Liquid Ejecting Head Compliance Section for Bubble Pressure Management

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Solution Overview

Problem

The meniscus at the nozzle opening of liquid ejecting heads, such as ink jet recording heads, is prone to destruction due to increased pressure from expanding air bubbles in the bubble chamber, leading to ink leakage and poor printing quality, especially when ambient temperature changes.

Innovation Solution

A compliance section is introduced upstream of the bubble chamber, which absorbs volume changes caused by temperature variations, maintaining pressure on the meniscus within its withstand-pressure limits and preventing destruction. This compliance section can be a flexible film that acts as a self-sealing valve, opening and closing to manage pressure changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If air bubbles are stored in the bubble chamber to suppress filter blocking, then filter effectiveness is improved, but pressure increases causing meniscus destruction

Engineering Contradiction:

Improvefilter effectivenessVSAvoidpressure inside liquid flow path

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The flow path member is divided into functional sections: a bubble chamber section for storing air bubbles to protect the filter, and a compliance section for absorbing pressure changes. This segmentation allows each section to perform its specific function without interfering with the other, resolving the contradiction between filter protection and pressure control.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The compliance section acts as an intermediary element between the bubble chamber and the nozzle opening. It absorbs the pressure increases caused by expanding air bubbles, preventing this pressure from reaching the meniscus and causing destruction, while still allowing the bubble chamber to fulfill its filter protection function.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If air bubble volume increases to suppress pressure during ejection, then ejection stability is improved, but meniscus withstand-pressure is exceeded during non-use

Engineering Contradiction:

Improveejection stabilityVSAvoidmeniscus destruction

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The compliance section is designed to absorb pressure changes beforehand during non-use periods when temperature variations occur. By cushioning the pressure increases caused by thermal expansion of air bubbles before they reach the meniscus, the system prevents meniscus destruction while maintaining the bubble chamber's ability to provide stability during ejection.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Productivity

If bubble chamber volume is increased to reduce head cleaning frequency, then maintenance interval is extended, but pressure control becomes more difficult

Engineering Contradiction:

Improvehead cleaning intervalVSAvoidpressure inside liquid flow path

Core Design Contradiction:

ProductivityVSStress or pressure

Solution Approach 1:

By segmenting the flow path member into a bubble chamber section and a compliance section, the system can accommodate a larger bubble chamber volume for extended maintenance intervals while the compliance section manages the pressure control, preventing excessive pressure from reaching the nozzle opening.

Inventive Principle:

Principle #1Segmentation

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 solution effectively prevents meniscus destruction, reduces ink leakage, and extends the interval between required head cleanings, improving printing efficiency and quality, especially during non-use periods when temperature changes are significant.

Implementation Method 1

the air bubbles, which grow in the bubble chamber and then the volume of which increases, are further expanded, resulting from gas expansion due to a change in the ambient temperature

Methodology Applied

Scientific EffectGas expansion: Thermal Expansion

Implementation Method 2

when the pressure of the ink inside the ink flow path increases and the pressure inside the ink flow path exceeds meniscus withstand-pressure of the ink in the nozzle opening, the meniscus is destroyed

Methodology Applied

Scientific EffectPressure change: Pressure Increase

Data Source

PatentUS8678559B2Liquid ejecting head and liquid ejecting apparatus

Publication Date: 2014.03.25 SEIKO EPSON CORP

AI summary

A liquid ejecting head includes a head body; and a flow path member having a liquid flow path circulating a liquid, supplied from a liquid storage unit, and a bubble chamber formed in the middle of the liquid flow path and in which air bubbles are caused to stay, wherein a compliance section (a sealing film) displaced according to a volume change in the air bubbles inside the bubble chamber is formed at upstream side of the bubble chamber so that an amount of the volume change in the compliance section due to the displacement of the compliance section is larger than an amount of a volume change in the air bubbles due to a change in the ambient temperature.