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FIELD OF THE INVENTION The present invention relates to cone speakers and in particular to
the improvement of the acoustic behavior of such speakers. It is already known to manufacture a
one-piece metal dome and a voice coil former for a cone speaker. This known product uses a
metal dome mainly for endothermic purposes and this dome is a nearly "flat" dome with a
slightly smaller curvature. Due to the malfunction of the dome and also of the cone with this
known product, a dispersion of the acoustic response occurs at relatively low frequencies. Rolloff based on this malfunction starts at as low as 2 to 3 KHz. Starting from the basis of a cone
speaker with a central dome, the following points are included in the object of the present
invention. 1. To achieve an acoustic response at the higher frequency limit of the voice band. 2.
Exciting the point at which the acoustic response is dispersed well above the voice band or at
least in the upper region of this band. 3. To substantially prevent the occurrence of vibration
mode. 4. To substantially prevent parasitic resonance of the dome. 5. substantially prevent the
occurrence of the self-resonant sound mode over the entire sound band. 6. Use a dome that is
made for its acoustic function and not made as a heat sink. 7. Activate the central dome over a
small (or larger) portion of the voice band. 8. To provide a central dome that is clean by its very
nature and is mechanically strong. The realization of these objects brings about a number of
advantages obtained by the loudspeaker according to the invention. These advantages are as
follows. 1, more stable acoustic response 2, prevention of dispersion in the voice band 3, easy
realization of smooth and loss over in multidirectional systems. 4, Realization of more practical
response at crossover frequency. 5 、 Loudspeaker's high frequency output makes sound like
tweeter (small speaker for high tone). 6, suitable for using electronic equalization to enable to
produce an accurate full-field speaker. Electronic equalization used with conventional speakers of
this type will increase the defects in acoustical properties. These objects and advantages are,
according to the invention, an annular cone, an acoustic radiator having mechanical strength and
being axially stiff and of its own nature. This is achieved by means of a cone loudspeaker
comprising a central dome.
Preferably the dome is also radially stiff. The shape and structure of the central dome and the
material or materials of which it is made are chosen to optimize the functionality of the dome and
to minimize malfunctions especially in the upper limits of the voice band. It is desirable for the
material of the dome to have a very high stiffness to weight ratio. One way to obtain the required
axial stiffness of the dome in conjunction with acting as a clean radiator is to shape the dome
with relatively steep sides. Preferably, the outer wall of the dome which descends from the top
end is at least steeply flanked, such as hemispherical. A dome of substantially hemispherical
shape has been found to be particularly suitable. As far as material is concerned, it has been
found that aluminum and titanium are particularly suitable materials for the central dome,
although the choice of material is determined by a wide variety of different ideas. Non-metallic
materials such as plastic materials reinforced with carbon fibers or glass fibers are also used.
Such materials have a particularly high stiffness to weight ratio. In the context of the present
invention, the central dome of the loudspeaker is made as comprising a voice coil form, or the
dome and the voice coil form are separated, possibly with an intermediate reinforcing ring. Ru.
EXAMPLES A number of embodiments of the cone speaker of the invention are illustrated below
by way of illustration and with reference to the accompanying drawings. As shown in the
drawings, this speaker comprises a conventional annular cone 10 with a compliance edge 12
around it. The dome 14 is located at the center of the cone. In Figures 1 to 3 the central dome 14
is a substantially hemispherical element. In FIG. 1, an integral cylindrical skirt 16 extends axially
in the open end of the dome. The core 10 is fixed to the outside of the central dome near the
point where the hemispherical dome element 14 and the skirt 16 meet. The top end of the
central dome 14 is here located substantially on the plane of the outer periphery of the cone 10.
However, in other embodiments, the dome top may be located above or below this plane. As
shown in FIG. 2, the voice coil 18 is shown wound on a voice coil former 20 separated from the
central dome 14 and has a T-shaped cross section and its T-shaped legs It has two components
held together by an intermediate reinforcing ring 22 located in the gap between the dome 14
and the former 20.
In this case, the dome 14 and the coil form 20 are manufactured as separate units. The coil
former 20 can be metallic or non-metallic. The reinforcing ring 22 provided around the dome 14
is located either inside or outside of the dome, preferably on the substantially hemispherical
equator. FIG. 2 shows an arrangement in which the T-shaped tongue has its T-shaped head
located outside the dome, in contrast to FIG. 31! I shows that this ring is inside the dome and
spans the gap between the dome and the former. The reinforcing ring 22 is preferably metal,
such as aluminum or magnesium, and is provided to enhance the radial stiffness of the dome.
The central dome 14 of the loudspeaker of the invention is a "hard" dome adapted to perform
well acoustically. Although a wide range of materials are used for the dome 14, it has been found
that titanium and aluminum are particularly good materials for this purpose. Although the need
to have relatively steep sides as domes has been shown in FIGS. 1 to 3 as being obtained by using
hemispherical domes, domes of other shapes and structures As shown in FIG. 4, for example, a
more elongated dome 14 'which is semi-ovoid may be used instead. In any case, the dome 14 is
axially rigid and has mechanical strength and, by its very nature, acts as a clean emitter, for
example up to about 17 KHz and preferably in the upper frequency range of the vocal cords
There is no malfunction at up to 20 KHz or more. The term "radial" as used herein is understood
to mean the direction transverse to the equator of the dome, whereas the term "axial" as used
herein refers to the dome vibrating in use It should be understood as meaning direction. Below
Brief description of the drawings
FIG. 1 is a schematic oblique view of a first embodiment of a cone speaker according to the
present invention, FIG. 2 is a partial view of a slightly modified dome structure, FIG. 3 is a partial
view of another modified dome structure, FIG. Is a schematic view of a dome having another
10: annular cone, 14: central dome, 16: skirt portion, 18: voice coil, 20: winding type, 22:
intermediate reinforcing ring. Below margin FIG. 2 ° FIG. 3 ° Procedure amendment (type) May
1st 1987 '5 ′ ′ Secretary General of Japan Patent Office Black 1) Akio Hall 1, display of case
Showa 621 patent application No. 30710 2, invention Name Corn Speaker 3 Relationship to the
Case of Correction Patent Applicant Name Celestion International Limited 4 Agent Address
Minato-ku, Tokyo 105 Toranomon-Min. Section 2 of “the applicant's representative” (2) Power
of attorney (3) specification (4) Figure 7; contents of correction (1) (2) as shown in the attached
sheet (3) None) (4) Drawing of clean book (no change in contents) 8, catalog of attached
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description, jps62248398
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