Liquid Droplet Ejection Head Nozzle Geometry for Drive Voltage Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing liquid droplet ejection heads face challenges in reducing the drive voltage required for high-frequency operation, leading to increased heat generation and viscosity changes in the ejected droplets.
Innovation Solution
A liquid droplet ejection head with a channel member and a piezoelectric element, where the natural frequency of the channel is set to 200 kHz or more, and the nozzle diameter and taper angle are optimized to satisfy θ≥−2.3×D+65 and θ>1.9×D, allowing for reduced drive voltage application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the natural frequency of the channel is increased to 200 kHz or more for high-speed recording, then the driving frequency can be increased, but the drive voltage required to eject a predetermined amount of liquid droplet increases
Solution Approach 1:
The patent changes the geometric parameters of the nozzle (diameter D and taper angle θ) to satisfy specific relationships (θ≥-2.3×D+65 and θ>1.9×D). These parameter changes optimize the channel characteristics to achieve high natural frequency (200 kHz or more) while reducing the drive voltage required for piezoelectric element operation.
2Productivity
If high drive voltage is applied to the piezoelectric element, then the liquid droplet can be ejected at high frequency, but the heat generated by the piezoelectric element increases
Solution Approach 1:
By optimizing the nozzle diameter and taper angle parameters, the patent reduces the drive voltage requirement, which directly reduces the heat generation from the piezoelectric element according to Joule's law (heat proportional to voltage squared).
Solution Approach 2:
The patent converts the potential harmful effect of high drive voltage (heat generation) into a benefit by redesigning the nozzle geometry to require lower drive voltage, thus eliminating the heat problem while maintaining high-frequency operation.
3Temperature
If the viscosity of the liquid decreases due to heat transmission, then the droplet volume increases, but the image density becomes too high
Solution Approach 1:
The patent takes preliminary action by optimizing the nozzle geometry before heat can cause viscosity changes. The optimized parameters (θ>1.9×D) ensure that even if some heat is generated, the droplet ejection characteristics remain stable and image density is maintained within the appropriate range.
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 enables efficient ink ejection at high frequencies with lower drive voltages, minimizing heat generation and maintaining consistent ink viscosity, thereby improving image quality.
Implementation Method 1
a piezoelectric element fixed to the channel member and pressurizing liquid in the pressure chamber
Implementation Method 2
a natural frequency Fr of the channel is 200 kHz or more
Implementation Method 3
the amount of heat generated by the piezoelectric element increases based on Joule's laws. When the heat of the piezoelectric element is transmitted to the liquid in the channel
Data Source
AI summary
A liquid droplet ejection head includes a channel member and a piezoelectric element. The channel member has a channel. The channel includes a nozzle and a pressure chamber communicating with the nozzle. The piezoelectric element is fixed to the channel member and applies a pressure to liquid in the pressure chamber. The channel has a natural frequency Fr of 200 kHz or more. The nozzle has a diameter D [μm] and a taper angle θ [°] that satisfy θ≥−2.3×D+65 and θ>1.9×D.