A comparative analysis of Inventor Patent Classification Coupling between the first-inventor and all-inventor: Taking 3D printing as an example

This article takes 43,753 patents collected in the Derwent database from 2011 to 2020 as data samples and studies the intellectual structure and evolution of the three-dimensional (3D) printing field in two time periods of 2011–2015 and 2016–2020. We compare the performance of the first-inventor patent classification codes coupling analysis and all-inventor patent classification codes coupling analysis in detecting the intellectual structure of the technical domain. We obtain the following findings: (1) Both methods, the first-inventor patent classification codes coupling analysis and the all-inventor patent classification codes coupling analysis, can show the intellectual structure of the 3D printing field. However, the first-inventor patent classification codes coupling analysis outperforms all-inventor patent classification codes coupling analysis in the detection of basic research; while all-inventor patent classification codes coupling analysis is more sensitive in emerging and interdisciplinary topics. (2) Three-dimensional printing has been evolving in the last decade. While the field has retained the research themes of the previous phase in the last 5 years, several new research themes have also emerged. The most prominent feature of this field is the development and integration of the previous phase’s topics. (3) The research direction of the top 20 inventors in the average coupling frequency ranking is consistent. A small number of researchers continue to work on their previous research, while most inventors move to popular technical topics or combine multiple topics at the same time.