What was the Role of Edison’s Incandescent Lamp Patent on Downstream Developments
In this paper we examine over four hundred patents in the USPTO incandescent lamp patent-relevant categories to assess how Edison's basic 223, 898 patent influenced inventive activity in the field. We categorise patents as 'inventions around' claim 2 of Edison's patent when their claims clearly provide an alternative technical means to those stipulated in Edison's claim 2. Prior work in the economics literature has not addressed the the relation of downstream invention to prior art patent claims. We also show that when the number of patents is plotted against time, there is a surge of patenting subsequent to the courts upholding the validity of Edison's claim 2. We argue that Edison's patent had the effect of stimulating downstream invention. This analysis is contrary to several recent papers that have been published in the student-reviewed US law literature that assume Edison's patent was used by General Electric to enforce an economic monopoly on the incandescent lamp field; this interpretation is in error.