Liquid-Jet Head Chip Air Vent Flow Path Design
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Solution Overview
Problem
Conventional ink-jet heads face issues with air bubble accumulation due to negative-pressure retention filters, leading to increased complexity, component count, and manufacturing costs, which complicates the ink flow path and prevents size reduction.
Innovation Solution
A liquid-jet head chip design featuring an actuator substrate with parallel discharge flow paths, a cover plate substrate with an independent air vent flow path and a foreign substance removal filter, and a filter with lower passage resistance for air bubbles, allowing air bubbles to be expelled externally while maintaining negative pressure without additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a negative-pressure retention filter is provided in the ink flow path member or in an additional separate component, then air bubbles can be retained and negative pressure can be maintained, but the shape of the ink flow path member becomes complicated or the number of components increases
Solution Approach 1:
The patent combines the negative-pressure retention filter function with the foreign substance removal filter by providing two independently open flow paths within the same filter component. The first flow path (for ink supply) includes a first filter for removing foreign substances, while the second flow path (for air venting) includes a second filter with larger holes for allowing air bubbles to pass through. This merging eliminates the need for separate components and simplifies the overall structure while maintaining reliable negative pressure.
2Reliability
If a negative-pressure retention filter is provided in the ink flow path member or in an additional separate component, then air bubbles can be retained and negative pressure can be maintained, but the size of the ink-jet head cannot be reduced
Solution Approach 1:
The patent integrates both filtering functions into a single filter component with two independently open flow paths, eliminating the need for additional separate components. This merging approach reduces the overall volume of the ink-jet head while maintaining the necessary negative pressure maintenance function.
Solution Approach 2:
The patent utilizes the thickness direction of the filter component to provide independent opening directions. The first flow path opens in a first direction for ink supply, while the second flow path opens in a second direction (different from the first) for air venting. This dimensional arrangement allows both functions to coexist in a compact space, reducing the overall head size.
3Reliability
If a foreign substance removal filter is provided in a liquid supply chamber, then foreign substances can be removed, but air bubbles which are too large to pass through the filter accumulate and cause insufficient ink supply
Solution Approach 1:
The patent segments the flow paths into two independently open channels within the filter component. The first flow path is dedicated to ink supply with a first filter for foreign substance removal, while the second flow path is dedicated to air venting with a second filter having larger holes. This segmentation allows each flow path to be optimized for its specific function, preventing air bubble accumulation while maintaining foreign substance removal capability.
Solution Approach 2:
The patent applies different filter characteristics to different flow paths based on local requirements. The first filter in the ink supply path has fine pores for removing foreign substances, while the second filter in the air vent path has larger holes for allowing air bubbles to pass through. This local quality differentiation ensures that each location in the system has the appropriate filtering characteristics for its specific function.
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 design simplifies the structure, reduces the size of the ink-jet head, and ensures stable ink discharge by preventing air bubble accumulation and maintaining negative pressure, thereby enabling efficient printing without additional components.
Implementation Method 1
air bubbles which are too large to pass through the foreign substance removal filter... air bubbles accumulated at the upstream of the foreign substance removal filter are exhausted to the exterior
Implementation Method 2
a filter for allowing passage of air bubbles, having a smaller passage resistance than that of the foreign substance removal filter... a negative-pressure retention filter is provided in the air-bubble exhaust path to retain a negative pressure in the ink flow path member
Implementation Method 3
side walls of each of the liquid discharge flow paths are subjected to shear deformation to change a volume of each of the liquid discharge flow paths. As a result, the liquid distributed from the opening portion to the liquid discharge flow paths can be discharged
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
To simplify a head-chip (1) is provided with an actuator (3) including grooves (13) and a cover plate (5) bonded onto the one surface of the actuator and including an opening portion (61) including an ink chamber (17) having an aperture plane (17A) being open on an upper end surface and slits (19) extending from the ink chamber to be in communication with the grooves, and an air vent flow path (71A,71B) for bringing the upper end surface and one end surface extending in a thickness direction into communication with each other, the opening portion and the flow path being provided independently of each other. In the head-chip, foreign substance removal filter (29) for removing a foreign substance is provided at a position at which the aperture plane of the ink chamber is substantially closed, and a filter (73) for allowing passage of air bubbles, is provided at a position at which an opening of the flow path is substantially closed.