3. Piezoelectric Buzzer Technology
The technology will be to make over !
Piezoelectric buzzer is a compact, energy efficient sound producing device, which is an assembly of a vibration mechanism attached to a piezoelectric ceramic plate with two electrodes on both sides. When AC electricity of a given frequency is applied to the electrodes, an audible vibrating sound with the same frequency is produced by the assembly. The materials used to manufacture the buzzer plates are derivatives of lead zirconium-titanate (PZT) with a general chemical formula: Pd x Sry (MZr. NTi)z0n + Nba0b.
Preparation of powder material
proper starting ingredients are mixed thoroughly, ground and made into small
cakes, which are then heated in a high temperature furnace. The following main
reaction takes place:
The heated cakes are then further finely ground into a powder form.
powder thus obtained is mixed with PEG binder and pressed into a thin film, from
which the product blanks with desired shapes are prepared.
Binder removal and sintering
product blanks are then heated to remove the binder and then sintered to give
piezoelectric ceramic plates.
Polarization and testing
sides of the ceramic plate are then coated with silver electrodes, which are
further strengthened through a polarization process. The resonance resistance of
the piezoelectric ceramic plates thus obtained should be below 4.8 ohms.
Buzzer assembling and QC
piezoelectric ceramic plates are then attached to the vibration mechanisms with
epoxy resin to give the buzzers. The product QC of the buzzers obtained through
the above sophisticated manufacturing process is carried out with special
instruments. The major electroacoustic parameter, Kp, should be better than 60%