Liquid Jetting Apparatus Common Electrode Trace Thickness Gradient
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Solution Overview
Problem
Conventional liquid jetting apparatuses face issues with trace thinning and excessive heating due to larger electric resistance in common electrode traces, leading to potential defects during the manufacturing process of pressure chamber formation substrates.
Innovation Solution
A liquid jetting apparatus design featuring a pressure chamber formation member with insulation film-covered pressure chambers, a cover with convex portions, and a wiring member connected to the pressure chamber formation member, where the piezoelectric layer is positioned between the insulation film and the extending portion of the second trace, ensuring reliable joining and minimizing stress on junction parts during grinding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the common electrode trace is made thinner to reduce space, then the manufacturing complexity is reduced, but the electric resistance increases leading to waveform degradation and excessive heating
Solution Approach 1:
The patent applies local quality by making the common electrode trace thickness non-uniform: thicker in regions with high current density (near piezoelectric elements) and thinner in regions with lower current density (toward the wiring member). This localized variation in trace thickness optimizes both electrical performance and space utilization, resolving the contradiction between trace thinning and reliable signal transmission.
2Volume of moving object
If the common electrode trace is made thinner to save space, then the device compactness is improved, but the electric resistance increases causing excessive heating
Solution Approach 1:
The patent implements local quality by varying the common electrode trace thickness along its length. The trace is thicker near the piezoelectric elements where current density is highest, effectively dissipating heat in critical regions. Toward the wiring member where current density decreases, the trace becomes thinner, saving space. This gradient design prevents excessive heating while maintaining compact dimensions.
3Reliability
If the individual electrode layer is formed across the step to connect electrodes, then the electrical connectivity is improved, but the trace becomes thinner than desired causing manufacturing defects
Solution Approach 1:
The patent applies segmentation by dividing the electrode connection path into two separate components: the individual electrode layer formed on the piezoelectric element surface, and the common electrode trace formed in the insulation film. This segmentation allows each component to be optimized independently - the individual electrodes maintain proper thickness for connectivity, while the common trace thickness varies appropriately along its length, avoiding the thinning problem that occurs when a single layer must cross the step.
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 the likelihood of defects in the manufacturing process by maintaining trace thickness and preventing excessive heating, ensuring stable drive signal transmission and prolonged apparatus lifespan.
Implementation Method 1
a piezoelectric layer overlapping with the insulation film and the first electrodes in the third direction
Data Source
AI summary
A liquid jetting apparatus includes: a pressure chamber formation member having first pressure chambers arranged in a first direction, and an insulation film covering the first pressure chambers; a cover which is joined to the pressure chamber formation member and has a first convex portion and a second convex portion; and a wiring member joined to the pressure chamber formation member. Each of the first convex portion and the second convex portion has a bonding surface to the pressure chamber formation member and extends in the first direction.