The USPTO considers applications for three types of patents: A utility patent covers new and useful processes, manufactured articles or machines; it may include improvements to these inventions. A plant patent covers new and distinct plant varieties. A design patent covers only the outward appearance of an invention and not its functional or structural elements. All patent applications must include full and detailed descriptions, including drawings, where relevant, of the invention or process seeking protection.
Expiry of Time
For applications filed on or after June 8, 1995, utility and plant patents last for 20 years; they automatically expire at the end of that period. Design patents last for 14 years from the date of issue. Once your patent expires, your invention or process is no longer protected. This means that any organization or individual can sell or use it freely without your permission.
Lapse Due to Non-payment of Maintenance Fees
The inventor or patent owner must pay maintenance fees to the USPTO to avoid having a utility or plant patent lapse. Fees are due after three years, seven years and 11 years from the date when the patent was first granted. The USPTO gives patent owners a grace period of six months following the date when the fees are due to make late payment, provided they pay a surcharge. The USPTO publishes its fees in October of each year. You do not have to pay maintenance fees for design patents.
Reviving a Patent
If your patent has expired due to non-payment of maintenance fees, you can apply to revive it, provided you apply within two years from the end of the six-month grace period. Your petition for revival must be on the grounds that the non-payment was either unintentional or unavoidable. You must explain in the petition that you took reasonable steps to ensure that the payment was made on time and that you filed the petition promptly once you realized that it wasn't paid.