Liquid-Ejecting Head Asymmetric Circulation Channel
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Solution Overview
Problem
Ink jet recording heads face issues with viscosity increase and component precipitation in the ink, leading to variations in ejection characteristics over time, and existing solutions require additional components like pumps to circulate ink, increasing size and production costs.
Innovation Solution
A liquid-ejecting head with a circulation channel featuring narrow portions that generate pressure changes using a pressure generator, eliminating the need for external pumps and maintaining uniform ejection quality by circulating ink within the head.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pump is provided to circulate ink in a common liquid chamber, then ink viscosity increase and component precipitation are suppressed, but the size of the recording head increases and production costs increase
Solution Approach 1:
The invention extracts and eliminates the pump component from the ink circulation system. Instead of using an active pump to circulate ink, the design relies on passive circulation through carefully engineered channel geometry with asymmetric narrow portions that create directional flow using pressure changes from the piezoelectric actuator alone.
Solution Approach 2:
The ink circulation system becomes self-service by utilizing the pressure changes naturally generated during the piezoelectric actuation process. The asymmetric channel structure converts these pressure changes into unidirectional ink flow, allowing the system to circulate ink without external assistance or additional energy-consuming components.
2Reliability
If a pump is provided to circulate ink in a common liquid chamber, then ink viscosity increase and component precipitation are suppressed, but production costs increase
Solution Approach 1:
The invention extracts and eliminates the pump component from the ink circulation system. Instead of using an active pump to circulate ink, the design relies on passive circulation through carefully engineered channel geometry with asymmetric narrow portions that create directional flow using pressure changes from the piezoelectric actuator alone.
Solution Approach 2:
The ink circulation system becomes self-service by utilizing the pressure changes naturally generated during the piezoelectric actuation process. The asymmetric channel structure converts these pressure changes into unidirectional ink flow, allowing the system to circulate ink without external assistance or additional energy-consuming components.
3Speed
If the cross-sectional area of the circulation channel is uniformly distributed, then liquid flow is smooth, but pressure change cannot be generated to drive circulation
Solution Approach 1:
The invention applies asymmetry by designing narrow portions in the circulation channel where the cross-sectional area is non-uniformly distributed. The first and second walls are tilted at different angles, creating an asymmetric geometry that generates pressure changes during ink flow. This asymmetry converts the pressure changes from piezoelectric actuation into unidirectional circulation while maintaining smooth flow through gradual area transitions.
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 solution effectively suppresses ink viscosity and component precipitation, maintaining consistent ejection quality while reducing the size and production costs of the liquid-ejecting head.
Implementation Method 1
a piezoelectric actuator provided on one surface of the channel-forming substrate. In such a recording head, the piezoelectric actuator is deformed to apply pressure to the inside of the pressure-generating chamber, thereby ejecting an ink droplet from a nozzle opening
Implementation Method 2
The circulation channel has a narrow portion including a first wall and a second wall, the first wall tilting with respect to a forward direction in which a liquid flows and serving to gradually decrease the cross-sectional area of the circulation channel toward the downstream side in the forward direction, the second wall tilting with respect to the flow direction and serving to gradually increase the cross-sectional area that has been gradually decreased by the first wall
Data Source
AI summary
A liquid-ejecting head includes a channel which is in communication with a nozzle opening and which includes a pressure-generating chamber, a circulation channel that serves to circulate a liquid in the channel, and a pressure generator that serves to generate pressure change. The circulation channel has a narrow portion including a first wall and a second wall, the first wall tilting with respect to a forward direction of a liquid flows and serving to gradually decrease the cross-sectional area, the second wall tilting with respect to the flow direction and serving to gradually increase the cross-sectional area. The tilt angle of the first wall with respect to the inner surface of the circulation channel is larger than the tilt angle of the second wall with respect to the inner surface of the circulation channel at the downstream side.