Fujifilm has developed a foldable film that can operate as speaker's diaphragm, with devices to be showcsaed at nano tech 2013 trade show in Tokyo. At the trade show, the company exhibited a slim, foldable speakers, which are using the film as a diaphragm, Japanese web site TechOn reported today.

The development of a bendable diaphragm requires use of soft, flaxible materials, which however, absorb vibration and lack of high acoustic characteristics.

To solve these issues, Fujitsu used a viscoelastic polymer that hardens in the audible range (20Hz to 20kHz) and softens in the range for bending it. The polyner was mixed with piezoelectric ceramics to make a piezoelectric composite and packaged it with a protection layer. When a voltage is applied to the electrodes attched to the device, the piezoelectric ceramics vibrates, and the viscoelastic polymer functions as a diaphragm.