JP2018182387

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DESCRIPTION JP2018182387
Abstract: To improve the bass characteristic of a speaker. A speaker 10B includes n diaphragms
31a to 31e and (n-1) sealed spaces 22a to 22d. The i-th sealed space faces the first surface of the
i-th diaphragm and the second surface of the (i + 1) -th diaphragm. The diaphragms 31a to 31e
are driven such that the volumes of all the enclosed spaces 22a to 22d become substantially
constant. The (i + 1) th diaphragm may be arranged such that the second surface faces in
substantially the same direction as the first surface of the ith diaphragm, adjacent to the side of
the ith diaphragm It may be arranged. [Selected figure] Figure 5
スピーカ
[0001]
The present invention relates to a speaker.
[0002]
Patent Documents 1 and 2 disclose a speaker having improved bass characteristics by combining
a plurality of speaker units.
[0003]
Patent No. 5719718 Patent No. 5719958
[0004]
An object of the present invention is to further improve the bass characteristic of a speaker.
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[0005]
The speaker may include n diaphragms and (n-1) space definition parts.
n may be a natural number of 3 or more.
The ith space definition part may define a sealed space facing the first surface of the ith
diaphragm and the second surface of the (i + 1) th diaphragm.
i may be a natural number less than n.
The diaphragm may be driven such that the volume of all the enclosed spaces is substantially
constant. The (i + 1) th diaphragm may be arranged such that the second surface faces in
substantially the same direction as the first surface of the i-th diaphragm, and is adjacent to the
side of the i-th diaphragm It may be arranged. The diaphragms may be arranged substantially in
line. n may be an odd number or a product of p and q. p and q may be two or more natural
numbers.
[0006]
According to the speaker, since the volume of all the enclosed spaces is substantially constant,
the back pressure of all the diaphragms is cancelled. As a result, since the lowest resonance
frequency is lowered, the bass characteristic is improved. Since there is at least one enclosed
space between the enclosed space defined by the first space definition and the enclosed space
defined by the (n-1) th space definition, the volume of each enclosed space is The first and n-th
diaphragms can be separated without increasing the size. If the first diaphragm and the n-th
diaphragm are separated, the sound emitted from the second surface of the first diaphragm
exposed to the outside and the first surface of the n-th diaphragm The pressure can be prevented
from canceling each other. Therefore, there is no need to provide an element such as a baffle
plate or an enclosure for preventing cancellation of the sound pressure radiated from the
diaphragm. If the volume of each enclosed space is small, the time taken for sound waves to be
transmitted in the enclosed space can be almost ignored, so that the back pressure of the
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diaphragm can be reliably canceled. Arranging the (i + 1) th diaphragm so that the second
surface faces in substantially the same direction as the first surface of the ith diaphragm, and / or
adjacent to the side of the ith diaphragm By arranging them, the volume of the i-th sealed space
can be reduced. If the diaphragms are arranged substantially in a straight line, the distance
between the first diaphragm and the n-th diaphragm can be maximized. If n is an odd number,
the directions in which the sound pressure is radiated to the outside from the first and n-th
diaphragms are different, so that the sound pressures can be prevented from canceling each
other. If n is the product of p and q, then p drivers for driving the diaphragm may be connected
in parallel to form q parallel circuits, and the parallel circuits may be connected in series.
Alternatively, q drivers may be connected in series to form p series circuits, and the series
circuits may be connected in parallel. Thereby, the combined impedance of the drive circuit is q /
p times the impedance of the driver. If p and q are the same or nearly the same, then the
combined impedance of the drive circuit will be the same or nearly the same as the driver's
impedance, so with an amplifier circuit designed to drive one driver , Drive circuit can be driven.
Therefore, even if the number of drive circuits is increased, it is not necessary to increase the
number of amplifier circuits.
[0007]
The front view which shows an example of a speaker. The II-II end elevation which shows the
said speaker. The front view which shows another example of a speaker. The rear view which
shows the said speaker. The VV end elevation which shows the said speaker. The circuit diagram
which shows an example of a circuit structure of a speaker. The circuit diagram which shows
another example of a circuit structure of a speaker.
[0008]
The speaker 10A according to the embodiment includes a main body 12 and five speaker units
13a to 13e, as shown in FIGS. 1 and 2. The main body 12 has a shape in which four boxes 21a to
21d are combined. The speaker units 13a to 13e are all identical, fixed to the holes provided in
the main body 12, and arranged in parallel and in a straight line. The front surface (second
surface) of the diaphragm 31a of the speaker unit 13a is exposed to the outside of the main body
12, and the rear surface (first surface) faces the internal space 22a of the box 21a. The
diaphragm 31b of the speaker unit 13b is disposed adjacent to the side of the diaphragm 31a of
the speaker unit 13a, and the back surface (second surface) faces the internal space 22a of the
box 21a, and the surface (first surface) Faces the internal space 22b of the box 21b. The
diaphragm 31c of the speaker unit 13c is disposed adjacent to the side of the diaphragm 31b of
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the speaker unit 13b, and the front surface (second surface) faces the internal space 22b of the
box 21b, and the rear surface (first surface) Faces the internal space 22c of the box 21c. The
diaphragm 31d of the speaker unit 13d is disposed adjacent to the side of the diaphragm 31c of
the speaker unit 13c, and the back surface (second surface) faces the internal space 22c of the
box 21c, and the surface (first surface) Faces the internal space 22 d of the box 21 d. The
diaphragm 31e of the speaker unit 13e is disposed adjacent to the side of the diaphragm 31d of
the speaker unit 13d, and the surface (second surface) faces the internal space 22d of the box
21d, and the surface is outside the main body 12 It is exposed. The internal spaces 22a to 22d
(sealed space) are enclosed by the boxes 21a to 21d (space defining part) and the diaphragms
31a to 31e and sealed.
[0009]
The diaphragms 31a to 31e are driven by the same signal. However, the diaphragms 31b and
31d are driven by a signal whose phase is opposite to that for driving the diaphragms 31a, 31c
and 31e. Therefore, when the diaphragm 31a moves to the front side, the diaphragm 31b moves
to the back side. Thus, the volume of the inner space 22a is always kept constant. Similarly, the
volumes of the internal spaces 22b to 22d are always kept constant. Since the volumes of the
internal spaces 22a to 22d are always kept constant, the air in the internal spaces 22a to 22d is
not compressed or expanded even if the diaphragms 31a to 31e move. When the volume of the
internal spaces 22a to 22d is large, it takes time for the movement of air generated near the
diaphragm to propagate to the entire internal space, so that pressure is transiently generated in
the internal spaces 22a to 22d. Unevenness occurs. Since the transient non-uniformity in
pressure can be suppressed if the volume of the internal spaces 22a to 22d is small, the
diaphragms 31a to 31e move without receiving the air resistance in the internal spaces 22a to
22d. Can. Here, instead of driving the diaphragms 31b and 31d with signals in reverse phase, the
speaker units 13b and 13d are fixed in the reverse direction to the speaker units 13a, 13c and
13e, and all the diaphragms 31a to 31e are in phase. It may drive by the signal of.
[0010]
The following equation holds for the lowest resonant frequency of the speaker. However, f0 is
the lowest resonant frequency. C is a constant. K0 is a spring constant. m0 represents an
equivalent mass.
[0011]
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In the case of a single speaker unit in which the front and rear of the diaphragm are open, the
following equation holds. However, m is an equivalent mass in a single speaker unit. K is a spring
constant at the driver portion. K 'represents a spring constant due to air resistance on each of the
front surface and the back surface of the diaphragm. Therefore, f1 represents the lowest
resonance frequency of the single speaker unit in which the front and back of the diaphragm are
open.
[0012]
On the other hand, in the case of the loudspeaker according to the present embodiment, the
equivalent mass is five times, and the spring constant at the driver portion is also five times. On
the other hand, since the air resistance occurs only on the surface of the diaphragm 31a and the
back surface of the diaphragm 31e, and the air resistance does not occur on the other surfaces,
the spring constant due to the air resistance does not change. Therefore, f5 represents the lowest
resonance frequency of the loudspeaker according to the present embodiment. From the above,
however, k = K / K '.
[0013]
For example, if f1 = 100 [Hz] and k = 1.27, then f5 = 71.5 [Hz], and the lowest resonance
frequency is significantly reduced.
[0014]
Thus, the internal space is finely divided to reduce the volume of each internal space, and a
diaphragm is provided at the boundary between the internal spaces to assist the movement of air
in the internal space. The lowest resonant frequency can be significantly reduced.
[0015]
Further, the reaction forces applied to the main body 12 by driving the diaphragms 31a to 31e
cancel each other except for one diaphragm.
Thereby, the vibration of the main body 12 can be suppressed and the characteristic of the
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speaker 10 can be improved.
[0016]
The air outside the main body 12 is vibrated by the surface of the diaphragm 31a and the back
surface of the diaphragm 31e.
Since the diaphragms 31a and 31e are separated, it is possible to prevent the sound generated
on the back side of the diaphragm 31e from turning around on the front side of the diaphragm
31a and canceling the sound generated by the diaphragm 31a. For this reason, it is not necessary
to enclose the back side of the diaphragm 31e.
[0017]
The number of speaker units is not limited to five, and may be three or more. If the number of
speaker units is an odd number, the two diaphragms exposed to the outside are exposed in
different directions, and there is no need to provide a configuration to prevent the sounds
generated by the two diaphragms from being canceled. When the number of speaker units is an
even number, two diaphragms exposed to the outside are exposed in the same direction, so for
example, a baffle plate is disposed between two diaphragms to isolate them, or the front side of
the last diaphragm is It is necessary to prevent the sounds generated by the two diaphragms
from being canceled, for example, by enclosing in an enclosure or the like.
[0018]
Assuming that the number of speaker units is n, however, fn represents the lowest resonance
frequency in the case of n speaker units. Therefore, as the number of speaker units increases, the
lowest resonance frequency decreases. However, since the number of speaker units increases,
the decrease rate of the lowest resonance frequency decreases.
[0019]
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The positional relationship between the speaker units is not limited to the above-described
arrangement, and may be another arrangement. For example, the speaker units may be arranged
vertically, or the speaker units may face in different directions. However, it is preferable to
arrange two diaphragms facing the same internal space as close as possible because the volume
of the internal space can be reduced. Further, it is preferable that the surfaces facing the same
internal space of the two diaphragms face in the same direction, because the reaction forces
generated when driving the two diaphragms cancel each other. For this reason, it is most
preferable to arrange two diaphragms facing the same inner space side by side adjacently.
Further, it is preferable to arrange the speaker units in a straight line, because the distance
between the two diaphragms exposed to the outside increases and the reaction force effectively
cancels out. In this case, the larger the number of speaker units, the larger the distance between
the two diaphragms exposed to the outside, which is preferable.
[0020]
A speaker 10B according to another embodiment includes a main body 12 and five speaker units
13a to 13e, as shown in FIGS. The speaker units 13a to 13e are the same as those of the speaker
10A, and the description thereof is omitted. Unlike the speaker 10A, the main body 12 has a
plate 23, eight lids 24b to 24e and 25a to 25d, and four tubes 26a to 26d. The plate 23 has a
substantially rectangular shape. The speaker units 13a to 13e are all identical, fixed to the holes
provided in the plate 23, and arranged in parallel and in a straight line. The lids 24 b to 24 e are
fixed to the front side of the plate 23. The lid 24 b encloses the front side of the speaker unit 13
b. The lid 24c encloses the front side of the speaker unit 13c. The lid 24d encloses the front side
of the speaker unit 13d. The lid 24e encloses the front side of the speaker unit 13e. The lids 25 a
to 25 d are fixed to the back side of the plate 23. The lid 25a encloses the back side of the
speaker unit 13a. The lid 25 b encloses the back side of the speaker unit 13 b. The lid 25c
encloses the back side of the speaker unit 13c. The lid 25d encloses the back side of the speaker
unit 13d. The tubes 26 a and 26 c are fixed to the back of the plate 23. The tubes 26 b and 26 d
are fixed to the front side of the plate 23. The tube 26a fluidly couples the space inside the lid
25a and the space inside the lid 25b. The plate 23, the lids 25a and 25b and the pipe 26a (space
defining portion) define one sealed internal space 22a (closed space). The tube 26 b fluidly
couples the space inside the lid 24 b and the space inside the lid 24 c. The plate 23, the lids 24b
and 24c and the tube 26b (space defining portion) define one sealed internal space 22b (closed
space). The tube 26c fluidly couples the space inside the lid 25c and the space inside the lid 25d.
The plate 23, the lids 25c and 25d and the pipe 26c (space defining portion) define one sealed
internal space 22c (closed space). The tube 26d fluidly couples the space inside the lid 24d and
the space inside the lid 24e. The plate 23, the lids 24d and 24e and the pipe 26d (space defining
portion) define one sealed internal space 22d (closed space).
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[0021]
The lids 24b to 24e and 25a to 25d have a gap between them and the speaker units 13a to 13e
so as not to disturb the movement of the diaphragms 31a to 31e, and the volume of the internal
spaces 22a to 22d is as small as possible. , And the shape following the shape of the speaker
units 13a to 13e. As a result, the volumes of the internal spaces 22a to 22d are significantly
reduced compared to the speaker 10A, so it is possible to further suppress transient pressure
unevenness. This further improves the bass characteristic.
[0022]
The speaker 10C in still another embodiment includes nine speaker units, as shown in FIG. The
nine speaker units are all identical, fixed to the main body, and arranged in parallel and in a
straight line. The main body is the same as that of the speaker 10A or 10B, and the description
will be omitted. The nine speaker units are divided into three groups. Three speaker units
belonging to each set are electrically connected in parallel to one another to form a parallel
circuit. Three parallel circuits configured by three speaker units are electrically connected in
series to one another to constitute a drive circuit.
[0023]
Assuming that the impedance of each speaker unit is Z, the combined impedance ZC of each
parallel circuit is Z / 3, and the combined impedance ZL of the entire drive circuit is 3ZC = Z. As
described above, if the number of speaker units is a square number, the combined impedance of
the entire drive circuit can be made equal to the impedance of the speaker units.
[0024]
In general, the impedance of the speaker unit is 4Ω or 8Ω, and an amplification circuit for
driving the speaker unit is designed to be impedance matched therewith. Since the combined
impedance of the entire drive circuit is equal to the impedance of one speaker unit, a general
amplification circuit can be used as it is. There is no need for a special circuit to match the
impedance, and although there are a large number of speaker units, only one amplifier circuit is
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required.
[0025]
The speaker 10D according to still another embodiment includes nine speaker units, as shown in
FIG. The nine speaker units are all identical, fixed to the main body, and arranged in parallel and
in a straight line. The main body is the same as that of the speaker 10A or 10B, and the
description will be omitted. The nine speaker units are divided into three groups. Three speaker
units belonging to each set are electrically connected in series to one another to form a series
circuit. Three series circuits constituted by three speaker units are electrically connected in
parallel to one another to constitute a drive circuit. Even with such a connection, the combined
impedance of the entire drive circuit can be made equal to the impedance of the speaker unit.
[0026]
The number of speaker units may not be a square number but a product of two or more integers
p and q. In that case, p parallel circuits in which q speaker units are connected in parallel may be
connected in series, or even if q serial circuits in which p speaker units are connected in series
are connected in parallel Good. The combined impedance of the entire drive circuit is p / q times
the impedance of the speaker unit. For example, when the impedance of the speaker unit is 4Ω
and the number of speaker units is eight, the combined impedance of the entire drive circuit can
be obtained by connecting four parallel circuits in which two speaker units are connected in
parallel. Becomes 8 Ω. Therefore, an amplifier circuit with an output impedance of 8Ω can be
used. If both p and q are odd, it is preferable because the number of speaker units is odd.
[0027]
The embodiment described above is an example for facilitating the understanding of the present
invention. The present invention is not limited thereto, and includes various modifications,
alterations, additions, or removals without departing from the scope defined by the appended
claims. This can be easily understood by those skilled in the art from the above description.
[0028]
10A to 10D speakers, 12 bodies, 13a to 13e speaker units, 21a to 21d boxes, 22a to 22d internal
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spaces, 23 plates, 24b to 24e, 25a to 25e lids, 26a to 26d tubes, 31a to 31e diaphragms.
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