Technological Trajectory Analysis of Patent Citation Networks: Examining the Technological Evolution of Computer Graphic Processing Systems

Abstract

This paper quantitatively analyzes how technology has evolved within the technological field of computer graphic processing systems. A path-dependent technological development path is called a ‘technological trajectory’ in the field of Innovation Economics. The technological trajectory of a technological field can be mapped as the main paths of patent citation networks. Using a method called main path analysis, main paths are calculated from the whole patent citation network data of the technological field. This paper examines how technology has evolved within the technological field of computer graphic processing systems using main path analysis. In addition, the change of the main paths over time is analyzed. According to this analysis, the appearances and disappearances of nodes on the main paths show certain patterns. First, all nodes observed on the main paths three times consecutively at 5-year intervals did not drop out from the main paths in the long term. Second, most of the appearances and disappearances of the nodes occur toward the end of the main paths. These observations are consistent with the technological lock-in process. The result of this research suggests that it takes less than 10 years to determine which technologies are locked-in. In addition, various patterns of the appearances and disappearances of companies owning patents on the main paths are also observed. Three companies are taken as examples to illustrate these patterns. These observations provide insight into how knowledge networks are formed.