The US Patent and Trademark Office’s web site is one of the most valuable publicly available resources for patent searches. All US patents are there along with most patent applications filed since 2000.  Because the potential value of a patent is closely tied to market size, and because the US is often the world’s largest market for an invention, that invention is more likely to be patented in the US than elsewhere. That does not mean this one database contains all the world’s technology. It does mean that this database should not be ignored.

Using the USPTO databases can be frustrating. Every database seems to have its own set of tricks and ’cheats’ that a searcher needs to learn in order to be effective. The USPTO’s has gone through several rounds of enhancements and is something of a system architect’s bad dream. It provides different amounts of data for different records and requires a different syntax at different search stages.

Keyword searches are familiar to almost all internet users. The leading internet search sites have done a lot to make such searches effective. Even so, keyword searches turn up lots of irrelevant references and miss a lot of important ones that were written using a different set of words than those selected by the searcher.  If you want to see a field where the writer’s choice of vocabulary is vastly different from what one ordinarily encounters – welcome to the world of patent searching. Keyword searches may be a good start, but other techniques are almost always called for as well.

Things to DO

·         Start with a keyword search and poke around until you find something close to the subject matter you’re interested in. On the full-text page of that reference, note the “US Class” or classes. There may be several. These are written in the format NN/MM, where NN is numeric and MM is some alphanumeric string. The ‘vaguely close’ reference might be in the same class (i.e., the ‘NN’ field) as the invention you’re looking for, but usually isn’t in the same subclass. This gets us to the next step:

·         Use the Manual of Classification of Patents to find references in the subject area of interest. Once you’ve found a likely class is (from a keyword search, for example), go to one of the ‘Class Numbers’ pages and read  through it to find if your invention fits. Clicking on any subclass takes you to the class definitions – which often point you to other classes/subclasses of possible interest. There’s no hard and fast rule, but a good search usually hits 2-3 classes and a total of 5-10 subclasses.

·         Use the citation search tools on any issued patent that appears to be interesting. The earlier patents listed there include citations that the examiner thought were most representative of prior art in the field. Looking at the cited ones will generally get you back to earlier generations of ideas in the same area. Immediately below the list of patents referred to by the one you’ve found, there’s a hyperlink (labeled ‘referenced by’) to all later US patents that cite the one you’re viewing. Look at them too.

·         Look at the drawings – the one on the front page of an issued patent has been selected by the examiner to be the one that best shows the invention. And, although the text of the patent may seem like gobbledygook, the pictures are generally clear. Of course, your browser will have to be able to display Tagged Image Format Files (*.tif) in order to do this. The PTO’s website will guide you to several browser plug-ins that facilitate this.

·         Search both issued patents and published applications. The published applications database often has the newest available material.  And, because it contains ‘raw’, unexamined filings, it can show you what ‘re-inventions’ are popular in your technical area.

Some DON’Ts

·         Don’t believe any search that pretends to tell you ‘there’s nothing like it out there’. There’s always something like it out there.

·         Don’t think that a title captures the essence of what a patent is all about. Titles are often overly general.

·         In reviewing a list of patents in a subclass of interest, don’t stop when the list runs out of titles and displays only patent numbers. Those apparently incomplete list entries are the older references that often show the basics of the technology.

·         Don’t expect that “no patents satisfied the query” means what it says. This is the default error message the system designers left us to live with. It usually means that your syntax was wrong.

·         Don’t stop after a USPTO search. Be sure to check other major patent databases as well as non-patent references available through your favorite internet search engine.

Some Gotcha’s

·         Most USPTO patent records from before 1976 have no associated text. No titles. No abstracts. No inventor lists, No assignees. No text. Period. Searching for anything older than 1976 generally requires use of the Manual of Classification, or a newer patent with an extensive prior art reference list. Not searching for anything older than 1976 may deprive you of the most basic and important references.

·         The default search period for issued patents is 1976-present. This may be good for an initial keyword scan, but you’ll need to remember to select ‘all years’ for later steps in your search.

·         The USPTO’s syntax is confusing. The error messages are not always helpful. This is your government. Not Google.

·         Subject classifications in the published applications database are only tentative.

David A. Kiewit
Registered Patent Agent
5901 Third St. South
St. Petersburg FL 33705-5305
+1 (727) 656-0669 voice

+1 (760) 841-0989 fax
questions to:
Copyright 2002-2013 by David A. Kiewit
All rights reserved



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