Tonpilz piezoelectric transducers are one style of transducers for high-power sound generation. However, the transducers have mainly been designed by the trial-and-error method. The object of this paper is to precisely estimate the transducer performances beforehand by a equivalent circuit analysis. The precise electro-mechano-acoustical equivalent circuit is derived for the transducer, including housing, an acoustic rubber layer and a bolt, and its transmission matrix is presented. To improve the calculation accuracy, the effects of adhesive layers in a piezoelectric ceramic stack part and compressive stress by bolting them together are included into the electrical and mechanical equivalent constants for the ceramic stack. Also, to accurately evaluate any errors between theoretical values and measured values, transducer performances are expressed as absolute values by MKS units. Then, based on this analysis, a Tonpilz transducer has been built. Transmitting and receiving voltage sensitivities for the transducer, as well as the respective resonant frequencies, mechanical quality factors and free admittance loci in air and in water, have been measured. As a result, a good agreement between theoretical values and experimental results has been achieved.

A method has been investigated for calculating the material constants for piezoelectric ceramics under the one-dimensional stress, using a bolted Langevin resonator, which can apply compressive stress to the ceramics. For this method, the piezoelectric, dielectric and elastic constants under the static compressive stress can be determined, by measuring the resonant and antiresonant frequencies and the capacitance at constant stress for the resonator, in the same method as used under stress-free condition. Also, four types of lead zirconate titanate piezoelectric ceramics for transducers, NEPEC-1, NEPEC-6, NEPEC-63 and NEPEC-21, have been measured as a function of one-dimensional compressive stress parallel to the polar axis up to a 176 MPa maximum. The hysteresis loops for dielectric constants /ε0, electromechanical coupling factors k33, piezoelectric constants d33 and g33, and elastic constants and for these ceramics have been presented. These measurement results show inclinations analogous to those reported by Krueger and Meeks. The experimental feasibility and practicability of using a bolted Langevin resonator to measure the piezoelectric ceramic material constants have been established.

A 1.544 MHz timing-extraction ceramic filter is examined. This filter has been successfully introduced into a PCM carrier system. Second-order Gaussian approximated effective-parameter theory with gentle frequency-phase inclination characteristics is applied in the circuit design. A ladder transformer filter construction, employing two resonator units and a coupling capacitor, is adopted. A resonator unit, comprising a trapped-energy piezoelectric ceramic strip resonator operating in the width-shear vibration mode and a ceramic capacitor connected in series with the resonator, fulfils the function for easy frequency adjustment and temperature compensation of the resonant frequency. Filter input and output terminating resistances are 30 Ω and 1500 Ω, respectively. The 3 dB fractional bandwidth is 1.07% and the insertion loss at center frequency f0 is -4.8 dB. The frequency deviation of f0 is within 200 ppm over a -20 to 60 temperature range and the aging rate of f0 is about 0.01%/decade. The frequency deviation over the operating temperature range is less than one-third and the aging rate is about one-half of the conventional LC filter used for this application. The filter size is reduced to one-fifth that of the LC filter.

The construction method for ladder filters employing piezoelectric ceramic resonators, widely used in consumer radio communication equipments, is investigated with the object of obtaining low-cost high-performance filters. For the presented method, the resonant or antiresonant frequencies of the resonators included in a filter are staggered one after another, perceiving that a small difference in these frequencies between electrically adjacent resonators can be tolerated. The allowable frequency limits for this filter are about four times as great as those for a usual filter, designed using the image parameter or near-image parameter method. The filter can exhibit performances equal to the usual filter. The frequency adjustment process for resonators is able to be fairly well curtailed. Filters based on this construction method include ceramic filters for CB transceiver and pocket-bell receiver, which were designed and trially produced. As a result, low-ripple filters with rough frequency adjustment at most were obtained.

A wideband and high efficiency underwater ultrasonic transducer with a single acoustic matching plate has been presented. The transducer consists of a piezoelectric ceramic resonator, operating in unstiffened longitudinal mode, and a single acoustic matching plate bonded to the ceramic resonator. The matching plate is made of a Al2O3-epoxy composite. The ceramic resonator is T-shaped with a taper, where its polarized part is a thin rectangular bar, which can be driven with low voltage, and where its non-polarized parts comprise a horn part and a head part. The transducer has been designed based on a double mode filter synthesis theory, because it has two resonant modes, whose phases differ byπfrom each other. The optimum specific acoustic impedance and length for the matching plate have been calculated. The 30 kHz array, including four transducers supported at their vibrational nodes, has been fabricated and evaluated. As a result, it has been confirmed that the array has the following characteristics: 33% fractional bandwidth, 211.6 dB sound pressure level re lµPa at l meter,177 dB receiving voltage sensitvity re 1 V/µPa and possible operating depth over 3000 meters. Excellent agreement between theoretical values and experimental results has been obtained. It has been proved that this transducer is useful as a transducer with high resolution for deep oceans.