Electrostatic Inkjet Diaphragm Stiffness Control
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Solution Overview
Problem
The challenge in developing electrostatic actuators for inkjet printers lies in the fragility and high manufacturing costs of small piezoelectric transducers, as well as the capital-intensive and tolerance-prone etching processes used to fabricate thin diaphragms, which can introduce defects and reduce yield productivity.
Innovation Solution
A method involving electroplating layers on a mandrel with photoresist to form a diaphragm with flexure recesses, reducing stiffness and improving strength, allowing for precise deposition of material and avoiding the drawbacks of rolling and etching processes, such as grain defects and loose tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thin diaphragms are fabricated using etching processes, then manufacturing precision is improved, but manufacturing cost increases and productivity decreases due to capital intensity and yield losses from pin holes and grain defects
Solution Approach 1:
The patent replaces the mechanical/chemical etching process with an electroplating process. Instead of chemically etching metal layers to create the diaphragm structure, the invention uses electroplating to deposit metal layers precisely where needed, eliminating the harmful etching chemistry that causes pin holes and grain defects while maintaining precise thickness control.
Solution Approach 2:
The patent changes the fabrication parameter from etching depth to electroplating thickness. By controlling the electroplating process parameters (current density, plating time, electrolyte composition), the diaphragm thickness can be precisely controlled without the defects associated with etching. This parameter change transforms a defect-prone process into a high-yield manufacturing method.
2Adaptability or versatility
If piezoelectric transducers are reduced in size to increase density, then actuator density is improved, but manufacturing cost increases and reliability decreases due to fragility
Solution Approach 1:
The patent replaces piezoelectric transducers with electrostatic actuators that use a different physical principle. Instead of relying on fragile piezoelectric crystals, the invention uses electrostatic attraction between charged plates to generate the actuating force, significantly improving reliability while enabling higher actuator density through MEMS fabrication techniques.
Solution Approach 2:
The patent changes the actuation mechanism from piezoelectric to electrostatic. This parameter change in the physical principle allows for smaller, more reliable actuators that can be fabricated using standard semiconductor manufacturing processes, enabling high density without sacrificing reliability.
3Length of moving object
If diaphragm thickness is reduced to enable smaller actuators, then actuator size is improved, but strength decreases making the diaphragm fragile
Solution Approach 1:
The patent applies local quality by creating regions of different thickness within the diaphragm structure. The diaphragm has thicker regions for structural support and thinner regions for flexibility and actuation. This spatial variation in thickness allows the diaphragm to be overall smaller while maintaining local strength where needed.
Solution Approach 2:
The patent uses composite material structures combining multiple metal layers with different properties. By stacking and bonding layers of different metals with complementary characteristics, the diaphragm achieves both the required thinness for small actuator size and sufficient strength through the composite structure.
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 solution results in a diaphragm that requires less current for actuation while maintaining strength and robustness, providing a more uniform pressure head for ink deposition and optimizing power requirements, thus enhancing the efficiency and reliability of electrostatic actuators in inkjet printers.
Implementation Method 1
such electrostatic actuators can include a thin diaphragm bonded to a substrate, with the thin diaphragm flexing by application of electrostatic force
Implementation Method 2
electroplating a first layer on a mandrel, and applying a photoresist to the first layer. The method also includes electroplating a second layer on the first layer adjacent the photoresist
Data Source
AI summary
Diaphragms for electrostatic actuators for inkjet printers and methods for manufacturing are provided. The method includes electroplating a first layer on a mandrel, and applying a photoresist to the first layer. The method also includes electroplating a second layer on the first layer adjacent the photoresist, such that the first and second layers form a substantially homogenous structure, and separating the photoresist from the first and second layers to expose one or more flexure recesses where the photoresist was positioned, with the diaphragm having a reduced stiffness proximal the flexure recess.