Liquid Jetting Head Humidity Sensor Contamination Prevention

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Solution Overview

Problem

Existing liquid jetting heads face challenges in maintaining stable humidity detection due to contamination of humidity sensors during dummy jetting and nozzle wiping, as ink mist and wiping liquids can adhere to or contaminate the sensors, disrupting accurate humidity measurement.

Innovation Solution

The implementation of a humidity sensor positioned further inside than the nozzle face, connected via air intake ports and nonlinear connection passages, with a contamination prevention mechanism that includes an air pump to maintain a clean air pathway, preventing ink and liquid from reaching the sensor during operations like dummy jetting and wiping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the humidity sensor is disposed near the nozzle face to detect ambient humidity, then the humidity detection capability is improved, but the sensor is contaminated by ink mist during dummy jetting and wiping liquid during nozzle wiping

Engineering Contradiction:

Improvehumidity detection capabilityVSAvoidsensor contamination

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

A nonlinear connection passage serves as an intermediary between the air intake port and humidity sensor. This passage includes a bypass portion that extends in a direction substantially perpendicular to the nozzle jetting direction, allowing air to reach the sensor while preventing direct contact with ink mist and wiping liquid. The bypass portion acts as a mediator that separates the sensor from harmful contaminants.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The connection passage is designed with a three-dimensional nonlinear path including a bypass portion that extends perpendicular to the nozzle jetting direction. This dimensional change in the air flow path allows the sensor to be positioned inside the nozzle face region while maintaining separation from contaminants through the vertical bypass component.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Object-affected harmful factors

If the humidity sensor is disposed inside the nozzle face, then the sensor is protected from contamination, but the responsiveness of humidity detection may be reduced due to the connection passage length

Engineering Contradiction:

Improvesensor contamination protectionVSAvoidhumidity detection responsiveness

Core Design Contradiction:

Object-affected harmful factorsVSSpeed

Solution Approach 1:

The connection passage includes a curved nonlinear path with a bypass portion that efficiently redirects air flow in a three-dimensional curve. This curved design allows the air to reach the sensor through the bypass portion without requiring an excessively long straight path, maintaining responsiveness while providing contamination protection.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Device complexity

If a linear connection passage is used between air intake port and humidity sensor, then the structure is simple, but ink mist and wiping liquid can directly reach the sensor causing contamination

Engineering Contradiction:

Improveconnection passage structureVSAvoidsensor contamination

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The connection passage is segmented into multiple portions including a bypass portion that extends perpendicular to the nozzle jetting direction. This segmentation creates distinct zones within the passage: a first portion for air intake and a second portion for sensor connection, separated by the bypass portion that blocks direct contaminant access while maintaining air flow.

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

This configuration effectively prevents sensor contamination, ensuring stable and accurate humidity detection even during prolonged operations and varying nozzle conditions, maintaining the humidity levels and preventing nozzle face drying.

Implementation Method 1

a contamination preventing part that prevents contamination of the humidity sensor

Methodology Applied

Scientific EffectAir pump pressurization: Pressurisation

Implementation Method 2

a humidity sensor that is disposed further inside than the nozzle face where the nozzle is disposed

Methodology Applied

Scientific EffectHumidity detection: Hygrometer

Implementation Method 3

a cap that holds a moisturizing liquid inside and maintaining the nozzles at high humidity due to evaporating moisture

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS10807361B2Liquid jetting head and liquid jetting device

Publication Date: 2020.10.20 FUJIFILM CORP

AI summary

Provided are a liquid jetting head and a liquid jetting device that prevent contamination of a humidity sensor. The liquid jetting head and the liquid jetting device include a nozzle that jets a liquid; a humidity sensor that is disposed further inside than the nozzle face where the nozzle is disposed; an air intake port that is disposed on the same plane as the nozzle face; a connection passage that allows the air intake port and the humidity sensor to communicate with each other; and a contamination preventing part that prevents contamination of the humidity sensor.