JPH11154768A - Piezoelectric ceramic transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric ceramic transformer which enables driving at high-frequency band and a high power output in a high frequency range above several hundreds of kHz. SOLUTION: A piezoelectric ceramic plate 10 is polarized in the perpendicular direction to the thickness directions. Input electrode pairs (11, 21), (13, 23), and (15, 25) and output electrode pairs (12, 22), (14, 24), and (16, 26) are arranged in parallel or perpendicular to the polarization direction on the piezoelectric ceramic plate 10. Then, the piezoelectric ceramic plate 10 is excited by applying an AC voltage with a frequency in the vicinity of the resonance frequency of the thickness-slip oscillation mode to the input electrode pairs (11, 21), (13, 23), and (15, 25). Then, the AC voltage is generated from the output electrode pairs (12, 22), (14, 24), and (16, 26).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric ceramic transformer operable in a high frequency band, and more particularly, to a piezoelectric ceramic transformer used for an on-board switching power supply which is required to be small and thin.

[0002]

2. Description of the Related Art In recent years, downsizing of electronic equipment has been demanded, and accordingly, downsizing of power supply devices has been demanded. In order to reduce the size of the power supply device, for example, in the case of a switching power supply device, the switching frequency is increased. In a switching power supply, by increasing the switching frequency, it is possible to reduce the size of a transformer, a coil, a capacitor, and the like that constitute the switching power supply, and therefore, it is possible to reduce the size of the entire power supply. Become.

Conventionally, an electromagnetic transformer has been used in a switching power supply device. However, when the switching frequency is increased, the hysteresis loss of the magnetic material used in the electromagnetic transformer, the eddy current loss, the loss due to the skin effect of the windings, etc. increase rapidly, and the efficiency of the transformer is greatly reduced. . Therefore, the upper limit of the practical switching frequency band of the switching power supply device using the electromagnetic transformer is about 500 KHz.

[0004] On the other hand, in recent years, a piezoelectric ceramic transformer capable of performing a switching operation in a high frequency band has been receiving attention. The piezoelectric ceramic transformer is used in a resonance state, and compared with a general electromagnetic transformer, (1) the efficiency of the transformer is high in a high frequency band of 500 KHz or more, (2) noncombustibility can be achieved, and (3) electromagnetic induction. It has advantages such as no noise.

FIG. 12 shows the structure of a Rosen type piezoelectric ceramic transformer, which is a typical conventional piezoelectric ceramic transformer. In the Rosen type piezoelectric ceramic transformer, an electrode 111 is formed on a half of an upper surface of the piezoelectric ceramic plate 100, and an electrode 121 is formed on a half of a lower surface of the piezoelectric ceramic plate 100 so as to face the electrode 111. An electrode 112 is formed on the side of the piezoelectric ceramic plate 100 where the electrodes 111 and 121 are not formed.

The external terminal 131 is connected to the electrode 111, the external terminal 132 is connected to the electrode 121, and the external terminal 141 is connected to the electrode 112. The region A1 of the piezoelectric ceramic plate 100 is polarized in the thickness direction of the piezoelectric ceramic plate 100 as indicated by an arrow 110, and a low impedance portion is formed between the electrode 111 and the electrode 121. The region A2 of the piezoelectric ceramic plate 100 is polarized in the length direction of the piezoelectric ceramic plate 100 as indicated by an arrow 120, and a high impedance portion is formed between the electrode 121 and the electrode 112.

When extracting a high voltage from the Rosen-type piezoelectric ceramic transformer, a low-impedance area A1 is used as an input section, and a high-impedance area A2 is used as an output section. The principle of operation of this Rosen-type piezoelectric ceramic transformer is that when an AC voltage is applied between the pair of input electrodes 111 and 121, the input side has a low impedance region A
Piezoelectric transverse effect with an electromechanical coupling factor k ₃₁ in 1 (3
1) A longitudinal vibration is excited in the mode, and the vibration causes the entire transformer to vibrate.

[0008] In the region A2 in this order output, the AC voltage by the piezoelectric longitudinal effect 33 mode occurs with the electromechanical coupling coefficient k _33, an AC voltage is taken out from between the pair of output electrodes 112, 121. At this time, it is known that the relationship between the input voltage Vin and the output voltage Vout of the Rosen-type piezoelectric ceramic transformer is given by the following equation. _{(Vout / Vin) α k 31} · k 33 · Qm · (L / t) (1) where, k _31: piezoelectric transverse effect of the electromechanical coupling factor k _33: electromechanical coupling coefficient of the piezoelectric longitudinal effect Qm: mechanical Quality factor L: Length of output part t: Thickness of piezoelectric ceramic transformer On the other hand, in order to input high voltage and output low voltage,
This can be realized by inverting the input terminal 131 and the output terminal 141, using the high-impedance area A2 as an input section, and using the low-impedance area A1 as an output section.

[0009]

The resonance frequency of longitudinal vibration used in a Rosen type piezoelectric ceramic transformer is proportional to the length L of the transformer. Therefore, in order to vibrate in a high frequency band, it is necessary to reduce the length L of the Rosen-type piezoelectric ceramic transformer. On the other hand, the power that can be extracted from the transformer is proportional to the size of the transformer. Therefore, when it is intended to output a large power by shortening the length L, a method of increasing the width L in the direction of the width W may be considered.

However, the electromechanical coupling coefficients k ₃₁ and k ₃₃ have a shape dependency, and when the value of (width W / length L) becomes 0.3 or more, the electromechanical coupling coefficients k ₃₁ and k ₃₃ become smaller. The value starts to drop. For this reason, the width W cannot be increased unnecessarily, and the practical application frequency is at most about 200 kHz. For this reason, it has been difficult for the conventional Rosen-type piezoelectric ceramic transformer to achieve both driving in a high frequency band and taking out large power.

Further, in a general piezoelectric magnetic material such as lead zirconate titanate, an electromechanical coupling coefficient k _{15 for} a thickness shear vibration, an electromechanical coupling coefficient k _{33 for} a longitudinal effect vibration, and an electromechanical coupling coefficient k33 for a transverse effect vibration. between k _31, a relationship of _{k 15> k 33> k 31} . For this reason, the conventional Rosen-type piezoelectric ceramic transformer has to use the vibration mode having the smallest electromechanical coupling coefficient, so that the efficiency of converting electric energy into mechanical vibration energy is low. Therefore, there is a disadvantage that the efficiency as a transformer is poor.

The present invention has been made in view of such conventional problems, and has as its object to provide a piezoelectric ceramic transformer capable of achieving both driving in a high frequency band and taking out large power. .

[0013]

In order to achieve this object, a piezoelectric ceramic transformer according to the present invention is constituted by a plate-shaped member, and the piezoelectric ceramic plate is uniformly polarized in a direction perpendicular to the thickness direction of the plate. A pair of input electrodes, which are disposed opposite to both sides of the piezoelectric ceramic plate in the thickness direction and are applied with an AC voltage having a frequency near the resonance frequency of the thickness shear vibration mode to excite the piezoelectric ceramic plate, and a piezoelectric ceramic plate; And a pair of output electrodes arranged to face the two surfaces positioned in the thickness direction and arranged side by side with the input electrode pair, and to extract an AC voltage induced by the excitation of the piezoelectric ceramic plate by the input electrode pair.

As described above, the piezoelectric ceramic transformer of the present invention comprises:
The conversion of the AC voltage by an input electrode pair to the AC voltage from the mechanical vibrations in the conversion and the output electrode pair to mechanical vibration using an electromechanical coupling factor k ₁₅ of the largest thickness shear vibration mode in the electro-mechanical coupling coefficient Therefore, energy can be transmitted more efficiently than a conventional piezoelectric ceramic transformer that performs conversion using another electromechanical coupling coefficient.

Further, the resonance frequency of the thickness shear vibration of the piezoelectric ceramic transformer of the present invention does not depend on the length or width of the piezoelectric ceramic plate, but only on the thickness. Therefore, the piezoelectric ceramic transformer is driven by the thickness shear vibration. In order to extract large power with the piezoelectric ceramic transformer of the present invention, it is sufficient to simply increase the length and width while keeping the thickness constant, and it is difficult to drive in a high frequency band with the conventional Rosen type piezoelectric ceramic transformer. High power extraction can be achieved at the same time.

Here, the input electrode pairs and the output electrode pairs may be arranged on the piezoelectric ceramic plate in a direction parallel to the polarization direction, or the input electrode pairs and the output electrode pairs may be arranged in the direction perpendicular to the polarization direction. It may be arranged on a piezoelectric ceramic plate. In the piezoelectric ceramic transformer of the present invention, a plurality of input electrode pairs and a plurality of output electrode pairs are arranged on a piezoelectric ceramic plate, and the input impedance is set to a desired value by connecting the plurality of input electrode pairs in series or in parallel. The output impedance is set to a desired value by connecting the output electrode pairs in series or in parallel. As a result, the relationship between the input and output impedances of the piezoelectric ceramic transformer can be adjusted as required.

That is, the setting of high impedance is achieved by connecting a plurality of input electrode pairs and a plurality of output electrode pairs in series, and the setting of low impedance is achieved by connecting a plurality of input electrode pairs and a plurality of output electrode pairs in parallel. . In addition, a plurality of input electrode pairs and a plurality of output electrode pairs are arranged such that the electrodes are alternately arranged.
Further, any one of the plurality of input electrode pairs and the plurality of output electrode pairs may be arranged side by side in one place, and the other may be arranged collectively in one electrode pair.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a piezoelectric ceramic transformer according to a first embodiment of the present invention, in which three input electrode pairs and three output electrode pairs are arranged as an example. In FIG. 1, the piezoelectric ceramic plate 10 is polarized perpendicularly to the thickness direction indicated by the arrow 18. On the upper surface of the piezoelectric ceramic plate 10, three electrodes 11, 13, 15 used for input are arranged, and three electrodes 12, 14, 14 used for output are alternately arranged with respect to the electrodes 11, 13, 15. 16 are installed.

On the lower surface of the piezoelectric ceramic plate 10, three electrodes 21, 23, 25 are provided at positions opposed to the three input electrodes 11, 13, 15 on the upper surface. Three electrodes 22, 24, and 26 are arranged at positions facing the output electrodes 12, 14, and 16, respectively. The upper electrodes 11 to 16 and the lower electrodes 21 to 26 make 3
Input electrode pairs (11, 21), (13, 23), (1
5, 25) and three output electrode pairs (12, 22), (1
4, 24) and (16, 26).

FIG. 2 shows an embodiment of the input / output connection to the piezoelectric ceramic transformer of FIG. First, electrodes 11 to 16 on the upper surface
Are connected to the lead terminals 31 to 36, and the lead terminals 41 to 46 are similarly connected to the electrodes 21 to 26 on the lower surface. The input electrodes 11, 13, 15 on the upper surface are connected to one input terminal 51 via lead terminals 31, 33, 35, and the electrodes 21, 23, 25 on the lower surface are connected to the lead terminal 4.
1, 43 and 45 are connected to the other input terminal 52.

Output electrodes 12, 14, 16 on the upper surface
Is connected to one output terminal 53 via lead terminals 32, 34, 36, and the electrodes 22, 24, 26 on the lower surface are connected to the other output terminal via lead terminals 42, 44, 46. The piezoelectric ceramic plate 10 in the piezoelectric ceramic transformer of FIG. 1 is made of lead zirconate titanate (PbTiO ₃ −
It is manufactured using PbZrO ₃ ) -based piezoelectric ceramic materials.
Of course, the piezoelectric ceramic material used for the piezoelectric ceramic plate 10 need not be limited to the lead zirconate titanate-based piezoelectric ceramic material.
If the value of the electromechanical coupling factor k ₁₅ in the thickness shear vibration large, may be used other materials.

The production of the piezoelectric ceramic plate 10 is as follows. First, a binder is mixed with the piezoelectric ceramic material powder, and the length is 45 mm and the width is 10 mm.
Press molding to a size of 2 mm and a thickness of 2 mm. The press-formed piezoelectric ceramic material powder is subjected to a binder removal treatment at 600 ° C. for 1 hour (heating rate 100 ° C./1 hour), and then fired at 1200 ° C. for 2 hours. By cutting and polishing the baked piezoelectric ceramic plate 10, the length is 31.7 m.
m, a width of 6.4 mm, and a thickness of 1.4 mm.

Here, the piezoelectric ceramic plate 10 is made by pressing and firing piezoelectric ceramic material powder.
Alternatively, a piezoelectric ceramic plate may be formed by a method of forming a green sheet using a doctor blade method or the like and firing the green sheet. Next, an Ag paste is applied to the opposing side surfaces of the piezoelectric ceramic plate 10 and baked to bake the Ag electrodes. 120 pieces of piezoelectric ceramic plate with Ag electrode
18 kV (about 2.8 kV / m
m) is applied to the Ag electrode, so that the piezoelectric ceramic plate 10
Is applied to uniformly polarize in the width direction orthogonal to the thickness direction.

After the polarization treatment, the Ag electrode baked on the side surface in the length direction is removed by polishing. Here, the electrodes are formed on the opposing side surfaces of the piezoelectric ceramic plate using an Ag paste. However, the present invention is not limited to the Ag paste, and any conductive material may be used for forming the electrodes. Subsequently, as shown in FIG. 1, the electrodes 11 to 16 are formed on the upper surface of the piezoelectric ceramic plate 10 and the electrodes 2 are formed on the lower surface thereof, as shown in FIG.
1 to 26 are formed. Here, the Au thin film is formed on the electrode by the sputtering method. However, the Au thin film is not limited to the Au thin film, and any conductive material may be used for forming the electrode.

Finally, as shown in FIG. 2, after the lead terminals 31 to 36 are attached to the electrodes 11 to 16 and the lead terminals 41 to 46 are attached to the electrodes 21 to 26, the input terminals 51 and 52 and the output terminals 53 and 54 are attached. Connect to Between the input terminals 51 and 52 of the piezoelectric ceramic transformer of FIG.
When an AC voltage having a frequency near the resonance frequency fp of the thickness-shear vibration mode of the piezoelectric ceramic plate 10 is applied as in the input voltage of FIG.
The A3, A5, thickness shear vibration is excited thickness-shear vibration with the electromechanical coupling k ₁₅ (15) mode by the displacement occurs in the piezoelectric ceramic plate 10, the entire transformer is vibrated by the vibration.

That is, at the point of time when the AC voltage -V at point A in FIG. 3A is applied, the piezoelectric ceramic plate 10 receives the stress F1 in the thickness shear vibration (15) mode as shown in FIG. F
2 at the time of the AC voltage OV at the point B, FIG.
As shown in (C), the distortion disappears, and at the point of time of the AC voltage + V at the point C, as shown in FIG.

[0027] At this time, in the region A2, A4, A6 of the output portion of the piezoelectric ceramic plate 10 of FIG. 1, the thickness shear vibration with the electromechanical coupling k ₁₅ (15) AC voltage by mode is generated, as a result, FIG. An AC voltage can be taken out between the output terminals 53 and 54 of the second. When the frequency characteristics of the impedance of the piezoelectric ceramic transformer were measured, f
The resonance in the thickness shear vibration mode was measured at p = 730 KHz. An AC voltage (sine wave) of 730 KHz and 7.3 V (rms) is input between the input terminals 51 and 52 of the piezoelectric ceramic transformer, and a load is connected between the output terminals 53 and 54 to vary the load. When the load current taken out of the piezoelectric ceramic transformer was changed in the above, the measurement results of the output voltage characteristic 200 with respect to the load current and the output power characteristic 210 with respect to the load current as shown in FIG. 4 were obtained.

From these characteristics, the peak value Pmax of the output power when the output voltage of 9.29 V (rms) is obtained with the load current of 63.2 mA (rms) in the piezoelectric ceramic transformer of the embodiment of FIGS. , Pmax = 587 mW.
In addition, the resonance frequency fp of the thickness shear vibration used for driving the piezoelectric ceramic transformer of the present invention is given by the following equation. fp = 1 / (2 · t) √ (C ₄₄ ^D / ρ) (2) ρ: Density of piezoelectric ceramic plate C ₄₄ ^D : Elastic constant t: Piezoelectric ceramic plate thickness According to this equation (2), piezoelectric The resonance frequency fp of the thickness shear vibration of the porcelain transformer does not depend on the length L or the width W of the piezoelectric ceramic plate 10, but only on the thickness t. For this reason, in order to extract a large amount of power with the piezoelectric ceramic transformer of the present invention driven by the thickness shear vibration, it is sufficient to simply increase the length L and the width W while keeping the thickness t constant. The phenomenon that the resonance frequency is lowered unlike the Rosen type piezoelectric ceramic transformer described above is not observed.

That is, in the piezoelectric ceramic transformer of the present invention,
It was difficult with conventional Rosen-type piezoelectric ceramic transformers.
It is possible to achieve both driving in a high frequency band and taking out large power. In the embodiments of FIGS. 1 and 2, three electrode pairs are connected in parallel to both the input and output sections. For example, if the input section is desired to have a high impedance, the three input electrode pairs are connected as shown in FIG. (11, 21), (13, 2)
3) and (15, 25) may be electrically connected in series. Conversely, if it is desired to make the output section high impedance, as shown in FIG. 6, three output electrode pairs (12, 22),
(14, 24) and (16, 26) may be electrically connected in series.

Further, by increasing the number of electrodes provided on the piezoelectric ceramic plate 10, it is possible to widen the setting range of the input impedance and the output impedance and to set them more finely. Further, in the embodiment of FIGS. 1 and 2, the electrodes of the input unit and the output unit are alternately arranged, but the input unit and the output unit may be combined in one direction. FIG.
Are the three electrode pairs (11, 2) on the input side in FIGS.
1), (12, 22) and (13, 23) are connected in series by lead terminals and connected between the input terminals 51 and 52, and the three electrode pairs on the output side in FIGS. Output electrode pairs (19, 20), and output terminals 53, 5
It is connected between four.

Further, input / output terminals 51 and 52 and output terminal 5
Regarding the connection wiring with the lead terminals for 3, 54,
It is also possible to install on the piezoelectric ceramic plate 10 using Ag paste or another conductive material. FIG. 8 shows a piezoelectric ceramic transformer according to a second embodiment of the present invention. The second embodiment is characterized in that the input electrode pairs and the output electrode pairs arranged on the upper and lower surfaces of the piezoelectric ceramic plate are arranged so as to be arranged perpendicular to the polarization direction of the piezoelectric ceramic plate.

In FIG. 8, the piezoelectric ceramic plate 10 is indicated by an arrow 18.
The polarization is perpendicular to the thickness direction. On the upper surface of the piezoelectric ceramic plate 10, the electrodes 61, 62, 63 are arranged side by side so as to be perpendicular to the polarization direction 18, and on the lower surface of the piezoelectric ceramic plate 10, each of the electrodes 61, 62, 63 on the upper surface is provided. The electrodes 71, 72, and 73 are arranged to face each other so as to be perpendicular to the polarization direction 18.

Here, the center electrode 62 has about twice the area of the electrodes 61 and 63 at both ends of the upper surface. This point is the same for the electrodes 71, 72, 73 on the lower surface. Lead electrodes 81 to 83 are connected to the electrodes 61 to 63 on the upper surface of the piezoelectric ceramic plate 10 as shown in FIG.
3, lead terminals 91 to 93 are connected. Lead terminals 81 and 83 are connected to one input terminal 51, and lead terminals 91 and 93 are connected to the other input terminal 52.

The lead terminal 82 is connected to one output terminal 53
, And the lead terminal 92 is connected to the other output terminal 54. As a result, two input electrode pairs (6
1, 71), (63, 73) and one output electrode pair (62, 72) of the output section. The manufacture of the piezoelectric ceramic transformer of FIGS. 8 and 9 is basically the same as that of the first embodiment of FIGS. 1 and 2, except that the piezoelectric ceramic plate after the polarization treatment and the removal of the Ag electrode has a length of 26. 7 mm, width 6.5 mm, and thickness 1.4 mm.

The resonance frequency in the thickness-shear vibration mode of the piezoelectric ceramic plate 10 is applied between the input terminals 51 and 52 of the piezoelectric ceramic transformer shown in FIG. 9 as shown in FIG. When applying an AC voltage having a frequency of fp neighborhood, in the area A1, A3 of the piezoelectric ceramic plate 10 of FIG. 8, the thickness shear vibration with the electromechanical coupling k ₁₅ (15) mode by the displacement occurs in the piezoelectric ceramic plate 10 thickness Slip vibration is excited, and this vibration causes the entire transformer to vibrate.

That is, the AC voltage −V at the point A in FIG.
As shown in FIG. 10B, the piezoelectric ceramic plate 10 is distorted by receiving the stresses F1 and F2 in the thickness shear vibration (15) mode.
At the AC voltage OV at the point B, the distortion disappears as shown in FIG. 10C, and at the AC voltage + V at the point C, the stresses F3 and F4 receive the stresses as shown in FIG. As a result, thickness shear vibration is excited in the piezoelectric ceramic plate 10, and
This vibration causes the entire transformer to vibrate. At this time, between the output electrode 62, 72 of the piezoelectric ceramic plate 10, an AC voltage is generated by the thickness-shear vibration (15) mode with an electromechanical coupling k _15, as a result, the output terminal 53 and 54
AC voltage can be taken out from between.

When the frequency characteristics of the impedance of the piezoelectric ceramic transformers of FIGS. 8 and 9 were measured, fp = 720
The resonance of the thickness shear vibration mode was measured at kHz. 720 between the input terminals 51 and 52 of the piezoelectric ceramic transformer.
An AC voltage (sine wave) of 7.3 V (rms) at kHz was input, a load was connected between the output terminals 53 and 54, and the load current was varied by varying the load. However, the measurement results of the output voltage characteristic 300 with respect to the load current and the output power characteristic 310 with respect to the load current as shown in FIG. 11 were obtained.

From this characteristic, the peak value Pmax of the output power when an output voltage of 21.1 V (rms) is obtained at a load current of 24.6 mA (rms) by the piezoelectric ceramic transformer of the embodiment of FIGS. = 519 mW. Here, in the second embodiment of FIGS. 8 and 9, two input electrode pairs (61, 71) and (63, 73) are arranged in the input section and connected in parallel, and one output electrode pair (62) is output section. , 72), but if you want to increase the input impedance,
Input electrode pair (61, 71), (63, 73)
A pair of electrodes may be connected in series, and when a high input impedance is required, the number of input electrode pairs may be increased and connected in series. To increase the output impedance, the number of output electrode pairs may be increased and connected in series.

In the above-described embodiment, a rectangular pattern is used as the electrode shape arranged on the piezoelectric ceramic plate 10, but an appropriate shape pattern such as a comb shape or a rectangular spiral type can be used. Further, the present invention is not limited by the numerical values shown in the above embodiments.

[0040]

As described above, the piezoelectric ceramic transformer of the present invention excites the piezoelectric ceramic plate by using the thickness-shear vibration mode and takes out an output voltage.
It can be used in a high frequency band of z to several MHz or more. In addition, the resonance frequency of the thickness-shear vibration mode is determined by the thickness of the piezoelectric ceramic transformer, and is not affected by the length or width. It is possible to achieve both power extraction.

Further, the piezoelectric ceramic transformer of the present invention can be configured by appropriately selecting the electrode arrangement and the connection of the external terminals.
The input impedance and the output impedance can be freely selected.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram of input / output connections of FIG. 1;

FIG. 3 is an explanatory diagram of displacement generated in a piezoelectric ceramic plate when the piezoelectric ceramic transformer of FIG. 2 is driven in a thickness shear vibration mode.

FIG. 4 is a characteristic diagram of output voltage and output power with respect to load current measured for the piezoelectric ceramic transformer of FIG. 2;

FIG. 5 is an explanatory diagram of an input / output connection in which the input is high impedance and the output is low impedance in the first embodiment of FIG. 1;

FIG. 6 is an explanatory diagram of an input / output connection in which the input has a low impedance and the output has a high impedance in the first embodiment of FIG. 1;

FIG. 7 is an explanatory view of an embodiment in which the input is connected to a high impedance and the output is a low impedance in which electrodes are put together for the piezoelectric ceramic transformer of the present invention.

FIG. 8 is an explanatory view of a piezoelectric ceramic transformer according to a second embodiment of the present invention.

FIG. 9 is an explanatory diagram of the input / output connection of FIG. 8;

FIG. 10 is an explanatory diagram of displacement generated in a piezoelectric ceramic plate when the piezoelectric ceramic transformer of FIG. 9 is driven in a thickness shear vibration mode.

11 is a characteristic diagram of output voltage and output power with respect to load current measured for the piezoelectric ceramic transformer of FIG. 9;

FIG. 12 is an explanatory diagram of a conventional Rosen-type piezoelectric ceramic transformer.

[Explanation of symbols]

10: Piezoelectric ceramic plates 11 to 16, 19, 20, 21 to 26, 61 to 63, 7
1-73: Electrode 18: Polarization direction 31-36, 41-46, 81-83, 91-93: Lead terminal 51, 52: Input terminal 53, 54: Output terminal

Claims (7)

[Claims] A piezoelectric ceramic plate composed of a plate-like member and uniformly polarized in a direction perpendicular to a thickness direction of the plate; and a piezoelectric ceramic plate disposed opposite to both surfaces located in a thickness direction of the piezoelectric ceramic plate; An input electrode pair that excites the piezoelectric ceramic plate by applying an AC voltage having a frequency near the resonance frequency of the thickness shear vibration mode, and opposing both surfaces of the piezoelectric ceramic plate in the thickness direction and the input electrode pair And a pair of output electrodes for extracting an alternating voltage induced by the excitation of the piezoelectric ceramic plate by the pair of input electrodes. 2. The piezoelectric ceramic transformer according to claim 1, wherein said input electrode pair and said output electrode pair are arranged on said piezoelectric ceramic plate in a direction parallel to said polarization direction. Porcelain transformer. 3. A piezoelectric ceramic transformer according to claim 1, wherein said pair of input electrodes and said pair of output electrodes are arranged on said piezoelectric ceramic plate in a direction perpendicular to said polarization direction. Porcelain transformer. 4. The piezoelectric ceramic transformer according to claim 1, wherein a plurality of input electrode pairs and a plurality of output electrode pairs are arranged on said piezoelectric ceramic plate, and said plurality of input electrode pairs are connected in series or in parallel. A piezoelectric ceramic transformer wherein the input impedance is set to a desired value, and the output impedance is set to a desired value by connecting the output electrode pairs in series or in parallel. 5. The piezoelectric ceramic transformer according to claim 4, wherein a plurality of input electrode pairs and a plurality of output electrode pairs are arranged on the piezoelectric ceramic plate, and the setting of high impedance is performed by the plurality of input electrode pairs and the plurality of output electrode pairs. Connecting a plurality of output electrode pairs in series,
The piezoelectric ceramic transformer according to claim 1, wherein the plurality of input electrode pairs and the plurality of output electrode pairs are connected in parallel to set the low impedance. 6. The piezoelectric ceramic transformer according to claim 4, wherein a plurality of input electrode pairs and a plurality of output electrode pairs are arranged alternately. 7. The piezoelectric ceramic transformer according to claim 4, wherein one of the plurality of input electrode pairs and the plurality of output electrode pairs are arranged in one place and the other is arranged in one electrode pair. A piezoelectric ceramic transformer characterized by: