Continuous Inkjet Printer EHT Trip Event Discrimination
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Solution Overview
Problem
Continuous inkjet printers face issues with distinguishing between true and false electrostatic trip events, leading to unnecessary shutdowns due to confusion with other sources of electrostatic discharge, such as an operator's static charge, which affects operational effectiveness.
Innovation Solution
A control unit is configured to detect electrostatic trip events and differentiate between true and false events by comparing time measures, including the duration of trip events and the time between successive events, using specific criteria to determine whether a trip condition is valid or false.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sensing facility is used to detect arcing and initiate shutdown, then print quality is protected from deterioration, but false trip events cause unnecessary shutdowns reducing operational effectiveness
Solution Approach 1:
The control unit continuously monitors trip events and uses feedback from multiple detection criteria (voltage threshold, pulse width, repetition rate) to determine whether to initiate shutdown. This multi-parameter feedback system distinguishes between true arcing conditions requiring shutdown and false trip events from static discharge, thereby protecting print quality while maintaining operational effectiveness.
Solution Approach 2:
The system changes the detection parameters from simple voltage threshold detection to a multi-parameter analysis including voltage threshold, pulse width duration, and repetition rate. By monitoring multiple parameters simultaneously, the system can differentiate between genuine arcing events (which exhibit specific temporal and voltage characteristics) and false trip events (such as operator static discharge), thus reducing unnecessary shutdowns while maintaining print quality protection.
2Reliability
If the detection threshold is made sensitive to detect all arcing, then print quality is protected, but false trip events from static discharge increase causing unnecessary shutdowns
Solution Approach 1:
The system transitions from single-parameter voltage threshold detection to multi-parameter detection including pulse width and repetition rate. True arcing events produce characteristic pulse patterns with specific durations and repetition rates, whereas static discharge events have different temporal characteristics. By analyzing multiple parameters, the system achieves high detection accuracy for genuine arcing while filtering out false trip events.
Solution Approach 2:
The control unit is pre-configured with knowledge of the temporal and voltage characteristics of both true arcing events and false trip events. This preliminary configuration allows the system to immediately distinguish between the two types of events when they occur, enabling accurate detection without requiring complex real-time analysis or additional sensing components.
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 solution effectively reduces unnecessary printer shutdowns by accurately distinguishing between true and false trip events, ensuring that only legitimate deteriorations in operating conditions lead to printer shutdowns, thereby maintaining print quality and operational effectiveness.
Implementation Method 1
an electrostatic facility, typically a spaced pair of conductive plates held at different potentials to create an extra high tension (EHT) field there-between
Implementation Method 2
Those droplets that are charged are deflected by the EHT field away from their original trajectory
Implementation Method 3
Ink, together with entrained air, is generally returned to the printer housing under vacuum, the vacuum being generated by a pump in the gutter line
Implementation Method 4
A vibration or perturbation is applied to the ink jet causing the jet to form into into a stream of droplets, a process known as break-up
Data Source
Figure 1~2
Figure 3~4(C)
AI summary
The invention describes a method and apparatus for characterising EHT tripping events and thus discriminating between false trip events and those that warrant the printer being shut down.