A patent is a legal right to exclude others from the commercial exploitation of a novel, useful, and non-obvious invention.
Patents are granted by a government agency (in the United States, the US Patent and Trademark Office) for a limited term, in exchange for the public disclosure of the invention and its workings.
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 Public Patent Search have different advantages. Use both to ensure a comprehensive search strategy.
Google Patents | USPTO |
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All patent documents, except recent months | All patent documents, updated weekly |
USPTO and 100+ other jurisdictions | USPTO patents only |
Also contains non-patent literature (technical documents and books indexed in Google Scholar and Google Books) |
Only patents |
Simple interface designed for quick review of matches | Complex interface designed for precise searching |
Searches full documents 1790-present | Searches full documents 1970-present; searches patent numbers, dates, and classifications 1790-present; searches inventor names 1920-present |
Searches images with Optical Character Recognition |
Searches text 1970-present (more reliable); searches with OCR 1790-1970 |
Default order of results is relevancy |
Default order of results is reverse-chronological |
Supports citation analysis across worldwide patents and other prior art |
Supports citation analysis across US patents |
1. Search by classification.
The most effective way to search for patents for a specific area of technology is to identify the most relevant classes and subclasses in the Cooperative Patent Classification (CPC) scheme.
Recommended: search by keyword in a patents database, find a relevant patent, then review its CPC classes and subclasses. In Google Patents, look for "Classifications".
Other strategies: (a) ask an AI tool for examples of CPC classes used for x technology; (b) browse the full CPC Scheme listing all CPC classes; (c) run keyword searches for matching classes with the USPTO's Classification Text Search.
2. Search by field.
Patent fields include inventor, assignee (owner), and patent number. Field searching is most useful for finding a known patent or patents held by a known person or corporation.
3. Search by keyword.
An increasing proportion of patents are available online with full text, making keyword searching more effective. But keyword searches may retrieve an overwhelming number of results or may fail to reflect the technical language used in patent writing. Use keyword searching (1) as a step to identify classes and subclasses; and (2) to supplement classification searching.