When to file a patent?

In almost every country, patent rights are lost when the invention is sold or publicly disclosed unless a patent application has already been filed. A notable exception is the United States, where the inventor can publicly disclose the invention and then file a corresponding patent application within one year, without losing patent rights. However, in this scenario you would still lose your patent rights essentially everywhere else. Therefore, the best time to file a patent application is before any publication disclosure of the invention. Filing an application in just one country, or filing an international umbrella application under the Patent Cooperation Treaty, is sufficient to preserve your rights in most other countries for at least a year.

The best rule to follow is to always file a patent application before any public disclosure or use of the invention. To gain protection in different countries, you need to secure patent protection in those countries. PCT is a great means to achieve a patent in blocs of countries, particularly Europe, but you still need patents to protect your inventions. So, for example, if you file in the US first, you have one year from the US filing to file a PCT application - then you have, usually, 30 months to file particular applications in particular countries, although some countries vary as to the filing times, so you need to check for the particular countries that you are interested in.