Piezoelectric Actuator Ink Heating via Volume Deformation
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Solution Overview
Problem
Existing liquid droplet jetting apparatuses face challenges in maintaining stable jetting performance due to variations in ink viscosity caused by temperature changes, which complicates the manufacturing process and requires complex voltage control and heating mechanisms, leading to inefficient heating and prolonged warming times.
Innovation Solution
A liquid droplet jetting apparatus with a piezoelectric actuator that alternates between different volume states in the pressure chamber to heat the ink without jetting, using a controller to perform specific deformation operations in both jetting and warm-up modes, allowing for efficient heating and stabilizing the jetting performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heater is provided to maintain ink temperature, then the ink temperature can be kept constant, but the device becomes expensive and heating takes time
Solution Approach 1:
The piezoelectric actuator is made to serve dual functions: jetting ink droplets and heating the ink. By applying voltage to the piezoelectric element, it generates heat through deformation while simultaneously pressurizing the ink chamber, eliminating the need for a separate heater component.
Solution Approach 2:
The piezoelectric actuator uses its own operational byproduct (heat generated during deformation) to warm the ink, making the system self-sufficient for temperature control without requiring external heating devices.
2Temperature
If drive voltage is controlled to be low during heating, then ink temperature increases, but the heating effect is insufficient
Solution Approach 1:
The piezoelectric actuator is driven with periodic voltage pulses that cause repeated deformation cycles. This periodic action accumulates heat over time while maintaining low average power, enabling effective ink heating without continuous high-voltage application.
Solution Approach 2:
The voltage waveform parameters (amplitude, pulse width, frequency) are optimized to maximize heat generation in the piezoelectric element while minimizing ink jetting. By adjusting these parameters, sufficient heating effect is achieved at low drive voltage levels.
3Reliability
If voltage ranking and waveform control are implemented, then jetting performance can be maintained, but manufacturing complexity increases
Solution Approach 1:
Instead of complex voltage ranking systems, the invention uses standardized voltage waveforms with adjusted parameters (amplitude, pulse width) that work across different operating conditions. This simplifies the control system while maintaining reliable jetting performance through parameter optimization rather than multiple voltage levels.
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 approach enables efficient heating of the ink, stabilizes the jetting performance, and reduces the risk of accidental droplet ejection, while also minimizing the complexity of voltage control and heating processes, allowing for faster warming of the ink.
Implementation Method 1
a pressure wave is generated by applying a voltage to a piezoelectric actuator, and a liquid such as an ink is made to be jetted from fine holes called nozzles
Implementation Method 2
when a voltage is applied to a piezoelectric element, a deformation directly proportional to a strength of an electric field occurs (inverse piezoelectric effect), and causes heat generation by the piezoelectric element
Data Source
AI summary
In a liquid droplet jetting mode of jetting liquid droplets, a controller controls a piezoelectric actuator to perform a liquid droplet jetting operation in which volume of a pressure chamber is decreased to a decreased volume smaller than a predetermined volume, and then the volume of the pressure chamber is increased to an increased volume greater than the predetermined volume, and the volume of the pressure chamber is again decreased to the decreased volume. On the other hand, in a warm-up mode of heating the liquid in the pressure chamber, the controller controls the piezoelectric actuator to perform at least one of a first warm-up operation in which the volume of the pressure chamber is changed repeatedly between the predetermined volume and the increased volume, and a second warm-up operation in which the volume of the pressure chamber is changed repeatedly between the predetermined volume and the decreased volume.