Controlling Inkjet Droplet Density via Bubble Timing
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Solution Overview
Problem
Inkjet printing heads face challenges in controlling material density during 3D printing, as air bubble formation can lead to inconsistent and undesirable properties in the printed objects, and existing methods to suppress bubble formation are not entirely effective.
Innovation Solution
Controlling the timing parameters of electrical pulses applied to the piezoelectric actuator in the inkjet printing head to introduce gas bubbles into the material, reducing its density to a selected value by adjusting pulse duration, period, and duty cycle, allowing for precise control of material density in each droplet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electrical pulses are applied to piezoelectric actuator to dispense material droplets, then material is deposited layer-by-layer to form 3D object, but gas bubbles form within the material reducing its density and causing inconsistent properties
Solution Approach 1:
The patent converts the harmful effect of gas bubble formation into a beneficial feature by deliberately introducing controlled amounts of gas bubbles through specific pulse timing parameters. This allows the material to achieve desired density reductions and property variations while maintaining consistent, reproducible results through precise control of the bubble introduction process.
Solution Approach 2:
The patent changes the timing parameters of electrical pulses applied to the piezoelectric actuator to control the amount and distribution of gas bubbles in the material. By adjusting pulse duration, period, and duty cycle, the material density can be precisely controlled to achieve target density values, transforming an uncontrolled harmful effect into a controllable process parameter.
2Reliability
If existing methods are used to suppress bubble formation, then material density remains consistent, but these methods are not entirely effective and require complex control systems
Solution Approach 1:
Instead of attempting to suppress and eliminate gas bubble formation, the patent inverts the approach by deliberately introducing gas bubbles through controlled pulse timing. This inversion simplifies the control strategy by working with the natural bubble-forming tendency of the system rather than fighting against it, achieving reliable density control without complex suppression mechanisms.
3Adaptability or versatility
If multiple printing heads or material changes are used to create objects with varying densities, then density control is achieved, but printing efficiency and resource utilization decrease
Solution Approach 1:
The patent makes the single printing head and material system multi-functional by enabling it to produce materials with varying densities through pulse timing control. This allows one printing system to perform what previously required multiple specialized systems, maintaining density adaptability while significantly improving printing efficiency and resource utilization.
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 method enables the formation of objects with controlled density, reducing material usage and potentially maintaining mechanical strength while making the objects lighter, and allows for the use of a single material to create objects with varying densities without the need for multiple printing heads or material changes, enhancing printing efficiency and resource utilization.
Implementation Method 1
An inkjet printing head may include piezoelectric elements. Application of an electrical pulse to a piezoelectric element may generate a pressure wave in the material that is within the printing head.
Implementation Method 2
Under some circumstances, a pressure wave may form small cavities (cavitation) within the material. Components of the material may fill the formed cavities in a gaseous state to form gas bubbles within the material.
Data Source
Figure 1
Figure 2A~2B
Figure 3A
AI summary
A printing method includes controlling timing parameters for application of electrical pulses to a piezoelectric nozzle of an inkjet printing head so as to dispense droplets of a material from the nozzle. The timing parameters are controlled to introduce gas bubbles into the droplets of material so as to reduce the density of the material to a selected density value that is less than a natural density of the material.