Celebrate Classical Music Month by diving into the ethereal world of the Theremin and the fascinating world of citations...

Leon Theremin was a Russian radio engineer with French and German roots who invented the famous Theremin. We're celebrating Classical Music Month by shining a light on his extraordinary invention and on the fascinating world of patent citations.  

In the 1920s, Theremin was working in a lab when he discovered that combining two antenna circuits and connecting these to an acoustic output allows you to control the pitch of a melody with one hand and volume with the other (see below). This was the birth of the first analogue synthesiser, patented in several countries, for example in the United States in 1928. 

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The Theremin's ethereal sound had an enormous impact, inspiring classical compositions for Theremin soloists and the invention later of the modern commercial synthesiser which has revolutionised the music world and allows classical music composers to write and listen to their compositions without the need for an orchestra. Outside of the music industry, Theremin's invention has also inspired patents in the areas of gaming devices and pulse techniques.

One way to assess the real impact the Theremin has had on subsequent inventions is by using forward citations. Forward citations are later published documents that have cited the patent document you are looking at (in this case, Theremin's patent of 1928). They reveal how an invention has impacted later technologies - the more forward citations, the bigger the impact. In Espacenet, for example, you can see that 39 patent families directly cite Theremin's patent. 

Using PATSTAT, you can create a forward citation tree to view the real long-term impact of an invention - not only the forward citations of an invention, but also the forward citations of the forward citations. In this way, you can clearly see how a patent has influenced filings in other areas, even those that were yet to exist (think video games, 3D sensing and data processing). The Theremin citation tree has a tremendous number of forward citations, with numbers growing even after fourteen iterations. This proves the Theremin has been a true game-changer and is a powerful example of a patent that has inspired many other technologies. 

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Perform the following steps to re-create this graph.

Enter this query in PATSTAT:

SELECT DISTINCT a.pat_publn_id FROM tls212_citation a
JOIN tls211_pat_publn orig ON orig.pat_publn_id=a.cited_pat_publn_id
WHERE orig.publn_auth='US' AND orig.publn_nr='1661058' 

Now paste the above query inside the brackets below to retrieve the number of forward citations for the next iteration: 

SELECT DISTINCT b.pat_publn_id FROM tls212_citation b
WHERE b.cited_pat_publn_id IN ( - paste the query for the previous iteration here - )

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Add as many outer queries as you like, each time giving the outer query table a new alias (note that more iterations search more documents and so take longer to run). Finally, import the data to Microsoft Excel and create the graph.

That's all folks! Ring the curtain up and let the music play ...

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