The purpose of doing a search for previously filed patents or applications is to determine whether the particular creation exists or has been disclosed to the public. In either event, the previous creation or disclosure of the invention may disrupt the ability to secure patent rights.
Patent Search Methods
The USPTO provides a database where you can conduct free searches of awarded patents since 1976 and patent applications since 2001. The database contains images of patents filed before 1976, but the entire text of the patent is not searchable.
Google offers a patent search engine that is also very effective method of searching for previously granted patents and patent applications. The google search engine has the same information as present in the USPTO database.
You may also visit a local Patent and Trademark Depository Library (PTDL), a network of libraries containing all patents previously filed with the USPTO. Numerous third-party companies provide patent searches for a fee.