Piezoelectric Droplet Ejector for High Density Printheads
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Solution Overview
Problem
Piezoelectric inkjet printers face limitations in nozzle count and suffer from acoustic cross-talk issues due to the interaction between neighboring piezoelectric actuators and fluid channels, restricting their operational efficiency and print quality.
Innovation Solution
A droplet ejector design that integrates a piezoelectric actuator on the nozzle-forming layer, using low-temperature processable piezoelectric materials like aluminium nitride and zinc oxide, which reduces acoustic cross-talk by requiring lower fluid pressures for droplet ejection, allowing for higher nozzle densities and improved manufacturing yields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If piezoelectric actuators are used in inkjet printers, then a range of fluids can be used and operational lifetime is extended, but nozzle count per printhead is limited and acoustic cross-talk occurs
Solution Approach 1:
The piezoelectric actuator is divided into multiple independent actuators arranged in an array on the printhead, with each actuator independently controlling a nozzle. This segmentation allows higher nozzle counts while maintaining the reliability benefits of piezoelectric technology.
Solution Approach 2:
The patent implements acoustic isolation structures (such as acoustic barriers or damping materials) between neighboring piezoelectric actuators to locally reduce acoustic cross-talk. This allows each actuator to operate independently without interference, enabling higher nozzle densities while maintaining operational reliability.
2Productivity
If high nozzle count is achieved, then productivity is improved, but acoustic cross-talk between neighbouring actuators increases
Solution Approach 1:
Acoustic isolation structures are introduced between neighboring piezoelectric actuators to extract or block the harmful acoustic waves. This prevents pressure waves from one actuator from interfering with adjacent actuators, enabling higher nozzle counts without compromising print quality.
Solution Approach 2:
Acoustic barrier structures serve as intermediary elements between neighboring piezoelectric actuators, absorbing or blocking acoustic energy to prevent cross-talk. This intermediary structure allows dense actuator arrays while maintaining independent operation of each nozzle.
3Device complexity
If electronic components are integrated with the substrate, then device complexity is reduced, but processing temperature must be kept below 450°C to avoid degradation
Solution Approach 1:
The patent changes the processing temperature parameter from high-temperature (>450°C) to low-temperature (<450°C) processing to enable the integration of piezoelectric actuators with CMOS electronic components on the same substrate without degrading the sensitive electronics.
Solution Approach 2:
The patent uses composite material structures that are compatible with low-temperature processing, allowing the piezoelectric actuator layer to be deposited and processed on a substrate containing temperature-sensitive CMOS electronics, achieving monolithic integration without component degradation.
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 design enables a higher nozzle count per printhead, reduces acoustic cross-talk, and enhances manufacturing efficiency by using materials that can be processed at lower temperatures without damaging integrated electronic components, leading to improved print quality and reduced manufacturing costs.
Implementation Method 1
Deformation of a piezoelectric element causes deflection of the piezoelectric actuator, inducing a pressure change in the printing fluid stored within the fluid chamber and thereby causing droplet ejection through a nozzle
Data Source
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AI summary
A droplet ejector for a printhead comprises: a substrate having a mounting surface and an opposite nozzle surface; at least one electronic component integrated with the substrate; a nozzle-forming layer formed on at least a portion of the nozzle surface of the substrate; a fluid chamber defined at least in part by the substrate and at least in part by the nozzle-forming layer,the fluid chamber having a fluid chamber outlet defined at least in part by a nozzle portion of the said nozzle-forming layer;a piezoelectric actuator formed on at least a portion of the nozzle portion of the nozzle- forming layer; and a protective layer covering the piezoelectric actuator and the nozzle-forming layer. The piezoelectric actuator comprises a piezoelectric body provided between first and second electrodes. At least one of the said first and second electrodes is electrically connected to the at least one electronic component. The piezoelectric body comprises one or more piezoelectric materials processable at a temperature below 450°C.