According to the Wikipedia page on Simplex noise:

Uses of implementations in 3D and higher for textured image synthesis are covered by U.S. Patent 6,867,776, if the algorithm is implemented using the specific techniques described in any of the patent claims. The patent is expected to expire on January 8, 2022.

That date has recently passed, but there was no update to the article about any change to the patent status. Following the reference to the patent itself, it shows the following entries:

2022-01-08 - Anticipated expiration

Status - Active

What exactly does this mean? Is the algorithm still protected by the patent?

  • You can request notice from the patent office.
    – Trish
    Jan 29, 2022 at 21:07
  • 3
    You've linked to Google, not the USPTO. There's a good chance Google doesn't re-scrape the USPTO's details about every patent ever day, and the USPTO might not update their website for expirations on a daily basis in the first place. The linked Google page does say "Expired - Lifetime" today (Jan. 30, 2022).
    – nobody
    Jan 30, 2022 at 18:47
  • 2
    I’m voting to close this question because this belongs to patent.stackexchange; it does not ask about patent law, but exclusively facts relating to a specific patent. If this is not a patent.stackexchange question, nothing is.
    – kisspuska
    Jan 31, 2022 at 8:20
  • @kisspuska the overview on Ask Patents says "for people interested in improving and participating in the patent system". I decided not to post there since I'm not trying to do either. Jan 31, 2022 at 16:55
  • 2
    Further, something being on-topic elsewhere does not make it off-topic here.
    – Ryan M
    Feb 2, 2022 at 0:13

1 Answer 1


What exactly does this mean? Is the algorithm still protected by the patent?

Assuming, without independently confirming, that the patent in question has indeed expired (and it would be very unusual for a patent of this kind to be extended near the end of its term), the claims made in the patent for which it sought patent protection are now part of the public domain and may be used without a royalty and without permission from the patent holder.

One should proceed with caution, however, because often an implementation of a patent also utilizes other patents with different claims that have a different expiration date. In a complex device, it wouldn't be unusual for dozens of patents to come into play. Likewise, an implementation of a patent may be associated with some trademark protections (like a distinctive, non-functional design associated with a particular company), or with derivative work copyright protections.

So, if you want to implement an expired patent in a manner that does not infringe other patents, copyrights, or trademarks, ideally you would confirm that there are not also other patents, copyrights, or trademarks that are still in force that govern some aspect of how you apply the expired patent.

  • From the language "anticipated expiration", it seems to suggest the possibility of some intervening circumstance that could prevent it from expiring on that date (although it appeared no such circumstance occurred). Do you have any ideas about what that could be? Is it simply in case of a last-minute extension? Jan 31, 2022 at 0:02
  • @HymnsForDisco The main reason patents are extended involves drug patents where there was a delay in FDA approval. whitcomblawpc.com/additional-blogs-of-interest/…. A change in the law could also have this effect.
    – ohwilleke
    Jan 31, 2022 at 0:04
  • 2
    I suppose someone wanted to be on the safe side. If I wrote “the patent will expire”, and you rely on it, and it doesn’t expire because my calculation is wrong, I might have a problem. Much safer to write “is expected to expire”. A trivial reason could be a European misreading 8/1/22 as Jan 8th instead of Aug 1st.
    – gnasher729
    Jan 31, 2022 at 0:41
  • 1
    Besides the standard term of 20 years from filing term length can be added to by “patent term extension”. It is a complicated calculation based in events in the prosecution history. At one point the USPTO’s interpretation of the rules was overturned by the courts and patent owners who had protested the interpretation got longer terms. Also non-payment if maintenance fees can cut the term short. Anticipated is a good word for this situation. Feb 12, 2022 at 23:01

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