It takes all kinds to make a world – Some thoughts on the use of classification in patent searching Review Article

This article addresses patent classification as practiced by different patent offices and one private company. It highlights strengths and weaknesses of the individual systems. To this end it compares the representation of the concept of controlling wind motors in the classification systems of WIPO, EPO, DPMA, JPO, USPTO and Derwent’s World Patent Index. As the author is a searcher in the mechanical and electronic arts, specific statements and examples will also relate to these technologies. A comparision of search results obtained by using different classification schemes will show how additional subject matter may be found. The incompatibilities of IPC-based and non-IPC systems and how they can be overcome are exemplified. Possible reasons for differences in application of the classifications are discussed and what these may mean for the searcher. In the conclusion reasons for expending the additional effort of applying several classifications will be given and the author argues why it is a good thing there are more than just one or two classification schemes.