Print Head Droplet Control for Precise Fluid Deposition
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Solution Overview
Problem
In printing processes using multiple nozzles, inconsistencies in droplet volumes lead to variations in deposited fluid volumes, which can result in defects in display manufacturing, particularly in OLED displays, and existing solutions either fail to maintain precision within tolerance ranges or significantly increase manufacturing time and cost.
Innovation Solution
Techniques for precisely controlling deposited fluid volumes by measuring and planning print head firing patterns and motion to accommodate nozzle-to-nozzle variations, using combinations of droplet volumes and alternate nozzle firing waveforms, and optimizing print head/substrate movements to achieve specific aggregate fill volumes within tolerance ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If standard drive waveform is applied to all nozzles, then manufacturing process is simple and fast, but droplet volume consistency deteriorates
Solution Approach 1:
The patent applies different drive waveforms to different nozzles based on their individual characteristics. Each nozzle is characterized to determine its specific droplet volumes under various drive waveforms, and this per-nozzle customization enables precise control of droplet volumes while maintaining overall system productivity.
Solution Approach 2:
The patent dynamically selects combinations of nozzles and their corresponding droplet volumes to achieve target fill volumes for each target region. The system adaptively plans which nozzles to use and how many droplets to eject based on real-time requirements, rather than using a fixed printing pattern for all regions.
2Manufacturing precision
If per-nozzle droplet volume measurement and planning is implemented, then deposited fluid precision is improved, but manufacturing complexity increases
Solution Approach 1:
The patent performs preliminary characterization of each nozzle to determine its droplet volumes under different drive waveforms before actual printing. This pre-acquired information is stored and used during printing planning to select appropriate nozzle-droplet combinations, eliminating the need for complex real-time adjustments during the printing process itself.
Solution Approach 2:
The system uses the measured characteristics of each nozzle to automatically plan its own printing strategy. The software independently determines which nozzles to use and how many droplets to eject from each nozzle to achieve target fill volumes, without requiring external intervention or complex hardware adjustments.
3Manufacturing precision
If combinations of droplet volumes are planned to reach precise fills, then manufacturing precision is improved, but manufacturing time increases
Solution Approach 1:
The patent segments the printing process into independent nozzle contributions, where each nozzle's droplet volumes are separately planned and combined to achieve target fill volumes. This segmentation allows the software to efficiently calculate optimal combinations without requiring iterative adjustments or multiple printing passes, thereby maintaining fast manufacturing speeds.
Solution Approach 2:
The patent replaces physical adjustments (such as mechanical positioning or multiple printing passes) with software-based planning. By using computational algorithms to determine optimal nozzle-droplet combinations, the system achieves precise fill volumes without the time penalty associated with mechanical recalibration or repeated printing operations.
4Reliability
If nozzle variations are accommodated through measurement and planning, then product quality is improved, but device complexity increases
Solution Approach 1:
The patent changes the control parameter from a single standard drive waveform applied uniformly to all nozzles to multiple nozzle-specific drive waveforms selected based on measured characteristics. This parameter change enables the system to accommodate nozzle variations and produce high-quality results while keeping the hardware relatively simple.
Solution Approach 2:
The system automatically characterizes each nozzle and uses this information to self-adjust its printing strategy. The software independently determines the optimal drive waveform and droplet count for each nozzle based on its measured characteristics, eliminating the need for complex external control mechanisms or manual calibration procedures.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3C
AI summary
A method for fabricating layers on respective substrates, to produce from each of the respective substrates a respective electronic device comprises the steps of: using a print head to print a liquid onto each of the respective substrates, wherein the print head has nozzles that each eject droplets of the liquid; transporting each of the respective substrates in succession to-and-from a printer where each of the respective substrates can be printed on by the print head; processing a film formed on each substrate from the droplets, in order to form a corresponding one of the layers; and measuring a characteristic of one of the droplets of the liquid ejected from one of the nozzles during droplet flight with a laser.