Apple Inc. has filed a complaint against HTC Corp., accusing Asia's second-largest maker of smartphones of infringing on the iPhone and iPad maker's patents. Apple has asked the U.S. International Trade Commission to enjoin the Taiwanese company from importing its phones and Flyer tablets to the U.S.

Apple's iPad has captured more than 80% of the tablet market and its iPhone is currently the single best-selling smartphone in the market. But because a number of manufacturers are using Google Inc.'s Android operating system and the multiple models they are offering, the Android has become the top platform for smartphones.

Apple has accused its rivals of widespread imitation. It has been pursuing complaints against manufacturers of phones based on the open source Android OS.

In the case against HTC, Apple claims that the Taiwanese vendor is infringing five patents related to software architecture and userinterfaces in portable electronic devices, hardware for touch screens and movement sensors.

Apple last week filed a complaint with the ITC, also seeking to block U.S. sales for Samsung smartphones and tablets. "The Galaxy S line of mobile phones has been designed to look and operate like the iPhone, and it infringes on multiple Apple utility and design patents," Apple said in the complaint.

Apple has previously filed a complaint against Motorola Mobility Holdings Inc., which also uses Android for its phones.

Aside from HTC mobile phones including the Droid Incredible, Wildfire, EVO 4G and Desire, Apple is also setting its sights on HTC's The Flyer. In March, HTC released the Flyer, its first tablet device in the U.S. to rival Apple's iPad and Samsung's Galaxy Tab. The Flyer has a 7-inch screen, 1.5 GHz processor, and uses Android. HTC's tablet upgrade, the EVO View 4G, which was released in May, was not included in the ITC complaint.

The newest case claims infringement of patents that cover "groundbreaking technologies developed by Apple in conjunction with the development of its innovative iPhone, iPad and iPod touch products," Apple said in the complaint.

HTC is denying the allegations. "HTC is dismayed that Apple has resorted to competition in the courts rather than the marketplace," said Grace Lei, HTC's general counsel. "HTC continues to vehemently deny all of Apple's past and present claims against it and will continue to protect and defend its own intellectual property as it has already done this year."

Last year Apple filed a complaint against HTC, alleging 20 counts of patent infringement. A decision on that suit is expected in August.
HTC last week signed a deal to buy S3 Graphics Co. for $300 million. The maker of video-game graphics chips previously won an infringement ruling at the trade agency against Apple. HTC said the acquisition strengthens HTC's technology leadership and extends its IP portfolio with the addition of 235 patents and the pending applications, including those related to graphics visualization technologies.

In order to protect itself from patent litigation, Google last month negotiated with Nortel Networks to buy the defunct telecommunications firm's 6,000 patents that can be used for smartphones. Google opened the bankruptcy court sanctioned auction with its $900 million offer and would have obtained the patents absent higher and better bids. After a four-day auction, Google lost and a $4.5 billion was the winning bid, which was from a consortium comprised of Apple Inc., Microsoft, Research In Motion Ltd., Sony Corp., Ericsson AB and EMC Corp. RIM's Blackberry and Apple's iPhone do not use the Android OS and Microsoft is providing its own OS for future Nokia phones.

Apple itself is not always on the offensive in IP suits. Samsung has its own claims against Apple and the week before Apple filed its new ITC complaint against Samsung, the Korean manufacturer requested that the ITC stop importing iPhone and iPad that are manufactured in China.

In addition, Apple in June agreed to award a one-time payment and ongoing royalties to Finnish handset maker Nokia to settle a patent fight. Nokia, has been in the handheld business earlier than Nokia, had claimed that Apple's iPhone smartphone and iPad tablet infringed on its patents. As licensee, Apple will be making royalty payments to Nokia for every iPhone sold.

The outcome of the Apple-Nokia dispute could have major implications for Google's Android operating system and the manufacturers using it because Android and Apple's mobile software are similar, meaning Android may also be using many of the same technologies in question, Florian Muller, an intellectual-property consultant in Starnberg, Germany, told the Wall Street Journal.

Global mobile-phone sales totaled 427.8 million units in the first quarter of 2011, an increase of 19 percent from the same period in 2010, according to research firm Gartner.

According to research firm International Data Corp., Apple was the second-largest manufacturer in the first quarter, with an 18.7% market share, selling 18.7 million units of the iPhone, just behind Nokia, which had a 24.3% share. Samsung's 10.8% market share was fourth, as it benefited from a 350% increase in sales year over year. HTC was in seventh place, selling 9.8 million units. Apple has not released a new smartphone this year.

Google's Android system, has already grown to become the largest smartphone operating system with 36 percent of units sold in the first quarter, compared to only 27.4% for the Symbian, and 3.6% for Windows-based devices, according to Gartner Inc.

RELATED STORIES