Liquid Ejection Head Circulation Layout for Stable Ink Concentration
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Solution Overview
Problem
Existing liquid ejection heads face issues with ink concentration at ejection nozzles due to evaporation, leading to variations in ejection amount and direction, which degrade image quality, and existing circulation methods risk reducing ejection performance.
Innovation Solution
A liquid ejection head with a straight-type flow passage configuration and intermittent driving of the electrothermal transducer to suppress recirculation concentration, ensuring continuous fresh ink supply to the nozzles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the electrothermal transducer is driven continuously to circulate ink, then ink concentration is prevented, but local heating hinders bubble generation and decreases flow rate
Solution Approach 1:
The electrothermal transducer is driven intermittently in a periodic manner, alternating between driving and non-driving states. This periodic action prevents continuous local heating that would hinder bubble generation, while still achieving ink circulation during the driving phases, thus maintaining both flow rate and preventing ink concentration
Solution Approach 2:
The driving parameters of the electrothermal transducer are changed by controlling the duty cycle (ratio of driving time to total cycle time). By adjusting this parameter, the system optimizes between sufficient heating for bubble generation and adequate cooling periods to maintain flow rate, while still achieving effective ink circulation
2Productivity
If the electrothermal transducer is driven intermittently in a U-shaped circulating flow passage, then local heating is avoided, but concentrated ink from the outflow portion is recirculated to the inflow portion, promoting concentration and deteriorating ejection performance
Solution Approach 1:
The circulating flow passage is segmented into distinct inflow and outflow portions with separated communication paths. The first communication path connects the outflow portion to the intermediate portion, while the second communication path connects the intermediate portion to the inflow portion, preventing direct recirculation of concentrated ink from outflow to inflow
Solution Approach 2:
The intermediate portion of the circulating flow passage acts as an intermediary that receives ink from the outflow portion and supplies it to the inflow portion. This intermediary structure prevents direct recirculation of concentrated ink, allowing the system to maintain both flow rate and ink composition stability
3Length of moving object
If the inflow portion and outflow portion are arranged close to each other in a U-shaped passage, then circulation path is shortened, but recirculation concentration occurs when driven intermittently
Solution Approach 1:
The circulation path is segmented into distinct sections with separated communication paths between outflow-intermediate and intermediate-inflow portions. This segmentation prevents direct recirculation of concentrated ink while maintaining a relatively compact overall structure
Solution Approach 2:
The flow passage configuration transitions from a two-dimensional U-shaped planar layout to a three-dimensional structure with separated communication paths. This dimensional change allows the system to maintain compact size while preventing direct recirculation through spatial separation of ink flow paths
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
The solution enhances circulation efficiency, preventing ink thickening at nozzles and maintaining stable ejection performance, thereby improving image quality.
Implementation Method 1
When the ink is heated by the electrothermal transducer, bubbles grow due to film boiling of the ink
Implementation Method 2
an electrothermal transducer for delivering liquid within the circulating flow passage
Implementation Method 3
one energy generating element for ejecting liquid and one electrothermal transducer for delivering liquid within the circulating flow passage
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A liquid ejection head (1) includes a pressure chamber (3) for ejecting liquid, a first energy generating element (35) for generating energy to eject the liquid , and circulating flow passages (6), each of which is provided with a second energy generating element (5) and has a supply port through which liquid to the pressure chamber flows in and a discharge port through which liquid from the pressure chamber is discharged, and the pressure chamber being disposed between the supply port and the discharge port. The supply port is located on one side of the pressure chamber the discharge port is located on the other side of the pressure chamber, and the supply port, pressure chamber, and discharge port are arranged in this order. The second energy generating element is disposed on a side closer to the supply port than the pressure chamber, and is driven while the first energy generating element is stopped.