Second, whether Party C can provide evidence (such as purchase invoices, etc.). ) said that he did not know and legally obtained the product, and he could cooperate with the investigation of the source, and he would be exempted from compensation. According to Article 70, anyone who uses, promises to sell or sells an infringing patented product for the purpose of production and operation without knowing that the product was manufactured or sold without the permission of the patentee shall not be liable for compensation.