Ultrasonic sensor is an instrument that uses a transducer to send and receive ultrasonic pulses, which relay information about the proximity of an object to measure the distance between the ultrasonic waves and the object.

1、 Principle of Ultrasonic Sensor

Ultrasonic sensors are sensors developed using the characteristics of ultrasonic waves. Ultrasonic waves are mechanical waves with a vibration frequency higher than sound waves, generated by the vibration of a transducer chip under voltage excitation. They have the characteristics of high frequency, short wavelength, small diffraction phenomenon, especially good directionality, and the ability to propagate directionally as rays. Ultrasonic waves have a great ability to penetrate liquids and solids, especially in solids that are opaque to sunlight. They can penetrate depths of several tens of meters. Ultrasonic waves will produce significant reflections when encountering impurities or interfaces, forming echoes, and can produce Doppler effects when encountering moving objects. Therefore, ultrasonic testing is widely used in industry, national defense, biomedical and other fields. Using ultrasonic waves as a detection method, it is necessary to generate and receive ultrasonic waves. The device that completes this function is an ultrasonic sensor, commonly referred to as an * or ultrasonic probe.

Ultrasonic probes are mainly composed of piezoelectric chips, which can emit and receive ultrasonic waves. Low power ultrasound probes are commonly used for detection purposes. It has many different structures, including straight probe (longitudinal wave), oblique probe (transverse wave), surface wave probe (surface wave), Lamb wave probe (Lamb wave), dual probe (one probe reflection, one probe reception), etc.

The core of an ultrasound probe is a piezoelectric chip inside its plastic or metal casing. There can be many types of materials that make up a chip. The size of the chip, such as diameter and thickness, also varies, so the performance of each probe is different. We must understand its performance in advance before using it. The main performance indicators of ultrasonic sensors include:;

1. Working frequency. The working frequency is the resonance frequency of the piezoelectric chip. When the frequency of the AC voltage applied to both ends is equal to the resonance frequency of the chip, the output energy is high and the sensitivity is also high.

2. Working temperature. Due to the generally high Curie point of piezoelectric materials, especially when using diagnostic ultrasonic probes with lower power, the working temperature is relatively low and can work for a long time without failure. The temperature of medical ultrasound probes is relatively high and requires separate refrigeration equipment.

3. Sensitivity. It mainly depends on the manufacturing of the chip itself. High electromechanical coupling coefficient and sensitivity; On the contrary, the sensitivity is low.

2、 Ultrasonic sensor structure

Ultrasonic sensors mainly consist of the following four parts:

Transmitter: Generate ultrasonic waves through vibration of a transducer (usually a ceramic product with a diameter of about 15 mm) and radiate them into the air.

Receiver: When the oscillator receives ultrasonic waves, it generates corresponding mechanical vibrations based on the ultrasonic waves and converts them into electrical energy as the output of the receiver.

Control part: By using integrated circuits to control the ultrasonic transmission of the transmitter, and determine whether the receiver has received the signal (ultrasonic), as well as the size of the received signal.

Power supply: Ultrasonic sensors usually use an external DC power supply with a voltage of DC12V ± 10% or 24V ± 10%, which is supplied to the sensor through an internal voltage regulator circuit.

3、 Application of Ultrasonic Sensors

Ultrasonic distance sensors can be widely used in areas such as level monitoring, robot collision prevention, various ultrasonic proximity switches, and anti-theft alarms. They are reliable, easy to install, waterproof, have a small emission angle, high sensitivity, and are convenient to connect with industrial display instruments. They also provide probes with larger emission angles.

1. Ultrasonic rangefinder:

The JH-UHZ series products of Jianheng Instrument's ultra-high energy acoustic ranging technology have made significant breakthroughs in ultrasonic ranging technology. They not only broaden the application scenarios of ultrasonic ranging technology (suitable for extremely harsh working environments), but also use intelligent adjustment technology to greatly improve the reliability and performance indicators of ultrasonic wave products, allowing users to use them without worries. .

The echo processing technology, with an ultra-high intensity wave frequency of 5-50KHz, enables the building constant level gauge to reach a large range of up to 120 meters, suitable for medium temperatures ranging from -20 ℃ to+175 ℃. The intelligent fully automatic adjustment of wave frequency and automatic temperature difference compensation function make its operation more stable and reliable. The JH-UHZ series products also have flexible and versatile working modes (power supply can be 12VDC, 24VDC, 110VAC, 220VAC; The two/three/four wire system can be freely combined in the same instrument. It also has advanced remote GSM, CDMA, Internet debugging functions, so that users can get technical support at any time.

Jianheng products have been widely used in industries such as chemical, power, metallurgy, coal mining, dock, water treatment, light industry, and food hygiene due to their stable and reliable technical quality.

2. Ultrasonic fish detector:

The principle of ultrasonic measurement technology is very simple, and it is called the "Doppler effect". Children in mountain villages call it "echo", just like calling out "how are you" in a valley, and soon you hear someone say something like "you... how are you...". People are developing ultrasonic measurement technology based on this point. In nature, bats can be considered as representatives. In bat caves, it is necessary to search for food and use sound waves for distance measurement. However, using ultrasonic waves for distance measurement inside the cave is a very difficult task that even advanced technological products cannot achieve. In the air, when sound stirs the air and transmits information forward, it will produce corresponding strong and weak reflected sounds when encountering objects of different sizes and hardness. We receive the sound of this fan bouncing back at high peaks, calculate the time difference of its fan bouncing, and thus understand the distance between the object in front and you. Based on the strength of its fan bouncing, we can determine the size of the object. This is the application principle of ultrasonic measurement in the air, just like the radar used in airports.

The situation in water is different because the density of water is significantly different from that of air. Sound of the same intensity transmitted in water and in the air is two different things. Therefore, when we use ultrasonic detection in water, the prerequisite is that the power must be strong in order to have a signal that bounces back. In the 1950s, the submarine search technology of the US Navy had fully developed, and it was no longer easy to search for submarines, let alone fish much smaller than submarines. To make a breakthrough, we must first find the secrets from the characteristics of ultrasound. In addition to high power, its frequency is also decisive, and the analysis technology after receiving the signal is indispensable. It is quite difficult to distinguish appropriate data among numerous signals. As a result, with the continuous development by the American public, fishing boats gradually began to install ultrasonic fish detectors specifically designed for searching for fish. So far, the ultrasonic detection technology used in the ocean, whether in theory or in products, has been mainly based in the United States, with Japan and Germany joining in in recent years.

Application in medical testing: B-ultrasound

Ultrasonic sensor for detecting liquid level:

Acoustic diffuse reflection proximity sensor is used to detect liquid level;

Acoustic reflection design is used to detect distant targets;

Acoustic proximity sensors can have analog output and are suitable for continuous control;

The linear slope between the analog output signal and the measured object distance can be adjusted to meet various control requirements;

The acoustic proximity sensor can have two switch points and can be conveniently set through buttons;

The square and original cylindrical designs meet different on-site installation requirements.

3. Application of Ultrasonic Sensors in Quality Inspection - Ultrasonic Flaw Detector

Ultrasonic flaw detectors are mainly used for quality inspection of metal workpieces, such as detecting whether there are bubbles in the metal and whether there are defects such as incomplete penetration in the welding area.

With the rapid development of science and technology, the application of ultrasound in sensors will become increasingly widespread. In the various industrial revolutions of human civilization, sensing technology has always played an important role as a pioneer. It is a key technology that runs through various technological and application fields, and in almost every imaginable field, it is. Sensors are one of the rapidly developing industries in countries around the world. With the joint efforts of relevant research, production, and application departments in various countries, sensor technology has made rapid progress and development. However, with the current level of technology, the specific sensing technologies that people can utilize are still very limited. Therefore, this is a thriving and infinitely promising field of technology and industry