PIEZO-ELECTRIC SOUNDING BODY

摘要

PURPOSE:To coincide with a phase of sound from a lower part and an upper part and improve a sound level by providing a through hole in the lower part, of a case. CONSTITUTION:The through hole 5 is provided in the lower part of the case 3. The position of the through hole 5 is set in a distance l from a point A so that a phase of a sound coming out from the through hole 5 may coincide with a phase of a sound from the through hole 4 on the upper part of the case 3. The measurement l is equal to almost n/2 times of wave length of oscillation sound of piezo-electric oscillator consisting of piezo-electric element 2 and metal plate 1. Thus, a level of sound pressure can be improved because no sound stays in the case 3 and a phase of sound coming out from each through hole 4, 5 coincide each other.