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Industrial Application Field The present invention relates to a magnetic speaker (hereinafter
referred to simply as a speaker) in which a planar diaphragm is improved. More specifically, a
WPC-processed wood thin plate having excellent dimensional stability and suitable physical
properties as a diaphragm of a speaker in characteristics such as internal friction and rigidity is
used as a planar diaphragm. 2. Related Art Conventionally, cone paper in which a valve is formed
in a conical shape has been widely used as a flat diaphragm of a speaker. The pulp has
characteristics suitable for the diaphragm in terms of internal friction and specific gravity, but it
is formed into a cone shape due to lack of rigidity, so that not only the storage space becomes
large but also the cavity at the four parts of the cone There is a problem that resonance occurs
and the frequency characteristic is disturbed. In order to solve the above-mentioned problem of
the frequency characteristics, in recent years, a flat plate of honeycomb 4R structure having a
light metal such as aluminum, a carbon fiber reinforced plastic, a glass fiber reinforced plastic,
etc. as a core material is also widely used. . In the case of the planar diaphragm of the
honeycomb structure, although it has flat frequency characteristics as compared with the abovementioned cone paper, there is a problem that adverse effects such as cell resonance are easily
generated. In order to prevent the occurrence of resonance, there is a problem that the structure
is complicated and the manufacturing cost is increased. The present invention has been made in
view of the problems described above, and does not generate resonance as compared with
conventional pulp cones or honeycomb diaphragms, and has excellent dimensional stability and
an internal It is an object of the present invention to provide a speaker provided with a flat
diaphragm having physical properties suitable for the diaphragm of the speaker in the
characteristics such as friction and rigidity, and having a low manufacturing cost. The speaker of
the present invention has a specific gravity of 0.25 to 0 formed in a thin plate so that a grain
surface or a grit surface such as softwood such as Sitka spruce or hardwood such as zelkova
appears on the surface. It is characterized in that a WPC-treated treated wood obtained by
impregnating and curing a wood material such as polyester with a wood material of .8 is adopted
as a flat diaphragm. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be explained in
more detail below by means of an embodiment shown in the drawings. In the loudspeaker shown
in FIGS. 1 and 2, the flat diaphragm 1 is attached to the square surface opening of the metal
frame 3 via the edge 2 bonded and fixed to the outer peripheral edge thereof. A ferrite magnet 4
is attached to the back surface of the metal frame 3 by adhesion using a metal plate 5 and a
metal yoke 6, and a hole is formed in the center of the plate 5 and the ferrite magnet 4. A gap S
is provided between the inner peripheral surfaces of 5 a and 4 a and the outer peripheral surface
of the hollow cylindrical portion 6 a protruding from the center of the yoke 6.
On the other hand, as shown in FIG. 3, a quadrangular frame-shaped support member 7 made of
a sitoku spruce material is adhesively fixed to the back surface of the flat diaphragm l, and the
substantially square pyramidal aluminum armature 8 is formed on the support member 7. The
front end face of the coil case 9 is adhered, and the coil winding frame 9 is adhered and fixed to
the rear end of the armature 8. A voice coil IO is attached to the rear end of the coil winding
frame 9, the voice coil attached portion is inserted into the gap S, and the voice coil IO and the
ferrite magnet 4 are opposed to each other. . Two lead wires 11 for supplying an audio signal are
attached to the coil winding frame 9 to the coil winding frame 9, and a cloth damper 12 is
interposed between the outer periphery of the coil winding frame and the inner circumferential
surface of the frame 3. doing. Therefore, when an audio current signal flows from the lead wire
11 to the voice coil IO, the voice coil 10 and the coil winding frame 9 vibrate according to the
signal, and the flat diaphragm 1 via the support member 7 along with the vibration. Vibrates and
sound is generated from the front of the diaphragm l. The flat diaphragm I described above is
WPC treated on a single sheet of Sitka spruce face material having a specific gravity of 0.43
formed in a rounded square with a thickness of 1 to 2 mm (2 mm in the example) and a length of
105 mm on each side. It is That is, after placing a single veneer of Sitka spruce grit material in a
pressure and pressure device and removing the air inside the same veneer by pressure reduction,
plastic, such as polyester and polystyrene, is injected under pressure, and a weight ratio of 30 to
40% The specific gravity is 0, 56 which is impregnated into the inside of the single body and
cured. As wood materials to be subjected to WPC treatment, those having a specific gravity of
0.25 to 0.8, such as softwoods such as Sitka spruce or hardwoods such as zelkova, are used. It is.
For example, a square of Sitka spruce has a specific gravity ρ of about 0.43, a dynamic Young's
modulus of about 1.25 × 10 10 dyne / cm , and an internal friction of about 6.35 Q− ′ ×
10 On the other hand, it has a large Young's modulus, so it is light in weight and stiff, and it has a
very high speed of sound, given by / T7; l ;, which makes it suitable as a speaker diaphragm.
However, since the sitoc spruce material is a natural material, it has high hygroscopicity, lacks
dimensional stability, and when the humidity is high, the sound pressure level tends to be
unstable, and the acoustic characteristics are likely to be unstable. Therefore, when the above
WPC treatment is performed, dimensional stability can be obtained with almost no loss of the
excellent acoustic characteristics of the sitka spruce material. That is, when WPC conversion
treatment is applied to a square of veneered Sitka spruce to set the polyester content to 31.2%,
its Young's modulus E is about 1, 53 x l O "dyne / am", and the specific gravity は is 1 .23 The
internal friction is 1.85Q-'xlO '.
As the Young's modulus increases but the specific gravity also increases, the speed of sound
υ677) is slightly reduced compared to Sitka spruce that is not subjected to WPC treatment, but
the internal friction is increased and the conventional pulp cone (2, OQ '' It becomes a value close
to x I O '). When the internal friction is up, the attenuation of the amplitude becomes a person,
and the separation of each sound, in other words, the sharpening becomes better, and it is
possible to produce a clear sound without turbidity. It should be noted that although it is
impossible to indicate the resin ratio because it is different depending on the wood species of the
wood and also depending on the part of the wood, the specific gravity is 0.3 when using in a low
humidity and constant place. The extent to which Wl) C is sufficient. On the other hand, when
used in a place where the humidity change is large, high impregnation and high specific gravity
makes the size stable and preferable. Frequency characteristics at 20 Hz to 20 000 fly in a
speaker provided with a flat diaphragm I consisting of a single plate subjected to WPC
processing and a speaker provided with a conventional flat structure of honeycomb structure
having aluminum as a core material − The harmonic distortion was compared and
experimented. The results are as shown in FIG. 4 (present embodiment) and FIG. 5 (conventional
example). As apparent from the comparison of the two figures, the frequency of the speaker
using the flat diaphragm 1 of the present embodiment is such that the Ill of the flat portion
becomes wider and the rising is fast, and wide coverage from bass to treble can be achieved.
Furthermore, the harmonic distortion decreases and the rise of the sound pressure level at low
frequencies becomes sharp. As described above, acoustic characteristics such as frequency
characteristics, harmonic distortion characteristics, and sound pressure levels are superior to
conventional speakers having a flat plate of aluminum honeycomb structure, and at the same
time, dimensional change due to temperature is less likely to occur. . Moreover, since it is wpcized without cavity resonance like a cone speaker, a change in sound due to humidity does not
occur. Moreover, since the flat diaphragm l of the present embodiment is subjected to WPC
processing, dimensional stability is improved, and the acoustic characteristics of natural wood
are degraded such as deformation of the diaphragm due to humidity change and increase in
specific gravity. Since the factor is removed, it is optimal as a speaker diaphragm. The present
invention is not limited to the above embodiment, and the shape of the flat diaphragm may be
circular as shown in FIG. The flat diaphragm 1 'is formed by polymerizing and bonding three
single veneers of a circular plate with a thickness of 0 ° 1 mm, a diameter of 100 mm and WPC
processing so that the grain directions of the veneers cross each other. It is As shown in FIG. 7,
an annular support member 7 made of a key material is adhered and fixed to the back surface of
the flat diaphragm 1, and a substantially conical aluminum armature (see FIG. 7) is attached to
the support member 7 '. (Not shown) is adhesively fixed.
Furthermore, the planar diaphragm is not limited to the above-mentioned circle and square, but
may be formed into a rectangle long in the grain direction, and may be driven using a plurality of
magnets. Further, the material of the diaphragm is not limited to the above-mentioned sitka
spruce or zelkova wood, and a wood material having a specific gravity of 0.25 to 0.8, for
example, pine softwood such as elm pine, various softwoods such as cedar and cypress, Various
hardwoods such as china, tochi and beech may be used. In addition to single speakers,
application to wall speakers is also possible. As is clear from the explanation above, according to
the present invention, according to the present invention, since the thin wood sheet subjected to
WPC processing is used as the flat diaphragm of the speaker, the following effects can be
obtained. (2) Since the wood material is treated with WPC for waterproofing, expansion due to
moisture can be prevented, occurrence of warping and twisting due to environmental changes
can be prevented, and dimensional stability is high. Therefore, in acoustic characteristics such as
frequency characteristics and harmonic distortion, it is possible to obtain acoustic characteristics
superior to that of a plane diaphragm of a honeycomb structure having aluminum or the like as a
core material. ■ WPC conversion processing wood improves internal friction, so it is possible to
get clear and clear sound quality with good sharpness of each sound. (3) When the flat
diaphragm is exposed, it is possible to make the best use of the characteristics of a beautiful
grain material or plate "one material in design," and improve the design as compared with an
aluminum honeycomb or the like. {Circle over (2)} Since the flat diaphragm of the present
invention uses inexpensive and easy-to-manufacture materials, the cost can be reduced, and
design freedom in terms of size and shape is increased.
Brief description of the drawings
FIG. 1 is a front view showing a flat diaphragm according to an embodiment of the present
invention, FIG. 2 is a cross-sectional view of a speaker provided with the flat diaphragm, and FIG.
4 is a graph showing a frequency characteristic-harmonic distortion diagram at 201-1 z to 20
000 Hz of the above-mentioned speaker, and FIG. 5 is a honeycomb structure having a
conventional aluminum core material. A graph showing a frequency characteristic-harmonic
distortion diagram at 20 Hz to 20,000 Hz of a speaker provided with a flat diaphragm, FIG. 6 is a
front view showing a modified example of the flat diaphragm, and FIG. It is a perspective view
which shows the state which adhesively fixed the supporting member to the plane diaphragm of
a figure.
1 ··· Flat diaphragm 2 · · · Edge 3 · · · Metal frame 4 · · · Ferrite magnet 7 · · · Support member 8 · · ·
Armature 9 · Coil winding frame 10 · · · Boil coil 11 · · · · · Lead wire patent applicant Chubu Corn
Manufacturing Co., Ltd. or one agent patent attorney Satoshi Maede Other two people? Fig. 3 面
7 第 4 図 S M M 飲 I IHz l