Go to the official website of the United States Patent and Trademark Office. Use the "Full-Text and Image Database" search to check existing patent applications and images. Both full applications and images are available for patents filed after 1975. You can also search imaged copies of applications filed between 1790 and 1975. Search existing patents using words that appear in or describe your idea. Check all results against your idea.
Locate the Patent and Trademark Depository Library nearest you. The staff can help you with researching patents and questions about similarities between your idea and an existing patent. Use the library search on the United States Patent and Trademark Office's official website to find a library in your state.
Contact the USPTO's Public Search Facility in Virginia at 571-272-3275 for information about visiting in person. You can visit the facility to access various patent search databases, including some patents outside of the United States, and the staff provides research help and a free system training class. Confirm the facility's operating hours and ask the representative any other questions you have about visiting or attending training.