Extension of patent protection: Equivalent patent infringement applies if the infringing object does not literally fall under the patent claim but incorporates the essential invention.

Prerequisite: A feature of the claim is not literally fulfilled. Instead, a functionally equivalent, obvious, and equivalent substitute is used.

Equivalent effect: The infringing object must achieve the same technical effect as the patented invention.

Obvious modification: The modification of the feature must not be surprising to a person skilled in the art, but must be considered an obvious technical modification.

Equivalence: The modified object must be regarded by a person skilled in the art as equivalent to the patented solution, i.e., there must be no indication in the patent specification itself that the modified object is not part of the invention.

The state of the art limits protection: What was known or obvious on the filing date of the patent cannot be protected by equivalence. (Formstein objection)