Prior Art Searches: A Must For Innovative SMES

By Paul Schwander, European Patent Office, The Hague1

Is my invention new? Who owns it already?

When you buy a house, a systematic check to verify who the real owner is done in order to prevent bad surprises. Curiously enough, this type of systematic check is not common practice in the immaterial world. When an organisation invests large sums of money in Research and Development (R&D) activities, it seldom verifies if the technology it wants to develop already exists and if it is it owned by someone else.

To know what has been developed before you initiate R&D work you need to perform a so-called prior art search to detect all existing similar developments or inventions. Usually, researchers rely on classic sources to access this information such as scientific publications, conference documentation, contacts with peers, the Internet, etc. In the process, patents are often overlooked because scientists consider patents to be more of a business instrument than a source of information.

Patents, however, not only offer a huge insight into existing technologies but also provide essential information on who owns a technology and who the major players are in a particular field.

Patents: a major source of prior art information

There are many reasons why you should systematically use patent databases as a source of technical information:

Patent documents contain information you will not find elsewhere. Since patent documents must describe inventions in such a way that persons skilled in the art can reproduce them, (insufficient disclosure can result in the rejection of a patent application) these documents will contain detailed information you will not find in classic scientific publications.

Patent documents are easily accessible. Today many patent databases are available freely on the Internet. Patent offices worldwide have agreed on publication standards and the sharing of their publications, resulting in global, well structured databases. Patent data is also classified according to a universally accepted scheme, subdividing the technical fields into very fine sub-domains. Classic scientific publications, on the other hand, originate from many sources and do not respect publication standards as patents do.

Free parking place indicators

Patent documents being systematically classified, you can quickly access huge amount of information on a given subject. This patent relates to free parking place indicators and is assigned to a technical subdivision of the International Classification G08G1/14 containing another 193 patent documents all relating to that subject.

Patent information is up-to-date. Most companies prefer not to disclose their research results for obvious competition reasons. But if a company wants to obtain exclusive rights on its invention, it must file a patent application that will eventually be published and made available to the public. This explains why patents are often the first publication on a given invention and are therefore a very up-to-date source of information on a technology.

Patents offer more than technical information. As patent documents can be legal titles of ownership, they give precious indications on which companies hold a technology, on inventors, on the length of ownership, on the free availability of a technology when the patent is lapsed, etc.

Patent document

This patent document relates to genetically modified plants comprising a reporter system to detect landmines: these plants turn from green to red when they are in contact with explosives in the soil. An article relating to that invention usually contains a few lines, while the corresponding patent document describes this invention in 111 pages! This illustrates the huge quantity of information that can only be retrieved from patent documents.

When do I need prior art information? 

Before starting your research

Whenever you enter a research project it’s a must to conduct a prior art analysis. This analysis can save you huge sums of money by detecting existing developments. It can also show you the best partners with whom you can collaborate. By basing your R&D work on what already exists, you can embark on genuinely innovative work.

During your research

It is most likely that your work, even based on an initial analysis, will venture into unexplored territories. In addition, during your research, new publications are made. Therefore, a permanent technology watch, detecting the latest publications in your research field, will keep you up-to-date on the progress made by others. 

Before exploiting a product or process

As the technology you want to commercialise can be owned by third parties, a deeper “freedom to operate” search is necessary before commercially exploiting a new product or process. This search, detecting valid patents that can hinder the exploitation of your invention, is for instance necessary if you want to market your invention. It is important to stress that even if you have a granted patent on your invention, it does not exclude your product being partially or fully covered by another patent. This often happens because patents are rights to exclude others from using an invention and because patents can be granted on improvements of an initial basic invention.

There are many other situations where this information can be useful. For example, to acquire statistical analysis on the most innovative companies in a field, to cancel a granted patent used against you by detecting new invalidating prior art that has not been considered in the patent grant process, etc.

How to proceed?

Prior art searches can have serious financial consequences as they can put into question a research programme or the commercialisation of a new product or process. While one can adopt, in an initial phase, an amateurish approach, the complete analysis must be left to information specialists using professional tools. This should not prevent you, however, from conducting a pre-analysis yourself to get an indication of how active a field is and who the major players are.

Do it yourself

If you can dedicate time to get acquainted with some search techniques, you can use free patent databases on the Internet. The basics you need to know are:

The concept approach

A prior art search usually boils down to a combination of “concepts” defining the subject you are looking for. Concepts can be retrieved by imagining ten different texts describing the same invention. In these ten different texts, you will necessarily find words expressing the same concepts. Knowing that the documents you are looking for have these common features, these so called concepts, your search will consist in finding documents where a given combination of concepts is present.

Since patent documents are classified, searching for a given concept must not be limited to a keyword search. A concept can perfectly be expressed by a classification symbol.

A sound search strategy will therefore involve a combination of keywords and classification symbols. An individual concept is usually defined by an "or", combination of keywords and classification symbols all relating to this concept.

Experience shows that it is not easy from the start to define all possible synonyms and classifications covering one concept. This usually remains an imperfect process. It can be tuned during the search itself as relevant documents reveal new ways to express your concepts. Using these new concepts, more documents can be retrieved and so on. This becomes an iterative process that an experienced searcher ends when he has feels that additional efforts will not bring more results.

Which “do it yourself” tools can I use to perform a search?

Before proceeding with a search, it is advised to develop your search skills using real examples as the one indicated below.

Free patent search tools that can be used to perform these searches are:

- esp@cenet®2, a service co-ordinated by the European Patent Office in close co-operation with the European Patent Organisation Member States. It offers an extensive patent coverage: 45 million documents covering 71 different countries or organisations- and gives access to the unique classification scheme developed and maintained by the EPO called ECLA.

- The Intellectual Project Digital Library (IPDL)3 of WIPO gives access to patent documents and abstracts published under the PCT framework - Patent Cooperation Treaty. This route is usually followed by applicants seeking a worldwide protection for their invention.

- DEPATISnet4, a service provided by the German Patent and Trade Mark Office offering access to patents of most industrialised countries using various search possibilities.

- The US Patent and Trademark Office Patent database5 covering US patents. Some part of the collection can be searched full-text. This collection is classified according to the US Patent Classification scheme.

- The Japanese Patent database6 offering access to Japanese patents and utility models.

This list is by far not exhaustive. More free databases can be found at

Advanced Search screenshot

All patent database services differ in the collection covered or the search possibilities. Starting your search using esp@cenet®, is a good option as this service covers most countries and offers a huge classified collection.

You can also supplement your patent search using the classic Internet search engines. For many fields, there are often other specialised sources available for free on the Internet, such as Medline7 in the biomedical field, that give access to non-patent information.

An example on how to find prior art about systems to prevent the use of mobile phones in pubic areas using esp@cenet®.

This example depicts a possible search strategy using the esp@cenet® tool to retrieve prior art information. The online version of this example can be accessed under:

You are often disturbed by the use of mobile phones in public areas: cinema, hospitals, etc. To resolve this problem, one can imagine systems blocking mobile telephone communications in a given area or room. In this example we will try retrieving patents relating to this system using the esp@cenet® service.

As a first step you can conduct a keyword search combining the concepts describing the invention: common technical features that may be found in patents relating to this subject.

To cover our invention, one can detect the following concepts, expressed by sets of synonyms:

- Concept mobile phone : mobile phone, cellular phone

- Concept noise: noise, disturb*, silence

- Concept public room: hospital, cinema, public

- Concept prevent: prevent*, screen*

The “*” stands for a truncation symbol: all words starting with the string of characters preceding the star symbol will be searched.

As a second step you can do a keyword search in the worldwide database of esp@cenet® using these sets of synonyms.

The combination "cellular and telephone and disturb*" yields a relevant document that corresponds to our subject.

- US2001006886 Communication inhibiting device and communication inhibiting system

To proceed further you must be familiar with the patent classification system. In our case, you can retrieve the classification symbol assigned to the relevant document, check the field it covers and continue your search using it as a search criterion if it seems relevant.

The US document we have retrieved is classified under the symbol H04K3/00 that covers systems to jam communications.

This classification symbol entered in the search screen in combination with the keywords "telephone or phone" yields a small number of additional documents, among them:

- WO0207120, A system to deny cellular service at refuelling stations

- EP1061686, Call masking system for mobile telephone

- WO9818232, Cellular telephone jamming method and device

This search can be continued to obtain a broader collection of patents by using other words to cover the concept “mobile telephone”. H04K3/00 combined with "mobile or cellular" yields an interesting list of additional relevant patents.

This search cannot be considered exhaustive, but it does give a good overview of existing patents and technologies used to inhibit cellular phone calls. A company investing money in such systems must seek the services of a patent search professional to have the most complete results before investing money in its project.

Before doing a search, always keep in mind

Limitation of the concept approach

When a subject cannot be expressed in a "normal" sentence, the concept approach is not applicable or can only be applicable in presence of good indexing schemes or using special search engines. It would be wrong to think of the concept approach as "the" universal search strategy.

EP 0 785 216 A1

Example of a patent on a genetic sequence for which the concept approach is impossible to use. The biotechnology field to which this patent belongs, requires special tools to search for prior art information.

Use the Web to its full extent

Specific patent searches are sometimes best conducted using both the information available on the Web and in patent databases: patent numbers or inventors’ names are often mentioned in documents available from the Internet. These are data you can use to continue the search in patent databases.

Technical domains where searches cannot be limited to patents

Even if patents offer the most exhaustive source of information for many domains, non-patent literature must also be consulted in the context of a prior art search. The domains where this type of literature plays an essential role comprise among others: medical science, computer technology and biotechnology.

Hiring external services

The limitations of the do-it-yourself approach

Only experienced searchers using professional tools can reach an adequate degree of search completeness. You cannot expect to be search proficient with a few minutes of training. In addition, it can be more efficient to hire a professional directly than to use free patent search tools yourself. A specialist uses fee-based professional tools and gets the out of all possible sources.

How do I find prior art search professionals?

Possible partners that perform professional searches include: patent offices search departments, patent libraries (sometimes operating under a patent office), patent search professional, specialised librarians and patent attorneys. Your national patent office is usually the best source of information about professional services8.


A simple prior art search can be conducted starting at 500€ (this increases with the complexity and degree of exhaustiveness required). The results of such searches can affect R&D investments, which are hundreds to thousands of times more costly, therefore, it would be extremely risky to enter an R&D project without performing such a search. Patent sources must be systematically considered when doing prior art searches.  Free patent information tools on the Internet offer a quick overview of what this source of information can offer. Persons who want to deepen their knowledge in this field or seek professional advice should best contact their patent office.

1 The views expressed in this article are those of the author and may not necessarily reflect those of the European Patent Office.







8 The following pages refer to websites of organisations that can help you find a search expert: