Legal analysis: 1, patent invalid 2, the defense of equivalent right (1) adopts the principle of prohibiting regret to defend; (2) the defense of freely known technology; 3. The case that is not legally regarded as patent infringement (1) enjoys the priority of use; (2) The patent right has been exhausted; (3) Temporary transit protection; (4) unproductive and commercial use; 4. The defense of legal use right (1) is based on the entrusted development contract (2) is based on the cooperative development contract (3) is based on the license contract (4) is based on the patent right. Other forms of defense (1) defense against others' right to use when the patent right is lost and restored: (2) (4) universally applicable defense principle.
Legal basis: According to Article 67 of the Patent Law of People's Republic of China (PRC), in a patent infringement dispute, if the accused infringer has evidence to prove that the technology or design he implemented belongs to the existing technology or design, it does not constitute patent infringement. Article 77 of the Patent Law of People's Republic of China (PRC) stipulates that anyone who uses, promises to sell or sells an infringing patented product for the purpose of production and operation without knowing that it was manufactured and sold without the permission of the patentee shall not be liable for compensation.