Liquid Ejection Apparatus Air Bubble Elimination

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Solution Overview

Problem

Existing liquid ejection apparatuses face challenges in eliminating air bubbles from individual channels without increasing liquid consumption, as purging methods can be inefficient and do not effectively address stagnant air bubbles.

Innovation Solution

A liquid ejection apparatus with a pump assembly and controller that draws air into individual channels through nozzles and applies pressure to eliminate air bubbles by forcing air into stagnant areas and circulating ink, allowing for air bubble removal without significant ink consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If purging is performed to eliminate air bubbles from individual channels, then air bubbles are removed, but liquid consumption increases

Engineering Contradiction:

Improveair bubble eliminationVSAvoidliquid consumption

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

Instead of forcing liquid through the channel to push air bubbles out (conventional purging), the invention reverses the approach by introducing air into the channel through the nozzle to displace and remove air bubbles. The pump draws air from the atmosphere through the nozzle into the individual channel, pushing air bubbles toward the feedback channel where they are evacuated, thereby eliminating bubbles without consuming additional liquid.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

Air acts as an intermediary substance to eliminate air bubbles. By introducing air through the nozzle, the system uses air as a mediator to push existing air bubbles through the channel and out through the feedback channel, avoiding the need to use liquid for purging and thus preventing liquid consumption.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If conventional circulation is used, then liquid flows through channels, but air bubbles in stagnant areas remain

Engineering Contradiction:

Improveliquid circulationVSAvoidair bubble elimination completeness

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

Rather than relying on liquid circulation to move air bubbles (which fails in stagnant areas), the invention introduces air flow from the nozzle end through the channel, reversing the conventional approach. This air injection method actively pushes air bubbles out of stagnant areas and through the entire channel length, including regions that liquid circulation cannot reach effectively.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The system performs periodic air introduction cycles through the nozzle, alternating with normal operation. During these periodic purging cycles, air is drawn through the individual channels to eliminate accumulated air bubbles, ensuring complete removal without requiring continuous liquid consumption or complex circulation modifications.

Inventive Principle:

Principle #19Periodic action

3Reliability

If purging is performed frequently, then air bubbles are removed, but operational time is lost

Engineering Contradiction:

Improveair bubble eliminationVSAvoidpurging time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system incorporates automatic detection and self-purging functionality. The controller monitors for air bubble presence in the individual channels and automatically initiates air introduction purging cycles only when needed, without requiring manual intervention or continuous operation. This self-service approach eliminates air bubbles efficiently while minimizing interruption to normal operations.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system uses feedback control to manage purging operations. The controller receives information about air bubble presence (through sensors or detection mechanisms) and adjusts purging frequency accordingly, initiating air introduction cycles only when air bubbles are detected. This feedback-based approach optimizes the balance between air bubble elimination and operational time, preventing unnecessary purging interruptions.

Inventive Principle:

Principle #23Feedback

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

Effectively removes air bubbles from individual channels without increasing liquid consumption, ensuring reliable operation and maintaining menisci in nozzles while minimizing ink discharge.

Implementation Method 1

The controller configures to drive the pump assembly to draw air into the individual channel through the nozzle

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Implementation Method 2

The controller configures to drive the pump assembly to apply a pressure in the individual channel from the feed channel toward the feedback channel

Methodology Applied

Scientific EffectPressure: Pressure Increase

Data Source

PatentUS10543690B2Liquid ejection apparatus

Publication Date: 2020.01.28 BROTHER KOGYO KK

AI summary

A liquid ejection apparatus includes a head that defines an individual channel including a nozzle, a feed channel communicating a reservoir and an inlet port of the individual channel, and a feedback channel communicating the reservoir and an outlet port of the individual channel. A pump assembly has at least one pump. A controller is configured to drive the pump assembly to draw air into the individual channel through the nozzle, and to drive the pump assembly to apply a pressure in the individual channel from the feed channel toward the feedback channel.