To answer the "how do I figure it out" question: The assignee at the time the patent issues, if there is one, will be listed on the front page of the patent. As bta said, the ownership can change after that. Those changes are not reflected by changes on the front page of the patent. Once granted and published, the patent document is static. The USPTO has a recordation office where people and companies buying and selling (assigning) patent rights can register a transaction. It is very much like recording a deed for a property transaction at the county courthouse. Google patents has started grabbing that data and posting it at the end of their information about a patent.
In this patent you can see that the inventors assigned the application to MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD., JAPAN while the application was still pending. It was then assigned to MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.;US and finally a change of name was filed from MATSUSHITA to Panasonic. This all happened before issue but in many cases there is a change of ownership many years after issue.
I have not calculated this carefully but this patent would normally be in force for 20 years after the US filing date in 2006. You can see on the front page that it was given 1190 extra days to make up for patent office delays. That would put it in 2029 or so as long the maintenance fees are paid and there is not terminal disclaimer.