A Study on Structural Parameters for Optimizing Wide-Band Property of Diaphragm-Type Transducer Using Piezoelectric Thick Film

We have investigated how the bandwidth and sensitivity change by thickening the PZT diaphragm by simulation, and confirmed that those are improved than a general thin diaphragm. In this study, a broadband design method of diaphragm type transducer is focused on. It is expected that the existence of an appropriate value of the aspect ratio defined between the width and the thickness. It is investigated that the reception performance of diaphragm transducers consisting of PZT and Si layer by FEM simulation. Design parameter dependence of the ultrasonic reception performance is confirmed by simulation, and its tendency is analyzed. Based on the results, a transducer design method for a desired frequency band is derived. It has been confirmed that a diaphragm thicker than a certain thickness threshold has a specific bandwidth of 150% or more. The critical thickness at which the bandwidth can be widened is determined by the aspect ratio. A thick diaphragm, that is, a high aspect ratio diaphragm causes coexistence of membrane vibration and thickness vibration. If the thickness is too thick, it becomes a simple thickness vibration, and the bandwidth gradually narrows. For desired frequency bands, it is possible to design for various applications from the viewpoint of bandwidth and sensitivity using the aspect ratio. From the results of this study, the relationship between the desired frequency bands and the aspect ratios was derived, and by using it, wideband design is easily realizable.