Acoustics – Diaphragm – Mounting or suspension means
Reexamination Certificate
2001-01-17
2003-04-08
Nappi, Robert E. (Department: 2837)
Acoustics
Diaphragm
Mounting or suspension means
C181S172000, C381S392000
Reexamination Certificate
active
06543574
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a speaker edge at the circumferential edge of a cone body (also referred to as a “speaker diaphragm body”).
BACKGROUND ART
In a speaker having a general configuration, as shown in
FIG. 5
, a cone body
50
composed of cone paper is retained on a frame F through a speaker edge
60
which is provided at the circumferential edge of the cone body, so that the cone body
50
is not prevented from vibrating. Incidentally, in order to not prevent the cone body
50
from vibrating, this speaker edge
60
is shaped so that a bent portion
65
, bent upward or downward with a sectionally arc shape, is formed between an inner circumferential edge
61
and an outer circumferential edge
63
.
In the background art, as such a speaker edge, there are: a speaker edge formed in such a manner that a foamed rubber composition is molded in a mold; a speaker edge formed in such a manner that molten resin of thermoplastic resin, for example, acrylic resin, polycarbonate resin, thermoplastic polyurethane resin, or the like, is injection-molded in a mold where a cone body is disposed; a speaker edge formed in such a manner that foamed polyurethane slavstock formed into a block by foam molding is cut out into a sheet with a predetermined thickness, and the foamed polyurethane sheet is shaped into the form of a speaker edge by heat compression with a press die; and so on.
However, the background-art speaker edges have problems as follows. First, in the speaker edge formed in such a manner that a foamed rubber composition is molded in a mold cavity, there is a problem that it is so heavy that the mass of a vibration system becomes heavy when the speaker edge is used in adhesion to a cone body. As a result, the sound pressure-frequency characteristic deteriorates. In addition, in the rubber speaker edge, there is another problem that high technology is required for bonding the speaker edge with a cone body.
In addition, in the speaker edge formed by injection molding out of molten thermoplastic resin, there is a problem that the temperature of the molten resin is about 200 to 300° C. which is so high that a cone body is apt to be damaged by heat when the speaker edge is molded integrally with the cone body in a mold.
In addition, in the speaker edge formed in such a manner that a slab of foamed polyurethane is cut out into a sheet and the foamed polyurethane sheet is molded by heat compression (hereinafter abbreviated to “slab cut-out heat compression molding”), the outer sides (convex sides) of bent base portions
66
and
67
shown in
FIG. 5
are extended on a larger scale at the time of heat compression by press molding so as to be low in density, while the opposite inner sides (concave sides) are compressed so as to be high in density. The state of density of such an uneven surface results in deterioration of strength. Thus, the speaker edge is not preferable in view of durability or the like. Particularly, in the speaker edge, the inner circumferential side of the speaker edge
60
vibrates together with the circumferential edge of the cone body
50
, while the outer circumferential side of the speaker edge
60
is bound on the frame F. As a result, fatigue is concentrated on the frame-side bent base portion
67
. Thus, in the speaker edge formed by slab cut-out heat compression molding, the strength of the bent base portion is not sufficient.
In addition, the above-mentioned foamed urethane sheet is cut out of a slab so as to have an even thickness, and molded by heat compression. Accordingly, there is a problem that a required portion of the speaker edge cannot be made to have an optimum thickness, for example, the bent base portions
66
and
67
where the strength is lowered in the above-mentioned compression molding cannot be thickened to enhance the strength.
In addition, the above-mentioned foamed urethane slab cannot help the fact that the density differs from one portion to another when the slab is foamed and produced. Thus, the foamed polyurethane sheet cut out of the slab differs in density from one cut-out position thereof to another. As a result, there is a problem that the speaker edge formed out of the cut-out foamed polyurethane sheet by heat compression molding varies widely in the lowest resonance frequency f
0
of the speaker so that the quality is hardly fixed. When the scattering of f
0
was measured in practice, it was ±15 Hz at N=100.
Further, in a speaker, or the like, which is disposed in a door of a car, waterproofness is required of the speaker edge. However, since the above-mentioned foamed polyurethane slab has such a property that water penetrates from the surface, there is a problem that the speaker edge formed by slab cut-out heat compression molding is also inferior in waterproofness. In order to solve this problem of waterproofness, there has been also proposed a speaker edge coated with fluororesin. Also in this speaker edge coated with fluororesin, however, since the coating has an open-cell cellular structure, it is not practical to coat the speaker edge thick enough to close aperture portions. It is therefore impossible to say that the waterproofness is ensured sufficiently. In addition, there is a problem that the cost increases.
In addition, in the above-mentioned speaker edge formed by slab cut-out heat compression molding, as shown in the expanded schematic view of
FIG. 6
which shows a section of an edge, the vicinity of a surface
65
a
is compressed at the time of heat compression molding, so that a hard and high-density skin layer
68
in which each cell H has been collapsed is formed through a clear boundary surface
68
a
between the skin layer
68
and a foamed layer
69
inside the skin layer
68
. Thus, since the physical properties change clearly and suddenly, the amplitude in resonance increases so that an undesired phenomenon is produced.
Taking the foregoing problems into consideration, it is an object of the present invention to provide a speaker edge which is high in strength, less in scattering of f
0
, high in waterproofness, small in amplitude in resonance, easy to mold, reliable and easy to be integrated with a cone body.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a speaker edge constituted by a molding which is molded in a manner so that a speaker edge raw material composition containing isocyanate and polyol is injected into a cavity of a mold by an agitating/mixing apparatus and subjected to reaction, foaming and curing the mold. The speaker edge raw material composition to be used for casting according to the present invention may be used in combination of ones suitably selected from formula systems applied for various purposes as polyurethane raw material compositions. So-called soft hot mold formula systems which are known, semi-rigid cold mold formula systems, or formula systems suitable for mechanical froth meatbod may be applied to molding.
(2) Further, the present invention is characterized in that the speaker edge raw material composition is injected into the molding cavity in which a cone body is disposed, and the speaker edge molded by reaction, foaming and curing of the raw material composition is bonded integrally with the cone body by chemical reaction at the time of the reaction, foaming and curing.
(3) Further, the present invention is characterized in that a composition having viscosity in a range of from 100 cps to 100,000 cps at room temperature immediately after mixing is used as the speaker edge raw material composition.
(4) Further, the present invention is characterized in that the polyol is composed of a mixture of polyether polyol and polypolyester polyol.
(5) Further, the present invention is characterized in that cell inside the speaker edge is composed of only closed cells or both closed and open cells.
(6) Further, the present invention is characterized in that a surface of the speaker edge is composed of a skin layer to which a mold surface of the mold is transferred.
(7) Further, the present invention is ch
Ikeda Kiyosi
Kaneko Shinya
Mizone Sinya
Yamasaki Hiroko
Inoac Corporation
Nappi Robert E.
San Martin Edgavdo
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