JP2002319718A - Piezoelectric transformer and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric transformer with improved characteristics, and to provide a method for manufacturing the same. SOLUTION: A piezoelectric transformer 40 consists of an input section, having a structure in which plural layers of piezoelectric bodies 41 and plural layers of inner electrodes 42 are alternately laminated and an output section, consisting of a single layer of a piezoelectric body 43. The value ε1 /ε2 , obtained by dividing a dielectric constant ε1 of the input section by a dielectric constant ε2 of the output section is set to 0.8-1.2. Such a piezoelectric transformer 40 can be manufactured, in such a way that, e.g. a green sheet is manufactured by using a piezoelectric ceramic powder containing a silver powder or a compound, to be changed into silver by heating of 0.1 wt.%-1.5 wt.% (expressed in terms of silver), a conductive paste containing a silver is printed on the surface of the sheet where the input section is formed at laminating of the green sheet, and the resulting body is integrally baked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric transformer used for a high-voltage power supply for lighting a backlight of a liquid crystal display device and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, a piezoelectric transformer which has been used as a power source for lighting a backlight of a liquid crystal display device has
In 1957, C. of the United States of America. E. FIG. It is based on the one invented by Rosen, and has a single-plate type structure such as a piezoelectric transformer 30 shown in FIG.
There is known a laminated structure such as a piezoelectric transformer 40 shown in FIG.

In a single-plate type piezoelectric transformer 30, one half of the longitudinal direction of a rectangular plate-shaped piezoelectric body 31 is an input portion (primary side) having input electrodes 32a and 32b formed on its main surface. The other half of the longitudinal direction is an output portion (secondary side) having an output electrode 32c formed on its end face.
The laminated piezoelectric transformer 40 has an input portion in which thin piezoelectric members 41 and internal electrodes 42 are alternately stacked in a plurality of layers in the thickness direction, and an output portion including a single-layer (bulk) piezoelectric member 43. And an output electrode 4 on the end face of the piezoelectric body 43.
4 is formed. The internal electrode 42
Are connected alternately to form a pair of electrodes.

As a piezoelectric body (piezoelectric material) used for the piezoelectric transformers 30 and 40, lead zirconate titanate (PZ) is used.
T) as a main component, and strontium (Sr), niobium (Nb), antimony (Sb), iron (Fe), manganese (Mn) and the like in order to improve predetermined characteristics.
Or, in combination, a plurality of piezoelectric ceramics generally added in the form of individual oxides are widely used,
For example, the laminated piezoelectric transformer 40 is generally formed by forming a piezoelectric ceramic powder into a sheet by using a sheet forming technique such as a doctor blade method, and then punching the sheet into a predetermined shape. It is manufactured through a process of laminating internal electrode pastes at predetermined positions by screen printing or the like, pressing and integrating them, and then firing.

[0005] A so-called integral firing (simultaneous firing, in which the piezoelectric body 41 and the internal electrode 42 are simultaneously fired and formed).
Co-firing) is usually performed under an oxygen concentration atmosphere equal to or higher than the air atmosphere. This is due to the fact that lead zirconate titanate-based piezoelectric ceramics cannot be sintered in a low-oxygen atmosphere due to the compositional deviation caused by evaporation of the lead component. As the electrode material, a material that is hardly oxidized at high temperature, for example, a noble metal electrode such as silver / palladium (Ag / Pd), palladium (Pd), and platinum (Pt) is used.
Generally, considering the product cost, the palladium content is 2
A silver / palladium electrode of 0% to 40% by weight is used.

[0006]

However, when the above-described integral firing method is used, the input portion has a laminated structure composed of piezoelectric ceramics and internal electrodes, but the output portion has green sheets integrated with each other. It is in bulk and does not contain metal electrodes. For this reason, in the laminated type piezoelectric transformer 40, the degree of progress of sintering is likely to be different due to the difference in shape and the like of the piezoelectric body to be sintered between the input portion and the output portion. In this case, there is a problem that a characteristic difference occurs in the piezoelectric ceramics, and the original characteristics of the piezoelectric transformer expected from the material characteristics of the piezoelectric ceramics cannot be obtained.

In the case where a piezoelectric ceramic material of lead zirconate titanate is used as the piezoelectric body, when an internal electrode material containing silver is used, silver diffuses into the piezoelectric ceramic during firing, and as a result, Then, the characteristics (relative permittivity, sound velocity, elastic coefficient, etc.) of the piezoelectric ceramic of the input section change. Also in this case, this is synonymous with using piezoelectric ceramics having different characteristics between the input part and the output part, and there is a problem that only characteristics lower than those of the original piezoelectric transformer can be obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has been achieved by reducing the difference in characteristics between the piezoelectric material constituting the input portion and the piezoelectric material constituting the output portion. Another object of the present invention is to provide a piezoelectric transformer having improved characteristics and a method of manufacturing the same.

[0009]

That is, according to the present invention, there is provided a piezoelectric transformer in which an input portion is formed on one half in the longitudinal direction of a strip-shaped plate and an output portion is formed on the other. The input unit has a stacked structure in which a plurality of piezoelectric layers and internal electrode layers are alternately stacked in the thickness direction of the plate-like body, and the output unit is formed of a single-layer piezoelectric body, A piezoelectric transformer, wherein a value ε ₁ / ε _{2 obtained} by dividing the relative permittivity ε ₁ of the portion by the relative permittivity ε ₂ of the output portion is 0.8 or more and 1.2 or less. .

Further, according to the present invention, as a method of manufacturing a piezoelectric transformer having such characteristics, the following first method will be described.
Provides a third method for manufacturing a piezoelectric transformer. That is, according to the present invention, as a first method of manufacturing a piezoelectric transformer, an input portion formed by alternately stacking a plurality of piezoelectric layers and internal electrode layers in a thickness direction, and an output formed by a single-layer piezoelectric material are provided. And a piezoelectric ceramic powder containing a silver powder or a compound which becomes silver when heated during baking in an amount of 0.1% by mass or more and 1.5% by mass or less in terms of silver. First to make a green sheet using
A second step of printing a conductive paste containing silver on a sheet surface of a portion where the input section is formed when the green sheets are laminated; and laminating the green sheets obtained in the second step to form an integrated body. And a third step of sintering and firing.

According to the second aspect of the present invention, as a second method for manufacturing a piezoelectric transformer, an input section in which a plurality of piezoelectric layers and internal electrode layers containing silver are alternately stacked in a thickness direction, and a single-layer piezoelectric section are provided. A method for manufacturing a strip-shaped piezoelectric transformer having an output part made of a body, comprising: a first step of producing a green sheet using piezoelectric ceramic powder; and forming the input part when the green sheets are laminated. A conductive material containing silver is printed on the sheet surface of a portion to be formed, and a predetermined amount of silver or a compound which becomes silver when heated during firing is added to the sheet surface of the portion forming the output portion. A second step of printing, applying, or spraying the paste or slurry, and a third step of laminating, integrating and firing the green sheets obtained in the second step. The method of manufacturing a piezoelectric transformer which, is provided.

According to the third aspect of the present invention, as a third method for manufacturing a piezoelectric transformer, an input portion in which a plurality of piezoelectric layers and internal electrode layers containing silver are alternately stacked in a thickness direction, and a single-layer piezoelectric A method for manufacturing a strip-shaped piezoelectric transformer having an output part made of a body, comprising: a first step of manufacturing a green sheet using piezoelectric ceramic powder; and forming the input part when the green sheets are laminated. A second step of printing a conductive paste containing silver on a part of the sheet surface, a third step of stacking and integrating the green sheets obtained in the second step, and a molded article obtained in the third step Is placed on an alloy plate that contains 10% by volume or more of silver and does not melt at a predetermined firing temperature.
And a method for manufacturing a piezoelectric transformer, comprising the steps of:

In such a piezoelectric transformer of the present invention, when the internal electrode layer contains silver (Ag) as one of the main components, it is preferable that the piezoelectric material constituting the output section also contains silver. According to the first to third manufacturing methods, an appropriate amount of silver can be easily contained in the piezoelectric body constituting the output section of the piezoelectric transformer. By matching the characteristics of the input section and the output section as in the piezoelectric transformer of the present invention, even when a piezoelectric body having the same composition as that of the related art is used,
It is possible to obtain a piezoelectric transformer exhibiting higher characteristics.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In the following, an embodiment of the piezoelectric transformer of the present invention will be described in which silver is used as one of the main components as the internal electrode of the input section. The case will be described.

As described above, the piezoelectric transformer according to the present invention has the same structure as the piezoelectric transformer 40 shown in FIG.
That is, an input portion is formed on one half of the longitudinal direction of the strip-shaped plate, and an output portion is formed on the other,
The input unit has a laminated structure in which a plurality of thin piezoelectric members 41 and internal electrodes 42 are alternately laminated in the thickness direction, and the output unit has a structure including a single-layer (bulk) piezoelectric member 43. I have. Then, when the piezoelectric transformer of the present invention, the dielectric constant of the input unit and epsilon _1, the relative dielectric constant of the output section was epsilon _2,
The value obtained by dividing the relative dielectric constant ε ₁ by the relative dielectric constant ε ₂ (ε ₁ / ε ₂ )
Is 0.8 or more and 1.2 or less.

One embodiment of a method for manufacturing a piezoelectric transformer having the above characteristics when silver / palladium is used as an internal electrode material is as follows. That is, first, a piezoelectric ceramic powder having a predetermined composition, for example, lead zirconate titanate-based piezoelectric ceramic powder,
A predetermined amount of silver powder is added and mixed uniformly. Next, a ceramic green sheet (hereinafter, referred to as a “green sheet”) is manufactured using the silver-containing piezoelectric ceramic powder thus manufactured. For the production of the green sheet, a known method, for example, a doctor blade method, an extrusion molding method, a calendar roll method, or the like can be used. The thickness of the green sheet to be formed is, for example, 50 μm to 200 μm after firing.
Adjust to be μm.

The green sheet thus produced is subjected to punching or cutting in consideration of shrinkage during firing and processing margin, and a sheet having a predetermined shape (hereinafter referred to as “printing sheet”) adapted to the strip shape of the piezoelectric transformer to be produced. That)
Get. Here, when the area of the front and back faces of the piezoelectric transformer to produce is small, it is preferable to adjust the size of the printing sheet to include a plurality of piezoelectric transformer in it.

A paste of an internal electrode material (hereinafter referred to as "internal electrode paste") is printed on a half area in the longitudinal direction of the printing sheet by a screen printing method or the like.
Here, in printing the internal electrode paste, for example, the printing thickness is adjusted so as to be about 2 μm to 5 μm after firing.
In addition, it is desirable to define a pattern for printing the internal electrode paste so that the internal electrodes to be formed can be easily connected every other layer thereafter.

A predetermined number of printing sheets on which the internal electrode paste is printed are aligned and laminated by a predetermined number, and the printing sheets thus laminated are bonded together by thermocompression using a hot press or the like. Next, the pressed body thus obtained is fired under predetermined conditions. During this firing, silver diffuses from the internal electrode material into the piezoelectric ceramic in the input portion. Grinding or polishing is performed on the side surface or surface of the obtained fired body as necessary to adjust the shape.

Next, using silver paste or the like, the internal electrodes of the input section are connected alternately to form a pair of electrodes, and after forming an output electrode on the end face of the output section, Treat at temperature and bake silver paste etc. Usually, the baking process of the silver paste or the like is performed at a temperature lower than the baking temperature. Then, a lead wire is attached to the formed silver electrode as needed.

Subsequently, a predetermined voltage is applied between a pair of electrodes provided on the input section and an electrode provided on an end face of the output section to perform polarization processing on the output section. The piezoelectric transformer is manufactured by applying a predetermined voltage between a pair of electrodes provided in the above and performing polarization processing of the input part. The polarization process is performed at a predetermined temperature lower than the Curie point of the piezoelectric ceramic for a predetermined time.

According to the above-described piezoelectric transformer manufacturing method, a lead zirconate titanate-based piezoelectric ceramic material whose relative dielectric constant is increased by adding a predetermined amount of silver is used, and the amount of silver added to the piezoelectric ceramic powder is determined. Table 1 shows the results of measuring the relative dielectric constant and the efficiency of the piezoelectric transformers (Samples 1 to 6) manufactured by changing the values. Also, lead zirconate titanate whose relative dielectric constant is reduced by adding a predetermined amount of silver. Table 2 shows the results of measuring the relative permittivity and the efficiency of piezoelectric transformers (Samples 7 to 12) manufactured by using a piezoelectric ceramic material and changing the amount of silver added to the piezoelectric ceramic powder. Here, these samples 1
The green sheet produced for producing the piezoelectric transformer of Sample No. 12 is formed so as to have a thickness of about 60 μm after firing, and the input portion has a laminated structure of 21 layers.

[0023]

[Table 1]

[0024]

[Table 2]

The values of the relative dielectric constants ε ₁ and ε ₂ of the input and output portions of the piezoelectric transformers (samples 1 to 12) shown in Tables 1 and 2 are shown in FIGS. ),
Impedance gain phase analyzer (IGA) 2
0, 1 V, 1 between a pair of electrodes provided in the input unit.
A voltage of 1 kHz is applied to measure the relative permittivity ε ₁ of the input portion, and a pair of electrodes provided at the input portion is short-circuited, and 1 V, 1 kHz is applied between the short-circuited electrode and the output electrode.
Is obtained by a voltage is applied obtained by measuring the dielectric constant epsilon ₂ of the output unit. However, the measurement voltage and the measurement frequency are not limited to these values, and another measurement device or the like may be used.

The efficiencies of the piezoelectric transformers (samples 1 to 12) shown in Tables 1 and 2 are determined by connecting a 170 kΩ resistor as an external load and an ammeter to the output of the piezoelectric transformer. The input section is connected to a frequency generator, an amplifier for amplification and a wattmeter. First, the sine wave voltage is changed from the frequency generator to the piezoelectric transformer, and the ammeter connected to the output section is connected to the output section. The frequency at which the indicated value is the largest is searched for, and then the input voltage is adjusted in a state where the frequency is fixed at the searched frequency, thereby controlling the current value of the output unit so that the power on the output side becomes, for example, 1 W. Then, the output power at this time (1 W = (external load resistance) ×
(Current value) 2) was obtained by dividing by the input power indicated by the wattmeter.

As shown in Table 1, Sample 1 which is a conventional piezoelectric transformer without adding silver to the piezoelectric ceramic powder was used.
In, the dielectric constant epsilon ₁ of the input portion is larger than the dielectric constant epsilon ₂ of the output unit. Moreover, as it is clear when looking at the change in the output portion of the dielectric constant epsilon ₂ in samples 1 to 6,
The dielectric constant of the output portion as the addition of silver to the piezoelectric ceramic powder is increased and becomes larger, the dielectric constant epsilon ₂ of the output of the sample 6, the dielectric constant epsilon ₁ of the input portion of the sample 1 The values are almost the same. On the other hand, the dielectric constant epsilon ₁ of change of the input portion is extremely small compared to the output unit, hardly changed even by the addition of silver to the piezoelectric ceramic powder. As a result, in Sample 6, the dielectric constant of the input section epsilon ₁ and a dielectric constant epsilon ₂ of the output section indicates a substantially equal value. further,
It can be seen that the efficiency increases as the relative permittivity ratio (ε ₁ / ε ₂ ) approaches 1.

The reason why the change in the relative permittivity ε _{2 at} the output portion is large and the change in the relative permittivity ε _{1 at} the input portion is small is that silver is uniformly dispersed in The effect of increasing the relative dielectric constant of ceramics is significant when the amount of silver added is very small and less than a predetermined amount. However, when silver is contained in a certain amount or more, this effect decreases and the relative dielectric constant decreases. It is considered that the rate hardly changed.

The results shown in Table 2 can be considered in the same manner as the results shown in Table 1. In other words, large specific change in the dielectric constant epsilon ₂ at the output, the dielectric constant at the input epsilon
The phenomenon that the change in ( ₁ ) is small is similar to the case of a lead zirconate titanate-based piezoelectric ceramic material in which the relative dielectric constant is reduced by adding silver, and silver is uniformly dispersed in the piezoelectric ceramic. In silver, the effect of lowering the relative dielectric constant of the piezoelectric ceramic is significant when the amount of silver added is very small and is less than a predetermined amount, but when silver is contained in a certain amount or more, this effect is reduced. This is because the relative permittivity hardly changes with the decrease.

For this reason, silver is a dielectric material of piezoelectric ceramics.
Whether to increase or decrease the rate
However, when manufacturing a piezoelectric transformer,
By including a predetermined amount of silver in the box,
And the ratio of the relative permittivity of the output section (ε ₁/ Ε₂) To 1
To manufacture piezoelectric transformers with high efficiency.
It works. At this time, the amount of silver added is not sufficient to obtain the predetermined efficiency.
To the extent possible, considering product costs
preferable. Also, from Tables 1 and 2, the input unit and the output unit
Relative dielectric constant ratio (ε₁/ Ε₂) Is 0.8 or more and 1.2 or less
By keeping it within the range of
Higher efficiency than conventional piezoelectric transformers is obtained and is preferred.

The amount of silver added to make the relative dielectric constant ratio (ε ₁ / ε ₂ ) 0.8 or more and 1.2 or less varies depending on the type and composition of the piezoelectric ceramic material used. Therefore, the amount of silver added to the piezoelectric ceramics (proportion of silver contained in the total mass of the piezoelectric ceramics and silver) for producing a piezoelectric transformer having an efficiency of 95% or more is shown in Table 1.
And as shown in Table 2, it is not limited to the range of 0.9% by mass or more and 1.5% by mass or less. Also, even if the thickness of the green sheet is changed, the thickness of the internal electrode is not usually changed, so the amount of silver added to the piezoelectric ceramic when manufacturing a piezoelectric transformer exhibiting high efficiency is determined by the thickness of the green sheet to be manufactured. It also changes by. However, in the case of a general lead zirconate titanate-based piezoelectric ceramic material, the added amount of silver is 0.1% by mass to 1.5% by mass.
It is preferable to set the following. This is because the amount of silver added is 0.1.
When the amount is less than 1% by mass, the effect of matching the relative permittivity of the input portion and the output portion does not appear. On the other hand, when the amount of silver added exceeds 1.5% by mass, the cost increases and silver aggregation is likely to occur. This is because there is a possibility that the efficiency may be reduced.

Next, another method of manufacturing a piezoelectric transformer in which the relative permittivity of the input section and the output section are matched will be described. In the method of manufacturing the piezoelectric transformer, a predetermined amount of silver powder was added to the piezoelectric ceramic powder to produce a green sheet.However, the piezoelectric ceramic is a compound that becomes silver when decomposed when heated during firing, for example, , Silver oxide (Ag ₂ O), silver carbonate (Ag ₂ CO ₃ ), silver oxalate (Ag
₂ C ₂ O ₄ ), silver acetate (CH ₃ COOAg), silver alkoxide, and the like can be added. A known method using a ball mill or the like can be used for mixing these silver compounds or silver powder with the piezoelectric ceramics. When the silver compound is water-soluble, it is also possible to disperse the piezoelectric ceramic powder in an aqueous solution containing silver ions and prepare a powder for producing a green sheet by using a spray heat drying method or the like.

As the silver compound, silver nitrate (AgNO ₃ ), silver chloride (AgCl) and the like can be used. However, when these compounds are used, nitric oxide gas (N
O _X) and generates a chlorine gas (Cl _2), also, these gases in order to corrosion of the burning facility, need arises to address these problems.

As another method of matching the characteristics of the input portion and the output portion of the piezoelectric transformer, a green sheet is produced by using a piezoelectric ceramic powder to which silver is not added, and the green sheet is obtained by punching or the like. A conductive paste containing silver is printed on a portion forming an input portion of the printing sheet, and silver or a compound which becomes silver when heated during firing (hereinafter referred to as “silver or the like”) is printed on a portion forming an output portion. The output portion is made to contain silver by printing, applying or spraying the paste or slurry of the added piezoelectric ceramic powder (hereinafter referred to as “paste or the like”), and the printing sheet thus produced is laminated, integrated and fired. Method.

In this case, the internal electrodes formed of the conductive paste and the part of the output portion formed of the paste of the piezoelectric ceramic powder to which silver or the like is added are not electrically connected so that the piezoelectric ceramics are not electrically connected. It is necessary to determine the amount of silver or the like to be added to the powder. For example, if the volume ratio of silver is less than 30%, a portion formed by a paste of a piezoelectric ceramic powder to which silver or the like is added is not usually made conductive. Further, the application amount of the paste of the piezoelectric ceramic powder to which silver or the like is added is controlled such that the total amount of silver contained in the entire output portion after firing is 0.1% by mass or more and 1.5% by mass or less. Is preferred.

As still another method of matching the characteristics of the input portion and the output portion of the piezoelectric transformer, a green sheet is prepared using a piezoelectric ceramic powder containing no silver, and a green sheet is formed by punching the green sheet. Print the conductive paste containing silver on the part forming the input part of the sheet for
The printing sheet is laminated and integrated without any treatment on the portion forming the output portion, and the formed body is formed on an alloy plate containing 10% by volume or more of silver and not melting at the firing temperature. And sintering.

This method is preferably used when the thickness of the compact placed on the alloy plate is equal to or less than the distance at which silver diffuses from the alloy plate. Further, when an alloy plate having a predetermined thickness is further placed on the compact placed on the alloy plate, a thicker compact can be fired. However, the alloy plate placed on the compact needs to have an appropriate weight so as not to hinder the sintering of the compact.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, even when a material that does not contain silver, for example, platinum is used as the internal electrode material of the input unit, the piezoelectric ceramic may differ depending on whether the input unit and the output unit have a laminated structure or a single layer. There is a difference in the progress of the sintering of the piezoelectric element, thereby increasing the difference in the relative permittivity between the input part and the output part, and it may not be possible to obtain the expected characteristics of the piezoelectric transformer. In this case, for example, the shape and sintering characteristics of the platinum powder used for the internal electrode paste, the composition of the frit to be added to the paste, and the like are examined.
By making the sintering behavior of the input portion close to the sintering behavior of the output portion, it is possible to reduce the difference in the relative dielectric constant between the input portion and the output portion, and improve the characteristics of the piezoelectric transformer.

When one of the main components of the internal electrode of the input portion is silver, and when a piezoelectric ceramic material having a property such that silver does not diffuse into the piezoelectric ceramic is used, as a result, the platinum is removed from the platinum. As in the case where the internal electrodes are used, by bringing the sintering behaviors of the piezoelectric ceramics of the input portion and the output portion close to each other, it is possible to reduce the difference in characteristics such as the relative permittivity between the input portion and the output portion.

[0040]

As described above, according to the piezoelectric transformer of the present invention and the method of manufacturing the same, it is possible to easily make the relative permittivity of the input part and the output part equal, thereby achieving the same composition as the conventional one. However, even when a piezoelectric body having the following characteristics is used, it is possible to obtain a piezoelectric transformer having higher characteristics.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the structure of a piezoelectric transformer.

FIG. 2 is an explanatory diagram showing a method for measuring the relative permittivity of an input unit and an output unit of a laminated piezoelectric transformer.

[Explanation of symbols]

20; Impedance gain phase analyzer (IG
A) 30; piezoelectric transformer (single-plate type) 31; piezoelectric body 32a / 32b; input electrode 32c; output electrode 40; piezoelectric transformer (laminated type) 41; piezoelectric body (input section) 42; internal electrode 43; Body (output part) 44; output electrode

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masayuki Watanabe 2-4-2 Daisaku, Sakura City, Chiba Prefecture Inside the Cement Co., Ltd. (72) Ryoichi Fukunaga 2-4-2 Daisaku, Sakura City, Chiba Prefecture Pacific Within Cement Co., Ltd. (72) Inventor Junko Seki 2-4-2 Daisaku, Sakura City, Chiba Prefecture Pacific Cement Co., Ltd. F-term (reference) 4G031 AA11 AA12 AA32 AA39 BA09 BA10 CA03 CA08 GA06

Claims (5)

[Claims] 1. A piezoelectric transformer in which an input portion is formed on one half of a longitudinal direction of a strip-shaped plate member and an output portion is formed on the other half thereof, wherein the input portion includes a plurality of piezoelectric layers. An internal electrode layer having a laminated structure alternately laminated in the thickness direction of the plate-like body, wherein the output section is formed of a single-layer piezoelectric body, and the relative permittivity ε ₁ of the input section is set to Relative permittivity ε ₂
Wherein the value ε ₁ / ε ₂ divided by is not less than 0.8 and not more than 1.2. 2. The piezoelectric device according to claim 1, wherein the internal electrode layer contains silver (Ag) as one of its main components, and silver is contained in a piezoelectric body constituting the output section. Trance. 3. A method for manufacturing a strip-shaped piezoelectric transformer having an input portion in which a plurality of piezoelectric layers and internal electrode layers are alternately stacked in a thickness direction, and an output portion made of a single-layer piezoelectric material. A first step of preparing a green sheet using a piezoelectric ceramic powder containing silver powder or a compound which becomes silver when heated during firing in a silver equivalent of 0.1% by mass or more and 1.5% by mass or less; A second step of printing a conductive paste containing silver on the surface of the sheet where the input section is formed when the green sheets are laminated; and laminating, integrating and firing the green sheets obtained in the second step. A method for manufacturing a piezoelectric transformer, comprising: a third step. 4. A strip-shaped piezoelectric transformer having an input portion in which a plurality of piezoelectric layers and an internal electrode layer containing silver are alternately stacked in a thickness direction, and an output portion made of a single-layer piezoelectric body. A manufacturing method, comprising: a first step of producing a green sheet using piezoelectric ceramic powder; and, when laminating the green sheets, printing a conductive paste containing silver on a sheet surface of a portion where the input section is formed. A second step of printing, applying or spraying a paste or slurry of a piezoelectric material to which a predetermined amount of silver or a compound which becomes silver when heated during baking is added to the sheet surface of the portion forming the output section. And a third step of laminating, integrating and firing the green sheets obtained in the second step, and firing the green sheets. 5. A strip-shaped piezoelectric transformer having an input portion in which a plurality of piezoelectric layers and an internal electrode layer containing silver are alternately stacked in a thickness direction, and an output portion made of a single-layer piezoelectric body. A manufacturing method, comprising: a first step of producing a green sheet using piezoelectric ceramic powder; and a step of printing a conductive paste containing silver on a sheet surface of a portion where the input section is formed when the green sheets are laminated. Two steps; a third step of laminating and integrating the green sheets obtained in the second step; and forming the green body obtained in the third step in an amount of at least 10% by volume of silver; A fourth step of mounting and firing on an alloy plate that does not melt at the firing temperature.