Liquid Ejecting Head Sloped Flow Passages Air Bubble Prevention

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Solution Overview

Problem

Existing liquid ejecting heads face ejection abnormalities due to air bubbles forming in the flow passages, leading to difficulties in ejecting ink from nozzles, which can result in poor print quality and increased ink viscosity.

Innovation Solution

The liquid ejecting head design incorporates sloped portions in the pressure compartments and communication flow passages to facilitate smooth ink flow, preventing air bubbles from becoming trapped and ensuring consistent ink ejection by maintaining pressure compartment communication through sloped surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional flow passage design is used, then device complexity is reduced, but air bubbles become trapped causing ejection abnormalities

Engineering Contradiction:

Improveejection reliabilityVSAvoidflow passage structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies curved surfaces and sloped portions within the flow passage to prevent air bubble entrapment. The communication flow passage includes sloped portions that create smooth transitions between different passage sections, eliminating sharp corners where air bubbles could accumulate. This curvature principle modifies the conventional straight-angle flow passages to ensure reliable liquid ejection without introducing complex mechanical components.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Reliability

If sloped portions are added to flow passages, then air bubble entrapment is prevented, but manufacturing complexity increases

Engineering Contradiction:

Improveink flow consistencyVSAvoidflow passage fabrication

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The sloped portions are integrated directly into the flow passage structure as continuous curved surfaces rather than separate components. This approach maintains manufacturing feasibility by using standard molding or machining processes capable of creating smooth transitions, while effectively preventing air bubble entrapment through the eliminated sharp corners and crevices.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Reliability

If air bubbles are present in flow passage, then ejection abnormality occurs, but increasing pressure to remove bubbles increases ink viscosity

Engineering Contradiction:

Improvenozzle ejection performanceVSAvoidink viscosity increase

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the potential harm of air bubbles by designing the flow passage to actively guide and eliminate them through sloped portions that direct air bubbles toward designated escape paths. This prevents bubble accumulation without requiring excessive pressure that would increase ink viscosity, as the structural design inherently facilitates bubble removal during normal operation.

Inventive Principle:

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

Data Source

PatentUS11554584B2Liquid ejecting head and liquid ejecting apparatus

Publication Date: 2023.01.17 SEIKO EPSON CORP

AI summary

a first sloped portion that is provided between the first wall surface and the third wall surface includes a first constituting surface that extends in a third direction between the first direction and the second direction.