Non-Contact Ultrasonic Cleaning for Drop-on-Demand Print Head Nozzle Plates
Solution Overview
Problem
Existing card processing systems face challenges in cleaning drop-on-demand print head nozzle plates without damaging them, as direct contact methods can lead to pressure or abrasion, degrading print quality.
Innovation Solution
An automated cleaning mechanism is implemented that cleans the nozzle plates without physical contact, using a cleaning carriage with movable cleaning blocks and a vacuum system to apply and remove cleaning fluid, ensuring the nozzle plates are not directly touched during the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct contact cleaning methods (cloth or brush) are used on the nozzle plate, then cleaning effectiveness is improved, but the nozzle plate surface is damaged due to excess pressure or abrasion
Solution Approach 1:
The patent replaces the mechanical contact-based cleaning system (cloth or brush) with a non-contact ultrasonic cleaning system. The ultrasonic transducer generates high-frequency vibrations that create cavitation bubbles in the cleaning fluid, which mechanically remove debris from the nozzle plate without direct contact from cleaning elements, thus eliminating abrasion and excess pressure damage.
Solution Approach 2:
The patent uses a spray mechanism that delivers cleaning fluid onto the nozzle plate through fluid dynamics. The cleaning fluid is sprayed onto the nozzle plate surface, and ultrasonic vibrations are applied to the fluid, creating cavitation that cleans the nozzle plate without requiring physical contact from solid cleaning elements.
2Manufacturing precision
If regular cleaning is performed to remove ink and debris accumulation, then print quality is maintained, but the cleaning process risks damaging the delicate nozzle plate surface
Solution Approach 1:
The patent replaces mechanical contact cleaning with ultrasonic vibration-based cleaning. The ultrasonic transducer generates high-frequency vibrations (typically 20-100 kHz) that create cavitation in the cleaning fluid, producing micro-jets and shock waves that remove ink and debris accumulation from the nozzle plate without mechanical contact, thereby maintaining print quality without damaging the delicate surface.
Solution Approach 2:
The ultrasonic cleaning process utilizes phase transitions of the cleaning fluid through cavitation. The ultrasonic vibrations create alternating high and low pressure cycles that cause the cleaning fluid to form and collapse bubbles (phase transition from liquid to vapor and back), generating intense local energy that removes debris without mechanical contact.
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 method effectively prevents damage to the nozzle plates, maintaining print quality and allowing for efficient cleaning of the drop-on-demand card printing system, enabling continuous high-quality printing without degrading the print heads.
Implementation Method 1
a vacuum system to apply and remove cleaning fluid
Implementation Method 2
the ink is an ultraviolet (UV) curable ink
Data Source
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AI summary
A card processing system includes a drop-on-demand card printing system that has at least one drop-on-demand print head with a nozzle plate. An automated cleaning mechanism is provided in the drop-on-demand card printing system that is configured to clean the nozzle plate without the cleaning mechanism physically contacting the nozzle plate. Since the nozzle plate is not physically contacted by the cleaning mechanism, damage to the nozzle plate during cleaning is avoided thereby avoiding degrading the resulting print quality of the print head.