Printhead Nucleation Detection via Thermal Response
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Solution Overview
Problem
Current methods for determining the appropriate firing pulse width for thermal inkjet printers require printing samples or external sensors, which are inefficient and may lead to variations in droplet formation and misdirection due to manufacturing variations.
Innovation Solution
A method that applies a series of energy-balanced input pulse trains to the printhead heaters, decrementing pulse width while maintaining constant power, and uses temperature slope analysis from thermal sense resistors to determine the nucleation point and set the optimal firing pulse width without the need for printing samples or external sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical alignment sensors or external sensors are used to measure drop velocity or print density for tuning fire pulse width, then droplet velocity and print density can be measured, but the system complexity increases and requires additional external components
Solution Approach 1:
The printhead uses its own thermal sense resistors to measure temperature during ink ejection, eliminating the need for external optical sensors. The system measures its own operational parameters through thermal feedback from the heating elements, achieving self-diagnosis and self-tuning capability
Solution Approach 2:
The measurement function is extracted from external optical sensing equipment and integrated directly into the printhead structure through thermal sense resistors, removing the need for separate external measurement systems while maintaining measurement capability
2Measurement precision
If printing samples are used to determine nucleation point, then fire pulse width can be tuned, but ink is consumed and printing time is required
Solution Approach 1:
The mechanical printing process is replaced with an electrical measurement process. Instead of physically printing samples and measuring them, the system uses electrical pulses and thermal sensing to detect nucleation point, substituting a non-contact electrical/thermal method for a contact-based mechanical printing method
Solution Approach 2:
The system performs preliminary thermal conditioning by applying a series of energy-balanced input pulse trains with decrementing pulse widths to bring the printhead to the nucleation point before actual printing begins, allowing measurement without consuming printing materials
3Measurement precision
If a series of energy-balanced input pulse trains with decrementing pulse widths are applied to determine nucleation point, then the proper firing pulse width can be accurately determined, but the measurement process time increases
Solution Approach 1:
The system applies periodic energy-balanced input pulse trains with systematically decrementing pulse widths to efficiently sweep through the parameter space and identify the nucleation point, using regular periodic measurements to accelerate the detection process
Solution Approach 2:
The system uses real-time thermal feedback from the thermal sense resistors during pulse application to dynamically adjust measurements and quickly identify the nucleation point, using the temperature response as feedback to optimize the search process
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 quick and accurate determination of the proper nozzle firing pulse width, ensuring consistent droplet formation and reduced misdirection, while conserving ink and minimizing printer downtime.
Implementation Method 1
The printhead temperature data received during each heating interval is processed to determine a respective temperature slope
Implementation Method 2
A series of intervals of energy-balanced input pulse trains are applied to the printhead heaters
Implementation Method 3
The slope of the printhead temperature for each interval is used to determine the nucleation point
Data Source
AI summary
A method for determining the pulse width for driving printhead nozzles in a thermal inkjet printer. The printhead is preheated to a desired temperature during a maintenance mode. The printhead nozzle heaters are successively driven in respective heating intervals, where each successive heating interval is characterized by shorter drive pulse width pulses occurring at a higher pulse frequency. The printhead temperature data received during each heating interval is processed to determine a respective temperature slope. The temperature slopes are compared to a desired threshold temperature slope, and when a match is found, the pulse width associated with the matched temperature slope is used to drive the nozzle heaters during subsequent printer operations to print characters on a print medium.