Google's Patent Search, launched in beta last month, has come under fire over its use of optical character recognition software to make available more than seven million files in the US Patent and Trademark Office (USPTO) database. 

Google Patent Search includes visual images of the words and drawings contained in patent specifications filed with the USPTO. 

The service emphasises the patent illustrations by randomly displaying five images on its main search page that showcase patents in the database, many of which are significant pieces of intellectual property.

Doug Banks, a software engineer at Google, said that Patent Search "uses much of the same technology that powers Google Book Search, so you can scroll through pages and zoom in on text and illustrations just like you can with books".

However, the howls of anguish over copyright infringement elicited by the Book Search tool are likely to be averted with the Patent Search tool.

"This is a natural extension of our mission to make public-domain government information more easily accessible," said Banks.

But alarmed intellectual property specialists in the US are warning that the OCR software used to scan the patents means that results can be incomplete and inaccurate.

Google's Patent Search does make for entertaining browsing, however. Check out the patents for a Pocket Protector (a device to prevent leakage from pockets), a Combined Scarecrow and Advertising Device, and a Device for Cooling an Infant's Brain.