Patent Research

1. Different patents use different keywords in their descriptions, so a keyword search alone will miss relevant results. CPCs and IPCs categorize patents; searching using these identifiers will get you all the patents that belong in a certain classification, making your search much more efficient.
2. You can start by browsing through the list of classifications or by using a CPC/IPC you found in the record of a related patent after an initial keyword search. Both are great!
3. Most patent search databases have an advanced search feature that lets you search specifically by CPC or IPC.
4. WIPO explains the differences between CPC and IPC classifications on this FAQ page: "CPC is the Cooperative Patent Classification scheme used by the European Patent Office (EPO) and the United States Patent and Trademark Office (USPTO), which was jointly developed by the two Offices. ... It is based on the IPC, but it is much more detailed. CPC classification codes can be used to carry out searches on both the Espacenet and the USPTO Classification databases."

Patents Before 1976

Patents documentation prior to 1976 was digitized using software that does its best to map the text of each physical document onto the digital one as well. While the software typically does a pretty good job, errors aren't uncommon. If you're having trouble, try using the wildcard operators explained in the box below to allow for various spelling misattributions. Still having trouble? Contact the research desk or a librarian for help.