Question of the Week: PolyJet Patents

By on January 7th, 2022 in news, question

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Diagram from the original PolyJet patent of 1999 [Source: Google Patents]

This week’s question is about expiring patents.

This week’s question focuses on the expiration of Stratasys-owned PolyJet patents.

Fabbaloo reader Robert Win asks:

“I came across your article on the expiring 3D printing patents, namely 3D System’s MJP and what it may mean for the industry and found it very interesting.

I’d like to ask whether you know when the Stratasys PolyJet patent is set to expire as I believe that may be just as significant.”

Indeed patents are quite important. It was the expiration of Stratasys’ original patent in 2009 that allowed companies like MakerBot and Ultimaker to emerge, and from them grew the entire desktop 3D printing industry. That’s a big deal today, as many of these companies have grown to a state where they’re actually eating some of Stratasys’ original market.

US patents, when granted, offer the submitter a period of 20 years during which they have exclusive rights to commercially use the method described in the patent. Should someone else use the same method (and by “same” I mean in the view of the patent holder), the patent holder may sue the other party for patent infringement. Usually this results in either dismissal because the other party’s use didn’t really infringe, or a settlement because it does.

During the patent period holders leverage their temporary monopoly as much as possible, hoping to build up a large business before expiry. At the end of the expiry, something has to happen to the patent holder’s business model, otherwise they’ll fail.

In the case of Stratasys, their business model changed soon after their key patent expiry by the acquisition of Objet, which was in the same business and still had active patents of their own. Stratasys effectively jumped from one patent monopoly to another.

Back to the question: what happened to these Objet patents?

Looking through the databases, it seems that Objet’s key patent for the PolyJet technology was US6259962B1, with inventor Hanan Gothait, and currently assigned to Stratasys.

By the way, Gothait was the original founder and CTO of Objet Geometries back in 1998. He left the company in 2004 and is now the CEO of XJET.

This particular patent, “Apparatus and method for three dimensional model printing”, is described as follows:

“Apparatus and a method for three-dimensional printing of a three-dimensional model is provided. The apparatus includes a printing head having a plurality of nozzles, a dispenser connected to the printing head for selectively dispensing interface material in layers and curing means for optionally curing each of the layers deposited. The depth of each deposited layer is controllable by selectively adjusting the output from each of the plurality of nozzles.”

This is patent-lingo describing the PolyJet process, wherein photopolymer resin is deposited in layers, each cured by a UV light source. Stratasys has leveraged this technology over the years into today’s amazing full color technology that can reproduce astonishingly realistic 3D prints. They do this by mixing different “inks” in the photopolymer resins to create any required color on a voxel-by-voxel basis.

Patent US6259962B1 was filed on March 3, 1999, and was granted in July of 2001. However, the 20 years of patent exclusivity begins at the filing date, not the grant date. Thus, this patent actually expired on March 3, 2019 — going on three years ago.

This opened up the possibility that others could use that method to produce 3D printers of similar capability — or at least to the original specification in the patent. There’s likely additional later-dated patents from Stratasys involving full color, etc.

As patents are publicly displayed, it’s certainly possible that future competitors could see the expiry date and work behind the scenes to develop an alternative device for launch literally on expiry day. That has happened in other industries.

Have we seen devices of this type emerge since 2019? Are there new MakerBots and Ultimakers rolling with this method?

Not so much. I don’t recall any companies making much use of this tech, even though it is now apparently available for general use. The only two that seem similar are Mimaki, which makes a full color 3D printer, not a general purpose device, and dp polar. If there are any general purpose PolyJet clones, they certainly haven’t made big waves on the 3D print scene, at least not yet.

There is a possible reason for this absence: PolyJet is a challenging technology.

If you’ve ever used PolyJet (and I have), it’s a complex process involving proprietary toxic resins, precision equipment and a lot of support material.

PolyJet objects are made with liquid that is dropped from inkjet heads. As such, there isn’t any possibility of overhangs in the printed object, so support material must be used everywhere there is even one degree of overhang. That requires a fair amount of pricey support material, in addition to the pricey material for the model itself. You must dissolve the support material afterwards in a messy post processing process.

PolyJet does produce amazingly good 3D prints, but it’s work and expense to do so. Anyone making an alternate PolyJet-like system would result in much the same kind of machine and experience — and costs.

That would automatically limit the potential commercial market to a smaller size.

Now, compare that with the ease and safety of the FDM process from Stratasys that was used by MakerBot and Ultimaker to produce their FFF equipment. Devices could be made ready for printing at far less expense, meaning the resulting equipment could be sold in large quantities to more buyers. The business case seemed appropriate, and that’s why the big push to consumers happened.

An alternate PolyJet maker would face a much more difficult situation: they’d have a smaller market to sell into, and guess what — there are already plenty of competitors with high quality resin options available that use other, simpler processes. The only difference is that Polyjet has the possibility of using multiple materials; that’s how they achieve the full color system.

This same dilemma faced Stratasys, and that is why you see them focusing PolyJet towards the full color options as much as possible: that market is mostly clear of competitors, and so they have a chance to succeed.

Should a third party attempt to make a full color PolyJet solution, they’d likely find a color patent or two still in force. They’d also be competing with Stratasys and Mimaki, and they’d lose because they’re too late.

The answer the original question is: I don’t think the patent expiry will be significant in the long run.

By Kerry Stevenson

Kerry Stevenson, aka "General Fabb" has written over 8,000 stories on 3D printing at Fabbaloo since he launched the venture in 2007, with an intention to promote and grow the incredible technology of 3D printing across the world. So far, it seems to be working!

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