Printhead Spitting Mechanism for Nozzle Clog Prevention
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Solution Overview
Problem
Commercially available printers using solvent or water-based printing liquids face a reduction in print quality due to evaporation from nozzles between ejections, leading to clogging and obstructed passage of printing fluid, which affects nozzle health and print quality.
Innovation Solution
Implementing a 'spitting' mechanism where the printhead ejects printing liquid into a designated reservoir or directly onto the printing medium in specific zones to clean and maintain nozzles, known as spitting zones, to prevent evaporation and clogging, utilizing a spit engine to control the process and determine optimal spitting locations and times based on nozzle usage and decap time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nozzles are capped between use to prevent evaporation, then nozzle health is maintained, but print quality deteriorates due to clogging from dried printing liquid
Solution Approach 1:
The system performs preliminary cleaning action by spitting printing liquid through the nozzles into a spittoon before the nozzles are needed for printing. This preliminary action removes dried printing liquid and prevents clogging, ensuring both nozzle health and print quality are maintained without requiring caps between uses
2Reliability
If printing liquid is ejected frequently to clean nozzles, then nozzle health is maintained, but printing productivity decreases due to additional ejection cycles
Solution Approach 1:
A spittoon is introduced as an intermediary component that receives cleaning ejections separately from the printing medium. This allows the printhead to eject printing liquid for cleaning purposes without depositing it on the printing medium, enabling maintenance operations without sacrificing printing productivity
Solution Approach 2:
The system segments the ejection function into two distinct modes: printing mode (depositing liquid on medium) and cleaning mode (spitting liquid into spittoon). This segmentation allows independent optimization of both printing productivity and nozzle health maintenance
3Reliability
If spitting zones are established on the printing medium, then nozzle cleaning is achieved, but visible marks are left on the printed image
Solution Approach 1:
A spittoon serves as an intermediary receptacle that intercepts cleaning ejections before they can contact the printing medium. This eliminates visible marks on the printed image while still achieving effective nozzle cleaning through the spitting mechanism
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 approach mitigates nozzle deterioration and maintains high print quality by regularly cleaning nozzles, reducing the size and visibility of spat drops, and balancing maintenance with minimal visibility impact on the printed image.
Implementation Method 1
evaporation from the nozzles between printing liquid ejection, or firing, of the nozzles
Data Source
AI summary
Printing liquid is spat from ai least one printhead nozzle onto a printing medium in a spitting zone when the printhead traverses the spitting zone during printing. The spitting zone is an area of the printing medium located at least partially in a second half of the printing medium in the direction of printhead travel, and wherein a centre point of the spitting zone is located in the second half of the printing medium in the direction of printhead travel.