Machine Design

Flat speakers get smaller

The second generation of distributed-mode actuators, the electromechanical components in flat speakers for portable devices, are now 20% smaller and up to 10 times more efficient than traditional magnet-and-coil designs.

The new DMAs from NXT plc, Huntingdon, U.K. (, measure 22 7 3.5 mm and rely on piezoelectric polycrystalline ceramics. Applying a voltage changes the ceramic actuator, which generates sound when the actuator is connected to an acoustic lens. In a portable phone, for example, the DMA, which contains two ceramic actuators, attaches to the display screen, which vibrates to create sound. DMAs are typically 1.5-mm thick, weigh about 2 gm, and cost less than $2.00.

TAGS: Technologies
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