SU721871A1 - Piezoelectric transformer - Google Patents

Description

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The invention relates to the field of piezoelectric devices, in particular, piezoelectric transformers (PT), and can be used in electronic equipment of low and medium power for converting an electrical signal of one level into a signal of another higher or lower level.

Piezoelectric transformers ij, which are monolithic polarized in the pscerech direction, are equipped with a piezoceramic element equipped with three electrodes at the ends, the ratio of the distance between the cores and the wavelength (L) of the mechanical oscillations at the operating frequency of the PT is equal to one ( second mode of oscillation).

The functional diagram of such PT consists of two sections - input and output, polymerized in the transverse direction (transverse type of PT).

PTs with the specified polarization direction are used in low-voltage (up to 1 kV) secondary power sources of electronic equipment at relatively high input and output currents. The magnitude of the transformation ratio for these FPs is slightly different from unity; it can be increased by connecting the h-piezo elements in parallel and in series.

The closest technical solution to the present invention is a piezoelectric transformer containing a longitudinal oscillation piezoelectric plate with three electrodes forming the input and output sections, with the ratio of the plate length to the wavelength of mechanical oscillations at the operating frequency equal to 3/4 2.

In the well-known transformer Bi ixoa, the section along rizovaya prodolis,

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and the end of the lower section is rigidly fixed.

Such a technical solution does not provide a transformation (| x |) Ishenga transformation with cross-polarization of the output section.

The aim of the invention is to increase the ratio ({) of the transformational chip. The goal is ensured by the fact that in a piezoelectric transistor, containing a piezoelectric plate of longitudinal oscillations with three: electrodes forming the input and output sections with the ratio of the plate length to the wavelength of mechanical oscillations at the operating frequency equal to 3/4, the said plate on the side of the output section is rigidly fixed and has a transverse polarization.

Such a constructive solution of the PT is due to the following: the implementation of the PT with a transform ratio greater than one is associated with the introduction of a single-meter into its functional diagram, i.e. with different constructive insertion of the inlet and transceiver sections (for example, different PLC electrodes of the sections, step ejection of the piezoelectric element, etc.-).

Different conditions of fixing at the ends of the piezoelectric element (one end is rigidly fixed, and the opposite is free) allow to increase the asymmetry of the PT functional circuit, i.e., increase the value of the transformation ratio while maintaining its operating frequency. Obviously, when the proposed flT is switched back on, the value of its transformation coefficient will be reduced accordingly.

Fig. 1 shows the constructive scheme of the proposed piezoelectric transformer; in fig. 2 is a variant of the plate fastening element.

The piezoelectric transformer (fig, 1) is complete in the form of a thin piezoceramic plate 1, length ce f. The plate is equipped with three electrodes 2, 3 and 4, forming the input (3.2) and output (4.3) sections, and is rigidly fixed to the end of the output section in the fastening element 5 The transformer operates as follows.

I mix the voltage of the electric-1HE field applied to the input section of the piezoplate (electrodes 2, 3 n

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FIG. 1) due to the inverse piezoelectric effect, causes mexaHiPiecKHB oscillations of the entire plate, resonantly amplified at a frequency characteristic of a plate with one clamped and another free horse and corresponding to wavelength A, mechanical oscillations in the output section of the first piezoelectric effect create an electric field resulting in the potential difference across the electrodes 4, 3.

A prototype of the proposed PT was manufactured.

The piezoelectric transformer is made in the form of a thin plate from the piezoelectric composition of the PZT-23 with a working length of 30 μm, which is soah

JET j- at a frequency of 80 kHz,

is in charge

0 wide - and thick -. The plate is equipped with three electrodes of length (input section), - j- (output section), and - common electrode. It is semi-transverse.

3 directions - in thickness and works in the mode of longitudinal oscillations in length at a frequency of –fp 80 kHz The end of the entrance section is free, the end of the output section is rigidly fixed in the clip 5

0 (see Fig. 1). A constructive version of the fastening element is shown in FIG. 2. Clamp 5 is a round rod made of metal with diameter AO / 2 and length A / 4 (Ld is the wavelength of the longitudinal oscillations in the material of the rod) with a diametrically slotted width Ac / 40 to a depth of о / 8- Piezoceramic plate 1 is glued into slot 6 using epoxy mass MD5-65.

Tests of the transformer showed that its transformation ratio is 2, 4.

Claims (1)

1. The UK patent number 132,558, cl. H 01 L 41 / O8, 13.05.76 (tfocl, H 2 H, published on 01.08.73.toype). log in Output 4 / 2.2