I work as an engineer (not software) and occasionally I have ideas that might make sense to follow through and maybe arive at some sort of invention. The first step would be, of course, to look up if anyone else had the same idea.

My approach consists mainly of either knowing from my field of the industry that something has already been done, asking collegues, or googling, searching journals.

What are other approaches? I'm especially mystified the way patents are sorted (I work in Germany, the most relevant search engine would be the DEPATIS net or somesuch of the german patent office) and would appreciate any guide here. Is there a patent research 101 out there?

Also, I find I hard to gather technical information from a patent but that's mostly because of the weird, long sentences that lawyers seem to like and the weird structure that the patent system forces on the documents - something that practice can probably fix.

Note that I want to know how to find out two linked things:

*Has something been done and is proven or disproven to work?

*Has something been patented or can't be because of prior art?

But I would really appreciate an answer that only adresses one of those.

  • What is the meaning of SOTA?
    – on4aa
    Commented Feb 4, 2017 at 13:33
  • 1
    State of the Art, here meaning the term as it is used in patent law.
    – mart
    Commented Feb 4, 2017 at 20:35

3 Answers 3


I'll just say a little about searching that may help get you started. Your last two questions deserve separate answers, I might come back to that in a while if no-one else addresses them.

Most patent databases - both the free ones like depatis, espacenet, google patents and the uspto one, and the subscription ones - allow word searches. But this has it's limitations, and getting to know the patent classification system will really improve your searches.

The classification I use most often is the IPC which you can learn more about here http://www.wipo.int/classifications/ipc/en/general/ Depatis uses this. Espacenet also uses the CPC, which is is built on the IPC but with a further level of resolution. Google patents and the USPTO site also use the US classification system, and you might be better using this for those database because some of the IPC codes the US patents were given aren't very accurate, but I believe the USPTO are switching to the CPC so this may change.

You can either dive straight in and search the classification, or find some close patents with keywords and see how they've been classified. Some inventions fall neatly within a single classification group, others don't seem to fit in anywhere and can be liberally spread through the whole classification.

How I search is to think of the relevant concepts, find classifications of each concept, and synonyms for each concept, and then search the combinations eg. classification(concept 1) AND ((synonym1(concept 2) OR (synonym2(concept 2)).

Once you've found some close patents, you can also search through the cited and citing patents, piggybacking on an Examiner's previous search (though they were perhaps searching for something slightly different). Still, it's a good way to widen a search.

Be aware of what coverage the database you're using has. The USPTO database only has US patents, google patents now has EP patents, Espacenet has a good worldwide coverage, I think depatis is similar, but you need to check.

When I say 'patent', this includes patent applications; for prior art purposes, it doesn't make any difference. Patents are searched because they are (relatively) well classified, and the publication date is known with certainty, but of course it's often helpful to top a search up with other sources.


To supplement the answer above:

There is a book that is pretty good. "Patent Searching Made Easy: How to do Patent Searches on the Internet and in the Library" By David Hitchcock.

Other places to search might be google scholar and for some things halfbakery. I also look up old versions of web sites in the wayback machine archive.org

At one presentation on searching by a professional searcher, he had on his PowerPoint "step 3 - walk your dog". There can be a Zen to searching. One aspect of that I have noticed is that it is much easier to find things I hope to find. That means it is hard to find my own dumb ideas - I don't really want to find them.


Patent searching has become a specialty businesses with hundreds of individuals whose primary job is to perform patent searches. I think that there probably are best practices and minimum standards of care.

One aspect is the databases searched. General subdivisions might include patents by place of origin, published patent documents by place of origin, and other techinical publications by database. Some familiarity of the technology may be required to determine which databases need to be included.

Another area subject to best practices would be the search tecnhiques which will depend greatly on the technology. Some technologies lend themselves to image searches more than others. Searching by classification as mentioned by PNH above is standard. It is also becoming expected that a search will include general internet search results. Additional expertise and search strategy probably varies by industry. There is a steep learning curve, but eventually you will become familiar with the different parts of patent documents and the legalese.

Most law firms contract out searches.

  • out of curiosity, who does the research? Engineers/technicians who couldn't get another leg up?
    – mart
    Commented Feb 1, 2013 at 8:39
  • Great question! It used to be aspiring patent attorneys. Now, it depends on who you are using. Some search firms use engineers or techs who found themselves there; some even outsource to India. However, there are some very accomplished researchers who spend a lot of time and effort searching, maintaining databases, and creating sophisticated search routines. These individuals chose this job.
    – Yorick
    Commented Feb 1, 2013 at 20:35

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