Diaphragm type piezoelectric electroacoustic transducer

An electroacoustic transducer comprising:

• a housing having a chamber therein and an aperture;
• a vibrating assembly mounted in the chamber of said housing and including:
• a metal diaphragm confronting the aperture;
• a piezoelectric element engaging one surface of the diaphragm;
• an acoustically-massive clamp ring engaging the periphery of the diaphragm;
• first and second electrical terminals connected to said piezoelectric element;
• and
• an acoustic leakage path within the chamber between the back of the diaphragm and the front of the diaphragm and operative when the transducer is in a transmitting mode to direct a portion of backward radiation from the back surface of the diaphragm to the aperture at a controlled phase in relation to the forward radiation from the front surface of the diaphragm to modify the directional transmission characteristics of the transducer, and operative when the transducer is in a receiving mode to direct a portion of received radiation from the aperture to the back surface of the diaphragm at a controlled phase in relation to the radiation received at the front surface of the diaphragm to modify the directional receiving characteristics of the transducer.

An electroacoustic transducer comprising:

• a housing having an aperture;
• a vibrating assembly mounted in said housing and including a metal diaphragm confronting the aperture, a piezoelectric element engaging one surface of the diaphragm and an acoustically-massive clamp ring engaging the periphery of the diaphragm;
• the vibrating assembly being driven by or receiving a fixed frequency less than the resonant frequency of the vibrating assembly, such that as ambient temperature increases, the resonant frequency decreases and approaches the fixed frequency;
• an acoustic leakage path between the back of the diaphragm and the front of the diaphragm and operative when the transducer is in a transmitting mode, to direct a portion of backward radiation from the back surface of the diaphragm to the aperture to provide greater reinforcement of forward energy with increasing temperature, and operative when the transducer is in a receiving mode, to become more nearly in phase with increasing temperature thereby to increase the sensitivity with increasing temperature.

For use with an electroacoustic transducer having a vibrating assembly which includes a metal diaphragm, a pattern director comprising:

• a first cavity having an input aperture spaced from said diaphragm to receive energy therefrom prior to beam formation;
• a second cavity contiguous with the first cavity and having a diameter one Fresnel zone greater in area than that of the first cavity;
• and
• the length of the first cavity and second cavity being one-quarter wavelength and one-half wavelength, respectively.

An electroacoustic transducer comprising:

• a housing having a chamber therein and an aperture;
• a vibrating assembly mounted in the chamber of said housing and including:
• a metal diaphragm confronting the aperture;
• a piezoelectric element engaging one surface of the diaphragm;
• and
• an acoustically-massive clamp ring engaging the periphery of the diaphragm;
• first and second electrical terminals connected to said piezoelectric element;
• an acoustic leakage path within the chamber between the back of the diaphragm and the front of the diaphragm and allowing a controlled portion of backward radiation from the back surface of the diaphragm to leak around the periphery of the vibrating assembly to said aperture at a controlled phase with respect to the forward radiation from the front surface of the diaphragm to modify the directional characteristics of the transducer;
• and
• a pattern director secured to said housing and extending outwardly and in communication with said aperture and having at least one cavity configured to provide a pattern of intended shape.