Piezo Source's KSN1103A ceramic speaker is a key component of the LS-671/VRC Loudspeaker unit which can be found in SINCGARS family of radios. The SINCGARS (Single Channel Ground and Airborne Radio System) is the Combat Net radio (CNR) currently used by U.S. and allied military forces , it is designed to be as a reliable and secure means of voice and data communication.
Piezo Source's KSN1103A is the ideal choice for this important equipment for this critical military application, because of its ruggedness and durability, as it is able to withstand the shock of hard handling that can be brought about under battle conditions. Piezo Source's KSN1103A is designed with military specification in mind. Its temperature and humidity characteristics allows it to perform reliably in the humid areas of the rain forest or the sweltering heat of the desert, the Piezo Source's KSN1103A is proven to be both reliable and durable, and the choice for battle conditions and mission critical applications.
Primary Examiner Kathlccn H. Claffy Assistant ExaminerThomas W. Brown Franklin Park, 111. a corporation ol'1llinois  AQOUSTIC TRANSDUCER INCLUDING A13ST1L ACT: A conversion between elcctricnl and mechanical HEZOELECTRIC WAFER SOLELY SUPPORTED stimnli lS accomplished in spcakers and microphones by'at- By A DIAPHRAGM tachmg a bimorph piezoelectric annular crystal at n5 center to sclaims n Drawing Figs. the apex or ZlXlS of the speaker or microphone diaphragm. The bimorph crystal is driven in an extension mode [0 effect  U.S.C1 179/110 cgnvgrsion of electrical signals zipplicd to thc cryslul into MPH/00 audio signals at the diaphragm or vice vcrsu. The muchment of the bimorph crystal at its center to the (fpc); of the 1 10, 110-1 diaphragm is the sole lTlCZll'lS ofutmchmcnl ollhc cryslul.
Link: Acoustic Transducer
Piezoelectric audio transducers are known to comprise a piezoelectric bender and supporting structure. Typically, such a transducer has the piezoelectric bender attached to the housing in by the periphery of the bender to provide adequate acoustic impedance. With such a structure, the piezoelectric bender vibrates when it receives an electrical stimulus. This vibration creates a sound pressure within the housing such that the transducer renders the electrical stimulus into an audible signal. By having the piezoelectric bender attached to the housing by it's periphery, the amount of vibration is limited for a give size bender, which also limits the strength of the audible signals.
Conventional piezoelectric loudspeakers require con¬ siderable mechanical dampening to smooth their frequency response. The dampening increases the moving mass of the speaker which in turn reduces its sensitivity, that is, greater drive power is required to produce a given acoustical output. Thus, the acoustic output level of conventional piezoelectric speakers is usually compromised in favor of a smoother frequency response. It has generally been impossible to accurately predict the frequency response of any given piezoelectric loudspeaker. It has been difficult, if not impossible in certain situations, to manipulate or alter the natural frequency response of conventional peizoelectric loud¬ speakers to meet the requirements of specific applications. United States patent Nos. 3,548,116 and 3,786,202, both to Hugo Schafft, are directed to piezoelectric speakers.
Piezoelectric transducers such as monomorphs have been increasingly used in signalling devices such as pagers and other alerting apparatus which employ an essentially single tone alert signal. A monomorph includes a ceramic disk bonded to a metallic backplate thus forming a bender. The monomorph resonates at a predetermined frequency when excited with electrical energy and exhibits a frequency response similar to the classical L-C tuned circuit about a predetermined center resonant frquency. An essentially single tone acoustic signal is generated by such monomorph with a frequency response dropping off rapidly on either side of the resonant frequency of the monomorph.
Conventional bimorph voice range piezoelectric speakers have an input impedance of less than 100 ohms at a frequency of 1500 Hertz (Hz). A typical 70.7 volt audio distribution system is designed to accept speakers having an impedance of 500 ohms to 10,000 ohms which corresponds to power levels of 10 watts to 0.5 watts, respectively. Thus, a matching circuit or transformer is required to couple a conventional piezoelectric speaker to such an audio system. It is an object of this invention to provide a piezoelectric transducer having a higher input impedance which can be directly coupled to audio systems requiring such impedances. A further object of this invention is to provide a piezoelectric transducer capable of operating with sustained voltages greater than 20 volts.
Primary Examiner-William C. Cooper Assistant Examiner-Douglas W. Olms romqx: Eug r eni [5 7 ABSTRACT A disk shaped piezoelectric element constructed to operate in a planar mode so as to define a first overtone nodal ring on one of the major surfaces, a conically shaped diaphragm having a truncated apex defining a generally circular area affixed to a major surface of the element concentric with the nodal ring and spaced radially therefrom so as to reduce the amplitude of the output of the first overtone to approximately the amplitude of the output of the fundamental frequency, and a rubber disk affixed to the opposite major surface of the piezoelectric element to lower the fundamental resonance frequency and damp the peak output of the fundamental and first overtone resonance frequencies to provide a flat response over a desired bandwidth.
Acoustic transducers such as shown in U.S. Pat. No. 3,548,116 often employ a piezoelectric element secured to a diaphragm and connected to a source of electric signals. The electric signals excite the piezoelectric element into mechanical vibration and the vibrations are transferred to the diaphragm developing acoustic energy. In other transducer systems such as disclosed in U.S. Pat. No. 3,739,299, piezoelectric elements have been used as a frequency determining capacitor. In such a system, the piezoelectric element is used as a capacitor in a tuned circuit.