超音波的使用（Use of ultrasound）.docVIP

超音波的使用（Use of ultrasound） Because of the rapid development and breakthrough of the electronic technology, the price and volume of the circuit have been improved greatly. Therefore, the range of ultrasonic applications has been expanded. Especially ultrasonic components, magnetic materials, deformation of newly discovered piezoelectric materials, electro deformation and development, will lead to more efficient vibration appearance and practicality, expand the application of ultrasound is the point the day and await for it. We in the meantime, the characteristics and application of ultrasound to know more, for the super single wave has a deeper knowledge, and be practical. (a) the frequency range of 1, the basic characteristics of ultrasound ultrasound: Piano, percussion, can hear the sound, this is because the instruments of vibration, the nearby air, transmitted to the human ear, the vibration of the eardrum, causing the auditory nerve to sound feeling. The sound depends on the number of vibrations, and the intensity of the sound depends on the magnitude of the vibration amplitude. The general ear audible frequency range is 16Hz~20KHz, but the limits of this frequency range, will be due to sound intensity or personal hearing, so the sound sense range of human ear can be roughly as if the diagram is shown in 7-1. This is the seventh chapter, the ultrasonic frequency ultrasonic sensor is not easy to determine the lower bound on the number of course, usually more than 20KHz sonic called (Ultrasonic wave) ultrasound. But hearing and hearing are just human ear feelings. Sometimes, in order to work together, the frequency is reduced to 10KHz, but sometimes the frequency is raised to 1000MHz. Type 2, ultrasonic launch mode: ultrasound is different, resulting in different types of ultrasound, can be broadly divided into five categories, as shown in Figure 7-2, figure (a) P (Longitudinal wave P wave) also called compression wave (compression wave), are consistent with the di