JPH1175292

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DESCRIPTION JPH1175292
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
electroacoustic transducer which is a flat loudspeaker.
[0002]
2. Description of the Related Art FIG. 1 is a view for explaining an electroacoustic transducer, and
FIG. 1A is a front view of the electroacoustic transducer, and FIG. 1B is a right side sectional view
of the electroacoustic transducer. 2A and 2B are diagrams for explaining the diaphragm
constituting the electroacoustic transducer, and FIG. 2A is a front view of the diaphragm, and FIG.
2B is a diagram of the conventional diaphragm taken along the line A-A '. (C) is a longitudinal
sectional view of the diaphragm of the present invention taken along the line A-A ', and FIG. 3 is a
diagram for explaining the structure of the outer peripheral portion of the diaphragm, FIG. 2A is
a partially enlarged sectional view of the conventional diaphragm shown in FIG. 2B, and FIG. 2B
is a partially enlarged sectional view of the diaphragm of the present invention shown in FIG. It
is.
[0003]
As shown in FIGS. 1 (A) and 1 (B), the full drive thin speaker unit A, which is an electroacoustic
transducer, includes a frame 1, a rear plate 2, a magnet 3, a pole piece 4, a guide pin 5, a voice
coil 6, A diaphragm (diaphragm) 7, a damper 8, and an edge 9 are roughly included.
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By increasing the combination (segment) of the magnet 3, the voice coil 6, and the diaphragm
(diaphragm) 7, it is possible to enlarge the diaphragm area. The dimensions of this speaker unit A
are, for example, 25 mm in thickness, 115 mm in width, and 136 mm in height, and its maximum
amplitude is 10 mmp-p (at 600 gf), and the input resistance is 60 W.
[0004]
The frame 1 is a frame formed by heat-resistant resin such as super heat-resistant ABS resin. The
frame 1 is screwed to a speaker cabinet (not shown) via screw holes 1A to 1D provided at its four
corners (the dimensions of the speaker cabinet are, for example, 60 mm in thickness, 120 mm in
width, 500 mm in height). In addition, the rear plate 2 is firmly screwed and fixed to the entire
rear surface of the frame 1 while four dampers 8 are bonded and fixed to the four corners on the
front side (the diaphragm 7 side). The four dampers 8 support the four corners of the diaphragm
7 in a freely vibrating manner.
[0005]
The rear plate 2 is a base plate which is formed of a metal plate such as iron and fixes the
longitudinal magnets 3 having the longitudinal pole pieces 4 adhered to the upper surface
thereof. A large number of air removal slits and holes are provided on the entire rear side of the
rear plate 2, and a pair of speaker terminals connected to the start end and the end of the voice
coil 6 are provided (both not shown). On the other hand, on the front side (the diaphragm 7 side)
of the rear plate 2, both ends of the longitudinal pole piece 4 to which the longitudinal magnet 3
is adhered are screwed and fixed by the guide pins 5 as described above. In the illustrated
example, seven longitudinal magnets 3 are juxtaposed parallel to one another.
[0006]
The magnet 3 is a magnet formed by sintering a ferrite such as strontium ferrite. Then, as
described above, when the magnet 3 is fixed to the front side (the diaphragm 7 side) of the rear
plate 2, one surface of the magnet 3 in contact with the rear plate 2 becomes an N pole, and the
magnet in contact with the pole piece 4. The magnet 3 is magnetized such that the other surface
(the diaphragm 7 side) of 3 is the S pole. The dimensions of the magnet 3 are, for example, 80
mm in length, 5 mm in width, and 8 mm in thickness.
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[0007]
The pole piece 4 is formed of a metal plate such as iron and has a pair of screw holes for fixing
the magnet 3 to the rear plate 2 at both ends thereof. The voice coil 6 is a coated copper wire
sequentially wound around the tops 7a1 to 7a7 constituting the diaphragm 7. As described
above, the beginning and end (not shown) of the voice coil 6 are respectively connected to a pair
of speaker terminals provided on the rear plate 2.
[0008]
The diaphragm (diaphragm) 7 is integrally molded using a polyimide (PI) film which withstands
the heat generation of the voice coil 6 and has excellent mechanical characteristics as a
diaphragm. Further, in order to reduce the weight of the diaphragm 7, it is necessary to make the
diaphragm itself as thin as possible, but the thickness of the diaphragm 7 used here is 75 μm. As
described above, the diaphragm 7 is attached to the magnet 3 and the pole piece 4 fixed on the
rear plate 2, and the periphery thereof is positioned and fixed to the frame 1 by the edge 9 made
of urethane or the like. The specific configuration of the diaphragm 7 will be described later.
[0009]
The damper 8 supports the diaphragm 7 in a vibrating manner, and is made of a thermoplastic
resin such as polycarbonate, which is a substance having high spring resistance and high impact
resistance and heat resistance. In order to obtain a maximum amplitude of 10 mmp-p in a limited
space, a multistage plate spring structure is used. Since the dampers 8 are fixed to the four
corners of the frame 1, the displacement is 10 gm-p at 150 gf per damper 8. This load is received
by four end support beam structures. Further, the tensile load in the surface direction of the
diaphragm 7 is received by the connecting portion of the central portion of the damper 8. And
the beam structure is arranged in a fan shape to save space.
[0010]
Now, as shown to FIG. 2 (A) and (B), the diaphragm 7 mentioned above is comprised from several
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peak part 7a1-7a7, the plane part 7b, and the outer peripheral part 7c, These peak part 7a1-7a7,
a plane The portion 7 b and the outer peripheral portion 7 c are integrally molded. Further, the
tops 7a1 to 7a7 are formed in a curved surface convex shape (protrusion) from the back side
(rear plate 2 side) of the vibrating plate 7 to the front side, and these tops 7a1 to 7a7 are
integrated as the main vibration portion 7A. It is molded. Here, the front side of the vibrating
plate 7 is the front side of the full drive thin speaker unit A. The seven crests 7a1 to 7a7 are
arranged in parallel in the longitudinal direction of the diaphragm 7 (in the vertical direction in
FIG. 1A and FIG. 2A), and the sectional shape of each crest 7a1 to 7a7 is Except for the both
ends, in FIG. 2 (B), it is a convex shape (蒲鉾 shape, semi-cylindrical shape) longitudinally cut by
the AA 'line. An outer peripheral portion 7c is formed around the main vibrating portion 7A.
[0011]
Thus, by supplying an audio signal (drive current) between the pair of speaker terminals of the
full-surface drive thin speaker unit A configured as described above, the top portions 7a1 to 7a7
of the diaphragm 7 are uniformed back and forth with respect to the paper surface. It will vibrate
on the entire surface.
[0012]
By the way, as described above, since the diaphragm (diaphragm) 7 is made as thin as possible in
order to reduce the weight and integrally molded with a polyimide film, after the molding It is
extremely difficult to keep the thickness of each part of the diaphragm 7 uniform.
In particular, the direction perpendicular to the longitudinal direction (FIGS. 1A and 2) is more
than the thickness of the seven crests 7a1 to 7a7 in the longitudinal direction (vertical direction
in FIGS. 1A and 2A). In (A), the defect that the thickness in the left and right direction becomes
thin occurs. For this reason, the mechanical strength in the short direction of each top part 7a17a7 was inferior. As a result, when an audio signal (drive current) having a relatively large level
is supplied to the full-surface drive thin speaker unit A, the top portions 7a1 to 7a7 do not
integrally vibrate as the main vibration portion 7A. Each of the tops 7a1 to 7a7 vibrates
uniformly without vibrating, and there is a risk that adjacent tops collide with each other to
generate an abnormal sound due to a divided vibration (so-called "flickering noise").
[0013]
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As a result, in the above-described conventional full-field drive thin speaker unit A, a dip of up to
40 dB occurs in the sound pressure particularly in the middle range (about 800 Hz to about 4
kHz), which is far greater than the other tone ranges. Level fluctuation is large. For this reason,
flat sound pressure frequency characteristics could not be obtained in the midrange.
[0014]
In order to solve the problem that the present invention can not obtain flat sound pressure in the
entire frequency band, in particular, by making the rigidity of the outer peripheral portion 7c of
the diaphragm 7 higher than the rigidity of the respective top portions 7a1 to 7a7. An object of
the present invention is to provide an electroacoustic transducer in which generation of
unnecessary resonance in the outer peripheral portion 7c is reduced to suppress acoustic
distortion even when the top portions 7a1 to 7a7 are integrally vibrated as the main vibration
portion 7A.
[0015]
SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present
invention provides an electroacoustic transducer having the following constitution (1).
[0016]
(1) As shown in FIG. 2 (C) and FIG. 3 (B), the entire surface of the flat diaphragm 70 formed of a
plurality of longitudinal projections (top portions) 7a1 to 7a7 arranged in parallel is driven. It is
an electroacoustic transducer (full surface drive thin speaker unit) AA, and the outer peripheral
portion 70c of the diaphragm 70 is made higher than the rigidity of the protrusions 7a1 to 7a7
as a bent structure (folded portion a). An electroacoustic transducer characterized by
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION An electroacoustic transducer according to
the present invention will be described below with reference to the drawings.
2 (C) is a longitudinal sectional view of the diaphragm of the present invention taken along the
line A-A ', and FIG. 3 (B) is a partially enlarged sectional view of the diaphragm of the present
invention shown in FIG. is there.
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The same components as those described above are denoted by the same reference numerals,
and the description thereof is omitted.
[0018]
The electroacoustic transducer (full surface drive thin speaker unit) AA of the present invention
has a flat surface of the diaphragm 7 at the edge 9 as shown in FIGS. 2 (B), (C), 3 (A) and 3 (B). In
contrast to the conventional one where the outer peripheral portion 7c is supported, the non-flat
outer peripheral portion 70c having the bent portion a is supported at the edge 9, and the elastic
force of the bent portion a of the outer peripheral portion 70c The diaphragm 70 is used to
further increase the rigidity.
[0019]
Specifically, as shown in FIGS. 1A and 1B, the full drive thin speaker unit AA, which is an
electroacoustic transducer according to the present invention, includes a frame 1, a rear plate 2,
a magnet 3, a pole piece 4, The guide pin 5, the voice coil 6, the diaphragm (diaphragm) 70, the
damper 8, and the edge 9 are generally configured.
[0020]
The diaphragm (diaphragm) 70 is integrally molded using a polyimide (PI) film that withstands
the heat generation of the voice coil 6 and has excellent mechanical characteristics as a
diaphragm.
As described above, the diaphragm 70 is attached to the magnet 3 and the pole piece 4 fixed on
the rear plate 2, and the periphery thereof is positioned and fixed to the frame 1 by the edge 9
made of urethane or the like.
[0021]
As shown in FIGS. 2A, 2C, and 3B, the diaphragm 70 includes a plurality of tops 7a1 to 7a7, a flat
portion 7b, and an outer peripheral portion 70c having a bent portion a. .
The outer peripheral portion 70 c is provided with a bent portion a at a portion in contact with
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the edge 9 in order to increase its rigidity.
The bent portion a is formed at the time of integral molding of the diaphragm 70. The bent
portion a shown in the figure forms one step, but in order to obtain the required rigidity, the bent
portion a may be formed with a plurality of steps (two steps, three steps,...) . Incidentally, the
rigidity (Young's modulus) of the flat outer peripheral portion 70c described above is 290 kgf /
mm 2.
[0022]
Further, the bent portion a of the outer peripheral portion 70c is formed in a frame shape with
one line around the entire periphery of the diaphragm 70, but the position where the bent
portion a is provided is the entire periphery of the diaphragm 70 It is not necessary to form over
a distance, and in order to obtain the required rigidity, it is possible to provide at any position of
the outer periphery 70c as needed, such as only the left and right side surfaces of the diaphragm
70 or only the upper and lower surfaces thereof. It is.
[0023]
Furthermore, although the bent portion a of the outer peripheral portion 70c is provided in a
frame shape with one line of uniform thickness around the diaphragm 70, in order to obtain the
required rigidity, the thick portion of the bent portion a In order to obtain the required rigidity
without making the thickness uniform, any thickness may be used, such as a shape in which
small semicircular spheres are linearly connected, or a shape in which bending lines are
continuous.
[0024]
Furthermore, as described above, in order to obtain the rigidity required for the outer peripheral
portion 70c, even if the number of steps of the bent portion a, the installation position of the
bent portion a, and the thickness of the bent portion a are combined. It goes without saying that
it is good.
[0025]
Thus, the rigidity of the outer peripheral portion 70c is further increased by providing the bent
portion a in the outer peripheral portion 70c of the diaphragm 70, so that the sound between the
pair of speaker terminals of the full drive thin speaker unit AA configured as described above By
supplying a signal (drive current), unnecessary resonance (divided vibration) occurs in the outer
peripheral portion 70c which occurs when the respective top portions 7a1 to 7a7 of the
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diaphragm 7 vibrate uniformly all over the front and back of the drawing sheet. Can be reduced
to suppress acoustic distortion.
[0026]
According to the electro-acoustic transducer of the present invention having the abovementioned structure, the projections are integrally vibrated, in particular, by making the outer
periphery of the diaphragm as a bending structure and further increasing the rigidity of the outer
periphery. It is possible to provide an electro-acoustic transducer in which acoustic distortion is
suppressed by reducing the occurrence of unnecessary resonance (divided vibration) in the outer
peripheral portion.
[0027]
Brief description of the drawings
[0028]
1 is a diagram for explaining an electro-acoustic transducer.
[0029]
2 is a diagram for explaining the diaphragm constituting the electro-acoustic transducer.
[0030]
3 is a diagram for explaining the structure of the outer peripheral portion of the diaphragm.
[0031]
Explanation of sign
[0032]
7, 70 Diaphragms 7a1 to 7a7 Tops (projections) 7c, 70c Outer circumferences a Bends A, AA
Full-surface drive thin speaker unit (electro-acoustic transducer)
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