Views:200 Author:Site Editor Publish Time: 2020-05-21 Origin:Site
Ultrasonic sensors have the characteristics of high measurement accuracy, stable operation, and temperature compensation. They are widely used in manufacturing, power, metallurgical measured building materials, chemicals, food, automobiles, warehousing, ships, ships, textiles, transportation, exploration, Liquid level, level monitoring, open ditch flow detection, robot technology, food processing, and other industries can measure both liquid materials and solid materials.
Although ultrasound is widely used, as the saying goes, good gold is not enough, no one is perfect. From your previous understanding and experience of ultrasonic sensors, are there any advantages and disadvantages of ultrasonic sensors, will these advantages and disadvantages have a certain impact on our lives? This is when we understand ultrasonic sensors in-depth, Need to pay attention.
First of all, let ’s talk about the working principle of the ultrasonic sensor: the ultrasonic sensor is a sensor developed using the characteristics of ultrasonic waves. The ultrasonic probe is mainly composed of piezoelectric chips, which can both transmit and receive ultrasonic waves. The piezoelectric ultrasonic generator actually uses the resonance of the piezoelectric crystal to work. It has two piezoelectric chips and a resonance plate. When the frequency of the pulse signal applied to its poles is equal to the natural oscillation frequency of the piezoelectric wafer, the piezoelectric wafer will resonate and drive the resonance plate to vibrate, which will generate ultrasonic waves. Conversely, if no voltage is applied between the two electrodes when the resonance plate receives ultrasonic waves, it will press the piezoelectric wafer to vibrate and convert mechanical energy into electrical signals. At this time, it becomes an ultrasonic receiver. Low-power ultrasonic probes are mostly used for detection. They have many different structures and can be divided into straight probes (longitudinal waves), oblique probes (transverse waves), surface probes (surface waves), lamb wave probes (lamb wave), and dual probes One probe reflects and one probe receives).
Secondly, the use of ultrasonic characteristics to measure objects has many advantages. That is because ultrasonic waves have the characteristics of high frequency, short wavelength, and small diffraction phenomena, especially good directivity, and can be ray and directional propagation. Ultrasonic waves have a great ability to penetrate liquids and solids, especially in opaque sun solids, which can penetrate a depth of tens of meters. Ultrasonic waves encountering impurities or interfaces will produce significant reflections and form reflections into echoes, and touching moving objects can produce the Doppler effect. Sensors developed based on ultrasonic characteristics are called "ultrasonic sensors" and are widely used in industry, national defense, biomedicine, etc.
However, because the Curie point of the piezoelectric material is generally relatively high, especially the ultrasonic sensor used for diagnosis uses a small ultrasonic sensor, the working temperature is relatively low, and it can work for a long time without failure. Medical ultrasound probes have relatively high temperatures and require separate refrigeration equipment. The sensitivity mainly depends on the wafer itself. The electromechanical coupling coefficient is large and the sensitivity is high; otherwise, the sensitivity is low. There are three reasons:
1.The frequency of current ultrasonic sensors is relatively fixed. For example, a 40KHz sensor can only be used at 38-42KHz. Other frequencies are similar. At present, sensors with a wide frequency range are hardly seen, such as 40KHz ~ 500KHz ;
2.The driving voltage is relatively high, generally between 100Vp-p and 1500Vp-p. In many low-voltage devices, a pulse transformer is required to boost, but it will also bring some complicated problems. If there is a sensor with 3 ~ 5V low voltage drive (larger power), it will be better;
3.The sensitivity should be higher.
It can be seen that the ultrasonic sensor can emit, receive and analyze the sound that our human ear cannot detect. In terms of detection, the use of ultrasonic sensors can achieve functions such as ultrasonic ranging and ultrasonic flaw detection, which can be used to detect submarine shipwrecks, enemy submarines, and display metal internal injuries. These can be applied to various technical fields such as industry, agriculture, light industry and medical treatment, which are closely related to our lives.