Japanese Patent Documents Are a Prime Source for Prior Art Search

By Lin Wang
Prior art is the information that has been made available to the public in any form before a given date that might be relevant to a patent's claims of originality. If an invention has been disclosed in public domains, a patent on that invention is not valid. Therefore, patent search and non-patent literature search are often performed before filling a patent or before / during a patent litigation.

Japanese patents are prime source of prior art search. Japan is ranked No.1 country in the number of patent applications filed annually. In 2009, there are about 400,00 patent applications filed in Japan (JPO), which is about 20% of the total patent applications filed worldwide, the highest number in all countries.

As a comparison, there are about 370,000 and 178,600 patent applications filed annually in the USPTO and EPO respectively.

Japanese patents are the richest sources of prior art in the world, with more than 50 millions searchable patent and trademark documents, over 200 millions pages, stored at the JPO database. As a comparison, USPTO has stored about 10 millions of searchable documents including patents and trademarks.

Applications filed in Japan are published (laid open) 18 months after the filling or priority date regardless of the examination. The invention described in the published application become a prior art as of this disclosure.

While they can be difficult to search, Japanese sources are extremely important considering they are the richest prior art sources in the world and Japan is one of the top 3 economies with the most advanced technologies in many fields.