关键词: 专利许可, 专利宽度, 孤立创新, 累积创新, Patent-licensing, Patent Breath, Isolated Innovation, Cumulative Innovation

Abstract: Through a model of quality ladder, this paper analyses the effect of duopoly’s research behavior and patent-licensing behavior to subgame perfect Nash equilibrium in the cases of cumulative innovation and isolated innovation, then studies the relevant optimal patent breath on that basis. The results show that the optimal patent breath changes to reflect changes in research efficiency of market, regardless of the type of innovation. Compared with the isolated innovation, the optimal patent breath may narrower or wider, it depend on the change of research efficiency, so patent system of isolated innovation may not apply to cumulative innovation.