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Patents and Trademarks

Preliminary Patent Search Guide

To perform a preliminary patent search:

  1. Brainstorm terms to describe the invention.
  2. Use these terms to find initial USPC class/subclass in the Index to the U.S. Patent Classification (USPC).  
  3. Verify the relevancy of USPC class/subclasses using the U.S. Patent Classification Numbers & Titles List. Then, confirm scope of subclass using U.S. Patent Classification Definitions (hyperlinked from the U.S. Patent Classification Schedules). 
  4. [CPC Alternative]Use your terms to find initial relevant Cooperative Patent Classification using the USPTO website's Site Search box ( In the Site search box found in the top right hand corner of the home page enter "CPC Scheme [plus keywords(s) describing invention]"; for example, if you were trying to find CPC Classifications for patents related to umbrellas, you would enter "CPC Scheme umbrella". Scan the resulting classification's Class Scheme (class schedules) to determine the most relevant classification to your invention. If you get zero results in your Site Search, consider substituting the word(s) you are using to describe your invention with synonyms, such as the alternative terms you came up with in Step 1.  (If you continue to be disappointed with the CPC Classification search results, look for your search word in the International Patent Classification Catchword Index; CPC is based on International Patent Classification).
  5. Retrieve and review complete U.S. patent documents and published applications by USPC classification [and/or CPC Classification] in the PatFT (Patents Full-Text) and AppFT (Applications Full-Text) databases.
  6. Using the USPC classification(s) you previously identified, find relevant Cooperative Patent Classifications (CPCs) using Statistical Mapping from USPC to CPC; retrieve and review U.S. patent documents and published applications with these CPC classifications in the PatFT and AppFT databases.
  7. Conduct a Classification Search of CPC Class Schemes on the EPO’s Espacenet website to expand your CPC searching to additional relevant CPC classifications.  You can then use these additional CPC classifications to find additional relevant patent documents and published applications on the PatFT and AppFT databases on the USPTO website.

You can find additional information at 

Finding Technical Search Terms

Technical dictionaries and reference books can help you identify useful search terms related to your concept.

Searching Patents on the USPTO Public Web Site

U.S. patents (including full-text) can be searched from any internet-connected computer with limited Boolean operators on the USPTO web site:

To search by keywords to identify CPC classifications, use this Index to the CPC (search box on lower right sde of page), or Espacenet's Classification Search.

What you should know about Google Patents

"Google is a very significant player in the world of patent searching now.  They have accomplished something that no other patent office, or to my knowledge, any of the for-fee patent databases have done, which is to have made nearly all US and European patent documents available in searchable full-text. However, they have used optical character recognition to create digital full text from the TIFF images of the old paper documents, and this has not been perfect. The oldest patents were hand-written, usually in very fancy script that can not be perfectly transcribed by OCR algorithms. It has also recently been pointed out that thousands of patents are actually missing from the Google database. Also of importance is that classification searching on Google is completely unreliable."

-from an interview with Martin Wallace, Science & Engineering Librarian at the University of Maine, Orono, who serves as Maine’s only representative to the Patent and Trademark Resource Center (PTRC).

Google's Advanced Patent Search is a user-friendly place for casual exploration of patents. Improve your results by using it as a source of keywords and classification numbers for further searching with the USPTO databases.

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