piezoelectric ceramics transducer for transformer application

Piezoelectric transformer is based on the principle of positive and negative piezoelectric effect, by using the resonant characteristics of piezoelectric vibrator, fabricated by ferroelectric piezo ceramic crystal quartz through sintering, high-voltage polarization and other processes, which can realize the mutual conversion between machine electrical energy. Piezoelectric transducer. Compared with the traditional iron core wound electromagnetic transformer, it has small volume, light weight, there is no breakdown during usage, it is high temperature resistance of the transformer itself, there is no fear of burning and no electromagnetic interference, and simple structure, easy to manufacture and easy to manufacture. The advantages of mass production just meet the development trend of today's electronics industry integration. Therefore, piezoelectric transformers have been widely used in mobile communication LCD background light sources, electrostatic copiers, negative ion generators and the like.

With the widespreading use of piezoelectric devices, there is an increasing demand for higher power of piezoelectric devices in many fields of application. For example, the large-scale LCD display requires that the output power of the piezoelectric transformer for backlight power supply should be more than 6W; the practical application of the piezoelectric transformer for replacing the ballast in the traditional fluorescent lamp driving circuit requires the output power of the piezoelectric transformer. To reach 30W or even higher. High power piezoelectric ceramics are developed on the basis of such requirements, based on the modification of traditional piezoelectric ceramics, with the high mechanical quality factor (Qm), electromechanical cohesion coefficient (Kp) and low dielectric loss. (tan S) and other characteristics of piezoelectric ceramics with superior performance.

(1) High electromechanical cohesion coefficient Kp and large quality factor Mo=(d33/s33); Kp is used to characterize the mutual conversion efficiency of piezoelectric vibrator power. To achieve high output power, the material must have large electromechanical conversion efficiency.

(2) Low electrical and mechanical losses, to prevent the piezo round disc transducer vibrator from generating excessive heat during high-speed vibration and causing damage to the device.

(3) Excellent performance stability, such as the lowest possible resonance frequency coefficient TCfr and anti-aging performance, thus ensuring a long stable service life of the piezoelectric transformer, and there is no temperature rising due to loss during use. Brings a large change in output power.

(4) It must have good structural properties to ensure that the device will not be damaged due to structural problems when is operating at the high speeds. In short: "double high" - high Qm, high Kp, and "double low" a low loss, low TCfr material. At the same time, from the economic point of view, the sintering temperature of piezo ceramics should be as low as possible.