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SAN JOSE, Calif.
— Prompted partly by the iPhone's phenomenal
popularity, consumers are demanding and likely to get a
wider range of touch screens on many more electronic
devices.
The
screens have become wildly trendy by allowing people to
operate cell phones, bank teller machines, airport
kiosks and other gadgets by simply pressing a finger to
a screen or, in some cases, merely waiving their pinkie
over it.
But the
multibillion-dollar touch-screen market is awash with at
least a dozen competing technologies, each requiring a
differently designed microchip known as a controller to
make their screens work. And that poses considerable
risk for any semiconductor company trying to determine
which technology to embrace.
"You're
kind of having to make a gamble," said
Randy Lawson
, a senior analyst with chip research firm iSuppli.
"A lot of people are asking, 'Who's going to be the
winner in five years?'"
Most
touch screens today use what is known as resistive
technology, which incorporates two electrically
conductive layers separated by air. When a finger or
stylus presses the screen, it compresses the layers
together and changes the electrical current, which the
screen recognizes as a touch.
One chip
maker long experienced with the resistive approach is
Maxim Integrated Products
of
Sunnyvale, Calif.
, which considers the technology ideal for such things
as printers, MP3 players, digital photo frames and car
entertainment systems.
"We've
being doing resistive touch-screen controllers for the
past eight years," said Bart DeCanne, a Maxim
business director, noting that the technology is popular
because it is relatively inexpensive and adaptable for a
variety of uses.
But
resistive touch screens have their limits. They tend to
wear out with all the pounding they take and they aren't
generally designed to accommodate gestures with more
than one finger, as is possible with the
Apple's
iPhone. With that phone, for example, a person can zoom
into a picture or Web page by putting their thumb and
index finger on the screen and spreading them apart. To
zoom back out, the fingers are pinched together.
While
companies are just beginning to explore multitouch
capabilities, experts say being able to operate screens
with up to 10 fingers will enable people to play virtual
piano, create elaborate finger paintings, easily
rearrange computerized photo albums and enjoy new types
of video games, among other possibilities.
The
technology generally regarded as best suited for
multiple-finger commands — and the one the iPhone uses
— is called capacitive touch, which relies on the
human body's electrical properties.
In a
basic configuration, a capacitive screen is given a
uniform electric field by electrodes placed around its
edges so that a finger touch draws current from each
corner of the screen. The controller then measures the
current flow from the corners to instantly calculate the
finger's location. Some capacitive designs can detect a
finger that comes close to the screen but doesn't
actually make contact with it.
While
generally more expensive to make than resistive screens,
the capacitive kind are becoming more affordable and
"getting a lot of interest" from chip makers,
said
Jennifer Colegrove
, an analyst with the market research firm DisplaySearch.
One
company that has forged heavily into capacitive
technology over the past two years and has become a
leading supplier of capacitive chips is
Cypress Semiconductor
of
San Jose
.
Many chip
companies, including Cypress, don't disclose how much
they earn specifically from touch-screen sales, which
analysts say makes it hard to calculate the overall size
of the touch-screen controller market. But the business
"is on a very growth trajectory," said
Gokul Krishnan
, Cypress' director of marketing user interface
solutions, adding that "almost everyone is
switching from resistive to capacitive."
Among
those jumping on the capacitive train is Maxim. But
because resistive touch screens are likely to remain
desirable for certain consumer and industrial
applications, said Maxim's DeCanne, "we believe
resistive is going to be the bulk of our business for
the next two years."
Hedging
its bets even more is Elo TouchSystems of
Menlo Park, Calif.
, which has been developing touch-screen capabilities
for about 40 years and became part of
Switzerland
-based
Tyco Electronics
in 1999.
Besides
selling resistive and capacitive controllers, Elo offers
products based on several other touch-screen
technologies. Two of them pass sound waves over the
screen, so a finger touch is identified by a change in
the wave. Another creates a grid on the screen with
infrared light-emitting diodes. When a finger interrupts
the light, the touch is detected by photo sensors.
By
offering several options, Elo differentiates itself from
competitors that "force-fit you into one type of
technology," said
Lorna Wood
, the company's global marketing manager.
More
alternatives are probably coming, said
Amy Leong
, an analyst with research firm
Gartner
.
"The
touch market is still in its infancy stage," she
said. "In the next few years, we are going to see
many types of touch technologies being tested and
deployed for various applications."
———
TWO
TOUCH-SCREEN TECHNOLOGIES
Resistive
technology incorporates two electrically conductive
layers separated by air. When a finger or stylus presses
the screen, it compresses the layers together and
changes the electrical current, which the screen
recognizes as a touch.
Capacitive
touch relies on the human body's electrical properties
and is regarded as best suited for multiple-finger
commands. In a basic configuration, a capacitive screen
is given a uniform electric field by electrodes placed
around its edges, so that a finger touch draws current
from each corner of the screen. The controller then
measures the current flow from the corners to instantly
calculate the finger's location.
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