United States Patent and Trademark Office

The USPTO web site has searchable text and images of every US patent issued since 1976, full page images of patents back to 1790, and published patent applications since 2001. you already know that.

International

Many US patents were filed earlier in other countries, and so it may be important to obtain the original foreign patent. Obtaining copies of foreign patents is more difficult than getting US patents - in general, there are few free searchable databases. 180 countries are members of WIPO - the World Intellectual Property Organization. These countries have signed the PCT (Patent Cooperation Treaty) which affords patent recognition in all member countries if a patent is filed according to the PCT rules. To quote from the PCT site:

The Patent Cooperation Treaty simplifies and reduces the cost of obtaining international patent protection and facilitates public access to a wealth of technical information relating to inventions. By filing one international patent application under the PCT you can simultaneously seek protection for an invention in over one hundred countries, including developing countries, throughout the world.

Unfortunately, the PCT system is all about filing, and not about access.

A fee-based service that covers both US and International patents is Thomson-Delphion. Their site allows very limited free access, but to do searches requires a paid subscription. Another fee-based database with international patents is Thomson-Dialog.

Many countries maintain their own on-line patent databases, often for a fee. The European Patent Organisation has the best free access to European patents that we've found. A few that we have used:

• ESP@CENET - The European Patent Organisation free internet search gateways
• ESP@CENET - UK gateway to esp@cenet.
• INPI - France (fee based)