U.S. patent number 3,645,356 [Application Number 05/100,959] was granted by the patent office on 1972-02-29 for loudspeaker.
This patent grant is currently assigned to Nippon Gakki Seizo Kabushiki Kaisha. Invention is credited to Hiromi Sotome.
United States Patent |
3,645,356 |
Sotome |
February 29, 1972 |
LOUDSPEAKER
Abstract
A loudspeaker including a diaphragm, means for driving said
diaphragm, an annular suspension member of rubberlike elastic
material attached to the marginal edge of said diaphragm and a
supporting frame to which said suspension member is fixed,
characterized in that said suspension member has a relatively large
radial width and a tapered thickness which gradually decreases from
the outer peripheral portion to the inner peripheral portion, and
said member is fixedly connected at said outer peripheral portion
to the supporting frame and at said inner peripheral portion to
said marginal edge of the diaphragm.
Inventors: |
Sotome; Hiromi (Hamamatsu,
JA) |
Assignee: |
Nippon Gakki Seizo Kabushiki
Kaisha (Hamamatsu-shi, JA)
|
Family
ID: |
14376813 |
Appl.
No.: |
05/100,959 |
Filed: |
December 23, 1970 |
Foreign Application Priority Data
|
|
|
|
|
Dec 26, 1969 [JA] |
|
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44/104291 |
|
Current U.S.
Class: |
181/172 |
Current CPC
Class: |
H04R
7/20 (20130101); H04R 2307/207 (20130101) |
Current International
Class: |
H04R
7/00 (20060101); H04R 7/20 (20060101); G10k
013/00 (); H04r 007/00 () |
Field of
Search: |
;181/32R,31R,24 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Tomsky; Stephen J.
Claims
I claim:
1. A loudspeaker comprising a diaphragm, means for driving said
diaphragm, an annular suspension member of elastic material, and a
supporting frame, said annular suspension member having a
relatively large radial width and a tapered thickness which
gradually reduces from its outer peripheral portion to its inner
peripheral portion and said member being fixedly connected at said
inner peripheral portion to the marginal edge of said diaphragm and
at said outer peripheral portion to said supporting frame.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a loudspeaker. More particularly,
it relates to a suspension for supporting a marginal edge of a
diaphragm of a loudspeaker onto a supporting frame.
Heretofore, various forms of suspension have been used to support
an edge of a diaphragm of a loudspeaker. Typical forms are shown in
FIGS. 1, 2 and 3.
FIG. 1 shows a suspension in which a diaphragm 1 is formed at its
edge portion with a corrugation 2, whose outer periphery in turn is
fixed at its periphery on a supporting frame 3. In such a
suspension, the available amplitude of the diaphragm can be
increased by increasing the number of waves of the corrugation 2 or
increasing the radial width of the suspension portion, but the
suspension portion having a large radial width and being
macroscopically of flat shape, tends to produce free vibration,
which will cause deep dips in the frequency characteristic of the
loudspeaker.
FIG. 2 shows a suspension in which a diaphragm 11 has, adhered to
the marginal portion thereof, a roll-shape suspension 12 whose
outer periphery in turn is fixed to a supporting frame 13. This
suspension has an advantage over the one shown in FIG. 1, in that
relatively large available amplitude can be obtained with
relatively narrow radial width of the suspension, which is of
unflat shape. The larger available amplitude, however, cannot be
obtained without the increase of the radial width and the
corresponding increase of radius of curvature of the roll-shape
suspension. The increase of the radius of curvature causes extreme
decrease of the strength of the suspension itself so that the
suspension may produce resonance in opposite phase relative to that
of the diaphragm or it may be adversely affected by the vibrating
air on the front and rear sides of the diaphragm.
FIG. 3 shows a suspension in which a diaphragm 21 is attached at
its periphery to a suspension sheet member 22 made of foamed
urethane or the like material, whose outer periphery in turn is
fixed on a supporting frame 23. The suspension of FIG. 3 produces
good results in the small amplitude range, but it has the same
defects as explained with reference to FIG. 1 in the large
amplitude range.
SUMMARY OF THE INVENTION
It is a general object of the present invention to provide a
loudspeaker which eliminates the disadvantages of the prior art as
noted above.
It is a particular object to provide a loudspeaker in which a
radial width of an edge portion is increased so that a large
available amplitude can be obtained with small deformation of the
suspension body itself.
It is another object of the present invention to provide a
loudspeaker having a suspension which provides lesser free
vibration and greater damping action than those of the prior art,
and which has sufficient strength to resist the vibrating air on
the front and rear sides of the diaphragm, so that few and little
peaks and dips appear in the frequency characteristic throughout
the whole sound range from low to high frequency sound.
It is a further object of the present invention to provide a
loudspeaker in which lowest resonance frequency can be easily
lowered so that satisfactorily low-frequency sound can be
reproduced even when mounted in a small cabinet.
In accordance with the present invention there is provided a
loudspeaker which comprises a diaphragm, means for driving said
diaphragm, an annular suspension member of elastic material, such
as rubber, attached to the marginal edge of said diaphragm, said
annular suspension member having a relatively large radial width
and a tapered thickness which gradually decreases from its outer
peripheral portion to its inner peripheral portion, and a
supporting frame to which said annular suspension member is fixed
at the outer peripheral portion thereof.
DESCRIPTION OF DRAWINGS
FIGS. 1, 2 and 3 are sectional views, showing diaphragm suspension
portions of three conventional types of loudspeaker, respectively;
and
FIGS. 4 and 5 are sectional views, showing diaphragm suspension
portions of two forms of loudspeaker according to the present
invention, respectively.
DETAILED DESCRIPTION
Referring the the drawings, FIG. 4 shows a form of a loudspeaker
according to the present invention, which includes a diaphragm 31
driven by any conventional driving means (not shown), an annular
suspension member 32 made of rubberlike elastic material attached
to the marginal edge of said diaphragm and a supporting frame 33 to
which said annular suspension member is fixed, said annular
suspension member 32 having a relatively large radial width. Said
suspension member 32 has an increased thickness at its outer
peripheral portion 34, which is fixed on the supporting frame 33.
The thickness gradually decreases from the outer peripheral portion
34 toward its inner peripheral portion 35 to which the marginal
edge of the diaphragm is adhered.
FIG. 5 shows another form of a loudspeaker according to the present
invention, which includes a diaphragm 41, a suspension member 42
and a supporting frame 43. The construction of these elements is
substantially same as that shown in FIG. 4, except that the
marginal edge of the diaphragm 41 is not adhered to the inner
peripheral surface of the suspension member, as shown in FIG. 4,
but inserted into and fixedly held by a groove formed in the inside
peripheral surface of the annular suspension member 42.
In practice, the radial width of the annular suspension member as
shown in FIGS. 4 and 5 for supporting the diaphragm having the
diameter of 30-40 cm. or more may be about 3-10 cm., depending on
the size of the diaphragm or the setting of the lowest resonance
frequency, and the thickness of said member at the outer peripheral
portion fixed on the supporting frame may be about 5-20 mm.
Although two forms of the connection between the diaphragm and the
suspension member are illustrated in FIGS. 4 and 5, such connection
may be constructed in other forms. For example, the diaphragm and
the suspension member may be overlapped together over the larger
width of connection, in order to avoid the occurrence of abrupt
boundary condition change which would produce reflection of
vibration.
It will be understood that the present invention provides a
loudspeaker in which a large available amplitude can be obtained
since the diaphragm is supported at its marginal edge on the
supporting frame through the relatively wide annular suspension
member made of rubberlike elastic material, and a flat frequency
characteristic is obtained because the tapered form of said
suspension member serves to reduce the resonance of the suspension
portion and smoothly absorb the vibration. The suspension member,
which is made of rubberlike elastic material, has good damping and
vibration-absorbing property. Because the suspension member has
gradually reduced thickness toward its inside periphery, it
produces under any vibrating frequency the vibration of only
minimum mass portion of said member required to obtain the
amplitude corresponding to said vibrating frequency, and
consequently good radiation efficiency and good transient property
can be obtained. The suspension member, which is thick and durable,
serves to improve the durability and weather-resistant property of
a loudspeaker. The loudspeaker can reproduce low-frequency sound
even when mounted in a small cabinet in view of the fact that the
lowest resonance frequency can be easily lowered.
* * * * *