Electrostatic Inkjet Printhead Actuator Fabrication
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Solution Overview
Problem
Piezoelectric actuated inkjet printheads used in large format inkjet printing face challenges in processing with conventional semiconductor wafer fabrication techniques, as they require lengthy saw times and have size limitations due to tooling constraints.
Innovation Solution
The development of an electrostatic actuator and fabrication process using standard semiconductor wafer processing tools, which includes an inkjet printhead with electrostatic forces generated by conductors to flex the ink channel walls for ink ejection, allowing for the use of MEMS capacitors and stiction bumps to prevent electrical shorting, enabling flexible and efficient ink drop ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If piezoelectric materials are used for inkjet printhead actuators, then large format printing capability is achieved, but manufacturing complexity increases due to lengthy saw times and tooling constraints
Solution Approach 1:
The patent replaces the mechanical saw cutting process with a chemical etching process using silicon dioxide layers. Instead of using a saw to pattern piezoelectric material, the invention uses standard semiconductor photolithography and etching techniques to define the actuator regions, eliminating the need for specialized saw tooling and reducing manufacturing complexity.
Solution Approach 2:
The patent changes the material parameter from piezoelectric material to piezoresistive material (silicon dioxide). This parameter change allows the use of conventional semiconductor fabrication processes instead of specialized piezoelectric processing, thereby simplifying the manufacturing process while maintaining large format printing capability.
2Manufacturing precision
If conventional semiconductor wafer fabrication techniques are used, then manufacturing precision is improved, but piezoelectric material processing becomes difficult
Solution Approach 1:
The patent substitutes piezoelectric material with piezoresistive material (silicon dioxide), which can be processed using standard semiconductor fabrication techniques. This material substitution enables the use of well-established photolithography, etching, and deposition processes, achieving high manufacturing precision while greatly improving ease of manufacture.
Solution Approach 2:
The patent changes the functional parameter from piezoelectric effect to piezoresistive effect. By using silicon dioxide that changes resistance under stress rather than piezoelectric materials that generate charge under stress, the invention enables compatibility with conventional semiconductor processing tools and techniques.
3Length of moving object
If saw tooling is used to pattern piezoelectric material, then feature size is limited, but productivity decreases due to lengthy saw times
Solution Approach 1:
The patent replaces the slow mechanical saw cutting process with rapid chemical etching using photolithography masks. This substitution eliminates the lengthy saw times while enabling precise patterning of the actuator features, thereby improving both productivity and feature size control.
Solution Approach 2:
The patent extracts the piezoelectric material from the conventional fabrication process and replaces it with piezoresistive material that can be processed using standard semiconductor techniques. This removal of the problematic material enables the use of faster, more precise fabrication methods.
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 solution allows for the production of inkjet printheads suitable for very large format printing, overcoming the limitations of conventional piezoelectric actuator fabrication by enabling precise control over ink ejection and reducing issues like air bubbles and ink drooling, while utilizing standard semiconductor processing techniques.
Implementation Method 1
electrostatic forces generated by conductors in the printhead flex one wall of the ink channel back and forth rapidly to alternately expand and contract the ink channel to eject drops of ink
Implementation Method 2
The capacitor includes a first conductor, a second conductor, and an insulator between the first conductor and the second conductor
Data Source
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AI summary
An electrostatic actuator (42) for ejecting fluid from a plurality of chambers, comprising a plurality of conductors (44,74) arranged on a bonding surface of a substrate, wherein each of the conductors (44,74) has an associated chamber (36); a plurality of blockers (104) arranged on the bonding surface of the substrate and positioned between each of the conductors (44,74). The electrostatic actuator also comprises a conductive layer (90) comprising a flexible conductive membrane (86) forming at least part of a wall of each chamber (36); and a plurality of bumps (102); and a voltage source (60) operably connected to each of the conductors (44,74) and the conductive layer (90), for selectively applying a voltage between each of the conductors (44,74) and the conductive layer (90). Each of the plurality of bumps (102) is located over a corresponding one of the plurality of blockers (104) across a gap (58).