Overview of US Classification and Sub-classifications
It is also important to realize that over time classifications and sub-classifications are created, deleted or merged. The result of this is that sometimes scores of patents have their classification changed. Although all similar types of patents should have similar classifications and be grouped together, they may not be especially true for emerging technologies that overtime may require a new class or subclass. Everything is classified by an examiner, so any given patents may not necessarily be where you would think it should be. The USPTO Manual of Classification (MOC) includes a number of ways to search within the classes and subclasses. To help visualize the relationships between classes and subclasses, we created a USPTO Classification Tree on the ArchPatent site that lets you drill down for each class into its associated subclasses. This type of resource can greatly simplify classification research.
How US Classifications Fit Within the USPTO Seven Step Prior Art Search Strategy?
1. Brainstorm keywords related to the purpose, use and composition of the invention.
2. Look up the words in the Index to the U.S. Patent Classification to find potential class/subclasses
3. Verify the relevancy of the class/subclasses by using the Classification Schedule in the Manual of Classification.
4. Read the Classification Definitions to verify the scope of the subclasses and note “see also” references.
Access Full Text
5. Search the Issued Patents and the Published Applications databases by “Current US Classification” and access full-text patents and published applications.
Review and References
6. Review the claims, specifications and drawings of documents retrieved for relevancy.
7. Check all references and note the “U.S. Cl.” and “Field of Search” areas for additional class/subclasses to search.
How to Use the US Patent Classifications to Enhance Key Word Searching to Achieve Higher Quality Prior Art Search Results?
The first step is the same as the USPTO’s Seven Steps Prior Art Search Strategy. Start by brainstorming “keywords related to the purpose, use and composition of the invention.” Let’s say you are interested in searching for patents related to the design and manufacture of golf ball coverings. We would start by searching for “golf balls”. At the time of this writing, these keywords will return 21141 results on ArchPatent. Looking at the filter rail on the left side of the results page, you will see a listing of classifications by name, ordered by most hits within the search results. The first classification listed is “Games Using Tangible Projectiles,” which means that a majority of the results containing the key words “golf balls” fall within this classification. Clicking this link will filter the search results to patents that contain the term “golf balls” and have the classification ”Games Using Tangible Projectiles”.
Filtering Classifications and Sub-classifications by Examiner
As you work through the classification and sub-classification review for each key search term, it may be helpful to also search the results by “Examiner”. Patent Examiners often work at the US Patent Office in a specific area of expertise for many years. This filter allows you to see very Patent Examiner that has reviewed patents and the number of patents they have reviewed.
Filtering Classifications by Most Referenced
Similar to the “Examiner” filter it also is helpful to see what patent is most referenced by other patents within a classification or sub-classification. Similar to a family tree, it is often helpful to see what patents examiners site the most often when granting patents within a classification or sub-classification.