Science Research Management ›› 2021, Vol. 42 ›› Issue (4): 123-130.

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Identification of patent thickets based on citation analysis——A case study by taking the high-speed train braking technology as an example

Feng Ling1,2, Yuan Xiaodong3   

  1. 1. School of Economics, Management and Law, Hubei Normal University, Huangshi 435002, Hubei, China;  2.Resource-Exhausted City Transformation and Development Research Center,Hubei Normal University, Huangshi 435002, Hubei, China;  3. School of Management, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China
  • Received:2020-05-01 Revised:2020-09-22 Online:2021-04-20 Published:2021-04-19

Abstract: Patent thicket is one of the forms of patent traps, which have attracted widespread attention because of its hindrance to technological innovation. The more serious of patent rights fragment and overlapping, the more patent thickets. Patent jungle has therefore become one of the technological traps that companies must pay attention to in innovation activities. Given concerns about the consequences of the patent thicket, identifying and analyzing the patent thicket is necessary as it can help companies predict and avoid related patent risks, and to a certain extent reduce obstacles in technological innovation.With the implementation of China′s high-speed train "going abroad" strategy, intellectual property issues, especially patent issues in the field of high-speed train make the exporting of China′s high-speed train facing potential technical risks. In this context, this paper intends to take the high-speed train braking technology as an example, study the patent thicket problem in the field of high-speed train technology. The empirical analysis of this paper involved two steps, including the identification of the patent thickets and the evolution process analysis of the patent thickets. The patent citation triples method is used to measure and identify the patent thicket in the field of high-speed train braking technology. With this method, only when any two of the three innovation subjects have mutual citation relationship, and then form a closed ring of citation relationship among these three innovation subjects, a complete triple can be formed. Then, based on the systematic cluster analysis of the effective patent time series, the evolution of patent thicket in the field of high-speed train braking technology is analyzed. Thicket patents that have a certain influence on other innovation subject′s innovative activities are valid patents in the protection period. Therefore, the change of the number of valid patents is taken as an analysis index to measure the evolution process of patent thickets in this paper. The empirical analysis results show that there is a patent thicket problem in the field of high-speed train technology. After experiencing the germination period, growth period, and maturity period of the patent thicket, the patent thicket is currently in the decline stage. With the increase of invalid patents in the existed patent thicket, the stock of valid patents is continuously decreasing. For the latecomer Chinese high-speed train enterprises, the resistance and obstacles to innovation are relatively reduced. In view of the patent thicket problems in the high-speed train industry and its stage, this paper proposes two suggestions for Chinese high-speed train related companies. Firstly, they should deepen the cooperation of the high-speed train technology alliance, promote the sharing of knowledge and patents, and jointly avoid the obstacles to technological innovation caused by the patent thicket. Secondly, technical standards for high-speed trains should be established while realizing the standardization of patented technologies of Chinese high-speed train companies.

Key words:  patent thicket, patent citation triples, active patent, systematic cluster analysis, high-speed train