Claims in a patent mean clauses that define the extent of protection conferred by that patent. Independent and dependent claims in a patent define the scope of an invention on which protection is sought. Whether an invention is patentable or not, is decided based on whether the claims are novel and inventive. This means that the claims must capture both novelty and inventive step of an invention.
A patent application is granted or rejected primarily based on the claims. Not only from a patent examination‘s perspective, claims are also an important deciding factor while asserting your patent against an external entity that potentially infringes your patent. You may want to check out this article that describes how are claims used in checking patent infringement of a patent.
What are the types of claims in a patent?
What is an independent claim and what is the purpose of dependent claims?
An Independent claim is a standalone claim that captures all the essential features of an invention (or at least an embodiment of the invention). An independent claim defines the minimum detail of the invention (or that embodiment) to stand on its own without requiring features from another claim.
This means that the claimed invention should at least be able to theoretically function using the features in the independent claim without borrowing features from any other claim.
An independent claim can be further supplemented by adding dependent claims that add more features (details) to the features covered in the independent claim. Each dependent claim qualifies the independent claim further by adding more features to it.
Let’s take a simple example to understand independent and dependent claims
Assume that a chair with 4 legs is invented for the first time and is applied for a patent. If the independent claim covers the chair that has 4 legs (essential elements), a dependent claim may specify that the chair is black (not essential but adds more details). Another dependent claim may specify that the chair is made of wood (another detail).
You may have understood by now that for the chair to function, 4 legs may be an essential element. Therefore, it is a part of the independent claim. However, the fact that it is black or is made of wood need not be essential to the functioning of the chair itself. Therefore, these features are covered in the dependent claims.
There is generally no limit on how many claims you can add except for fee constraints. Most of the patent offices globally allow for some free claims (10 free claims in India; 20 free claims in US). However, you have to pay a specified fee beyond that. This is the reason most US patents have up to 20 claims to optimize costs.
You may want to explore some patents using Google patent search or Google patent advanced search. Try to read some actual claims in patents to get a better understanding of this concept. Here is the link to Google patents website.
Hope you liked reading the above article. Do comment if you have any questions or comments!