It is known that the invention patent "MP3 Player" was applied by Pei Yongzhi in March, 2000, and granted by the State Intellectual Property Office (SIPO) in Feburary, 2005. In October, 2010, Pei Yongzhi filed a lawsuit against Sony Company at Beijing No.2 Intermediate People's Court, claiming the MP3 Player (NWZ-W252/BM) Sony Company manufactured and distribution infringed his invention patent and requiring the court to order Sony Company to stop manufacturing and distribution.

Sony Company then filed a request for invalidation of the patent. In November, 2011, the patent reexamination board of SIPO made No. 17613 decision on the request, declaring the invalidation of the claim 1, 2, 7, 8, 9 and validation of the claim 3, 4, 5, 6, 10. Dissatisfied with the decision, Pei Yongzhi withdrew its civil lawsuit and lodged a complaint against the patent reexamination board at Beijing No.1 Intermediate People's Court, requiring the court withdraw the decision. However, his claim was rejected by the court. As Pei Yongzhi didn't made an appeal, the ruling took effect. In Feburary, 2013, Pei Yongzhi, on the basis of claim 6, filed another lawsuit against Sony Company at Beijing No.2 Intermediate People's Court on the ground of patent infringement.

Sony Company argued that the products didn't fall within the protected scope of Pei Yongzhi's patent right. What is more, it claimed that the products were manufactured in Malaysia and it was merely sold them. Based on this, Sony Company required the court to reject Pei Yongzhi's claim.

Beijing No.2 Intermediate People's Court heard the case and held that the technical feature of Sony Company's player was as same as that of E and F of claim 6. Hence, the court ruled the products have fell within the protected scope of claim 6 and ordered Sony Company immediately stopped the infringement.