The diversity of agents and patent thicket evolution in electric vehicles

The evolution of the inventive process in electric vehicles has been increasingly complex and thus the probability of patent thicket too. However, patent agents (individual inventors, companies, non-practicing entities and alliances) are not homogeneous in interests and abilities. Based on information from the Patent and Trademark Office (USPTO) in the period 1976-2012, it is described: 1) the growing complexity in the inventive activity of electric vehicles; 2) the characteristics and evolution in the inventive activity of agents; 3) the relation with patent thickets. It is shown that the evolution of patent thickets (from low to high complexity) is associated to the evolution of technological knowledge as well as the evolution of the agents.