Identifying The Core Patents Based On The Citation Network

The 18 th National Congress of the Communist Party of China(CPC)pointed out that our country would carry out innovation-driven development strategy,which encouraged innovation to promote economic development.And it needs the support of patent information resources which are a set of economic,legal and technical information.Patent documents are the carrier of scientific technology information,which contain ninety to ninety-five percent of the latest technologies in the world.If the country and enterprise want to access to the latest developments in a particular technology area,the reference to patent documents is indispensable.However,there are much more patent documents applied every year.Therefore,how to find the core technology in a field from the massive files is an urgently needed solved work to both the country and company.Undoubtedly,finding the key technology helps the organization to follow and learn the latest technique and this will promote their sense and ability in innovation.In the first,this paper introduced the traditional method in identifying core patents,which include patents' external features,integrated citation network,Bradford law and using related software.However,the four methods have some limitations in different level.For example,patents' external features have strong subjective,integrated citation network is complicated,Bradford law and using related software are too targeted.Therefore,in this paper,we consider direct citation network instead of previous methods and introduce the PageRank algorithm referring to the network citation relationship.But the existing research about this is simply the application of PageRank without taking into account the features in patents.Based on the above information,in this paper,combing the external attribute-the cited times and the internal attribute-patent age,we proposed the new PageRank named PatentRank(referred to as PTR)involving two factors "authority" and "time".In order to testify the rational and superiority of the method,in this paper,we select the OLED field as empirical example.By comparing the cited times,initial PageRank and PTR,we find the three methods are consistent in principle.Besides,the improved PageRank algorithm can not only identify the key patents but also the basic patents compared with the cited time.What's more,the improved PageRank have a higher degree of distinction compared with the initial PageRank.However,we must also notice that the "time" factor has less influence than "authority" factor and this indeed need further thinking.