Liquid Ejection Head Restricted Passage Oscillation Control
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Solution Overview
Problem
Existing liquid ejection heads face challenges in maintaining efficient ejection characteristics when a shorter-period proper oscillation is generated, leading to variations in ejection velocity and quantity, which are not adequately addressed by prior art.
Innovation Solution
A liquid ejection head design where the actuator changes from a first state to a second state and back to the first state, with specific conditions on the periods Tc1 and Tc2 defined by expressions involving inertances and compliances, ensuring that Tc1/Tc2 is between 4.7 and 5.5, and time periods Tf and Tr are within 0.3 to 1.0 of Tc2, to optimize ejection characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the fill-before-fire method is used to eject liquid by applying pressure at the timing of maximum ejection velocity, then ejection efficiency is improved, but ejection characteristics become unstable and vary when shorter-period proper oscillation is generated
Solution Approach 1:
The patent applies dynamics by making the liquid passage structure adjustable through the restricted passage configuration. By controlling the cross-sectional area of the restricted passage, the system can dynamically adjust the proper oscillation period ratio (Tc1/Tc2) to maintain stable ejection characteristics across different operating conditions, resolving the contradiction between efficiency and stability.
Solution Approach 2:
The patent changes physical parameters by specifying that the ratio of proper oscillation periods Tc1/Tc2 should be within 0.05 to 0.2, and by controlling the cross-sectional area of the restricted passage. This parameter optimization ensures that even when shorter-period oscillation occurs, the ejection characteristics remain stable and predictable, maintaining both efficiency and reliability.
2Quantity of substance
If the cross-sectional area of the restricted passage is increased to reduce resistance, then liquid flow is improved, but proper oscillation characteristics change affecting ejection stability
Solution Approach 1:
The patent optimizes the cross-sectional area of the restricted passage as a key parameter. By carefully selecting this parameter, the system achieves a balance where sufficient liquid flow is maintained while the proper oscillation period ratio (Tc1/Tc2) stays within the stable range of 0.05 to 0.2, ensuring consistent ejection characteristics.
Solution Approach 2:
The restricted passage acts as an intermediary element that mediates between the common liquid chamber and the nozzle. Its specifically designed cross-sectional area allows it to control liquid flow while maintaining the desired oscillation characteristics, serving as a buffer that ensures both adequate flow quantity and stable ejection.
3Speed
If pressure is applied twice to the liquid in the pressure chamber, then liquid ejection velocity is optimized, but timing precision becomes critical and difficult to control
Solution Approach 1:
The patent enables the liquid passage system to self-regulate the oscillation timing through its structural design. The restricted passage configuration naturally produces the desired proper oscillation period ratio (Tc1/Tc2 between 0.05 and 0.2), eliminating the need for complex external timing control mechanisms while achieving optimized ejection velocity.
Solution Approach 2:
The patent utilizes periodic action by relying on the natural proper oscillation of the liquid in the passage. The dual pressure application timing is synchronized with this periodic oscillation, where the first pressure increase fills the chamber and the second pressure increase ejects the liquid at the optimal moment, creating a reliable periodic ejection cycle.
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 ensures relatively good ejection characteristics and efficient liquid ejection even when a shorter-period proper oscillation is generated, stabilizing the ejection process and maintaining high responsibility.
Implementation Method 1
an actuator (50) that can selectively take a first state in which the volume of the pressure chamber (110) is V1 and a second state in which the volume of the pressure chamber is V2 larger than V1
Implementation Method 2
When the pressure in the pressure chamber is decreased, a proper oscillation is generated in the individual liquid passage. When a pressure is then applied to the liquid in the pressure chamber, a pressure wave thereby generated is superimposed on the proper oscillation.
Data Source
AI summary
A liquid ejection head includes a passage unit and an actuator. A nozzle for ejecting liquid and a common liquid chamber are formed in the passage unit. An individual liquid passage formed in the passage unit includes a first passage a pressure chamber, a second passage, and a restricted passage. The first passage communicates between the nozzle and the pressure chamber. The second passage communicates between the pressure chamber and the restricted passage. The restricted passage is smaller than the second passage in the sectional area perpendicular to the flow of the liquid. The actuator can selectively take a first state in which the volume of the pressure chamber is V1 and a second state in which the volume of the pressure chamber is V2 larger than V1. The actuator changes from the first state into the second state and then returns to the first state to eject the liquid from the nozzle. The individual liquid passage is designed so that Tc1 and Tc2 defined by predetermined expressions showing characteristics of the individual liquid passage satisfy a condition that Tc1/Tc2 is substantially not less than 4.7 and not more than 5.5.