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DESCRIPTION JPH0335694

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DESCRIPTION JPH0335694
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
Hi-Fi speaker, and more particularly to a dome-shaped speaker for improving input resistance
and improving directivity. (1) (2) Prior Art In recent years, a speaker apparatus for Hi-Fi has been
desired to be highly resistant to human power and to improve directivity so as to reproduce a
uniform tone even when listening to it with a toe. As a known technique for improving directivity,
a dome-shaped speaker that receives high-pitched sound is dealt with in a direction to make the
effective diameter of the diaphragm smaller, but the voice coil diameter becomes smaller and the
input resistance is improved. Has not improved. The above-mentioned conventional dome-shaped
speaker will be described below with reference to the drawings. FIG. 2 shows a cross section of a
conventional dome-shaped spinno. In FIG. 2, 1 is a bottom plate, 2 is a ring-shaped magnet, 3 is a
top plate, and the bottom plate 1 and the top plate 3 sandwich the magnet 2 to form a magnetic
circuit, and an annular magnetic gap 4 is formed. Form A voice coil 5 is wound around a voice
coil povin 6 and is suspended so as to be able to vibrate in the magnetic gap 4. A dome
diaphragm 7 is formed of a thin metal foil. A rubber coating is applied to the outer peripheral
portion of the dome diaphragm 7 to which a roll edge 8 formed of a non-air-permeable cloth is
fixed. The outer peripheral portion of the roll edge 8 is fixed on the spacer 9 and is held by the
baffle plate 10. Further, a shielding plate 11 is formed on the inner peripheral portion of the
baffle plate 10 in order to shield the sound from the roll edge 8. 12 is a screw for fixing the
baffle plate. The operation of the dome-shaped speaker configured as described above will be
described below. First, the voice coil 5 is suspended in the magnetic gap 4. When an electric
signal is applied, the voice coil 5 vibrates according to Fleming's left-hand rule to vibrate the
dome diaphragm 7 via the voice coil bobbin 6. Explaining from the viewpoint of the directivity of
sound, according to the following equation, at the same frequency, if the directivity angle (?)
becomes a wide angle, the sound pressure level decreases, and it is further determined by the
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ratio of diaphragm diameter to wavelength In order to reduce the effective diaphragm diameter
including the edge. ? = ? o 2 J + (k a-s i n ?) / (ka-sin ? ?); velocity potential a at a certain
directivity angle <?): effective vibration radius ? 0; velocity potential on the axis ? P; sound
pressure J l: No. A Bessel function 0 0: density k of air; and a wave constant so that the acoustic
radiation from the roll edge 8 is blocked II: a shield 11 is provided on the front surface.
However, in the above-described conventional configuration, the voice coil diameter can be set
large, and the input resistance to the speaker can be improved. However, since the roll edge 8
vibrates in the shielded space, the shield is shielded. There is a problem that sound is radiated
from between the plate 11 and the dome diaphragm 7 and peaks and dips occur in the sound
pressure frequency characteristics. SUMMARY OF THE INVENTION The present invention solves
the above-described conventional problems, and provides a dome-shaped speaker in which the
sound pressure frequency characteristic is smooth and the directivity is improved by improving
the resistance to input to the speaker. Means for Solving the Problems In order to solve the
problems, the dome-shaped speaker according to the present invention comprises a metallic
diaphragm such as titanium or a non-metallic dome diaphragm such as mica, and an airpermeable diaphragm fixed to the outer periphery thereof. An edge formed of a large thin cloth,
paper or the like is provided, and a shield plate disposed on the front surface of the edge and
formed of a part of the baffle plate is used. Operation With this configuration, the voice coil
diameter is increased to improve the input resistance, and since the edge has air permeability,
there is no radiation of sound even if it vibrates in the shielded space, and the effective
diaphragm diameter is small, so it is smooth. Sound pressure frequency characteristics and wide
directivity characteristics can be obtained. Embodiment An embodiment of the present invention
will be described with reference to the drawings. In FIG. 1, 13 is a bottom plate, 14 is a ringshaped magnet, 15 is a top plate, and the bottom plate 13 and the top plate 15 sandwich the
magnet 14 to form a magnetic circuit to form an annular magnetic gap 16. Form. A voice coil 17
is wound around a voice coil bobbin 18 and is suspended so as to be able to vibrate in the
magnetic gap 16. A dome vibration 19 is formed of a thin metal foil, and its outer peripheral
portion is fixed to a roll edge 20 formed of a cloth. The outer peripheral portion of the roll edge
20 is fixed on the spacer 21 and sandwiched by the baffle plate 22. Further, a shielding plate 23
is formed on the inner peripheral portion of the baffle plate 22 in order to shield the sound from
the roll edge 20. Reference numeral 24 denotes a screw for fixing the baffle plate 22. Here, the
roll edge 20 has a highly air-permeable property in which a relatively coarse woven thin cloth is
impregnated with a phenol resin or the like to be hot-bottomed. The operation of the domeshaped speaker configured as described above will be described below. The driving force acting
on the voice coil 17 by the electrical signal is similar to that described in the prior art. In the case
of this embodiment, even if the diameter of the voice coil is increased, there is no radiation of
sound even if it vibrates in the shielded space because the roll edge 20 has air permeability, and
the effective diaphragm diameter is small. It is possible to obtain frequency characteristics and
wide directivity characteristics in the high range.
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As described above, according to the present embodiment, even if the voice coil diameter is
increased, a relatively coarse-grained thin cloth is formed on the outer peripheral portion of the
dome diaphragm 19 formed of metal thin foil. By fixing the roll edge 20 having a large property
of air permeability which is made by impregnating it with heat, there is no radiation of sound
from the edge vibrating in the shielding space, and the effective vibration diameter becomes
small, It is possible to improve directivity at high input resistance and high range. As described
above, according to the present invention, the present invention is formed of a metallic
diaphragm such as titanium or a non-metallic dome diaphragm such as mica, and a highly
breathable thin cloth or paper fixed to the outer periphery thereof. For example, a relatively
coarse, thin cloth is impregnated with a phenol resin or the like to form a thermoformed edge,
and a shield plate disposed on the front of the edge and formed of a part of the baffle plate.
Therefore, even if the voice coil diameter is increased in order to achieve high input resistance,
the diaphragm diameter can be reduced by the shielding plate, and the edge has air permeability.
Because there is no radiation of sound, it is possible to realize a dome-shaped speaker whose
directivity can be improved in the high range.
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a cross-sectional view of a dome-shaped speaker according to an embodiment of the
present invention, and FIG. 2 is a cross-sectional view of a conventional dome-shaped speaker.
13 и и и и и и и и Bottom plate, 14 и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и
voice coil, 18
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ииии Baffle plate, 23 ииии ииииииииииииииииииииииииииииииииииии Bis.
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