The principle of ultrasonic sensor generating ultrasonic waves
When a pulse electrical signal with a frequency of 40KHz is input from the ultrasonic transmitting sensor, the piezoelectric crystal will vibrate due to deformation, and the vibration frequency is above 20KHz, thus forming ultrasonic waves. Then the ultrasonic wave is resonantly amplified by the conical resonant disk and then emitted in a direction. After the receiving sensor receives the emitted ultrasonic signal, it causes the piezoelectric chip to deform to generate an electrical signal, and the electrical signal is amplified through the amplifier.
The ultrasonic sensor transmitter uses the piezoelectric effect to generate ultrasonic waves. That is, when the transmitter continuously gives a voltage signal of a certain frequency, such as 40KHz, ultrasonic waves can be generated. You can consider using a single-chip microcomputer to implement it. Of course, if the power is not high, you can use a single-chip microcomputer to implement it. There are two main frequencies of ultrasonic sensors, 25KHz and 40KHz.
Ultrasound is a sound wave with a frequency greater than 20KHz. The transmitting sensor itself emits ultrasonic waves and then receives feedback ultrasonic waves. The receiving ultrasonic sensor itself does not emit ultrasonic waves. It receives ultrasonic waves through the sensor and converts them into electrical signals for measurement. Ultrasonic sensors are sensors developed using the characteristics of ultrasonic waves.
Ultrasound is a mechanical wave with a vibration frequency higher than that of sound waves. It is generated by the vibration of the transducer chip under the stimulation of voltage. It has high frequency, wave length and small diffraction phenomenon. In particular, it has good deflection and may become rays and be directional. Dissemination and other features. When ultrasonic waves encounter impurities or interfaces, they will be significantly reflected to form echoes. When ultrasonic waves encounter moving objects, the Doppler effect will occur. Therefore, ultrasonic testing is widely used in industry, national defense, biomedicine, etc.
The task frequency is the resonant frequency of the piezoelectric chip. When the frequency of the AC voltage applied to both ends is consistent with the resonant frequency of the chip, the output energy is high and the sensitivity is also high. Sensitivity: mainly depends on the chip itself. The electromechanical coupling coefficient is large, and the sensitivity is high; on the contrary, the sensitivity is low. Because the Curie point of piezoelectric materials is generally relatively high, especially diagnostic ultrasonic probes use less power, so the working temperature is relatively low and they can work for a long time without failure. The temperature of the probe of the medical ultrasonic sensor is relatively high and requires separate refrigeration equipment.
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