Liquid Ejecting Head Bubble Discharge via Circulation Path
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Solution Overview
Problem
Liquid ejecting heads face issues with bubble discharge during operation, leading to increased ink consumption due to required cleaning operations, as bubbles are trapped in narrow flow paths and cannot be easily expelled through nozzles.
Innovation Solution
The design incorporates a configuration with inflow and outflow ports in the supply liquid chamber, allowing for the circulation of ink and effective discharge of bubbles, reducing the need for maintenance operations and ink consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a one-way flow path is used from liquid storage member to nozzles, then the liquid supply structure is simple, but bubbles are trapped in the narrow flow path and cannot be discharged
Solution Approach 1:
The flow path is segmented into multiple sections: supply liquid chamber, individual communication paths to pressure chambers, and nozzle communication paths. This segmentation allows bubbles to be separated and discharged through the outflow port before entering the nozzles, resolving the contradiction between simple structure and bubble discharge capability.
Solution Approach 2:
Instead of the conventional one-way flow path, the invention introduces a circulation path with outflow ports that allow liquid (and trapped bubbles) to flow back toward the supply liquid chamber. This inverted flow direction enables bubble discharge while maintaining structural simplicity.
2Reliability
If cleaning operation is performed to discharge bubbles, then bubble discharge is achieved, but liquid consumption increases
Solution Approach 1:
The system performs self-cleaning through the circulation path. Bubbles are automatically discharged through the outflow port during normal operation without requiring external cleaning interventions, eliminating liquid consumption associated with manual cleaning operations.
Solution Approach 2:
The circulation path operates continuously during liquid supply, constantly moving liquid through the system and automatically carrying bubbles to the outflow port. This continuous action prevents bubble accumulation without requiring periodic cleaning operations that consume liquid.
3Device complexity
If liquid remains in the flow path inside the liquid ejecting head, then the one-way flow path structure is maintained, but bubbles are unlikely to be discharged from the nozzle
Solution Approach 1:
The system transitions from a static one-way flow path to a dynamic circulation system. Liquid continuously flows through the supply liquid chamber and pressure chambers, creating movement that actively carries bubbles to the outflow port, significantly improving bubble discharge efficiency.
Solution Approach 2:
The outflow port acts as an intermediary element that provides a dedicated exit path for bubbles. By introducing this intermediate component, bubbles can be discharged from the circulation path without disrupting the overall simple flow path configuration.
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 reduces the frequency and ink consumption of maintenance operations, such as cleaning and flushing, while maintaining ejection characteristics by enabling bubble discharge and preventing ink thickening near nozzles.
Implementation Method 1
a pressure generation element (or also referred to as a driving element or an actuator) such as a piezoelectric element, which causes pressure vibration in a liquid in the pressure chamber, in other words, a pressure change
Implementation Method 2
a buoyant force is applied. Therefore, the bubbles are unlikely to be discharged from the nozzle
Data Source
AI summary
A liquid ejecting head has head units for ejecting a liquid from nozzles onto a medium that is relatively moved in a first direction are arranged in a second direction perpendicular to the first direction. The head unit includes: a nozzle row in which the nozzles are arranged in a third direction intersecting the first direction and the second direction; a pressure chamber which communicates with the nozzles; a pressure generation element which corresponds to the pressure chamber; a supply liquid chamber which communicates with the pressure chambers and into which the liquid to be supplied to each pressure chamber is introduced; an inflow port through which the liquid flows into the head unit; and an outflow port through which the liquid flows out of the head unit.