Flow Path Member Slit Design for Bubble Emission
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Solution Overview
Problem
In liquid ejecting apparatuses, such as ink jet type recording heads, gas bubbles tend to attach to the inner walls of flow path members, leading to unstable film operation, droplet discharge failures, and increased liquid consumption due to inefficient bubble emission.
Innovation Solution
A flow path member design featuring a recess portion with a wall that includes a first slit and a second slit, where the second slit is outside the wall, and both slits are oriented vertically, allowing for improved liquid stirring and bubble emission by directing flow through the first slit and facilitating bubble movement via the second slit, along with a pressure receiving plate with a spring retainer and inclined surface to stabilize the film and prevent stagnation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a wall is provided around the first opening with a slit to form flow in a direction opposite to the shortest distance line, then liquid residence is inhibited, but gas bubbles attach to the inner side of the wall causing decline in bubble emission characteristic
Solution Approach 1:
The wall is divided into two separate slits (first slit and second slit) rather than one continuous opening. The first slit has a larger opening area for liquid flow, while the second slit has a smaller opening area specifically for bubble emission. This segmentation allows the wall to simultaneously achieve liquid circulation and bubble release functions that a single opening cannot provide.
Solution Approach 2:
Different portions of the wall are given different properties through the two slits. The first slit with larger opening area is optimized for liquid flow in the opposite direction to prevent residence, while the second slit with smaller opening area is optimized for bubble emission. This local differentiation allows each part of the wall to perform its specific function effectively.
2Loss of substance
If a slit is provided only in a vertically lower portion of the wall, then liquid flow is directed opposite to the shortest distance, but bubbles ascending by buoyancy are likely to attach to the wall
Solution Approach 1:
The solution moves from a single-dimensional (vertical position only) slit arrangement to a two-dimensional arrangement with slits at different positions. By placing the second slit in the vertically upper portion of the wall, bubbles ascending by buoyancy can be emitted through this upper slit before attaching to the wall, while the first slit in the lower portion continues to direct liquid flow oppositely.
3Loss of substance
If the opening area of the first slit is made larger to improve liquid stirring, then liquid residence is further inhibited, but the structure becomes more complex
Solution Approach 1:
The wall structure with two slits serves multiple functions simultaneously: the first slit provides liquid flow in the opposite direction to prevent residence, the second slit provides bubble emission pathway, and together they maintain relatively simple wall geometry. The asymmetric design with different opening areas optimizes both liquid circulation and bubble emission without requiring complex additional components.
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 enhances bubble emission characteristics, stabilizes liquid droplet discharge, and reduces undesirable liquid consumption by effectively moving bubbles away from the flow path and preventing their accumulation.
Implementation Method 1
When the pressure on the downstream side of the valve device is negative (relative to the atmosphere pressure), the pressure difference between the inside of the recess portion and the outside of the film flexuously deforms the film
Implementation Method 2
bubbles, ascending by buoyancy, are likely to attach to the wall
Data Source
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AI summary
A flow path member includes a film, a main body that includes a recess portion that is closed by the film, a first opening and a second opening that are provided in the recess portion and that are used to supply and emit a liquid, and a wall which is provided in the recess portion and which switches between contact and non-contact between the film and the main body via the wall as the film is displaced. In a view taken in a first direction that is a stacking direction of the main body and the film, the wall is provided around the first opening, the wall has a first slit in one of two portions of the wall across the first opening from each other and a second slit in the other one of the two portions, and the second opening is outside the wall. An opening area of the first slit is larger than an opening area of the second slit.