A patent assignment is a conveyance of the rights in a patent or patent application. It recognizes a buyer and seller of the patent rights and identifies what is provided in exchange for the rights. The patent assignment often states whether future patent rights are affected by the assignment, as well, such as if the inventor develops an improvement on the original invention.
A patent assignment is necessary where an employee conceives of an invention on behalf of the employer company, and the company is the owner of that invention. The assignment memorializes and effects the transfer of ownership from the employee to employer. An assignment is also necessary where an independent inventor sells his rights in his patent application to someone.
An assignment is different from a license. While both a license and an assignment transfer rights from one party to another, an assignment is a transfer of the all of the rights in the property, while a license is a transfer of only some of those rights – a license is a transfer with limitations. For instance, a license may transfer ownership for only a few years, after which ownership reverts to the original owner. Or, a license may transfer the right to prevent others from selling and using the product, but not the right to exclude others from making the product. In contrast, an assignment transfers ownership completely and finally.