Deflection Plate Dielectric Coating for Liquid Jet Printer Arcing
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Solution Overview
Problem
Liquid jet printers experience arcing between deflection plates due to droplet accumulation, which reduces the effective gap and causes electrical field breakdown, leading to defects in the print pattern.
Innovation Solution
Applying a high dielectric strength coating on the deflection plates, combined with a hydrophobic layer, to insulate and prevent arcing by minimizing droplet coalescence and maintaining the electrical field integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid droplets accumulate on the deflection plates, then the effective gap between plates is reduced, but this causes electrical field breakdown and arcing between plates
Solution Approach 1:
A dielectric coating layer is applied as an intermediary between the conductive deflection plate and the accumulated liquid droplets. This dielectric layer prevents direct electrical contact between the plate and droplets, eliminating the arcing pathway while allowing the plates to tolerate droplet accumulation without electrical field breakdown.
2Reliability
If a thick dielectric layer is applied on the deflection plate, then arcing is reduced, but the plate encroaches upon the liquid jet droplet path
Solution Approach 1:
The dielectric layer thickness is optimized to a specific range (100 nm to 0.1 mm) that provides sufficient arcing resistance while maintaining adequate clearance from the droplet path. This parameter optimization allows the system to achieve both protection against arcing and preservation of droplet trajectory without requiring excessive material thickness.
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
The solution effectively reduces arcing and maintains print quality by ensuring the electrical field steers droplets accurately without breakdown, even with accumulated droplets, thereby preventing defects on the substrate.
Implementation Method 1
An outer layer of the interior side of one or both of the deflecting plates is a dielectric. The dielectric outer layer is selected from a variety of materials that are capable of insulating liquid droplets collected on the deflecting plates, providing a voltage drop between the deflecting plate and collected liquid droplets
Implementation Method 2
The dielectric outer layer is selected from a variety of materials that are capable of insulating liquid droplets collected on the deflecting plates, providing a voltage drop between the deflecting plate and collected liquid droplets and/or decreasing arcing between the pair of deflecting plates
Implementation Method 3
The invention may further include a hydrophobic film overlaying the dielectric outer layer. Or, the dielectric layer may itself be hydrophobic. The hydrophobic film minimizes the size of the liquid droplets that coalesce on the deflecting plates.
Data Source
AI summary
A liquid jet printing apparatus is provided having a nozzle for emitting a stream of liquid droplets toward a substrate, a charging section for providing an electrical charge to liquid droplets and a pair of electrically conductive deflecting plates for deflecting the liquid droplets to a desired location on the substrate, wherein the inside face of the deflecting plates is provided with dielectric layer to minimize problems associated with liquid droplets collecting and coalescing on the deflecting plates.