By Josh Ong

Published: 08:30 PM EST (05:30 PM PST)

Google has continued its run of intellectual property purchases by acquiring 1,023 patents from IBM in an effort to shore up the defenses of its Android mobile operating system.

The U.S. Patent and Trademark Office revealed the purchase after recording the patent transfers on Tuesday, as noted by SEO by the Sea. Google spokesman Jim Prosser confirmed the transaction, but declined to provide details of the deal, which took place on Aug. 17, according to the USPTO's records.

The fact that the Mountain View, Calif., software company purchased more than a thousand patents from IBM just two days after announcing its $12.5 billion acquisition of Motorola points to its continued interest in building up its patent portfolio, even after staking its claim on Motorola's 17,000 issued patents and 7,500 ongoing applications.

This isn't the first time Google has turned to the well-established technology giant for inventions, as the company purchased a batch of 1,030 patents from IBM in July.

A relatively young technology company given its size, Google has found its smaller IP collection easily outmatched by competitors. CEO Larry Page said last month that the Motorola merger came as an effort to "better protect Android from anti-competitive threats from Microsoft, Apple and other companies."

Google recently complained that its rivals are conspiring against it by banding together to purchase groups of "bogus patents" from Novell and Nortel. In late June, Apple led a consortium including Microsoft, Sony and Research in Motion in bidding against Google. As for the Novell patents, Microsoft claims that Google was actually invited to join the group but declined.

The patent dispute between Apple and Android ratcheted up earlier this month when handset maker HTC took patents it had recently received from Google and promptly sued Apple for infringement. Google itself had received the patents from Palm, Motorola and Openwave over the past year.

Apple is locked in several fierce legal battles with major Android vendors, such as Samsung, Motorola and HTC. The iPhone maker recently won a permanent ban on Samsung's Galaxy Tab 10.1 tablet in Germany and an initial victory in its complaint against HTC with the U.S. International Trade Commission.

Android vendors are also facing a patent royalty assault from Microsoft. On top of a major licensing deal with HTC that may provide $5 per Android smartphone sold, Microsoft has struck patent licensing agreements (1, 2) with Acer, Viewsonic, Wistron Corp., Velocity Micro, General Dynamics and Onkyo Corp.