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JPH1141690

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DESCRIPTION JPH1141690
[0001]
TECHNICAL FIELD The present invention relates to an electrodynamic speaker.
[0002]
2. Description of the Related Art An electrodynamic speaker is shown in FIGS. 12 and 13. FIG. In
this case, a disk-shaped mounting body 41 made of lightweight aluminum, synthetic resin or the
like is fitted and fixed to the upper end portion of the voice coil bobbin 40, and the mounting
body 41 is a general-purpose small-sized acceleration sensor 42. Is embedded.
[0003]
The acceleration sensor 42 detects acceleration of a vibration system, and has a case 44 made of
aluminum, and an amplifier unit (piezoelectric circuit unit) formed of an acceleration pickup, a
field effect transistor (FET), and the like. The amplifier section is incorporated in the case 44 and
shielded as it has a very high impedance, and generates a voltage proportional to the acceleration
of the vibration system as an output signal. This output signal is fed back to the drive amplifier of
the speaker via the output line to perform motional feedback (MFB) operation.
[0004]
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1
By the way, in order to prevent the acceleration sensor 42 and the mounting body 41 from
affecting the vibration of the vibration system and to perform the MFB operation well, the
acceleration sensor 42 and the mounting body 41 can be reduced in weight and mounted. It is
necessary to vibrate the body 41 integrally with the vibration system of the speaker.
[0005]
Then, in order to vibrate the mounting body 41 integrally with the vibration system of the
speaker, for example, the rigidity (strength) of the mounting body 41 is increased, and the
amount of deformation of the mounting body 41 in the back and forth direction at the time of
vibration of the vibration system. Needs to be reduced.
[0006]
However, in the case of a speaker in which the inner diameter of the voice coil is 30 mm or more,
if the mounting body 41 is formed of metal such as aluminum or synthetic resin, the rigidity and
weight of the mounting body 41 can not be balanced. A problem arises.
[0007]
That is, when the thickness of the mounting body 41 is reduced to reduce the weight of the
mounting body 41, it is possible to reduce the possibility of adversely affecting the vibration of
the vibration system.
However, the rigidity of the mounting body 41 is weakened, and the amount of deformation in
the front-rear direction of the mounting body 41 becomes large when the vibration system
vibrates, whereby the mounting body 41 resonates at a frequency of 3000 Hz. As a result, a large
peak 46 occurs in the output voltage level of the acceleration sensor 42, which causes a problem
that the MFB can not be performed well.
[0008]
Also, contrary to the above, when the thickness of the mounting body 41 is increased, the rigidity
of the mounting body 41 can be made large, and the amount of deformation of the mounting
body 41 in the front-rear direction becomes small when the vibration system vibrates. The
mounting body 41 is less likely to resonate, and hence the output voltage level of the
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2
acceleration sensor 42 does not have a large peak, and the MFB operation can be performed well.
However, since the weight of the mounting body 41 is increased, the vibration of the vibration
system is adversely affected, and there is a problem that the cost is also increased.
[0009]
By the way, although the vibration system of the speaker is composed of the voice coil bobbin
40, the voice coil 48, the diaphragm 49, the damper 50, etc., in the case of the speaker having an
inner diameter of 30 mm or more, the weight of the vibration system is It will be about 10 g.
On the other hand, the weight of the small acceleration sensor 42 is 2 to 3 g, and as described
above, when the thickness of the mounting body 41 is increased and the rigidity thereof is
increased, The weight also becomes about 2 to 3 g, and the weight of the acceleration sensor 42
and the mounting body 41 becomes considerably large compared to the weight of the vibration
system.
[0010]
An object of the present invention is to provide an electrodynamic speaker that can solve the
above problems.
[0011]
SUMMARY OF THE INVENTION In order to achieve the above object, the feature of the present
invention is characterized in that an acceleration sensor for detecting an acceleration of a
vibration system is provided in the vibration system via a mounting body. In the electric speaker,
the mounting body is a flexible arc-shaped wiring substrate having a conductive layer on both
sides and having flexibility, and the mounting body is mounted along the circumferential
direction on the voice coil bobbin, and acceleration is provided. The sensor has a wiring pattern
formed on the surface of the mounting body opposite to the voice coil bobbin and a circuit
element mounted on the wiring pattern.
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3
The mounting body may be substantially cylindrical. In addition, the mounting body may be in
close contact with the voice coil bobbin over substantially the entire length in the circumferential
direction. Furthermore, the mounting body may be bonded to the voice coil bobbin. Further, in an
electrodynamic speaker including an acceleration sensor for detecting acceleration of a vibration
system, the voice coil bobbin is a wiring substrate having a conductive layer on both sides and
having flexibility, and the acceleration sensor is a voice coil bobbin There are also cases where it
has a wiring pattern formed on the circuit board and a circuit element attached to the wiring
pattern. Furthermore, the voice coil bobbin may have an insulating plate in which conductive
layers are formed on both sides, and the mounting portion of the voice coil in the voice coil
bobbin may be only the insulating plate. The acceleration sensor may include an amplifier unit
that outputs a voltage according to the acceleration of the vibration system, and the amplifier
unit may include a shield that shields the radially inner side of the speaker.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION A first example of the embodiment of the
present invention will be described below with reference to the drawings in FIGS. 1 to 6. FIG. 1
shows a circular speaker, which has a bowl shape projecting backward Frame 2 having an
opening 1 in the center, a ring-shaped upper plate 3 fixed to the rear surface of the frame 2, a
ring-shaped magnet 4 fixed to the rear surface of the upper plate 3, and a rear surface of the
magnet 4 The lower plate 5 is fixed to the center pole 8 and the magnetic gap 7 is formed
between the center pole piece 6 and the upper plate 3. The voice coil bobbin 9 is inserted into
the magnetic gap 7 and protrudes upward. The voice coil 10 wound around the outer
circumferential surface of the voice coil 10 and inserted into the magnetic gap 7, the mounting
body 11 provided on the inner peripheral surface of the voice coil bobbin 9, and the acceleration
provided on the mounting body 11 Sensor 12, a damper 13 and a diaphragm 14 provided on the
outer periphery of the voice coil bobbin 9, and a dust cap 15 mounted on the inner periphery of
the diaphragm 14 and externally fitted on the upper end of the voice coil bobbin 9. .
[0013]
As shown in FIGS. 2 to 4 and 6, the voice coil bobbin 9 has a thin cylindrical shape and is made
of paper, synthetic resin or the like, and the voice coil bobbin 9, the voice coil 10, and the
diaphragm 14. The vibration system of the speaker is configured by (and the damper 13 and the
dust cap 15).
[0014]
The mounting body (mounting means) 11 is a wiring substrate such as a glass epoxy double-
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4
sided board, and is formed on the both sides of the insulating plate 17 made of glass epoxy resin
or the like and electrolytic copper foil etc. A layer (conductive portion, wiring layer, wiring
portion) 18 is provided.
The thickness of the mounting body 11 is reduced to be substantially the same as the thickness
of the voice coil bobbin 9 or smaller than the thickness of the voice coil bobbin 9, and the
thickness thereof is, for example, about 0.4 mm. .
[0015]
The mounting body 11 is formed into an elongated plate shape and has flexibility (elastically
deformable property), and the curvature radius smaller than that of the voice coil bobbin 9 when
the plate thickness is thin (in the normal case) After being elastically deformed in an arc shape
((approximately) cylindrical shape) having the above and fitted in the upper portion of the voice
coil bobbin 9, it is deformed so that the radius of curvature becomes large by its elastic restoring
force (elastic force) Do.
Thus, the mounting body 11 is in a substantially cylindrical shape, and is in close contact with
the inner circumferential surface of the voice coil bobbin 9 in the circumferential direction over
(almost) the entire circumference (entire circumferential length) without gaps. Contact) to be
held in this state.
[0016]
When the plate thickness of the mounting body 11 is thick, first, it is formed into an arc shape
having a curvature radius larger than that of the voice coil bobbin 9 by heat treatment, but at this
time, a mold having an arc shaped clearance is used. The mounting body 11 is bent into an arc
shape by using the mounting body 11 in the formation gap and heating to 200 to 250 ° C. After
this processing, in the same manner as described above, the mounting body 11 is fitted in the
upper portion of the voice coil bobbin 9 while being elastically deformed so as to reduce the
radius of curvature.
[0017]
Then, the outer peripheral surface of the mounting body 11 is bonded to the inner peripheral
08-05-2019
5
surface of the voice coil bobbin 9 through an adhesive or the like over the (substantially) entire
circumference (total length in the circumferential direction) on the inner peripheral surface of
the voice coil bobbin 9 As described above, since the mounting body 11 is held by the voice coil
bobbin 9 by an elastic restoring force, a means for temporarily fixing the mounting body 11 to
the voice coil bobbin 9 is unnecessary, and the mounting body 11 can be easily attached to the
voice coil bobbin 9 It can be bonded at low cost in a short time.
[0018]
In addition, although the attachment body 11 is made into substantially cylindrical shape as
mentioned above, as this "substantially cylindrical shape" is shown in FIG. 2, the both ends of the
attachment body 11 contact without gap, without overlapping. This is a concept including a
completely cylindrical state, a state in which both ends of the mounting body 11 overlap, and a
state in which a slight gap is formed between the two ends of the mounting body 11.
In the case where a cylinder having the same radius of curvature as that of the mounting body
11 is assumed, the above slight gap means, for example, about 1⁄5 of the length of the
circumference of the cylinder.
[0019]
The mounting body 11 may have an arc shape instead of the substantially cylindrical shape as
described above, but if the mounting body 11 is substantially cylindrical, the adhesion area or
mounting area (adhesion area) of the mounting body 11 to the voice coil bobbin 9 is , And the
attachment (adhesion) strength of the mounting body 11 to the voice coil bobbin 9 can be
increased, which is preferable. Further, the mounting body 11 may be mounted not on the inner
peripheral surface of the voice coil bobbin 9 but on the outer peripheral surface. In this case, the
following wiring pattern is formed on the outer peripheral surface of the mounting body 11, and
the curvature radius of the mounting body 11 is smaller than that of the voice coil bobbin 9
before the mounting body 11 is attached to the voice coil bobbin 9. When the mounting body 11
is fitted onto the voice coil bobbin 9, the mounting body 11 is held by the voice coil bobbin 9 by
its elastic restoring force.
[0020]
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6
Further, in the illustrated example, the mounting body 11 is slightly protruded upward from the
voice coil bobbin 9 and, for example, as shown by the phantom line in FIG. 4 and in FIG. When
mounting on the voice coil bobbin 9, a U-shaped positioning tool 20 may be provided to position
the mounting body 11 in the front-rear direction with respect to the voice coil bobbin 9. The
positioning tool 20 is disposed three or more on the mounting body 11 at equal intervals in the
circumferential direction (substantially), and is inserted and fixed (inserted) to the front end
portion of the mounting body 11. And abut. The front end of the mounting body 11 and the front
end of the voice coil bobbin 9 may be matched in the front-rear direction without the positioning
tool 20.
[0021]
The acceleration sensor 12 detects the acceleration of the vibration system of the speaker, and a
wiring pattern (circuit pattern, wiring portion) formed by printing (printing) or the like in the
circumferential direction (approximately) central portion of the inner peripheral surface of the
mounting body 11 And 22), circuit elements (elements, circuit parts, (components) parts)
provided in the wiring pattern 22, and the wiring pattern 22 and a shield body 23 covering the
circuit elements.
[0022]
As the circuit elements, an acceleration pickup 26, a field effect transistor (FET) 25, and other
parts (circuit elements) 27 and 28 such as resistors are used.
An amplifier unit (piezoelectric circuit unit, sensor unit) 29 configured to output a voltage
proportional to the acceleration of the vibration system of the speaker is configured by the FET
25 and the components 27 and 28 and the like. The wiring pattern 22 is connected to four lines
30 including positive and negative power supply lines and two output lines, and these lines 30
are connected to the drive amplifier 33 of the speaker via the sockets 31 and 32, etc. When the
output signal from the amplifier unit 29 is fed back to the drive amplifier 33, a motional
feedback (MFB) function is performed. The four wires 30 are usually collected, and the dust cap
15, the diaphragm 14, the frame 2 and the like are inserted and led to the outside of the speaker.
[0023]
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7
The amplifier unit 29 has a very high impedance, so the radially inner side of the speaker is
shielded by the shield body 23 made of a conductive material such as aluminum. The shield body
23 is a case made of a conductive material such as aluminum or a tape or the like. The radially
outer side of the speaker in the amplifier unit 29 is shielded by the outer conductive layer 18 of
the mounting body 11 and does not need to be shielded separately, so that the speaker can be
assembled easily and in a short time. .
[0024]
Note that FIGS. 1 to 6 (as well as the other drawings) are simplified for the convenience of the
description, and the dimensions are also different from the actual ones. For example, the wiring
pattern 22 shown in FIG. 2 and FIG. 3 and the circuit element attached thereto are different from
the real thing. Moreover, in FIG. 3, the acceleration sensor 12 which removed the shield body 23
is shown.
[0025]
In the first example, the acceleration sensor 12 and the mounting body 11 do not affect the
vibration of the vibration system, and the weight of the acceleration sensor 12 and the mounting
body 11 is reduced in order to perform the MFB operation well. At the same time, it is necessary
to vibrate the mounting body 11 integrally with the vibration system of the speaker.
[0026]
Then, in order to vibrate the mounting body 11 integrally with the vibration system of the
speaker, A.
B. reducing the amount of deformation of the mounting body 11 in the front-rear direction
during vibration of the vibration system; C. increasing the mounting strength of the mounting
body 11 to the voice coil bobbin 9; It is necessary to increase the strength of the voice coil
bobbin 9 and the like.
[0027]
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8
First, considering the weight of the acceleration sensor 12 and the mounting body 11, the
mounting body 11 can be reduced in weight because it is used as a wiring substrate instead of
the aluminum disk as in the prior art. Further, as described above, it is not necessary to
separately provide the wiring substrate for the acceleration sensor 12 as a wiring substrate as
described above, and the weight of the acceleration sensor 12 can be reduced accordingly.
[0028]
Next, when the vibration state of the acceleration sensor 12 and the attachment body 11 is
considered, it is as follows. Since the mounting body 11 is substantially cylindrical or arc-shaped
and attached to the inner peripheral surface of the voice coil bobbin 9 along the circumferential
direction (in a close contact), the mounting body 11 is vibrated when the vibration system of the
speaker vibrates. There is no significant deformation in the longitudinal direction. The outer
peripheral surface of the substantially cylindrical or arc-shaped mounting body 11 is formed
along the circumferential direction on the inner peripheral surface of the voice coil bobbin 9, and
the mounting body 11 is extended over the entire circumferential direction (substantially) Since
the voice coil bobbin 9 is closely attached (bonded) to the inner peripheral surface of the voice
coil bobbin 9, the attachment area (adhesive area) of the attachment body 11 to the voice coil
bobbin 9 can be made large, and the attachment strength of the attachment body 11 to the voice
coil bobbin 9 It can be great. Since the mounting body 11 is attached to the voice coil bobbin 9 in
the above-described form, the strength of the voice coil bobbin 9 itself can also be improved.
According to the above, the mounting body 11 can be vibrated substantially integrally with the
voice coil 10.
[0029]
As described above, the acceleration sensor 12 and the mounting body 11 can be reduced in
weight, and the influence exerted on the vibration system of the speaker can be reduced. In
addition, since the mounting body 11 can be vibrated substantially integrally with the voice coil
10, resonance of the mounting body 11 can be suppressed, and a large peak does not occur in
the output voltage level of the acceleration sensor 12, and the MFB operation is favorably
performed. It can do.
[0030]
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9
7 to 10 show a second example of the embodiment of the present invention, in which the voice
coil bobbin 9 itself is a (substantially) cylindrical substrate for wiring, and the voice coil bobbin 9
is an insulating plate 17; A conductive pattern 18 is provided on both sides of the front portion
of the insulating plate 17, and a wiring pattern 22 is formed in the circumferential center of the
rear portion of the conductive layer 18 on the inner peripheral side. The rear portion of the voice
coil bobbin 9 is constituted only by the insulating plate 17, and the voice coil 10 is provided at
the rear portion. For example, in the voice coil 10, when the inner diameter is 50.5 mm, the
length of the circumference is 159.6 mm, the length of the front portion where the conductive
layer 18 is formed is 30 mm, and the rear portion consists only of the insulating plate 17 Is 20
mm in length.
[0031]
In the second example, the voice coil bobbin 9 itself is used as a wiring substrate, the voice coil
bobbin 9 is provided with the acceleration sensor 12, and the voice coil bobbin 9 and the
conventional mounting body 11 are integrated. The increase in weight due to the mounting
means (conventional mounting body 11) to the system can be reduced (extremely) and the
influence of the equipment of the acceleration sensor 12 on the vibration system of the speaker
can be reduced (extremely) Can be suppressed (extremely), so that the output voltage level of the
acceleration sensor 12 accompanying the attachment means does not have a large peak, and the
MFB action can be performed well. Further, as described above, since the voice coil bobbin 9 and
the mounting body 11 are integrated and the number of parts is reduced, the speaker can be
assembled easily at a low cost and in a short time.
[0032]
Next, an experiment was conducted on the relationship between the output signal level from the
acceleration sensor and the frequency, with the implementation of the first example of the
embodiment of the present invention as an example. In the embodiment, the diameter of the
voice coil bobbin is 50.5 mm, and the mounting body is a glass epoxy double-sided board, the
total length is 145 mm, the width (length in the front-rear direction of the speaker) is 12 mm,
and the thickness is 0. It was 4 mm.
[0033]
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10
FIG. 11 is an experimental result. Compared with the conventional experimental result in FIG. 14,
in the prior art, the mounting body resonates at a frequency of around 3000, and a large peak is
generated in the output signal level of the acceleration sensor. In the example, the above peak is
small.
[0034]
As described above in detail, according to the present invention, the weight of the acceleration
sensor can be reduced, and the increase in weight due to the mounting means of the acceleration
sensor to the vibration system can also be reduced. The effect of the vibration system on the
vibration system can be reduced, and the resonance caused by the mounting means can be
suppressed, and the motional feedback (MFB) operation can be performed well.
[0035]
In particular, according to claim 1, since the mounting body, which is the mounting means for
the vibration system of the acceleration sensor, can be held on the voice coil bobbin by elastic
restoring force, the means for temporarily fixing the mounting body to the voice coil bobbin is
unnecessary. The mounting body can be attached to the voice coil bobbin easily and in a short
time and at low cost.
In claims 2 and 3, the mounting area of the mounting body to the voice coil bobbin can be made
large, and the mounting strength of the mounting body to the voice coil bobbin and the strength
of the voice coil bobbin itself can be made large, and the resonance of the mounting body is
suppressed accordingly It can do, and can do MFB action better. According to the fifth aspect of
the present invention, the increase in weight due to the attachment means of the acceleration
sensor to the vibration system can be reduced, and the influence of the acceleration sensor
equipment on the vibration system of the speaker can be further reduced. Therefore, the MFB
action can be performed better. Further, as described above, since the voice coil bobbin and the
mounting body are integrated and the number of parts is reduced, the speaker can be assembled
easily and in a short time at low cost. According to the sixth aspect of the present invention, the
shield on the radially outer side of the speaker in the amplifier portion of the acceleration sensor
can be performed by the mounting body or the conductive layer on the outer peripheral side of
the voice coil bobbin. Therefore, the speaker can be easily and quickly assembled.
[0036]
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11
Brief description of the drawings
[0037]
1 is a longitudinal side sectional view showing a first example of the embodiment of the present
invention.
[0038]
2 is a perspective view of the main part of FIG.
[0039]
3 is an exploded perspective view of FIG.
[0040]
4 is a cross-sectional view taken along line AA of FIG.
[0041]
5 is a plan view of the positioning tool of FIG.
[0042]
6 is a cross-sectional view taken along the line B-B in FIG.
[0043]
7 is a longitudinal side sectional view showing a second example of the embodiment of the
present invention.
[0044]
8 is a perspective view of the main part of FIG.
[0045]
9 is a development view of the main part of FIG.
08-05-2019
12
[0046]
10 is a cross-sectional view taken along the line CC in FIG.
[0047]
It is a graph which shows the relationship between the output voltage level of FIG. 11 Example,
and a frequency.
[0048]
12 is a vertical side sectional view showing a conventional example.
[0049]
13 is an exploded perspective view of the main part of FIG.
[0050]
14 is a graph showing the relationship between the output voltage level and the frequency of the
conventional example.
[0051]
Explanation of sign
[0052]
9 voice coil bobbin 10 voice coil 11 mounting body 12 acceleration sensor 13 damper 14
diaphragm 15 dust cap 17 insulating plate 18 conductive layer 22 wiring pattern 23 shield 25
FET 26 acceleration pickup 27 28 parts 29 amplifier section
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