You have an idea for an invention - or have gone so far as to create a prototype. Before marketing your invention, you will need to determine if your invention has already been patented. You will want to conduct a thorough patent search. This will usually involve searching a number of different patent sites, so it is useful to keep a log of all your search activity, thus avoiding duplicate efforts.
You can begin your search the following way:
1. Brainstorm Keywords to describe your invention - think of synonyms.
2. Use your Keywords to search for a similar match of your invention in Google Patents. The Advanced Search in Google Patents lets you enter phrases, exclude a word, etc.
3. Write down the class and subclass of the similar invention.
4. Use the class and subclass to search patents and patent applications at the USPTO website classification search. Note: The default search is CPC (Cooperative Patent Classification) which is a joint effort between the United States Patent and Trademark Office (USPTO) and the European Patent Office (EPO). This classification system harmonizes the former European Classification (ECLA) and United States Patent Classification (USPC) systems.
5. Trace related patents through references.
Although Google Patents is easy to use it is not as current as the USPTO website. If you need to look through a large number of patents it mat be worthwhile to make an appointment to use the PubWEST database at the Patent & Trademark Resource Center. This database is not accessible except through the PTRC.
Also: Patent Process Overview
While it is possible to search patents using just keywords, the best way to conduct a comprehensive patent search is by classification. Classification helps bring together similar devices and concepts, even when different terms have been used to describe them.