JPH07176804A - Piezoelectric porcelain transformer and its drive - Google Patents

Abstract

PURPOSE:To make it possible to launch the high-power drive of a piezo-electric porcelain transformer in a low-input voltage and to make it possible to lead out easily a high voltage by a method wherein a plurality of internal electrodes and a plurality of piezoelectric porcelain layers are alternately laminated in the direction of the board thickness of the transformer in the part of 1/3 or shorter of a piezo-electric porcelain transformer length and the transformer is driven in a length longitudinal tertiary mode. CONSTITUTION:As the material for a piezoelectric porcelain, a PZT piezo-electric porcelain is used and internal electrodes are formed by a method, wherein a Pt paste is subjected to screen printing on a green sheet, which is a piezoelectric material, and is calcined integrally along with the piezoelectric material. Low-impedance parts 8L and 8R are formed into a laminated structure, wherein four layers of active piezoelectric porcelain layers 6L and five layers of the internal electrodes 5L and four layers of active piezoelectric porcelain layers 6R and five layers of the internal electrodes 5R are respectively laminated alternately and moreover, the laminated materials respectively have an inactive piezoelectric porcelain layer one layer by one layer on their upper and as an insulator, is made to adhere on the exposed parts of the side surfaces of their respective active layers 6L and 6R alternately in the left and right on every other layer by an electrophoresis method, an Ag paste is applied and calcined to form external electrodes.

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 used in various high-voltage generating power supply circuits and a method of driving the same, and particularly to a compact, thin and high-voltage device that requires miniaturization and high reliability. The present invention relates to a piezoelectric ceramic transformer and a driving method thereof.

[0002]

2. Description of the Related Art Conventionally, a winding type electromagnetic transformer has been used as a transformer element for generating a high voltage in a power supply circuit in a device requiring a high voltage such as a deflecting device for a television or a charging device for a copying machine. . This electromagnetic transformer has a structure in which a conductor wire is wound around a magnetic core, and it is necessary to increase the number of conductor wires wound in order to realize a high transformation ratio. That is, it is indispensable to wind the conductor wire at least hundreds to thousands of times. Therefore, in order to realize a small and thin electromagnetic transformer, it must first be an ultrafine wire,
The copper loss inevitably increased, and the miniaturization and high efficiency of the electromagnetic transformer conflicted with each other.

On the other hand, a piezoelectric ceramic transformer using a piezoelectric effect (hereinafter referred to as a piezoelectric transformer) has been proposed. FIG. 6 shows the structure of a conventional Rosen type piezoelectric transformer, which is a typical piezoelectric transformer. Hereinafter, description will be given with reference to the drawings. A low-impedance drive unit 61 of a piezoelectric transformer made of a piezoelectric plate having electrodes on its surface is provided with counter electrodes 63 and 64 on its upper and lower surfaces.
It is polarized in the thickness direction as shown by the thick arrow in the figure.
Further, an electrode 65 is provided on the end surface of the high impedance power generation unit 62, and the power generation unit 62 is polarized in the length direction of the piezoelectric plate as indicated by a thick arrow in the figure.

The operation of this piezoelectric transformer is as follows. When a voltage is applied to the drive electrodes 63 and 64 from the external terminals 66 and 67, an electric field is applied in the polarization direction in the drive unit 61, and the length is changed by the piezoelectric effect (piezoelectric lateral effect 31 mode) that is displaced in the direction perpendicular to the polarization direction. Longitudinal vibration is excited,
The whole transformer vibrates. Further, in the power generation unit 62, the output electrode 65 is driven by the piezoelectric effect (piezoelectric longitudinal effect 33) mode in which mechanical strain occurs in the polarization direction and a potential difference occurs in the polarization direction.
A voltage having the same frequency as the input voltage is taken out from the external terminal 68. At this time, if the drive frequency is made equal to the resonance frequency of the piezoelectric transformer, a very high output voltage can be obtained. When inputting a high voltage and outputting a low voltage,
The vertical effect high impedance portion 62 may be the input side, and the horizontal effect low impedance portion 61 may be the output side.

This piezoelectric transformer is used in a resonance state,
Compared with general electromagnetic transformers, (1) the winding structure is unnecessary and the energy density is high, so it can be made smaller and thinner, (2) non-combustible, (3) no electromagnetic induction noise, It has many advantages.

[0006]

In the above-mentioned conventional Rosen type piezoelectric transformer, since the electrode 65 of the power generation section 62 is located at the antinode of vibration, the connection of the external terminal 68 increases the vibration loss, or There was an accident in which the lead wire connecting the power generating electrode 65 and the external terminal 68 was cut during high power driving, and there was a problem in terms of reliability.

Further, the load resistance (for example, 10 to 100 M) is extremely large as compared with the output impedance of the piezoelectric transformer.
Ω), a high output voltage can be obtained, but if the value of the load resistance is not so large, there is a drawback that a high output voltage cannot be obtained.

Further, in the conventional Rosen type transformer,
In order to drive a large amplitude at a low voltage, the plate thickness must be extremely thin. In this case, first of all, the output impedance of the transformer may become too large, causing an impedance mismatch with the load impedance.
It is difficult to obtain a high output voltage at a substantially low voltage. Secondly, the volume of the transformer becomes too small and sufficient output power cannot be obtained.

Therefore, it is an object of the present invention to realize a piezoelectric transformer capable of taking out sufficient output power even at a low input voltage, and further to provide a highly reliable piezoelectric transformer.

[0010]

According to the piezoelectric ceramic transformer of the present invention, the internal electrode and the piezoelectric ceramic are respectively provided at the maximum one-third or less of the total piezoelectric ceramic transformer length from each of the two end faces in the longitudinal direction. Two low impedance parts with a structure in which layers are alternately laminated in the plate thickness direction, and the piezoelectric ceramic layers facing each other with each internal electrode sandwiched are polarized in opposite directions with respect to the axis in the lamination direction. In the central portion in the length direction, a pair of electrodes facing each other on two surfaces facing each other perpendicular to the plate thickness direction axis, the piezoelectric ceramic layer between the pair of electrodes is the plate thickness. It is characterized in that it has a high impedance portion having a structure that is polarized in the direction, and operates in a lengthwise third-order mode.

Further, in the piezoelectric ceramic transformer of the present invention, the internal electrodes and the piezoelectric ceramic layers are formed on the respective portions of the two end faces in the longitudinal direction at the maximum one-third or less of the total length of the piezoelectric ceramic transformer. It has two low impedance parts with a structure in which a plurality of layers are alternately laminated in the thickness direction, and the piezoelectric ceramic layers facing each other with each internal electrode sandwiched are polarized in opposite directions with respect to the axis of the lamination direction. The central portion in the depth direction has a pair of electrodes facing each other on two surfaces facing each other perpendicular to the plate width direction axis, and the piezoelectric ceramic layer between the pair of electrodes is polarized in the plate width direction. It is characterized in that it has a high impedance part of the structure described above and operates in a lengthwise third-order mode.

The piezoelectric ceramic transformer of the present invention is a method for driving the piezoelectric ceramic transformer according to claim 1 or 2, wherein the two low impedance portions are input portions and the high impedance portion is output. Driving the two low impedance portions in the same phase while applying an AC input voltage to each of the low impedance portions so that the internal electrodes forming each of them have the same potential every other layer. However, by extracting the output voltage from the high impedance portion, a high output voltage can be efficiently obtained with a low input voltage.

[0013]

The piezoelectric transformer according to the present invention is, as shown in FIG. 1, one third of the total length of the piezoelectric transformer from the left end face in the length direction.
A plurality of internal electrodes 5L and a piezoelectric ceramic layer 6 are provided in the following length part.
The low impedance portion 8L has a structure in which L and L are alternately laminated in the thickness direction. Further, a low impedance portion 8R having a structure in which a plurality of internal electrodes 5R and piezoelectric ceramic layers 6R are alternately laminated in the thickness direction is provided in a portion of one third or less of the entire length from the right end surface on the opposite side. . Piezoelectric ceramic layers 6L that are adjacent to each other via the internal electrodes 5L and 5R, 6
The Rs are polarized in opposite directions, as indicated by the thin arrows in the figure. The internal electrodes 5L and 5R are connected to the external terminals 1L and 2L and 1R and 2R, respectively.

Electrodes 7A and 7B are formed on the lower surface and the upper surface in the thickness direction at the central portion where there is no internal electrode.
The internal piezoelectric ceramic layer 6C sandwiched between 7B is polarized in the direction perpendicular to the electrodes 7A and 7B as indicated by the thick arrow in the figure. This central portion is a high impedance portion 9.

The length of each of the internal electrodes 5L and 5R and the electrodes 7A and 7B is within 1/3 of the length of the piezoelectric transformer in the longitudinal direction (left-right direction on the paper). The external terminals 1L, 2L and 1R, 2R are connected to the low impedance portion 8
The internal electrodes 5L and 5R of L and 8R are connected to each other by one layer. Electrodes 7A, 7 of the high impedance part 9
B is connected to the external terminals 3 and 4.

The piezoelectric ceramic transformer of the present invention has a structure in which piezoelectric ceramic plates polarized in the thickness direction are stacked, and is a novel piezoelectric ceramic transformer that operates in the longitudinal longitudinal third-order mode. As apparent from the vibration velocity distribution and the stress distribution shown in FIG. 1, the piezoelectric transformer according to the present invention operates most efficiently when operated in the lengthwise third-order mode. As is well known, the oscillating stress of the present piezoelectric transformer operating in the transverse effect length longitudinal vibration mode is such that tension or compression force is generated in the longitudinal direction, and they are perpendicular to the laminating direction of the internal electrodes 5L and 5R. That is, since the structurally weakest structure is such that no vibration stress is applied in the stacking direction of the internal electrodes, there is an advantage that sufficient strength can be maintained even during high power operation.

Next, how to take out the external terminal from the electrode will be described. In this piezoelectric transformer that operates in the lengthwise third-order mode, there are three vibration nodes (nodes). The nodes of vibration are located in the center of the low impedance portion 8L, the center of the high impedance portion 9 and the center of the low impedance portion 8R in order from the left side of FIG. Therefore, the external terminals 3 and 4 from the high impedance portion 9 are connected to the electrodes 7A and 7A.
Since B is exposed to the outside, it can be taken out by a method such as normal soldering. On the other hand, the external terminals 1L, 2L (1R, 2R) from the low impedance portion 8L (8R)
Is a structure in which the exposed portions of the internal electrodes 5L (5R) exposed on the side surfaces of the piezoelectric transformer are covered with an insulating layer every other layer and the remaining exposed portions are connected to every other layer by, for example, an electrophoresis method. It can be taken out from the internal electrode. Such a method of taking out the external terminal is a method usually used in a so-called full-surface electrode type laminated ceramic piezoelectric actuator in which the planar shape of the internal electrode is the same as the planar shape of the ceramic layer (piezoelectric ceramic layer), for example. Therefore, the present invention can also be applied. Alternatively, when the internal electrodes 5L and 5R of the low impedance portions 8L and 8R of the piezoelectric transformer of the present invention are recessed from the ceramic layer except for a part of the exposed side surface, a so-called laminated ceramic capacitor type structure is used. The external terminal lead-out structure usually used in this multilayer ceramic capacitor can be applied to the present invention.

Next, a method of driving the piezoelectric transformer will be described. First, a method of driving the low impedance portions 8L and 8R at the left and right ends to output a high voltage from the high impedance portion 9 will be described. When an AC voltage is applied to the low impedance portions 8L and 8R at the left and right ends of FIG. 1, electric energy is converted into mechanical vibration energy via the lateral effect electromechanical coupling coefficient k ₃₁ . At this time, in order to efficiently excite the longitudinal longitudinal third mode, it is important to drive the low impedance portions 8L and 8R at the left and right ends in the same phase. Further, if the electrical connections of the low impedance portions at the left and right ends are parallel, a large current can be applied at a low voltage. Moreover, by applying a technique such as a monolithic ceramic capacitor or a piezoelectric actuator, the internal electrodes can be formed thin and the distance between the electrodes can be reduced, so that so-called low-voltage high-power driving is possible. That is, when a technique such as a monolithic ceramic capacitor is applied to the low impedance portions 8L and 8R of the present multilayer structure, the distance between the electrodes can be easily reduced to 50 μm or less, which is higher than the drive voltage of a known Rosen type piezoelectric transformer. It can be driven with an extremely small voltage.

Furthermore, in the output side high impedance portion 9 of the piezoelectric transformer driven in the lengthwise third order mode,
Vibrations of opposite phases to the low impedance drive units 8L and 8R at the left and right ends are excited, and a high voltage is output from the external terminals 3 and 4 via the coupling coefficient k ₃₁ of the lateral effect vertical vibration.

Needless to say, in order to output a large current with a low voltage from the piezoelectric transformer, it is possible to easily carry out the reverse operation of the above-mentioned driving. That is, by driving the high impedance portion 9 located at the center of the piezoelectric transformer,
By using the low impedance parts 8L and 8R located at both ends as output parts, low voltage and large current can be output.

The lumped constant approximate equivalent circuit in the vicinity of the resonance frequency of this piezoelectric ceramic transformer is similar to that of other piezoelectric transformers, as shown in FIG.
Shown in. In FIG. 2, Cd ₁ and Cd ₂ are braking capacitances on the input side and the output side, respectively. A ₁ and A ₂
Is the input / output force coefficient. m, c, and r _m are the equivalent mass, equivalent compliance, and equivalent mechanical resistance, respectively, for the third longitudinal longitudinal vibration mode. The input and output force coefficients A ₁ and A ₂ of the piezoelectric ceramic transformer of the present invention vary depending on the width, the thickness, the distance between the electrodes of the driving section, and the number of layers of the electrodes. When the driving part has a laminated structure of n layers like the piezoelectric transformer according to the present invention, the force coefficient A ₁ thereof is n times that of a single plate, and the same level of vibration is generated at a low voltage of 1 / n. It can be excited. As is clear from the equivalent circuit of FIG.
Generally, the output power V _out of the piezoelectric transformer changes depending on the resistance value of the connected load, and the larger the load resistance value, the larger the V _out value. Further, the energy transmission efficiency also depends on the load resistance, and the transmission efficiency is not so high except for the load whose value matches the output impedance of the piezoelectric ceramic transformer. In the piezoelectric ceramic transformer of the present invention, in addition to the length, width, and thickness of the entire transformer, there is a degree of freedom in the area of the output electrode or the area of the input electrode, and the range in which the output impedance of the load and the piezoelectric ceramic transformer can be matched. Has a wide range.

As is apparent from FIG. 1, the main piezoelectric ceramic transformer has a four-terminal structure in which the input and output external terminals are galvanically isolated. Therefore, it is possible to increase the degree of freedom of the peripheral circuit as compared with the three-terminal type Rosen type piezoelectric transformer shown in FIG.

As described above, in the piezoelectric ceramic transformer according to the present invention shown in FIG. 1, a high output can be obtained with a low input power, and terminals can be taken out from the electrodes of the vibrating portion by soldering or the like. There are many features such as

Further, as shown in FIG. 3, the output electrodes 37A and 37B are provided on the side surface of the central portion of the piezoelectric transformer so that the output voltage is higher than that of the piezoelectric transformer shown in FIG. This can be dealt with by using a polarized configuration.

According to this structure, as in the piezoelectric transformer shown in FIG. 1, the output voltage is taken out through the lateral effect coupling coefficient k ₃₁ , but the output impedance of the piezoelectric transformer can be set high. It is possible to take out a higher output voltage than the piezoelectric transformer shown in FIG.

In the piezoelectric transformer shown in FIG. 1, if it is desired to increase the output impedance, the plate thickness of the piezoelectric transformer may be increased or the plate width may be decreased.
On the contrary, in the piezoelectric transformer shown in FIG. 2, when the output impedance is increased, the plate thickness is decreased and the plate width is increased.

Further, in the piezoelectric transformer according to the present invention, the low impedance portion on the input side has three layers, five layers, or seven layers.
If odd layers such as layers are used, as shown in FIG. 4 or FIG.
The input side may have the same external electrode structure as the output side, and the external electrode may cover most of the main surface of the input side.
The electrodes 41A, 41B, 42A and 42B in FIG. 4 and the electrodes 51A, 51B, 52A and 52B in FIG. 5 are the input side electrodes of the external electrode structure. In this case, the extraction of the external terminals 1L, 2L and 1R, 2R from the electrodes is
By using this external electrode, it becomes easier compared with the piezoelectric transformer having the configuration shown in FIGS.

[0028]

EXAMPLE As a first example of the piezoelectric ceramic transformer according to the present invention, a piezoelectric ceramic transformer having the structure shown in FIG. 1 was produced by a green sheet method. The material of the piezoelectric ceramic is P
ZT was used (PbZrO ₃ -PbTiO ₃₎ based piezoelectric ceramic. Further, the internal electrodes were formed by screen-printing a Pt paste on a green sheet of a piezoelectric material and integrally firing it together with the piezoelectric material. Although PZT-based piezoelectric ceramics and Pt were used as the materials for the piezoelectric ceramics and the internal electrodes here, it goes without saying that other combinations may be used as long as they are piezoelectric ceramic materials and electrode materials that can be integrally fired with them. Yes.

Each of the low impedance portions 8L and 8R has four active piezoelectric ceramic layers 6L and 6R and an internal electrode 5 respectively.
This is a laminated structure in which L and 5R are alternately laminated in five layers, and further one inactive piezoelectric ceramic layer is provided on each of the upper and lower layers. The thickness of each piezoelectric ceramic layer 6L, 6R was 0.2 mm, and the total thickness was 1.2 mm. After firing, overall length 30 mm, width 7
It was cut to a size of mm.

In the low impedance portions 8L and 8R, glass as an insulator is applied to the exposed side surfaces of the internal electrodes 5L and 5R alternately every other layer by electrophoretic method, and then Ag paste is applied. Further, for the high impedance portion 9, after applying Ag paste on the upper and lower main surfaces,
It was fired to form an external electrode. These external electrodes may be formed by forming a thin film of a conductive material other than Ag using a method other than coating and baking, such as vapor deposition or sputtering.

After that, the low impedance portions 8L and 8R and the high impedance portion 9 were polarized by applying a voltage of 4 kV / mm in insulating oil at 100 ° C. Further, a conductive wire was soldered to each of the external electrodes. At this time, the low impedance parts 8L and 8R are soldered to positions 5 mm inside from both ends of the piezoelectric ceramic transformer, and the high impedance part 9 is the center of the entire piezoelectric transformer so that the connection points with the external electrodes become nodes of vibration. Soldered to the part. Here, in order to increase the boost ratio, 2
Terminals 1L and 2L taken out from two low impedance parts
Although 1R and 2R are connected in parallel, it goes without saying that they function as a transformer even if they are connected in series.

The resonance frequency of the third longitudinal longitudinal vibration mode of this piezoelectric ceramic transformer is 1 from the frequency characteristic of admittance.
It was measured at 48 kHz. When a load resistance of 100 kΩ, which is a relatively low resistance for high voltage applications, is connected to this piezoelectric ceramic transformer, 420 V is input for an input voltage of 10 V.
Was obtained, and the output power at this time was 1.8W.

Although 100 piezoelectric ceramic transformers according to this example were continuously driven for 2000 hours, none of the samples showed peeling of the external electrodes or abnormal characteristics.

As shown in FIG. 4, this piezoelectric ceramic transformer eliminates the upper and lower piezoelectric inactive layers from the low impedance portion, and odd-numbered piezoelectric active layers 5L and 5R, the internal electrodes, and the upper and lower portions of the low impedance portion. External electrode 41A provided on the main surface,
41B, 42A, 42B, and electrical connection can be established from the upper and lower main surfaces to the external terminals 1L, 2L, 1R, 2R. In this case, the external electrodes 41A, 41B, 42A, 42B are formed by arranging the internal electrodes 6L, 6R so as to reach different side surfaces alternately like the monolithic ceramic capacitor, and applying Ag paste on the side surfaces and firing. it can. Therefore, the external terminals 1L, 2L, 1R, 2R can be taken out from the upper and lower main surfaces, so that the degree of freedom in mounting is increased.
In a piezoelectric transformer with three active layers,
When a load resistance of 100 kΩ is connected, input voltage 10
An output voltage of 370 V was obtained with respect to V, and the output power at this time was 1.4 W.

Subsequently, as shown in FIG. 3, a piezoelectric transformer of a second embodiment having a structure in which the high impedance portion was polarized in the width direction was produced. The method of integrally firing the piezoelectric ceramic layer and the internal electrode is the same as in the first embodiment. Here, the overall dimensions are 30 mm in length, 4 mm in width, and 1.2 mm in thickness.
The Ag electrodes were formed on the side surfaces of the low impedance portions 8L and 8R by the electrophoresis method as in the first embodiment. External electrodes 37A and 37B were formed on the high impedance portion 9 by applying Ag paste on the side surface and baking the paste. At this time, the internal electrodes 5L, 8L of the low impedance portions 8L, 8R,
5R and external electrodes 37A and 37B of the high impedance part 9
The distance between and is 2 mm to prevent dielectric breakdown during polarization.
And These external electrodes 37A and 37B are formed by Ag using a method other than coating and baking, such as vapor deposition or sputtering.
It does not matter if a thin film of a conductive material other than the above is formed.

After that, both the low impedance portions 8L and 8R and the high impedance portion 9 were subjected to polarization treatment by applying a voltage of 4 kV / mm in insulating oil at 100 ° C. Further, a conductive wire was soldered to each of the external electrodes. At this time, so that the connection point with the external electrode becomes a node of vibration, the low impedance portions 8L and 8R are soldered to positions 5 mm inside from both ends of the piezoelectric ceramic transformer, and the high impedance portion is centered on the entire piezoelectric transformer. Soldered to. Here, in order to increase the boosting ratio, terminals 1L, 2L and 1 taken out from the two low impedance parts are used.
Although R and 2R are connected in parallel, it goes without saying that even if they are connected in series, they function as a transformer.

The resonance frequency of the third longitudinal longitudinal vibration mode of this piezoelectric ceramic transformer is 1 from the frequency characteristic of admittance.
It was measured at 7 kHz. When a load resistance of 100 kΩ, which is a relatively low resistance for high voltage applications, is connected to this piezoelectric ceramic transformer, an output voltage of 530 V is obtained for an input voltage of 10 V, and the output power at this time is 2.8 W. It was

Although 100 piezoelectric ceramic transformers according to this example were continuously driven for 2000 hours, none of the samples showed peeling of the external electrodes or abnormal characteristics.

As shown in FIG. 5, this piezoelectric ceramic transformer eliminates the upper and lower piezoelectric inactive layers from the low impedance portion, and odd-numbered piezoelectric active layers, internal electrodes, and the upper and lower main surfaces of each low impedance portion. External electrodes 51A, 51B provided on the
With 52A and 52B, it is possible to establish electrical connection from the upper and lower main surfaces to the external terminals 1L, 2L, 1R and 2R. In this case, the external electrodes 51A, 51B, 52A, and 52B can be formed by arranging the internal electrodes 6 so as to reach different side surfaces alternately as in the laminated ceramic condenser, and applying Ag paste to the side surfaces and firing. Therefore, the external terminals 1L, 2L, 1R, 2R can be taken out from the upper and lower main surfaces, so that the degree of freedom in mounting is increased. In a piezoelectric transformer with three layers of active layers actually manufactured, 10
When a load resistance of 0 kΩ was connected, an output voltage of 480 V was obtained for an input voltage of 10 V, and the output power at this time was 2.3 W.

[0040]

As described above, the piezoelectric ceramic transformer according to the present invention can be driven with high power at a low input voltage and can easily take out a high voltage. Moreover, because it matches well with the impedance of the load, it has excellent characteristics,
In addition, it has advantages that conventional piezoelectric transformers do not have, such as high reliability, and has a great industrial value.

[Brief description of drawings]

FIG. 1 is a diagram showing a structure of a piezoelectric ceramic transformer according to a first embodiment of the present invention, a vibration velocity distribution during operation, and a stress distribution.

FIG. 2 is a lumped constant equivalent circuit diagram of the piezoelectric ceramic transformer of the present invention.

FIG. 3 is a diagram showing a structure of a piezoelectric ceramic transformer according to a second embodiment of the present invention, and a vibration velocity distribution and a stress distribution during operation.

FIG. 4 is a perspective view showing the structure of a modification of the first embodiment of the present invention.

FIG. 5 is a perspective view showing the structure of a modification of the second embodiment of the present invention.

FIG. 6 is a perspective view showing a structure of a Rosen type piezoelectric transformer as an example of a conventional piezoelectric ceramic transformer.

[Explanation of symbols]

1L, 1R, 2L, 2R, 3, 4 External terminal 5L, 5R Internal electrode 6L, 6R Piezoelectric ceramic layer 7A, 7B, 37A, 37B Electrode 41A, 41B, 42A, 42B, 51A, 51B, 5
2A, 52B Electrodes 8L, 8R Low impedance part 9 High impedance part 61 Drive part 62 Power generation part 63, 64, 65 Electrode 66, 67, 68 External terminal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Inoue 5-7-1, Shiba, Minato-ku, Tokyo NEC Corporation

Claims (3)

[Claims] 1. A plurality of internal electrodes and piezoelectric ceramic layers are alternately laminated in the plate thickness direction on the maximum one-third or less of the total piezoelectric ceramic transformer length from each of the two end faces in the length direction. The piezoelectric ceramic layers facing each other sandwiching each internal electrode are provided with two low impedance parts having a structure in which they are polarized in opposite directions with respect to the stacking direction axis. A high impedance portion having a structure in which a pair of electrodes facing each other on two surfaces facing each other perpendicular to the axis in the plate thickness direction and a piezoelectric ceramic layer between the pair of electrodes are polarized in the plate thickness direction. Is equipped with a length of 3
A piezoelectric ceramic transformer that operates in the next mode. 2. A plurality of internal electrodes and piezoelectric ceramic layers are alternately laminated in the plate thickness direction on the maximum one-third or less of the total piezoelectric ceramic transformer length from each of the two end faces in the length direction. The piezoelectric ceramic layers facing each other sandwiching each internal electrode are provided with two low impedance parts having a structure in which they are polarized in opposite directions with respect to the stacking direction axis. A high impedance part having a structure in which a pair of electrodes facing each other on two surfaces facing each other perpendicular to the axis in the plate width direction and a piezoelectric ceramic layer between the pair of electrodes are polarized in the plate width direction A piezoelectric ceramic transformer, which is equipped with and operates in a third-longitudinal longitudinal mode. 3. A method for driving a piezoelectric ceramic transformer according to claim 1, wherein the two low impedance parts are input parts and the high impedance part is an output part. An AC input voltage is applied to each of the low-impedance portions so that the internal electrodes forming each of them have the same potential every other layer, and the two low-impedance portions are driven in the same phase and output from the high-impedance portion. A method for driving a piezoelectric ceramic transformer, which is characterized by extracting a voltage.