Droplet Delivery Device Using Charge-Neutralizing Pre-Drops
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Solution Overview
Problem
Electrostatic ejection type inkjet heads face challenges in accurately ejecting ink droplets due to electrostatic charging issues and uneven electric field distributions on the object surface, leading to misplacement of ink droplets.
Innovation Solution
A droplet ejection device utilizing a combination of piezo and electrostatic ejection mechanisms, where a first liquid droplet with volatile material is used to neutralize the object surface, followed by a second droplet with controlled electrostatic ejection to stabilize the deposition, synchronized to ensure precise placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electrostatic ejection type inkjet head is used, then finer liquid droplet can be ejected, but ink ejection becomes difficult due to electrostatic charging of object and droplet placement accuracy deteriorates due to uneven electric field strength distributions
Solution Approach 1:
The patent applies preliminary action by first ejecting a conductive liquid droplet to neutralize electrostatic charge on the object surface before ejecting the actual ink droplet. This preliminary charge neutralization step prepares the surface to receive subsequent droplets accurately, preventing deflection caused by electrostatic repulsion and ensuring stable, precise placement throughout the printing process.
Solution Approach 2:
The patent uses conductive liquid as an intermediary substance between the electrostatic field and the ink droplets. This intermediary conductive droplet acts as a charge carrier that equalizes the electric potential on the object surface, creating a more uniform electric field environment for subsequent ink ejection and improving overall placement accuracy.
2Reliability
If conventional surface treatments like plasma or UV ozone are applied, then ink droplet ejection stability is improved, but device complexity and process time increase
Solution Approach 1:
The patent extracts and eliminates the need for complex external surface treatment systems (plasma generators, UV ozone equipment) by implementing a simpler integrated solution. The electrostatic ejection head itself is modified to include charge neutralization capability, removing the separate surface treatment step while maintaining droplet ejection stability.
Solution Approach 2:
The patent applies multi-functionality by designing the electrostatic ejection head to perform both ink droplet ejection and charge neutralization functions in one device. The same ejection mechanism that deposits ink also deposits conductive liquid for charge neutralization, eliminating the need for separate surface treatment equipment and simplifying the overall system.
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
Enables stable and precise ejection of droplets onto the object surface, reducing the need for surface treatments like plasma or UV ozone, and minimizing damage to the object.
Implementation Method 1
a piezo element 145 that deforms a nozzle 141 to apply pressure to the first liquid 143 and eject the first liquid droplet 147
Implementation Method 2
the first liquid droplet 147 includes a volatile material 148 and the volatile material 148 neutralizes an electrostatic charge on a surface 200 of the object 200
Implementation Method 3
an electrostatic ejection type inkjet head, which can eject a finer liquid droplet
Data Source
Figure 1
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AI summary
A liquid droplet ejection device includes a first liquid droplet ejection unit including a first liquid holding unit configured to hold a first liquid and a first tip configured to eject a first liquid of the first liquid holding unit as a first liquid droplet, a second liquid droplet ejection unit including a second liquid holding unit configured to hold a second liquid and a second configured tip to eject the second liquid of the second liquid holding unit as a second liquid droplet differing from the first liquid droplet, an object holding unit configured to hold an object the first liquid and the second liquid being ejected to the object, a driving unit configured to move the first tip and the second tip in a first direction relative to the object holding unit, and the first tip is arranged in the first direction relative to the second tip.