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1 specification 1, title of the invention
Speaker device
3. Detailed Description of the Invention The present invention relates to a suitable speaker device
when applied to an electroacoustic transducer or the like that allows a large input, and more
particularly to an improvement of means for improving the heat resistance of the device. A
speaker device applied to an electroacoustic transducer that allows a large input must be heat
resistant. FIG. 1 is a cross-sectional view showing the outline of a conventional large input cone
speaker apparatus, and FIG. 2 is an enlarged view of the main part of FIG. In FIG. 1 and FIG. 2, 1
is a core, 2 is a magnet for applying a magnetic bias, 3 is an upper plate mounted and fixed on
the magnet and constituting a magnetic circuit together with the core 1. A voice coil 5 wound
around the outer periphery of a cylindrical voice coil bobbin 4 is inserted in the gap between the
upper plate 3 and the core 1. 6 is a frame, and a speaker cone 7 is stretched between the tip of
the fan-muro and one end of the voice coil bobbin 4. 8 is a dustproof cap, 9 is a tinsel cord, and
10 is a cloth damper. The cloth damper 10 and the speaker cone 7 are bonded to the voice coil
bobbin 4 with an adhesive at a portion indicated by a symbol A. In such a large input speaker
device, the heat generation of the voice coil 5 may reach 200 to 300 C. Therefore, unless the sift
coil bobbin 4 is taken any means, the magnetic circuit may be overheated to cause thermal
deformation or characteristics of each part. It causes deterioration. Apart from this, damage to
the heat-resistant diaphragm, that is, the bonding point between the weakly vibrating plate, ie,
the cone 7 or the cloth damper 10, and the voice coil bobbin 4 is likely to occur. Will occur.
Conventionally, the following methods have been taken as means for solving such problems. One
of them is to dissipate heat to the voice coil bobbin 4 using a heat conductive aluminum material.
Another one is that the cross-sectional shape of the voice coil 5 is not a complete circle but a
square to enhance the heat radiation effect. Still another one is to make the shape of the
magnetic pole ball rich in asperities, and to increase the heat dissipation effect of the magnetic
circuit by attaching fins to the yoke to prevent overheating. Among the means described above,
the former two are relatively frequently used means, but in the case of a large entry casby force
device in which the temperature of the voice coil 5 reaches 200C to 300C, it is not sufficient to
use only the above two means. Therefore, in such a case, the third means for enhancing the heat
radiation effect of the magnetic circuit can not but be used in combination.
However, if this third means is used, the magnetic circuit and hence the entire device f11 may
become large and expensive. The present invention has been made in consideration of such
circumstances, and the purpose thereof is to have extremely high heat resistance, to be able to
form a light weight and firmly without any fear that the 4 may become large, and to manufacture
at a lower cost. It is an object of the present invention to provide a speaker device capable of
effectively suppressing unnecessary vibration modes in addition to the above. The details of the
present invention will be clarified below by the embodiments shown in the drawings. FIG. 3 is a
cross-sectional view showing the configuration of the main part of an embodiment of the present
invention shown corresponding to FIG. 2, and FIG. 4 is an enlarged view of a portion B of FIG. is
there. In the WJa diagram and FIG. 4, 1) is a core, 13 is a reed in the upper plate, and 14 is a
voice coil bobbin. The voice coil bobbin 14 is made of a material having good thermal
conductivity, such as aluminum. A voice coil 15 is wound on the bobbin 14. 12 is a speaker cone,
18 is an insulating tape, 19 is a tinsel cord, and 20 is a cloth damper. The speaker cone 17 is
obtained by sticking a non-air-permeable material such as a polymer film 77b on the inner
surface of a foam metal cone J7m made of foam metal. Here, the foam metal is a porous body
manufactured by applying the powder metallurgy method, and it is desirable that the relative
density is less than 80%, and is in the range of 10% or more. In the case of the relative tight
steering 80% or more, the predetermined heat radiation effect can not be expected, and it is not
appropriate because it becomes relatively serious. On the other hand, if it is 10% or less, it causes
a problem in mechanical strength. As a material, a foamed metal made of aluminum or an
aluminum alloy is most suitable in terms of specific gravity, 4 ° C. of heat body and practical
heat resistance temperature. However, Ti, Be, and the like are also possible. In the speaker cone
17 having such a configuration, its base portion is connected to one end of the bobbin 14
together with the cloth damper 20 as shown in FIG. Since the speaker device is configured as
described above, the heat generated by the voice coil 15 is transferred to the voice coil bobbin
14 having good thermal conductivity, and further to the cone 17 of the foam metal ring coupled
to the bobbin 14. Transfer heat and dissipate. In this case, since the cone 17 has a very large heat
radiation area, a good heat dissipation effect can be obtained. Thus, in the present apparatus, it is
possible to prevent the junction line between the voice coil bobbin 14 and the cone 17 from
being damaged due to overheating. Of course, since the temperature rise of the voice coil itself
can be suppressed, disconnection accident and insulation failure can be prevented.
Further, since it is not necessary to provide a special heat radiation means to the magnetic circuit
or the like, it is possible to prevent the complexity of the nine structures in which the magnetic
circuit and hence the entire apparatus is enlarged. On the other hand, since the foam metal is
extremely lightweight, the efficiency of the speaker does not decrease even if the thickness of the
diaphragm is large. Therefore, a speaker cone having a large bending rigidity can be obtained.
Incidentally, metal diaphragms have been considered conventionally, but since the specific
gravity of metal diaphragms is almost 1 or more, the speaker efficiency will be reduced unless
extremely thin materials are used. was there. Therefore, in such a product, the mechanical
strength is as low as EndPage: 2, and practically it is hardly used to cause various problems. This
point is solved in this device. Note that the speaker efficiency ytc] can be expressed as: Where
ρ0 is the density of air% e '(1 is the speed of sound in air, S is the face of the diaphragm, F is the
driving force, mD is the weight of the diaphragm, my is the weight of the voice coil, mb is the
voice It is the weight of the coil bobbin. As apparent from the above equation, the speaker
efficiency largely depends on the weight town of the diaphragm. Foam metal is very
advantageous in this respect. In addition, the foam metal has an effect of suppressing vibration.
Therefore, in the present apparatus, there is an advantage that the unnecessary vibration mode
generated on the diaphragm can be effectively damped. The following table is data showing the
results of various investigations in manufacturing the diaphragm of this device. However, the
diaphragm material is NiFoametal. Table 1 (Limiting expansion force) Table 2 (Compression
stress) Table 3 (Impact, breaking stress) Table 4 (Temperature coefficient) Table 5 (Sound
absorption) Note that the present invention is limited to the above-described embodiment It is
not something to be done. That is, although the cone-shaped speaker has been described in the
above embodiment, the present invention can also be applied to other types of speakers, for
example, a speaker provided with a dome-shaped diaphragm or a plane-centered diaphragm. As
the foam metal, one having open cells, one having non-air permeability on one side, or one
having open cells may be used. As described above, the present invention is a speaker device
characterized in that a diaphragm made of foam metal is coupled to a weight of voice coil formed
of a material having good thermal conductivity. Therefore, according to the present invention,
the heat radiation is performed via the foamed metal agricultural diaphragm which has a wide
heat radiation area of EndPage: 3 so that the heat resistance strength is remarkably enhanced
and various problems due to the heat generation of the voice coil can be eliminated. Since there
is no need to provide a special means of heat radiation for the circuit etc., there is no risk of the
apparatus becoming large in size, and it is warm and solid, and moreover, can be manufactured
inexpensively. It is possible to provide a speaker device having four exceptional advantages such
as the ability to suppress cine-required vibration modes.
4. Brief description of the drawings. FIG. 1 is a schematic view of a conventional cone speaker
device according to a fourth embodiment of the present invention. FIG. 2 is a cross-sectional view
showing the main part of FIG. FIG. 3 is a cross-sectional view showing the main part of an
embodiment of the present invention, and FIG. 4 is a cross-sectional view showing a part of the
same embodiment as enlarged. 1.11 ... core, 2 ... magnet, 3.13 ... top plate, 4. J4 ... voice coil
bobbin, 5 ° 15 ... voice coil, 6 ... frame, 7.17 ... speaker cone, 12a ... foamed metal cord /, 17b ...
polymer film, 8 ...・ Dustproof cap, 9.19 ... tinsel cord, io, 2 o ... cloth damper. Applicant agent
patent attorney, Takehiko Suzue piece 1 figure piece 2 figure piece 3 figure yF 40 i?
1EndPage: 4
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