Inkjet Head Conductive Layer Charge Dissipation

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Solution Overview

Problem

Inkjet heads face issues with ink droplet adhesion due to charging during ejection, leading to unstable ejection and reduced image quality, particularly because existing solutions like metal substrates are limited and nozzle covers protrude, affecting gap control and liquid repellent layer formation.

Innovation Solution

An inkjet head with a nozzle plate featuring a conductive layer between the substrate and a liquid repellent layer on the ink discharge surface, which reduces charge accumulation and prevents ink mist adhesion, using materials like tin-doped indium oxide or organic conductive polymers for the conductive layer and fluorine-based compounds for liquid repellency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a fluorine-containing organic compound is used for liquid repellent treatment on the nozzle plate surface, then liquid repellency is improved, but charge accumulation increases leading to ink mist adhesion

Engineering Contradiction:

Improveliquid repellencyVSAvoidcharge accumulation

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

An intermediate layer is introduced between the substrate and the liquid repellent layer. This intermediate layer acts as a mediator that provides charge dissipation pathways while allowing the liquid repellent layer to maintain its repellency function. The intermediate layer typically has higher electrical conductivity than the substrate, creating a gradient that dissipates charges before they accumulate on the liquid repellent layer surface.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The nozzle plate surface is constructed as a composite structure with multiple layers: a substrate, an intermediate layer with specific electrical properties, and a liquid repellent layer. This composite structure combines the liquid repellency of the fluorine-containing compound with the charge dissipation capability of the intermediate layer, resolving the contradiction between repellency and charge accumulation.

Inventive Principle:

Principle #40Composite materials

2Reliability

If a metal substrate is used to provide conductivity, then charge dissipation is improved, but adaptability is reduced due to material limitations

Engineering Contradiction:

Improvecharge dissipationVSAvoidmaterial selection flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

Instead of changing the substrate material to metal, the invention changes the electrical conductivity parameter by introducing an intermediate layer with controlled electrical properties. This allows the substrate to remain as flexible polymer materials while achieving the necessary charge dissipation through the intermediate layer's electrical conductivity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The intermediate layer serves as an intermediary that provides the electrical conductivity function without requiring the substrate itself to be conductive. This mediator layer enables charge dissipation while preserving the advantages of polymer substrates, including flexibility and ease of manufacturing.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If a nozzle cover is added to prevent ink adhesion, then ejection stability is improved, but gap control precision deteriorates due to protrusion

Engineering Contradiction:

Improveejection stabilityVSAvoidgap control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The invention extracts the ink adhesion prevention function from the mechanical nozzle cover structure and transfers it to the liquid repellent layer on the nozzle plate surface. This eliminates the need for the protruding nozzle cover, maintaining gap control precision while preserving ejection stability through the surface treatment.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The mechanical solution of using a physical nozzle cover is replaced with a surface chemistry solution using liquid repellent layers. This substitution eliminates the mechanical protrusion that interferes with gap control while maintaining the protective function against ink adhesion through chemical surface properties.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 configuration enhances ejection stability and prevents ink mist accumulation, ensuring high-quality inkjet recording images by effectively managing electrical charges and maintaining a stable ink discharge surface.

Implementation Method 1

the conductive layer quickly dissipates charges

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

liquid repellent layer on an outermost surface of the substrate on an ink discharge surface side

Methodology Applied

Scientific EffectLiquid repellency: Hydrophobe

Data Source

PatentUS11807004B2Inkjet head and image forming method

Publication Date: 2023.11.07 KONICA MINOLTA INC

AI summary

Provided is an inkjet head containing: a substrate having a nozzle hole, and a nozzle plate having a liquid repellent layer on an outermost surface of the substrate on an ink discharge surface side, wherein the nozzle plate has a conductive layer between the substrate and the liquid repellent layer.