JPS63272084A - Piezoelectric transformer - Google Patents

Abstract

PURPOSE:To obtain a piezoelectric transformer capable of raising two input voltages of different frequencies by making a generation part composed of a pair of output parts which are formed at prescribed intervals. CONSTITUTION:This transformer is composed of a plate-shaped driving part piezoelectric element 18, which is polarized in the direction of its thickness and has electrodes 20 and 22 on both its ends, and generation part piezoelectric elements 14, 16 which are fixed on respective sides facing each other perpendicularly to these electrodes planes of the driving part piezoelectric element 18 and are polarized perpendicularly to these fixture planes. Said respective generation part piezoelectric elements 14 and 16 in such a piezoelectric transformer 10 are composed of two pairs of output parts 41, 43 and 45, 47 which are respectively formed via prescribed gaps 40. Accordingly, oscillation appears in an in-phase mode, in which the output parts with the gaps 40 on both their sides are oscillated with similar phases, and in a negative mode, in which they are oscillated with phases shifted in 180 degrees from each other. Two desired input voltages of different frequencies can be hence raised by setting a gap width W1 in an appropriate value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a piezoelectric transformer that performs a voltage transformation action using piezoelectric phenomena.

[Conventional technology]

In the cathode ray tube of a CRT display, a high voltage of approximately 30°C must be applied to the anode in order to accelerate the electrons in the electron beam emitted from the electron gun and cause them to collide with the phosphor screen at high speed. The power supply that obtains this high voltage is called a flyback transformer, and uses the pulse voltage of the horizontal deflection output circuit that scans the electron beam as a drive signal, and guides this pulse voltage to the primary side of the flyback transformer to boost the voltage. ,
Obtaining high voltage. The pulse voltage of the horizontal deflection output circuit has a generation period that varies depending on the number of scanning lines of the electron beam that scans the fluorescent screen of the cathode ray tube. 24 on display
．． It has a frequency of 83kHz. Therefore, the flyback transformer can be used by simply boosting the pulse voltage of the horizontal deflection output circuit depending on the application. A piezoelectric transformer using a piezoelectric element such as a piezoelectric ceramic is used because it has the advantage of having a small amount of noise.

In the piezoelectric transformer, the drive section has a first electrode polarized in the thickness direction.
a second piezoelectric element, the power generation part of which is fixed to the side surface of the first piezoelectric element, and whose polarization direction is orthogonal to the fixed surface; and an electrode provided on the tip surface of the second piezoelectric element. When performing a boosting action, an input voltage is applied between both electrodes of the first piezoelectric element, and strong mechanical vibration is generated in the second piezoelectric element due to the electrostrictive effect.
A high voltage is obtained from the electrodes of the piezoelectric element.

[Problem that the invention seeks to solve]

However, in order to generate strong mechanical vibrations in the second piezoelectric element, which is the power generation part of the piezoelectric transformer, it is necessary to input a frequency equal to the natural vibration frequency determined by the length of the entire transformer in the polarization direction of the second piezoelectric element. A voltage must be applied to the drive unit, for this reason piezoelectric transformers used in conventional CRT displays, for example 15.75kHz
z or 24.83 kHz pulse voltage, and was suitable for 15.75 kHz single frequency or 24.83 kHz single frequency. but,
In order to use a CRT display efficiently, it must be connected to a signal source with a different horizontal deflection frequency, such as a personal computer that produces a signal with a horizontal deflection frequency of 15.75 kHz, and a signal source with a horizontal deflection frequency of 24.83 kHz. A dual scan CRT display that can also be connected to a birth computer is required. Therefore, the flyback transformer used in dual scan displays must be able to step up pulse voltages at two different frequencies. It was not possible to support scan displays, and a piezoelectric flyback transformer that could handle this was desired.

The present invention has been made in view of the above-mentioned request, and an object of the present invention is to provide a piezoelectric transformer capable of boosting two types of input voltages having different frequencies.

[Means for solving problems]

In order to achieve the above object, the present invention includes a plate-shaped drive piezoelectric element that is polarized in the thickness direction and has electrodes on both sides, and a plate-shaped drive piezoelectric element that is polarized in the thickness direction and has electrodes on both sides. In a piezoelectric transformer having power generating part piezoelectric elements fixed to each of the side surfaces and having a polarization direction perpendicular to the fixed face, each of the power generating part piezoelectric elements consists of a pair of output parts formed with a predetermined gap between them. This is a piezoelectric transformer with the following characteristics.

(Function) In the present invention configured as described above, the power generation section is configured with a pair of output sections separated by a predetermined gap, so that when mechanical vibration is caused in the length direction of the power generation section, the gap is increased. The resonance frequencies of the output parts of the power generating parts that are separated and facing each other are caused by an in-phase mode vibration mode having the same period and phase and an anti-phase mode vibration mode having a 180 degree difference in phase with each other. By setting the gap width to an appropriate value, it is possible to step up two desired types of input voltages with different frequencies, and it is possible to obtain a piezoelectric flyback transformer that is compatible with dual scan displays.

〔Example〕

Preferred embodiments of the piezoelectric transformer according to the present invention will be described in detail with reference to the accompanying drawings.

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

In FIG. 1, the piezoelectric transformer 10 has a drive section 12 at its center, and power generation sections 14.1 at both sides of the drive section 12.
It is 6. The drive unit 12 corresponds to the primary side of a wire-wound transformer, and has electrodes 20 on both sides of a plate-shaped drive unit piezoelectric element 18.
22 is provided. Drive part piezoelectric element 1
8 is made of piezoelectric ceramic or the like, and is polarized in the thickness direction as shown by arrow 24. Electrode 20.2
2 is formed by vapor deposition or the like on the surface in the thickness direction of the driving part piezoelectric element 18, and input terminals 26 and 28 are connected to each of them. Further, an output electrode 30 is connected to one electrode 22, and is used for extracting an output voltage together with an output electrode of a power generation section to be described later.

The power generation parts 14 and 16 correspond to the secondary side of the wire-wound transformer and have the same shape, and each of the power generation part piezoelectric elements 32 and 34 has a pair of opposing electrodes perpendicular to the electrode surface of the drive part piezoelectric element 18. fixed to the side. Each power generation section piezoelectric element 32.
34, the polarization direction is perpendicular to the fixed surface as shown by the arrow 36, and the central part in the width direction (vertical direction in FIG. 1) is cut out in a rectangular shape from the tip toward the drive part 12, and the width W.I.

A gap 40 is formed with a length. That is, each of the power generation part piezoelectric elements 32 and 34 has a shape in which a pair of output parts are arranged with a gap 40 in between, and the four output parts 4
1, 43, 45, 47 are formed, and the piezoelectric transformer 10
The overall shape is approximately H-shaped. And each output section 4
1, 43, 45, and 47 are provided with electrodes 42, respectively.
, 44, 46° 48 are formed by vapor deposition etc.
Output terminals 50.52, 54.56 are connected to each of these electrodes.

The operation of the embodiment configured as described above is as follows.

An input voltage having the same frequency as the natural frequency determined by the length dimension of the piezoelectric transformer 10 in the length direction (horizontal direction in FIG. 1) is applied to the electrodes 20. of the drive section 12 via the input terminals 26.28. When applied between 22 and 22, mechanical vibration occurs in the length direction due to the electrostrictive effect, and this mechanical vibration generates charges due to the piezoelectric effect in the piezoelectric elements 32 and 34 of the power generation section, and the voltage between the output terminals 30 and 50 is Between 30.52 and output terminal 3
0.54 and a high voltage can be obtained between the output terminals 30 and 56. That is, by applying an input voltage to the input terminals 26 and 28, electrical energy is transformed into mechanical energy, and this mechanical energy is further converted into electrical energy and boosted.

When the gap 40 is not provided in the power generation section 14, 16, the natural vibration frequency f of the piezoelectric transformer 10 can be determined by the following equation.

f (kHz) L Here, ■ is the propagation speed of sound in the piezoelectric element (m/S), and L is the length of the piezoelectric transformer 10 (■). Follow,
When piezoelectric ceramic is used as the piezoelectric element, the sound propagation velocity V is approximately 4000 m/s, and the length is 10 cm.
Then, the natural vibration frequency f will be approximately 20 kHz.

However, as in this embodiment, there is a gap 4 in the power generation section 14,16.
0, as the length LI of the gap 40 increases, there will be an in-phase mode in which the output parts on both sides of the gap 400 vibrate with the same phase, and an in-phase mode in which the output parts on both sides of the gap 40 vibrate with a phase shift of 180 degrees from each other. A vibration mode of anti-phase mode appears. Therefore, by making the length of the gap 40 appropriate, the piezoelectric transformer 10 can be operated at 15.75kHz and 24kHz.
It can have two natural vibration frequencies of 83kHz and can support dual scan displays.

FIG. 2 shows the ratio 1 of the gap length in the piezoelectric transformer 10 having the shape shown in FIG. 1 to the length L of the piezoelectric transformer 10.
．． ．． /1. This figure shows the relationship between this and the natural vibration frequency. The solid line represents the total width W w 5 cta, the gap width W, -
This is the case of i-kaku. As the gap width Wl increases, the natural vibration frequency changes as shown by the dashed line and the broken line. Therefore, having two desired natural vibration frequencies,
The value of /L is determined by the relationship with the gap width W,
For example, the number of combinations of /L and W to obtain natural vibration frequencies of 15.75 kHz and 24.83 kHz is not limited to one.

In addition, in the case of the embodiment shown in FIG.
, 43, 45.47 output terminals 50, 52.54.56
may be combined in parallel and used as one output section, or each output section may be used as a separate output section.Furthermore, the electrodes 42, By changing the area of 44°46.48, it is possible to mutually change the magnitude of the output voltage of each output section. In the above embodiment, the case where the gap 40 is formed in a rectangular shape has been explained, but it may be formed into a V-shaped gap, or the power generation section may be provided on the four sides of the drive section piezoelectric element 18. good. Furthermore, in the embodiment described above, a case has been described in which the power generation sections 14 and 16 are formed in a concave shape, but each output section may be formed by a separate piezoelectric element.

〔Effect of the invention〕

As explained above, according to the present invention, by forming a gap along the length direction in the power generating section and providing a pair of output sections, it is possible to generate the vibration modes of the in-phase mode and the anti-phase mode. It is possible to boost two types of input voltages with different frequencies.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of a piezoelectric transformer according to the present invention, and FIG. 2 is a diagram showing the relationship between the ratio of the gap length to the total length of the gap formed in the power generation section and the natural vibration frequency. 10... Piezoelectric transformer, 12... Drive unit, 14.1
6... Power generation section, 18... Drive section piezoelectric element, 20, 2
2゜42.44, 46.48... Electrode, 32.34.
...Power generation part piezoelectric element, 40...Gap, 41, 43, 4
5゜47...Output section. Agent Patent Attorney Tomo Murakami - Part 1 Figure 10, Piezoelectric transformer 12: 1 section movement included p 14.16: Power generation department + 8: 12 + shift number μm piezoelectric leaf 32.34: Power generation department/f: Electric power generation section 1 gap 9f, 2 fig.

Claims (1)

[Claims] A plate-shaped drive piezoelectric element that has been polarized in the thickness direction and has electrodes on both sides, and is fixed to each of the opposing side surfaces perpendicular to the electrode surface of this drive piezoelectric element, and the polarization direction is the fixed surface. 1. A piezoelectric transformer having a power generation section piezoelectric element orthogonal to the power generation section piezoelectric element, wherein each of the power generation section piezoelectric elements is comprised of a pair of output sections formed with a predetermined gap in between.