May 9 (NBD) -- Shortly after Xiaomi Corp (Xiaomi) filed for Hong Kong IPO, China's smartphone supplier Coolpad Group Ltd (Coolpad) announced it has filed a lawsuit against Xiaomi over patent issues.

According to a filing submitted to the Hong Kong Exchanges and Clearing Limited (HKEX) last Friday, Coolpad has requested the Shenzhen Intermediate People's Court to ban Xiaomi from selling mobile products Xiaomi Redmi Note 4X, Xiaomi Mi 6, Xiaomi Mi Max 2, Xiaomi Mi Note 3, and Xiaomi Mi 5X.

The relevant person in charge at Coolpad said to NBD that the company will release the details about the lawsuit later this Friday, while Xiaomi declined to comment.

Coolpad sued Xiaomi in January this year claiming the latter violates three of its patents related to the software, and the case was heard in late April, but no ruling was announced.

Earlier this month, Xiaomi filed for Hong Kong IPO, which is the first IPO application to the HKEX after it started to accept the listing of companies with WVR structures on April 30 this year.

Although the sales volume of the Redmi Note 4X, Xiaomi Mi 6, Xiaomi Mi Max 2, Xiaomi Mi Note 3, and Xiaomi Mi 5X isn't disclosed in the prospectus of Xiaomi, these five smartphone models undoubtedly are bestsellers of the company. The prospectus introduces the above-mentioned five phones as the company's core independently-developed products and mostly target the high- and medium-end segments.

Li Junhui, a research fellow of the Center for Intellectual Property Studies at China University of Political Science and Law, pointed out since the court hasn't yet determined whether Xiaomi indeed infringes Coolpad's patents, it remains uncertain whether Coolpad's request to cease the sale of the five Xiaomi products would be supported by the court.

Zhao Zhanling, a lawyer, shared the same opinion, saying that it's hard to tell whether the court would rule in favor of Coolpad. Generally speaking, a sales ban will be issued if the court finds the accused's behaviors are very likely to constitute infringement and the plaintiff will suffer further loss if no action is taken, explained Zhao.

As competition among smartphone makers intensifies, the patent litigation in this sector is happening more frequently. Li held that besides Xiaomi, other phone makers also face similar worries at different levels.

It's noticed that Xiaomi places increasing importance on R&D and patents. According to the prospectus, as of March 31, 2018, Xiaomi employed 5,515 R&D personnel. The company spent 1.5 billion yuan (235.4 million U.S. dollars) on R&D in 2015, 2.1 billion yuan (329.5 million U.S. dollars) in 2016, and 3.2 billion yuan (502.1 million U.S. dollars) in 2017, with annual expenditure on patent applications standing at 77.9 million yuan (12.2 million U.S. dollars), 171 million yuan (26.8 million U.S. dollars) and 139 million yuan (21.8 million U.S. dollars), respectively, in these three years.

Email: gaohan@nbd.com.cn