Dual Cap Inkjet Nozzle Sealing to Prevent Droplet Splashing

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Solution Overview

Problem

Ink jet recording apparatuses face ejection failure due to splashing droplets containing air bubbles that reach the nozzle openings, caused by the capillary force acting on the space between the cap member and the nozzle face during cap opening operations, leading to reduced pressure and ink flow path contamination.

Innovation Solution

The apparatus incorporates a cap member with an outer cap portion and an inner cap portion, where the inner cap portion has cutouts to divide the liquid film, preventing splashing droplets from reaching the nozzle openings by maintaining a thicker liquid film on the inner cap portion, which absorbs the splashing droplets and releases negative pressure, thus preventing ejection failure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a cap member is used to seal the nozzle openings during non-printing periods, then ink evaporation and clogging are prevented, but liquid film formation and splashing droplet generation occur during cap opening operations

Engineering Contradiction:

Improveprevention of ink evaporation and cloggingVSAvoidsplashing droplets containing air bubbles

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The cap member is divided into an outer cap portion and an inner cap portion, creating multiple sealing zones. The inner cap portion seals the nozzle openings directly, while the outer cap portion provides additional sealing and absorbs splashing droplets, preventing them from reaching the nozzle openings.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The liquid film formed between the cap member and nozzle face acts as an intermediary layer. By controlling the thickness of this liquid film through the dual-cap structure, the patent prevents direct contact between splashing droplets and nozzle openings while maintaining the sealing function.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If the cap member is separated from the nozzle face during cap opening operation, then the cap opening operation is completed, but negative pressure is generated and liquid film breaks forming splashing droplets

Engineering Contradiction:

Improvecap opening operationVSAvoidmaintenance of ink flow path integrity

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The inner cap portion is positioned to maintain contact with the nozzle face during the cap opening operation, creating a cushioning effect that prevents the liquid film from breaking. This beforehand cushioning ensures that even when the outer cap portion is separated, the inner sealing mechanism maintains ink flow path integrity.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Device complexity

If a single cap portion is used, then the device complexity is low, but the liquid film becomes thin and breaks easily during cap opening operations

Engineering Contradiction:

Improvecap member structureVSAvoidliquid film thickness

Core Design Contradiction:

Device complexityVSStability of the object's composition

Solution Approach 1:

The cap member is segmented into two functional portions: the inner cap portion that maintains liquid film thickness by contacting the nozzle face, and the outer cap portion that provides additional sealing and absorbs splashing droplets. This segmentation allows each portion to perform its specific function optimally.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the cap member have different functions and properties. The inner cap portion is designed to maintain liquid film thickness, while the outer cap portion is designed to absorb splashing droplets. This local differentiation of function resolves the contradiction between device complexity and liquid film stability.

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

This configuration effectively prevents splashing droplets from reaching the nozzle openings, maintaining the integrity of the ink flow and preventing ejection failure by ensuring that the liquid film formed between the inner cap portion and the nozzle face remains intact, even when the outer cap portion's film breaks, thereby maintaining the pressure and flow path cleanliness.

Implementation Method 1

a cap member which forms a space by abutting against the nozzle face and receives liquid ejected through the nozzle openings in a state where the space is in a negative pressure

Methodology Applied

Scientific EffectNegative pressure: Pressure Drop

Implementation Method 2

The liquid film is formed when a capillary force acts on the space due to viscosity of the liquid droplets and the space has such a size that the capillary force acts thereon

Methodology Applied

Scientific EffectCapillary force: Capillary Action

Data Source

PatentUS8740346B2Liquid ejecting apparatus

Publication Date: 2014.06.03 SEIKO EPSON CORP

AI summary

When an ink film between an outer cap and a nozzle face is broken, an ink film formed between an inner cap and the nozzle face is not broken for the following reason. That is, when the ink film between the outer cap and the nozzle face is broken, a negative pressure is not generated on a space formed by the inner cap because the ink film between the inner cap and the nozzle face is formed to be thick and the space communicates with the outside environment by cutouts. Therefore, the ink film formed on the inner cap is not broken at a time when the ink film formed on the outer cap is broken to the inner side with a negative pressure. This makes it possible to suppress splashing droplets from traveling to nozzle rows.