Inkjet Actuator Barrier Layer Crack Protection
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Solution Overview
Problem
Conventional liquid jetting apparatuses, such as ink-jet heads, face the risk of electric short-circuit between individual electrodes and a common electrode due to ink penetration through cracks in the ceramics layer of the actuator unit, which can lead to jetting failure.
Innovation Solution
Incorporating a barrier layer between the contact surface and the individual electrodes closest to the contact surface, positioned differently from the outer surface, to prevent ink penetration and ensure the barrier layer is not flawed during manufacturing, thereby blocking ink from reaching the electrodes and preventing short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive protection film is formed on the joint surface of the actuator unit to prevent ink penetration, then the risk of electric short-circuit is reduced, but the protection film is likely to be flawed in manufacturing processes and ink can still penetrate through cracks
Solution Approach 1:
A barrier layer is introduced as an intermediary component between the ceramics layer and the individual electrodes. This barrier layer serves as a mediator that blocks ink penetration paths, preventing ink from reaching the electrodes even when the ceramics layer has cracks or the protection film is flawed. The barrier layer is integrated into the actuator unit structure and positioned to cover potential crack paths.
Solution Approach 2:
The barrier layer is formed on the ceramics layer before the individual electrodes are applied. This preliminary action ensures that the barrier layer is in place to prevent ink penetration before the electrodes are positioned, creating a pre-protective structure that addresses potential crack issues before electrode placement.
2Reliability
If the barrier layer is positioned at the contact surface to prevent ink penetration, then electrode protection is improved, but the barrier layer may be flawed during manufacturing processes
Solution Approach 1:
The barrier layer is positioned at a different location (different dimension) from the outer contact surface. Specifically, it is placed between the ceramics layer and the individual electrodes, not at the exposed contact surface. This dimensional repositioning allows the barrier layer to be protected from manufacturing flaws that affect surface layers while still effectively blocking ink penetration paths to the electrodes.
3Productivity
If the actuator unit uses a ceramics sintered compact for actuation, then jetting performance is achieved, but the ceramics layer easily suffers minute cracks during firing or driving
Solution Approach 1:
The barrier layer is applied beforehand to the ceramics layer to cushion against the harmful effect of ink penetration. Even when the ceramics layer develops cracks during firing or driving, the pre-applied barrier layer catches and blocks ink, preventing it from reaching the electrodes and causing short circuits. This beforehand protection compensates for the inherent brittleness of the ceramics material.
4Reliability
If a conductive protection film is fired after application to prevent ink charging, then electrical protection is improved, but the fired protection film may develop flaws that allow ink penetration
Solution Approach 1:
The barrier layer serves as an intermediary protective layer that is integrated into the actuator unit structure, positioned between the ceramics layer and the individual electrodes. Unlike the external conductive protection film that is applied and fired separately, the barrier layer is part of the internal structure and provides continuous protection without being subject to the same manufacturing flaw issues.
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
The barrier layer effectively prevents ink from penetrating to the individual electrodes, avoiding electric short-circuits and enhancing the reliability of the liquid jetting apparatus even when the ceramics layer has cracks, thus ensuring stable operation.
Implementation Method 1
a barrier layer preventing the liquid from penetrating therethrough are stacked
Implementation Method 2
When voltage is applied between the individual electrode and the common electrode of the actuator unit to drive the active portion, the actuator unit deforms to change the volume of the pressure chamber
Data Source
AI summary
A liquid jetting apparatus includes: a cavity unit having a plurality of nozzles and pressure chambers; and an actuator unit applying jetting pressures to the pressure chambers. The actuator unit has a plurality of stacked ceramics layers, individual electrodes corresponding to the pressure chambers, a common electrode common to all the pressure chambers, and a barrier layer preventing the liquid from being penetrated therethrough. The barrier layer is stacked on a position which is between a contact surface, of the actuator unit, making contact with the cavity unit and the individual electrodes closest to the contact surface, except a position on the contact surface. It is possible to prevent the individual electrodes and the common electrode from being electrically short-circuited due to the liquid even when the ceramics layer in contact with the cavity unit has a crack.