Liquid Ejection Head Energy Inspection Without Ink Ejection

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Solution Overview

Problem

Existing methods for setting ejection energy in liquid ejection heads require actual liquid ejection and dedicated wiring for capacitance measurement, complicating the manufacturing process and increasing costs.

Innovation Solution

A method and apparatus for inspecting liquid ejection energy by measuring the electrical resistance value and film thickness of electrothermal converters without changing the substrate wiring, using film thickness monitor portions to calculate the necessary ejection energy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If actual liquid ejection is performed to set ejection energy, then ejection energy can be accurately determined, but the manufacturing process becomes more complex and time-consuming due to additional steps for ink supply and cleaning

Engineering Contradiction:

Improveejection energy determination accuracyVSAvoidmanufacturing process complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The invention performs preliminary measurements of electrical resistance and film thickness during the manufacturing process to determine ejection energy before actual liquid ejection is required. This allows ejection energy settings to be established in advance using non-intrusive electrical measurements, eliminating the need for subsequent ink supply and cleaning operations that would otherwise be necessary for accurate ejection energy determination.

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If capacitance measurement is used to estimate film thickness, then ejection energy can be determined without liquid ejection, but dedicated wiring and measurement electrodes must be added to the substrate

Engineering Contradiction:

Improvemanufacturing process simplificationVSAvoidwiring complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The invention extracts the essential measurement parameters (electrical resistance and film thickness) from the complex capacitance measurement approach. By measuring electrical resistance through existing wiring and combining it with film thickness measurements, the method eliminates the need for dedicated capacitance measurement wiring and electrodes, thereby simplifying the device structure while maintaining the ability to determine ejection energy without liquid ejection.

Inventive Principle:

Principle #2Taking out (Extraction)

3Measurement precision

If ink supply and cleaning steps are added to the manufacturing process, then accurate ejection energy measurement is achieved, but productivity decreases and manufacturing costs increase

Engineering Contradiction:

Improveejection energy measurement accuracyVSAvoidmanufacturing throughput

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The invention replaces mechanical liquid ejection operations with electrical measurements. Instead of physically ejecting ink to measure ejection energy, the method uses electrical resistance measurements combined with film thickness data to calculate the required ejection energy. This substitution eliminates the need for ink supply and cleaning steps, thereby increasing manufacturing throughput and reducing associated costs while maintaining measurement accuracy.

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

Accurately determines ejection energy without actual liquid ejection, simplifying the manufacturing process, reducing costs, and enabling smaller manufacturing facilities.

Implementation Method 1

heat generation portion having an electrothermal converter provided on a first surface of the substrate

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

acquiring, as a first measurement result, an electrical resistance value of the electrothermal converter

Methodology Applied

Scientific EffectElectrical resistance measurement: Electrical Resistance

Data Source

PatentUS12365177B2Liquid ejection head inspection method, liquid ejection head inspection apparatus, and ejection element substrate

Publication Date: 2025.07.22 CANON KK

AI summary

Provided is a technique which can inspect liquid ejection energy without changing electric wiring on an ejection element substrate of a liquid ejection head or ejecting liquid from the liquid ejection head. A liquid ejection head as an ejection-energy inspection target includes an ejection element substrate having a substrate, a heat generation portion having an electrothermal converter on the substrate, a protective film covering the electrothermal converter, and an organic layer covering the electrothermal converter and the protective film. For this liquid ejection head, an electrical resistance value of the electrothermal converter is acquired as a first measurement result, and the film thickness of a film thickness measurement portion of the ejection element substrate where the protective film is exposed is acquired as a second measurement result. Further, information on ejection energy needed to eject liquid from the ejection port is obtained based on the first and second measurement results.