The newly-developed piezoelectric speaker.
TDK Corp developed a thin speaker with a thickness of 0.49mm.
TDK stacked 12 layers of piezoelectric material so that displacement at the time of applying a voltage becomes large. As a result, the volume of sound was increased.
Also, by making improvements to the structural design of the speaker, TDK increased sound pressure at a frequency of several hundred hertz, at which it is difficult to increase output with a piezoelectric speaker.
TDK expects that the speaker will be employed for consumer products such as tablet computers and TVs. The company also plans to develop an in-vehicle model to be used in the interior space of vehicle by 2020.
The new speaker was developed by using a piezoelectric device that TDK has been developing for tactile devices. While the speaker for tactile devices, which gives a small displacement to the surface, uses two layers of piezoelectric material, the new speaker uses 12 layers of piezoelectric material to increase sound pressure.
To increase the number of layers, through-holes were made in each layer for interconnection so that a voltage can be applied without voltage dividing.
The speaker comes in two types: a “wide-range” type and “high-range” type. The usage frequency band of the wide-range type is 400-20kHz. Though it does not support a low range, compared with commonly-used electromagnetic speakers, it is sometimes enough for tablet computers and notebook computers, TDK said.
The usage frequency band of the high-range type is 1,000-20kWz. It is expected to be embedded in TVs, etc and clarify a location from which sound is being generated (sound positioning).
The price of the sample of the speaker is ¥6,000. TDK plans to start to produce 30,000 units of the speaker per month.