With the acquisition of 1,023 patents from International Business Machines Crop. (IBM), Google is continuing with building its intellectual property arsenal to protect Android.

The new patents range from signature verification system for documents to display system with image scanning apparatus.

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.

This is Google's third move since July to strengthen its patent portfolio to counter litigation from rivals like Apple and Microsoft.

In July, Google acquired more than 1,030 patents from IBM. In August, it went way ahead of IBM's number and acquired Motorola, gaining access to the hardware company's gamut of 17,000 patents by paying $12.5 million. The Google-Motorola deal raised fears that some top Android vendors could seek other platforms for their smartphones.

Google is mainly trying to protect Android. Patents is what they are after, Florian Seiche, head of Europe, Middle East and Africa for HTC, told Reuters in an interview after the deal took place last month.

Google, HTC and others using the platform have been under numerous legal challenges from the likes of Apple and Microsoft. Apple has also seen the first courtroom success in its attempts to block Samsung from selling some of its Android devices.

The Motorola acquisition has given Google access to one of the mobile phone industry's largest patent libraries. The company had been under pressure to build a patent portfolio after losing out to Apple, Microsoft Corp and others in a recent auction of bankrupt Nortel's assets.