The United States Patent and Trademark Office (USPTO) maintains a free, searchable database that is available at http://www.uspto.gov/patents/process/search/index.jsp. Before applying for a patent, a search for similar inventions is recommended to determine whether a patent is viable.
When starting a search, one of the first considerations should be determining the key features of your invention. As an example consider Post-it® Notes, which might be described as a piece of paper with an adhesive. Additionally, consider the different ways the key features could be described. For example, paper might be referred to as a sheet or page; and an adhesive might be referred to as a sticky material, glue, or paste. Search databases typically have basic tools that will let you fine tune your search, such as logic operators like “OR” and “AND.” Searching for [word #1] OR [word #2] will return documents that have either word in the document, whereas searching for [word #1] AND [word #2] will return documents that have both word in the document. Using the example above, the search entered would be “(paper OR sheet OR page) AND (adhesive OR sticky material OR glue OR paste).” If a search results in too many results, consider if additional key features could be added to the search (e.g. Post-it® Notes can be removed and repositioned so try adding these terms to the search).
In addition to the searching tips discussed above, there are several advanced tools that can be found in the USPTO’s search help page that can help you find patents or patent publications that are relevant (http://patft.uspto.gov/netahtml/PTO/help/help.htm). If you are aware of the company selling a similar invention, you can search for documents referencing the company name (e.g. AN/Minnesota Mining and Manufacturing Company). If you are aware an inventor, you can search by the inventors name (e.g. IN/Fry-Arthur). Additionally, the search help page provides information on several other search tools that can be useful, such as searching by title, application number, patent number, etc.
Once a few relevant patents have been found, you can gather valuable information from those patents to guide further searching. Patents are classified into technology areas by classes and subclasses (See http://www.uspto.gov/web/patents/classification/selectnumwithtitle.htm). Reviewing the classes/subclasses helps you identify specific classes and subclasses that are relevant to your invention. For example, a review of U.S. Patent No. 5,194,299 shows that it is classified in class/subclass 427/208.6, 427/284 and several other classes/subclasses. A review of the classes and subclasses reveals that any patents or patent publications discussing a coating process that uses an edge or border coating will be found in class/subclass 427/284 (e.g. CCL/427/284).
These search tips can help you determine whether similar inventions exist. Once you have completed the search, please contact your Patent Attorney for additional information and assistance.