Sub Tank Valve for Ink Leakage Prevention

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Solution Overview

Problem

Inkjet recording devices face issues with ink leakage from a sub tank when the main tank is detached, as the sub tank is open to the atmosphere, leading to potential ink loss during tank exchange, especially when residual ink is present.

Innovation Solution

A liquid ejection device with a sub tank that includes a valve to selectively open and close an atmosphere opening, ensuring the sub tank remains sealed when the main tank is detached, preventing ink leakage by maintaining a negative pressure inside the sub tank and using a labyrinth flow path for gas-liquid separation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the sub tank is open to the atmosphere to enable gas-liquid separation and prevent air entry into the ink supply path, then air can be separated from ink effectively, but ink may leak out when the main tank is detached

Engineering Contradiction:

Improvegas-liquid separation functionVSAvoidink leakage

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The valve is activated in advance upon detection of main tank detachment to close the atmosphere opening before ink leakage can occur. The control unit detects the detachment state and preemptively closes the valve to prevent the harmful effect of ink leakage while maintaining the beneficial gas-liquid separation function when connected.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses a sensor to detect whether the main tank is connected or detached, and this feedback signal controls the valve operation. When detachment is detected, the valve closes to prevent ink leakage; when connected, the valve opens to enable gas-liquid separation. This feedback mechanism dynamically adjusts the system state based on operational conditions.

Inventive Principle:

Principle #23Feedback

2Productivity

If the ink inlet is positioned at the lower position of the sub tank to maximize ink supply and gas-liquid separation efficiency, then ink can be fully utilized and air separation is improved, but the risk of ink leakage increases when the main tank is detached

Engineering Contradiction:

Improveink supply efficiencyVSAvoidink leakage risk

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The valve acts as an intermediary mechanism between the atmosphere opening and the ink-containing environment. It mediates between the need for gas-liquid separation (requiring open atmosphere access) and the need to prevent ink leakage (requiring sealed atmosphere access), allowing the system to switch between these conflicting requirements based on operational state.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Loss of substance

If the sub tank maintains a sealed state to prevent ink leakage, then ink loss is minimized, but air cannot be separated from ink and may enter the ejection head

Engineering Contradiction:

Improveink loss preventionVSAvoidair separation function

Core Design Contradiction:

Loss of substanceVSReliability

Solution Approach 1:

The system transitions from a static sealed or open state to a dynamic state where the atmosphere opening can be selectively opened or closed based on operational requirements. The valve enables the system to adapt its sealing state dynamically, being sealed when preventing ink loss is critical and open when gas-liquid separation is needed.

Inventive Principle:

Principle #15Dynamics

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 prevents ink leakage during main tank detachment and ensures smooth ink supply by maintaining a sealed state and utilizing gas-liquid separation to manage air entry, ensuring reliable operation and minimizing ink loss.

Implementation Method 1

maintaining a negative pressure inside the sub tank and using a labyrinth flow path for gas-liquid separation

Methodology Applied

Scientific EffectNegative pressure: Pressure Gradient

Implementation Method 2

air may enter into a connection portion between the main tank and the sub tank during exchange of the main tank, since the sub tank is open to the atmosphere, the entered air moves along with the ink into sub tank and thereafter is separated from the ink due to its buoyancy and then discharged to the exterior

Methodology Applied

Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Data Source

PatentUS8186815B2Liquid ejection device and sub tank for use with the same

Publication Date: 2012.05.29 BROTHER KOGYO KK

AI summary

A liquid ejection device is connectable to a main tank. The liquid ejection device includes an ejection head; and a sub tank having an inner space defined therein and including a connection portion configured to connect the inner space with the main tank. The sub tank includes a liquid inlet through which the liquid is allowed to flow from the main tank into the inner space when the main tank is connected to the connection portion; an atmosphere opening that communicates between an outside of the sub tank and the inner space; and a valve configured to selectively open and close the atmosphere opening. The valve opens the atmosphere opening in a state where the main tank is connected to the connection portion and closes the atmosphere opening in a state where the main tank is not connected to the connection portion.