Abstract
Actuating a Langevin vibrator at highly operating voltage, the resonant frequency was shifted due to the phenomena of thermal levitation and the loading of extra pre-pressure, resulting in the less mechanical work output. Otherwise, considering the limit magnitude of vibration for a vibrator, a horn, or call a resonant amplifier, was designed and added to the top side on a vibrator to enlarge the mechanical vibration amplitude.The piezoelectric impedance measurement and the equivalent circuit were obtained for the fundamental characteristics of a vibrator via the HP 4194A Impedance Gain/Phase Analyzer in this thesis. These parameters are called as the piezoelectric static feature. The characteristic of motional current relative to frequency response was achieved under practical driving voltage for a vibrator, called as the piezoelectric dynamic feature. Both static and dynamic features in a piezoelectric vibrator were compared in order to find the difference and build the dynamic equivalent circuit with operating voltage. Furthermore, the vibration measurement module of optical fiber was employed to detect the maximum displacement of a vibrator with a resonant horn (amplifier). The measured result has demonstrated that the resonant frequency was moved to the lower frequency band. Therefore, the new equivalent circuit model was proposed for more matching the real response through P-Spice simulation in this study. By mean of measurement and simulation, the stepped horn could increase about seven times of the mechanical vibration amplitude; that is the more efficient in mechanical output for a vibrator. The resonant horn is a series circuit of a negative resistor and a inductor based on the simulation and analysis of the dynamic equivalent circuit.