Thin Silicon Membrane Printhead for High-Resolution Inkjet Printing
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Solution Overview
Problem
High-resolution inkjet printheads face challenges in maintaining small orifice spacing and reducing voltage requirements due to the thickness of piezoelectric actuator materials, which affects printing accuracy and efficiency.
Innovation Solution
A method involving the formation of a microfabricated device with a thin silicon membrane using a silicon-on-insulator substrate, where a piezoelectric layer is bonded to the membrane, and a metal etch stop is used to prevent charge accumulation and heat-related defects during etching, allowing for thinner membrane formation and reduced orifice spacing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the thickness of the piezoelectric layer is increased, then the deflecting wall area is increased, but the voltage requirement increases
Solution Approach 1:
The patent uses a thin membrane structure (less than 15 microns thick) as the deflecting wall of the pumping chamber. This thin film approach allows the membrane to be more compliant and require less voltage for actuation while maintaining sufficient deflecting area for effective ink ejection.
Solution Approach 2:
The patent changes the thickness parameter of the membrane from conventional thicker piezoelectric layers to a thin membrane structure less than 15 microns thick. This parameter change reduces the voltage requirement while maintaining the necessary deflecting wall area through the thin film's flexibility.
2Area of moving object
If the thickness of the piezoelectric layer is increased, then the deflecting wall area is increased, but the design complexity increases due to larger pumping chamber requirements
Solution Approach 1:
The thin membrane acts as a flexible shell that provides the necessary deflecting area without requiring a large pumping chamber volume. The membrane's flexibility compensates for its small thickness, allowing effective actuation within a compact chamber design.
Solution Approach 2:
Instead of increasing area by expanding the pumping chamber in planar dimensions, the patent uses the thin dimension (less than 15 microns) to create a compliant structure that achieves the necessary deflecting area through its flexibility rather than its size.
3Use of energy by moving object
If a thin membrane is used, then the voltage requirement is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The membrane is formed using a pre-polished silicon substrate with controlled thickness (less than 15 microns). This preliminary preparation of the substrate ensures uniform thickness before the membrane is released and bonded to the printhead body, reducing variability in the final product.
Solution Approach 2:
The patent replaces mechanical grinding or dicing methods with a chemical release approach using oxide layers. The membrane is released from its support substrate through oxide removal and bonding, which provides more uniform thickness control compared to mechanical methods that can introduce variations.
4Manufacturing precision
If smaller orifice spacing is implemented, then the printing resolution is improved, but the design complexity increases due to voltage and chamber size constraints
Solution Approach 1:
The thin membrane allows for smaller orifice spacing because each membrane section requires less voltage to actuate. This reduces the overall voltage requirements and allows for higher density nozzle arrangements without increasing the complexity of individual actuator designs.
Solution Approach 2:
By changing the membrane thickness parameter to less than 15 microns, the patent enables higher resolution printing with smaller orifice spacing. The reduced thickness lowers the voltage requirement for each actuator, allowing for more nozzles per inch without proportionally increasing the voltage demands or chamber sizes.
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 approach enables the production of higher resolution printers with improved thickness uniformity and reduced voltage requirements, enhancing printing accuracy and efficiency by forming thinner, uniform membranes.
Implementation Method 1
The piezoelectric actuator has a layer of piezoelectric material, which changes geometry, or bends, in response to an applied voltage. The bending of the piezoelectric layer pressurizes ink in a pumping chamber located along the ink path.
Implementation Method 2
The bonding forms a silicon-to-silicon bond between the upper surface of the substrate and the silicon layer.
Data Source
AI summary
A microfabricated device and method for forming a microfabricated device are described. A thin membrane including silicon is formed on a silicon body by bonding a silicon-on-insulator substrate to a silicon substrate. The handle and insulator layers of the silicon-on-insulator substrate are removed, leaving a thin membrane of silicon bonded to a silicon body such that no intervening layer of insulator material remains between the membrane and the body. A piezoelectric layer is bonded to the membrane.