Thermal Bend Actuator for High-Density Inkjet Nozzles
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Solution Overview
Problem
Existing thermal bend actuated inkjet nozzles face inefficiencies in bend actuation and drop ejection characteristics, particularly in achieving high packing density and optimal droplet volume with minimal structural rigidity and viscous ink interaction.
Innovation Solution
The design incorporates a thermal bend actuator with a reduced working face area of less than 800 square microns, utilizing a fused active and passive beam configuration with a peak actuator velocity of at least 2.5 m/s, and an ink supply system that varies hydrostatic pressure to control droplet volume, enabling efficient drop ejection and denser nozzle packing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the working face area of the thermal bend actuator is reduced to increase packing density, then nozzle packing density is improved, but drop ejection efficiency may deteriorate
Solution Approach 1:
The patent optimizes the working face area to a specific range (less than 800 square microns) to achieve the right balance between packing density and ejection efficiency. This parameter optimization allows smaller actuator footprint while maintaining sufficient force generation for effective drop ejection.
Solution Approach 2:
The patent addresses potential ejection efficiency loss by implementing preliminary design compensations in the actuator structure and drive waveform, ensuring that the reduced working face area does not compromise drop ejection performance. The drive circuitry is specifically designed to compensate for the smaller actuator area.
2Power
If the active and passive beams are spaced apart to maximize thermal bend efficiency, then thermal bend efficiency is improved, but structural rigidity deteriorates
Solution Approach 1:
The patent employs a fused beam configuration where the active and passive beams are connected through a fusion process, creating a rigid yet thermally efficient structure. This fusion technique maintains structural integrity while allowing the beams to be positioned close together, maximizing thermal bend efficiency without sacrificing rigidity.
3Force
If both faces of the paddle work against viscous ink to achieve sufficient displacement, then drop ejection force is improved, but actuator complexity increases
Solution Approach 1:
The patent eliminates the traditional paddle structure entirely, replacing it with a direct actuator configuration where the fused active and passive beams provide the necessary displacement. This extraction of the paddle component simplifies the actuator structure while maintaining effective drop ejection force through optimized beam geometry and material properties.
4Productivity
If the working face area is reduced to enable denser packing, then manufacturing density is improved, but the force generation capability may worsen
Solution Approach 1:
The patent uses composite material construction for the fused active and passive beams, selecting materials with high Young's modulus and appropriate thermal expansion coefficients. This composite approach enables the small working face area to generate sufficient force by leveraging the superior mechanical properties of the materials, thus achieving both high packing density and adequate force generation.
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 drop ejection efficiency, reduces satellite droplets, and allows for denser nozzle packing while achieving droplet volumes up to 100% larger than minimum volumes, supporting versatile printing applications.
Implementation Method 1
when a current is passed through the active beam, the active beam heats and expands relative to the passive beam
Implementation Method 2
the active beam heats and expands relative to the passive beam resulting in bending of the actuator
Implementation Method 3
said actuator has a working face for generating a positive pressure pulse in said ink during said bending of said actuator
Data Source
AI summary
An inkjet nozzle assembly comprising a nozzle chamber for containing ink, the chamber having a nozzle opening and an ink inlet; a pair of electrical contacts positioned at one end of the assembly and connected to drive circuitry; and a thermal bend actuator for ejecting ink through the nozzle opening, the actuator comprising: an active beam connected to the electrical contacts and extending longitudinally away from the contacts, the active beam defining a bent current flow path between the contacts; and a passive beam fused to the active beam, such that when a current is passed through the active beam, the active beam heats and expands relative to the passive beam resulting in bending of the actuator, wherein the actuator has a working face for generating a positive pressure pulse in the ink during the bending of the actuator, the working face having an area of less than 800 square microns.