The polarization direction and vibration direction of the piezoelectric ceramics are along the thickness direction. Therefore, the input and output part of the piezoelectric ceramic resonator of the thickness vibration mode piezoelectric ceramics are longitudinal vibration modes, and the thickness vibration mode of piezoelectric ceramic transformer belongs to low voltage transformer with low voltage gain.
It consists of two or more piezoelectric ceramic discs polarized in the thickness direction. Therefore, although the polarization and excitation directions are the same as those of the thickness mode of piezoelectric ceramic transformer and the radial mode piezoelectric ceramic transformer with PZT material parameter.The vibration direction is different from the thickness mode piezoelectric transformer. The vibration direction is along the radius of the wafer. Since the vibration direction is perpendicular to the polarization direction, the radial mode piezoelectric ceramic transformer belongs to the transverse vibration mode transformer. The voltage conversion range is between Rosen between a piezoelectric transformer and a thickness mode piezoelectric transformer.
A Rosen-type piezoelectric transformer is operating in a third-order vibration mode. The input end of the PZT piezoelectric ceramic transformer is composed of two pieces of piezoelectric ceramic slenders of the same lateral vibration mode and the output end,which is located the two input piezoelectric ceramics. The output electrode is located at the geometric center of the transformer. By selecting the material and geometry of the input and output sections of the transformer, the three components of the transformer are respectively resonated to the half-wavelength resonance state, so the geometric center is exactly the displacement node, and the output connection line does not affect the transformer and vibration state. The output impedance of the Rosen-type piezoelectric ceramic transformer in the third-order vibration mode is only one quarter of that of the conventional vibration mode piezoelectric ceramic transformer, so that it can output higher electric power.High power multilayer ultrasound piezoelectric ceramic transformers are designed to achieve miniaturization and high power of piezoelectric ceramic transformers. In addition to the development and use of high power piezoelectric ceramic materials, Japanese experts have developed a high-power multilayer piezoelectric ceramic transformer. It is actually a superposition of a plurality of Rosen-type piezoelectric ceramic transformers. At the primary end, that is, the input end of the piezoelectric ceramic is polarized along the thickness direction at the secondary end, that is, the output end,the piezoelectric ceramic is along the length direction. A prominent feature of the multilayer piezoelectric ceramic transformer is that when the thickness of the piezoelectric ceramic transformer is constant, the boost ratio is proportional to the number of layers of the transformer, and the transformer is easy to be flat, especially suitable for ultra-thin power supplies. There is surface assembly requirements of piezo ceramic materials.
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Circular plate type of single polarization direction piezoelectric ceramic transformer
All of the piezoelectric ceramic transformers mentioned above are basically composed of two parts of the input and output parts. The piezoceramic materials piezoelectric disc of the input and output parts have different polarization directions, even the same polarization direction, the input and output parts. Polarization is also carried out separately. For piezoelectric ceramic transformers ,with different polarization directions at the intersection of the input and output portions, stress concentration affects the performance of the piezoelectric transformer due to the difference in the polarization directions. In order to avoid this problem and improve the power capacity of the piezoelectric ceramic transformer, a single polarization direction circular plate type piezoelectric ceramic transformer has been proposed.
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