What is the difference between ultrasonic sensor and transducer?

There are some differences between Ultrasonic Sensors and Ultrasonic Transducers in function and application, as follows:

1. Different principles. Ultrasonic sensor is the use of ultrasonic wave in the object propagation time to measure the object distance or object speed, flow and other parameters, the principle is the transmitter sent by the ultrasonic reflected by the object is received by the receiver, according to the reflection time to calculate the object distance or speed; Ultrasonic transducer converts high-frequency electrical energy into mechanical energy, and converts mechanical energy into ultrasonic energy through the piezoelectric effect to achieve the conversion between energy, the principle is to use the characteristics of piezoelectric crystals, so that it deforms under the action of electric field, resulting in mechanical vibration and sound waves.

2. Different structures. The ultrasonic transducer is mainly composed of piezoelectric crystal, patch, reflector, cavity, connection and so on. Ultrasonic sensor is composed of transmitter, receiver, signal processing circuit and so on.

3. Different uses. Ultrasonic sensors are mainly used to measure object distance, speed, flow and other parameters, widely used in ranging, obstacle avoidance, smart home, medical, industrial and other fields; For example, in autonomous vehicles, ultrasonic sensors are often used to detect surrounding vehicles and obstacles. Ultrasonic transducers are widely used in ultrasonic imaging, non-destructive detection, cleaning and liquid level measurement, mainly used in ultrasonic cleaning.

The main function of ultrasonic sensors is to convert ultrasonic signals into other energy signals (usually electrical signals). Ultrasonic wave is a mechanical wave with a vibration frequency higher than 20kHz, which has the characteristics of high frequency, short wavelength, small diffraction phenomenon, good directivity, and directional propagation. The penetration of ultrasonic waves to liquids and solids is very large, especially in solids that are opaque to sunlight. When the ultrasonic wave hits the impurities or the interface, it will produce significant reflection to form a reflection echo, and it can produce Doppler effect when it hits the moving object. Ultrasonic sensors are widely used in industry, national defense, biomedical and other aspects, such as echo sounder, Doppler log and harmonic correlation log.

The transducer is a device that converts electrical energy and sound energy into each other. In the echo sounder, Doppler log and harmonic correlation log, the transducer converts electrical energy into sound energy (transmitting transducer) or converts sound energy into electrical energy (receiving transducer). Transmitting and receiving transducers are usually used separately, but one can also be shared. The main performance indexes of the transducer include operating frequency, frequency band width, electro-acoustic frequency, impedance at resonant frequency, directivity (transmitting beam width) and sensitivity.