JP2011050085

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DESCRIPTION JP2011050085
PROBLEM TO BE SOLVED: To provide a speaker capable of obtaining excellent acoustic
characteristics by allowing a vibration to be efficiently transmitted to a diaphragm and causing
the entire diaphragm to be sufficiently vibrated with a relatively simple configuration. A speaker
(21) for emitting a musical tone according to a musical tone signal (S), which differentiates
amplitude information of the musical tone signal (S) and converts it into speed information, a
diaphragm (2), and a diaphragm (2) In a state where a gap G2 is provided between the provided
mounting portion 22 and the diaphragm 2, it is attached to the diaphragm 2 via the mounting
portion 22 and in accordance with the speed information of the tone signal S from the
differentiation circuit 6. In a state where it vibrates and velocity information is converted into
acceleration information, the first acoustic transducer 3 which radiates the sound wave W to the
diaphragm 2 via the gap G2 to vibrate the diaphragm 2 and directly attached to the diaphragm 2
And a second vibrator 23 that vibrates according to the amplitude information of the musical
tone signal S and vibrates the diaphragm 2. [Selected figure] Figure 3
スピーカ
[0001]
The present invention relates to a speaker that is used for an independent speaker unit, an
electronic musical instrument, or the like and emits a musical tone.
[0002]
The applicant has proposed this type of speaker, for example, in Japanese Patent Application No.
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2004-163668 (Japanese Patent Laid-Open No. 2005-347964).
The speaker includes a diaphragm made of a wood single plate, and two electromagnetic
actuators (hereinafter referred to as "actuators") directly attached to the diaphragm. The actuator
is driven by inputting a tone signal generated by an electronic musical instrument or the like to
vibrate the diaphragm. As a result, a tone corresponding to the tone signal is emitted from the
diaphragm.
[0003]
JP 2005-347964 A
[0004]
However, the above-mentioned speaker has room for improvement in that the whole diaphragm
is vibrated efficiently and good acoustic characteristics are obtained.
That is, in this speaker, the diaphragm is vibrated by two actuators directly attached to the
diaphragm. As described above, since the vibration generated in a point shape by the actuator is
transmitted to the entire diaphragm, it is particularly difficult for the vibration to propagate to a
position far from the actuator, and the entire diaphragm is vibrated sufficiently. It is impossible
to obtain good acoustic characteristics. In particular, in the case where the diaphragm is made of
plywood or when the mass of the diaphragm is large, the acceleration vibration is hard to
propagate and tends to be insufficient, so that the above problem becomes remarkable. In
addition, since the actuator is directly attached to the diaphragm, the actuator can be attached to
the diaphragm in a state where the contact surface thereof is appropriately pressed against the
diaphragm in order to facilitate propagation of the vibration of the actuator to the diaphragm as
much as possible. It needs to be firmly attached, which complicates the mounting and adjustment
of the actuator. For the same reason, noise components may be mixed in during operation of the
actuator, which may adversely affect the acoustic characteristics.
[0005]
The present invention has been made to solve such a problem, and is relatively simple in
construction, efficiently propagates vibration to a diaphragm, and causes excellent vibration by
sufficiently vibrating the entire diaphragm. An object is to provide a speaker capable of obtaining
characteristics.
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[0006]
In order to achieve this object, the invention according to claim 1 is a speaker for emitting a
musical tone according to a musical tone signal representing amplitude information, which is
converted into velocity information by differentiating the amplitude information of the musical
tone signal. The musical tone input from the differentiation circuit, attached to the diaphragm
through the attachment section with a gap between the differentiation circuit, the diaphragm, the
attachment section provided on the diaphragm, and the diaphragm A first vibrator for vibrating a
diaphragm by radiating a sound wave to a diaphragm through a gap in a state of vibrating
according to velocity information of a signal and converting velocity information into
acceleration information, and a diaphragm And a second vibrator for directly vibrating the
diaphragm by vibrating according to the amplitude information of the musical tone signal
directly attached and input.
[0007]
In this speaker, the first vibrator is attached to the diaphragm via the attachment portion
provided on the diaphragm, and a gap, that is, an air layer is formed between the first vibrator
and the diaphragm.
In addition, the second vibrator is directly attached to the diaphragm.
[0008]
A musical tone signal representing the amplitude information is output to the differentiating
circuit and the second vibrator.
The second vibrator vibrates the diaphragm directly by vibrating according to the amplitude
information of the input musical tone signal. Further, the differentiating circuit differentiates the
amplitude information of the musical tone signal to convert into speed information, and then
outputs the speed information to the first amplitude element. The first amplitude element
vibrates according to the speed information of the inputted musical tone signal, and in a state
where this speed information is converted into acceleration information, the diaphragm is
released by radiating a sound wave to the diaphragm through the gap. Vibrate.
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[0009]
As described above, a sound wave representing acceleration information of a musical tone signal
is propagated from the first vibrator to the diaphragm with a planar spread via the air layer
formed between the first vibrator and the diaphragm. Therefore, the acceleration vibration is
efficiently given to the diaphragm. Further, in addition to the first vibrator, the second vibrator
for directly vibrating the diaphragm according to the vibration information of the musical tone
signal is used in combination, so that both the first and second vibrators can be used. The
diaphragm can be sufficiently vibrated to a position far from the vibrator. As a result of the
above, the entire diaphragm can be vibrated sufficiently, and excellent acoustic characteristics
can be obtained.
[0010]
The invention according to claim 2 is characterized in that, in the speaker according to claim 1,
the mounting portion is made of metal.
[0011]
It is a perspective view of the speaker by a 1st embodiment of the present invention.
It is the elements on larger scale of the speaker of FIG. It is a perspective view of the speaker by a
2nd embodiment of the present invention. It is the elements on larger scale of the speaker of FIG.
FIG. 6 is a diagram showing frequency characteristics of the diaphragm in the vicinity of the
actuator when both the metal plate and the actuator provided to the diaphragm are driven in the
speaker of FIG. 3. FIG. 6 is a diagram showing frequency characteristics of a diaphragm in the
vicinity of the actuator when only the actuator provided on the metal plate is driven in the
speaker of FIG. 3. FIG. 6 is a diagram showing frequency characteristics of the diaphragm in the
vicinity of the actuator when only the actuator provided on the diaphragm is driven in the
speaker of FIG. 3. FIG. 6 is a diagram showing frequency characteristics of the diaphragm at a
position far from the actuator when both the metal plate and the actuator provided to the
diaphragm are driven in the speaker of FIG. 3. FIG. 6 is a diagram showing frequency
characteristics of the diaphragm at a position far from the actuator when only the actuator
provided on the metal plate is driven in the speaker of FIG. 3. FIG. 6 is a diagram showing
frequency characteristics of the diaphragm at a position far from the actuator when only the
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actuator provided on the diaphragm is driven in the speaker of FIG. 3.
[0012]
Hereinafter, preferred embodiments of the present invention will be described in detail with
reference to the drawings. 1 and 2 show a loudspeaker 1 according to a first embodiment of the
invention. The speaker 1 is assembled as a speaker unit (not shown), and the speaker unit is
incorporated in or connected to an electronic musical instrument or an audio device, and used
independently.
[0013]
As shown in FIG. 1, the speaker 1 includes a diaphragm 2, two electromagnetic actuators
(hereinafter referred to as actuators ) 3, 3 (vibrators) that vibrate the diaphragm 2, and the
diaphragm 2 with each actuator 3. And two power amplifiers 5, 5 and two differential circuits 6,
6 and the like.
[0014]
The diaphragm 2 is formed of, for example, a veneer of natural wood such as Sitka spruce or
spruce or a wood board such as plywood, and is formed in a rectangular shape.
Further, in the diaphragm 2, two front and rear bolt holes 7 (see FIG. 2) are respectively formed
at two positions separated by predetermined distances from both ends in the length direction.
[0015]
The actuator 3 is, for example, an electromagnetic actuator used for a loudspeaker, and as shown
in FIG. 2, a support plate 8, a ferrite magnet 9 attached to and supported by the lower surface of
the support plate 8, and a ferrite magnet A plurality of electromagnetic coils 10 (only two are
shown) provided opposite to the left and right of 9 and a diaphragm 11 connected to these
electromagnetic coils 10 and covering the ferrite magnet 9 from the lower side, a ferrite magnet
9 and a diaphragm A plurality of dampers 12 (only two of which are shown) or the like provided
between them 11 and the like. The electromagnetic coil 10 is driven by being excited according
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to the musical tone signal S outputted from the musical tone reproduction device 16 such as an
electronic musical instrument or an audio device, and the vibration of the electromagnetic coil 10
is transmitted to the diaphragm 11. The diaphragm 11 vibrates. At the end of the support plate
8, two bolt holes 8a and 8a are formed.
[0016]
The mounting bolt 4 is passed from below to the bolt hole 7 of the diaphragm 2 and is fixed to
the diaphragm 2 by tightening a nut 14 screwed to the mounting bolt 4 against the upper
surface of the diaphragm 2 . Between the head of the mounting bolt 4 and the lower surface of
the diaphragm 2 and between the nut 14 and the upper surface of the diaphragm 2, a vibrationproof material 13 made of hard rubber or the like is interposed. Further, the upper end portion
of the mounting bolt 4 is passed through the bolt hole 8 a of the support plate 8, and the upper
and lower two nuts 15 and 15 screwed to the support plate 8 sandwich the support plate 8.
Thereby, the actuator 3 is attached to the diaphragm 2 via the mounting bolt 4, and a gap G 1
(air layer) is formed between the diaphragm 2 and the actuator 3.
[0017]
The power amplifier 5 amplifies the musical tone signal S representing the amplitude information
output from the musical tone reproduction device 16 with a predetermined gain, and outputs the
amplified musical tone signal S to the differentiating circuit 6. The differentiating circuit 6
differentiates the amplified musical tone signal S to convert the amplitude information of the
musical tone signal S into velocity information, and then outputs the velocity information to the
actuator 3. The actuator 3 vibrates in response to the input musical tone signal S, and emits a
sound wave W from the diaphragm 11 to the air layer.
[0018]
The sound wave W is emitted from the actuator 3 in a state where the speed information of the
tone signal S is converted into acceleration information for the following reason. The following
equations (1) and (2) respectively represent the sound pressure P and the particle velocity V at
the position of the distance r from the actuator 3 when an acoustic wave is emitted from the
actuator 3 into air.
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[0019]
Here, k is the wave number, ρ is a scalar component of the acoustic impedance, c is the velocity
of sound, and A is the volume velocity. Therefore, the acoustic impedance (= P / V) Z at this time
is given by the following equation (3). Further, the wave number k is represented by the angular
frequency ω / sound speed c, and the complex number jω of the angular frequency is replaced
with the Laplace operator s, and then expanded, the acoustic impedance Z is expressed as
Expression (4). That is, it can be represented by an incomplete derivative having a pole at the
sound velocity c / distance r.
[0020]
As described above, after the tone signal S representing the amplitude information is
differentiated by the differentiating circuit 6, the sound wave W representing the acceleration
information obtained by differentiating the tone signal S twice from the actuator 3 is the gap G1
by outputting to the actuator 3. It is radiated to the diaphragm 2 through the air layer.
[0021]
As described above, according to the present embodiment, the acoustic wave W corresponding to
the musical tone signal S is spread from the actuator 3 to the diaphragm 2 through the air layer
formed between the actuator 3 and the diaphragm 2. Since the propagation is performed with
the spread, the vibration is efficiently given to the diaphragm 2 and efficiently and sufficiently
propagated to the whole diaphragm 2.
As a result, the entire diaphragm 2 can be vibrated sufficiently, and excellent acoustic
characteristics can be obtained.
[0022]
Further, by differentiating the tone signal S by the differentiating circuit 6 and further
differentiating the tone signal S by the radiation of the sound wave W from the actuator 3, it is
possible to efficiently and sufficiently give the acceleration vibration to the entire diaphragm 2.
[0023]
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Furthermore, since the relatively inexpensive electromagnetic actuator used for the loudspeaker
is used as the actuator 3, the loudspeaker 1 can be configured inexpensively.
Further, since the diaphragm 2 is vibrated through the air layer, attachment and adjustment of
the actuator 3 to the diaphragm 2 become easy, and the configuration of the speaker 1 can be
simplified. For the same reason, mixing of noise components can be prevented.
[0024]
3 and 4 show a loudspeaker 21 according to a second embodiment of the present invention. In
the following description, the same components as those in the first embodiment described
above are denoted by the same reference numerals, and detailed description thereof will be
omitted. As shown in FIG. 3, the speaker 21 includes a diaphragm 2, two metal plates 22 and 22
attached to the diaphragm 2, and a first actuator 3 attached to each metal plate 22 (only one is
shown) And the second actuator 23 attached to the diaphragm 2 and the like. At each end in the
width direction of the diaphragm 2, five bolt holes 24 (only one is shown in FIG. 4) are formed at
intervals in the length direction.
[0025]
The metal plate 22 is formed of an elongated angle member made of metal (for example, steel),
and extends over the entire length of the diaphragm 2. As shown in FIGS. 3 and 4, the metal plate
22 has an L-shaped cross-sectional shape, and is constituted by a main body 22a and a rising
portion 22b which perpendicularly rises from the main body 22a upward. Five bolt holes 25
(only one is shown in FIG. 4) are formed in the main body 22 a at positions corresponding to the
bolt holes 24 of the diaphragm 2. The metal plate 22 is fixed to the diaphragm 2 by the bolts 26
and nuts 14 which are passed from the lower side to the bolt holes 24 and 25 of the main body
22 a of the diaphragm 2 and the metal plate 22.
[0026]
The first actuator 3 is for giving acceleration information of the musical tone signal S, and is
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disposed at a predetermined distance away from one end of each metal plate 22. As shown in
FIG. 4, the first actuator 3 is mounted on the rising portion 22b and the main portion 22a of the
metal plate 22 at the upper end and the lower end of the support plate 8 through the mounting
brackets 27 and 27 having an L-shaped cross section It is fixed. Thus, a gap G2 is formed
between the diaphragm 11 of the first actuator 3 and the metal plate 22. The first actuator 3 is
connected to the tone reproduction device 16 via the power amplifier 5 and the differentiation
circuit 6.
[0027]
The second actuator 23 is for giving amplitude information of the tone signal S, is configured in
the same manner as the first actuator 3, and is directly attached to the upper surface of the
diaphragm 2. As shown in FIG. 3, the second actuator 23 is disposed at the same distance from
the one end of the diaphragm 2 as the first actuator 3. The second actuator 23 is connected to
the tone reproduction device 16 only via the power amplifier 5.
[0028]
With the above configuration, the tone signal S representing the amplitude information output
from the tone reproduction device 16 is amplified to a predetermined gain by the power
amplifier 5 and then output to the second actuator 23 and the differentiating circuit 6. The
second actuator 23 vibrates in response to the input musical tone signal S, and vibrates the
diaphragm 2 directly by the vibration. Further, the differentiating circuit 6 differentiates the
inputted musical tone signal S and outputs it to the first actuator 3. Thereby, from the first
actuator 3, a sound wave W representing acceleration information obtained by differentiating the
musical tone signal S twice is radiated to the metal plate 22 through the gap G2. The metal plate
22 is vibrated by the emitted sound wave W, and the vibration propagates along the length
direction of the metal plate 22 (arrow A) and spreads over the entire metal plate 22. Thus, the
vibration spread over the entire metal plate 22 is further transmitted to the diaphragm 2 from
the main body 22a in surface contact with the diaphragm 2 (arrow B).
[0029]
Further, assuming that the mechanical impedance of the metal plate 22 is Zm and the mechanical
impedance of the diaphragm 2 is Zo, these mechanical impedances Zm and Zo are respectively
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calculated by dividing the pressure P by the particle velocity V (= P / V) Be done. Further, since
the pressure P and the particle velocity V depend on the elastic modulus of the metal plate 22
and the diaphragm 2, the mechanical impedance Zm of the metal plate 22 and the mechanical
impedance Zo of the diaphragm 2 have different characteristics from each other. There is. For
this reason, at the interface where the main body 22a of the metal plate 22 is in surface contact
with the diaphragm 2, the vibration from the first actuator 3 is transmitted to the diaphragm 2
while causing phenomena such as reflection, transmission and bending. Thus, acceleration
vibration can be efficiently and sufficiently applied to the diaphragm 2.
[0030]
5 to 7 show the measurement results of the frequency characteristics of the diaphragm 2 at
positions near the first and second actuators 3 and 23 (hereinafter referred to as "nearby
positions"), and FIGS. 2 shows the measurement results of the frequency characteristics of the
diaphragm 2 at positions far from the actuators 3 and 23 (hereinafter referred to as far
position ). Also, among these figures, FIGS. 5 and 8 show that when both the first and second
actuators 3 and 23 are driven, and FIGS. 6 and 9 show that when only the first actuator 3 is
driven, FIGS. And FIG. 10 shows the one when only the second actuator 23 is driven.
[0031]
As apparent from these figures, the case where both the first and second actuators 3 and 23 are
driven (FIGS. 5 and 8) and the case where only the first actuator 3 is driven (FIGS. 6 and 9) are
compared. Then, in the higher frequency band, that is, the band with many acceleration
components, the same sound pressure level is obtained at both the near position and the far
position. On the other hand, when only the second actuator 23 is driven (FIGS. 7 and 10), the
sound pressure level is greatly attenuated in both the near position and the far position in the
region where the acceleration component is large.
[0032]
Also, when the frequency characteristics of the near position and the far position when both of
the first and second actuators 3 and 23 are driven are compared (FIGS. 5 and 8), the sound
pressure level of the band with many acceleration components at the far position. Is slightly
attenuated. The same applies to the case where only the first actuator 3 is driven (FIGS. 6 and 9).
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On the other hand, when only the second actuator 23 is driven, the sound pressure level in the
band where the acceleration component is large is greatly attenuated at the distant position
(FIGS. 7 and 10).
[0033]
From the above results, by using the first and second actuators 3 and 23 in combination, the
diaphragm 2 can be positioned far from the first and second actuators 3 and 23 as well as near
the first and second actuators 3 and 23. Was confirmed to be able to vibrate enough.
[0034]
As described above, according to the present embodiment, the rising portion 22 b is easily
vibrated by the vibration of the first actuator 3, and the vibration is propagated along the length
direction of the metal plate 22.
Further, since the main body 22a is attached to the diaphragm 22 in a surface contact state, the
vibration transmitted from the rising portion 22b is efficiently transmitted to the diaphragm 2
with a linear spread from the contact surface with the main body 22a. be able to. As a result, the
vibration can be efficiently transmitted to the entire diaphragm 2, the entire diaphragm 2 can be
sufficiently vibrated, and excellent acoustic characteristics can be obtained. Further, since the
acceleration information is given to the metal plate 22 by the first actuator 3, the acceleration
vibration can be efficiently and sufficiently given to the diaphragm 2.
[0035]
Further, since the metal plate 22 only needs to be added between the diaphragm 2 and the first
actuator 3, the speaker 21 can be realized with a relatively simple configuration. Furthermore, by
using the first and second actuators 3, 23 in combination, the diaphragm 2 can be located not
only near the first and second actuators 3, 23 but also at a position far from the first and second
actuators 3, 23. It can be vibrated sufficiently and superior acoustic characteristics can be
obtained.
[0036]
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In addition, this invention can be implemented in various aspects, without being limited to the
described embodiment. For example, although the differentiating circuit 6 is provided between
the power amplifier 5 and the actuator 3 in the embodiment, it may be provided between the
tone reproduction device 16 and the power amplifier 5. In the embodiment, although the
diaphragm 2 is made of wood, the present invention is not limited to this. For example, the
diaphragm 2 may be made of acrylic or another metal having mechanical impedance
characteristics different from the metal plate 22. Furthermore, in the second embodiment, the
first actuator 3 is attached so as to straddle the main body portion 22a and the rising portion
22b of the metal plate 22, but may be attached only to the rising portion 22b. Further, in the
second embodiment, the first actuator 3 is attached to each of the metal plates 22 and the second
actuator 23 is attached to the diaphragm 2 one by one. However, the number is not limited to
this. In addition, it is possible to change suitably the details within the scope of the meaning of
the present invention.
[0037]
DESCRIPTION OF SYMBOLS 2 diaphragm 3 1st actuator (1st vibrator ¦ oscillator) 6
differentiation circuit 21 Speaker 22 metal plate (attachment part) 23 2nd actuator (2nd vibrator
¦ oscillator) G2 gap S musical-tone signal W sound wave
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