Inkjet Head Lid Segmentation for Residual Stress Reduction
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Solution Overview
Problem
Inkjet heads with piezoelectric elements experience internal stress due to thermosetting material bonding, leading to improper liquid discharge from pressure chambers.
Innovation Solution
The nozzle plate and lid members are integrally formed, with the nozzle plate made of polyimide and lid members made of metal with a nickel plating layer, ensuring each lid is not in contact with electrodes and pressure chambers, reducing residual stress and improving discharge efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a lid member with high rigidity is bonded to piezoelectric elements using thermosetting material, then the rigidity of pressure chamber walls is improved, but internal stress remains in the piezoelectric elements after bonding and cooling, causing improper liquid discharge
Solution Approach 1:
The lid member is divided into multiple separate lid portions, each covering individual pressure chambers. This segmentation reduces the overall bonding area between the lid member and piezoelectric elements, thereby minimizing the generation of internal stress during thermal bonding while still providing sufficient rigidity to each pressure chamber wall.
Solution Approach 2:
The piezoelectric elements are positioned at specific locations where they do not directly contact the lid member, creating localized stress-free zones. This allows the lid member to maintain high rigidity over the pressure chambers while the piezoelectric elements remain free from internal stress, ensuring proper liquid discharge functionality.
2Strength
If thermosetting material is used for bonding the lid member to piezoelectric elements, then bonding strength is improved, but heat application during bonding causes internal stress and residual stress after cooling
Solution Approach 1:
The bonding structure is segmented into multiple small bonding interfaces between the lid portions and piezoelectric elements, rather than one large continuous bonding area. This reduces the total heat-affected zone and minimizes thermal stress accumulation during the bonding process.
Solution Approach 2:
The lid member acts as an intermediary structure that is positioned between the pressure chambers and the external environment. By designing it with multiple separate lid portions rather than a continuous structure, it provides mechanical support while allowing thermal stress to be distributed and reduced.
3Stability of the object's composition
If the lid member is made with high rigidity material, then pressure stabilization in pressure chambers is improved, but manufacturing complexity increases due to stress management requirements
Solution Approach 1:
The lid member is manufactured as multiple separate lid portions that can be individually positioned and bonded. This segmentation simplifies the manufacturing process by allowing each lid portion to be independently fabricated and assembled, reducing the overall manufacturing complexity while maintaining pressure stabilization functionality.
Solution Approach 2:
Instead of making the lid member a single complex piece that integrates all functions, the design inverts the approach by using multiple simple lid portions that collectively achieve the same pressure stabilization effect, thereby reducing manufacturing complexity.
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 enhances the rigidity and precision of inkjet heads, allowing for efficient liquid discharge and reducing residual stress, resulting in improved printing performance and cost-effectiveness.
Implementation Method 1
a piezoelectric unit disposed on the substrate and including a plurality of piezoelectric elements arranged along a surface of the substrate
Implementation Method 2
the lid members made of metal with a nickel plating layer
Data Source
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AI summary
An inkjet head includes a substrate, a piezoelectric unit disposed on the substrate and including a plurality of piezoelectric elements arranged along a surface of the substrate, and a plurality of pressure chambers, each of the pressure chambers being formed between two adjacent piezoelectric elements, a plurality of lid members, each of which is disposed on two adjacent piezoelectric elements and has a hole connected to one of the pressure chambers, and a nozzle plate disposed on the plurality of lid members and having a plurality of nozzles through which the liquid is discharged, each of the nozzles being connected to one of the holes of the lid members.