Views: 0 Author: Site Editor Publish Time: 2023-02-23 Origin: Site
The sound that people can hear is due to the vibration of objects. Its frequency is within the range of 20HZ-20KHZ ultrasonic sensor. If it exceeds 20KHZ, it is called ultrasonic wave, and if it is lower than 20HZ, it is called infrasonic wave. Commonly used ultrasonic frequencies are tens of KHZ-tens of MHZ.
Ultrasonic wave is a kind of mechanical oscillation in elastic medium, which has two forms: transverse oscillation (shear wave) and longitudinal oscillation (longitudinal wave). The application of ultrasonic transducers in industry mainly adopts longitudinal oscillation. Ultrasonic waves can propagate in gases, liquids and solids at different speeds. In addition, it also has refraction and reflection phenomena, and has attenuation during propagation. Ultrasound propagates in the air, and its frequency is low, generally tens of KHZ, while in solid and liquid, the frequency can be higher. It attenuates faster in the air, but propagates in liquids and solids with less attenuation and farther propagation. Utilizing the characteristics of ultrasound, it can be made into various ultrasonic sensors, coupled with different circuits, into various devices and devices, and widely used in communication, medical appliances and other aspects.
The main materials of ultrasonic sensors are piezoelectric ultrasonic transducers (electrostrictive) and nickel-iron-aluminum alloy (magnetostrictive). Electrostrictive materials include lead zirconate titanate (PZT) and the like. The ultrasonic sensor composed of piezoelectric crystals is a reversible sensor, which can convert electrical energy into mechanical oscillation to generate ultrasonic waves. At the same time, when it receives ultrasonic waves, it can also be converted into electrical energy, so it can be divided into transmitters or receivers. Some ultrasonic sensors can both send and receive. Only small ultrasonic range transducers are introduced here, and the transmission and reception are slightly different. It is suitable for transmission in the air and the working frequency.
