等同理论，又称等同侵权或依据等同理论的侵权，是专利侵权认定中的一个核心问题。美国的等同理论是由一系列判例构成的。在１９９７年３月的希尔顿化学公司案的判决中，美国最高法院再次阐述了等同理论中的一些基本原则。如：等同是指被控侵权产品或方法中的某一技术要素与专利权利要求中的某一权项的等同；禁止反悔是指专利权人不得将专利审查中为区别“现有技术”而放弃的技术要素重新纳入受保护的范围；判定等同的时间点是侵权的时间；等同理论与侵权者的主观状态无关；等等。本文还以该案为基础，深入探讨了等同理论与禁止反悔理论、非显而易见性理论的关系，指出这三个理论在具体适用上具有高度的一致性。一方面，它们对于专利权人提供了不同时间点上的连续保护，另一方面又保障了公众在不侵犯他人专利权的前提下自由从事发明创造和使用公有技术的权利 Equivalence theory, also known as infringement equivalent to infringement or based on the same theory, is a core issue in the determination of patent infringement. The American equivalent theory is made up of a series of precedents. In a March 1997 case of the Hilton Chemical Company, the Supreme Court of the United States again set out some of the basic principles of equivalence theory. Such as: Equivalent is accused of infringing products or methods of a technical element and patent claims in a certain right of the equivalent; no estoppel means that the patentee may not be in the patent examination for the distinction between “prior art” and Abandoned technical elements are re-included in the protected area; judgment equivalent time is the time of infringement; equivalence theory has nothing to do with the infringer’s subjective state; Based on this case, this article also discusses in depth the relationship between the theory of equivalence and the theory of estoppel, the theory of non-obviousness, and points out that the three theories are highly consistent in their concrete application. On the one hand, they provide patentees with continuous protection at different points in time, and on the other hand they guarantee the public the right to freely engage in the invention, creation and use of public technology without infringing the patent rights of others