Can a previously invented technology infringe a recent patent?

You have not really provided enough facts to truly determine the correct situation. For example, when you say that you kept the technology confidential, was it still in public use but could not readily be determined/detected. The classic Coca-Cola situation comes to mind - allegedly, for years, the precise composition of Coke was a trade secret, yet Coke was being publicly sold - therefore, Coca-Cola themselves could not get a patent because the composition had been in public use for years, and no one else could get a patent for the composition for the same reason - according to 35 USC 102(a), a person is entitled to a patent unless the subject matter was in use or on sale prior to the effective filing date of the patent application. So, in Coca-Cola's case, no one can get a patent. So, if your situation is the same - the technology is still, in effect, confidential, but it has been in public use for two years, then no one can get a patent on it, and you will not infringe the patent if they obtain the patent, or if they obtain the patent and allege infringement against you, you can effectively invalidate their patent based upon public use prior to their filing for their patent. On the other hand, if you did not publicly use the technology, then this other party could in fact obtain a patent and then you would likely infringe their patent.

Hi,

You are describing a situation were you kept a trade secret and another third party filed a patent on it.
In general - First, you are barred most likely from getting a patent on your technology, because its considered public use and it's over a year. There are fine deals that matter and going over it with an attorney will let you know if your barred 100% or not (sometimes you can still get method claims and not apparatus and vice versa).
Second, the third party can file on it (most likely) and not be barred. So their patent is valid, because your use was secret to them. Unless your use was informing (complicated issue).

Lastly, there is a defense for you if you are indeed infringing under 35 USC section 273. You can still use your trade secret, but your use doesn't invalidate their patent. Your use is like a limited free license to operate, but it is non-transferable.

Please note this is general information, and your case will have details that need a hired attorney to answer. You may want to try and invalidate their patent, you may want to know if you really are infringing, you may want to know if your barred from filing on some things etc... there are many issues.

Hope this helps!
Mary

Yes. You will

No, you will not be an infringer.