Inkjet Printhead Meniscus Control via Dynamic Pressure
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Solution Overview
Problem
Inkjet printing systems face limitations in supplying ink to nozzles on complex, three-dimensional surfaces due to the reliance on backpressure, which restricts the ink supply rate and is not effectively adaptable to changing printhead orientations.
Innovation Solution
The system incorporates a feed line and a recirculation line with variable speed pumps and sensors to dynamically control feed and recirculation fluid pressures, adjusting based on printhead orientation to maintain a target pressure differential at the nozzle, ensuring consistent ink supply regardless of orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If backpressure is used to supply ink to the nozzle, then the meniscus level is maintained, but the ink supply rate is limited
Solution Approach 1:
The system divides the ink supply function into two independent pathways: a feed line with a feed pump for primary ink supply, and a recirculation line with a recirculation pump for maintaining meniscus pressure. This segmentation allows each pump to be optimized for its specific function, resolving the contradiction between maintaining meniscus level and achieving high supply rate.
Solution Approach 2:
The system dynamically adjusts the speeds of both the feed pump and recirculation pump based on real-time feedback from pressure sensors and orientation sensors. This dynamic control allows the system to maintain stable meniscus pressure while adapting ink supply rates to varying operational demands, thereby resolving the contradiction between reliability and productivity.
2Device complexity
If a single pressure control system is used, then the system is simple, but it cannot adapt to changing printhead orientations
Solution Approach 1:
The system transitions from static pressure control to dynamic pressure control by continuously monitoring printhead orientation via orientation sensors and adjusting pump speeds accordingly. This allows the dual-pump system to adapt to varying orientations while maintaining appropriate pressure differentials, resolving the contradiction between system simplicity and adaptability.
Solution Approach 2:
The system incorporates pressure sensors in both the feed line and recirculation line, along with orientation sensors, that provide real-time feedback to the controller. This feedback mechanism enables the system to automatically adjust pump operations in response to changing orientations, achieving adaptability without excessive complexity through intelligent control.
3Adaptability or versatility
If variable speed pumps are used to dynamically control pressure, then ink supply adapts to orientation changes, but system complexity increases
Solution Approach 1:
The controller serves multiple functions: it manages both the feed pump and recirculation pump, processes data from pressure sensors and orientation sensors, calculates required pressure differentials based on orientation, and adjusts pump speeds accordingly. This multi-functionality reduces overall system complexity by consolidating control logic into a single intelligent unit.
Solution Approach 2:
The system uses closed-loop feedback control where pressure sensors continuously monitor actual pressures in both lines, and the controller adjusts pump speeds to maintain target pressure differentials. This feedback mechanism automates the adaptation process, reducing the need for complex manual control systems while achieving superior adaptability to orientation changes.
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 allows for efficient and adaptive ink supply to nozzles on complex surfaces, enabling precise inkjet printing by dynamically managing fluid pressures and flow rates in response to printhead orientation, thereby overcoming the limitations of traditional backpressure methods.
Implementation Method 1
A feed pump is disposed in the feed line and has a variable feed pump speed to generate a feed fluid pressure in the feed line between the feed pump and the nozzle
Implementation Method 2
A recirculation pump is disposed in the recirculation line and has a variable recirculation pump speed to generate a recirculation fluid pressure in the recirculation line between the recirculation pump and the nozzle
Implementation Method 3
maintain a target pressure differentiation across the nozzle
Data Source
AI summary
Inkjet printing systems and methods dynamically control meniscus pressure at a nozzle to more reliably deliver ink to a substrate. The systems and methods include inferring an angle of a longitudinal axis of a printhead relative to the vertical reference axis based on an orientation signal from an orientation sensor, determining a target feed fluid pressure upstream of the nozzle and a target recirculation fluid pressure downstream of the nozzle, thereby to maintain a target pressure differentiation across the nozzle based, at least in part, on the inferred angle of the longitudinal axis, and controlling a variable feed pump speed and a variable recirculation pump speed to obtain the target feed fluid pressure and the target recirculation fluid pressure.