An ultrasonic sensor is an instrument that uses a transducer to transmit and receive ultrasonic pulses that relay information about the proximity of an object such that the ultrasonic waves measure the distance to the object.

First, the principle of ultrasonic sensors

The ultrasonic sensor is a sensor that is developed using the characteristics of ultrasonic waves. Ultrasonic wave is a kind of mechanical wave whose vibration frequency is higher than sound wave. It is generated by the vibration of the transducer wafer under the excitation of voltage. It has high frequency, short wavelength, small diffraction phenomenon, especially good directionality, and can be oriented as a ray. Characteristics such as communication. Ultrasonic penetration of liquids and solids is very large, especially in sunlight opaque solids, which can penetrate depths of several tens of meters. When an ultrasonic wave hits an impurity or an interface, it will produce a significant reflection to form a reflection into an echo, which can produce a Doppler effect when it hits a moving object. Therefore, ultrasonic testing is widely used in industrial, national defense, biomedical and other fields. Ultrasound is used as a detection means, and ultrasonic waves and ultrasonic waves must be generated. The device that performs this function is an ultrasonic sensor, which is customarily called an ultrasonic transducer, or an ultrasonic probe.

The ultrasonic probe is mainly composed of a piezoelectric wafer, which can emit ultrasonic waves as well as ultrasonic waves. Small power ultrasound probes are used for detection. It has many different configurations, which can be divided into straight probe (longitudinal wave), oblique probe (transverse wave), surface wave probe (surface wave), Lamb wave probe (Lamp wave), dual probe (one probe reflection, one probe reception) Wait.

The core of the ultrasound probe is a piezoelectric wafer in its plastic jacket or metal jacket. There are many kinds of materials constituting the wafer. The size of the wafer, such as the diameter and thickness, is different, so the performance of each probe is different, we must know its performance before use. The main performance indicators of ultrasonic sensors, including;

1. Working frequency. The operating frequency is the resonant frequency of the piezoelectric wafer. When the frequency of the alternating voltage applied to both ends thereof is equal to the resonant frequency of the wafer, the output energy is the largest and the sensitivity is also high.

2. Working temperature. Since the Curie point of the piezoelectric material is generally high, in particular, the diagnostic ultrasonic probe uses less power, so the operating temperature is relatively low, and it can work for a long time without causing failure. Medical ultrasound probes are relatively hot and require separate refrigeration equipment.

3. Sensitivity. It mainly depends on the manufacture of the wafer itself. The electromechanical coupling coefficient is large and the sensitivity is high; on the contrary, the sensitivity is low.

Second, the ultrasonic sensor structure

The ultrasonic sensor is mainly composed of the following four parts:

Transmitter: Vibrates by a vibrator (typically a ceramic product, approximately 15 mm in diameter) to generate ultrasonic waves and radiate into the air.

Receiver: When the vibrator receives the ultrasonic wave, it generates corresponding mechanical vibration according to the ultrasonic wave and converts it into electric energy as the output of the receiver.

Control section: Controlling the ultrasonic transmission of the transmitter by using an integrated circuit, and judging whether the receiver receives the signal (ultrasonic wave) and the size of the received signal.

Power supply part: The ultrasonic sensor is usually powered by an external DC power supply with a voltage of DC12V ± 10 % or 24V ± 10 %, and is supplied to the sensor via an internal voltage regulator circuit.

Third, ultrasonic sensor application

Ultrasonic distance sensor can be widely used in level (liquid level) monitoring, robot anti-collision, various ultrasonic proximity switches, and anti-theft alarm and other related fields, reliable operation, easy installation, waterproof type, small launch angle and high sensitivity. It is convenient to connect with industrial display instruments, and also provides probes with large launch angles.

1. Ultrasonic range finder:

Jianheng Instrument's ultra-high-energy acoustic ranging technology JH-UHZ series products have made a major breakthrough in ultrasonic ranging technology. It not only broadens the application of ultrasonic ranging technology (for extremely harsh working environments), but also uses intelligent adjustment. Technology has greatly improved the reliability and performance indicators of ultrasonic products, allowing users to use no worries. .

Excellent echo processing technology, the ultra-high-strength wave frequency of 5-50KHZ enables the maximum range of the Jianheng level meter to reach 120 meters, and the applicable medium temperature is –20°C- +175°C. The intelligent automatic adjustment of the wave frequency and the automatic temperature difference compensation function make the work more stable and reliable. JH-UHZ series products also have flexible and variable working modes (power supply can be 12VDC, 24VDC, 110VAC, 220VAC; two/three/four wire system can be combined in the same instrument. It also has advanced remote GSM, CDMA, Internet debugging features enable users to get technical support at any time.

With its cutting-edge technology and stable and reliable work quality, Jianheng products are widely used in chemical, electric power, metallurgy, coal mine, dock, water treatment, light industry and food hygiene industries.

2. Ultrasonic fish finder:

The principle of ultrasonic measurement technology is very simple. The name of the high-end point is called “Doppa effect”, and the children of Shancun are called “Echo”, just like “How are you?” in a valley, I will hear it as if someone is learning. Your words are the same "you...good...?". From this point, people have developed ultrasonic measurement technology. Like in nature, bats can be counted as representative. In the bat cave, both foraging and sonic ranging are required. It is very difficult to use ultrasonic ranging in the cave. Very advanced technology products. Can't do it either. In the air, when the sound agitates the air and transmits the message forward, when it encounters an object of different size and hardness, it will produce a correspondingly strong and weak reflected sound, and we receive the sound of the fan back at the peak, and calculate The time gap between the fan bombs, so that you can understand the distance between the front object and you, the strength of the fan bomb, the size of the object, this is the application principle of ultrasonic measurement in the air, just like the radar used in the airport.

There is a difference in the water, because the density of water is significantly different from the density of air. The same intensity of sound, water transfer and airborne transmission are completely two-fold. Therefore, we use ultrasonic detection in water, the prerequisite is power. Powerful, in order to have the signal that the fan bounced back. In the 1950s, the submarine search technology of the American HAI Army was fully developed. It is not easy to search for submarines, let alone the fish that are much smaller than the submarine. To make a breakthrough, we must first find out the subtleties from the characteristics of ultrasonic waves. In addition to its powerful power, its frequency is also decisive, and the analysis technology after receiving signals is even more indispensable. It is quite difficult to distinguish the appropriate data among many signals. For this reason, in the aftermath of the continuous development of the American folk, it was gradually begun to have a fishing boat installed with an ultrasonic fish finder designed to search for fish. Up to now, the ultrasonic detection technology used in the ocean, whether it is theory or product, is mainly in the United States, and later in Japan and Germany, it has only been added in recent years.

Application in medical testing: B-ultrasound

Ultrasonic sensor for detecting liquid level:

Acoustic diffuse reflection proximity sensor for detecting liquid level;

Acoustic reflection design is used to detect distant targets;

The acoustic proximity sensor can have an analog output for accurate continuous control.

The linear slope of the analog output signal and the distance of the measured object is adjustable to meet various control requirements;

The sonic proximity sensor can have two switch point settings and can be easily set by buttons;

The square and original cylindrical design meets different field installation requirements.

3, the application of ultrasonic sensors in quality inspection - ultrasonic flaw detector

The ultrasonic flaw detector is mainly used for the quality inspection inside the metal workpiece, such as detecting whether the metal has air bubbles, whether the welded part has defects such as incomplete penetration.

With the rapid development of science and technology, ultrasonic applications will become more and more widely used in sensors. In the industrial revolution of human civilization, sensing technology has always played an important role as a pioneer. It is a key technology that runs through various technologies and applications. It is almost ubiquitous in all areas that people can imagine. Sensors are one of the fastest growing industries in the world. With the joint efforts of research, production and application departments in various countries, sensor technology has developed rapidly and progressed. However, as far as the current state of the art is concerned, the sensor technology that people can specifically use is still very limited. Therefore, this is a technology and industry field that is booming and has unlimited prospects.

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