Liquid Ejection Head Circulation Layout for Nozzle Ink Thickening
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Solution Overview
Problem
Ink concentration at ejection nozzles due to evaporation leads to variations in ejection amount and direction, causing image quality issues in liquid ejection heads, and existing circulation methods risk deteriorating ejection performance.
Innovation Solution
A liquid ejection head with a flow passage configuration and driving method that includes a second energy generating element in the circulating flow passage, driven intermittently to enhance circulation efficiency and prevent recirculation concentration.
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 with multiple driving periods between each ejection operation. This periodic driving pattern prevents continuous operation that causes local heating and bubble generation issues, while still maintaining effective ink circulation. The multiple driving periods within each interval ensure thorough mixing and prevention of ink concentration without the negative effects of continuous heating.
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 divided into multiple sections with separate inflow and outflow portions. By segmenting the flow path and positioning the electrothermal transducer to drive flow from the inflow side toward the outflow side, the system prevents concentrated ink from the outflow portion from being immediately recirculated back to the inflow portion. This segmentation breaks the recirculation loop that would otherwise concentrate ink and degrade ejection performance.
Solution Approach 2:
The electrothermal transducer is positioned specifically at the inflow side of the pressure chamber, creating localized driving force at a specific location. This local quality approach ensures that the driving action occurs where fresh ink enters, pushing it through the passage toward the outflow side, rather than creating general circulation that would recirculate concentrated ink back to the inflow region.
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 effectively suppresses ink thickening at the nozzle, ensuring stable ejection performance and improved image quality by continuously supplying fresh ink.
Implementation Method 1
one energy generating element for ejecting liquid... the first energy generating element is driven... to eject the liquid from the ejection nozzle
Implementation Method 2
a pressure chamber... for generating energy to eject the liquid from the ejection nozzle
Implementation Method 3
the electrothermal transducer is disposed within the circulating flow passage. When the ink is heated by the electrothermal transducer, bubbles grow due to film boiling of the ink
Implementation Method 4
When the ink is heated by the electrothermal transducer, bubbles grow due to film boiling of the ink
Implementation Method 5
bubbles grow due to film boiling of the ink, and during the subsequent contraction process, a flow is generated
Data Source
AI summary
A liquid ejection head includes a pressure chamber for ejecting liquid, a first energy generating element for generating energy to eject the liquid, and circulating flow passages, each of which is provided with a second energy generating element 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.