Using Patent Databases and Finding Patents

Patent examiners advise searching by patent classification. That is:

• Figure out the subject classification(s) for your area of interest
• Get the list of patents assigned (by the U.S. and other patent offices) to that subject classification
• Examine the patents in the list --- for their details and for cited literature.

Classification searching may be done in all patent databases; we will use Espacenet.

---

Classification searching starts with a system of classification.  The Cooperative Patent Classification (CPC) System  is the patent classification system used in Europe, the U.S., and some other countries.  In classification searching, it is your job to match your area of interest to the right subject classification(s).  The two usual approaches are to: 

1. Search by keyword to find patents of interest.  Find the classifications assigned to those patents.
2. Go directly to the classification tables to figure out the best codes.

Here is the search interface to the CPC classification tables:

 

At the CPC tables you may:

• Browse the tables 
• Search by keyword or, if you have it, by classification to find a location within the classification scheme.

 

1. For example, we can search "hair brush" to find where that area of invention fits in the CPC:

• "Hair brush" finds a quick match but the usual advice is to try various term related to your interest
• The language of patents is not always obvious.  Don't expect to find trade names.

 

2. Looks as though we will want to consider the broad category of A46B 2200/00:

• Click on the classification to expand the CPC scheme for that section
• Ask yourself if this seems like the correct area for hair brushes
• Look for notes pointing to other classes or giving clarification
• Notice the dot (•) structure showing a hierarchical arrangement of the headings.

 

 

3. To see the patents assigned to the classification:

• Select the classification of interest with a click in its box.
• To fill in the search box on the right.

 

4. Some notes:

• /low selects the classification AND the classifications under it in the hierarchy --- sometimes there are no classifications under the one selected
• to select only one classification when the system forces more, use the "Advanced Search" option --- selecting a "classification search" with an "=" operator.

 

5. Click on  to see the list of patent documents assigned to the classification.

 

 

 

6. "Finding the patents" for this classification gives a large set of results --- more than 1,600 patents and applications.  Fortunately, you won't have to look at all of them right now.

• First, you will do some evaluation work.  Do these patents match your area of interest?  
  • Click on the title of the patent for more information.
  • You may check the classifications, look at the drawings, or examine the full document.

​

 

• It may be necessary to go back to the CPC Tables and reconsider what is the right classification.
• When you see a patent of particular interest, note:
  • all the assigned classification codes
  • so that you can investigate those additional classifications.

 

7. When you have decided on the right classifications for your area of interest:

• For thorough searching, the U.S. patent examiners recommend looking at each patent in each of the classifications.  You may decide to do a less comprehensive search by combining classifications or narrowing the results in another way.
  • "Looking" means at least:
    • Checking first-page information to get a sense of the invention.
    • Checking the claims.

Also, the U.S. Patent and Trademark Office (USPTO) pages offer the Multi-Step U.S. Patent Search Strategy for classification searching.  The approach illustrates use in the U.S. patent databases but, once understood, the technique can be used in other patent databases.

Classification Resources from the USPTO offer help in understanding currently used classification schemes and the (mostly) previously used U.S.Patent Classification.