JPH09162456A - Piezoelectric transformer - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a piezoelectric transformer having an inductor on the input side and satisfying market demands such as size reduction, height reduction, voltage reduction, and cost reduction. A pair of input electrodes 12a, 12b for inputting an electrical signal and a pair of output electrodes 13a, 1 for extracting an electrical signal are provided on a piezoelectric ceramic rectangular plate 11.
3b, the piezoelectric ceramic rectangular plate 11 is provided with at least one inductor formed by the thin film conductor 14 on the surface or inside thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric transformer using a rectangular plate of a piezoelectric vibrator, and more specifically, it cancels the capacitance of a capacitor generated between the input electrodes of the piezoelectric transformer by using a resonance inductor built in a piezoelectric transformer element. ， Relating to an efficient piezoelectric transformer that suppresses input power.

[0002]

2. Description of the Related Art Conventionally, a piezoelectric transformer is known as a device to which a rectangular plate of a piezoelectric vibrator is applied. At present, a ceramic or a lithium niobate single crystal is often used as a vibrator used in a piezoelectric transformer, and as a general structure, as shown in a schematic perspective view of FIG.
Is a structure in which a pair of input electrodes 12a, 12b and a pair of output electrodes 13a, 13b capable of inputting and outputting an electric signal and an output signal from an input electric signal source 51 are formed on the surface or side surface of a piezoelectric ceramic rectangular plate 11 so as to face each other. Is. When a resonance inductor is added in parallel or in series with the input electrodes 12a and 12b, an external inductor 53 is connected to the outside of the piezoelectric transformer and leads 54a connected to the input electrodes 12a and 12b and the input signal source 51. The method of connecting to 54b was common. In the figure, the arrow indicates the polarization direction of the piezoelectric ceramic rectangular plate 11,
Input electrodes 12a, 12b and output electrodes 13a, 13b
Polarize before making, or after making, input electrode 1
2a, 12b and the output electrodes 13a, 13b are used for polarization, and reference numeral 52 is a load resistance.

[0003]

Piezoelectric transformers are generally required to be small, low in height and low in cost, but conventional piezoelectric transformers cannot sufficiently meet these demands. . That is, when an inductor 53 is to be added to the piezoelectric transformer 50 as shown in FIG. 5, the input electrodes 12a and 12b of the piezoelectric transformer 50 and the external inductor 53 are different from the piezoelectric ceramic rectangular plate 11.
Separately arranged, the leads 54a, 54b, 55a, 55b
Since they are connected by such means, the mounting area and man-hours are enormous even if the size and height of the piezoelectric transformer are reduced.

When the piezoelectric transformer is intended to be driven at a low voltage, the boosting ratio of the piezoelectric transformer can be increased by forming the input into a laminated structure. However, if the input has a laminated structure, the input capacitance becomes large, the input impedance becomes small, the input current becomes large, and it becomes very difficult to drive the piezoelectric transformer drive circuit. Table 1 below shows the input capacitance and the inductance at resonance when stacking. Here, the resonance inductance is expressed as L = 1 / ω ² C from ωL = 1 / ωC.

[0005]

[Table 1]

From Table 1 above, as the number of layers increases, the input capacitance increases and the inductor decreases.

As described above, the conventional piezoelectric transformer has a drawback that it is very difficult to sufficiently satisfy the market demands for downsizing, height reduction, voltage reduction, and cost reduction.

[0008] Therefore, a technical object of the present invention is to provide a piezoelectric transformer which is provided with an inductor on the input side and satisfies market demands such as size reduction, height reduction, voltage reduction, and cost reduction.

[0009]

According to the present invention, at least one set of input electrodes for inputting an electrical signal and at least one set of output electrodes for extracting an electrical signal are provided on a piezoelectric ceramic plate. In the provided piezoelectric transformer, it is possible to obtain a piezoelectric transformer characterized in that at least one inductor is provided on the surface or inside of the piezoelectric ceramic plate.

Further, according to the present invention, in the piezoelectric transformer, it is possible to obtain a piezoelectric transformer characterized in that the inductor is composed of a conductor and a magnetic body surrounding the conductor.

Further, according to the present invention, in any one of the piezoelectric transformers described above, the piezoelectric transformer is obtained in which the inductor is connected in parallel or in series with the input electrode.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing a piezoelectric transformer according to a first embodiment of the present invention. Referring to FIG.
The piezoelectric transformer 10 uses a piezoelectric ceramic rectangular plate 11 forming a piezoelectric vibrator, and has a pair of input electrodes 12 for inputting and outputting a voltage to both sides of the ceramic rectangular plate 11.
a, 12b and output electrodes 13a, 13b are formed.
The size of the piezoelectric ceramic rectangular plate 11 is 40 mm in length and 1 in width.
0 mm, thickness 1.5 mm, using PZT ceramics, input electrodes 12a, 12b and output electrodes 13a, 1
The external electrodes such as 3b were formed by baking Ag. Finally, the thin film conductor 14 is formed on the surface of the piezoelectric ceramic rectangular plate 11 by vapor deposition to form an inductor that is substantially resonant with the input capacitance.
The configuration is such that the input electrodes 12a and 12b can be connected in parallel. The arrows in the figure indicate the polarization direction of the piezoelectric ceramic rectangular plate 11, and the input electrodes 12a and 12b and the output electrode 13 are shown.
The piezoelectric ceramic rectangular plates 11 are polarized so that they are parallel to each other in the lengthwise direction of the piezoelectric ceramic rectangular plate 11 in the opposite directions of a and 13b.

FIG. 2 is a perspective view showing a piezoelectric transformer according to the second embodiment. Piezoelectric transformer 20 shown in FIG.
In order to obtain a larger inductance than in the piezoelectric transformer 20 of the first embodiment shown in FIG. 1, the number of meandering of the thin film conductor 14 on the surface is increased. In this way, the desired inductance can be obtained by changing the meandering number of the thin film conductor 14. The arrow in the figure indicates the polarization direction of the piezoelectric ceramic rectangular plate 11, and the input electrode 12
The electrodes a, 12b and the output electrodes 13a, 13b are polarized so as to be parallel to each other by approximately half in the length direction of the piezoelectric ceramic rectangular plate 11, respectively.

FIG. 3 is an exploded perspective view showing a piezoelectric transformer 30 according to a third embodiment of the present invention. In order to obtain a larger inductance than the inductance of the piezoelectric transformers 10 and 20 of the first and second embodiments shown in FIGS. 1 and 2, the piezoelectric transformer 3 of FIG.
In No. 0, an inductor formed by a thin film conductor 14 having a meandering conductor pattern is arranged on the piezoelectric ceramic rectangular plate 11 so as to be included in the magnetic bodies 15 and 16 having the same plane shape. Input electrode 12 of transformer 30
This inductor is connected in parallel with a and 12b. Further, here, since ferrite is used for the magnetic bodies 15 and 16 and PZT is used for the piezoelectric ceramic plate 11, 1
Integral sintering at around 050 ° C is also possible. The piezoelectric ceramic rectangular plate 11 is polarized so as to be parallel to each other in the width direction, that is, in the facing direction of the input electrodes 12a and 12b and the output electrodes 13a and 13b, as in the case shown in FIGS. Has been done.

FIG. 4 is an exploded perspective view showing a piezoelectric transformer according to a fourth embodiment of the present invention. The piezoelectric transformer 40 in FIG. 4 shows a case where the piezoelectric transformer 40 has a larger inductance than the piezoelectric transformer 30 in FIG. As shown in FIG. 4, in the piezoelectric transformer 40, a conductor pattern made of the thin film conductor 14 is formed on the magnetic body 16 on the piezoelectric ceramic rectangular plate 11, and the openings 17a, 19a, 22a are further formed in part.
Magnetic body 1 having the same planar shape as the magnetic body 16 in which the
7,19,22 through the openings 17a, 19a, 22a
Was laminated so that the conductor patterns of the thin film conductors 18, 21, 23 were continuously connected through the openings 17a, 19a, 22a as one end, and the magnetic body 24 was further laminated on this laminated body. In addition, a pair of input electrodes 12a and 12b and output electrodes 13a and 13b are formed for input and output. Although not shown, the input electrode 12b is formed from the side surface of the piezoelectric ceramic plate 11 to the thin film conductor 23
Is formed to extend to one end of. The inductor formed by the pattern of the thin film conductors 14, 18, 21, 23 formed here has 3.5 turns, and the piezoelectric ceramic rectangular plate 11 has the same width as that shown in FIGS. 1 and 2. The electrodes are polarized so as to be parallel to each other in the direction, that is, the facing direction of the input electrodes 12a and 12b and the output electrodes 13a and 13b. The piezoelectric ceramic rectangular plate 11 is polarized in the width direction.

Further, in the piezoelectric transformer according to the embodiment of the present invention, the same effect can be obtained even if the piezoelectric transformer is formed in a state before sintering and integrally sintered or formed by adhesion after sintering. Further, the same effect can be obtained even when the inductor on the surface or inside is a thin film formed by vapor deposition or a thick film formed by printing.

Next, an example of the characteristics of the prototyped piezoelectric transformer will be shown. In the third embodiment of FIG. 3, the number of layers is 10
In the case of a layer, the input capacitance is 150 nF and the resonance inductance is 26 μH. Here, assuming that the output power is constant when the load of the piezoelectric transformer is 100 kΩ, the conventional configuration as shown in FIG.
The input current was A, but in the configuration according to the third embodiment of FIG. 3, the input current was 400 mA at 6 V input, and the input power could be reduced by about 10%.

As described above, when the piezoelectric transformer according to the embodiment of the present invention is used, resonance of the single plate or the piezoelectric transformer having a laminated structure intended for low voltage is realized by the inductor arranged on the surface of or inside the piezoelectric transformer. The input current is suppressed and the efficiency is improved by using, and the piezoelectric transformer itself has an inductor, which reduces the number of parts and the mounting area, and is compact, low profile and low voltage.
It is possible to provide a piezoelectric transformer that can be manufactured at low cost and that can be easily surface-mounted.

[0020]

As described above, by using the piezoelectric transformer of the present invention, it is possible to use an external inductor without using an inductor.
Since the resonant circuit can be configured by the piezoelectric transformer itself, the efficiency of the piezoelectric transformer can be improved, and the number of parts and the mounting area can be greatly reduced, which enables a significant reduction in size, height, voltage and cost. Yes, the practical effect is very large.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a piezoelectric transformer according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of a piezoelectric transformer according to a second embodiment of the present invention.

FIG. 3 is an exploded perspective view showing a configuration of a piezoelectric transformer according to a third embodiment of the present invention.

FIG. 4 is a perspective view showing a configuration of a piezoelectric transformer according to a fourth embodiment of the present invention.

FIG. 5 is a perspective view showing an example of a conventional piezoelectric transformer.

[Explanation of symbols]

 11 Piezoelectric ceramic rectangular plates 12a, 12b Input electrodes 13a, 13b Output electrodes 14, 18, 21, 23 Thin film conductors 15, 16, 17, 19, 22, 24 Magnetic body 17a, 19a, 22a Opening 51 Input signal source 52 Load resistance

Claims (3)

[Claims] 1. A piezoelectric transformer having, on a piezoelectric ceramic plate, at least one set of input electrodes for inputting an electric signal and at least one set of output electrodes for taking out an electric signal. A piezoelectric transformer characterized in that at least one inductor is provided on the surface or inside thereof. 2. The piezoelectric transformer according to claim 1, wherein
The piezoelectric transformer comprises a conductor and a magnetic body surrounding the conductor. 3. The piezoelectric transformer according to claim 1, wherein the inductor is connected in parallel or in series with the input electrode.