Wednesday, April 3, 2019

Prior Art Searching: Utilizing CPC Subclasses

One of the most robust and useful techniques in trawling the patent literature centers on the Cooperative Patent Classification (CPC) subclasses.  The CPC system is an international classification scheme that indexes and classifies patent publications into general inventive concepts.  Because the CPC system is used across many jurisdictions, it may further serve to sidestep linguistic barriers.
Returning to the electric unicycle wheel lighting example of prior posts, it will quickly become clear how useful the CPC system can be.  You must first determine which CPC subclass(es) will be of greatest relevance to your invention.  Beginning with the fairly broad search query (electric) (unicycle OR monocycle), Google Patents returns, as discussed previously, thousands of patents across a wide spectrum of relevance.
To effectively utilize the CPC system in the process of sifting through the prior art, begin by selecting a patent publication which covers your broadest concepts.  As an example, the top result returned from the above search query is U.S. Patent No. 8,800,697 (“ELECTRIC-POWERED SELF-BALANCING UNICYCLE WITH STEERING LINKAGE BETWEEN HANDLEBARS AND WHEEL FORKS”).  Though the ‘697 patent doesn’t cover lighting subsystems in detail, it certainly addresses electric unicycles broadly.
With this patent selected, look for the “Classifications” header near the top of the publication page.

Select “View 9 more classifications” to toggle a drop-down menu (publications are often assigned more than one CPC subclass).

B60L2200/14 sounds like a good start – this is listed as the CPC subclass for “vehicles with one wheel only,” which should cover both unicycles and monocycles.  Note, however, that this is just the description of the sub-classification.  It’s worth looking at the CPC scheme on the USPTO’s website to determine what the broader B60L classification is directed to.  This may be significant, because the CPC subclass B60L may be a broad concept like “vehicles,” or it may be something more specific, like “brakes.”

Perfect – B60L is directed to “propulsion of electrically-propelled vehicles.”  A more complete description of B60L2200/14 is thus “propulsion of electrically-propelled vehicles with one wheel only.”  You can now effectively utilize the CPC subclass in your prior art search.

Notice that there are now only 67 results – the CPC subclass has filtered out publications that simply recite the terms “electric” and “unicycle” or “monocycle” in favor of those publications which are specifically directed to propulsion of electric unicycles/monocycles.  Now tack on some of the key search terms from the previous posts to determine which of these publications show similar features to your invention.

Only 7 results!  By mixing and matching the tactics of this post and the two immediately preceding it, you can thus capture a few specific publications directly pertinent to your invention.  After reading these yourself, but before handing them over to your attorney for a more substantive analysis and further searching, there is one more trick that you should know.
 Once you have found a very close patent publication to your inventive concept, direct your attention to the info box at the top of the publication page.  Therein, you will find a citations section.

The “Patent citations,” “Non-patent citations,” and “Cited by” links are shortcuts to the bottom of the page, which list out every publication which either cites the publication in question, or which the publication itself cites.  This will allow you to fill in any small gaps which combinations of your other searching techniques may have left exposed.  They may also serve as a good double-check of the quality of your search queries; that is, if you are running into the same publications, you have likely tracked down near everything of relevance.  You are now free to reinvent the wheel!
In the next post, we will take several steps back to address how to assess the patent landscape prior to performing any rigorous, publication-directed searches.  This will be key to the brainstorming process and will allow you to understand your competitors and their filing trends.  You will find that several of the concepts and strategies already discussed will be necessary for this stage.


Note that the views expressed herein do not represent the views of any law firm or client, and may not even represent the views of the author. This blog is NOT legal advice and is for informational purposes only. No attorney client relationship can be formed by reading this blog or using any of the information provided. The accuracy of the information provided has not been verified.