A patent is often described as a monopoly (generally limited to 17-20 years) granted to the inventor of a new and useful machine, process, or other invention in exchange for the inventor's complete written description of how to make and use the invention in a patent application. These details can be highly useful to design engineers, who can use patents to learn how others have approached similar problems, what design strategies have and have not worked in the past, and to get a handle on what is state-of-the-art in their field.
But with almost 7 million U.S. patents covering virtually every field of technology, it can be a lot like trying to find a needle in a haystack to locate the patents that are most relevant to your design problem. In this article, I share some of the basic search strategies I use as a patent lawyer (and former engineer) to sift through the clutter.
This article assumes that you're using the search engines of the U.S. Patent and Trademark Office (USPTO).
First a Few Basics on Patent Searching
Some of my favorite patent-searching resources on the Web are listed in the sidebar, and the following discussion will assume that you're using the search engine of the United States Patent and Trademark Office (USPTO), the government agency that administers the U.S. patent system.
While you can simply enter a string of terms into the search engine and obtain all the patents or published applications that contain these terms, the USPTO's search engines, like most patent search engines, helpfully allow "fielded" searching. Terms can be entered in certain fields, such as Title, Abstract, Assignee (Owner), etc., to locate patents or published patent applications having the entered terms in the specified fields (in the specified sections of the patents or applications).
The USPTO also allows strings of fielded search terms to be connected with Boolean terms such as AND, OR, and ANDNOT, and parentheses can be used to order the connected terms (see a sample search on page 80). Additionally, the ends of search terms can be truncated and the "wildcard" symbol $ can be substituted to search for variants of the term. For example, "circuit$" will search for the terms circuit, circuits, circuitry, etc. (Note that a term may not be truncated to less than four characters.) Search terms can also be combined in strings by using quotation marks. For example, entering the term "circuit board" (in quotes) will search for the adjacent words "circuit" and "board," in that order.
It might seem that a good way of locating relevant patents is to search in the Abstract (ABST) and/or Title (TTL) fields. Unfortunately, this is rarely the case. Titles are usually vaguely worded because patent attorneys fear the potential ramifications of a specifically worded title. The same is true of most Abstracts, which poorly represent the contents of their documents.
So it's no surprise, then, that an Abstract and/or Title search should never be regarded as complete and accurate. A Specification (SPEC) search, which extends to the detailed bodies of the patents or applications, is far more complete. Nevertheless, if a search strategy results in a very large number of hits, it may be preferable to begin a search by limiting it to the Title (TTL) or Abstract (ABST) fields.
Other useful search fields include the Assignee (AN) field, which may list the owner of the patent, and/or the Inventor (IN) field. You may be able to find relevant patents by searching for those that name a company and/or inventor who has expertise in your field of interest.
Nevertheless, while the use of fields, Boolean connectors, and wildcards can help you locate relevant patents and applications faster, many people still find it difficult to generate relevant search results.
All patents and patent applications are assigned "class numbers" by the USPTO codes that classify the patent or application into one or more very particular fields of technology, similar to the Dewey Decimal System. So if you can identify the classes of your problem or technology of interest, and then use the USPTO search engines to search documents in these classes, you'll often find relevant documents much faster.
To identify U.S. classes for particular fields of technology, you can access the Manual of U.S. Patent Classification at www.uspto.gov/web/classification/. Unfortunately, most users find the manual confusing and difficult to use, and it usually takes significant experience before one can quickly and accurately locate the appropriate class(es) relating to a technology in question.
By following the six easy steps I have outlined on page 80, you can bypass the manual almost entirely (or at least minimize its use) and get superior search results immediately.
Once you're done, you can then use the search results in your research and design efforts. In some cases, you may even be able to adopt a patented invention as an "off-the-shelf" solution. You're usually free to use matter described in a patent so long as:
(1) The matter is not secured by this (or another) patent (i.e., the matter is not defined by the "claims" set forth at the end of a patent); or
(2) Even if the matter is covered by the claims, if the patent's expired. Usually, patents have terms lasting 20 years from their patent application filing date, or 20 years from the date of patent issuance, whichever date is later. Both of these dates are shown on the first page of a patent. However, patents can (and often do) expire earlier for failure to pay periodic maintenance fees to the USPTO. You can check this out at the USPTO website at https://ramps.uspto.gov/eram/.
Nevertheless, if you have questions about whether and how you can use certain matter, you really should get the assistance of a patent attorney. As the old saying goes, "anyone who serves as his own attorney has a fool for a client."
Craig Fieschko has a BSME and MSME and worked for several years as an R&D engineer. He is a registered patent attorney at the DeWitt Ross & Stevens law firm, and he also teaches intellectual property law at the University of Wisconsin Law School. Request a more detailed version of the article by contacting Fieschko at
, or at (608) 828-0722.