Displacement amplification and resonance characteristics of the cymbal transducers

The cymbal transducer consists of an inner P-5 piezoelectric disk mechanically coupled to two thin brass end caps on each of its electrode faces by eccobond epoxy. The caps serve as mechanical transformers for converting and amplifying the small radial displacement and vibration velocity of the ceramic disk into a much larger axial displacement and vibration velocity normal to the surface of the caps. Based on previous studies of cymbal transducers, the displacement amplification and the properties of resonance of the cymbal were elevated by optimizing the fabrication technique. Several kinds of end caps were designed and some theoretical models were used for the cymbals to study their performances based on the cavity depth and caps thickness. They showed more than 14× to 38× amplification over the uncapped ceramic alone under the direct current (dc) mode. And under the alternating current (ac) mode, the cymbals showed much larger peak-to-peak displacement than dc displacement. Effective piezoelectric charge coefficient of the cymbal reached to 22,550 pm/V. The cymbals also showed the first resonance frequency from 28.54 to 58.53 kHz and faster resonance time about several tens of microseconds.