Patent Classification Systems
Below are some of the various schemes historically used or currently used to classify patents.
With literally millions of patents, having some sort of classification or organization
is a good thing. It's generally useful to be able do searches for patents within a
particular class. In theory similar patents should be assigned similar classifications.
For extra fun I've added a power search
that lets you search
the five systems below from that single page.
ccl or USPC is the uspto's original patent classification system which is apparently
being phased out through no fault of my own. (They will still be used for design and plant
patents so they won't go away entirely.)
Try the beta
ccl search! Enter strings to look for in ccl subclass definitions
and then search for corresponding patents and/or patent applications.
- Display a ccl subclass' details and generate a search for it.
- Check out my spin on the NBER's (National Bureau of Economic Research)
aggregation of the patent office's classifications.
- Class listings
- Try the beta classification search!
- Class listings
- Collapsed listing
- Subclass counts
This system was phased out late in 1989 and was what the original cpc acronym stood for.
Updated for 2019!
- Here is a Canadian Patent Classification search you can use. It still is relevant on the
Canadian Patent Office's web site to find older patents classified under this system.
- (Corrected Link) Display a cpc subclass' details and generates a CIPO (Canadian Intellectual Property Office) search for it!
- Also available are Canadian class listings.
Updated for 2020.08
- See fun ipc statistics
- Try the beta
ipc search! Enter strings to look for in ipc subclass definitions
and then search for corresponding patents and/or patent applications at the uspto.
- Display an ipc subclass' details and generate a CIPO search for it.
This is the world's newfangled way of classifying patents. Most countries on the planet have adopted it.
Here are tools to help you navigate the twisty passages.
Classification Case Study
- See fun cpc statistics
Try the beta
cpc search! Enter strings to look for in cpc classifications
and then search for corresponding US patents and/or US patent applications.
- Display a cpc classification's details and generate a uspto search for it.
- Check out this page of patents I've come across without cpcs.
The USPTO was supposed to assign cpcs to all utility patent however they
missed a few. The uspto makes available a bulk file of cpcs for utility patents as well as a list of withdrawn patents. It's a relatively easy programming
task to find the
9,615 utility patents not in the bulk cpc file that weren't withdrawn patents.
- No one believes me, but I found that over 50% of US Plant Patents have cpc assignments.
Also, as far as I know, there is no bulk source for this data. The
bulk cpc data file that is available only contains assignments for utility patents.
Bulk CPC assignments for reissued patents apparently aren't available either.
- I just loaded 2020.08 which replaced 2019.02 here on my site (I missed a few updates in between). In comparing the plant cpcs just mentioned against 2020.08,
I see plant patents with cpc assignments that are no longer valid (the assigned cpc no longer exists in 2020.08). There could be more orphaned cpc assignments,
these were found by comparing the plant cpc assignments I have on hand. The orphaned classifications would be easier to find if only, say it with me, there
was a bulk source of cpc assignments for non utility patents.
- Add cpc-based searches to your browser's tool bar!
Then when you are viewing a page with a cpc classification highlight it and then press
one of the bookmarklets in your tool bar to see corresponding applications or patents.
Try it out here. Highlight the A61K 35/65 and press either bookmarket in your toolbar
|A61K 35/65||. .
||Amphibians, e.g. toads, frogs, salamanders or newts|
Note that the highlighting can be done while viewing a
cpc scheme page or
an ordinary one like this one!
Important note: The buttons would break (stop working) if
the uspto changes or replaces patft and appft so no warranty is expressed or implied!
Windows: One-time instructions to load these searches to your tool bar
Hover over each of these links. Hold down the left mouse button
and drag (while still holding down left mouse button) each link to your browsers tool bar (then release the left mouse button):
Here's how the bookmarklets look in firefox
Note that the links need to be dragged individually to your tool bar. This is a one time
iPad: One time instructions for a Safari tool bar
It's slightly more work on an iPad but is possible!
There is some one time setup:
You'll need to enable a tool bar in Safari.
Go to "Settings" and tap on "Safari." Set Show Favorites Bar to "ON."
Then just repeat this for each bookmark:
Repeat for cpc patents. This
youtube video makes it look easy!
- Create a bookmark - name it cpc apps and set the location to Favorites