JPH0864883A - Piezoelectric ceramic transformer - Google Patents

Abstract

PURPOSE: To obtain a piezoelectric ceramic transformer having a large step-up ratio without increasing the L/T of the length L and the thickness T of a piezoelectric element ceramic assembly. CONSTITUTION: The input electrodes 2 and 3 side of the primary side of a piezoelectric ceramic element assembly 1 of a flat rectangular parallelepiped shape are polarized in a thickness T direction, output electrodes 8A and 8B of secondary side are divided into a plurality, and polarized in the length L direction of the reverse direction thereto.

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 using a ceramic (porcelain) that does not require a coil, and more particularly to a piezoelectric ceramic transformer in which an output electrode on the secondary side of a piezoelectric ceramic body is divided into two parts.

[0002]

2. Description of the Related Art Conventionally, piezoelectric ceramic transformers have been widely used as a method for obtaining a high voltage power supply. As shown in FIG. 3, the piezoelectric ceramic transformer has a length of 2 Lmm, a width of Wmm, and a thickness of Tmm.
/ 2 = form the primary side input electrodes 2 and 3 up to the L position,
Similarly, the output electrode 6 is formed on the right side surface (W × T surface), the input side is polarized in the thickness T direction as P ₁ , and the output side is polarized in the length L direction as P ₂ . These electrodes 2 and 3 and 6 are connected to input / output terminals 4 and 5 and 7, respectively,
The output voltage is obtained between the output terminals 7 and 5 by supplying the input voltage between the input terminals 4 and 5.

When the input side to which the input voltage is supplied has a low impedance and the output side from which the output voltage is obtained has a high impedance in the above configuration, a transformation ratio equal to the square root of the impedance ratio can be obtained at the time of resonance.

That is, the transformation ratio (Vout / Vin) is expressed by the following equation (1). Vout / Vin ∝k ₃₁ · k ₃₃ · Q _m · L / T (1) where K ₃₁ : lateral effect coupling coefficient, k ₃₃ : longitudinal effect coupling coefficient, Q _m : machine quality coefficient, L And T are the length and thickness of the piezoelectric ceramic body 1.

[0005]

In the piezoelectric ceramic transformer described in the above-mentioned conventional configuration, k can be obtained by increasing the transformation ratio (or reducing the input voltage) as can be seen from the above equation (1).
_{Since the} coefficients of ₃₁ , k ₃₃ , Q _m, etc. are constant, L / T should be increased. However, to increase L / T, L
Is increased or T is decreased, and if L is increased, the piezoelectric ceramic transformer is naturally increased in size.
If T is made smaller, it naturally becomes thinner, and there is a problem in mechanical strength output.

The present invention has been made in order to solve the above problems, and an object thereof is to obtain a piezoelectric ceramic transformer which can obtain a higher transformation ratio (step-up ratio) with the same shape as the conventional configuration. It is something to try.

[0007]

As shown in FIG. 1, the piezoelectric ceramic transformer of the present invention has a primary side facing the upper and lower main surfaces of a flat rectangular parallelepiped piezoelectric ceramic body 1. Input electrodes 2 and 3 are formed, and the input electrodes 2 and 3 are formed.
In the piezoelectric ceramic transformer in which the secondary side output electrode is formed on the side surface opposite to the side surface on which is formed, the thickness of the primary side input electrodes 2 and 3 formed to face the upper and lower main surfaces 1a and 1b. the opposite output electrodes 8A and 8B of the secondary side that is formed on the side surface 1d along with polarized P ₁ in the direction T by dividing into plural, the longitudinal direction L of the piezoelectric ceramic body 1 of the rectangular
And P ₂ and P ₃ are polarized in opposite directions.

[0008]

According to the present invention, the output electrode on the secondary side of the transformer is divided into, for example, two sections 8A and 8B, and polarizations P ₂ and P are applied in opposite directions.
_By doing so, a piezoelectric ceramic transformer with a high transformation ratio (step-up ratio) can be obtained without increasing L / T.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The piezoelectric ceramic transformer of the present invention will be described below with reference to FIGS. FIG. 1 is an overall perspective view showing an embodiment of the piezoelectric ceramic transformer of the present invention, and FIGS. 2A to 2D are explanations for explaining a forming procedure of an input / output electrode and a polarization procedure of the piezoelectric ceramic transformer of the present invention. It is a figure. The parts corresponding to those of the piezoelectric ceramic transformer described in the conventional configuration are designated by the same reference numerals.

In FIG. 1, the piezoelectric ceramic body 1 has a length of 2 Lm.
m, width Wmm, and thickness Tmm is a flat, substantially rectangular parallelepiped shape. As the material, PZT ceramics having a large mechanical quality factor is selected.

The upper and lower main surfaces (2
(L × W surface) 1a and 1b have a length of 2L, approximately 2L / 2 =
The input electrodes 2 and 3 are formed on the primary side main surface of the piezoelectric ceramic transformer 10 over the entire width up to the L position. Similarly, for example, the left side surface 1c on the side where the input electrodes 2 and 3 are formed on the main surfaces of the left and right side surfaces 1c and 1d of the piezoelectric ceramic body 1.
The output electrodes 8A and 8B on the secondary side of the piezoelectric ceramic transformer 10 are formed on the right side surface 1d on the opposite side. The output electrodes 8A and 8B are not formed uniformly on the entire surface on the right side like the conventional output electrode 6 shown in FIG. 3, but are provided with a gap 9 consisting of a void having a predetermined gap width. The electrodes 8A and 8B are formed so as to be divided into two. These input / output electrodes 2, 3 and 8A and 8B are baked with Ag base or the like.

Further, the primary side is polarized in the thickness T direction like P ₁ , and the secondary side is polarized in the length L direction opposite to each other like P ₂ and P ₃ . These respective electrodes 2 and 3 and 8A and 8
B is connected to input / output terminals 4 and 5 as well as 6 and 7, and output terminals 6 and 7 are connected in series via a load resistor R or the like to supply an input voltage of about AC5V to 12V between input terminals 4 and 5. By doing so, the boosted high voltage is output between the output terminals 6 and 7.

An electrode forming procedure and a polarization procedure of such a piezoelectric ceramic transformer 10 will be described with reference to FIG.

First, as the raw material of the ceramic body 1, PZT ceramics having a high mechanical quality factor Q _m is selected.
This PZT ceramic, for example, has a mechanical ratio of PbZrO ₃ (lead zirconate) added to PbTiO ₃ (lead titanate) to form a solid solution crystal. The maximum value of the coefficient Q _m appears,
It is stable with respect to temperature.

Such PZT is mixed with a predetermined binder (molding aid) and put into a molding die such as a pouring method, an extrusion method, a pressing method, etc., and a flat length 2L = 24 mm, width W = 6 mm,
The piezoelectric ceramic body 1 is obtained by forming and sintering a flat rectangular parallelepiped (plate) having a thickness T = 1.5 mm.

Next, as shown in FIG. 2A, the input electrodes 2 and 3 are formed over the entire width W of approximately 2L / 2 = L in the longitudinal direction 2L of the upper and lower main surfaces 1a and 1b of the piezoelectric ceramic body 1. . This electrode can be used by baking Ag paste. Further, as shown in the figure, an electrode 8A divided into two via a predetermined gap 9 on the left side surface 1d of the piezoelectric ceramic body 1.
And 8B are formed by baking Ag paste.

Next, the piezoelectric ceramic body 1 is separated by 2 in the length direction.
Polarize the next side. That is, the input electrodes 2 and 3 on the primary side
Are connected in common and one end is grounded to obtain the connection state of FIG. 2B. Then, the piezoelectric ceramic body 1 was dipped in a silicon oil bath at 100 ° C., and first divided into two output electrodes 8
A direct current plus 30 KV is applied to A for 1 hour to polarize the piezoelectric ceramic body 1 in the length direction L as indicated by P ₃ . Similarly, the other output electrode 8B has a DC of -30 KV.
Is applied for 1 hour to polarize in the length direction L in the P ₂ direction opposite to P ₃ . The polarization voltage in this case is 25 KV / c
m.

Of course, as described above, one output electrode 8A is connected to a DC plus 30 KV power source without being separately polarized,
A DC minus 30 KV power source may be connected to the other output electrode 8B, the primary side electrodes 2 and 3 may be commonly connected and grounded, and at the same time polarized in the opposite direction to the length direction L.

Further, contrary to the above, if DC minus 30 KV is applied to the output electrode 8A side and DC plus 30 KV is applied to the output electrode 8B side, the directions are opposite to the polarization P ₃ and P ₂ directions of FIG. 2C. It is clear that a polarized piezoceramic element 1 is obtained.

Next, as shown in FIG. 2C, a DC voltage of 3.75 KV is applied between the input electrodes 2 and 3 on the primary side of the piezoelectric ceramic body 1. That is, the input electrode 3 side is grounded and the other input electrode 2 has a thickness of 1.5 mm and DC 3.75 KV,
By applying (25 KV / cm) in silicon oil at 100 ° C. for 1 hour, P is applied in the thickness T direction of the piezoelectric ceramic body 1.
Polarization is performed in ₁ of the way.

As shown in FIG. 2D, the electrodes 2 and 3 and the electrodes 8A and 8B, which have been formed and polarized as described above, have a number 1 as shown in FIG.
By connecting the lead wires 11 and 12 on the secondary and secondary sides and supplying the primary voltage of AC to the input terminals 4 and 5, the load resistor R connected between the output terminals 6 and 7 is boosted to a secondary voltage. High voltage is obtained.

That is, in the present example, the length 2L of the piezoelectric ceramic element 1 is 2L × 2 = 4L as compared with the conventional one, so that it is approximately 4 as compared with the piezoelectric ceramic element body 1 having the same conventional length.
A double boosting ratio will be obtained.

The flat rectangular parallelepiped of the piezoelectric ceramic body 1 described above has a length L = 24 mm, a width W = 6 mm, and a thickness T = 1.
In the conventional piezoelectric ceramic transformer of the structure shown in FIG. 3 in which the output electrode on the secondary side is not divided into two, the primary voltage is A
The secondary voltage when applying C5V-12V is AC500V
~ AC1200V, the secondary voltage of this example is A
The value was about four times as large as C1900 to AC2200V.

In the above embodiment, the secondary side output electrode is divided into two, but it is possible to obtain a higher number by dividing the output electrode into n.
It is clear that a piezoelectric ceramic transformer having an n-fold boost ratio can be obtained.

[0025]

According to the piezoelectric ceramic transformer of the present invention, the same shape dimension as the conventional piezoelectric ceramic transformer, that is, L
A secondary voltage having a step-up ratio of about 4 times is obtained while having / T, and it is not necessary to increase the length L or the thickness T of the piezoelectric ceramic element, thereby lowering the mechanical strength. It is possible to obtain a piezoelectric ceramic transformer having a high output voltage without using it.

[Brief description of drawings]

FIG. 1 is a perspective view of a piezoelectric ceramic transformer showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing electrodes and polarization procedures of the piezoelectric ceramic transformer of the present invention.

FIG. 3 is a principle explanatory diagram of a conventional piezoelectric ceramic transformer.

[Explanation of symbols]

1 Piezoelectric ceramic element 2, 3 Input electrode 8A, 8B Output electrode P ₁ , P ₂ , P ₃ Polarization direction

Claims (1)

[Claims] 1. A primary side input electrode is formed so as to face upper and lower main surfaces of a flat rectangular parallelepiped piezoelectric ceramic body, and a secondary side is provided on a side surface opposite to a side surface on which the input electrode is formed. In a piezoelectric ceramic transformer having an output electrode formed thereon, the primary side input electrode formed opposite to the upper and lower main surfaces is polarized in the thickness direction, and the secondary side output electrode formed on the opposite side surface is divided into a plurality of parts. A piezoelectric ceramic transformer, wherein the rectangular parallelepiped piezoelectric ceramic body is polarized in mutually opposite directions in a longitudinal direction.