1. Field of the Invention
The invention is about a measuring system for determining the electromechanical coupling characteristics of a piezoceramic (PZT) vibrator, and more particularly to a system measuring bouncing height and time of a metal ball for determining the electromechanical coupling characteristics of a PZT vibrator or for determining the hardness of other rigid object.
2. Description of the Prior Art
When an object is placed on surface of a Langevin PZT vibrator vibrating in high frequency, the object is easily to leave up and to slip, which is called levitation phenomena of vibrators in physics. Traditionally, ultrasonic levitation is caused by a vibrator vibrating in ultrasonic frequency to disturb the air and then generate a radiation pressure field. If an object is placed in the pressure field, it would be levitated by the radiation pressure. As a result of decrease of contact force between the object and vibrating surface, the ultrasonic levitation can solve industrial abrasion and vibration issues.
However, it is hard to measure the contact status between the levitated object and the vibrator and to realize whether there is a point contact or a air gap. Prior researches apply several methods comprising using CCD camera to observe the levitation; measuring different required voltage of the vibrator to levitate objects with different weight; using Doppler laser analyzer to measure the gap between the levitated object and the vibrator and realize the contact status with quantification of data; or using non-contact opto-fiber displacement meter to directly measure the tiny vibration of the vibrator. No matter how, the mechanism is caused by the effect of piezoceramic material of a Langevin vibrator transforming the input electrical power into mechanical energy. The mechanical energy is presented in mechanical form and is the important issue of measurement.