Piezoelectric speakers

Claim 2

A piezoelectric speaker comprising: a frame including a generally circular side wall portion having a sloped inner side wall; a mid plate defining with the frame a first chamber therebelow having a circular rim and a second chamber thereabove with the circular side wall, the mid plate also defining a throttle hole therethrough interconnecting the first and second chambers; a diaphragm inserted in the first chamber; a cover means press-fitted to the frame in the first chamber and having a circular side wall thereof retaining the diaphragm in position by means of a peripheral top edge of the circular side wall coacting with the circular rim of the mid plate; a piezoelectric transducer element longitudinally bonded underneath to the diaphragm; and, a reflection cover extending over the second chamber and, spaced from the mid plate, the reflection cover having a contoured inner surface with a curved cross-sectional configuration with a protruding tip located adjacent to the throttle hole of the mid plate and defining a plurality of discharge openings uniformly located around an outer periphery.

Claim 3

A piezoelectric speaker as claimed in claim 1 wherein the diaphragm is axially spaced from an inlet of the throttle hole of the mid plate a distance of from 0.5 mm to 0.7 mm.

Claim 4

A piezoelectric speaker as claimed in claim 1 wherein the inner surface of the reflection cover defines a plurality of first cusps and an adjacent surface of the mid plate defines a plurality of second cusps laterally offset with respect to the plurality of first cusps.

Claim 5

A piezoelectric speaker comprising: a frame including a mid plate having a throttle hole, a circular side wall extending downwardly from a peripheral edge of the mid plate and a flange, the frame defining a first chamber communicating with the throttle hole and the flange defining a plurality of uniformly disposed discharge openings; a diaphragm inserted in the first chamber; a cover means press-fitted to the frame in the first chamber with a circular side wall thereof retaining the diaphragm in position by means of a peripheral top edge of the circular side wall coacting with a portion of the mid plate; a piezoelectric transducer element longitudinally bonded underneath to the diaphragm; and, a reflection cover having a top wall extending over, but spaced from the mid plate, defining a second chamber, the top wall having a contoured inner surface with a curved cross-sectional configuration with a protruding tip located adjacent to the throttle hole of the mid plate and a circular side wall extending downwardly from a peripheral edge of the top wall so as to engage a periphery of the flange.

Claim 6

A piezoelectric speaker comprising: a frame including a mid plate having a throttle hole, a circular side wall extending downwardly from a peripheral edge of the mid plate and a flange, the frame defining a first chamber communicating with the throttle hole and the flange defining a plurality of uniformly disposed discharge openings; a diaphragm inserted in the first chamber; a cover means press-fitted to the frame in the first chamber with a circular side wall thereof retaining the diaphragm in position by means of a peripheral top edge of the circular side wall coacting with a portion of the mid plate; a piezoelectric transducer element longitudinally bonded underneath to the diaphragm; and, a reflection cover having a top wall extending over, but spaced from the mid plate, defining a second chamber, the top wall having a contoured inner surface with a curved cross-sectional configuration with a protruding tip located adjacent to the throttle hole of the mid plate and a circular side wall extending downwardly from a peripheral edge of the top wall so as to engage a periphery of the flange.