, which are not adequately addressed in existing technologies.
Innovation Solution
The implementation of a shielding member made of corrosion-resistant material that covers the common electrode on the substrate, preventing direct contact with temperature control fluid and maintaining effective heat exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the common electrode is provided on both sides of the substrate to reduce resistance, then the resistance value decreases, but the electrode becomes susceptible to corrosion from temperature control fluid
Solution Approach 1:
A resin layer is introduced as an intermediary barrier between the common electrode and the temperature control fluid. This resin layer has lower thermal conductivity than the substrate, allowing it to block the corrosive fluid while still permitting sufficient heat transfer to maintain temperature control functionality.
Solution Approach 2:
The patent applies different material properties to different regions: the substrate provides structural support and electrical connectivity, while the resin layer provides localized corrosion protection specifically where the electrode contacts the temperature control fluid, without compromising overall thermal management.
2Temperature
If a temperature control fluid flow path is provided near the piezoelectric material for heat dissipation, then temperature control efficiency improves, but the risk of electrode corrosion increases
Solution Approach 1:
The resin layer serves as a protective intermediary that allows the temperature control fluid to flow adjacent to the piezoelectric material for efficient heat dissipation, while simultaneously blocking the corrosive fluid from reaching the common electrode.
Solution Approach 2:
The patent segments the functional zones: one zone allows fluid flow for thermal management near the piezoelectric material, while another zone protected by the resin layer maintains electrical functionality without corrosion exposure.
3Reliability
If the electrode area is increased to reduce resistance, then the resistance value decreases, but the device complexity increases
Solution Approach 1:
The resin layer enables the use of a simpler electrode arrangement on one side of the substrate without increasing complexity elsewhere, as the resin provides the necessary protection that would otherwise require complex multi-sided electrode configurations.
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
Prevents electrode corrosion and reduces the risk of driver IC failure, ensuring reliable operation of the liquid ejection head by isolating the common electrode from the temperature control fluid while maintaining temperature control efficiency.
Implementation Method 1
the amount of heat generated by a piezoelectric material, such as lead zirconate titanate (PZT), increases as the driving frequency increases
Implementation Method 2
it is usually necessary to provide a temperature control fluid flow path near the piezoelectric material
Implementation Method 3
temperature control fluid (e.g., cooling water) may flow over the common electrode portion
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
According to one embodiment, a liquid ejection head includes a substrate with a hole, a nozzle plate with a plurality of nozzles, and an actuator on a first surface of the substrate. The actuator has a plurality of pressure chambers aligned to the plurality of nozzles. An electrode has a first portion on the first surface of the substrate and a second portion on a second surface of the substrate. The second surface is on an opposite side of the substrate from the first surface. A manifold has a first liquid hole facing the hole in the substrate and a second liquid hole facing another portion of the substrate other than the hole. A shielding member is between the substrate and the manifold and covers the second liquid hole.