Two industrial manufacturers, Guardian Industries and Honeywell International, have sued dozens of companies in the global PC and video display businesses in a U.S. federal court to try to recoup royalties on liquid-crystal technology.

　　Guardian, a maker of industrial glass, and Honeywell, known for making weapons systems, assert in filings in the U.S. District Court in Delaware that their intellectual property for liquid crystal displays, used in notebook computers, TVs, and cellular phones, have been infringed.

　　Taiwan and South Korea are the two primary centers of LCD production, which is growing rapidly as demand for LCD-based televisions rises. The lawsuits target the LCD industry directly, but also assert claims against companies that incorporate LCDs into final electronic products.

　　Jin Kim, the director LCD market research for research firm DisplaySearch, said the LCD business largely avoided patent lawsuits through its earlier years, but has attracted litigants as the business blossomed into a $40 billion market.

　　"When you get big, and the industry becomes somewhat popular, there's always lawyers or companies willing to suddenly develop a way to be a part of it," he said.

　　Privately held Guardian, based in Auburn Hills, Mich., is one of the world's largest makers of fabricated glass products, and its mainstay is automotive and industrial glass.

　　The company asserts rights on four patents related to the design and manufacturing of LCD displays. The patents cover technologies that affect the viewing zone and high-contrast features of LCD displays, according to court papers.

　　In January, the company sued 14 companies, including PC makers Dell, Gateway and Acer; Taiwanese computer gear makers BenQ and Lite-On Technology; and Taiwan-based LCD manufacturers AU Optronics, Chunghwa Picture Tubes and Quanta Display. The defendants or their attorneys did not return calls for comment, although Dell filed court papers last week denying infringement and asking a judge to rule in its favor.

　　Honeywell's case is pending in the same court. The company said late last year that it was targeting 34 electronics companies, including Apple Computer, phone maker Sony Ericsson Mobile Communications, and Japanese computer maker Fujitsu. It also sued Finland's Nokia, the world's largest cellular phone maker.

　　Honeywell claims that the companies infringed patented technology covering image brightness and interference reduction on LCD screens. Ron Crotty, a spokesman for Honeywell in Phoenix, said the company developed the technologies originally for aerospace applications but found them appearing in consumer products.

　　"The issue is they are infringing our patents, and we aggressively protect our intellectual property," Crotty said.

　　Honeywell, which filed the suit last October, has pointed to three large LCD makers, LG.Philips LCD, Samsung Electronics, and Japan's NEC Electronics that it said have agreed to sign license agreements for the technology. Representatives of the Honeywell defendants could not immediately be reached or did not return calls for comment.

　　Jin, the DisplaySearch analyst, said LCD makers have been hesitant to resort to lawsuits against rivals, in part because there are so many patents covering the technology that any plaintiff could easily be countersued. Honeywell and Guardian, neither known for LCD production, could be shielded from countersuits, he said, since they don't deal directly in the market.

　　"There is kind of a symbiotic relationship among all the LCD suppliers," he said. "That's why it has traditionally been not much of a factor."