Sony Corp. has offered LG Electronics an New Year gift: a patent infringement lawsuit. But it is only one of several as companies try to use patents to protect market share or force others to pay for use of technology.

Sony Corp. has filed a complaint with the U.S. International Trade Commission as well as a lawsuit in the U.S. District Court for the Central District of California. It says its patents related to mobile phones, which are sold by Sony Ericsson, Samsung and Nokia were infringed by Korean electronics maker LG Electronics.

The patent infringement  complaint covers 10 LG smartphones which includes Encore, LG Accolade, Neon, Quantum and Rumor Touch. Bloomberg cited other names in the list such as Xenon, Lotus Elite and Remaq. The patents are for technologies related to microphones, signal transfer, and contacts display. Sony filed the complaint with U.S. International Trade Commission seeking to bar LG from importing phones to the U.S.

The lawsuit follows another high-profile case, a revised patent lawsuit filed by Microsoft co-founder Paul Allen on Dec. 28 against Google, Apple, eBay, Facebook, Netflix, AOL, Yahoo!, Office Depot, OfficeMax and Staples. Also on Dec. 23, Motorola extended its patent lawsuit against Microsoft to include two new patents which cover the Kinect motion controller technology while Microsoft in response added seven new patents to its claims which include Motorola's DVR set top box technology along with Android.

However, while Sony fired a salvo of patents against LG, its own joint venture Sony Ericsson was in the firing line when SmartPhone Technologies LLC filed a patent suit against Sony Ericsson, Excedea, Nokia, HTC and Kyocera in October. SmartPhone LLC had also sued Apple, AT&T, LG, Motorola and RIM in March.

Also in April a class-action suit was filed against Sony by a PlayStation 3 owner accusing Sony of downgrading millions of its devices by expunging its ability to run Linux, fallout of its controversial decision to disable support for other operating systems on older PlayStation3 consoles.

Sony was also sued with other six PC makers by Solid Oak Software in January, for stealing code for use in their products. Solid Oak was seeking $2.2 billion in damages.

As the smartphone market continues to expand, a clear leader has failed to emerge. With multiple platforms like iOS, Android, WP7, WebOS, Symbian and MeeGo vying for space, the intense fight for market share has resulted in companies resorting to acquiring patents as a preemptive tool or charging each other with patent lawsuits to protect their turf. Also in the game are patent trolls that are seeking to milk the growing smartphone industry.