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Printing with droplets

A project log for open hardware fast high resolution LASER

AKA Hexastorm

HexastormHexastorm 07/16/2019 at 12:450 Comments

Let's quickly read, Inkjet Technolgy for Digital Fabrication, IAN M. Hutchings. There are various ways to create droplets such as Continuous Inkjet and Drop On Demand (DOD).
A well known challenge with DOD technologies are the limits with respect to viscosity.  Continuous inkjet allows for higher viscosity but the stream has to be broken up into droplets and droplets need to be selected.
In Continuous Inkjet generation an electric field can be used to position the droplets, see Sweet 1965.
Rejected droplets can be put in a container and reused.
This requires a conductive ink. For non-conductive inks, Kodak has explored alternative selection techniques to select the droplets via air. A patent on droplet selection can be found here US8544974.
The liquid stream has to be forced to break up into droplets when the liquid stream leaves the nozzle. As man, you might recall from peeing that the stream doesn't break up into droplets immediately when the liquid leaves the nozzle.
A way for doing this is via a piezoelectric effect or heating.  The droplets can be detected by a stroboscope and a camera.
I claim that the Hexastorm is used to force the break up of droplets in a continuous inkjet head using heating. I claim that the Hexastorm is used to detect the position of one or more droplets.
I then claim that the Hexastorm is used as a selection mechanism to evaporate certain droplets or push them away by colliding them with another droplet generated with laser induced forward transfer.
I claim that the Hexastorm is used to emit a droplet from one stream via LIFT and then merge it into another droplet.
Likewise, I claim the same things for a drop on demand system where droplets are ejected by acoustic energy, piezoelectric effect or thermal effect. Again the Hexastorm can be used to detect the position of droplets, see if nozzles are clogged and calibrate the inkjet head by checking the position of droplets either upon the substrate or in the air.
Light can be used to cure liquids so they become conductive via so called flash curing. In some novel conductive inks nano-particles are dissolved. The solvent is used to lower the viscosity and facilitate transportation in the head. If the ink is on the substrate, the solvent must be removed which is done via flash curing.
They could also cure UV inks and vary the dosage per ink using optical coherence tomography. Or use OCT to check wether the conductive ink is fully cured. This could be very interesting for companies like Luxexcel. They try to create optical components with droplets, see patent application EP2412767A1.

Anyway, what might be of interest to the reader is the work of Georg von Hippel from the MIT Sloan school of Management.

At the moment, l I am a bit done with creating prior art and will move back to building the scanner!

People who think I am over doing it with the claims should read about the patent war between formlabs and DWS. Basically, DWS patented the idea of heating a liquid in a bottom up projection photo-polymer printer. I agree with Formlabs this is not novel at all but also agree with DWS that this is a typical 3D printing patent. Stratasys has a very similar patent on a heating build chamber for fused filament printers.

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