Dual-Adhesive Liquid Ejecting Head Bubble Elimination

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Solution Overview

Problem

Ink jet type recording heads face issues with bubble elimination in pressure-generating chambers due to low affinity between adhesive substrates and ink, leading to printing defects and reduced discharge characteristics, as bubbles adhere to adhesive surfaces and are not effectively removed by low-flow-rate cleaning.

Innovation Solution

A liquid ejecting head design utilizing two types of adhesives: a first adhesive with low affinity for ink on the upstream side to absorb and aggregate bubbles, preventing them from entering the pressure-generating chamber, and a second adhesive with higher affinity on the downstream side to ensure bubble elimination during low-flow-rate cleaning, thereby maintaining discharge characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single adhesive with low affinity for ink is used in the pressure-generating chamber, then bubbles can be adsorbed and aggregated for elimination, but the adhesive property is insufficient for reliable substrate bonding

Engineering Contradiction:

Improvebubble elimination capabilityVSAvoidadhesive bonding strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The adhesive application area is segmented into two distinct zones: a first adhesive region on the upstream side with low ink affinity for bubble adsorption, and a second adhesive region on the downstream side with high ink affinity for reliable bonding. This segmentation allows each zone to perform its specific function optimally without compromise

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different adhesive properties are assigned to different locations within the pressure-generating chamber. The upstream region uses adhesive with low ink affinity (high bubble affinity) while the downstream region uses adhesive with high ink affinity, creating local quality variations that solve both bubble elimination and bonding strength requirements

Inventive Principle:

Principle #3Local quality

2Reliability

If the affinity of ink itself is increased to prevent bubble adhesion, then bubbles may be eliminated more easily, but the flexibility in design is reduced

Engineering Contradiction:

Improvebubble elimination capabilityVSAvoiddesign flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The adhesive serves as an intermediary substance between the substrate and the ink/bubbles. By controlling the adhesive's affinity characteristics, bubble elimination is achieved without requiring changes to the ink formulation, thereby preserving design flexibility in the ink system while still solving the bubble adhesion problem

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If high-flow-rate cleaning is used to eliminate bubbles, then bubbles can be removed more effectively, but the risk of damaging delicate components and reducing discharge characteristics increases

Engineering Contradiction:

Improvebubble elimination capabilityVSAvoiddischarge characteristics

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The adhesive with low ink affinity, which initially appears harmful due to potential bubble adhesion issues, is actually converted into a beneficial element by deliberately positioning it in the upstream region where it actively adsorbs and aggregates bubbles for easy elimination, thereby protecting the discharge characteristics from damage

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 dual-adhesive approach effectively eliminates bubbles, preventing them from entering the pressure-generating chamber and enhancing discharge characteristics, thus improving bubble-eliminating properties and maintaining printing quality.

Implementation Method 1

the first adhesive having low affinity with a liquid continuously adsorbs bubbles to aggregate the bubbles and make the size of the bubbles larger

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

the adhesive being exposed to the wall surface of the downstream-side passage including the pressure-generating chamber is composed of a second adhesive having affinity higher than that of the first adhesive, bubbles are not adsorbed to the adhesive in the pressure-generating chamber

Methodology Applied

Scientific EffectSurface affinity: Surface Tension

Data Source

PatentUS8215752B2Liquid ejecting head and liquid ejecting apparatus

Publication Date: 2012.07.10 SEIKO EPSON CORP

AI summary

Provided is a liquid ejecting head including a plurality of substrates that are at least partially bonded to one another with adhesives and form a liquid passage in which a liquid flows. The liquid passage includes a pressure-generating chamber that communicates to a nozzle opening through which the liquid is ejected. The adhesive being exposed to a wall surface of the passage on the upstream side of the pressure-generating chamber is composed of a first adhesive, and the adhesive being exposed to a wall surface of the downstream-side passage including the pressure-generating chamber is composed of a second adhesive. The second adhesive has affinity with the liquid higher than that of the first adhesive.