DOD Print Head Maintenance with Larger Drops for Less Aerosolization
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Solution Overview
Problem
DOD print heads in card personalization systems experience nozzle clogging and aerosolization issues due to infrequent use, leading to reduced throughput and maintenance requirements.
Innovation Solution
Implement a spitting routine where nozzles are actuated multiple times in rapid succession to form larger ink drops that minimize aerosolization and reduce purging frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If nozzles are not used periodically, then card throughput is improved, but nozzle clogging occurs preventing operation
Solution Approach 1:
The system performs preliminary maintenance actions (spitting routine) on nozzles before they become clogged from disuse. By periodically actuating nozzles to eject waste ink drops, the system prevents clogging proactively while allowing cards to be processed continuously, thus maintaining both throughput and nozzle operability
2Reliability
If conventional spitting routine is used with small waste ink drops, then nozzle maintenance is performed, but aerosolization occurs causing blockage
Solution Approach 1:
The system changes the parameter of waste ink drop size by actuating nozzles multiple times in rapid succession to create larger drops. These larger drops have lower velocity and do not aerosolize when they contact the nozzle plate, eliminating the harmful aerosol contamination while still clearing nozzles of dried ink
Solution Approach 2:
The spitting routine uses periodic actuation of nozzles at specific intervals during card processing. This periodic maintenance action prevents nozzle clogging without requiring system shutdown, maintaining productivity while ensuring nozzle reliability through regular clearing
3Reliability
If maintenance routines are performed frequently, then nozzle operability is maintained, but card throughput is reduced due to downtime
Solution Approach 1:
The spitting routine is designed to be performed continuously during normal card processing without interrupting the workflow. By integrating nozzle maintenance into the ongoing production process rather than requiring separate maintenance stops, the system maintains continuous useful action on both card processing and nozzle maintenance simultaneously
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
Enhances nozzle maintenance efficiency, reduces aerosol contamination, and maintains high card throughput by minimizing downtime and waste ink production.
Implementation Method 1
the size of the ejected drop of waste ink is such that the drop has a tendency to aerosolize. The aerosol may float back up to the nozzle plate of the DOD print head and land on the nozzle plate
Data Source
AI summary
A card (or passport) personalization system is described that includes a print mechanism with one or more DOD print heads. A maintenance routine, also referred to as a spitting routine, is described where one or more nozzles of the DOD print head is electrically actuated a plurality of times in rapid succession, each actuation emitting a small drop of ink. The small drops of ink join together in flight after being ejected to create one or more larger waste ink drops. The larger ink drop(s) has less tendency to aerosolize which reduces aerosol contamination of the nozzle plate and the nozzle.