MyPatent.co.za

(Extract from MyPatent's Patent e-Book)

Patent rights are defined by the claims. Any product that includes the features described in a patent claim infringes that patent. The existence of additional features is irrelevant to the question of infringement. However, it is possible that the inventor of these additional features may obtain patent protection for such features, if new.

For example, the first person (inventor X) to invent a pencil, could have obtained a 20 year monopoly for the following principle:

Assuming that another person (inventor Y) invented the standard pen, he would have to pay a royalty to inventor X to make the pen, but would also be entitled to patent protection for the following principle:

Now assuming that inventor Z creates a click-type pen, he would have to pay royalties to both inventor X and inventor Y, but would be able to secure patent proctection for the following principle: