Liquid Ejecting Head Three-Electrode Segmentation for Kogation Control

Solution Overview

Problem

Existing liquid ejecting heads face instability and kogation issues due to heat-generated ink components adhering to heating resistors, leading to reduced thermal conductivity and operational instability, despite previous methods incorporating polarity-matched molecules or electrode configuration changes which can cause anodization and electrode degradation.

Innovation Solution

A liquid ejecting head with a configuration of three electrodes: a first electrode covering the heating resistor, a second electrode positioned differently, and a third electrode for cleaning, where voltage polarity is switched between these electrodes to prevent ink component adherence and maintain electrode functionality without causing anodization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an upper electrode and opposite electrode are placed to release ink colloid particles from the heating resistor layer, then kogation is prevented, but colloidal particles adhere to the opposite electrode

Engineering Contradiction:

Improveejecting operation stabilityVSAvoidcolloidal particle adherence to opposite electrode

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The electrode system is divided into three separate electrodes: a first electrode (upper electrode) covering the heating resistor, a second electrode (opposite electrode) positioned away from the first electrode, and a third electrode (cleaning electrode) positioned away from both the first and second electrodes. This segmentation allows each electrode to have specialized functions, with the third electrode specifically dedicated to cleaning the second electrode of adhered colloidal particles.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The third electrode acts as an intermediary cleaning mechanism. By applying voltage between the second electrode and third electrode, colloidal particles adhering to the second electrode are released and moved toward the third electrode, preventing accumulation on the opposite electrode while maintaining the primary electrode configuration for ink ejection.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-generated harmful factors

If molecules smaller than colloidal particles are incorporated into ink, then colloidal particles are unlikely to adhere to the opposite electrode, but multiple small molecules are drawn to the opposite electrode

Engineering Contradiction:

Improvecolloidal particle adherenceVSAvoidfunctional area of opposite electrode

Core Design Contradiction:

Object-generated harmful factorsVSArea of stationary object

Solution Approach 1:

The electrode system is divided into three separate electrodes: a first electrode (upper electrode) covering the heating resistor, a second electrode (opposite electrode) positioned away from the first electrode, and a third electrode (cleaning electrode) positioned away from both the first and second electrodes. This segmentation allows each electrode to have specialized functions, with the third electrode specifically dedicated to cleaning the second electrode of adhered colloidal particles.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The third electrode provides self-cleaning functionality to the second electrode. By periodically applying voltage between the second and third electrodes, the system automatically removes accumulated colloidal particles and small molecules from the second electrode surface, maintaining its functional area without manual intervention.

Inventive Principle:

Principle #25Self-service

3Duration of action of stationary object

If voltage polarity is switched between upper electrode and opposite electrode, then anodization reaction occurs and upper electrode melts, but this extends electrode lifetime

Engineering Contradiction:

Improveliquid ejecting head lifetimeVSAvoidanodization reaction and electrode melting

Core Design Contradiction:

Duration of action of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The electrode system is divided into three separate electrodes: a first electrode (upper electrode) covering the heating resistor, a second electrode (opposite electrode) positioned away from the first electrode, and a third electrode (cleaning electrode) positioned away from both the first and second electrodes. This segmentation allows each electrode to have specialized functions, with the third electrode specifically dedicated to cleaning the second electrode of adhered colloidal particles.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cleaning function is extracted from the primary electrode system. Instead of using the first and second electrodes for both ejection and cleaning functions, the third electrode is introduced to handle cleaning separately. This allows the first electrode to focus on ejection without undergoing damaging anodization reactions during cleaning cycles.

Inventive Principle:

Principle #2Taking out (Extraction)

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 enables stable long-term ejecting operations without kogation by effectively managing ink component adherence and preventing electrode degradation, ensuring consistent performance.

Implementation Method 1

a heating resistor to generate thermal energy for ejecting the liquid

Methodology Applied

Scientific EffectFilm boiling: Boiling

Implementation Method 2

applying a voltage to a heating resistor to induce film boiling in liquid, resulting in liquid ejection using the growth energy of bubbles

Methodology Applied

Scientific EffectBubble growth: Bubble

Implementation Method 3

a voltage is applied between the first electrode and the second electrode so that the first electrode has same polarity as polarity of a predetermined component included in the liquid, and the second electrode has polarity opposite to the polarity of the predetermined component

Methodology Applied

Scientific EffectElectrostatic force: Electrostatics

Implementation Method 4

a voltage is applied between the second electrode and the third electrode so that the second electrode has same polarity as the polarity of the predetermined component, and the third electrode has polarity opposite to the polarity of the predetermined component

Methodology Applied

Scientific EffectElectrostatic force: Electrostatics

Data Source

PatentUS10434777B2Liquid ejecting head, cleaning method, and liquid ejecting apparatus

Publication Date: 2019.10.08 CANON KK

AI summary

A liquid ejecting head maintains stable ejecting operations without causing kogation. To achieve such operations, the liquid ejecting head includes, in its liquid chamber, a first electrode placed so as to cover a heating resistor, a second electrode placed at a position different from that of the first electrode, and a third electrode. In a case where the heating resistor is driven, a voltage is applied between the first electrode and the second electrode so that the first electrode has the same polarity as that of a predetermined liquid component, and the second electrode has the opposite polarity. In a case where the heating resistor is not driven, a voltage is applied between the second electrode and the third electrode so that the second electrode has the same polarity as that of the predetermined component, and the third electrode has the opposite polarity.