JPS61125179A - Torus-shaped piezoelectric transformer - Google Patents

Abstract

PURPOSE:To obtain a light-weight small-sized transformer, which can be driven at high frequency, simply by dividing and polarizing a torus-shaped piezoelectric porcelain into the plural in the circumferential direction and forming split electrodes on the surface and back of the porcelains. CONSTITUTION:A torus-shaped piezoelectric porcelain 2 is divided into four in the circumferential direction, and a pair of opposite sections are polarized in the same directon and a pair of other opposite sections in the opposite direction asshown in the arrows. Split electrodes 3a, 3a', 3b, 3b' are each formed onto the surface and back of the porcelain 2, thus shaping a torus-shaped thick slip mode piezoelectric vibrator 1. The electrodes 3a, 3a' are connected in parallel with primary terminals A, A' by lead wires 4, and secondary terminals B, B', C, C' are connected to the electrodes 3b, 3b' by lead wires 5, 6, thus acquiring a transformer. Accordingly, the transformer can be lightend and miniaturized while it can also at driven at high frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a toroidal piezoelectric transformer using a toroidal thickness-shear mode piezoelectric element.

(Technical Background of the Invention) Generally, a coil-wound transformer is used as a transformer, and the structure usually uses an iron core (pot type ferrite core) to reduce the total capacity, but the frequency is 1 to 10 MHz. As the height increases, the effect of inserting the core decreases, making it difficult to downsize. Therefore, the shape of this type of transformer,
The weight of the transformer increases, and reducing the weight of the transformer becomes a major issue when a large number of transformers are installed in one device, and it is desirable to reduce the size of the transformer in order to save mounting space on the printed circuit board. was.

For this reason, various piezoelectric transformers have been tried in the past, but piezoelectric transformers with particularly high operating frequencies (1 to 10 MHz
), and the requirements for a large load current on the output side, none of these specifications could be met.

(Object of the Invention) The present invention has been made based on the above-mentioned circumstances, and it is an object of the present invention to provide an annular piezoelectric transformer that can be driven by a high-frequency signal, is lighter in weight, smaller in size, and has improved mass productivity. purpose.

(Summary of the Invention) In order to achieve the object, the present invention provides a structure in which an annular piezoelectric porcelain is divided into a plurality of parts in the circumferential direction and polarized, and divided electrodes are provided on each of the front and back surfaces. An output signal obtained by converting the input signal generated from the output side of at least another pair of the divided electrodes by applying an input signal to the input side of the pair of divided electrodes of the annular thickness-shear mode piezoelectric element to excite it. Make sure to take it out.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

Note that the same reference numerals in each figure indicate similar objects.

FIG. 1 is a perspective view showing one embodiment of the present invention.

2 is an annular piezoelectric porcelain, which is divided into four parts in the circumferential direction, and as shown by the arrows in the figure, a pair of opposing parts are placed in the same direction, and another pair of opposing parts are placed in the same direction. The annular thickness-shear mode piezoelectric vibrator 1 is polarized in the opposite direction, and divided electrodes 3a, 3a'; 3b, 3b' are provided on the front and back surfaces of the annular piezoelectric ceramic 2, respectively. A lead wire 4 connects the primary terminals A, A' and the electrodes 3a, 3a/ in parallel.

B, Er; C1σ are secondary terminals, each with lead wire 5.6
The electrodes 3b and 3b' are connected to each other through the electrodes 3b and 3b'.

As a method for polarizing annular piezoelectric porcelain in the circumferential direction,
(1), (f) Make the tips of a pair of high-voltage polarization electrodes brush-like and stretchable, and slide them one after another while maintaining a gap larger than the thickness of the element, or A temporary electrode is provided with polarization, and a high voltage is applied in parallel.

The final electrode of the segmented electrode is usually formed by means such as electroless plating or vacuum deposition.

Next, to explain the effect, the frequency that resonates in the thickness shear mode at the negative side terminal A, 7V (frequency constant, for example, Ns =
90 kHz-cm), the annular thickness-shear mode piezoelectric vibrator 1 excites thickness-shear vibration, and an output signal with the same frequency as the excitation voltage (or current) is generated from the electrodes 3b and 3b'. , secondary terminal B, Ilr; C1
It can be extracted from σ. Depending on the purpose of use, it may be determined whether the secondary side terminals B and C1σ are connected in parallel or in series.

In order to particularly increase the load current on the output side or to increase the voltage, the above-mentioned annular thickness-shear mode piezoelectric elements can be driven in parallel with two sheets to achieve the feather-like vibration state described below. The divided electrodes on the output side are connected in series or parallel in accordance with the polarization to increase the voltage or current. This will be explained with reference to the drawings. FIG. 2 is a partially enlarged explanatory view of an annular thickness-shear mode piezoelectric element in which two sheets are bonded together. In the figure, reference numerals 10 and 11 are annular thickness-shear mode oscillators that are attached via adhesive and are polarized in the direction of the arrow. This annular thickness shear mode oscillator 10.1
The input sides of 1 are electrically connected in parallel.

When an input signal is applied to the annular thickness-shear oscillator 10.11, the annular thickness-shear oscillator 10.11 generates thickness-shear vibration. Dotted lines 101 and 102 indicate the state of the element when no input signal is applied.

When an input signal is applied to this, the element becomes solid line 103, 10
4. As shown in 105 and 106, a feather-like thickness difference occurs and resonance vibration occurs. , since the element is annular, every part takes a feather-like vibration state as shown in FIG. This excitation is converted to the secondary side to obtain an increased output signal as explained in FIG.

In FIG. 2, when the inputs are connected in series, the polarization directions of the upper and lower elements are reversed. This is a circuit that can be arbitrarily selected depending on the voltage and excitation intensity that the circuit can output.

FIG. 3 shows a third embodiment. In Figure 3(a), 2
0.21 are annular thickness-shear oscillators bonded together via an adhesive. The secondary side is divided into a plurality of blocks (six blocks in this embodiment) and polarized in the direction of the arrow, that is, the annular thickness-shear oscillators 20 and 21 are polarized in opposite directions, and are connected in series with electrodes to generate a high voltage. (1 to 3 kV) is an annular piezoelectric transformer. D and U are primary side terminals, and 88g is a secondary side terminal.

FIG. 3(b) is an equivalent circuit of FIG. 3(a). By laminating two annular thickness-shear mode vibrators, the primary side capacity becomes twice that of the annular thickness-shear mode vibrator shown in FIG. 1, and the secondary side output voltage becomes six times as high.

The present invention is not limited to the above-described embodiments, but includes various other aspects. For example, the same function can be obtained even if the electrodes are provided at positions on the inner and outer peripheries of an annular ring after polarization.

(Effect of the invention) As described above, the present invention provides the following effects.

(1) By making the thickness-shear oscillator circular and endless, stable resonance conversion with less parasitic vibration near the resonance point becomes possible.

(2) The annular thickness-shear oscillator can be easily mass-produced by making the element thinner as desired, increasing the resonance frequency (1 to 1
0 MHz), and therefore the signal intermittent frequency can be set as fast < (100kHz = 10 pse
c) can be designed.

(3) For the secondary output, the method of connecting the split elements is that high capacity (large current) can be obtained by connecting them in parallel, or high voltage can be obtained by connecting them in series. By laminating two sheets together, the capacity is further increased and a more elastic design becomes possible.

(4) Electrical insulation between the primary and secondary sides of the annular thickness-slip piezoelectric element can be made into a 4-terminal configuration depending on the structural arrangement of the attached electrodes, and there is a small stray capacitance (stray capacitance) between the capacitance) and high insulation resistance.

(5) When the operating frequency is high, the thickness of the annular piezoelectric ceramic becomes thinner, so when mounting it on a printed circuit board, both the area and the materials used can be saved, and the cooling effect is improved, so it can be used with a larger amplitude. Become.

(6) By processing the piezoelectric ceramic into an annular shape, an infinite circle can be formed and resonate at a single frequency, so a piezoelectric transformer with less dyspurious (parasitic vibration) can be formed.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing one embodiment of the present invention, FIG. 2 is a partially enlarged explanatory view of the second embodiment, FIG. 3 is a perspective view of the third embodiment, and FIG. 4 is a perspective view of the third embodiment. FIG. 3 is an equivalent circuit diagram of the third embodiment. 1: Annular thickness shear mode vibrator, 2: Annular piezoelectric porcelain, 3a, 3 a/, 3b, 3b': split electrode, 4.
5.6: Lead wire, A, R knee side terminal, B, Er
;C, C': Secondary side terminal.

Claims (3)

[Claims] (1) An input signal is input to the input side of a pair of divided electrodes of an annular thickness shear mode piezoelectric vibrator in which an annular piezoelectric porcelain is divided into a plurality of parts in the circumferential direction and polarized, and divided electrodes are provided on the front and back surfaces respectively. An annular piezoelectric transformer, characterized in that an output signal obtained by converting the input signal generated from the output side of at least another pair of the divided electrodes is extracted by applying and exciting the transformer. (2) An annular piezoelectric transformer according to claim 1, wherein two annular thickness-slip mode piezoelectric vibrators are bonded together and driven simultaneously. (3) An annular piezoelectric transformer according to claims 1 and 2, wherein a plurality of pairs of output sides of the divided electrodes are connected in series or in parallel.