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JPS63136798

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DESCRIPTION JPS63136798
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker system, and more particularly to a speaker system that is thin and enables high fidelity
reproduction. The demand for a thin and high fidelity reproducible speaker system is extremely
strong because of the advantage of space saving. By the way, the difficulty for thinning is not so
great for so-called mid-high frequencies above a few hundred hertz, but for low frequencies
below a few hundred hertz the sound is sufficient unless the volume velocity of the diaphragm is
increased I can not get the pressure level. However, when using a closed cabinet, the stiffness of
the cabinet SB (= ooCo2S2 / V + po; density of air + COi sound 3 pages speed + Si diaphragm area
y, cabinet volume) increases, so the diaphragm In the case where the cabinet is attached to the
cabinet, the sound pressure level in the low region is insufficient because the minimum
resonance frequency JOB iff 1M; the vibration system mass including the additional mass) is
high. In order to lower Jan, it is sufficient to increase M?i or to decrease (Sn + 5n) fi?. However,
if M is increased, the sound pressure level is lowered, so (Sa + Sn) can only be reduced. However,
in the case of a constant 5-1, since V is small in a thin speaker, it is impossible to reduce SB> SD
and foB. On the other hand, if S is reduced, the amplitude must be increased in order to secure a
constant volume velocity, which causes distortion. Therefore, in the conventional thin speaker
system, a rear open cabinet is mainly adopted. This will be described with reference to FIG. In
FIG. 7, reference numeral 1 denotes a diaphragm, which is attached to a cabinet 3f by an edge 2.
The drive system has been omitted for the sake of simplicity. The speaker system was attached to
the rigid wall 4 and the axial sound pressure frequency characteristics were measured while
changing the distance d to the rigid wall 4 as shown in FIG. Clearly, the lower the sound pressure
level is, the higher the distance from the hard wall 4 is. This is because the sound A emitted from
the front surface of the diaphragm and the sound B emitted from the rear surface have opposite
phases at the measurement point P and cancel each other as they approach the rigid wall. For
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this reason, although it is a thin speaker, it is not possible to secure a sufficient reproduction
sound pressure level unless it is installed 50 to 60 (m apart from the wall surface), and the
purpose of space saving was not fulfilled. In order to solve the above-mentioned drawback of the
open rear cabinet, even when closely attached to the hard wall, the sound radiated back and forth
is such that it generates a phase difference at the measurement point (mostly in phase) A method
of providing a path has been proposed.
This method will be described with reference to FIG. The cabinet 3g is provided with an opening
6, and the sound emitted from the rear surface of the diaphragm passes through the opening 6
and is emitted to the front through the five-page sound path 7 formed between the cabinet 3g
and the hard wall 4 Be done. For this reason, the sound directly radiated from the front surface
has a phase difference equivalent to the distance 1 compared to the previous example, and the
sound pressure level is improved. However, if the diaphragm area is increased to reduce the
amplitude of the diaphragm in the above method, the mass Ma (MaMP; mass of air in the sound
path) generated in the gap between the back of the cabinet and the hard wall increases and the
output sound pressure level Reduce. Therefore, in order to solve the above-mentioned problems,
the inventors have proposed a speaker system in which the central part of the large-area
diaphragm is open at the back and the peripheral part is sealed. The structure of this scheme is
shown in FIG. In this method, since the area of the rear opening provided in the cabinet 3h is
small, the MAL is small, and the rear opening effectively functions and the peripheral part is a
closed system in which no sound cancellation occurs. Even if it is a type speaker, there is an
advantage that sufficient low-pass reproduction is possible even if it is installed in close contact
with the wall surface. In the configuration as described above, it is difficult to cause the
diaphragm to vibrate with the piston because the load applied to the rear surface of the
diaphragm is largely different between the back open part and the closed part. It was the cause
of causing a peak dip on the characteristics. An example of the sound pressure frequency
characteristic is shown in FIG. 11. The characteristic B in the actual measurement has a clearly
larger peak dip than the characteristic B obtained in the simulation when the diaphragm vibrates
with a piston. In view of the above problems, the present invention provides a speaker system
which is thin and capable of sufficiently low-frequency reproduction even when closely installed
on a wall surface, and which realizes flat sound pressure characteristics over a wide frequency
range. The purpose is to Means for Solving the Problems In order to achieve the above object, the
speaker system of the present invention is provided with independent diaphragms, each driven
by an independent drive system. A speaker unit and a closed speaker unit are provided, and the
sound radiated from the opening of the rear open type speaker unit is emitted to the front
through the sound path. In the conventional method, since the rear open part and the closed part
are constituted by the same diaphragm, the load on the rear of the diaphragm is partially
different to prevent the piston vibration, but in the present invention, each is an independent
vibration. Since each plate is a plate, the load on the back of each diaphragm is equal and the
piston can be easily oscillated by driving the position of the node in free oscillation of the
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diaphragm.
Furthermore, since each diaphragm becomes smaller, even if a diaphragm having the same
configuration is used, the minimum individual resonance frequency can be high, and the piston
vibration band can be expanded. Embodiment An embodiment of the present invention will be
described with reference to the drawings. In FIG. 1, 3 is a cabinet of 1 m О 1 m О 6 cfn, 1a and
1b are diaphragms of 30 cr ILX 17?, and 1 C is a diaphragm of 3 o ? X 46 crn. As each
diaphragm, the thing which stuck the surface material of aluminum on the front and back of the
foam of thickness smm is used. The back surface of the diaphragm 1 & is a closed cabinet, and an
opening 6 is provided on the back surface of the central diaphragm 1c to form a back open
cabinet. Each diaphragm is driven by a total of four voice coils 8. Reference numeral 2 is an edge,
and 9 is a magnetic circuit for driving each voice coil 8. When the conventional diaphragm is
integrated, as described above, since the load on the back surface is different between the sealing
portion and the opening portion, stress concentration occurs near the boundary between the
sealing portion and the opening portion, causing distortion. In addition, there is a peak dip on the
sound pressure frequency characteristics. The sound pressure frequency characteristics of this
embodiment are shown in FIG. 2, but the characteristics of the independent diaphragm of this
embodiment have a much smaller peak dip than the characteristics of the conventional integral
diaphragm, The bandwidth is also expanding. Although a square diaphragm is used in the
present embodiment, the present invention is a nine beno that exerts an effect regardless of the
shape of the diaphragm, and for example, as shown in FIG. The same effect is obtained even in
the case where the back surface of the central portion is opened by the opening 6a and the back
surface of the outer peripheral portion is sealed, provided on the coaxial diaphragm 21.22
'provided through 21 L. . Furthermore, if the cabinet 31L is too small to ensure a sufficient phase
difference between the sound radiated from the rear port and the sound radiated from the front,
as shown in FIG. And the diaphragm 31.32 through the edge 2C and the sound path 7 is formed
between the back surface of the cabinet 3C and the rigid wall 4C, so that the sound emitted from
the mounting port of the crosspiece 10 is When the sound path 7 is emitted to the front surface,
an effect is obtained. Of course, the sound path 7 may be integrated with the cabinet 3d as
shown in FIG. 6 without using the wall surface, or as shown in FIGS. 6A and 6B in order not to
increase the thickness of the cabinet. The diaphragm 41.42 is provided at the central portion of
the cabinet 36 via the edge 2e, and the sound path 7e is provided via the opening 6e at the side
of the cabinet 3e so as to surround the central portion. May be
In these cases, it is not only necessary to attach the cabinet and the rigid wall in close contact
with each other, but it is also possible to obtain an effect that the installation can be performed
regardless of the unevenness of the wall. In the drawings, the same parts are denoted by the
same reference numerals. Effect of the Invention The present invention is sufficient to produce a
phase difference by radiating the sound emitted from the opening on the back of the rear part
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open net to the front through the sound path and to install it while being thin and in close
contact with the wall In a speaker system capable of low-range reproduction, by using
independent diaphragms for the rear surface i and the sealing portion, the piston vibration band
of the diaphragm is dramatically expanded to realize flat frequency characteristics. And can
reduce distortion. Furthermore, since each diaphragm becomes smaller, bending rigidity is
improved, so that the diaphragm can be made thinner and lighter, and hence the output sound
pressure level is improved. Also, I have 11 pages for the arrangement of the diaphragm.
Mountain deer will increase and assembly will be easier.
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a schematic cross-sectional view showing the configuration of a speaker system
according to an embodiment of the present invention, FIG. 2 is a sound pressure frequency
characteristic diagram of this embodiment and the conventional speaker system, and FIG. 4A and
4B are plan views showing the configuration when a crosspiece is provided on the back of the
cabinet to form a sound path between the cabinet and the rigid wall. Is a schematic sectional
view showing the configuration when the sound path is integrated with the back of the cabinet,
FIG. 6B, B is a plan view showing the configuration when the sound path is integrated with the
side of the cabinet, a schematic cross section, FIG. Is a schematic cross-sectional view showing
the configuration and sound path when the rear open speaker is attached to the wall, and FIG. 8
is a sound pressure frequency with the distance to the wall as a parameter when the rear open
speaker is attached to the wall Characteristic diagram, Figure 9 shows the configuration of the
speaker system with ports on the back of the cabinet FIG. 10 is a schematic cross-sectional view
showing the path of sound, FIG. 10 is a schematic cross-sectional view showing the configuration
of a speaker system in which the diaphragm is integrated in an open / closed combination
system, FIG. 11 is the sound of the speaker system shown in FIG. It is a pressure frequency
characteristic view.
1a, 1b, 1C ...... diaphragm, 2 ...... edge, 3.3 &, 30,3f3 ииииии cabinet, 4 ...... rigid wall, 5- .......... ...
crosspieces. Name of Agent Attorney Nakao Toshio and 1 more person 6 4 ... 3 3 Figure 6 (C) (f3)
Tomi Chichi 2- ?-Eji Figure 8 "60 cm---% j Sat 1 "). Eshi ? 20 cm? Shi cm willow \ Tsuchi
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