Inkjet Droplet Positioning via Post-Ejection Camera Feedback
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Solution Overview
Problem
Existing inkjet devices lack reliable methods for precise positioning of bioactive droplets on substrates and fail to detect droplet degeneration during the printing process, which limits their reliability, especially in applications requiring accurate biochemical tests.
Innovation Solution
An inkjet device equipped with a print head and a control camera that detects droplets post-ejection, providing high-precision imaging of droplet trajectory, size, velocity, and straightness, allowing for continuous monitoring and detection of droplet positioning and degeneration through viscosity and surface tension analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional photo detector is used to detect droplet ejection, then the device structure is simple, but the measurement precision is insufficient to detect droplet characteristics accurately
Solution Approach 1:
The patent replaces the conventional photo detector (optical detection system) with a control camera system that captures images of droplets during ejection. This substitution enables precise measurement of droplet characteristics including position, velocity, size, and trajectory by analyzing multiple images taken at different time points, thereby significantly improving measurement precision while accepting increased device complexity
Solution Approach 2:
The control camera creates visual copies (images) of the droplet at different stages of ejection. By capturing and analyzing these image copies, the system can determine droplet characteristics such as position, velocity, and trajectory without physically interfering with the droplet, thus achieving high precision measurement
2Reliability
If droplet detection is performed only from time to time, then the device operation is simple, but the reliability of droplet positioning is insufficient
Solution Approach 1:
The patent implements continuous detection of droplet ejection by the control camera throughout the printing process, rather than periodic detection. This continuous monitoring ensures that every droplet's position and characteristics are verified in real-time, significantly improving positioning reliability while requiring a more complex control system to process the continuous stream of detection data
Solution Approach 2:
The system establishes a feedback loop where the control camera continuously detects droplet characteristics and provides real-time information to the control unit. The control unit can then adjust printing parameters based on this feedback to ensure accurate positioning, thereby improving reliability through active correction while increasing control system complexity
3Stability of the object's composition
If no substance degradation detection is implemented, then the printing process is fast, but the integrity of bioactive substances cannot be ensured
Solution Approach 1:
The control camera captures images of the droplet during its flight before it reaches the substrate. This preliminary detection allows the system to assess droplet characteristics and substance integrity early in the process, enabling timely correction or rejection of defective droplets without significantly impacting the overall printing throughput
Solution Approach 2:
The system performs rapid image capture and analysis of droplet characteristics during flight, skipping detailed analysis for obviously acceptable droplets while focusing computational resources on borderline cases. This selective approach maintains high printing speed while ensuring substance integrity through targeted detection
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
Ensures highly reliable and precise droplet positioning with continuous feedback, reducing errors and maintaining the integrity of bioactive substances by detecting and addressing any deviations in droplet characteristics during the printing process.
Implementation Method 1
a control camera arranged such that after ejection of the droplet out of the nozzle, the droplet is detected by the control camera
Implementation Method 2
the droplet is detected by the control camera
Data Source
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Figure 5a~5b
AI summary
The invention provides a device for the controlled positioning of droplets of a substance onto a substrate, the device comprising at least a print head comprising a nozzle provided to eject the droplet, the inkjet device further comprising a control camera arranged such that after ejection of the droplet out of the nozzle, the droplet is detected by the control camera. In case either the droplet volume or velocity or flight path or viscosity or surface tension start to deviate from preset values, the software can correct for this in a closed loop manner. If the droplet is not ejected at all, the control software stops the printer and an operator can maintain the print head.