Liquid Ejecting Head Slanted Surface Bubble Discharge
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Solution Overview
Problem
Miniaturization of liquid ejecting heads, such as ink jet heads, leads to reduced reservoir sizes, making it difficult to discharge bubbles due to narrowed flow channels, resulting in reduced print quality and ineffective cleaning processes.
Innovation Solution
A liquid ejecting head design featuring a common liquid chamber with slanted surfaces and strategically positioned inflow ports to ensure a flow rate of at least 0.025 m/s when negative pressure is applied, facilitating effective bubble discharge, and further enhanced by beveled edges and optimized pressure loss distribution across nozzle openings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the reservoir size is reduced to miniaturize the ink jet head, then the device size is reduced, but the flow channels are narrowed making it difficult to discharge bubbles
Solution Approach 1:
The patent introduces a slanted surface at a specific location within the reservoir to create localized flow dynamics. This slanted surface is positioned to overlap with the arrangement of supply openings, creating a region where liquid flow is enhanced during cleaning operations to facilitate bubble discharge from that critical area.
Solution Approach 2:
The slanted surface introduces a geometric curvature element into the otherwise planar reservoir bottom. This curved surface design modifies the flow pattern of liquid during cleaning, creating favorable flow conditions that enable effective bubble discharge even from the narrowed flow channels of miniaturized reservoirs.
2Object-generated harmful factors
If protrusions are added to the reservoir entrance to improve bubble discharge, then bubble discharge is enhanced, but the device complexity increases
Solution Approach 1:
Instead of adding protrusions at the reservoir entrance, the patent applies a slanted surface at a different location - overlapping with the supply openings arrangement. This localized geometric modification achieves the bubble discharge function without adding complex structural elements to the reservoir entrance region.
Solution Approach 2:
The patent uses a simple slanted surface geometry rather than complex protruding structures. This curved surface approach achieves effective bubble discharge through flow dynamics modification while maintaining structural simplicity and avoiding the need for additional mechanical components.
3Speed
If the flow rate is increased to discharge bubbles effectively, then bubble discharge is improved, but the pressure loss across nozzle openings becomes non-uniform
Solution Approach 1:
The slanted surface is positioned to overlap with the arrangement of supply openings, creating localized flow enhancement at specific regions. This targeted approach ensures that high flow rates are achieved where needed for bubble discharge while maintaining more uniform pressure distribution across the nozzle array during normal operation.
Solution Approach 2:
The curved slanted surface design creates favorable flow patterns that balance the conflicting requirements of high flow rate for bubble discharge and uniform pressure distribution for consistent printing performance. The geometry is optimized to achieve both objectives simultaneously.
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 significantly improves bubble discharge properties, reducing missing dots and enhancing print quality by ensuring efficient liquid flow and bubble removal during the cleaning process, even in miniaturized reservoirs.
Implementation Method 1
when the liquid is sucked from the nozzle openings by applying negative pressure to the nozzle openings
Implementation Method 2
a flow rate of the liquid is no less than 0.025 m/s (meters per second) in the vicinity of an end of the inflow port in the arrangement direction
Data Source
AI summary
A common liquid chamber that communicates with a plurality of pressure chambers includes at least one inflow port into which a liquid flows, a plurality of supply openings, arranged in a row, for supplying the liquid to each of the pressure chambers, and a slanted surface that, when viewed from a second direction that is orthogonal to an arrangement direction in which the supply openings are arranged and that follows a substrate in which the common liquid chamber is formed, is slanted so that the slanted surface overlaps with the arrangement of some of the supply openings including supply openings located at ends of the arrangement direction and approaches the arrangement of the supply openings at the end areas of the arrangement direction. At least part of the inflow port is located within the range of the arrangement of the stated some of the supply openings when viewed from the second direction. An angle of the slanted surface and a position of the inflow port are set so that a flow rate of the liquid is no less than 0.025 m/s in the vicinity of an end of the inflow port in the arrangement direction when the liquid is sucked from the nozzle openings by applying negative pressure to the nozzle openings.