Piezoelectric Actuator Electrode Design for Inkjet Head Manufacturing
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Solution Overview
Problem
The existing piezoelectric actuators for ink jet recording heads have a high manufacturing cost due to the need for multiple layers, and attempts to reduce the number of layers by eliminating the adjustment layer result in electrical disconnection issues due to silver corrosion from solder spreading on silver-based surface electrodes.
Innovation Solution
A piezoelectric actuator with an eight-layered structure is designed, featuring surface individual electrodes with slender shapes and through holes for internal electrode connections, using thermo-fusing conductive bonding materials and thickened portions to prevent electrical disconnection, allowing for a staggered pattern of electrode terminals and reduced layer count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the number of piezoelectric layers is reduced to eliminate the adjustment layer, then manufacturing cost is reduced, but electrical disconnection occurs due to silver corrosion from solder spreading on silver-based surface electrodes
Solution Approach 1:
The patent applies preliminary action by forming a protective coating layer on the surface electrodes before the soldering process. This coating layer is applied in advance to prevent silver corrosion when solder is applied, thus maintaining electrical connectivity while enabling the reduced eight-layered structure that lowers manufacturing costs
Solution Approach 2:
The patent introduces a protective coating layer as an intermediary between the silver-based surface electrodes and the solder. This intermediate layer prevents direct contact between solder and silver, eliminating the silver corrosion issue that would otherwise occur when reducing the number of piezoelectric layers
2Productivity
If electrode terminals are disposed in a staggered pattern to enable high-density wiring, then wiring efficiency is improved, but through holes must be precisely positioned immediately below electrode terminals to prevent disconnection
Solution Approach 1:
The patent applies preliminary action by forming the protective coating layer to extend along the longitudinal direction of the surface electrodes before electrode terminals are formed. This pre-formed coating provides continuous protection from the electrode base to the terminal, ensuring electrical connectivity is maintained even with precise staggered positioning of through holes for high-density wiring
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 reduces manufacturing costs while maintaining electrical connectivity and mechanical integrity, enabling efficient ink ejection by reducing the likelihood of silver corrosion-induced disconnections.
Implementation Method 1
a piezoelectric actuator attached to the cavity unit and configured to apply an ejection pressure to ink in the pressure chamber by selectively varying the cubic capacity of the pressure chamber. The piezoelectric actuator includes a common electrode and a plurality of individual electrodes alternately intervene between a plurality of piezoelectric layers
Implementation Method 2
an electrode terminal smaller than a dimension with respect to the longitudinal direction of the respective surface individual electrodes is formed on each of the surface individual electrodes, wherein the plurality of electrode terminals are disposed along the first direction to be staggered and are connectable to the respective drive side terminal electrodes through a thermo-fusing conductive bonding material
Data Source
AI summary
A piezoelectric actuator includes piezoelectric layers. Individual electrodes are formed on an outermost piezoelectric layer and arranged in a row extending along a first direction. Through holes are formed in the outermost piezoelectric layer and arranged substantially in a row extending in the first direction to contact with first end portions of the individual electrodes. The individual electrodes include at least one first individual electrode and at least one second individual electrode. The first individual electrode comprises a first electrode terminal provided at the first end portion, and the second individual electrode comprises a second electrode terminal provided at a second end portion opposite to the first end portion with respect to a second direction perpendicular to the first direction. The second individual electrode has a thickened portion extending from the second electrode terminal towards the first end portion.