piezoelectric transducer to measure displacement

Publish Time: 2018-03-22     Origin: Site

                     piezoelectric transducer to measure displacement


  Piezoelectric ultrasonic transducers are using the piezoelectric effect of piezoelectric materials. The polarized PZT material piezo platesundergoes mechanical deformation under the applied electric field. This is called the inverse piezoelectric effect. Conversely, the mechanical deformation of the piezoelectric material also generates the voltage. This is called the positive piezoelectric effect. piezo energy harvestingis using the inverse piezoelectric effect, high-frequency voltages can be converted into high-frequency mechanical vibrations to generate ultrasonic waves; the positive ultrasonic vibrations can also be used to convert receiving ultrasonic vibrations into electrical signals. This is how the ultrasonic transducer works. Piezoelectric ultrasonic transducers can be seen as four-terminal networks with electrical and mechanical ends. Piezoelectric materials of piezo block crystal is making ultrasonic transducers include piezoelectric single crystals, it is polycrystalline piezoelectric ceramics, piezoelectric polymers, piezoelectric composites. Among them, lead zirconate titanate piezoelectric disc crystal have the advantages of high mechanical strength, temperature and humidity resistance, low cost, and good electromechanical coupling effect, and have been widely used in ultrasonic transducers. Ultrasonic transducers are used in the ultrasonic range finders. Using lead zirconate titanate piezoelectric ceramics is vibrator materials.



  Piezoelectric ceramics vibrate under the application of an alternating electric field which excites ultrasonic waves. Piezoelectric ceramic is commonly used vibration modes are stretching vibration, piezoelectric ultrasonic transformeris bending vibration and shear vibration. The commonly is used for vibration mode of piezoelectric ceramic vibrator,which is divided into length vibration mode, radial vibration mode and thickness vibration mode. Figure shows the wafer thickness stretching vibration mode. The vibrator of 1.7MHZ piezoelectric ring is in the form of a circular plate. The polarization direction and the applied electric field are all parallelled to the thickness direction, and the vibrator vibrates along the thickness direction. The fundamental resonant frequency of this vibration mode is inversely proportional to the thickness, the applicable frequency range is 30 to 100 kHz, and the relative bandwidth is within 1% to 4%.


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