Patent ID: 6147595
Filing Date: 2000-11-14
Classification: G10K

Abstract:
A buzzer comprising:a casing, said casing comprising a cylindrical open chamber, a bottom center hole at the center of a bottom sidewall thereof for output of sound waves, and an annular supporting flange rose from the bottom sidewall within said open chamber around said bottom center hole;a diaphragm mounted inside said cylindrical open chamber of said casing and fixedly supported on said annular supporting flange, said diaphragm comprised of a thin circular piece of metal film fixedly supported on said annular supporting flange, and a ceramic membrane adhered to said circular piece of metal film, said circular piece of metal film having a diameter approximately equal to the diameter of said cylindrical open chamber, said ceramic membrane having a diameter approximately equal to the diameter of said annular supporting flange, said ceramic membrane having a bottom side wall coated with a layer of metal coating and electrically conductively adhered to said metal film, a non-conductive peripheral line around the periphery thereof, and a non-conductive curved line provided at a top side wall thereof and connected between two points at said peripheral line, said non-conductive peripheral line and said non-conductive curved line separating said ceramic membrane and said metal film into three conductive zones; anda circuit board mounted in said cylindrical open chamber inside said casing, said circuit board having a diameter approximately equal to the diameter of said cylindrical open chamber, said circuit board comprising a buzzer starting circuit at a bottom side wall thereof, two power terminals raised from a top side wall thereof for connection to power supply;wherein said casing comprises a plurality of locating ribs symmetrically disposed inside said cylindrical open chamber for the positioning of said circuit board in said casing; said circuit board comprises three metal contact spring elements raised from the bottom side wall and respectively maintained in contact with the conductive zones at said diaphragm, and a plurality of peripheral notches respectively matched with the locating ribs at said casing for positioning.