JPS5632900

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DESCRIPTION JPS5632900
Specification 1, title of the invention Flat plate speaker 1, diameter supported around edge by
edge, circular flat diaphragm of uniform thickness and plural parts produced when the circular
flat diaphragm is excited under free condition A plurality of cones having the same semi-apical
angle with the outer peripheral portion fixed to each of the nodal circles, and a bobbin having the
button voice coil fixed at one end and the inner peripheral portion of the plurality of cones fixed
at the other end; A flat-plate speaker comprising: a vibration system comprising a snore to hold
the periphery of the bobbin; and a magnetic circuit having a magnetic gap for drawing in the
voice coil and providing a DC magnetic field.
2, the scope of claims
DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flat panel
speaker which mode-drives a circular flat diaphragm. Generally, when attempting to obtain wideband reproduction using a flat diaphragm of uniform thickness, if you drive a joint circle
generated when the peripheral free diaphragm is excited, the band as a speaker has the following
resonance frequency It is known to spread up. Also, in the case where there are a plurality of
driving node circles, it is necessary that the forces applied to the node circles of each n be
substantially equal. The conventional flat speaker has a diameter n (= o, 541D) and a (==
0.391D,) corresponding to the nodal circle of the second mode of the circular flat diaphragm 1
having a diameter, as shown in FIG. ) Outside diameter 7). Inner diameter D4. Half apex angle θ,
cone 11 and outer diameter 8. Inner diameter D4. It is a system driven by the outer peripheral
part EndPage: 1 of the cone 12 of half apex angle (theta) and. The distribution of the force given
to each joint circle in this prior art example will be described with reference to FIG. Force F
generated in the voice coil 4 Is F at cone IN, = pocosθ4. In the cone 12, it propagates as y, ==
yocos θ2. Next, in the circular plane diaphragm 1, the component force in the vertical direction
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is p ′ ′ at the connection point with the cone 111 and the connection point with the FBHQO
8θ11 cone 12 == F′2008θ. FB、FBをF。 If you organize about FB = FO cos' θ ,. It
becomes F4 = F6oos'theta. In the conventional example, 01 ← θ, so it is clear that FB ′ ′ eF 4
is 9 and the forces distributed to each node circle are unequal. As a result, as indicated by the
dotted line in FIG. 7 showing the sound pressure frequency characteristics of the flat speaker, it
is busy and peaks around 4 to 5 KH2. There was a gap and the bandwidth was narrow, and the
performance was insufficient. An object of the present invention is to provide a flat panel speaker
having a flat sound pressure frequency characteristic and a wide band without the abovementioned drawbacks of the prior art. According to the present invention, in order to give almost
equal force to a plurality of joint circles of one circular plane diaphragm 1), the half apex angles
of the cone 11 and the cone 12 for driving are equal. Thus, the force transmitted through each
cone and the force applied to each node circle of the circular flat diaphragm 1 were equalized.
The present invention will be described according to FIG. FIG. 3 shows a first embodiment of the
present invention, in which a circular flat diaphragm 1 ° and two large and small cones 11 and
12 are used. ボビ/3. ボイスコイル4. A vibration system consisting of an edge 2 and a
spider 13; It is a flat speaker configured of a magnetic circuit including the magnet 6, the outer
yoke plate 7 and the sound absorbing material 14.
The circular flat diaphragm 1 has a uniform thickness and diameter. The joint mode circle of the
second mode in the surrounding free state, = 0.841 D, D, = O,! It occurs at 191. Outer diameter 7.
Inner diameter D4 + half apex angle θ, cone 11 and outer diameter D8 + inner diameter D4. The
cone 12 of the half apex angle θ is formed, and the outer periphery is fixed to the node circle of
the circular diaphragm 102 order mode, and the inner periphery of each cone has an outer
diameter D4. It was fixed to the bobbin 3. A voice coil 4 is wound around the other @ of the
bobbin 3 to apply an alternating current. The periphery of the circular flat diaphragm 1 is
suspended by an edge 2 on a frame 8, and the bobbin 3 is supported by a spider 13. The
distribution of the force given to each joint circle in this embodiment will be described with
reference to FIG. The force F0 generated in the voice coil 4 is F in = r-711, = F (I cos θ4. It
propagates in the cone 12 as F2 = Focosθ. Next, in each node circle of the circular plane
diaphragm 1, the vertical component force becomes F, = pz cos θ2 at the connection point with
F-FlooB'11 cone 12 at the connection point with co-711. FsF、をF。 If you organize about
Fs = Fo (3) 2θ ,. It becomes F4 = FBcos2theta2. In the present embodiment, θ, = θ, and thus,
clearly F, = F, and the forces distributed to the joint circles are equal. A second embodiment of
the present invention will be described with reference to FIG. In the second embodiment, a
circular flat diaphragm 1 and an outer cone 15 concentrically fixed to the back surface of the
circular flat diaphragm 1. 2. A bobbin in which the voice coil 4 is wound around an inner 111
cone 16, 1jl. エツジ2. Vibration system consisting of spider 13 and ball plate 5. It is a flat
speaker composed of the magnet 6, the outer yoke plate 7 and the sound absorbing member 14
or the magnetic circuit consisting of j5. The circular flat diaphragm 1 has a uniform thickness
and diameter. The joint mode circle of the second mode in its peripheral free state occurs at -0,
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841 D, D: 0.391. Outer diameter D2. The outer cone 15 whose inner half apex angle is θ is fixed
at its outer peripheral portion to the diameter D20 node circle of the circular flat diaphragm 1,
and its inner peripheral portion is fixed to the outer side of the bobbin 3. The inner cone 16 with
an outer diameter D4 = 0.616 D, an inner diameter = 0.391 D, and a half apex angle θ2 is upside
down, and the inner peripheral portion of the inner cone 16 is the inner side of the circular plane
diaphragm 1 The outer peripheral portion of the inner cone 16 is fixed to the inner pressure of
the bobbin 3. The voice coil 4 is wound around one other 1 mK of the bobbin 5 and the spider 13
is fixed to the periphery 8 of the bobbin 3 between the voice coil 4 and the fixed portion of the
outer cone 15 to support the bobbin 3. It is fixed around the circular flat diaphragm 10 and
suspended on the frame 8.
EndPage: The distribution of the force applied to each node in the present embodiment will be
described with reference to FIG. Force F generated in the voice coil 4 , F at the outer cone 15, = F,
■ Sθ, It propagates as F2 = FO cos θ 2 in the inner core 716. Next, in each node circle of the
circular plane diaphragm 1, the vertical component force is p, = l ′, 008θ7, 7 at the connection
point with the outer cone 15. At the connection point with the inner core -716, F = F2 cos θ2.
F、、F6をF。 If we arrange for F, = Focos'? '+ 16 = F6QO8' ?. In the present embodiment, θ,
= 02, so that clearly KF, = F. And the power distributed to each joint circle becomes equal. As
described above, by equalizing the half apex angles of the cones for driving each nodal circle, the
forces for driving each nodal circle are all equal, so that the circular flat diaphragm 1 can be
driven in a balanced state. became. Specific numerical examples will be described for the first
embodiment of the present invention. As a circular flat diaphragm 1, a honeycomb core material
having a diameter of 123 mm and a thickness of 5 ff ff fl is sanded with an aluminum thin plate
on the surface, and a cone 11 piece outer diameter 103.4 rnrr, inner diameter 36.5 mmθ, = 380,
cone 12 Outer diameter 48.1 mm inner diameter 36.5 mm θ = 38 °. All materials were
aluminum. The nine-plane speaker prototyped with the above-mentioned material has the
characteristics of the solid line shown in Fig.7. The characteristics of the conventional example
described in 1-point 1 in FIG. 7 are also shown, and the circular flat diaphragm is made of the
same material and the same size as that of the present embodiment. The apex angle θ is 41 °,
and the half apex angle θ2 of the cone 12 is 10 °. In the conventional example, the beak 1 tag
is generated at 4 to 5 KHz and the band is narrowed, but in one example, the peak and gap
disappear and the sound pressure frequency characteristic becomes flat, and the high region
resonance frequency is also high 8 KHz Moving as above, the band as a whole has an effect of
spreading twice as much as the conventional example.
4. Brief description of the drawings. FIG. 1 is a cross-sectional view of a conventional flat speaker,
FIG. 2 is a partial cross-sectional view of the conventional flat speaker with distributed force, and
FIG. FIG. 4 is a cross-sectional view of the first embodiment, FIG. 4 is a cross-sectional view of the
second embodiment of the flat loudspeaker according to the present invention, and FIG. FIG. 7 is
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a sound pressure frequency characteristic diagram of each of the flat speaker of the prior art and
the present invention, in which FIG. 1: Circular plane diaphragm 3: Bobbin 4: Voice coil 11: Large
cone 12: Small cone 15: Outer cone 16: Inner cone 17: Magnetic air gap 5: Ball plate 6: Magnet
7; Outer yoke great. O Fig. 1 EndPage: 3 o 2 2 days off 3 years old 4 fig o 5t ¥ 1 EndPage: 4
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