ultrasonic sensor

Release date：2019-05-15 Number of views：

Ultrasonic sensor is a kind of sensor that converts ultrasonic signal into other energy signal (usually electrical signal). Ultrasonic wave is a mechanical wave whose vibration frequency is higher than 20kHz. It has the characteristics of high frequency, short wavelength, small diffraction phenomenon, especially good directivity, and can become a ray and propagate directionally. Ultrasonic has great penetration ability to liquid and solid, especially in the solid with opaque sunlight. When the ultrasonic wave touches the impurity or interface, it will produce significant reflection and echo, and when it touches the moving object, it will produce Doppler effect. Ultrasonic sensors are widely used in industry, national defense, biomedicine and so on.

component

The commonly used ultrasonic sensors are composed of piezoelectric chips, which can transmit and receive ultrasonic waves. Low power ultrasonic probe is mostly used for detection. It has many different structures, including straight probe (longitudinal wave), oblique probe (transverse wave), surface wave probe (surface wave), Lamb wave probe (Lamb wave), double probe (one probe transmitting and one probe receiving), etc.

performance index

The core of ultrasonic probe is a piezoelectric chip in its plastic or metal jacket. There are many kinds of materials that make up wafers. Chip size, such as diameter and thickness are also different, so the performance of each probe is different. We need to know its performance in advance before using it. The main performance indexes of ultrasonic sensor include:

working frequency

The working frequency is the resonant frequency of the piezoelectric chip. When the frequency of the AC voltage applied to both ends of the chip is equal to the resonant frequency of the chip, the output energy is larger and the sensitivity is higher.

working temperature

Because the Curie point of piezoelectric materials is generally high, especially the power of ultrasonic probe for diagnosis is small, so the working temperature is relatively low, and it can work for a long time without failure. The temperature of ultrasonic probe used in medical treatment is relatively high, which needs separate refrigeration equipment.

sensitivity

It's mainly up to the chip itself. Large electromechanical coupling coefficient and high sensitivity; On the contrary, the sensitivity is low.

Directivity

Detection range of ultrasonic sensor

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