Common Electrode With Through Holes for Inkjet Head Reliability
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Solution Overview
Problem
The existing ink-jet heads face issues with electrical reliability due to cracks in the piezoelectric body caused by foreign matter during the manufacturing process, leading to potential short circuits when voltage is applied, especially when individual electrodes corresponding to multiple pressure chambers are coupled.
Innovation Solution
The design includes a piezoelectric body with individual electrodes and a common electrode configuration where the common electrode has through holes and protrusions to prevent electrical fields between the electrodes, reducing the likelihood of short circuits and enhancing electrical reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If individual electrodes corresponding to multiple pressure chambers are coupled together to function as one electrode, then sufficient ink discharge from multiple chambers is achieved, but the risk of short circuit between the coupling portion and common electrode increases due to potential cracks in the piezoelectric body
Solution Approach 1:
The patent introduces a third dimension (stacking direction) to separate the coupling portion of individual electrodes from the common electrode. By forming through-holes in the common electrode at positions overlapping with the coupling portions in the stacking direction, the patent creates spatial separation that prevents short circuits while maintaining the electrical coupling function for simultaneous ink discharge from multiple pressure chambers.
2Volume of moving object
If the common electrode is positioned to overlap with individual electrodes in the stacking direction, then compact design is achieved, but electrical fields between the electrodes may cause short circuits when cracks occur in the piezoelectric material
Solution Approach 1:
The patent extracts the problematic electrical field interaction by removing the overlapping region between the common electrode and individual electrodes in the stacking direction. Through-holes are formed in the common electrode at these overlapping positions, effectively taking out the source of electrical field interference while preserving the necessary compact design.
Solution Approach 2:
The through-holes in the common electrode act as intermediaries that allow the individual electrodes to pass through without creating harmful electrical field interactions. This intermediary structure enables the common electrode to maintain its grounding function while preventing direct electrical field coupling with the individual electrodes.
3Ease of manufacture
If foreign matter is present during the joining of actuator unit to channel unit, then manufacturing defects occur, but pressure applied during joining cannot escape, easily cracking the piezoelectric body
Solution Approach 1:
The patent performs preliminary action by forming through-holes in the common electrode before the joining process. These through-holes are positioned to overlap with the coupling portions of individual electrodes, creating pressure release paths that prevent crack formation during the subsequent joining of the actuator unit to the channel unit.
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 inhibits short circuits and improves the electrical reliability of the ink-jet head by preventing electrical fields between the individual electrodes and the common electrode, even when cracks occur in the piezoelectric material.
Implementation Method 1
an actuator unit including a piezoelectric body in which piezoelectric material layers (ceramic sheet) are stacked
Data Source
AI summary
There is provided a liquid discharge head, including: a piezoelectric body having a plurality of piezoelectric layers stacked on top of each other in a stacking direction; individual electrodes; and a first common electrode. Each of the individual electrodes has a first portion and a second portion arranged in the first direction at an interval, and a third portion coupling the first portion with the second portion. The first common electrode includes a first extending portion as well as first protrusions and second protrusions protruding from the first extending portion. Portions of the first extending portion overlapping in the stacking direction with the third portions are formed having through holes passing through the first common electrode in the stacking direction.