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How to Do a Patent Search on The US Patent Website

One item that the US Patent Office emphasizes when you are doing a patent search is that you should not limit yourself to just keyword searches. The reasons for this is that wording in patents can be vague. Some patents may use obsolete names or terms. Words can also have different meanings in different fields. Another problem is that your keyword search may fail to find patents using synonyms of your keywords.

In the end they recommend that you conduct a search by classification. In the US Patent Office’s classification system the broader class number is listed first, followed by a slash and then a second number that indicates a subclass within the class. For example 002/67 represents the broad class 2 for apparel and subclass 67 for bathing suits.

The following are highlights of the strategy that the US Patent Office recommends for doing a patent search:
1. Brainstorm keywords related to the purpose, use and composition of the invention.

2. Do a keyword patent search to find potential class/subclasses.

Once you have a list of patents, search the titles and find any relevant patents. Open up each patent document and note the US class on the top right of the top of the page under the list of the inventors. You can use the button below to go to the US Patent Office website to do a keyword patent search.

3. Verify that the class and subclasses found in step 2 would be applicable for your invention.

You can use the button below to go to the US Patent Office website page that lists patent classes. Click on the “Go” button in front of each patent class to search for applicable subclasses.

4. Another way to determine the patent class of your invention is to search the alphabetical list of patent classes.

You can use the button below to go to the US Patent Office website obtain a PDF document that has an alphabetical list of patent classes.

5. The US Patent Office also provides a search tool for looking for the class and subclass by doing an search using the first letter of key words that describe your invention.

You can use the button below to go to the US Patent Office web page that will allow you to do this type of search.

With this method you click on the first letter of keywords that describe your invention, For example, lets say your invention involves a dental implant abutment. In this case you could click on “I” for Implant.


After scanning down the list you find Implant.  Looking down this list you find Dental AClass 433″ and a ASubclass 173″


After right clicking on the 173 hyperlink you get another list.  Looking down the list you find another subclass 200.1 for “Dental Implant Construction”.


Clicking on “Dental Implant Construction” you get a summary of the Class and Subclasses pertaining to your invention 433/167/201.1 (Dental/Prosthodontics/Dental Implant Construction)


Clicking on the blue “A” that is to the left of “Dental Implant Construction” gives you a list of the relevant patent applications that are at the US patent Office.  Clicking on the red “P” gives you a list of the registered patents that pertain to 433/167/201.1.  Here is an example of a relevant patent that was presented in the list:


When you click on this patent you can read the contents of the registered patent to determine if your idea is still novel. Review the claims, specifications and drawings of the patent documents which are retrieved in order to determine if they are relevant to your invention.   In addition, pay attention to the references listed at the top of each patent.  Investigate these references to further verify the novelty and uniqueness of your invention.  Use the references to learn of any class/subclasses that you may not have included in your patent search.  Below is what was listed in the above-mentioned patent.  Note the hyperlinks to each of the referenced patents.


If you find new Classes and Subclasses in the referenced patents, you can investigate these Classes and Subclasses by using the button below to go to the US Patent Office’s web page to get more information about a particular patent class and subclass.


You can enter a Class to get a list of subclasses pertaining to that class.  On the other hand you can include a subclass to bring you to the part of the list that contains the subclass that was entered.


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