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Patent Subject Searching

A tutorial for patent subject searching at the US Patent Office website.

Frequently Asked Questions (FAQ)

Class/subclass search - the best way

  1. Go to www.uspto.gov on the web. Choose "Patents". Choose "Patent Classification". Choose "Classification Index, Patents".
  2. Click on the letter of the alphabet that corresponds to your subject. For example, let's say you have invented a new robotic arm. Click on "R". Then either scroll down to "Robot" or use your web browser's search feature to search for the word "Robot". Under Robot there is a listing for "Arm Movement" which has a link to a classification number next to it. The number is 901/14, followed by a + sign (+ means that other classes exist related to Robotic Arm Movement immediately following 901/14). Click the 14.
  3. The next screen lands you in the numeric Manual of Classification listing at the entries under 901/14. We see that 901/15 is a jointed arm.
  4. Click the "15" for the patent office's definition of what a jointed arm is. Click the red "P".
  5. Now you should be at the list of all the patents issued under that numeric subclassification.
  6. You also must search the patent applications in order to do a thorough search. Using the class and subclasses you found in steps 2-5, go to http://www.uspto.gov/patft/index.html and choose "Quick Search" under "AppFT: Applications." Type your class and subclass in the search box (i.e. 901/15) and choose "Current US Classification" in the drop-down field menu.

Keyword Search - An alternate way to find patents

Suppose you tried the search above and didn't find any classification number for your idea. You can search the titles and abstracts of patents issued from 1976 onward. Your goal in searching by keyword should be to find some relevant patents, see what classification numbers they were filed under, and then start over with a class/subclass search as described above.

  1. Go to www.uspto.gov on the web. Choose "Patents."
  2. Choose "Search Patents". Choose "USPTO Full-Text and Image Database (PatFT)". Choose "Quick Search" under "Searching Full-Text Patents".
  3. At this search screen you can enter words or combinations of words which you think might appear in descriptions of your invention. Suppose, for example, you have invented a bicycle helmet with a built in fan. You could type "bicycle helmet" in the Term 1 box and "fan" in the Term 2 box. (Single words can be truncated with a $ character, so you could truncate fan$ to retrieve fan, fans, etc., but phrases like "bicycle helmet" cannot be truncated.) Set the "Select Years" box to "1790 to present[entire database]". Click "Search". This search retrieves 8 patents, one of which looks relevant. Within the patent (number 5,687,426), you may note that the classification was 2/411. This classification may be searched by going back to the Patent Office Home page at www.uspto.gov, then choosing "Patents", then "Patent Classification", then "Manual of Classification Schedules, patent". You might also have a look at the patents which are cited in 5,687,426, to see if any of them are relevant, and if so, note their classification numbers.
  4. You also must search the patent applications in order to do a thorough search. Using the class and subclasses you found in steps 1-3, return to http://www.uspto.gov/patft/index.html and choose "Quick Search" under "Published Applications." Type your class and subclass in the search box (i.e. 2/411) and choose "Current US Classification" in the drop-down field menu.