Liquid Ejecting Head Electrode Segmentation for Ink Droplet Uniformity
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Solution Overview
Problem
The existing liquid ejecting heads face issues with inconsistent ink ejection characteristics due to differences in potential differences between electrodes, leading to variations in ink droplet size and shape when ejecting from multiple nozzles, as the potential differences vary based on the number of nozzles activated and their positions.
Innovation Solution
A liquid ejecting head design featuring a first piezoelectric body, a second piezoelectric body, a first electrode, a second electrode, and a third electrode, where the third electrode is electrically coupled to both piezoelectric bodies and has varying widths to minimize potential differences, ensuring consistent ejection characteristics regardless of the number of nozzles activated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a continuous upper electrode layer is used over multiple pressure chambers, then the electrode structure is simple and manufacturing is easy, but potential differences vary significantly when multiple nozzles are activated causing inconsistent ink ejection
Solution Approach 1:
The continuous upper electrode layer is divided into multiple separate electrode portions, each corresponding to a specific pressure chamber. This segmentation allows independent potential control for each nozzle while maintaining a relatively simple overall structure, resolving the contradiction between manufacturing simplicity and ejection consistency.
Solution Approach 2:
Each electrode portion is designed with specific local characteristics (separate potential control) to address the potential difference issue at each pressure chamber location. This local differentiation ensures consistent ink ejection across all nozzles while keeping the overall electrode design straightforward.
2Productivity
If all lower electrode layers are activated simultaneously, then all nozzles can eject ink, but large potential differences occur due to resistance in the upper electrode layer causing variation in droplet characteristics
Solution Approach 1:
By segmenting the upper electrode layer into multiple independent portions, each can be controlled separately. This allows simultaneous activation of multiple nozzles while maintaining uniform potential distribution across all active nozzles, eliminating the potential difference issue that occurs with a continuous electrode layer.
Solution Approach 2:
The segmented electrode structure enables each electrode portion to maintain equipotential conditions independently. When multiple nozzles are activated, each corresponding electrode portion can be controlled to have the appropriate potential, ensuring uniform droplet characteristics across all active nozzles regardless of their position.
3Manufacturing precision
If the upper electrode layer is made thinner to reduce resistance, then potential distribution improves, but electrode strength and durability decrease
Solution Approach 1:
Segmenting the electrode layer reduces the required thickness for each individual electrode portion while maintaining sufficient mechanical strength. The segmented structure distributes mechanical loads more effectively, allowing thinner electrodes that still provide adequate strength and uniform potential distribution.
Solution Approach 2:
The electrode may use composite material structures that provide both electrical conductivity and mechanical strength. This allows the electrode to be sufficiently thin for uniform potential distribution while maintaining the necessary mechanical properties through material composition rather than relying solely on thickness.
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 ensures consistent ink ejection characteristics by minimizing potential differences between electrodes, maintaining uniformity in ink droplet size and shape across all nozzles, regardless of the number of nozzles activated, thereby improving printing quality.
Implementation Method 1
Each of the piezoelectric element bodies includes lower electrode layers, a piezoelectric layer, and an upper electrode layer. When a voltage is applied to the lower electrode layers and the upper electrode layer, distortion occurs in the piezoelectric layer positioned between the lower electrode layers and the upper electrode layer. As a result, the piezoelectric element bodies are distorted and deformed and ink in the pressure chambers is ejected from the nozzles.
Data Source
AI summary
A width in a second direction of the first portion disposed in a position corresponding to the first piezoelectric body in the third electrode which intersects with the first direction is a first width. A width in a second direction of the second portion in the third electrode disposed in a position corresponding to the second piezoelectric body is a second width. A width in the second direction of the third portion in the third electrode disposed in a position between the first piezoelectric body and the second piezoelectric body in the first direction is a third width which is smaller than the first width and the second width.