Patent Abstracts of Japan

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Patent Abstracts of Japan is an electronic collection of hand translated English-language abstracts produced for all published Japanese patent applications by the JAPIO (Japan Patent Information Organization) corporation. This important collection is loaded on many free and commercial patent search databases, and it makes English keyword searching within the Japanese art possible.

Another provider of searchable Japanese data is the Patolis Corporation, which applies English-language keywords and deep indexing to its collections.

The Importance of Japan

Japanese patents are a major source of technical information. Because it has been a global leader in innovation for decades, Japan’s patent publications hold a wealth of industry knowledge that must be consulted in prior art searches. The Japanese patent office, the US patent office, and the European patent office are the major patent offices in the industrialized world. These three powerhouses are known as the "trilateral offices."

Japanese patents are also an important prior art source because they are published in huge quantities. As explained by Stephen Adams in his seminal book on patent information sources, both legal and cultural factors in Japan have driven the number of patent applications sky-high. The legal factors include a past longtime restriction that Japanese applications could only include one claim, while the cultural factors include a "publish-or-perish" attitude for many companies, where patent publications are seen as an indicator of research efforts.[1]

The Patent Abstracts of Japan File

Because of the importance of Japanese patents to prior art searching, it became essential that non-Japanese speakers be able to somehow search this collection. The Patent Abstracts of Japan (PAJ) file is produced by the JAPIO Corporation and provided to database producers as a collection of CD-ROMS. A PAJ record usually contains bibliographic information, an English abstract, and a representative image from the application.

Coverage in the PAJ file begins in 1976. From 1976 to 1989, abstracts were only produced for the documents falling under certain IPC codes, and only for cases which were first filed in Japan (before 1989, foreign filings were assumed to be published in at least one western language and therefore were considered more accessible). After 1989, both of these limitations were removed: all documents were abstracted regardless of IPC code, and the collection was expanded to documents which were first filed outside of Japan. Although, according to Adams, there are no plans to fill in the backfile gaps for those IPC classes which were not indexed before 1989, there is a separate series of CD-ROMS that can be licensed to fill in the foreign-filed documents.

The PAJ collection covers only published Japanese applications, or JP-A documents; there is absolutely no coverage of granted Japanese patents within the file. However, several commercial databases have used family relationships and DOCDB bibliographic data to associate JP-B Japanese patent numbers with the English abstract produced for the corresponding JP-A application.

As of mid-2008, the time delay from when a Japanese application is published to when the English abstract is available from the PAJ service is four months.[2] When searching for Japanese documents, users should be aware that in systems which do not augment their Japanese abstract collection with new DOCDB bibliographic data, the search results will lag four months behind the current Japanese publications. However, users should also be aware that even in systems which do include up-to-date bibliographic data for their Japanese collection, no English abstract information will be present for those records, and keyword searching will be of little use. A good strategy for identifying very recently published Japanese documents may be to conduct a search in the other major collections, and then to investigate relevant hits to determine whether any recently-added Japanese applications appear in the family data.

There are further special considerations to keep in mind when searching the Japanese data. Difficulty in translating and transliterating Japanese names into English characters and vice/versa makes indexing the inventors listed on Japanese patents very difficult, for both Japanese language and English language databases. According to Adams, the Japanese Patent Office (JPO) has removed this field from its search files altogether, and the Derwent World Patents Index did not record Japanese inventor names at all until 2005.[3]

Some Facts about the Japanese Patent System

Filing a patent application in Japan does not automatically equal a request for that application to be examined by the Japanese Patent Office or issued as a granted patent. After the application is published for public inspection, the applicant has three years to request examination for the application to become a granted patent; if this time period expires without an examination request, the application is deemed to be withdrawn.

Japanese applications are published 18 months after their application date. Since January 2000, Japan has also allowed early publication by request. An applicant may request that an application be laid open to public inspection before the 18 months has expired. The applicant may choose to do so in order to obtain provisional protection or to claim compensation from an infringing third party.[4]

From a searching standpoint, it may be useful to note that in 1976, laws were enacted in Japan that allowed for the protection of medicines and chemical products. Before this time, only the processes of making these products could be protected.[3]

Understanding Japanese Document Numbering

Historically, Japanese documents have been numbered using the country’s Imperial Calendar, which is based upon the year of the Emperor’s reign. After the year 2000, Japan converted to using the calendar year as the date prefix for its document numbering system; however, pre-2000 documents may still be referred to by Emperor year.

Because the Patent Abstracts of Japan coverage begins in 1976, there should be relatively little confusion about which year is meant by the imperial year prefix on a document, as it covers only two eras: the Showa era (emperor Hirohito), from 1926-1989, will have year prefixes of 51-64; the Heisei era (emperor Akihito) began in 1989, and will have a corresponding number of 1-18 (through 2007). The transition from Showa to Heisei occurred on January 9th of 1989; however, as Adams cautions, printed publications continued to bear the "64" prefix for several months after the transition, although the electronic records now bear the correct "01" prefix.[1]


  1. 1.0 1.1 Adams, Stephen R. Information Sources in Patents. 2nd ed. Munich: K.G. Saur, 2006. Page 61.
  2. Patent Abstracts of Japan content description related to the ESPACE CD-ROM subscription product. EPO website, Accessed on October 3, 2008.
  3. 3.0 3.1 Adams, Stephen R. Information Sources in Patents. 2nd ed. Munich: K.G. Saur, 2006. Page 69.
  4. Information obtained from the European Patent Office’s East Asian FAQ on Japan. EPO website, Accessed on November 26, 2007.

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