Patents are legal documents that protect invention. While the claims in a patent are the key legal 'meat' of the document, an incredible amount of technical information is disclosed for review and contemplation. Indeed, the motivation of disclosing patents is to challenge and generate more invention!
Powerful patent databases exist for formal patent searching and patent estate mapping. Patbase® and ® are two that come to mind.These services come with a fee. t
The United States Patent Office provides some limited but useful search capabilities to find US patents and publications. This service is provided free of charge, and is a good 'starting point' for patent review. It only covers US patents, however, and is therefore not comprehensive.
A nice feature of the US patent Office searching, an identified patent has a link in the content entitled "Referenced By", which allows one to identify any US patent that has referenced the current patent. With the references listed in the patent, and the 'referenced by' forward patents available, one gets a powerful broad overview to the invention trail. Indeed, while somewhat cumbersome, reviewing the referenced patents and the 'referenced by' patents and their references/referenced by, iteratively, one eventually can eventually identify an entire invention US patent estate.
Want a hard copy of a patent for free? Check out Pat2pdf, input the patent number and it will provide you with a downloadable pdf of the patent.