After brainstorming keywords related to your invention and finding a list of relevant classes and subclasses, search the United States Patent and Trademark Office databases or a third party patent document database (e.g., freepatentsonline.com) for relevant patent documents.
Limitations on search
Upon the filing of a patent application, the patent application remains secret for a period of 18 months by default. The publication may be expedited by filing a request for early publication. Conversely, a non-publication request may be filed which prevents publication of the patent application until and if the patent application matures into a patent. These non-public patent application cannot be uncovered but is still considered to be prior art to the invention. Hence, every patent search has limitations.
Issued patent and published patent application databases
The USPTO has one database for issued patents and another database for published patent applications. The reason is that not all published patent applications eventually mature into a patent. Additionally, not all patents were published before issuance. For example, design patents are never published until they issue as a patent. Additionally, non-publication requests prevent the publication of the patent application until the patent application matures into a patent. Hence, both databases must be searched to conduct a proper patent search.
Go to http://patft.uspto.gov/, click on Search under PatFT: Patents. (see below). In Term 1 enter the class/subclass in the following format “XX/XXX”. In Field 1, select Current US Classification. In Term 2, enter your keywords. Click search.
Review the titles and click through to relevant titles to read the abstract. Do not read through the entire reference. Just keep track of the relevant references which will be downloaded later and reviewed more thoroughly.
Go through this process with each keyword and class/subclass combination. Manually filter out the relevant references. The list of references will be much shorter than a search conducted without specifying a class/subclass. Moreover, the references should be more on point than a search conducted without specifying the class/subclass.
Repeat the keyword search process for the published patent application database. Go to http://patft.uspto.gov/ and click Search under AppFT: Applications. Perform the keyword and class/subclass search in this database. Keep track of relevant references.
Review the uncovered references and check its class and subclass to see if you can find other relevant classes and subclasses for your invention.
Patent searching is an iterative process
As you read through the references, you will develop additional search terms and additional classes and subclasses, repeat the search until you have searched all of the keywords within the relevant classes and subclasses.
Other related blog posts:
1. Overview: How to conduct a DIY patent search
2. Basics of a DIY Patent Search
3. Brainstorming keywords for the DIY patent search
4. Finding the right class and subclass for the DIY patent search
5. Search databases for both the issued patents and published patent applications for your DIY patent search
I invite you to contact me with your patent questions at (949) 433-0900 or [email protected]. Please feel free to forward this article to your friends. As an Orange County Patent Lawyer, I serve Orange County, Irvine, Los Angeles, San Diego, and surrounding cities.