Legal analysis: 1. Documentary evidence: usually a notarial certificate. After the patentee discovers the infringement through market research, he will usually apply to the notary office to review the process of purchasing the infringing product and the purchased goods. Notarize the infringing product or conduct an investigation and notarization of the infringing site (such as a promise to sell) or the installation site of the infringing product, and obtain a notarial certificate to prove the defendant's infringement. During the process of notarization and evidence collection, it is best for the patentee to take the initiative to ask the seller for the product brochure, the business card of the person selling the infringing product, the purchase invoice or receipt, to further clarify who the manufacturer and seller of the product are, and who has the patent right. A person may request the notary office to explain the source and authenticity of the aforementioned information and record it in the notarial certificate. In addition, by the way, when choosing a notary office, you should also consider it. For example, in a provincial capital city, you can choose a provincial notary office instead of a district notary office. On the one hand, the district notary office may lack experience, and on the other hand, the district notary office may lack experience. They use various excuses for local protection or fear of retaliation. The author once encountered such a problem when applying for notarization in two cities, Tianjin and Zhengzhou. The district notary office refused to accept the application. However, the Tianjin Notary Office and the Henan Provincial Notary Office accepted the notarization application in a timely manner and efficiently processed it. Evidence preservation notarization was made. 2. Physical evidence: Infringing products purchased by the patentee from the market. Purchased infringing products should be sealed by a notary and photographed. Before submitting it to the court, the plaintiff should ensure that the seal is intact, otherwise the defendant may raise objections during cross-examination and deny recognition of the infringing product.

Legal basis: "The People's Republic of China and the Civil Code"

Article 120 If civil rights and interests are infringed, the infringed party has the right to request the infringer to bear tort liability .

Article 183: If one is harmed due to protecting the civil rights and interests of others, the infringer shall bear civil liability, and the beneficiary may provide appropriate compensation. If there is no infringer, the infringer has escaped or is unable to bear civil liability, and the victim requests compensation, the beneficiary shall provide appropriate compensation.

Article 1,167 If an infringement endangers the personal or property safety of others, the infringed party has the right to request the infringer to bear tort liability such as ceasing the infringement, removing obstacles, and eliminating danger.

Article 1,168 If two or more persons jointly commit infringement and cause damage to others, they shall bear joint and several liability.