Can a previously invented technology infringe a recent 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