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What Are Ultrasonic Sensors ,How To Use Ultrasonic Sensors

What Are Ultrasonic Sensors ,How To Use Ultrasonic Sensors

August 29 , 2023 0

Ultrasonic sensors are transducers that convert ultrasonic signals into other energy signals (usually electrical). Ultrasonic waves are mechanical waves with a vibration frequency higher than 20kHz. It has a high frequency, short wavelength, small bypass phenomenon, especially good directionality, can become a ray and directional propagation and other characteristics. Ultrasonic waves on the liquid, solid penetration ability is great, especially in the sun opaque solid. Ultrasonic waves encountered impurities or interfaces will produce significant reflection of the formation of reflective echoes, encountered the Doppler effect can be generated by moving objects. Ultrasonic sensors are widely used in industry, defense, biomedical and other aspects.

Characteristics And Principles OF Ultrasonic Sensors

Ultrasonic sensors use "ultrasonic waves", a kind of sound waves. 20kHz or more, the human ear can not hear the sound is called ultrasonic waves.
Depending on the frequency band, ultrasonic waves can propagate in any medium such as gases, liquids and solids, but the propagation speed depends on the acoustic impedance of the medium.

Ultrasonic waves are used in a variety of ways, such as distance detection using the reflection of ultrasonic waves, and presence detection for detecting ultrasonic fluctuations. In distance detection uses, unlike optical distance sensors, it also has the characteristic of being able to detect substances such as transparent plastics and glass.
The principle of ultrasonic sensors utilizes the property that piezoelectric ceramics expand and contract in response to the direction of voltage and generate air vibrations (ultrasonic waves).

Ultrasonic Sensor Components Commonly Used Ultrasonic

Commonly used ultrasonic transducers consist of piezoelectric wafers that both emit and receive ultrasonic waves. The low-power ultrasonic probe is mostly used as a probe. It has many different structures, which can be divided into straight probe (longitudinal wave), oblique probe (transverse wave), surface wave probe (surface wave), Lamb wave probe (Lamb wave), double probe (one probe transmits, one probe receives) and so on.

Ultrasonic Sensors Main Application Areas

Ultrasonic sensing technology is used in different aspects of production and practice, and medical application is one of its most important applications, the following medicine as an example to illustrate the application of ultrasonic sensing technology. The main application of ultrasound in medicine is to diagnose diseases, and it has become an indispensable diagnostic method in clinical medicine. The advantages of ultrasound diagnosis are: no pain, no damage to the examinee, simple method, clear image, diagnostic accuracy and so on. Therefore, it is easy to popularize and welcomed by medical workers and patients. Ultrasound diagnosis can be based on different medical principles, let's take a look at one of the representative so-called A-type method. This method utilizes the reflection of ultrasound waves. When ultrasound waves propagating through human tissue encounter two layers of a medium interface with different acoustic impedances, a reflected echo is generated at that interface. Each time a reflective surface is encountered, the echo is displayed on the screen of an oscilloscope, and the difference in impedance between the two interfaces also determines the amplitude of the echo.
In industry, the typical applications of ultrasound are both non-destructive testing of metals and ultrasonic thickness measurement. In the past, many technologies have been hindered by the inability to detect the inside of an object's tissue, and the advent of ultrasonic sensing technology has changed this situation. Of course, more ultrasonic sensors are fixed in different devices, "silent" to detect the signal people need. In future applications, ultrasound will be combined with information technology, new materials technology, there will be more intelligent, highly sensitive ultrasonic sensors.
Ultrasonic distance sensor technology applications
Ultrasonic penetration of liquids, solids, especially in opaque solids, it can penetrate the depth of tens of meters.
Ultrasonic waves encountered impurities or interfaces will produce significant reflections form reflections into echoes, encountering active objects can produce the Doppler effect. Therefore, ultrasonic detection is widely used in industry, defense, biomedical and other aspects.
Ultrasonic distance sensors can be widely used in level monitoring, robot collision avoidance, various ultrasonic proximity switches, as well as anti-theft alarms and other related fields, reliable, easy to install, waterproof, small launch angle, high sensitivity, easy to connect with the industrial display instrumentation, but also provides a larger launch angle of the probe.

The Working Principle OF Ultrasonic Sensor

People can hear the sound is due to the vibration of the object, its frequency in the range of 20HZ-20KHZ, more than 20KHZ is called ultrasonic, less than 20HZ is called infrasound. Commonly used ultrasonic frequency of tens of KHZ - tens of MHZ.
Ultrasound is a mechanical oscillation in an elastic medium, there are two forms: transverse oscillation (transverse wave) and longitudinal oscillation (longitudinal wave). In industrial applications mainly use longitudinal oscillation. Ultrasonic waves can propagate in gases, liquids and solids at different speeds. In addition, it also has refraction and reflection phenomena, and there is attenuation in the propagation process. Ultrasonic propagation in the air, its frequency is low, generally tens of KHZ, while in the solid, liquid is available in higher frequency. Faster attenuation in the air, while in the liquid and solid propagation, attenuation is smaller, spread farther. The use of ultrasonic characteristics, can be made into a variety of ultrasonic sensors, with different circuits, made of a variety of ultrasonic measuring instruments and devices, and in communications, medical home appliances and other aspects of a wide range of applications.

Ultrasonic transducer main materials are piezoelectric crystal (electrostrictive) and nickel-iron aluminum alloy (magnetostrictive) two types. Electrostrictive materials such as lead zirconate titanate (PZT). Piezoelectric crystal ultrasonic transducer is a reversible sensor, it can convert electrical energy into mechanical oscillation and produce ultrasonic waves, at the same time it receives ultrasonic waves, can also be converted into electrical energy, so it can be divided into transmitter or receiver. Some ultrasonic sensors can be used as both transmitter and receiver. Here only introduce small ultrasonic sensors, send and receive a slight difference, it is suitable for propagation in the air, the working frequency is generally 23-25KHZ and 40-45KHZ. these sensors are suitable for distance measurement, remote control, anti-theft and other purposes. This kind of T / R-40-16, T / R-40-12, etc. (which T said to send, R said to receive, 40 said the frequency of 40KHZ, 16 and 12 said the size of its outer diameter, in millimeters). There is another sealed ultrasonic sensor (MA40EI type). It is characterized by its waterproof function (but can not be put into the water), and can be used as a material level and proximity switch, which has a better performance. There are three basic types of ultrasonic applications. Transmissive type is used for remote control, burglar alarms, automatic doors, proximity switches, etc.; Separate reflective type is used for ranging, liquid level or material level; Reflective type is used for material flaw detection, thickness measurement, etc.

By the sending sensor (or wave transmitter), receiving sensor (or wave receiver), control part and power supply part. Transmitter sensor by the transmitter and the use of ceramic vibrator transducer diameter of 15mm or so, the role of the transducer is the ceramic vibrator electrical vibration energy into super-energy and radiate into the air; and receive the sensor by the ceramic vibrator transducer and amplifier circuit, the transducer receives the wave mechanical vibration, which will be converted into electrical energy as the sensor receiver's output, so as to send the ultrasonic signal Detection. In practice, the ceramic oscillator used as a transmitter sensor can also be used as a receiver sensor society ceramic oscillator. The control section mainly controls the frequency, duty cycle and sparse modulation of the pulse chain sent from the transmitter, as well as the counting and detection distance.

The Ultrasonic Sensor Consists OF Four Main Parts:

Transmitter: the vibration of the oscillator (generally ceramic products, about 15 mm in diameter) generates ultrasonic waves and radiates them into the air.
Receiver: the oscillator receives the ultrasonic waves, according to the ultrasonic waves occur corresponding mechanical vibration, and will be converted into electrical energy, as the output of the receiver.
Control section: the ultrasonic wave sent by the transmitter is controlled by an integrated circuit, and determines whether the receiver receives the signal (ultrasonic wave), and the size of the received signal.
Power supply section: ultrasonic sensors are usually powered by an external DC power supply with a voltage of DC12V ± 10 % or 24V ± 10 %, which is supplied to the sensors via an internal voltage regulator circuit.