Liquid Ejection Head Bubble Communication for Droplet Stability
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Solution Overview
Problem
Existing liquid ejection heads, such as those using thermal ejection methods, face issues with droplet tail instability during long-continued ejection, leading to satellite formation and potential image quality degradation due to accumulated foreign substances near the discharge port.
Innovation Solution
The liquid ejection head incorporates a design with a liquid chamber, discharge port, nozzle, liquid supply path, and liquid collection path. Thermal energy generates a bubble in the liquid chamber, which enters the nozzle to eject liquid under pressure. The bubble communicates with the atmosphere before the liquid contacts the surface, ensuring stable ejection and reduced satellite formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the bubble communicates with the atmosphere before the liquid contacts the surface, then the droplet tail is shortened and satellite formation is reduced, but the ejection stability during long-continued operation deteriorates due to foreign substance accumulation
Solution Approach 1:
The liquid collection path is designed to collect and remove foreign substances before they can accumulate and affect ejection stability. This preliminary cleaning action prevents the deterioration of ejection stability during long-continued operation while maintaining the benefits of early bubble-atmosphere communication for tail shortening
Solution Approach 2:
The liquid collection path acts as an intermediary mechanism that intercepts and removes foreign substances from the ejection system. This intermediary function allows the bubble to communicate with the atmosphere early (for tail shortening) while the collection path handles the foreign substance removal that would otherwise compromise ejection stability
2Productivity
If long-continued ejection is performed without recovery action, then productivity is maintained, but foreign substances accumulate near the discharge port causing deviation in droplet landing position
Solution Approach 1:
The liquid collection path enables the system to clean itself during operation. Foreign substances are automatically collected and removed through the liquid flow in the collection path, allowing continuous ejection without manual intervention while maintaining droplet landing position accuracy
Solution Approach 2:
The liquid collection path operates continuously during ejection, constantly removing foreign substances. This continuous cleaning action allows prolonged productivity while preventing the accumulation that would cause landing position deviation, thus maintaining both productivity and precision simultaneously
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 achieves ejection stability during long-continued operation while effectively shortening the droplet tail, thereby reducing satellite formation and maintaining high image quality.
Implementation Method 1
a heat generating resistor (heater) in the pressure chamber... the energy generated by the heat generating resistor
Implementation Method 2
applying heat to liquid (for example, ink) for film boiling and ejecting the liquid by using the bubbling force caused by the film boiling
Implementation Method 3
The tail is separated from the main droplet due to the surface tension of the liquid during the flight of the droplet
Data Source
AI summary
A liquid ejection head includes a liquid chamber having an element that generates thermal energy, a discharge port for liquid, a nozzle that communicates between the discharge port and the liquid chamber, and a liquid supply path and a liquid collection path in communication with the liquid chamber on opposite sides. The thermal energy forms a bubble in the liquid chamber, and the formed bubble enters the nozzle to eject liquid under pressure of the bubble. In a state where at least a portion of the bubble in the nozzle has a velocity component toward a surface of the liquid chamber that has the element and before liquid to be ejected comes in contact with the surface of the liquid chamber by being drawn into the liquid chamber by contraction of the bubble, the bubble communicates with an atmosphere and the liquid is ejected through the discharge port.