Patent ID: 8908889

Claim:
A piezoelectric buzzer, comprising: a) a diaphragm that can be vibrated by a piezoelectric material powered by an electric current to produce a buzzing sound; b) a housing substantially enclosing said diaphragm, wherein said housing defines a resonating chamber that includes at least one sound emission port that provides a passageway for sound waves emitted by the diaphragm to leave the resonating chamber, and wherein said resonating chamber has an optimal resonating frequency at a temperature T defined by: f H =v/ 2π(√( A/v o L )) wherein: v is the velocity of sound waves in air at a temperature T, A is the effective area of the sound emission port, v o is the volume of the resonating chamber, and L is the effective length of the sound emission port; and c) a bimetal temperature compensator that moves in response to a change in temperature across a temperature range of at least 200° C. to reduce the value of √(A/v o L) at substantially the same rate as the value of 1/v changes in response to that same temperature change, and thereby to hold the value of f H substantially constant across said temperature range.