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Patent/Prior Art Searching: Start

This a good review of the topics covered in the Patents/Prior Art Searching Workshop


This guide will serve to introduce the reader to the challenges of prior art searching as a part of an inventor's greater patent application.  It covers the typical stumbling blocks or pinch-points that potential inventors might have with patent searching in preparation for a future meeting with a patent attorney or patent agent.

Helpful Background Information

The Challenges of Prior Art Searching (as framed by the USPTO 7-Step Strategy)

Brainstorm Terms Describing Your Invention

Brainstorming of terms for patent literature searching is the first threshold a new inventor will have to cross.  A key thing to keep in mind is how patents are currently written and, in many cases, how patents have changed over the years.  Patents can be difficult to locate with keywords because they usually describe an invention by what it does instead of what it is.  The classic example is the original patent for the computer mouse, "X-Y POSITION INDICATOR FOR A DISPLAY SYSTEM" (US 3,541,541).  If you think about it, yes, a computer mouse is used to control a cursor on a computer screen.  Usually this is indeed a two-dimensional x-y position that the user is controlling.  The important point is that the term "computer mouse" will be nowhere to be found!  Thus, searching with keywords can be quite tricky.

What 's an inventor to do?  It's okay to try what it's called, you'll probably find a few patents.  But if you have a chance to brainstorm the keywords for a search, make a concerted effort to hone in on what it does and try to describe that.  You'll also need to consider Steps 2 through 4 of this search strategy where one utilizes patent classification.

If you are really struggling at this stage, it will help if you have come across any patents already.  Explore how those patents are worded.  Patent searching will be an iterative process.  The inventor should always be on the lookout for new or surprising ways of describing stuff that they're interested in.

Here are some other great examples of the challenges with the written descriptions of inventions:

MULTI-EVENT INPUT SYSTEM (US 7,777,732) - Apple's patent for the enhanced touch sensitive screen for its iPhone and iPad (suggested by Li Zhang of the University of Saskachewan).

IMPROVEMENT IN VELOCIPEDES (US 59,915) - This early variant of what we now call the bicycle reminds us that the names for common items can change over the years (suggested by Rebecca Renirie of Central Michigan University).

GENERALLY SPHERICAL OBJECT WITH FLOPPY FILAMENTS TO PROMOTE SURE CAPTURE (US 4,756,529) - It's the Koosh ball, of course!!! (suggested by many).

OCCUPANT PROPELLED LAND VEHICLE (US 6,352,274) -This is a three-wheeled vehicle with hand peddles instead of foot peddles so that someone that is wheelchair bound might enjoy a bicycle experience. (suggested by Rebecca Greenstein of Northwestern University).

IMPROVEMENT IN TELEGRAPHY (US 174,465) - Even reading the patent it's hard to realize that this is the telephone! (suggested by Larayne Dallas of the University of Texas at Austin).


Access and Review Cooperative Patent Classification (CPC) Schema Using UPSTO's Website Site Search Feature

The Cooperative Patent Classification Schema is searchable from the home page of the USPTO website. In the screenshot below, you'll find the opening query for where I might find the classification number for a clock.  I'm thinking that I want to find the right classification for a cuckoo clock ... if that might exist.  Look in the upper right hand corner of the screen shot to see the query "cpc scheme clock" and then keep scrolling down for notes and screen shots.

Screen Shot of CPC Scheme Search

The results of the search of the CPC Scheme are seen below:

Screen Shot of CPC Scheme Search Results

As is often the case, we will need to peruse the results for our needs.True cuckoo clocks aren't powered by electricity.  Scrolling through the search results we come across:

Screen Shot of the Search Result of Interest

Our next step is to take a look at the details for the "G04B" section of the Cooperative Patent Classification system. It's a long section, but at least it's feasible to use the browser to search for a word ... like cuckoo.

Screen Shot Showing a Simple Search for "cuckoo" within G04B

So, our result seems to G04B 25/06.  You, as the inventor, will be the best judge of the most promising areas of the classification.  For demonstration purposes, let's move on to Step 3.


Review Classification Definition Linked to the CPC Classification You Selected

Sometimes, inspection of the classification does not yield additional information.  Sometimes it does.  In this case, this is all the information that we'll get.

Screen Shot of G408 25/06 - No Additional Information This Time

Retrieve and Review Issued Patents Using the CPC Classification You Selected

In this step of the process, we'll face a typical problem of searching databases - query syntax.  Databases can have odd quirks when it comes to what constitutes an allowable query.  The search system of the USPTO is no exception.  You'll note that our classification for cuckoo clocks was:

G04B 25/06.

In order to successfully retrieve our classification number, we need to keep in mind that the query syntax might be a little tricky.  It is, but it's not too bad.  Please note that you can always find help for the syntax of your queries.  I'll show you where, but for now we'll start at the USPTO main web page.  In this screen shot, I've hovered over the word Patents that is found on the top left of the screen.  Look at the "Application process" column and you'll see the first topic is Search for Patents.

Screen Shot of the USPTO Search Page While Hovering Over "Patents"

Below is the Search for Patents page.  There are many helpful links on this particular page that I would encourage you to explore, but for now let's start with the USPTO Patent Full-Text and Image Database (PatFT).  We want to try our CPC Classification Number to find the mother lode of cuckoo clock patents.

The USPTO Search for Patents Page

That kept us on the same page, but in an area devoted to searching.  We want to choose the Quick Search choice under Searching Full-Text Patents (Since 1976).  It's not obvious at this point, but when we get to the search form where we can enter our query, we'll be able to extend our CPC Classification Number search back to 1790.

Screen Shot of Specific Area of the USPTO Search for Patents Page Focusing on Searching Full Text Patents (since 1976)

The next screen shot finally shows the query form for our search.  Note that "Current CPC Classification" is the field that we want to search (NOT "Current CPC Classification Class").  The latter would be if you wanted a broader search of the G04B class without specifying the 25/06 subclass.  Note that I've selected "1790 to present (entire database)."  We're able to do that since we're doing a classification search.  I do see the note in red font at the bottom of our screen.  Reclassification is at least underway so that we can use the CPC Classification instead of the US Classification, but I'm not sure of the current status.  We will currently get a number of pre-1976 patents with a Current CPC Classification search, but is it a complete search?  That's to be determined.  For now we will have to assume that our results might be incomplete.  We'll revisit this in Step 7.  Finally, take note of how the Current CPC Classification is entered in the query.  There is no longer a blank space between the "B" and the "2" (the class and the subclass).  A compacted form of the query of a particular field of a database is done by design.  There is no uniform standard for database design, so we need to always keep this in mind..  Always look for it as a possibility if you want to run a query on an alphanumeric field of a database.  A good example is a search for a government report number.  So, our query is:

USPTO Search Query Form Prepared for a Search

Our search results, will include anything with a "moving figure."  Remember, cuckoo clocks were an example.  So, even this search could be considered broad.  The searcher will need to make a choice.  One benefit from reviewing all 33 patents would be to explore any kind of mechanical movement in this type of clock.  The inventor could learn a lot from the review.  It will have to be a judgment call with regard to their time, cost avoidance and idea generation (at a minimum).  The inventor can quickly scan 33 patents to determine if they wish to inspect them more closely, so my personal advice (I'm not an attorney ... I'm a librarian) would be to go for it - scan the front page of all 33.  As you scan down the list, some are obviously of interest just from the title while others are rather vaguely worded.  The pre-1976 patents have an icon that is supposed to indicate that all you will get is an image of the patent (no searchable full text).  One helpful thing for the older patents is a listing of US Patent Classification numbers with the primary one in bold font.  We might want to use those numbers in Step 7.  The next two screen shots illustrate these points:

Screen Shot of Search Results for Cuckoo Clock via Current CPC Classification

Screen Shot of Further USPTO Search Results for Cuckoo Clock Query

Conduct In-Depth Review of Patents You Selected Based on Their Front-Page Information

Encourage your inventor to keep subsequent search activity in mind as they review patents of great interest.  Suggestions are:

  • Inventor and assignee names can be important search terms.  They should also be put into a list of potential competitors/collaborators.
  • Allow yourself to recognize possible new terminology or classification numbers which could be of use.
  • If you use a tool like Mendeley or Zotero, you could start taking notes about how a particular patent doesn't measure up to your idea.
  • You may wish to take notes about particularly clever ideas that you wish to think about in more depth at a later time.

Note that recent patents (since 1976) are readily available for viewing as images.  That's great if you need to see the drawings or the overall image of the patent.  Here's an image of US 9,514,730:

Screen Shot of the Image of US 9,514,730


While the image is helpful in some ways, looking at the full text of the patent has its advantages.  Links are provided to any citing patents and to the US Patents that are considered prior art.  In addition, a more complete listing of the "Field of Classification Search" is provided.  See the next screen shot to see what I mean:

Screen Shot of the Text of US 9,514,730

Screen Shot of More of the Text of US 9,514,730

Retrieve and Review Published Patent Applications Using the CPC Classifications You Identified

Relax! You've done all of the heavy lifting for this step.  You know the CPC Classification(s) you want to search and you even know the syntax for the query.  As before, keep in mind to be on the lookout for terminology, etc.

So, the query:

Screen Shot of Patent Application Full Text and Image Database Search Query

And, the results:

Screen Shot of the Search Results for a Search of the Patent Application Full Text and Image Database


It's important to note that the general layout of the patent application will be similar to that of a patent:

Screen Shot of an Image of a US Patent Application Publication


Similarly, the full text of the patent application can be viewed.  Again, links to citing references and prior art that are US patents are available.

Options for Broadening Your Search

There are a number of ways that a search can be broadened. Most are going to be crucial for a thorough search.  In general, they include:



  • Searching a research database that indexes patent literature in addition to other types of literature such as:


Eeek!  So when do we stop?!!

  • Have you thought of every reasonable database to search for the topic?
  • Did you exhaust trying possible keywords or classification numbers?
  • Did you follow up on inventors and assignees of interest?
  • Are you still discovering relevant patents or other literature that you haven't seen before?


Are You Searching for Design Patents instead of Utility Patents? 

Consider the following databases (beyond those you've already learned of):