The
piezoelectric speaker consists of a piezoelectric
crystal
connected to a metal
membrane.
Buildup:
______________________
|______________________| Membrane
|##############| piezoelectric crystal
"""""""""""""" electrode
The other surface of the crystal is metalized to create
an
electrode. The membrane also serves as an electrode
When a
signal source is connected to the electrodes
the crystal
expands and
contracts in
relation
to the signal, this makes the membrane
vibrate and
thus creates soundwaves.
The piezoelectric speaker is
compact, only about 1mm thick
but is best
suited for higher
frequencies. They are
used in
electronic alarm
clocks,
buzzers and other
applications
where a small soundsource is needed.