Inventing-Around Edison's Incandescent Lamp Patent: Evidence of Patents’ Role in Stimulating Downstream Development and Competition
51 Pages Posted: 11 Jul 2014
Date Written: October 9, 2013
The social welfare benefit of the design-around aspect of the patent system has not been adequately assessed. This paper provides the first empirical detailed case study of design-around patents. We study the influence of the patent claims of Edison’s incandescent lamp patent U.S. 223,898 on downstream invention and development. In particular, we shows how the improved certainty provided by court decisions as to the boundaries of this patent’s claims altered subsequent inventor activity. First, we show that court decisions upholding Edison’s patent generated a surge of patent filings in the incandescent lamp classes at the U.S. Patent Office. Second, by inspection of the specifications of these later patents we are able to identify and categorize invention-around efforts by their evasion of specific elements of the claims of Edison’s ‘898 patent. We make two further investigations of these invention-around patents; first, by analysis of forward citation to these patents we show that regardless of these inventions’ commercial viability in the incandescent lamp market, some laid the groundwork for the later successful substitutes for Edison’s lamp and some became important prior art for new technological fields. Finally, we show by means of the relevant commercial data that the recent view that Edison’s patent gave the patent holder General Electric (GE) a dominant position in the incandescent lamp market is incorrect: we reveal GE’s market position to have been stable, even weakening through the period of the ‘898 patent enforcement.
Keywords: incandescent lamp, Edison, design-around, invention-around, downstream development, patent
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