JPH0733279Y2 - Silencer - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silencer for silencing unwanted sounds such as noise.

[0002]

2. Description of the Related Art The sound environment is one of the most important factors in pursuing a comfortable living space.

Above all, the emphasis is placed on noise countermeasures. In a house, a sound absorbing material such as foamed plastic is sandwiched between walls to reduce the sound reflected by the walls and to mitigate unnecessary sounds. That is usually done.

[0004]

However, in the above-mentioned conventional structure, it is necessary to make the sound absorbing material considerably thick in order to enhance the sound absorbing property in the wall, and if this is done, the wall is actually too thick, On the contrary, there is a problem that the room becomes small.

Therefore, in order to solve this problem, FIG.
A muffling device as shown in FIG.

That is, in this silencer, a sound wave 26 such as noise from the outside is received by the speaker 21, the received vibration is detected by a detector 23 such as an acceleration sensor or a displacement sensor, and based on this detection signal. , The transmission circuit 22 has a sound wave 27 having the same frequency as the sound wave 26 but the opposite phase.
An electric signal is transmitted to the speaker 22 for transmission so that the sound wave 26 is canceled from the sound wave 26 by causing the sound wave 26 and the sound wave 27 to interfere with each other.

However, the above-described structure of the silencer requires the transmission circuit 24 and the power supply circuit 25 for driving the transmission circuit 24, which causes a new problem that the device becomes large-scale.

[0008]

SUMMARY OF THE INVENTION In order to solve the above problems, a silencer of the present invention has a first piezoelectric element for generating an electric signal by sound waves such as noise, and a first piezoelectric element for generating the electric signal. A second piezoelectric element that is driven by the generated electric signal to generate a sound wave having a phase opposite to that of the sound wave so as to cancel the sound wave; and the first and second piezoelectric elements. Is formed on one piezoelectric film.

[0009]

According to the above construction, the first piezoelectric element for generating an electric signal by a sound wave such as noise, and the first piezoelectric element driven by the electric signal generated by the first piezoelectric element to cancel the sound wave. A second piezoelectric element that generates a sound wave having a phase opposite to that of the sound wave is provided close to the first piezoelectric element
Since the above piezoelectric element is formed on one piezoelectric film, the sound wave such as noise is canceled by the sound wave generated by the second piezoelectric element.

Further, since the second piezoelectric element is driven by the electric signal generated in the first piezoelectric element by a sound wave such as noise, an external power source is unnecessary. Moreover, the first and second
Since the piezoelectric element can be handled as a single piezoelectric film, it is convenient in the manufacturing process, and the silencer can be manufactured more efficiently.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 1, the muffler of this embodiment has a structure in which a piezoelectric film 3 having first and second piezoelectric elements 1 and 2 is sandwiched between a front panel 6 and a back panel 7. ing.

When the front panel 6 and the back panel 7 are fitted to each other, a cylindrical hole portion 10 opening to the front panel 6 side is formed, and the piezoelectric element 1 has a shallow hole portion 10. The piezoelectric element 2 is installed in a place deep in the hole 10.

A material having electrical conductivity is used on at least the surfaces of the front panel 6 and the back panel 7 which are in contact with the piezoelectric film 3 to electrically connect the piezoelectric elements 1 and 2. Specifically, for example, a metal material is used for the front panel 6 and the back panel 7. In this case, the insulating layer 8 is provided on the front side of the front panel 6 so as to prevent electrical leakage.

The piezoelectric elements 1 and 2 are one piezoelectric film 3
A disk-shaped electrode 4 formed on the upper and lower surfaces of the piezoelectric film 3 and having a diameter larger than the diameter of the hole 10.
・ 5 is formed so as to face each other and is polarized. Further, the electrodes 4 are electrically connected to the front panel 6, and the electrodes 5 are electrically connected to the back panel 7. Therefore, the piezoelectric element 1
4 and the electrode 4 of the piezoelectric element 2 are electrically connected by the front panel 6, and the electrode 5 of the piezoelectric element 1 and the electrode 5 of the piezoelectric element 2 are electrically connected by the back panel 7. .

The polarization directions of the piezoelectric elements 1 and 2 are opposite to each other, as indicated by the dotted arrows in the figure, and are substantially perpendicular to the surface of the front panel 6. .

In the above structure, the outside (upward direction in the drawing)
Sound waves such as noise propagating from the piezoelectric element 1 reach the piezoelectric element 1 provided in the shallow portion of the hole 10 slightly faster than the piezoelectric element 2 provided in the deep portion of the hole 10. Therefore, the piezoelectric element 1 is excited by the sound wave earlier than the piezoelectric element 2 in time, and an electric signal is generated. Then, the output voltage of the piezoelectric element 1 is applied to the piezoelectric element 2 through the front panel 6 and the back panel 7. At this time, the vibration direction of the piezoelectric element 2 and the vibration direction of the piezoelectric element 2 have opposite phases,
The piezoelectric element 1 and the piezoelectric element 2 are the front panel 6 and the back panel 7.
Since the piezoelectric element 2 is connected by the piezoelectric element 1, the output voltage of the piezoelectric element 1 causes the piezoelectric element 2 to emit a sound wave having the same frequency as the external sound wave but having a phase opposite to that of the external sound wave, thereby canceling the external sound wave. .

Next, a method of manufacturing the above-mentioned muffler will be described with reference to FIGS. 2 to 4.

As shown in FIG. 2, metal vapor deposition or metal paste coating or the like is applied to the upper and lower surfaces of the piezoelectric film 3 made of a composite piezoelectric material obtained by kneading piezoelectric particles such as polymer piezoelectric material or piezoelectric ceramics in resin. By doing so, the disk-shaped electrodes 4 and 5 facing each other with the piezoelectric film 3 interposed therebetween are formed at a predetermined interval.

Next, as shown in FIG. 3, adjacent electrodes 4
By applying a DC high voltage with different polarities (indicated by +-in the figure) between electrodes 5, electrodes 4 and 5
The electric dipole in the piezoelectric film 3 between the predetermined direction (in the figure,
(Indicated by an arrow) to form piezoelectric elements 1 and 2 polarized in opposite directions.

Then, as shown in FIG. 4, by sandwiching the piezoelectric film 3 on which the piezoelectric elements 1 and 2 are formed between the front panel 6 and the back panel 7, and pressing from above and below,
The silencer (FIG. 1) is manufactured. The front panel 6 and the back panel 7 are formed with a cylindrical hole 10 that opens toward the front panel 6 in the fitted state, and the piezoelectric element 1 is installed in a shallow place of the hole 10. The piezoelectric element 2 is preformed so as to be installed deep inside the hole 10.

A metal material, for example, is used for the front panel 6 and the back panel 7. In this case, an insulating layer 8 is provided on the front side of the front panel 6 so as to prevent electrical leakage.

As the insulating layer 8, an insulating plate may be adhered to the front side of the front panel 6 or used, or an insulating material may be coated on the front side of the front panel 6.

Further, resin molded products may be used for the front panel 6 and the back panel 7, and in this case, the front panel 6 and the piezoelectric film 3 are connected to each other to electrically connect the piezoelectric elements 1 and 2. A metal foil, a metal-deposited resin film, or the like may be inserted between the piezoelectric film 3 and the back panel 7.

As described above, the muffling device of this embodiment has two
It has a very simple structure using two piezoelectric elements 1 and 2, and can easily muffle external noise without supplying electric power. Moreover, since the thickness of the piezoelectric elements 1 and 2 is 1 mm or less, the present silencer is extremely thin. Furthermore, in this embodiment, since the two piezoelectric elements 1 and 2 are formed on the single piezoelectric film 3, the piezoelectric elements 1 and 2 are compared with the case where the piezoelectric elements 1 and 2 are handled separately in the manufacturing process.
・ 2 is easy to handle, and the silencer can be manufactured efficiently.

In the above embodiment, one piezoelectric film 3 is used.
Although the case where the two piezoelectric elements 1 and 2 are formed in the above is described, the present invention is also applicable to a muffling device in which a large number of piezoelectric elements 1 and 2 groups are formed in one piezoelectric film 3. in this case,
The sound deadening effect can be further improved, and moreover, a large number of piezoelectric elements 1 and 2 groups can be easily handled as a single piezoelectric film 3. Can be manufactured efficiently.

The above-mentioned muffling device can be used not only as a muffler for indoor use but also for muffling outdoors, such as application to noise barriers on expressways.

[0028]

As described above, the silencer of the present invention is driven by the first piezoelectric element that generates an electric signal by sound waves such as noise, and the electric signal generated by the first piezoelectric element. A second piezoelectric element that generates a sound wave having a phase opposite to that of the sound wave so as to cancel the sound wave is provided close to the first piezoelectric element, and the first and second piezoelectric elements are provided on one piezoelectric film. Since it is formed, the sound wave such as noise is canceled by the sound wave generated by the second piezoelectric element. Further, since the second piezoelectric element is driven by the electric signal generated in the first piezoelectric element by the sound wave such as noise,
No external power supply required. Moreover, since the first and second piezoelectric elements can be handled as a single piezoelectric film, it is convenient in the manufacturing process, and the silencer can be manufactured more efficiently.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention and is a schematic configuration diagram of a silencer.

2 shows a method for manufacturing the silencer of FIG. 1,
It is sectional drawing which shows the process of forming an electrode on the upper and lower surfaces of a piezoelectric film.

3 is a cross-sectional view showing a process of forming a piezoelectric element by applying a direct current high voltage between electrodes formed on the piezoelectric film of FIG. 2 to perform polarization processing.

FIG. 4 is a cross-sectional view showing a process of manufacturing the silencer of FIG. 1 by sandwiching the piezoelectric film having the piezoelectric element of FIG. 3 sandwiched between a front panel and a back panel.

FIG. 5 is a schematic configuration diagram showing a possible configuration of the silencer.

[Explanation of symbols]

 1 Piezoelectric element (first piezoelectric element) 2 Piezoelectric element (second piezoelectric element) 3 Piezoelectric film 6 Front panel 7 Back panel

Claims (1)

[Scope of utility model registration request] 1. A first piezoelectric element that generates an electric signal by a sound wave such as noise, and an opposite phase to the sound wave so that the sound wave is canceled by being driven by the electric signal generated by the first piezoelectric element. And a second piezoelectric element that generates a sound wave of (1) are provided in close proximity to each other, and the first and second piezoelectric elements are formed on a single piezoelectric film.