Most patent information is openly available online. Patent databases and search engines vary by breadth of contents, national or international coverage, basic interfaces and advanced search tools.
Google Patents and the USPTO's databases have different advantages. Use both to ensure a comprehensive search strategy.
| USPTO Patent Public Search | Google Patents |
|---|---|
| All patent documents, updated weekly | All patent documents, except recent months |
| USPTO patents only | USPTO, EPO and WIPO patents |
| Complex interface for precise searching | Easy-to-use Google-style interface |
| Document searching 1976-present, index searching 1790-1975 | Document searching for all patents |
| Searches text (more reliable) | Searches images with Optical Character Recognition |
1. Search by classification.
The most effective way to search for patents for a specific area of technology is by classification. All U.S. patents created before 2015 have a classification based on the U.S. Patent Classification (USPC) system; all U.S. patents created from 2015 onwards have a classification based on the Cooperative Patent Classification (CPC) system.
2. Search by field.
Patent fields include inventor, assignee (owner) and patent number. Field searching is most useful for finding a known patent.
3. Search by keyword.
An increasing proportion of patents are available online with full text, making keyword more effective. But keyword searches may retrieve an overwhelming number of results or may fail to reflect the technical language used in patent writing.