Parameters and knowledge of ultrasonic transducers

The technical problem to be solved for ultrasonic transducers is to design an ultrasonic transducer with a long operating distance and wide frequency band. The present invention consists of a casing, matching layer, piezoelectric ceramic disc transducer, backing, lead out cable, and a Cymbal array receiver. The piezoelectric ceramic disc transducer is made of PZT-5 piezoelectric material with thickness polarization. The Cymbal array receiver consists of 8-16 Cymbal transducers, two metal rings, and rubber washers. Piezoelectric ceramic disc transducer is used as a basic ultrasonic transducer, which emits and receives ultrasonic signals; The Cymbal array receiver is located on top of a circular piezoelectric transducer and serves as an ultrasonic receiver for receiving Doppler echo signals outside the frequency band of the circular transducer. The effective distance of the present invention is greater than 35m, the frequency band width reaches 10kHz, and it can detect high-speed moving long-distance targets. The ultrasonic transducer comprises a casing (1), a matching layer, i.e. a sound window (2), a piezoelectric ceramic disc transducer (3), a backing (4), and an outgoing cable (5), characterized in that it also includes a Cymbal array receiver, which is composed of outgoing cables (6), 8-16 Cymbal transducers (7), metal rings (8), (9), and rubber washers (10); The Cymbal array receiver is located on top of the disc piezoelectric transducer 3; Piezoelectric ceramic disc transducer is used as a basic ultrasonic transducer, which emits and receives ultrasonic signals; The Cymbal array receiver is located on top of a circular piezoelectric transducer and serves as an ultrasonic receiver for receiving Doppler echo signals outside the frequency band of the circular transducer.

Testing of ultrasonic transducer parameters and impedance tester

Impedance analyzer can be used to evaluate the performance of various devices and equipment, such as piezoelectric ceramic sheets, piezoelectric transducers, and the entire vibration system (ultrasonic transducers plus amplitude converters, molds). Using an impedance analyzer to analyze ultrasonic device equipment, several important parameters are as follows: 1 Fs: Mechanical resonance frequency, which refers to the working frequency of the vibration system and should be designed as close as possible to the expected value. For cleaning machines, the higher the consistency of the resonant frequency of the oscillator, the better. For plastic welding machines or ultrasonic processing, if the design of the amplitude lever or mold is unreasonable, the resonant frequency of the oscillator will deviate from the working point. 2. Gmax: Conductivity during resonance, the conductivity value during the operation of the vibration system, which is the reciprocal of the dynamic resistance. Under the same support conditions, the larger the better, Gmax=1/R1. Generally, for cleaning or welding oscillators, it is between 50ms and 500ms. If it is too small, generally speaking, there will be problems with the operation of the oscillator or vibration system, such as circuit mismatch, low conversion efficiency, and short oscillator life. 3. C0: The capacitance of the static branch in the equivalent circuit of the piezoelectric component of the ultrasonic transducer, C0=CT-C1 (where CT is the free capacitance at 1kHz and C1 is the capacitance of the dynamic branch in the equivalent circuit of the piezoelectric component). When using, balance C0 with inductance. In the circuit design of cleaning machines or ultrasonic processing machines, correctly balancing C0 can improve the power factor of the power supply. There are two methods of using inductance balance: parallel tuning and series tuning. 4. The mechanical quality factors of ultrasonic transducers are determined by the conductivity curve method, with Qm=Fs/(F2-F1). The higher the Qm, the better, as the higher the efficiency of the oscillator; But it must be matched with the power supply. When the Qm value is too high, the power supply cannot match. For cleaning the oscillator, the higher the value, the better. Generally speaking, the Qm for cleaning the oscillator should reach 500 or above. If it is too low, the efficiency of the oscillator will be low. For ultrasonic processing of ultrasonic transducers, the Qm value of the oscillator itself is generally around 500. After adding the amplitude lever, it generally reaches around 1000, and with the addition of the mold, it generally reaches 1500-3000. If it is too low, the vibration efficiency will be low, but it cannot be too high because the higher the Qm, the narrower the working bandwidth, making it difficult to match the power supply, making it difficult for the power supply to work at the resonant frequency point, and the equipment cannot work. 5. F2, F1: The half power point frequency of the oscillator. For the entire vibration system of ultrasonic machining (including the amplitude converter and mold), F2-F1 should be greater than 10Hz. Otherwise, the frequency band is too narrow, making it difficult for the power supply to work at the resonant frequency point and the equipment cannot work. F2-F1 is directly related to the Qm value, where Qm=Fs/(F2-F1). 6. Fp: Anti resonant frequency, the resonant frequency of the parallel branch of the piezoelectric oscillator, at which the impedance of the piezoelectric oscillator is high. 7. Zmax: Anti resonant impedance. Under normal circumstances, the anti resonant impedance of a transducer is several thousand ohms or more. If the anti resonant impedance is relatively low, the lifespan of the oscillator is often shorter. 8. CT: The capacitance value of the ultrasonic transducer free capacitance and piezoelectric components at a frequency of 1kHz, which is consistent with the value measured by a digital capacitance meter. By subtracting the dynamic capacitance C1 from this value, the true static capacitance C0 can be obtained. C0 needs to be balanced with an external inductor, and C1 participates in energy conversion during system operation and does not need to be balanced. 9. R1: Dynamic resistance, the resistance of a series branch of a piezoelectric oscillator, the smaller the better under the same support conditions. For cleaning or welding the oscillator, if R1 is too large, it indicates that there is a problem with the oscillator. 10. Keff: Effective electromechanical coupling coefficient. Generally speaking, the higher the Keff, the higher the conversion efficiency