There are two principles to judge patent infringement, one is the principle of universal coverage, and the other is the principle of equivalence, 1. The principle of universal coverage means that all the technical features of your patent right must cover the infringing object involved, none of which is indispensable and none of which will infringe.
2. The principle of equivalence, because of the profoundness of Chinese and the similarity of physical and chemical properties of some features, it is somewhat arbitrary to use the principle of universal coverage completely, so it is introduced. The principle of equivalence means that the technical characteristics of the invention patent are similar to those of the product involved, and the object is regarded as equivalent. For example, if the material recorded in the invention is iron and the product involved is steel, it can be regarded as the principle of equivalence, but the use of the principle of equivalence is gradually restricted. Some experts believe that the principle of equivalence can only be used for technical features in existing technical features.
In addition, there are the principle of estoppel and the principle of gift, which are a few concepts and will not be repeated here. In the practice of judging patent infringement, it is easier to judge the product invention, because the specific structural parts can be disassembled and compared with the technical characteristics of the invention, but it is more difficult to judge the method invention. For example, when recording factors such as air pressure, temperature and reaction time in the invention, it is difficult to determine the specific values of these parameters in the technology involved, and it is also difficult to preserve evidence. At this time, a professional patent agency team is needed to do it. I have been engaged in the patent agency industry for 7 years and have represented cases of patent infringement.
If you really want to study this problem, I recommend you a book, Guide to the Determination of Patent Infringement, published by China National Intellectual Property Administration Law Department. It has a detailed explanation.