Classification Searching Overview

When patents are examined in patent offices around the world, a special group of patent classifiers, as well as the examiners, classify the patents.  They do a remarkable job in my opinion.  Classification searching is the best, and really only, way to do a credible job of isolating technologies for patent landscapes and comparing two portfolios without doing extensive manual classification yourself.  I'll just say it, a lot of patent search professionals don't trust, don't like, and rarely use classification searching.  While I think it is a mistake, I understand it.  Especially as classification analysis is not handled well in other tools that I have seen.

Clearly, all patents are not classified perfectly.  Some patents aren't classified at all and are just dumped into catch-all classes, such as the 1/1 class in the US Classification system.  But with the vagaries of human language, it is your best bet.

AcclaimIP handles classification in very powerful ways, as will be explained in this and other chapters of the Help Manual.

3 Global Classification Systems

There are really three major patent classification systems used around the globe:

  1. Cooperative Patent Classification System (CPC)
  2. International Patent Classification System (IPC)
  3. Japanese Classification System (F-Terms)

AcclaimIP provides tools for querying patents via all three systems.  AcclaimIP also provides tools for searching the older US Classification System (USPC). 

All patent collections in AcclaimIP can be searched using the IPC system.  The limitation is that there are fewer subdivisions in IPC compared to the other classification systems such as USPC and CPC.

The USPC applies only to US patents and applications, but the CPC has replaced the USPC.  However, there may still be patents (e.g., older patents) that are only classified under the USPC.  Therefore, AcclaimIP still allows you to search using this classification system.  Just know that there are limitations, and you will miss many newer patents if you use only this classification system.

The CPC is the Cooperative Patent Classification system and is a joint effort by the US and European Patent offices in order to both share the costs of maintaining the classification system and to better harmonize the global patent system.  The CPC is based on the older European Classification System (ECLA).  The ECLA system is dead, and we don't support the ECLA in our user interface by providing filters and facets.  However, you can still query it in AcclaimIP by using advanced syntax and the ECLA field code.  

The IPC is basically a simplified (fewer subdivisions) version of the CPC.  Really, though, the CPC is based on the ECLA, which was based on the IPC.  Some smaller patenting jurisdictions may continue to use the IPC system.

 The F-Terms (and FI, meaning File forming term and File Index, respectively) is a classification system specific to the Japanese Patent Office. If you are familiar with this system, it can be even more precise than IPC and CPC (F-term consists of approximately 360,000 entries).

Hierarchical Nature of the Patent Classification Systems

Hierarchical Nature of the Patent Classification Systems

All of the systems are hierarchical.  That is, there are classes, sub-classes, sub-sub classes, etc., up to a depth required to suitably classify the subject matter.  Some of the hierarchies can be up to 16 levels deep!

Patents are classified at all tiers of the classification hierarchy, which complicates matters.

All children subclasses share the attributes of their parent subclasses, but have additional limitations associated with the child class.  Let's look at CPC class H04W12/06, which is 5 tiers deep in its hierarchy.

H:                    ELECTRICITY  --  Broad topic

H04:                ELECTRIC COMMUNICATION TECHNIQUE  --  Telephones, basically

H04W:             WIRELESS COMMUNICATING SYSTEM  --  Mobile Phones, basically

H04W12/00:    Security Arrangements

H04W12/06:    Authentication  --  The one dot sub-class

It often helps to read class hierarchies backwards for a better comprehension of the subject matter.  As the figure above shows, you can view the full class hierarchy tree by hovering your mouse over the class name.  Note that if you right-click on the pop-up box with the class definitions, the box will lock in place until you click the X.

Once you have checked the box next to the class or classes that you want, click Update Search.


Once you have restricted your search to the particular class you want, all of the patents in your search will be in that class (although, as shown on the Biblio tab in this example, patents may not be only in that one class, but may be listed in multiple classes).  Here you can also hover over the various classes shown in order to get the heirarchy and class titles.  You can then right-click to lock the pop-up window here, too.  If the pop-up window has a blue linked CPC class (not just the black text), you can click on those blue linked individual Class Code and run a matrix based on that particular class.

You could, of course, query these classes using the Search field.  If you wanted to do this for the example above, your search query would be CPC:H04W12/06.  However, this would require you to be familiar with the classes that you want to search for.  Instead, AcclaimIP allows you an easier method to drill down into the classes and heirarchies through using the facets found in the Refine Search panel.



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