Google Inc. has bought 1,000 pending and issued patents from IBM Corporation in its quest to shore up its defenses against suits by other technology companies, according to documents filed with the U.S. Patent and Trademark Office. Google and IBM spokesmen wouldn't comment Friday on the purchase.

The patent transfers were recorded two weeks ago and cover a range of technologies, many of which have little to do with Google's Internet search and advertising business. One covers ways of automatically adjusting a clock, another deals with surface treatments for electrical contacts.  Phone makers that use Google Inc.'s Android software are being sued by Apple Inc. and Microsoft Corporation as a young company, Google has few patents of its own to counter with. But even patents that have little do with Google's business can be useful ammunition in the hyper-litigious technology world. If it's sued over patents by a company whose business relies on technologies covered by Google's patents, Google can file a retaliatory lawsuit.