Abstract
The recently developed Cooperative Patent Classifications of the U.S. Patent and Trade Office (USPTO) and the European Patent Office (EPO) provide new options for an informed delineation of samples in both USPTO data and the Worldwide Patent Statistical Database (PatStat) of EPO. Among the “technologies for the mitigation of climate change” (class Y02), we zoom in on nine material technologies for photovoltaic cells; and focus on one of them (CuInSe2) as a lead case. Two recently developed techniques for making patent maps with interactive overlays—geographical ones using Google Maps and maps based on citation relations among International Patent Classifications (IPC)—are elaborated into dynamic versions that allow for online animations and comparisons by using split screens. Various forms of animation are discussed. The longitudinal development of Rao-Stirling diversity in the IPC-based maps provided us with a heuristics for studying technological diversity in terms of generations of the technology. The longitudinal patterns are clear in USPTO data more than in PatStat data because PatStat aggregates patent information from countries in different stages of technological development, whereas one can expect USPTO patents to be competitive at the technological edge.
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Notes
For using USPTO patents, see at http://www.leydesdorff.net/software/patentmaps/dynamic; and for PatStat data analogously at http://www.leydesdorff.net/software/patstat.
See for more information about CPC at http://www.cooperativepatentclassification.org/index.html.
At the date of this research (August–October 2013), this backtracking had been completed for USPTO data, but not for the then current version of PatStat (April 2013), for two of the nine classes here under study (see Table 1 below). The USPTO envisages replacing the US Patent Classification System (USPC) with CPC during a period of transition to 2015; at EPO, however, the European classification ECLA has already been replaced with CPC.
The Y02-class follows up on the “Pilot Program for Green Technologies Including Greenhouse Gas Reduction” that USPTO launched in 2009 (USPTO 2009).
The Y02 class can be displayed and is searchable via http://worldwide.espacenet.com/classification?locale=en_EP#!/CPC=y02 (Veefkind et al. 2012, at p. 111, n12.).
The total number of patents tagged with “Y02” in USPTO was 152,983 on October 25, 2013. The total number of patents tagged “Y02E 10/54$” was 5,021.
Table 1 provides a number of 422 for the retrieval on 20 September 2013, but we use the 419 patents first downloaded from USPTO on 20 August 2013.
This colour scheme was first used by Bornmann and Leydesdorff (2011) for z-testing proportions of publications in cities.
Differences between cities can also be z-tested for their significance as explained in Bornmann et al. (2012). An Excel sheet available at http://www.leydesdorff.net/scimago11/index.htm can be used as guidance to this application.
The Bing Geocoder is also available from the Sci2 Tool at https://sci2.cns.iu.edu. This workflow is faster, but requires reformatting of the data (Sci2 Team 2009). One can register for a free API key of Bing Maps at http://msdn.microsoft.com/en-us/library/ff428642.aspx.
USPTO is available as html for patents granted since 1976; but the filing dates can be from earlier years. Our data begin in 1974 and the last period of five years is 2008–2012.
The files are consecutively numbered as z1974.txt, z1975.txt, z1976.txt, etc. in the case of USPTO data—the “z” indicates that this data is z-tested—and pat1974.txt, pat1975.txt, pat1976.txt, etc., for PatStat data.
Pajek is a program for the analysis and visualization of large networks that is available for free academic usage at http://pajek.imfm.si/doku.php?id=download.
The program itself and the source code can be downloaded at https://github.com/Data2Semantics/PatViz/releases.
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Acknowledgments
We are grateful to comments on a previous version of this manuscript by Jan Youtie (Georgia Tech) and Wilfried van Sark (Utrecht University). We also thank two anonymous referees for their constructive comments.
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Appendix
Appendix
The PatViz tool enables users to animate output from the (geo-coded) patent maps produced from USPTO data (at http://www.leydesdorff.net/software/patentmaps/dynamic) or from PatStat data (at http://www.leydesdorff.net/software/patstat) both locally and online. Interactive versions are provided at http://www.leydesdorff.net/patviz or http://data2semantics.github.io/PatViz.
Instead of generating and visualizing the maps one by one for each year consecutively (at http://www.gpsvisualizer.com/map_input?form=data), PatViz reads an entire time series of files first. Using JavaScript, the program automatically generates the animation using the same parameters as specified in this study. Currently, one can be upload files with the names pat*.txt (e.g., pat1980.txt, pat1981.txt, etc.) as generated by ps_geoyr.exe for PatStat data; and the files z*.txt generated by usptoyr.exe for USPTO data. Instructions for preparing these files can be found at http://www.leydesdorff.net/software/patstat and http://www.leydesdorff.net/software/patentmaps/dynamic, respectively (Fig. 13).
Users can load their own data files by clicking “Select files to display…”, the two demo buttons provide access to data for CuInSe2 as material technology for PV cells retrieved on the basis of Y02E10/541 as the Cooperative Patent Classification for the download in USPTO and PatStat, respectively. Figures 2, 5 above provide snapshots of these two configurations in 2000–2004. For an example and further instructions, see http://www.leydesdorff.net/photovoltaic/patviz.
Users can scroll through the years by clicking the “<” and “>” buttons in the menu bar. Clicking “Play” will start an animation that will automatically cycle through all years available in the dataset. Clicking “Stop” halts the animation. The “Legend” button gives information about the colors used in the visualization.
At the top right of the screen, the “Save” button enables users to save the results for demonstration purposes in a single html-file (containing the specific data set) that can be run locally using a browser, or hosted online. After clicking “Save”, PatViz prompts for a filename and for a Google Maps API key (that is freely available from Google at http://console.developers.google.com) so that all interfaces are available; an Internet connection remains required for this application since it depends on externally hosted JavaScript libraries.
The latest release of PatViz can be downloaded from https://github.com/Data2Semantics/PatViz/releases for installation at one’s own machine. After unzipping the files, one installs the program and can run it by opening the index.html file in a Web browser. The program requires that the computer be connected to the Internet in order to download the Google Maps and other external libraries. The program can also be uploaded and used online, after replacing the API key of Google Maps in index.html with the one for one’s own website.
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Leydesdorff, L., Alkemade, F., Heimeriks, G. et al. Patents as instruments for exploring innovation dynamics: geographic and technological perspectives on “photovoltaic cells”. Scientometrics 102, 629–651 (2015). https://doi.org/10.1007/s11192-014-1447-8
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DOI: https://doi.org/10.1007/s11192-014-1447-8