SEOUL (WSJ) -- Samsung Electronics Co. filed complaints against Sharp Corp., responding to its Japan rival's patent-infringement lawsuits on liquid-crystal displays.

The move ramps up the legal battle between two electronics companies that are among the world's biggest manufacturers of LCD televisions.
In the July-September period, Samsung was No. 1 in global market share by revenue, while Sharp was No. 3, according to data vendor Display Search.
In mid-December, Sharp accelerated its legal offensive against Samsung. It filed a lawsuit in a Seoul court alleging LCD-patent infringements.
Sharp also filed a lawsuit against the company over a different set of LCD patents in Texas in August.
Patent lawsuits are common in the industry. Electronics manufacturers often devote large sums to quickly rolling out similar products. The cases can stretch on for years before they are resolved.
James Chung, a Samsung spokesman, said the company had filed countersuits against Sharp in Delaware and Texas in the U.S. and in Tokyo.
Samsung has also asked the U.S. International Trade Commission to investigate the case.
The company, in a statement, alleged that Sharp and its U.S. subsidiaries engaged in unfair trade by importing LCD products that infringed on four patents owned by Samsung.
The South Korean company requested that the commission initiate an investigation and issue an order barring imports of Sharp's LCD products that infringed Samsung's patents.
In a separate statement, Samsung also said it filed suit seeking a preliminary injunction against Sharp in the Tokyo District Court.
The suit alleges LCD TVs manufactured and sold by Sharp in Japan infringed on two LCD-related Japanese patents owned by Samsung.
Samsung said it requested that the court prohibit the manufacturing and sale of the infringing products in Japan.
""Samsung has and will continue to vigorously protect itself against the infringement and unauthorized use of its intellectual property,"" Samsung said in a statement.
A Sharp spokesman said the company will take appropriate legal countermeasures by considering the details of the complaint.