There are generally two fixing methods for piezoelectric buzzer: peripheral support and node support. These two methods are explained in detail as follows.
Piezoelectric buzzer The so-called peripheral support mode is to fix the outer diameter edge of the piezoelectric buzzer in the resonant cavity, and generally adopt the non feedback buzzer (separately excited piezoelectric buzzer). The piezoelectric buzzer frequency must be matched with the resonant cavity frequency to have a higher sound voltage output, and the external oscillation circuit generates a push signal to make the buzzer sound.
Because of the vibration in the same side, although the phase is the same side, the phase direction sound wave of its cavity must be isolated first. The smaller the edge, the better, to avoid suppressing the buzzer touch Piezoelectric buzzer for peripheral support The node support means that the piezoelectric buzzer is fixed in a circular layout with the same diameter as the ceramic sheet. If the resonant cavity is properly designed and matched with feedback buzzer (self-excited piezoelectric buzzer) and positive feedback circuit with accurate frequency, large sound pressure and accurate frequency will occur. As the node supporting the piezoelectric buzzer, the phase difference between space A and space B (B1, B2) is 180 °?,
In order to prevent the sound pressure from canceling each other and further improve the sound of specific frequency, the middle part and the periphery are isolated acoustically, and the middle part is taken out of the same phase.