Abstract
In performing patent retrieval, it is important to construct queries that cover relevant patents comprehensively because missing only one patent might bring enormous risk. Ironically, many critical patents are written in words such that the database retrieval cannot catch easily. Therefore, full-text retrieval has certain limitation even if the ability of database retrieval is improved. In this regard, to overcome this limitation, the practical use of patent classification system is needed. European Patent Classification (ECLA) is used as a tool for classifying not only European patents but also patents worldwide. It hasn't been long since ECLA became searchable in commercial databases so that ECLA has not been popular in Japan yet. However, ECLA can be regarded as a powerful tool not only for patent search for patents in European countries but also U.S. patent search especially. In this article, we'll explain the history of the establishment of ECLA and its framework, the relations with IPC (International Patent Classification) and future trend. Further we'll show the practical use of ECLA in patent searches.
