Rob Giseburt Just did a great post on makezine on this.
"3D Systems is claiming that Formlabs, makers of the Form 1 3D printer, is infringing its patent “Simultaneous multiple layer curing in stereolithography.”
The Form 1, unlike most RepRap-style DIY 3D printers that use plastic
extrusion to build 3D objects, instead uses stereolithography (SL)
technology, where lasers are used to solidify UV curable material in
layers. SL technology creates 3D prints that are a much higher
resolution than can be achieved by plastic extrusion technology, and
makes the Form 1 compete in quality with 3D Systems’ higher-end printers
that cost many times more than the Form 1."
Link to the post.
Link to the patent on google documnets.
Patent number: 5597520
Filing date: Apr 25, 1994
Issue date: Jan 28, 1997
Join EFF's Efforts to Keep 3D Printing Open By Julie Samuels
Is a good blog post of the possible 3d printing patent issues.
"While many core patents restricting 3D printing have expired or will
soon expire, there is a risk that "creative" patent drafting will
continue to lock up ideas beyond the 20-year terms of those initial
patents or that patents will restrict further advances made by the open
hardware community. The incremental nature of innovation in 3D printing
makes it particularly unsuitable for patenting, as history has shown."
Link to blog post.
This seems to me to be the important part of the patent?
'"until higher layers of material are deposited so as to allow
down-facing features of the object to be located at a depth in the
building material which is equal to or exceeds a minimum cure depth that
can effectively be used for solidifying these features."
I wonder what would happen if the object was facing up not down during the build process? I am not a patent lawyer so I my wrong on this. The problem that I see when reading the patent is that it is intentionally vague in many points. So that lawyers can then argue for days if a 3d printer meets these requirements are not. I think that is why I hate lawyers they do not operate in the real world.