JP3088499B2 - Piezoelectric transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric transformer utilizing mechanical vibration of a piezoelectric vibrator for obtaining a DC high-voltage power supply used for an electronic copying machine, an electrostatic air cleaner or the like. The present invention relates to a piezoelectric transformer whose reliability is improved by extracting an output terminal from a node of vibration.

[0002]

2. Description of the Related Art FIG. 5 is a perspective view schematically showing the structure of a conventional piezoelectric transformer. In FIG. 5, an input electrode 2 and an earth electrode 3 which are opposed to each other in the thickness direction are formed at approximately half the length in the piezoelectric ceramic rectangular plate 1, and a portion where the input electrode 2 and the earth electrode 3 are formed is formed. An output electrode 4 is formed on the opposite end face. In the conventional piezoelectric transformer shown in FIG. 5, the portion of the input electrode 2 and the ground electrode 3 is polarized in the thickness direction, and the portion between the output electrode 4 and the input electrode 2 and the ground electrode 3 is a piezoelectric ceramic rectangular. The plate 1 is polarized in the longitudinal direction. 6A and 6B are explanatory views of the operation principle of a conventional piezoelectric transformer. FIG. 6A is a cross-sectional view of a piezoelectric ceramic rectangular plate, and FIG. FIG. 6C shows a displacement distribution in the case of vibrating in the resonance mode, and FIG. 6C shows a strain distribution at that time. In FIG. 6A,
When a voltage having a frequency equal to the resonance frequency of the one-wavelength resonance mode of the longitudinal vibration of the piezoelectric ceramic rectangular plate is applied to the input electrode 2 by using the ground electrode 3 as a ground terminal, the rectangular plate becomes as shown in FIGS. Vibrates as shown in FIG. At this time, a voltage is generated between the ground electrode 3 and the output electrode 4 by a piezoelectric effect. Here, the input voltage applied to the input electrode 2 and the output voltage generated at the output electrode 4 will be described.
The distance between the input electrode 2 and the ground electrode 3 is sufficiently smaller than the distance between the ground electrode 3 and the output electrode 4, and the area of the input electrode 2 and the ground electrode 3 is sufficiently larger than the area of the output electrode 4. The capacitance on the output side is a sufficiently large value compared to the capacitance on the output side. Therefore, when an AC voltage is applied to the input side to excite the vibrator, the voltage generated between the ground electrode and the output electrode is changed to a vibration generated at the output side by the AC voltage applied to the input side to the output side. When a voltage is applied, a voltage substantially equal to the voltage required to generate vibration of the same magnitude is generated at the output electrode. In the conventional piezoelectric transformer shown in FIGS. 5 and 6, in order to support the vibrator so as not to affect the vibration, it is necessary to support the vibrator at the node of the vibration shown in FIG. On the other hand, as described above, since the output terminal needs to be taken out from the end face having the largest vibration amplitude, deterioration and reliability of the characteristics such as changes in the vibrator characteristics due to the weight of the lead wire and disconnection of the lead wire take-out portion due to vibration are caused. There is a drawback that causes deterioration of the performance, especially using a material that has little effect on vibration, such as conductive rubber, in the output terminal take-out portion,
Special structural measures such as the need to form an electrode having high adhesion to the piezoelectric ceramics as the end face electrode were required.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned problems of the conventional piezoelectric transformer and to provide a highly reliable piezoelectric transformer with a simple structure. The purpose is.

[0004]

According to the present invention, there is provided a piezoelectric transformer which is substantially equal to one-third of the length of the piezoelectric ceramic rectangular plate from one end face of the piezoelectric ceramic rectangular plate shown in FIG.
An input electrode and a ground electrode which are opposed to each other in the thickness direction are formed on almost the entire area of the rectangular plate, and opposed to the two-thirds and five-sixths of the length of the rectangular plate from the same end face in the thickness direction. After forming a polarization electrode and an output electrode to be electrically connected between the polarization electrode and the output electrode, the input electrode and the ground electrode are polarized in the thickness direction,
A portion between the input electrode, the ground electrode, and the polarization electrode, and a portion between the polarization electrode and the output electrode are polarized in directions shown in opposite directions in the length direction of the rectangular plate to form the input electrode and the ground electrode. The one-sixth of the length of the rectangular plate and the portion of the output electrode are connected by soldering or the like with metal wires arranged in a direction perpendicular to the length direction of the rectangular plate of the piezoelectric ceramics from the set end face. Then, the piezoelectric transformer is obtained by supporting the piezoelectric ceramic rectangular plate so as to sandwich the metal wire with the metal wire.

That is, according to the present invention, an input electrode opposed in the thickness direction is formed on substantially one-third of the length of the piezoelectric ceramic rectangular plate from one end face of the piezoelectric ceramic rectangular plate. Polarized electrodes are formed at two-thirds of the length of the rectangular plate from the end face, and output electrodes are formed in strips at five-sixths of the rectangular plates so as to oppose each other in the thickness direction. After the electrical connection, the input electrode and the ground electrode are polarized in the thickness direction, and a rectangular plate is formed between the input electrode, the ground electrode and the polarization electrode, and between the polarization electrode and the output electrode. In the length direction of the piezoelectric ceramic rectangular plate, the polarization is applied in the opposite directions to each other, and one sixth of the length of the rectangular plate from the end face of the input electrode and the output electrode portion. At right angles, the piezoelectric ceramic rectangle Of a metal wire connected by soldering or the like from both sides to form the electrodes, and a piezoelectric transformer which is characterized by being configured to support so as to sandwich the piezoelectric ceramic rectangular plate with the metal wire.

[0006]

An input electrode surface and a ground electrode surface are formed on substantially the entire surface of both sides of one third of the length of the piezoelectric ceramic rectangular plate from one end of the piezoelectric ceramic rectangular plate. Band-shaped polarization electrodes are formed on both sides of the ceramic rectangular plate at two-thirds positions, and band-shaped output electrodes are formed on both surfaces of the ceramic rectangular plate at five-sixth positions.
Polarization in the direction of the input electrode surface and the ground electrode surface, polarization between the input electrode and the ground electrode and between the polarized electrode and the polarized electrode direction from the polarized electrode direction to the input electrode direction, and polarization processing from the polarized electrode direction to the output electrode direction are performed. As a result, the directions of polarization on both sides of the polarization electrode are reversed, and the characteristics of strain during vibration are reversed, so that the voltage generated at this portion is added to become a large output voltage. Also, since the metal wire from the output electrode is taken out from the position of the node of the vibration, the metal wire does not shake greatly when the piezoelectric ceramic rectangular plate vibrates. Transformer reliability is greatly improved.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A piezoelectric transformer according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective view schematically showing the structure of a piezoelectric transformer according to the present invention. The piezoelectric transformer has a thickness substantially equal to one-third of the length of the piezoelectric ceramic rectangular plate from one end face thereof. The input electrode 12 and the ground electrode 13 which face each other in the vertical direction are formed, and two-thirds of the length of the rectangular plate and five-sixths from the same end face.
, The polarization electrodes 14a facing each other in the thickness direction,
Polarizing electrode 14b, output electrode 15a, output power 15
b is formed. Polarized electrode 14a, polarized electrode 14b
After electrically connecting between the output electrode 15a and the output electrode 15b, the input electrode 12 and the ground electrode 13 are polarized in the thickness direction, and the input electrode 12, the ground electrode 13, and the polarization electrode 14a are polarized. , The portion of the polarizing electrode 14b and the portion between the polarizing electrode 14a and the polarizing electrode 14b and the portion between the output electrode 15a and the output electrode 15b are mutually separated in the length direction of the rectangular plate in the directions of arrows A, B and C. Polarized in the opposite direction. FIG. 2 is a circuit connection diagram showing an example of a method of performing the above-described polarization using one DC high-voltage power supply. A voltage corresponding to the distance between the electrodes is necessary to sufficiently saturate the polarization. Voltage is applied to each terminal by using a resistor so as to obtain an appropriate electric field strength. FIG. 3 is an explanatory view of the operation principle of the piezoelectric transformer according to the present invention, and FIG.
FIG. 3B is a cross-sectional view of a piezoelectric ceramic rectangular plate, and FIG. 3B is a displacement distribution when the piezoelectric ceramic rectangular plate vibrates in a three-wavelength resonance mode of longitudinal vibration, and FIG. ) Shows the strain distribution at that time. In FIG.
When a voltage having a frequency equal to the resonance frequency of the three-half wavelength resonance mode of the longitudinal vibration of the piezoelectric ceramic rectangular plate is applied to the input electrode 12 with the ground electrode 13 serving as a ground terminal, the piezoelectric ceramic rectangular plate becomes as shown in FIG. b) and vibrates as shown in FIG. At this time, the ground electrode 13 is used as a ground terminal, and a high output voltage is generated at the output electrode 15a and the output electrode 15b according to the same principle as that described with reference to FIG. In FIG. 3, the polarization electrode 14a and the polarization electrode 14b are electrodes used for polarization, and when used as a piezoelectric transformer, they become floating electrodes after polarization, and thus may be removed.

[0008] As shown in FIG.
a, the polarization directions on both sides of the polarization electrode 14b are opposite, but as shown in FIG. 3C, the polarity of the strain is opposite to that of the portion where the polarization direction is opposite. Therefore, the voltages generated in this portion are added to each other to become an output voltage. Further, in the piezoelectric transformer of the present invention, as shown in FIG. 3B, the output terminal is taken out from the position of the node of the vibration, so that not only does not affect the vibration characteristics of the piezoelectric transformer, but also the terminal connection is made. Since the part does not vibrate, the terminal does not come off and the reliability is greatly improved.

FIG. 4 is a perspective view showing a method of supporting and fixing the piezoelectric transformer according to the present invention, in which one-sixth the length of the rectangular plate from the end faces of the input electrode 12 and the ground electrode 13 and the output. The electrode 15a and the output electrode 15b are connected to the metal wire 16 and the input electrode 12, the metal wire 17 and the ground electrode 13, the metal wire 18 and the output electrode 15a arranged in the direction perpendicular to the length direction of the piezoelectric ceramic rectangular plate. , The metal wire 19 and the output electrode 15b are connected by soldering. Both ends of each metal wire are fixed to holders 20 and 21 made of highly insulating plastic, respectively, and are supported so that the piezoelectric ceramic rectangular plate is sandwiched between these metal wires. Using a strip-shaped metal as the metal wire,
In addition, when a material having a spring property such as phosphor bronze is used, the stability of the support of the vibrator and the influence on the vibrator characteristics are further improved.

[0010]

As described above, the piezoelectric transformer according to the present invention has a simple structure in which the input / output terminals can be obtained from the positions of the nodes of vibration, and the positions of the nodes of vibration are sandwiched between metal wires. It is possible to obtain a highly reliable piezoelectric transformer having a high output voltage, and the effect is extremely large in practical use.

[Brief description of the drawings]

FIG. 1 is an external perspective view schematically showing the structure of a piezoelectric transformer according to the present invention.

FIG. 2 is a diagram illustrating a method of polarizing a vibrator of a piezoelectric transformer according to the present invention;
FIG. 4 is a circuit diagram showing an example.

3A and 3B are front views illustrating the operation of the piezoelectric transformer according to the present invention. FIG. 3A is a side sectional view, FIG. 3B is a diagram showing a displacement distribution, and FIG. Distribution map.

FIG. 4 is an external perspective view showing the support and fixing of the piezoelectric transformer of the present invention.

FIG. 5 is a perspective view schematically showing a conventional piezoelectric transformer and its structure.

6A and 6B are diagrams for explaining the operation of the conventional piezoelectric transformer, wherein FIG. 6A is a side sectional view, FIG. 6B is a displacement distribution diagram,
FIG. 6C is a strain distribution diagram.

[Explanation of symbols]

 1,11 Piezoelectric ceramic rectangular plate 2,12 Input electrode 3,13 Ground electrode 4 End face electrode (output electrode) 14a, 14b Polarization electrode 15a, 15b Output electrode 16,17,18,19 Metal wire 20,21 Holder 22 Lead wire A, B, C Polarization direction

Claims (1)

(57) [Claims] 1. An input electrode facing in the thickness direction is formed on substantially one-third of the length of the piezoelectric ceramic rectangular plate from one end surface of the piezoelectric ceramic rectangular plate. Polarized electrodes are formed at two-thirds of the length of the plate, and output electrodes are formed at five-sixths of the plate in a strip shape facing each other in the thickness direction. After the connection, the input electrode and the earth electrode are polarized in the thickness direction, and the rectangular plate is inserted between the input electrode, the earth electrode and the polarization electrode, and between the polarization electrode and the output electrode. In the direction perpendicular to the length direction of the piezoelectric ceramic rectangular plate, a polarization is applied in the direction opposite to the longitudinal direction of the piezoelectric ceramic rectangular plate from the end face of the input electrode to one sixth of the length of the rectangular plate and the output electrode. Shape on both sides of the piezoelectric ceramic rectangular plate A piezoelectric transformer, wherein a metal wire is connected to the formed electrode by soldering or the like, and the metal wire is supported so as to sandwich the piezoelectric ceramic rectangular plate.