In reference to the patent: US2949381

1 Answer 1


The patent must have expired many years ago. Patents can't be "renewed". It is the basic principle with patents that in return for exclusive ownership for a fixed period of time, once expired anyone can use the technology.

Patents filed before June 8th 1995 expire 17 years after the issue date. After that it is 20 years from the filing date. See Wikipedia

  • How long are they for? If they all vary, how do you find out? Thanks. Nov 24, 2016 at 18:14
  • It used to be 17 years from the issue date. Now it is 20 years from the application date.
    – Eric S
    Nov 25, 2016 at 3:22
  • @Jane Steinhardt: If you find my answer adequate, please accept it.
    – Eric S
    Nov 26, 2016 at 17:31
  • @Jane Steinhardt: I appreciate your thanks, but you still would love for you to accept my answer. Look for a check box near the answer.
    – Eric S
    Dec 2, 2016 at 22:40

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .