JPH09205029A - Bolt clamped piezoelectric transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a piezoelectric transformer at high efficiency at a high step-up ratio by a method wherein ceramic is interposed by metal blocks and a resonator clamped by a bolt is connected to a resonator having only a different section so that both resonators are resonated at a specific value. SOLUTION: In piezoelectric ceramic A13, in order to face positive electrodes to each other to form a pair of electric terminals A12 having a heteropolar electrode, one is interposed between the positive electrodes as a terminal of the positive electrode and the other is interposed between a metal cylinder A11 and a negative electrode face as a terminal of the negative electrode. The piezoelectric ceramic A13 are interposed between the metal cylinder A11 and a metal cylinder B14 and clamped by a bolt A15 to structure a resonator A11a. In piezoelectric ceramics B18 having a different outer diameter from the piezoelectric ceramics A13, in order to face positive electrodes to each other to form a pair of electric terminals B17 having a heteropolar electrode, one is interposed between the positive electrodes as a terminal of the positive electrode and the other is interposed between a metal cylinder C16 and a metal cylinder D19 as a terminal of the negative electrode. The piezoelectric ceramics B18 are clamped by a bolt B10 to structure a resonator B11b, which is connected to the resonator A11a. The resonator A11a is connected to the resonator B11b via an axial core and each of them is set so as to resonate at λ/2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flyback transformer used for applying a high voltage to a cathode ray tube of a television, or a transformer used for generating a high voltage for lighting a fluorescent lamp or the like. is there.

[0002]

2. Description of the Related Art Conventionally, a transformer of this type uses a bobbin consisting of a bobbin, an upper and lower collar and a pin terminal, around which a winding is wound and a pair of ferrite cores is arranged. Further, a piezoelectric transformer using a single plate of piezoelectric ceramic is used.

[0003]

The above winding transformer is
Due to the use of magnetic force, the leakage magnetic field may affect other electronic components, and it is necessary to take precautions such as providing a shield if necessary. Also, the secondary side of the winding that generates high voltage is
Insulation measures are required to prevent short circuits. Further, in a conventional piezoelectric transformer using a ceramic single plate, although there is no magnetic field leakage, it is difficult to achieve high power because it causes a ceramic cutting loss and the like.

[0004]

According to the present invention, in order to eliminate these drawbacks, a ceramic is sandwiched between metal blocks made of an Al material having a high Qm to prevent the ceramic from being cut off and an Al material having a high Qm is used. By doing so, the bolt tightening type piezoelectric transformer which has improved input / output efficiency, reduced heat generation, increased step-up ratio and high power at the same time is provided.

According to the present invention, a pair of metal terminals having different poles and a piezoelectric ceramic having the same poles facing each other are sandwiched between a pair of metal cylinders having the same length, and the resonator is fastened with bolts in the axial direction. A, on the other hand, a resonator B having the same structure as that of the resonator A but having a different cross section is formed.
The resonator B is connected to the axis of the above, and the bolted piezoelectric transformer characterized in that the resonator A and the resonator B resonate with λ / 2 is obtained.

According to the present invention, a pair of metal terminals having different polarities and a piezoelectric ceramic having the same poles facing each other are provided.
The resonator a is sandwiched between a pair of metal cylinders having different lengths and fastened with bolts in the axial direction. On the other hand, a pair of metal terminals having different poles and the same pole having a different cross section from the piezoelectric ceramic face each other. The piezoelectric ceramic is sandwiched between the longer metal cylinder and another metal cylinder having a different cross section, and the resonator b is fastened with bolts in the axial direction to form a resonator b. A bolted piezoelectric transformer having a mechanism of resonating twice and expanding the resonance is obtained.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described based on examples with reference to the drawings.

FIG. 1 is a front view showing a bolt tightening type piezoelectric transformer of the present invention, and a diagram showing stress distribution and vibration velocity distribution with respect to the position of the major axis of the bolt tightening type piezoelectric transformer. FIG. 1A is a front view of a bolt tightening type piezoelectric transformer of the present invention. FIG. 1B is a diagram showing a stress distribution. FIG. 1C is a diagram showing a vibration velocity distribution.

As shown in FIG. 1 (a), the bolt tightening type piezoelectric transformer of the first embodiment of the present invention has a pair of piezoelectric ceramics A13 and B18 made of polarized PZT having electrodes on both sides thereof. A metal cylinder A11 and a metal cylinder B14 having the same diameter as the piezoelectric ceramic A, and a metal cylinder C16 and a metal cylinder D19 having the same diameter as the piezoelectric ceramic B.
, Electric terminal A12, electric terminal B17, and bolt A1
5, bolts B10, and nuts (not shown). At this time, each pair of piezoelectric ceramics A1
3 and B18 have almost the same thickness, and the metal cylinder A1
1, B14, C16, D19 have the same length.

The piezoelectric ceramic A13 faces the positive electrode so that the pair of electric terminals A12 have different polarities.
One is a positive electrode terminal and is sandwiched between the positive electrodes, and the other is a negative electrode terminal and is sandwiched between the metal column A11 and the negative electrode surface, and these are sandwiched between the metal column A11 and the metal column B14, and the bolt The resonator is fastened from the outside at A15 to form a resonator A11a.

Here, the resonator A11a resonates by λ / 2. As shown in FIG. 1B, the stress distribution σ is plotted on the vertical axis.
(Kg / mm ² ), where the horizontal axis represents the position of the long axis of the bolted piezoelectric transformer, the central position of the piezoelectric ceramic A has the maximum stress σ ₁ of this λ / 2 resonance in order to maximize efficiency. The position is shown. This time,
σ ₁ = σ ₂ .

Also, the Q of the vibration system of the bolted piezoelectric transformer
From the contents shown in Table 1, the Al material is the best in order to increase the height of the metal cylinder. Therefore, the Al material is used for the metal columns A and B.

[0013]

The piezoelectric ceramic A13 and the piezoelectric ceramic B18 having a different outer diameter are faced to the positive electrode, and one of them is sandwiched between the positive electrodes as a positive electrode terminal so that the pair of electric terminals B17 have different polarities. Is the negative terminal,
It is sandwiched by a metal cylinder C16 and a metal cylinder D19, fastened with a bolt B10, constitutes a resonator B11b, and is connected to the resonator A11a.

Also, like the resonator A11a, a metal cylinder C is used.
16 and the metal cylinder D19 are made of Al material. The center position of the piezoelectric ceramic B18 is the same as that of the resonator B11.
The maximum stress portion σ _{2 of} b [see FIG. 1 (b)] is located.

The resonator A11a and the resonator B11b
And are connected by an axis, and they are set to have λ / 2 resonance.

FIG. 2 (a) is a front view of a step horn-shaped bolting type piezoelectric transformer of the second embodiment.
This type of bolted type piezoelectric transformer shown in FIG. 2 includes a pair of piezoelectric ceramics a3 and b7 and the piezoelectric transformer a.
3, metal cylinders a1 and b4 having the same diameter and different lengths, metal cylinders b4, metal cylinders c6 having different cross sections from the metal cylinders, electric terminals a2, electric terminals b9, and bolts a
5, bolt b8 and nut (not shown). At this time, the thickness of the pair of piezoelectric ceramics a3 and b7 is substantially the same. However, the metal cylinders a1 and b
4 and c6 are different in length.

Similar to the first embodiment, the pair of piezoelectric ceramics a3 are polarized together with the pair of metal terminals, and are sandwiched between the metal cylinders a1 and b4 for resonance. It constitutes the body a11A. Here, the length of the metal cylinder b4 is about twice the length of the metal cylinder a1.
The pair of piezoelectric ceramics b7 are polarized and arranged together with the pair of metal terminals, as in the first embodiment.
The resonator b11B is sandwiched between the metal cylinder b4 and the metal cylinder c6 having different cross-sections to form a resonator b11B. Since the step-horn-shaped bolted piezoelectric transformer consisting of three metal cylinders is slightly different from the bolted piezoelectric transformer composed of four metal cylinders shown in FIG. 1,
The mechanism resonates at λ / 2 and expands this resonance.

Stress distribution σ of this bolt tightening piezoelectric transformer
At (kg / mm ³ ), σ ₁₁ <σ _{22 as shown} in FIG. Also, the vibration velocity distribution v (cm /
In s), v ₃₃ becomes larger than v ₁₁ and v ₂₂ as shown in FIG. That is, the vibration speed at the open end of the metal cylinder c6 is high.

In the case of the bolt tightening type piezoelectric transformer shown in FIG. 1, the resonator A11a side is the primary side and the low voltage 1
The maximum stress σ ₁ generated in the piezoelectric ceramic A13 when driven at the resonance frequency of V is as follows. When σ ₁ = ρ ₁ c ₁ v ₀ ρ ₁ : Al material density, c ₁ : speed, v ₀ : end vibration speed, the end face on the resonator B 11 b side has a similar vibration speed v
₀ , the maximum stress σ ₂ = ρ on the piezoelectric ceramic B18
Generate ₁ c ₁ v ₀ .

The total pressure F1 of the piezoelectric ceramic A13 perpendicular to the axial direction of the resonator A11a is F ₁ = σ ₁ S ₁ when the area S ₁ of the piezoelectric ceramic A is taken. Similarly, the total pressure F ₂ of the piezoelectric ceramic B18 perpendicular to the axial direction of the resonator B11b is F ₂ = σ ₂ S ₂ when the area S ₂ of the piezoelectric ceramic B is taken.

However, if σ ₁ = σ ₂ , S ₁ ≧ S ₂ , and the pressure is increased by the ratio of this total pressure. Further, since the resonance is used, the voltage is boosted by Q times that of the entire vibration system.

Here, when the boost ratio G is obtained, the relationship of equation 1 is obtained. In the case of FIG. 1, σ ₁ = σ ₂ .

[0024]

[Equation 1]

In the case of the bolted piezoelectric transformer shown in FIG.
σ ₂ becomes larger by the expansion ratio of the horn, and the expansion ratio becomes M
Then, since σ ₂ = Mσ ₁ , the equation ₁ becomes the equation ₂ .

[0026]

[Equation 2]

In the bolt tightening type piezoelectric transformer of FIG. 1, the electric terminal A12 of the piezoelectric transformer A13 and the electric terminal B17 of the piezoelectric ceramic B18 are electrically connected to each other as shown in FIG. A circuit was constructed so that the output voltage can be detected when R22 is inserted and a voltage on the output side is applied.

Then, the resonator A11a and the resonator B11b are structured as shown in Table 2.

[0029]

In such a bolt tightening type piezoelectric transformer, when 10 Vpp was inputted to the resonator A side, an output voltage of 200 Vpp was obtained to the resonator B. However, the resistance R
= 0.

Generally, a ceramic single-plate piezoelectric transformer has a limit of input of several watts, but by using a bolt tightening structure, input of several tens of watts is possible, and it can be used in a field that cannot be used in the past. With the advantage that you can.

[0032]

As described above, according to the present invention,
By using an Al material having a high Qm (small vibration loss) and tightening it with bolts, a highly efficient piezo-voltage transformer having a high step-up ratio can be obtained.

[Brief description of drawings]

FIG. 1 is a front view showing a bolt tightening type piezoelectric transformer according to a first embodiment of the present invention, and a diagram showing a stress distribution and a vibration velocity distribution with respect to a position of a long axis of the piezoelectric transformer. FIG.
(A) is a front view. FIG. 1B is a diagram showing a stress distribution. FIG.
(C) is a figure which shows a vibration velocity distribution.

FIG. 2 is a front view showing a step-horn-shaped bolted piezoelectric transformer according to a second embodiment of the present invention, and a diagram showing stress distribution and vibration velocity distribution with respect to the position of the long axis of the piezoelectric transformer. FIG. 2A is a front view. FIG. 2B is a diagram showing a stress distribution. FIG. 2C is a diagram showing a vibration velocity distribution.

FIG. 3 is an explanatory diagram showing an example of an input / output circuit of the piezoelectric transformer according to the first embodiment of the present invention.

[Explanation of symbols]

 1 Metal Cylinder a 2 Electric Terminal a 3 Piezoelectric Ceramic a 4 Metal Cylinder b 5 Bolt a 6 Metal Cylinder c 7 Piezoelectric Ceramic b 8 Bolt b 9 Electric Terminal b 10 Bolt B 11 Metal Cylinder A 11A Resonator a 11B Resonator b 11a Resonator A 11b Resonator B 12 Electric terminal A 13 Piezoelectric ceramic A 14 Metal cylinder B 15 Bolt A 16 Metal cylinder C 17 Electric terminal B 18 Piezoelectric ceramic B 19 Metal cylinder D 22 Resistance R

Claims (2)

[Claims] 1. A resonator A is constructed by sandwiching a pair of metal terminals having different polarities and a piezoelectric ceramic having the same poles facing each other between a pair of metal cylinders having the same length, and fastening them in the axial direction with bolts. On the other hand, a resonator B having the same structure as that of the resonator A but having a different cross-section is formed, and the resonator B is connected to the axis of the resonator A so that the resonator A and the resonator B have λ / A bolt tightening type piezoelectric transformer that has two resonances. 2. A resonator a is constructed by sandwiching a pair of metal terminals having different polarities and a piezoelectric ceramic having the same poles facing each other between a pair of metal cylinders having different lengths, and fastening them in the axial direction with bolts. On the other hand, a pair of metal terminals having different polarities, a piezoelectric ceramic having a cross section different from that of the piezoelectric ceramic, and a piezoelectric ceramic having the same poles facing each other are formed by the longer metal cylinder and another metal cylinder having a different cross section. The resonator b is sandwiched and fastened with bolts in the axial direction, and the resonator a and the resonator b are λ
A bolted type piezoelectric transformer having a mechanism of resonating with / 2 and expanding the resonance.