In reference to the patent: US4146939

I don't know much about patents and I can't figure out what the status is on this patent. I'm working on a new invention that attaches to this patent[US4146939]. I want to cut down my costs so my question is am I allowed to replicate and sell the product from the patent?

Many thanks


That patent was issued in 1979 and expired 17 years later. The rules changed in 1995 and now patents expire 20 years from their priority date which is usually the filing date.

  • Okay but why does it say new owner? worldwide.espacenet.com/publicationDetails/… – Joe 1978 Oct 24 '17 at 6:48
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    That was from 2003. – Eric S Oct 24 '17 at 20:48
  • So basically I can't use it till 2023? – Joe 1978 Oct 25 '17 at 7:17
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    No, the patent has to expire 17 years after grant (back then). The assignee can change hands at any time, but it doesn’t change the expiration date. This patent must have expired do you can use it. Always be aware that other patents may apply. – Eric S Oct 25 '17 at 7:53

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