Elo TouchSystems, a division of Tyco Electronics Corp., is unveiling a major new touchscreen technology June 7 at the Society for Information Display International Symposium in San Francisco. Dubbed Acoustic Pulse Recognition, or APR, the technology has serious potential for self-service applications.

"Simply stated, a touch at each position on the glass generates a unique sound," said Elo product manager David Chen. "Four tiny transducers attached to the edges of the touchscreen glass pick up the sound of the touch. The sound is then digitized by the controller and compared to a list of prerecorded sounds for every position on the glass. The cursor position is instantly updated to the touch location."

By using the sound generated when a finger or stylus touches the glass, APR allows users to touch the screen with practically anything - a fingernail, gloved hand, pen or corner of a credit card. Since there is no optical component being measured, it doesn't matter if the glass - plain glass - becomes scratched or otherwise marred.

Elo president and general manager Mark Mendenhall said research on the technology began about 10 years ago, with the initial filing of patents starting four years ago.

"The last two years is when the ramp-up of the technology started," he said, "when we started getting really excited about it."

Mendenhall said extensive research has tested ambient sound, which is used to build the database that powers the software drivers. In one test, jingling keys near the screen "sounded" like a touch - so those sounds were added as factor-outs to the driver's library of noises.

One of APR's main strengths is that the touchscreen - as well as the device that bears it - can be completely shielded from the elements and still function properly. Because many touchscreens fall short in that area, Mendenhall said Elo's screen is ideal for outdoor applications and POS systems - the latter of which marks Elo's first push for the technology.

"We think this product is going to be great in POS," he said.

Other benefits include the optical qualities and durability of pure glass, a fixed coordinate system that won't "drift" over time, and the ability to ignore portions of the screen (for instance, to perform palm rejection for on-screen signature pads).

APR also promises to be economical, especially in large-scale applications. Since it uses plain glass, as well as a software algorithm to "hear" the location of the touch, it is economically attractive for very large displays.

The technology does have one weakness - its inability to detect an "untouch." If someone touches the screen and then pauses, it doesn't know whether the touch is still taking place, since sound is no longer generated.

That presents a problem for applications that require a "touch and hold" or a "drag and hold," but Mendenhall said he doesn't think it will pose problems for most kiosk and self-service applications.

Mendenhall added that Elo continues to manufacture all of its existing technologies, including surface acoustic wave (SAW), resistive and capacitive, so someone needing to be able to read an "untouch" will still have those options.

(To learn more about APR, download Elo's comprehensive white paper on the technology.)