Liquid Ejection Head With Separate Thermal Elements for Ink Circulation
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Solution Overview
Problem
Existing liquid ejection systems, such as those described in Japanese Patent Laid-Open No. 2020-104312, require complex mechanisms like pumps and pressure adjustments to circulate ink, leading to increased size and complexity of printing apparatuses, and lack clear driving data for combined ejection and flow energy generating elements.
Innovation Solution
A liquid ejection head and method that optimizes driving data for both ejection and flow energy generating elements, using a combination of electrothermal conversion elements to circulate ink efficiently within the head, reducing the need for external pumps and pressure adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a differential pressure system with pump and pressure adjustment mechanism is used to circulate ink, then ink circulation is achieved, but the printing apparatus and head are upsized
Solution Approach 1:
The invention extracts the ink circulation function from the main printing apparatus by providing a separate circulation pump and circulation flow path. This allows the head to be smaller while maintaining reliable ink circulation through a dedicated circulation system that operates independently from the ejection system.
Solution Approach 2:
The invention segments the fluid system into two independent flow paths: a circulation flow path for ink circulation and an ejection flow path for ink ejection. This segmentation allows each system to be optimized independently, enabling compact head design while maintaining effective ink circulation.
2Reliability
If a circulation pump is provided inside the liquid ejection head, then ink is circulated inside the head, but the head structure becomes more complex
Solution Approach 1:
The invention extracts the circulation pump from the head structure and places it in the printing apparatus body. This reduces head complexity while maintaining effective ink circulation through a separate circulation system that connects to the head via circulation flow paths.
3Measurement precision
If ejection energy generating element and flow energy generating element are driven with separate driving data, then precise control is achieved, but data amount increases
Solution Approach 1:
The invention merges the control of ejection and circulation functions by using a single driving data signal to control both the ejection energy generating element and the flow energy generating element. The element switching unit selectively activates the appropriate element based on the same driving data, reducing data transmission requirements while maintaining precise control.
Solution Approach 2:
The driving data is designed to serve multiple functions: it controls both ejection and circulation operations depending on which energy generating element is activated. This multi-functional approach reduces the total data amount needed while maintaining precise control over both functions.
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 approach minimizes waste ink and maintains ejection stability by suppressing evaporation and condensation near the ejection orifice, improving throughput and yield while allowing for a more compact and efficient printing apparatus design.
Implementation Method 1
a flow energy generating element different from an energy generating element configured to eject the liquid
Implementation Method 2
the ink is circulated in the circulation path by driving the flow energy generating element
Implementation Method 3
an energy generating element configured to eject the liquid
Implementation Method 4
suppressing evaporation and condensation near the ejection orifice
Implementation Method 5
suppressing evaporation and condensation near the ejection orifice
Implementation Method 6
suppressing evaporation and condensation near the ejection orifice
Data Source
Figure 1A~1B
Figure 2A~2D
Figure 3A~3D
AI summary
A liquid ejection method for a liquid ejection head including a common flow path for supplying a liquid to a plurality of separate flow paths of a plurality of separate ejection units, each of the separate ejection units including an ejection orifice, a pressure chamber, a first heat energy generating element provided for the pressure chamber, a separate flow path communicating with the pressure chamber, and a second heat energy generating element provided for the separate flow path, the method comprising: controlling the first and second heat energy generating elements to be driven under a condition that, when the first heat energy generating element is driven, the second heat energy generating element is not driven, and, when the first heat energy generating element is not driven, the second heat energy generating element is driven upon receiving a driving signal that instructs drive relative to the second heat energy generating element.