Paul Sakuma, Associated Press
A customer holds an iPhone in October 2007. Other manufacturers are racing to produce touch-screen models.

NEW YORK — It's been a good year for touch screens.

The launch of the first iPhone model a year ago boosted interest in the technology tremendously, and the updated model that went on sale Friday likely will stoke enthusiasm further. Now touch-screen manufacturers are going flat out, and more devices will soon be controlled by the tip of your finger.

"After the iPhone came out, a lot of mobile-phone companies said, 'Oh, I can make that kind of touch-screen mobile phone, too,"' said Jennifer Colegrove, analyst at iSuppli Corp.

In the United States, Sprint Nextel Corp. just introduced a touch-screen phone, the Samsung Instinct, that's very reminiscent of the iPhone. Verizon Wireless this year introduced its first two phones that use touch screens as their main interface. Research In Motion Ltd. is believed to be making a touch-screen version of the BlackBerry. Sony Ericsson is bringing out its first touch-screen model in a few months.

Jon Mulder, product marketing manager for Sony Ericsson's U.S. arm, said touch screens have become a "hygiene factor" — a must-have for phones that want to compete in the high end of the U.S. market.

Colegrove projects that 341 million touch screens will be shipped worldwide this year, up from 218 million in 2007 and 81 million in 2006.

In the first half of 2007, before Apple Inc.'s iPhone launched, a big maker of touch sensors for portable electronics would make perhaps a million units per month, Colegrove said. "Then, in the second half of 2007, suddenly they received huge orders, so they ramped up their production to maybe 3 or 4 million units per month."

Apart from the iPhone, demand for touch screens is driven by new phones in Asia that allow the user to write Chinese or Japanese characters on the screen, usually with the aid of a stylus. That's much easier than entering those characters with a keypad, Colegrove said.

Most touch sensors are made in Japan, Taiwan and China by companies that are relatively unknown in the United States, like Nissha Printing Co., Wintek Corp. and Truly Semiconductors Ltd.

Balda AG of Germany supplied the touch sensor for the first iPhone through a joint venture with a Chinese company.

In the United States, major players in the touch field are 3M Co. — though it mainly supplies larger screens for ATMs and monitors, rather than portable electronics — and Synaptics Inc., which supplies touchpads for Apple's laptops. Others, like Cypress Semiconductor Corp., make the chips that control the sensors.

Synaptics has a growing business supplying touch sensors for cell phones, as well. It uses a particular type of touch sensor known as "projected capacitive." Before the iPhone came along, Synaptics was struggling to convince manufacturers that the technology was better than the cheaper "resistive" screens.

"The technology was there to use years before the iPhone," said Andrew Hsu, Synaptics' touch-screen expert.

Capacitive sensors are more durable, interfere less with the screen's image and can sense the touch of more than one finger at a time — allowing for the iPhone's signature "multitouch" ability. They cost about $20 for an iPhone-size sensor, compared with about $5 for a resistive screen.

Frustrated with the lack of interest, Synaptics put together its own concept phone, the Onyx, in 2006, to demonstrate the capabilities of the touch screen, including multitouch input. LG of Korea then used Synaptics' touch sensor in its Prada phone, which came out some months before the iPhone. But it was Apple that broke the barriers, Hsu said.

"The best showcase of this technology has been the introduction of a production model that works very well," he said.

Colegrove expects projected capacitive sensors to be among the fastest-growing technologies, with over 35 million units shipped this year, mainly for the iPhone and iPod Touch. That's up from 10 million units last year and only a handful in 2006. But the more traditional resistive type will continue to make up most of the volume, especially since they're better suited to stylus input for the Asian market.

The touch-screen craze is spreading beyond cell phones, as well.

Microsoft Corp. Chairman Bill Gates has said touch sensors and speech recognition are a focus of the company's development efforts. Hewlett-Packard Co. introduced a desktop PC with touch screen last year and updated the line this year. Touch screens have become standard for GPS devices, a fast-selling category. Colegrove expects e-book readers to start coming with touch screens too.

Touch screens are the ideal solution, Hsu said, for maximizing screen size while keeping gadgets small. They also make for easy-to-use devices, because each application can present its own specific controls, rather than relying on hardware buttons shared with other applications.

"There's really no room left for buttons," Hsu said.