This tutorial will demonstrate:

  • one method of creating an effective search strategy for a thorough patent search.

Let's get started!

To move forward or back, simply click the arrows at the bottom of this column.

Patent applications are evaluated on whether the inventions are new, useful, and obvious.

To assess these three factors, you need to know what else is out there. You do a patent search to make sure your idea isn’t already covered by another patent.

Important Note: If you were really doing a comprehensive search to determine if your idea is “‘patentable”, you need to search more than just patent literature. For example, you may also want to search international patents, patent applications, scholarly articles, standards, blog posts, public presentations - any public information.

Let's start searching!

Our product will be a dog’s water dish with a heating element, so it doesn’t freeze over in the winter if left outside.

Let's do some brainstorming:

  • Is it just for dogs? Just for pets?
  • Would you only use it for water, or for other liquids?
  • What other ways could you express the concept of supplying a dog with water?

To begin, we'll start with a keyword search in a keyword-friendly database, like this one - Lens.

Type dog water dish into the search bar, then click Submit Search.

type dog water dish in the search bar

Let's narrow down our search to only US patents. This will help us weed out patents in other languages that we may not be able to read.

On the left side of the screen, click on Jurisdictions.

Check the box beside United States of America.

Press the teal button, Refine.

united states of america jurisdiction

Click on the result titled "Auto Pet"

click on the result titled Auto Pet

In the abstract we discover this particular patent is for a water dish that keeps water fresh even when left outside. This is a similar idea to our product.

Abstract description of Auto Pet patent

Scroll down to the classification list toward the bottom.

For this patent search we will be focusing on the CPC code. The CPC is the most up-to-date "classification system" used in the United States and Europe to organize patents.

This patent's CPC is:

  • A01K7/005

patent cpc classification code

Using this CPC, we're going to use the Espacenet database to find out what areas of technology this particular CPC covers.

Click on the following link to be directed to the Espacenet database.


The CPC we found from our Lens search was:

  • A01K7/005


click on A for HUMAN NECESSITIES category

Click on A01 (AGRICULTURE; etc)

Click on A01K (ANIMAL HUSBANDRY; etc)

Notice that

  • A01K1/00 is for housing animals, which isn’t what we want.
  • A01K5/00 is feeding devices, which might work if we want to say our invention could also be used for food.
  • A01K7/00 is watering devices, which seems like the better option for what we're looking for.
notice these different CPC classes

Click on A01K7/00.

Of the subclasses, A01K7/027 is perfect!

  • A01K7/027 - Drinking equipment with water heaters, coolers or means for preventing freezing.

listing of subclasses

From here we're going to take this refined CPC back to the Lens database to find other patents similar to our product.

Click on the following link to be directed back to the Lens database.


Type the CPC code we found in Espacenet, A01K7/027 into the search field.

In the drop-down to the right of the search field, select CPC Classification.

Lens drop-down menu for CPC Classification

Click the teal button, Submit Search.

Now let's refine our results to just United States patents again.

On the left side of the screen, click on Jurisdictions.

Check the box beside United State of America.

Click the teal button, Refine.

Jurisdiction refine to United States of America

You’re now seeing all of the search results that are US patents and patent applications in class A01K7/27. Each one represents a unique invention for delivering heated or cooled water to animals, even though they all describe those ideas using different terms.

Important Note: You can use Lens’ analysis view (the little bar graph icon in the upper right corner) to get a chart showing all of the CPC classes present in your search results.

Lens bar graph icon in upper right corner

You can see that A01K7/025 is the second-most popular class in our search. This would be something to look into later on in your search.

CPC Classifications second CPC option

If you have trouble using the Lens or Espacenet database, Purdue Libraries has many ways to assist you to make sure you find what you need. Ask a Librarian!

Or contact the Engineering Library at enginlib@purdue.edu. We will be happy to assist you in finding the information you need.

Now you know how to perform a basic patent search using Lens and Espacenet.

Thank you for using this tutorial.