Deep dive into the search function in the field of patent (Part – 3) – Method of Searching

“Searching is a skill but, finding is an art” – Gerard van der Ligt, former head of the search department, Philips, Eindhoven

In the earlier two articles in this three article series, we looked at the situations in which patent related searches are done and the differences between the types of documents and what parts of the documents are of relevance to each type of search.

In this third and concluding article we will take a look at what tools and skills a searcher uses for searching.


For most people, Google® has become synonymous with searching. So much so that googling and googled have entered the English language. Still, many may not even be aware that Google has a specialized search tool for patents (Google Patents® ) and one for scholarly articles (Google Scholar® ). Many might even be under the impression that patent related searches are also done only on Google or an equivalent web search engine.

While there is nothing wrong with a Google search, features such as how the result set is ranked for display may not be very convenient in comparison with many dedicated databases and search tools. Further, the sheer number of documents that a Google search fetches is prohibitive for many focused searches.

However, there are dedicated patent databases with more convenient and powerful search interfaces. For example, the European patent office (EPO) offers a free search tool – the Espacenet patent search. It has two variants – Patent search and Advanced search. Using this tool we can search for patents relevant to our needs from EPO’s database which has tens of millions of patent records from all over the world.

Similarly, many national patent offices offer free search tools to the patents in their databases. Apart from these, there are commercial patent databases offering search tools and interfaces which are subscription based. If you search the web for patent tools, patent engines, and patent databases, you get a plethora of them and it is not worthwhile to list them here.

Non-patent, scientific and technical literature

As mentioned earlier, Google Scholar lets you search for scholarly articles based on keywords. Similar to it is the Microsoft Academic® . As before, if you do a web search for scientific and technical search engines, databases and tools, you will find a host of them on the internet too. Apart from these, there are specialized databases for the electrical and electronics and related fields, provided by IEEE. Since this article is about searching it is appropriate to say here that depending on your field of interest, if you if you do a web search for search engines and tools with the field as the keyword, you are sure to find a list of those as well.

Hitherto, we have assumed that the search is done with one or more individual keywords. It is also possible to search with Boolean operators. For example ((a OR b) AND (c OR d) NOT e). What this means is that the document must contain the words a or b and must also contain c or d but should not contain e. Elaborate combinations may be defined with Boolean operators. However, each tool has iits own syntax and the searcher has to learn them. Other combinations of keywords are also possible. For example if you enclose two or more words in inverted commas or quotation marks, Google, for example, treats it as a phrase and looks for those words in that sequence. Many search engines offer various types of proximity operators in that you can fetch all documents having those two words within a given number of words. It is not the purpose of this article to list all those but to give an idea of what a searcher can use.

There are means to search other than with keywords. Let us take one example – a classification search. Books are classified in a scientifically organized library based on their field and subject within that field and so on. Similarly, many classification schemes have been developed by different patent offices to classify patents. Thus, each patent is assigned one or more classification codes. Examples of such schemes are the US (USPC), Japanese (FI and F terms), German (DPK), European classifications (ECLA) and the international patent classification (IPC). However, there have been attempts to unify, the classification schemes and now there is Cooperative Patent Classification System (CPC), managed jointly by the European Patent Office and the US patent office. It has more than 250,000 classification entries and the numbers will grow. If you know the scheme of classification in general and determine one or more classes that an invention may fall under, you can search using only class codes. Further Espacenet provides an interface to search for the correct CPC itself, using keywords, if you do not know the classification codes. You can also use Boolean operators between codes. It is possible to search using combinations of classification codes and keywords for example, with the Boolean operators for example. It is sometimes beneficial to search for patents by a one or more companies or patentee or an inventor. Most databases and their search interfaces offer that facility.

With computer translations becoming ubiquitous most patents in languages other than English are automatically translated to English and are searchable only using English keyword. It may be beneficial, however, to use keywords from other languages. For example, in my experience, patents in the German language are very important for searching for patents in the field of lighting and illumination. So it would be worthwhile to collect and use keywords in multiple languages to expand the net.

With these, even if you get a patent in a language on which you do not have the required command, you can get them machine translated and study them. It is not unknown to get parts of or even complete patent documents translated by human experts for ascertaining their relevance.

Thus, a skilled and experienced patent searcher develops an elaborate skill and tool set and uses them judiciously to ferret out the most important documents from the massive databases. Apart from this, the skilled searcher has the ability to recognize the importance of a document to the job on hand by interpreting the document found.

This three article series attempts to give an insight into the search function. Due to the vastness of the subject and the limitation of space, they attempt to give an introduction to this field so that inventors and decision makers may benefit from it. If they have questions and requirements that may involve searching, they should consult patent professionals to make the best use of searches.

Article J L Anil Kumar, Senior Consultant, LexOrbis.

1st published on Lexology.