JPH06236189A - Sound wave canceller - Google Patents

Abstract

PURPOSE:To effectively interrupt an occurring sound wave without narrowing a space interrupting the sound wave. CONSTITUTION:Electrodes 2 are formed, and plural piezoelectric sheets 1 with a strip of fancy paper (for writing a tanka on) shape are linked like a blind by a supporting string 4. A voltage by which the sound wave with a phase opposite to the sound wave to be canceled out is generated by respective piezoelectic sheets 1 is applied between the electrodes 2 of respective piezoelectric sheets 1 by a power source 5 through an electrode wiring 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for shutting off a sound source generated from an audio device, an electric motor or the like to preserve the environment.

[0002]

2. Description of the Related Art In order to block a sound source emitted from a device such as an audio device or an electric motor, a method of partitioning a space with a wall, a shielding plate or a shielding curtain is generally used in order to block a sound wave propagating in air.

Further, a method of canceling a sound wave generated from an acoustic device, an electric motor or the like by newly generating a sound wave having a phase opposite to that of the generated sound wave is adopted.

[0004]

The first method is based on the fact that sound waves are absorbed or reflected by walls, shield plates and curtains, but it is not sufficient in terms of efficiency. In addition, the second method has a high sound wave blocking efficiency, but requires a speaker that emits sound with an opposite phase according to the sound source to be canceled out.To cancel the generated sound source, coil driving is generally used. This can be done by vibrating the diaphragm, but the diaphragm and coil (speaker system) having a large volume are placed in the space to be cut off, so that the space becomes narrow.

An object of the present invention is to provide a sound wave canceller which efficiently cuts off the generated sound wave without narrowing the space where the sound wave is cut off.

[0006]

A sound wave canceller of the present invention has a plurality of strip-shaped piezoelectric sheets in which electrodes are formed and are connected in a blind manner, and each piezoelectric sheet has a phase opposite to that of a sound wave to be canceled. It has an electrode wiring and a power supply for applying a voltage for generating a sound wave between the electrodes of each piezoelectric sheet.

In another acoustic wave canceller of the present invention, a plurality of piezoelectric sheets having electrodes formed on the surface of the wall material in a tile shape, and each of the piezoelectric sheets generate an acoustic wave having a phase opposite to that of the acoustic wave to be canceled. It has an electrode wiring and a power supply for applying a voltage to be generated between the electrodes of each piezoelectric sheet.

[0008]

There is a flat panel speaker using a piezoelectric sheet as a speaker having a small volume, which can generate a sound wave having an opposite phase to the generated sound wave in a wide frequency range. When a voltage is applied to this speaker, the material is deformed by stress, and the speaker vibrates and makes a sound with the deformation. Such a material is a material called a piezoelectric material, and PZT (lead titanium zirconate) powder material can be given as a representative example. The piezoelectric sheet as the base material is obtained by mixing the powder material with plastic (polyvinylidene fluoride) and molding the mixture into a sheet by a roll molding method. An electrode is formed on the obtained sheet, a polarization process called poling is performed, and a voltage corresponding to audio information is applied between the film electrodes to generate an audio.

The generated sound wave can be canceled by applying a voltage between the electrodes of the piezoelectric sheet under the condition of generating the opposite phase of the sound wave to be canceled (generated sound wave). A sheet is cut into tile shapes, and the tiles are stacked on the surface of the wall material like a stack, and electrodes are wired to the tile-shaped flat speaker that has been applied, and when a voltage is applied, it becomes an active speaker that does not take up space. In addition, a piezoelectric sheet is cut into strips, electrodes are formed, the sheets with electrodes are bundled in a blind manner, and a voltage that generates a sound wave having a phase opposite to that of the sound wave passing between the bundled strips is piezoelectric. By applying between the electrodes of the sheet, it is possible to prevent the sound wave from propagating to the space behind the blind.

[0010]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a perspective view of a sound wave canceller according to a first embodiment of the present invention.

In the sound wave canceller of this embodiment, a plurality of piezoelectric sheets 1 in which electrodes 2 are formed and are connected in a blind manner by a support string 4 and these piezoelectric sheets 1 generate a sound wave having a phase opposite to that of a sound wave to be canceled. It is composed of a voltage wiring 3 and a power source 5 for applying a generated voltage between the electrodes 2 of each piezoelectric sheet 1.

Next, a method of manufacturing the sound wave canceller of this embodiment will be described.

Lead titanium zirconate (90 parts by weight) and vinylidene fluoride (10 parts by weight) were kneaded in a ball mill,
A sheet having a thickness of 150 μm and a size of 30 × 30 cm is prepared using a roll extruder. A copper foil having a thickness of 100 μm is glued on both sides of the sheet to form an electrode 2. With a direct current electric field of 150 V applied between the electrodes 2, a poling treatment is performed in a thermostatic chamber at 150 ° C. for 5 hours. The treated sheet 1 is cut into a width of 5 cm, and is arranged at an angle of 45 ° with respect to the horizontal as shown in FIG. The electrode wiring 3 is formed so as to be bundled with the support string 4. The piezoelectric sheets 1 having a length of 2.3 m and a width of 30 cm manufactured in this manner were arranged in five rows and installed at the entrance of a space partitioned on three sides by walls. The sound recorded on the CD was reproduced by the speaker in the partitioned space. During reproduction, the voltage modulated to 2 KHz was continuously applied from the power source 5 to each piezoelectric sheet 1 of the blind. Comparing the maximum of the amplitude intensity of the voice before and after passing the blind, the intensity outside the blind was about 5% with respect to the intensity in the space.

The sound wave canceller according to the second embodiment of the present invention is obtained by laminating a piezoelectric sheet on a wooden board in a tile shape.

Next, a method of manufacturing the sound wave canceller of this embodiment will be described.

As in the first embodiment, the width is 5 cm and the length is 3
A piezoelectric sheet of 0 cm is prepared. A wooden board with a thickness of 1 cm (with a door that allows entry and exit) will be installed at the entrance of the space that is divided on three sides by walls. The piezoelectric sheet prepared previously is bonded to the surface of the wooden board with an adhesive. Electrode wiring is formed on both front and back surfaces of the piezoelectric sheet. Insert the electrode wiring between the piezoelectric sheets. And like the first embodiment,
The sound recorded on the CD was reproduced by a speaker, and a voltage modulated at 2 KHz was continuously applied to the piezoelectric sheet during reproduction.
The space being played and outside the space (near the entrance board)
Then, when the amplitude intensity of the voice was compared, the intensity outside the board was 0.5% of the intensity within the space.

[0018]

As described above, according to the present invention, the piezoelectric sheets are arranged in a blind shape or attached to the wall material, and each piezoelectric sheet generates a sound wave having a phase opposite to that of the sound wave to be canceled. Is applied between the electrodes of each piezoelectric sheet, which has the effect of blocking the sound generated from the acoustic device or the like and preventing the sound wave from propagating after the blind or the wall material.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a sound wave canceller according to a first embodiment of the present invention.

[Explanation of symbols]

 1 Piezoelectric sheet 2 Electrode 3 Electrode wiring 4 Support string 5 Power supply

Claims (2)

[Claims] 1. A plurality of strip-shaped piezoelectric sheets in which electrodes are formed and connected in a blind-like manner, and a voltage at which each piezoelectric sheet generates a sound wave having a phase opposite to that of a sound wave to be canceled out. A sound wave canceller having an electrode wiring and a power supply applied between electrodes of a sheet. 2. A plurality of piezoelectric sheets having electrodes formed on a surface of a wall material in a tile shape, and each of the piezoelectric sheets,
A sound wave canceller having an electrode wiring and a power supply for applying a voltage that generates a sound wave having a phase opposite to that of a sound wave to be canceled out, between the electrodes of each piezoelectric sheet.