In the last two months Microsoft has filed 500 patents with the US Patent and Trademark Office.

Microsoft's patent push has been stimulated by a number of factors including competition and trying to make sure Microsoft's rivals don't get access to key innovations.

However, the company also begun a broad intellectual property licensing push several years ago, under which it licenses technology to many companies big and small. The company has signed a slew of patent cross licensing deals since then, the most recent being Tuesday's deal with Japan's JVC.

Trolling through filings can offer a glimpse of where a company is headed, but as with Apple's closely watched patent filings, seeing something in a patent application is far from a guarantee of what will eventually ship.

A number of Microsoft's recently published patent applications cover search and advertising, areas in which Microsoft is investing significant amounts as it tries to play catch-up with Google. Recent filings cover things such as creating a spot market for video ads, and creating marketing that uses a combination of video and banner advertisements.

Among the other patent filings are hardware designs such as a washable keyboard and a washable mouse.

One patent which has been receiving recent controversy covers a means by which a computer that can use factors such as a person's heart rate, blood pressure, and facial expression to take action.

There have been concerns about the "Big Brother" implications such a technology could have, such as notifying an employer if a worker appears stressed or is not being productive.

Microsoft's vice president of intellectual property and licensing Horacio Gutierrez, commented on the patent in a statement:

"This particular patent application, in general, describes an innovation aimed at improving activity-monitoring systems and uses the monitoring of user heart rate as an example of the kind of physical state that could be monitored to detect when users need assistance with their activities, and to offer assistance by putting them in touch with other users who may be able to help."

"It is important to keep in mind that with most organisations in the business of innovation, some of our patent applications reflect inventions that are currently present in our products, and other applications represent innovations being developed for potential future use," he continued.

Another patent covers so called managed copy, which takes things such as video files or DVDs, and uses digital rights management (DRM) to enable people make a copy that can be used on their various digital devices but does not allow unlimited duplication.

Meanwhile, IBM Nokia and Sony are moving in the opposite direction, creating an Eco-Patents Commons for eco-friendly patents. Participants who submit patents into the Eco-Patents Commons pledge not to enforce those patents against others who use them.