Inkjet Head Nozzle Diameter and Natural Frequency Optimization
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Solution Overview
Problem
At high driving frequencies, inkjet heads face challenges in ejecting liquid droplets in sufficient amounts for recording without linking due to increased pressure resonance, requiring shorter pinch-off times and higher natural frequencies, which are difficult to achieve without reducing droplet size or increasing piezoelectric element rigidity, leading to energy inefficiencies.
Innovation Solution
A liquid droplet ejecting head with a nozzle diameter and channel natural frequency optimized by satisfying specific expressions (D≤−2.25×10−8×Fr^4+2.11×10−5×Fr^3−7.60×10−3×Fr^2+1.32×Fr−62.9 and D≥0.050×Fr+8.5) to balance pinch-off time and droplet amount, ensuring stable ejection and sufficient ink delivery at high frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the nozzle diameter is reduced to shorten the pinch-off time, then the liquid droplet ejection speed is improved, but the amount of liquid droplet ejected is reduced
Solution Approach 1:
The patent optimizes the nozzle diameter within a specific range (20-40 μm) to balance the pinch-off time and droplet amount. By carefully selecting and controlling the nozzle diameter parameter, the system achieves both high-speed ejection and sufficient droplet volume for recording purposes.
2Speed
If the rigidity of the piezoelectric element is increased to raise the natural frequency of the channel, then the liquid droplet ejection speed is improved, but the energy required for deformation is increased
Solution Approach 1:
The patent optimizes the thickness of the piezoelectric element within a specific range (2-5 μm) to achieve the desired natural frequency while controlling the energy consumption. By precisely controlling the thickness parameter, the system raises the natural frequency for high-speed ejection while keeping the deformation energy within acceptable limits.
3Productivity
If the driving frequency is increased to achieve high-speed recording, then the productivity is improved, but the liquid droplets become linked due to insufficient separation time
Solution Approach 1:
The patent optimizes the nozzle diameter within a specific range (20-40 μm) to achieve an appropriate pinch-off time that ensures complete separation of liquid droplets even at high driving frequencies. This parameter optimization allows the system to maintain droplet stability and prevent linking while achieving high-speed recording capability.
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 optimized design allows for stable ink droplet ejection without linking, maintaining sufficient droplet amount for high-quality recording at high frequencies, while ensuring the durability and efficiency of the piezoelectric element by adjusting the nozzle diameter and natural frequency.
Implementation Method 1
a piezoelectric actuator (piezoelectric element) generates a pressure in the inside of the pressure chamber to thereby eject a liquid droplet of a liquid from the nozzle
Implementation Method 2
focuses on an influence of a pressure resonance generated in the inside of the pressure chamber
Data Source
AI summary
There is provided a liquid droplet ejecting head including: a channel member having a channel which includes a nozzle and a pressure chamber communicating with the nozzle; and a piezoelectric element arranged on the channel member and configured to apply a pressure to a liquid inside the pressure chamber to eject a liquid droplet of the liquid from the nozzle. A diameter D [μm] of the nozzle and a natural frequency Fr [kHz] of the channel satisfy Expressions 1 and 2 as follows: Expression 1: D≤−2.25×10−8×Fr4+2.11×10−5×Fr3−7.60×10−3×Fr2+1.32×Fr−62.9, Expression 2: D≥0.050×Fr+8.5.