Rock 'n' Roll Up: Super-Thin Speakers on Horizon

ByABC News
April 18, 2001, 2:02 PM

April 19, 2001 — -- Is it possible for your typical stereo speaker to both rock and roll?

Researchers at a South Korean laboratory think they have come up with a breakthrough to allow more widespread use of relatively inexpensive loudspeakers that can be pinned to a wall, then folded or rolled to be carried away in someone's pocket.

They could even, says one expert, become a computer screen that's also a speaker.

Scientists at the Thin Film Technology Research Center, at the government-run Korea Institute of Science and Technology, hope their new technique for bonding electrodes more securely to piezoelectric film will allow for more durable speakers made of the clear, paper-thin material.

"The film itself is a speaker," says Koh Seok-keun, principal scientist on the project.

Piezoelectric films and ceramics, which convert electrical energy into vibrations and vice versa, have long been used as components in speakers, underwater sonar systems, cell phone ringers, police sirens, cigarette lighters and other devices, experts in the field say. They create sound or energy with microscopic vibrations on the materials' surface.

Specialty dealers have sold small piezoelectric film speakers for a decade, says one such dealer with an Internet storefront. And according to Kenji Uchino, an expert in piezoelectric devices at Penn State University, large companies in Japan have marketed flat, rollable, opaque speakers made with piezoelectric ceramics for almost as long.

The problem with these existing speakers, critics say, is that while they do a good job of reproducing high-frequency sounds, they often are not substantial enough to produce deep bass sounds, or play at high volume.

"Even with quite large ones, which I've got a pair of them in my living room, they need a bass reinforcement," says David Pearce, a research fellow in functional materials at the University of Birmingham in England who specializes in piezoelectric ceramics. "Hearing these sort of panel speakers individually, they always sound kind of tinny. But then you put them together with bass support and you say, 'That sounds pretty good, actually.'"