Liquid Ejecting Apparatus Tank Overflow Management

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Solution Overview

Problem

Existing liquid ejecting apparatuses face failures due to accidental leakage of ink from tanks, leading to potential clogging of air pumps and color mixing issues, particularly when the ink supply valve or liquid level sensor malfunctions.

Innovation Solution

A liquid ejecting apparatus with a configuration that includes a first tank, a second tank, and a circulation path, where the second tank has a second opening positioned lower than the first opening, allowing over-supplied ink to overflow through a second atmosphere opening valve, preventing it from reaching the second pressure adjusting unit and reducing the risk of pump failure and color mixing. Additionally, a main tank supplies ink continuously, and valves are designed to manage flow paths to minimize overflow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If ink is excessively supplied to the negative pressure side sub-tank due to valve or sensor failure, then the ink circulation system continues to operate, but the air pump draws in ink and fails

Engineering Contradiction:
Improvecontinuous operation of ink circulation systemVSAvoidair pump failure due to ink ingestion
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

A gas-liquid separator is introduced as an intermediary component between the negative pressure side sub-tank and the air pump. This separator acts as a protective barrier that prevents ink from reaching the air pump while allowing the air circulation function to continue, thus resolving the contradiction between continuous operation and pump reliability

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The gas-liquid separator is positioned in advance before the air pump to cushion against potential ink overflow. By placing this protective component beforehand in the flow path, the system prepares for possible failures of the ink supply valve or liquid level sensor, preventing ink from reaching the air pump even when excessive ink is supplied to the sub-tank

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Productivity

If ink is excessively supplied to the negative pressure side sub-tank, then the ink circulation system continues to operate, but color mixing occurs in the sub-tank

Engineering Contradiction:
Improvecontinuous operation of ink circulation systemVSAvoidcolor mixing of ink in sub-tank
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The gas-liquid separator serves as an intermediary that not only protects the air pump but also helps maintain ink composition stability. By separating gases from liquids and controlling the interface, it prevents turbulent mixing of different ink colors in the negative pressure side sub-tank, thus resolving the contradiction between continuous operation and ink composition stability

Inventive Principle:
Principle #24Intermediary (Mediator)

3Device complexity

If a single opening is provided in the second tank for both pressure adjustment and atmosphere communication, then the device structure is simplified, but liquid may accidentally leak from the tank

Engineering Contradiction:
Improvesimplified tank structure with single openingVSAvoidaccidental liquid leakage from tank
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The single opening in the second tank is segmented into two separate openings: one dedicated to pressure adjustment and another for atmosphere communication. This segmentation allows each opening to be optimized for its specific function and includes separate control mechanisms, preventing accidental leakage while maintaining relatively simple overall structure

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different local qualities are assigned to different openings in the second tank. The first opening is equipped with specific pressure control characteristics while the second opening has atmosphere communication characteristics. This local differentiation ensures that each opening performs its function reliably without causing accidental liquid leakage, resolving the contradiction between structural simplicity and reliability

Inventive Principle:
Principle #3Local quality

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 ink overflow into the air pump and reduces the risk of color mixing, ensuring stable operation and continuous printing by managing ink flow and overflow through strategic valve and tank positioning.

Implementation Method 1

the second tank has a second opening arranged at a position lower than the first opening in the vertical direction

Methodology Applied
Scientific EffectGravity: Gravitation

Data Source

PatentEP3369578B1Liquid ejecting apparatus
Publication Date: 2019.07.10 SEIKO EPSON CORP
  • EP3369578B1 patent drawingFigure 1
  • EP3369578B1 patent drawingFigure 2
  • EP3369578B1 patent drawingFigure 3

AI summary

A liquid ejecting apparatus includes a first tank that stores liquid to be supplied to a liquid ejecting head, a second tank that receives liquid that has not been ejected by the liquid ejecting head, and a circulation path that circulates liquid. The second tank separately has a first opening that communicates with a second pressure adjusting unit that can depressurize the second tank and a second opening that communicates with a second atmosphere opening valve that switches the second tank between a sealed state and an atmosphere opening state. The second opening is arranged at a position lower than the first opening in a vertical direction.