Inkjet Ink Circulation Venting for Air Bubble Removal
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Solution Overview
Problem
Inkjet printers can experience air accumulation in the ink circulation path due to disturbed menisci at the nozzle discharge ports, leading to pressure imbalances when not in use, which can mix air into the ink and cause printing issues.
Innovation Solution
The inkjet printing apparatus incorporates a design with collecting-side and supply-side individual pipes featuring upward protruding portions and air pipes, along with negative and positive pressure application units, to discharge air from the ink and reduce accumulation, using a circulation pump and liquid-level sensors for control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ink circulation path is sealed to prevent contamination, then ink purity is improved, but air accumulation occurs in the circulation path
Solution Approach 1:
The patent extracts air from the ink circulation path by providing a vent hole in the collecting tank that allows air to escape to the atmosphere. The air separation chamber in the supply tank further separates and removes air bubbles from the ink before it reaches the discharge head, thus maintaining ink purity while preventing air accumulation.
Solution Approach 2:
The patent introduces air separation chambers and vent holes as intermediary structures between the sealed circulation path and the atmosphere. These intermediaries allow controlled air release without compromising the overall sealing of the ink circulation system, enabling air removal while maintaining ink purity.
2Device complexity
If the discharge head is positioned at the same level as the supply tank, then ink flow is simplified, but air bubbles cannot be effectively separated from ink
Solution Approach 1:
The patent positions the supply tank at a higher vertical level than the discharge head, utilizing the vertical dimension to create gravitational flow. This elevation difference enables air bubbles to rise to the air separation chamber in the supply tank and be effectively separated from the ink, improving reliability without significantly increasing device complexity.
3Object-affected harmful factors
If the meniscus at the nozzle discharge port is stable, then air entry is prevented, but ink discharge requires higher pressure
Solution Approach 1:
The patent removes air from the ink circulation path before ink discharge by providing air separation chambers and vent holes. This preliminary air removal action prevents air bubbles from entering the discharge head, maintaining stable menisci at the nozzles while reducing the pressure required for ink discharge.
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 design effectively removes air from the ink circulation path, preventing pressure imbalances and ink drop, ensuring reliable ink discharge and reducing air accumulation in the individual pipes.
Implementation Method 1
each of a plurality of the collecting-side individual pipes has a protruding portion protruding upward in an inverted U shape or an inverted V shape
Implementation Method 2
a meniscus of ink near the discharge port may be disturbed
Implementation Method 3
a negative pressure application unit connected to the collecting tank and configured to apply a negative pressure to the inside of the collecting tank
Implementation Method 4
a positive pressure application unit connected to the supply tank and configured to apply a positive pressure to the inside of the supply tank
Implementation Method 5
a circulation pump, a control unit, and a liquid-level sensor. The circulation pump delivers ink from the collecting tank to the supply tank via the feedback pipe
Implementation Method 6
an air pipe that allows communication between an internal passage of the protruding portion and the space portion is provided
Data Source
AI summary
A collecting tank stores ink collected from a plurality of heads that discharge ink. A plurality of collecting-side individual pipes are connected respectively to the downstream sides of a plurality of the heads. A collecting-side manifold has a downstream end communicating with the collecting tank and is forked into a plurality of the collecting-side individual pipes. Further, a space portion is formed above the stored ink in the collecting tank. In addition, each of a plurality of the collecting-side individual pipes has a protruding portion protruding upward in an inverted U shape. An uppermost position of the protruding portion is located higher than an uppermost position of a plurality of the heads and the collecting-side manifold and lower than a liquid level of ink stored in the collecting tank. Moreover, an air pipe that allows communication between an internal passage of the protruding portion and the space portion is provided.