1. Brainstorm keywords related to the purpose, use, and composition of the invention
2. Look up the words in the Index to the U.S. Patent Classification to find potential class/subclasses
3. Verify the relevancy of the class/subclasses by using the Classification Schedule in the Manual of Classification
4. Read the Classification Definitions to verify the scope of the subclasses and note "see also" references
5. Search the Issued Patents and the Published Applications databases (PatFT and AppFT) by "Current US Classification" and access full-text patents and published applications
Review and References
6. Review the claims, specifications and drawings of documents retrieved for relevancy
7. Check all references and note the "U.S. Cl." and "Field of Search" areas for additional class/subclasses to search
1. Brainstorm keywords that describe your idea or invention. What does it do? How is it made? How does it work? Think about what makes your invention innovative or unique.
2. Use your keywords to begin searching in Google Patents to find similar patents. Google Patents is a very user-friendly resource because it allows you to search the full text of patents going back to 1790. Try different combinations of your terms until you find relevant patents. You can also search in the official USPTO database PatFT, but it only allows full text searching back to 1976 and is a bit more confusing to navigate.
3. When you have found a patent that looks relevant, click on the link that says "View Patent at USPTO" to see the official published version of that patent. It's important to check the USPTO version of a patent, because there are some errors in the scanned versions used by Google, and also because changes can be made to a patent's classification after they are published which may not be reflected in the version provided by Google Patents.
4. Look up the definition of the Current U.S. Classification assigned to the patent using the Manual of Patent Classification. If your patent also would fit in this class/subclass, use that number to search more precisely for relevant patents using the Advanced Search page in Google Patents or the USPTO's PatFT database (set the search option to Current US Classification).
5. Review the claims, descriptions, and drawings of all relevant patents that you find. Check references and "Cited by" notes in Google Patents, and return to Step 3 as needed.