Inkjet Nozzle Paddle Actuation for Droplet Direction Control
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Solution Overview
Problem
Pagewidth inkjet printheads face challenges in achieving high print quality and efficiency due to redundant nozzle rows for dead nozzle compensation and ground bounce issues, which increase complexity and cost, while also requiring precise alignment and ink distribution across join regions.
Innovation Solution
The development of an inkjet nozzle assembly with moveable paddles actuated by thermal bend actuators, allowing independent control of droplet ejection direction and enabling reduced redundant nozzle rows, improved electrical efficiency, and seamless integration across pagewidth printheads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant nozzle rows are added for dead nozzle compensation, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies dynamics by making the nozzle opening moveable through a paddle mechanism that can be actuated to change the position and direction of ink ejection. This dynamic capability allows a single nozzle to compensate for dead nozzles by redirecting droplets to alternate locations, eliminating the need for redundant static nozzle rows while maintaining reliability.
Solution Approach 2:
The moveable paddle mechanism provides multi-functionality by enabling a single nozzle to perform both normal ejection and dead nozzle compensation functions. The paddle can redirect droplets to different positions on the print medium, allowing one nozzle to serve multiple purposes including compensating for failures in other nozzles, thereby reducing the need for redundant nozzle rows.
2Manufacturing precision
If multiple independently-actuable paddles are used to control droplet directionality, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the roof of the nozzle chamber into multiple independently-actuable paddles (typically two or more). Each paddle can be controlled separately to adjust droplet direction, allowing precise control of ejection angle and position. This segmented approach enables fine-tuned directional control while keeping each individual paddle relatively simple in structure.
Solution Approach 2:
The patent replaces complex mechanical positioning systems with a simpler thermal or electrostatic actuation mechanism for the paddles. By using thermal bend actuators or electrostatic forces to move the paddles, the system achieves precise droplet directionality control without requiring complex mechanical linkages, gears, or motors, thus improving precision while limiting complexity growth.
3Productivity
If moveable paddles with thermal bend actuators are implemented, then productivity is improved through reduced redundant nozzles, but use of energy increases
Solution Approach 1:
The patent employs thermal expansion through thermal bend actuators that use temperature changes to move the paddles. When current is applied to the thermal actuator, it heats up and expands, causing the paddle to bend and redirect the droplet. This thermal mechanism is energy-efficient compared to mechanical actuators, providing sufficient force for paddle movement with minimal energy input, thus improving productivity without excessive energy consumption.
4Adaptability or versatility
If independent paddle actuation is used for drop directionality control, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent applies dynamics by implementing independently-actuable paddles that can be controlled in real-time to adjust droplet ejection direction. This dynamic control capability allows the system to adapt to different printing requirements, such as compensating for dead nozzles, adjusting dot placement, or optimizing ink distribution, thereby improving adaptability while maintaining relatively simple paddle structures.
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 enhances print quality and efficiency by minimizing redundant nozzle rows, reducing complexity and cost, and ensuring consistent dot pitch across the printhead width, while improving electrical efficiency and ink distribution, thus achieving higher dot densities and reliable operation.
Implementation Method 1
each paddle including a thermal bend actuator comprising: an upper thermoelastic beam connected to drive circuitry; and a lower passive beam fused to the thermoelastic beam, such that when a current is passed through the thermoelastic beam, the thermoelastic beam expands relative to the passive beam, resulting in bending of a respective paddle towards the floor of the nozzle chamber
Data Source
AI summary
A method of controlling a direction of droplet ejection from an inkjet nozzle having a plurality of moveable paddles, the method includes the steps of: (i) actuating a first thermal bend actuator via respective first drive circuitry such that a respective first paddle bends towards a floor of the nozzle chamber; (ii) actuating a second thermal bend actuator via respective second drive circuitry such that a respective second paddle bends towards a floor of the nozzle chamber; and (iii) thereby ejecting a droplet of ink. Actuation of the first and second thermal bend actuators is independently controlled via the first and second drive circuitry so as to control the direction of droplet ejection.