Beginner's Guide to On-line Patent Searching

Prepared by Bill Larkins (US Patent Office Unit 2503, retired*)

*Disclaimer: This Guide represents only personal views, and should not be taken as representing the views of the US Patent and Trademark Office, nor should it be regarded as legal advice.  For a thorough patent search, the reader is strongly advised to contact a registered patent attorney or patent agent. A listing of US registered patent attorneys and agents can be found on the US Patent and Trademark Office web site. Patent Attorney and Agent lists are also available for most major countries through their respective patent offices.

 

On-line search sites

To do your own patent search before deciding whether an idea is worth following up on or is already known, there are resources available on the Internet World Wide Web. The US Patent and Trademark Office, the European Patent Office, and the Japanese Patent Office all have extensive files of their respective published patent documents available in a format for on-line searching.  Several other countries also have made their patent documents available on line for searching, but the bulk of patent documents world-wide are issued by the above three offices. Another good search tool is provided by the Singapore Intellectual Property Office, which cross-searches various patent offices worldwide and also includes technical literature. Unfortunately, none of the major patent issuing authorities have fully searchable data bases that go back to older patents.  The data bases only include searchable full text documents from the 1970's for the US, (images of earlier US patents are available now at the US Patent and Trademark Office web site). European and Japanese patent documents vary in completeness.

On-line patent classifications


In order to do an on-line patent search, you first need to know what areas to search.  The best search is done using a classified search file, in which the patent documents are classified according to subject matter.  There are two major patent classification systems.  The US Patent Classification can be accessed through Patentec while the International Classification can be accessed through the World Intellectual Property Organization, WIPO.
 

"Full Text" searching

Full text searching can also be done through the US Patent and Trademark Office web site. However, full text searching, in which searches are done for particular words in the text of a patent, is difficult to do reliably.  Full text searches require that the exact words that you are searching for appear in the document. Because a concept can be described in an almost unlimited number of ways, there is no way to reliably carry out a typical search using the "full text" method. One would have to be able to think of every possible combination of words that might be used to describe a concept, in order to conduct a reliable full text search. If your invention involved a flexible rake handle, you couldn't just search for "flexible handle", the concept might be described in relevant documents as "bendable" or "hinged" or "jointed" or a multitude of other possible terms, and it might be "handle" or "shaft" or various other terms.  Generally, only a complete classified file search can be regarded as meaningful.

So to do an on-line search, go to the US Patent Classification and the International Classification and try to locate classifications that would be appropriate to your invention.

A few words about the language of patent classification systems might be in order. Patent classifications were developed over time, and are continually evolving as technology improves. Many of the class and subclass names reflect this change, for example, if your invention were a computer memory cell of the type known as a "Dynamic Random Access Memory" (DRAM), the normal memory chip in today's personal computers, the proper search area would be Class 365, Static Memory, and not the class that refers to "dynamic" memory. This came about because before the advent of semiconductor-based computer memories, computer memory often relied on a moving magnetic storage medium (think of a computer disk drive.)  The "Static" in class 365 is not the same as the "static" in "dynamic RAM:" v.s. "static RAM" in current terminology. Both "dynamic" and "static" RAM are classified in class 365; neither have any moving parts; the "Static" in the title of Class 365 is based on physical movement, not the distinction between memory which must be frequently refreshed and memory which holds its state as long as the power is on which is what is meant in computer terms by "dynamic" v.s. "static" memory.

Also, since patent classes change and are replaced over time, older patents would be classified in the classifications in existance at the time those older patents issued. Currently the US Patent Office updates their online database to reflect reclassification projects, so that current classifications are given for older patents as well, but this may not be the case for other countries. This can cause serious problems in on-line searching, since older patents will not have the classifications in the current on-line classification manual.

Once you have located likely looking US and International Classifications for your idea, it's time to start searching. Go to the US Patent and Trademark Office web site, and do a "text" search of the classifications you selected. You should get a "hit list" of US patents in the classifications. View these documents, one at a time. On the US web site, you can also get full images of the patent documents (necessary to examine the drawings.)