Bill Gates and several of Microsoft’s top technologists are credited as inventors in eight newly disclosed U.S. patent applications. That isn’t a surprise. But here’s where it starts to get unusual: The applications weren’t made on Microsoft’s behalf.

Why are Gates and others from Microsoft doing their “inventing” outside the realm of the company? Microsoft has an explanation, and the company says it's not as unorthodox as it might seem.

Here's what we know: An entity called Searete LLC applied for the patents. Searete is part of Intellectual Ventures LLC, the Bellevue-based invention house run by Nathan Myhrvold, Microsoft’s former chief technology officer. Myhrvold’s company has stirred controversy with its large patent hoard.

Searete's latest applications list as inventors a who’s who of Microsoft’s technological brass. Apart from Gates, they include: Craig Mundie, chief research and strategy officer; Gary Flake, one of Microsoft’s top Internet gurus; Alex Gounares, a key Microsoft online advertising executive; and Rick Rashid, the Microsoft Research chief. Microsoft itself isn’t mentioned in any of the filings.

A Microsoft spokesman said in a statement that the company is an investor in Intellectual Ventures, and that the relationship includes having some of its technologists participate in Intellectual Ventures' brainstorming sessions.

"At times, a specific innovation is created as a result of these sessions," the statement said. "When that happens, it is customary for the individuals who have contributed to the innovation to be credited if a patent application is filed."

Microsoft says it also conducts similar brainstorming sessions of its own.

An Intellectual Ventures spokeswoman described Searete as an "IV (Intellectual Ventures) holding company that holds many of the applications that arise from the invention sessions." She said she didn't know exactly when the Microsoft executives took part in the Searete brainstorming session, but said it was more than 18 months ago.

Searete’s latest batch of patent applications, which were made public Oct. 30 and list the Microsoft executives as inventors, describe various ways of figuring out how people are influenced by content on the Internet – and then rewarding content providers based on how much influence they have.

Gates is also named in earlier Searete patent applications for a method of delivering medication from a small reservoir placed inside the human body. [Techdirt has more information on some of the patents.]

The Microsoft chairman, a longtime friend of Myhrvold, is known to participate in Intellectual Ventures brainstorming sessions. And Gates has been opening himself up to more non-Microsoft pursuits since ending his everyday role at the company this summer.

But why are Microsoft’s top people coming up with ideas on behalf of a separate entity, which is then filing for patents on those ideas? Why aren't they generating ideas only for Microsoft?

Here's Microsoft's full explanation, via spokesman Michael Marinello:

"As you know, Microsoft is one of many investors in IV (Intellectual Ventures). Another part of our work with IV includes having our technologists sit in on ISF (Invention Science Fund) sponsored innovation sessions. ISF is part of IV. Several times per year ISF brings together thought leaders across industry and academia for these day long, forward ideation discussions. At times, a specific innovation is created as a result of these sessions. When that happens, it is customary for the individuals who have contributed to the innovation to be credited if a patent application is filed."

John Cook and Eric Engleman contributed to this report.