Printhead cleaning

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Solution Overview

Problem

Existing printhead cleaning systems face issues with excess liquid accumulation, leading to reduced cleaning effectiveness and potential damage to electronic components, increasing costs and downtime, due to the inefficiencies in managing liquid saturation and distribution during the cleaning process.

Innovation Solution

A printhead cleaning system that employs a movable web with a dispensing apparatus to apply liquid, a scraper element to remove excess liquid, and a pusher element to ensure optimal wetting conditions, preventing excess liquid from dripping and enhancing the cleaning process while protecting sensitive components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a moistened web is used to wipe the printhead nozzles, then cleaning effectiveness is improved, but excess liquid accumulates on the web causing over-saturation and potential damage to electronic components

Engineering Contradiction:
Improvecleaning effectivenessVSAvoidexcess liquid accumulation
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements a system where the cleaning web is continuously fed and discarded after use, rather than being reused. This allows the web to be replaced with a fresh, dry section after it becomes saturated, preventing excess liquid accumulation while maintaining cleaning effectiveness. The web feed mechanism ensures continuous supply of clean wiping surfaces.

Inventive Principle:
Principle #34Discarding and recovering

Solution Approach 2:

The patent extracts and removes excess liquid from the cleaning web through a series of drying rollers and suction mechanisms positioned along the web path. This separation of liquid removal function from the wiping function allows the web to maintain optimal moisture levels for cleaning without becoming over-saturated.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If liquid is applied to moisten the cleaning web, then cleaning performance is improved, but the cost and complexity of liquid distribution control increases

Engineering Contradiction:
Improvecleaning performanceVSAvoidliquid distribution control
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The cleaning web is designed to be self-regulating in its liquid absorption. Rather than requiring complex sensors and controllable fluid distribution devices, the web naturally absorbs the amount of liquid needed for effective cleaning through capillary action, eliminating the need for active control systems.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent employs a disposable or frequently replaceable cleaning web that does not require precise liquid distribution control. By using a new web section for each cleaning cycle, the system achieves consistent cleaning performance without investing in complex liquid management infrastructure.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Reliability

If a wiper pushes the cleaning web against the printhead face, then cleaning contact is improved, but the squeezing effect causes excess liquid to drip from the web

Engineering Contradiction:
Improvecleaning contactVSAvoidliquid dripping
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The cleaning system is divided into distinct functional zones: a wetting zone where liquid is applied, a wiping zone where the web contacts the printhead, and a drying zone where excess liquid is removed. This segmentation allows each zone to perform its function optimally without interfering with others, preventing liquid dripping while maintaining effective contact.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of applying force in the vertical direction (pushing the web against the printhead), the patent uses a horizontal web feed mechanism to move the cleaning web continuously through the cleaning zone. This dimensional change eliminates the squeezing effect that causes dripping while maintaining adequate contact through the web's inherent flexibility and continuous motion.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 system effectively wipes printhead nozzles without excess liquid, improving print quality, extending printhead lifespan, and reducing downtime by maintaining efficient cleaning cycles and minimizing damage to electronic components.

Implementation Method 1

a dispensing apparatus to apply a liquid upon the web

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Implementation Method 2

a moistened web... to periodically wipe the printhead nozzles

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Implementation Method 3

a scraper element to scrape the web at a second side

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3628494B1Printhead cleaning
Publication Date: 2022.11.02 HP SCITEX LTD
  • EP3628494B1 patent drawingFigure 1
  • EP3628494B1 patent drawingFigure 2
  • EP3628494B1 patent drawingFigure 3A~3B

AI summary

In an example of the disclosure, a cleaning system for a printhead includes a web of material movable in a web direction. The web has a first side for wiping a printhead face. The cleaning system includes a dispensing apparatus to dispense a liquid upon the web. The cleaning system includes a scraper element for scraping liquid from the web and includes a collector element with a trough. The collector element is to cause collection of liquid scraped from the web to collect in the trough. The cleaning system includes a pusher element to push against the second side of the web and thereby cause the first side of the web to wipe the printhead face