11 ms·

It's from the priority date, which was Aug 29, 1986 making this expired. https://en.wikipedia.org/wiki/Term_of_patent_in_the_United_States https://en.wikipedia

• tzs 10y ago
  From 35 USC 154(a): (2)Term.— Subject to the payment of fees under this title, such grant shall be for a term beginning on the date on which the patent issues and ending 20 years from the date on which the application for the patent was filed in the United States or, if the application contains a specific reference to an earlier filed application or applications under section 120, 121, 365(c), or 386(c), from the date on which the earliest such application was filed. (3)Priority.— Priority under section 119, 365(a), 365(b), 386(a), or 386(b) shall not be taken into account in determining the term of a patent. For this patent, there is a chain of specific references to earlier filed applications, but I'm not sure which of those, if any, are under section 120, 121, 365(c) or 386(c) and so affect the expiration date of the patent.