Inkjet Printer Purge Cap Dents for Bubble Removal
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Solution Overview
Problem
Inkjet printers face instability in ink ejection performance due to bubbles generated during purging operations, which are not effectively removed, leading to delayed restoration of ejection performance and potential damage to nozzle surfaces.
Innovation Solution
The design incorporates a printhead with a purge cap featuring dents and grooves that form small chambers around nozzles, allowing for efficient discharge and suction of bubbles during purging, reducing air volume and preventing bubble formation, thereby ensuring quick ink filling and stable ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a purge cap covers the front surface of the printhead during purging, then ink can be received and purged from the nozzles, but bubbles are generated and drawn into the nozzles upon separation, causing instability in ejection performance
Solution Approach 1:
The contact surface of the purge cap is divided into multiple regions by forming dents that create separate small chambers around each nozzle. This segmentation allows independent bubble removal for each nozzle, preventing bubbles from being drawn into the nozzles when the purge cap is separated, thereby maintaining ejection performance stability.
Solution Approach 2:
The harmful bubbles are extracted from the ink flow by providing dedicated small chambers that collect and contain bubbles during purging. The bubbles are removed from the system through these chambers before the purge cap is separated, preventing them from entering the nozzles and affecting ejection performance.
2Reliability
If deaerated ink is used to dissolve bubbles in the ink passage, then ejection performance can be restored, but it takes time for bubbles to dissolve, requiring waiting time before next printing
Solution Approach 1:
The small chambers are prepared in advance on the purge cap contact surface, positioned to align with the nozzles during purging. These pre-formed chambers immediately capture and contain bubbles as they are generated during purging, eliminating the need to wait for bubble dissolution in the ink passage and enabling quicker resumption of printing.
3Strength
If the nozzle surface is covered with a metallic cover plate, then the nozzle surface is protected from damage, but ink remaining on the front surface cannot be completely removed after purging
Solution Approach 1:
The purge cap contact surface is designed with local variations in geometry through dents and grooves that create small chambers specifically at the nozzle locations. This local structural modification allows complete ink removal from these critical areas while maintaining the protective cover plate configuration for overall nozzle surface durability.
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 solution effectively prevents bubble introduction into nozzles, maintains ink stability, and reduces the need for additional maintenance operations like flashing, enhancing print quality and reducing costs by minimizing the necessity for wiper mechanisms.
Implementation Method 1
a plurality of dents formed on at least one of the contact surface of the purge cap and the front surface of the printhead so as to form, at least when the contact surface is in contact with the front surface, a plurality of branches a part of each of which is in communication with at least one of the nozzles
Implementation Method 2
At a moment when the purge cap is separated from the front surface of the printhead, this mixture is drawn into a nozzle because of a negative pressure in the printhead
Data Source
AI summary
There is disclosed an inkjet printer including: a printhead having a front surface in which is formed at least one nozzle row consisting of a plurality of nozzles from each of which a droplet of ink is ejected; a maintenance unit including a purge cap which receives ink from the nozzles during a purging operation, the purge cap having a contact surface to be brought into contact with the front surface of the printhead, and at least one main channel extending alongside the nozzle row; and a plurality of dents formed on at least one of the contact surface of the purge cap and the front surface of the printhead so as to form, at least when the contact surface is in contact with the front surface, a plurality of branches a part of each of which is in communication with at least one of the nozzles, and another part of each of which is in communication with the main channel.