JPS60187799A - Piezoelectric fan - Google Patents

Abstract

PURPOSE:To permit to reduce noise without reducing the flow amount of air of the fan by a method wherein a reinforcing plate is provided on the extension of a vibration plate to provide the vibration plate with an inertia mass, reduce the resonance frequency of the plate and increase the amplitude of the plate. CONSTITUTION:When A.C. signal is impressed inbetween a lead wire 5 and supporting plates 3, 4, an piezoelectric element 1 is polarized into the direction shown by the notations 1b and bending vibration is caused in the piezoelectric element 1. In case the A.C. signal is set properly, a composite body of the extension 2a of vibration plate 2 and the reinforcing plate 2b therefor is vibrated forcibly and a large amplitude is obtained whereby the flow of air is excited. In this piezoelectric fan, the vibration of high-frequency is reduced by the reinforcing plate 2b and noise is reduced. The reinforcing plate 2b, provided on the extension 2a of the vibration plate 2, effects as the inertia mass, therefore, sound pressure is reduced due to the reduction of resonance frequency and the noise of the fan may be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a piezoelectric fan, and more particularly to a piezoelectric fan used for cold months 1 of electronic equipment and for introducing air or other gases into mold.

[Prior art]

Recently, piezoelectric fans have come to be used in place of electric nine-rotation fans for air ventilators of electronic devices and the like.

As shown in FIGS. 1 and 2, the piezoelectric fan has electrodes 1a on both sides, and a diaphragm 2 between a pair of piezoelectric elements 1, the tip of which extends from one end of the piezoelectric elements 1. The piezoelectric element 1 is sandwiched so as to protrude, and the other end of the piezoelectric element 1 is held by a support plate 3.4.By applying an AC signal between the electrodes 4@la, the diaphragm 2 vibrates. ,
It's starting to feel like a lull. ) - Since the extension part 2a is formed by protruding the diaphragm from one end of the vibration plate element 1, the air blowing capacity is enhanced.

In the conventional piezoelectric fan described above, the diaphragm 2 operates with not only vibrations at its fundamental frequency but also vibrations at a considerably high frequency, resulting in a noise problem. Even more +! In order to increase i1m, if the thickness of the diaphragm 2 is increased, the resonant frequency of the diaphragm increases and the sound pressure also increases. This will reduce noise. Normally, the operating frequency of a piezoelectric fan is in the range from several +1-12 to several hundred) 4Z, and in this range C, the frequency is low and the audible sensitivity of humans is high, so the I'' of the diaphragm 2 is It is not preferable to thicken the thickness and increase IIIfFl.

[Purpose of the invention]

The present defense solves the above-mentioned drawbacks by providing a piezoelectric fan that avoids reducing high-frequency vibrations even though it generates a relatively large amount of ff1l.

1. That is, according to the present invention, a pair of plate-shaped piezoelectric elements having electrodes on both sides, a diaphragm sandwiched between these piezoelectric elements, and a holding layer at one end of the pair of plate-shaped piezoelectric elements are provided. The diaphragm is provided so as to extend outward from the holding device and the other end of the pair of plate-shaped piezoelectric elements, and an alternating current signal is applied to the extension part and the electrodes of the pair of plate-shaped piezoelectric elements. In a piezoelectric fan that includes a drive device that vibrates these piezoelectric elements,
A piezoelectric fan C is provided in which an inertial mass is provided in the above-mentioned extension portion.

Specifically, for example, the above-mentioned ill property tJ1 can be obtained by increasing the thickness of a portion of the extension portion. In this way, by giving the 11th quality II to the 4th part of the imaging plate, the resonant frequency can be lowered, but -(the amplitude increases, so the noise can be reduced without significantly decreasing the Ill ffi itself. can be done.

〔Example〕

The invention will be explained in more detail below in the form of an example and with reference to FIGS. 3 to 11. FIG.

First of all, referring to FIGS. 3 to 5, the first embodiment of the present invention will be described.
Z T ) Both sides of the piezoelectric element (made of porcelain) are printed with A! 1. A cross-shaped electric conductor made of conductive metal such as Ni or 1st class 4! ! ! 1 A has 6 colors and C.

A fan member is constructed by combining the piezoelectric elements 1 described above as a pair, with the diaphragm 2 sandwiched between them, and joining them together using an adhesive. The diaphragm 2 protrudes from one end of the pair of piezoelectric elements 1, and has an extension 2a formed therein. This extension 2
A reinforcing plate 2]) is attached to the tip of a on both sides with adhesive.The material of the reinforcing plate 2b is Kovar, A1Cl.
In addition to the 3rd grade metal shrine 11, polyethylene terephthalate 1
It may also be made of resin such as ・.

The fan member has a 63.degree.
Hold it between the metal support plates 3.4 and tighten it with the screws 6 (
Fixed to Kusuf. The support plates 3 and 4 also serve as terminals, and are electrically connected to the outer electrodes 1a+, 1a+ of each piezoelectric element 1. Roughly speaking, the imaging plate 2 is electrically connected to the inner electrode 1a of each piezoelectric element 1, and has a lead wire 5 at the rear end of the diaphragm 2, that is, at the end opposite to the extension part 2a. It is joined with solder etc.

These support plates 3.4 and lead wires 5 are connected to a drive device (U shown in the figure).
electrically connected to

The operation of the first embodiment having the above configuration will be explained. When an alternating current signal is applied between the lead ms and the support plate 3.4 from the drive device, the +i-electron 1 is polarized in the direction of the protrusion 11), causing the piezoelectric element 1 to bend and vibrate. By setting the alternating current signal appropriately, the structure consisting of the extension 2a of the diaphragm 2 and its reinforcing plate 2b vibrates strongly, and a large amplitude 1q is obtained. Due to this impulse, a flow of air is excited.

FIG. 6 shows the relationship between the vibration frequency and noise of the piezoelectric fan. The thick line (B) shows the characteristics of the piezoelectric fan of this example, and the thin line C (Δ) shows the characteristics of the conventional piezoelectric fan. 1" - When playing an electric fan, there is a song that makes noise due to vibrations at the fundamental frequency, and the noise due to high frequency vibrations is noticeable.
t, T In the piezoelectric fan of the present invention, the reinforcement 2b reduces the vibration of the field frequency and reduces the noise. Also, diaphragm 2
Since the reinforcing plate 2b is provided on the extension part 2a of T, this serves as an inertial mass, which lowers the resonance frequency and lowers the frequency. This lowered resonant frequency is in a lower range of human auditory sensitivity, and the sound pressure is also lowered, so it is possible to reduce the noise.

Although the frequency decreases by installing the reinforcing plate 21), the amplitude increases and the air volume increases. It won't drop significantly.

Experiment The inventors conducted the following experiment to evaluate the piezoelectric fan of the present invention.

The piezoelectric fan shown in FIG. 5 is formed into a groove, that is, the total length is 27.
Between the PZT soup making electronic elements 1 with a length of 5 mm, a width of 22111 m, and a plate thickness of 0.2 mm, a total length of 55.0 mm, a width of 221 T1 m,
A Kovar diaphragm 2 with a plate thickness of 0.1 mm is held so that the piezoelectric element 1 protrudes by 522.5 mm to form an extension 2a, and a length of 12 mI is attached to the tip of the extension 2a! 1. Reinforcement plate 21 made of polyethylene teleftaku 1~ with a width of 22 mm
) was constructed by gluing them together.

Using the above configuration, changes in the noise and riuti of the piezoelectric fan were examined by changing the thickness of the reinforcing plate 2b. The results are shown in FIGS. 7 and 8.

J3, the noise is measured at a location iQcm in front of the piezoelectric fan.

FIG. 7 shows the relationship between the thickness of the reinforcing plate 2b and noise, and FIG. 8 shows the relationship between the thickness of the reinforcing plate 2b and the air volume (v1).

From FIG. 7, the noise is reduced by reinforcing plate 21). The temperature decreases as jf < l! l! iffed.

As you cross the reinforcing plate 2 o'clock by 11 times, I! i, lji is i1
(It's down, but it's not a significant 11 (down), it's a slight drop.

FIGS. 7 and 8 show that the optimal mounting position of the reinforcing plate 2b is to attach it to the tip of the extension 2a of the diaphragm, but it is also effective to install the extension 2a at a position of 1N. There is.

FIG. 9 shows a second embodiment of the present invention.
In the embodiment, the diaphragm 2 and the diaphragm extension 2a are:
Although it is assumed to be an integral part, in this embodiment, it is made as a separate part, and the extension part 2a is fitted into the tip of the element 1 with a pressure 1. The material of this extension part 2a is preferably metal, resin, etc.

FIG. 10 shows a third embodiment of the woodworking rim, so the diaphragm 2 and the diaphragm extension 2a are integrally made of resin, and the diaphragm 2
sandwiched between the electric board ICs, and inserted between the piezoelectric elements lυ
This is a J: sea urchin that passes through this electrode plate IC and the electrode 1a.

FIG. 11 shows a fourth embodiment of the present invention, in which the diaphragm 2 and the diaphragm extension 2a are integrated, and the reinforcing plate 2b provided with the extension 2a is also integrally bound. It is a ζ thing. A diaphragm having such a structure can be manufactured by molding, cutting, etc.

Although the present invention has been described in the form of embodiments, the present invention is not limited to the above-mentioned embodiments, and can be modified in various ways within the scope of the claims.

〔Effect of the invention〕

Conventional piezoelectric fans generate unpleasant high-frequency noise, but the configuration of the present invention eliminates most of the high-frequency noise, thereby providing an almost silent piezoelectric fan with an FFL amount. becomes possible.

[Brief explanation of the drawing]

FIG. 1 shows a perspective view of a conventional piezoelectric device. FIG. 2 is a top view of the piezoelectric fan of FIG. 1; FIG. 3 is a perspective view of a piezoelectric fan according to a first embodiment of the present invention. Figure f34 shows the side view at 1]] of Figure 3. Figure 5 (; 1, Incorporating the piezoelectric noise shown in Figure 3/Ll 1
Figure 1 shows a top view of the air fan assembly. FIG. 6 is a graph showing 1411 of the J1 electric fan. 7 and 8 are diagrams of the piezoelectric fan of FIG. An example is shown in a top view. IMI. 1...Piezoelectric element, la, lc...electrode, 2...diaphragm, 2a...vibration base 1!74!(,2b...
Reinforcement plate, 3.4... Support, 5... Riet wire, 6.
...screw, 7...case. Dai Jjp person Asahi 41 Ko 1 figure 2 figure 3 flash cylinder a number IHz) Heron 9 figure Otouma 10 figure

Claims (1)

[Scope of Claims] (1) A pair of plate-shaped piezoelectric elements (1) provided with electrodes (1a) on both sides, and a diaphragm (1) sandwiched between the pair of plate-shaped piezoelectric elements (1). 2), a holding device (3, 4) that holds the pair of plate-shaped piezoelectric elements (1) at one end thereof, and a holding device (3, 4) that holds the pair of plate-shaped piezoelectric elements (1) at one end; The extension part (2a) of the diaphragm (2) and the pair of plate-shaped piezoelectric elements (1)
), an AC signal is applied to the electrode (1a) of the piezoelectric element (1
), the piezoelectric fan is characterized in that the extension portion (2a) is provided with an inertial mass m (2ti>). In the piezoelectric fan described above, the inertial property (2b) is characterized in that the thickness of a part of the extension (2a) of the diaphragm (2) is increased. (3) Claims In the piezoelectric fan according to item 2, the diaphragm (2) and the diaphragm extension (2a)
A piezoelectric fan, characterized in that the diaphragm extension portion (2a) is a separate piece, and the diaphragm extension portion (2a) is fitted to the tips of the pair of piezoelectric elements (1). (4) In the piezoelectric fan according to any one of claims 2 or 3, a reinforcing plate (2b) is bonded to the tip of the diaphragm extension (2a) to increase the thickness. A piezoelectric fan characterized by increasing. (5) The piezoelectric fan according to claim 4, wherein the diaphragm (2) is a synthetic resin plate, and electrodes are provided on both sides of the synthetic resin plate. . (6) In the piezoelectric fan according to claims 4 and 5, the reinforcing plate (2b) and the diaphragm extension part (2a) are integrally molded. fan.