Views: 4 Author: Site Editor Publish Time: 2018-08-24 Origin: Site
Ultrasonic transducers are essentially a class of electromechanical energy conversion devices, which can be divided into piezoelectric, electromagnetic and magnetostrictive types according to their working principles. At present, common ultrasonic transducers are generally piezoelectric, which works by using the positive and negative piezoelectric effects of piezoelectric materials. The piezoelectric material is forced to generate electric charge, which is called positive piezoelectric effect. Conversely, when an electric field is applied to the piezoelectric material, the piezoelectric material will produce mechanical deformation and mechanical stress.This phenomenon is called inverse piezoelectric effect. When the ultrasonic transducer sensor applied electric field is an alternating signal, various forms of elastic waves can be excited in the piezoelectric material. When the frequency of the alternating electric field coincides with the mechanical resonance frequency of the piezoelectric material, the piezoelectric material is in a mechanical resonance state and becomes a piezoelectric vibrator. If the mechanical resonance frequency is in the ultrasonic spectrum, the mechanical wave sent out by the piezoelectric vibrator is ultrasonic.
In the ultrasonic testing technology, the ultrasonic transmitting probe and the receiving ultrasonic range probe can be separately fabricated by using the positive and negative piezoelectric effects. Because the piezoelectric effect is reversible, most ultrasonic probes are both transmitting and receiving.
Ultrasonic distance measuring sensors can be divided into three ranges: large, medium and small according to their working distance. Among them, the small range detection distance is less than 2m, the working frequency is between 90-300kHz; the medium range detection distance is about 20m, the working frequency is between 90kHz; the large 300KHz ultrasonic transducer sensor is about 50m, and the working frequency is between 20-30kHz. In addition, there is an audio ranging sensor whose detection distance is greater than 50 m and the operating frequency is about 10 kHz.
