Liquid Ejection Head with Gas-Permeable Bubble Removal
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Solution Overview
Problem
Bubbles entering liquid ejection heads during maintenance can cause insufficient ejection pressure and liquid leakage due to environmental changes, affecting the stability and performance of liquid ejection apparatuses.
Innovation Solution
A liquid ejection head design featuring a depressurization chamber with a gas-permeable film, a first opening on the lower side, and a second opening for external communication, allowing for the discharge of bubbles through controlled pressure differentials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a sub tank greatly bulges in the scanning direction from an ejection unit to route tubes, then tubes for gas discharge and ink can be connected, but the head unit size increases
Solution Approach 1:
The patent repositions the sub tank from a horizontal arrangement (bulging in scanning direction) to a vertical arrangement (extending in vertical direction). This dimensional change allows tube connections while maintaining a compact head unit footprint in the scanning direction, effectively resolving the contradiction between ease of manufacture and head unit size.
2Device complexity
If bubbles remain inside channels in the liquid ejection head, then the structure is simple, but bubbles expand due to environmental changes causing liquid leakage
Solution Approach 1:
The patent extracts bubbles from the ink channels by providing a separate gas discharge channel that communicates with the ink channel through a gas permeable partition. This allows bubbles to be removed from the liquid ejection path while maintaining the simplicity of the overall channel structure, resolving the contradiction between device complexity and reliability.
Solution Approach 2:
The patent segments the channel into two functional zones: an ink channel for liquid ejection and a gas discharge channel for bubble removal, separated by a gas permeable partition. This segmentation allows independent handling of liquid and gas phases, preventing bubble expansion from affecting ejection stability while maintaining structural simplicity.
3Ease of manufacture
If bubbles enter pressure chambers during maintenance, then replacement is simple, but sufficient ejection pressure cannot be obtained
Solution Approach 1:
The patent enables the head unit to automatically remove bubbles from pressure chambers through the gas discharge channel and permeable partition system. This self-service mechanism continuously maintains ejection pressure without requiring manual intervention or complex replacement procedures, resolving the contradiction between ease of manufacture and ejection pressure reliability.
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 design effectively reduces the size of the liquid ejection head and apparatus while maintaining stable ejection performance by efficiently removing bubbles, preventing leakage, and ensuring consistent pressure for ink ejection.
Implementation Method 1
a gas permeable film therebetween and configured such that an inside of the depressurization chamber is depressurizable
Implementation Method 2
the pressure inside the gas collection hollow portion is set to be lower than the pressure inside the filter chamber to cause a gas in the filter chamber to permeate through the permeable partition by means of the pressure difference
Implementation Method 3
a depressurization chamber adjoining the liquid reservoir chamber with a gas permeable film therebetween and configured such that an inside of the depressurization chamber is depressurizable
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A liquid ejection head (1) includes: an ejection port (13) for ejecting the liquid; a pressure chamber (12) provided with an energy generation element (15) which generates an energy for ejecting the liquid from the ejection port (13); a liquid reservoir chamber (122) which fluidly communicates with one end of the pressure chamber (12) and holds the liquid to be supplied to the pressure chamber (12); a depressurization chamber (760) adjoining the liquid reservoir chamber (122) with a gas permeable film (710) therebetween and configured such that an inside of the depressurization chamber (760) is depressurizable; a first opening (1506) through which the liquid reservoir chamber (122) communicates with an outside; and a second opening (1507) through which the depressurization chamber (760) communicates with an outside. The first opening (1506) is located on a lower side in a vertical direction relative to the second opening (1507).