Principle of judging patent infringement: To judge whether an act constitutes an invention or utility model patent infringement depends on whether the object pointed by the act belongs to the protection scope of the invention or utility model patent. If the technical scheme implemented by the alleged infringement contains all the necessary technical features expressed in one or several claims of the invention or utility model patent, then the act belongs to the protection scope of the invention or utility model patent, that is, it constitutes an invention or utility model patent infringement, which is the principle of universal application.