It is easy to understand that a patent must be practical in one of the three aspects, that is, the technical method must be useful to the society before it can pass the patent application. The purpose of patented products is to promote social progress. Do not rule out being used. In other words, for example, A owns a patented technology, and B finds that there are many disadvantages in this technology or method during its use, and B puts forward many improvement schemes. At this time, B can apply for a patent with its own improved scheme. That is, a technology +b technology = new technology (this is actually the definition of utility model in some cases)