1. Invalid patents refer to patents that have not been approved in the end, have been authorized but have been declared invalid, or have lost patent rights due to various reasons stipulated in the law and are no longer protected by patent laws. Expired patents become a free public resource due to their expiration, and naturally become "public knowledge and public use". 2. The reasons for patent invalidation are: 1. The patent exceeds the prescribed period of patent law: The protection period of invention patents in my country is 20 years, and the protection period of utility models and designs is 10 years. After the expiration of its effective protection period, a patent no longer enjoys the exclusive rights granted by the Patent Law, falls into a publicly known technical field, and can be used by the public free of charge. It has been more than 20 years since the Patent Law was implemented in 1985. The patents applied for in the early stages have basically expired and become invalid patents. 2. The patentee terminates the patent right early. The main reasons for early termination by the patentee include: discovering that the original invention is not advanced enough, failing to implement it after applying for the patent, and replacing it with better technology, thus losing the meaning of existence and being forced to give up the patent right and becoming an expired patent; the applied for patent itself lacks Market development value, so there is no need to retain the patent; it is difficult to implement the patent: it cannot be implemented by itself, nor can it be transferred. It cannot generate benefits and must pay patent fees every year. The burden is too heavy, so the patent rights are given up. Methods of voluntary abandonment include failure to pay annual fees as required; the patentee gives up its patent rights in a written statement. Patent annual fee, also known as patent maintenance fee, refers to the fee paid by the patentee to the patent authority starting from the year when the patent right is granted to maintain the effectiveness of the patent right. This is the legal obligation of the patentee. The right to waive is a right enjoyed by the patentee in accordance with the law. The patented technology has since become an expired patent and entered the public domain, and anyone can use it freely and free of charge. Generally speaking, the technology for which the patentee has given up its patent rights in a written statement is a technology that is about to be replaced or eliminated and does not have much development and utilization value. 3. The patent applicant gives up after submitting the application but before obtaining authorization. The main circumstances in which a patent applicant gives up the patent right include: (1) For utility models and designs, when the Patent Office makes a decision to grant a patent right, the patent applicant fails to pay the patent certificate fee and annual fee and is unable to obtain the patent right; ( 2) For invention patents, patent rights cannot be obtained without submitting for substantive examination. Strictly speaking, this situation is a patent application, because it has never obtained a patent right. To be precise, it cannot be called an invalid patent, but can only be called an "invalid patent application." However, the content of the invention has been recorded in the patent application documents distributed after the filing date and has become known to the public. 4. Patents declared invalid by others. Article 45 of the Patent Law stipulates that from the date when the Patent Administration Department of the State Council announces the grant of a patent right, any unit or individual that believes that the grant of the patent right does not comply with the relevant provisions of this Law may request the Patent Reexamination Board to declare the patent right invalid. . Since patent declarations can be divided into full invalidity and partial invalidity, invalid patents can also be divided into full invalidity and partial invalidity.