BACKGROUND OF THE INVENTION
The present invention relates to a sound-eliminating board capable of thoroughly capturing noises and internally repeatedly reflecting sound waves penetrated thereinto to finally eliminate the sound waves through energy dispersion, overlapped amplitude, and counterbalanced energy of the sound waves. Any low-frequency sound waves are also absorbed in an elastic and porous layer of the sound-eliminating board.
Noises do harm to a person's eardrum and have negative influences on the mental and physical conditions of a person who works or lives in a noisy environment for a prolonged time. Unfortunately, there are so many noise sources in our living environment, such as stereophonic equipment, traffic equipment, machinery in plants, construction sites, etc., that many people are constantly and seriously harmed by noises.
- SUMMARY OF THE INVENTION
There are many commercially available products designed to protect people against noises, such as noise barrier shields erected at two sides of overhead roads to isolate noises by forcing noise waves to reflect from the barrier shields, and sound-eliminating boards made of soft fibrous material for use indoors. It is known that when a sound wave meets some barrier, a part of the sound wave penetrates through the barrier while others reflect or diffract. Factors that determine a penetrating power of a sound wave include physical properties of the barrier and a frequency of the sound wave. Given the physical properties of a barrier are fixed, the lower the frequency of a sound wave is, the higher the penetrating power of the sound wave is. Generally, a soft sound-absorbing material is not able to completely absorb sound waves. And, the rigid noise barrier shield does not absorb sound waves but reflects and diffracts them, and part of the reflected and diffracted sound waves propagate at a height over the barrier.
A primary object of the present invention is to provide a sound-eliminating board that is able to treat sound waves of different frequencies and can therefore be used indoors and outdoors to thoroughly absorb sound waves and achieve the purpose of eliminating sound.
BRIEF DESCRIPTION OF THE DRAWINGS
To achieve the above and other objects, the sound-eliminating board of the present invention mainly includes a sound transmissible top layer, a rigid sound-eliminating middle layer, and an elastic sound-eliminating bottom layer being sequentially bonded into an integral unit. The sound transmissible top layer allows sound waves to penetrate into the rigid sound-eliminating middle layer, which includes a plurality of checkered partitions to define a plurality of open-topped small compartments. Sound waves penetrated into the rigid sound-eliminating middle layer reflect repeatedly in the small compartments to result in energy dispersion and counterbalanced energy due to overlapped amplitude of the reflected sound waves, and are finally eliminated. In case of any residual low-frequency sound waves that penetrate through the rigid sound-eliminating middle layer into the elastic sound-eliminating bottom layer, they are further absorbed in the bottom layer.
The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein
FIG. 1 is a perspective of a sound-eliminating board according to the present invention;
FIG. 2 is an exploded perspective of the sound-eliminating board of FIG. 1;
FIG. 3 is a sectional view of the sound-eliminating board of FIG. 1;
FIG. 4 is an enlarged view of the encircled area of FIG. 3; and
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 5 is a perspective of a sound-eliminating board according to another embodiment of the present invention.
Please refer to FIGS. 1, 2 and 3 in which a sound-eliminating board 10 according to the present invention is shown. The sound-eliminating board 10 mainly includes a sound transmissible top layer 11, a rigid sound-eliminating middle layer 12, and an elastic sound-eliminating bottom layer 13. These three layers 11, 12, 13 are sequentially bonded together to form an integral unit.
The sound transmissible top layer 11 is a decorative layer permitting sound waves to pass through it into the rigid sound-eliminating middle layer 12. When the sound-eliminating board 10 is used outdoors, the top layer 11 may be made of a rigid material and provided with densely distributed tiny holes 17. And, when the sound-eliminating board 10 is used indoors, the top layer 11 may be made of the above-described rigid material with a plurality of tiny holes 17 or a gas-permeable soft material, such as non-woven fabrics (not shown).
The rigid sound-eliminating middle layer 12 includes a plurality of checkered partitions 14 that together define a plurality of small and open-topped sound-eliminating compartments 15 on the middle layer 12. When a sound wave enters the sound-eliminating middle layer 12, it reflects many times in the sound-eliminating compartments 15, resulting in energy dispersion of the penetrated sound. Moreover, reflected sound waves in the sound-eliminating middle layer 12 create an effect of overlapped amplitude of sound wave, resulting in counterbalanced sound energy. That is, the sound is eliminated. The sound-eliminating compartments 15 may be designed to have a depth within a range from 1 to 5 cm. When the sound-eliminating compartments 15 have an increased depth, they are more effective in eliminating a sound of high decibel. And, sound-eliminating compartments 15 having reduced depth are more effective in eliminating a sound of low decibel. The sound-eliminating compartments 15 on the rigid sound-eliminating middle layer 12 may have a uniform depth or have different depths in randomly assigned areas, depending on actual condition of sounds in a place where sounds are to be eliminated.
The elastic sound-eliminating bottom layer 13 is made of an elastic material having densely distributed pores 16 therein. When sound waves propagate among the pores 16, sound energy of these sound waves is absorbed in the elastic sound-eliminating bottom layer 13. Sound waves that penetrate the elastic sound-eliminating bottom layer 13 are low-frequency sound waves capable of penetrating through the rigid sound-eliminating middle layer 12. When the low-frequency sound waves penetrate into the elastic sound-eliminating bottom layer 13, they collide with one another in the pores 16 repeatedly to result in changed frequency of sound waves and weakened sound energy. The elastic sound-eliminating bottom layer 13 finally absorbs residual sound waves and eliminates sound. An example of forming the sound-eliminating bottom layer 13 is to compress and thereby mold rubber granules, and pores 16 naturally form among the compressed and molded granulated rubber.
The sound-eliminating board of the present invention is characterized in the rigid sound-eliminating middle layer 12, in which sound waves reflect repeatedly to result in overlapped amplitude of sound waves and counterbalanced sound energy to effectively eliminate the sound.
In another embodiment of the present invention, it is possible to produce a sound-eliminating board 10′ that includes only the sound transmissible top layer 11 and the rigid sound-eliminating layer 12, as shown in FIG. 5, for use at a location where no low-frequency sound wave exists.
With the above-described structure, the rigid middle layer 12 and the elastic bottom layer 13 of the sound-eliminating board of the present invention are able to eliminate high-frequency and low-frequency sound waves, respectively, making the present invention an excellent sound absorption material.