Body-felt sound unit and vibration transmitting method therefor

A body-felt sound unit having a vibration transmitting member imbedded in a human body support member, for example, a chair, a bed, etc., and an electro-mechanical vibration transducer attached to the vibration transmitting member, the transducer generating mechanical vibration on receipt of a low-frequency current, thereby transmitting the vibration to the human body. The vibration transmitting member comprises a flat plate- or net-shaped member of a relatively large area, and the electro-mechanical vibration transducer is attached to the vibration transmitting member such that the direction of vibration generated from the transducer coincides with the direction of the width of the vibration transmitting member so as to transmit transverse vibration to the vibration transmitting member. Even if the vibration transmitting member is thin, the apparent rigidity becomes high, so that the transmission of vibration is made effectively.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a body-felt vibration unit wherein a sound 
signal from a sound device is converted into vibration through an 
electro-mechanical vibration transducer to vibrate a vibration 
transmitting member installed on a thing for the human body to be placed 
on (hereinafter referred to as "human body support member"), for example, 
a chair, a bed, etc., thereby giving the user a bodily sensation of 
vibration. The present invention also relates to a method of transmitting 
the vibration in the above-described body-felt sound unit. 
2. Prior Art 
The present inventors have been conducting studies, for a long time, of 
body-felt sound unit that converts a sound signal received from a sound 
device or the like into mechanical vibration and allows the user to 
receive this vibration by his/her body, together with sound from a speaker 
or a head receiver, and we have already obtained many patent rights and 
utility model rights (for example, see Japanese Patent Publication Nos. 
58-2517, 57-9272, and 58-9640, and Japanese Utility Model Publication Nos. 
64-6622, and 58-4316). All the sensible vibration units disclosed in these 
publications have a structure in which an electro-mechanical vibration 
transducer is imbedded in or attached to a human body support member, for 
example, a chair, and vibration that is generated from the 
electro-mechanical vibration transducer is applied to the user's body 
through a vibration transmitting member or the human body support member. 
This type of body-felt vibration unit is designed to allow the user to feel 
low bass frequencies generated from an electric signal in the bass region 
by the vibration of the eardrum and the bodily-sensation of vibration with 
a view to relaxing the user mainly through the appreciation of music with 
an intensified feeling of being at a live performance, or through the 
bodily sensation of vibration by the vibration signal alone,, without 
music. Accordingly, body-felt vibration units, which have been proved to 
be effective medically or psychiatrically, are used in a wide field of 
application. 
As to the electro-mechanical vibration transducer (hereinafter referred to 
as simply "transducer") that is employed in the above-described body-felt 
vibration unit, a basic type of transducer has already been disclosed in 
U.S. Pat. No. 4,750,208. 
Transducers which are usable for the body-felt vibration unit include an 
electrodynamic type of transducer and an electromagnetic type of 
transducer, both of which are arranged such that a vibrating part thereof 
vibrates in accordance with the intensity of the input signal to cause a 
vibration transmitting member, which is imbedded in or attached to a human 
body support member, to vibrate in the direction of vibration of the 
vibrating part, so that the vibration is transmitted to the user's body in 
a direction normal to it. This vibration will hereinafter be referred to 
as "longitudinal vibration". 
The above-mentioned Japanese Patent Publication No. 58-2517 deals with an 
invention relating to a cushioning member that is to be interposed between 
a vibration transmitting member and the human body, and gives a 
description of the feeling that the user has when sitting on the chair, 
for example, as a human body support member, and the uniform dispersion of 
the vibration that is applied to the user's body in a direction normal to 
it. Japanese Patent Publication No. 57-9272 also discloses a combination 
of a vibrating plate and a cushioning member, but this invention aims at 
efficiently transmitting vibration to the user's body. The inventions in 
the other three publications described above disclose a means for reducing 
the size and weight of the transducer and a method of attaching the 
transducer to a human body support member. All of these three inventions 
relate to a device to allow the user's body to receive efficiently a sound 
signal in the low-frequency region from a vibration transmitting member. 
If a body-felt vibration unit is arranged such that vibration that is 
generated from a transducer is transmitted to the user's body through a 
human body support member, as described above, it is likely that all or 
part of the user's weight will be applied to the transducer, as a matter 
of course. It is therefore necessary to improve the human body support 
member or the transducer so that the transducer will not be damaged even 
if the user's weight is applied thereto. In other words, a reinforcing 
member or the like is needed in order to prevent application of 
unnecessary external force to the transducer, resulting in problems, such 
as an increase in the overall size of the apparatus. 
Further, from the viewpoint of the structural association of the transducer 
with the vibrating plate, disclosed in the above-described publications, 
the vibration transmitting plate that vibrates sympathetically to the 
vibration generated from the transducer must have a plate-shaped 
configuration and the plate-shaped member must be vibrated in the 
direction of the thickness thereof in order to attain the purpose thereof. 
In this case, the arrangement is such that, no matter where the transducer 
is imbedded in the human body support member, the vibration from the 
vibrating plate is transmitted to the user's body in a direction normal to 
it. Accordingly, the user's weight forms longitudinal vibration that is 
counter to the direction of vibration of the vibration transmitting 
member. 
In addition, since the transmission of vibration from the transducer to the 
vibration transmitting member is effected convergently, it is necessary in 
order to transmit uniform vibration to the whole vibration transmitting 
member to increase the thickness of the vibration transmitting member 
itself or to take into consideration the necessity of a structure in which 
transducers are dispersedly disposed. 
SUMMARY OF THE INVENTION 
In view of the above-described problems of the prior art, it is an object 
of the present invention to provide a body-felt vibration unit wherein a 
flat plate- or net-shaped vibration transmitting member of a relatively 
large area is attached to a transducer in such a manner that the vibration 
transmitting member is vibrated in the direction of the width thereof (the 
vibration being hereinafter referred to as "transverse vibration"). 
It is another object of the present invention to provide a vibration 
transmitting method for use in a body-felt vibration unit in which a 
vibration transmitting member is vibrated by a transducer, wherein the 
vibration transmitting member comprises a flat plate- or net-shaped member 
of a relatively large area which faces the user's body across a cushioning 
member, and vibration that is generated from the transducer is transmitted 
to the vibration transmitting member in the direction of the width of the 
latter. 
The vibration transmitting mechanism in the plate-shaped vibration 
transmitting member will be explained below. 
Assuming that vibration from the transducer is applied to the center of a 
flat plate-shaped member of a predetermined large area, the longitudinal 
vibration is transmitted to the periphery of the plate-shaped member from 
the transducer as the center of vibration. At this time, the intensity of 
the vibration transmitted attenuates as the distance from the center 
increases. The degree of attenuation is inversely proportional to the 
increase in the hardness and stiffness of the plate-shaped member. 
Accordingly, if the transducer is provided in the peripheral portion of the 
vibration transmitting member so that the user's weight will not be 
applied thereto, the longitudinal vibration attenuates markedly as the 
distance from the transducer increases, so that the desired effect cannot 
be obtained. 
However, it has been confirmed experimentally that, if vibration is applied 
from the edge portion of a plate-shaped member in the direction of the 
width of the plate-shaped member, that is, in a direction perpendicular to 
the direction of the above-described longitudinal vibration, the 
above-described attenuation becomes extremely small. This phenomenon is 
attributable to the fact that, if a vibrating medium is continuously 
present in the direction of the transverse vibration applied thereto, the 
transmission of the vibration is effected efficiently in proportion to the 
density and hardness of the medium. 
Considering that the vibration transmitting member of the present invention 
is not always used in the form of a flat plate, it will be understood that 
application of transverse vibration by making use of the above-described 
phenomenon is extremely effective from the viewpoint of the object of the 
present invention.

DETAILED EXPLANATION OF THE INVENTION 
One embodiment of the present invention will be explained below with 
reference to the accompanying drawings. 
Referring to FIG. 1, a vibrating mat 1 has a vibration transmitting member 
2 provided therein. The vibrating mat 1 is a bag-shaped member comprising 
soft cloth and urethane foam with a thickness of 25 mm and having the 
vibration transmitting member 2 wrapped therein. The vibration 
transmitting member 2 comprises a plastic net with a thread diameter of 
3.5 mm and has a proper hardness and elasticity. A vibrating plate 3 is 
attached to one end of the vibration transmitting member 2 in such a 
manner as to be erect at right angles to the direction in which the net 
extends. Four transducers 4 with a structure described later are attached 
to the vibrating plate 3. The transducers 4 are attached in such a manner 
that the transducers 4 are fitted into respective bores 5 provided in the 
vibrating plate 3 and secured by means, for example, bolts (not shown), as 
shown in FIGS. 3 and 4. The transducers 4 are preferably connected in such 
a manner that two pairs of series-connected transducers are connected in 
parallel to input terminals 6 and 7, as shown exemplarily in FIG. 5. 
If a sound signal having its low frequency component cut off is input to 
the transducers 4 attached to the vibrating plate 3 in this way, vibration 
that is generated from the transducers 4 is transmitted to the vibration 
transmitting member 2 through the vibrating plate 3. More specifically, 
transverse vibration is applied to the vibration transmitting member 2 
from the end thereof to which the vibrating plate 3 is attached. The 
reason why the vibrating plate 3 is interposed between the transducers 4 
and the vibration transmitting member 2 is to produce uniform vibration by 
transmitting the vibration of the transducers 4 as a vibration source to 
the relatively thick vibrating plate 3 so as to induce longitudinal 
vibration and by disposing the vibrating plate 3 over the entire edge 
portion of the plate-shaped vibration transmitting member 2. In principle, 
it is only necessary that the direction of vibration generated from the 
transducers 4 is coincident with the direction of the width of the 
vibration transmitting member 2. In the process of transmitting the 
vibration to the other end of the vibration transmitting member 2, the 
vibration is partly converted to vibration in the transverse direction 
(i.e., the direction intersecting the vibration transmitting member 2), 
but the user 9 who lies on the vibrating mat 1 feels mainly the transverse 
vibration. 
FIG. 6 shows another embodiment of the present invention, in which the 
body-felt vibration unit of the present invention is formed in the shape 
of a U and this is put on the center of a ready-made mattress 8 from above 
it, as shown in FIG. 7. In this state, vibrations that are generated from 
the transducers 4 are transmitted (in the form of transverse vibration) in 
the direction of the width of the mattress 8, as shown in FIG. 8. If the 
transducers 4, which are disposed at the left and right sides of the 
mattress 8 to face opposite to each other, are arranged to be opposite in 
polarity to each other, the vibrations exhibit synergistic effect in 
push-pull manner, as shown in FIG. 8. 
FIG. 9 shows one example of electrical conductive transducers 4. In this 
figure, reference numeral 10 denotes a base plate having its outer 
periphery formed into a flange, and 11 a cover. The cover 11 is secured to 
the base plate 10 by a bolt 12. A structure such as that described below 
is accommodated in a casing body that comprises the base plate 10 and the 
cover 11, thereby forming a transducer 4. 
As shown in FIG. 9, a yoke 13 has a T-shaped cross-sectional configuration. 
A ring-shaped magnet 14 is attached to the outer peripheral portion of the 
yoke 13, and a top plate 15 is provided on the outer side of the magnet 
14. These members are supported by the bolt 12 through a ring spring 16 
serving as a damper. Reference numeral 17 denotes a spacer. With the 
above-described structure, a magnetic air gap 18 is formed between the 
inner periphery of the top plate 15, one surface of which is in contact 
with the magnet 14, and the projecting portion of the yoke 13. A coil 19 
is provided in the air gap 18 such that a low-frequency current is 
supplied to the coil 19 from a sound device (not shown) through a cord 20. 
The transducer 4, arranged as decribed above, is attached to the vibrating 
plate 3 and supplied with a sound signal after it has been subjected to 
signal processing. More specifically, when the coil 19 receives a 
low-frequency current from a sound device (not shown), which has been 
subjected to signal processing, the coil 19 is caused to vibrate with 
respect to the integral structure comprising the yoke 13, the magnet 14 
and the top plate 15 by the magnetic interference between the coil 19 and 
the magnet 14. In consequence, the vibrating plate 3 having the transducer 
4 attached thereto longitudinally vibrates in the direction of the 
thickness thereof, so that the vibration transmitting member 2 vibrates 
transversely. The vibration allows the user 9 on the vibrating mat 1 to 
feel a bodily sensation of vibration. 
FIGS. 12 and 13 show a further embodiment of the present invention, in 
which the invention is applied to a seat 22 for an automobile. In this 
case, the vibrating mat 1 is curved in conformity with the seat 22, but 
the basic arrangement thereof is the same as that shown in FIG. 1. 
FIGS. 14 and 15 show a still further embodiment of the present invention, 
in which the invention is applied to a floor 23 for aerobics in a physical 
fitness gym. Reference numeral 24 denotes supports. To cause the floor 23 
to vibrate transversely in this case, the vibrating plates 3 may be 
disposed not only at the positions shown in the figure but also at the 
center or other positions of the floor 23. In this embodiment, when the 
apparatus is activated, the floor 23 vibrates transversely, as shown by 
the arrows in FIG. 15. 
Although the foregoing embodiments use the transducers 4 having an internal 
structure such as that shown in FIG. 9, it should be noted that the 
present invention is not necessarily limited thereto and that transducers 
4 with a structure different from the above may also be employed. The 
essential thing is to use transducers 4 which can generate a vibration 
corresponding to an input signal which varies incessantly in both 
frequency and amplitude, such as a musical signal. The low-frequency 
current that is applied to the transducers 4 is preferably below about 150 
Hz from the viewpoint of the vibration efficiency, but it is preferable to 
determine a proper cut-off frequency in conformity with the material of 
the vibration transmitting member 2, the configuration of the vibrating 
mat 1, etc. 
As to the vibration transmitting member 2, it is also possible to employ a 
film- or bar-shaped vibration transmitting member made of a plastics or 
other material, in addition to the plastic net employed in the described 
embodiments. 
As has been described above, according to the present invention, transverse 
vibration is applied to a plate- or net-shaped vibration transmitting 
member, and therefore, even if the vibration transmitting member is thin, 
the apparent rigidity becomes high, so that the transmission of vibration 
is made effectively. As a result, the following specific advantages are 
obtained: 
(1) The thickness of the unit can be reduced, so that the user can sit on 
it without discomfort. 
(2) Since the transducers can be arranged such that the user will not lie 
thereon, there is no probability of the transducers being destroyed. It 
was confirmed experimentally that satisfactory results were obtained also 
when a chair or the like was placed on the unit. 
(3) The unit can be formed in a soft structure, on the whole, and can be 
used as a rug which is suitable for either of Japanese- and Western-style 
rooms. 
(4) Because of the transverse vibration system, there is less acoustic 
radiation (i.e., beat note) from the vibation transmitting member by the 
woofer effect. The conventional longitudinal vibration system suffers from 
the disadvantage that, as the area of vibration of a floor or a rug 
increases, the acoustic radiation efficiency of bass increases and the 
acoustic radiation increases, whereas the present invention that adopts 
transverse vibration is free from such a problem. 
(5) The vibration transmission efficiency is high. Since the vibrating 
system can be made light in weight and superior in the vibration 
transmission, a product of high vibration efficiency can be obtained. More 
specifically, the conventional longitudinal vibration system involves the 
problem that, if the vibration transmitting member is made light in 
weight, it becomes soft, resulting in a lowering in the vibration 
transmission efficiency. However, in the transverse vibration system 
according to the present invention, the material is vibrated transversely, 
and therefore, even if the material is a net-shaped light plastic 
material, as shown in the embodiments, the stiffness in the direction of 
vibration can be maintained at a high level equivalently, so that the 
vibration transmission efficiency can be maintained at a high level. 
(6) Comfortable vibration can be obtained. The conventional longitudinal 
vibration system involves the problem that the user may have a feeling of 
being thrust up excessively, depending upon the kind of sound, whereas the 
transverse vibration system has less probability that such a problem will 
occur. 
(7) It is possible to cope with a vibration transmitting member with a wide 
area by driving it from both sides thereof. In such a case, transducers 
which are disposed at the two sides of the vibration transmitting member 
are arranged to be opposite in driving polarity to each other. When the 
area of the vibration transmitting member employed is wider than the 
above, it may be driven from four directions. 
(8) It is possible to form an even more convenient unitized commodity by 
attaching a speaker or/and an amplifier to a portion of the vibrating 
plate where the transducers are attached.