What Are the Parameters That Affect the Ultrasonic Transducer?

Ultrasonic transducer plays a very important role in ultrasonic welding machine. A high-quality ultrasonic transducer can ensure strong and stable output power. Only when you understand the parameters of the ultrasonic transducer, you can accurately match with your ultrasonic generator. So, There are the parameters that affect the medical ultrasonic transducer as follow.


Ⅰ. Mechanical resonance frequency of ultrasonic transducer (Fs)


This refers to the working frequency of the vibration system of the ultrasonic surgical instrument, which shall be as close to the expected value as possible in the design and must match the working point of the power supply. Contact BBT medical for more high frequency ultrasonic transducer info!


Ⅱ. Ultrasonic transducer dynamic resistance (R1)


The resistance of the series branch of the piezoelectric vibrator is as small as possible under the same support conditions! For cleaning or welding vibrator, it is generally between 5 Ω and 20 Ω. If it is too large, the vibrator or vibration system will have problems, such as circuit mismatch or low conversion efficiency, short vibrator life and so on.


Ⅲ. Mechanical quality factors of ultrasonic transducer (Qm)


It is determined by the conductivity curve method that Qm= Fs/(F2-F1). The higher the QM, the better, because the higher the Qm is, the higher the efficiency of the vibrator. However, Qm must match the power supply. When the Qm value is too high, the power supply cannot match. For cleaning the vibrator, the higher the Qm value, the better. Generally speaking, the Qm for cleaning the vibrator should reach 500-1000. If it is too low, the vibrator efficiency is low, and if it is too high, the power supply cannot be matched. For ultrasonic welding or processing, the Qm value of the vibrator itself is generally about 50-1000, and the system of  medical ultrasonic transducer is 1500-3000. If it is too low, the vibration efficiency is low, but it cannot be too high, because the higher the QM, the narrower the working bandwidth, and the power supply is difficult to match, that is, the power supply is difficult to work at the resonant frequency point, and the equipment cannot work normally.


Ⅳ. Ultrasonic transducer free capacitance (CT)


Capacitance value of piezoelectric device at 1kHz frequency, which is consistent with the value measured by digital capacitance meter. By subtracting the dynamic capacitance C1 from this value, the real electrostatic capacitance C0 can be obtained,


C0=CT-C1. C0 should be balanced with inductance during using. In the circuit design of ultrasonic machining machine, correctly balancing C0 can improve the power factor of power supply. There are two methods of inductance balance, parallel tuning and series tuning.


Ⅴ. Anti-resonance frequency of ultrasonic transducer (Fp)


The resonant frequency of the parallel branch of the piezoelectric vibrator, at this frequency, the impedance Zmax of the piezoelectric vibrator of the ultrasonic transducer is the largest. If the anti-resonant impedance Zmax is very low, there is a problem with the vibrator.

Other Articles